ϕ 4 4 with negative coupling

1985 ◽  
pp. 137-152
Author(s):  
A. Kupiainen
Keyword(s):  
Negative Coupling

scholarly journals INTERACTION BETWEEN DARK ENERGY AND DARK MATTER: OBSERVATIONAL CONSTRAINTS FROM OHD, BAO, CMB AND SNe Ia

2013 ◽  
Vol 22 (14) ◽  
pp. 1350082 ◽  
Author(s):  
SHUO CAO ◽  
NAN LIANG
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Observational Constraints ◽  
Coincidence Problem ◽  
Cosmological Constraints ◽  
Coincidence Index ◽  
Acceleration Of The Universe ◽  
Interaction Term ◽  
Negative Coupling ◽  
The Universe

In order to test if there is energy transfer between dark energy (DE) and dark matter (DM), we investigate cosmological constraints on two forms of nontrivial interaction between the DM sector and the sector responsible for the acceleration of the universe, in light of the newly revised observations including OHD, CMB, BAO and SNe Ia. More precisely, we find the same tendencies for both phenomenological forms of the interaction term Q = 3γHρ, i.e. the parameter γ to be a small number, |γ| ≈ 10-2. However, concerning the sign of the interaction parameter, we observe that γ > 0 when the interaction between dark sectors is proportional to the energy density of dust matter, whereas the negative coupling (γ < 0) is preferred by observations when the interaction term is proportional to DE density. We further discuss two possible explanations to this incompatibility and apply a quantitative criteria to judge the severity of the coincidence problem. Results suggest that the γm IDE model with a positive coupling may alleviate the coincidence problem, since its coincidence index C is smaller than that for the γd IDE model, the interacting quintessence and phantom models by four orders of magnitude.

Correlations Between the DMN and the Smoking Cessation Outcome of a Real-Time fMRI Neurofeedback Supported Exploratory Therapy Approach: Descriptive Statistics on Tobacco-Dependent Patients

2021 ◽  
pp. 155005942110627
Author(s):  
Marco Paolini ◽  
Daniel Keeser ◽  
Boris-Stephan Rauchmann ◽  
Sarah Gschwendtner ◽  
Hannah Jeanty ◽  
...  
Keyword(s):  
Smoking Cessation ◽  
Functional Connectivity ◽  
Real Time ◽  
Smoking Status ◽  
Connectivity Pattern ◽  
Resting State Functional Connectivity ◽  
Correlation Pattern ◽  
Early Withdrawal ◽  
Seed Analysis ◽  
Negative Coupling

The aim of this study was to explore the potential of default mode network (DMN) functional connectivity for predicting the success of smoking cessation in patients with tobacco dependence in the context of a real-time function al MRI (RT-fMRI) neurofeedback (NF) supported therapy. Fifty-four tobacco-dependent patients underwent three RT-fMRI-NF sessions including resting-state functional connectivity (RSFC) runs over a period of 4 weeks during professionally assisted smoking cessation. Patients were randomized into two groups that performed either active NF of an addiction-related brain region or sham NF. After preprocessing, the RSFC baseline data were statistically evaluated using seed-based ROI (SBA) approaches taking into account the smoking status of patients after 3 months (abstinence/relapse). The results of the real study group showed a widespread functional connectivity in the relapse subgroup (n = 10) exceeding the DMN template and mainly low correlations and anticorrelations in the within-seed analysis. In contrast, the connectivity pattern of the abstinence subgroup (n = 8) primarily contained the core DMN in the seed-to-whole-brain analysis and a left lateralized correlation pattern in the within-seed analysis. Calculated Multi-Subject Dictionary Learning (MSDL) matrices showed anticorrelations between DMN regions and salience regions in the abstinence group. Concerning the sham group, results of the relapse subgroup (n = 4) and the abstinence subgroup (n = 6) showed similar trends only in the within-seed analysis. In the setting of a RT-fMRI-NF-assisted therapy, a widespread intrinsic DMN connectivity and a low negative coupling between the DMN and the salience network (SN) in patients with tobacco dependency during early withdrawal may be useful as an early indicator of later therapy nonresponse.

scholarly journals Land–atmosphere feedbacks exacerbate concurrent soil drought and atmospheric aridity

2019 ◽  
Vol 116 (38) ◽  
pp. 18848-18853 ◽  
Author(s):  
Sha Zhou ◽  
A. Park Williams ◽  
Alexis M. Berg ◽  
Benjamin I. Cook ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Vapor Pressure ◽  
High Probability ◽  
Vapor Pressure Deficit ◽  
Cmip5 Models ◽  
Soil Drought ◽  
Global Land ◽  
High Vapor ◽  
Mean Climate ◽  
Negative Coupling

Compound extremes such as cooccurring soil drought (low soil moisture) and atmospheric aridity (high vapor pressure deficit) can be disastrous for natural and societal systems. Soil drought and atmospheric aridity are 2 main physiological stressors driving widespread vegetation mortality and reduced terrestrial carbon uptake. Here, we empirically demonstrate that strong negative coupling between soil moisture and vapor pressure deficit occurs globally, indicating high probability of cooccurring soil drought and atmospheric aridity. Using the Global Land Atmosphere Coupling Experiment (GLACE)-CMIP5 experiment, we further show that concurrent soil drought and atmospheric aridity are greatly exacerbated by land–atmosphere feedbacks. The feedback of soil drought on the atmosphere is largely responsible for enabling atmospheric aridity extremes. In addition, the soil moisture–precipitation feedback acts to amplify precipitation and soil moisture deficits in most regions. CMIP5 models further show that the frequency of concurrent soil drought and atmospheric aridity enhanced by land–atmosphere feedbacks is projected to increase in the 21st century. Importantly, land–atmosphere feedbacks will greatly increase the intensity of both soil drought and atmospheric aridity beyond that expected from changes in mean climate alone.

