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Sample records for extra negative feedback

  1. Positive feedback promotes oscillations in negative feedback loops.

    Directory of Open Access Journals (Sweden)

    Bharath Ananthasubramaniam

    Full Text Available A simple three-component negative feedback loop is a recurring motif in biochemical oscillators. This motif oscillates as it has the three necessary ingredients for oscillations: a three-step delay, negative feedback, and nonlinearity in the loop. However, to oscillate, this motif under the common Goodwin formulation requires a high degree of cooperativity (a measure of nonlinearity in the feedback that is biologically "unlikely." Moreover, this recurring negative feedback motif is commonly observed augmented by positive feedback interactions. Here we show that these positive feedback interactions promote oscillation at lower degrees of cooperativity, and we can thus unify several common kinetic mechanisms that facilitate oscillations, such as self-activation and Michaelis-Menten degradation. The positive feedback loops are most beneficial when acting on the shortest lived component, where they function by balancing the lifetimes of the different components. The benefits of multiple positive feedback interactions are cumulative for a majority of situations considered, when benefits are measured by the reduction in the cooperativity required to oscillate. These positive feedback motifs also allow oscillations with longer periods than that determined by the lifetimes of the components alone. We can therefore conjecture that these positive feedback loops have evolved to facilitate oscillations at lower, kinetically achievable, degrees of cooperativity. Finally, we discuss the implications of our conclusions on the mammalian molecular clock, a system modeled extensively based on the three-component negative feedback loop.

  2. Enhanced Negative Feedback Responses in Remitted Depression

    OpenAIRE

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

    2008-01-01

    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 pun...

  3. Enhanced Negative Feedback Responses in Remitted Depression

    Science.gov (United States)

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

    2011-01-01

    Major depressive disorder (MDD) is characterized by hypersensitivity to negative feedback that might involve frontocingulate dysfunction. MDD subjects exhibit enhanced electrophysiological responses to negative internal (errors) and external (feedback) cues. Whether this dysfunction extends to remitted depressed (RD) subjects with a history of MDD is currently unknown. To address this issue, we examined the feedback-related negativity (FRN) in RD and control subjects using a probabilistic punishment learning task. Despite equivalent behavioral performance, RD subjects showed larger FRNs 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. PMID:18580576

  4. Anomalous feedback and negative domain wall resistance

    Science.gov (United States)

    Cheng, Ran; Zhu, Jian-Gang; Xiao, Di

    2016-11-01

    Magnetic induction can be regarded as a negative feedback effect, where the motive-force opposes the change of magnetic flux that generates the motive-force. In artificial electromagnetics emerging from spintronics, however, this is not necessarily the case. By studying the current-induced domain wall dynamics in a cylindrical nanowire, we show that the spin motive-force exerting on electrons can either oppose or support the applied current that drives the domain wall. The switching into the anomalous feedback regime occurs when the strength of the dissipative torque β is about twice the value of the Gilbert damping constant α. The anomalous feedback manifests as a negative domain wall resistance, which has an analogy with the water turbine.

  5. Transversality for Cyclic Negative Feedback Systems

    OpenAIRE

    2014-01-01

    Transversality of stable and unstable manifolds of hyperbolic periodic trajectories is proved for monotone cyclic systems with negative feedback. Such systems in general are not in the category of monotone dynamical systems in the sense of Hirsch. Our main tool utilized in the proofs is the so-called cone of high rank. We further show that stable and unstable manifolds between a hyperbolic equilibrium and a hyperbolic periodic trajectory, or between two hyperbolic equilibria with different di...

  6. Negative feedback effects on star formation history and cosmic reionization

    CERN Document Server

    Wang, Lei; Xiang, Shouping; Yuan, Ye-Fei

    2008-01-01

    After considering the effects of negative feedback on the process of star formation, we explore the relationship between star formation process and the associated feedback, by investigating how the mechanical feedback from supernovae(SNe) and radiative feedback from luminous objects regulate the star formation rate and therefore affect the cosmic reionization.Based on our present knowledge of the negative feedback theory and some numerical simulations, we construct an analytic model in the framework of the Lambda cold dark matter model. In certain parameter regions, our model can explain some observational results properly. In large halos(T_vir>10000 K), both mechanical and radiative feedback have a similar behavior: the relative strength of negative feedback reduces as the redshift decreases. In contrast, in small halos (T_vir<10000 K$) that are thought to breed the first stars at early time, the radiative feedback gets stronger when the redshift decreases. And the star formation rate in these small halos...

  7. Stress reduces use of negative feedback in a feedback-based learning task.

    Science.gov (United States)

    Petzold, Antje; Plessow, Franziska; Goschke, Thomas; Kirschbaum, Clemens

    2010-04-01

    In contrast to the well-established effects of stress on learning of declarative material, much less is known about stress effects on reward- or feedback-based learning. Differential effects on positive and negative feedback especially have received little attention. The objective of this study, thus, was to investigate effects of psychosocial stress on feedback-based learning with a particular focus on the use of negative and positive feedback during learning. Participants completed a probabilistic selection task in both a stress and a control condition. The task allowed quantification of how much participants relied on positive and negative feedback during learning. Although stress had no effect on general acquisition of the task, results indicate that participants used negative feedback significantly less during learning after stress compared with the control condition. An enhancing effect of stress on use of positive feedback failed to reach significance. These findings suggest that stress acts differentially on the use of positive and negative feedback during learning.

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

    OpenAIRE

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

    2011-01-01

    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 underlyi...

  9. Effects of Informative and Confirmatory Feedback on Brain Activation During Negative Feedback Processing

    Directory of Open Access Journals (Sweden)

    Yeon-Kyoung eWoo

    2015-06-01

    Full Text Available The current study compared the effects of informative and confirmatory feedback on brain activation during negative feedback processing. For confirmatory feedback trials, participants were informed that they had failed the task, whereas informative feedback trials presented task relevant information along with the notification of their failure. Fourteen male undergraduates performed a series of spatial-perceptual tasks and received feedback while their brain activity was recorded. During confirmatory feedback trials, greater activations in the amygdala, dorsal anterior cingulate cortex, and the thalamus (including the habenular were observed in response to incorrect responses. These results suggest that confirmatory feedback induces negative emotional reactions to failure. In contrast, informative feedback trials elicited greater activity in the dorsolateral prefrontal cortex (DLPFC when participants experienced failure. Further psychophysiological interaction (PPI analysis revealed a negative coupling between the DLPFC and the amygdala during informative feedback relative to confirmatory feedback trials. These findings suggest that providing task-relevant information could facilitate implicit down-regulation of negative emotions following failure.

  10. Negative feedbacks in the economy and industrial location

    NARCIS (Netherlands)

    Brakman, S; Garretsen, H; Gigengack, R; vanMarrewijk, C; Wagenvoort, R

    1996-01-01

    Incorporating regional asymmetry and negative feedbacks (congestion) in a model of economic geography and international trade shows that complete specialization of production at one location is unlikely. We identify an agglomerating force: the home market effect, and two spreading forces,

  11. Seeing ghosts: negative body evaluation predicts overestimation of negative social feedback.

    Science.gov (United States)

    Alleva, Jessica M; Lange, Wolf-Gero; Jansen, Anita; Martijn, Carolien

    2014-06-01

    The current study investigated whether negative body evaluation predicts women's overestimation of negative social feedback related to their own body (i.e., covariation bias). Sixty-five female university students completed a computer task where photos of their own body, of a control woman's body, and of a neutral object, were followed by nonverbal social feedback (i.e., facial crowds with equal numbers of negative, positive, and neutral faces). Afterward, women estimated the percentage of negative, positive, and neutral social feedback that followed their own body, the control woman's body, and the neutral object. The findings provided evidence for a covariation bias: negative body evaluation predicted higher estimates of negative social feedback for women's own body, but not for the other stimuli. Additionally, the covariation bias was not explained by differences in how women interpreted the social feedback (the facial stimuli). Clinical implications of the covariation bias to body image are discussed.

  12. A Biopsychosocial Model Based on Negative Feedback and Control

    Directory of Open Access Journals (Sweden)

    Timothy Andrew Carey

    2014-02-01

    Full Text Available Although the biopsychosocial model has been a popular topic of discussion for over four decades it has not had the traction in fields of research that might be expected of such an intuitively appealing idea. One reason for this might be the absence of an identified mechanism or a functional architecture that is authentically biopsychosocial. What is needed is a robust mechanism that is equally important to biochemical processes as it is to psychological and social processes. Negative feedback may be the mechanism that is required. Negative feedback has been implicated in the regulation of neurotransmitters as well as important psychological and social processes such as emotional regulation and the relationship between a psychotherapist and a client. Moreover, negative feedback is purported to also govern the activity of all other organisms as well as humans. Perceptual Control Theory (PCT describes the way in which negative feedback establishes control at increasing levels of perceptual complexity. Thus, PCT may be the first biopsychosocial model to be articulated in functional terms. In this paper we outline the working model of PCT and explain how PCT provides an embodied hierarchical neural architecture that utilises negative feedback to control physiological, psychological, and social variables. PCT has major implications for both research and practice and, importantly, provides a guide by which fields of research that are currently separated may be integrated to bring about substantial progress in understanding the way in which the brain alters, and is altered by, its behavioural and environmental context.

  13. Negative Feedback, Linearity and Parameter Invariance in Linear Electronics

    CERN Document Server

    Costa, Luciano da F; Comin, Cesar H

    2016-01-01

    Negative feedback is a powerful approach capable of improving several aspects of a system. In linear electronics, it has been critical for allowing invariance to device properties. Negative feedback is also known to enhance linearity in amplification, which is one of the most important foundations of linear electronics. At the same time, thousands of transistors types have been made available, suggesting that these devices, in addition to their known variability of parameters, have distinguishing properties. The current work reports a systematic approach to quantifying the potential of negative feedback, with respect to bipolar transistors, as a means to providing device invariance and linearity. Several methods, including concepts from multivariate statistics and complex systems, are applied at the theoretical as well as experimental levels, and a number of interesting results are obtained and discussed. For instance, it has been verified that the transistors types indeed have well-defined characteristics wh...

  14. Feedback-induced glutamate spillover enhances negative feedback from horizontal cells to cones

    NARCIS (Netherlands)

    Vroman, Rozan; Kamermans, M.

    2015-01-01

    KEY POINTS: In the retina, horizontal cells feed back negatively to cone photoreceptors. Glutamate released from cones can spill over to neighbouring cones. Here we show that cone glutamate release induced by negative feedback can also spill over to neighbouring cones. This glutamate activates the g

  15. Impact of negative feedback in metabolic noise propagation.

    Science.gov (United States)

    Borri, Alessandro; Palumbo, Pasquale; Singh, Abhyudai

    2016-10-01

    Synthetic biology combines different branches of biology and engineering aimed at designing synthetic biological circuits able to replicate emergent properties useful for the biotechnology industry, human health and environment. The role of negative feedback in noise propagation for a basic enzymatic reaction scheme is investigated. Two feedback control schemes on enzyme expression are considered: one from the final product of the pathway activity, the other from the enzyme accumulation. Both schemes are designed to provide the same steady-state average values of the involved players, in order to evaluate the feedback performances according to the same working mode. Computations are carried out numerically and analytically, the latter allowing to infer information on which model parameter setting leads to a more efficient noise attenuation, according to the chosen scheme. In addition to highlighting the role of the feedback in providing a substantial noise reduction, our investigation concludes that the effect of feedback is enhanced by increasing the promoter sensitivity for both schemes. A further interesting biological insight is that an increase in the promoter sensitivity provides more benefits to the feedback from the product with respect to the feedback from the enzyme, in terms of enlarging the parameter design space.

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

    Science.gov (United States)

    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

  17. Seeing ghosts: Negative body evaluation predicts overestimation of negative social feedback

    NARCIS (Netherlands)

    Alleva, J.M.; Lange, W.G.; Jansen, A.T.M.; Martijn, C.

    2014-01-01

    The current study investigated whether negative body evaluation predicts women's overestimation of negative social feedback related to their own body (i.e., covariation bias). Sixty-five female university students completed a computer task where photos of their own body, of a control woman's body, a

  18. Seeing ghosts: Negative body evaluation predicts overestimation of negative social feedback

    NARCIS (Netherlands)

    Alleva, J.M.; Lange, W.G.; Jansen, A.T.M.; Martijn, C.

    2014-01-01

    The current study investigated whether negative body evaluation predicts women's overestimation of negative social feedback related to their own body (i.e., covariation bias). Sixty-five female university students completed a computer task where photos of their own body, of a control woman's body, a

  19. Seeing ghosts: Negative body evaluation predicts overestimation of negative social feedback

    NARCIS (Netherlands)

    Alleva, J.M.; Lange, W.G.; Jansen, A.T.M.; Martijn, C.

    2014-01-01

    The current study investigated whether negative body evaluation predicts women's overestimation of negative social feedback related to their own body (i.e., covariation bias). Sixty-five female university students completed a computer task where photos of their own body, of a control woman's body,

  20. Negative Avalanche Feedback Detectors for Photon-Counting Optical Communications

    Science.gov (United States)

    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.

  1. Negative Avalanche Feedback Detectors for Photon-Counting Optical Communications

    Science.gov (United States)

    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.

  2. Controlling a negative loaded hydraulic cylinder using pressure feedback

    DEFF Research Database (Denmark)

    Hansen, M.R.; Andersen, T.O.

    2010-01-01

    the high pass filtered pressure gradient equal tozero is introduced. It yields lead compensation with a markedly improved performance. The sizing of the filter is described taking into account the bandwidth of the directional control valve. The suggested control scheme is implemented and examined......This paper is concerned with the inherent oscillatory nature of pressure compensated velocity control of a hydraulic cylinder subjected to a negative load and suspended by means of an over-center valve. Initially, a linearized stability analysis of such a hydraulic circuit is carried out clearly...... showing that without extra measures such a system will be unstable in a substantial part of the cylinder stroke. The stability criterion is expressed in hard quantities: Cylinder volumes, cylinder area ratio and overcenter valve pilot area ratio. A pressure feed back scheme that has as target to maintain...

  3. Noise Control in Gene Regulatory Networks with Negative Feedback.

    Science.gov (United States)

    Hinczewski, Michael; Thirumalai, D

    2016-07-01

    Genes and proteins regulate cellular functions through complex circuits of biochemical reactions. Fluctuations in the components of these regulatory networks result in noise that invariably corrupts the signal, possibly compromising function. Here, we create a practical formalism based on ideas introduced by Wiener and Kolmogorov (WK) for filtering noise in engineered communications systems to quantitatively assess the extent to which noise can be controlled in biological processes involving negative feedback. Application of the theory, which reproduces the previously proven scaling of the lower bound for noise suppression in terms of the number of signaling events, shows that a tetracycline repressor-based negative-regulatory gene circuit behaves as a WK filter. For the class of Hill-like nonlinear regulatory functions, this type of filter provides the optimal reduction in noise. Our theoretical approach can be readily combined with experimental measurements of response functions in a wide variety of genetic circuits, to elucidate the general principles by which biological networks minimize noise.

  4. Oscillator frequency stability improvement by means of negative feedback.

    Science.gov (United States)

    Goryachev, Maxim; Galliou, Serge; Abbé, Philippe; Komine, Vadim

    2011-11-01

    A novel, simple method is proposed to increase the frequency stability of an oscillator. An additional negative feedback is used in combination with the positive loop of the harmonic oscillator to decrease the phase sensitivity to fluctuations of parameters other than the resonator. The main advantage of the proposed correction approach is that it does not require expensive external elements such as mixers or resonators. The validity of the method is theoretically demonstrated on a Colpitts oscillator using the control system theory approach and numerical simulations, and is experimentally verified with phase noise measurements of an actual oscillator-mockup. It is shown that the medium-term frequency stability can be easily improved by a factor of ten.

  5. Negative plant soil feedback explaining ring formation in clonal plants.

    Science.gov (United States)

    Cartenì, Fabrizio; Marasco, Addolorata; Bonanomi, Giuliano; Mazzoleni, Stefano; Rietkerk, Max; Giannino, Francesco

    2012-11-21

    Ring shaped patches of clonal plants have been reported in different environments, but the mechanisms underlying such pattern formation are still poorly explained. Water depletion in the inner tussocks zone has been proposed as a possible cause, although ring patterns have been also observed in ecosystems without limiting water conditions. In this work, a spatially explicit model is presented in order to investigate the role of negative plant-soil feedback as an additional explanation for ring formation. The model describes the dynamics of the plant biomass in the presence of toxicity produced by the decomposition of accumulated litter in the soil. Our model qualitatively reproduces the emergence of ring patterns of a single clonal plant species during colonisation of a bare substrate. The model admits two homogeneous stationary solutions representing bare soil and uniform vegetation cover which depend only on the ratio between the biomass death and growth rates. Moreover, differently from other plant spatial patterns models, but in agreement with real field observations of vegetation dynamics, we demonstrated that the pattern dynamics always lead to spatially homogeneous vegetation covers without creation of stable Turing patterns. Analytical results show that ring formation is a function of two main components, the plant specific susceptibility to toxic compounds released in the soil by the accumulated litter and the decay rate of these same compounds, depending on environmental conditions. These components act at the same time and their respective intensities can give rise to the different ring structures observed in nature, ranging from slight reductions of biomass in patch centres, to the appearance of marked rings with bare inner zones, as well as the occurrence of ephemeral waves of plant cover. Our results highlight the potential role of plant-soil negative feedback depending on decomposition processes for the development of transient vegetation patterns.

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

    Science.gov (United States)

    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.

  7. Age-related changes in deterministic learning from positive versus negative performance feedback

    NARCIS (Netherlands)

    van de Vijver, I.; Ridderinkhof, K.R.; de Wit, S.

    2015-01-01

    Feedback-based learning declines with age. Because older adults are generally biased toward positive information ("positivity effect"), learning from positive feedback may be less impaired than learning from negative outcomes. The literature documents mixed results, due possibly to variability

  8. From Positivity to Negativity Bias: Ambiguity Affects the Neurophysiological Signatures of Feedback Processing.

    Science.gov (United States)

    Gibbons, Henning; Schnuerch, Robert; Stahl, Jutta

    2016-04-01

    Previous studies on the neurophysiological underpinnings of feedback processing almost exclusively used low-ambiguity feedback, which does not fully address the diversity of situations in everyday life. We therefore used a pseudo trial-and-error learning task to investigate ERPs of low- versus high-ambiguity feedback. Twenty-eight participants tried to deduce the rule governing visual feedback to their button presses in response to visual stimuli. In the blocked condition, the same two feedback words were presented across several consecutive trials, whereas in the random condition feedback was randomly drawn on each trial from sets of five positive and five negative words. The feedback-related negativity (FRN-D), a frontocentral ERP difference between negative and positive feedback, was significantly larger in the blocked condition, whereas the centroparietal late positive complex indicating controlled attention was enhanced for negative feedback irrespective of condition. Moreover, FRN-D in the blocked condition was due to increased reward positivity (Rew-P) for positive feedback, rather than increased (raw) FRN for negative feedback. Our findings strongly support recent lines of evidence that the FRN-D, one of the most widely studied signatures of reinforcement learning in the human brain, critically depends on feedback discriminability and is primarily driven by the Rew-P. A novel finding concerned larger frontocentral P2 for negative feedback in the random but not the blocked condition. Although Rew-P points to a positivity bias in feedback processing under conditions of low feedback ambiguity, P2 suggests a specific adaptation of information processing in case of highly ambiguous feedback, involving an early negativity bias. Generalizability of the P2 findings was demonstrated in a second experiment using explicit valence categorization of highly emotional positive and negative adjectives.

  9. Career Goal Revision in Response to Negative Feedback: Testing a Longitudinal Cross-Lagged Model.

    Science.gov (United States)

    Hu, Shi; Creed, Peter A; Hood, Michelle

    2017-02-06

    We tested a model based on goal-setting and self-regulation theories of the cross-lagged relationships among negative career-related feedback, negative affect (career-related stress), and career goal revision (downward goal revision and goal disengagement). Participants were 409 Chinese university/college students (Mage 19 years; 58% female), who completed a survey at 2 time points approximately 6 months apart. Consistent with our hypotheses, negative career-related feedback at T1 was related to more career goal disengagement and greater downward goal revision at T2. Career-related stress partially mediated the relationship between negative career-related feedback and downward goal revision. In addition, there were reverse relationships between negative career-related feedback and career-related stress, and between career-related stress and goal disengagement. These findings highlight important roles for negative career-related feedback and negative affect in young peoples' career goal pursuit. (PsycINFO Database Record

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

    Directory of Open Access Journals (Sweden)

    Stefan Kobza

    Full Text Available 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.

  11. Negative Plant-Soil Feedback and Positive Species Interaction in a Herbaceous Plant Community

    NARCIS (Netherlands)

    Bonanomi, G.; Rietkerk, M.; Dekker, S.C.; Mazzoleni, S.

    2005-01-01

    Increasing evidence shows that facilitative interaction and negative plant¿soil feedback are driving factors of plant population dynamics and community processes. We studied the intensity and the relative impact of negative feedback on clonal growth and seed germination of Scirpus holoschoenus, a

  12. Negative Plant–Soil Feedback and Positive Species Interaction in a Herbaceous Plant Community

    NARCIS (Netherlands)

    Bonanomi, G.; Rietkerk, M.G.; Dekker, S.C.; Mazzoleni, S.

    2005-01-01

    Increasing evidence shows that facilitative interaction and negative plant–soil feedback are driving factors of plant population dynamics and community processes. We studied the intensity and the relative impact of negative feedback on clonal growth and seed germination of Scirpus holoschoenus, a

  13. Negative Plant–Soil Feedback and Positive Species Interaction in a Herbaceous Plant Community

    NARCIS (Netherlands)

    Bonanomi, G.; Rietkerk, M.G.; Dekker, S.C.; Mazzoleni, S.

    2005-01-01

    Increasing evidence shows that facilitative interaction and negative plant–soil feedback are driving factors of plant population dynamics and community processes. We studied the intensity and the relative impact of negative feedback on clonal growth and seed germination of Scirpus holoschoenus, a ‘r

  14. Negative Plant-Soil Feedback and Positive Species Interaction in a Herbaceous Plant Community

    NARCIS (Netherlands)

    Bonanomi, G.; Rietkerk, M.; Dekker, S.C.; Mazzoleni, S.

    2005-01-01

    Increasing evidence shows that facilitative interaction and negative plant¿soil feedback are driving factors of plant population dynamics and community processes. We studied the intensity and the relative impact of negative feedback on clonal growth and seed germination of Scirpus holoschoenus, a `r

  15. Controlling a negative loaded hydraulic cylinder using pressure feedback

    DEFF Research Database (Denmark)

    Hansen, M.R.; Andersen, T.O.

    2010-01-01

    showing that without extra measures such a system will be unstable in a substantial part of the cylinder stroke. The stability criterion is expressed in hard quantities: Cylinder volumes, cylinder area ratio and overcenter valve pilot area ratio. A pressure feed back scheme that has as target to maintain...

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

    Science.gov (United States)

    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.

  17. Boys, don't cry: Gender and reactions to negative performance feedback.

    Science.gov (United States)

    Motro, Daphna; Ellis, Aleksander P J

    2017-02-01

    Our experiment is aimed at understanding how employee reactions to negative feedback are received by the feedback provider and how employee gender may play a role in the process. We focus specifically on the act of crying and, based on role congruity theory, argue that a male employee crying in response to negative performance feedback will be seen as atypical behavior by the feedback provider, which will bias evaluations of the employee on a number of different outcome variables, including performance evaluations, assessments of leadership capability, and written recommendations. That is, we expect an interactive effect between gender and crying on our outcomes, an effect that will be mediated by perceived typicality. We find support for our moderated mediation model in a sample of 169 adults, indicating that men who cry in response to negative performance feedback will experience biased evaluations from the feedback provider. Theoretical and practical implications are discussed. (PsycINFO Database Record

  18. Learning from Negative Feedback in Patients with Major Depressive Disorder is Attenuated by SSRI Antidepressants

    Directory of Open Access Journals (Sweden)

    Mohammad M. Herzallah

    2013-09-01

    Full Text Available 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 (SSRI 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 subjects. All were administered a category-learning task that allows for dissociation between learning from positive feedback (reward versus 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 versus negative feedback showed that both the medicated MDD and healthy control 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

  19. Failure to retreat: Blunted sensitivity to negative feedback supports risky behavior in adolescents.

    Science.gov (United States)

    McCormick, Ethan M; Telzer, Eva H

    2017-02-15

    Decision-making processes rarely occur in isolation. Rather, representations are updated constantly based on feedback to past decisions and actions. However, previous research has focused on the reaction to feedback receipt itself, instead of examining how feedback information is integrated into future decisions. In the current study, we examined differential neural sensitivity during risk decisions following positive versus negative feedback in a risk-taking context, and how this differential sensitivity is linked to adolescent risk behavior. Fifty-eight adolescents (ages 13-17 years) completed the Balloon Analogue Risk Task (BART) during an fMRI session and reported on their levels of risk-taking behavior. Results show that reduced medial PFC (mPFC) response following negative versus positive feedback is associated with fewer reductions in task-based risky decisions following negative feedback, as well as increased self-reported risk-taking behavior. These results suggest that reduced neural integration of negative feedback into during future decisions supports risky behavior, perhaps by discounting negative relative to positive feedback information when making subsequent risky decisions.

  20. A novel approach to negative feedback in RX front-ends

    DEFF Research Database (Denmark)

    Vandi, Luca; Andreani, Pietro; Tired, Tobias

    2006-01-01

    A new approach to negative feedback is proposed and applied to active mixer cells based on Gilbert multiplier. The feedback can be exploited in several ways, and different configurations are derived. A dual-loop topology provides a solution for inductor-less broad-band receiver stages. The nature...

  1. Age-related changes in deterministic learning from positive versus negative performance feedback

    NARCIS (Netherlands)

    Vijver, I. van de; Ridderinkhof, K.R.; Wit, S. de

    2015-01-01

    Feedback-based learning declines with age. Because older adults are generally biased toward positive information (“positivity effect”), learning from positive feedback may be less impaired than learning from negative outcomes. The literature documents mixed results, due possibly to variability betwe

  2. Age-related changes in deterministic learning from positive versus negative performance feedback

    NARCIS (Netherlands)

    van de Vijver, I.; Ridderinkhof, K.R.; de Wit, S.

    2015-01-01

    Feedback-based learning declines with age. Because older adults are generally biased toward positive information ("positivity effect"), learning from positive feedback may be less impaired than learning from negative outcomes. The literature documents mixed results, due possibly to variability betwe

  3. Negative Feedback for Small Capacitive Touchscreen Interfaces: A Usability Study for Data Entry Tasks.

    Science.gov (United States)

    Parikh, S P; Esposito, J M

    2012-01-01

    Touchscreen technology has become pervasive in the consumer product arena over the last decade, offering some distinct advantages such as software reconfigurable interfaces and the removal of space consuming mice and keyboards. However, there are significant drawbacks to these devices that have limited their adoption by some users. Most notably, standard touchscreens demand the user's visual attention and require them to look at the input device to avoid pressing the wrong button. This issue is particularly important for mobile, capacitive sensing, nonstylus devices, such as the iPhone where small button sizes can generate high error rates. While previous work has shown the benefits of augmenting such interfaces with audio or vibrotactile feedback, only positive feedback (confirmation of button presses) has been considered. In this paper, we present a simple prototype interface that provides negative vibrotactile feedback. By negative, we mean feedback is generated when an inactive or ambiguous part of the screen, such as the area between two buttons, is touched. First, we present a usability study comparing positive and negative vibrotactile feedback for a benchmark numerical data entry task. The difference in performance is not statistically significant, implying negative feedback provides comparable benefits. Next, based on the experimenter's observations and the users comments, we introduce a multimodal feedback strategy-combining complementary positive audio and negative vibrotactile signals. User tests on a text entry experiment show that, with multimodal feedback, users exhibit a (statistically significant) 24 percent reduction in corrective key presses, as compared to positive audio feedback alone. Exit survey comments indicate that users favor multimodal feedback.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  6. Methylglyoxal in cells elicits a negative feedback loop entailing transglutaminase 2 and glyoxalase 1

    Directory of Open Access Journals (Sweden)

    Der-Yen Lee

    2014-01-01

    Full Text Available Glyoxalase 1 (GlxI is the key enzyme that converts the highly reactive α-oxo-aldehydes into the corresponding α-hydroxy acids using l-glutathione as a cofactor. In our preliminary data, GlxI was identified as a substrate of transglutaminase 2 (TG2, a ubiquitous enzyme with multiple functions. According to the catalytic properties of TG2, protein cross-linking, polyamine conjugation, and/or deamidation are potential post-translational modifications. In this article, we have demonstrated that TG2 catalyzes either polyamine conjugation or deamidation to GlxI depending on the presence of polyamines or not. Deamidation leads to activation of GlxI while polyamine conjugation results in activation of GlxI as well as stabilization of GlxI against denaturation treatment. In cultured HeLa cells, methylglyoxal challenge causes increase in intracellular levels of reactive oxygen species (ROS and calcium leading to TG2 activation and subsequent transamidation and activation of GlxI. The inhibition of TG2 significantly weakens the cell resistance to the methylglyoxal challenge. Thus, GlxI is a novel substrate of TG2 and is activated by TG2 in vitro and in cellulo. Exposure to methylglyoxal elicits a negative feedback loop entailing ROS, calcium, TG2 and GlxI, thus leading to attenuation of the increase in the methylglyoxal level. The results imply that cancer cells highly express TG2 or GlxI can endure the oxidative stress derived from higher glycolytic flux and may gain extra growth advantage from the aerobic glycolysis.

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

    Science.gov (United States)

    Forbes, Chad E; Leitner, Jordan B

    2014-10-01

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

  8. Negative consequences of positive feedbacks in US wildfire management

    Directory of Open Access Journals (Sweden)

    David E Calkin

    2015-04-01

    Full Text Available Over the last two decades wildfire activity, damage, and management cost within the US have increased substantially. These increases have been associated with a number of factors including climate change and fuel accumulation due to a century of active fire suppression. The increased fire activity has occurred during a time of significant ex-urban development of the Wildland Urban Interface (WUI along with increased demand on water resources originating on forested landscapes. These increased demands have put substantial pressure on federal agencies charged with wildfire management to continue and expand the century old policy of aggressive wildfire suppression. However, aggressive wildfire suppression is one of the major factors that drive the increased extent, intensity, and damage associated with the small number of large wildfires that are unable to be suppressed. In this paper we discuss the positive feedback loops that lead to demands for increasing suppression response while simultaneously increasing wildfire risk in the future. Despite a wealth of scientific research that demonstrates the limitations of the current management paradigm pressure to maintain the existing system are well entrenched and driven by the existing social systems that have evolved under our current management practice. Interestingly, US federal wildland fire policy provides considerable discretion for managers to pursue a range of management objectives; however, societal expectations and existing management incentive structures result in policy implementation that is straining the resilience of fire adapted ecosystems and the communities that reside in and adjacent to them.

  9. Negative consequences of positive feedbacks in US wildfire management

    Institute of Scientific and Technical Information of China (English)

    David E Calkin; MattheWP Thompson; Mark A Finney

    2015-01-01

    Over the last two decades wildfire activity, damage, and management cost within the US have increased substantially. These increases have been associated with a number of factors including climate change and fuel accumulation due to a century of active fire suppression. The increased fire activity has occurred during a time of significant ex-urban development of the Wildland Urban Interface (WUI) along with increased demand on water resources originating on forested landscapes. These increased demands have put substantial pressure on federal agencies charged with wildfire management to continue and expand the century old policy of aggressive wildfire suppression. However, aggressive wildfire suppression is one of the major factors that drive the increased extent, intensity, and damage associated with the small number of large wildfires that are unable to be suppressed. In this paper we discuss the positive feedback loops that lead to demands for increasing suppression response while simultaneously increasing wildfire risk in the future. Despite a wealth of scientific research that demonstrates the limitations of the current management paradigm pressure to maintain the existing system are well entrenched and driven by the existing social systems that have evolved under our current management practice. Interestingly, US federal wildland fire policy provides considerable discretion for managers to pursue a range of management objectives;however, societal expectations and existing management incentive structures result in policy implementation that is straining the resilience of fire adapted ecosystems and the communities that reside in and adjacent to them.

  10. The feedback-related negativity reflects the binary evaluation of good versus bad outcomes.

    Science.gov (United States)

    Hajcak, Greg; Moser, Jason S; Holroyd, Clay B; Simons, Robert F

    2006-02-01

    Electrophysiological studies have utilized event-related brain potentials to study neural processes related to the evaluation of environmental feedback. In particular, the feedback-related negativity (FRN) has been shown to reflect the evaluation of monetary losses and negative performance feedback. Two experiments were conducted to examine whether or not the FRN is sensitive to the magnitude of negative feedback. In both experiments, participants performed simple gambling tasks in which they could receive a range of potential outcomes on each trial. Relative to feedback indicating monetary gain, feedback indicating non-rewards was associated with a FRN in both experiments; however, the magnitude of the FRN did not demonstrate sensitivity to the magnitude of non-reward in either experiment. These data suggest that the FRN reflects the early appraisal of feedback based on a binary classification of good versus bad outcomes. These data are discussed in terms of contemporary theories of the FRN, as well as appraisal processes implicated in emotional processing.

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

    Science.gov (United States)

    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

  12. Negative feedback enables fast and flexible collective decision-making in ants.

    Directory of Open Access Journals (Sweden)

    Christoph Grüter

    Full Text Available 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.

  13. Negative feedback enables fast and flexible collective decision-making in ants.

    Science.gov (United States)

    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.

  14. Ultrasensitive Negative Feedback Control: A Natural Approach for the Design of Synthetic Controllers

    Science.gov (United States)

    Montefusco, Francesco; Akman, Ozgur E.; Soyer, Orkun S.; Bates, Declan G.

    2016-01-01

    Many of the most important potential applications of Synthetic Biology will require the ability to design and implement high performance feedback control systems that can accurately regulate the dynamics of multiple molecular species within the cell. Here, we argue that the use of design strategies based on combining ultrasensitive response dynamics with negative feedback represents a natural approach to this problem that fully exploits the strongly nonlinear nature of cellular information processing. We propose that such feedback mechanisms can explain the adaptive responses observed in one of the most widely studied biomolecular feedback systems—the yeast osmoregulatory response network. Based on our analysis of such system, we identify strong links with a well-known branch of mathematical systems theory from the field of Control Engineering, known as Sliding Mode Control. These insights allow us to develop design guidelines that can inform the construction of feedback controllers for synthetic biological systems. PMID:27537373

  15. The effect of negative feedback on noise propagation in transcriptional gene networks

    Science.gov (United States)

    Hooshangi, Sara; Weiss, Ron

    2006-06-01

    This paper analyzes how the delay and repression strength of negative feedback in single-gene and multigene transcriptional networks influences intrinsic noise propagation and oscillatory behavior. We simulate a variety of transcriptional networks using a stochastic model and report two main findings. First, intrinsic noise is not attenuated by the addition of negative or positive feedback to transcriptional cascades. Second, for multigene negative feedback networks, synchrony in oscillations among a cell population can be improved by increasing network depth and tightening the regulation at one of the repression stages. Our long term goal is to understand how the noise characteristics of complex networks can be derived from the properties of modules that are used to compose these networks.

  16. The Effects of Anticipated Negative Feedback on Psychological States Among Narcissists

    Directory of Open Access Journals (Sweden)

    Akiko Matsuo

    2016-05-01

    Full Text Available Although narcissism has long been researched in relation to anger, previous research examined narcissistic anger toward negative feedback that had already occurred. In this study, we investigated the effects of anticipation of evaluation (present vs. absent and negative feedback (present vs. absent, using a creativity task paradigm, on state anger scores among 231 U.S. undergraduates (76% White, 60% women. We also measured undergraduates’ narcissistic tendencies and impressions of the creativity task. Multiple regression analyses revealed a significant interaction between narcissism and negative feedback on total anger scores, with narcissists responding with more anger than non-narcissists in the condition of negative feedback. We also found a significant two-way interaction between narcissism and anticipation of evaluation on total enjoyment scores. Anticipation of feedback inhibited narcissist-prone individuals from enjoying the task in the anticipation condition, but this pattern was not present in the no-anticipation condition. Implications and recommendations to better understand the nature of narcissism are discussed.

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

    Directory of Open Access Journals (Sweden)

    Kerstin eUnger

    2012-06-01

    Full Text Available 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 midfrontal error signals as reflected in the error negativity (Ne/ERN and the FRN (feedback-related negativity. 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.

  18. Flat-response spin-exchange relaxation free atomic magnetometer under negative feedback.

    Science.gov (United States)

    Lee, Hyun Joon; Shim, Jeong Hyun; Moon, Han Seb; Kim, Kiwoong

    2014-08-25

    We demonstrate that the use of negative feedback extends the detection bandwidth of an atomic magnetometer in a spin-exchange relaxation free (SERF) regime. A flat-frequency response from zero to 190 Hz was achieved, which is nearly a three-fold enhancement while maintaining sensitivity, 3 fT/Hz1/2 at 100 Hz. With the extension of the bandwidth, the linear correlation between measured signals and a magne-tocardiographic field synthesized for comparison was increased from 0.21 to 0.74. This result supports the feasibility of measuring weak biomagnetic signals containing multiple frequency components using a SERF atomic magnetometer under negative feedback.

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

    Science.gov (United States)

    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

  20. Age-related changes in deterministic learning from positive versus negative performance feedback.

    Science.gov (United States)

    van de Vijver, Irene; Ridderinkhof, K Richard; de Wit, Sanne

    2015-01-01

    Feedback-based learning declines with age. Because older adults are generally biased toward positive information ("positivity effect"), learning from positive feedback may be less impaired than learning from negative outcomes. The literature documents mixed results, due possibly to variability between studies in task design. In the current series of studies, we investigated the influence of feedback valence on reinforcement learning in young and older adults. We used nonprobabilistic learning tasks, to more systematically study the effects of feedback magnitude, learning of stimulus-response (S-R) versus stimulus-outcome (S-O) associations, and working-memory capacity. In most experiments, older adults benefitted more from positive than negative feedback, but only with large feedback magnitudes. Positivity effects were pronounced for S-O learning, whereas S-R learning correlated with working-memory capacity in both age groups. These results underline the context dependence of positivity effects in learning and suggest that older adults focus on high gains when these are informative for behavior.

  1. How to not get stuck-negative feedback due to crowding maintains flexibility in ant foraging.

    Science.gov (United States)

    Czaczkes, Tomer J

    2014-11-07

    Ant foraging is an important model system in the study of adaptive complex systems. Many ants use trail pheromones to recruit nestmates to resources. Differential recruitment depending on resource quality coupled with positive feedback allows ant colonies to make rapid and accurate collective decisions about how best to allocate their work-force. However, ant colonies can become trapped in sub-optimal foraging decisions if recruitment to a poor resource becomes too strong before a better resource is discovered. Genetic algorithms and Ant Colony Optimisation heuristics can also suffer from being trapped in such local optima. Recently, two negative feedback effects were described, in which an increase in crowding (crowding negative feedback-CNF) or trail pheromones (pheromone negative feedback-PNF) caused a decrease in subsequent pheromone deposition. Using agent based simulations with realistic parameters I test whether these negative feedback effects can prevent simulated ant colonies from becoming trapped in sub-optimal foraging decisions. Colonies are presented with two food sources of different qualities, and these qualities switch part way through the experiment. When either no negative feedback effects are implemented or only PNF is implemented colonies are completely unable to refocus their foraging effort to the high quality feeder. However, when CNF alone is implemented at a realistic level 97% of colonies successfully refocus their foraging effort. This ability to refocus colony foraging efforts is due to the strong reduction of pheromone deposition caused by CNF. This suggests that CNF is an important behaviour enabling ant colonies to maintain foraging flexibility. However, CNF comes at a slight cost to colonies when making their initial foraging decision. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Feedback-related negativity codes outcome valence, but not outcome expectancy, during reversal learning

    NARCIS (Netherlands)

    Borries, A.K.L. von; Verkes, R.J.; Bulten, B.H.; Cools, R.; Bruijn, E.R. de

    2013-01-01

    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 pr

  3. Removal of Negative Feedback Enhances WCST Performance for Individuals with ASD

    Science.gov (United States)

    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…

  4. Feedback-related negativity codes outcome valence, but not outcome expectancy, during reversal learning

    NARCIS (Netherlands)

    Borries, A.K.L. von; Verkes, R.J.; Bulten, B.H.; Cools, R.

    2013-01-01

    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 p

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

    NARCIS (Netherlands)

    van Duijvenvoorde, A.C.K.; Zanolie, K.; Rombouts, S.A.R.B.; Raijmakers, M.E.J.; Crone, E.A.

    2008-01-01

    Howchildren 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

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

    Science.gov (United States)

    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…

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

    Science.gov (United States)

    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.…

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

    Directory of Open Access Journals (Sweden)

    Jingbo Gong

    Full Text Available 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.

  9. Usefulness of interferon-γ release assay for the diagnosis of sputum smear-negative pulmonary and extra-pulmonary TB in Zhejiang Province, China.

    Science.gov (United States)

    Ji, Lei; Lou, Yong-Liang; Wu, Zhong-Xiu; Jiang, Jin-Qin; Fan, Xing-Li; Wang, Li-Fang; Liu, Xiao-Xiang; Du, Peng; Yan, Jie; Sun, Ai-Hua

    2017-09-01

    Quick diagnosis of smear-negative pulmonary tuberculosis (TB) and extra-pulmonary TB are urgently needed in clinical diagnosis. Our research aims to investigate the usefulness of the interferon-γ release assay (IGRA) for the diagnosis of smear-negative pulmonary and extra-pulmonary TB. We performed TB antibody and TB-IGRA tests on 389 pulmonary TB patients (including 120 smear-positive pulmonary TB patients and 269 smear-negative pulmonary TB patients), 113 extra-pulmonary TB patients, 81 patients with other pulmonary diseases and 100 healthy controls. Blood samples for the TB-Ab test and the TB-IGRA were collected, processed, and interpreted according to the manufacturer's protocol. The detection ratio of smear-positive pulmonary TB patients and smear-negative pulmonary TB patients were 90.8% (109 of 120) and 89.6% (241 of 269), respectively. There was no statistically significant difference of its performance between these two sample sets (P > 0.05). The detection ratio of positive TB patients and extra-pulmonary TB patients were 90.0% (350 of 389) and 87.6% (99 of 113), respectively, which was not significantly different (P > 0.05). In this work, the total detection ratio using TB-IGRA was 89.4%, therefore TB-IGRA has diagnostic values in smear-negative pulmonary TB and extra-pulmonary TB diagnosis.

  10. The anti-waggle dance: use of the stop signal as negative feedback

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    Parry Macdonald Kietzman

    2015-02-01

    Full Text Available Numerous activities within honey bee (Apis mellifera L. colonies rely on feedback loops for organization at the group level. Classic examples of these self-organizing behaviors occur during foraging and swarm nest site selection. The waggle dance provides positive feedback, promoting foraging at a specific location or increased scouting at a potential nest site. Rather less well known than the waggle dance, the stop signal, a short vibration often delivered while butting against a dancing bee, is currently best understood as a counter to the waggle dance, offering negative feedback towards the advertised foraging location or nest site. When the stop signal is received by a waggle dancer she is more likely to terminate her dance early and retire from the dance floor. Bees that experienced danger or overcrowding at a food source are more likely to perform the stop signal upon their return to the colony, resulting in an inhibition of foraging at that location. During a swarm’s nest site selection process, scout bees that visited a different site than the one being advertised are more likely to stop-signal the waggle dancer than are scouts that had visited the same site. Over time, the scout bees build recruitment to a single site until a quorum is reached and the swarm can move to it. The balance between the positive feedback from the waggle dance and the negative feedback from the stop signal allows for a more sensitive adjustment of response from the colony as a unit. Many of the processes associated with the feedback loops organizing a honey bee colony’s activities are in striking parallel to other systems, such as intercellular interactions involved in motor neuron function.

  11. To choose or to avoid: age differences in learning from positive and negative feedback.

    Science.gov (United States)

    Eppinger, Ben; Kray, Jutta

    2011-01-01

    In this study, we investigated whether older adults learn more from bad than good choices than younger adults and whether this is reflected in the error-related negativity (ERN). We applied a feedback-based learning task with two learning conditions. In the positive learning condition, participants could learn to choose responses that lead to monetary gains, whereas in the negative learning condition, they could learn to avoid responses that lead to monetary losses. To test the stability of learning preferences, the task involved a reversal phase in which stimulus-response assignments were inverted. Negative learners were defined as individuals that performed better in the negative than in the positive learning condition (and vice versa for positive learners). The behavioral data showed strong individual differences in learning from positive and negative outcomes that persisted throughout the reversal phase and were more pronounced for older than younger adults. Older negative learners showed a stronger tendency to avoid negative outcomes than younger negative learners. However, contrary to younger adults, this negative learning bias was not associated with a larger ERN, suggesting that avoidance learning in older negative learners might be decoupled from error processing. Furthermore, older adults showed learning impairments compared to younger adults. The ERP analyses suggest that these impairments reflect deficits in the ability to build up relational representations of ambiguous outcomes.

  12. Evolution of gene network activity by tuning the strength of negative-feedback regulation.

    Science.gov (United States)

    Peng, Weilin; Liu, Ping; Xue, Yuan; Acar, Murat

    2015-02-11

    Despite the examples of protein evolution via mutations in coding sequences, we have very limited understanding on gene network evolution via changes in cis-regulatory elements. Using the galactose network as a model, here we show how the regulatory promoters of the network contribute to the evolved network activity between two yeast species. In Saccharomyces cerevisiae, we combinatorially replace all regulatory network promoters by their counterparts from Saccharomyces paradoxus, measure the resulting network inducibility profiles, and model the results. Lowering relative strength of GAL80-mediated negative feedback by replacing GAL80 promoter is necessary and sufficient to have high network inducibility levels as in S. paradoxus. This is achieved by increasing OFF-to-ON phenotypic switching rates. Competitions performed among strains with or without the GAL80 promoter replacement show strong relationships between network inducibility and fitness. Our results support the hypothesis that gene network activity can evolve by optimizing the strength of negative-feedback regulation.

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

    Science.gov (United States)

    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.

  14. Spatio-temporal dynamcis of a cell signal cascade with negative feedback

    Science.gov (United States)

    Maya Bernal, Jose Luis; Ramirez-Santiago, Guillermo

    2014-03-01

    We studied the spatio-temporal dynamics of a system of reactio-diffusion equations that models a cell signal transduction pathway with six cycles and negative feedback. The basic cycle consists of the phosphorylation-dephosphorylation of two antagonic proteins. We found two regimes of saturation of the enzimatic reaction in the kinetic parameters space and determined the conditions for the signal propagation in the steady state. The trajectories for which transduction occurs are defined in terms of the ratio of the enzimatic activities. We found that in spite of the negative feedback the cell signal cascade behaves as an amplifier and produces phosphoprotein concentration gradients within the cell. This model behaves also as a noise filter and as a switch. Supported by DGAPA-UNAM Contract IN118410-3.

  15. Coherently amplified negative feedback loop as a model for NF-kappaB oscillations

    Science.gov (United States)

    Joo, Jaewook

    2010-03-01

    The cells secrets various signaling molecules as a response to an external signal and modulate its own signaling processes. The precise role of this autocrine and/or paracrine signaling on cell information processing is mostly unknown. We will present the effect of TNF alpha autocrine signaling on NF-kappaB oscillations, using a simplified model of coherently amplified negative feedback loop. We will discuss the bifurcation diagram (i.e., dose-response curve), especially the robustness and the tenability of the period of NF-kappaB oscillations. Finally, we will compare the results from the above model with those from a previous model of time-delayed negative feedback alone.

  16. Near infrared single photon avalanche detector with negative feedback and self quenching

    Science.gov (United States)

    Linga, Krishna; Yevtukhov, Yuriy; Liang, Bing

    2009-08-01

    We present the design and development of a negative feedback devices using the internal discrete amplifier approach used for the development of a single photon avalanche photodetector in the near infrared wavelength region. This new family of photodetectors with negative feedback, requiring no quenching mechanism using Internal Discrete Amplification (IDA) mechanism for the realization of very high gain and low excess noise factor in the visible and near infrared spectral regions, operates in the non-gated mode under a constant bias voltage. The demonstrated device performance far exceeds any available solid state Photodetectors in the near infrared wavelength range. The measured devices have Gain > 2×105, Excess noise factor Lidar, free space optical communication, 3D imaging, industrial and scientific instrumentation, night vision, quantum cryptography, and other military, defence and aerospace applications.

  17. Negative feedback loops leading to nitrate homeostasis and oscillatory nitrate assimilation in plants and fungi.

    OpenAIRE

    Huang, Yongshun

    2011-01-01

    Nitrate is an important nutrient for plants and fungi. For plants it has been shown that cytosolic nitrate levels are under homeostatic control. Here we describe two networks that can obtain robust, i.e. perturbation independent, homeostatic behavior in cytosolic nitrate concentration. One of the networks, a member in the family of outflow controllers, is based on a negative feedback loop containing a nitrate-induced activation of a controller molecule which removes nitrate. In plants this co...

  18. A Nonlinear Distortion Compensation Method with Adaptive Predistorter and Negative Feed-Back for a Narrow-Band Signal

    Science.gov (United States)

    Zhang, Yitao; Muta, Osamu; Akaiwa, Yoshihiko

    The adaptive predistorter and the negative feedback system are known as methods to compensate for the nonlinear distortion of a power amplifier. Although the feedback method is a simple technique, its instability impedes the capability of high-feedback gain to achieve a high-compensation effect. On the other hand, the predistorter requires a long time for convergence of the adaptive predistorters. In this paper, we propose a nonlinear distortion compensation method for a narrow-band signal. In this method, an adaptive predistorter and negative feedback are combined. In addition, to shorten the convergence time to minimize nonlinear distortion, a variable step-size (VS) method is also applied to the algorithm to determine the parameters of the adaptive predistorter. Using computer simulations, we show that the proposed scheme achieves both five times faster convergence speed than that of the predistorter and three times higher permissible delay time in the feedback amplifier than that of a negative feedback only amplifier.

  19. The role of time delay in adaptive cellular negative feedback systems.

    Science.gov (United States)

    Lapytsko, Anastasiya; Schaber, Jörg

    2016-06-07

    Adaptation in cellular systems is often mediated by negative feedbacks, which usually come with certain time delays causing several characteristic response patterns including an overdamped response, damped or sustained oscillations. Here, we analyse generic two-dimensional delay differential equations with delayed negative feedback describing the dynamics of biochemical adaptive signal-response networks. We derive explicit thresholds and boundaries showing how time delay determines characteristic response patterns of these networks. Applying our theoretical analyses to concrete data we show that adaptation to osmotic stress in yeast is optimal in the sense of minimizing adaptation time without causing oscillatory behaviour, i.e., a critically damped response. In addition, our framework demonstrates that a slight increase of time delay in the NF-κB system might induce a switch from damped to sustained oscillatory behaviour. Thus, we demonstrate how delay differential equations can be used to explicitly study the delay in biochemical negative feedback systems. Our analysis also provides insight into how time delay may tune biological signal-response patterns and control the systems behaviour.

  20. The feedback-related negativity reflects ‘more or less’ prediction error in appetitive and aversive conditions

    Directory of Open Access Journals (Sweden)

    Rongjun eYu

    2014-05-01

    Full Text Available Humans make predictions and use feedback to update their subsequent predictions. The feedback-related negativity (FRN has been found to be sensitive to negative feedback as well as negative prediction error, such that the FRN is larger for outcomes that are worse than expected. The present study examined prediction errors in both appetitive and aversive conditions. We found that the FRN was more negative for reward omission versus wins and for loss omission versus losses, suggesting that the FRN might classify outcomes in a more-or-less than expected fashion rather than in the better-or-worse than expected dimension. Our findings challenge the previous notion that the FRN only encodes negative feedback and ‘worse than expected’ negative prediction error.

  1. Negative feedback regulation of Wnt4 signaling by EAF1 and EAF2/U19.

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    Xiaoyang Wan

    Full Text Available Previous studies indicated that EAF (ELL-associated factor family members, EAF1 and EAF2/U19, play a role in cancer and embryogenesis. For example, EAF2/U19 may serve as a tumor suppressor in prostate cancer. At the same time, EAF2/U19 is a downstream factor in the non-canonical Wnt 4 signaling pathway required for eye development in Xenopus laevis, and along with EAF1, contributes to convergence and extension movements in zebrafish embryos through Wnt maintenance. Here, we used zebrafish embryos and mammalian cells to show that both EAF1 and EAF2/U19 were up-regulated by Wnt4 (Wnt4a. Furthermore, we found that EAF1 and EAF2/U19 suppressed Wnt4 expression by directly binding to the Wnt4 promoter as seen in chromatin immunoprecipitation assays. These findings indicate that an auto-regulatory negative feedback loop occurs between Wnt4 and the EAF family, which is conserved between zebrafish and mammalian. The rescue experiments in zebrafish embryos showed that early embryonic development required the maintenance of the appropriate levels of Wnt4a through the feedback loop. Others have demonstrated that the tumor suppressors p63, p73 and WT1 positively regulate Wnt4 expression while p21 has the opposite effect, suggesting that maintenance of appropriate Wnt4 expression may also be critical for adult tissue homeostasis and prevention against tumor initiation. Thus, the auto-regulatory negative feedback loop that controls expression of Wnt4 and EAF proteins may play an important role in both embryonic development and tumor suppression. Our findings provide the first convincing line of evidence that EAF and Wnt4 form an auto-regulatory negative feedback loop in vivo.

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

    Science.gov (United States)

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

    2013-04-06

    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.

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

    Science.gov (United States)

    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

  4. Examination of a perceived cost model of employees' negative feedback-seeking behavior.

    Science.gov (United States)

    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.

  5. A computational model clarifies the roles of positive and negative feedback loops in the Drosophila circadian clock

    Science.gov (United States)

    Wang, Junwei; Zhou, Tianshou

    2010-06-01

    Previous studies showed that a single negative feedback structure should be sufficient for robust circadian oscillations. It is thus pertinent to ask why current cellular clock models almost universally have interlocked negative feedback loop (NFL) and positive feedback loop (PFL). Here, we propose a molecular model that reflects the essential features of the Drosophila circadian clock to clarify the different roles of negative and positive feedback loops. In agreement with experimental observations, the model can simulate circadian oscillations in constant darkness, entrainment by light-dark cycles, as well as phenotypes of per and clk mutants. Moreover, sustained oscillations persist when the PFL is removed, implying the crucial role of NFL for rhythm generation. Through parameter sensitivity analysis, it is revealed that incorporation of PFL increases the robustness of the system to regulatory processes in PFL itself. Such reduced models can aid understanding of the design principles of circadian clocks in Drosophila and other organisms with complex transcriptional feedback structures.

  6. Acute stress modulates feedback processing in men and women: differential effects on the feedback-related negativity and theta and beta power.

    Directory of Open Access Journals (Sweden)

    Stella Banis

    Full Text Available 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.

  7. Impact of time delays on oscillatory dynamics of interlinked positive and negative feedback loops

    Science.gov (United States)

    Huang, Bo; Tian, Xinyu; Liu, Feng; Wang, Wei

    2016-11-01

    Interlinking a positive feedback loop (PFL) with a negative feedback loop (NFL) constitutes a typical motif in genetic networks, performing various functions in cell signaling. How time delay in feedback regulation affects the dynamics of such systems still remains unclear. Here, we investigate three systems of interlinked PFL and NFL with time delays: a synthetic genetic oscillator, a three-node circuit, and a simplified single-node model. The stability of steady states and the routes to oscillation in the single-node model are analyzed in detail. The amplitude and period of oscillations vary with a pointwise periodicity over a range of time delay. Larger-amplitude oscillations can be induced when the PFL has an appropriately long delay, in comparison with the PFL with no delay or short delay; this conclusion holds true for all the three systems. We unravel the underlying mechanism for the above effects via analytical derivation under a limiting condition. We also develop a stochastic algorithm for simulating a single reaction with two delays and show that robust oscillations can be maintained by the PFL with a properly long delay in the single-node system. This work presents an effective method for constructing robust large-amplitude oscillators and interprets why similar circuit architectures are engaged in timekeeping systems such as circadian clocks.

  8. Novel Sinorhizobium meliloti quorum sensing positive and negative regulatory feedback mechanisms respond to phosphate availability.

    Science.gov (United States)

    McIntosh, Matthew; Meyer, Stefan; Becker, Anke

    2009-12-01

    The Sin quorum sensing system of Sinorhizobium meliloti depends upon at least three genes, sinR, sinI and expR, and N-acyl homoserine lactones (AHLs) as signals to regulate multiple processes in its free-living state in the rhizosphere and in the development towards symbiosis with its plant host. In this study, we have characterized novel mechanisms of transcription control through which the system regulates itself. At low AHL levels a positive feedback loop activates expression of sinI (AHL synthase), resulting in amplification of AHL levels. At high AHL levels, expression of sinI is reduced by a negative feedback loop. These feedback mechanisms are mediated by the LuxR-type regulators ExpR and SinR. Expression of sinR and expR is regulated by ExpR in the presence of AHLs. A novel ExpR binding site in the promoter of sinR is responsible for the reduction of expression of this gene. In addition, expression of sinR, upon which sinI expression is dependent, is induced by phoB during growth under phosphate-limiting conditions. This indicates that this response ensures quorum sensing in phosphate-restricted growth.

  9. Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes.

    Science.gov (United States)

    Cornelissen, Johannes H C; van Bodegom, Peter M; Aerts, Rien; Callaghan, Terry V; van Logtestijn, Richard S P; Alatalo, Juha; Chapin, F Stuart; Gerdol, Renato; Gudmundsson, Jon; Gwynn-Jones, Dylan; Hartley, Anne E; Hik, David S; Hofgaard, Annika; Jónsdóttir, Ingibjörg S; Karlsson, Staffan; Klein, Julia A; Laundre, Jim; Magnusson, Borgthor; Michelsen, Anders; Molau, Ulf; Onipchenko, Vladimir G; Quested, Helen M; Sandvik, Sylvi M; Schmidt, Inger K; Shaver, Gus R; Solheim, Bjørn; Soudzilovskaia, Nadejda A; Stenström, Anna; Tolvanen, Anne; Totland, Ørjan; Wada, Naoya; Welker, Jeffrey M; Zhao, Xinquan

    2007-07-01

    Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold northern biomes worldwide. Leaf litters collected from the predominant species in 33 global change manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously in two contrasting arctic life zones. We demonstrate that longer-term, large-scale changes to leaf litter decomposition will be driven primarily by both direct warming effects and concomitant shifts in plant growth form composition, with a much smaller role for changes in litter quality within species. Specifically, the ongoing warming-induced expansion of shrubs with recalcitrant leaf litter across cold biomes would constitute a negative feedback to global warming. Depending on the strength of other (previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this may partly counteract direct warming enhancement of litter decomposition.

