contrast avoidance model: Topics by Science.gov

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A novel theory of experiential avoidance in generalized anxiety disorder: A review and synthesis of research supporting a contrast avoidance model of worry☆,☆☆

PubMed Central

Newman, Michelle G.; Llera, Sandra J.

2011-01-01

An important emphasis of the literature on generalized anxiety disorder (GAD) has been to achieve a greater understanding of the function of emotion (e.g., avoidance, dysregulation) in the etiology and maintenance of this disorder. The purpose of the following paper is to propose a new way of conceptualizing emotional sequelae in GAD by detailing the Contrast Avoidance Model of Worry. In presenting this model, we review theory and data that led to our current position, which is that individuals with GAD are more sensitive to feeling emotionally vulnerable to unexpected negative events, and that worry (the key pathological feature of GAD) is employed to prolong and maintain a negative emotional state thereby avoiding an unexpected negative emotional shift, or contrast experience. We also discuss implications for treatment given the presence of a new target for emotional exposure techniques. Finally, we establish the Contrast Avoidance Model within the framework of extant theories and models of pathogenic processes of GAD. PMID:21334285
Physiological and neural correlates of worry and rumination: Support for the contrast avoidance model of worry.

PubMed

Steinfurth, Elisa C K; Alius, Manuela G; Wendt, Julia; Hamm, Alfons O

2017-02-01

The current experiments tested neural and physiological correlates of worry and rumination in comparison to thinking about neutral events. According to the avoidance model-stating that worry is a strategy to reduce intense emotions-physiological and neurobiological activity during worried thinking should not differ from activation during neutral thinking. According to the contrast avoidance model-stating that worry is a strategy to reduce abrupt shifts of emotions-activity should be increased. To test these competing models, we induced worry and neutral thinking in healthy participants using personal topics. A rumination condition was added to investigate the specificity of changes induced by the mental process. Two experiments were conducted assessing the effects on different response levels: (1) neural activation using fMRI, and (2) physiological response mobilization using startle and autonomic measures. During worry, participants showed a potentiated startle response and BOLD activity indicative of emotional network activation. These data partly support the contrast avoidance model of worry. Both mental processes showed elevated activity in a common network referred to as default network indicating self-referential activity. © 2016 Society for Psychophysiological Research.
Rethinking the role of worry in generalized anxiety disorder: evidence supporting a model of emotional contrast avoidance.

PubMed

Llera, Sandra J; Newman, Michelle G

2014-05-01

The Contrast Avoidance model (Newman & Llera, 2011) proposes that individuals with generalized anxiety disorder (GAD) are hypersensitive to sharp upward shifts in negative emotion that typically accompany negative events, and use worry to maintain sustained intrapersonal negativity in an attempt to avoid these shifts. Although research shows that worry increases negative emotionality and mutes further emotional reactivity to a stressor when compared to the worry period (e.g., Llera & Newman, 2010), no study has tracked changes in negative emotionality from baseline to worry inductions followed by a range of emotional exposures. Further, no study has yet assessed participants' subjective appraisals of prior worry on helping to cope with such exposures. The present study tested the main tenets of the Contrast Avoidance model by randomly assigning participants with GAD (n=48) and nonanxious controls (n=47) to experience worry, relaxation, and neutral inductions prior to sequential exposure to fearful, sad, and humorous film clips. Both physiological (nonspecific skin conductance responses [NS-SCRs]) and self-reported emotional changes were observed. Results indicated that worry boosted negative emotionality from baseline, which was sustained across negative exposures, whereas low negative emotionality during relaxation and neutral inductions allowed for sharp increases in response to exposures. Furthermore, GAD participants found worry to be more helpful than other conditions in coping with exposures, whereas control participants reported the opposite pattern. Results provide preliminary support for the Contrast Avoidance model. This suggests that treatment should focus on underlying avoidance patterns before attempting to reduce worry behavior. Copyright © 2014. Published by Elsevier Ltd.
Development and validation of two measures of emotional contrast avoidance: The contrast avoidance questionnaires.

PubMed

Llera, Sandra J; Newman, Michelle G

2017-06-01

The Contrast Avoidance (CA) model (Newman & Llera, 2011) proposed that individuals with generalized anxiety disorder (GAD) fear sharp emotional shifts (or contrasts), such as the shift from a pleasant or neutral state to one of sudden distress following a negative event. Further, the model suggests that chronic worry is employed by those with GAD to sustain negative emotionality as a means to avoid sudden shifts into negativity. The model has received empirical support; however, no validated measure exists to assess CA tendencies. In this paper we developed and tested two measures of CA: one focusing on worry, and another examining broader mechanisms of CA that could be used test whether CA is applicable to other disorders. In Study 1, Part 1, we used 3 samples of participants (each N=410) to perform item reduction, exploratory factor analysis, and confirmatory factor analysis. In Study 1, Part 2, we performed tests of construct validity. In Study 2, we used a new sample (N=126) to determine test-retest reliability. All data point to the strong psychometric properties of the CA questionnaires and their relationship to GAD. Both measures distinguished between participants reporting clinical levels of GAD symptoms and nonanxious controls, demonstrating their utility as complementary measures of CA tendencies. Copyright © 2017 Elsevier Ltd. All rights reserved.
Prospective Investigation of the Contrast Avoidance Model of Generalized Anxiety and Worry.

PubMed

Crouch, Tara A; Lewis, Jamie A; Erickson, Thane M; Newman, Michelle G

2017-07-01

The factors that maintain generalized anxiety disorder (GAD) symptoms and worry over time are not entirely clear. The Contrast Avoidance Model (CAM) postulates that individuals at risk for pathological worry and GAD symptoms uniquely fear emotional shifts from neutral or positive emotions into negative emotional states, and consequently use worry to maintain negative emotion in order to avoid shifts or blunt the effect of negative contrasts. This model has received support in laboratory experiments, but has not been investigated prospectively in the naturalistic context of daily life. The present study tested the CAM in a longitudinal experience sampling study with a subclinical sample. Participants selected to represent a broad range of symptoms (N = 92) completed baseline measures of GAD and depression symptoms, and eight weekly assessments of worry, experiences of negative emotional contrasts during their worst event of the week, and situation-specific negative emotion. Consistent with the CAM, GAD symptoms prospectively predicted higher endorsement of negative contrast experiences as worst events, independent of depression symptoms. Unsurprisingly, higher negative contrasts predicted higher negative emotion. However, both higher baseline GAD symptoms and weekly worry uniquely moderated (reduced) this relationship, providing consistent support for the idea that worry may blunt the emotional effects of contrasts. Depression symptoms did not have the same moderating effect. These findings support the CAM in an ecologically valid context. Copyright © 2016. Published by Elsevier Ltd.
Worry and Generalized Anxiety Disorder: A Review and Theoretical Synthesis of Evidence on Nature, Etiology, Mechanisms, and Treatment

PubMed Central

Newman, Michelle G.; Llera, Sandra J.; Erickson, Thane M.; Przeworski, Amy; Castonguay, Louis G.

2016-01-01

Generalized anxiety disorder (GAD) is associated with substantial personal and societal cost yet is the least successfully treated of the anxiety disorders. In this review, research on clinical features, boundary issues, and naturalistic course, as well as risk factors and maintaining mechanisms (cognitive, biological, neural, interpersonal, and developmental), are presented. A synthesis of these data points to a central role of emotional hyperreactivity, sensitivity to contrasting emotions, and dysfunctional attempts to cope with strong emotional shifts via worry. Consistent with the Contrast Avoidance model, evidence shows that worry evokes and sustains negative affect, thereby precluding sharp increases in negative emotion. We also review current treatment paradigms and suggest how the Contrast Avoidance model may help to target key fears and avoidance tendencies that serve to maintain pathology in GAD. PMID:23537486
Business models and leadership styles in small medical device and bio-science businesses--examples in a region and their implications.

PubMed

Williams, D J; Hourd, P C

2004-01-01

This paper reviews the leadership styles and business models found in small technologically based businesses operating in the healthcare sector within one of the UK regions, the East Midlands. The most frequently encountered business model strands were 1) mixed economies: that fund development with service income; cross-sectoral product portfolios; and decoupled business portfolios led by a single entrepreneur and 2) scale sensitive "stay small" models including the avoidance of venture capital; "early exit"; and virtual business strands. There was found to be little correlation between leadership style and business model for the small number of businesses surveyed. The avoidance of venture capital is in direct contrast to adjacent regions.
Per Aspera ad Astra: Through Complex Population Modeling to Predictive Theory.

PubMed

Topping, Christopher J; Alrøe, Hugo Fjelsted; Farrell, Katharine N; Grimm, Volker

2015-11-01

Population models in ecology are often not good at predictions, even if they are complex and seem to be realistic enough. The reason for this might be that Occam's razor, which is key for minimal models exploring ideas and concepts, has been too uncritically adopted for more realistic models of systems. This can tie models too closely to certain situations, thereby preventing them from predicting the response to new conditions. We therefore advocate a new kind of parsimony to improve the application of Occam's razor. This new parsimony balances two contrasting strategies for avoiding errors in modeling: avoiding inclusion of nonessential factors (false inclusions) and avoiding exclusion of sometimes-important factors (false exclusions). It involves a synthesis of traditional modeling and analysis, used to describe the essentials of mechanistic relationships, with elements that are included in a model because they have been reported to be or can arguably be assumed to be important under certain conditions. The resulting models should be able to reflect how the internal organization of populations change and thereby generate representations of the novel behavior necessary for complex predictions, including regime shifts.
Neural correlates of alcohol-approach bias in alcohol addiction: the spirit is willing but the flesh is weak for spirits.

PubMed

Wiers, Corinde E; Stelzel, Christine; Park, Soyoung Q; Gawron, Christiane K; Ludwig, Vera U; Gutwinski, Stefan; Heinz, Andreas; Lindenmeyer, Johannes; Wiers, Reinout W; Walter, Henrik; Bermpohl, Felix

2014-02-01

Behavioral studies have shown an alcohol-approach bias in alcohol-dependent patients: the automatic tendency to faster approach than avoid alcohol compared with neutral cues, which has been associated with craving and relapse. Although this is a well-studied psychological phenomenon, little is known about the brain processes underlying automatic action tendencies in addiction. We examined 20 alcohol-dependent patients and 17 healthy controls with functional magnetic resonance imaging (fMRI), while performing an implicit approach-avoidance task. Participants pushed and pulled pictorial cues of alcohol and soft-drink beverages, according to a content-irrelevant feature of the cue (landscape/portrait). The critical fMRI contrast regarding the alcohol-approach bias was defined as (approach alcohol>avoid alcohol)>(approach soft drink>avoid soft drink). This was reversed for the avoid-alcohol contrast: (avoid alcohol>approach alcohol)>(avoid soft drink>approach soft drink). In comparison with healthy controls, alcohol-dependent patients had stronger behavioral approach tendencies for alcohol cues than for soft-drink cues. In the approach, alcohol fMRI contrast patients showed larger blood-oxygen-level-dependent responses in the nucleus accumbens and medial prefrontal cortex, regions involved in reward and motivational processing. In alcohol-dependent patients, alcohol-craving scores were positively correlated with activity in the amygdala for the approach-alcohol contrast. The dorsolateral prefrontal cortex was not activated in the avoid-alcohol contrast in patients vs controls. Our data suggest that brain regions that have a key role in reward and motivation are associated with the automatic alcohol-approach bias in alcohol-dependent patients.
Quintessential inflation with α-attractors

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

Dimopoulos, Konstantinos; Owen, Charlotte, E-mail: k.dimopoulos1@lancaster.ac.uk, E-mail: c.owen@lancaster.ac.uk

2017-06-01

A novel approach to quintessential inflation model building is studied, within the framework of α-attractors, motivated by supergravity theories. Inflationary observables are in excellent agreement with the latest CMB observations, while quintessence explains the dark energy observations without any fine-tuning. The model is kept intentionally minimal, avoiding the introduction of many degrees of freedom, couplings and mass scales. In stark contrast to ΛCDM, for natural values of the parameters, the model attains transient accelerated expansion, which avoids the future horizon problem, while it maintains the field displacement mildly sub-Planckian such that the flatness of the quintessential tail is not liftedmore » by radiative corrections and violations of the equivalence principle (fifth force) are under control. In particular, the required value of the cosmological constant is near the eletroweak scale. Attention is paid to the reheating of the Universe, which avoids gravitino overproduction and respects nucleosynthesis constraints. Kination is treated in a model independent way. A spike in gravitational waves, due to kination, is found not to disturb nucleosynthesis as well.« less
Quintessential inflation with α-attractors

NASA Astrophysics Data System (ADS)

Dimopoulos, Konstantinos; Owen, Charlotte

2017-06-01

A novel approach to quintessential inflation model building is studied, within the framework of α-attractors, motivated by supergravity theories. Inflationary observables are in excellent agreement with the latest CMB observations, while quintessence explains the dark energy observations without any fine-tuning. The model is kept intentionally minimal, avoiding the introduction of many degrees of freedom, couplings and mass scales. In stark contrast to ΛCDM, for natural values of the parameters, the model attains transient accelerated expansion, which avoids the future horizon problem, while it maintains the field displacement mildly sub-Planckian such that the flatness of the quintessential tail is not lifted by radiative corrections and violations of the equivalence principle (fifth force) are under control. In particular, the required value of the cosmological constant is near the eletroweak scale. Attention is paid to the reheating of the Universe, which avoids gravitino overproduction and respects nucleosynthesis constraints. Kination is treated in a model independent way. A spike in gravitational waves, due to kination, is found not to disturb nucleosynthesis as well.
Patterns in the English language: phonological networks, percolation and assembly models

NASA Astrophysics Data System (ADS)

Stella, Massimo; Brede, Markus

2015-05-01

In this paper we provide a quantitative framework for the study of phonological networks (PNs) for the English language by carrying out principled comparisons to null models, either based on site percolation, randomization techniques, or network growth models. In contrast to previous work, we mainly focus on null models that reproduce lower order characteristics of the empirical data. We find that artificial networks matching connectivity properties of the English PN are exceedingly rare: this leads to the hypothesis that the word repertoire might have been assembled over time by preferentially introducing new words which are small modifications of old words. Our null models are able to explain the ‘power-law-like’ part of the degree distributions and generally retrieve qualitative features of the PN such as high clustering, high assortativity coefficient and small-world characteristics. However, the detailed comparison to expectations from null models also points out significant differences, suggesting the presence of additional constraints in word assembly. Key constraints we identify are the avoidance of large degrees, the avoidance of triadic closure and the avoidance of large non-percolating clusters.
The relationship of work avoidance and learning goals to perceived competence, externality and meaning.

PubMed

Seifert, T L; O'Keefe, B A

2001-03-01

Motivational researchers have suggested that work avoidance may be an academic goal in which students seek to minimise the amount of work they do in school. Additionally, research has also suggested that emotions may be catalysts for goals. This study examined the relationship between emotions and learning or work avoidance goals. Do emotions explain goals? The participants were 512 senior high school students in Eastern Canada. Students completed a survey assessing motivation related constructs. A structural equation model was postulated in which students' affect predicted learning goals and work avoidant goals. A cluster analysis of affect scores was performed followed by between-group and within-group contrasts of goal scores. The structural equation model suggested that a sense of competence and control were predictive of a learning goal while lack of meaning was related to work avoidance. The cluster analysis showed that confidence and control were associated with a learning goal but that a sense of inadequacy, lack of control or lack of meaning could give rise to work avoidance. Emotions seem to be directly linked to goals. Teachers who foster feelings of self-assuredness will be helping students develop learning goals. Students who feel less competent, bored or have little control will adopt work avoidant goals.
Use of a decision-analytic model to support the use of a new oral US contrast agent in patients with abdominal pain.