scholarly journals Inferring correlations associated to causal interactions in brain signals using autoregressive models

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Víctor J. López-Madrona ◽  
Fernanda S. Matias ◽  
Claudio R. Mirasso ◽  
Santiago Canals ◽  
Ernesto Pereda
Keyword(s):  
Causal Link ◽  
Neuronal Population ◽  
Inhibitory Neurons ◽  
Additional Information ◽  
Brain Signals ◽  
Causal Connections ◽  
Negative Effect ◽  
Negative Coupling ◽  
Specific Influence

AbstractThe specific connectivity of a neuronal network is reflected in the dynamics of the signals recorded on its nodes. The analysis of how the activity in one node predicts the behaviour of another gives the directionality in their relationship. However, each node is composed of many different elements which define the properties of the links. For instance, excitatory and inhibitory neuronal subtypes determine the functionality of the connection. Classic indexes such as the Granger causality (GC) quantifies these interactions, but they do not infer into the mechanism behind them. Here, we introduce an extension of the well-known GC that analyses the correlation associated to the specific influence that a transmitter node has over the receiver. This way, the G-causal link has a positive or negative effect if the predicted activity follows directly or inversely, respectively, the dynamics of the sender. The method is validated in a neuronal population model, testing the paradigm that excitatory and inhibitory neurons have a differential effect in the connectivity. Our approach correctly infers the positive or negative coupling produced by different types of neurons. Our results suggest that the proposed approach provides additional information on the characterization of G-causal connections, which is potentially relevant when it comes to understanding interactions in the brain circuits.

scholarly journals Negative Coupling as a Mechanism for Signal Propagation between C2 Domains of Synaptotagmin I

PLoS ONE ◽  
2012 ◽  
Vol 7 (10) ◽  
pp. e46748 ◽  
Author(s):  
Michael E. Fealey ◽  
Jacob W. Gauer ◽  
Sarah C. Kempka ◽  
Katie Miller ◽  
Kamakshi Nayak ◽  
...  
Keyword(s):  
Signal Propagation ◽  
C2 Domains ◽  
Synaptotagmin I ◽  
Negative Coupling

scholarly journals 4D GRAVITY ON A BRANE FROM BULK HIGHER-CURVATURE TERMS

2005 ◽  
Vol 20 (36) ◽  
pp. 2775-2783 ◽  
Author(s):  
OLINDO CORRADINI
Keyword(s):  
Gravity Model ◽  
Brane Tension ◽  
Classical Level ◽  
Consistency Conditions ◽  
Codimension One ◽  
Negative Coupling

We study a gravity model where a tensionful codimension-one three-brane is embedded in a bulk with infinite transverse length. We find that 4D gravity is induced on the brane already at the classical level if we include higher-curvature (Gauss–Bonnet) terms in the bulk. Consistency conditions appear to require a negative brane tension as well as a negative coupling for the higher-curvature terms.

Passive negative coupling in solid-laser resonator

1973 ◽  
Vol 18 (1) ◽  
pp. 18-20
Author(s):  
�. G. Berzing ◽  
Yu. V. Naboikin ◽  
Yu. A. Tiunov ◽  
V. S. Chernov
Keyword(s):  
Laser Resonator ◽  
Negative Coupling ◽  
Solid Laser

scholarly journals Atypical Prefrontal–Amygdala Circuitry Following Childhood Exposure to Abuse: Links With Adolescent Psychopathology

2019 ◽  
Vol 24 (4) ◽  
pp. 411-423 ◽  
Author(s):  
Matthew Peverill ◽  
Margaret A. Sheridan ◽  
Daniel S. Busso ◽  
Katie A. McLaughlin
Keyword(s):  
Emotion Regulation ◽  
Functional Connectivity ◽  
Emotional Abuse ◽  
Adolescent Psychopathology ◽  
Brain Network ◽  
Imaging Data ◽  
Childhood Experiences ◽  
Abuse Severity ◽  
History Of ◽  
Negative Coupling

Adverse childhood experiences have been associated with more negative coupling between the ventromedial prefrontal cortex (vmPFC) and amygdala, a brain network involved in emotion regulation in both children and adults. This pattern may be particularly likely to emerge in individuals exposed to threatening experiences during childhood (e.g., exposure to child abuse), although this has not been examined in prior research. We collected functional magnetic resonance imaging data on 57 adolescents during an emotion regulation task. Greater negative functional connectivity between vmPFC and amygdala occurred during viewing of negative compared to neutral images. This vmPFC-amygdala task-related functional connectivity was more negative in adolescents exposed to physical, sexual, or emotional abuse than those without a history of maltreatment and was associated with abuse severity. This pattern of more negative functional connectivity was associated with higher levels of externalizing psychopathology concurrently and 2 years later. Greater negative connectivity in the vmPFC-amygdala network during passive viewing of negative images may reflect disengagement of regulatory responses from vmPFC in situations eliciting strong amygdala reactivity, potentially due to stronger appraisals of threat in children exposed to early threatening environments. This pattern may be adaptive in the short term but place adolescents at higher risk of psychopathology later in life.

scholarly journals Placebo-induced pain reduction is associated with negative coupling between brain networks at rest

NeuroImage ◽  
2020 ◽  
Vol 219 ◽  
pp. 117024
Author(s):  
Isabella C. Wagner ◽  
Markus Rütgen ◽  
Allan Hummer ◽  
Christian Windischberger ◽  
Claus Lamm
Keyword(s):  
Brain Networks ◽  
Pain Reduction ◽  
Negative Coupling
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