  10. The Effect of Positive and Negative Feedback on Risk-Taking across Different Contexts.

    Directory of Open Access Journals (Sweden)

    Annabel B Losecaat Vermeer

    Full Text Available Preferences for risky choices have often been shown to be unstable and context-dependent. Though people generally avoid gambles with mixed outcomes, a phenomenon often attributed to loss aversion, contextual factors can impact this dramatically. For example, people typically prefer risky options after a financial loss, while generally choosing safer options after a monetary gain. However, it is unclear what exactly contributes to these preference shifts as a function of prior outcomes, as these gain/loss outcomes are usually confounded with participant performance, and therefore it is unclear whether these effects are driven purely by the monetary gains or losses, or rather by success or failure at the actual task. Here, we experimentally separated the effects of monetary gains/losses from performance success/failure prior to a standard risky choice. Participants performed a task in which they experienced contextual effects: 1 monetary gain or loss based directly on performance, 2 monetary gain or loss that was randomly awarded and was, crucially, independent from performance, and 3 success or failure feedback based on performance, but without any monetary incentive. Immediately following these positive/negative contexts, participants were presented with a gain-loss gamble that they had to decide to either play or pass. We found that risk preferences for identical sets of gambles were biased by positive and negative contexts containing monetary gains and losses, but not by contexts containing performance feedback. This data suggests that the observed framing effects are driven by aversion for monetary losses and not simply by the positive or negative valence of the context, or by potential moods resulting from positive or negative contexts. These results highlight the specific context dependence of risk preferences.

  11. Plant-soil feedbacks promote negative frequency dependence in the coexistence of two aridland grasses.

    Science.gov (United States)

    Chung, Y Anny; Rudgers, Jennifer A

    2016-07-27

    Understanding the mechanisms of species coexistence is key to predicting patterns of species diversity. Historically, the ecological paradigm has been that species coexist by partitioning resources: as a species increases in abundance, self-limitation kicks in, because species-specific resources decline. However, determining coexistence mechanisms has been a particular puzzle for sedentary organisms with high overlap in their resource requirements, such as plants. Recent evidence suggests that plant-associated microbes could generate the stabilizing self-limitation (negative frequency dependence) that is required for species coexistence. Here, we test the key assumption that plant-microbe feedbacks cause such self-limitation. We used competition experiments and modelling to evaluate how two common groups of soil microbes (rhizospheric microbes and biological soil crusts) influenced the self-limitation of two competing desert grass species. Negative feedbacks between the dominant plant competitor and its rhizospheric microbes magnified self-limitation, whereas beneficial interactions between both plant species and biological soil crusts partly counteracted this stabilizing effect. Plant-microbe interactions have received relatively little attention as drivers of vegetation dynamics in dry land ecosystems. Our results suggest that microbial mechanisms can contribute to patterns of plant coexistence in arid grasslands.

  12. Positive and negative feedbacks among Amazon land uses, drought, and fire: the drought of 2005

    Science.gov (United States)

    Nepstad, D.; Brando, P.; Soares-Filho, B.; Balch, J.; Moutinho, P.

    2006-12-01

    Climate, rural economies, and ecosystems are connected in the Amazon basin through complex interactions with important implications for greenhouse gas fluxes, biodiversity, and the well-being of rural people. In the historically severe drought of 2005, drought-induced tree mortality and fire-dependent land uses (cattle ranching, swidden agriculture) favored forest fire as it increased the likelihood of further drought. Regions with fire-sensitive investments in the landscape, including improved cattle forage, agroforestry systems, and forest management, were also regions of high investments in the prevention of accidental fire, and experienced low levels of forest fire, in a negative feedback cycle. Some areas of agroindustrial production(cultivated soy) also experienced low forest fire occurrence because of the low flammability of crop fields. The combination of drought- and fire-induced carbon emissions can approach one billion tons in years of severe drought. The negative feedbacks between some types of land use and forest fire could substantially reduce these emissions in the short term.

  13. The effect of negative feedback on tension and subsequent performance: the main and interactive effects of goal content and conscientiousness.

    Science.gov (United States)

    Cianci, Anna M; Klein, Howard J; Seijts, Gerard H

    2010-07-01

    The purpose of this experiment was to examine the interplay of goal content, conscientiousness, and tension on performance following negative feedback. Undergraduate students were assigned either a learning or performance goal and then were provided with false feedback indicating very poor performance on the task they performed. After assessing tension, participants performed the task again with the same learning or performance goal. A mediated moderation model was tested, and results were supportive of our hypotheses. Specifically, individuals assigned a learning goal experienced less tension and performed better following negative feedback than individuals assigned a performance goal. Individuals high in conscientiousness experienced greater tension than individuals low in conscientiousness. Conscientiousness and goal content interacted in relating to both tension and performance, with tension as a mediator, such that high conscientiousness amplified the detrimental effect of a performance goal on tension following negative feedback leading to lower performance. High conscientiousness facilitated performance for participants with a learning goal.

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

    Science.gov (United States)

    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

  15. Elevated atmospheric CO2 negatively impacts photosynthesis through radiative forcing and physiology-mediated climate feedback

    Science.gov (United States)

    Zhu, Peng; Zhuang, Qianlai; Ciais, Philippe; Welp, Lisa; Li, Wenyu; Xin, Qinchuan

    2017-02-01

    Increasing atmospheric CO2 affects photosynthesis involving directly increasing leaf carboxylation rates, stomatal closure, and climatic effects. The direct effects are generally thought to be positive leading to increased photosynthesis, while its climatic effects can be regionally positive or negative. These effects are usually considered to be independent from each other, but they are in fact coupled through interactions between land surface exchanges of gases and heat and the physical climate system. In particular, stomatal closure reduces evapotranspiration and increases sensible heat emissions from ecosystems, leading to decreased atmospheric moisture and precipitation and local warming. We use a coupled earth system model to attribute the influence of the increase in CO2 on gross primary productivity (GPP) during the period of 1930-2011. In our model, CO2 radiative effects cause climate change that has only a negligible effect on global GPP (a reduction of 0.9 ± 2% during the last 80 years) because of opposite responses between tropical and northern biomes. On the other hand, CO2 physiological effects on GPP are both positive, by increased carboxylation rates and water use efficiency (7.1 ± 0.48% increase), and negative, by vegetation-climate feedback reducing precipitation, as a consequence of decreased transpiration and increased sensible heat in areas without water limitation (2.7 ± 1.76% reduction).When considering the coupled atmosphere-vegetation system, negative climate feedback on photosynthesis and plant growth due to the current level of CO2 opposes 29-38% of the gains from direct fertilization effects.

  16. A negative feedback loop mediated by STAT3 limits human Th17 responses.

    Science.gov (United States)

    Purvis, Harriet A; Anderson, Amy E; Young, David A; Isaacs, John D; Hilkens, Catharien M U

    2014-08-01

    The transcription factor STAT3 is critically required for the differentiation of Th17 cells, a T cell subset involved in various chronic inflammatory diseases. In this article, we report that STAT3 also drives a negative-feedback loop that limits the formation of IL-17-producing T cells within a memory population. By activating human memory CD4(+)CD45RO(+) T cells at a high density (HiD) or a low density (LoD) in the presence of the pro-Th17 cytokines IL-1β, IL-23, and TGF-β, we observed that the numbers of Th17 cells were significantly higher under LoD conditions. Assessment of STAT3 phosphorylation revealed a more rapid and stronger STAT3 activation in HiD cells than in LoD cells. Transient inhibition of active STAT3 in HiD cultures significantly enhanced Th17 cell numbers. Expression of the STAT3-regulated ectonucleotidase CD39, which catalyzes ATP hydrolysis, was higher in HiD, than in LoD, cell cultures. Interestingly, inhibition of CD39 ectonucleotidase activity enhanced Th17 responses under HiD conditions. Conversely, blocking the ATP receptor P2X7 reduced Th17 responses in LoD cultures. These data suggest that STAT3 negatively regulates Th17 cells by limiting the availability of ATP. This negative-feedback loop may provide a safety mechanism to limit tissue damage by Th17 cells during chronic inflammation. Furthermore, our results have relevance for the design of novel immunotherapeutics that target the STAT3-signaling pathway, because inhibition of this pathway may enhance, rather than suppress, memory Th17 responses.

  17. Adolescents' comments in social media : Why do adolescents receive negative feedback and who is most at risk?

    NARCIS (Netherlands)

    Koutamanis, Maria; Vossen, Helen G M; Valkenburg, Patti M.

    2015-01-01

    Abstract Receiving negative peer feedback in social media may have negative consequences for adolescents' psychosocial development and well-being. Therefore, the first aim of this study was to investigate online behavior (i.e., online social exploration, risky online self-presentation) that predicts

  18. Adolescents’ comments in social media: why do adolescents receive negative feedback and who is most at risk?

    NARCIS (Netherlands)

    Koutamanis, M.; Vossen, H.G.M.; Valkenburg, P.M.

    2015-01-01

    Receiving negative peer feedback in social media may have negative consequences for adolescents’ psychosocial development and well-being. Therefore, the first aim of this study was to investigate online behavior (i.e., online social exploration, risky online self-presentation) that predicts receivin

  19. The effects of the personality traits and positive and negative feedback on the perceived self-efficacy

    Directory of Open Access Journals (Sweden)

    Smederevac-Stokić Snežana

    2004-01-01

    Full Text Available The main purpose of this study was to determine the relation between the self-efficacy, feedback and personality traits. The participants were 114 psychology students attending their first and third year from the University of Novi Sad. In the first part of the research, all subjects completed The NEO-PI-R (Costa and McCrae, 1992.. In the second phase the subjects were asked to create a short measurement scale. Before and after this task, as well as after the given feedback, the students completed The Self-efficacy Questionnaire (Terry, 1995. The feedback was the criterion to divide subjects into three groups: the first group received the positive, the second negative, and third group received no feedback. Criteria variables in the MANCOVA (repeated measures were the estimated success, difficulty and ability to perform the task in the three stages of measurement. Predictor variables were the type of the feedback and the personality traits, as covariates. The results suggest that before feedback, the impact of traits on the self-efficacy was significant. But after received feedback, self-efficacy was related to the type of received feedback only. These results showed that self-efficacy was significantly influenced both by personality traits and feedback context.

  20. Vibration Analysis of a Piecewise-Smooth System with Negative Stiffness under Delayed Feedback Control

    Directory of Open Access Journals (Sweden)

    Dongmei Huang

    2017-01-01

    Full Text Available The principal resonance of a delayed piecewise-smooth (DPWS system with negative stiffness under narrow-band random excitation is investigated in aspects of multiscale analysis, design methodology of the controller, and response properties. The amplitude-frequency response and steady-state moments together with the corresponding stability conditions of the controlled stochastic system are derived, in which the degradation case is also under consideration. Then, from the perspective of the equivalent damping, the comparisons of the response characteristics of the controlled system to the uncontrolled system, such as the phenomenon of frequency island, are fulfilled. Furthermore, sensitivity of the system response to feedback gain and time delay is studied and interesting dynamic properties are found. Meanwhile, the classification of the steady-state solution is also discussed. To control the maximum amplitude, the feedback parameters are determined by the frequency response together with stability boundaries which must be utilized to exclude the combinations of the unstable parameters. For the case with small noise intensity, mean-square responses present the similar characteristics to what is discussed in the deterministic case.

  1. Negative feedback, beliefs and personal goals in prediction of dysfunctional emotions

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    Popov Boris

    2007-01-01

    Full Text Available Rational emotive behavior therapy (REBT demonstrates good results in evaluation therapy researches. However, some of its basic concepts, as well as theory as a whole itself, did not receive satisfactory empirical support so far, in comparison to other cognitive models (Beck, Lazarus etc.. Quasiexperimental study was designed to test the role that (1 negative feedback (A and (2 irrational beliefs (B both play in formation of dysfunctional negative emotions, in the context of significant personal goals (in our case value of potential award - G. ABC theoretical model received limited support: statistically significant three-times interaction A x B x G was found in predicting general negative emotional state, as well as anger. In contrast with that, ANOVA showed only main effect of irrational beliefs (as continuous variable to be significant in predicting emotions of anxiety and depression. Findings are discussed in the context of REBT theory of emotions, as well as their possible practical applications. Limitations of the study were also mentioned. .

  2. Feedback.

    Science.gov (United States)

    Richardson, Barbara K

    2004-12-01

    The emergency department provides a rich environment for diverse patient encounters, rapid clinical decision making, and opportunities to hone procedural skills. Well-prepared faculty can utilize this environment to teach residents and medical students and gain institutional recognition for their incomparable role and teamwork. Giving effective feedback is an essential skill for all teaching faculty. Feedback is ongoing appraisal of performance based on direct observation aimed at changing or sustaining a behavior. Tips from the literature and the author's experience are reviewed to provide formats for feedback, review of objectives, and elements of professionalism and how to deal with poorly performing students. Although the following examples pertain to medical student education, these techniques are applicable to the education of all adult learners, including residents and colleagues. Specific examples of redirection and reflection are offered, and pitfalls are reviewed. Suggestions for streamlining verbal and written feedback and obtaining feedback from others in a fast-paced environment are given. Ideas for further individual and group faculty development are presented.

  3. Experimental Comparison of two Active Vibration Control Approaches: Velocity Feedback and Negative Capacitance Shunt Damping

    Science.gov (United States)

    Beck, Benjamin; Schiller, Noah

    2013-01-01

    This paper outlines a direct, experimental comparison between two established active vibration control techniques. Active vibration control methods, many of which rely upon piezoelectric patches as actuators and/or sensors, have been widely studied, showing many advantages over passive techniques. However, few direct comparisons between different active vibration control methods have been made to determine the performance benefit of one method over another. For the comparison here, the first control method, velocity feedback, is implemented using four accelerometers that act as sensors along with an analog control circuit which drives a piezoelectric actuator. The second method, negative capacitance shunt damping, consists of a basic analog circuit which utilizes a single piezoelectric patch as both a sensor and actuator. Both of these control methods are implemented individually using the same piezoelectric actuator attached to a clamped Plexiglas window. To assess the performance of each control method, the spatially averaged velocity of the window is compared to an uncontrolled response.

  4. Messenger RNA Fluctuations and Regulatory RNAs Shape the Dynamics of Negative Feedback Loop

    CERN Document Server

    Martínez, María Rodríguez; Tlusty, Tsvi; Pilpel, Yitzhak; Furman, Itay; 10.1103/PhysRevE.81.031924

    2010-01-01

    Single cell experiments of simple regulatory networks can markedly differ from cell population experiments. Such differences arise from stochastic events in individual cells that are averaged out in cell populations. For instance, while individual cells may show sustained oscillations in the concentrations of some proteins, such oscillations may appear damped in the population average. In this paper we investigate the role of RNA stochastic fluctuations as a leading force to produce a sustained excitatory behavior at the single cell level. Opposed to some previous models, we build a fully stochastic model of a negative feedback loop that explicitly takes into account the RNA stochastic dynamics. We find that messenger RNA random fluctuations can be amplified during translation and produce sustained pulses of protein expression. Motivated by the recent appreciation of the importance of non--coding regulatory RNAs in post--transcription regulation, we also consider the possibility that a regulatory RNA transcri...

  5. Thyroid hormone exerts negative feedback on hypothalamic type 4 melanocortin receptor expression.

    Science.gov (United States)

    Decherf, Stéphanie; Seugnet, Isabelle; Kouidhi, Soumaya; Lopez-Juarez, Alejandra; Clerget-Froidevaux, Marie-Stéphanie; Demeneix, Barbara A

    2010-03-01

    The type 4 melanocortin receptor MC4R, a key relay in leptin signaling, links central energy control to peripheral reserve status. MC4R activation in different brain areas reduces food intake and increases energy expenditure. Mice lacking Mc4r are obese. Mc4r is expressed by hypothalamic paraventricular Thyrotropin-releasing hormone (TRH) neurons and increases energy usage through activation of Trh and production of the thyroid hormone tri-iodothyronine (T(3)). These facts led us to test the hypothesis that energy homeostasis should require negative feedback by T(3) on Mc4r expression. Quantitative PCR and in situ hybridization showed hyperthyroidism reduces Mc4r mRNA levels in the paraventricular nucleus. Comparative in silico analysis of Mc4r regulatory regions revealed two evolutionarily conserved potential negative thyroid hormone-response elements (nTREs). In vivo ChIP assays on mouse hypothalamus demonstrated association of thyroid hormone receptors (TRs) with a region spanning one nTRE. Further, in vivo gene reporter assays revealed dose-dependent T(3) repression of transcription from the Mc4r promoter in mouse hypothalamus, in parallel with T(3)-dependent Trh repression. Mutagenesis of the nTREs in the Mc4r promoter demonstrated direct regulation by T(3), consolidating the ChIP results. In vivo shRNA knockdown, TR over-expression approaches and use of mutant mice lacking specific TRs showed that both TRalpha and TRbeta contribute to Mc4r regulation. T(3) repression of Mc4r transcription ensures that the energy-saving effects of T(3) feedback on Trh are not overridden by MC4R activation of Trh. Thus parallel repression by T(3) on hypothalamic Mc4r and Trh contributes to energy homeostasis.

  6. Smart conjugated polymer nanocarrier for healthy weight loss by negative feedback regulation of lipase activity

    Science.gov (United States)

    Chen, Yu-Lei; Zhu, Sha; Zhang, Lei; Feng, Pei-Jian; Yao, Xi-Kuang; Qian, Cheng-Gen; Zhang, Can; Jiang, Xi-Qun; Shen, Qun-Dong

    2016-02-01

    Healthy weight loss represents a real challenge when obesity is increasing in prevalence. Herein, we report a conjugated polymer nanocarrier for smart deactivation of lipase and thus balancing calorie intake. After oral administration, the nanocarrier is sensitive to lipase in the digestive tract and releases orlistat, which deactivates the enzyme and inhibits fat digestion. It also creates negative feedback to control the release of itself. The nanocarrier smartly regulates activity of the lipase cyclically varied between high and low levels. In spite of high fat diet intervention, obese mice receiving a single dose of the nanocarrier lose weight over eight days, whereas a control group continues the tendency to gain weight. Daily intragastric administration of the nanocarrier leads to lower weight of livers or fat pads, smaller adipocyte size, and lower total cholesterol level than that of the control group. Near-infrared fluorescence of the nanocarrier reveals its biodistribution.Healthy weight loss represents a real challenge when obesity is increasing in prevalence. Herein, we report a conjugated polymer nanocarrier for smart deactivation of lipase and thus balancing calorie intake. After oral administration, the nanocarrier is sensitive to lipase in the digestive tract and releases orlistat, which deactivates the enzyme and inhibits fat digestion. It also creates negative feedback to control the release of itself. The nanocarrier smartly regulates activity of the lipase cyclically varied between high and low levels. In spite of high fat diet intervention, obese mice receiving a single dose of the nanocarrier lose weight over eight days, whereas a control group continues the tendency to gain weight. Daily intragastric administration of the nanocarrier leads to lower weight of livers or fat pads, smaller adipocyte size, and lower total cholesterol level than that of the control group. Near-infrared fluorescence of the nanocarrier reveals its biodistribution

  7. Negative feedback regulation of Homer 1a on norepinephrine-dependent cardiac hypertrophy

    Energy Technology Data Exchange (ETDEWEB)

    Chiarello, Carmelina; Bortoloso, Elena; Carpi, Andrea; Furlan, Sandra; Volpe, Pompeo, E-mail: pompeo.volpe@unipd.it

    2013-07-15

    Homers are scaffolding proteins that modulate diverse cell functions being able to assemble signalling complexes. In this study, the presence, sub-cellular distribution and function of Homer 1 was investigated. Homer 1a and Homer 1b/c are constitutively expressed in cardiac muscle of both mouse and rat and in HL-1 cells, a cardiac cell line. As judged by confocal immunofluorescence microscopy, Homer 1a displays sarcomeric and peri-nuclear localization. In cardiomyocytes and cultured HL-1 cells, the hypertrophic agonist norepinephrine (NE) induces α{sub 1}-adrenergic specific Homer 1a over-expression, with a two-to-three-fold increase within 1 h, and no up-regulation of Homer 1b/c, as judged by Western blot and qPCR. In HL-1 cells, plasmid-driven over-expression of Homer 1a partially antagonizes activation of ERK phosphorylation and ANF up-regulation, two well-established, early markers of hypertrophy. At the morphometric level, NE-induced increase of cell size is likewise and partially counteracted by exogenous Homer 1a. Under the same experimental conditions, Homer 1b/c does not have any effect on ANF up-regulation nor on cell hypertrophy. Thus, Homer 1a up-regulation is associated to early stages of cardiac hypertrophy and appears to play a negative feedback regulation on molecular transducers of hypertrophy. -- Highlights: • Homer 1a is constitutively expressed in cardiac tissue. • In HL-1 cells, norepinephrine activates signaling pathways leading to hypertrophy. • Homer 1a up-regulation is an early event of norepinephrine-induced hypertrophy. • Homer 1a plays a negative feedback regulation modulating pathological hypertrophy. • Over-expression of Homer 1a per se does not induce hypertrophy.

  8. An evolutionarily conserved negative feedback mechanism in the Hippo pathway reflects functional difference between LATS1 and LATS2.

    Science.gov (United States)

    Park, Gun-Soo; Oh, Hyangyee; Kim, Minchul; Kim, Tackhoon; Johnson, Randy L; Irvine, Kenneth D; Lim, Dae-Sik

    2016-04-26

    The Hippo pathway represses YAP oncoprotein activity through phosphorylation by LATS kinases. Although variety of upstream components has been found to participate in the Hippo pathway, the existence and function of negative feedback has remained uncertain. We found that activated YAP, together with TEAD transcription factors, directly induces transcription of LATS2, but not LATS1, to form a negative feedback loop. We also observed increased mRNA levels of Hippo upstream components upon YAP activation. To reveal the physiological role of this negative feedback regulation, we deleted Lats2 or Lats1 in the liver-specific Sav1-knockout mouse model which develops a YAP-induced tumor. Additional deletion of Lats2 severely enhanced YAP-induced tumorigenic phenotypes in a liver specific Sav1 knock-out mouse model while additional deletion of Lats1 mildly affected the phenotype. Only Sav1 and Lats2 double knock-down cells formed larger colonies in soft agar assay, thereby recapitulating accelerated tumorigenesis seen in vivo. Importantly, this negative feedback is evolutionarily conserved, as Drosophila Yorkie (YAP ortholog) induces transcription of Warts (LATS2 ortholog) with Scalloped (TEAD ortholog). Collectively, we demonstrated the existence and function of an evolutionarily conserved negative feedback mechanism in the Hippo pathway, as well as the functional difference between LATS1 and LATS2 in regulation of YAP.

  9. Negative feedback regulation of auxin signaling by ATHB8/ACL5-BUD2 transcription module.

    Science.gov (United States)

    Baima, Simona; Forte, Valentina; Possenti, Marco; Peñalosa, Andrés; Leoni, Guido; Salvi, Sergio; Felici, Barbara; Ruberti, Ida; Morelli, Giorgio

    2014-06-01

    The role of auxin as main regulator of vascular differentiation is well established, and a direct correlation between the rate of xylem differentiation and the amount of auxin reaching the (pro)cambial cells has been proposed. It has been suggested that thermospermine produced by ACAULIS5 (ACL5) and bushy and dwarf2 (BUD2) is one of the factors downstream to auxin contributing to the regulation of this process in Arabidopsis. Here, we provide an in-depth characterization of the mechanism through which ACL5 modulates xylem differentiation. We show that an increased level of ACL5 slows down xylem differentiation by negatively affecting the expression of homeodomain-leucine zipper (HD-ZIP) III and key auxin signaling genes. This mechanism involves the positive regulation of thermospermine biosynthesis by the HD-ZIP III protein Arabidopsis thaliana homeobox8 tightly controlling the expression of ACL5 and BUD2. In addition, we show that the HD-ZIP III protein REVOLUTA contributes to the increased leaf vascularization and long hypocotyl phenotype of acl5 likely by a direct regulation of auxin signaling genes such as like auxin resistant2 (LAX2) and LAX3. We propose that proper formation and differentiation of xylem depend on a balance between positive and negative feedback loops operating through HD-ZIP III genes.

  10. Negative BOLD in default-mode structures measured with EEG-MREG is larger in temporal than extra-temporal epileptic spikes

    Directory of Open Access Journals (Sweden)

    Julia eJacobs

    2014-11-01

    Full Text Available AbstractIntroduction: EEG-fMRI detects BOLD changes associated with epileptic interictal discharges (IED and can identify epileptogenic networks in epilepsy patients. Besides positive BOLD changes, negative BOLD changes have sometimes been observed in the default-mode network, particularly using group analysis. A new fast fMRI sequence called MREG (Magnetic Resonance Encephalography shows increased sensitivity to detect IED-related BOLD changes compared to the conventional EPI sequence, including frequent occurrence of negative BOLD responses in the DMN. The present study quantifies the concordance between the DMN and negative BOLD related to IEDs of temporal and extra-temporal origin.Methods: Focal epilepsy patients underwent simultaneous EEG-MREG. Areas of overlap were calculated between DMN regions, defined as precuneus, posterior cingulate, bilateral inferior parietal and mesial prefrontal cortices according to a standardized atlas, and significant negative BOLD changes revealed by an event-related analysis based on the timings of IED seen on EEG. Correlation between IED number/lobe of origin and the overlap were calculated. Results: 15 patients were analyzed, some showing IED over more than one location resulting in 30 different IED types. The average overlap between negative BOLD and DMN was significantly larger in temporal (23.7 ± 19.6cm³ than extra-temporal IEDs (7.4 ± 5.1 cm³, p=0.008. There was no significant correlation between the number of IEDs and the overlap between DMN structures and negative BOLD areas.Discussion: MREG results in an increased sensitivity to detect negative BOLD responses related to focal IED in single patients, with responses often occurring in DMN regions. In patients with high overlap with the DMN, this suggests that epileptic IEDs may be associated with a brief decrease in attention and cognitive ability. Interestingly this observation was not dependent on the frequency of IED but more common in IED of

  11. MK3 controls Polycomb target gene expression via negative feedback on ERK

    Directory of Open Access Journals (Sweden)

    Prickaerts Peggy

    2012-08-01

    Full Text Available Abstract Background Gene-environment interactions are mediated by epigenetic mechanisms. Polycomb Group proteins constitute part of an epigenetic cellular transcriptional memory system that is subject to dynamic modulation during differentiation. Molecular insight in processes that control dynamic chromatin association and dissociation of Polycomb repressive complexes during and beyond development is limited. We recently showed that MK3 interacts with Polycomb repressive complex 1 (PRC1. The functional relevance of this interaction, however, remained poorly understood. MK3 is activated downstream of mitogen- and stress-activated protein kinases (M/SAPKs, all of which fulfill crucial roles during development. We here use activation of the immediate-early response gene ATF3, a bona fide PRC1 target gene, as a model to study how MK3 and its effector kinases MAPK/ERK and SAPK/P38 are involved in regulation of PRC1-dependent ATF3 transcription. Results Our current data show that mitogenic signaling through ERK, P38 and MK3 regulates ATF3 expression by PRC1/chromatin dissociation and epigenetic modulation. Mitogenic stimulation results in transient P38-dependent H3S28 phosphorylation and ERK-driven PRC1/chromatin dissociation at PRC1 targets. H3S28 phosphorylation by itself appears not sufficient to induce PRC1/chromatin dissociation, nor ATF3 transcription, as inhibition of MEK/ERK signaling blocks BMI1/chromatin dissociation and ATF3 expression, despite induced H3S28 phosphorylation. In addition, we establish that concomitant loss of local H3K27me3 promoter marking is not required for ATF3 activation. We identify pERK as a novel signaling-induced binding partner of PRC1, and provide evidence that MK3 controls ATF3 expression in cultured cells via negative regulatory feedback on M/SAPKs. Dramatically increased ectopic wing vein formation in the absence of Drosophila MK in a Drosophila ERK gain-of-function wing vein patterning model, supports the

  12. Dopaminergic medication modulates learning from feedback and error-related negativity in Parkinson’s disease: a pilot study

    Directory of Open Access Journals (Sweden)

    Chiara Volpato

    2016-10-01

    Full Text Available Dopamine systems mediate key aspects of reward learning. Parkinson’s disease (PD represents a valuable model to study reward mechanisms because both the disease process and the anti-Parkinson medications influence dopamine neurotransmission. The aim of this pilot study was to investigate whether the level of levodopa differently modulates learning from positive and negative feedback and its electrophysiological correlate, the error related negativity (ERN, in PD. Ten PD patients and ten healthy participants performed a two-stage reinforcement learning task. In the Learning Phase they had to learn the correct stimulus within a stimulus pair on the basis of a probabilistic positive or negative feedback. Three sets of stimulus pairs were used. In the Testing Phase the participants were tested with novel combinations of the stimuli previously experienced to evaluate whether they learned more from positive or negative feedback. PD patients performed the task both ON- and OFF-levodopa in two separate sessions while they remained on stable therapy with dopamine agonists. The electroencephalogram was recorded during the task. PD patients were less accurate in negative than positive learning both OFF- and ON-levodopa. In the OFF-levodopa state they were less accurate than controls in negative learning. PD patients had a smaller ERN amplitude OFF- than ON-levodopa only in negative learning. In the OFF-levodopa state they had a smaller ERN amplitude than controls in negative learning. We hypothesize that high tonic dopaminergic stimulation due to the dopamine agonist medication, combined to the low level of phasic dopamine due to the OFF-levodopa state, could prevent phasic dopamine dips indicated by the ERN needed for learning from negative feedback.

  13. A computational model clarifies the roles of positive and negative feedback loops in the Drosophila circadian clock

    Energy Technology Data Exchange (ETDEWEB)

    Wang Junwei, E-mail: wangjunweilj@yahoo.com.c [Cisco School of Informatics, Guangdong University of Foreign Studies, Guangzhou 510006 (China); Zhou Tianshou [School of Mathematics and Computational Science, Sun Yat-Sen University, Guangzhou 510275 (China)

    2010-06-14

    Previous studies showed that a single negative feedback structure should be sufficient for robust circadian oscillations. It is thus pertinent to ask why current cellular clock models almost universally have interlocked negative feedback loop (NFL) and positive feedback loop (PFL). Here, we propose a molecular model that reflects the essential features of the Drosophila circadian clock to clarify the different roles of negative and positive feedback loops. In agreement with experimental observations, the model can simulate circadian oscillations in constant darkness, entrainment by light-dark cycles, as well as phenotypes of per{sup 01} and clk{sup Jrk} mutants. Moreover, sustained oscillations persist when the PFL is removed, implying the crucial role of NFL for rhythm generation. Through parameter sensitivity analysis, it is revealed that incorporation of PFL increases the robustness of the system to regulatory processes in PFL itself. Such reduced models can aid understanding of the design principles of circadian clocks in Drosophila and other organisms with complex transcriptional feedback structures.

  14. The interplay between feedback-related negativity and individual differences in altruistic punishment: An EEG study.

    Science.gov (United States)

    Mothes, Hendrik; Enge, Sören; Strobel, Alexander

    2016-04-01

    To date, the interplay betwexen neurophysiological and individual difference factors in altruistic punishment has been little understood. To examine this issue, 45 individuals participated in a Dictator Game with punishment option while the feedback-related negativity (FRN) was derived from the electroencephalogram (EEG). Unlike previous EEG studies on the Dictator Game, we introduced a third party condition to study the effect of fairness norm violations in addition to employing a first person perspective. For the first time, we also examined the role of individual differences, specifically fairness concerns, positive/negative affectivity, and altruism/empathy as well as recipients' financial situation during altruistic punishment. The main results show that FRN amplitudes were more pronounced for unfair than for fair assignments in both the first person and third party perspectives. These findings suggest that FRN amplitudes are sensitive to fairness norm violations and play a crucial role in the recipients' evaluation of dictator assignments. With respect to individual difference factors, recipients' current financial situation affected the FRN fairness effect in the first person perspective, indicating that when being directly affected by the assignments, more affluent participants experienced stronger violations of expectations in altruistic punishment decisions. Regarding individual differences in trait empathy, in the third party condition FRN amplitudes were more pronounced for those who scored lower in empathy. This may suggest empathy as another motive in third party punishment. Independent of the perspective taken, higher positive affect was associated with more punishment behavior, suggesting that positive emotions may play an important role in restoring violated fairness norms.

  15. Urocortin3 mediates somatostatin-dependent negative feedback control of insulin secretion.

    Science.gov (United States)

    van der Meulen, Talitha; Donaldson, Cynthia J; Cáceres, Elena; Hunter, Anna E; Cowing-Zitron, Christopher; Pound, Lynley D; Adams, Michael W; Zembrzycki, Andreas; Grove, Kevin L; Huising, Mark O

    2015-07-01

    The peptide hormone urocortin3 (Ucn3) is abundantly expressed by mature beta cells, yet its physiological role is unknown. Here we demonstrate that Ucn3 is stored and co-released with insulin and potentiates glucose-stimulated somatostatin secretion via cognate receptors on delta cells. Further, we found that islets lacking endogenous Ucn3 have fewer delta cells, reduced somatostatin content, impaired somatostatin secretion, and exaggerated insulin release, and that these defects are rectified by treatment with synthetic Ucn3 in vitro. Our observations indicate that the paracrine actions of Ucn3 activate a negative feedback loop that promotes somatostatin release to ensure the timely reduction of insulin secretion upon normalization of plasma glucose. Moreover, Ucn3 is markedly depleted from beta cells in mouse and macaque models of diabetes and in human diabetic islets. This suggests that Ucn3 is a key contributor to stable glycemic control, whose reduction during diabetes aggravates glycemic volatility and contributes to the pathophysiology of this disease.

  16. Effects of delay and noise in a negative feedback regulatory motif

    Science.gov (United States)

    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.

  17. Messenger RNA fluctuations and regulatory RNAs shape the dynamics of a negative feedback loop

    Science.gov (United States)

    Rodríguez Martínez, María; Soriano, Jordi; Tlusty, Tsvi; Pilpel, Yitzhak; Furman, Itay

    2010-03-01

    Single-cell experiments of simple regulatory networks can markedly differ from cell population experiments. Such differences arise from stochastic events in individual cells that are averaged out in cell populations. For instance, while individual cells may show sustained oscillations in the concentrations of some proteins, such oscillations may appear damped in the population average. In this paper we investigate the role of RNA stochastic fluctuations as a leading force to produce a sustained excitatory behavior at the single-cell level. As opposed to some previous models, we build a fully stochastic model of a negative feedback loop that explicitly takes into account the RNA stochastic dynamics. We find that messenger RNA random fluctuations can be amplified during translation and produce sustained pulses of protein expression. Motivated by the recent appreciation of the importance of noncoding regulatory RNAs in post-transcription regulation, we also consider the possibility that a regulatory RNA transcript could bind to the messenger RNA and repress translation. Our findings show that the regulatory transcript helps reducing gene expression variability both at the single-cell level and at the cell population level.

  18. Negative feedback from CaSR signaling to aquaporin-2 sensitizes vasopressin to extracellular Ca2.

    Science.gov (United States)

    Ranieri, Marianna; Tamma, Grazia; Di Mise, Annarita; Russo, Annamaria; Centrone, Mariangela; Svelto, Maria; Calamita, Giuseppe; Valenti, Giovanna

    2015-07-01

    We previously described that high luminal Ca(2+) in the renal collecting duct attenuates short-term vasopressin-induced aquaporin-2 (AQP2) trafficking through activation of the Ca(2+)-sensing receptor (CaSR). Here, we evaluated AQP2 phosphorylation and permeability, in both renal HEK-293 cells and in the dissected inner medullary collecting duct, in response to specific activation of CaSR with NPS-R568. In CaSR-transfected cells, CaSR activation drastically reduced the basal levels of AQP2 phosphorylation at S256 (AQP2-pS256), thus having an opposite effect to vasopressin action. When forskolin stimulation was performed in the presence of NPS-R568, the increase in AQP2-pS256 and in the osmotic water permeability were prevented. In the freshly isolated inner mouse medullar collecting duct, stimulation with forskolin in the presence of NPS-R568 prevented the increase in AQP2-pS256 and osmotic water permeability. Our data demonstrate that the activation of CaSR in the collecting duct prevents the cAMP-dependent increase in AQP2-pS256 and water permeability, counteracting the short-term vasopressin response. By extension, our results suggest the attractive concept that CaSR expressed in distinct nephron segments exerts a negative feedback on hormones acting through cAMP, conferring high sensitivity of hormone to extracellular Ca(2+). © 2015. Published by The Company of Biologists Ltd.

  19. Who Deserves My Trust? Cue-Elicited Feedback Negativity Tracks Reputation Learning in Repeated Social Interactions

    Science.gov (United States)

    Li, Diandian; Meng, Liang; Ma, Qingguo

    2017-01-01

    Trust and trustworthiness contribute to reciprocal behavior and social relationship development. To make better decisions, people need to evaluate others’ trustworthiness. They often assess this kind of reputation by learning through repeated social interactions. The present event-related potential (ERP) study explored the reputation learning process in a repeated trust game where subjects made multi-round decisions of investment to different partners. We found that subjects gradually learned to discriminate trustworthy partners from untrustworthy ones based on how often their partners reciprocated the investment, which was indicated by their own investment decisions. Besides, electrophysiological data showed that the faces of the untrustworthy partners induced larger feedback negativity (FN) amplitude than those of the trustworthy partners, but only in the late phase of the game. The ERP results corresponded with the behavioral pattern and revealed that the learned trustworthiness differentiation was coded by the cue-elicited FN component. Consistent with previous research, our findings suggest that the anterior cue-elicited FN reflects the reputation appraisal and tracks the reputation learning process in social interactions. PMID:28663727

  20. Chronic Psychosocial Stress and Negative Feedback Inhibition: Enhanced Hippocampal Glucocorticoid Signaling despite Lower Cytoplasmic GR Expression.

    Science.gov (United States)

    Füchsl, Andrea M; Reber, Stefan O

    2016-01-01

    Chronic subordinate colony housing (CSC), a pre-clinically validated mouse model for chronic psychosocial stress, results in increased basal and acute stress-induced plasma adrenocorticotropic hormone (ACTH) levels. We assessed CSC effects on hippocampal glucocorticoid (GC) receptor (GR), mineralocorticoid receptor (MR), and FK506 binding protein (FKBP51) expression, acute heterotypic stressor-induced GR translocation, as well as GC effects on gene expression and cell viability in isolated hippocampal cells. CSC mice showed decreased GR mRNA and cytoplasmic protein levels compared with single-housed control (SHC) mice. Basal and acute stress-induced nuclear GR protein expression were comparable between CSC and SHC mice, as were MR and FKBP51 mRNA and/or cytoplasmic protein levels. In vitro the effect of corticosterone (CORT) on hippocampal cell viability and gene transcription was more pronounced in CSC versus SHC mice. In summary, CSC mice show an, if at all, increased hippocampal GC signaling capacity despite lower cytoplasmic GR protein expression, making negative feedback deficits in the hippocampus unlikely to contribute to the increased ACTH drive following CSC.

  1. A Negative Feedback Between Anthropogenic Ozone Pollution and Enhanced Ocean Emissions of Iodine

    Science.gov (United States)

    Saiz-Lopez, A.; Prados-Roman, C.; Cuevas, C.; Fernandez, R.; Lamarque, J. F.; Kinnison, D. E.

    2014-12-01

    Naturally emitted from the oceans, iodine compounds efficiently destroy atmospheric ozone and reduce its positive radiative forcing effects in the troposphere. Emissions of inorganic iodine have been experimentally shown to depend on the deposition to the oceans of tropospheric ozone, whose concentrations have significantly increased since 1850 as a result of human activities. A chemistry-climate model is used to quantify the current ocean emissions of inorganic iodine and assess the impact that the anthropogenic increase of tropospheric ozone has had on the natural cycle of iodine in the marine environment since pre-industrial times. Results included in this communication indicate that the human-driven enhancement of tropospheric ozone has doubled the oceanic inorganic iodine emissions following the reaction of ozone with iodide at the sea surface. The consequent build-up of atmospheric iodine, with maximum enhancements of up to 70% with respect to preindustrial times in continental pollution outflow regions, has in turn accelerated the ozone chemical loss over the oceans with strong spatial patterns. We suggest that this ocean-atmosphere interaction represents a negative geochemical feedback loop by which current ocean emissions of iodine act as a natural buffer for ozone pollution and its radiative forcing in the global marine environment.

  2. Negative Feedback Effect of Microwave Irradiation in the Microwave—assisted Hydrothermal Synthesis of Bi2S3 Nanorods

    Institute of Scientific and Technical Information of China (English)

    陶秀成; 邵名望

    2002-01-01

    The microwave-assisted hydrothermal synthesis of Bi2S3 nanorods was reported.The result showed that microwave irradiation can help to produce Bi2S3 nanorods in very short time.There is a negative feedback effcet which increases the degree of crystallinity in the reaction.

  3. Negative Feedback Effect of Microwave Irradiation in the Microwave-assisted Hydrothermal Synthesis of Bi2S3 Nanorods

    Institute of Scientific and Technical Information of China (English)

    TAO,Xiu-Cheng(陶秀成); SHAO,Ming-Wang(邵名望)

    2002-01-01

    The microwave-assisted hydrothermal synthesis of Bi2S3 nanorods was reported. The result showed that microwave irradiation can help to produce Bi2S3 nanorods in very short time.There is a negative feedback effect which increases the degree of crystallinity in the reaction.

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

    Science.gov (United States)

    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.

  5. Attractivity in a Delayed Three-species Ratio-dependent Predator-prey System without Dominating Instantaneous Negative Feedback

    Institute of Scientific and Technical Information of China (English)

    Rui Xu; Lan-sun Chen; M.A.J. Chaplain

    2003-01-01

    A delayed three-species ratio-dependent predator-prey food-chain model without dominating instantaneous negative feedback is investigated. It is shown that the system is permanent under some appropriate conditions, and sufficient conditions are derived for the global attractivity of the positive equilibrium of the system.

  6. Inhibitory and toxic effects of extracellular self-DNA in litter : A mechanism for negative plant-soil feedbacks?

    NARCIS (Netherlands)

    Mazzoleni, Stefano; Bonanomi, Giuliano; Incerti, Guido; Chiusano, Maria Luisa; Termolino, Pasquale; Mingo, Antonio; Senatore, Mauro; Giannino, Francesco; Cartenì, Fabrizio; Rietkerk, Max; Lanzotti, Virginia

    2015-01-01

    Plant-soil negative feedback (NF) is recognized as an important factor affecting plant communities. The objectives of this work were to assess the effects of litter phytotoxicity and autotoxicity on root proliferation, and to test the hypothesis that DNA is a driver of litter autotoxicity and plant-

  7. Clustering and negative feedback by endocytosis in planar cell polarity signaling is modulated by ubiquitinylation of prickle.

    Science.gov (United States)

    Cho, Bomsoo; Pierre-Louis, Gandhy; Sagner, Andreas; Eaton, Suzanne; Axelrod, Jeffrey D

    2015-05-01

    The core components of the planar cell polarity (PCP) signaling system, including both transmembrane and peripheral membrane associated proteins, form asymmetric complexes that bridge apical intercellular junctions. While these can assemble in either orientation, coordinated cell polarization requires the enrichment of complexes of a given orientation at specific junctions. This might occur by both positive and negative feedback between oppositely oriented complexes, and requires the peripheral membrane associated PCP components. However, the molecular mechanisms underlying feedback are not understood. We find that the E3 ubiquitin ligase complex Cullin1(Cul1)/SkpA/Supernumerary limbs(Slimb) regulates the stability of one of the peripheral membrane components, Prickle (Pk). Excess Pk disrupts PCP feedback and prevents asymmetry. We show that Pk participates in negative feedback by mediating internalization of PCP complexes containing the transmembrane components Van Gogh (Vang) and Flamingo (Fmi), and that internalization is activated by oppositely oriented complexes within clusters. Pk also participates in positive feedback through an unknown mechanism promoting clustering. Our results therefore identify a molecular mechanism underlying generation of asymmetry in PCP signaling.

  8. Negative feedback governs gonadotrope frequency-decoding of gonadotropin releasing hormone pulse-frequency.

    Directory of Open Access Journals (Sweden)

    Stefan Lim

    Full Text Available The synthesis of the gonadotropin subunits is directed by pulsatile gonadotropin-releasing hormone (GnRH from the hypothalamus, with the frequency of GnRH pulses governing the differential expression of the common alpha-subunit, luteinizing hormone beta-subunit (LHbeta and follicle-stimulating hormone beta-subunit (FSHbeta. Three mitogen-activated protein kinases, (MAPKs, ERK1/2, JNK and p38, contribute uniquely and combinatorially to the expression of each of these subunit genes. In this study, using both experimental and computational methods, we found that dual specificity phosphatase regulation of the activity of the three MAPKs through negative feedback is required, and forms the basis for decoding the frequency of pulsatile GnRH. A fourth MAPK, ERK5, was shown also to be activated by GnRH. ERK5 was found to stimulate FSHbeta promoter activity and to increase FSHbeta mRNA levels, as well as enhancing its preference for low GnRH pulse frequencies. The latter is achieved through boosting the ultrasensitive behavior of FSHbeta gene expression by increasing the number of MAPK dependencies, and through modulating the feedforward effects of JNK activation on the GnRH receptor (GnRH-R. Our findings contribute to understanding the role of changing GnRH pulse-frequency in controlling transcription of the pituitary gonadotropins, which comprises a crucial aspect in regulating reproduction. Pulsatile stimuli and oscillating signals are integral to many biological processes, and elucidation of the mechanisms through which the pulsatility is decoded explains how the same stimulant can lead to various outcomes in a single cell.

  9. The stress-buffering effect of acute exercise: Evidence for HPA axis negative feedback.

    Science.gov (United States)

    Zschucke, Elisabeth; Renneberg, Babette; Dimeo, Fernando; Wüstenberg, Torsten; Ströhle, Andreas

    2015-01-01

    According to the cross-stressor adaptation hypothesis, physically trained individuals show lower physiological and psychological responses to stressors other than exercise, e.g. psychosocial stress. Reduced stress reactivity may constitute a mechanism of action for the beneficial effects of exercise in maintaining mental health. With regard to neural and psychoneuroendocrine stress responses, the acute stress-buffering effects of exercise have not been investigated yet. A sample of highly trained (HT) and sedentary (SED) young men was randomized to either exercise on a treadmill at moderate intensity (60-70% VO2max; AER) for 30 min, or to perform 30 min of "placebo" exercise (PLAC). 90 min later, an fMRI experiment was conducted using an adapted version of the Montreal Imaging Stress Task (MIST). The subjective and psychoneuroendocrine (cortisol and α-amylase) changes induced by the exercise intervention and the MIST were assessed, as well as neural activations during the MIST. Finally, associations between the different stress responses were analysed. Participants of the AER group showed a significantly reduced cortisol response to the MIST, which was inversely related to the previous exercise-induced α-amylase and cortisol fluctuations. With regard to the sustained BOLD signal, we found higher bilateral hippocampus (Hipp) activity and lower prefrontal cortex (PFC) activity in the AER group. Participants with a higher aerobic fitness showed lower cortisol responses to the MIST. As the Hipp and PFC are brain structures prominently involved in the regulation of the hypothalamus-pituitary-adrenal (HPA) axis, these findings indicate that the acute stress-buffering effect of exercise relies on negative feedback mechanisms. Positive affective changes after exercise appear as important moderators largely accounting for the effects related to physical fitness.

  10. The apparent paradox of the negative and positive feedback control system on gonadotropin secretion.

    Science.gov (United States)

    Yen, S S; Lein, A

    1976-12-01

    The separate and interactive effects of estradiol (E2) and luteinizing hormone-releasing factor (LRF) on the dynamics of LH storage and release were studied. Measurements were made of the serum gonadotropin responses to submaximal doses of LRF, given as brief pulses or infused over an extended period to normal women at various stages of the follicular phase of their menstrual cycles and to hypogonadal women with and without estrogen treatment. The two-pool concept of pituitary gonadotropin was verified; the dynamic responses of the two pools to the inputs of LRF and E2 were investigated and related to pituitary properties of sensitivity and reserve. Our results indicate that LRF appears to serve as a primary drive on the gonadotrophs, stimulating gonadotropin synthesis and storage (second pool), as well as release (first). E2 for the most part, amplifies the action of LRF except that it impedes LRF-induced release of gonadotropin. E2 augments the second pool activity (reserve) preferentially, and the relative activity of the first pool appears to be influenced by the E2-dependent self-priming effect of LRF. The interactions of the various elements of the system, when combined, provide a U-shaped curve to describe the over-all capacity of the gonadotrophs as a function of a broad range of E2 inputs. Negative and possitive feedback of E2 are revealed to operate by different mechanisms and to represent different segments of a single U-shaped curve rather than paradoxically disparate actions.

  11. Phasic Firing and Coincidence Detection by Subthreshold Negative Feedback: Divisive or Subtractive or, Better, Both

    Science.gov (United States)

    Huguet, Gemma; Meng, Xiangying; Rinzel, John

    2017-01-01

    Phasic neurons typically fire only for a fast-rising input, say at the onset of a step current, but not for steady or slow inputs, a property associated with type III excitability. Phasic neurons can show extraordinary temporal precision for phase locking and coincidence detection. Exemplars are found in the auditory brain stem where precise timing is used in sound localization. Phasicness at the cellular level arises from a dynamic, voltage-gated, negative feedback that can be recruited subthreshold, preventing the neuron from reaching spike threshold if the voltage does not rise fast enough. We consider two mechanisms for phasicness: a low threshold potassium current (subtractive mechanism) and a sodium current with subthreshold inactivation (divisive mechanism). We develop and analyze three reduced models with either divisive or subtractive mechanisms or both to gain insight into the dynamical mechanisms for the potentially high temporal precision of type III-excitable neurons. We compare their firing properties and performance for a range of stimuli. The models have characteristic non-monotonic input-output relations, firing rate vs. input intensity, for either stochastic current injection or Poisson-timed excitatory synaptic conductance trains. We assess performance according to precision of phase-locking and coincidence detection by the models' responses to repetitive packets of unitary excitatory synaptic inputs with more or less temporal coherence. We find that each mechanism contributes features but best performance is attained if both are present. The subtractive mechanism confers extraordinary precision for phase locking and coincidence detection but only within a restricted parameter range when the divisive mechanism of sodium inactivation is inoperative. The divisive mechanism guarantees robustness of phasic properties, without compromising excitability, although with somewhat less precision. Finally, we demonstrate that brief transient inhibition if

  12. The Arcuate Nucleus: A Site of Fast Negative Feedback for Corticosterone Secretion in Male Rats

    Science.gov (United States)

    Kawata, Mitsuhiro; Escobar, Carolina

    2017-01-01

    Abstract Variations in circulating corticosterone (Cort) are driven by the paraventricular nucleus of the hypothalamus (PVN), mainly via the sympathetic autonomic nervous system (ANS) directly stimulating Cort release from the adrenal gland and via corticotropin-releasing hormone targeting the adenohypophysis to release adrenocorticotropic hormone (ACTH). Cort feeds back through glucocorticoid receptors (GRs). Here we show in male Wistar rats that PVN neurons projecting to the adrenal gland do not express GRs, leaving the question of how the ANS in the PVN gets information about circulating Cort levels to control the adrenal. Since the arcuate nucleus (ARC) shows a less restrictive blood–brain barrier, expresses GRs, and projects to the PVN, we investigated whether the ARC can detect and produce fast adjustments of circulating Cort. In low Cort conditions (morning), local microdialysis in the ARC with type I GR antagonist produced a fast and sustained increase of Cort. This was not observed with a type II antagonist. At the circadian peak levels of Cort (afternoon), a type II GR antagonist, but not a type I antagonist, increased Cort levels but not ACTH levels. Antagonist infusions in the PVN did not modify circulating Cort levels, demonstrating the specificity of the ARC to give Cort negative feedback. Furthermore, type I and II GR agonists in the ARC prevented the increase of Cort after stress, demonstrating the role of the ARC as sensor to modulate Cort release. Our findings show that the ARC may be essential to sense blood levels of Cort and adapt Cort secretion depending on such conditions as stress or time of day. PMID:28275717

  13. Negative feedback governs gonadotrope frequency-decoding of gonadotropin releasing hormone pulse-frequency.

    Science.gov (United States)

    Lim, Stefan; Pnueli, Lilach; Tan, Jing Hui; Naor, Zvi; Rajagopal, Gunaretnam; Melamed, Philippa

    2009-09-29

    The synthesis of the gonadotropin subunits is directed by pulsatile gonadotropin-releasing hormone (GnRH) from the hypothalamus, with the frequency of GnRH pulses governing the differential expression of the common alpha-subunit, luteinizing hormone beta-subunit (LHbeta) and follicle-stimulating hormone beta-subunit (FSHbeta). Three mitogen-activated protein kinases, (MAPKs), ERK1/2, JNK and p38, contribute uniquely and combinatorially to the expression of each of these subunit genes. In this study, using both experimental and computational methods, we found that dual specificity phosphatase regulation of the activity of the three MAPKs through negative feedback is required, and forms the basis for decoding the frequency of pulsatile GnRH. A fourth MAPK, ERK5, was shown also to be activated by GnRH. ERK5 was found to stimulate FSHbeta promoter activity and to increase FSHbeta mRNA levels, as well as enhancing its preference for low GnRH pulse frequencies. The latter is achieved through boosting the ultrasensitive behavior of FSHbeta gene expression by increasing the number of MAPK dependencies, and through modulating the feedforward effects of JNK activation on the GnRH receptor (GnRH-R). Our findings contribute to understanding the role of changing GnRH pulse-frequency in controlling transcription of the pituitary gonadotropins, which comprises a crucial aspect in regulating reproduction. Pulsatile stimuli and oscillating signals are integral to many biological processes, and elucidation of the mechanisms through which the pulsatility is decoded explains how the same stimulant can lead to various outcomes in a single cell.

  14. Effects of spike-triggered negative feedback on receptive-field properties.

    Science.gov (United States)

    Urdapilleta, Eugenio; Samengo, Inés

    2015-04-01

    Sensory neurons are often described in terms of a receptive field, that is, a linear kernel through which stimuli are filtered before they are further processed. If information transmission is assumed to proceed in a feedforward cascade, the receptive field may be interpreted as the external stimulus' profile maximizing neuronal output. The nervous system, however, contains many feedback loops, and sensory neurons filter more currents than the ones representing the transduced external stimulus. Some of the additional currents are generated by the output activity of the neuron itself, and therefore constitute feedback signals. By means of a time-frequency analysis of the input/output transformation, here we show how feedback modifies the receptive field. The model is applicable to various types of feedback processes, from spike-triggered intrinsic conductances to inhibitory synaptic inputs from nearby neurons. We distinguish between the intrinsic receptive field (filtering all input currents) and the effective receptive field (filtering only external stimuli). Whereas the intrinsic receptive field summarizes the biophysical properties of the neuron associated to subthreshold integration and spike generation, only the effective receptive field can be interpreted as the external stimulus' profile maximizing neuronal output. We demonstrate that spike-triggered feedback shifts low-pass filtering towards band-pass processing, transforming integrator neurons into resonators. For strong feedback, a sharp resonance in the spectral neuronal selectivity may appear. Our results provide a unified framework to interpret a collection of previous experimental studies where specific feedback mechanisms were shown to modify the filtering properties of neurons.

  15. Performance characteristics of positive and negative delayed feedback on chaotic dynamics of directly modulated InGaAsP semiconductor lasers

    Indian Academy of Sciences (India)

    Bindu M Krishna; Manu P John; V M Nandakumaran

    2008-12-01

    The chaotic dynamics of directly modulated semiconductor lasers with delayed optoelectronic feedback is studied numerically. The effects of positive and negative delayed optoelectronic feedback in producing chaotic outputs from such lasers with nonlinear gain reduction in its optimum value range is investigated using bifurcation diagrams. The results are confirmed by calculating the Lyapunov exponents. A negative delayed optoelectronic feedback configuration is found to be more effective in inducing chaotic dynamics to such systems with nonlinear gain reduction factor in the practical value range.

  16. A general non-equilibrium framework for the parameterization of positive and negative feedbacks in atmospheric systems

    Science.gov (United States)

    Garrett, T. J.

    2012-12-01

    For any identifiable system, regardless of its complexity or scale, evolution can be treated as a spontaneous thermodynamic response to a local convergence of down-gradient material flows. In climate studies, examples of identifiable systems might include cloud cover or the global incidence of temperatures warmer than a certain threshold. Here it is shown how the time-dependent evolution of such systems is constrained by positive and negative feedbacks that fall into a few mathematically distinct modes. In general, evolution depends on the time integral of past flows and the current availability of material and energetic resources. More specifically, negative feedbacks arise from the depletion or predation of the material and potential energy reservoirs that supply the system. Positive feedbacks are due to either new reservoir "discovery" or system expansion into existing reservoirs. When positive feedbacks dominate, the time dependent response of system growth falls into a few clearly identifiable behaviors that include a law of diminishing returns, logistic behavior, and, if reservoirs are expanding very rapidly, unstable super-exponential or explosive growth. For open systems (e.g. radiative flows in our atmosphere) that have a resolved sink as well as a source, oscillatory behavior emerges and can be characterized in terms of a slightly modified form of the predator-prey equations commonly employed in ecology. The perturbation formulation of these equations is equivalent to a damped simple harmonic oscillator. Specific examples of non-equilibrium positive and negative feedback response can be described for the sudden development of rain and the oscillatory evolution of open-celled stratocumulus cloud decks.

  17. Two different modes of oscillation in a gene transcription regulatory network with interlinked positive and negative feedback loops

    Science.gov (United States)

    Karmakar, Rajesh

    2016-12-01

    We study the oscillatory behavior of a gene regulatory network with interlinked positive and negative feedback loop. The frequency and amplitude are two important properties of oscillation. The studied network produces two different modes of oscillation. In one mode (mode-I), frequency of oscillation remains constant over a wide range of amplitude and in the other mode (mode-II) the amplitude of oscillation remains constant over a wide range of frequency. Our study reproduces both features of oscillations in a single gene regulatory network and shows that the negative plus positive feedback loops in gene regulatory network offer additional advantage. We identified the key parameters/variables responsible for different modes of oscillation. The network is flexible in switching between different modes by choosing appropriately the required parameters/variables.