PubMed

Bree, R L; Arnold, R J; Pettit, K G; Kaniecki, D J; O'haeri, C; LaFrance, N D; Toaff, A L

2001-03-01

The authors performed this study to compare the cost and diagnostic abilities of ultrasound (US) performed with and without the use of an oral contrast material recently approved by the U.S. Food and Drug Administration. An interactive decision-analytic model was constructed to compare US performed with and without contrast material (SonoRx; Bracco Diagnostics) for the evaluation of patients with abdominal pain who were suspected of having pancreatic disease. The model considered all resources that might be used to evaluate a patient suspected of having pancreatic disease (eg, US, computed tomography [CT], endoscopic retrograde cholangiopancreatography, fine-needle aspiration biopsy, and open biopsy). The literature and an expert panel were the clinical data sources. Cost estimates were based on Medicare and non-Medicare reimbursements. The primary cost-effectiveness measure was the cost to achieve a diagnosis. SonoRx-enhanced US was less expensive than unenhanced US ($714 vs $808, respectively, with Medicare costs; $1,612 vs $1,878, respectively, with non-Medicare costs) and as effective (0.785 vs 0.782, respectively). SonoRx-enhanced US was more cost-effective than unenhanced US ($909 vs $1,034, respectively, with Medicare costs; $2,052 vs $2,401, respectively, with non-Medicare costs). This relationship was maintained throughout extensive sensitivity analyses. SonoRx-enhanced US is more cost-effective than unenhanced US, primarily because it avoids the need for CT. CT may be avoided owing to the higher probability of obtaining optimal US scans with oral contrast material.
A Bio-inspired Collision Avoidance Model Based on Spatial Information Derived from Motion Detectors Leads to Common Routes

PubMed Central

Bertrand, Olivier J. N.; Lindemann, Jens P.; Egelhaaf, Martin

2015-01-01

Avoiding collisions is one of the most basic needs of any mobile agent, both biological and technical, when searching around or aiming toward a goal. We propose a model of collision avoidance inspired by behavioral experiments on insects and by properties of optic flow on a spherical eye experienced during translation, and test the interaction of this model with goal-driven behavior. Insects, such as flies and bees, actively separate the rotational and translational optic flow components via behavior, i.e. by employing a saccadic strategy of flight and gaze control. Optic flow experienced during translation, i.e. during intersaccadic phases, contains information on the depth-structure of the environment, but this information is entangled with that on self-motion. Here, we propose a simple model to extract the depth structure from translational optic flow by using local properties of a spherical eye. On this basis, a motion direction of the agent is computed that ensures collision avoidance. Flying insects are thought to measure optic flow by correlation-type elementary motion detectors. Their responses depend, in addition to velocity, on the texture and contrast of objects and, thus, do not measure the velocity of objects veridically. Therefore, we initially used geometrically determined optic flow as input to a collision avoidance algorithm to show that depth information inferred from optic flow is sufficient to account for collision avoidance under closed-loop conditions. Then, the collision avoidance algorithm was tested with bio-inspired correlation-type elementary motion detectors in its input. Even then, the algorithm led successfully to collision avoidance and, in addition, replicated the characteristics of collision avoidance behavior of insects. Finally, the collision avoidance algorithm was combined with a goal direction and tested in cluttered environments. The simulated agent then showed goal-directed behavior reminiscent of components of the navigation behavior of insects. PMID:26583771
The relationship between wave and geometrical optics models of coded aperture type x-ray phase contrast imaging systems

PubMed Central

Munro, Peter R.T.; Ignatyev, Konstantin; Speller, Robert D.; Olivo, Alessandro

2013-01-01

X-ray phase contrast imaging is a very promising technique which may lead to significant advancements in medical imaging. One of the impediments to the clinical implementation of the technique is the general requirement to have an x-ray source of high coherence. The radiation physics group at UCL is currently developing an x-ray phase contrast imaging technique which works with laboratory x-ray sources. Validation of the system requires extensive modelling of relatively large samples of tissue. To aid this, we have undertaken a study of when geometrical optics may be employed to model the system in order to avoid the need to perform a computationally expensive wave optics calculation. In this paper, we derive the relationship between the geometrical and wave optics model for our system imaging an infinite cylinder. From this model we are able to draw conclusions regarding the general applicability of the geometrical optics approximation. PMID:20389424
The relationship between wave and geometrical optics models of coded aperture type x-ray phase contrast imaging systems.

PubMed

Munro, Peter R T; Ignatyev, Konstantin; Speller, Robert D; Olivo, Alessandro

2010-03-01

X-ray phase contrast imaging is a very promising technique which may lead to significant advancements in medical imaging. One of the impediments to the clinical implementation of the technique is the general requirement to have an x-ray source of high coherence. The radiation physics group at UCL is currently developing an x-ray phase contrast imaging technique which works with laboratory x-ray sources. Validation of the system requires extensive modelling of relatively large samples of tissue. To aid this, we have undertaken a study of when geometrical optics may be employed to model the system in order to avoid the need to perform a computationally expensive wave optics calculation. In this paper, we derive the relationship between the geometrical and wave optics model for our system imaging an infinite cylinder. From this model we are able to draw conclusions regarding the general applicability of the geometrical optics approximation.
It depends: Approach and avoidance reactions to emotional expressions are influenced by the contrast emotions presented in the task.

PubMed

Paulus, Andrea; Wentura, Dirk

2016-02-01

Studies examining approach and avoidance reactions to emotional expressions have yielded conflicting results. For example, expressions of anger have been reported to elicit approach reactions in some studies but avoidance reactions in others. Nonetheless, the results were often explained by the same general underlying process, namely the influence that the social message signaled by the expression has on motivational responses. It is therefore unclear which reaction is triggered by which emotional expression, and which underlying process is responsible for these reactions. In order to address this issue, we examined the role of a potential moderator on approach and avoidance reactions to emotional expressions, namely the contrast emotion used in the task. We believe that different approach and avoidance reactions occur depending on the congruency or incongruency of the evaluation of the 2 emotions presented in the task. The results from a series of experiments supported these assumptions: Negative emotional expressions (anger, fear, sadness) elicited avoidance reactions if contrasted with expressions of happiness. However, if contrasted with a different negative emotional expression, anger and sadness triggered approach reactions and fear activated avoidance reactions. Importantly, these results also emerged if the emotional expression was not task-relevant. We propose that approach and avoidance reactions to emotional expressions are triggered by their evaluation if the 2 emotions presented in a task differ in evaluative connotation. If they have the same evaluative connotation, however, reactions are determined by their social message. (PsycINFO Database Record (c) 2016 APA, all rights reserved).
Masculine Norms, Avoidant Coping, Asian Values and Depression among Asian American Men.

PubMed

Iwamoto, Derek Kenji; Liao, Liang; Liu, William Ming

2010-01-01

Contrary to the "model minority" myth, growing research indicates that the rates of mental health problems among Asian Americans may be higher than initially assumed. This study seeks to add to the scant knowledge regarding the mental health of Asian American men by examining the role of masculine norms, coping and cultural values in predicting depression among this population (N=149). Results reveal that Asian American men who used avoidant coping strategies and endorsed the masculine norm Dominance reported higher levels of depressive symptoms. In contrast, endorsing Winning masculine norms was associated to lower levels of depressive symptoms. Findings suggest that adherence to masculine norms and avoidant coping strategies play a salient role in the mental health of Asian American men.
Stressors and anxiety in dementia caregiving: multiple mediation analysis of rumination, experiential avoidance, and leisure.

PubMed

Romero-Moreno, R; Losada, A; Márquez-González, M; Mausbach, B T

2016-11-01

Despite the robust associations between stressors and anxiety in dementia caregiving, there is a lack of research examining which factors contribute to explain this relationship. This study was designed to test a multiple mediation model of behavioral and psychological symptoms of dementia (BPSD) and anxiety that proposes higher levels of rumination and experiential avoidance and lower levels of leisure satisfaction as potential mediating variables. The sample consisted of 256 family caregivers. In order to test a simultaneously parallel multiple mediation model of the BPSD to anxiety pathway, a PROCESS method was used and bias-corrected and accelerated bootstrapping method was used to test confidence intervals. Higher levels of stressors significantly predicted anxiety. Greater stressors significantly predicted higher levels of rumination and experiential avoidance, and lower levels of leisure satisfaction. These three coping variables significantly predicted anxiety. Finally, rumination, experiential avoidance, and leisure satisfaction significantly mediated the link between stressors and anxiety. The explained variance for the final model was 47.09%. Significant contrasts were found between rumination and leisure satisfaction, with rumination being a significantly higher mediator. The results suggest that caregivers' experiential avoidance, rumination, and leisure satisfaction may function as mechanisms through which BPSD influence on caregivers' anxiety. Training caregivers in reducing their levels of experiential avoidance and rumination by techniques that foster their ability of acceptance of their negative internal experiences, and increase their level of leisure satisfaction, may be helpful to reduce their anxiety symptoms developed by stressors.

Experiential avoidance as an emotion regulatory function: an empirical analysis of experiential avoidance in relation to behavioral avoidance, cognitive reappraisal, and response suppression.

PubMed

Wolgast, Martin; Lundh, Lars-Gunnar; Viborg, Gardar

2013-01-01

The purpose of the present study was to empirically test the suggestion that experiential avoidance in an emotion regulation context is best understood as an emotion regulatory function of topographically distinct strategies. To do this we examined whether a measure of experiential avoidance could statistically account for the effects of emotion regulation strategies intervening at different points of the emotion-generative process as conceptualized by Gross' (1998) process model of emotion regulation. The strategies under examination were behavioral avoidance, cognitive reappraisal, and response suppression. The specific hypotheses to be tested were (1) that behavioral avoidance, cognitive reappraisal, and response suppression would statistically mediate the differences in measures of psychological well-being between a clinical and nonclinical sample, but that (2) these indirect effects would be reduced to nonsignificant levels when controlling for differences in experiential avoidance. The results provide clear support for the first hypothesis with regard to all the studied strategies. In contrast to the second hypothesis, the results showed the predicted outcome pattern only for the response-focused strategy "response suppression" and not for cognitive reappraisal or behavioral avoidance. The results are interpreted and discussed in relation to theories on experiential avoidance and emotion regulation.
Ribbon synapses compute temporal contrast and encode luminance in retinal rod bipolar cells

PubMed Central

Oesch, Nicholas W.; Diamond, Jeffrey S.

2011-01-01

Contrast is computed throughout the nervous system to encode changing inputs efficiently. The retina encodes luminance and contrast over a wide range of visual conditions and so must adapt its responses to maintain sensitivity and avoid saturation. Here we show how one type of adaptation allows individual synapses to compute contrast and encode luminance in biphasic responses to step changes in light levels. Light-evoked depletion of the readily releasable vesicle pool (RRP) at rod bipolar cell (RBC) ribbon synapses in rat retina limits the dynamic range available to encode transient but not sustained responses, thereby allowing the transient and sustained components of release to compute temporal contrast and encode mean light levels, respectively. A release/replenishment model shows that a single, homogeneous pool of synaptic vesicles is sufficient to generate this behavior and reveals that the dominant mechanism shaping the biphasic contrast/luminance response is the partial depletion of the RRP. PMID:22019730
Parsing the Role of the Hippocampus in Approach-Avoidance Conflict.

PubMed

Loh, Eleanor; Kurth-Nelson, Zeb; Berron, David; Dayan, Peter; Duzel, Emrah; Dolan, Ray; Guitart-Masip, Marc

2017-01-01

The hippocampus plays a central role in the approach-avoidance conflict that is central to the genesis of anxiety. However, its exact functional contribution has yet to be identified. We designed a novel gambling task that generated approach-avoidance conflict while controlling for spatial processing. We fit subjects' behavior using a model that quantified the subjective values of choice options, and recorded neural signals using functional magnetic resonance imaging (fMRI). Distinct functional signals were observed in anterior hippocampus, with inferior hippocampus selectively recruited when subjects rejected a gamble, to a degree that covaried with individual differences in anxiety. The superior anterior hippocampus, in contrast, uniquely demonstrated value signals that were potentiated in the context of approach-avoidance conflict. These results implicate the anterior hippocampus in behavioral avoidance and choice monitoring, in a manner relevant to understanding its role in anxiety. Our findings highlight interactions between subregions of the hippocampus as an important focus for future study. © The Author 2016. Published by Oxford University Press.
Parsing the Role of the Hippocampus in Approach–Avoidance Conflict

PubMed Central

Loh, Eleanor; Kurth-Nelson, Zeb; Berron, David; Dayan, Peter; Duzel, Emrah; Dolan, Ray; Guitart-Masip, Marc

2017-01-01

Abstract The hippocampus plays a central role in the approach–avoidance conflict that is central to the genesis of anxiety. However, its exact functional contribution has yet to be identified. We designed a novel gambling task that generated approach–avoidance conflict while controlling for spatial processing. We fit subjects’ behavior using a model that quantified the subjective values of choice options, and recorded neural signals using functional magnetic resonance imaging (fMRI). Distinct functional signals were observed in anterior hippocampus, with inferior hippocampus selectively recruited when subjects rejected a gamble, to a degree that covaried with individual differences in anxiety. The superior anterior hippocampus, in contrast, uniquely demonstrated value signals that were potentiated in the context of approach–avoidance conflict. These results implicate the anterior hippocampus in behavioral avoidance and choice monitoring, in a manner relevant to understanding its role in anxiety. Our findings highlight interactions between subregions of the hippocampus as an important focus for future study. PMID:27993819
Formation of Bragg band gaps in anisotropic phononic crystals analyzed with the empty lattice model

DOE PAGES

Wang, Yan -Feng; Maznev, Alexei; Laude, Vincent

2016-05-11

Bragg band gaps of phononic crystals generally, but not always, open at Brillouin zone boundaries. The commonly accepted explanation stems from the empty lattice model: assuming a small material contrast between the constituents of the unit cell, avoided crossings in the phononic band structure appear at frequencies and wavenumbers corresponding to band intersections; for scalar waves the lowest intersections coincide with boundaries of the first Brillouin zone. However, if a phononic crystal contains elastically anisotropic materials, its overall symmetry is not dictated solely by the lattice symmetry. We construct an empty lattice model for phononic crystals made of isotropic andmore » anisotropic materials, based on their slowness curves. We find that, in the anisotropic case, avoided crossings generally do not appear at the boundaries of traditionally defined Brillouin zones. Furthermore, the Bragg "planes" which give rise to phononic band gaps, are generally not flat planes but curved surfaces. Lastly, the same is found to be the case for avoided crossings between shear (transverse) and longitudinal bands in the isotropic case.« less
Formation of Bragg band gaps in anisotropic phononic crystals analyzed with the empty lattice model

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

Wang, Yan -Feng; Maznev, Alexei; Laude, Vincent

Bragg band gaps of phononic crystals generally, but not always, open at Brillouin zone boundaries. The commonly accepted explanation stems from the empty lattice model: assuming a small material contrast between the constituents of the unit cell, avoided crossings in the phononic band structure appear at frequencies and wavenumbers corresponding to band intersections; for scalar waves the lowest intersections coincide with boundaries of the first Brillouin zone. However, if a phononic crystal contains elastically anisotropic materials, its overall symmetry is not dictated solely by the lattice symmetry. We construct an empty lattice model for phononic crystals made of isotropic andmore » anisotropic materials, based on their slowness curves. We find that, in the anisotropic case, avoided crossings generally do not appear at the boundaries of traditionally defined Brillouin zones. Furthermore, the Bragg "planes" which give rise to phononic band gaps, are generally not flat planes but curved surfaces. Lastly, the same is found to be the case for avoided crossings between shear (transverse) and longitudinal bands in the isotropic case.« less
Masculine Norms, Avoidant Coping, Asian Values and Depression among Asian American Men

PubMed Central

Iwamoto, Derek Kenji; Liao, Liang; Liu, William Ming

2010-01-01

Contrary to the “model minority” myth, growing research indicates that the rates of mental health problems among Asian Americans may be higher than initially assumed. This study seeks to add to the scant knowledge regarding the mental health of Asian American men by examining the role of masculine norms, coping and cultural values in predicting depression among this population (N=149). Results reveal that Asian American men who used avoidant coping strategies and endorsed the masculine norm Dominance reported higher levels of depressive symptoms. In contrast, endorsing Winning masculine norms was associated to lower levels of depressive symptoms. Findings suggest that adherence to masculine norms and avoidant coping strategies play a salient role in the mental health of Asian American men. PMID:20657794
Physical activity during work and leisure show contrasting associations with fear-avoidance beliefs: cross-sectional study among more than 10,000 wage earners of the general working population.