  18. CaV3.2 Channels and the Induction of Negative Feedback in Cerebral Arteries

    Science.gov (United States)

    Harraz, Osama F.; Abd El-Rahman, Rasha R.; Bigdely-Shamloo, Kamran; Wilson, Sean M.; Brett, Suzanne E.; Romero, Monica; Gonzales, Albert L.; Earley, Scott; Vigmond, Edward J.; Nygren, Anders; Menon, Bijoy K.; Mufti, Rania E.; Watson, Tim; Starreveld, Yves; Furstenhaupt, Tobias; Muellerleile, Philip R.; Kurjiaka, David T.; Kyle, Barry D.; Braun, Andrew P.; Welsh, Donald G.

    2015-01-01

    Rationale T-type (CaV3.1/CaV3.2) Ca2+ channels are expressed in rat cerebral arterial smooth muscle. Although present, their functional significance remains uncertain with findings pointing to a variety of roles. Objective This study tested whether CaV3.2 channels mediate a negative feedback response by triggering Ca2+ sparks, discrete events that initiate arterial hyperpolarization by activating large-conductance Ca2+-activated K+ channels. Methods and Results Micromolar Ni2+, an agent that selectively blocks CaV3.2 but not CaV1.2/CaV3.1, was first shown to depolarize/constrict pressurized rat cerebral arteries; no effect was observed in CaV3.2−/− arteries. Structural analysis using 3-dimensional tomography, immunolabeling, and a proximity ligation assay next revealed the existence of microdomains in cerebral arterial smooth muscle which comprised sarcoplasmic reticulum and caveolae. Within these discrete structures, CaV3.2 and ryanodine receptor resided in close apposition to one another. Computational modeling revealed that Ca2+ influx through CaV3.2 could repetitively activate ryanodine receptor, inducing discrete Ca2+-induced Ca2+ release events in a voltage-dependent manner. In keeping with theoretical observations, rapid Ca2+ imaging and perforated patch clamp electrophysiology demonstrated that Ni2+ suppressed Ca2+ sparks and consequently spontaneous transient outward K+ currents, large-conductance Ca2+-activated K+ channel mediated events. Additional functional work on pressurized arteries noted that paxilline, a large-conductance Ca2+-activated K+ channel inhibitor, elicited arterial constriction equivalent, and not additive, to Ni2+. Key experiments on human cerebral arteries indicate that CaV3.2 is present and drives a comparable response to moderate constriction. Conclusions These findings indicate for the first time that CaV3.2 channels localize to discrete microdomains and drive ryanodine receptor–mediated Ca2+ sparks, enabling large

  19. The Effects of Positive and Negative Feedback on Maximal Voluntary Contraction Level of the Biceps Brachii Muscle: Moderating Roles of Gender and Conscientiousness.

    Science.gov (United States)

    Sarıkabak, Murat; Yaman, Çetin; Tok, Serdar; Binboga, Erdal

    2016-11-02

    We investigated the effect of positive and negative feedback on maximal voluntary contraction (MVC) of the biceps brachii muscle and explored the mediating effects of gender and conscientiousness. During elbow flexion, MVCs were measured in positive, negative, and no-feedback conditions. Participants were divided into high- and low-conscientiousness groups based on the median split of their scores on Tatar's five-factor personality inventory. Considering all participants 46 college student athletes (21 female, 28 male), positive feedback led to a greater MVC percentage change (-5.76%) than did negative feedback (2.2%). MVC percentage change in the positive feedback condition differed significantly by gender, but the negative feedback condition did not. Thus, positive feedback increased female athletes' MVC level by 3.49%, but decreased male athletes' MVC level by 15.6%. For conscientiousness, MVC percentage change in the positive feedback condition did not differ according to high and low conscientiousness. However, conscientiousness interacted with gender in the positive feedback condition, increasing MVC in high-conscientiousness female athletes and decreasing MVC in low-conscientiousness female athletes. Positive feedback decreased MVC in both high- and low-conscientiousness male athletes.

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

    Science.gov (United States)

    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.

  1. A negative-feedback loop regulating ERK1/2 activation and mediated by RasGPR2 phosphorylation

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Jinqi [Departments of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599 (United States); Cook, Aaron A.; Bergmeier, Wolfgang [Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC 27599 (United States); Sondek, John, E-mail: sondek@med.unc.edu [Departments of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599 (United States); Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC 27599 (United States); Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599 (United States)

    2016-05-20

    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–ERK 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.

  2. Positive or negative? The impact of X-ray feedback on the formation of direct collapse black hole seeds

    Science.gov (United States)

    Regan, John A.; Johansson, Peter H.; Wise, John H.

    2016-09-01

    A nearby source of Lyman-Werner (LW) photons is thought to be a central component in dissociating H2 and allowing for the formation of a direct collapse black hole seed. Nearby sources are also expected to produce copious amounts of hydrogen ionizing photons and X-ray photons. We study here the feedback effects of the X-ray photons by including a spectrum due to high-mass X-ray binaries on top of a galaxy with a stellar spectrum. We explicitly trace photon packages emerging from the nearby source and track the radiative and chemical effects of the multifrequency source (Ephoton = 0.76 eV → 7500 eV). We find that X-rays have a strongly negative feedback effect, compared to a stellar only source, when the radiative source is placed at a separation greater than ≳ 1 kpc. The X-rays heat the low and medium density gas in the envelope surrounding the collapsing halo suppressing the mass inflow. The result is a smaller enclosed mass compared to the stellar only case. However, for separations of ≲ 1 kpc, the feedback effects of the X-rays becomes somewhat neutral. The enhanced LW intensity at close separations dissociates more H2 and this gas is heated due to stellar photons alone, the addition of X-rays is then not significant. This distance dependence of X-ray feedback suggests that a Goldilocks zone exists close to a forming galaxy where X-ray photons have a much smaller negative feedback effect and ideal conditions exist for creating massive black hole seeds.

  3. Influences of State and Trait Affect on Behavior, Feedback-Related Negativity, and P3b in the Ultimatum Game.

    Directory of Open Access Journals (Sweden)

    Korbinian Riepl

    Full Text Available 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

  4. Influences of State and Trait Affect on Behavior, Feedback-Related Negativity, and P3b in the Ultimatum Game.

    Science.gov (United States)

    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

  5. Development of a low noise induction magnetic sensor using magnetic flux negative feedback in the time domain.

    Science.gov (United States)

    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.

  6. The near-miss effect in slot-machine gambling: modulation of feedback-related negativity by subjective value.

    Science.gov (United States)

    Luo, Qiuling; Wang, Yang; Qu, Chen

    2011-12-21

    Near-miss plays an important role in the development of gambling addictions. In this study, we measured the neural correlates of the process by which near-miss outcomes are evaluated in simplified, static, slot-machine gambling using event-related potentials. Analysis of event-related potentials revealed that the size of FRN (feedback-related negativity) for a near miss is between the full miss and the win. These results suggest that participants distinguish among near misses, full misses, and wins during the early evaluation phase. The subjective value and objective value of outcome were assessed separately to discuss FRN on outcome evaluation. It is suggested that FRN is mediated not only by the objective value of outcomes but also by the subjective value of feedback.

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

    Science.gov (United States)

    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

  8. Nonlinearity arising from noncooperative transcription factor binding enhances negative feedback and promotes genetic oscillations

    CERN Document Server

    Lengyel, Iván M; Oates, Andrew C; Morelli, Luis G

    2015-01-01

    We study the effects of multiple binding sites in the promoter of a genetic oscillator. We evaluate the regulatory function of a promoter with multiple binding sites in the absence of cooperative binding, and consider different hypotheses for how the number of bound repressors affects transcription rate. Effective Hill exponents of the resulting regulatory functions reveal an increase in the nonlinearity of the feedback with the number of binding sites. We identify optimal configurations that maximize the nonlinearity of the feedback. We use a generic model of a biochemical oscillator to show that this increased nonlinearity is reflected in enhanced oscillations, with larger amplitudes over wider oscillatory ranges. Although the study is motivated by genetic oscillations in the zebrafish segmentation clock, our findings may reveal a general principle for gene regulation.

  9. Blowin' in the wind: both `negative' and `positive' feedback in an obscured high-z Quasar

    CERN Document Server

    Cresci, G; Brusa, M; Marconi, A; Perna, M; Mannucci, F; Piconcelli, E; Maiolino, R; Feruglio, C; Fiore, F; Bongiorno, A; Lanzuisi, G; Merloni, A; Schramm, M; Silverman, J D; Civano, F

    2014-01-01

    Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation in galaxies, 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. Here we present SINFONI near infrared integral field spectroscopy of XID2028, an obscured, radio-quiet z=1.59 QSO detected in the XMM-COSMOS survey, 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 Ha emission and the re...

  10. Limitation of immune tolerance-inducing thymic epithelial cell development by Spi-B-mediated negative feedback regulation.

    Science.gov (United States)

    Akiyama, Nobuko; Shinzawa, Miho; Miyauchi, Maki; Yanai, Hiromi; Tateishi, Ryosuke; Shimo, Yusuke; Ohshima, Daisuke; Matsuo, Koichi; Sasaki, Izumi; Hoshino, Katsuaki; Wu, Guoying; Yagi, Shintaro; Inoue, Jun-ichiro; Kaisho, Tsuneyasu; Akiyama, Taishin

    2014-11-17

    Medullary thymic epithelial cells (mTECs) expressing the autoimmune regulator AIRE and various tissue-specific antigens (TSAs) are critical for preventing the onset of autoimmunity and may attenuate tumor immunity. However, molecular mechanisms controlling mTEC development remain elusive. Here, we describe the roles of the transcription factor Spi-B in mTEC development. Spi-B is rapidly up-regulated by receptor activator of NF-κB ligand (RANKL) cytokine signaling, which triggers mTEC differentiation, and in turn up-regulates CD80, CD86, some TSAs, and the natural inhibitor of RANKL signaling, osteoprotegerin (OPG). Spi-B-mediated OPG expression limits mTEC development in neonates but not in embryos, suggesting developmental stage-specific negative feedback regulation. OPG-mediated negative regulation attenuates cellularity of thymic regulatory T cells and tumor development in vivo. Hence, these data suggest that this negative RANKL-Spi-B-OPG feedback mechanism finely tunes mTEC development and function and may optimize the trade-off between prevention of autoimmunity and induction of antitumor immunity.

  11. Arctic shelf flooding: a negative feedback on climate warming during terminations

    Science.gov (United States)

    Blaschek, Michael; Renssen, Hans

    2013-04-01

    heat release and surface warming during the entire year. Our analysis exhibits a surprising connection between increased sea-ice export through Fram Strait and changes in atmospheric winds that result from modifications in the atmospheric circulation, that are forced by changes in differential heating over the East Siberian Shelf and the Nordic Seas. This atmospheric teleconnection clearly shows that regional changes can affect hemispheric changes. In a first comparison with available sea-ice proxy reconstructions our results do not disagree, but show the necessity of increased temporal and spatial coverage of proxy reconstructions for future investigations. Our results indicate that shelf flooding had a significant impact on the climate during the early Holocene, namely reducing sea-ice cover and affecting atmospheric circulation. During terminations this can be considered to be a negative feedback on the progress of the termination, as a shelf area becomes flooded, sea-ice production and extent are likely to increase and reduce high latitude intake of orbitally-forced insolation, slowing down the warming trend. This can be the cause of observed cold reversals during warming phases in the continuous transformation of a glacial to an interglacial climate. This implies that shelf flooding should be taken into account when studying the climate dynamics during all glacial terminations. References Bauch, H.; Mueller-Lupp, T.; Taldenkova, E.; Spielhagen, R.; Kassens, H.; Grootes, P.; Thiede, J.; Heinemeier, J. & Petryashov, V. Chronology of the Holocene transgression at the North Siberian margin, Global and Planetary Change, 2001, 31, 125 - 139 Rigor, I. & Colony, R., Sea-ice production and transport of pollutants in the Laptev Sea, 1979-1993, Science of The Total Environment, Environmental Radioactivity in the Arctic, 1997, 202, 89-110 Tamura, T. & Ohshima, K. I., Mapping of sea ice production in the Arctic coastal polynyas, J. Geophys. Res., AGU, 2011, 116, C07030-

  12. FY 14 interim report : Evaluation of treatments to mitigate negative plant-soil feedbacks and improve reconstruction seeding success at Kulm Wetland Management District

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Interim report for fiscal year 2014 on the research "Evaluation of treatments to mitigate negative plant-soil feedbacks and improve reconstruction seeding success at...

  13. Microwave oscillator with reduced phase noise by negative feedback incorporating microwave signals with suppressed carrier

    Science.gov (United States)

    Dick, G. J.; Saunders, J.

    1989-01-01

    Oscillator configurations which reduce the effect of 1/f noise sources for both direct feedback and stabilized local oscillator (STALO) circuits are developed and analyzed. By appropriate use of carrier suppression, a small signal is generated which suffers no loss of loop phase information or signal-to-noise ratio. This small signal can be amplified without degradation by multiplicative amplifier noise, and can be detected without saturation of the detector. Together with recent advances in microwave resonator Qs, these circuit improvements will make possible lower phase noise than can be presently achieved without the use of cryogenic devices.

  14. Fast negative feedback enables mammalian auditory nerve fibers to encode a wide dynamic range of sound intensities.

    Directory of Open Access Journals (Sweden)

    Mark Ospeck

    Full Text Available Mammalian auditory nerve fibers (ANF are remarkable for being able to encode a 40 dB, or hundred fold, range of sound pressure levels into their firing rate. Most of the fibers are very sensitive and raise their quiescent spike rate by a small amount for a faint sound at auditory threshold. Then as the sound intensity is increased, they slowly increase their spike rate, with some fibers going up as high as ∼300 Hz. In this way mammals are able to combine sensitivity and wide dynamic range. They are also able to discern sounds embedded within background noise. ANF receive efferent feedback, which suggests that the fibers are readjusted according to the background noise in order to maximize the information content of their auditory spike trains. Inner hair cells activate currents in the unmyelinated distal dendrites of ANF where sound intensity is rate-coded into action potentials. We model this spike generator compartment as an attenuator that employs fast negative feedback. Input current induces rapid and proportional leak currents. This way ANF are able to have a linear frequency to input current (f-I curve that has a wide dynamic range. The ANF spike generator remains very sensitive to threshold currents, but efferent feedback is able to lower its gain in response to noise.

  15. Observational evidence that positive and negative AGN feedback depends on galaxy mass and jet power

    Science.gov (United States)

    Kalfountzou, E.; Stevens, J. A.; Jarvis, M. J.; Hardcastle, M. J.; Wilner, D.; Elvis, M.; Page, M. J.; Trichas, M.; Smith, D. J. B.

    2017-10-01

    Several studies support the existence of a link between the active galactic nucleus (AGN) and star formation activity. Radio jets have been argued to be an ideal mechanism for direct interaction between the AGN and the host galaxy. A drawback of previous surveys of AGN is that they are fundamentally limited by the degeneracy between redshift and luminosity in flux-density limited samples. To overcome this limitation, we present far-infrared Herschel observations of 74 radio-loud quasars (RLQs), 72 radio-quiet quasars (RQQs) and 27 radio galaxies (RGs), selected at 0.9 correlation with the bolometric luminosity for all AGN sub-samples, (2) the RLQs show an SFR excess of about a factor of 1.4 compared to the RQQs, matched in terms of black hole mass and bolometric luminosity, suggesting that either positive radio-jet feedback or radio AGN triggering is linked to star formation triggering, and (3) RGs have lower SFRs by a factor of 2.5 than the RLQ sub-sample with the same BH mass and bolometric luminosity. We suggest that there is some jet power threshold at which radio-jet feedback switches from enhancing star formation (by compressing gas) to suppressing it (by ejecting gas). This threshold depends on both galaxy mass and jet power.

  16. miR-486 sustains NF-κB activity by disrupting multiple NF-κB-negative feedback loops

    Institute of Scientific and Technical Information of China (English)

    Libing Song; Chuyong Lin; Hui Gong; Chanjuan Wang; Liping Liu; Jueheng Wu; Sha Tao

    2013-01-01

    Deubiquitinases,such as CYLD,A20 and Cezanne,have emerged as important negative regulators that balance the strength and the duration of NF-κB signaling through feedback mechanisms.However,how these serial feedback loops are simultaneously disrupted in cancers,which commonly exhibit constitutively activated NF-κB,remains puzzling.Herein,we report that miR-486 directly suppresses NF-κB-negative regulators,CYLD and Cezanne,as well as multiple A20 activity regulators,including ITCH,TNIP-1,TNIP-2 and TNIP-3,resulting in promotion of ubiquitin conjugations in NF-κB signaling and sustained NF-κB activity.Furthermore,we demonstrate that upregulation of miR-486 promotes glioma aggressiveness both in vitro and in vivo through activation of NF-κB signaling pathway.Importantly,miR-486 levels in primary gliomas significantly correlate with NF-κB activation status.These findings uncover a novel mechanism for constitutive NF-κB activation in gliomas and support a functionally and clinically relevant epigenetic mechanism in cancer progression.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  19. Free Running Single Photon Detection based on a negative feedback InGaAs APD

    CERN Document Server

    Lunghi, Tommaso; Guinnard, Olivier; Houlmann, Raphael; Jiang, Xudong; Itzler, Mark A; Zbinden, Hugo

    2012-01-01

    InGaAs/InP-based semiconductor avalanche photodiode are usually employed for single-photon counting at telecom wavelength. However they are affected by afterpulsing which limits the diode performance. Recently, Princeton Lightwave has commercialised a diode integrating monolithically a feedback resistor. This solution effectively quenches the avalanche and drastically reduces afterpulsing. Here, we report the development and characterization of a detector module based on this diode, implementing an active hold-off circuit which further reduces the afterpulsing and notably improves the detector performances. We demonstrate free-running operation with 600 Hz dark count rate at 10% detection efficiency. We also improved the standard double-window technique for the afterpulsing characterization. Our algorithm implemented by a FPGA allows to put the APD in a well-defined initial condition and to measure the impact of the higher order afterpulses.

  20. mTORC1 Is a Local, Postsynaptic Voltage Sensor Regulated by Positive and Negative Feedback Pathways

    Directory of Open Access Journals (Sweden)

    Farr Niere

    2017-05-01

    Full Text Available The mammalian/mechanistic target of rapamycin complex 1 (mTORC1 serves as a regulator of mRNA translation. Recent studies suggest that mTORC1 may also serve as a local, voltage sensor in the postsynaptic region of neurons. Considering biochemical, bioinformatics and imaging data, we hypothesize that the activity state of mTORC1 dynamically regulates local membrane potential by promoting and repressing protein synthesis of select mRNAs. Our hypothesis suggests that mTORC1 uses positive and negative feedback pathways, in a branch-specific manner, to maintain neuronal excitability within an optimal range. In some dendritic branches, mTORC1 activity oscillates between the “On” and “Off” states. We define this as negative feedback. In contrast, positive feedback is defined as the pathway that leads to a prolonged depolarized or hyperpolarized resting membrane potential, whereby mTORC1 activity is constitutively on or off, respectively. We propose that inactivation of mTORC1 increases the expression of voltage-gated potassium alpha (Kv1.1 and 1.2 and beta (Kvβ2 subunits, ensuring that the membrane resets to its resting membrane potential after experiencing increased synaptic activity. In turn, reduced mTORC1 activity increases the protein expression of syntaxin-1A and promotes the surface expression of the ionotropic glutamate receptor N-methyl-D-aspartate (NMDA-type subunit 1 (GluN1 that facilitates increased calcium entry to turn mTORC1 back on. Under conditions such as learning and memory, mTORC1 activity is required to be high for longer periods of time. Thus, the arm of the pathway that promotes syntaxin-1A and Kv1 protein synthesis will be repressed. Moreover, dendritic branches that have low mTORC1 activity with increased Kv expression would balance dendrites with constitutively high mTORC1 activity, allowing for the neuron to maintain its overall activity level within an ideal operating range. Finally, such a model suggests that

  1. Negative Feedbacks by Isoprenoids on a Mevalonate Kinase Expressed in the Corpora Allata of Mosquitoes.

    Directory of Open Access Journals (Sweden)

    Pratik Nyati

    Full Text Available Juvenile hormones (JH regulate development and reproductive maturation in insects. JHs are synthesized through the mevalonate pathway (MVAP, an ancient metabolic pathway present in the three domains of life. Mevalonate kinase (MVK is a key enzyme in the MVAP. MVK catalyzes the synthesis of phosphomevalonate (PM by transferring the γ-phosphoryl group from ATP to the C5 hydroxyl oxygen of mevalonic acid (MA. Despite the importance of MVKs, these enzymes have been poorly characterized in insects.We functionally characterized an Aedes aegypti MVK (AaMVK expressed in the corpora allata (CA of the mosquito. AaMVK displayed its activity in the presence of metal cofactors. Different nucleotides were used by AaMVK as phosphoryl donors. In the presence of Mg(2+, the enzyme has higher affinity for MA than ATP. The activity of AaMVK was regulated by feedback inhibition from long-chain isoprenoids, such as geranyl diphosphate (GPP and farnesyl diphosphate (FPP.AaMVK exhibited efficient inhibition by GPP and FPP (Ki less than 1 μM, and none by isopentenyl pyrophosphate (IPP and dimethyl allyl pyrophosphate (DPPM. These results suggest that GPP and FPP might act as physiological inhibitors in the synthesis of isoprenoids in the CA of mosquitoes. Changing MVK activity can alter the flux of precursors and therefore regulate juvenile hormone biosynthesis.

  2. REVEILLE8 and PSEUDO-REPONSE REGULATOR5 Form a Negative Feedback Loop within the Arabidopsis Circadian Clock

    Science.gov (United States)

    Rawat, Reetika; Jones, Matthew A.; Schwartz, Jacob; Salemi, Michelle R.; Phinney, Brett S.; Harmer, Stacey L.

    2011-01-01

    Circadian rhythms provide organisms with an adaptive advantage, allowing them to regulate physiological and developmental events so that they occur at the most appropriate time of day. In plants, as in other eukaryotes, multiple transcriptional feedback loops are central to clock function. In one such feedback loop, the Myb-like transcription factors CCA1 and LHY directly repress expression of the pseudoresponse regulator TOC1 by binding to an evening element (EE) in the TOC1 promoter. Another key regulatory circuit involves CCA1 and LHY and the TOC1 homologs PRR5, PRR7, and PRR9. Purification of EE–binding proteins from plant extracts followed by mass spectrometry led to the identification of RVE8, a homolog of CCA1 and LHY. Similar to these well-known clock genes, expression of RVE8 is circadian-regulated with a dawn phase of expression, and RVE8 binds specifically to the EE. However, whereas cca1 and lhy mutants have short period phenotypes and overexpression of either gene causes arrhythmia, rve8 mutants have long-period and RVE8-OX plants have short-period phenotypes. Light input to the clock is normal in rve8, but temperature compensation (a hallmark of circadian rhythms) is perturbed. RVE8 binds to the promoters of both TOC1 and PRR5 in the subjective afternoon, but surprisingly only PRR5 expression is perturbed by overexpression of RVE8. Together, our data indicate that RVE8 promotes expression of a subset of EE–containing clock genes towards the end of the subjective day and forms a negative feedback loop with PRR5. Thus RVE8 and its homologs CCA1 and LHY function close to the circadian oscillator but act via distinct molecular mechanisms. PMID:21483796

  3. REVEILLE8 and PSEUDO-REPONSE REGULATOR5 form a negative feedback loop within the Arabidopsis circadian clock.

    Directory of Open Access Journals (Sweden)

    Reetika Rawat

    2011-03-01

    Full Text Available Circadian rhythms provide organisms with an adaptive advantage, allowing them to regulate physiological and developmental events so that they occur at the most appropriate time of day. In plants, as in other eukaryotes, multiple transcriptional feedback loops are central to clock function. In one such feedback loop, the Myb-like transcription factors CCA1 and LHY directly repress expression of the pseudoresponse regulator TOC1 by binding to an evening element (EE in the TOC1 promoter. Another key regulatory circuit involves CCA1 and LHY and the TOC1 homologs PRR5, PRR7, and PRR9. Purification of EE-binding proteins from plant extracts followed by mass spectrometry led to the identification of RVE8, a homolog of CCA1 and LHY. Similar to these well-known clock genes, expression of RVE8 is circadian-regulated with a dawn phase of expression, and RVE8 binds specifically to the EE. However, whereas cca1 and lhy mutants have short period phenotypes and overexpression of either gene causes arrhythmia, rve8 mutants have long-period and RVE8-OX plants have short-period phenotypes. Light input to the clock is normal in rve8, but temperature compensation (a hallmark of circadian rhythms is perturbed. RVE8 binds to the promoters of both TOC1 and PRR5 in the subjective afternoon, but surprisingly only PRR5 expression is perturbed by overexpression of RVE8. Together, our data indicate that RVE8 promotes expression of a subset of EE-containing clock genes towards the end of the subjective day and forms a negative feedback loop with PRR5. Thus RVE8 and its homologs CCA1 and LHY function close to the circadian oscillator but act via distinct molecular mechanisms.

  4. High diatom production and export in stratified waters - A potential negative feedback to global warming

    Science.gov (United States)

    Kemp, Alan E. S.; Villareal, Tracy A.

    2013-12-01

    It is widely held that increased stratification and reduced vertical mixing in the ocean driven by global warming will promote the replacement of diatoms by smaller phytoplankton and lead to an overall decrease in productivity and carbon export. Here we present contrary evidence from a synergy of modern observations and palaeo-records that reveal high diatom production and export from stratified waters. Diatom adaptations to stratified waters include the ability to grow in low light conditions in deep chlorophyll maxima; vertical migrations between nutricline depths and the surface, and symbioses with N2-fixing cyanobacteria in diatom-diazotroph associations (DDA). These strategies foster the maintenance of seed populations that may then exploit mixing events induced by storms or eddies, but may also inherently promote blooms. Recent oceanographic observations in the subtropical gyres, at increasingly high temporal and spatial resolutions, have monitored short-lived but often substantial blooms and export of stratified-adapted diatoms including rhizosolenids and the diazotroph-associated Hemiaulus hauckii. Aggregate formation by such diatoms is common and promotes rapid settling thereby minimizing water column remineralization and optimizing carbon flux. Convergence zones associated with oceanic fronts or mesoscale features may also generate substantial flux of stratified-adapted diatom species. Conventional oceanographic observing strategies and sampling techniques under-represent such activity due to the lack of adequate capability to sample the large sized diatoms and colonies involved, the subsurface location of many of these blooms, their common development in thin global warming. However, the key genera involved in such potential feedbacks are underrepresented in both laboratory and field studies and are poorly represented in models. Our findings suggest that a reappraisal is necessary of the way diatoms are represented as plankton functional types (PFTs) in

  5. Model of Calcium Oscillations Due to Negative Feedback in Olfactory Cilia

    DEFF Research Database (Denmark)

    Reidl, Juergen; Borowski, Peter; Sensse, Anke;

    2006-01-01

    We present a mathematical model for Ca oscillations in the cilia of olfactory sensory neurons. The underlying mechanism is based on direct negative regulation of cyclic nucleotide-gated channels by calcium/calmodulin and does not require any autocatalysis such as calcium-induced calcium release....... The model is in quantitative agreement with available experimental data, both with respect to oscillations and to fast adaptation. We give predictions for the ranges of parameters in which oscillations should be observable. Relevance of the model to calcium oscillations in other systems is discussed....

  6. The effectiveness of attachment based intervention using video feedback method on decreasing negative representations and separation anxiety of children

    Directory of Open Access Journals (Sweden)

    parisa sadat Seyedmousavi

    2015-09-01

    Full Text Available Background: With regard to the importance of attachment in developing separation anxiety, the purpose of this study was to investigate the effectiveness of attachment based intervention via video feedback on decreasing negative representations and separation anxiety problems in preschool children. Materials and Method: The research method was semi experimental with pretest-posttest and follow up. For this, 21 mother-child dyads (11 dyads in experimental and 10 dyads in control group were selected from 2 child counseling centers based on including criteria. The experimental group received 8 to 10 individual attachment based intervention sessions and the control group received the other relation based intervention for comparison of their effectiveness. The participants were assessed using maternal behavior Q-SORT, MacArthur story stems and child psychopathological symptoms inventory in pretest, post-test and 3 months interval follow up. Results: The findings revealed the effectiveness of attachment-based intervention on increasing maternal sensitivity, decreasing negative representations of child and also separation anxiety symptoms in children of experimental group. The mean scores of experimental group in comparison to witness group have significantly decreased in all variables. Conclusion: Considering this results, it seems attachment-based intervention could increas maternal sensitivity and this change with decreasing negative representation of child via recovering interactions have a positive effect on decreasing separation anxiety problems of children.

  7. Periodic solutions of piecewise affine gene network models with non uniform decay rates: the case of a negative feedback loop.

    Science.gov (United States)

    Farcot, Etienne; Gouzé, Jean-Luc

    2009-12-01

    This paper concerns periodic solutions of a class of equations that model gene regulatory networks. Unlike the vast majority of previous studies, it is not assumed that all decay rates are identical. To handle this more general situation, we rely on monotonicity properties of these systems. Under an alternative assumption, it is shown that a classical fixed point theorem for monotone, concave operators can be applied to these systems. The required assumption is expressed in geometrical terms as an alignment condition on so-called focal points. As an application, we show the existence and uniqueness of a stable periodic orbit for negative feedback loop systems in dimension 3 or more, and of a unique stable equilibrium point in dimension 2. This extends a theorem of Snoussi, which showed the existence of these orbits only.

  8. miR-340 and ZEB1 negative feedback loop regulates TGF-β- mediated breast cancer progression

    Science.gov (United States)

    Xie, Ye-Gong; Wang, Jie; Mao, Jie-Fei; Zhang, Bin; Wang, Xin; Cao, Xu-Chen

    2016-01-01

    MicroRNAs act as key regulators in carcinogenesis and progression in various cancers. In present study, we explored the role of miR-340 in the breast cancer progression. Our results showed that overexpression of miR-340 inhibits breast cancer cell proliferation and invasion, whereas depletion of miR-340 promotes breast cancer progression. Molecularly, ZEB1 was identified as a target gene of miR-340 and miR-340 suppressed the expression of ZEB1 by directly binding to the 3′-UTR of ZEB1. Furthermore, ZEB1 transcriptionally suppresses miR-340 expression. The negative feedback loop regulated TGF-β-mediated breast cancer progression. In conclusion, our data suggested that miR-340 acted as a tumor suppressor in breast cancer progression. PMID:27036021

  9. Experimental investigation on nonlinear dynamics of 1550 nm VCSEL simultaneously subject to orthogonal optical injection and negative optoelectronic feedback

    Science.gov (United States)

    Deng, Tao; Xia, Guang-Qiong; Chen, Jian-Jun; Tang, Xi; Lin, Xiao-Dong; Yang, Xin; Huang, Shou-Wen; Wu, Zheng-Mao

    2017-04-01

    Nonlinear dynamic characteristics of a 1550 nm vertical-cavity surface-emitting laser (1550 nm VCSEL) simultaneously subject to orthogonal optical injection and negative optoelectronic feedback are experimentally investigated. The results show that, under suitable orthogonal optical injection the VCSEL can exhibit rich nonlinear dynamic behaviors such as stable state (S), period-one (P1), period-two (P2), chaos (CO), stable injection locking (SIL) and polarization switching (PS). After further introducing negative optoelectronic feedback with a certain feedback delay time, the dynamic distribution of the orthogonal optical injection 1550 nm VCSEL is significantly affected, and some new phenomena including three-frequency quasiperiodic (Q3) state can be observed. With the increase of optoelectronic feedback strength, the S and SIL regions typically are shrank, while the quasiperiodic (QP) and CO regions are enlarged.

  10. FGF signaling enhances a sonic hedgehog negative feedback loop at the initiation of spinal cord ventral patterning.

    Science.gov (United States)

    Morales, Aixa V; Espeso-Gil, Sergio; Ocaña, Inmaculada; Nieto-Lopez, Francisco; Calleja, Elena; Bovolenta, Paola; Lewandoski, Mark; Diez Del Corral, Ruth

    2016-09-01

    A prevalent developmental mechanism for the assignment of cell identities is the production of spatiotemporal concentration gradients of extracellular signaling molecules that are interpreted by the responding cells. One of such signaling systems is the Shh gradient that controls neuronal subtype identity in the ventral spinal cord. Using loss and gain of function approaches in chick and mouse embryos, we show here that the fibroblast growth factor (FGF) signaling pathway is required to restrict the domains of ventral gene expression as neuroepithelial cells become exposed to Shh during caudal extension of the embryo. FGF signaling activates the expression of the Shh receptor and negative pathway regulator Patched 2 (Ptch2) and therefore can enhance a negative feedback loop that restrains the activity of the pathway. Thus, we identify one of the mechanisms by which FGF signaling acts as a modulator of the onset of Shh signaling activity in the context of coordination of ventral patterning and caudal axis extension. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 956-971, 2016.

  11. Origin of the 'Extra Entropy'

    Science.gov (United States)

    Mushotzky, R.

    2008-01-01

    I will discuss how one can determine the origin of the 'extra entropy' in groups and clusters and the feedback needed in models of galaxy formation. I will stress the use of x-ray spectroscopy and imaging and the critical value that Con-X has in this regard.

  12. Germline genetic variants disturbing the Let-7/LIN28 double-negative feedback loop alter breast cancer susceptibility.

    Directory of Open Access Journals (Sweden)

    Ao-Xiang Chen

    2011-09-01

    Full Text Available Previous studies have shown that let-7 can repress the post-transcriptional translation of LIN28, and LIN28 in turn could block the maturation of let-7, forming a double-negative feedback loop. In this study, we investigated the effect of germline genetic variants on regulation of the homeostasis of the let-7/LIN28 loop and breast cancer risk. We initially demonstrated that the T/C variants of rs3811463, a single nucleotide polymorphism (SNP located near the let-7 binding site in LIN28, could lead to differential regulation of LIN28 by let-7. Specifically, the C allele of rs3811463 weakened let-7-induced repression of LIN28 mRNA, resulting in increased production of LIN28 protein, which could in turn down-regulate the level of mature let-7. This effect was then validated at the tissue level in that the normal breast tissue of individuals with the rs3811463-TC genotype expressed significantly lower levels of let-7 and higher levels of LIN28 protein than those individuals with the rs3811463-TT genotype. Because previous in vitro and ex vivo experiments have consistently suggested that LIN28 could promote cellular transformation, we then systematically evaluated the relationship between rs3811463 as well as other common LIN28 SNPs and the risk of breast cancer in a stepwise manner. The first hospital-based association study (n = 2,300 demonstrated that two SNPs were significantly associated with breast cancer risk, one of which was rs3811463, while the other was rs6697410. The C allele of the rs3811463 SNP corresponded to an increased risk of breast cancer with an odds ratio (OR of 1.25 (P = 0.0091, which was successfully replicated in a second independent study (n = 1,156 with community-based controls. The combined P-value of the two studies was 8.0 × 10⁻⁵. Taken together, our study demonstrates that host genetic variants could disturb the regulation of the let-7/LIN28 double-negative feedback loop and alter breast cancer risk.

  13. Germline genetic variants disturbing the Let-7/LIN28 double-negative feedback loop alter breast cancer susceptibility.

    Science.gov (United States)

    Chen, Ao-Xiang; Yu, Ke-Da; Fan, Lei; Li, Ji-Yu; Yang, Chen; Huang, A-Ji; Shao, Zhi-Ming

    2011-09-01

    Previous studies have shown that let-7 can repress the post-transcriptional translation of LIN28, and LIN28 in turn could block the maturation of let-7, forming a double-negative feedback loop. In this study, we investigated the effect of germline genetic variants on regulation of the homeostasis of the let-7/LIN28 loop and breast cancer risk. We initially demonstrated that the T/C variants of rs3811463, a single nucleotide polymorphism (SNP) located near the let-7 binding site in LIN28, could lead to differential regulation of LIN28 by let-7. Specifically, the C allele of rs3811463 weakened let-7-induced repression of LIN28 mRNA, resulting in increased production of LIN28 protein, which could in turn down-regulate the level of mature let-7. This effect was then validated at the tissue level in that the normal breast tissue of individuals with the rs3811463-TC genotype expressed significantly lower levels of let-7 and higher levels of LIN28 protein than those individuals with the rs3811463-TT genotype. Because previous in vitro and ex vivo experiments have consistently suggested that LIN28 could promote cellular transformation, we then systematically evaluated the relationship between rs3811463 as well as other common LIN28 SNPs and the risk of breast cancer in a stepwise manner. The first hospital-based association study (n = 2,300) demonstrated that two SNPs were significantly associated with breast cancer risk, one of which was rs3811463, while the other was rs6697410. The C allele of the rs3811463 SNP corresponded to an increased risk of breast cancer with an odds ratio (OR) of 1.25 (P = 0.0091), which was successfully replicated in a second independent study (n = 1,156) with community-based controls. The combined P-value of the two studies was 8.0 × 10⁻⁵. Taken together, our study demonstrates that host genetic variants could disturb the regulation of the let-7/LIN28 double-negative feedback loop and alter breast cancer risk.

  14. Phytochrome Signaling in Green Arabidopsis Seedlings: Impact Assessment of a Mutually Negative phyB-PIF Feedback Loop

    Institute of Scientific and Technical Information of China (English)

    Pablo Leivar; Elena Monte; Megan M. Cohn; Peter H. Quail

    2012-01-01

    The reversibly red (R)/far-red (FR)-Iight-responsive phytoch rome (phy) photosensory system initiates both the deetiolation process in dark-germinated seedlings upon first exposure to light,and the shade-avoidance process in fully deetiolated seedlings upon exposure to vegetational shade.The intracellular signaling pathway from the light-activated photoreceptor conformer (Pfr) to the transcriptional network that drives these responses involves direct,physical interaction of Pfr with a small subfamily of bHLH transcription factors,termed Phy-lnteracting Factors (PIFs),which induces rapid PIF proteolytic degradation.In addition,there is evidence of further complexity in light-grown seedlings,whereby phyB-PIF interaction reciprocally induces phyB degradation,in a mutually-negative,feedback-loop configuration.Here,to assess the relative contributions of these antagonistic activities to the net phenotypic readout in light-grown seedlings,we have examined the magnitude of the light- and simulated-shade-induced responses of a pentuple phyBpif1pif3pif4pif5 (phyBpifq) mutant and various multiple pif-mutant combinations.The data (1) reaffirm that phyB is the predominant,if not exclusive,photoreceptor imposing the inhibition of hypocotyl elongation in deetiolating seedlings in response to prolonged continuous R irradiation and (2) show that the PIF quartet (PIF1,PIF3,PIF4,and PIF5) retain and exert a dual capacity to modulate hypocotyl elongation under these conditions,by concomitantly promoting cell elongation through intrinsic transcriptional-regulatory activity,and reducing phyB-inhibitory capacity through feedback-loop-induced phyB degradation.In shade-exposed seedlings,immunoblot analysis shows that the shade-imposed reduction in Pfr levels induces increases in the abundance of PIF3,and mutant analysis indicates that PIF3 acts,in conjunction with PIF4 and PIF5,to promote the known shade-induced acceleration of hypocotyl elongation.Conversely,although the quadruple pifq

  15. Negative feedback avalanche diode

    Science.gov (United States)

    Itzler, Mark Allen (Inventor)

    2010-01-01

    A single-photon avalanche detector is disclosed that is operable at wavelengths greater than 1000 nm and at operating speeds greater than 10 MHz. The single-photon avalanche detector comprises a thin-film resistor and avalanche photodiode that are monolithically integrated such that little or no additional capacitance is associated with the addition of the resistor.

  16. Inhibition of Wnt signaling by Wise (Sostdc1) and negative feedback from Shh controls tooth number and patterning.

    Science.gov (United States)

    Ahn, Youngwook; Sanderson, Brian W; Klein, Ophir D; Krumlauf, Robb

    2010-10-01

    Mice carrying mutations in Wise (Sostdc1) display defects in many aspects of tooth development, including tooth number, size and cusp pattern. To understand the basis of these defects, we have investigated the pathways modulated by Wise in tooth development. We present evidence that, in tooth development, Wise suppresses survival of the diastema or incisor vestigial buds by serving as an inhibitor of Lrp5- and Lrp6-dependent Wnt signaling. Reducing the dosage of the Wnt co-receptor genes Lrp5 and Lrp6 rescues the Wise-null tooth phenotypes. Inactivation of Wise leads to elevated Wnt signaling and, as a consequence, vestigial tooth buds in the normally toothless diastema region display increased proliferation and continuous development to form supernumerary teeth. Conversely, gain-of-function studies show that ectopic Wise reduces Wnt signaling and tooth number. Our analyses demonstrate that the Fgf and Shh pathways are major downstream targets of Wise-regulated Wnt signaling. Furthermore, our experiments revealed that Shh acts as a negative-feedback regulator of Wnt signaling and thus determines the fate of the vestigial buds and later tooth patterning. These data provide insight into the mechanisms that control Wnt signaling in tooth development and into how crosstalk among signaling pathways controls tooth number and morphogenesis.

  17. The timing of upper-layer neurogenesis is conferred by sequential derepression and negative feedback from deep-layer neurons.

    Science.gov (United States)

    Toma, Kenichi; Kumamoto, Takuma; Hanashima, Carina

    2014-09-24

    The prevailing view of upper-layer (UL) neurogenesis in the cerebral cortex is that progenitor cells undergo successive rounds of asymmetric cell division that restrict the competence and production of UL neurons later in development. However, the recent discovery of UL fate-committed early progenitors raises an alternative perspective concerning their ontogeny. To investigate the emergence of UL progenitors, we manipulated the timing and extent of cortical neurogenesis in vivo in mice. We demonstrated that UL competence is tightly linked to deep-layer (DL) neurogenesis and that this sequence is determined primarily through derepression of Fezf2 by Foxg1 within a closed transcriptional cascade. We further demonstrated that the sequential acquisition of UL competence requires negative feedback, which is propagated from postmitotic DL neurons. Thus, neocortical progenitors integrate intrinsic and extrinsic cues to generate UL neurons through a system that controls the sequence of DL and UL neurogenesis and to scale the production of intracortical projection neurons based on the availability of their subcortical projection neuron counterparts during cortical development and evolution.

  18. Low noise InGaAs/InP single-photon negative feedback avalanche diodes: characterization and applications

    Science.gov (United States)

    Boso, Gianluca; Korzh, Boris; Lunghi, Tommaso; Zbinden, Hugo

    2015-05-01

    In recent years, many applications have been proposed that require detection of light signals in the near-infrared range with single-photon sensitivity and time resolution down to few hundreds of picoseconds. InGaAs/InP singlephoton avalanche diodes (SPADs) are a viable choice for these tasks thanks to their compactness and ease-of-use. Unfortunately, their performance is traditionally limited by high dark count rates (DCRs) and afterpulsing effects. However, a recent demonstration of negative feedback avalanche diodes (NFADs), operating in the free-running regime, achieved a DCR down to 1 cps at 10 % photon detection efficiency (PDE) at telecom wavelengths. Here we present our recent results on the characterization of NFAD detectors for temperatures down to approximately 150 K. A FPGA controlled test-bench facilitates the acquisition of all the parameters of interest like PDE, DCR, afterpulsing probability etc. We also demonstrate the performance of the detector in different applications: In particular, with low-temperature NFADs, we achieved high secret key rates with quantum key distribution over fiber links between 100-300 km. But low noise InGaAs/InP SPADs will certainly find applications in yet unexplored fields like photodynamic therapy, near infrared diffuse optical spectroscopy and many more. For example with a large area detector, we made time-resolved measurements of singlet-oxygen luminescence from a standard Rose Bengal dye in aqueous solution.

  19. Pleckstrin homology domain-containing protein PHLDB3 supports cancer growth via a negative feedback loop involving p53

    Science.gov (United States)

    Chao, Tengfei; Zhou, Xiang; Cao, Bo; Liao, Peng; Liu, Hongbing; Chen, Yun; Park, Hee-Won; Zeng, Shelya X.; Lu, Hua

    2016-01-01

    The tumour suppressor p53 transactivates the expression of its target genes to exert its functions. Here, we identify a pleckstrin homology domain-containing protein (PHLDB3)-encoding gene as a p53 target. PHLDB3 overexpression increases proliferation and restrains apoptosis of wild-type p53-harboring cancer cells by reducing p53 protein levels. PHLDB3 binds to MDM2 (mouse double minute 2 homolog) and facilitates MDM2-mediated ubiquitination and degradation of p53. Knockdown of PHLDB3 more efficiently inhibits the growth of mouse xenograft tumours derived from human colon cancer HCT116 cells that contain wild type p53 compared with p53-deficient HCT116 cells, and also sensitizes tumour cells to doxorubicin and 5-Fluorouracil. Analysis of cancer genomic databases reveals that PHLDB3 is amplified and/or highly expressed in numerous human cancers. Altogether, these results demonstrate that PHLDB3 promotes tumour growth by inactivating p53 in a negative feedback fashion and suggest PHLDB3 as a potential therapeutic target in various human cancers. PMID:28008906

  20. Genetic polymorphisms in circadian negative feedback regulation genes predict overall survival and response to chemotherapy in gastric cancer patients.

    Science.gov (United States)

    Qu, Falin; Qiao, Qing; Wang, Nan; Ji, Gang; Zhao, Huadong; He, Li; Wang, Haichao; Bao, Guoqiang

    2016-03-01

    Circadian negative feedback loop (CNFL) genes play important roles in cancer development and progression. To evaluate the effects of single nucleotide polymorphisms (SNPs) in CNFL genes on the survival of GC patients, 13 functional SNPs from 5 CNFL genes were genotyped in a cohort of 1030 resected GC patients (704 in the training set, 326 in the validation set) to explore the association of SNPs with overall survival (OS). Among the 13 SNPs, three SNPs (rs1056560 in CRY1, rs3027178 in PER1 and rs228729 in PER3) were significantly associated with OS of GC in the training set, and verified in the validation set and pooled analysis. Furthermore, a dose-dependent cumulative effect of these SNPs on GC survival was observed, and survival tree analysis showed higher order interactions between these SNPs. In addition, protective effect conferred by adjuvant chemotherapy (ACT) on GC was observed in patients with variant alleles (TG/GG) of rs1056560, but not in those with homozygous wild (TT) genotype. Functional assay suggested rs1056560 genotypes significantly affect CRY1 expression in cancer cells. Our study presents that SNPs in the CNFL genes may be associated with GC prognosis, and provides the guidance in selecting potential GC patients most likely responsive to ACT.

  1. SIRT1 is regulated by a PPARγ–SIRT1 negative feedback loop associated with senescence

    Science.gov (United States)

    Zhou, Rui; Niu, Jing; McNutt, Michael A.; Wang, Pan; Tong, Tanjun

    2010-01-01

    Human Silent Information Regulator Type 1 (SIRT1) is an NAD+-dependent deacetylase protein which is an intermediary of cellular metabolism in gene silencing and aging. SIRT1 has been extensively investigated and shown to delay senescence; however, less is known about the regulation of SIRT1 during aging. In this study, we show that the peroxisome proliferator-activated receptor-γ (PPARγ), which is a ligand-regulated modular nuclear receptor that governs adipocyte differentiation and inhibits cellular proliferation, inhibits SIRT1 expression at the transcriptional level. Moreover, both PPARγ and SIRT1 can bind the SIRT1 promoter. PPARγ directly interacts with SIRT1 and inhibits SIRT1 activity, forming a negative feedback and self-regulation loop. In addition, our data show that acetylation of PPARγ increased with increasing cell passage number. We propose that PPARγ is subject to regulation by acetylation and deacetylation via p300 and SIRT1 in cellular senescence. These results demonstrate a mutual regulation between PPARγ and SIRT1 and identify a new posttranslational modification that affects cellular senescence. PMID:20660480

  2. Active vibration control of structure by Active Mass Damper and Multi-Modal Negative Acceleration Feedback control algorithm

    Science.gov (United States)

    Yang, Don-Ho; Shin, Ji-Hwan; Lee, HyunWook; Kim, Seoug-Ki; Kwak, Moon K.

    2017-03-01

    In this study, an Active Mass Damper (AMD) consisting of an AC servo motor, a movable mass connected to the AC servo motor by a ball-screw mechanism, and an accelerometer as a sensor for vibration measurement were considered. Considering the capability of the AC servo motor which can follow the desired displacement accurately, the Negative Acceleration Feedback (NAF) control algorithm which uses the acceleration signal directly and produces the desired displacement for the active mass was proposed. The effectiveness of the NAF control was proved theoretically using a single-degree-of-freedom (SDOF) system. It was found that the stability condition for the NAF control is static and it can effectively increase the damping of the target natural mode without causing instability in the low frequency region. Based on the theoretical results of the SDOF system, the Multi-Modal NAF (MMNAF) control is proposed to suppress the many natural modes of multi-degree-of-freedom (MDOF) systems using a single AMD. It was proved both theoretically and experimentally that the MMNAF control can suppress vibrations of the MDOF system.

  3. Coordination of Double Strand Break Repair and Meiotic Progression in Yeast by a Mek1- Ndt80 Negative Feedback Loop.

    Science.gov (United States)

    Prugar, Evelyn; Burnett, Cameron; Chen, Xiangyu; Hollingsworth, Nancy M

    2017-03-01

    During meiosis, homologous chromosomes are physically connected by crossovers and sister chromatid cohesion. Interhomolog crossovers are generated by the highly regulated repair of programmed double strand breaks (DSBs). The meiosis-specific kinase, Mek1, is critical for this regulation. Mek1 down-regulates the mitotic recombinase Rad51, indirectly promoting interhomolog strand invasion by the meiosis-specific recombinase, Dmc1. Mek1 also promotes the formation of crossovers that are distributed throughout the genome by interference and is the effector kinase for a meiosis-specific checkpoint that delays entry into Meiosis I until DSBs have been repaired. The target of this checkpoint is a meiosis-specific transcription factor, Ndt80, which is necessary to express the polo-like kinase, CDC5, and the cyclin, CLB1, thereby allowing completion of recombination and meiotic progression. This work shows that Mek1 and Ndt80 negatively feedback on each other such that when DSB levels are high, Ndt80 is inactive due to high levels of Mek1 activity. As DSBs are repaired, chromosomes synapse and Mek1 activity is reduced below a threshold that allows activation of Ndt80. Ndt80 transcription of CDC5 results in degradation of Red1, a meiosis-specific protein required for Mek1 activation, thereby abolishing Mek1 activity completely. Elimination of Mek1 kinase activity allows Rad51-mediated repair of any remaining DSBs. In this way, cells do not enter Meiosis I until recombination is complete and all DSBs are repaired.

  4. Dysregulation of SOCS-Mediated Negative Feedback of Cytokine Signaling in Carcinogenesis and Its Significance in Cancer Treatment

    Science.gov (United States)

    Jiang, Mengmeng; Zhang, Wen-wen; Liu, Pengpeng; Yu, Wenwen; Liu, Ting; Yu, Jinpu

    2017-01-01

    Suppressor of cytokine signaling (SOCS) proteins are major negative feedback regulators of cytokine signaling mediated by the Janus kinase (JAK)-signal transducer and activator of transcription signaling pathway. In particular, SOCS1 and SOCS3 are strong inhibitors of JAKs and can play pivotal roles in the development and progression of cancers. The abnormal expression of SOCS1 and SOCS3 in cancer cells is associated with the dysregulation of cell growth, migration, and death induced by multiple cytokines and hormones in human carcinomas. In addition, the mechanisms involved in SOCS1- and SOCS3-regulated abnormal development and activation of immune cells in carcinogenesis, including T cells, macrophages, dendritic cells, and myeloid-derived suppressor cells, are still unclear. Therefore, this study aims to further discuss the molecules and signal pathways regulating the expression and function of SOCS1 and SOCS3 in various types of cancers and elucidate the feasibility and efficiency of SOCS-based target therapeutic strategy in anticancer treatment. PMID:28228755

  5. Be kind to your eating disorder patients: the impact of positive and negative feedback on the explicit and implicit self-esteem of female patients with eating disorders

    NARCIS (Netherlands)

    Vanderlinden, J.; Kamphuis, J.H.; Slagmolen, C.; Wigboldus, D.; Pieters, G.; Probst, M.

    2009-01-01

    OBJECTIVE: Lack of self-esteem may play an important role in the development of eating disorders (ED). This study investigated the differential impact of positive and negative feedback on implicit and explicit self-esteem in women with an ED (N=25) as compared to women without an ED (N=29). METHOD:

  6. Be kind to your eating disorder patients: The impact of positive and negative feedback on the explicit and implicit self-esteem of female patients with eating disorders

    NARCIS (Netherlands)

    Linden, J. van der; Kamphuis, J.H.; Slagmolen, C.J.J.; Wigboldus, D.H.J.; Pieters, G.; Probst, M.

    2009-01-01

    OBJECTIVE: Lack of self-esteem may play an important role in the development of eating disorders (ED). This study investigated the differential impact of positive and negative feedback on implicit and explicit self-esteem in women with an ED (N=25) as compared to women without an ED (N=29). METHOD:

  7. Baseline EEG theta/beta ratio and punishment sensitivity as biomarkers for feedback-related negativity (FRN) and risk-taking

    NARCIS (Netherlands)

    Massar, S.A.A.; Rossi, V.; Schutter, D.J.L.G.; Kenemans, J.L.

    2012-01-01

    Objective: Feedback-related negativity (FRN) is associated with reinforcement learning and punishment sensitivity. Furthermore, reinforcement learning proficiency can be predicted from pre-task baseline EEG theta/beta ratio. In this study it was examined whether there was a relation between baseline

  8. Generalized Anxiety Disorder and Social Anxiety Disorder, but Not Panic Anxiety Disorder, Are Associated with Higher Sensitivity to Learning from Negative Feedback: Behavioral and Computational Investigation.

    Science.gov (United States)

    Khdour, Hussain Y; Abushalbaq, Oday M; Mughrabi, Ibrahim T; Imam, Aya F; Gluck, Mark A; Herzallah, Mohammad M; Moustafa, Ahmed A

    2016-01-01

    Anxiety disorders, including generalized anxiety disorder (GAD), social anxiety disorder (SAD), and panic anxiety disorder (PAD), are a group of common psychiatric conditions. They are characterized by excessive worrying, uneasiness, and fear of future events, such that they affect social and occupational functioning. Anxiety disorders can alter behavior and cognition as well, yet little is known about the particular domains they affect. In this study, we tested the cognitive correlates of medication-free patients with GAD, SAD, and PAD, along with matched healthy participants using a probabilistic category-learning task that allows the dissociation between positive and negative feedback learning. We also fitted all participants' data to a Q-learning model and various actor-critic models that examine learning rate parameters from positive and negative feedback to investigate effects of valence vs. action on performance. SAD and GAD patients were more sensitive to negative feedback than either PAD patients or healthy participants. PAD, SAD, and GAD patients did not differ in positive-feedback learning compared to healthy participants. We found that Q-learning models provide the simplest fit of the data in comparison to other models. However, computational analysis revealed that groups did not differ in terms of learning rate or exploration values. These findings argue that (a) not all anxiety spectrum disorders share similar cognitive correlates, but are rather different in ways that do not link them to the hallmark of anxiety (higher sensitivity to negative feedback); and (b) perception of negative consequences is the core feature of GAD and SAD, but not PAD. Further research is needed to examine the similarities and differences between anxiety spectrum disorders in other cognitive domains and potential implementation of behavioral therapy to remediate cognitive deficits.

  9. 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.

    Science.gov (United States)

    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.

  10. Using Extra Credit to Facilitate Extra Learning in Students

    Directory of Open Access Journals (Sweden)

    Mohammad Muztaba Fuad

    2012-06-01

    Full Text Available Giving students extra credit work is a hotly debated pedagogical issue. This paper shares experience of using extra credit quizzes to push students to think critically and beyond the boundaries. This particular type of quizzes are not announced before and presented to students as a surprise quiz. A certain percentage of the grade earned in these quizzes was included in student’s final grade calculations. With a well-developed model of questions, quiz structure and grade calculation, the presented model of extra credit eliminates negativity related to extra credit work and also motivates students into course work. Our findings showed that by relieving students from the mental pressure of test taking and by making those tests/quizzes as extra credit; students actually performs better in solving harder problems and eventually learns more of the advanced course topics.

  11. FRET imaging and statistical signal processing reveal positive and negative feedback loops regulating the morphology of randomly migrating HT-1080 cells.

    Science.gov (United States)

    Kunida, Katsuyuki; Matsuda, Michiyuki; Aoki, Kazuhiro

    2012-05-15

    Cell migration plays an important role in many physiological processes. Rho GTPases (Rac1, Cdc42, RhoA) and phosphatidylinositols have been extensively studied in directional cell migration. However, it remains unclear how Rho GTPases and phosphatidylinositols regulate random cell migration in space and time. We have attempted to address this issue using fluorescence resonance energy transfer (FRET) imaging and statistical signal processing. First, we acquired time-lapse images of random migration of HT-1080 fibrosarcoma cells expressing FRET biosensors of Rho GTPases and phosphatidyl inositols. We developed an image-processing algorithm to extract FRET values and velocities at the leading edge of migrating cells. Auto- and cross-correlation analysis suggested the involvement of feedback regulations among Rac1, phosphatidyl inositols and membrane protrusions. To verify the feedback regulations, we employed an acute inhibition of the signaling pathway with pharmaceutical inhibitors. The inhibition of actin polymerization decreased Rac1 activity, indicating the presence of positive feedback from actin polymerization to Rac1. Furthermore, treatment with PI3-kinase inhibitor induced an adaptation of Rac1 activity, i.e. a transient reduction of Rac1 activity followed by recovery to the basal level. In silico modeling that reproduced the adaptation predicted the existence of a negative feedback loop from Rac1 to actin polymerization. Finally, we identified MLCK as the probable controlling factor in the negative feedback. These findings quantitatively demonstrate positive and negative feedback loops that involve actin, Rac1 and MLCK, and account for the ordered patterns of membrane dynamics observed in randomly migrating cells.

  12. Suppressor of cytokine signalling-6 promotes neurite outgrowth via JAK2/STAT5-mediated signalling pathway, involving negative feedback inhibition.

    Directory of Open Access Journals (Sweden)

    Sakshi Gupta

    Full Text Available BACKGROUND: Suppressors of cytokine signalling (SOCS protein family are key regulators of cellular responses to cytokines and play an important role in the nervous system. The SOCS6 protein, a less extensively studied SOCS family member, has been shown to induce insulin resistance in the retina and promote survival of the retinal neurons. But no reports are available about the role of SOCS6 in neuritogenesis. In this study, we examined the role of SOCS6 in neurite outgrowth and neuronal cell signalling. METHODOLOGY/PRINCIPAL FINDINGS: The effect of SOCS6 in neural stem cells differentiation was studied in neural stem cells and PC12 cell line. Highly elevated levels of SOCS6 were found upon neural cell differentiation both at the mRNA and protein level. Furthermore, SOCS6 over-expression lead to increase in neurite outgrowth and degree of branching, whereas SOCS6 knockdown with specific siRNAs, lead to a significant decrease in neurite initiation and extension. Insulin-like growth factor-1 (IGF-1 stimulation which enhanced neurite outgrowth of neural cells resulted in further enhancement of SOCS6 expression. Jak/Stat (Janus Kinase/Signal Transducer And Activator Of Transcription pathway was found to be involved in the SOCS6 mediated neurite outgrowth. Bioinformatics study revealed presence of putative Stat binding sites in the SOCS6 promoter region. Transcription factors Stat5a and Stat5b were involved in SOCS6 gene upregulation leading to neuronal differentiation. Following differentiation, SOCS6 was found to form a ternary complex with IGFR (Insulin Like Growth Factor-1 Receptor and JAK2 which acted in a negative feedback loop to inhibit pStat5 activation. CONCLUSION/SIGNIFICANCE: The current paradigm for the first time states that SOCS6, a SOCS family member, plays an important role in the process of neuronal differentiation. These findings define a novel molecular mechanism for Jak2/Stat5 mediated SOCS6 signalling.

  13. Negative Fgf8-Bmp2 feed-back is regulated by miR-130 during early cardiac specification.

    Science.gov (United States)

    Lopez-Sanchez, Carmen; Franco, Diego; Bonet, Fernando; Garcia-Lopez, Virginio; Aranega, Amelia; Garcia-Martinez, Virginio

    2015-10-01

    It is known that secreted proteins from the anterior lateral endoderm, FGF8 and BMP2, are involved in mesodermal cardiac differentiation, which determines the first cardiac field, defined by the expression of the earliest specific cardiac markers Nkx-2.5 and Gata4. However, the molecular mechanisms responsible for early cardiac development still remain unclear. At present, microRNAs represent a novel layer of complexity in the regulatory networks controlling gene expression during cardiovascular development. This paper aims to study the role of miR130 during early cardiac specification. Our model is focused on developing chick at gastrula stages. In order to identify those regulatory factors which are involved in cardiac specification, we conducted gain- and loss-of-function experiments in precardiac cells by administration of Fgf8, Bmp2 and miR130, through in vitro electroporation technique and soaked beads application. Embryos were subjected to in situ hybridization, immunohistochemistry and qPCR procedures. Our results reveal that Fgf8 suppresses, while Bmp2 induces, the expression of Nkx-2.5 and Gata4. They also show that Fgf8 suppresses Bmp2, and vice versa. Additionally, we observed that Bmp2 regulates miR-130 -a putative microRNA that targets Erk1/2 (Mapk1) 3'UTR, recognizing its expression in precardiac cells which overlap with Erk1/2 pattern. Finally, we evidence that miR-130 is capable to inhibit Erk1/2 and Fgf8, resulting in an increase of Bmp2, Nkx-2.5 and Gata4. Our data present miR-130 as a necessary linkage in the control of Fgf8 signaling, mediated by Bmp2, establishing a negative feed-back loop responsible to achieve early cardiac specification.

  14. PKD1 mediates negative feedback of PI3K/Akt activation in response to G protein-coupled receptors.

    Directory of Open Access Journals (Sweden)

    Yang Ni

    Full Text Available We examined whether protein kinase D1 (PKD1 mediates negative feeback of PI3K/Akt signaling in intestinal epithelial cells stimulated with G protein-coupled receptor (GPCR agonists. Exposure of intestinal epithelial IEC-18 cells to increasing concentrations of the PKD family inhibitor kb NB 142-70, at concentrations that inhibited PKD1 activation, strikingly potentiated Akt phosphorylation at Thr(308 and Ser(473 in response to the mitogenic GPCR agonist angiotensin II (ANG II. Enhancement of Akt activation by kb NB 142-70 was also evident in cells with other GPCR agonists, including vasopressin and lysophosphatidic acid. Cell treatment with the structurally unrelated PKD family inhibitor CRT0066101 increased Akt phosphorylation as potently as kb NB 142-70 [corrected]. Knockdown of PKD1 with two different siRNAs strikingly enhanced Akt phosphorylation in response to ANG II stimulation in IEC-18 cells. To determine whether treatment with kb NB 142-70 enhances accumulation of phosphatidylinositol (3,4,5-trisphosphate (PIP3 in the plasma membrane, we monitored the redistribution of Akt-pleckstrin homology domain-green fluorescent protein (Akt-PH-GFP in single IEC-18 cells. Exposure to kb NB 142-70 strikingly increased membrane accumulation of Akt-PH-GFP in response to ANG II. The translocation of the PIP3 sensor to the plasma membrane and the phosphorylation of Akt was completed prevented by prior exposure to the class I p110α specific inhibitor A66. ANG II markedly increased the phosphorylation of p85α detected by a PKD motif-specific antibody and enhanced the association of p85α with PTEN. Transgenic mice overexpressing PKD1 showed a reduced phosphorylation of Akt at Ser(473 in intestinal epithelial cells compared to wild type littermates. Collectively these results indicate that PKD1 activation mediates feedback inhibition of PI3K/Akt signaling in intestinal epithelial cells in vitro and in vivo.

  15. Mining Specific and General Features in Both Positive and Negative Relevance Feedback. QUT E-Discovery Lab at the TREC󈧍 Relevance Feedback Track

    Science.gov (United States)

    2009-11-01

    relevance feedback algo- rithm. Four methods, εMap [1], MapA , P10A, and StatAP [2], were used in the track to measure the performance of Phase 2 runs...εMap and StatAP were applied to the runs us- ing the testing set of only ClueWeb09 Category-B, whereas MapA and P10A were applied to those using the...whole ClueWeb09 English set. Because our experiments were based on only ClueWeb09 Category-B, measuring our per- formance by MapA and P10A might not

  16. Disturbance of the let-7/LIN28 double-negative feedback loop is associated with radio- and chemo-resistance in non-small cell lung cancer.

    Science.gov (United States)

    Yin, Jun; Zhao, Jian; Hu, Weimin; Yang, Guangping; Yu, Hui; Wang, Ruihao; Wang, Linjing; Zhang, Guoqian; Fu, Wenfan; Dai, Lu; Li, Wanzhen; Liao, Boyu; Zhang, Shuxu

    2017-01-01

    Radio- and chemo-resistance represent major obstacles in the therapy of non-small-cell lung cancer (NSCLC) and the underlying molecular mechanisms are not known. In the present study, during induction of radio- or chemo-resistance in NSCLC cells, dynamic analyses revealed that decreased expression of let-7 induced by irradiation or cisplatin resulted in increased expression of its target gene LIN28, and increased expression of LIN28 then contributed to further decreased expression of let-7 by inhibiting its maturation and biogenesis. Moreover, we showed that down-regulation of let-7 and up-regulation of LIN28 expression promoted resistance to irradiation or cisplatin by regulating the single-cell proliferative capability of NSCLC cells. Consequently, in NSCLC cells, let-7 and LIN28 can form a double-negative feedback loop through mutual inhibition, and disturbance of the let-7/LIN28 double-negative feedback loop induced by irradiation or chemotherapeutic drugs can result in radio- and chemo-resistance. In addition, low expression of let-7 and high expression of LIN28 in NSCLC patients was associated significantly with resistance to radiotherapy or chemotherapy. Therefore, our study demonstrated that disturbance of the let-7/LIN28 double-negative feedback loop is involved in the regulation of radio- and chemo-resistance, and that let-7 and LIN28 could be employed as predictive biomarkers of response to radiotherapy or chemotherapy in NSCLC patients.

  17. Monte Carlo simulations of the distributions of intra- and extra-vesicular ions and membrane associated charges in hybrid liposomes composed of negatively charged tetraether and zwitterionic diester phospholipids

    Directory of Open Access Journals (Sweden)

    István P. Sugár

    2017-04-01

    Full Text Available Here, we model a negatively charged lipid vesicle, composed of a mixture of bipolar tetraether and diester (or diether phospholipid molecules, by a spherical shell that has zero ion permeability. We take into consideration all the charge-charge interactions between intra-vesicular ions, extra-vesicular ions, and membrane lipid associated charges. Monte Carlo simulations result in homogeneous and double-exponential ion distribution, respectively, in the intra- and extra-vesicular space. The extra-vesicular ion concentration close to the membrane surface is proportional to the total amount of the membrane charges (Nm and is independent of the partitioning of the membrane charges between the outer (Nom and inner membrane (Nim surface. This result shows that one should not disregard the effect of the charges on the inner membrane surface when calculating the ion distributions around a charged vesicle. If the partitioning of the membrane charges is not restricted (i.e., lipid flip-flop is allowed, then at different Nm, the Nom/Nim ratio remains constant and the value of Nom/Nim, as a consequence of the interaction between every charges of the model, is close to, but significantly higher than, the ratio of the outer to the inner surface area of the membrane. These results indicate that the amount and the orientation of the negatively-charged tetraether lipids in the membrane are important determinants of membrane properties in tetraether/zwitterionic diester phospholipid liposomes. Finally we compared the results of our discrete charge model and continuous models based on the solutions of the Poisson-Boltzmann equation and pointed out qualitative similarities and sometimes major quantitative differences between these two types of models.

  18. BLOWIN' IN THE WIND: BOTH ''NEGATIVE'' AND ''POSITIVE'' FEEDBACK IN AN OBSCURED HIGH-z QUASAR

    Energy Technology Data Exchange (ETDEWEB)

    Cresci, G.; Mannucci, F. [INAF-Osservatorio Astrofisco di Arcetri, largo E. Fermi 5, I-50127, Firenze (Italy); Mainieri, V. [European Southern Observatory, Karl-Schwarzschild-strasse 2, D-85748 Garching bei München (Germany); Brusa, M.; Perna, M.; Lanzuisi, G. [Dipartimento di Fisica e Astronomia, Università di Bologna, viale Berti Pichat 6/2, I-40127 Bologna (Italy); Marconi, A. [Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, via G. Sansone 1, I-50019 Sesto F.no, Firenze (Italy); Piconcelli, E.; Feruglio, C.; Fiore, F.; Bongiorno, A. [INAF-Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone (Italy); Maiolino, R. [Cavendish Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge (United Kingdom); Merloni, A [Max Planck Institut für Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching bei München (Germany); Schramm, M.; Silverman, J. D. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, the University of Tokyo, Kashiwanoha 5-1-5, Kashiwa-shi, Chiba 277-8568 (Japan); Civano, F., E-mail: gcresci@arcetri.astro.it [Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, PO Box 208121, New Haven, CT 06520-8121 (United States)

    2015-01-20

    Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation in galaxies, preventing massive galaxies to overgrow and producing the red colors of ellipticals. On the other hand, some models are also requiring ''positive'' active galactic nucleus 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. Here we present SINFONI near infrared integral field spectroscopy of XID2028, an obscured, radio-quiet z = 1.59 QSO detected in the XMM-COSMOS survey, in which we clearly resolve a fast (1500 km s{sup –1}) and extended (up to 13 kpc from the black hole) outflow in the [O III] 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 from Hubble Space Telescope/Advanced Camera for Surveys imaging enable to map the current star formation in the host galaxy: both tracers independently 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.

  19. Feedback valence affects auditory perceptual learning independently of feedback probability

    OpenAIRE

    Amitay, S.; Moore, D. R.; Molloy, K.; Halliday, L. 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 wer...

  20. Differences between negative inotropic and vasodilator effects of calcium antagonists acting on extra- and intracellular calcium movements in rat and guinea-pig cardiac preparations

    NARCIS (Netherlands)

    Hugtenburg, J.G.; Mathy, M.-J.; Boddeke, H.W.G.M.; Beckeringh, J.J.; Van Zwieten, P.A.

    1989-01-01

    In order to get more insight into the utilization of calcium in the mammalian heart and the influence of calcium antagonists on this process we have evaluated the negative inotropic and vasodilator effect of nifedipine, diltiazem, verapamil, bepridil and lidoflazine as well as of the intracellularly

  1. A patient-specific model of the negative-feedback control of the hypothalamus-pituitary-thyroid (HPT) axis in autoimmune (Hashimoto's) thyroiditis.

    Science.gov (United States)

    Pandiyan, Balamurugan; Merrill, Stephen J; Benvenga, Salvatore

    2014-09-01

    The purpose of modelling the negative-feedback control mechanism of the hypothalamus-pituitary-thyroid (HPT) axis in autoimmune (Hashimoto's) thyroiditis is to describe the clinical course of euthyroidism, subclinical hypothyroidism and overt hypothyroidism for patients. Thyroid hormone thyroxine (T4) and triiodothyronine (T3) levels are controlled by negative-feedback control through thyroid-stimulating hormone (TSH). T4, like other hormones, can be bound or unbound; the unbound T4 (FT4) is used as a marker for hypothyroidism. Autoimmune thyroiditis is a disease in which the thyroid-infiltrating lymphocytes attack autoantigens in follicle cells, destroying them over a long time. To describe the operation of the feedback control, we developed a mathematical model involving four clinical variables: TSH, FT4, anti-thyroid peroxidase antibodies and the thyroid gland's functional size. The first three variables are regularly measured while the last variable is determined through relationships between the other three variables. The problem of two different time scales for circulating hormones and thyroid damage is addressed using singular perturbation theory. Analysis of the mathematical model establishes stability and conditions under which the diseased state can maintain the slow movement toward diseased state equilibrium. Although we have used four variables in modelling the feedback control through the HPT axis, the predicted clinical course given any set of parameters is shown to depend on the steady-state levels of TSH and FT4. This observation makes possible the development of the clinical charts based only on the levels of TSH, time and potential steady-state values. To validate the model predictions, a dataset obtained from a Sicilian adult population has been employed. © The Authors 2013. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.

  2. Negative feedback regulation is responsible for the non-linear modulation of photosynthetic activity in plants and cyanobacteria exposed to a dynamic light environment.

    Science.gov (United States)

    Nedbal, Ladislav; Brezina, Vítezslav; Adamec, Frantisek; Stys, Dalibor; Oja, Vello; Laisk, Agu; Govindjee

    2003-10-17

    Photosynthetic organisms exposed to a dynamic light environment exhibit complex transients of photosynthetic activities that are strongly dependent on the temporal pattern of the incident irradiance. In a harmonically modulated light of intensity I approximately const.+sin(omegat), chlorophyll fluorescence response consists of a steady-state component, a component modulated with the angular frequency of the irradiance omega and several upper harmonic components (2omega, 3omega and higher). Our earlier reverse engineering analysis suggests that the non-linear response can be caused by a negative feedback regulation of photosynthesis. Here, we present experimental evidence that the negative feedback regulation of the energetic coupling between phycobilisome and Photosystem II (PSII) in the cyanobacterium Synechocystis sp. PCC6803 indeed results in the appearance of upper harmonic modes in the chlorophyll fluorescence emission. Dynamic changes in the coupling of the phycobilisome to PSII are not accompanied by corresponding antiparallel changes in the Photosystem I (PSI) excitation, suggesting a regulation limited to PSII. Strong upper harmonic modes were also found in the kinetics of the non-photochemical quenching (NPQ) of chlorophyll fluorescence, of the P700 redox state and of the CO(2) assimilation in tobacco (Nicotiana tabaccum) exposed to harmonically modulated light. They are ascribed to negative feedback regulation of the reactions of the Calvin-Benson cycle limiting the photosynthetic electron transport. We propose that the observed non-linear response of photosynthesis may also be relevant in a natural light environment that is modulated, e.g., by ocean waves, moving canopy or by varying cloud cover. Under controlled laboratory conditions, the non-linear photosynthetic response provides a new insight into dynamics of the regulatory processes.

  3. Simulation of Low Gain Avalanche Detector characteristics based on the concept of negative feedback in irradiated silicon detectors with carrier impact ionization

    Science.gov (United States)

    Verbitskaya, E.; Eremin, V.; Zabrodskii, A.; Luukka, P.

    2016-12-01

    In this study the main characteristics of silicon Low Gain Avalanche Detectors (LGAD), the dependencies of the collected charge versus bias voltage and fluence, are calculated to fit experimental data. The calculations are based on two previously developed Ioffe Institute models of radiation degradation in Si detectors: 1) a model of two effective energy levels of radiation-induced defects, and 2) a mechanism of internal negative feedback responsible for the gain degradation in irradiated Si detectors originating from the avalanche multiplication at the detector junction. The combination of these models describes well the properties of irradiated p-i-n detectors in a wide range of fluences. For simulating the LGAD characteristics the models are adapted to its n+-pbi-p-p+ structure, where the built-in boron-doped layer pbi produces high electric field sufficient for carrier impact ionization. It is shown that the developed models give adequate quantitative description of the experimental results for the LGADs up to the fluence of 2×1015 n/cm2 including the detector pulse response; however, additional boron removal from the pbi layer is required to have the best correlation with the experimental data. Similar to the physical model developed for silicon strip detectors operated at high voltage, the results are interpreted in terms of the internal negative feedback mechanism. It is shown that in irradiated LGADs this feedback leads to the transfer of a significant fraction of the potential drop from the built-in layer toward the p+ contact. It initiates two negative effects, which both cause the gain degradation with irradiation: the lowering of the electric field in the n+-pbi region that reduces the multiplication probability, and the increase of the collection time and trapping-related charge losses.

  4. An intercomparison between the surface heat flux feedback in five coupled models, COADS and the NCEP reanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Frankignoul, C.; Kestenare, E. [Universite Pierre et Marie Curie, Institute Pierre-Simon Laplace, Laboratoire d' Oceanographie Dynamique et de Climatologie, 4 place Jussieu, 75252 Paris Cedex 05 (France); Botzet, M. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Carril, A.F. [Istituto Nazionale di Geofisica e Vulcanologia, Bologna (Italy); Drange, H. [Nansen Environmental and Remote Sensing Center, Bergen (Norway); Pardaens, A. [Hadley Centre for Climate Prediction and Research, Met Office (United Kingdom); Terray, L.; Sutton, R. [Department of Meteorology, University of Reading (United Kingdom)

    2004-04-01

    The surface heat flux feedback is estimated in the Atlantic and the extra-tropical Indo-Pacific, using monthly heat flux and sea surface temperature anomaly data from control simulations with five global climate models, and it is compared to estimates derived from COADS and the NCEP reanalysis. In all data sets, the heat flux feedback is negative nearly everywhere and damps the sea surface temperature anomalies. At extra-tropical latitudes, it is strongly dominated by the turbulent fluxes. The radiative feedback can be positive or negative, depending on location and season, but it remains small, except in some models in the tropical Atlantic. The negative heat flux feedback is strong in the mid-latitude storm tracks, exceeding 40 W m{sup -2} K{sup -1} at place, but in the Northern Hemisphere it is substantially underestimated in several models. The negative feedback weakens at high latitudes, although the models do not reproduce the weak positive feedback found in NCEP in the northern North Atlantic. The main differences are found in the tropical Atlantic where the heat flux feedback is weakly negative in some models, as in the observations, and strongly negative in others where it can exceed 30 W m{sup -2} K{sup -1} at large scales, in part because of a strong contribution of the radiative fluxes, in particular during spring. A comparison between models with similar atmospheric or oceanic components suggests that the atmospheric model is primarily responsible for the heat flux feedback differences at extra-tropical latitudes. In the tropical Atlantic, the ocean behavior plays an equal role. The differences in heat flux feedback in the tropical Atlantic are reflected in the sea surface temperature anomaly persistence, which is too small in models where the heat flux damping is large. A good representation of the heat flux feedback is thus required to simulate climate variability realistically. (orig.)

  5. Subjective and model-estimated reward prediction: association with the feedback-related negativity (FRN) and reward prediction error in a reinforcement learning task.

    Science.gov (United States)

    Ichikawa, Naho; Siegle, Greg J; Dombrovski, Alexandre; Ohira, Hideki

    2010-12-01

    In this study, we examined whether the feedback-related negativity (FRN) is associated with both subjective and objective (model-estimated) reward prediction errors (RPE) per trial in a reinforcement learning task in healthy adults (n=25). The level of RPE was assessed by 1) subjective ratings per trial and by 2) a computational model of reinforcement learning. As results, model-estimated RPE was highly correlated with subjective RPE (r=.82), and the grand-averaged ERP waves based on the trials with high and low model-estimated RPE showed the significant difference only in the time period of the FRN component (pcontingency.

  6. Evaluation of rapid techniques for the detection of mycobacteria in sputum with scanty bacilli or clinically evident, smear negative cases of pulmonary and extra-pulmonary tuberculosis

    Directory of Open Access Journals (Sweden)

    Pottathil Shinu

    2011-08-01

    Full Text Available The objective of the current study was to compare two rapid methods, the BBL Mycobacteria Growth Indicator Tube (MGIT TM and Biotec FASTPlaque TB TM (FPTB assays, with the conventional Löwenstein-Jensen (LJ media assay to diagnose mycobacterial infections from paucibacillary clinical specimens. For evaluation of the clinical utility of the BBL MGIT TM and FPTB assays, respiratory tract specimens (n = 208, with scanty bacilli or clinically evident, smear negative cases and non-respiratory tract specimens (n = 119 were analyzed and the performance of each assay was compared with LJ media. MGIT and FPTB demonstrated a greater sensitivity (95.92% and 87.68%, specificity (94.59% and 98.78%, positive predictive value (94.91% and 99.16% and negative predictive value (96.56% and 90.92%, respectively, compared to LJ culture for both respiratory tract and non-respiratory tract specimens. However, the FPTB assay was unable to detect nontuberculous mycobacteria and few Mycobacterium tuberculosis complex cases from paucibacillary clinical specimens. It is likely that the analytical sensitivity of FPTB is moderately low and may not be useful for the direct detection of tuberculosis in paucibacillary specimens. The current study concluded that MGIT was a dependable, highly efficient system for recovery of M. tuberculosis complexes and nontuberculous mycobacteria from both respiratory and non-respiratory tract specimens in combination with LJ media.

  7. A Negative Feedback Loop Controlling bHLH Complexes Is Involved in Vascular Cell Division and Differentiation in the Root Apical Meristem.

    Science.gov (United States)

    Katayama, Hirofumi; Iwamoto, Kuninori; Kariya, Yuka; Asakawa, Tomohiro; Kan, Toshiyuki; Fukuda, Hiroo; Ohashi-Ito, Kyoko

    2015-12-07

    Controlling cell division and differentiation in meristems is essential for proper plant growth. Two bHLH heterodimers consisting of LONESOME HIGHWAY (LHW) and TARGET OF MONOPTEROS 5 (TMO5)/TMO5-LIKE1 (T5L1) regulate periclinal cell division in vascular cells in the root apical meristem (RAM). In this study, we further investigated the functions of LHW-T5L1, finding that in addition to controlling cell division, this complex regulates xylem differentiation in the RAM via a novel negative regulatory system. LHW-T5L1 upregulated the thermospermine synthase gene ACAULIS5 (ACL5), as well as SUPPRESSOR OF ACAULIS5 LIKE3 (SACL3), which encodes a bHLH protein, in the RAM. The SACL3 promoter sequence contains a conserved upstream open reading frame (uORF), which blocked translation of the main SACL3 ORF in the absence of thermospermine. Thermospermine eliminated the negative effect of uORF and enhanced SACL3 production. Further genetic and molecular biological analyses indicated that ACL5 and SACL3 suppress the function of LHW-T5L1 through a protein-protein interaction between LHW and SACL3. Finally, we showed that a negative feedback loop consisting of LHW-T5L1, ACL5, SACL3, and LHW-SACL3 contributes to maintain RAM size and proper root growth. These findings suggest that a negative feedback loop regulates the LHW-T5L1 output level to coordinate cell division and differentiation in a cell-autonomous manner. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Using Satellite Data to Represent Tropical Instability Waves (TIWs-Induced Wind for Ocean Modeling: A Negative Feedback onto TIW Activity in the Pacific

    Directory of Open Access Journals (Sweden)

    Jinzhong Min

    2013-05-01

    Full Text Available Recent satellite data and modeling studies indicate a pronounced role Tropical Instability Waves (TIW-induced wind feedback plays in the tropical Pacific climate system. Previously, remotely sensed data were used to derive a diagnostic model for TIW-induced wind stress perturbations (τTIW, which was embedded into an ocean general circulation model (OGCM to take into account TIW-induced ocean-atmosphere coupling in the tropical Pacific. While the previous paper by Zhang (2013 is concerned with the effect on the mean ocean state, the present paper is devoted to using the embedded system to examine the effects on TIW activity in the ocean, with τTIW being interactively determined from TIW-scale sea surface temperature (SSTTIW fields generated in the OGCM, written as τTIW = αTIW·F(SSTTIW, where αTIW is a scalar parameter introduced to represent the τTIW forcing intensity. Sensitivity experiments with varying αTIW (representing TIW-scale wind feedback strength are performed to illustrate a negative feedback induced by TIW-scale air-sea coupling and its relationship with TIW variability in the ocean. Consistent with previous modeling studies, TIW wind feedback tends to have a damping effect on TIWs in the ocean, with a general inverse relationship between the τTIW intensity and TIWs. It is further shown that TIW-scale coupling does not vary linearly with αTIW: the coupling increases linearly with intensifying τTIW forcing at low values of αTIW (in a weak τTIW forcing regime; it becomes saturated at a certain value of αTIW; it decreases when αTIW goes above a threshold value as the τTIW forcing increases further. This work presents a clear demonstration of using satellite data to effectively represent TIW-scale wind feedback and its multi-scale interactions with large-scale ocean processes in the tropical Pacific.

  9. HER2 phosphorylation is maintained by a PKB negative feedback loop in response to anti-HER2 herceptin in breast cancer.

    Science.gov (United States)

    Gijsen, Merel; King, Peter; Perera, Tim; Parker, Peter J; Harris, Adrian L; Larijani, Banafshé; Kong, Anthony

    2010-12-21

    Herceptin (trastuzumab) is used in patients with breast cancer who have HER2 (ErbB2)-positive tumours. However, its mechanisms of action and how acquired resistance to Herceptin occurs are still poorly understood. It was previously thought that the anti-HER2 monoclonal antibody Herceptin inhibits HER2 signalling, but recent studies have shown that Herceptin does not decrease HER2 phosphorylation. Its failure to abolish HER2 phosphorylation may be a key to why acquired resistance inevitably occurs for all responders if Herceptin is given as monotherapy. To date, no studies have explained why Herceptin does not abolish HER2 phosphorylation. The objective of this study was to investigate why Herceptin did not decrease HER2 phosphorylation despite being an anti-HER2 monoclonal antibody. We also investigated the effects of acute and chronic Herceptin treatment on HER3 and PKB phosphorylation in HER2-positive breast cancer cells. Using both Förster resonance energy transfer (FRET) methodology and conventional Western blot, we have found the molecular mechanisms whereby Herceptin fails to abolish HER2 phosphorylation. HER2 phosphorylation is maintained by ligand-mediated activation of EGFR, HER3, and HER4 receptors, resulting in their dimerisation with HER2. The release of HER ligands was mediated by ADAM17 through a PKB negative feedback loop. The feedback loop was activated because of the inhibition of PKB by Herceptin treatment since up-regulation of HER ligands and ADAM17 also occurred when PKB phosphorylation was inhibited by a PKB inhibitor (Akt inhibitor VIII, Akti-1/2). The combination of Herceptin with ADAM17 inhibitors or the panHER inhibitor JNJ-26483327 was able to abrogate the feedback loop and decrease HER2 phosphorylation. Furthermore, the combination of Herceptin with JNJ-26483327 was synergistic in tumour inhibition in a BT474 xenograft model. We have determined that a PKB negative feedback loop links ADAM17 and HER ligands in maintaining HER2

  10. HER2 phosphorylation is maintained by a PKB negative feedback loop in response to anti-HER2 herceptin in breast cancer.

    Directory of Open Access Journals (Sweden)

    Merel Gijsen

    Full Text Available Herceptin (trastuzumab is used in patients with breast cancer who have HER2 (ErbB2-positive tumours. However, its mechanisms of action and how acquired resistance to Herceptin occurs are still poorly understood. It was previously thought that the anti-HER2 monoclonal antibody Herceptin inhibits HER2 signalling, but recent studies have shown that Herceptin does not decrease HER2 phosphorylation. Its failure to abolish HER2 phosphorylation may be a key to why acquired resistance inevitably occurs for all responders if Herceptin is given as monotherapy. To date, no studies have explained why Herceptin does not abolish HER2 phosphorylation. The objective of this study was to investigate why Herceptin did not decrease HER2 phosphorylation despite being an anti-HER2 monoclonal antibody. We also investigated the effects of acute and chronic Herceptin treatment on HER3 and PKB phosphorylation in HER2-positive breast cancer cells. Using both Förster resonance energy transfer (FRET methodology and conventional Western blot, we have found the molecular mechanisms whereby Herceptin fails to abolish HER2 phosphorylation. HER2 phosphorylation is maintained by ligand-mediated activation of EGFR, HER3, and HER4 receptors, resulting in their dimerisation with HER2. The release of HER ligands was mediated by ADAM17 through a PKB negative feedback loop. The feedback loop was activated because of the inhibition of PKB by Herceptin treatment since up-regulation of HER ligands and ADAM17 also occurred when PKB phosphorylation was inhibited by a PKB inhibitor (Akt inhibitor VIII, Akti-1/2. The combination of Herceptin with ADAM17 inhibitors or the panHER inhibitor JNJ-26483327 was able to abrogate the feedback loop and decrease HER2 phosphorylation. Furthermore, the combination of Herceptin with JNJ-26483327 was synergistic in tumour inhibition in a BT474 xenograft model. We have determined that a PKB negative feedback loop links ADAM17 and HER ligands in maintaining

  11. Discoidin domain receptor 2-microRNA 196a-mediated negative feedback against excess type I collagen expression is impaired in scleroderma dermal fibroblasts.

    Science.gov (United States)

    Makino, Katsunari; Jinnin, Masatoshi; Aoi, Jun; Hirano, Ayaka; Kajihara, Ikko; Makino, Takamitsu; Sakai, Keisuke; Fukushima, Satoshi; Inoue, Yuji; Ihn, Hironobu

    2013-01-01

    Systemic sclerosis (SSc) is characterized by excess collagen deposition in the skin, due to intrinsic transforming growth factor-β (TGF-β) activation. We tried to determine the expression and the role of discoidin domain receptor 2 (DDR2) in SSc. The expression of DDR2 mRNA and protein was significantly decreased in SSc dermal fibroblasts, which was recovered by knocking down TGF-β. The knockdown of DDR2 in normal fibroblasts induced microRNA-196a expression, which led to type I collagen downregulation, indicating that DDR2 itself has a negative effect on microRNA-196a expression and inducible effect on collagen expression. In SSc fibroblasts, however, the DDR2 knockdown did not affect TGF-β signaling and microRNA-196a expression. The microRNA-196a levels were significantly decreased in normal fibroblasts treated with TGF-β and in SSc fibroblasts. Taken together our data indicate that, in SSc fibroblasts, intrinsic TGF-β stimulation induces type I collagen expression, and also downregulates DDR2 expression. This probably acts as a negative feedback mechanism against excess collagen expression, as a decreased DDR2 expression is supposed to stimulate the microRNA-196a expression and further change the collagen expression. However, in SSc fibroblasts the microRNA-196a expression was downregulated by TGF-β signaling. DDR2-microRNA-196a pathway may be a previously unreported negative feedback system, and its impairment may be involved in the pathogenesis of SSc.

  12. MicroRNA miR-308 regulates dMyc through a negative feedback loop in Drosophila

    Directory of Open Access Journals (Sweden)

    Kaveh Daneshvar

    2012-10-01

    The abundance of Myc protein must be exquisitely controlled to avoid growth abnormalities caused by too much or too little Myc. An intriguing mode of regulation exists in which Myc protein itself leads to reduction in its abundance. We show here that dMyc binds to the miR-308 locus and increases its expression. Using our gain-of-function approach, we show that an increase in miR-308 causes a destabilization of dMyc mRNA and reduced dMyc protein levels. In vivo knockdown of miR-308 confirmed the regulation of dMyc levels in embryos. This regulatory loop is crucial for maintaining appropriate dMyc levels and normal development. Perturbation of the loop, either by elevated miR-308 or elevated dMyc, caused lethality. Combining elevated levels of both, therefore restoring balance between miR-308 and dMyc levels, resulted in lower apoptotic activity and suppression of lethality. These results reveal a sensitive feedback mechanism that is crucial to prevent the pathologies caused by abnormal levels of dMyc.

  13. Double-negative feedback between S-phase cyclin-CDK and CKI generates abruptness in the G1/S switch

    Directory of Open Access Journals (Sweden)

    Rainis eVenta

    2012-12-01

    Full Text Available The G1/S transition is a crucial decision point in the cell cycle. At G1/S, there is an abrupt switch from a state of high CDK inhibitor (CKI levels and low S-phase CDK activity to a state of high S-phase CDK activity and degraded CKI. In budding yeast, this transition is triggered by phosphorylation of the Cdk1 inhibitor Sic1 at multiple sites by G1-phase CDK (Cln1,2-Cdk1 and S-phase CDK (Clb5,6-Cdk1 complexes. Using mathematical modeling we demonstrate that the mechanistic basis for the abruptness and irreversibility of the G1/S transition is the highly specific phosphorylation of Sic1 by S-phase CDK complex. This switch is generated by a double negative feedback loop in which S-CDK1 phosphorylates Sic1, thus targeting it for destruction, and thereby liberating further S-CDK1 from the inhibitory Sic1-S-CDK1 complex. Our model predicts that the abruptness of the switch depends upon a strong binding affinity within the Sic1-S-CDK inhibitory complex. In vitro phosphorylation analysis using purified yeast proteins revealed that free Clb5-Cdk1 can create positive feedback by phosphorylating Sic1 that is bound in the inhibitory complex, and that Sic1 inhibits Clb5-Cdk1 with a sub-nanomolar inhibition constant. Our model also predicts that if the G1-phase CDK complex is too efficient at targeting Sic1 for destruction, then G1/S becomes a smooth and readily reversible transition. We propose that the optimal role for the G1-phase CDK in the switch would not be to act as a kinase activity directly responsible for abrupt degradation of CKI, but rather to act as a priming signal that initiates a positive feedback loop driven by emerging free S-phase CDK.

  14. Non-linear states of a positive or negative refraction index material in a cavity with feedback

    Science.gov (United States)

    Mártin, D. A.; Hoyuelos, M.

    2010-06-01

    We study a system composed by a cavity with plane mirrors containing a positive or negative refraction index material with third order effective electric and magnetic non-linearities. The aim of the work is to present a general picture of possible non-linear states in terms of the relevant parameters of the system. The parameters are the ones that appear in a reduced description that has the form of the Lugiato-Lefever equation. This equation is obtained from two coupled non-linear Schrödinger equations for the electric and magnetic field amplitudes.

  15. The Feedback-Related Negativity and the P300 Brain Potential Are Sensitive to Price Expectation Violations in a Virtual Shopping Task.

    Science.gov (United States)

    Schaefer, Alexandre; Buratto, Luciano G; Goto, Nobuhiko; Brotherhood, Emilie V

    A large body of evidence shows that buying behaviour is strongly determined by consumers' price expectations and the extent to which real prices violate these expectations. Despite the importance of this phenomenon, little is known regarding its neural mechanisms. Here we show that two patterns of electrical brain activity known to index prediction errors-the Feedback-Related Negativity (FRN) and the feedback-related P300 -were sensitive to price offers that were cheaper than participants' expectations. In addition, we also found that FRN amplitude time-locked to price offers predicted whether a product would be subsequently purchased or not, and further analyses suggest that this result was driven by the sensitivity of the FRN to positive price expectation violations. This finding strongly suggests that ensembles of neurons coding positive prediction errors play a critical role in real-life consumer behaviour. Further, these findings indicate that theoretical models based on the notion of prediction error, such as the Reinforcement Learning Theory, can provide a neurobiologically grounded account of consumer behavior.

  16. The Feedback-Related Negativity and the P300 Brain Potential Are Sensitive to Price Expectation Violations in a Virtual Shopping Task

    Science.gov (United States)

    Schaefer, Alexandre; Buratto, Luciano G.; Goto, Nobuhiko; Brotherhood, Emilie V.

    2016-01-01

    A large body of evidence shows that buying behaviour is strongly determined by consumers’ price expectations and the extent to which real prices violate these expectations. Despite the importance of this phenomenon, little is known regarding its neural mechanisms. Here we show that two patterns of electrical brain activity known to index prediction errors–the Feedback-Related Negativity (FRN) and the feedback-related P300 –were sensitive to price offers that were cheaper than participants’ expectations. In addition, we also found that FRN amplitude time-locked to price offers predicted whether a product would be subsequently purchased or not, and further analyses suggest that this result was driven by the sensitivity of the FRN to positive price expectation violations. This finding strongly suggests that ensembles of neurons coding positive prediction errors play a critical role in real-life consumer behaviour. Further, these findings indicate that theoretical models based on the notion of prediction error, such as the Reinforcement Learning Theory, can provide a neurobiologically grounded account of consumer behavior. PMID:27658301

  17. It's not what you expect: feedback negativity is independent of reward expectation and affective responsivity in a non-probabilistic task.

    Science.gov (United States)

    Highsmith, Jonathan M; Wuensch, Karl L; Tran, Tuan; Stephenson, Alexandra J; Everhart, D Erik

    2017-03-01

    ERP studies commonly utilize gambling-based reinforcement tasks to elicit feedback negativity (FN) responses. This study used a pattern learning task in order to limit gambling-related fallacious reasoning and possible affective responses to gambling, while investigating relationships between the FN components between high and low reward expectation conditions. Eighteen undergraduates completed measures of reinforcement sensitivity, trait and state affect, and psychophysiological recording. The pattern learning task elicited a FN component for both high and low win expectancy conditions, which was found to be independent of reward expectation and showed little relationship with task and personality variables. We also observed a P3 component, which showed sensitivity to outcome expectancy variation and relationships to measures of anxiety, appetitive motivation, and cortical asymmetry, although these varied by electrode location and expectancy condition. Findings suggest that the FN reflected a binary reward-related signal, with little relationship to reward expectation found in previous studies, in the absence of positive affective responses.

  18. Synergism between insecticides permethrin and propoxur occurs through activation of presynaptic muscarinic negative feedback of acetylcholine release in the insect central nervous system.

    Science.gov (United States)

    Corbel, Vincent; Stankiewicz, Maria; Bonnet, Julien; Grolleau, Françoise; Hougard, Jean Marc; Lapied, Bruno

    2006-07-01

    Although synergism between pesticides has been widely documented, the physiological mechanisms by which an insecticide synergizes another remains unclear. Toxicological and electrophysiological studies were carried out on two susceptible pest species (the mosquito Culex quinquefasciatus and the cockroach Periplaneta americana) to understand better the physiological process involved in pyrethroid and carbamate interactions. Larval bioassays were conducted with the susceptible reference strain SLAB of C. quinquefasciatus to assess the implication of multi-function oxidases and non-specific esterases in insecticide detoxification and synergism. Results showed that the general theory of synergism (competition between pesticides for a common detoxification enzyme) was unlikely to occur in the SLAB strain since the level of synergy recorded between permethrin and propoxur was unchanged in the presence of piperonyl butoxide and tribufos, two inhibitors of oxidases and esterases, respectively (synergism ratios were similar with and without synergists). We also showed that addition of a sub-lethal concentration of nicotine significantly increased the toxicity of permethrin and propoxur at the lower range of the dose-mortality regression lines, suggesting the manifestation of important physiological disruptions at synaptic level. The effects of both permethrin and propoxur were studied on the cercal-afferent giant-interneuron synapses in the terminal abdominal ganglion of the cockroach P. americana using the single-fibre oil-gap method. We demonstrated that permethrin and propoxur increased drastically the ACh concentration within the synaptic cleft, which thereby stimulated a negative feedback of ACh release. Atropine, a muscarinic receptor antagonist, reversed the effect of permethrin and propoxur mixtures. This demonstrates the implication of the presynaptic muscarinic receptors in the negative feedback regulation process and in synergism. Based on these findings, we

  19. Fulfilling Desire: Evidence for negative feedback between men’s testosterone, sociosexual psychology, and sexual partner number

    Science.gov (United States)

    Puts, David A.; Pope, Lauramarie E.; Hill, Alexander K.; Cárdenas, Rodrigo A.; Welling, Lisa L. M.; Wheatley, John R.; Breedlove, S. Marc

    2015-01-01

    Across human societies and many nonhuman animals, males have greater interest in uncommitted sex (more unrestricted sociosexuality) than do females. Testosterone shows positive associations with male-typical sociosexual behavior in nonhuman animals. Yet, it remains unclear whether the human sex difference in sociosexual psychology (attitudes and desires) is mediated by testosterone, whether any relationships between testosterone and sociosexuality differ between men and women, and what the nature of these possible relationships might be. In studies to resolve these questions, we examined relationships between salivary testosterone concentrations and sociosexual psychology and behavior in men and women. We measured testosterone in all men in our sample, but only in those women taking oral contraception (OC-using women) in order to reduce the influence of ovulatory cycle variation in ovarian hormone production. We found that OC-using women did not differ from normally-ovulating women in sociosexual psychology or behavior, but that circulating testosterone mediated the sex difference in human sociosexuality and predicted sociosexual psychology in men but not OC-using women. Moreover, when sociosexual psychology was controlled, men’s sociosexual behavior (number of sexual partners) was negatively related to testosterone, suggesting that testosterone drives sociosexual psychology in men and is inhibited when those desires are fulfilled. This more complex relationship between androgen and male sexuality may reconcile some conflicting prior reports. PMID:25644313

  20. Double negative feedback loop between reprogramming factor LIN28 and microRNA let-7 regulates aldehyde dehydrogenase 1-positive cancer stem cells

    Science.gov (United States)

    Yang, Xiaojun; Lin, Xiaojuan; Zhong, Xiaomin; Kaur, Sippy; Li, Ning; Liang, Shun; Lassus, Heini; Wang, Liping; Katsaros, Dionyssios; Montone, Kathleen; Zhao, Xia; Zhang, Youcheng; Bützow, Ralf; Coukos, George; Zhang, Lin

    2010-01-01

    A relatively rare aldehyde dehydrogenase 1 (ALDH1) positive “stem cell-like” subpopulation of tumor cells has the unique ability to initiate and perpetuate tumor growth; moreover it is highly resistant to chemotherapy and significantly associated with poor clinical outcomes. The development of more effective therapies for cancer requires targeting of this cell population. Using cDNA microarray analysis, we identified that the expression of the C. elegans lin-28 homolog (LIN28) was positively correlated with the percentage of ALDH1+ tumor cells; this was further validated in an independent set of tissue arrays (n=197). Both lose-of-function and gain-of-function studies demonstrated that LIN28 plays a critical role in the maintenance of ALDH1+ tumor cells. In addition, we found that there is a double negative feedback loop between LIN28 and let-7 in tumor cells, and that let-7 negatively regulates ALDH1+ tumor cells. Finally, we report that a LIN28/let-7 loop modulates self renewal and differentiation of mammary gland epithelial progenitor cells. Our data provide evidence that cancer stem cells may arise through a “reprogramming-like” mechanism. A rebalancing of the LIN28/let-7 regulatory loop could be a novel therapeutic strategy to target ALDH1+ cancer stem cells. PMID:21045151

  1. Negative feedback circuit for toll like receptor-8 activation in human embryonic Kidney 293 using outer membrane vesicle delivered bi-specific siRNA.

    Science.gov (United States)

    Adhikari, Anurag; Gupta, Birendra Prasad; Das Manandhar, Krishna; Mishra, Shravan Kumar; Saiju, Hari Krishna; Shrestha, Rajendra Maan; Mishra, Nawneet; Sharma, Shishir

    2015-07-23

    TLR8 assists in antiviral approach by producing Type 1 INF via MyD88 dependent IRF7 pathway. However, over expression of INFα/β molecule poses threat by developing tolerance in chronic infection cases and enhancing inflammatory response. Here we report a bi-specific siRNA based complex which differentially activates and silences the TLR8 and MYD88 respectively in a negatively regulated fashion. Outer membrane vesicle from Escherichia coli used for siRNA delivery was observed more efficient when attached with invasive protein Ail along with OmpA (Pmembrane vesicle, thus facilitating the escape of siRNA complex to the host cytoplasm in order to silence MyD88 transcript (P<0.001). We investigated the activation of TLR8 by bi-specific si-RNA for the production of INFβ. In the same setting we showed that bi-specific si-RNA was able to silence MyD88 transcript in a delayed manner. For the cases of auto immune disease and inflammation where over activation of endosomal TLRs poses serious threat, bi specific siRNA could be used as negative feedback controlled system.

  2. Shrimp with knockdown of LvSOCS2, a negative feedback loop regulator of JAK/STAT pathway in Litopenaeus vannamei, exhibit enhanced resistance against WSSV.

    Science.gov (United States)

    Wang, Sheng; Song, Xuan; Zhang, Zijian; Li, Haoyang; L, Kai; Yin, Bin; He, Jianguo; Li, Chaozheng

    2016-12-01

    JAK/STAT pathway is one of cytokine signaling pathways and mediates diversity immune responses to protect host from viral infection. In this study, LvSOCS2, a member of suppressor of cytokine signaling (SOCS) families, has been cloned and identified from Litopenaeus vannamei. The full length of LvSOCS2 is 1601 bp, including an 1194 bp open reading frame (ORF) coding for a putative protein of 397 amino acids with a calculated molecular weight of ∼42.3 kDa. LvSOCS2 expression was most abundant in gills and could respond to the challenge of LPS, Vibrio parahaemolyticus, Staphhylococcus aureus, Poly (I: C) and white spot syndrome virus (WSSV). There are several STAT binding motifs presented in the proximal promoter region of LvSOCS2 and its expression was induced by LvJAK or LvSTAT protein in a dose dependent manner, suggesting LvSOCS2 could be the transcriptional target gene of JAK/STAT pathway. Moreover, the transcription of DmVir-1, a read out of the activation of JAK/STAT pathway in Drosophila, was promoted by LvJAK but inhibited by LvSOCS2, indicating that LvSOCS2 could be a negative regulator in this pathway and thus can form a negative feedback loop. Our previous study indicated that shrimp JAK/STAT pathway played a positive role against WSSV. In this study, RNAi-mediated knockdown of LvSOCS2 shrimps showed lower susceptibility to WSSV infection and caused lessened virus loads, which further demonstrated that the JAK/STAT pathway could function as an anti-viral immunity in shrimp.

  3. TRIM30α Is a Negative-Feedback Regulator of the Intracellular DNA and DNA Virus-Triggered Response by Targeting STING.

    Directory of Open Access Journals (Sweden)

    Yanming Wang

    2015-06-01

    Full Text Available Uncontrolled immune responses to intracellular DNA have been shown to induce autoimmune diseases. Homeostasis regulation of immune responses to cytosolic DNA is critical for limiting the risk of autoimmunity and survival of the host. Here, we report that the E3 ubiquitin ligase tripartite motif protein 30α (TRIM30α was induced by herpes simplex virus type 1 (HSV-1 infection in dendritic cells (DCs. Knockdown or genetic ablation of TRIM30α augmented the type I IFNs and interleukin-6 response to intracellular DNA and DNA viruses. Trim30α-deficient mice were more resistant to infection by DNA viruses. Biochemical analyses showed that TRIM30α interacted with the stimulator of interferon genes (STING, which is a critical regulator of the DNA-sensing response. Overexpression of TRIM30α promoted the degradation of STING via K48-linked ubiquitination at Lys275 through a proteasome-dependent pathway. These findings indicate that E3 ligase TRIM30α is an important negative-feedback regulator of innate immune responses to DNA viruses by targeting STING.

  4. TRIM30α Is a Negative-Feedback Regulator of the Intracellular DNA and DNA Virus-Triggered Response by Targeting STING.

    Directory of Open Access Journals (Sweden)

    Yanming Wang

    2015-06-01

    Full Text Available Uncontrolled immune responses to intracellular DNA have been shown to induce autoimmune diseases. Homeostasis regulation of immune responses to cytosolic DNA is critical for limiting the risk of autoimmunity and survival of the host. Here, we report that the E3 ubiquitin ligase tripartite motif protein 30α (TRIM30α was induced by herpes simplex virus type 1 (HSV-1 infection in dendritic cells (DCs. Knockdown or genetic ablation of TRIM30α augmented the type I IFNs and interleukin-6 response to intracellular DNA and DNA viruses. Trim30α-deficient mice were more resistant to infection by DNA viruses. Biochemical analyses showed that TRIM30α interacted with the stimulator of interferon genes (STING, which is a critical regulator of the DNA-sensing response. Overexpression of TRIM30α promoted the degradation of STING via K48-linked ubiquitination at Lys275 through a proteasome-dependent pathway. These findings indicate that E3 ligase TRIM30α is an important negative-feedback regulator of innate immune responses to DNA viruses by targeting STING.

  5. Identification of a negative feedback loop between cyclic di-GMP-induced levels of IFI16 and p202 cytosolic DNA sensors and STING.

    Science.gov (United States)

    Panchanathan, Ravichandran; Liu, Hongzhu; Xin, Duan; Choubey, Divaker

    2014-10-01

    A host type I IFN response is induced by cytosolic sensing of the bacterial second messenger cyclic-di-GMP (c-di-GMP) by STING (stimulator of IFN genes). Because the STING, an adaptor protein, links the cytosolic detection of DNA by the cytosolic DNA sensors such as the IFN-inducible human IFI16 and murine p202 proteins to the TBK1/IRF3 axis, we investigated whether c-di-GMP-induced signaling could regulate expression of IFI16 and p202 proteins. Here, we report that activation of c-di-GMP-induced signaling in human and murine cells increased steady-state levels of IFI16 and p202 proteins. The increase was c-di-GMP concentration- and time-dependent. Unexpectedly, treatment of cells with type I IFN decreased levels of the adaptor protein STING. Therefore, we investigated whether the IFI16 or p202 protein could regulate the expression of STING and activation of the TBK1/IRF3 axis. We found that constitutive knockdown of IFI16 or p202 expression in cells increased steady-state levels of STING. Additionally, the knockdown of IFI16 resulted in activation of the TBK1/IRF3 axis. Accordingly, increased levels of the IFI16 or p202 protein in cells decreased STING levels. Together, our observations identify a novel negative feedback loop between c-di-GMP-induced levels of IFI16 and p202 cytosolic DNA sensors and the adaptor protein STING.

  6. Increasing Induction-Level Teachers' Positive-to-Negative Communication Ratio and Use of Behavior-Specific Praise through E-Mailed Performance Feedback and Its Effect on Students' Task Engagement

    Science.gov (United States)

    Rathel, Jeanna M.; Drasgow, Erik; Brown, William H.; Marshall, Kathleen J.

    2014-01-01

    The purpose of this study was to examine the effects of e-mailed specific performance feedback that included progress monitoring graphs on induction-level teachers' ratios of positive-to-negative communication behaviors and their use of behavior-specific praise in classrooms for students with emotional and behavioral disorders, mild…

  7. Audio Feedback -- Better Feedback?

    Science.gov (United States)

    Voelkel, Susanne; Mello, Luciane V.

    2014-01-01

    National Student Survey (NSS) results show that many students are dissatisfied with the amount and quality of feedback they get for their work. This study reports on two case studies in which we tried to address these issues by introducing audio feedback to one undergraduate (UG) and one postgraduate (PG) class, respectively. In case study one…

  8. Introduction to Extra Dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Rizzo, Thomas G.; /SLAC

    2010-04-29

    Extra dimensions provide a very useful tool in addressing a number of the fundamental problems faced by the Standard Model. The following provides a very basic introduction to this very broad subject area as given at the VIII School of the Gravitational and Mathematical Physics Division of the Mexican Physical Society in December 2009. Some prospects for extra dimensional searches at the 7 TeV LHC with {approx}1 fb{sup -1} of integrated luminosity are provided.

  9. Identification of novel non-coding RNA-based negative feedback regulating the expression of the oncogenic transcription factor GLI1.

    Science.gov (United States)

    Villegas, Victoria E; Rahman, Mohammed Ferdous-Ur; Fernandez-Barrena, Maite G; Diao, Yumei; Liapi, Eleni; Sonkoly, Enikö; Ståhle, Mona; Pivarcsi, Andor; Annaratone, Laura; Sapino, Anna; Ramírez Clavijo, Sandra; Bürglin, Thomas R; Shimokawa, Takashi; Ramachandran, Saraswathi; Kapranov, Philipp; Fernandez-Zapico, Martin E; Zaphiropoulos, Peter G

    2014-07-01

    Non-coding RNAs are a complex class of nucleic acids, with growing evidence supporting regulatory roles in gene expression. Here we identify a non-coding RNA located head-to-head with the gene encoding the Glioma-associated oncogene 1 (GLI1), a transcriptional effector of multiple cancer-associated signaling pathways. The expression of this three-exon GLI1 antisense (GLI1AS) RNA in cancer cells was concordant with GLI1 levels. siRNAs knockdown of GLI1AS up-regulated GLI1 and increased cellular proliferation and tumor growth in a xenograft model system. Conversely, GLI1AS overexpression decreased the levels of GLI1, its target genes PTCH1 and PTCH2, and cellular proliferation. Additionally, we demonstrate that GLI1 knockdown reduced GLI1AS, while GLI1 overexpression increased GLI1AS, supporting the role of GLI1AS as a target gene of the GLI1 transcription factor. Activation of TGFβ and Hedgehog signaling, two known regulators of GLI1 expression, conferred a concordant up-regulation of GLI1 and GLI1AS in cancer cells. Finally, analysis of the mechanism underlying the interplay between GLI1 and GLI1AS indicates that the non-coding RNA elicits a local alteration of chromatin structure by increasing the silencing mark H3K27me3 and decreasing the recruitment of RNA polymerase II to this locus. Taken together, the data demonstrate the existence of a novel non-coding RNA-based negative feedback loop controlling GLI1 levels, thus expanding the repertoire of mechanisms regulating the expression of this oncogenic transcription factor.

  10. Growth factor TGF-β induces intestinal epithelial cell (IEC-6) differentiation: miR-146b as a regulatory component in the negative feedback loop.

    Science.gov (United States)

    Liao, Yalin; Zhang, Man; Lönnerdal, Bo

    2013-01-01

    TGF-β is a potent pleiotropic factor that promotes small intestinal cell differentiation. The role of microRNAs in the TGF-β induction of intestinal epithelial phenotype is largely unknown. We hypothesized that microRNAs are functionally involved in TGF-β-induced intestinal cell growth. In this study, TGF-β caused a morphological change of IEC-6 cells and stimulated expression of the epithelial cell markers alkaline phosphatase, villin, and aminopeptidase N. By global microRNA profiling during TGF-β-induced intestinal crypt cell (IEC-6) differentiation, we identified 19 differentially expressed microRNAs. We showed by real-time Q-PCR that miR-146b expression increased rapidly after TGF-β treatment; sequence analysis and in vitro assays revealed that miR-146b targets SIAH2, an E3 ubiquitin ligase, with decreased protein expression upon IEC-6 cell differentiation. Transfection of miR-146b inhibitor before TGF-β treatment blocked the down-regulation of SIAH2 in response to TGF-β. Moreover, SIAH2 over-expression during TGF-β treatment caused a significant decrease in Smad7 protein expression in IEC-6 cells. Furthermore, activation of the ERK1/2 pathway is active in the up-regulation of miR-146b by TGF-β. These findings suggest a novel mechanism whereby TGF-β signaling during IEC-6 cell differentiation may be modulated in part by microRNAs, and we propose a key role for miR-146b in the homeostasis of growth factor TGF-β signaling through a negative feedback regulation involving down-regulation of SIAH2 repressed Smad7 activities.

  11. Loss of the oncogenic phosphatase PRL-3 promotes a TNF-R1 feedback loop that mediates triple-negative breast cancer growth.

    Science.gov (United States)

    Gari, H H; DeGala, G D; Lucia, M S; Lambert, J R

    2016-08-15

    Stimulating tumor cell senescence and apoptosis are proven methods for therapeutically combating cancer. However, senescence and apoptosis are conventionally viewed as parallel, not sequential, processes. We have discovered that the metastasis-promoting phosphatase, PRL-3, is transcriptionally regulated by the NF-ĸB pathway in triple-negative breast cancer (TNBC) cells, and that PRL-3 knockdown elicits an autocrine tumor necrosis factor receptor 1 (TNF-R1) feedback loop that results in TNBC cell senescence followed by apoptosis. Knockdown of PRL-3 leads to rapid G1 cell cycle arrest and induction of a strong TNFα cytokine response that promotes a period of cellular senescence through TNF-R1-mediated activation of NF-ĸB. Senescent PRL-3 knockdown cells subsequently underwent apoptosis as a result of increased TNF-R1 signaling through the TNFα-associated extrinsic death pathway, shunting signaling away from the NF-ĸB cascade. These data suggest that TNF-R1 signaling dynamically re-programs after PRL-3 knockdown, from sustaining cell senescence through NF-ĸB to promoting apoptosis through TNF-R1 internalization and caspase-8 activation. The molecular mechanisms that determine the survival-death balance of TNF-R1 signaling are poorly understood, despite the fact that TNF-R1 has been extensively studied. Our results describe PRL-3 knockdown as a novel survival-death balance modifier of the TNF-R1 pathway, and show that senescent TNBC tumor cells can be sensitized to undergo apoptosis in a sequential manner.

  12. Spontaneous kisspeptin neuron firing in the adult mouse reveals marked sex and brain region differences but no support for a direct role in negative feedback.

    Science.gov (United States)

    de Croft, Simon; Piet, Richard; Mayer, Christian; Mai, Oliver; Boehm, Ulrich; Herbison, Allan E

    2012-11-01

    Kisspeptin-Gpr54 signaling is critical for the GnRH neuronal network controlling fertility. The present study reports on a kisspeptin (Kiss)-green fluorescent protein (GFP) mouse model enabling brain slice electrophysiological recordings to be made from Kiss neurons in the arcuate nucleus (ARN) and rostral periventricular region of the third ventricle (RP3V). Using dual immunofluorescence, approximately 90% of GFP cells in the RP3V of females, and ARN in both sexes, are shown to be authentic Kiss-synthesizing neurons in adult mice. Cell-attached recordings of ARN Kiss-GFP cells revealed a marked sex difference in their mean firing rates; 90% of Kiss-GFP cells in males exhibited slow irregular firing (0.17 ± 0.04 Hz) whereas neurons from diestrous (0.01 ± 0.01 Hz) and ovariectomized (0 Hz) mice were mostly or completely silent. In contrast, RP3V Kiss-GFP cells were all spontaneously active, exhibiting tonic, irregular, and bursting firing patterns. Mean firing rates were significantly (P neurons at the time of the proestrous GnRH surge revealed a significant decline in firing rate after the surge. Together, these observations demonstrate unexpected sex differences in the electrical activity of ARN Kiss neurons and markedly different patterns of firing by Kiss neurons in the ARN and RP3V. Although data supported a positive influence of gonadal steroids on RP3V Kiss neuron firing, no direct evidence was found to support the previously postulated role of ARN Kiss neurons in the estrogen-negative feedback mechanism.