PubMed

Tribian, Annika; Vinstrup, Jonas; Sundstrup, Emil; Jay, Kenneth; Bös, Klaus; Andersen, Lars L

2018-01-26

The association between different types of physical activity and fear-avoidance beliefs remains unclear. This study investigates the association between work-related and leisure-time physical activity with fear-avoidance beliefs in the general working population. Currently employed wage earners (n=10,427) from the 2010 round of the Danish Work Environment Cohort Study replied to questions about work, lifestyle and health. General linear models controlling for lifestyle, psychosocial work factors, education, pain, medication-use and chronic diseases tested associations of work-related and leisure-time physical activity (explanatory variables) with fear-avoidance beliefs (outcome variable, scale 0-100). The level of fear-avoidance was 41.7 (SD 27.3), 38.0 (SD 26.9) and 54.3 (SD 27.7) among the general working population, a subgroup of pain-free individuals, and a subgroup with back disease, respectively. In the general working population, the level of fear-avoidance among those with low, moderate and high physical activity during leisure were 47 [95% confidence intervals (CI) 45-49], 44 (95% CI 42-46) and 43 (95% CI 41-45), and physical activity at work were 40 (95% CI 39-42), 44 (95% CI 42-46) and 49 (95% CI 48-51), respectively. Individuals with back disease and a high level of physical activity at work showed the overall highest level of fear-avoidance whereas pain-free individuals with a low level of physical activity at work showed the overall lowest level of fear-avoidance. Physical activity during work and leisure shows contrasting associations with fear-avoidance beliefs. While high physical activity during leisure is associated with lower levels, high physical activity at work is associated with higher levels of fear-avoidance. The present results may reflect some deeply rooted negative beliefs about pain and work in the population. On the societal level, campaigns may be a possible way forward as these have shown to improve beliefs about musculoskeletal pain and work.
Avoidable Burden of Risk Factors for Serious Road Traffic Crashes in Iran: A Modeling Study.

PubMed

Khosravi Shadmani, Fatemeh; Mansori, Kamyar; Karami, Manoochehr; Zayeri, Farid; Shadman, Reza Khosravi; Hanis, Shiva Mansouri; Soori, Hamid

2017-03-01

The aim of this study was to model the avoidable burden of the risk factors of road traffic crashes in Iran and to prioritize interventions to reduce that burden. The prevalence and the effect size of the risk factors were obtained from data documented by the traffic police of Iran in 2013. The effect size was estimated using an ordinal regression model. The potential impact fraction index was applied to calculate the avoidable burden in order to prioritize interventions. This index was calculated for theoretical, plausible, and feasible minimum risk level scenarios. The joint effects of the risk factors were then estimated for all the scenarios. The highest avoidable burdens in the theoretical, plausible, and feasible minimum risk level scenarios for the non-use of child restraints on urban roads were 52.25, 28.63, and 46.67, respectively. In contrast, the value of this index for speeding was 76.24, 37.00, and 62.23, respectively, for rural roads. On the basis of the different scenarios considered in this research, we suggest focusing on future interventions to decrease the prevalence of speeding, the non-use of child restraints, the use of cell phones while driving, and helmet disuse, and the laws related to these items should be considered seriously.
Development of collision avoidance system for useful UAV applications using image sensors with laser transmitter

NASA Astrophysics Data System (ADS)

Cheong, M. K.; Bahiki, M. R.; Azrad, S.

2016-10-01

The main goal of this study is to demonstrate the approach of achieving collision avoidance on Quadrotor Unmanned Aerial Vehicle (QUAV) using image sensors with colour- based tracking method. A pair of high definition (HD) stereo cameras were chosen as the stereo vision sensor to obtain depth data from flat object surfaces. Laser transmitter was utilized to project high contrast tracking spot for depth calculation using common triangulation. Stereo vision algorithm was developed to acquire the distance from tracked point to QUAV and the control algorithm was designed to manipulate QUAV's response based on depth calculated. Attitude and position controller were designed using the non-linear model with the help of Optitrack motion tracking system. A number of collision avoidance flight tests were carried out to validate the performance of the stereo vision and control algorithm based on image sensors. In the results, the UAV was able to hover with fairly good accuracy in both static and dynamic collision avoidance for short range collision avoidance. Collision avoidance performance of the UAV was better with obstacle of dull surfaces in comparison to shiny surfaces. The minimum collision avoidance distance achievable was 0.4 m. The approach was suitable to be applied in short range collision avoidance.
Categorization-based stranger avoidance does not explain the uncanny valley effect.

PubMed

MacDorman, Karl F; Chattopadhyay, Debaleena

2017-04-01

The uncanny valley hypothesis predicts that an entity appearing almost human risks eliciting cold, eerie feelings in viewers. Categorization-based stranger avoidance theory identifies the cause of this feeling as categorizing the entity into a novel category. This explanation is doubtful because stranger is not a novel category in adults; infants do not avoid strangers while the category stranger remains novel; infants old enough to fear strangers prefer photographs of strangers to those more closely resembling a familiar person; and the uncanny valley's characteristic eeriness is seldom felt when meeting strangers. We repeated our original experiment with a more realistic 3D computer model and found no support for categorization-based stranger avoidance theory. By contrast, realism inconsistency theory explains cold, eerie feelings elicited by transitions between instances of two different, mutually exclusive categories, given that at least one category is anthropomorphic: Cold, eerie feelings are caused by prediction error from perceiving some features as features of the first category and other features as features of the second category. In principle, realism inconsistency theory can explain not only negative evaluations of transitions between real and computer modeled humans but also between different vertebrate species. Copyright © 2017 Elsevier B.V. All rights reserved.
Avoidable errors in dealing with anaphylactoid reactions to iodinated contrast media.

PubMed

Segal, Arthur J; Bush, William H

2011-03-01

Contrast reactions are much less common today than in the past. This is principally because of the current and predominant use of low and iso-osmolar contrast media compared with the prior use of high osmolality contrast media. As a result of the significantly diminished frequency, there are now fewer opportunities for physicians to recognize and appropriately treat such adverse reactions. In review of the literature combined with our own clinical and legal experience, 12 potential errors were identified and these are reviewed in detail so that they can be avoided by the physician-in-charge. Basic treatment considerations are presented along with a plan to systematize an approach to contrast reactions, simplify treatment options and plans, and schedule periodic drills.
The "ick" Factor Matters: Disgust Prospectively Predicts Avoidance in Chemotherapy Patients.

PubMed

Reynolds, Lisa M; Bissett, Ian P; Porter, David; Consedine, Nathan S

2016-12-01

Chemotherapy can be physically and psychologically demanding. Avoidance and withdrawal are common among patients coping with these demands. This report compares established emotional predictors of avoidance during chemotherapy (embarrassment; distress) with an emotion (disgust) that has been unstudied in this context. This report outlines secondary analyses of an RCT where 68 cancer patients undergoing chemotherapy were randomized to mindfulness or relaxation interventions. Self-reported baseline disgust (DS-R), embarrassment (SES-SF), and distress (Distress Thermometer) were used to prospectively predict multiple classes of avoidance post-intervention and at 3 months follow-up. Measures assessed social avoidance, cognitive and emotional avoidance (IES Avoidance), as well as information seeking and treatment adherence (General Adherence Scale). Repeated-measures ANOVAs evaluated possible longitudinal changes in disgust and forward entry regression models contrasted the ability of the affective variables to predict avoidance. Although disgust did not change over time or vary between groups, greater disgust predicted greater social, cognitive, and emotional avoidance, as well as greater information seeking. Social avoidance was predicted by trait embarrassment and distress predicted non-adherence. This report represents the first investigation of disgust's ability to prospectively predict avoidance in people undergoing chemotherapy. Compared to embarrassment and distress, disgust was a more consistent predictor across avoidance domains and its predictive ability was evident across a longer period of time. Findings highlight disgust's role as an indicator of likely avoidance in this health context. Early identification of cancer patients at risk of deleterious avoidance may enable timely interventions and has important clinical implications (ACTRN12613000238774).
MO-F-CAMPUS-J-01: Effect of Iodine Contrast Agent Concentration On Cerebrovascular Dose for Synchrotron Radiation Microangiography Based On a Simple Mouse Head Model and a Voxel Mouse Head Phantom

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

Lin, H; Jing, J; Xie, C

Purpose: To find effective setting methods to mitigate the irradiation injure in synchrotron radiation microangiography(SRA) by Monte Carlo simulation. Methods: A mouse 1-D head model and a segmented voxel mouse head phantom were simulated by EGSnrc/Dosxyznrc code to investigate the dose enhancement effect of the iodine contrast agent irradiated by a monochromatic synchrotron radiation(SR) source. The influence of, like iodine concentration (IC), vessel width and depth, with and without skull layer protection and the various incident X ray energies, were simulated. The dose enhancement effect and the absolute dose based on the segmented voxel mouse head phantom were evaluated. Results:more » The dose enhancement ratio depends little on the irradiation depth, but strongly on the IC, which is linearly increases with IC. The skull layer protection cannot be ignored in SRA, the 700µm thick skull could decrease 10% of the dose. The incident X-ray energy can significantly affact the dose. E.g. compared to the dose of 33.2keV for 50mgI/ml, the 32.7keV dose decreases 38%, whereas the dose of 33.7 keV increases 69.2%, and the variation will strengthen more with enhanced IC. The segmented voxel mouse head phantom also showed that the average dose enhancement effect and the maximal voxel dose per photon depends little on the iodine voxel volume ratio, but strongly on IC. Conclusion: To decrease dose damage in SRA, the high-Z contrast agent should be used as little as possible, and try to avoid radiating locally the injected position immediately after the contrast agent injection. The fragile vessel containing iodine should avoid closely irradiating. Avoiding irradiating through the no or thin skull region, or appending thin equivalent material from outside to protect is also a better method. As long as SRA image quality is ensured, using incident X-ray energy as low as possible.« less
The effect of healthcare delivery privatisation on avoidable mortality: longitudinal cross-regional results from Italy, 1993-2003.

PubMed

Quercioli, Cecilia; Messina, Gabriele; Basu, Sanjay; McKee, Martin; Nante, Nicola; Stuckler, David

2013-02-01

During the 1990s, Italy privatised a significant portion of its healthcare delivery. The authors compared the effectiveness of private and public sector healthcare delivery in reducing avoidable mortality (deaths that should not occur in the presence of effective medical care). The authors calculated the average rate of change in age-standardised avoidable mortality rates in 19 of Italy's regions from 1993 to 2003. Multivariate regression models were used to analyse the relationship between rates of change in avoidable mortality and levels of spending on public versus private healthcare delivery, controlling for potential demographic and economic confounders. Greater spending on public delivery of health services corresponded to faster reductions in avoidable mortality rates. Each €100 additional public spending per capita on NHS delivery was independently associated with a 1.47% reduction in the rate of avoidable mortality (p=0.003). In contrast, spending on private sector services had no statistically significant effect on avoidable mortality rates (p=0.557). A higher percentage of spending on private sector delivery was associated with higher rates of avoidable mortality (p=0.002). The authors found that neither public nor private sector delivery spending was significantly associated with non-avoidable mortality rates, plausibly because non-avoidable mortality is insensitive to healthcare services. Public spending was significantly associated with reductions in avoidable mortality rates over time, while greater private sector spending was not at the regional level in Italy.
Predator-prey coevolution: Australian native bees avoid their spider predators.

PubMed

Heiling, A M; Herberstein, M E

2004-05-07

Australian crab spiders Thomisus spectabilis manipulate visual flower signals to lure introduced Apis mellifera. We gave Australian native bees, Austroplebia australis, the choice between two white daisies, Chrysanthemum frutescens, one of them occupied by a crab spider. The colour contrast between flowers and spiders affected the behaviour of native bees. Native bees approached spider-occupied flowers more frequently. However, native bees avoided flowers occupied by spiders and landed on vacant flowers more frequently. In contrast to honeybees that did not coevolve with T. spectabilis, Australian native bees show an anti-predatory response to avoid flowers occupied by this predator.
Predator-prey coevolution: Australian native bees avoid their spider predators.

PubMed Central

Heiling, A M; Herberstein, M E

2004-01-01

Australian crab spiders Thomisus spectabilis manipulate visual flower signals to lure introduced Apis mellifera. We gave Australian native bees, Austroplebia australis, the choice between two white daisies, Chrysanthemum frutescens, one of them occupied by a crab spider. The colour contrast between flowers and spiders affected the behaviour of native bees. Native bees approached spider-occupied flowers more frequently. However, native bees avoided flowers occupied by spiders and landed on vacant flowers more frequently. In contrast to honeybees that did not coevolve with T. spectabilis, Australian native bees show an anti-predatory response to avoid flowers occupied by this predator. PMID:15252982
Approach/avoidance in dreams.

PubMed

Malcolm-Smith, Susan; Koopowitz, Sheri; Pantelis, Eleni; Solms, Mark

2012-03-01

The influential threat simulation theory (TST) asserts that dreaming yields adaptive advantage by providing a virtual environment in which threat-avoidance may be safely rehearsed. We have previously found the incidence of biologically threatening dreams to be around 20%, with successful threat avoidance occurring in approximately one-fifth of such dreams. TST asserts that threat avoidance is over-represented relative to other possible dream contents. To begin assessing this issue, we contrasted the incidence of 'avoidance' dreams with that of their opposite: 'approach' dreams. Because TST states that the threat-avoidance function is only fully activated in ecologically valid (biologically threatening) contexts, we also performed this contrast for populations living in both high- and low-threat environments. We find that 'approach' dreams are significantly more prevalent across both contexts. We suggest these results are more consistent with the view that dreaming is generated by reward-seeking systems than by fear-conditioning systems, although reward-seeking is clearly not the only factor determining the content of dreams. Copyright © 2011 Elsevier Inc. All rights reserved.
Visuo-motor coordination and internal models for object interception.

PubMed

Zago, Myrka; McIntyre, Joseph; Senot, Patrice; Lacquaniti, Francesco

2009-02-01

Intercepting and avoiding collisions with moving objects are fundamental skills in daily life. Anticipatory behavior is required because of significant delays in transforming sensory information about target and body motion into a timed motor response. The ability to predict the kinematics and kinetics of interception or avoidance hundreds of milliseconds before the event may depend on several different sources of information and on different strategies of sensory-motor coordination. What are exactly the sources of spatio-temporal information and what are the control strategies remain controversial issues. Indeed, these topics have been the battlefield of contrasting views on how the brain interprets visual information to guide movement. Here we attempt a synthetic overview of the vast literature on interception. We discuss in detail the behavioral and neurophysiological aspects of interception of targets falling under gravity, as this topic has received special attention in recent years. We show that visual cues alone are insufficient to predict the time and place of interception or avoidance, and they need to be supplemented by prior knowledge (or internal models) about several features of the dynamic interaction with the moving object.
Zero-Adjective Contrast in Much-less Ellipsis: The Advantage for Parallel Syntax.

PubMed

Carlson, Katy; Harris, Jesse A

2018-01-01

This paper explores the processing of sentences with a much less coordinator ( I don't own a pink hat, much less a red one ). This understudied ellipsis sentence, one of several focus-sensitive coordination structures, imposes syntactic and semantic conditions on the relationship between the correlate ( a pink hat ) and remnant ( a red one ). We present the case of zero-adjective contrast, in which an NP remnant introduces an adjective without an overt counterpart in the correlate ( I don't own a hat, much less a red one ). Although zero-adjective contrast could in principle ease comprehension by limiting the possible relationships between the remnant and correlate to entailment, we find that zero-adjective contrast is avoided in production and taxing in online processing. Results from several studies support a processing model in which syntactic parallelism is the primary guide for determining contrast in ellipsis structures, even when violating parallelism would assist in computing semantic relationships.

Inbreeding avoidance under different null models of random mating in the great tit.

PubMed

Szulkin, Marta; Zelazowski, Przemyslaw; Nicholson, George; Sheldon, Ben C

2009-07-01

1. In populations where inbreeding causes a substantial decrease in fitness, selection is expected to favour the evolution of inbreeding avoidance behaviours. Elsewhere we have documented substantial inbreeding depression and the importance of dispersal in avoiding inbreeding in a long-term population study of the great tit Parus major in Wytham (UK). In this study, we ask whether individuals from this population actively avoid mating with kin. 2. We generated four contrasting models of random mate choice that assumed varying levels of mate availability in each year of the data set. This allowed us to compare observed and simulated distributions and frequencies of inbreeding coefficients from 41 years of breeding data. 3. We found no evidence that birds avoid mating with related partners. Our results show that birds breed more often with relatives than expected under null models of mate choice that lack population structure, but not when compared to scenarios where birds were mated with their nearest neighbours. Pedigree-derived F(IS) values were positive for all scenarios of random mating, confirming the lack of inbreeding avoidance in this population. 4. These results imply the existence of spatial genetic structure where related individuals occur closer together than nonrelated individuals while breeding, and suggest that the relatedness between breeding individuals of the opposite sex decreases with distance. Thus, while dispersal from the natal site decreases the number of relatives around an individual, it does not completely homogenize genetic structure. 5. We show that brother-sister pairs are observed more often than under any scenario of random mating, suggesting that not only birds do not avoid mating with kin, but also that the apparently maladaptive choice of mating with a sibling is made more often than expected. 6. Our results provide no evidence to suggest that individuals actively avoid kin. In fact, some types of inbreeding occur more often than expected, despite the substantial fitness costs. The observed lack of inbreeding avoidance is in agreement with other studies of non-cooperatively breeding passerine birds, although the higher than expected frequency of sibling mating remains a puzzling result.
Vector Autoregression, Structural Equation Modeling, and Their Synthesis in Neuroimaging Data Analysis

PubMed Central

Chen, Gang; Glen, Daniel R.; Saad, Ziad S.; Hamilton, J. Paul; Thomason, Moriah E.; Gotlib, Ian H.; Cox, Robert W.