  13. Feedback and Incentives

    DEFF Research Database (Denmark)

    Eriksson, Tor Viking; Poulsen, Anders; Villeval, Marie Claire

    2009-01-01

    This paper experimentally investigates the impact of different pay schemes and relative performance feedback policies on employee effort. We explore three feedback rules: no feedback on relative performance, feedback given halfway through the production period, and continuously updated feedback. We...... use two pay schemes, a piece rate and a tournament. We find that overall feedback does not improve performance. In contrast to the piece-rate pay scheme there is some evidence of positive peer effects in tournaments since the underdogs almost never quit the competition even when lagging significantly...... behind, and front runners do not slack off. But in both pay schemes relative performance feedback reduces the quality of the low performers' work; we refer to this as a "negative quality peer effect"....

  14. Cosmology With Extra Dimensions

    CERN Document Server

    Martín, J

    2005-01-01

    We review several properties of models that include extra dimensions, focusing on aspects related to cosmology and particle physics phenomenology. The properties of effective four dimensional inflationary geometry are studied in two distinct frameworks: (i) in Kaluza- Klein (KK) compactifications and (ii) in braneworld scenarios. From numerical simulations we find that inflationary braneworlds are unstable if the scale of inflation is too large in comparison with the stabilization scale of the interbrane distance. The analysis of perturbations confirms the existence of a tachyon associated with the volume modulus of the extra dimensions both in braneworlds and KK compactifications. With the numerical program BRANECODE non- perturbative properties of braneworlds are studied. We fully understand the non-perturbative consequences of this instability. Generic attractors are (i) an increase of the interbrane distance and the formation of a naked singularity, (ii) the brane colli...

  15. SCONUL Research Extra

    OpenAIRE

    John Hall

    2006-01-01

    SCONUL Research Extra is a cooperative access and borrowing scheme for staff and research students in UK and Irish higher education institutions. Under the terms of the scheme, eligible researchers may visit any participating library and register as an external borrower. The scheme is run on behalf of SCONUL, the Society of College, National and University Libraries which represents the directors of the library and information services in all the universities of the United Kingdom and Ireland...

  16. Supervisor Feedback.

    Science.gov (United States)

    Hayman, Marilyn J.

    1981-01-01

    Investigated the effectiveness of supervisor feedback in contributing to learning counseling skills. Counselor trainees (N=64) were assigned to supervisor feedback, no supervisor feedback, or control groups for three training sessions. Results indicated counseling skills were learned best by students with no supervisor feedback but self and peer…

  17. Biased Reasoning : Adaptive Responses to Health Risk Feedback

    OpenAIRE

    Renner, Britta

    2004-01-01

    The present study examined reactions toward repeated self relevant feedback. Participants in a community health screening received feedback about their cholesterol level on two separate occasions. Reactions to the first feedback were examined with regard to feedback valence and expectedness. The findings showed that negative feedback was devalued, but only when it was unexpected. Feedback consistency war incorporated into analyses of the second feedback. Again, results showed that negative fe...

  18. Phenomenology of Extra Dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Hewett, J.L.; /SLAC

    2006-11-07

    If the structure of spacetime is different than that readily observed, gravitational physics, particle physics and cosmology are all immediately affected. The physics of extra dimensions offers new insights and solutions to fundamental questions arising in these fields. Novel ideas and frameworks are continuously born and evolved. They make use of string theoretical features and tools and they may reveal if and how the 11-dimensional string theory is relevant to our four-dimensional world. We have outlined some of the experimental observations in particle and gravitational physics as well as astrophysical and cosmological considerations that can constrain or confirm these scenarios. These developing ideas and the wide interdisciplinary experimental program that is charted out to investigate them mark a renewed effort to describe the dynamics behind spacetime. We look forward to the discovery of a higher dimensional spacetime.

  19. Qubits from extra dimensions

    CERN Document Server

    Lévay, Péter

    2011-01-01

    We link the recently discovered black hole-qubit correspondence to the structure of extra dimensions. In particular we show that for toroidal compactifications of type IIB string theory simple qubit systems arise naturally from the geometrical data of the tori parametrized by the moduli. We also generalize the recently suggested idea of the attractor mechanism as a distillation procedure of GHZ-like entangled states on the event horizon, to moduli stabilization for flux attractors in F-theory compactifications on elliptically fibered Calabi-Yau four-folds. Finally using a simple example we show that the natural arena for qubits to show up is an embedded one within the realm of fermionic entanglement of quantum systems with indistinguishable constituents.

  20. SCONUL Research Extra

    Directory of Open Access Journals (Sweden)

    John Hall

    2006-04-01

    Full Text Available SCONUL Research Extra is a cooperative access and borrowing scheme for staff and research students in UK and Irish higher education institutions. Under the terms of the scheme, eligible researchers may visit any participating library and register as an external borrower. The scheme is run on behalf of SCONUL, the Society of College, National and University Libraries which represents the directors of the library and information services in all the universities of the United Kingdom and Ireland, and in most other UK institutions of higher education, and the directors of the national libraries; it is for all institutions in membership of SCONUL able to lend library materials and, with 158 institutions signed up, it is now the largest reciprocal borrowing scheme in the UK and Ireland, serving almost the entire membership of SCONUL.

  1. Simulation Analysis of Negative Feedback Mplifying Circuit Based on Multisim8%基于multisim8的负反馈放大电路的仿真分析

    Institute of Scientific and Technical Information of China (English)

    孙剑芬

    2014-01-01

    EDA simulation software for electronic circuit teaching were added to the experiments in order to meet the theory course. Through the use of Multisim8 on virtual simulation experiment of negative feedback amplifying circuit, the influence of AC amplification circuit performance intuitively were researched due to the introduction of negative feedback. The result of sim-ulation is consistent with the conclusion of theoretical analysis. The practice has proved that the feasibility of application of multi-sim8 in the electronic circuit experiment teaching, thereby has great significance to improve students' practical ability.%配合理论课程在实验中增加了EDA仿真软件用于电子电路辅助教学,通过运用multisim8对负反馈放大电路进行虚拟仿真实验,研究了引入负反馈对交流放大电路性能的影响。仿真实验结果与理论分析结果相一致。实践证明在电子电路实验教学中应用multisim8的可行性,对高校学生实际操作能力的提高有重大的意义。

  2. The negative feedback molecular mechanism which regulates excitation level in the plant photosynthetic complex LHCII: towards identification of the energy dissipative state.

    Science.gov (United States)

    Zubik, Monika; Luchowski, Rafal; Puzio, Michal; Janik, Ewa; Bednarska, Joanna; Grudzinski, Wojciech; Gruszecki, Wieslaw I

    2013-03-01

    Overexcitation of the photosynthetic apparatus is potentially dangerous because it can cause oxidative damage. Photoprotection realized via the feedback de-excitation in the pigment-protein light-harvesting complex LHCII, embedded in the chloroplast lipid environment, was studied with use of the steady-state and time-resolved fluorescence spectroscopy techniques. Illumination of LHCII results in the pronounced singlet excitation quenching, demonstrated by decreased quantum yield of the chlorophyll a fluorescence and shortening of the fluorescence lifetimes. Analysis of the 77K chlorophyll a fluorescence emission spectra reveals that the light-driven excitation quenching in LHCII is associated with the intensity increase of the spectral band in the region of 700nm, relative to the principal band at 680nm. The average chlorophyll a fluorescence lifetime at 700nm changes drastically upon temperature decrease: from 1.04ns at 300K to 3.63ns at 77K. The results of the experiments lead us to conclude that: (i) the 700nm band is associated with the inter-trimer interactions which result in the formation of the chlorophyll low-energy states acting as energy traps and non-radiative dissipation centers; (ii) the Arrhenius analysis, supported by the results of the FTIR measurements, suggests that the photo-reaction can be associated with breaking of hydrogen bonds. Possible involvement of photo-isomerization of neoxanthin, reported previously (Biochim. Biophys. Acta 1807 (2011) 1237-1243) in generation of the low-energy traps in LHCII is discussed.

  3. Extra Low ENergy Antiproton

    CERN Multimedia

    To produce dense antiproton beams at very low energies (110 keV), it has been proposed to install a small decelerator ring between the existing AD ring and the experimental area. Phase-space blowup during deceleration is compensated by electron cooling such that the final emittances are comparable to the 5MeV beam presently delivered by the AD. An immediate consequence is a significant increase in the number of trapped antiprotons at the experiments as outlined in the proposal CERN/SPSC-2009-026; SPCS-P-338. This report describes the machine parameters and layout of the proposal ELENA (Extra Low ENergy Antiproton)ring also gives an approximate estimate of cost and manpower needs. Since the initial estimate, published in 2007 (CERN-AB-2007-079), the ELENA design has evolved considerably. This is due to a new location in the AD hall to acommodate for the possibility of another experimental zone, as suggested by the SPCS, and also due to improvements in the ring optics and layout. The cost estimate that is prese...

  4. Insulin Activates RSK (p90 Ribosomal S6 Kinase) to Trigger a New Negative Feedback Loop That Regulates Insulin Signaling for Glucose Metabolism*

    Science.gov (United States)

    Smadja-Lamère, Nicolas; Shum, Michael; Déléris, Paul; Roux, Philippe P.; Abe, Jun-Ichi; Marette, André

    2013-01-01

    We previously demonstrated that the mTORC1/S6K1 pathway is activated by insulin and nutrient overload (e.g. amino acids (AA)), which leads to the inhibition of the PI3K/Akt pathway via the inhibitory serine phosphorylation of IRS-1, notably on serine 1101 (Ser-1101). However, even in the absence of AA, insulin can still promote IRS-1 Ser-1101 phosphorylation by other kinases that remain to be fully characterized. Here, we describe a new negative regulator of IRS-1, the p90 ribosomal S6 kinase (RSK). Computational analyses revealed that Ser-1101 within IRS-1 falls into the consensus motif of RSK. Moreover, recombinant RSK phosphorylated IRS-1 C-terminal fragment on Ser-1101, which was prevented by mutations of this site or when a kinase-inactive mutant of RSK was used. Using antibodies directed toward the phosphorylation sites located in the activation segment of RSK (Ser-221 or Ser-380), we found that insulin activates RSK in L6 myocytes in the absence of AA overload. Inhibition of RSK using either the pharmacological inhibitor BI-D1870 or after adenoviral expression of a dominant negative RSK1 mutant (RSK1-DN) showed that RSK selectively phosphorylates IRS-1 on Ser-1101. Accordingly, expression of the RSK1-DN mutant in L6 myocytes and FAO hepatic cells improved insulin action on glucose uptake and glucose production, respectively. Furthermore, RSK1 inhibition prevented insulin resistance in L6 myocytes chronically exposed to high glucose and high insulin. These results show that RSK is a novel regulator of insulin signaling and glucose metabolism and a potential mediator of insulin resistance, notably through the negative phosphorylation of IRS-1 on Ser-1101. PMID:24036112

  5. Model Predicts That MKP1 and TAB1 Regulate p38α Nuclear Pulse and Its Basal Activity through Positive and Negative Feedback Loops in Response to IL-1.

    Science.gov (United States)

    Singh, Raghvendra

    2016-01-01

    Interleukin-1 mediates inflammation and stress response through nuclear activity of p38α. Although IL-1 receptor is not degraded, p38α activation is transient. IL-1 also causes cell migration and EMT by modulating cell-cell junctions. Although molecules involved in p38 activation are known, mechanism of the transient nuclear response and its basal activity remains unknown. By mathematical modeling of IL1/p38 signaling network, we show that IL-1 induces robust p38α activation both in the nucleus and in the cytoplasm/membrane. While nuclear response consists of an acute phase, membrane response resembles a step change. Following stimulation, p38α activity returns to a basal level in absence of receptor degradation. While nuclear pulse is controlled by MKP1 through a negative feedback to pp38, its basal activity is controlled by both TAB1 and MKP1 through a positive feedback loop. Our model provides insight into the mechanism of p38α activation, reason for its transient nuclear response, and explanation of the basal activity of MKK3/6 and p38α, which has been experimentally observed by other groups.

  6. Formativ Feedback

    DEFF Research Database (Denmark)

    Hyldahl, Kirsten Kofod

    Denne bog undersøger, hvordan lærere kan anvende feedback til at forbedre undervisningen i klasselokalet. I denne sammenhæng har John Hattie, professor ved Melbourne Universitet, udviklet en model for feedback, hvilken er baseret på synteser af meta-analyser. I 2009 udgav han bogen "Visible...

  7. Supersymmetry breaking with extra dimensions

    Indian Academy of Sciences (India)

    Fabio Zwirner

    2004-02-01

    This talk reviews some aspects of supersymmetry breaking in the presence of extra dimensions. The first part is a general introduction, recalling the motivations for supersymmetry and extra dimensions, as well as some unsolved problems of four-dimensional models of supersymmetry breaking. The central part is a more focused introduction to a mechanism for (super)symmetry breaking, proposed first by Scherk and Schwarz, where extra dimensions play a crucial role. The last part is devoted to the description of some recent results and of some open problems.

  8. M/M/1/N Feedback Queue with Negative Customers and Working Vacations%带有负顾客且具有反馈的M/M/1/N工作休假排队

    Institute of Scientific and Technical Information of China (English)

    顾庆凤; 朱翼隽

    2011-01-01

    研究带反馈的且具有正、负两类顾客的M/M/1/N工作休假排队模型.工作休假策略为空竭服务多重工作休假.负顾客一对一抵消队首正在接受服务的正顾客(若有),若系统中无正顾客时,到达的负顾客自动消失,负顾客不接受服务.完成服务的正顾客以概率p(0<p≤1)离开系统,以概率1-p反馈到队尾寻求再次服务.利用马尔科夫过程理论和矩阵几何解方法求出了稳态概率的矩阵解,并得到了系统的平均队长、平均等待队长以及顾客的消失概率等性能指标.%The paper deals with an M/M/1/N feedback queue with working vacations in which customers are either "positive" or "negative" . The working vacation policy is exhaustive service and multiple working vacations. Negative customers remove positive customers only one by one at the head (if present). When a negative customer arrives, if the system is empty, it will disappear. Negative customers need no services. Just after completion of his service, a positive customer may leave the system with probability p(0 < p ≤ 1), or feedback with probability 1 - p. The matrix form solution of the steady-state probability is derived by the Markov process method and the matrix-geometric solution method. Some performance measures of the system such as the expected number of the customers in the system or in the queue and the loss probability of customer8 are also presented.

  9. Inflation from periodic extra dimensions

    CERN Document Server

    Higaki, Tetsutaro

    2016-01-01

    We discuss a realization of a small field inflation based on string inspired supergravities. In theories accompanying extra dimensions, compactification of them with small radii is required for realistic situations. Since the extra dimension can have a periodicity, there will appear (quasi-)periodic functions under transformations of moduli of the extra dimensions in low energy scales. Such a periodic property can lead to a UV completion of so-called multi-natural inflation model where inflaton potential consists of a sum of multiple sinusoidal functions with a decay constant smaller than the Planck scale. As an illustration, we construct a SUSY breaking model, and then show that such an inflaton potential can be generated by a sum of world sheet instantons in intersecting brane models on extra dimensions containing $T^2/{\\mathbb Z}_2$ orbifold. We show also predictions of cosmic observables by numerical analyzes.

  10. miR-30 family microRNAs regulate myogenic differentiation and provide negative feedback on the microRNA pathway.

    Science.gov (United States)

    Guess, Martin G; Barthel, Kristen K B; Harrison, Brooke C; Leinwand, Leslie A

    2015-01-01

    microRNAs (miRNAs) are short non-coding RNAs that can mediate changes in gene expression and are required for the formation of skeletal muscle (myogenesis). With the goal of identifying novel miRNA biomarkers of muscle disease, we profiled miRNA expression using miRNA-seq in the gastrocnemius muscles of dystrophic mdx4cv mice. After identifying a down-regulation of the miR-30 family (miR-30a-5p, -30b, -30c, -30d and -30e) when compared to C57Bl/6 (WT) mice, we found that overexpression of miR-30 family miRNAs promotes differentiation, while inhibition restricts differentiation of myoblasts in vitro. Additionally, miR-30 family miRNAs are coordinately down-regulated during in vivo models of muscle injury (barium chloride injection) and muscle disuse atrophy (hindlimb suspension). Using bioinformatics tools and in vitro studies, we identified and validated Smarcd2, Snai2 and Tnrc6a as miR-30 family targets. Interestingly, we show that by targeting Tnrc6a, miR-30 family miRNAs negatively regulate the miRNA pathway and modulate both the activity of muscle-specific miR-206 and the levels of protein synthesis. These findings indicate that the miR-30 family may be an interesting biomarker of perturbed muscle homeostasis and muscle disease.

  11. Phenomenology of universal extra dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Kyoungchul; Matchev, Konstantin T.; /Florida U.

    2006-10-01

    In this proceeding, the phenomenology of Universal Extra Dimensions (UED), in which all the Standard Model fields propagate, is explored. We focus on models with one universal extra dimension, compactified on an S{sub 1}/Z{sub 2} orbifold. We revisit calculations of Kaluza-Klein (KK) dark matter without an assumption of the KK mass degeneracy including all possible coannihilations. We then contrast the experimental signatures of low energy supersymmetry and UED.

  12. Feedback and Incentives

    DEFF Research Database (Denmark)

    Eriksson, Tor Viking; Poulsen, Anders; Villeval, Marie Claire

    2009-01-01

    This paper experimentally investigates the impact of different pay schemes and relative performance feedback policies on employee effort. We explore three feedback rules: no feedback on relative performance, feedback given halfway through the production period, and continuously updated feedback. ...

  13. Extra Stimulation in Intermediate Grade Reading.

    Science.gov (United States)

    Mason, George E.

    Three types of extra stimulation in reading are discussed: extra teacher time devoted to teaching reading, extra student time devoted to practice in reading, and extra motivation and reinforcement leading to greater amounts of student reading outside the school. Problems are created (1) when teaching time spent on reading is increased in the…

  14. Collider searches for extra dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Landsberg, Greg; /Brown U.

    2004-12-01

    Searches for extra spatial dimensions remain among the most popular new directions in our quest for physics beyond the Standard Model. High-energy collider experiments of the current decade should be able to find an ultimate answer to the question of their existence in a variety of models. Until the start of the LHC in a few years, the Tevatron will remain the key player in this quest. In this paper, we review the most recent results from the Tevatron on searches for large, TeV{sup -1}-size, and Randall-Sundrum extra spatial dimensions, which have reached a new level of sensitivity and currently probe the parameter space beyond the existing constraints. While no evidence for the existence of extra dimensions has been found so far, an exciting discovery might be just steps away.

  15. Flavor Models In Extra Dimensions

    CERN Document Server

    Valadez, J

    2005-01-01

    This thesis consists of implementing flavor symmetries in the context of extra dimensions. To the particle content of the Standard Model we add an additional scalar (flavon) field and we assume that all the fields propagate in the extra-dimensional space-time. When the flavon field acquires a vacuum expectation value the flavor symmetry is effectively broken thus generating the Yukawa textures associated with the particles. An specific model in 5D that reproduces all fermion masses, mixing angles and ratios is presented.

  16. Signatures of Large Extra Dimensions

    CERN Document Server

    Hossenfelder, S; Stöcker, H

    2004-01-01

    String theory suggests modifications of our spacetime such as extra dimensions and the existence of a mininal length scale. In models with addidional dimensions, the Planck scale can be lowered to values accessible by future colliders. Effective theories which extend beyond the standart-model by including extra dimensions and a minimal length allow computation of observables and can be used to make testable predictions. Expected effects that arise within these models are the production of gravitons and black holes. Furthermore, the Planck-length is a lower bound to the possible resolution of spacetime which might be reached soon.

  17. The Positive Impact of Negative Feedback

    Science.gov (United States)

    2011-03-01

    Psychology, 79(4), 506–517 (1994). Northouse , Peter G. Leadership Theory and Practice . Thousand Oaks, CA: Sage Publications, 2007. Nowack...model (FRLM), depicted in Figure 2, is one of the most widely studied leadership theories since the mid-1980s ( Northouse , 2007). This approach is... leadership theory for accurate measures of leadership behavior. Accordingly, this effort will employ a leadership behavior survey based on Bass’ (1985

  18. Cosmology With Dynamical Extra Dimensions

    CERN Document Server

    Erickson, J K

    2005-01-01

    Nearly every attempt to unify the fundamental forces incorporates the idea of compact extra dimensions. The notion was introduced by Kaluza and Klein in the 1920s and is an essential part of contemporary string theory and M-theory. In most treatments the extra dimensions are static. We consider the consequences of extra dimensions with time-varying radii. The radii are modeled by light scalar fields. These may have unusual properties which produce observable effects, such as non-canonical kinetic energies, couplings to matter and radiation, and non- minimal coupling to gravity. Extra dimensions may be responsible for dark energy in the late universe. The simplest model of dark energy is characterized by its equation of state. We show that constraints placed on realistic models by the universality of free fall, variation of fundamental constants and metric tests of gravity are often stricter than bounds on the equation of state. Testing the equivalence principle maybe an effective way of distinguishing some qu...

  19. Wormholes leading to extra dimensions

    CERN Document Server

    Bronnikov, K A

    2016-01-01

    In 6D general relativity with a scalar field as a source of gravity, a new type of static wormhole solutions is presented: such wormholes connect our universe with a small 2D extra subspace with a universe where this extra subspace is large, and the whole space-time is effectively 6-dimensional. We consider manifolds with the structure M0 x M1 x M2 , where M0 is 2D Lorentzian space-time while each of M1 an M2 can be a 2-sphere or a 2-torus. After selecting possible asymptotic behaviors of the metric functions compatible with the field equations, we give two explicit examples of wormhole solutions with spherical symmetry in our space-time and toroidal extra dimensions. In one example, with a massless scalar field (it is a special case of a well-known more general solution), the extra dimensions have a large constant size at the "far end"; the other example contains a nonzero potential $V(\\phi)$ which provides a 6D anti-de Sitter asymptotic, where all spatial dimensions are infinite.

  20. Cosmology with dynamical extra dimensions

    Science.gov (United States)

    Erickson, Joel K.

    Nearly every attempt to unify the fundamental forces incorporates the idea of compact extra dimensions. The notion was introduced by Kaluza and Klein in the 1920s and is an essential part of contemporary string theory and M-theory. In most treatments the extra dimensions are static. We consider the consequences of extra dimensions with time-varying radii. The radii are modeled by light scalar fields. These may have unusual properties which produce observable effects, such as non-canonical kinetic energies, couplings to matter and radiation, and non-minimal coupling to gravity. Extra dimensions may be responsible for dark energy in the late universe. The simplest model of dark energy is characterized by its equation of state. We show that constraints placed on realistic models by the universality of free fall, variation of fundamental constants and metric tests of gravity are often stricter than bounds on the equation of state. Testing the equivalence principle maybe an effective way of distinguishing some quintessence models from a cosmological constant. In certain dark energy models the speed of sound is much less than the speed of light. We calculate how this affects the cosmic microwave background and show that the speed of sound may be measurable, provided dark energy is sufficiently dense at decoupling. This is another possible signature of quintessence. Dynamical extra dimensions may have consequences for the early universe. In the cyclic model, the universe is described in terms of a series of contractions and expansions of an extra dimension. The big bang is preceded by a big crunch and quantum fluctuations of the scalar field produce structure in universe. We consider how the fluctuations evolve and build over many cycles and show that there are no observable instabilities or adverse effects. In the cyclic model extra dimensions act as both dark energy and as an agent to cause contraction and a big crunch. Previous theorems suggested that contraction

  1. Galaxy-scale AGN Feedback - Theory

    CERN Document Server

    Wagner, A Y; Umemura, M; Sutherland, R S; Silk, J

    2015-01-01

    Powerful relativistic jets in radio galaxies are capable of driving strong outflows but also inducing star-formation by pressure-triggering collapse of dense clouds. We review theoretical work on negative and positive active galactic nuclei feedback, discussing insights gained from recent hydrodynamical simulations of jet-driven feedback on galaxy scales that are applicable to compact radio sources. The simulations show that the efficiency of feedback and the relative importance of negative and positive feedback depends strongly on interstellar medium properties, especially the column depth and spatial distribution of clouds. Negative feedback is most effective if clouds are distributed spherically and individual clouds have small column depths, while positive feedback is most effective if clouds are predominantly in a disc-like configuration.

  2. Signatures of AGN feedback

    Science.gov (United States)

    Wylezalek, Dominika; Zakamska, Nadia L.; MaNGA-GMOS Team

    2017-01-01

    Feedback from actively accreting SMBHs (Active Galactic Nuclei, AGN) is now widely considered to be the main driver in regulating the growth of massive galaxies. Observational proof for this scenario has, however, been hard to come by. Many attempts at finding a conclusive observational proof that AGN may be able to quench star formation and regulate the host galaxies' growth have shown that this problem is highly complex.I will present results from several projects that focus on understanding the power, reach and impact of feedback processes exerted by AGN. I will describe recent efforts in our group of relating feedback signatures to the specific star formation rate in their host galaxies, where our results are consistent with the AGN having a `negative' impact through feedback on the galaxies' star formation history (Wylezalek+2016a,b). Furthermore, I will show that powerful AGN-driven winds can be easily hidden and not be apparent in the integrated spectrum of the galaxy. This implies that large IFU surveys, such as the SDSS-IV MaNGA survey, might uncover many previously unknown AGN and outflows that are potentially very relevant for understanding the role of AGN in galaxy evolution (Wylezalek+2016c)!

  3. On a time-dependent extra spatial dimension

    CERN Document Server

    Kuhfittig, P K F

    2006-01-01

    In the usual brane-world scenario matter fields are confined to the four-dimensional spacetime, called a 3-brane, embedded in a higher-dimensional space, usually referred to as the bulk spacetime. In this paper we assume that the 3-brane a de Sitter space; there is only one extra spatial dimension, assumed to be time dependent. By using the form of the brane-world energy-momentum tensor suggested by Shiromizu et al. in the five-dimensional Einstein equations, it is shown that whenever the bulk cosmological constant \\Lambda is negative, the extra spatial dimension rapidly shrinks during the inflation of the brane. When \\Lambda>0, on the other hand, the extra spatial dimension either completely follows the cosmological expansion of the brane or completely ignores it. This behavior resembles the all-or-nothing behavior of ordinary systems in an expanding universe, as recently demonstrated by R.H. Price.

  4. A novel double-negative feedback loop between miR-489 and the HER2-SHP2-MAPK signaling axis regulates breast cancer cell proliferation and tumor growth.

    Science.gov (United States)

    Patel, Yogin; Shah, Nirav; Lee, Ji Shin; Markoutsa, Eleni; Jie, Chunfa; Liu, Shou; Botbyl, Rachel; Reisman, David; Xu, Peisheng; Chen, Hexin

    2016-04-05

    Human epidermal growth factor receptor 2 (HER2 or ErBb2) is a receptor tyrosine kinase overexpressed in 20-30% of breast cancers and associated with poor prognosis and outcome. Dysregulation of several microRNAs (miRNAs) plays a key role in breast cancer progression and metastasis. In this study, we screened and identified miRNAs dysregualted in HER2-positive breast cancer cells. Our molecular study demonstrated that miR-489 was specifically downregulated by the HER2-downstream signaling, especially through the MAPK pathway. Restoration or overexpression of miR-489 in HER2-positive breast cancer cells significantly inhibited cell growth in vitro and decreased the tumorigenecity and tumor growth in xenograft mice. Mechanistically, we found that overexpression of miR-489 led to the decreased levels of HER2 and SHP2 and thus attenuated HER2-downstream signaling. Furthermore, we for the first time demonstrated that HER2 is a direct target of miR-489 and therefore HER2-SHP2-MAPK and miR-489 signaling pathways form a mutually inhibitory loop. Using quantitative real-time PCR analysis and Fluorescent in situ hybridization technique (FISH), we found that miR-489 was expressed at significantly lower level in tumor tissues compared to the adjacent normal tissues. Downregulation of miR-489 in breast cancers was associated with aggressive tumor phenotypes. Overall, our results define a double-negative feedback loop involving miR-489 and the HER2-SHP2-MAPK signaling axis that can regulate breast cancer cell proliferation and tumor progression and might have therapeutic relevance for HER2-positive breast cancer.

  5. Search for extra space dimensions with ATLAS

    Indian Academy of Sciences (India)

    Ambreesh Gupta; ATLAS Collaboration

    2004-03-01

    If extra spatial dimensions were to exist, they could provide a solution to the hierarchy problem. The studies done by the ATLAS Collaboration on the sensitivity of the detector to various extra dimension models are reported in this document.

  6. Negative feedback action of adipocytokine and the pathogenesis of obesity and type 2 diabetes%脂肪细胞因子的负反馈作用与肥胖和2型糖尿病的形成

    Institute of Scientific and Technical Information of China (English)

    李江华; 肖全红; 汤长发

    2006-01-01

    BACKGROUND: To explore the effect of negative feedback mechanism of adipose tissue in the pathogenesis of obesity and type 2 diabetes through analyzing the function of the adipocytokines in regulating energy metabolism and fat accumulation.DATA SOURCES: We searched in the PubMed database of National Library of Medicine in USA for the articles on negative feedback action of adipocytokine, obesity and type 2 diabetes published from Jan 1962 to Nov 2005, using the key words of "adipocytokines, obesity, tumor necrosis factor-α, interleukin-6, leptin, adiponectin, resistin and PGAR" and limited the language to English.STUDY SELECTION: The articles of original researches and associated with energy metabolism and fat accumulation were included. The articles of repetitive researches, reviews and little associated with energy metabolism and fat accumulation were excluded.DATA EXTRACTION: A total of 158 articles were collected, of which 35 were closely correlated with this paper, and the 123 excluded articles were all repetitive studies, reviews and little correlated with this paper.DATA SYNTHESIS: Researches show that the fat tissue is able to secrete adipocytokines to regulate the fat mass, While the mass of body fat increases, the adipocytokines will inhibit lipogenesis and promote lipolysis.Adipocytokines can either resist the action of insulin or suppress the secretion of insulin. Thus lead to lipogenesis inhibition, lipolysis increasing and suppressing the utilization of blood glucose.CONCLUSION: When man develops obesity going up to certain degree,the negative feedback action of adipocytokines may lead to insulin resistance and type 2 diabetes.%背景:通过分析脂肪细胞因子对机体的能量代谢及脂肪积累的调节作用,探讨脂肪组织的负反馈机制在肥胖、2型糖尿病形成中的作用.资料来源:应用计算机检索美国国立医学图书馆PubMed数据库1962-01/2005-11有关脂肪细胞因子的负反馈作用,肥胖和2型糖尿

  7. Social feedback processing in borderline personality disorder.

    Science.gov (United States)

    Korn, C W; La Rosée, L; Heekeren, H R; Roepke, S

    2016-02-01

    Patients with borderline personality disorder (BPD) show negative and unstable self- and other-evaluations compared to healthy individuals. It is unclear, however, how they process self- and other-relevant social feedback. We have previously demonstrated a positive updating bias in healthy individuals: When receiving social feedback on character traits, healthy individuals integrate desirable more than undesirable feedback. Here, our aim was to test whether BPD patients exhibit a more negative pattern of social feedback processing. We employed a character trait task in which BPD patients interacted with four healthy participants in a real-life social interaction. Afterwards, all participants rated themselves and one other participant on 80 character traits before and after receiving feedback from their interaction partners. We compared how participants updated their ratings after receiving desirable and undesirable feedback. Our analyses included 22 BPD patients and 81 healthy controls. Healthy controls showed a positivity bias for self- and other-relevant feedback as previously demonstrated. Importantly, this pattern was altered in BPD patients: They integrated undesirable feedback for themselves to a greater degree than healthy controls did. Other-relevant feedback processing was unaltered in BPD patients. Our study demonstrates an alteration in self-relevant feedback processing in BPD patients that might contribute to unstable and negative self-evaluations.

  8. Relaxation oscillations and hierarchy of feedbacks in MAPK signaling

    Science.gov (United States)

    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.

  9. Light Stops from extra dimensions

    CERN Document Server

    Garcia-Pepin, Mateo

    2016-01-01

    In supersymmetric models the mass of the stops can be considered as the naturalness measure of the theory. Roughly, the lighter the stops are, the more natural the theory is. Both, the absence of supersymmetric signals at experiment and the measurement of the Higgs mass, put scenarios with light stops under increasing tension. I will present a supersymmetry breaking mechanism of the Scherk-Schwarz type that, by introducing extra $SU(2)_L$ triplets in the Higgs sector, is able to generate the correct Higgs mass while keeping stops light.

  10. PID control with robust disturbance feedback control

    DEFF Research Database (Denmark)

    Kawai, Fukiko; Vinther, Kasper; Andersen, Palle

    2015-01-01

    Disturbance Feedback Control (DFC) is a technique, originally proposed by Fuji Electric, for augmenting existing control systems with an extra feedback for attenuation of disturbances and model errors. In this work, we analyze the robustness and performance of a PID-based control system with DFC...... and performance (if such gains exist). Finally, two different simulation case studies are evaluated and compared. Our numerical studies indicate that better performance can be achieved with the proposed method compared with a conservatively tuned PID controller and comparable performance can be achieved when...... compared with an H-infinity controller....

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

    Science.gov (United States)

    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.

  12. PC-1解除S6K对AKT信号通路的负反馈抑制%PC-1 Release the Negative Feedback Regulation of p70S6K on the PI3K/AKT Pathway

    Institute of Scientific and Technical Information of China (English)

    张晓清; 王健; 王洪涛; 李山虎; 王芃; 黄芳; 洪鎏; 邓楚中; 周建光

    2014-01-01

    Objective: To construct a prostate cancer LNCaP cell line stably overexpressing PC-1 and a C4-2 cell line in which PC-1 expression is stably knocked down and to explore how PC-1 active AKT pathway. Meth-ods: PC-1 and siRNA primers targeting PC-1 were separately cloned into the control vector pCDH-EF1-MCS-T2A-Puro and pSIH1-H1-Puro. Prostate cancer cells LNCaP and C4-2 cells were infected with lentivirus and the expression of PC-1 was identified by Western blot. Meanwhile, Western blot was performed to detect the phosphor-ylation level of PI3K/AKT/mTOR pathway associated proteins such as S6K, AKT. Results: PC-1 overexpression can decrease the S6K phosphorylation level, while increase AKT phophorylation level. Conclusion: PC-1 may ac-tive AKT kinase in some way through releasing negative feedback regulation of S6K on the PI3K/AKT pathway.%目的:通过建立过表达PC-1的前列腺癌LNCaP细胞系及敲低PC-1表达的C4-2细胞系,探究PC-1激活AKT信号通路的分子机制。方法:将PC-1基因及针对PC-1的siRNA序列,分别克隆至慢病毒表达载体pCDH-EF1-Myc-MCS-T2A-Puro及干扰载体pSIH1-H1-Puro,包装成慢病毒后分别感染前列腺癌LNCaP及C4-2细胞,通过Western印迹鉴定PC-1过表达及敲低效果,并检测PI3K/AKT/mTOR信号通路相关蛋白S6K、AKT的磷酸化水平。结果:PC-1过表达时,S6K磷酸化水平下降,而AKT的磷酸化水平上升。结论:PC-1可以通过抑制S6K激酶活性,解除其对AKT的负反馈抑制作用,从而激活AKT激酶的活性。

  13. Higgs Bosons in Extra Dimensions

    CERN Document Server

    Quiros, Mariano

    2015-01-01

    In this paper, motivated by the recent discovery of a Higgs-like boson at the LHC with a mass m_H\\simeq 126 GeV, we review different models where the hierarchy problem is solved by means of a warped extra dimension. In the Randall-Sundrum model electroweak observables provide very strong bounds on the mass of KK modes which motivates extensions to overcome this problem. Two extensions are briefly discussed. One particular extension is based on the deformation of the metric such that it strongly departs from the AdS_5 structure in the IR region while it goes asymptotically to AdS_5 in the UV brane. This model has the IR brane close to a naked metric singularity (which is outside the physical interval) characteristic of soft-walls constructions. The proximity of the singularity provides a strong wave-function renormalization for the Higgs field which suppresses the T and S parameters. The second class of considered extensions are based on the introduction of an extra gauge group in the bulk such that the custod...

  14. Feedback, Incentives and Peer Effects

    DEFF Research Database (Denmark)

    Eriksson, Tor Viking; Poulsen, Anders; Villeval, Marie Claire

    effects in the piece-rate pay scheme. In both pay schemes, interim feedback generates negative quality peer effects on the less able performers. We find however evidence of positive peer effects in the tournament scheme since the underdogs almost never quit the competition even when lagging significantly...

  15. A Framework for Teacher Verbal Feedback: Lessons from Chinese Mathematics Classrooms

    Science.gov (United States)

    Li, Na; Cao, Yiming; Mok, Ida Ah Chee

    2016-01-01

    Teacher verbal feedback plays an important role in classroom teaching. Different types of feedback can have different effect on students' learning. Praise and blame feedback could provide positive and negative results for learners. The gap was left in considering teachers' attitudes in providing verbal feedback to students. Due to feedback which…

  16. Flavor Symmetries in Extra Dimensions

    CERN Document Server

    Aranda, A; Aranda, Alfredo

    2002-01-01

    We present a model of flavor based on a discrete local symmetry that reproduces all fermion masses and mixing angles both in the quark and lepton sectors. The particle content of the model is that of the standard model plus an additional flavon field. All the fields propagate in a fifth universal extra dimension and the flavor scale is associated with the cutoff of the 5D theory which is $\\sim 10$ TeV. The Yukawa matrices as well as the Majorana mass matrix for the neutrinos are generated by higher dimension operators involving the flavon field. When the flavon field acquires a vacuum expectation value it breaks the flavor symmetry and thus generates the Yukawa couplings. The model is consistent with the nearly bimaximal solution to the solar and atmospheric neutrino deficits.

  17. Materia extraña

    CERN Document Server

    Gómez Cadenas, J J

    2008-01-01

    Enero, 1999. Unas extrañas burbujas se han colocado en el acelerador de particulas del CERN (Ginebra). Ante el riesgo de que esto desencadene una catástrofe a escala mundial, el centro ordena detener el experimento. Años después, Irene, una joven y promotedora científica, es contratada en la división de Física Teórica del CERN. Allí coincide con el mayor Espinosa, destinado a la sede suiza de la ONU para trabajar en un proyecto contra la proliferación de armas nucleares. La misión de Espinosa resulta ser mucho más arriesgada de lo que parecía. Irene ambiciosa y rebelde, toma una decisión de efectos imprevisibles.

  18. Exploring Extra Dimensions in Spectroscopy Experiments

    Institute of Scientific and Technical Information of China (English)

    LUO Feng; LIU Hong-Ya

    2006-01-01

    @@ We propose an idea in spectroscopy to search for extra spatial dimensions as well as to detect the possible deviation from Newton's inverse-square law at small scale, and we take high-Z hydrogenic systems and muonic atoms as illustrations. The relevant experiments might help to explore a more than two extra dimensions scenario in the brane world model proposed by Arkani-Hamed, Dimopoulos, Dvali (ADD) and to set constraints for fundamental parameters such as the size of extra dimensions.

  19. Insights from a refined decomposition of cloud feedbacks

    Science.gov (United States)

    Zelinka, Mark D.; Zhou, Chen; Klein, Stephen A.

    2016-09-01

    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 cloud feedback but its anticorrelation with other components damps overall spread. 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.

  20. Extra and intradural spinal Hemangioblastoma Hemangioblastoma espinal extra e intradural Hemangioblastoma espinhal extra e intradural

    Directory of Open Access Journals (Sweden)

    Marcelo Campos Moraes Amato

    2012-09-01

    Full Text Available Hemangioblastomas of the central nervous system (CNS are low-grade highly vascularized tumors that may be sporadic or associated with Von Hippel-Lindau disease. Extradural hemangioblastomas are uncommon and those located extra and intradurally are even rarer. This study uses an illustrative case and literature review to discuss the difficulties to consider the correct diagnosis and to select the best surgical approach. A 57 years-old white male patient presented with myelopathy and right C5 radiculopathy. The images showed a lobulated, hourglass shaped, highly enhanced extra/intradural lesion that occupied the spinal canal and widened the C4-C5 right intervertebral foramen. Total resection of the intradural lesion was achieved through a posterior approach, but the extradural part could only be partially removed. Complete improvement was observed after four months of follow-up and the residual tumor has been followed up clinically and radiologically. Even though the preoperative impression was of a spinal schwannoma, the histopathological examination revealed grade I hemangioblastoma as per WHO. Despite their rarity, current complementary exams allow considering the diagnosis of hemangioblastoma preoperatively. That is essential to a better surgical planning in view of the particular surgical features of this lesion.Hemangioblastomas del sistema nervioso central (SNC son tumores altamente vascularizados, de grado bajo, que pueden ser esporádicos o vinculados a la enfermedad de Von Hippel-Lindau. Hemangioblastomas extradurales no son comunes, y aquellos localizados extra e intraduralmente son aún más raros. Este estudio usa un caso ilustrativo y la revisión de la literatura para analizar las dificultades cuanto a considerar el diagnóstico correcto y para seleccionar el mejor abordaje quirúrgico. Un paciente, hombre blanco de 57 años de edad, presentaba mielopatía con radiculopatía C5 derecha. Las imágenes mostraban lesión extra

  1. Extra informatie op matrixborden : mogelijkheden en effecten.

    NARCIS (Netherlands)

    Craen, S. de & Niet, M. de

    2002-01-01

    In this report, the possibilities of displaying extra safety information on Dynamic Message Signs (DMSs) are explored. The technical possibilities for placing extra information on the signs are looked at, and the road safety effects are examined. The information to be displayed can be divided into t

  2. Extra dimensions at particle colliders

    Energy Technology Data Exchange (ETDEWEB)

    Dvergsnes, Erik Wolden

    2004-08-01

    This thesis consists of an introduction where we consider different aspects of theories involving extra dimensions, together with four research publications (Papers I-IV) attached at the end. The introductional chapters should serve as background material for better understanding the models on which the articles are based. In Chap. 4 we also present some plots not included in the papers. The topic of Papers I-III is graviton induced Bremsstrahlung. In Paper I we consider the contribution to this process from graviton exchange through gluon-gluon fusion at the LHC, compared to the QED background. Only final-state radiation is considered in Paper I, whereas in Paper II we extend this work to include also the quark-antiquark annihilation with graviton exchange, as well as initial-state radiation for both graviton and Standard Model exchange. Paper III is a study of graviton-induced Bremsstrahlung at e{sup +}e{sup -} colliders, including both initial- and final-state radiation. Paper IV is devoted to a study of the center-edge asymmetry at hadron colliders, an asymmetry which previously had been studied for e{sup +}e{sup -} colliders. The center-edge asymmetry can be used as a method of distinguishing between spin-1 and spin-2 exchange, something which will be of major importance if a signal is observed.

  3. A review on models for count data with extra zeros

    Science.gov (United States)

    Zamri, Nik Sarah Nik; Zamzuri, Zamira Hasanah

    2017-04-01

    Typically, the zero inflated models are usually used in modelling count data with excess zeros. The existence of the extra zeros could be structural zeros or random which occur by chance. These types of data are commonly found in various disciplines such as finance, insurance, biomedical, econometrical, ecology, and health sciences. As found in the literature, the most popular zero inflated models used are zero inflated Poisson and zero inflated negative binomial. Recently, more complex models have been developed to account for overdispersion and unobserved heterogeneity. In addition, more extended distributions are also considered in modelling data with this feature. In this paper, we review related literature, provide a recent development and summary on models for count data with extra zeros.

  4. Paraganglioma funcional extra-adrenal

    Directory of Open Access Journals (Sweden)

    Laura Arroyo-Martínez

    2006-03-01

    Full Text Available Los paragangliomas funcionales son tumores raros, se originan del tejido cromafín extraadrenal productor de catecolaminas, con frecuencia son malignos y tienen alta incidencia de enfermedad persistente o recurrente¹. Se les conoce como: glomus, quemodectomas, paragangliomas cromafines y glomerulocitomas. La localización es diversa y refleja la distribución paraganglionar en el cuerpo, desde la base del cráneo hasta el piso pélvico. Los paragangliomas se encuentran en donde hay ganglios del sistema autónomo, sin embargo, aproximadamente el 90% de estos tumores aparecen en las glándulas suprarrenales (y constituyen los feocromocitomas y el 10% restante tienen una ubicación extraadrenal, mas se ha dicho que su incidencia puede ser subestimada, variando del 18% al 22% en adultos, y en niños hasta un 30%. Los extra-adrenales se originan con mayor frecuencia en el abdomen (85%, otros en el tórax (12% y más raramente en la cabeza y el cuello (3% ². Los estudios de imágenes y la medición de la producción no fisiológica de catecolaminas pueden ayudar en el diagnóstico de esta entidad. La cirugía es el tratamiento de elección. Presentamos aquí el caso de una paciente de 32 años, primigesta con HTAIE que requirió cesárea, quien tuvo un postparto tórpido y pese a múltiples tratamientos antihipertensivos su patología fue de difícil manejo, con complicaciones oftálmicas. Tiempo después la paciente se estudia por hiperhidrosis, se solicitan exámenes de laboratorio e imágenes y se le documenta incidentalmente, una tumoración retroperitoneal izquierda, se le amplían los estudios, y se llega al diagnóstico correcto. La tumoración requirió resección quirúrgica. Tuvo un postoperatorio satisfactorio y la paciente egresó con control en la Consulta Externa.Functioning paragangliomas are rare tumors that produce catecholamines. They originate from extra-adrenal chromaffin cells. They are frequentIy malignant and are associated

  5. The Motivational Hierarchy between Self and Mother:Evidence from the Feedback-related Negativity%母亲与自我具有相同的动机等级:来自结果评价的FRN证据

    Institute of Scientific and Technical Information of China (English)

    朱湘茹; 张艳; 杨苏勇; 伍海燕; 王丽丽; 古若雷

    2015-01-01

    their mothers than for strangers, but there was no significant difference between self and mother conditions. These ERP results provided evidence that self and mother share the same motivational hierarchy in Chinese brain.%自我不仅包括个体自我,还包括关系自我。母亲是关系自我一个非常重要的构成。朱滢等人(2007)的研究表明,与西方文化下的被试不同,母亲与自我在中国人大脑中的表征无显著差异。但是目前尚不清楚母亲与自我的动机等级性是否存在差异。在本研究中,我们利用一个简单的赌博任务,以反馈相关负波(feedback-related negativity, FRN)为指标,考察为自己而赌、为母亲而赌和为陌生人而赌三种情境下FRN波幅有无差异。行为结果没有发现三种不同受益者情境下的动机差异。脑电结果发现母亲和自我情境下的FRN显著大于陌生人情境下的 FRN,但是母亲和自我情境下的 FRN 波幅统计上无显著差异。这个结果表明,母亲和自我的动机等级性在中国文化下是相同的。本研究首次在结果评价领域提供了母亲与自我具有相同动机等级的脑电证据。

  6. SOGI-based capacitor voltage feedback active damping in LCL-filtered grid converters

    DEFF Research Database (Denmark)

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang

    2015-01-01

    The capacitor voltage feedback active damping control is an attractive way to suppress LCL-filter resonance especially for the systems where the capacitor voltage is used for grid synchronization, since no extra sensors are added. The derivative is the core of the capacitor voltage feedback active...... derivative is more suited for capacitor voltage feedback active damping control. Experimental results validate the effectiveness of the proposed method....

  7. Paraganglioma funcional extra-adrenal

    Directory of Open Access Journals (Sweden)

    Laura Arroyo-Martínez

    2006-03-01

    Full Text Available Los paragangliomas funcionales son tumores raros, se originan del tejido cromafín extraadrenal productor de catecolaminas, con frecuencia son malignos y tienen alta incidencia de enfermedad persistente o recurrente¹. Se les conoce como: glomus, quemodectomas, paragangliomas cromafines y glomerulocitomas. La localización es diversa y refleja la distribución paraganglionar en el cuerpo, desde la base del cráneo hasta el piso pélvico. Los paragangliomas se encuentran en donde hay ganglios del sistema autónomo, sin embargo, aproximadamente el 90% de estos tumores aparecen en las glándulas suprarrenales (y constituyen los feocromocitomas y el 10% restante tienen una ubicación extraadrenal, mas se ha dicho que su incidencia puede ser subestimada, variando del 18% al 22% en adultos, y en niños hasta un 30%. Los extra-adrenales se originan con mayor frecuencia en el abdomen (85%, otros en el tórax (12% y más raramente en la cabeza y el cuello (3% ². Los estudios de imágenes y la medición de la producción no fisiológica de catecolaminas pueden ayudar en el diagnóstico de esta entidad. La cirugía es el tratamiento de elección. Presentamos aquí el caso de una paciente de 32 años, primigesta con HTAIE que requirió cesárea, quien tuvo un postparto tórpido y pese a múltiples tratamientos antihipertensivos su patología fue de difícil manejo, con complicaciones oftálmicas. Tiempo después la paciente se estudia por hiperhidrosis, se solicitan exámenes de laboratorio e imágenes y se le documenta incidentalmente, una tumoración retroperitoneal izquierda, se le amplían los estudios, y se llega al diagnóstico correcto. La tumoración requirió resección quirúrgica. Tuvo un postoperatorio satisfactorio y la paciente egresó con control en la Consulta Externa.

  8. Extra dimensions in space and time

    CERN Document Server

    Bars, Itzhak

    2010-01-01

    Covers topics such as Einstein and the Fourth Dimension; Waves in a Fifth Dimension; and String Theory and Branes Experimental Tests of Extra Dimensions. This book offers a discussion on Two-Time Physics

  9. Fault Tolerant Feedback Control

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, H.

    2001-01-01

    An architecture for fault tolerant feedback controllers based on the Youla parameterization is suggested. It is shown that the Youla parameterization will give a residual vector directly in connection with the fault diagnosis part of the fault tolerant feedback controller. It turns out...... that there is a separation be-tween the feedback controller and the fault tolerant part. The closed loop feedback properties are handled by the nominal feedback controller and the fault tolerant part is handled by the design of the Youla parameter. The design of the fault tolerant part will not affect the design...... of the nominal feedback con-troller....

  10. Pasta de azeite versus azeite virgem extra

    OpenAIRE

    Dias, Susana Marisa da Cunha

    2009-01-01

    Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia Innovative products of high nutritional quality, with healthy benefits and extended conservation are an asset to the food sector. With beneficial health properties and high nutritional quality, extra virgin olive oil is an extraordinary fat, thanks to its unique chemical composition. The olive oil spread, subject of this study, is an innovative product, created from extra virgin olive oil, with a consistency ...

  11. Editorial: Focus on Extra Space Dimensions

    Science.gov (United States)

    Agashe, Kaustubh; Pomarol, Alex

    2010-07-01

    Experiments at the Large Hadron Collider (LHC) have just started. In addition to verifying the Standard Model (SM) of particle physics, these experiments will probe a new energy frontier and test extensions of the SM. The existence of extra dimensions is one of the most attractive possibilities for physics beyond the SM. This focus issue contains a collection of articles addressing both theoretical and phenomenological aspects of extra-dimensional models. Focus on Extra Space Dimensions Contents Minimal universal extra dimensions in CalcHEP/CompHEP AseshKrishna Datta, Kyoungchul Kong and Konstantin T Matchev Disordered extra dimensions Karim Benakli Codimension-2 brane-bulk matching: examples from six and ten dimensions Allan Bayntun, C P Burgess and Leo van Nierop Gauge threshold corrections in warped geometry Kiwoon Choi, Ian-Woo Kim and Chang Sub Shin Holographic methods and gauge-Higgs unification in flat extra dimensions Marco Serone Soft-wall stabilization Joan A Cabrer, Gero von Gersdorff and Mariano Quirós Warped five-dimensional models: phenomenological status and experimental prospects Hooman Davoudiasl, Shrihari Gopalakrishna, Eduardo Pontón and José Santiago

  12. Nonlinear feedback control of Timoshenko beam

    Institute of Scientific and Technical Information of China (English)

    冯德兴; 张维弢

    1995-01-01

    This note is concerned with nonlinear boundary feedback control of a Timoshenko beam. Under some nonlinear boundary feedback control, first the nonlinear semigroup theory is used to show the existence and uniqueness of solution for the corresponding closed loop system. Then by using the Lyapunov method, it is proved that the vibration of the beam under the proposed control action decays in a negative power of time t as t→.

  13. Types and Frequencies of Feedback Interventions in Classroom Interaction in Secondary Education

    Science.gov (United States)

    Voerman, Lia; Meijer, Paulien C.; Korthagen, Fred A. J.; Simons, Robert Jan

    2012-01-01

    Contributing to the growing amount of literature on learning-enhancing feedback, this article attempts to distinguish between progress feedback and discrepancy feedback. Building on relevant literature drawn from psychology, we propose the use of a ratio of 3:1, positive:negative feedback. We analyzed contiguous 10 min blocks of classroom…

  14. Feedback is good or bad? Medical residents’ points of view on feedback in clinical education

    Directory of Open Access Journals (Sweden)

    LEILA BAZRAFKAN

    2013-04-01

    Full Text Available Introduction: Feedback is very important in education and can help quality in the training process and orient the trainees in clinical contexts. This study aimed to assess the residents’ points of view about feedback in clinical education at Shiraz University of Medical Sciences. Methods: The sample of this study included 170 medical residents attending medical workshops in Shiraz University of Medical Sciences. The residents filled a valid and reliable questionnaire containing 21 items on their perceptions of the feedback they got throughout the workshops. The data were analyzed using SPSS version 14. Results: The study revealed that residents, generally, have a positive perception of feedback in their training. The highest score belonged to the items such as “feedback was applicable to future work”, “feedback corrected my behavior”, “feedback worked as a motivation for education” and “feedback was specific in one subject”. Residents who had a negative feedback experience also increased their efforts to learn. The Surgery residents acquired the highest scores while radiology residents got the lowest. The difference between these groups was statistically significant (P = 0.000. Conclusion: The highest mean score belonged to internal medicine residents. This shows that residents believe that obstetrics & gynecology ward is a ward in which the formative assessment is much more powerful in comparison to the other three major wards. The surgery ward received the lowest score for formative assessment and this shows that the feedback in surgery ward is very low.

  15. Rateless feedback codes

    DEFF Research Database (Denmark)

    Sørensen, Jesper Hemming; Koike-Akino, Toshiaki; Orlik, Philip

    2012-01-01

    This paper proposes a concept called rateless feedback coding. We redesign the existing LT and Raptor codes, by introducing new degree distributions for the case when a few feedback opportunities are available. We show that incorporating feedback to LT codes can significantly decrease both...... the coding overhead and the encoding/decoding complexity. Moreover, we show that, at the price of a slight increase in the coding overhead, linear complexity is achieved with Raptor feedback coding....

  16. Preventing Feedback Fizzle

    Science.gov (United States)

    Brookhart, Susan M.

    2012-01-01

    Feedback is certainly about saying or writing helpful, learning-focused comments. But that is only part of it. What happens beforehand? What happens afterward? Feedback that is helpful and learning-focused fits into a context. Before a teacher gives feedback, students need to know the learning target so they have a purpose for using the feedback…

  17. Developing Sustainable Feedback Practices

    Science.gov (United States)

    Carless, David; Salter, Diane; Yang, Min; Lam, Joy

    2011-01-01

    Feedback is central to the development of student learning, but within the constraints of modularized learning in higher education it is increasingly difficult to handle effectively. This article makes a case for sustainable feedback as a contribution to the reconceptualization of feedback processes. The data derive from the Student Assessment and…

  18. Feedback effect on flute dynamics in a mirror machine

    Science.gov (United States)

    Be'Ery, Ilan; Seemann, Omri

    2015-11-01

    Active feedback techniques may stabilize the flute instability in mirror traps and make them viable candidates for fusion machines. A fast feedback with optical sensors and electrical actuators was implemented in a table-top mirror machine and used to study several aspects of feedback stabilization. For a cold, dense plasma the feedback reduces dramatically the flute amplitude of the first two mode. For higher temperature plasma, a significant increase of plasma density due to feedback stabilization is also demonstrated. The effect of changing feedback gain and phase has some interesting feature such as asymmetry with respect to positive and negative phase shifts and non-monotonic dependence of flute amplitude on feedback gain. These effects are explained using simplified analytic model of the flute and feedback.

  19. Extra-oral halitosis: an overview.

    Science.gov (United States)

    Tangerman, A; Winkel, E G

    2010-03-01

    Halitosis can be subdivided into intra-oral and extra-oral halitosis, depending on the place where it originates. Most reports now agree that the most frequent sources of halitosis exist within the oral cavity and include bacterial reservoirs such as the dorsum of the tongue, saliva and periodontal pockets, where anaerobic bacteria degrade sulfur-containing amino acids to produce the foul smelling volatile sulfur compounds (VSCs), especially hydrogen sulfide (H(2)S) and methyl mercaptan (CH(3)SH). Tongue coating is considered to be the most important source of VSCs. Oral malodor can now be treated effectively. Special attention in this overview is given to extra-oral halitosis. Extra-oral halitosis can be subdivided into non-blood-borne halitosis, such as halitosis from the upper respiratory tract including the nose and from the lower respiratory tract, and blood-borne halitosis. The majority of patients with extra-oral halitosis have blood-borne halitosis. Blood-borne halitosis is also frequently caused by odorous VSCs, in particular dimethyl sulfide (CH3SCH3). Extra-oral halitosis, covering about 5-10% of all cases of halitosis, might be a manifestation of a serious disease for which treatment is much more complicated than for intra-oral halitosis. It is therefore of utmost importance to differentiate between intra-oral and extra-oral halitosis. Differences between intra-oral and extra-oral halitosis are discussed extensively. The importance of applying odor characterization of various odorants in halitosis research is also highlighted in this article. The use of the odor index, odor threshold values and simulation of bad breath samples is explained.

  20. Polarized Th1 and Th2 cells are less responsive to negative feedback by receptors coupled to the AC/cAMP system compared to freshly isolated T cells

    NARCIS (Netherlands)

    Heijink, Irene H; Vellenga, Edo; Borger, Peter; Postma, Dirkje S; Monchy, Jan G R de; Kauffman, Henk F

    2003-01-01

    1 The adenylyl cyclase (AC)/cyclic adenosine monophosphate (cAMP) system is known to negatively regulate transcriptional activity of T cells, thereby possibly modulating T-cell-mediated responses at the sites of inflammation. Effects of cAMP have been widely studied in freshly isolated T cells and T

  1. Dark Energy as Evidence for Extra Dimensions

    CERN Document Server

    Milton, K A

    2003-01-01

    It is argued that fluctuations of quantum fields in four-dimensional space do not give rise to dark energy, but are rather a negligible contribution to dark matter. By (relativistic) dark matter we mean that the relation between pressure and energy density is $p=\\frac13 u$, while dark energy is characterized by $p=-u$. A possible source of dark energy are the fluctuations in quantum fields, including quantum gravity, inhabiting extra compactified dimensions. These fluctuations have been computed for some simple geometries, such as $S^2$, $S^4$, and $S^6$. If the extra dimensions are too small, they would give rise to a dark energy larger than that observed, whereas if they are too large they would be in conflict with experimental tests of Newton's law. This notion suggests that the size of the extra dimensions is of order 100 $\\mu$m. If the limit on the size of extra dimensions becomes lower than this bound, extra dimensions probably do not exist, and another source for cosmological dark energy will have to b...

  2. Quantum feedback channels

    CERN Document Server

    Bowen, G

    2002-01-01

    In classical information theory the capacity of a noisy communication channel cannot be increased by the use of feedback. In quantum information theory the no-cloning theorem means that noiseless copying and feedback of quantum information cannot be achieved. In this paper, quantum feedback is defined as the unlimited use of a noiseless quantum channel from receiver to sender. Given such quantum feedback, it is shown to provide no increase in the entanglement-assisted capacities of a noisy quantum channel, in direct analogy to the classical case. It is also shown that in various cases of non-assisted capacities, feedback can increase the capacity of many quantum channels.

  3. Situated Formative Feedback

    DEFF Research Database (Denmark)

    Lukassen, Niels Bech; Wahl, Christian; Sorensen, Elsebeth Korsgaard

    2016-01-01

    This study addresses the conceptual challenge of providing students with good quality feedback to enhance student learning in an online community of practice (COP). The aim of the study is to identify feedback mechanisms in a virtual learning environment (VLE) and to create a full formative...... feedback episode (FFE) through an online dialogue. The paper argues that dialogue is crucial for student learning and that feedback is not only something the teacher gives to the student. Viewing good quality feedback as social, situated, formative, emphasis is put on the establishment of dialogue. We...... refer to this type of feedback as, Situated Formative Feedback (SFF). As a basis for exploring, identifying and discussing relevant aspects of SFF the paper analyses qualitative data from a Moodle dialogue. Data are embedded in the qualitative analytic program Nvivo and are analysed with a system...

  4. Neural correlates of anticipation and processing of performance feedback in social anxiety.

    Science.gov (United States)

    Heitmann, Carina Y; Peterburs, Jutta; Mothes-Lasch, Martin; Hallfarth, Marlit C; Böhme, Stephanie; Miltner, Wolfgang H R; Straube, Thomas

    2014-12-01

    Fear of negative evaluation, such as negative social performance feedback, is the core symptom of social anxiety. The present study investigated the neural correlates of anticipation and perception of social performance feedback in social anxiety. High (HSA) and low (LSA) socially anxious individuals were asked to give a speech on a personally relevant topic and received standardized but appropriate expert performance feedback in a succeeding experimental session in which neural activity was measured during anticipation and presentation of negative and positive performance feedback concerning the speech performance, or a neutral feedback-unrelated control condition. HSA compared to LSA subjects reported greater anxiety during anticipation of negative feedback. Functional magnetic resonance imaging results showed deactivation of medial prefrontal brain areas during anticipation of negative feedback relative to the control and the positive condition, and medial prefrontal and insular hyperactivation during presentation of negative as well as positive feedback in HSA compared to LSA subjects. The results indicate distinct processes underlying feedback processing during anticipation and presentation of feedback in HSA as compared to LSA individuals. In line with the role of the medial prefrontal cortex in self-referential information processing and the insula in interoception, social anxiety seems to be associated with lower self-monitoring during feedback anticipation, and an increased self-focus and interoception during feedback presentation, regardless of feedback valence.

  5. Compact Extra Dimensions in Quantum Mechanics

    CERN Document Server

    Deutschmann, Nicolas

    2016-01-01

    Extra-dimensions are a common topic in popular descriptions of theoretical physics with which undergraduate student most often have no contact in physics courses. This paper shows how students could be introduced to this topic by presenting an approach to two basic consequences of the presence of compact extra-dimensions based on undergraduate-level physics. The insensibility of low-energy physics to compact extra dimensions is illustrated in the context of non-relativistic quantum mechanics and the prediction of Kaluza-Klein excitations of particles is discussed in the framework of relativistic wave-equations. An exercise that could be used as a follow-up to the "particle in a box" is proposed.

  6. Extra-dimensional models on the lattice

    CERN Document Server

    Knechtli, Francesco

    2016-01-01

    In this review we summarize the ongoing effort to study extra-dimensional gauge theories with lattice simulations. In these models the Higgs field is identified with extra-dimensional components of the gauge field. The Higgs potential is generated by quantum corrections and is protected from divergencies by the higher dimensional gauge symmetry. Dimensional reduction to four dimensions can occur through compactification or localization. Gauge-Higgs unification models are often studied using perturbation theory. Numerical lattice simulations are used to go beyond these perturbative expectations and to include non-perturbative effects. We describe the known perturbative predictions and their fate in the strongly-coupled regime for various extra-dimensional models.

  7. Extra-pulmonary manifestations of sarcoidosis

    Energy Technology Data Exchange (ETDEWEB)

    Vardhanabhuti, V. [Radiology Department, Derriford Hospital, Plymouth (United Kingdom); Venkatanarasimha, N. [St Michael' s Hospital, 30 Bond Street, Toronto, Ontario M5B 1W8 (Canada); Bhatnagar, G.; Maviki, M.; Iyengar, S.; Adams, W.M. [Radiology Department, Derriford Hospital, Plymouth (United Kingdom); Suresh, P., E-mail: sureshpriya2000@yahoo.com [Radiology Department, Derriford Hospital, Plymouth (United Kingdom)

    2012-03-15

    Although, the diagnosis and evaluation of sarcoidosis has traditionally remained confined to the chest, its multi-system nature has been widely recognized. Radiological features of pulmonary sarcoidosis are well known but extra-pulmonary manifestations can produce a plethora of non-specific imaging findings that can affect subcutaneous tissue, and the neurological, cardiac, gastrointestinal, urological, liver, spleen, and skeletal systems. In the literature, there are various case reports and specific system reviews but there are few reviews that encompass all the extra-pulmonary manifestations. In this paper, we comprehensively review the imaging features of extra-pulmonary sarcoidosis with characteristic features as well as atypical presentations. In addition, we discuss the emerging role of nuclear medicine in sarcoidosis.

  8. Longitudinal influence of musculo-skeletal injuries and extra physical education on physical fitness in schoolchildren.

    Science.gov (United States)

    Rexen, C T; Ersbøll, A K; Wedderkopp, N; Andersen, L B

    2016-12-01

    The aims of this study were to investigate if (A) injuries and (B) increased physical education (PE) influenced the development of physical fitness in schoolchildren. Simultaneously, to investigate if a possible PE effect was modified by sport participation outside school hours. This was a longitudinal controlled school-based study. Six schools with 270 min of PE (extra PE) and four schools with 90 min of PE were followed up for 2.5 years. In total, 1054 children were included for analysis (normal PE = 443, extra PE = 611). Development in fitness was analyzed using composite z-scores from six fitness tests measured four times. Information of injury and sport was derived from weekly automated mobile phone text messages surveying the presence of musculo-skeletal pain and organized sport participation. Injury and extra PE both influenced the development of physical fitness. Injury decreased development of physical fitness with -1.01 composite z-score units (95% CI: -1.57; -0.45). Extra PE increased physical fitness development with 0.80 (95% CI: 0.49; 1.10) composite z-score units. The influence of injury was not dependent on extra PE. No modifying effect was found by mean weekly sport participation outside school hours. In conclusion, extra PE had a positive effect, whereas injuries had a negative effect on physical fitness development in schoolchildren. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. Mediation of supersymmetry breaking in extra dimensions

    CERN Document Server

    Scrucca, C A

    2004-01-01

    I review the mechanisms of supersymmetry breaking mediation that occur in sequestered models, where the visible and the hidden sectors are separated by an extra dimension and communicate only via gravitational interactions. By locality, soft breaking terms are forbidden at the classical level and reliably computable within an effective field theory approach at the quantum level. I present a self-contained discussion of these radiative gravitational effects and the resulting pattern of soft masses, and give an overview of realistic model building based on this set-up. I consider both flat and warped extra dimensions, as well as the possibility that there be localized kinetic terms for the gravitational fields.

  10. Electromagnetism from extra space multi connectivity

    Energy Technology Data Exchange (ETDEWEB)

    Gauthier, C. [Moncton Univ., Moncton (France). Dept. de Mathematiques et de Statistique

    2001-09-01

    In a unified field theory of the Kaluza-Klein type, it is used a multi connected extra space to interpret geometrically the quantum properties of physics. This paper presents a pure geometric interpretation of electromagnetism. The electric change of a body is identified with its cross-section for interaction of twisted waves due to the extra space multi connectivity. A by-product of this interpretation is an expression for the permittivity of free space as an integral of the flux of these waves over their frequencies.

  11. Signatures of extra dimensional sterile neutrinos

    Directory of Open Access Journals (Sweden)

    Werner Rodejohann

    2014-10-01

    Full Text Available We study a large extra dimension model with active and sterile Dirac neutrinos. The sterile neutrino masses stem from compactification of an extra dimension with radius R and are chosen to have masses around eV or keV, in order to explain short-baseline anomalies or act as warm dark matter candidates. We study the effect of the sterile neutrino Kaluza–Klein tower in short-baseline oscillation experiments and in the beta spectrum as measurable by KATRIN-like experiments.

  12. Signatures of extra dimensional sterile neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Rodejohann, Werner, E-mail: werner.rodejohann@mpi-hd.mpg.de; Zhang, He, E-mail: he.zhang@mpi-hd.mpg.de

    2014-10-07

    We study a large extra dimension model with active and sterile Dirac neutrinos. The sterile neutrino masses stem from compactification of an extra dimension with radius R and are chosen to have masses around eV or keV, in order to explain short-baseline anomalies or act as warm dark matter candidates. We study the effect of the sterile neutrino Kaluza–Klein tower in short-baseline oscillation experiments and in the beta spectrum as measurable by KATRIN-like experiments.

  13. The Higgs Mechanism from an extra dimension

    CERN Document Server

    A., Yu

    2016-01-01

    The standard $SU(2) \\times U(1)$ fields are considered in 4D plus one extra compact dimension. As a result two basic effects are obtained. First, four Goldstone-like scalars are produced, three of them are used to create longitudinal modes of the $W,Z$ fields, while the fourth becomes the Higgs-like scalar. Second, $W$ and $Z$ get their masses from the extra compact dimension with the standard pattern of symmetry violation. The resulting theory has the same fields as in the standard model, but without the Higgs vacuum average. The properties of the new Higgs scalar and its interaction with fermions are briefly discussed.

  14. Phenomenology of symmetry breaking from extra dimensions

    CERN Document Server

    Alfaro, J; Gavela-Legazpi, Maria Belen; Rigolin, S; Salvatori, M

    2007-01-01

    Motivated by the electroweak hierarchy problem, we study the symmetry breaking pattern induced by a background magnetic flux living on extra dimensions, with the four-dimensional scalar fields being gauge boson components in full space. For SU(N) and two compact, toroidal, extra dimensions, we determine analytically the possible field configurations of stable vacua and their symmetries. From the four-dimensional point of view, the system responds dynamically to the magnetic background by an infinite chain of vacuum expectation values so as to reach a stable vacuum. The equivalence between flux compactification and constant boundary conditions - either Scherk-Schwarz or twisted - is established.

  15. A positive feedback synapse from retinal horizontal cells to cone photoreceptors.

    Directory of Open Access Journals (Sweden)

    Skyler L Jackman

    2011-05-01

    Full Text Available Cone photoreceptors and horizontal cells (HCs have a reciprocal synapse that underlies lateral inhibition and establishes the antagonistic center-surround organization of the visual system. Cones transmit to HCs through an excitatory synapse and HCs feed back to cones through an inhibitory synapse. Here we report that HCs also transmit to cone terminals a positive feedback signal that elevates intracellular Ca(2+ and accelerates neurotransmitter release. Positive and negative feedback are both initiated by AMPA receptors on HCs, but positive feedback appears to be mediated by a change in HC Ca(2+, whereas negative feedback is mediated by a change in HC membrane potential. Local uncaging of AMPA receptor agonists suggests that positive feedback is spatially constrained to active HC-cone synapses, whereas the negative feedback signal spreads through HCs to affect release from surrounding cones. By locally offsetting the effects of negative feedback, positive feedback may amplify photoreceptor synaptic release without sacrificing HC-mediated contrast enhancement.

  16. 电励磁同步电动机转矩角截止负反馈闭环控制%Torque-Angle Cut-Off Negative Feedback Closed-Loop Control Strategy of Electrical Excited Synchronous Motor

    Institute of Scientific and Technical Information of China (English)

    谢慕君; 步伟明; 冯敬芳; 王志乾

    2013-01-01

    针对电励磁同步电动机负载变化易失步的问题,通过对转矩角特性分析,提出了一种基于转矩角截止负反馈的控制策略。阐述了利用转矩角控制防止失步的原理,建立了基于同步电动机磁链观测的转矩角数学模型,并设计了转矩角外环、励磁电流内环的双闭环控制系统。仿真结果表明,该控制策略与常规控制相比,适应负载变化的能力显著提高,有效抑制了电机的失步,为电机的稳定控制开辟了新途径。%Aiming at the problem that the electrical synchronous excited motor will be out of step with the load changes, this paper raised a control strategy based on torque-angle cut-off feedback via the analysis of torque-angle characteristics. Discussion was made to the principle using torque-angle control to prevent out-of-step. The mathematical model of torque-angle was constructed based on the flux linkage observation of synchronous motors and the double closed-loop control system for the outer loop adopting torque-angle and the inner loop adopting field current were designed. The simulation results show that compared with conventional control, this control strategy obviously met the requirements of load changes, effectively restraining out-of-step of motors, which opens up a new way for stable control of motors.

  17. Pulmonary involvement in patients presenting with extra-pulmonary tuberculosis: thinking beyond a normal chest x-ray

    Directory of Open Access Journals (Sweden)

    Herath S

    2014-03-01

    Full Text Available INTRODUCTION: Recognition of pulmonary involvement in extra-pulmonary tuberculosis (TB may be an important public health issue, as smear-negative pulmonary TB is responsible for about 17% of new infections. Pulmonary TB can be present despite a normal chest x-ray (CXR, even in human immunodeficiency virus (HIV–negative patients. In this retrospective clinical audit, we reviewed a case series of HIV-negative patients with extra-pulmonary tuberculosis to identify the proportion with concurrent pulmonary TB despite an unremarkable CXR. METHODS: Clinical notes, microbiology results and CXR reports were reviewed from consecutive patients treated at Auckland City Hospital for extra-pulmonary TB from January 2007 to July 2010. RESULTS: Of the sample of 103 patients with extra-pulmonary TB, the majority of patients were born in an Asian country (n=70; 68%. The commonest presentation of extra-pulmonary TB was lymphadenopathy (n=51; 50%, followed by pleural (n=24; 23% and bone (n=6; 6% disease. Extra-pulmonary TB was diagnosed by biopsy or excision of the extra-pulmonary site in the majority (n=74; 72%, and by sputum testing alone in 26 (25%. The majority had CXR abnormalities (n=76; 74%. In the group with a normal CXR (n=27, 55% (n=15 had sputum cultures performed. In total, 18% (n=5 of patients with extra-pulmonary TB and a normal CXR had pulmonary TB, of whom two were smear positive. DISCUSSION: In patients with extra-pulmonary TB, sputum testing should be considered to detect concurrent pulmonary TB even if a CXR is normal, especially in immunosuppressed or symptomatic patients. This may aid diagnosis and determine infectivity and consequent public health action.

  18. The Greenhouse Effect and Climate Feedbacks

    Science.gov (United States)

    Covey, C.; Haberle, R. M.; McKay, C. P.; Titov, D. V.

    This chapter reviews the theory of the greenhouse effect and climate feedback. It also compares the theory with observations, using examples taken from all four known terrestrial worlds with substantial atmospheres: Venus, Earth, Mars, and Titan. The greenhouse effect traps infrared radiation in the atmosphere, thereby increasing surface temperature. It is one of many factors that affect a world's climate. (Others include solar luminosity and the atmospheric scattering and absorption of solar radiation.) A change in these factors — defined as climate forcing — may change the climate in a way that brings other processes — defined as feedbacks — into play. For example, when Earth's atmospheric carbon dioxide increases, warming the surface, the water vapor content of the atmosphere increases. This is a positive feedback on global warming because water vapor is itself a potent greenhouse gas. Many positive and negative feedback processes are significant in determining Earth's climate, and probably the climates of our terrestrial neighbors.

  19. Extra-1 acupressure for children undergoing anesthesia.

    Science.gov (United States)

    Wang, Shu-Ming; Escalera, Sandra; Lin, Eric C; Maranets, Inna; Kain, Zeev N

    2008-09-01

    Acupuncture and related techniques have been used as adjuncts for perioperative anesthesia management. We examined whether acupressure in the Extra-1 (Yin-Tang) point would result in decreased preprocedural anxiety and reduced intraprocedural propofol requirements in a group of children undergoing endoscopic procedures. Fifty-two children were randomized to receive acupressure bead intervention either at the Extra-1 acupuncture point or at a sham point. A Bispectral Index (BIS) monitor was applied to all children before the onset of the intervention. Anxiety was assessed at baseline and before entrance to the operating room. Anesthetic techniques were standardized and maintained with IV propofol infusion titrated to keep BIS values of 40-60. We found that after the intervention, children in the Extra-1 group experienced reduced anxiety whereas children in the sham group experienced increased anxiety (-9% [-3 to -15] vs 2% [-6 to 7.4], P = 0.012). In contrast, no significant changes in BIS values were observed in the preprocedural waiting period between groups (P = ns). We also found that total intraprocedural propofol requirements did not differ between the two study groups (214 +/- 76 microg x kg(-1) x min(-1) vs 229 +/- 95 microg x kg(-1) x min(-1), P = 0.52). We conclude that acupressure bead intervention at Extra-1 acupoint reduces preprocedural anxiety in children undergoing endoscopic procedures. This intervention, however, has no impact on BIS values or intraprocedural propofol requirements.

  20. Gauge coupling unification with extra Higgs doublets

    Energy Technology Data Exchange (ETDEWEB)

    Harada, Junpei [Research Center for Higher Education, Health Sciences University of Hokkaido (Japan)

    2016-06-15

    Gauge coupling unification is studied within the framework where there are extra Higgs doublets and E{sub 6} exotic fields. Supersymmetric models and nonsupersymmetric models are investigated, and a catalog of models with gauge coupling unification is presented. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Precision constraints on extra fermion generations.

    Science.gov (United States)

    Erler, Jens; Langacker, Paul

    2010-07-16

    There has been recent renewed interest in the possibility of additional fermion generations. At the same time there have been significant changes in the relevant electroweak precision constraints, in particular, in the interpretation of several of the low energy experiments. We summarize the various motivations for extra families and analyze them in view of the latest electroweak precision data.

  2. Probing Extra Dimensions with Neutrino Oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Machado, P.A.N. [Instituto de Fisica, Universidade de Sao Paulo, C. P. 66.318, 05315-970 Sao Paulo (Brazil); Nunokawa, H. [Departamento de Fisica, Pontificia Universidade Catolica do Rio de Janeiro, C. P. 38071, 22452-970 Rio de Janeiro (Brazil); Zukanovich Funchal, R., E-mail: zukanov@fma.if.usp.br [Instituto de Fisica, Universidade de Sao Paulo, C. P. 66.318, 05315-970 Sao Paulo (Brazil)

    2011-08-15

    We consider a model where sterile neutrinos can propagate in a large compactified extra dimension (a) giving rise to Kaluza-Klein (KK) modes and the Standard Model left-handed neutrinos are confined to a 4-dimensional spacetime brane. The KK modes mix with the standard neutrinos modifying their oscillation pattern. We examine current experiments in this framework obtaining stringent limits on a.

  3. Extra-oral halitosis : an overview

    NARCIS (Netherlands)

    Tangerman, A.; Winkel, E. G.

    2010-01-01

    Halitosis can be subdivided into intra-oral and extra-oral halitosis, depending on the place where it originates. Most reports now agree that the most frequent sources of halitosis exist within the oral cavity and include bacterial reservoirs such as the dorsum of the tongue, saliva and periodontal

  4. Cystic lesions accompanying extra-axial tumours

    NARCIS (Netherlands)

    Lohle, PNM; Wurzer, HAL; Seelen, PJ; Kingma, LM; Go, KG

    1999-01-01

    We examined the mechanism of cyst formation in extra-axial tumours in the central nervous system (CNS). Cyst fluid, cerebrospinal fluid (CSF) and blood plasma were analysed in eight patients with nine peritumoral cysts: four with meningiomas, two with intracranial and two spinal intradural schwannom

  5. Extra dimensions and violations of Lorentz symmetry

    CERN Document Server

    Overduin, James M

    2016-01-01

    We use experimental limits on Lorentz violation to obtain new constraints on Kaluza-Klein-type theories in which the extra dimensions may be large but do not necessarily have units of length. The associated variation in fundamental quantities such as rest mass must occur slowly, on cosmological scales.

  6. The Night Of Hennessy Paradis Extra Cognac

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    <正>The world-known Hennessy Paradis Extra Cognaclaunched its"dazzling night"on the evening of May 22 tolet guests enjoy to their hearts’content the fine wine andthe charming glamour of the diamond evening dress. A liquid,dating back to the 18th century,was called

  7. A lightweight feedback-controlled microdrive for chronic neural recordings

    Science.gov (United States)

    Jovalekic, A.; Cavé-Lopez, S.; Canopoli, A.; Ondracek, J. M.; Nager, A.; Vyssotski, A. L.; Hahnloser, R. H. R.

    2017-04-01

    Objective. Chronic neural recordings have provided many insights into the relationship between neural activity and behavior. We set out to develop a miniaturized motorized microdrive that allows precise electrode positioning despite possibly unreliable motors. Approach. We designed a feedback-based motor control mechanism. It contains an integrated position readout from an array of magnets and a Hall sensor. Main results. Our extremely lightweight (feedback-based microdrive control requires little extra size and weight, suggesting that such control can be incorporated into more complex multi-electrode designs.

  8. RF feedback for KEKB

    Energy Technology Data Exchange (ETDEWEB)

    Ezura, Eizi; Yoshimoto, Shin-ichi; Akai, Kazunori [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1996-08-01

    This paper describes the present status of the RF feedback development for the KEK B-Factory (KEKB). A preliminary experiment concerning the RF feedback using a parallel comb-filter was performed through a choke-mode cavity and a klystron. The RF feedback has been tested using the beam of the TRISTAN Main Ring, and has proved to be effective in damping the beam instability. (author)

  9. Neural cryptography with feedback

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Shacham, Lanir; Kanter, Ido

    2004-04-01

    Neural cryptography is based on a competition between attractive and repulsive stochastic forces. A feedback mechanism is added to neural cryptography which increases the repulsive forces. Using numerical simulations and an analytic approach, the probability of a successful attack is calculated for different model parameters. Scaling laws are derived which show that feedback improves the security of the system. In addition, a network with feedback generates a pseudorandom bit sequence which can be used to encrypt and decrypt a secret message.

  10. Neural cryptography with feedback.

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Shacham, Lanir; Kanter, Ido

    2004-04-01

    Neural cryptography is based on a competition between attractive and repulsive stochastic forces. A feedback mechanism is added to neural cryptography which increases the repulsive forces. Using numerical simulations and an analytic approach, the probability of a successful attack is calculated for different model parameters. Scaling laws are derived which show that feedback improves the security of the system. In addition, a network with feedback generates a pseudorandom bit sequence which can be used to encrypt and decrypt a secret message.

  11. Strategies for the management of lecturer stress in feedback tutorials

    OpenAIRE

    Hartney, Elizabeth

    2007-01-01

    Abstract The process of providing students with individual feedback on assessed work was identified as a source of lecturer stress (Stough and Emmer, 1998). An action research approach was used to address the following research question. What approaches to providing students with feedback minimize lecturer stress? Data were collected using written feedback mark-sheets and a reflective diary. Findings indicated that negative expectations, student emotion, challenges from students an...

  12. The challenge of giving written thesis feedback to nursing students.

    Science.gov (United States)

    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.

  13. Policy Feedback System (PFS)

    Data.gov (United States)

    Social Security Administration — The Policy Feedback System (PFS) is a web application developed by the Office of Disability Policy Management Information (ODPMI) team that gathers empirical data...

  14. Feedback Loop Gains and Feedback Behavior (1996)

    DEFF Research Database (Denmark)

    Kampmann, Christian Erik

    2012-01-01

    Linking feedback loops and system behavior is part of the foundation of system dynamics, yet the lack of formal tools has so far prevented a systematic application of the concept, except for very simple systems. Having such tools at their disposal would be a great help to analysts in understanding...... large, complicated simulation models. The paper applies tools from graph theory formally linking individual feedback loop strengths to the system eigenvalues. The significance of a link or a loop gain and an eigenvalue can be expressed in the eigenvalue elasticity, i.e., the relative change...... of an eigenvalue resulting from a relative change in the gain. The elasticities of individual links and loops may be found through simple matrix operations on the linearized system. Even though the number of feedback loops can grow rapidly with system size, reaching astronomical proportions even for modest systems...

  15. Personalised feedback and eco-driving : An explorative study

    NARCIS (Netherlands)

    Brouwer, R. F. T.; Stuiver, A.; Hof, T.; Kroon, L.; Pauwelussen, J.; Holleman, B.

    2015-01-01

    Conventional road transport has negative impact on the environment. Stimulating eco-driving through feedback to the driver about his/her energy conservation performance has the potential to reduce CO2 emissions and promote fuel cost savings. Not all drivers respond well to the same type of feedback.

  16. Balancing forward and feedback error correction for erasure channels with unreliable feedback

    CERN Document Server

    Sahai, Anant

    2007-01-01

    The traditional information theoretic approach to studying feedback is to consider ideal instantaneous high-rate feedback of the channel outputs to the encoder. This was acceptable in classical work because the results were negative: Shannon pointed out that even perfect feedback often does not improve capacity and in the context of symmetric DMCs, Dobrushin showed that it does not improve the fixed block-coding error exponents in the interesting high rate regime. However, it has recently been shown that perfect feedback does allow great improvements in the asymptotic tradeoff between end-to-end delay and probability of error, even for symmetric channels at high rate. Since gains are claimed with ideal instantaneous feedback, it is natural to wonder whether these improvements remain if the feedback is unreliable or otherwise limited. Here, packet-erasure channels are considered on both the forward and feedback links. First, the feedback channel is considered as a given and a strategy is given to balance forwa...

  17. Neural Correlates of Feedback Processing in Decision Making under Risk

    Directory of Open Access Journals (Sweden)

    Beate eSchuermann

    2012-07-01

    Full Text Available Introduction. Event-related brain potentials (ERP provide important information about the sensitivity of the brain to process varying risks. The aim of the present study was to determine how different risk levels are reflected in decision-related ERPs, namely the feedback-related negativity (FRN and the P300. Material and Methods. 20 participants conducted a probabilistic two-choice gambling task while an electroencephalogram was recorded. Choices were provided between a low-risk option yielding low rewards and low losses and a high-risk option yielding high rewards and high losses. While options differed in expected risks, they were equal in expected values and in feedback probabilities. Results. At the behavioral level, participants were generally risk-averse but modulated their risk-taking behavior according to reward history. An early positivity (P200 was enhanced on negative feedbacks in high-risk compared to low-risk options. With regard to the FRN, there were significant amplitude differences between positive and negative feedbacks in high-risk options, but not in low-risk options. While the FRN on negative feedbacks did not vary with decision riskiness, reduced amplitudes were found for positive feedbacks in high-risk relative to low-risk choices. P300 amplitudes were larger in high-risk decisions, and in an additive way, after negative compared to positive feedback. Discussion. The present study revealed significant influences of risk and valence processing on ERPs. FRN findings suggest that the reward prediction error signal is increased after high-risk decisions. The increased P200 on negative feedback in risky decisions suggests that large negative prediction errors are processed as early as in the P200 time range. The later P300 amplitude is sensitive to feedback valence as well as to the risk of a decision. Thus, the P300 carries additional information for reward processing, mainly the enhanced motivational significance of risky

  18. Feedback og interpersonel kommunikation

    DEFF Research Database (Denmark)

    Dindler, Camilla

    2016-01-01

    Som interpersonel kommunikationsform handler feedback om at observere, mærke og italesætte det, som handler om relationen mellem samtaleparterne mere end om samtaleemnet. Her er fokus på, hvad der siges og hvordan der kommunikeres sammen. Feedback er her ikke en korrigerende tilbagemelding til...

  19. "Feedback" For Instructioal Television.

    Science.gov (United States)

    Schramm, Wilbur

    A number of different methods have been used by instructional television (ITV) projects to obtain audience feedback, and some of these are now being used in the ITV system in El Salvador. We know that pretesting programs on a representative sample can bring considerable gains in learning. Another feedback source can be a classroom of pupils in the…

  20. Feedback i matematik

    DEFF Research Database (Denmark)

    Sortkær, Bent

    2017-01-01

    Feedback bliver i litteraturen igen og igen fremhævet som et af de mest effektive midler til at fremme elevers præstationer i skolen (Hartberg, Dobson, & Gran, 2012; Hattie & Timperley, 2007; Wiliam, 2015). Dette på trods af, at flere forskere påpeger, at feedback ikke altid er læringsfremmende...... (Hattie & Gan, 2011), og nogle endda viser, at feedback kan have en negativ virkning i forhold til præstationer (Kluger & DeNisi, 1996). Artiklen vil undersøge disse tilsyneladende modstridende resultater ved at stille spørgsmålet: Under hvilke forudsætninger virker feedback i matematik læringsfremmende......? Dette gøres ved at dykke ned i forskningslitteraturen omhandlende feedback ud fra en række temaer for på den måde at besvare ovenstående spørgsmål....

  1. Feedback and Incentives:

    DEFF Research Database (Denmark)

    Eriksson, Tor Viking; Poulsen, Anders; Villeval, Marie-Claire

    This paper experimentally investigates the impact of different pay and relative performance information policies on employee effort. We explore three information policies: No feedback about relative performance, feedback given halfway through the production period, and continuously updated feedback....... The pay schemes are a piece rate payment scheme and a winner-takes-all tournament. We find that, regardless of the pay scheme used, feedback does not improve performance. There are no significant peer effects in the piece-rate pay scheme. In contrast, in the tournament scheme we find some evidence...... of positive peer effects since the underdogs almost never quit the competition even when lagging significantly behind, and frontrunners do not slack off. Moreover, in both pay schemes information feedback reduces the quality of the low performers' work....

  2. Situated Formative Feedback

    DEFF Research Database (Denmark)

    Lukassen, Niels Bech; Wahl, Christian; Sorensen, Elsebeth Korsgaard

    2016-01-01

    feedback episode (FFE) through an online dialogue. The paper argues that dialogue is crucial for student learning and that feedback is not only something the teacher gives to the student. Viewing good quality feedback as social, situated, formative, emphasis is put on the establishment of dialogue. We...... refer to this type of feedback as, Situated Formative Feedback (SFF). As a basis for exploring, identifying and discussing relevant aspects of SFF the paper analyses qualitative data from a Moodle dialogue. Data are embedded in the qualitative analytic program Nvivo and are analysed with a system...... theoretical textual analysis method. Asynchronous written dialogue from an online master’s course at Aalborg University forms the empirical basis of the study. The findings suggests in general that students play an essential role in SFF and that students and educators are equal in the COP, but holds different...

  3. IMPAC OF VOLATILITY EXCHANGE RATES ON INDONESIAN ELECTRONIC IMPORTS FROM INTRA AND EXTRA ASEAN

    Directory of Open Access Journals (Sweden)

    Imam Muklis

    2011-09-01

    Full Text Available This study analyzes the effects of exchange rates volatility and Gross Domestic Product (GDP onelectronic commodity import demand in Indonesia from intra and extra ASEAN. It applies an ErrorCorrection Model along with Dickey-Fuller and Augmented Dickey-Fuller tests. It finds that Indonesianimport demand for electronic commodity is significantly affected by GDP only in the shortrun. It also finds that exchange rates volatility in the short run have a negative effect on import demandfrom intra ASEAN and have a positive effect from extra ASEAN. In the long term, Indonesianimport demand from extra ASEAN is positively affected only by exchange rates volatility.Keywords: Exchange rates volatility, error correction model, gross domestic product, ASEANJEL classification numbers: F14, F31

  4. Extra Fructose in the Growth Medium Fuels Lipogenesis of Adipocytes

    Directory of Open Access Journals (Sweden)

    Armin Robubi

    2014-01-01

    Full Text Available Fructose in excessive amounts exerts negative effects on insulin sensitivity, blood pressure, and liver metabolism. These adverse outcomes were attributed to its disturbances of key metabolic pathways in the liver. Recently, possible consequences of high fructose levels directly on adipocytes in vivo have been considered. We have cultured adipocytes in growth media containing 1 g/L fructose additionally to glucose and monitored the cells fate. Cells developed lipid vesicles much earlier with fructose and showed altered kinetics of the expression of mRNAs involved in lipogenesis and hexose uptake. Adiponectin secretion, too, peaked earlier in fructose containing media than in media with glucose only. From these data it can be speculated that similar effects of fructose containing diets happen in vivo also. Apart from toxic action on liver cells, adipocytes might be stimulated to take up extra fructose and generate new lipid vesicles, further dysregulating energy homeostasis.

  5. Construction Process Control of Large Extra Caissons

    Institute of Scientific and Technical Information of China (English)

    HU Shaowei; WANG Hongxia; FAN Jiansheng

    2005-01-01

    The complexity of geotechnical engineering and variability in construction circumstances of large extra caissons make the problem of maintaining appropriate sink attitude quite difficult, especially in keeping sink uniformity and achieving the expected final sink depth. A new construction control method is presented using (H∞) theory, considering uncertainties in the mechanics model and external noise in the construction site parameters. The design method of an (H∞) controller has consequently been obtained for large extra caissons. Control results using only constructor experiences are compared with simulation results using the (H∞) controller for a practical engineering situation, which indicates that the (H∞) controller is successful in maintaining sink uniformity, avoiding sink as well as in achieving the expected final sink depth.

  6. Brane modeling in warped extra-dimension

    CERN Document Server

    Ahmed, Aqeel

    2012-01-01

    Five-dimensional scenarios with infinitesimally thin branes replaced by appropriate configurations of a scalar field were considered. A possibility of periodic extra dimension was discussed in the presence on non-minimal scalar-gravity coupling and a generalized Gibbons-Kallosh-Linde sum rule was found. In order to avoid constraints imposed by periodicity, a non-compact spacial extra dimension was introduced. A five dimensional model with warped geometry and two thin branes mimicked by a scalar profile was constructed and discussed. In the thin brane limit the model corresponds to a set-up with two positive-tension branes. The presence of two branes allows to address the issue of the hierarchy problem which could be solved by the standard warping of the four dimensional metric. Stability of the background solution was discussed and verified in the presence of the most general perturbations of the metric and the scalar field.

  7. Indirect Collider Signals for Extra Dimensions

    CERN Document Server

    Hewett, J L

    1999-01-01

    A recent suggestion that quantum gravity may become strong near the weak scale has several testable consequences. In addition to probing for the new large (submillimeter) extra dimensions associated with these theories via gravitational experiments, one could search for the Kaluza Klein towers of massive gravitons which are predicted in these models and which can interact with the fields of the Standard Model. Here we examine the indirect effects of these massive gravitons being exchanged in fermion pair production in \\epem\\ annihilation and Drell-Yan production at hadron colliders. In the latter case, we examine a novel feature of this theory, which is the contribution of gluon gluon initiated processes to lepton pair production. We find that these processes provide strong bounds, up to several TeV, on the string scale which are essentially independent of the number of extra dimensions. In addition, we analyze the angular distributions for fermion pair production with spin-2 graviton exchanges and demonstrat...

  8. Extra-dimensional confinement of quantum particles

    CERN Document Server

    Hedin, Eric R

    2016-01-01

    A basic theoretical framework is developed in which elementary particles have a component of their wave function extending into higher spatial dimensions. This model postulates an extension of the Schrodinger equation to include a 4th and 5th spatial component. A higher-dimensional simple harmonic oscillator confining potential localizes particles into 3-d space, characterizing the brane tension which confines Standard Model particles to the sub-manifold. Quantum effects allow a non-zero probability for a particle's evanescent existence in the higher dimensions, and suggest an experimental test for the validity of this model via particles being temporarily excited into the first excited state of the extra-dimensional potential well, in which their probability of existing in 3-d space transiently drops to zero. Several consistency checks of the outcomes of this extra-dimensional model are included in this paper. Among the outcomes of this model are: a match with the quantum phenomenon of zitterbewegung; the pr...

  9. Celulitis por cuerpo extraño

    Directory of Open Access Journals (Sweden)

    Miguel B. Carrasco Guzmán

    2016-01-01

    Full Text Available Las infecciones de la piel y el tejido celular subcutáneo surgen como un grupo importante de afecciones con una alta morbilidad en edades pediátricas, generalmente relacionada con traumatismo y cuerpos extraños. Se presenta el caso de una escolar femenina de 6 años de edad, con síntomas y signos clínicos que sugieren celulitis en el muslo derecho,  por su evolución tórpida se le realizó el estudio ultrasonográfico que confirmó el diagnóstico etiológico de una celulitis secundaria a un traumatismo, provocada por la introducción de un gran cuerpo extraño, que pasó inadvertido para a familia de la menor.

  10. Neutrino anomalies and large extra dimensions

    CERN Document Server

    Dighe, A S; Dighe, Amol S.; Joshipura, Anjan S.

    2001-01-01

    Theories with large extra dimensions can generate small neutrino masses when the standard model neutrinos are coupled to singlet fermions propagating in higher dimensions. The couplings can also generate mass splittings and mixings among the flavour neutrinos in the brane. We systematically study the minimal scenario involving only one singlet bulk fermion coupling weakly to the flavour neutrinos. We explore the neutrino mass structures in the brane that can potentially account for the atmospheric, solar and LSND anomalies simultaneously in a natural way. We demonstrate that in the absence of a priori mixings among the SM neutrinos, it is not possible to reconcile all these anomalies. The presence of some structure in the mass matrix of the SM neutrinos can solve this problem. This is exemplified by the Zee model, which when embedded in extra dimensions in a minimal way can account for all the neutrino anomalies.

  11. Origin of extra chromosome in Patau syndrome.

    Science.gov (United States)

    Ishikiriyama, S; Niikawa, N

    1984-01-01

    Five live-born infants with Patau syndrome were studied for the nondisjunctional origin of the extra chromosome. Transmission modes of chromosomes 13 from parents to a child were determined using both QFQ- and RFA-heteromorphisms as markers, and the origin was ascertained in all of the patients. The extra chromosome had originated in nondisjunction at the maternal first meiotic division in two patients, at the maternal second meiosis in other two, and at the paternal first meiosis in the remaining one. Summarizing the results of the present study, together with those of the previous studies on a liveborn and abortuses with trisomy 13, nondisjunction at the maternal and the paternal meiosis occurred in this trisomy in the ratio of 14:3. This ratio is not statistically different from that inferred from the previous studies for Down syndrome. These findings suggest that there may be a fundamental mechanism common to the occurrence of nondisjunction in the acrocentric trisomies.

  12. Regional feedbacks under changing climate and land-use conditions

    Directory of Open Access Journals (Sweden)

    L. Batlle Bayer

    2012-04-01

    Full Text Available Ecosystem responses to a changing climate and human-induced climate forcings (e.g. deforestation might amplify (positive feedback or dampen (negative feedback the initial climate response. Feedbacks may include the biogeochemical (e.g. carbon cycle and biogeophysical feedbacks (e.g. albedo and hydrological cycle. Here, we first review the most important feedbacks and put them into the context of a conceptual framework, including the major processes and interactions between terrestrial ecosystems and climate. We explore potential regional feedbacks in four hot spots with pronounced potential changes in land-use/management and local climate: sub-Saharan Africa (SSA, Europe, the Amazon Basin and South and Southeast Asia. For each region, the relevant human-induced climate forcings and feedbacks were identified based on published literature.

    When evapotranspiration is limited by a soil water deficit, heat waves in Europe are amplified (positive soil moisture-temperature feedback. Drought events in the Amazon lead to further rainfall reduction when water recycling processes are affected (positive soil moisture-precipitation feedback. In SSA, the adoption of irrigation in the commonly rainfed systems can modulate the negative soil moisture-temperature feedback. In contrast, future water shortage in South and Southeast Asia can turn the negative soil moisture-temperature feedback into a positive one.

    Further research including advanced modeling strategies is needed to isolate the dominant processes affecting the strength and sign of the feedbacks. In addition, the socio-economic dimension needs to be considered in the ecosystems-climate system to include the essential role of human decisions on land-use and land-cover change (LULCC. In this context, enhanced integration between Earth System (ES and Integrated Assessment (IA modeling communities is strongly recommended.

  13. Strategies in probabilistic feedback learning in Parkinson patients OFF medication.

    Science.gov (United States)

    Bellebaum, C; Kobza, S; Ferrea, S; Schnitzler, A; Pollok, B; Südmeyer, M

    2016-04-21

    Studies on classification learning suggested that altered dopamine function in Parkinson's Disease (PD) specifically affects learning from feedback. In patients OFF medication, enhanced learning from negative feedback has been described. This learning bias was not seen in observational learning from feedback, indicating different neural mechanisms for this type of learning. The present study aimed to compare the acquisition of stimulus-response-outcome associations in PD patients OFF medication and healthy control subjects in active and observational learning. 16 PD patients OFF medication and 16 controls were examined with three parallel learning tasks each, two feedback-based (active and observational) and one non-feedback-based paired associates task. No acquisition deficit was seen in the patients for any of the tasks. More detailed analyses on the learning strategies did, however, reveal that the patients showed more lose-shift responses during active feedback learning than controls, and that lose-shift and win-stay responses more strongly determined performance accuracy in patients than controls. For observational feedback learning, the performance of both groups correlated similarly with the performance in non-feedback-based paired associates learning and with the accuracy of observed performance. Also, patients and controls showed comparable evidence of feedback processing in observational learning. In active feedback learning, PD patients use alternative learning strategies than healthy controls. Analyses on observational learning did not yield differences between patients and controls, adding to recent evidence of a differential role of the human striatum in active and observational learning from feedback.

  14. Precision Constraints on Extra Fermion Generations

    CERN Document Server

    Erler, Jens

    2010-01-01

    In the recent past there has been renewed interest in the possibility of additional fermion generations. At the same time there have been significant changes in the relevant electroweak (EW) precision constraints, in particular in the interpretation of several of the low energy experiments. We summarize the various motivations for the increased activity regarding extra families and analyze them in view of the latest EW precision data.

  15. Extra gauge symmetries in BHT gravity

    CERN Document Server

    Blagojević, M

    2011-01-01

    We study the canonical structure of the Bergshoeff-Hohm-Townsend massive gravity, linearized around a maximally symmetric background. At the critical point in the space of parameters, defined by $\\Lambda_0/m^2=-1$, we discover an extra gauge symmetry, which reflects the existence of the partially massless mode. The number of the Lagrangian degrees of freedom is found to be 1. We show that the canonical structure of the theory at the critical point is unstable under linearization.

  16. Extra gauge symmetries in BHT gravity

    Science.gov (United States)

    Blagojević, M.; Cvetković, B.

    2011-03-01

    We study the canonical structure of the Bergshoeff-Hohm-Townsend massive gravity, linearized around a maximally symmetric background. At the critical point in the space of parameters, defined by Λ 0/ m 2 = -1, we discover an extra gauge symmetry, which reflects the existence of the partially massless mode. The number of the Lagrangian degrees of freedom is found to be 1. We show that the canonical structure of the theory at the critical point is unstable under linearization.

  17. Quantum simulation of an extra dimension.

    Science.gov (United States)

    Boada, O; Celi, A; Latorre, J I; Lewenstein, M

    2012-03-30

    We present a general strategy to simulate a D+1-dimensional quantum system using a D-dimensional one. We analyze in detail a feasible implementation of our scheme using optical lattice technology. The simplest nontrivial realization of a fourth dimension corresponds to the creation of a bi-volume geometry. We also propose single- and many-particle experimental signatures to detect the effects of the extra dimension.

  18. Dimensional reduction without continuous extra dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Chamseddine, Ali H. [American University of Beirut, Physics Department, Beirut, Lebanon and I.H.E.S. F-91440 Bures-sur-Yvette (France); Froehlich, J.; Schubnel, B. [ETHZ, Mathematics and Physics Departments, Zuerich (Switzerland); Wyler, D. [Institute of Theoretical Physics, University of Zuerich (Switzerland)

    2013-01-15

    We describe a novel approach to dimensional reduction in classical field theory. Inspired by ideas from noncommutative geometry, we introduce extended algebras of differential forms over space-time, generalized exterior derivatives, and generalized connections associated with the 'geometry' of space-times with discrete extra dimensions. We apply our formalism to theories of gauge- and gravitational fields and find natural geometrical origins for an axion- and a dilaton field, as well as a Higgs field.

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

    Science.gov (United States)

    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…

  20. Collider Implications Of Extra Dimensions At Lhc

    CERN Document Server

    Reema

    2005-01-01

    Scope and method of study. The intent of this research is to consider multiple TeV-1-size extra compact dimensions in an asymmetric string compactification scenario in which the SM gauge bosons can propagate into the TeV-1-size extra dimensions while the SM fermions are confined to the usual SM D3-brane. The contributions that the KK excitations of the gluons, g*'s, make to the multijet cross sections in proton- proton collisions at the LHC energy are calculated. Fortran was used to do the calculations. Findings and conclusions. At very high pT, the dijet signal will either be enhanced significantly due to virtual g* exchanges or place a lower bound on the compactification scale of about 8 TeV. It is found that the dijet signal is very sensitive to three parameters—the compactification scale, the string scale, and the number of extra dimensions. Thus, although the dijet signal is much more sensitive to KK effects, the dijet signal alone does not provide sufficient information to deduce the number of...

  1. MR findings of extra abdominal fibromatosis

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hee Jin; Lee, Sung Moon; Rhee, Chang Soo; Sohn, Chul Ho; Lee, Hee Jung; Kim, Jung Sik; Kim, Hong [Dongsan Medical Center, Keimyung Univ. College of Medicine, Taegu (Korea, Republic of); Seo, Kyung Jin [Suh Joo MRI center, Seoul (Korea, Republic of); Jo, Kil Ho [Youngnam Univ. College of Medicine, Kyongsan (Korea, Republic of)

    1999-12-01

    To evaluate the MR findings of extra-abdominal fibromatosis and the role of MRI in primary diagnosis Fifteen cases in of histologically proven extra-abdominal fibromatosis in 13 patients were retrospectively reviewed. T1-weighted and T2-weighted images were obtained in axial, coronal and sagittal planes. Gd-enhancement was performed in 14 cases, and dynamic enhancement studies in two. All lesions were evaluated for mass shape and margin definition. Among the 15 cases, tumors of the buttock accounted for five, and tumor of the thigh for two. in eight cases tumors were intermuscular and in six cases were intramuscular. In ten cases (67%) the mass extended along the long axis of the body and in 14 of 15 cases (93%) focal infiltration of adjacent structures was visible. The signal intensity of the lesion was in all cases inhomogeneous on both T1 and T2 weighted images. As seen on Gd-DTPA enhanced scans, the masses were inhomogeneously enhanced. In all cases MRI revealed star-shaped linear strands or a band-like low signal area in the mass. These features were not enhanced and were arranged along the long axis of the mass. MR findings of extra-abdominal fibromatosis were relatively characteristic and helpful for primary diagnosis of the condition.

  2. Feedback som tredjeordensiagttagelse

    Directory of Open Access Journals (Sweden)

    Ane Qvortrup

    2013-09-01

    Full Text Available Feedback tilskrives stor betydning for læring, men trods intensiv forskning på området synes det svært at fange, hvori feedbacks særlige potentiale består. I forsøgene på at gøre dette knyttes an til en række faktorer eller parametre, der fremhæves som centrale. En af disse faktorer er tid, hvor der kredses om forskellen mellem umiddelbar og forsinket feedback samt om fordele og ulemper ved hver af de to. I denne artikel knyttes der an til en forståelse af feedback som tredjeordensiagttagelse, og der sættes herfra fokus på, hvordan man i en praktisk undervisningssituation kan imødekomme tidsfaktoren knyttet til feedback. Med udgangspunkt i et undervisningsforløb på bachelorniveau, hvor der er arbejdet systematisk med feedback understøttet af Wikis, belyses det, hvordan et sådant arbejde synes at have potentiale for understøttelse af såvel læring som undervisning. En sådan teoretisk reflekteret belysning kan udgøre et refleksionsprogram for fremtidig planlægning af og løbende refleksion over undervisning.     The article investigates the effect of feedback on learning. Feedback has been shown to be one of the most powerful influences on achievement in education. But, in spite of much research on the matter, there is no agreement on how the special potential of feedback can be described, and consequently no agreement on what is good and bad feedback. This article sets out to rectify this omission by seeking a new theoretical framework that is sensitive to the complexity of the impact of feedback. The author propose a system theoretical frame and through its use identifies significant didactical issues. Although feedback is described as an internal, system-relative construction, when seen through a system theoretical lens different teaching environments create diverse conditions for feedback constructions. The final section of the paper explores this idea in relation to wikis.

  3. Feedback som tredjeordensiagttagelse

    Directory of Open Access Journals (Sweden)

    Ane Qvortrup

    2013-09-01

    Full Text Available Feedback tilskrives stor betydning for læring, men trods intensiv forskning på området synes det svært at fange, hvori feedbacks særlige potentiale består. I forsøgene på at gøre dette knyttes an til en række faktorer eller parametre, der fremhæves som centrale. En af disse faktorer er tid, hvor der kredses om forskellen mellem umiddelbar og forsinket feedback samt om fordele og ulemper ved hver af de to. I denne artikel knyttes der an til en forståelse af feedback som tredjeordensiagttagelse, og der sættes herfra fokus på, hvordan man i en praktisk undervisningssituation kan imødekomme tidsfaktoren knyttet til feedback. Med udgangspunkt i et undervisningsforløb på bachelorniveau, hvor der er arbejdet systematisk med feedback understøttet af Wikis, belyses det, hvordan et sådant arbejde synes at have potentiale for understøttelse af såvel læring som undervisning. En sådan teoretisk reflekteret belysning kan udgøre et refleksionsprogram for fremtidig planlægning af og løbende refleksion over undervisning.  The article investigates the effect of feedback on learning. Feedback has been shown to be one of the most powerful influences on achievement in education. But, in spite of much research on the matter, there is no agreement on how the special potential of feedback can be described, and consequently no agreement on what is good and bad feedback. This article sets out to rectify this omission by seeking a new theoretical framework that is sensitive to the complexity of the impact of feedback. The author propose a system theoretical frame and through its use identifies significant didactical issues. Although feedback is described as an internal, system-relative construction, when seen through a system theoretical lens different teaching environments create diverse conditions for feedback constructions. The final section of the paper explores this idea in relation to wikis.

  4. Online assessment: what influences students to engage with feedback?

    Science.gov (United States)

    Stone, Alan

    2014-07-01

    The intention of giving written feedback is to close the gap between the standard achieved and the standard desired, but students do not always read it. Web-based marking tools are increasingly being used in assessment practices to deliver the feedback. What motivates students to read the feedback provided, especially since the advent of these online marking tools, is poorly understood. This research looked at the factors likely to influence a medical student's engagement with written feedback delivered through an online marking tool (grademark by Turnitin). What motivates students to read the feedback provided Third-year medical students on a UK undergraduate medical course submitted an assignment online. A questionnaire was distributed to a cohort of them following the release of their results and feedback, allowing quantitative and qualitative data collection. Software recorded whether they opened their feedback. Previous examination performance figures were also collated. Online feedback is accessible and acceptable to the majority of students. Personal demographics, computer literacy, previous course performance, or personal motivational drivers did not predict those who did or did not read it. Some students reported seeing little value in feedback because of their previous negative experiences. A minority found feedback hurtful, and were likely to show avoidance behaviours. This research found that feedback provided through an online marking tool overcame many of the problems associated with handwritten feedback, but alone was not enough to ensure universal engagement. Feedback dialogues are proposed as a method to overcome negative student experiences, enhance tutor performance and encourage future student engagement. © 2014 John Wiley & Sons Ltd.

  5. Strategies for effective feedback.

    Science.gov (United States)

    Kritek, Patricia A

    2015-04-01

    Provision of regular feedback to trainees on clinical performance by supervising providers is increasingly recognized as an essential component of undergraduate and graduate health sciences education; however, many individuals have not been formally trained in this pedagogical skill. At the bedside or in the clinic, effective performance feedback can be accomplished by following four key steps. Begin by setting expectations that incorporate the trainee's personal goals and external objectives. Delineate how and when you will provide feedback to the learner. Next, directly observe the trainee's performance. This can be challenging while engaged on a busy clinical service, but a focus on discrete activities or interactions (e.g., family meeting, intravascular volume assessment using bedside ultrasound, or obtaining informed consent) is helpful. The third step is to plan and prioritize the feedback session. Feedback is most effective when given in a timely fashion and delivered in a safe environment. Limit the issues addressed because learners often disengage if confronted with too many deficiencies. Finally, when delivering feedback, begin by listening to the trainee's self-evaluation and then take a balanced approach. Describe in detail what the trainee does well and discuss opportunities for improvement with emphasis on specific, modifiable behaviors. The feedback loop is completed with a plan for follow-up reassessment. Through the use of these relatively simple practices, both the trainee and teacher can have a more productive learning experience.

  6. Gemcitabine resistance in breast cancer cells regulated by PI3K/AKT-mediated cellular proliferation exerts negative feedback via the MEK/MAPK and mTOR pathways

    Directory of Open Access Journals (Sweden)

    Yang XL

    2014-06-01

    ability of 231/Gem cells. Western blot analysis showed that treatment with a PI3K/AKT inhibitor decreased the expression levels of p-AKT, p-MEK, p-mTOR, and p-P70S6K; however, treatments with either MEK/MAPK or mTOR inhibitor significantly increased p-AKT expression. Thus, our data suggest that gemcitabine resistance in breast cancer cells is mainly mediated by activation of the PI3K/AKT signaling pathway. This occurs through elevated expression of p-AKT protein to promote cell proliferation and is negatively regulated by the MEK/MAPK and mTOR pathways. Keywords: chemoresistance, gemcitabine, breast cancer

  7. Semi-global output regulation for linear systems with input saturation by composite nonlinear feedback control

    Science.gov (United States)

    Wang, Chongwen; Yu, Xiao; Lan, Weiyao

    2014-10-01

    To improve transient performance of output response, this paper applies composite nonlinear feedback (CNF) control technique to investigate semi-global output regulation problems for linear systems with input saturation. Based on a linear state feedback control law for a semi-global output regulation problem, a state feedback CNF control law is constructed by adding a nonlinear feedback part. The extra nonlinear feedback part can be applied to improve the transient performance of the closed-loop system. Moreover, an observer is designed to construct an output feedback CNF control law that also solves the semi-global output regulation problem. The sufficient solvability condition of the semi-global output regulation problem by CNF control is the same as that by linear control, but the CNF control technique can improve the transient performance. The effectiveness of the proposed method is illustrated by a disturbance rejection problem of a translational oscillator with rotational actuator system.

  8. Feedback og motivation

    DEFF Research Database (Denmark)

    Bjerresgaard, Helle

    2016-01-01

    Feedback til elever, som enten er gået midlertidigt i stå eller i værste tilfælde oplever sig selv magtesløse, skal hjælpe dem til at etablere en tro på, at de kan øve indflydelse på og være betydningsfulde for deres omgivelser. Feedback sættes ofte i forbindelse med ’læring’. I denne artikel...... påvirket af en målrettet, individuel feedback – eller manglen på samme....

  9. Who Does Extra-Credit Work in Introductory Science Courses?

    Science.gov (United States)

    Moore, Randy

    2005-01-01

    On the first day of classes, 81% of students in an introductory biology course claimed that they would submit extra-credit work if given the opportunity. When given two chances for extra-credit work, fewer than one-fourth of students submitted one or both assignments. Students who submitted extra-credit work were more likely to attend class,…

  10. Random distributed feedback fibre lasers

    Science.gov (United States)

    Turitsyn, Sergei K.; Babin, Sergey A.; Churkin, Dmitry V.; Vatnik, Ilya D.; Nikulin, Maxim; Podivilov, Evgenii V.