2011-01-01

Vector autoregression (VAR) and structural equation modeling (SEM) are two popular brain-network modeling tools. VAR, which is a data-driven approach, assumes that connected regions exert time-lagged influences on one another. In contrast, the hypothesis-driven SEM is used to validate an existing connectivity model where connected regions have contemporaneous interactions among them. We present the two models in detail and discuss their applicability to FMRI data, and interpretational limits. We also propose a unified approach that models both lagged and contemporaneous effects. The unifying model, structural vector autoregression (SVAR), may improve statistical and explanatory power, and avoids some prevalent pitfalls that can occur when VAR and SEM are utilized separately. PMID:21975109
Optical side-effects of fs-laser treatment in refractive surgery investigated by means of a model eye

PubMed Central

Ackermann, Roland; Kammel, Robert; Merker, Marina; Kamm, Andreas; Tünnermann, Andreas; Nolte, Stefan

2013-01-01

Optical side-effects of fs-laser treatment in refractive surgery are investigated by means of a model eye. We show that rainbow glare is the predominant perturbation, which can be avoided by randomly distributing laser spots within the lens. For corneal applications such as fs-LASIK, even a regular grid with spot-to-spot distances of ~3 µm is sufficient to minimize rainbow glare perception. Contrast sensitivity is affected, when the lens is treated with large 3D-patterns. PMID:23413236
Morphological rational operator for contrast enhancement.

PubMed

Peregrina-Barreto, Hayde; Herrera-Navarro, Ana M; Morales-Hernández, Luis A; Terol-Villalobos, Iván R

2011-03-01

Contrast enhancement is an important task in image processing that is commonly used as a preprocessing step to improve the images for other tasks such as segmentation. However, some methods for contrast improvement that work well in low-contrast regions affect good contrast regions as well. This occurs due to the fact that some elements may vanish. A method focused on images with different luminance conditions is introduced in the present work. The proposed method is based on morphological transformations by reconstruction and rational operations, which, altogether, allow a more accurate contrast enhancement resulting in regions that are in harmony with their environment. Furthermore, due to the properties of these morphological transformations, the creation of new elements on the image is avoided. The processing is carried out on luminance values in the u'v'Y color space, which avoids the creation of new colors. As a result of the previous considerations, the proposed method keeps the natural color appearance of the image.
Achievement goals, self-handicapping, and performance: a 2 x 2 achievement goal perspective.

PubMed

Ntoumanis, Nikos; Thøgersen-Ntoumani, Cecilie; Smith, Alison L

2009-11-01

Elliot and colleagues (2006) examined the effects of experimentally induced achievement goals, proposed by the trichotomous model, on self-handicapping and performance in physical education. Our study replicated and extended the work of Elliot et al. by experimentally promoting all four goals proposed by the 2 x 2 model (Elliot & McGregor, 2001), measuring the participants' own situational achievement goals, using a relatively novel task, and testing the participants in a group setting. We used a randomized experimental design with four conditions that aimed to induce one of the four goals advanced by the 2 x 2 model. The participants (n = 138) were undergraduates who engaged in a dart-throwing task. The results pertaining to self-handicapping partly replicated Elliot and colleagues' findings by showing that experimentally promoted performance-avoidance goals resulted in less practice. In contrast, the promotion of mastery-avoidance goals did not result in less practice compared with either of the approach goals. Dart-throwing performance did not differ among the four goal conditions. Personal achievement goals did not moderate the effects of experimentally induced goals on self-handicapping and performance. The extent to which mastery-avoidance goals are maladaptive is discussed, as well as the interplay between personal and experimentally induced goals.
Angle selective backscattered electron contrast in the low-voltage scanning electron microscope: Simulation and experiment for polymers.

PubMed

Wan, Q; Masters, R C; Lidzey, D; Abrams, K J; Dapor, M; Plenderleith, R A; Rimmer, S; Claeyssens, F; Rodenburg, C

2016-12-01

Recently developed detectors can deliver high resolution and high contrast images of nanostructured carbon based materials in low voltage scanning electron microscopes (LVSEM) with beam deceleration. Monte Carlo Simulations are also used to predict under which exact imaging conditions purely compositional contrast can be obtained and optimised. This allows the prediction of the electron signal intensity in angle selective conditions for back-scattered electron (BSE) imaging in LVSEM and compares it to experimental signals. Angle selective detection with a concentric back scattered (CBS) detector is considered in the model in the absence and presence of a deceleration field, respectively. The validity of the model prediction for both cases was tested experimentally for amorphous C and Cu and applied to complex nanostructured carbon based materials, namely a Poly(N-isopropylacrylamide)/Poly(ethylene glycol) Diacrylate (PNIPAM/PEGDA) semi-interpenetration network (IPN) and a Poly(3-hexylthiophene-2,5-diyl) (P3HT) film, to map nano-scale composition and crystallinity distribution by avoiding experimental imaging conditions that lead to a mixed topographical and compositional contrast. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.
Molecular Profiles of Contrasting Shade Response Strategies in Wild Plants: Differential Control of Immunity and Shoot Elongation.

PubMed

Gommers, Charlotte M M; Keuskamp, Diederik H; Buti, Sara; van Veen, Hans; Koevoets, Iko T; Reinen, Emilie; Voesenek, Laurentius A C J; Pierik, Ronald

2017-02-01

Plants growing at high densities elongate their shoots to reach for light, a response known as the shade avoidance syndrome (SAS). Phytochrome-mediated detection of far-red light reflection from neighboring plants activates growth-promoting molecular pathways leading to SAS However, it is unknown how plants that complete their life cycle in the forest understory and are shade tolerant prevent SAS when exposed to shade. Here, we show how two wild Geranium species from different native light environments regulate contrasting responses to light quality cues. A comparative RNA sequencing approach unveiled the molecular underpinnings of their contrasting growth responses to far-red light enrichment. It also identified differential phytochrome control of plant immunity genes and confirmed that far-red enrichment indeed contrastingly affects resistance against Botrytis cinerea between the two species. Furthermore, we identify a number of candidate regulators of differential shade avoidance. Three of these, the receptor-like kinases FERONIA and THESEUS1 and the non-DNA binding bHLH protein KIDARI, are functionally validated in Arabidopsis thaliana through gene knockout and/or overexpression studies. We propose that these components may be associated with either showing or not showing shade avoidance responses. © 2017 American Society of Plant Biologists. All rights reserved.
Using High-Dimensional Image Models to Perform Highly Undetectable Steganography

NASA Astrophysics Data System (ADS)

Pevný, Tomáš; Filler, Tomáš; Bas, Patrick

This paper presents a complete methodology for designing practical and highly-undetectable stegosystems for real digital media. The main design principle is to minimize a suitably-defined distortion by means of efficient coding algorithm. The distortion is defined as a weighted difference of extended state-of-the-art feature vectors already used in steganalysis. This allows us to "preserve" the model used by steganalyst and thus be undetectable even for large payloads. This framework can be efficiently implemented even when the dimensionality of the feature set used by the embedder is larger than 107. The high dimensional model is necessary to avoid known security weaknesses. Although high-dimensional models might be problem in steganalysis, we explain, why they are acceptable in steganography. As an example, we introduce HUGO, a new embedding algorithm for spatial-domain digital images and we contrast its performance with LSB matching. On the BOWS2 image database and in contrast with LSB matching, HUGO allows the embedder to hide 7× longer message with the same level of security level.
Active Avoidance: Neural Mechanisms and Attenuation of Pavlovian Conditioned Responding.

PubMed

Boeke, Emily A; Moscarello, Justin M; LeDoux, Joseph E; Phelps, Elizabeth A; Hartley, Catherine A

2017-05-03

Patients with anxiety disorders often experience a relapse in symptoms after exposure therapy. Similarly, threat responses acquired during Pavlovian threat conditioning often return after extinction learning. Accordingly, there is a need for alternative methods to persistently reduce threat responding. Studies in rodents have suggested that exercising behavioral control over an aversive stimulus can persistently diminish threat responses, and that these effects are mediated by the amygdala, ventromedial prefrontal cortex, and striatum. In this fMRI study, we attempted to translate these findings to humans. Subjects first underwent threat conditioning. We then contrasted two forms of safety learning: active avoidance, in which participants could prevent the shock through an action, and yoked extinction, with shock presentation matched to the active condition, but without instrumental control. The following day, we assessed subjects' threat responses (measured by skin conductance) to the conditioned stimuli without shock. Subjects next underwent threat conditioning with novel stimuli. Yoked extinction subjects showed an increase in conditioned response to stimuli from the previous day, but the active avoidance group did not. Additionally, active avoidance subjects showed reduced conditioned responding during novel threat conditioning, but the extinction group did not. We observed between-group differences in striatal BOLD responses to shock omission in Avoidance/Extinction. These findings suggest a differential role for the striatum in human active avoidance versus extinction learning, and indicate that active avoidance may be more effective than extinction in persistently diminishing threat responses. SIGNIFICANCE STATEMENT Extinguished threat responses often reemerge with time, highlighting the importance of identifying more enduring means of attenuation. We compared the effects of active avoidance learning and yoked extinction on threat responses in humans and contrasted the neural circuitry engaged by these two processes. Subjects who learned to prevent a shock through an action maintained low threat responses after safety learning and showed attenuated threat conditioning with novel stimuli, in contrast to those who underwent yoked extinction. The results suggest that experiences of active control over threat engage the striatum and promote a shift from expression of innate defensive responses toward more adaptive behavioral responses to threatening stimuli. Copyright © 2017 the authors 0270-6474/17/374808-11$15.00/0.
Active Avoidance: Neural Mechanisms and Attenuation of Pavlovian Conditioned Responding

PubMed Central

Boeke, Emily A.; Moscarello, Justin M.; Phelps, Elizabeth A.

2017-01-01

Patients with anxiety disorders often experience a relapse in symptoms after exposure therapy. Similarly, threat responses acquired during Pavlovian threat conditioning often return after extinction learning. Accordingly, there is a need for alternative methods to persistently reduce threat responding. Studies in rodents have suggested that exercising behavioral control over an aversive stimulus can persistently diminish threat responses, and that these effects are mediated by the amygdala, ventromedial prefrontal cortex, and striatum. In this fMRI study, we attempted to translate these findings to humans. Subjects first underwent threat conditioning. We then contrasted two forms of safety learning: active avoidance, in which participants could prevent the shock through an action, and yoked extinction, with shock presentation matched to the active condition, but without instrumental control. The following day, we assessed subjects' threat responses (measured by skin conductance) to the conditioned stimuli without shock. Subjects next underwent threat conditioning with novel stimuli. Yoked extinction subjects showed an increase in conditioned response to stimuli from the previous day, but the active avoidance group did not. Additionally, active avoidance subjects showed reduced conditioned responding during novel threat conditioning, but the extinction group did not. We observed between-group differences in striatal BOLD responses to shock omission in Avoidance/Extinction. These findings suggest a differential role for the striatum in human active avoidance versus extinction learning, and indicate that active avoidance may be more effective than extinction in persistently diminishing threat responses. SIGNIFICANCE STATEMENT Extinguished threat responses often reemerge with time, highlighting the importance of identifying more enduring means of attenuation. We compared the effects of active avoidance learning and yoked extinction on threat responses in humans and contrasted the neural circuitry engaged by these two processes. Subjects who learned to prevent a shock through an action maintained low threat responses after safety learning and showed attenuated threat conditioning with novel stimuli, in contrast to those who underwent yoked extinction. The results suggest that experiences of active control over threat engage the striatum and promote a shift from expression of innate defensive responses toward more adaptive behavioral responses to threatening stimuli. PMID:28408411
Activation of β-adrenoceptor facilitates active avoidance learning through enhancement of glutamate levels in the hippocampal dentate gyrus.

PubMed

Lv, Jing; Feng, Hao; Chen, Ling; Wang, Wei-Yao; Yue, Xue-Ling; Jin, Qing-Hua

2017-10-18

Long-term potentiation (LTP) is widely accepted as the best studied model for neurophysiological mechanisms that could underlie learning and memory formation. Despite a number of studies indicating that β-adrenoceptors in the hippocampal dentate gyrus (DG) is involved in the modulation of learning and memory as well as LTP, few studies have used glutamate release as a visual indicator in awake animals to explore the role of β-adrenoceptors in learning-dependent LTP. Therefore, in the present study, the effects of propranolol (an antagonist of β-adrenoceptor) and isoproterenol (an agonist of β-adrenoceptor) on extracellular concentrations of glutamate and amplitudes of field excitatory postsynaptic potential were measured in the DG region during active avoidance learning in freely moving conscious rats. In the control group, the glutamate level in the DG was significantly increased during the acquisition of active avoidance behavior and returned to basal level following extinction training. In propranolol group, antagonism of β-adrenoceptors in the DG significantly reduced the change in glutamate level, and the acquisition of the active avoidance behavior was significantly inhibited. In contrast, the change in glutamate level was significantly enhanced by isoproterenol, and the acquisition of the active avoidance behavior was significantly accelerated. Furthermore, in all groups, the changes in glutamate level were accompanied by corresponding changes in field excitatory postsynaptic potential amplitude and active avoidance behavior. Our results suggest that activation of β-adrenoceptors in the hippocampal DG facilitates active avoidance learning by modulations of glutamate level and synaptic efficiency in rats.
Cognitive Defusion versus thought Distraction in the Mitigation of Learned Helplessness

ERIC Educational Resources Information Center

Hooper, Nic; McHugh, Louise

2013-01-01

Recent research suggests that attempting to avoid unwanted psychological events is maladaptive. Contrastingly, cognitive defusion, which is an acceptance-based method for managing unwanted thoughts, may provide a plausible alternative. The current study was designed to compare defusion and experiential avoidance as strategies for coping with…
Avoidance and depression vulnerability: An examination of avoidance in remitted and currently depressed individuals.

PubMed

Quigley, Leanne; Wen, Alainna; Dobson, Keith S

2017-10-01

Behavioral theories posit that depression is characterized by heightened levels of avoidance, and recent research has supported this notion. Whether avoidance persists after remission from depression is unknown, however. In this study, we investigated levels of cognitive and behavioral avoidance in remitted, currently, and never depressed individuals. We also examined relationships among avoidance and purported adaptive and maladaptive emotion regulation strategies. Remitted depressed individuals exhibited levels of cognitive and behavioral avoidance, in social and nonsocial domains, that were greater than nonclinical control individuals but lower than currently depressed individuals. Avoidance was significantly associated with use of maladaptive emotion regulation strategies, although the pattern of relationships differed across remitted and currently depressed individuals. In contrast, avoidance was largely unrelated to use of adaptive emotion regulation strategies, among remitted and currently depressed individuals. Copyright © 2017 Elsevier Ltd. All rights reserved.
A new automated quantification algorithm for the detection and evaluation of focal liver lesions with contrast-enhanced ultrasound.

PubMed

Gatos, Ilias; Tsantis, Stavros; Spiliopoulos, Stavros; Skouroliakou, Aikaterini; Theotokas, Ioannis; Zoumpoulis, Pavlos; Hazle, John D; Kagadis, George C

2015-07-01

Detect and classify focal liver lesions (FLLs) from contrast-enhanced ultrasound (CEUS) imaging by means of an automated quantification algorithm. The proposed algorithm employs a sophisticated segmentation method to detect and contour focal lesions from 52 CEUS video sequences (30 benign and 22 malignant). Lesion detection involves wavelet transform zero crossings utilization as an initialization step to the Markov random field model toward the lesion contour extraction. After FLL detection across frames, time intensity curve (TIC) is computed which provides the contrast agents' behavior at all vascular phases with respect to adjacent parenchyma for each patient. From each TIC, eight features were automatically calculated and employed into the support vector machines (SVMs) classification algorithm in the design of the image analysis model. With regard to FLLs detection accuracy, all lesions detected had an average overlap value of 0.89 ± 0.16 with manual segmentations for all CEUS frame-subsets included in the study. Highest classification accuracy from the SVM model was 90.3%, misdiagnosing three benign and two malignant FLLs with sensitivity and specificity values of 93.1% and 86.9%, respectively. The proposed quantification system that employs FLLs detection and classification algorithms may be of value to physicians as a second opinion tool for avoiding unnecessary invasive procedures.
Temperament and character profiles in bipolar I, bipolar II and major depressive disorder: Impact over illness course, comorbidity pattern and psychopathological features of depression.