    2014-09-01

    The concept of random lasers exploiting multiple scattering of photons in an amplifying disordered medium in order to generate coherent light without a traditional laser resonator has attracted a great deal of attention in recent years. This research area lies at the interface of the fundamental theory of disordered systems and laser science. The idea was originally proposed in the context of astrophysics in the 1960s by V.S. Letokhov, who studied scattering with “negative absorption” of the interstellar molecular clouds. Research on random lasers has since developed into a mature experimental and theoretical field. A simple design of such lasers would be promising for potential applications. However, in traditional random lasers the properties of the output radiation are typically characterized by complex features in the spatial, spectral and time domains, making them less attractive than standard laser systems in terms of practical applications. Recently, an interesting and novel type of one-dimensional random laser that operates in a conventional telecommunication fibre without any pre-designed resonator mirrors-random distributed feedback fibre laser-was demonstrated. The positive feedback required for laser generation in random fibre lasers is provided by the Rayleigh scattering from the inhomogeneities of the refractive index that are naturally present in silica glass. In the proposed laser concept, the randomly backscattered light is amplified through the Raman effect, providing distributed gain over distances up to 100 km. Although an effective reflection due to the Rayleigh scattering is extremely small (˜0.1%), the lasing threshold may be exceeded when a sufficiently large distributed Raman gain is provided. Such a random distributed feedback fibre laser has a number of interesting and attractive features. The fibre waveguide geometry provides transverse confinement, and effectively one-dimensional random distributed feedback leads to the generation

  11. Random distributed feedback fibre lasers

    Energy Technology Data Exchange (ETDEWEB)

    Turitsyn, Sergei K., E-mail: s.k.turitsyn@aston.ac.uk [Aston Institute of Photonic Technologies, Aston University, Birmingham B4 7ET (United Kingdom); Novosibirsk State University, 2 Pirogova str., 630090, Novosibirsk (Russian Federation); Babin, Sergey A. [Novosibirsk State University, 2 Pirogova str., 630090, Novosibirsk (Russian Federation); Institute of Automation and Electrometry SB RAS, 1 Ac. Koptug. ave., 630090, Novosibirsk (Russian Federation); Churkin, Dmitry V. [Aston Institute of Photonic Technologies, Aston University, Birmingham B4 7ET (United Kingdom); Novosibirsk State University, 2 Pirogova str., 630090, Novosibirsk (Russian Federation); Institute of Automation and Electrometry SB RAS, 1 Ac. Koptug. ave., 630090, Novosibirsk (Russian Federation); Vatnik, Ilya D.; Nikulin, Maxim [Institute of Automation and Electrometry SB RAS, 1 Ac. Koptug. ave., 630090, Novosibirsk (Russian Federation); Podivilov, Evgenii V. [Novosibirsk State University, 2 Pirogova str., 630090, Novosibirsk (Russian Federation); Institute of Automation and Electrometry SB RAS, 1 Ac. Koptug. ave., 630090, Novosibirsk (Russian Federation)

    2014-09-10

    The concept of random lasers exploiting multiple scattering of photons in an amplifying disordered medium in order to generate coherent light without a traditional laser resonator has attracted a great deal of attention in recent years. This research area lies at the interface of the fundamental theory of disordered systems and laser science. The idea was originally proposed in the context of astrophysics in the 1960s by V.S. Letokhov, who studied scattering with “negative absorption” of the interstellar molecular clouds. Research on random lasers has since developed into a mature experimental and theoretical field. A simple design of such lasers would be promising for potential applications. However, in traditional random lasers the properties of the output radiation are typically characterized by complex features in the spatial, spectral and time domains, making them less attractive than standard laser systems in terms of practical applications. Recently, an interesting and novel type of one-dimensional random laser that operates in a conventional telecommunication fibre without any pre-designed resonator mirrors–random distributed feedback fibre laser–was demonstrated. The positive feedback required for laser generation in random fibre lasers is provided by the Rayleigh scattering from the inhomogeneities of the refractive index that are naturally present in silica glass. In the proposed laser concept, the randomly backscattered light is amplified through the Raman effect, providing distributed gain over distances up to 100 km. Although an effective reflection due to the Rayleigh scattering is extremely small (∼0.1%), the lasing threshold may be exceeded when a sufficiently large distributed Raman gain is provided. Such a random distributed feedback fibre laser has a number of interesting and attractive features. The fibre waveguide geometry provides transverse confinement, and effectively one-dimensional random distributed feedback leads to the

  12. Influence of qual ity feedback theory on perioperative negative mood in patients with esophageal cancer and rehabilitation effect%质量反馈理论对食管癌病人围术期负性情绪及康复效果的影响

    Institute of Scientific and Technical Information of China (English)

    王明欢; 喻红; 董翠萍

    2014-01-01

    Obj ective:To probe into the influence of quality of feedback theo-ry on perioperative negative mood,postoperative complications and quality of life of patients with esophageal cancer.Methods:A total of 84 cases of e-sophageal cancer patients underwent surgical treatment were randomly di-vided into observation group and control group according to the random number table,42 cases in each.The patients in control group were given routine care,besides that in observation group,the quality feedback theory was used to guide perioperative nursing care.The anxiety self assessment form(SAS),depression self assessment sheet(SDS)and tumor Quality of Life Scale(QOL)were used to evaluate the negative emotion and quality of life of both groups of patients.Results:After intervention the SAS and SDS scores in observation group were lower than that in control group(P<0.05),QOL total score and each dimension scores of quality of life were higher than that in control group (P<0.05 );the incidence of postoperative complications was 16.67% in observation group,40.48% in control group,and the differ-ence was statistically significant (P<0.05 ).Conclusion:Quality feedback theory can effectively improve the perioperative negative emotions of esoph-ageal cancer patients and reduce the incidence of postoperative complications of patients and improve the quality of life of patients after surgery.%[目的]探讨质量反馈理论对食管癌病人围术期负性情绪、术后并发症及生存质量的影响。[方法]将84例行手术治疗的食管癌病人根据随机数字表法随机分为观察组及对照组各42例,对照组术后给予常规护理,观察组在常规性护理基础上应用质量反馈理论指导围术期护理。干预前后应用焦虑自评表(SAS)、抑郁自评表(SDS)及肿瘤生存质量量表(QOL)对两组病人负性情绪及生存质量进行评价。[结果]观察组干预后 SAS、SDS评分低于对照组(P<0.05),QOL 生存质量总评分及各

  13. Students’ expectations of feedback given on draft writing

    Directory of Open Access Journals (Sweden)

    Zach Simpson

    2011-09-01

    Full Text Available Academic writing is the primary means of assessing university students and feedback (oral or written responses on writing can contribute significantly to student learning and success (Ferris, 2003; Hyland & Hyland, 2006. This study explores students’ expectations of feedback on draft writing. The research design was two-pronged. The initial quantitative aspect employed a questionnaire which students completed after receiving feedback from Writing Centre consultants who aim to give developmental feedback. A subsequent phase involved focus groups with volunteer students. This mixed methods design allowed for greater depth of understanding as the qualitative findings extended the quantitative results. The study concludes that students expect feedback to be understandable, encouraging and to focus on both positive and negative aspects of their writing. Importantly, students expect feedback to ‘unpack’ the conventions of academic literacy while still encouraging independence and originality.

  14. NAIP 2015 Imagery Feedback

    Data.gov (United States)

    Farm Service Agency, Department of Agriculture — The NAIP 2015 Imagery Feedback web application allows users to make comments and observations about the quality of the 2015 National Agriculture Imagery Program...

  15. NAIP 2014 Imagery Feedback

    Data.gov (United States)

    Farm Service Agency, Department of Agriculture — The NAIP 2014 Imagery Feedback map allows users to make comments and observations about the quality of the 2014 National Agriculture Imagery Program (NAIP)...

  16. Feedback in analog circuits

    CERN Document Server

    Ochoa, Agustin

    2016-01-01

    This book describes a consistent and direct methodology to the analysis and design of analog circuits with particular application to circuits containing feedback. The analysis and design of circuits containing feedback is generally presented by either following a series of examples where each circuit is simplified through the use of insight or experience (someone else’s), or a complete nodal-matrix analysis generating lots of algebra. Neither of these approaches leads to gaining insight into the design process easily. The author develops a systematic approach to circuit analysis, the Driving Point Impedance and Signal Flow Graphs (DPI/SFG) method that does not require a-priori insight to the circuit being considered and results in factored analysis supporting the design function. This approach enables designers to account fully for loading and the bi-directional nature of elements both in the feedback path and in the amplifier itself, properties many times assumed negligible and ignored. Feedback circuits a...

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

    Science.gov (United States)

    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…

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

    Science.gov (United States)

    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…

  19. Bioaccessibility and antioxidant activity stability of phenolic compounds from extra-virgin olive oils during in vitro digestion.

    Science.gov (United States)

    Dinnella, Caterina; Minichino, Patrizia; D'Andrea, Anna Maria; Monteleone, Erminio

    2007-10-17

    The impact of an in vitro procedure that mimics the physiochemical changes occurring in gastric and small intestinal digestion on the bioaccessibility and antioxidant activity of phenols from 10 extra-virgin olive oil samples was assessed. Extra-virgin olive oil phenols were totally extracted in the aqueous phase, which reproduces gastric fluids during the digestion procedure. A linear bioaccessibility model, based on tyrosol behavior in model oil samples, was used to estimate the bioaccessibility index (BI%) of extra-virgin olive oil phenols. The BI% varied amongst samples from a maximum of 90% to a minimum of 37%, thus indicating that only a fraction of phenols can be considered bioaccessible. The specific antioxidant activity of olive oil phenols proved to be negatively affected by the digestion procedure. By computing a principal component analysis, it was possible to show that differences in the potential bioactive effect of extra-virgin olive oil samples were related to different phenolic profiles.

  20. Negative learning

    Energy Technology Data Exchange (ETDEWEB)

    Oppenheimer, M. [Woodrow Wilson School of Public and International Affairs, Department of Geosciences, Princeton University, Princeton, NJ (United States); O' Neill, B.C. [International Institute for Applied Systems Analysis, Laxenburg (Austria)]|[Institute for the Study of Society and Environment, National Center for Atmospheric Research, Boulder, CO (United States); Webster M. [MIT Joint Program on the Science and Policy of Global Change, Massachusetts Institute of Technology, Cambridge, MA (United States)

    2008-07-15

    New technical information may lead to scientific beliefs that diverge over time from the a posteriori right answer. We call this phenomenon, which is particularly problematic in the global change arena, negative learning. Negative learning may have affected policy in important cases, including stratospheric ozone depletion, dynamics of the West Antarctic ice sheet, and population and energy projections. We simulate negative learning in the context of climate change with a formal model that embeds the concept within the Bayesian framework, illustrating that it may lead to errant decisions and large welfare losses to society. Based on these cases, we suggest approaches to scientific assessment and decision making that could mitigate the problem. Application of the tools of science history to the study of learning in global change, including critical examination of the assessment process to understand how judgments are made, could provide important insights on how to improve the flow of information to policy makers.

  1. Feedback and rewards, part II: formal and informal feedback reviews.

    Science.gov (United States)

    Harolds, Jay

    2013-02-01

    There are 2 major classes of feedback. One class of feedback consists of the informal, numerous conversations between various people in the organization regarding the performance, behavior, and goals of an individual. Another class of feedback consists of formal reviews held once or twice a year between a supervisor and an individual. This article discusses both types of feedback.

  2. Extra-adrenal Pheochromocytoma in an Adolescent

    Directory of Open Access Journals (Sweden)

    Abdullah, Ibrahim

    2011-05-01

    Full Text Available A 17-year-old male with symptoms of headache and diaphoresis presented to the emergency department. He had eight months of noted hypertension attributed to medications. On arrival his blood pressure was 229/117mmHg, and he was ill-appearing. His blood pressure was managed aggressively, and he was diagnosed with extra-adrenal pheochromocytoma by computed tomography. He eventually underwent resection of the mass. Children with severe, symptomatic hypertension should be evaluated for pheochromocytoma. Although rare, it is curable. Failure to diagnose carries a high risk of morbidity and mortality. [West J Emerg Med. 2011;12(2:258-261.

  3. Aneurisma micotico de origem extra-vascular

    Directory of Open Access Journals (Sweden)

    Nelson Pires Ferreira

    1976-12-01

    Full Text Available É relatado o caso de uma paciente com três anos de idade portadora de oftalmoplegia completa unilateral e aneurisma da artéria carótida interna, em sua porção intra-cavernosa. A etiologia infecciosa extra-vascular, na vigência de tromboflebite de seio cavernoso, foi considerada. As informações da literatura são discutidas, sendo comentada a infrequência da patologia. A indicação de ligadura da artéria carótida interna, no tratamento desses aneurismas, merece ulterior comprovação.

  4. Enhanced gravitational scattering from large extra dimensions

    CERN Document Server

    Koyama, K; Wands, D; Koyama, Kazuya; Piazza, Federico; Wands, David

    2005-01-01

    We show that enhanced gravitational scattering on small scales (< 0.1 mm), which becomes possible in models with large extra dimensions, can establish statistical equilibrium between different particle species in the early Universe. Ultra-light WIMPs (e.g., axions) can be thermalized by such a mechanism and therefore are not viable CDM candidates in models with a fundamental Planck scale below about 10 TeV. More generally we note that the energy transfer rate is sensitive to trans-Planckian physics

  5. Radio communications with extra-terrestrial civilizations

    Science.gov (United States)

    Kotelnikov, V. A.

    1974-01-01

    Communications between civilizations within our galaxy at the present level of radio engineering is possible, although civilizations must begin to search for each other to achieve this. If an extra-terrestrial civilization possessing a technology at our level wishes to make itself known and will transmit special radio signals to do this, then it can be picked up by us at a distance of several hundreds of light years using already existing radio telescopes and specially built radio receivers. If it wishes, this civilization can also send us information without awaiting our answer.

  6. Dynamic aspects of the tubuloglomerular feedback mechanism

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H

    1992-01-01

    unlikely, it cannot be excluded that a vascular pacemaker is involved in the underlying oscillatory mechanism. To test the hypothesis that the oscillations are caused by the TGF system, a series of dynamic mathematical models of the TGF system have been developed.(ABSTRACT TRUNCATED AT 400 WORDS)......Tubuloglomerular feedback (TGF) is an important intrarenal regulatory mechanism, which acts to stabilize renal blood flow, GFR, and the tubular flow rate. The anatomical basis for this negative feedback system is the Juxtaglomerular Apparatus (JGA). This is located at the point of contact between...... the thick ascending limb of the loop of Henle (TAL) and the vascular pole of the glomerulus. The JGA includes the macula densa, a specialized plaque of cells in the TAL thought to be responsible for the sensing step in the feedback mechanism; the mesangial cells, a cushion of cells separating the macula...

  7. Training Metacognition in the Classroom: The Influence of Incentives and Feedback on Exam Predictions

    Science.gov (United States)

    Miller, Tyler M.; Geraci, Lisa

    2011-01-01

    In two semester-long studies, we examined whether college students could improve their ability to accurately predict their own exam performance across multiple exams. We tested whether providing concrete feedback and incentives (i.e., extra credit) for accuracy would improve predictions by improving students' metacognition, or awareness of their…

  8. Does use of the CPREzy involve more work than CPR without feedback?

    NARCIS (Netherlands)

    Berkom, P.F. van; Noordergraaf, G.J.; Scheffer, G.J.; Noordergraaf, A.

    2008-01-01

    AIM: Feedback during CPR may facilitate quality in chest compressions, but has also been associated with caregiver complaints such as stiff wrists, the need for more force and increased fatigue. This concern about extra work is, when using the CPREzy with its own spring-loaded surface, particularly

  9. Does use of the CPREzy involve more work than CPR without feedback?

    NARCIS (Netherlands)

    Berkom, P.F. van; Noordergraaf, G.J.; Scheffer, G.J.; Noordergraaf, A.

    2008-01-01

    AIM: Feedback during CPR may facilitate quality in chest compressions, but has also been associated with caregiver complaints such as stiff wrists, the need for more force and increased fatigue. This concern about extra work is, when using the CPREzy with its own spring-loaded surface, particularly

  10. Negative Certainty

    Science.gov (United States)

    Ariso, José María

    2017-01-01

    The definitions of "negative knowledge" and the studies in this regard published to date have not considered the categorial distinction Wittgenstein established between knowledge and certainty. Hence, the important role that certainty, despite its omission, should have in these definitions and studies has not yet been shown. In this…

  11. Negative Numbers

    Science.gov (United States)

    Galbraith, Mary J.

    1974-01-01

    Examination of models for representing integers demonstrates that formal operational thought is required for establishing the operations on integers. Advocated is the use of many models for introducing negative numbers but, apart from addition, it is recommended that operations on integers be delayed until the formal operations stage. (JP)

  12. Negative Certainty

    Science.gov (United States)

    Ariso, José María

    2017-01-01

    The definitions of "negative knowledge" and the studies in this regard published to date have not considered the categorial distinction Wittgenstein established between knowledge and certainty. Hence, the important role that certainty, despite its omission, should have in these definitions and studies has not yet been shown. In this…

  13. Feedback and rewards, Part I: Introduction to effective feedback.

    Science.gov (United States)

    Harolds, Jay A

    2013-01-01

    This series of articles discusses conversations regarding feedback. Feedback can include input from numerous sources, including one's supervisor, peers, subordinates, suppliers, customers, patients, and/or society members. Effective feedback is very important to the operation of any organization and to the growth of the individual. However, feedback done poorly does not appear to be rare and can be highly destructive to all. A variety of tips on how to do feedback well are included in this article.

  14. Tropical cirrus and water vapor: an effective Earth infrared iris feedback?

    Directory of Open Access Journals (Sweden)

    Q. Fu

    2001-09-01

    Full Text Available We revisit a model of feedback processes proposed by Lindzen et al. (2001, in which an assumed 22% reduction in the area of tropical high clouds per degree of sea surface temperature increase produces negative feedbacks associated with upper tropospheric water vapor and cloud radiative effects. We argue that the water vapor feedback is overestimated in Lindzen et al. (2001 by at least 60%, and that the high cloud feedback should be small. Although not mentioned by Lindzen et al, tropical low clouds make a significant contribution to their negative feedback, which is also overestimated. Using more realistic parameters in the model of Lindzen et al., we obtain a feedback factor in the range of −0.15 to −0.51, compared to their larger negative feedback factor of −0.45 to −1.03.

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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...

  17. Lipase production by yeasts from extra virgin olive oil.

    Science.gov (United States)

    Ciafardini, G; Zullo, B A; Iride, A

    2006-02-01

    Newly produced olive oil has an opalescent appearance due to the presence of solid particles and micro-drops of vegetation water from the fruits. Some of our recent microbiological research has shown that a rich micro-flora is present in the suspended fraction of the freshly produced olive oil capable of improving the quality of the oil through the hydrolysis of the oleuropein. Present research however has, for the first time, demonstrated the presence of lipase-positive yeasts in some samples of extra virgin olive oil which can lower the quality of the oil through the hydrolysis of the triglycerides. The tests performed with yeasts of our collection, previously isolated from olive oil, demonstrated that two lipase-producing yeast strains named Saccharomyces cerevisiae 1525 and Williopsis californica 1639 were able to hydrolyse different specific synthetic substrates represented by p-nitrophenyl stearate, 4-nitrophenyl palmitate, tripalmitin and triolein as well as olive oil triglycerides. The lipase activity in S. cerevisiae 1525 was confined to the whole cells, whereas in W. californica 1639 it was also detected in the extracellular fraction. The enzyme activity in both yeasts was influenced by the ratio of the aqueous to the organic phase reaching its maximum value in S. cerevisiae 1525 when the water added to the olive oil was present in a ratio of 0.25% (v/v), whereas in W. californica 1639 the optimal ratio was 1% (v/v). Furthermore, the free fatty acids of olive oil proved to be good inducers of lipase activity in both yeasts. The microbiological analysis carried out on commercial extra virgin olive oil, produced in four different geographic areas, demonstrated that the presence of lipase-producing yeast varied from zero to 56% of the total yeasts detected, according to the source of oil samples. The discovery of lipase-positive yeasts in some extra virgin olive oils leads us to believe that yeasts are able to contribute in a positive or negative way towards

  18. Digital Realization of Capacitor-Voltage Feedback Active Damping for LCL-Filtered Grid Converters

    DEFF Research Database (Denmark)

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang

    2015-01-01

    The capacitor voltage of an LCL-filter can also be used for active damping, if it is fed back for synchronization. By this way, an extra current sensor can be avoided. Compared with the existing active damping techniques designed with capacitor current feedback, the capacitor voltage feedback....... To overcome their drawbacks, a new derivative method is then proposed, based on the non-ideal generalized integrator. The performance of the proposed derivative has been found to match the ideal “s” function closely. Active damping based on capacitor voltage feedback can therefore be realized accurately...

  19. Extra-mammary findings in breast MRI

    Energy Technology Data Exchange (ETDEWEB)

    Rinaldi, Pierluigi; Costantini, M.; Belli, P.; Giuliani, M.; Bufi, E.; Fubelli, R.; Distefano, D.; Romani, M.; Bonomo, L. [Catholic University - Policlinic A. Gemelli, Department of Bio-Imaging and Radiological Sciences, Rome (Italy)

    2011-11-15

    Incidental extra-mammary findings in breast Magnetic Resonance Imaging (MRI) may be benign in nature, but may also represent a metastasis or another important lesion. We aimed to analyse the prevalence and clinical relevance of these unexpected findings. A retrospective review of 1535 breast MRIs was conducted. Only axial sequences were reassessed. Confirmation examinations were obtained in all cases. 285 patients had a confirmed incidental finding, which were located in the liver (51.9%), lung (11.2%), bone (7%), mediastinal lymph nodes (4.2%) or consisted of pleural/pericardial effusion (15.4%). 20.4% of incidental findings were confirmed to be malignant. Positive predictive value for MRI to detect a metastatic lesion was high if located within the bone (89%), lymph nodes (83%) and lung (59%), while it was low if located within the liver (9%) or if it consisted of pleural/pericardial effusion (6%). The axial enhanced sequence showed superior sensitivity to unenhanced images in detecting metastatic lesions, especially if only smaller ({<=}10 mm.) lesions were considered. The prevalence of metastatic incidental extra-mammary findings is not negligible. Particular attention should be to incidental findings located within the lung, bone and mediastinal lymph nodes. (orig.)

  20. Neutrino Mass Models in Extra Dimensions

    CERN Document Server

    Ng, J N

    2003-01-01

    Neutrinos play a crucial role in many areas of physics from very short distances to astrophysics and cosmology. It is a long held believe that they are good probes of physics at the GUT scale. Recent developments have made it clear that they can also be of fundamental importance for the physics of extra dimensions if these exist. Here we pedagogically review the construction of neutrino mass models in extra dimensions within the brane world scenarios. These models are usually nontrivial generalizations of their four dimensional counterparts. We describe the theoretical tools that have been forged and the new perpectives gained in this rapidly developing area. In particular we discuss the issues involve in building models without the use of right-handed singlets. It is very difficult to directly test the origin of neutrino masses in different models be it in four or more dimensions. We point out that different models give very different indirect signatures in the TeV region and in precision measurements.

  1. Neptune migration model with one extra planet

    CERN Document Server

    Yeh, Lun-Wen; 10.1016/j.icarus.2009.06.008

    2009-01-01

    We explore conventional Neptune migration model with one additional planet of mass at 0.1-2.0 Me. This planet inhabited in the 3:2 mean motion resonance with Neptune during planet migration epoch, and then escaped from the Kuiper belt when Jovian planets parked near the present orbits. Adding this extra planet and assuming the primordial disk truncated at about 45 AU in the conventional Neptune migration model, it is able to explain the complex structure of the observed Kuiper belt better than the usual Neptune migration model did in several respects. However, numerical experiments imply that this model is a low-probability event. In addition to the low probability, two features produced by this model may be inconsistent with the observations. They are small number of low-inclination particles in the classical belt, and the production of a remnant population with near-circular and low-inclination orbit within a = 50-52 AU. According to our present study, including one extra planet in the conventional Neptune ...

  2. Exploring extra dimensions with scalar waves

    CERN Document Server

    Jones-Smith, Katherine; Verostek, Michael

    2016-01-01

    This paper provides a pedagogical introduction to the physics of extra dimensions focussing on the ADD, Randall-Sundrum and DGP models. In each of these models, the familiar particles and fields of the standard model are assumed to be confined to a four dimensional space-time called the brane; the brane is a slice through a higher dimensional space-time called the bulk. The geometry of the ADD, Randall-Sundrum and DGP space-times is described and the relation between Randall-Sundrum and Anti-de-Sitter space-time is explained. The necessary differential geometry background is introduced in an appendix that presumes no greater mathematical preparation than multivariable calculus. The ordinary wave equation and the Klein-Gordon equation are briefly reviewed followed by an analysis of the propagation of scalar waves in the bulk in all three extra-dimensional models. We also calculate the scalar field produced by a static point source located on the brane for all three models. For the ADD and Randall-Sundrum model...

  3. Dynamical Electroweak Symmetry Breaking from Extra Dimensions

    CERN Document Server

    Hashimoto, M; Yamawaki, K; Hashimoto, Michio; Tanabashi, Masaharu; Yamawaki, Koichi

    2003-01-01

    We study the dynamical electroweak symmetry breaking (DEWSB) in the $D (=6,8,...)$-dimensional bulk with compactified extra dimensions. We identify the critical binding strength for triggering the DEWSB, based on the ladder Schwinger-Dyson equation. In the top mode standard model with extra dimensions, where the standard model gauge bosons and the third generation of quarks and leptons are put in the bulk, we analyze the most attractive channel (MAC) by using renormalization group equations (RGEs) of (dimensionless) bulk gauge couplings and determine the effective cutoff where the MAC coupling exceeds the critical value. We then find that the top-condensation can take place for D=8. Combining RGEs of top-Yukawa and Higgs-quartic couplings with compositeness conditions, we predict the top mass, $m_t=173-180$ GeV, and the Higgs mass, $m_H=181-211$ GeV, for D=8, where we took the universal compactification scale $1/R = 1-100$ TeV.

  4. Dynamical Electroweak Symmetry Breaking from Extra Dimensions

    Science.gov (United States)

    Hashimoto, Michio; Tanabashi, Masaharu; Yamawaki, Koichi

    2003-08-01

    We study the dynamical electroweak symmetry breaking (DEWSB) in the D(= 6, 8, ⋯)-dimensional bulk with compactified extra dimensions. We identify the critical binding strength for triggering the DEWSB, based on the ladder Schwinger-Dyson equation. In the top mode standard model with extra dimensions, where the standard model gauge bosons and the third generation of quarks and leptons are put in the bulk, we analyze the most attractive channel (MAC) by using renormalization group equations (RGEs) of (dimensionless) bulk gauge couplings and determine the effective cutoff where the MAC coupling exceeds the critical value. We then find that the top-condensation can take place for D = 8. Combining RGEs of top-Yukawa and Higgs-quartic couplings with compositeness conditions, we predict the top mass, mt = 173 - 180 GeV, and the Higgs mass, mH = 181 - 211 GeV, for D = 8, where we took the universal compactification scale 1/R = 1 - 100 TeV.

  5. Extra-Galactic Diffuse Interstellar Bands

    Science.gov (United States)

    Cox, N.; Ehrenfreund, Pascale; Kaper, Lex; Spaans, Marco; Foing, Bernard

    Diffuse Interstellar Bands (DIBs) have been observed ubiquitously along many sight-lines probing the interstellar medium of the Milky Way. Despite extensive efforts, their carrier(s) have not yet been identified, although they are very likely of a carbonaceous nature and reside in the gas phase. Possible candidates include, but are not limited to, polycyclic aromatic hydro- carbons (PAHs), fullerenes and carbon chains. To advance our understanding of DIB behaviour and thus DIB carrier properties we need to study environments inherently different from those observed in the Milky Way. Only recent advances in instrumentation and telescope capabilities are providing us with new exciting possibilities for extra-galactic DIB research. We present here a selection of our recent observational results for (extra)-galactic DIBs in the Local Group and beyond. In particular, DIBs in the Magellanic Clouds and in the spiral galaxy NGC1448. These first results show surprising similarities between certain DIB profiles as well as differences in DIB behaviour. Understanding diffuse cloud chemistry, in particular with respect to complex (carbonaceous) molecules, is crucial to any DIB carrier identification. In this respect, external galaxies offer a unique window as they exhibit local interstellar conditions (such as metallicity, UV-field and gas-to-dust ratio) very different from those observed in the Milky Way. We discuss briefly the effect of metallicity and the gas-to-dust ratio on the physi-chemical properties of diffuse clouds and the subsequent effects on the PAH charge state distribution and the DIB carriers.

  6. [Extra-articular manifestations of seronegative spondylarthritis].

    Science.gov (United States)

    Cammelli, Daniele

    2006-05-01

    Seronegative spondylarthritis are frequently characterised by extra-articular manifestations. They are frequently in recurrent uveitis. Between the cutaneous manifestations should be mentioned erythema nodosum, typical of inflammatory bowel diseases, and keratoderma blenorrhagicum, in the Reiter's syndrome. Cardiac complications in ankylosing spondylitis (AS) include aortic valvular regurgitation and arrhythmia and, more rarely, mitral valvulopathy, cardiomyopathy and pericarditis. Pulmonary involvement in AS includes ventilatory restrictive syndrome and fibro-bullous disease of the apex. Vertebral osteoporosis is a very important extra-articular manifestation because of the possibility of spontaneous fractures of the vertebrae. Central neurological manifestations include medullary compression from cervical sub-luxation while the most important peripheral involvements are lumbar stenosis and the cauda equina syndrome. Type AA amyloidosis is a rare late complication of the AS, possible cause of death especially in patients with aggressive disease. Kidney complications can be observed as consequences of prolonged anti-inflammatory therapy, but the most frequent renal complications are amyloidosis and mesangial IgA segmental and focal glomerulonephritis.

  7. Gauge symmetries emerging from extra dimensions

    Science.gov (United States)

    Chkareuli, J. L.; Kepuladze, Z.

    2016-09-01

    We argue that extra dimensions with a properly chosen compactification scheme could be a natural source for emergent gauge symmetries. Actually, some proposed vector field potential terms or polynomial vector field constraints introduced in five-dimensional Abelian and non-Abelian gauge theory are shown to smoothly lead to spontaneous violation of an underlying 5D spacetime symmetry and generate pseudo-Goldstone vector modes as conventional 4D gauge boson candidates. As a special signature, there appear, apart from conventional gauge couplings, some properly suppressed direct multiphoton (multiboson, in general) interactions in emergent QED and Yang-Mills theories whose observation could shed light on their high-dimensional nature. Moreover, in emergent Yang-Mills theories an internal symmetry G also occurs spontaneously broken to its diagonal subgroups once 5D Lorentz violation happens. This breaking originates from the extra vector field components playing a role of some adjoint scalar field multiplet in the 4D spacetime. So, one naturally has the Higgs effect without a specially introduced scalar field multiplet. Remarkably, when being applied to grand unified theories (GUTs) this results in a fact that the emergent GUTs generically appear broken down to the Standard Model just at the 5D Lorentz violation scale M .

  8. The Universe’s extra bits

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Parallel universes, unknown forms of matter, extra dimensions….This is not cheap science fiction but very concrete physics theories that the scientists are trying to confirm with the LHC and other ongoing experiments. Although it's enough to make us dream about going to a parallel world for the weekend, let’s keep our feet firmly on the ground and try to work out what all these things really are…   Given the astonishing fact that 96% of the Universe is actually unknown, we can think of filling it with all sorts of weird and exotic things. Extra dimensions and parallel universes may indeed be real, that is, their existence is accepted by a large community of scientists who have worked out mathematical models and physical constraints. “The idea of a fifth dimension was first introduced by Kaluza and Klein at the beginning of the last century in an attempt to unify gravity and electromagnetism”, confirms Ignatios Antoniadis from CERN’s Th...

  9. Feedback: Now with Physics

    Science.gov (United States)

    Hopkins, Philip F.; Quataert, Eliot; Faucher-Giguere, Claude-Andre; Keres, Dusan; Wetzel, Andrew R.; Murray, Norman W.

    2017-01-01

    The most fundamental unsolved problems in galaxy formation revolve around "feedback" from massive stars and black holes. In the last few years, a new generation of theoretical models have emerged which combine new numerical methods and physics in an attempt to realistically model the diverse physics of the interstellar medium, star formation, and feedback from super-massive black holes and massive stars (winds, jets, SNe, and radiation). These mechanisms lead to 'self-regulated' galaxy and star formation, in which global correlations such as the Schmidt-Kennicutt law, the inefficiency of star formation, and the stellar mass function -- emerge naturally. Within galaxies, feedback regulates the structure of the interstellar medium, and many observed properties of the ISM, star formation, and galaxies can be understood as a fundamental consequence of super-sonic turbulence in a rapidly cooling, self-gravitating medium. But feedback also produces galactic super-winds that can dramatically alter the cosmological evolution of galaxies, change the nature of dark matter cores and ‘cusps’, and re-structure the circum-galactic and inter-galactic medium. These winds depend non-linearly on multiple feedback mechanisms in a way that explains why they have been so difficult to model in previous "sub-grid" approaches. This resolves long-standing problems in understanding even apparently "simple" galaxy properties like the mass-metallicity relation. Finally, I'll discuss where feedback fails, and where either additional, exotic physics, or new, previously-dismissed feedback mechanisms, may be needed to explain observations.

  10. Feedback control of quantum system

    Institute of Scientific and Technical Information of China (English)

    DONG Dao-yi; CHEN Zong-hai; ZHANG Chen-bin; CHEN Chun-lin

    2006-01-01

    Feedback is a significant strategy for the control of quantum system.Information acquisition is the greatest difficulty in quantum feedback applications.After discussing several basic methods for information acquisition,we review three kinds of quantum feedback control strategies:quantum feedback control with measurement,coherent quantum feedback,and quantum feedback control based on cloning and recognition.The first feedback strategy can effectively acquire information,but it destroys the coherence in feedback loop.On the contrary,coherent quantum feedback does not destroy the coherence,but the capability of information acquisition is limited.However,the third feedback scheme gives a compromise between information acquisition and measurement disturbance.

  11. The influence of teacher feedback on children's perceptions of student-teacher relationships.

    OpenAIRE

    Skipper, Y; Douglas, K

    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 effects of person, process, and no feedback on children's perceptions of their relationship with a (fictional) teacher following success and failure. SAMPLES: Participant...

  12. Simple models of assortment through environmental feedback.

    Science.gov (United States)

    Pepper, John W

    2007-01-01

    Social evolution depends critically on assortment, or segregation versus even mixing, between cooperators and noncooperators. Altruistic traits, which reduce the absolute fitness of their bearers, cannot evolve without positive assortment (excess segregation). The question of how positive assortment can arise has been controversial, but most evolutionary biologists believe that common descent is the only effective general mechanism. Here I investigate another recently proposed mechanism for generating nonrandom assortment, termed environmental feedback. This requires only that two forms of a trait affect the quality of the local environment differently in such a way that all individuals are more likely to leave low-quality locales. Experiments with simple computational models confirm that environmental feedback generates significant levels of genetic similarity among non-kin within locales. The mechanism is fairly general, and can under some conditions produce levels of genetic similarity comparable to those resulting from close genealogical relationship. Environmental feedback can also generate the negative assortment necessary for the evolution of spiteful traits. Environmental feedback is expected to create positive frequency-dependent selection, which thus favor any social trait that becomes common in the population. Results from this stylized model suggest that environmental feedback could be important in the evolution of both cooperation and spite, within as well as between species.

  13. Global climate feedbacks

    Energy Technology Data Exchange (ETDEWEB)

    Manowitz, B.

    1990-10-01

    The important physical, chemical, and biological events that affect global climate change occur on a mesoscale -- requiring high spatial resolution for their analysis. The Department of Energy has formulated two major initiatives under the US Global Change Program: ARM (Atmospheric Radiation Measurements), and CHAMMP (Computer Hardware Advanced Mathematics and Model Physics). ARM is designed to use ground and air-craft based observations to document profiles of atmospheric composition, clouds, and radiative fluxes. With research and models of important physical processes, ARM will delineate the relationships between trace gases, aerosol and cloud structure, and radiative transfer in the atmosphere, and will improve the parameterization of global circulation models. The present GCMs do not model important feedbacks, including those from clouds, oceans, and land processes. The purpose of this workshop is to identify such potential feedbacks, to evaluate the uncertainties in the feedback processes (and, if possible, to parameterize the feedback processes so that they can be treated in a GCM), and to recommend research programs that will reduce the uncertainties in important feedback processes. Individual reports are processed separately for the data bases.

  14. Gender differences in reward and punishment for monetary and social feedback in children: An ERP study

    Science.gov (United States)

    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

  15. TUNE FEEDBACK AT RHIC

    Energy Technology Data Exchange (ETDEWEB)

    CAMERON,P.; CERNIGLIA,P.; CONNOLLY,R.; CUPOLO,J.; DAWSON,W.C.; DEGEN,C.; DELLAPENNA,A.; DELONG,J.; DREES,A.; HUHN,A.; KESSELMAN,M.; MARUSIC,A.; OERTER,B.; MEAD,J.; SCHULTHEISS,C.; SIKORA,R.; VAN ZEIJTS,J.

    2001-06-18

    Preliminary phase-locked loop betatron tune measurement results were obtained during RHIC 2000 with a resonant Beam Position Monitor. These results suggested the possibility of incorporating PLL tune measurement into a tune feedback system for RHIC 2001. Tune feedback is useful in a superconducting accelerator, where the machine cycle time is long and inefficient acceleration due to resonance crossing is not comfortably tolerated. This is particularly true with the higher beam intensities planned for RHIC 2001. We present descriptions of a PLL tune measurement system implemented in the DSP/FPGA environment of a RHIC BPM electronics module and the feedback system into which the measurement is incorporated to regulate tune. In addition, we present results from the commissioning of this system during RHIC 2001.

  16. Climate forcings and feedbacks

    Science.gov (United States)

    Hansen, James

    1993-01-01

    Global temperature has increased significantly during the past century. Understanding the causes of observed global temperature change is impossible in the absence of adequate monitoring of changes in global climate forcings and radiative feedbacks. Climate forcings are changes imposed on the planet's energy balance, such as change of incoming sunlight or a human-induced change of surface properties due to deforestation. Radiative feedbacks are radiative changes induced by climate change, such as alteration of cloud properties or the extent of sea ice. Monitoring of global climate forcings and feedbacks, if sufficiently precise and long-term, can provide a very strong constraint on interpretation of observed temperature change. Such monitoring is essential to eliminate uncertainties about the relative importance of various climate change mechanisms including tropospheric sulfate aerosols from burning of coal and oil smoke from slash and burn agriculture, changes of solar irradiance changes of several greenhouse gases, and many other mechanisms. The considerable variability of observed temperature, together with evidence that a substantial portion of this variability is unforced indicates that observations of climate forcings and feedbacks must be continued for decades. Since the climate system responds to the time integral of the forcing, a further requirement is that the observations be carried out continuously. However, precise observations of forcings and feedbacks will also be able to provide valuable conclusions on shorter time scales. For example, knowledge of the climate forcing by increasing CFC's relative to the forcing by changing ozone is important to policymakers, as is information on the forcing by CO2 relative to the forcing by sulfate aerosols. It will also be possible to obtain valuable tests of climate models on short time scales, if there is precise monitoring of all forcings and feedbacks during and after events such as a large volcanic eruption

  17. Higgs Phenomenology of Minimal Universal Extra Dimensions

    Directory of Open Access Journals (Sweden)

    Kakizaki Mitsuru

    2012-06-01

    Full Text Available The minimal model of Universal Extra Dimensions (MUED is briefly reviewed. We explain how the cross-sections for Higgs production via gluon fusion and decay into photons are modified, relative the the Standard Model (SM values, by KK particles running in loops, leading to an enhancement of the gg → h → γγ and gg → h → W+W− cross-sections. ATLAS and CMS searches for the SM Higgs in these channels are reinterpreted in the context of MUED and used to place new limits on the MUED parameter space. Only a small region of between 1 and 3 GeV around mh = 125 GeV for 500 GeV < R−1 < 1600 GeV remains open at the 95 % confidence level.

  18. Celulitis por cuerpo extraño

    OpenAIRE

    2016-01-01

    Las infecciones de la piel y el tejido celular subcutáneo surgen como un grupo importante de afecciones con una alta morbilidad en edades pediátricas, generalmente relacionada con traumatismo y cuerpos extraños. Se presenta el caso de una escolar femenina de 6 años de edad, con síntomas y signos clínicos que sugieren celulitis en el muslo derecho,  por su evolución tórpida se le realizó el estudio ultrasonográfico que confirmó el diagnóstico etiológico de una celulitis secundaria a un traumat...

  19. Black holes, cosmology and extra dimensions

    CERN Document Server

    Bronnikov, Kirill A

    2013-01-01

    Assuming foundational knowledge of special and general relativity, this book guides the reader on issues surrounding black holes, wormholes, cosmology, and extra dimensions. Its first part is devoted to local strong field configurations (black holes and wormholes) in general relativity and the most relevant of alternative theories: scalar-tensor, f(R) and multidimensional theories. The second part is on cosmology, including inflation and a unified description of the whole evolution of the universe. The third part concerns multidimensional theories of gravity and contains a number of original results obtained by the authors. Expository work is conducted for a mechanism of symmetries and fundamental constants formation, while the original approach to nonlinear multidimensional gravity that is able to construct a unique perspective describing different phenomena is highlighted. Much of the content is new in book publications, because it was previously found only in journal publications, e.g. regarding regular bl...

  20. Phenomenology of symmetry breaking from extra dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Alfaro, Jorge [Facultad de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Broncano, Alicia [Max Planck Institute for Physics, Foehringer Ring 6, 80805 Munich (Germany); Belen Gavela, Maria [Departamento de Fisica Teorica and Instituto de Fisica Teorica, Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Rigolin, Stefano [Departamento de Fisica Teorica and Instituto de Fisica Teorica, Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Salvatori, Matteo [Departamento de Fisica Teorica and Instituto de Fisica Teorica, Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain)

    2007-01-15

    Motivated by the electroweak hierarchy problem, we consider theories with two extra dimensions in which the four-dimensional scalar fields are components of gauge boson in full space. We explore the Nielsen-Olesen instability for SU(N) on a torus, in the presence of a magnetic background. A field theory approach is developed, computing explicitly the minimum of the complete effective potential, including tri-linear and quartic couplings and determining the symmetries of the stable vacua. We also develop appropriate gauge-fixing terms when both Kaluza-Klein and Landau levels are present and interacting, discussing the interplay between the possible six and four dimensional choices. The equivalence between coordinate dependent and constant Scherk-Schwarz boundary conditions - associated to either continuous or discrete Wilson lines - is analyzed.

  1. Dynamic Extra Buses Scheduling Strategy in Public Transport

    Directory of Open Access Journals (Sweden)

    Bin Yu

    2015-06-01

    Full Text Available This paper presents a dynamic extra buses scheduling strategy to improve the transit service of transit routes. In this strategy, in order to decide when to dispatch an extra bus, the service reliability of transit route is assessed firstly. A model aimed at maximizing the benefit of the extra buses scheduling strategy is constructed to determine how many stops extra buses need to skip from the terminal to accommodate passengers at the following stops. A heuristic algorithm is defined and implemented to estimate the service reliability of transit route and to optimize the initial stop of extra buses scheduling strategy. Finally, the strategy is tested on two examples: a simple and a real-life transit route in the Dalian city in China. The results show that the extra buses scheduling strategy based on terminal stops with a reasonable threshold can save 8.01% waiting time of passengers.

  2. Evaluation of fresh pasta-making properties of extra-strong common wheat (Triticum aestivum L.).

    Science.gov (United States)

    Ito, Miwako; Maruyama-Funatsuki, Wakako; Ikeda, Tatsuya M; Nishio, Zenta; Nagasawa, Koichi; Tabiki, Tadashi; Yamauchi, Hiroaki

    2012-12-01

    The relationship between characterictics of flour of common wheat varieties and fresh pasta-making qualitites was examined, and the fresh pasta-making properties of extra-strong varieties that have extra-strong dough were evaluated. There was a positive correlation between mixing time (PT) and hardness of boiled pasta, indicating that the hardness of boiled pasta was affected by dough properties. Boiled pasta made from extra-strong varieties, Yumechikara, Hokkai 262 and Hokkai 259, was harder than that from other varieties and commercial flour. There was a negative correlation between flour protein content and brightness of boiled pasta. The colors of boiled pasta made from Yumechikara and Hokkai 262 grown under the condition of standard manuring culture were superior to those of boiled pasta made from other varieties. Discoloration of boiled pasta made from Yumechikara grown under the condition of heavy manuring culture was caused by increase of flour protein content. On the other hand, discoloration of boiled pasta made from Hokkai 262 grown under the condition of heavy manuring culture was less than that of boiled pasta made from Yumechikara. These results indicate that pasta made from extra-strong wheat varieties has good hardness and that Hokkai 262 has extraordinary fresh pasta-making properties.

  3. Cosmologically safe QCD axion as a present from extra dimension

    Directory of Open Access Journals (Sweden)

    Masahiro Kawasaki

    2015-11-01

    Full Text Available We propose a QCD axion model where the origin of PQ symmetry and suppression of axion isocurvature perturbations are explained by introducing an extra dimension. Each extra quark–antiquark pair lives on branes separately to suppress PQ breaking operators. The size of the extra dimension changes after inflation due to an interaction between inflaton and a bulk scalar field, which implies that the PQ symmetry can be drastically broken during inflation to suppress undesirable axion isocurvature fluctuations.

  4. Cosmologically safe QCD axion as a present from extra dimension

    Energy Technology Data Exchange (ETDEWEB)

    Kawasaki, Masahiro [Institute for Cosmic Ray Research, The University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Yamada, Masaki, E-mail: yamadam@icrr.u-tokyo.ac.jp [Institute for Cosmic Ray Research, The University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Yanagida, Tsutomu T. [Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan)

    2015-11-12

    We propose a QCD axion model where the origin of PQ symmetry and suppression of axion isocurvature perturbations are explained by introducing an extra dimension. Each extra quark–antiquark pair lives on branes separately to suppress PQ breaking operators. The size of the extra dimension changes after inflation due to an interaction between inflaton and a bulk scalar field, which implies that the PQ symmetry can be drastically broken during inflation to suppress undesirable axion isocurvature fluctuations.

  5. Compact extra dimensions in cosmologies with f(T) structure

    CERN Document Server

    Fiorini, Franco; Vasquez, Yerko

    2013-01-01

    The presence of compact extra dimensions in cosmological scenarios in the context of f(T)-like gravities is discussed. For the case of toroidal compactifications, the analysis is performed in an arbitrary number of extra dimensions. Spherical topologies for the extra dimensions are then carefully studied in six and seven spacetime dimensions, where the proper vielbein fields responsible for the parallelization process are found.

  6. Feedback i undervisningen

    DEFF Research Database (Denmark)

    Kirkegaard, Preben Olund

    2015-01-01

    undervisningsdifferentiering, feedback på læreprocesser, formativ og summativ evaluering, observationer og analyse af undervisning samt lærernes teamsamarbejde herom. Praktikken udgør et særligt læringsrum i læreruddannelsen. Samspillet mellem studerende, praktiklærere og undervisere giver den studerende en unik mulighed...

  7. Plant–soil feedbacks

    NARCIS (Netherlands)

    Cortois, Roeland; Schröder-Georgi, Thomas; Weigelt, Alexandra; Putten, van der Wim H.; Deyn, De Gerlinde B.

    2016-01-01

    1. Plant–soil feedback (PSF), plant trait and functional group concepts advanced our understanding of plant community dynamics, but how they are interlinked is poorly known.
    2. To test how plant functional groups (FGs: graminoids, small herbs, tall herbs, legumes) and plant traits relate to PSF,

  8. Feedback and Prior Achievement.

    Science.gov (United States)

    Hyman, Cynthia; Tobias, Sigmund

    The hypothesis that feedback in programmed instruction is an important variable in the learning of novel, but not familiar, content was investigated. A linear, constructed response program dealing with the Sabbath rituals in the synagogue was chosen due to wide variability in student familiarity with this topic. Subjects were randomly assigned to…

  9. Review of Assessment Feedback

    Science.gov (United States)

    Li, Jinrui; De Luca, Rosemary

    2014-01-01

    This article reviews 37 empirical studies, selected from 363 articles and 20 journals, on assessment feedback published between 2000 and 2011. The reviewed articles, many of which came out of studies in the UK and Australia, reflect the most current issues and developments in the area of assessing disciplinary writing. The article aims to outline…

  10. Science with the EXTraS Project: Exploring the X-ray Transient and variable Sky

    CERN Document Server

    De Luca, A; Tiengo, A; D'Agostino, D; Watson, M G; Haberl, F

    2015-01-01

    The EXTraS project (Exploring the X-ray Transient and variable Sky) will characterise the temporal behaviour of the largest ever sample of objects in the soft X-ray range (0.1-12 keV) with a complex, systematic and consistent analysis of all data collected by the European Photon Imaging Camera (EPIC) instrument onboard the ESA XMM-Newton X-ray observatory since its launch. We will search for, and characterize variability (both periodic and aperiodic) in hundreds of thousands of sources spanning more than nine orders of magnitude in time scale and six orders of magnitude in flux. We will also search for fast transients, missed by standard image analysis. Our analysis will be completed by multiwavelength characterization of new discoveries and phenomenological classification of variable sources. All results and products will be made available to the community in a public archive, serving as a reference for a broad range of astrophysical investigations.

  11. Extra relativistic degrees of freedom without extra particles using Planck data

    CERN Document Server

    Mastache, Jorge

    2013-01-01

    A recent number of analysis of cosmological data have shown indications for the presence of extra radiation beyond the standard model at equality and nucleosynthesis epoch, which has been usually interpreted as an effective number of neutrinos, Neff > 3.046. In this work we establish the theoretical basis for a particle physics-motivated model (Bound Dark Matter, BDM) which explain the need of extra radiation. The BDM model describes dark matter particles which are relativistic at a scale below aac due to non-perturbative methods, as protons and neutrons do, this process is described by a time dependent equation of state, w_bdm(a). We compute the range of values of the BDM model, xc=ac*vc, that explain the values obtain for the 4He at BBN and Neff at equality. Combining different analysis we conclude that this may happen in xc = 5.01 (^{+6.01}_{-5.01}) x 10^{-5} with a vc = 0.56 \\pm 0.39. We conclude that we can account for the apparent extra radiation Nex using phase transition in the dark matter with a time...

  12. Clustering in Cell Cycle Dynamics with General Response/Signaling Feedback

    CERN Document Server

    Young, Todd; Buckalew, Richard; Moses, Gregory; Boczko, Erik; 10.1016/j.jtbi.2011.10.002.

    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 fr...

  13. Online feedback op schriftelijk werk: betere feedback in minder tijd.

    NARCIS (Netherlands)

    van den Berg, B.A.M.|info:eu-repo/dai/nl/288125797; van der Hulst, M.E.

    2015-01-01

    Feedback is a powerful teaching technic to raise students’ performance, provided that the feedback is informative on how to improve, is given in a timely manner and students have the opportunity to act upon it. Therefore, many institutions want their students to receive feedback on their performance

  14. Online feedback op schriftelijk werk: betere feedback in minder tijd.

    NARCIS (Netherlands)

    van den Berg, B.A.M.; van der Hulst, M.E.

    2015-01-01

    Feedback is a powerful teaching technic to raise students’ performance, provided that the feedback is informative on how to improve, is given in a timely manner and students have the opportunity to act upon it. Therefore, many institutions want their students to receive feedback on their performance

  15. Timing matters: the impact of immediate and delayed feedback on artificial language learning.

    Science.gov (United States)

    Opitz, Bertram; Ferdinand, Nicola K; Mecklinger, Axel

    2011-01-01

    In the present experiment, we used event-related potentials (ERP) to investigate the role of immediate and delayed feedback in an artificial grammar learning (AGL) task. Two groups of participants were engaged in classifying non-word strings according to an underlying rule system, not known to the participants. Visual feedback was provided after each classification either immediately or with a short delay of 1 s. Both groups were able to learn the artificial grammar system as indicated by an increase in classification performance. However, the gain in performance was significantly larger for the group receiving immediate feedback as compared to the group receiving delayed feedback. Learning was accompanied by an increase in P300 activity in the ERP for delayed as compared to immediate feedback. Irrespective of feedback delay, both groups exhibited learning related decreases in the feedback-related positivity (FRP) elicited by positive feedback only. The feedback-related negativity (FRN), however, remained constant over the course of learning. These results suggest, first, that delayed feedback is less effective for AGL as task requirements are very demanding, and second, that the FRP elicited by positive prediction errors decreases with learning while the FRN to negative prediction errors is elicited in an all-or-none fashion by negative feedback throughout the entire experiment.

  16. Timing matters: The impact of immediate and delayed feedback on artificial language learning

    Directory of Open Access Journals (Sweden)

    Bertram Opitz

    2011-02-01

    Full Text Available In the present experiment, we used event-related potentials (ERP to investigate the role of immediate and delayed feedback in an artificial grammar learning task. Two groups of participants were engaged in classifying non-word strings according to an underlying rule system, not known to the participants. Visual feedback was provided after each classification either immediately or with a short delay of one second. Both groups were able to learn the artificial grammar system as indicated by an increase in classification performance. However, the gain in performance was significantly larger for the group receiving immediate feedback as compared to the group receiving delayed feedback. Learning was accompanied by an increase in P300 activity in the ERP for delayed as compared to immediate feedback. Irrespective of feedback delay, both groups exhibited learning related decreases in the feedback-related positivity (FRP elicited by positive feedback only. The feedback-related negativity (FRN, however, remained constant over the course of learning. These results suggest, first, that delayed feedback is less effective for artificial grammar learning as task requirements are very demanding, and second, that the FRP elicited by positive prediction errors decreases with learning while the FRN to negative prediction errors is elicited in an all-or-none fashion by negative feedback throughout the entire experiment.

  17. Stability and optimal parameters for continuous feedback chaos control.

    Science.gov (United States)

    Kouomou, Y Chembo; Woafo, P

    2002-09-01

    We investigate the conditions under which an optimal continuous feedback control can be achieved. Chaotic oscillations in the single-well Duffing model, with either a positive or a negative nonlinear stiffness term, are tuned to their related Ritz approximation. The Floquet theory enables the stability analysis of the control. Critical values of the feedback control coefficient fulfilling the optimization criteria are derived. The influence of the chosen target orbit, of the feedback coefficient, and of the onset time of control on its duration is discussed. The analytic approach is confirmed by numerical simulations.

  18. Reach adaptation and proprioceptive recalibration following terminal visual feedback of the hand

    Directory of Open Access Journals (Sweden)

    Victoria eBarkley

    2014-09-01

    Full Text Available We have shown that when subjects reach with continuous, misaligned visual feedback of their hand, their reaches are adapted and proprioceptive sense of hand position is recalibrated to partially match the visual feedback (Salomonczyk et al., 2011. It is unclear if similar changes arise after reaching with visual feedback that is provided only at the end of the reach (i.e., terminal feedback, when there are shorter temporal intervals for subjects to experience concurrent visual and proprioceptive feedback. Subjects reached to targets with an aligned hand-cursor that provided visual feedback at the end of each reach movement across a 99-trial training block, and with a rotated cursor over 3 successive blocks of 99 trials each. After each block, no cursor reaches, to measure aftereffects, and felt hand positions were measured. Felt hand position was determined by having subjects indicate the position of their unseen hand relative to a reference marker. We found that subjects adapted their reaches following training with rotated terminal visual feedback, yet slightly less (i.e., reach aftereffects were smaller, than subjects from a previous study who experienced continuous visual feedback. Nonetheless, current subjects recalibrated their sense of felt hand position in the direction of the altered visual feedback, but this proprioceptive change increased incrementally over the three rotated training blocks. Final proprioceptive recalibration levels were comparable to our previous studies in which subjects performed the same task with continuous visual feedback. Thus, compared to reach training with continuous, but altered visual feedback, subjects who received terminal altered visual feedback of the hand produced significant but smaller reach aftereffects and similar changes in hand proprioception when given extra training. Taken together, results suggest that terminal feedback of the hand is sufficient to drive motor adaptation, and also

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

    Directory of Open Access Journals (Sweden)

    Suzete Chiviacowsky

    Full Text Available 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.

  20. Engaging Students with Audio Feedback

    Science.gov (United States)

    Cann, Alan

    2014-01-01

    Students express widespread dissatisfaction with academic feedback. Teaching staff perceive a frequent lack of student engagement with written feedback, much of which goes uncollected or unread. Published evidence shows that audio feedback is highly acceptable to students but is underused. This paper explores methods to produce and deliver audio…

  1. Higgs Pair Production in Models with Universal Extra Dimensions

    CERN Document Server

    de Sandes, Hiroshi

    2007-01-01

    In this letter we study the process of gluon fusion into a pair of Higgs bosons in a model with one universal extra dimension. We find that the contributions from the extra top quark Kaluza-Klein excitations lead to a Higgs pair production cross section that can be significantly altered compared to the Standard Model value for small values of the compactification scale.

  2. 29 CFR 541.604 - Minimum guarantee plus extras.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Minimum guarantee plus extras. 541.604 Section 541.604 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS... SALES EMPLOYEES Salary Requirements § 541.604 Minimum guarantee plus extras. (a) An employer may...

  3. Direct Detection of Extra-Solar Comets is Possible

    OpenAIRE

    Jura, M.

    2005-01-01

    The dust tails of comets similar to Hale-Bopp can scatter as much optical light as does the Earth. Space-based observatories such as the Terrestrial Planet Finder or Darwin that will detect extra-solar terrestrial planets also will be able to detect extra-solar comets.

  4. Fundamental and composite scalars from extra dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Aranda, Alfredo [Dual C-P Institute of High Energy Physics, Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima, Colima (Mexico)], E-mail: fefo@ucol.mx; Diaz-Cruz, J.L. [Dual C-P Institute of High Energy Physics, Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima, Colima (Mexico); Dual C-P Institute of High Energy Physics, Facultad de Ciencias Fisico-Matematicas, BUAP, Apdo. Postal 1364, C.P. 72000 Puebla, Pue (Mexico)], E-mail: lorenzo.diaz@fcfm.buap.mx; Hernandez-Sanchez, J. [Dual C-P Institute of High Energy Physics, Centro de Investigacion en Matematicas, Universidad Autonoma del Estado de Hidalgo, Carretera Pachuca-Tulancingo km. 4.5, C.P. 42184, Pachuca, Hidalgo (Mexico)], E-mail: jaimeh@uaeh.edu.mx; Noriega-Papaqui, R. [Dual C-P Institute of High Energy Physics, Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apdo. Postal 20-364, 01000 Mexico D.F. (Mexico)], E-mail: rnoriega@fisica.unam.mx

    2007-12-13

    We discuss a scenario consisting of an effective 4D theory containing fundamental and composite fields. The strong dynamics sector responsible for the compositeness is assumed to be of extra dimensional origin. In the 4D effective theory the SM fermion and gauge fields are taken as fundamental fields. The scalar sector of the theory resembles a bosonic topcolor in the sense there are two scalar Higgs fields, a composite scalar field and a fundamental gauge-Higgs unification scalar. A detailed analysis of the scalar spectrum is presented in order to explore the parameter space consistent with experiment. It is found that, under the model assumptions, the acceptable parameter space is quite constrained. As a part of our phenomenological study of the model, we evaluate the branching ratio of the lightest Higgs boson and find that our model predicts a large FCNC mode h{yields}tc, which can be as large as O(10{sup -3}). Similarly, a large BR for the top FCNC decay is obtained, namely BR(t{yields}c+H){approx_equal}10{sup -4}.