PubMed

Zaninotto, Leonardo; Souery, Daniel; Calati, Raffaella; Di Nicola, Marco; Montgomery, Stuart; Kasper, Siegfried; Zohar, Joseph; Mendlewicz, Julien; Robert Cloninger, C; Serretti, Alessandro; Janiri, Luigi

2015-09-15

Studies comparing temperament and character traits between patients with mood disorders and healthy individuals have yielded variable results. The Temperament and Character Inventory (TCI) was administered to 101 bipolar I (BP-I), 96 bipolar II (BP-II), 123 major depressive disorder (MDD) patients, and 125 HS. A series of generalized linear models were performed in order to: (a) compare the TCI dimensions across groups; (b) test any effect of the TCI dimensions on clinical features of mood disorders; and (c) detect any association between TCI dimensions and the psychopathological features of a major depressive episode. Demographic and clinical variables were also included in the models as independent variables. Higher Harm Avoidance was found in BP-II and MDD, but not in BP-I. Higher Self-Transcendence was found in BP-I. Our models also showed higher Self-Directedness in HS, either vs MDD or BP-II. No association was found between any TCI dimension and the severity of symptoms. Conversely, a positive association was found between Harm Avoidance and the overall burden of depressive episodes during lifetime. The cross-sectional design and the heterogeneity of the sample may be the main limitations of our study. In general, our sample seems to support the view of a similar profile of temperament and character between MDD and BP-II, characterized by high Harm Avoidance and low Self-Directedness. In contrast, patients with BP-I only exhibit high Self-Transcendence, having a near-normal profile in terms of Harm Avoidance or Self-Directedness. Copyright © 2015 Elsevier B.V. All rights reserved.
Rumination and behavioural factors in Parkinson's disease depression.

PubMed

Julien, Camille L; Rimes, Katharine A; Brown, Richard G

2016-03-01

Parkinson's disease is associated with high rates of depression. There is growing interest in non-pharmacological management including psychological approaches such as Cognitive Behaviour Therapy. To date, little research has investigated whether processes that underpin cognitive models of depression, on which such treatment is based, apply in patients with Parkinson's disease. The study aimed to investigate the contribution of core psychological factors to the presence and degree of depressive symptoms. 104 participants completed questionnaires measuring mood, motor disability and core psychological variables, including maladaptive assumptions, rumination, cognitive-behavioural avoidance, illness representations and cognitive-behavioural responses to symptoms. Regression analyses revealed that a small number of psychological factors accounted for the majority of depression variance, over and above that explained by overall disability. Participants reporting high levels of rumination, avoidance and symptom focusing experienced more severe depressive symptoms. In contrast, pervasive negative dysfunctional beliefs did not independently contribute to depression variance. Specific cognitive (rumination and symptom focusing) and behavioural (avoidance) processes may be key psychological markers of depression in Parkinson's disease and therefore offer important targets for tailored psychological interventions. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.
A Daily Diary Study of Posttraumatic Stress Symptoms and Romantic Partner Accommodation

PubMed Central

Campbell, Sarah B.; Renshaw, Keith D.; Kashdan, Todd B.; Curby, Timothy W.; Carter, Sarah P.

2017-01-01

Little is known about the role of romantic partner symptom accommodation in PTSD symptom maintenance. To explore the bidirectional associations of posttraumatic stress disorder (PTSD) symptoms and romantic partner symptom accommodation over time, military servicemen (n = 64) with symptoms of PTSD and their co-habiting heterosexual civilian romantic partners (n = 64) completed a 2-week daily diary study. Cross-lagged, autoregressive models assessed the stability of men’s PTSD symptoms and partners’ accommodation, as well as the prospective associations of earlier PTSD symptoms with later accommodation and vice versa. Analyses used Bayesian estimation to provide point estimates (b) and Credible Intervals (CIs). In all models, PTSD symptoms (total and individual clusters) were highly stable (b = 0.91; CI: 0.88–0.95), and accommodation was moderately stable (b = 0.48; CI: 0.40–0.54). In all models, earlier PTSD symptoms (total and clusters) were significantly, positively associated with later accommodation (b = 0.04; CI: 0.02–0.07). In contrast, earlier accommodation was significantly associated only with later situational avoidance (b = 0.02; CI: 0.00–0.07). Thus, PTSD symptoms may lead to subsequent accommodating behaviors in romantic partners, but partner accommodation seems to contribute only to survivors’ future situational avoidance symptoms. The findings reinforce the notion that PTSD symptoms have an impact on relationship behaviors, and that accommodation from partners may sustain avoidant behaviors in particular. Clinicians should attend to romantic partners’ accommodating behaviors when working with survivors. PMID:28270332
Improved image quality in pinhole SPECT by accurate modeling of the point spread function in low magnification systems

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

Pino, Francisco; Roé, Nuria; Aguiar, Pablo, E-mail: pablo.aguiar.fernandez@sergas.es

2015-02-15

Purpose: Single photon emission computed tomography (SPECT) has become an important noninvasive imaging technique in small-animal research. Due to the high resolution required in small-animal SPECT systems, the spatially variant system response needs to be included in the reconstruction algorithm. Accurate modeling of the system response should result in a major improvement in the quality of reconstructed images. The aim of this study was to quantitatively assess the impact that an accurate modeling of spatially variant collimator/detector response has on image-quality parameters, using a low magnification SPECT system equipped with a pinhole collimator and a small gamma camera. Methods: Threemore » methods were used to model the point spread function (PSF). For the first, only the geometrical pinhole aperture was included in the PSF. For the second, the septal penetration through the pinhole collimator was added. In the third method, the measured intrinsic detector response was incorporated. Tomographic spatial resolution was evaluated and contrast, recovery coefficients, contrast-to-noise ratio, and noise were quantified using a custom-built NEMA NU 4–2008 image-quality phantom. Results: A high correlation was found between the experimental data corresponding to intrinsic detector response and the fitted values obtained by means of an asymmetric Gaussian distribution. For all PSF models, resolution improved as the distance from the point source to the center of the field of view increased and when the acquisition radius diminished. An improvement of resolution was observed after a minimum of five iterations when the PSF modeling included more corrections. Contrast, recovery coefficients, and contrast-to-noise ratio were better for the same level of noise in the image when more accurate models were included. Ring-type artifacts were observed when the number of iterations exceeded 12. Conclusions: Accurate modeling of the PSF improves resolution, contrast, and recovery coefficients in the reconstructed images. To avoid the appearance of ring-type artifacts, the number of iterations should be limited. In low magnification systems, the intrinsic detector PSF plays a major role in improvement of the image-quality parameters.« less
A non-invasive test for receptor binding applied to nephrogenic diabetes insipidus.

PubMed Central

Britton, K. E.; Tedder, R. S.; Khokhar, A. M.; Brown, N. J.; Davison, A.; Slater, J. D.

1977-01-01

Studies in animals have determined the importance of specific receptors to the action of many hormones and drugs. In man, a non-invasive external counting technique has been used and absence of receptor function has been demonstrated in a patient with nephrogenic diabetes insipidus using radioactively labelled arginine vasopressin. This is in contrast to the findings in a patient with pituitary diabetes insipidus and a normal control. These results suggest a model for the study of hormone and drug kinetics in man avoiding multiple samplings of biological fluids. PMID:196275
Unifying Time to Contact Estimation and Collision Avoidance across Species

PubMed Central

Keil, Matthias S.; López-Moliner, Joan

2012-01-01

The -function and the -function are phenomenological models that are widely used in the context of timing interceptive actions and collision avoidance, respectively. Both models were previously considered to be unrelated to each other: is a decreasing function that provides an estimation of time-to-contact (ttc) in the early phase of an object approach; in contrast, has a maximum before ttc. Furthermore, it is not clear how both functions could be implemented at the neuronal level in a biophysically plausible fashion. Here we propose a new framework – the corrected modified Tau function – capable of predicting both -type (“”) and -type (“”) responses. The outstanding property of our new framework is its resilience to noise. We show that can be derived from a firing rate equation, and, as , serves to describe the response curves of collision sensitive neurons. Furthermore, we show that predicts the psychophysical performance of subjects determining ttc. Our new framework is thus validated successfully against published and novel experimental data. Within the framework, links between -type and -type neurons are established. Therefore, it could possibly serve as a model for explaining the co-occurrence of such neurons in the brain. PMID:22915999

The Perfect Aspect as a State of Being.

ERIC Educational Resources Information Center

Moy, Raymond H.

English as second language (ESL) learners often avoid using the present perfect or use it improperly. In contrast with native speakers of English sampled from newspaper editorials, of whom 75 percent used the present perfect, only 22 percent of ESL college students used the present perfect correctly. This avoidance is due in part to lack of…
"Thou Shalt Not Plagiarise": From Self-Reported Views to Recognition and Avoidance of Plagiarism

ERIC Educational Resources Information Center

Risquez, Angelica; O'Dwyer, Michele; Ledwith, Ann

2013-01-01

Throughout much of the literature on plagiarism in higher education, there is an implicit assumption that students who understand plagiarism, who have high ethical views and declare not to engage in plagiaristic behaviour are able to recognise it and avoid it in practice. Challenging this supposition, this paper contrasts students' self-reported…
How do attachment dimensions affect bereavement adjustment? A mediation model of continuing bonds.

PubMed

Yu, Wei; He, Li; Xu, Wei; Wang, Jianping; Prigerson, Holly G

2016-04-30

The current study aims to examine mechanisms underlying the impact of attachment dimensions on bereavement adjustment. Bereaved mainland Chinese participants (N=247) completed anonymous, retrospective, self-report surveys assessing attachment dimensions, continuing bonds (CB), grief symptoms and posttraumatic growth (PTG). Results demonstrated that attachment anxiety predicted grief symptoms via externalized CB and predicted PTG via internalized CB at the same time, whereas attachment avoidance positively predicted grief symptoms via externalized CB but negatively predicted PTG directly. Findings suggested that individuals with a high level of attachment anxiety could both suffer from grief and obtain posttraumatic growth after loss, but it depended on which kind of CB they used. By contrast, attachment avoidance was associated with a heightened risk of maladaptive bereavement adjustment. Future grief therapy may encourage the bereaved to establish CB with the deceased and gradually shift from externalized CB to internalized CB. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
3D widefield light microscope image reconstruction without dyes

NASA Astrophysics Data System (ADS)

Larkin, S.; Larson, J.; Holmes, C.; Vaicik, M.; Turturro, M.; Jurkevich, A.; Sinha, S.; Ezashi, T.; Papavasiliou, G.; Brey, E.; Holmes, T.

2015-03-01

3D image reconstruction using light microscope modalities without exogenous contrast agents is proposed and investigated as an approach to produce 3D images of biological samples for live imaging applications. Multimodality and multispectral imaging, used in concert with this 3D optical sectioning approach is also proposed as a way to further produce contrast that could be specific to components in the sample. The methods avoid usage of contrast agents. Contrast agents, such as fluorescent or absorbing dyes, can be toxic to cells or alter cell behavior. Current modes of producing 3D image sets from a light microscope, such as 3D deconvolution algorithms and confocal microscopy generally require contrast agents. Zernike phase contrast (ZPC), transmitted light brightfield (TLB), darkfield microscopy and others can produce contrast without dyes. Some of these modalities have not previously benefitted from 3D image reconstruction algorithms, however. The 3D image reconstruction algorithm is based on an underlying physical model of scattering potential, expressed as the sample's 3D absorption and phase quantities. The algorithm is based upon optimizing an objective function - the I-divergence - while solving for the 3D absorption and phase quantities. Unlike typical deconvolution algorithms, each microscope modality, such as ZPC or TLB, produces two output image sets instead of one. Contrast in the displayed image and 3D renderings is further enabled by treating the multispectral/multimodal data as a feature set in a mathematical formulation that uses the principal component method of statistics.
Problems of test choice and data analysis in behavioral teratology: the case of prenatal benzodiazepines.

PubMed

Chiarotti, F; Alleva, E; Bignami, G

1987-01-01

Higher-tier tests for the assessment of early treatment effects should be aimed at providing specific information on the behavior processes affected, rather than simply at extending the descriptive data base. The contrast between positive and negative results can be useful to point out possible mechanisms of action. For example, late prenatal oxazepam exposure of mice produced a reduction of the amphetamine hyperactivity at the end of the second postnatal week, but did not significantly affect the response to scopolamine at the end of the third week. An impairment of active locomotor avoidance was observed at the young adult stage, which contrasted with the absence or scarcity of changes in passive avoidance and extinction responding in the same go-no go tests. These changes in response-activating mechanisms appear to be in agreement with the medium- and long-term effects on CNS monoamine metabolism described in the literature. As concerns statistical analysis, dichotomous or polytomous data obtained, e.g., by the Fox battery are not yet amenable to an adequate processing, due to the shortcomings of the available nonparametric tests. By contrast, mixed-model ANOVAs can cope with complex data obtained, e.g., in activity and learning tests. However, the available checks on various assumptions (normality, homogeneity of variance, sphericity) are not valid when nested factors, block factors and repeated measures coexist. Finally, the more usual cross-fostering procedures provide adequate information on some aspects (e.g., separation of main effects of prenatal treatments from postnatal maternal effects) but not on others.(ABSTRACT TRUNCATED AT 250 WORDS)
Dyadic effects of attachment on mental health: Couples in a postdisaster context.

PubMed

Gallagher, H Colin; Lusher, Dean; Gibbs, Lisa; Pattison, Philippa; Forbes, David; Block, Karen; Harms, Louise; MacDougall, Colin; Kellett, Connie; Ireton, Greg; Bryant, Richard A

2017-03-01

Research on mental health following disasters has led to the identification of many individual protective and risk factors for postdisaster mental health. However, there is little understanding of the exact influence that disasters have on the functioning of intimate relationships. Especially relevant are attachment styles, which are likely to play an important role in the provision and perception of social support between partners, and subsequent mental health outcomes. Heterosexual couples (N = 127) affected by the 2009 Victorian "Black Saturday" Bushfires in southeastern Australia were surveyed for disaster experiences, posttraumatic stress disorder (PTSD) symptoms, depression, and attachment style between May 2012 and January 2013, approximately 3 years after the disaster. Using actor-partner interdependence models (APIM), we examined both intrapersonal and interpersonal associations of attachment anxiety and avoidance with depression and PTSD, in combination with shared disaster exposure. Male partners' attachment avoidance was associated with depression and PTSD in both partners. By contrast, a female partner's attachment avoidance was associated with greater depression and PTSD in herself, but fewer PTSD symptoms in a male partner. Amid the chronic stressors of a postdisaster setting, the attachment avoidance of the male partner may play a particularly negative role, with his tendency toward isolation and denial becoming especially maladaptive for the couple as a whole. The female partner's attachment avoidance is likewise an important factor, but its associations with negative social support and relationship breakup must be clarified to understand its impact on partnership functioning. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
Reconceptualising the doctor-patient relationship: recognising the role of trust in contemporary health care.

PubMed

Bending, Zara J

2015-06-01

The conception of the doctor-patient relationship under Australian law has followed British common law tradition whereby the relationship is founded in a contractual exchange. By contrast, this article presents a rationale and framework for an alternative model-a "Trust Model"-for implementation into law to more accurately reflect the contemporary therapeutic dynamic. The framework has four elements: (i) an assumption that professional conflicts (actual or perceived) with patient safety, motivated by financial or personal interests, should be avoided; (ii) an onus on doctors to disclose these conflicts; (iii) a proposed mechanism to contend with instances where doctors choose not to disclose; and (iv) sanctions for non-compliance with the regime.
Filter methods to preserve local contrast and to avoid artifacts in gamut mapping

NASA Astrophysics Data System (ADS)

Meili, Marcel; Küpper, Dennis; Barańczuk, Zofia; Caluori, Ursina; Simon, Klaus

2010-01-01

Contrary to high dynamic range imaging, the preservation of details and the avoidance of artifacts is not explicitly considered in popular color management systems. An effective way to overcome these difficulties is image filtering. In this paper we investigate several image filter concepts for detail preservation as part of a practical gamut mapping strategy. In particular we define four concepts including various image filters and check their performance with a psycho-visual test. Additionally, we compare our performance evaluation to two image quality measures with emphasis on local contrast. Surprisingly, the most simple filter concept performs highly efficient and achieves an image quality which is comparable to the more established but slower methods.
Fixed drug eruption associated with intravenous contrast media: report in a woman receiving iohexol.

PubMed

Wright, Natalie A; Cohen, Philip R

2011-07-01

Fixed drug eruption, a medication-associated mucocutaneous reaction, rarely presents as a delayed adverse reaction to intravenous non-ionic contrast media. We describe a 57-year-old woman with a history of metastatic renal cell carcinoma who repeatedly developed a sharply demarcated, erythematous patch on her left breast after receiving the iodinated non-ionic contrast media iohexol for staging computed tomography scans. Recurrent fixed drug eruption may be avoided by using another contrast medium. Prophylactic treatment with systemic corticosteroids may prevent repeated fixed drug eruption if an alternative contrast agent cannot be used.
[Substance use, affective problems and personality traits: test of two association models].

PubMed

Chakroun, N; Doron, J; Swendsen, J

2004-01-01

The International Consortium of Psychiatric Epidemiology has confirmed the high comorbidity in community-drawn samples between substance use disorders and anxiety or depression. In the same way, associations between substance use and specific personality traits (such as novelty seeking, harm avoidance or antisocial personality) have also been extensively documented. Self-medication and social deviance are among the most commonly evoked explanatory models for these forms of comorbidity, and are based on findings that affective disorders and specific personality traits often precede the onset of substance use disorders. The self-medication model postulates that an individual chooses a specific substance according to its psychopharmacologic action on the given psychological state of the person. By contrast, the social deviance model posits that this form of comorbidity is due to the fact that persons consuming certain substances may have affective or personality characteristics that are more severe or more deviant than non-consumers (or than consumers of socially well-accepted substances). In this way, the individual does not use a particular substance to assuage pre-existing disorders but, due to a more deviant personality, is less influenced by social norms and may more easily turn to using illicit substances or to polyconsumption. However, a major limitation of the current scientific literature concerning tests of these models is that previous investigations have been based in overwhelming majority on clinical populations. The examination only of clinical samples renders difficult the identification of causal (or primary) risk factors for the emergence of substance use disorders from the potential consequences of substance use itself. The goal of the current study was therefore to simultaneously compare both models of association using a non clinical population of substance users. In addition to selecting subjects based on use (rather than abuse or dependence), multiple comparisons were corrected with a Bonferroni adjustment. A two-phase sampling plan was used with post-stratification on substances use. In the first stage, an initial sample of 685 students was pre-selected based on responses to a battery of self-questionnaires, including information concerning recent consumption of substances (alcohol, cannabis, cocaine, heroin, acid, solvents, and so on), anxiety levels measured by the State and Trait Anxiety Inventory (STAI, Spielberger, 1983) and depression levels evaluated by the Center of Epidemiologic Studies Depression Scale (CES-D, Radloff, 1977). Based on responses to these questionnaires, 98 subjects were selected in the second phase to compose four groups of substance users: non consumers (those who did not use any substance during the last month); consumers of alcohol only, consumers of cannabis (with or without alcohol) and consumers of other illicit substances (with or without cannabis or alcohol). These subjects were then invited to participate in a brief laboratory-based meeting where they completed the Temperament and Character Inventory (TCI, Cloninger, 1992), which assessed different personality characteristics such as novelty seeking (NS), harm avoidance (HA) or antisocial personality disorder (APD). The hypotheses concerning self-medication were tested by multiple logistic regression by comparing each group of substance consumption to the non-consumer group relative to levels of anxiety, depression and scores of novelty seeking and harm avoidance. The social deviance model was tested by ANOVAs using contrasts which allowed for a test of a linear tendency across the four groups of consumption relative to each of the personality traits (novelty seeking, harm avoidance and antisocial personality). Results of multiple logistic regressions showed no difference between non-consumers and any group of consumers with regard to anxiety, depression and harm avoidance. However, consumers of other illicit substances significantly differed from non-consumers for novelty seeking trait (qOR=8.4; p<0.05). Results of the ANOVA also showed no differences between the four groups with regard to scores of harm avoidance and level of antisocial personality but again a comparison of novelty seeking scores was significant, F(94)=6.46, p<0.05. Moreover, the contrast method demonstrated that novelty seeking scores increased linearly and significantly (p<0.001) from the group of non-consumers to the group of the consumers of the most deviant substances. The results obtained in this non-clinical sample are in favor of social deviance model which posits that the personality trait of novelty seeking is associated to the consumption of the most illicit and deviant substances (such as heroin or cocaine). On the other hand, no support was found for the hypothesis of self-medication which assumes that specific substances should be particularly associated with specific psychological characteristics or vulnerabilities.
Distributed capillary adiabatic tissue homogeneity model in parametric multi-channel blind AIF estimation using DCE-MRI.

PubMed

Kratochvíla, Jiří; Jiřík, Radovan; Bartoš, Michal; Standara, Michal; Starčuk, Zenon; Taxt, Torfinn

2016-03-01

One of the main challenges in quantitative dynamic contrast-enhanced (DCE) MRI is estimation of the arterial input function (AIF). Usually, the signal from a single artery (ignoring contrast dispersion, partial volume effects and flow artifacts) or a population average of such signals (also ignoring variability between patients) is used. Multi-channel blind deconvolution is an alternative approach avoiding most of these problems. The AIF is estimated directly from the measured tracer concentration curves in several tissues. This contribution extends the published methods of multi-channel blind deconvolution by applying a more realistic model of the impulse residue function, the distributed capillary adiabatic tissue homogeneity model (DCATH). In addition, an alternative AIF model is used and several AIF-scaling methods are tested. The proposed method is evaluated on synthetic data with respect to the number of tissue regions and to the signal-to-noise ratio. Evaluation on clinical data (renal cell carcinoma patients before and after the beginning of the treatment) gave consistent results. An initial evaluation on clinical data indicates more reliable and less noise sensitive perfusion parameter estimates. Blind multi-channel deconvolution using the DCATH model might be a method of choice for AIF estimation in a clinical setup. © 2015 Wiley Periodicals, Inc.
Stimulation of postsynapse adrenergic α2A receptor improves attention/cognition performance in an animal model of attention deficit hyperactivity disorder.

PubMed

Kawaura, Kazuaki; Karasawa, Jun-ichi; Chaki, Shigeyuki; Hikichi, Hirohiko

2014-08-15

A 5-trial inhibitory avoidance test using spontaneously hypertensive rat (SHR) pups has been used as an animal model of attention deficit hyperactivity disorder (ADHD). However, the roles of noradrenergic systems, which are involved in the pathophysiology of ADHD, have not been investigated in this model. In the present study, the effects of adrenergic α2 receptor stimulation, which has been an effective treatment for ADHD, on attention/cognition performance were investigated in this model. Moreover, neuronal mechanisms mediated through adrenergic α2 receptors were investigated. We evaluated the effects of both clonidine, a non-selective adrenergic α2 receptor agonist, and guanfacine, a selective adrenergic α2A receptor agonist, using a 5-trial inhibitory avoidance test with SHR pups. Juvenile SHR exhibited a shorter transfer latency, compared with juvenile Wistar Kyoto (WKY) rats. Both clonidine and guanfacine significantly prolonged the transfer latency of juvenile SHR. The effects of clonidine and guanfacine were significantly blocked by pretreatment with an adrenergic α2A receptor antagonist. In contrast, the effect of clonidine was not attenuated by pretreatment with an adrenergic α2B receptor antagonist, or an adrenergic α2C receptor antagonist, while it was attenuated by a non-selective adrenergic α2 receptor antagonist. Furthermore, the effects of neither clonidine nor guanfacine were blocked by pretreatment with a selective noradrenergic neurotoxin. These results suggest that the stimulation of the adrenergic α2A receptor improves the attention/cognition performance of juvenile SHR in the 5-trial inhibitory avoidance test and that postsynaptic, rather than presynaptic, adrenergic α2A receptor is involved in this effect. Copyright © 2014 Elsevier B.V. All rights reserved.
Forebrain-specific CRF overproduction during development is sufficient to induce enduring anxiety and startle abnormalities in adult mice.

PubMed

Toth, Mate; Gresack, Jodi E; Bangasser, Debra A; Plona, Zach; Valentino, Rita J; Flandreau, Elizabeth I; Mansuy, Isabelle M; Merlo-Pich, Emilio; Geyer, Mark A; Risbrough, Victoria B

2014-05-01

Corticotropin releasing factor (CRF) regulates physiological and behavioral responses to stress. Trauma in early life or adulthood is associated with increased CRF in the cerebrospinal fluid and heightened anxiety. Genetic variance in CRF receptors is linked to altered risk for stress disorders. Thus, both heritable differences and environmentally induced changes in CRF neurotransmission across the lifespan may modulate anxiety traits. To test the hypothesis that CRF hypersignaling is sufficient to modify anxiety-related phenotypes (avoidance, startle, and conditioned fear), we induced transient forebrain-specific overexpression of CRF (CRFOE) in mice (1) during development to model early-life stress, (2) in adulthood to model adult-onset stress, or (3) across the entire postnatal lifespan to model heritable increases in CRF signaling. The consequences of these manipulations on CRF peptide levels and behavioral responses were examined in adulthood. We found that transient CRFOE during development decreased startle habituation and prepulse inhibition, and increased avoidance (particularly in females) recapitulating the behavioral effects of lifetime CRFOE despite lower CRF peptide levels at testing. In contrast, CRFOE limited to adulthood reduced contextual fear learning in females and increased startle reactivity in males but did not change avoidance or startle plasticity. These findings suggest that forebrain CRFOE limited to development is sufficient to induce enduring alterations in startle plasticity and anxiety, while forebrain CRFOE during adulthood results in a different phenotype profile. These findings suggest that startle circuits are particularly sensitive to forebrain CRFOE, and that the impact of CRFOE may be dependent on the time of exposure.
Distribution and movement of Caenorhabditis elegans on a thermal gradient.

PubMed

Yamada, Yohko; Ohshima, Yasumi

2003-08-01

To analyze thermal responses of Caenorhabditis elegans in detail, distribution of a worm population and movement of individual worms were examined on a linear, reproducible and broad temperature gradient. Assay methods were improved compared with those reported previously to ensure good motility and dispersion of worms. Well-fed, wild-type worms distributed over a wide temperature range of up to 10 degrees C, and, within this range, worms migrated in both directions of the gradient at similar frequencies without any specific response to the growth temperature in most cases. By contrast, worms migrated down the gradient if put in a region warmer than the warm boundary of distribution. The distribution range changed depending on the growth temperature and starvation, but active avoidance of a starvation temperature was not detected. These findings contradict previous hypotheses of taxis or migration to the growth temperature in association with food and instead indicate avoidance of a warm temperature. Our results favor a model for thermal response of C. elegans that postulates a single drive based on warm sensation rather than downward and upward drives in the physiological temperature range. Mutants in ttx-3, tax-2, tax-4 or egl-4 genes showed abnormal thermal responses, suggesting that these genes are involved in warm avoidance. Laser ablation and gene expression studies suggest that AFD neurons are not important, and tax-4 expression in neurons other than AFD is required, for warm avoidance.
Testing conditions in shock-based contextual fear conditioning influence both the behavioral responses and the activation of circuits potentially involved in contextual avoidance.

PubMed

Viellard, Juliette; Baldo, Marcus Vinicius C; Canteras, Newton Sabino

2016-12-15

Previous studies from our group have shown that risk assessment behaviors are the primary contextual fear responses to predatory and social threats, whereas freezing is the main contextual fear response to physically harmful events. To test contextual fear responses to a predator or aggressive conspecific threat, we developed a model that involves placing the animal in an apparatus where it can avoid the threat-associated environment. Conversely, in studies that use shock-based fear conditioning, the animals are usually confined inside the conditioning chamber during the contextual fear test. In the present study, we tested shock-based contextual fear responses using two different behavioral testing conditions: confining the animal in the conditioning chamber or placing the animal in an apparatus with free access to the conditioning compartment. Our results showed that during the contextual fear test, the animals confined to the shock chamber exhibited significantly more freezing. In contrast, the animals that could avoid the conditioning compartment displayed almost no freezing and exhibited risk assessment responses (i.e., crouch-sniff and stretch postures) and burying behavior. In addition, the animals that were able to avoid the shock chamber had increased Fos expression in the juxtadorsomedial lateral hypothalamic area, the dorsomedial part of the dorsal premammillary nucleus and the lateral and dorsomedial parts of the periaqueductal gray, which are elements of a septo/hippocampal-hypothalamic-brainstem circuit that is putatively involved in mediating contextual avoidance. Overall, the present findings show that testing conditions significantly influence both behavioral responses and the activation of circuits involved in contextual avoidance. Copyright © 2016 Elsevier B.V. All rights reserved.
Iodinated contrast media and contrast-induced nephropathy: is there a preferred cost-effective agent?

PubMed

Sharma, Samin K

2008-05-01

Over 20 years have passed since the introduction of the tri-iodinated low-osmolar nonionic contrast agents such as iopamidol, iohexol, ioversol and iopromide. During this time, most cardiology practices have switched to these nonionic agents to avoid the nuisance side effects and cardiac adverse events associated with the older ionic contrast agents. Although the improved tolerability of the nonionic agents is generally attributed to their decreased osmolality (approximately half that of the older ionic contrast agents), in fact, these contrast agents also differ from the older agents in their ionicity, viscosity and direct chemotoxicity. The impact of these properties on safety, together with cost differences, should be considered when selecting a contrast agent.
Threat interferes with response inhibition.

PubMed

Hartikainen, Kaisa M; Siiskonen, Anna R; Ogawa, Keith H

2012-05-09

A potential threat, such as a spider, captures attention and engages executive functions to adjust ongoing behavior and avoid danger. We and many others have reported slowed responses to neutral targets in the context of emotional distractors. This behavioral slowing has been explained in the framework of attentional competition for limited resources with emotional stimuli prioritized. Alternatively, slowed performance could reflect the activation of avoidance/freezing-type motor behaviors associated with threat. Although the interaction of attention and emotion has been widely studied, little is known on the interaction between emotion and executive functions. We studied how threat-related stimuli (spiders) interact with executive performance and whether the interaction profile fits with a resource competition model or avoidance/freezing-type motor behaviors. Twenty-one young healthy individuals performed a Go-NoGo visual discrimination reaction time (RT) task engaging several executive functions with threat-related and emotionally neutral distractors. The threat-related distractors had no effect on the RT or the error rate in the Go trials. The NoGo error rate, reflecting failure in response inhibition, increased significantly because of threat-related distractors in contrast to neutral distractors, P less than 0.05. Thus, threat-related distractors temporarily impaired response inhibition. Threat-related distractors associated with increased commission errors and no effect on RT does not suggest engagement of avoidance/freezing-type motor behaviors. The results fit in the framework of the resource competition model. A potential threat calls for evaluation of affective significance as well as inhibition of undue emotional reactivity. We suggest that these functions tax executive resources and may render other executive functions, such as response inhibition, temporarily compromised when the demands for resources exceed availability.
Contrasting models of driver behaviour in emergencies using retrospective verbalisations and network analysis.

PubMed

Banks, Victoria A; Stanton, Neville A

2015-01-01

Automated assistance in driving emergencies aims to improve the safety of our roads by avoiding or mitigating the effects of accidents. However, the behavioural implications of such systems remain unknown. This paper introduces the driver decision-making in emergencies (DDMiEs) framework to investigate how the level and type of automation may affect driver decision-making and subsequent responses to critical braking events using network analysis to interrogate retrospective verbalisations. Four DDMiE models were constructed to represent different levels of automation within the driving task and its effects on driver decision-making. Findings suggest that whilst automation does not alter the decision-making pathway (e.g. the processes between hazard detection and response remain similar), it does appear to significantly weaken the links between information-processing nodes. This reflects an unintended yet emergent property within the task network that could mean that we may not be improving safety in the way we expect. This paper contrasts models of driver decision-making in emergencies at varying levels of automation using the Southampton University Driving Simulator. Network analysis of retrospective verbalisations indicates that increasing the level of automation in driving emergencies weakens the link between information-processing nodes essential for effective decision-making.
Teleradiology: a case study of the economic and legal considerations in international trade in telemedicine.

PubMed

McLean, Thomas R; Richards, Edward P

2006-01-01

Growth in the global market for telemedical services is being driven by economics. Two operational models are already recognizable. "Nighthawk" providers are virtually indistinguishable from their domestic counterparts with respect to medical malpractice liability and price for service. Indian providers, in contrast, offer deep price discounts on services, but jurisdictional loopholes are likely to allow these providers a method to avoid medical malpractice liability. Hospitals that outsource their radiology services need to be aware of these differences, because hiring Indian telemedical providers will likely result in a shift of medical malpractice liability from providers to hospitals.
Skill learning and the evolution of social learning mechanisms.