  5. Girls and war: an extra vulnerability.

    Science.gov (United States)

    Black, M

    1998-01-01

    It is no longer possible to consider the raping of girls as an isolated atrocity of war. In Uganda, guerrilla forces have kidnapped 6000-10,000 children and have forced the "most desirable" girls to become "wives" of warlords. Girls who manage to escape are deeply traumatized and suffer ill health as well as possible social ostracism. In refugee camps, recognition that adolescent girls face special risks of rape and of engaging in the informal prostitution that may expose them to HIV/AIDS has led to the introduction of new measures to increase female security. Families in refugee camps in Burundi and Somalia protect female honor by submitting their daughters to very early marriage, which also abuses the girls' rights. Girls conscripted to military groups are forced to transport materials, cook, or help loot villages. In conditions of war, even girls who remain at home protected by their families must assume extra responsibilities, especially if men go off to fight leaving women with the agricultural and livestock burdens. Girls will be the first children withdrawn from school to help keep the household afloat. Girls and women are also expected to tend those wounded by the very war that destroys the health care services that are vital to meet women's reproductive needs. Efforts are being made to identify rape as a specific war crime, and these efforts should be extended to the kidnapping and forced recruitment of children into combat roles. Moral codes must be reestablished, even if they are only nominal at present.

  6. Diphoton Resonance from a Warped Extra Dimension

    CERN Document Server

    Bauer, Martin; Neubert, Matthias

    2016-01-01

    We argue that extensions of the Standard Model (SM) with a warped extra dimension, which successfully address the hierarchy and flavor problems of elementary particle physics, can provide an elegant explanation of the 750 GeV diphoton excess recently reported by ATLAS and CMS. A gauge-singlet bulk scalar with O(1) couplings to fermions is identified as the new resonance S, and the vector-like Kaluza-Klein excitations of the SM quarks and leptons mediate its loop-induced couplings to photons and gluons. The electroweak gauge symmetry almost unambiguously dictates the bulk matter content and hence the hierarchies of the S->\\gamma\\gamma, WW, ZZ, Z\\gamma, t\\bar t and dijet decay rates. We find that the S->Z\\gamma decay mode is strongly suppressed, such that Br(S->Z\\gamma)Br(S->\\gamma\\gamma)S->\\gamma\\gamma signal requires Kaluza-Klein masses in the multi-TeV range, in perfect agreement with bounds from flavor physics and electroweak precision observables.

  7. Gravitation, holographic principle, and extra dimensions

    CERN Document Server

    Caimmi, R

    2016-01-01

    Within the context of Newton's theory of gravitation, restricted to point-like test particles and central bodies, stable circular orbits in ordinary space are related to stable circular paths on a massless, unmovable, undeformable vortex-like surface, under the action of a tidal gravitational field along the symmetry axis. An interpretation is made in the light of a holographic principle, in the sense that motions in ordinary space are connected with motions on a selected surface and vice versa. Then ordinary space is conceived as a 3-hypersurface bounding a $n$-hypervolume where gravitation takes origin, within a $n$-hyperspace. The extension of the holographic principle to extra dimensions implies the existence of a minimum distance where test particles may still be considered as distinct from the central body. Below that threshold, it is inferred test particles lose theirs individuality and "glue" to the central body via unification of the four known interactions and, in addition, (i) particles can no long...

  8. Diphoton resonance from a warped extra dimension

    Science.gov (United States)

    Bauer, Martin; Hörner, Clara; Neubert, Matthias

    2016-07-01

    We argue that extensions of the Standard Model (SM) with a warped extra dimension, which successfully address the hierarchy and flavor problems of elementary particle physics, can provide an elegant explanation of the 750 GeV diphoton excess recently reported by ATLAS and CMS. A gauge-singlet bulk scalar with {O} (1) couplings to fermions is identified as the new resonance S, and the vector-like Kaluza-Klein excitations of the SM quarks and leptons mediate its loop-induced couplings to photons and gluons. The electroweak gauge symmetry almost unambiguously dictates the bulk matter content and hence the hierarchies of the Sto γ γ, W W,ZZ,Zγ, toverline{t} and dijet decay rates. We find that the S → Zγ decay mode is strongly suppressed, such that Br( S → Zγ) /Br( S → γγ) converge and can be calculated in closed form with a remarkably simple result. Reproducing the observed pp → S → γγ signal requires Kaluza-Klein masses in the multi-TeV range, consistent with bounds from flavor physics and electroweak precision observables.

  9. Brane Stabilization and Regionality of Extra Dimensions

    CERN Document Server

    Jacobs, David M; Tolley, Andrew J

    2012-01-01

    Extra dimensions are a common feature of beyond the Standard Model physics. In a braneworld scenario, local physics on the brane can depend strongly on the brane's location within the bulk. Generically, the relevant properties of the bulk manifold for the physics on/of the brane are neither local nor global, but depend on the structure of finite regions of the bulk, even for locally homogeneous and isotropic bulk geometries. In a recent work, various mechanisms (in a braneworld context) were considered to stabilize the location of a brane within bulk spaces of non-trivial topology. In this work we elaborate on and generalize that work by considering additional bulk and brane dimensionalities as well as different boundary conditions on the bulk scalar field that provides a Casimir force on the brane, providing further insight on this effect. In D=2+1 (D=5+1) we consider both local and global contributions to the effective potential of a 1-brane (4-brane) wrapped around both the 2-dimensional hyperbolic horn an...

  10. LHC Signals from Warped Extra Dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Agashe, K.; Belyaev, A.; Krupovnickas, T.; Perez, G.; Virzi, J.

    2006-12-06

    We study production of Kaluza-Klein gluons (KKG) at the Large Hadron Collider (LHC) in the framework of a warped extra dimension with the Standard Model (SM) fields propagating in the bulk. We show that the detection of KK gluon is challenging since its production is suppressed by small couplings to the proton's constituents. Moreover, the KK gluon decaysmostly to top pairs due to an enhanced coupling and hence is broad. Nevertheless, we demonstrate that for MKKG<~;; 4 TeV, 100 fb-1 of data at the LHC can provide discovery of the KK gluon. We utilize a sizeable left-right polarization asymmetry from the KK gluon resonance to maximize the signal significance, and we explore the novel feature of extremely highly energetic"top-jets." We briefly discuss how the detection of electroweak gauge KK states (Z/W) faces a similar challenge since their leptonic decays ("golden" modes) are suppressed. Our analysis suggests that other frameworks, for example little Higgs, which rely on UV completion via strong dynamics might face similar challenges, namely (1) Suppressed production rates for the new particles (such as Z'), due to their"lightfermion-phobic" nature, and (2) Difficulties in detection since the new particles are broad and decay predominantly to third generation quarks and longitudinal gauge bosons.

  11. Extra cellular matrix features in human meninges.

    Science.gov (United States)

    Montagnani, S; Castaldo, C; Di Meglio, F; Sciorio, S; Giordano-Lanza, G

    2000-01-01

    We collected human fetal and adult normal meninges to relate the age of the tissue with the presence of collagenous and non-collagenous components of Extra Cellular Matrix (ECM). Immunohistochemistry led us to observe some differences in the amount and in the distribution of these proteins between the two sets of specimens. In particular, laminin and tenascin seem to be expressed more intensely in fetal meninges when compared to adult ones. In order to investigate whether the morphofunctional characteristics of fetal meninges may be represented in pathological conditions we also studied meningeal specimens from human meningiomas. Our attention was particularly focused on the expression of those non-collagenous proteins involved in nervous cell migration and neuronal morphogenesis as laminin and tenascin, which were present in lesser amount in normal adult specimens. Microscopical evidences led us to hipothesize that these proteins which are synthesized in a good amount during the fetal development of meninges can be newly produced in tumors. On the contrary, the role of tenascin and laminin in adult meninges is probably only interesting for their biophysical characteristics.

  12. Effects of intrinsic motivation on feedback processing during learning.

    Science.gov (United States)

    DePasque, Samantha; Tricomi, Elizabeth

    2015-10-01

    Learning commonly requires feedback about the consequences of one's actions, which can drive learners to modify their behavior. Motivation may determine how sensitive an individual might be to such feedback, particularly in educational contexts where some students value academic achievement more than others. Thus, motivation for a task might influence the value placed on performance feedback and how effectively it is used to improve learning. To investigate the interplay between intrinsic motivation and feedback processing, we used functional magnetic resonance imaging (fMRI) during feedback-based learning before and after a novel manipulation based on motivational interviewing, a technique for enhancing treatment motivation in mental health settings. Because of its role in the reinforcement learning system, the striatum is situated to play a significant role in the modulation of learning based on motivation. Consistent with this idea, motivation levels during the task were associated with sensitivity to positive versus negative feedback in the striatum. Additionally, heightened motivation following a brief motivational interview was associated with increases in feedback sensitivity in the left medial temporal lobe. Our results suggest that motivation modulates neural responses to performance-related feedback, and furthermore that changes in motivation facilitate processing in areas that support learning and memory.

  13. Improving the quality of written feedback using written feedback.

    Science.gov (United States)

    Bartlett, Maggie; Crossley, James; McKinley, Robert

    2017-01-01

    Educational feedback is amongst the most powerful of all learning interventions. (1) Can we measure the quality of written educational feedback with acceptable metrics? (2) Based on such a measure, does a quality improvement (QI) intervention improve the quality of feedback? We developed a QI instrument to measure the quality of written feedback and applied it to written feedback provided to medical students following workplace assessments. We evaluated the measurement characteristics of the QI score using generalisability theory. In an uncontrolled intervention, QI profiles were fed back to GP tutors and pre and post intervention scores compared. A single assessor scoring 6 feedback summaries can discriminate between practices with a reliability of 0.82.The quality of feedback rose for two years after the introduction of the QI instrument and stabilised in the third year. The estimated annual cost to provide this feedback is £12 per practice. Interpretation and recommendations: It is relatively straightforward and inexpensive to measure the quality of written feedback with good reliability. The QI process appears to improve the quality of written feedback. We recommend routine use of a QI process to improve the quality of educational feedback.

  14. Regenerative feedback resonant circuit

    Science.gov (United States)

    Jones, A. Mark; Kelly, James F.; McCloy, John S.; McMakin, Douglas L.

    2014-09-02

    A regenerative feedback resonant circuit for measuring a transient response in a loop is disclosed. The circuit includes an amplifier for generating a signal in the loop. The circuit further includes a resonator having a resonant cavity and a material located within the cavity. The signal sent into the resonator produces a resonant frequency. A variation of the resonant frequency due to perturbations in electromagnetic properties of the material is measured.

  15. Global Stability in Dynamical Systems with Multiple Feedback Mechanisms

    DEFF Research Database (Denmark)

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

    2016-01-01

    . This is a bounded set with non-negative elements where solutions cannot escape. All solutions are shown to converge to a “minimal” trapping region. 2) At least one fixed point exists. 3) Sufficient criteria for a unique fixed point are formulated. One case where this is fulfilled is when the feedbacks are negative.......A class of n-dimensional ODEs with up to n feedbacks from the n’th variable is analysed. The feedbacks are represented by non-specific, bounded, non-negative C1 functions. The main result is the formulation and proof of an easily applicable criterion for existence of a globally stable fixed point...... of the system. The proof relies on the contraction mapping theorem. Applications of this type of systems are numerous in biology, e.g., models of the hypothalamic-pituitary-adrenal axis and testosterone secretion. Some results important for modelling are: 1) Existence of an attractive trapping region...

  16. New synthesis algorithm of static output feedback sliding mode control for a class of uncertain systems

    Institute of Scientific and Technical Information of China (English)

    Ji XIANG; Hongye SU; Jian CHU; Xiaoyu ZHANG

    2004-01-01

    Based on a kind of regular form,a Lyapunov matrix with special structure is presented to design the sliding surface matrix conveniently and then an effective algorithm is developed on it.A simple static output feedback sliding mode control law without extra dynamic equation is given,such that the predefined sliding surface is reached in finite time for the general matching uncertainties.In the reported result,this extra dynamic equation is used for evaluating the norm bound of the unmeasured state vector.Finally,some examples are studied to illustrate the proposed approach.

  17. Feedback on Feedback: Eliciting Learners' Responses to Written Feedback through Student-Generated Screencasts

    Science.gov (United States)

    Fernández-Toro, María; Furnborough, Concha

    2014-01-01

    Despite the potential benefits of assignment feedback, learners often fail to use it effectively. This study examines the ways in which adult distance learners engage with written feedback on one of their assignments. Participants were 10 undergraduates studying Spanish at the Open University, UK. Their responses to feedback were elicited by means…

  18. Feedback on Feedback: Eliciting Learners' Responses to Written Feedback through Student-Generated Screencasts

    Science.gov (United States)

    Fernández-Toro, María; Furnborough, Concha

    2014-01-01

    Despite the potential benefits of assignment feedback, learners often fail to use it effectively. This study examines the ways in which adult distance learners engage with written feedback on one of their assignments. Participants were 10 undergraduates studying Spanish at the Open University, UK. Their responses to feedback were elicited by means…

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

    Science.gov (United States)

    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…

  20. Feedback på arbejdspladser

    DEFF Research Database (Denmark)

    Holdt Christensen, Peter

    Feedback på arbejdspladser er vigtig. Men feedback er også et populært begreb mange taler med om uden dog at vide sig helt sikker på hvad det er. Formålet med denne bog er at bidrage til en bedre forståelse af hvad feedback er, hvordan det fungerer og dermed hvordan arbejdspladser bedst muligt bør...... understøtte feedback. Med udgangspunkt i forskningen identificeres centrale udfordringer ved feedback, bl.a. hvorfor det kan være svært at give præcis feedback, hvordan forholdet mellem lederen og den ansatte påvirker den feedback der gives, og hvad der kendetegner en feedback kultur. Bogen er skrevet til...... undervisere og studerende på videregående uddannelser samt praktikere der ønsker en systematisk og forskningsbaseret forståelse af feedback på arbejdspladser. Bogen er således ikke en kogebog til bedre feedback, men en analyse og diskussion af hvad forskningen ved om feedback, og bidrager med inspiration og...

  1. Decorrelation of Neural-Network Activity by Inhibitory Feedback

    Science.gov (United States)

    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

  2. Error bounds from extra precise iterative refinement

    Energy Technology Data Exchange (ETDEWEB)

    Demmel, James; Hida, Yozo; Kahan, William; Li, Xiaoye S.; Mukherjee, Soni; Riedy, E. Jason

    2005-02-07

    We present the design and testing of an algorithm for iterative refinement of the solution of linear equations, where the residual is computed with extra precision. This algorithm was originally proposed in the 1960s [6, 22] as a means to compute very accurate solutions to all but the most ill-conditioned linear systems of equations. However two obstacles have until now prevented its adoption in standard subroutine libraries like LAPACK: (1) There was no standard way to access the higher precision arithmetic needed to compute residuals, and (2) it was unclear how to compute a reliable error bound for the computed solution. The completion of the new BLAS Technical Forum Standard [5] has recently removed the first obstacle. To overcome the second obstacle, we show how a single application of iterative refinement can be used to compute an error bound in any norm at small cost, and use this to compute both an error bound in the usual infinity norm, and a componentwise relative error bound. We report extensive test results on over 6.2 million matrices of dimension 5, 10, 100, and 1000. As long as a normwise (resp. componentwise) condition number computed by the algorithm is less than 1/max{l_brace}10,{radical}n{r_brace} {var_epsilon}{sub w}, the computed normwise (resp. componentwise) error bound is at most 2 max{l_brace}10,{radical}n{r_brace} {center_dot} {var_epsilon}{sub w}, and indeed bounds the true error. Here, n is the matrix dimension and w is single precision roundoff error. For worse conditioned problems, we get similarly small correct error bounds in over 89.4% of cases.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  5. Effects of Mongolian Pharmaceutical Betel Shisanwei Ingredients Pill on hypothalamic-pituitary-adrenal axis negative feedback function in rat models of chronic stress-induced depression%慢性应激抑郁模型大鼠下丘脑-垂体-肾上腺轴负反馈功能与蒙药槟榔十三味丸的干预

    Institute of Scientific and Technical Information of China (English)

    包伍叶; 范盎然; 白亮凤; 佟海英; 于雪; 乌吉斯古冷; 李婧; 胡日乐巴根; 张月

    2014-01-01

    BACKGROUND:Mongolian Pharmaceutical Betel Shisanwei Ingredients Pil has achieved good clinical efficacy, but the underlying mechanism remains unclear. OBJECTIVE: To study the effects of Mongolian Pharmaceutical Betel Shisanwei Ingredients Pil on the hypothalamic-pituitary-adrenal axis negative feedback function in the chronic depressed rats, and to explore anti-depression mechanisms of Mongolian Pharmaceutical Betel Shisanwei ingredients pil. METHODS: Eighty male Wistar rats were randomly divided into ten groups according to the sugar consumption test (with eight rats in each group): normal control group, model group, fluoxetine group, high-, medium- and low-dose Betel Shisanwei Ingredients Pil groups, RU486 group, high-, medium- and low-dose Betel Shisanwei Ingredients Pil plus RU486 groups. Except normal control group, the other groups were treated with the chronic unpredictable mild stress stimulation combined with lonely rising, to establish depression models. In the meantime, rats of the high-, medium- and low-dose Betel Shisanwei Ingredients Pil groups were given oral gavage of Betel Shisanwei Ingredients Pil (0.2, 0.4, 0.8 g/kg) for 28 days; rats of the normal control group and model group were intragstricaly administered with sodium carboxymethyl celulose; rats of RU486 group were given abdominal subcutaneous injection of RU486 from day 21 after modeling; rats of the high-, medium- and low-dose Betel Shisanwei Ingredients Pil plus RU486 groups were intragstricaly administered with Betel Shisanwei Ingredients Pil (0.2, 0.4, 0.8 g/kg) and subcutaneous injection of RU486 from day 21. RESULTS AND CONCLUSION:Compared with normal control group, cortisone content increased significantly (P < 0.05), the expression of glucocorticoid receptor mRNA in hippocampus, hypothalamus and pituitary gland decreased significantly, and hypothalamic corticotrophin releasing hormone mRNA expression increased significantly in the model group and RU486 group. Compared with model

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

    Science.gov (United States)

    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.

  7. National extra heavy crude oil upgrade; Melhoramento de petroleos extra pesados nacionais no ambiente de producao

    Energy Technology Data Exchange (ETDEWEB)

    Medina, Lilian Camen; Zilio, Evaldo L.; Guimarae, Regina C.; Tosta, Luiz C. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas; Barros, Ricardo S. de [Fundacao Universitaria Jose Bonifacio (FUJB), Rio de Janeiro, RJ (Brazil); Leite, Luiz Fernando T. [PETROBRAS S.A., Vitoria, ES (Brazil). Unidade de Negocios-ES

    2008-07-01

    Brazilian petroleums are becoming increasingly heavy, reaching values of up to 7 deg API, which classifies them as extra heavy. They are also very viscous, sometimes presenting values as 10184 mm{sup 2}/s to 50 deg C. These two factors affect production operations like lifting, flow assurance and primary processing, with implications on transporting and refining. Trading these kinds of oils is also difficult; once there are not many refineries in the world able to process them. Due to these facts and also to the lower yield on premium products, the international market value is lower than the reference oil, for example, oil 'Brent'. Studies indicate that in some heavy oils fields the process of well lifting and also the flow in pipelines is almost impracticable in a first analysis, mainly offshore field, impacting both technically and economically the development of the production of a new field. Therefore it becomes necessary implement efforts to develop alternatives to increase oil's API density and at the same time reduce the viscosity of extra heavy oil inside the well, i.e. through a process of upgrading assuring its flow and consequently their production, primary processing and refining, increasing, the value of marketing. (author)

  8. Proprioceptive feedback and brain computer interface (BCI based neuroprostheses.

    Directory of Open Access Journals (Sweden)

    Ander Ramos-Murguialday

    Full Text Available Brain computer interface (BCI technology has been proposed for motor neurorehabilitation, motor replacement and assistive technologies. It is an open question whether proprioceptive feedback affects the regulation of brain oscillations and therefore BCI control. We developed a BCI coupled on-line with a robotic hand exoskeleton for flexing and extending the fingers. 24 healthy participants performed five different tasks of closing and opening the hand: (1 motor imagery of the hand movement without any overt movement and without feedback, (2 motor imagery with movement as online feedback (participants see and feel their hand, with the exoskeleton moving according to their brain signals, (3 passive (the orthosis passively opens and closes the hand without imagery and (4 active (overt movement of the hand and rest. Performance was defined as the difference in power of the sensorimotor rhythm during motor task and rest and calculated offline for different tasks. Participants were divided in three groups depending on the feedback receiving during task 2 (the other tasks were the same for all participants. Group 1 (n = 9 received contingent positive feedback (participants' sensorimotor rhythm (SMR desynchronization was directly linked to hand orthosis movements, group 2 (n = 8 contingent "negative" feedback (participants' sensorimotor rhythm synchronization was directly linked to hand orthosis movements and group 3 (n = 7 sham feedback (no link between brain oscillations and orthosis movements. We observed that proprioceptive feedback (feeling and seeing hand movements improved BCI performance significantly. Furthermore, in the contingent positive group only a significant motor learning effect was observed enhancing SMR desynchronization during motor imagery without feedback in time. Furthermore, we observed a significantly stronger SMR desynchronization in the contingent positive group compared to the other groups during active and

  9. Search for Large Extra Dimensions in Dielectron and Diphoton Production

    CERN Document Server

    Abbott, B; Abramov, V; Acharya, B S; Adams, D L; Adams, M; Alves, G A; Amos, N; Anderson, E W; Baarmand, M M; Babintsev, V V; Babukhadia, L R; Baden, A; Baldin, B Yu; Balm, P W; Banerjee, S; Bantly, J; Barberis, E; Baringer, P; Bartlett, J F; Bassler, U; Bean, A; Begel, M; Belyaev, A; Beri, S B; Bernardi, G; Bertram, I; Besson, A; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Bhattacharjee, M; Blazey, G C; Blessing, S; Böhnlein, A; Bozhko, N; Borcherding, F; Brandt, A; Breedon, R; Briskin, G M; Brock, R; Brooijmans, G; Bross, A; Buchholz, D; Bühler, M; Büscher, V; Burtovoi, V S; Butler, J M; Canelli, F; Carvalho, W S; Casey, D; Casilum, Z; Castilla-Valdez, H; Chakraborty, D; Chan, K M; Chekulaev, S V; Cho, D K; Choi, S; Chopra, S; Christenson, J H; Chung, M; Claes, D; Clark, A R; Cochran, J; Coney, L; Connolly, B; Cooper, W E; Coppage, D; Cummings, M A C; Cutts, D; Dahl, O I; Davis, G A; Davis, K; De, K; Del Signore, K; Demarteau, M; Demina, R; Demine, P; Denisov, D S; Denisov, S P; Desai, S V; Diehl, H T; Diesburg, M; DiLoreto, G; Doulas, S; Draper, P; Ducros, Y; Dudko, L V; Duensing, S; Dugad, S R; Dyshkant, A; Edmunds, D L; Ellison, J; Elvira, V D; Engelmann, R; Eno, S; Eppley, G; Ermolov, P; Eroshin, O V; Estrada, J K; Evans, H; Evdokimov, V N; Fahland, T; Fehér, S; Fein, D; Ferbel, T; Fisk, H E; Fisyak, Yu; Flattum, E M; Fleuret, F; Fortner, M R; Frame, K C; Fuess, S; Gallas, E J; Galjaev, A N; Gartung, P E; Gavrilov, V; Genik, R J; Genser, K; Gerber, C E; Gershtein, Yu; Gibbard, B; Gilmartin, R; Ginther, G; Gómez, B; Gómez, G; Goncharov, P I; González-Solis, J L; Gordon, H; Goss, L T; Gounder, K; Goussiou, A; Graf, N; Graham, G; Grannis, P D; Green, J A; Greenlee, H; Grinstein, S; Groer, L S; Grudberg, P M; Grünendahl, S; Sen-Gupta, A; Gurzhev, S N; Gutíerrez, G; Gutíerrez, P; Hadley, N J; Haggerty, H; Hagopian, S L; Hagopian, V; Hahn, K S; Hall, R E; Hanlet, P; Hansen, S; Hauptman, J M; Hays, C; Hebert, C; Hedin, D; Heinson, A P; Heintz, U; Heuring, T C; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoftun, J S; Hou, S; Huang, Y; Ito, A S; Jerger, S A; Jesik, R; Johns, K; Johnson, M; Jonckheere, A M; Jones, M; Jöstlein, H; Juste, A; Kahn, S; Kajfasz, E; Karmanov, D E; Karmgard, D J; Kehoe, R; Kim, S K; Klima, B; Klopfenstein, C; Knuteson, B; Ko, W; Kohli, J M; Kostritskii, A V; Kotcher, J; Kotwal, A V; Kozelov, A V; Kozlovskii, E A; Krane, J; Krishnaswamy, M R; Krzywdzinski, S; Kubantsev, M A; Kuleshov, S; Kulik, Y; Kunori, S; Kuznetsov, V E; Landsberg, G L; Leflat, A; Lehner, F; Li, J; Li, Q Z; Lima, J G R; Lincoln, D; Linn, S L; Linnemann, J T; Lipton, R; Lucotte, A; Lueking, L H; Lundstedt, C; Maciel, A K A; Madaras, R J; Manankov, V; Mao, H S; Marshall, T; Martin, M I; Martin, R D; Mauritz, K M; May, B; Mayorov, A A; McCarthy, R; McDonald, J; McMahon, T; Melanson, H L; Meng, X C; Merkin, M; Merritt, K W B; Miao, C; Miettinen, H; Mihalcea, D; Mincer, A; Mishra, C S; Mokhov, N V; Mondal, N K; Montgomery, H E; Moore, R W; Mostafa, M A; Da Motta, H; Nagy, E; Nang, F; Narain, M; Narasimham, V S; Neal, H A; Negret, J P; Negroni, S; Norman, D; Oesch, L H; Oguri, V; Olivier, B; Oshima, N; Padley, P; Pan, L J; Para, A; Parashar, N; Partridge, R; Parua, N; Paterno, M; Patwa, A; Pawlik, B; Perkins, J; Peters, M; Peters, O; Piegaia, R; Piekarz, H; Pope, B G; Popkov, E; Prosper, H B; Protopopescu, S D; Qian, J; Quintas, P Z; Raja, R; Rajagopalan, S; Ramberg, E; Rapidis, P A; Reay, N W; Reucroft, S; Rha, J; Rijssenbeek, M; Rockwell, T; Roco, M T; Rubinov, P M; Ruchti, R C; Rutherfoord, John P; Santoro, A F S; Sawyer, L; Schamberger, R D; Schellman, H; Schwartzman, A; Scully, J R; Sen, N; Shabalina, E; Shankar, H C; Shivpuri, R K; Shpakov, D; Shupe, M A; Sidwell, R A; Simák, V; Singh, H; Singh, J B; Sirotenko, V I; Slattery, P F; Smith, E; Smith, R P; Snihur, R; Snow, G A; Snow, J; Snyder, S; Solomon, J; Sorin, V; Sosebee, M; Sotnikova, N; Soustruznik, K; Souza, M; Stanton, N R; Steinbruck, G; Stephens, R W; Stevenson, M L; Stichelbaut, F; Stoker, D; Stolin, V; Stoyanova, D A; Strauss, M; Streets, K; Strovink, M; Stutte, L; Sznajder, A; Taylor, W; Tentindo-Repond, S; Thompson, J; Toback, D; Tripathi, S M; Trippe, T G; Turcot, A S; Tuts, P M; Van Gemmeren, P; Vaniev, V; Van Kooten, R; Varelas, N; Volkov, A A; Vorobev, A P; Wahl, H D; Wang, H; Wang, Z M; Warchol, J; Watts, G; Wayne, M; Weerts, H; White, A; White, J T; Whiteson, D; Wightman, J A; Wijngaarden, D A; Willis, S; Wimpenny, S J; Wirjawan, J V D; Womersley, J; Wood, D R; Yamada, R; Yamin, P; Yasuda, T; Yip, K; Youssef, S; Yu, J; Yu, Z; Zanabria, M E; Zheng, H; Zhou, Z; Zhu, Z H; Zielinski, M; Zieminska, D; Zieminski, A; Zutshi, V; Zverev, E G; Zylberstejn, A

    2001-01-01

    We report a search for effects of large extra spatial dimensions in ppbar collisions at a center-of-mass energy of 1.8 TeV with the DZero detector, using events containing a pair of electrons or photons. The data are in good agreement with the expected background and do not exhibit evidence for large extra dimensions. We set the most restrictive lower limits to date, at the 95% confidence level, on the effective Planck scale between 1.0 TeV and 1.4 TeV for several formalisms and numbers of extra dimensions.

  10. Search for Large Extra Dimensions in Dielectron and Diphoton Production

    Science.gov (United States)

    Abbott, B.; Abolins, M.; Abramov, V.; Acharya, B. S.; Adams, D. L.; Adams, M.; Alves, G. A.; Amos, N.; Anderson, E. W.; Baarmand, M. M.; Babintsev, V. V.; Babukhadia, L.; Baden, A.; Baldin, B.; Balm, P. W.; Banerjee, S.; Bantly, J.; Barberis, E.; Baringer, P.; Bartlett, J. F.; Bassler, U.; Bean, A.; Begel, M.; Belyaev, A.; Beri, S. B.; Bernardi, G.; Bertram, I.; Besson, A.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Bhattacharjee, M.; Blazey, G.; Blessing, S.; Boehnlein, A.; Bojko, N. I.; Borcherding, F.; Brandt, A.; Breedon, R.; Briskin, G.; Brock, R.; Brooijmans, G.; Bross, A.; Buchholz, D.; Buehler, M.; Buescher, V.; Burtovoi, V. S.; Butler, J. M.; Canelli, F.; Carvalho, W.; Casey, D.; Casilum, Z.; Castilla-Valdez, H.; Chakraborty, D.; Chan, K. M.; Chekulaev, S. V.; Cho, D. K.; Choi, S.; Chopra, S.; Christenson, J. H.; Chung, M.; Claes, D.; Clark, A. R.; Cochran, J.; Coney, L.; Connolly, B.; Cooper, W. E.; Coppage, D.; Cummings, M. A.; Cutts, D.; Dahl, O. I.; Davis, G. A.; Davis, K.; de, K.; del Signore, K.; Demarteau, M.; Demina, R.; Demine, P.; Denisov, D.; Denisov, S. P.; Desai, S.; Diehl, H. T.; Diesburg, M.; di Loreto, G.; Doulas, S.; Draper, P.; Ducros, Y.; Dudko, L. V.; Duensing, S.; Dugad, S. R.; Dyshkant, A.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Engelmann, R.; Eno, S.; Eppley, G.; Ermolov, P.; Eroshin, O. V.; Estrada, J.; Evans, H.; Evdokimov, V. N.; Fahland, T.; Feher, S.; Fein, D.; Ferbel, T.; Fisk, H. E.; Fisyak, Y.; Flattum, E.; Fleuret, F.; Fortner, M.; Frame, K. C.; Fuess, S.; Gallas, E.; Galyaev, A. N.; Gartung, P.; Gavrilov, V.; Genik, R. J.; Genser, K.; Gerber, C. E.; Gershtein, Y.; Gibbard, B.; Gilmartin, R.; Ginther, G.; Gómez, B.; Gómez, G.; Goncharov, P. I.; González Solís, J. L.; Gordon, H.; Goss, L. T.; Gounder, K.; Goussiou, A.; Graf, N.; Graham, G.; Grannis, P. D.; Green, J. A.; Greenlee, H.; Grinstein, S.; Groer, L.; Grudberg, P.; Grünendahl, S.; Gupta, A.; Gurzhiev, S. N.; Gutierrez, G.; Gutierrez, P.; Hadley, N. J.; Haggerty, H.; Hagopian, S.; Hagopian, V.; Hahn, K. S.; Hall, R. E.; Hanlet, P.; Hansen, S.; Hauptman, J. M.; Hays, C.; Hebert, C.; Hedin, D.; Heinson, A. P.; Heintz, U.; Heuring, T.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Hoftun, J. S.; Hou, S.; Huang, Y.; Ito, A. S.; Jerger, S. A.; Jesik, R.; Johns, K.; Johnson, M.; Jonckheere, A.; Jones, M.; Jöstlein, H.; Juste, A.; Kahn, S.; Kajfasz, E.; Karmanov, D.; Karmgard, D.; Kehoe, R.; Kim, S. K.; Klima, B.; Klopfenstein, C.; Knuteson, B.; Ko, W.; Kohli, J. M.; Kostritskiy, A. V.; Kotcher, J.; Kotwal, A. V.; Kozelov, A. V.; Kozlovsky, E. A.; Krane, J.; Krishnaswamy, M. R.; Krzywdzinski, S.; Kubantsev, M.; Kuleshov, S.; Kulik, Y.; Kunori, S.; Kuznetsov, V. E.; Landsberg, G.; Leflat, A.; Lehner, F.; Li, J.; Li, Q. Z.; Lima, J. G.; Lincoln, D.; Linn, S. L.; Linnemann, J.; Lipton, R.; Lucotte, A.; Lueking, L.; Lundstedt, C.; Maciel, A. K.; Madaras, R. J.; Manankov, V.; Mao, H. S.; Marshall, T.; Martin, M. I.; Martin, R. D.; Mauritz, K. M.; May, B.; Mayorov, A. A.; McCarthy, R.; McDonald, J.; McMahon, T.; Melanson, H. L.; Meng, X. C.; Merkin, M.; Merritt, K. W.; Miao, C.; Miettinen, H.; Mihalcea, D.; Mincer, A.; Mishra, C. S.; Mokhov, N.; Mondal, N. K.; Montgomery, H. E.; Moore, R. W.; Mostafa, M.; da Motta, H.; Nagy, E.; Nang, F.; Narain, M.; Narasimham, V. S.; Neal, H. A.; Negret, J. P.; Negroni, S.; Norman, D.; Oesch, L.; Oguri, V.; Olivier, B.; Oshima, N.; Padley, P.; Pan, L. J.; Para, A.; Parashar, N.; Partridge, R.; Parua, N.; Paterno, M.; Patwa, A.; Pawlik, B.; Perkins, J.; Peters, M.; Peters, O.; Piegaia, R.; Piekarz, H.; Pope, B. G.; Popkov, E.; Prosper, H. B.; Protopopescu, S.; Qian, J.; Quintas, P. Z.; Raja, R.; Rajagopalan, S.; Ramberg, E.; Rapidis, P. A.; Reay, N. W.; Reucroft, S.; Rha, J.; Rijssenbeek, M.; Rockwell, T.; Roco, M.; Rubinov, P.; Ruchti, R.; Rutherfoord, J.; Santoro, A.; Sawyer, L.; Schamberger, R. D.; Schellman, H.; Schwartzman, A.; Sculli, J.; Sen, N.; Shabalina, E.; Shankar, H. C.; Shivpuri, R. K.; Shpakov, D.; Shupe, M.; Sidwell, R. A.; Simak, V.; Singh, H.; Singh, J. B.; Sirotenko, V.; Slattery, P.; Smith, E.; Smith, R. P.; Snihur, R.; Snow, G. R.; Snow, J.; Snyder, S.; Solomon, J.; Sorín, V.; Sosebee, M.; Sotnikova, N.; Soustruznik, K.; Souza, M.; Stanton, N. R.; Steinbrück, G.; Stephens, R. W.; Stevenson, M. L.; Stichelbaut, F.; Stoker, D.; Stolin, V.; Stoyanova, D. A.; Strauss, M.; Streets, K.; Strovink, M.; Stutte, L.; Sznajder, A.; Taylor, W.; Tentindo-Repond, S.; Thompson, J.; Toback, D.; Tripathi, S. M.; Trippe, T. G.; Turcot, A. S.; Tuts, P. M.; van Gemmeren, P.; Vaniev, V.; van Kooten, R.; Varelas, N.; Volkov, A. A.; Vorobiev, A. P.; Wahl, H. D.; Wang, H.; Wang, Z.-M.; Warchol, J.; Watts, G.; Wayne, M.; Weerts, H.; White, A.; White, J. T.; Whiteson, D.; Wightman, J. A.; Wijngaarden, D. A.; Willis, S.; Wimpenny, S. J.; Wirjawan, J. V.; Womersley, J.; Wood, D. R.; Yamada, R.; Yamin, P.; Yasuda, T.; Yip, K.; Youssef, S.; Yu, J.; Yu, Z.; Zanabria, M.; Zheng, H.; Zhou, Z.; Zhu, Z. H.; Zielinski, M.; Zieminska, D.; Zieminski, A.; Zutshi, V.; Zverev, E. G.; Zylberstejn, A.

    2001-02-01

    We report a search for effects of large extra spatial dimensions in pp¯ collisions at a center-of-mass energy of 1.8 TeV with the D0 detector, using events containing a pair of electrons or photons. The data are in good agreement with the expected background and do not exhibit evidence for large extra dimensions. We set the most restrictive lower limits to date, at the 95% C.L. on the effective Planck scale between 1.0 and 1.4 TeV for several formalisms and numbers of extra dimensions.

  11. Intersection democracy for winding branes and stabilization of extra dimensions

    CERN Document Server

    Rador, Tonguc

    2005-01-01

    We show that, in the context of pure Einstein gravity, a democratic principle for intersection possibilities of branes winding around extra dimensions in a given partitioning yield stabilization, while what the observed space follows is matter-like dust evolution . Here democracy is used in the sense that, in a given decimation of extra dimensions, all possible wrappings and hence all possible intersections are allowed. Generally, the necessary and sufficient condition for this is that the dimensionality $m$ of the observed space dimensions obey $3\\leqm \\le N$ where $N$ is the decimation order of the extra dimensions.

  12. La inquietante extrañeza en el cine

    OpenAIRE

    Antelo, Marcela

    2015-01-01

    La inquietante extrañeza en el cine parte de considerar la experiencia cinematográfica como un acontecimiento de la sensibilidad. La sala oscura proporciona una intimidad con extraños, y el silencio y la oscuridad evocan lo ‘infantil inextinguible’ de la angustia, descubierto por Sigmund Freud, cuando se atreve a penetrar la comarca de la estética y teoriza lo Unheimlich como lo extraño que invade lo familiar. Un afecto estético. Esta tesis muestra que el cine es Unheimlich pues acosa la real...

  13. La inquietante extra??eza en el cine

    OpenAIRE

    Antelo, Marcela

    2015-01-01

    La inquietante extra??eza en el cine parte de considerar la experiencia cinematogr??fica como un acontecimiento de la sensibilidad. La sala oscura proporciona una intimidad con extra??os, y el silencio y la oscuridad evocan lo ???infantil inextinguible??? de la angustia, descubierto por Sigmund Freud, cuando se atreve a penetrar la comarca de la est??tica y teoriza lo Unheimlich como lo extra??o que invade lo familiar. Un afecto est??tico. Esta tesis muestra que el cine es Unheimlich pues aco...

  14. Finite temperature Casimir effect in spacetime with extra compactified dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Teo, L.P. [Faculty of Information Technology, Multimedia University, Jalan Multimedia, Cyberjaya 63100, Selangor Darul Ehsan (Malaysia)], E-mail: lpteo@mmu.edu.my

    2009-02-16

    In this Letter, we derive the explicit exact formulas for the finite temperature Casimir force acting on a pair of parallel plates in the presence of extra compactified dimensions within the framework of Kaluza-Klein theory. Using the piston analysis, we show that at any temperature, the Casimir force due to massless scalar field with Dirichlet boundary conditions on the plates is always attractive and the effect of extra dimensions becomes stronger when the size or number of the extra dimensions increases. These properties are not affected by the explicit geometry and topology of the Kaluza-Klein space.

  15. A new energy source originating from extra dimensions

    Institute of Scientific and Technical Information of China (English)

    Tao Bi-Xiu; Ji Shi-Yin; Li Fang-Qiong

    2004-01-01

    In this work the Einstein gravitational field equations and the Lichnerowicz boundary formalism in the extra dimensions are used to build up our black hole model from 6-dimensional space-time. From the internal stress-energy tensor the solutions with energy levels and semiclassical space-quantization are obtained, which combines with only one metric condition outside the defect. We show a new type of energy source, which originates from extra dimensions. A part of the energy source of quasi-stellar object (QSO) maybe come from extra dimensions in that way. The theoretical arithmetic upper limit is identical to that of the output energy of QSO.

  16. The Endogenous Feedback Network

    DEFF Research Database (Denmark)

    Augustenborg, Claudia Carrara

    2010-01-01

    proposals, it will first be considered the extents of their reciprocal compatibility, tentatively shaping an integrated, theoretical profile of consciousness. A new theory, the Endogenous Feedback Network (EFN) will consequently be introduced which, beside being able to accommodate the main tenets...... of the reviewed theories, appears able to compensate for the explanatory gaps they leave behind. The EFN proposes consciousness as the phenomenon emerging from a distinct network of neural paths broadcasting the neural changes associated to any mental process. It additionally argues for the need to include a 5th...

  17. Portfolio, refleksion og feedback

    Directory of Open Access Journals (Sweden)

    Ane Qvortrup

    2017-08-01

    Full Text Available Denne leder definerer indledningsvist begrebet portfolio og gør rede for anvendelsesmuligheder i en uddannelseskontekst. Dernæst behandles portfoliometodens kvalitet og effekt for læring og undervisning og de centrale begreber refleksion, progression og feedback præsenteres og diskuteres. Herefter listes teknologier, der understøtter portfolioens opbygning og brug og implikationerne forbundet med valg af teknologi diskuteres kort. Afslutningsvist præsenteres temanummerets 5 artikler, der endvidere er inddraget undervejs i lederen som eksemplificering af de præsenterede begreber og teknologier.

  18. Precipitation-Regulated Feedback

    Science.gov (United States)

    Voit, Mark

    2016-07-01

    Star formation in the central galaxies of galaxy clusters appears to be fueled by precipitation of cold clouds out of hot circumgalactic gas via thermal instability. I will present both observational and theoretical support for the precipitation mode in large galaxies and discuss how it can be implemented in cosmological simulations of galaxy evolution. Galaxy cluster cores are unique laboratories for studying the astrophysics of thermal instability and may be teaching us valuable lessons about how feedback works in galaxies spanning the entire mass spectrum.

  19. Models of AGN feedback

    CERN Document Server

    Combes, F

    2014-01-01

    The physical processes responsible of sweeping up the surrounding gas in the host galaxy of an AGN, and able in some circumstances to expel it from the galaxy, are not yet well known. The various mechanisms are briefly reviewed: quasar or radio modes, either momentum-conserving outflows, energy-conserving outflows, or intermediate. They are confronted to observations, to know whether they can explain the M-sigma relation, quench the star formation or whether they can also provide some positive feedback and how the black hole accretion history is related to that of star formation.

  20. Neural regulation of the stress response: glucocorticoid feedback mechanisms

    Directory of Open Access Journals (Sweden)

    J.P. Herman

    2012-04-01

    Full Text Available The mammalian stress response is an integrated physiological and psychological reaction to real or perceived adversity. Glucocorticoids are an important component of this response, acting to redistribute energy resources to both optimize survival in the face of challenge and to restore homeostasis after the immediate challenge has subsided. Release of glucocorticoids is mediated by the hypothalamo-pituitary-adrenal (HPA axis, driven by a neural signal originating in the paraventricular nucleus (PVN. Stress levels of glucocorticoids bind to glucocorticoid receptors in multiple body compartments, including the brain, and consequently have wide-reaching actions. For this reason, glucocorticoids serve a vital function in negative feedback inhibition of their own secretion. Negative feedback inhibition is mediated by a diverse collection of mechanisms, including fast, non-genomic feedback at the level of the PVN, stress-shut-off at the level of the limbic system, and attenuation of ascending excitatory input through destabilization of mRNAs encoding neuropeptide drivers of the HPA axis. In addition, there is evidence that glucocorticoids participate in stress activation via feed-forward mechanisms at the level of the amygdala. Feedback deficits are associated with numerous disease states, underscoring the necessity for adequate control of glucocorticoid homeostasis. Thus, rather than having a single, defined feedback ‘switch’, control of the stress response requires a wide-reaching feedback ‘network’ that coordinates HPA activity to suit the overall needs of multiple body systems.

  1. Haptic gas pedal feedback.

    Science.gov (United States)

    Mulder, M; Mulder, M; van Paassen, M M; Abbink, D A

    2008-11-01

    Active driver support systems either automate a control task or present warnings to drivers when their safety is seriously degraded. In a novel approach, utilising neither automation nor discrete warnings, a haptic gas pedal (accelerator) interface was developed that continuously presents car-following support information, keeping the driver in the loop. This interface was tested in a fixed-base driving simulator. Twenty-one drivers between the ages of 24 and 30 years participated in a driving experiment to investigate the effects of haptic gas pedal feedback on car-following behaviour. Results of the experiment indicate that when haptic feedback was presented to the drivers, some improvement in car-following performance was achieved, while control activity decreased. Further research is needed to investigate the effectiveness of the system in more varied driving conditions. Haptics is an under-used modality in the application of human support interfaces, which usually draw on vision or hearing. This study demonstrates how haptics can be used to create an effective driver support interface.

  2. Metastatic disease of the brain: extra-axial metastases (skull, dura, leptomeningeal) and tumour spread

    Energy Technology Data Exchange (ETDEWEB)

    Maroldi, Roberto; Ambrosi, Claudia; Farina, Davide [University of Brescia, Department of Radiology, Brescia, BS (Italy)

    2005-03-01

    Extra-axial intracranial metastases may arise through several situations. Hematogenous spread to the meninges is the most frequent cause. Direct extension from contiguous extra-cranial neoplasms, secondary invasion of the meninges by calvarium and skull base metastases, and migration along perineural or perivascular structures are less common. Leptomeningeal invasion gives rise to tumour cell dissemination by the cerebrospinal fluid (CSF), eventually leading to neoplastic coating of brain surfaces. Contrast-enhanced magnetic resonance (MR) imaging is complementary to CSF examinations and can be invaluable, detecting up to 50% of false-negative lumbar punctures. MR findings range from diffuse linear leptomeningeal enhancement to multiple enhancing extra-axial nodules, obstructive communicating and non-communicating hydrocephalus. Both calvarial and epidural metastases infrequently transgress the dura, which acts as a barrier against tumour spread. Radionuclide bone studies are still a valuable screening test to detect bone metastases. With computed tomography (CT) and MR, bone metastases extending intracranially and primary dural metastases show the characteristic biconvex shape, usually associated with brain displacement away from the inner table. Although CT is better in detecting skull base erosion, MR is more sensitive and provides more detailed information about dural involvement. Perineural and perivascular spread from head and neck neoplasms require thin-section contrast-enhanced MR. (orig.)

  3. Emotional feedback for mobile devices

    CERN Document Server

    Seebode, Julia

    2015-01-01

    This book investigates the functional adequacy as well as the affective impression made by feedback messages on mobile devices. It presents an easily adoptable experimental setup to examine context effects on various feedback messages, and applies it to auditory, tactile and auditory-tactile feedback messages. This approach provides insights into the relationship between the affective impression and functional applicability of these messages as well as an understanding of the influence of unimodal components on the perception of multimodal feedback messages. The developed paradigm can also be extended to investigate other aspects of context and used to investigate feedback messages in modalities other than those presented. The book uses questionnaires implemented on a Smartphone, which can easily be adopted for field studies to broaden the scope even wider. Finally, the book offers guidelines for the design of system feedback.

  4. Cloud and Star Formation in Disk Galaxy Models with Feedback

    CERN Document Server

    Shetty, Rahul

    2008-01-01

    We include feedback in global hydrodynamic simulations in order to study the star formation properties, and gas structure and dynamics, in models of galactic disks. We extend previous models by implementing feedback in gravitationally bound clouds: momentum is injected at a rate proportional to the star formation rate. This mechanical energy disperses cloud gas back into the surrounding ISM, truncating star formation in a given cloud, and raising the overall level of ambient turbulence. Propagating star formation can however occur as expanding shells collide, enhancing the density and triggering new cloud and star formation. By controlling the momentum injection per massive star and the specific star formation rate in dense gas, we find that the negative effects of high turbulence outweigh the positive ones, and in net feedback reduces the fraction of dense gas and thus the overall star formation rate. The properties of the large clouds that form are not, however, very sensitive to feedback, with cutoff masse...

  5. Kuu plaat : Cardigans "Super Extra Gravity". Plaadid kauplusest Lasering

    Index Scriptorium Estoniae

    2005-01-01

    Heliplaatidest : Cardigans "Super Extra Gravity", Metsatöll "Terast mis hangund me hinge 10218", Ursula "Annamemenõu", Critikal "Chapter One ehk Teine Maitse", Robbie Williams "Intensive Care", Depeche Mode "Playing the Angel"

  6. Extra limit counts for southern sea otter 2016

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The GIS shapefile "Extra limit counts of southern sea otters 2016" is a point layer representing the locations of sea otter sightings that fall outside the...

  7. Probing large extra dimensions with IceCube

    Energy Technology Data Exchange (ETDEWEB)

    Esmaili, Arman [Institute of Convergence Fundamental Studies and School of Liberal Arts, Seoul National University of Science and Technology, Seoul 139-743 (Korea, Republic of); Peres, O.L.G.; Tabrizi, Zahra, E-mail: arman@ipm.ir, E-mail: orlando@ifi.unicamp.br, E-mail: tabrizi.physics@ipm.ir [Instituto de Física Gleb Wataghin - UNICAMP, 13083-859, Campinas, SP (Brazil)

    2014-12-01

    In models with Large Extra Dimensions the smallness of neutrino masses can be naturally explained by introducing gauge singlet fermions which propagate in the bulk. The Kaluza-Klein modes of these fermions appear as towers of sterile neutrino states on the brane. We study the phenomenological consequences of this picture for the high energy atmospheric neutrinos. For this purpose we construct a detailed equivalence between a model with large extra dimensions and a (3+n) scenario consisting of three active and n extra sterile neutrino states, which provides a clear intuitive understanding of Kaluza-Klein modes. Finally, we analyze the collected data of high energy atmospheric neutrinos by IceCube experiment and obtain bounds on the radius of extra dimensions.

  8. Kuu plaat : Cardigans "Super Extra Gravity". Plaadid kauplusest Lasering

    Index Scriptorium Estoniae

    2005-01-01

    Heliplaatidest : Cardigans "Super Extra Gravity", Metsatöll "Terast mis hangund me hinge 10218", Ursula "Annamemenõu", Critikal "Chapter One ehk Teine Maitse", Robbie Williams "Intensive Care", Depeche Mode "Playing the Angel"

  9. ExTrA: Exoplanets in Transit and their Atmospheres

    CERN Document Server

    Bonfils, X; Jocou, L; Wunsche, A; Kern, P; Delboulbé, A; Delfosse, X; Feautrier, P; Forveille, T; Gluck, L; Lafrasse, S; Magnard, Y; Maurel, D; Moulin, T; Murgas, F; Rabou, P; Rochat, S; Roux, A; Stadler, E

    2015-01-01

    The ExTrA facility, located at La Silla observatory, will consist of a near-infrared multi-object spectrograph fed by three 60-cm telescopes. ExTrA will add the spectroscopic resolution to the traditional differential photometry method. This shall enable the fine correction of color-dependent systematics that would otherwise hinder ground-based observations. With both this novel method and an infrared-enabled efficiency, ExTrA aims to find transiting telluric planets orbiting in the habitable zone of bright nearby M dwarfs. It shall have the versatility to do so by running its own independent survey and also by concurrently following-up on the space candidates unveiled by K2 and TESS. The exoplanets detected by ExTrA will be amenable to atmospheric characterisation with VLTs, JWST, and ELTs and could give our first peek into an exo-life laboratory.

  10. Ultra-low-voltage-trigger thyristor for on-chip ESD protection without extra process cost

    Science.gov (United States)

    Yi, Shan; Jun, He; Wenyi, Huang

    2009-07-01

    A new thyristor is proposed and realized in the foundry's 0.18-μm CMOS process for electrostatic discharge (ESD) protection. Without extra mask layers or process steps, the new ultra-low-voltage-trigger thyristor (ULVT thyristor) has a trigger voltage as low as 6.7 V and an ESD robustness exceeding 50 mA/μm, which enables effective ESD protection. Compared with the traditional medium-voltage-trigger thyristor (MVT thyristor), the new structure not only has a lower trigger voltage, but can also provide better ESD protection under both positive and negative ESD zapping conditions.

  11. Ultra-low-voltage-trigger thyristor for on-chip ESD protection without extra process cost

    Energy Technology Data Exchange (ETDEWEB)

    Shan Yi [Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); He Jun; Huang Wenyi, E-mail: iamshanyi@163.co, E-mail: yi.shan@gracesemi.co [Grace Semiconductor Manufacturing Corporation, Shanghai 201203 (China)

    2009-07-15

    A new thyristor is proposed and realized in the foundry's 0.18-{mu}m CMOS process for electrostatic discharge (ESD) protection. Without extra mask layers or process steps, the new ultra-low-voltage-trigger thyristor (ULVT thyristor) has a trigger voltage as low as 6.7 V and an ESD robustness exceeding 50 mA/{mu}m, which enables effective ESD protection. Compared with the traditional medium-voltage-trigger thyristor (MVT thyristor), the new structure not only has a lower trigger voltage, but can also provide better ESD protection under both positive and negative ESD zapping conditions.

  12. [Influenza A H1N1v treated with extra-corporal membrane oxygenation.

    DEFF Research Database (Denmark)

    Jensen, Reinhold; Severinsen, Inge Krogh; Terp, Kim

    2010-01-01

    A 37-year-old woman with body mass index > 30 was admitted to hospital with severe pneumonia due to H1N1v. Thoracic X-ray showed bilateral, diffuse infiltrates. There was no sign of complicating bacterial infection and all microbiological tests of tracheal secretion, blood and urine were negative....... Polymerase chain reaction test for H1N1v was positive until day ten. No mutations were found in the virus. The patient was given oseltamivir tablets and inhalable zanamivir as well as antibiotics. The patient was treated with extra-corporal membrane oxygenation (EcmO) for 12 days followed by ventilator...

  13. [Influenza A H1N1v treated with extra-corporal membrane oxygenation.

    DEFF Research Database (Denmark)

    Jensen, Reinhold; Severinsen, Inge Krogh; Terp, Kim

    2010-01-01

    A 37-year-old woman with body mass index > 30 was admitted to hospital with severe pneumonia due to H1N1v. Thoracic X-ray showed bilateral, diffuse infiltrates. There was no sign of complicating bacterial infection and all microbiological tests of tracheal secretion, blood and urine were negative....... Polymerase chain reaction test for H1N1v was positive until day ten. No mutations were found in the virus. The patient was given oseltamivir tablets and inhalable zanamivir as well as antibiotics. The patient was treated with extra-corporal membrane oxygenation (EcmO) for 12 days followed by ventilator...

  14. Do students profit from feedback?

    OpenAIRE

    Arild Raaheim

    2006-01-01

    Undergraduate students in psychology were given the opportunity to exchange the traditional exam with portfolio assessment. The students received written feedback, by way of a standard feedback form, on two of the three essays of the portfolio. To investigate whether students attend to and act on the feedback, a comparison was made between unofficial marks on the first draft of the first essay and the official marks on the full portfolio at the end of the semester. With approximately 20% of t...

  15. Multiple extra macular branch retinal vein occlusions in hyperhomocysteinemia

    Directory of Open Access Journals (Sweden)

    Abhijit Diwakar Gore

    2014-01-01

    Full Text Available Hyperhomocysteinemia is a well-known modifiable risk factor for thromboembolism. Retinal vascular occlusion in patients having hyperhomocysteinemia is a known entity, particularly in young patients. However, multiple extra macular branch retinal vein occlusion (BRVO is a rare condition, which can be a presentation of this disease. We present a patient who had multiple extra macular BRVO; on complete systemic workup, he was found to have raised homocysteine levels.

  16. Extra-aortic implantable counterpulsation pump in chronic heart failure.

    Science.gov (United States)

    Mitnovetski, Sergei; Almeida, Aubrey A; Barr, Althea; Peters, William S; Milsom, F Paget; Ho, Betty; Smith, Julian A

    2008-06-01

    Extra-aortic counterpulsation for the management of chronic heart failure is a novel approach. We report the use of an extra-aortic implantable counterpulsation pump in the management of a 73-year-old patient with severe heart failure refractory to medical therapy. The implantable counterpulsation pump prolonged his life and greatly improved its quality. The patient lived almost 7 months after the implantation of the device and died of septic complications secondary to gas line infection.

  17. Extra-Abdominal Desmoid Tumors Associated with Familial Adenomatous Polyposis

    Directory of Open Access Journals (Sweden)

    George T. Calvert

    2012-01-01

    Full Text Available Extra-abdominal desmoid tumors are a significant cause of morbidity in patients with familial adenomatous polyposis syndrome. Understanding of the basic biology and natural history of these tumors has increased substantially over the past decade. Accordingly, medical and surgical management of desmoid tumors has also evolved. This paper analyzes recent evidence pertaining to the epidemiology, molecular biology, histopathology, screening, and treatment of extra-abdominal desmoid tumors associated with familial adenomatous polyposis syndrome.

  18. Kaluza-Klein Theory without Extra Dimensions: Curved Clifford Space

    CERN Document Server

    Pavsic, M

    2005-01-01

    A theory in which 16-dimensional curved Clifford space (C-space) provides realization of Kaluza-Klein theory is investigated. No extra dimensions of spacetime are needed: "extra dimensions" are in C-space. It is shown that the covariant Dirac equation in C-space contains Yang-Mills fields of the U(1)xSU(2)xSU(3) group as parts of the generalized spin connection of the C-space.

  19. Scale Factor in Very Early Universe with the Extra Dimensions

    CERN Document Server

    Mohsenzadeh, M

    2010-01-01

    The main goal of this paper is presentation an expanding scenario of 5-dimensional space-time in the very early universe. We introduce the 5-dimensional generalized FRW metric and obtain the evolution of the bulk scale factor with space-like and time-like extra dimensions. It is shown that, additional space-like dimensions can produce an exponentially expansion for the bulk scale factor under repulsive strong gravitational force in the empty very early universe with the extra dimension.

  20. [On mistakes in contemporary literatures of extra points in China].

    Science.gov (United States)

    Huang, Long-Xiang; Huang, You-Min

    2013-06-01

    Contemporary literatures which are taken as the base of literature study of extra points are insufficient and lack of reliability. The foundation of study is very weak. Based on abundant firsthand materials, analyses are made on the major problems of confounded names and locations, unclear quotation and source of reference in the study of contemporary literatures of extra points. Meanwhile, methods and way of thinking for solving the above mentioned problems are discussed in this article as well.