PubMed

van der Post, Daniel J; Franz, Mathias; Laland, Kevin N

2016-08-24

Social learning is potentially advantageous, but evolutionary theory predicts that (i) its benefits may be self-limiting because social learning can lead to information parasitism, and (ii) these limitations can be mitigated via forms of selective copying. However, these findings arise from a functional approach in which learning mechanisms are not specified, and which assumes that social learning avoids the costs of asocial learning but does not produce information about the environment. Whether these findings generalize to all kinds of social learning remains to be established. Using a detailed multi-scale evolutionary model, we investigate the payoffs and information production processes of specific social learning mechanisms (including local enhancement, stimulus enhancement and observational learning) and their evolutionary consequences in the context of skill learning in foraging groups. We find that local enhancement does not benefit foraging success, but could evolve as a side-effect of grouping. In contrast, stimulus enhancement and observational learning can be beneficial across a wide range of environmental conditions because they generate opportunities for new learning outcomes. In contrast to much existing theory, we find that the functional outcomes of social learning are mechanism specific. Social learning nearly always produces information about the environment, and does not always avoid the costs of asocial learning or support information parasitism. Our study supports work emphasizing the value of incorporating mechanistic detail in functional analyses.

Practical Unitary Simulator for Non-Markovian Complex Processes

NASA Astrophysics Data System (ADS)

Binder, Felix C.; Thompson, Jayne; Gu, Mile

2018-06-01

Stochastic processes are as ubiquitous throughout the quantitative sciences as they are notorious for being difficult to simulate and predict. In this Letter, we propose a unitary quantum simulator for discrete-time stochastic processes which requires less internal memory than any classical analogue throughout the simulation. The simulator's internal memory requirements equal those of the best previous quantum models. However, in contrast to previous models, it only requires a (small) finite-dimensional Hilbert space. Moreover, since the simulator operates unitarily throughout, it avoids any unnecessary information loss. We provide a stepwise construction for simulators for a large class of stochastic processes hence directly opening the possibility for experimental implementations with current platforms for quantum computation. The results are illustrated for an example process.
Nuclear Magnetic Resonance Relaxation and Imaging Studies on Water Flow in Soil Cores

NASA Astrophysics Data System (ADS)

Pohlmeier, Andreas; Haber-Pohlmeier, Sabina; Stapf, Siegfried

2010-05-01

Magnetic resonance imaging (MRI) is applied to the study of flow processes in a model and a natural soils core. Since flow velocities in soils are mostly too slow to be monitored directly by MRI flow velocity imaging, Gd-DTPA was used as contrast agent for the first time for flow processes in soils. Apart from its chemical stability the main advantage is the anionic net charge in neutral aqueous solution. Here we can show that this property hinders the adsorption at soil mineral surfaces and therefore retardation. Gd-DTPA turns out to be a very convenient conservative tracer for the investigation of flow processes in model and natural soil cores. With respect to the flow processes in the coaxial model soil column and the natural soil column we found total different flow patterns: In the first case tracer plume moves quite homogeneously only in the inner highly conductive core. No penetration into the outer fine material takes place. In contrast, the natural soil core shows a flow pattern which is characterized by preferential paths avoiding dense regions and preferring loose structures. In the case of the simpler model column also the local flow velocities are calculated by the application of a peak tracking algorithm.
Cerebral venous infarction: a potentially avoidable complication of deep brain stimulation surgery.

PubMed

Morishita, Takashi; Okun, Michael S; Burdick, Adam; Jacobson, Charles E; Foote, Kelly D

2013-01-01

Despite numerous reports on the morbidity and mortality of deep brain stimulation (DBS), cerebral venous infarction has rarely been reported. We present four cases of venous infarct secondary to DBS surgery. The diagnosis of venous infarction was based on 1) delayed onset of new neurologic deficits on postoperative day 1 or 2; 2) significant edema surrounding the superficial aspect of the implanted lead, with or without subcortical hemorrhage on CT scan. Four cases (0.8% per lead, 1.3% per patient) of symptomatic cerebral venous infarction were identified out of 500 DBS lead implantation procedures between July 2002 and August 2009. All four patients had Parkinson's disease. Their DBS leads were implanted in the subthalamic nucleus (n = 2), and the globus pallidus internus (n = 2). Retrospective review of the targeting confirmed that the planned trajectory passed within 3 mm of a cortical vein in two cases for which contrast-enhanced preoperative magnetic resonance (MR) imaging was available. In the other two cases, contrasted targeting images were not obtained preoperatively. Cerebral venous infarction is a potentially avoidable, but serious complication. To minimize its incidence, we propose the use of high-resolution, contrast-enhanced, T1-weighted MR images to delineate cerebral venous anatomy, along with careful stereotactic planning of the lead trajectory to avoid injury to venous structures. © 2013 International Neuromodulation Society.
Phase contrast imaging of preclinical portal vein embolization with CO2 microbubbles.

PubMed

Tang, Rongbiao; Yan, Fuhua; Yang, Guo Yuan; Chen, Ke Min

2017-11-01

Preoperative portal vein embolization (PVE) is employed clinically to avoid postoperative liver insufficiency. Animal models are usually used to study PVE in terms of mechanisms and pathophysiological changes. PVE is formerly monitored by conventional absorption contrast imaging (ACI) with iodine contrast agent. However, the side effects induced by iodine can give rise to animal damage and death. In this study, the feasibility of using phase contrast imaging (PCI) to show PVE using homemade CO 2 microbubbles in living rats has been investigated. CO 2 gas was first formed from the reaction between citric acid and sodium bicarbonate. The CO 2 gas was then encapsulated by egg white to fabricate CO 2 microbubbles. ACI and PCI of CO 2 microbubbles were performed and compared in vitro. An additional increase in contrast was detected in PCI. PCI showed that CO 2 microbubbles gradually dissolved over time, and the remaining CO 2 microbubbles became larger. By PCI, the CO 2 microbubbles were found to have certain stability, suggesting their potential use as embolic agents. CO 2 microbubbles were injected into the main portal trunk to perform PVE in living rats. PCI exploited the differences in the refractive index and facilitated clear visualization of the PVE after the injection of CO 2 microbubbles. Findings from this study suggest that homemade CO 2 microbubbles-based PCI is a novel modality for preclinical PVE research.
Reclaiming the best of the biopsychosocial model of mental health care and 'recovery' for older people through a 'person-centred' approach.

PubMed

McKay, Roderick; McDonald, Regina; Lie, David; McGowan, Helen

2012-12-01

The 'biopsychosocial', 'person-centred care' (PCC) and 'recovery' models of care can be seen as distinct and competing paradigms. This paper proposes an integration of these valuable perspectives and suggestions for effective implementation in health services for the elderly. An overview of PCC and recovery models, and their application for older people with mental health problems, is provided. Their overlap and contrast with the familiar 'biopsychosocial' model of mental health care is considered, together with obstacles to implementation. Utilisation of PCC and recovery concepts allow clinicians to avoid narrow application of the biopsychosocial approach and encourages clinicians to focus on the person's right to autonomy, their values and life goals. Service reform and development is required to embed these concepts into core clinical processes so as to improve outcomes and the quality of life for older people with mental health problems.
Mathematical and information-geometrical entropy for phenomenological Fourier and non-Fourier heat conduction

NASA Astrophysics Data System (ADS)

Li, Shu-Nan; Cao, Bing-Yang

2017-09-01

The second law of thermodynamics governs the direction of heat transport, which provides the foundational definition of thermodynamic Clausius entropy. The definitions of entropy are further generalized for the phenomenological heat transport models in the frameworks of classical irreversible thermodynamics and extended irreversible thermodynamics (EIT). In this work, entropic functions from mathematics are combined with phenomenological heat conduction models and connected to several information-geometrical conceptions. The long-time behaviors of these mathematical entropies exhibit a wide diversity and physical pictures in phenomenological heat conductions, including the tendency to thermal equilibrium, and exponential decay of nonequilibrium and asymptotics, which build a bridge between the macroscopic and microscopic modelings. In contrast with the EIT entropies, the mathematical entropies expressed in terms of the internal energy function can avoid singularity paired with nonpositive local absolute temperature caused by non-Fourier heat conduction models.
Parental modelling and prompting effects on acceptance of a novel fruit in 2-4-year-old children are dependent on children's food responsiveness.

PubMed

Blissett, Jackie; Bennett, Carmel; Fogel, Anna; Harris, Gillian; Higgs, Suzanne

2016-02-14

Few children consume the recommended portions of fruit or vegetables. This study examined the effects of parental physical prompting and parental modelling in children's acceptance of a novel fruit (NF) and examined the role of children's food-approach and food-avoidance traits on NF engagement and consumption. A total of 120 caregiver-child dyads (fifty-four girls, sixty-six boys) participated in this study. Dyads were allocated to one of the following three conditions: physical prompting but no modelling, physical prompting and modelling or a modelling only control condition. Dyads ate a standardised meal containing a portion of a fruit new to the child. Parents completed measures of children's food approach and avoidance. Willingness to try the NF was observed, and the amount of the NF consumed was measured. Physical prompting but no modelling resulted in greater physical refusal of the NF. There were main effects of enjoyment of food and food fussiness on acceptance. Food responsiveness interacted with condition such that children who were more food responsive had greater NF acceptance in the prompting and modelling conditions in comparison with the modelling only condition. In contrast, children with low food responsiveness had greater acceptance in the modelling control condition than in the prompting but no modelling condition. Physical prompting in the absence of modelling is likely to be detrimental to NF acceptance. Parental use of physical prompting strategies, in combination with modelling of NF intake, may facilitate acceptance of NF, but only in food-responsive children. Modelling consumption best promotes acceptance in children with low food responsiveness.
Critical roles for anterior insula and dorsal striatum in punishment-based avoidance learning.

PubMed

Palminteri, Stefano; Justo, Damian; Jauffret, Céline; Pavlicek, Beth; Dauta, Aurélie; Delmaire, Christine; Czernecki, Virginie; Karachi, Carine; Capelle, Laurent; Durr, Alexandra; Pessiglione, Mathias

2012-12-06

The division of human learning systems into reward and punishment opponent modules is still a debated issue. While the implication of ventral prefrontostriatal circuits in reward-based learning is well established, the neural underpinnings of punishment-based learning remain unclear. To elucidate the causal implication of brain regions that were related to punishment learning in a previous functional neuroimaging study, we tested the effects of brain damage on behavioral performance, using the same task contrasting monetary gains and losses. Cortical and subcortical candidate regions, the anterior insula and dorsal striatum, were assessed in patients presenting brain tumor and Huntington disease, respectively. Both groups exhibited selective impairment of punishment-based learning. Computational modeling suggested complementary roles for these structures: the anterior insula might be involved in learning the negative value of loss-predicting cues, whereas the dorsal striatum might be involved in choosing between those cues so as to avoid the worst. Copyright © 2012 Elsevier Inc. All rights reserved.
Radioprotection and contrast agent use in pediatrics: what, how, and when.

PubMed

Lancharro Zapata, Á M; Rodríguez, C Marín

2016-05-01

It is essential to minimize exposure to ionizing radiation in children for various reasons. The risk of developing a tumor from exposure to a given dose of radiation is greater in childhood. Various strategies can be used to reduce exposure to ionizing radiation. It is fundamental to avoid unnecessary tests and tests that are not indicated, to choose an alternative test that does not use ionizing radiation, and/or to take a series of measures that minimize the dose of radiation that the patient receives, such as avoiding having to repeat tests, using the appropriate projections, using shields, adjusting the protocol (mAs, Kv, or pitch) to the patient's body volume, etc… When contrast agents are necessary, intracavitary ultrasound agents can be used, although the use of ultrasound agents is also being extended to include intravenous administration. In fluoroscopy, contrast agents with low osmolarity must be used, as in CT where we must adjust the dose and speed of injection to the patient's weight and to the caliber of the peripheral line, respectively. In MRI, only three types of contrast agents have been approved for pediatric use. It is sometimes necessary to use double doses or organ-specific contrast agents in certain clinical situations; the safety of contrast agents for these indications has not been proven, so they must be used off label. Copyright © 2016 SERAM. Published by Elsevier España, S.L.U. All rights reserved.
The Westermarck Hypothesis and the Israeli Kibbutzim: Reconciling Contrasting Evidence.

PubMed

Shor, Eran

2015-11-01

The case of the communal education system in the Israeli kibbutzim is often considered to provide conclusive support for Westermarck's (1891) assertion regarding the existence of evolutionary inbreeding avoidance mechanisms in humans. However, recent studies that have gone back to the kibbutzim seem to provide contrasting evidence and reopen the discussion regarding the case of the kibbutzim and inbreeding avoidance more generally (Lieberman & Lobel, 2012; Shor & Simchai, 2009). In this article, I reassess the case of the kibbutzim, reevaluating the findings and conclusions of these recent research endeavors. I argue that the differences between recent research reports largely result from conceptual and methodological differences and that, in fact, these studies provide insights that are more similar than first meets the eye. I also suggest that we must reexamine the common assumption that the kibbutzim serve as an ideal natural experiment for examining the sources of incest avoidance and the incest taboo. Finally, I discuss the implications of these studies to the longstanding debate over the Westermarck hypothesis and call for a synthetic theoretical framework that produces more precise predictions and more rigorous empirical research designs.
Roles of inter-individual differences and intra-individual acute elevations in early smoking lapse in people with posttraumatic stress disorder.

PubMed

Dedert, Eric A; Hicks, Terrell A; Dennis, Paul A; Calhoun, Patrick S; Beckham, Jean C

2016-09-01

Existing models of the role of posttraumatic stress disorder (PTSD) symptoms and smoking have almost exclusively examined mean symptom levels, rather than the acute elevations that might trigger smoking lapse immediately or increase risk of a smoking lapse in the next few hours. We examined ecological momentary assessments (EMA) of PTSD symptom clusters and smoking in the first week of a quit attempt in 52 people with PTSD. In multilevel models including PTSD symptom means, acute elevations, and lagged acute elevations together as simultaneous predictors of odds of smoking in the same models, pre-quit smoking occasions were significantly related to acute elevations in symptoms, including PTSD totals (OR=1.20; 95% CI, 1.10 to 1.31), PTSD re-experiencing symptoms (OR=1.16; 95% CI, 1.06 to 1.27), PTSD avoidance symptoms (OR=1.20; 95% CI, 1.10 to 1.31), PTSD numbing symptoms (OR=1.14; 95% CI, 1.04 to 1.24), and PTSD hyperarousal symptoms (OR=1.20; 95% CI, 1.09 to 1.31). In contrast, post-quit smoking was related to lagged acute elevations in PTSD re-experiencing (OR=1.24, 95% CI, 1.03 to 1.50) avoidance (OR=1.27, 95% CI, 1.05 to 1.53), and numbing symptoms (OR=1.24, 95% CI, 1.02 to 1.51). During a quit attempt, individuals with PTSD delayed smoking in response to acute elevations in PTSD re-experiencing and Avoidance. This period presents an opportunity to use mobile health interventions to prevent smoking lapse and to use coping skills acquired in trauma-focused therapy to respond to acute PTSD symptom elevation. Published by Elsevier Ltd.
The Color Red Supports Avoidance Reactions to Unhealthy Food.

PubMed

Rohr, Michaela; Kamm, Friederike; Koenigstorfer, Joerg; Groeppel-Klein, Andrea; Wentura, Dirk

2015-01-01

Empirical evidence suggests that the color red acts like an implicit avoidance cue in food contexts. Thus specific colors seem to guide the implicit evaluation of food items. We built upon this research by investigating the implicit meaning of color (red vs. green) in an approach-avoidance task with healthy and unhealthy food items. Thus, we examined the joint evaluative effects of color and food: Participants had to categorize food items by approach-avoidance reactions, according to their healthfulness. Items were surrounded by task-irrelevant red or green circles. We found that the implicit meaning of the traffic light colors influenced participants' reactions to the food items. The color red (compared to green) facilitated automatic avoidance reactions to unhealthy foods. By contrast, approach behavior toward healthy food items was not moderated by color. Our findings suggest that traffic light colors can act as implicit cues that guide automatic behavioral reactions to food.
Life-threatening event reduces subjective well-being through activating avoidance motivation: a longitudinal study.

PubMed

Van Dijk, Dina; Seger-Guttmann, Tali; Heller, Daniel

2013-04-01

Drawing on the approach-avoidance theory, we have examined the role of avoidance motivation in explaining the negative effects of a life-threatening event on subjective well-being (SWB). Residents of the south of Israel were surveyed during heavy missile attacks in January 2009 (T1; n = 283), and again after 6 months (T2; n = 212) and 1 year (T3; n = 154). During the missile attacks, we also surveyed a group from the center of the country (T1; n = 102), not exposed to the attacks. The results indicate that avoidance motivation was activated by the life threat and further mediated its detrimental influence on SWB measures (positive/negative affects, anxiety, and subjective health). Moreover, within the southern sample, the drop in avoidance motivation over time mediated the parallel drop in SWB. In contrast to avoidance motivation, approach motivation remained stable over time and was related to positive emotions. The role of avoidance and approach motivations in life-threatening situations is further discussed. PsycINFO Database Record (c) 2013 APA, all rights reserved.
INFLUENCE OF PARENT-ADOLESCENT CONFLICT FREQUENCY ON ADOLESCENT FAMILY SATISFACTION AND SELF-SATISFACTION IN CHINA: CONFLICT COPING TACTICS AS MODERATORS.

PubMed

Zhao, Hongyu; Xu, Yan; Wang, Fang; Jiang, Jiang; Zhang, Xiaohui

2015-12-01

Existing studies have found that parent-adolescent conflict frequency and conflict coping tactics influence adolescent family satisfaction and self-satisfaction under the background of Western culture. However, due to differences between Eastern and Western cultures, it is unknown whether previous results of the Western population can be extended to Chinese adolescents. The present study investigated grade differences in parent-adolescent conflict frequency and conflict coping tactics and examined the moderating effects of conflict coping tactics on the relationships between conflict frequency and adolescent family satisfaction and between conflict frequency and adolescent self-satisfaction. Chinese adolescents in Grades 7, 8, 10, and 11 (N = 524) completed measures on conflict frequency, conflict coping tactics, family satisfaction, and self-satisfaction. An analysis of variance (ANOVA) and structural equation model analyses found, first, that conflict frequency decreased with grade level. For coping tactics, conciliation, avoidance, and assertion behaviors increased with grade level. Second, conflict frequency was negatively related to family satisfaction regardless of conciliation and avoidance tactics. By contrast, conflict frequency was negatively related to self-satisfaction when high conciliation and high avoidance behaviors were practiced. In addition, at low conflict frequency conciliation was positively associated with self-satisfaction and was not significant at high conflict frequency.
Reactive Collision Avoidance Algorithm

NASA Technical Reports Server (NTRS)

Scharf, Daniel; Acikmese, Behcet; Ploen, Scott; Hadaegh, Fred

2010-01-01

The reactive collision avoidance (RCA) algorithm allows a spacecraft to find a fuel-optimal trajectory for avoiding an arbitrary number of colliding spacecraft in real time while accounting for acceleration limits. In addition to spacecraft, the technology can be used for vehicles that can accelerate in any direction, such as helicopters and submersibles. In contrast to existing, passive algorithms that simultaneously design trajectories for a cluster of vehicles working to achieve a common goal, RCA is implemented onboard spacecraft only when an imminent collision is detected, and then plans a collision avoidance maneuver for only that host vehicle, thus preventing a collision in an off-nominal situation for which passive algorithms cannot. An example scenario for such a situation might be when a spacecraft in the cluster is approaching another one, but enters safe mode and begins to drift. Functionally, the RCA detects colliding spacecraft, plans an evasion trajectory by solving the Evasion Trajectory Problem (ETP), and then recovers after the collision is avoided. A direct optimization approach was used to develop the algorithm so it can run in real time. In this innovation, a parameterized class of avoidance trajectories is specified, and then the optimal trajectory is found by searching over the parameters. The class of trajectories is selected as bang-off-bang as motivated by optimal control theory. That is, an avoiding spacecraft first applies full acceleration in a constant direction, then coasts, and finally applies full acceleration to stop. The parameter optimization problem can be solved offline and stored as a look-up table of values. Using a look-up table allows the algorithm to run in real time. Given a colliding spacecraft, the properties of the collision geometry serve as indices of the look-up table that gives the optimal trajectory. For multiple colliding spacecraft, the set of trajectories that avoid all spacecraft is rapidly searched on-line. The optimal avoidance trajectory is implemented as a receding-horizon model predictive control law. Therefore, at each time step, the optimal avoidance trajectory is found and the first time step of its acceleration is applied. At the next time step of the control computer, the problem is re-solved and the new first time step is again applied. This continual updating allows the RCA algorithm to adapt to a colliding spacecraft that is making erratic course changes.
Gaze direction differentially affects avoidance tendencies to happy and angry faces in socially anxious individuals.

PubMed

Roelofs, Karin; Putman, Peter; Schouten, Sonja; Lange, Wolf-Gero; Volman, Inge; Rinck, Mike

2010-04-01

Increasing evidence indicates that eye gaze direction affects the processing of emotional faces in anxious individuals. However, the effects of eye gaze direction on the behavioral responses elicited by emotional faces, such as avoidance behavior, remain largely unexplored. We administered an Approach-Avoidance Task (AAT) in high (HSA) and low socially anxious (LSA) individuals. All participants responded to photographs of angry, happy and neutral faces (presented with direct and averted gaze), by either pushing a joystick away from them (avoidance) or pulling it towards them (approach). Compared to LSA, HSA were faster in avoiding than approaching angry faces. Most crucially, this avoidance tendency was only present when the perceived anger was directed towards the subject (direct gaze) and not when the gaze of the face-stimulus was averted. In contrast, HSA individuals tended to avoid happy faces irrespectively of gaze direction. Neutral faces elicited no approach-avoidance tendencies. Thus avoidance of angry faces in social anxiety as measured by AA-tasks reflects avoidance of subject-directed anger and not of negative stimuli in general. In addition, although both anger and joy are considered to reflect approach-related emotions, gaze direction did not affect HSA's avoidance of happy faces, suggesting differential mechanisms affecting responses to happy and angry faces in social anxiety. 2009 Elsevier Ltd. All rights reserved.
Naturalness preservation image contrast enhancement via histogram modification

NASA Astrophysics Data System (ADS)

Tian, Qi-Chong; Cohen, Laurent D.

2018-04-01

Contrast enhancement is a technique for enhancing image contrast to obtain better visual quality. Since many existing contrast enhancement algorithms usually produce over-enhanced results, the naturalness preservation is needed to be considered in the framework of image contrast enhancement. This paper proposes a naturalness preservation contrast enhancement method, which adopts the histogram matching to improve the contrast and uses the image quality assessment to automatically select the optimal target histogram. The contrast improvement and the naturalness preservation are both considered in the target histogram, so this method can avoid the over-enhancement problem. In the proposed method, the optimal target histogram is a weighted sum of the original histogram, the uniform histogram, and the Gaussian-shaped histogram. Then the structural metric and the statistical naturalness metric are used to determine the weights of corresponding histograms. At last, the contrast-enhanced image is obtained via matching the optimal target histogram. The experiments demonstrate the proposed method outperforms the compared histogram-based contrast enhancement algorithms.
Study on Earthquake Emergency Evacuation Drill Trainer Development

NASA Astrophysics Data System (ADS)

ChangJiang, L.

2016-12-01

With the improvement of China's urbanization, to ensure people survive the earthquake needs scientific routine emergency evacuation drills. Drawing on cellular automaton, shortest path algorithm and collision avoidance, we designed a model of earthquake emergency evacuation drill for school scenes. Based on this model, we made simulation software for earthquake emergency evacuation drill. The software is able to perform the simulation of earthquake emergency evacuation drill by building spatial structural model and selecting the information of people's location grounds on actual conditions of constructions. Based on the data of simulation, we can operate drilling in the same building. RFID technology could be used here for drill data collection which read personal information and send it to the evacuation simulation software via WIFI. Then the simulation software would contrast simulative data with the information of actual evacuation process, such as evacuation time, evacuation path, congestion nodes and so on. In the end, it would provide a contrastive analysis report to report assessment result and optimum proposal. We hope the earthquake emergency evacuation drill software and trainer can provide overall process disposal concept for earthquake emergency evacuation drill in assembly occupancies. The trainer can make the earthquake emergency evacuation more orderly, efficient, reasonable and scientific to fulfill the increase in coping capacity of urban hazard.
Ageism among Israeli students: structure and demographic influences.

PubMed

Bodner, Ehud; Lazar, Aryeh

2008-10-01

Research concerning negative attitudes toward the elderly among samples of North American respondents has uncovered two distinct yet comparable three-factor structures: (1) avoidance, antilocution and separation; and (2) discrimination, stereotypes and affective attitudes. In addition, previous research has demonstrated that men and younger people have more negative attitudes toward the elderly than do women and older people. The aim of this study is to examine the extent to which these findings can be generalized to individuals from a different culture. The Fraboni Scale of Ageism (FSA) was administered to 491 Israeli participants aged 20-50 years. Exploratory factor analysis with varimax rotation uncovered a three-factor structure, similar to previous investigations. In contrast to the literature, however, no simple group (gender, age) differences were found for ageism. However, discriminant function analysis revealed a more complex relationship between age, gender and ageism. Older males, in contrast to older females, demonstrated a tendency to perceptions of the elderly that associated avoidance of the elderly with negative stereotypes whereas older females, in contrast to younger females, held perceptions that associated avoidance of the elderly with a negative perception of the elderly person's contribution to society. Despite cultural differences between Israel and North America, the similarity of findings provides support for the generalizabilty of the structure of attitudes toward the elderly as measured by the FSA to various cultures. In addition, the combined effect of age and gender on differential forms of ageism is complex and should be examined in future research.
A clinical perspective on a pain neuroscience education approach to manual therapy.

PubMed

Louw, Adriaan; Nijs, Jo; Puentedura, Emilio J

2017-07-01

In recent years, there has been an increased interest in pain neuroscience education (PNE) in physical therapy. There is growing evidence for the efficacy of PNE to decrease pain, disability, fear-avoidance, pain catastrophization, limited movement, and health care utilization in people struggling with pain. PNE teaches people in pain more about the biology and physiology of their pain experience including processes such as central sensitization, peripheral sensitization, allodynia, inhibition, facilitation, neuroplasticity and more. PNE's neurobiological model often finds itself at odds with traditional biomedical models used in physical therapy. Traditional biomedical models, focusing on anatomy, pathoanatomy, and biomechanics have been shown to have limited efficacy in helping people understand their pain, especially chronic pain, and may in fact even increase a person's pain experience by increasing fear-avoidance and pain catastrophization. An area of physical therapy where the biomedical model is used a lot is manual therapy. This contrast between PNE and manual therapy has seemingly polarized followers from each approach to see PNE as a 'hands-off' approach even having clinicians categorize patients as either in need of receiving PNE (with no hands-on), or hands-on with no PNE. In this paper, we explore the notion of PNE and manual therapy co-existing. PNE research has shown to have immediate effects of various clinical signs and symptoms associated with central sensitization. Using a model of sensitization (innocuous, noxious, and allodynia), we argue that PNE can be used in a manual therapy model, especially treating someone where the nervous system has become increasingly hypervigilant. Level of Evidence : VII.

Are Regional Habitat Models Useful at a Local-Scale? A Case Study of Threatened and Common Insectivorous Bats in South-Eastern Australia

PubMed Central

McConville, Anna; Law, Bradley S.; Mahony, Michael J.

2013-01-01

Habitat modelling and predictive mapping are important tools for conservation planning, particularly for lesser known species such as many insectivorous bats. However, the scale at which modelling is undertaken can affect the predictive accuracy and restrict the use of the model at different scales. We assessed the validity of existing regional-scale habitat models at a local-scale and contrasted the habitat use of two morphologically similar species with differing conservation status (Mormopterus norfolkensis and Mormopterus species 2). We used negative binomial generalised linear models created from indices of activity and environmental variables collected from systematic acoustic surveys. We found that habitat type (based on vegetation community) best explained activity of both species, which were more active in floodplain areas, with most foraging activity recorded in the freshwater wetland habitat type. The threatened M. norfolkensis avoided urban areas, which contrasts with M. species 2 which occurred frequently in urban bushland. We found that the broad habitat types predicted from local-scale models were generally consistent with those from regional-scale models. However, threshold-dependent accuracy measures indicated a poor fit and we advise caution be applied when using the regional models at a fine scale, particularly when the consequences of false negatives or positives are severe. Additionally, our study illustrates that habitat type classifications can be important predictors and we suggest they are more practical for conservation than complex combinations of raw variables, as they are easily communicated to land managers. PMID:23977296
Pediatric fear-avoidance model of chronic pain: Foundation, application and future directions

PubMed Central

Asmundson, Gordon JG; Noel, Melanie; Petter, Mark; Parkerson, Holly A

2012-01-01

The fear-avoidance model of chronic musculoskeletal pain has become an increasingly popular conceptualization of the processes and mechanisms through which acute pain can become chronic. Despite rapidly growing interest and research regarding the influence of fear-avoidance constructs on pain-related disability in children and adolescents, there have been no amendments to the model to account for unique aspects of pediatric chronic pain. A comprehensive understanding of the role of fear-avoidance in pediatric chronic pain necessitates understanding of both child/adolescent and parent factors implicated in its development and maintenance. The primary purpose of the present article is to propose an empirically-based pediatric fear-avoidance model of chronic pain that accounts for both child/adolescent and parent factors as well as their potential interactive effects. To accomplish this goal, the present article will define important fear-avoidance constructs, provide a summary of the general fear-avoidance model and review the growing empirical literature regarding the role of fear-avoidance constructs in pediatric chronic pain. Assessment and treatment options for children with chronic pain will also be described in the context of the proposed pediatric fear-avoidance model of chronic pain. Finally, avenues for future investigation will be proposed. PMID:23248813
Pediatric fear-avoidance model of chronic pain: foundation, application and future directions.

PubMed

Asmundson, Gordon J G; Noel, Melanie; Petter, Mark; Parkerson, Holly A

2012-01-01

The fear-avoidance model of chronic musculoskeletal pain has become an increasingly popular conceptualization of the processes and mechanisms through which acute pain can become chronic. Despite rapidly growing interest and research regarding the influence of fear-avoidance constructs on pain-related disability in children and adolescents, there have been no amendments to the model to account for unique aspects of pediatric chronic pain. A comprehensive understanding of the role of fear-avoidance in pediatric chronic pain necessitates understanding of both child⁄adolescent and parent factors implicated in its development and maintenance. The primary purpose of the present article is to propose an empirically-based pediatric fear-avoidance model of chronic pain that accounts for both child⁄adolescent and parent factors as well as their potential interactive effects. To accomplish this goal, the present article will define important fear-avoidance constructs, provide a summary of the general fear-avoidance model and review the growing empirical literature regarding the role of fear-avoidance constructs in pediatric chronic pain. Assessment and treatment options for children with chronic pain will also be described in the context of the proposed pediatric fear-avoidance model of chronic pain. Finally, avenues for future investigation will be proposed.
Approximate dynamic programming approaches for appointment scheduling with patient preferences.

PubMed

Li, Xin; Wang, Jin; Fung, Richard Y K

2018-04-01

During the appointment booking process in out-patient departments, the level of patient satisfaction can be affected by whether or not their preferences can be met, including the choice of physicians and preferred time slot. In addition, because the appointments are sequential, considering future possible requests is also necessary for a successful appointment system. This paper proposes a Markov decision process model for optimizing the scheduling of sequential appointments with patient preferences. In contrast to existing models, the evaluation of a booking decision in this model focuses on the extent to which preferences are satisfied. Characteristics of the model are analysed to develop a system for formulating booking policies. Based on these characteristics, two types of approximate dynamic programming algorithms are developed to avoid the curse of dimensionality. Experimental results suggest directions for further fine-tuning of the model, as well as improving the efficiency of the two proposed algorithms. Copyright © 2018 Elsevier B.V. All rights reserved.
Computer-aided global breast MR image feature analysis for prediction of tumor response to chemotherapy: performance assessment

NASA Astrophysics Data System (ADS)

Aghaei, Faranak; Tan, Maxine; Hollingsworth, Alan B.; Zheng, Bin; Cheng, Samuel

2016-03-01

Dynamic contrast-enhanced breast magnetic resonance imaging (DCE-MRI) has been used increasingly in breast cancer diagnosis and assessment of cancer treatment efficacy. In this study, we applied a computer-aided detection (CAD) scheme to automatically segment breast regions depicting on MR images and used the kinetic image features computed from the global breast MR images acquired before neoadjuvant chemotherapy to build a new quantitative model to predict response of the breast cancer patients to the chemotherapy. To assess performance and robustness of this new prediction model, an image dataset involving breast MR images acquired from 151 cancer patients before undergoing neoadjuvant chemotherapy was retrospectively assembled and used. Among them, 63 patients had "complete response" (CR) to chemotherapy in which the enhanced contrast levels inside the tumor volume (pre-treatment) was reduced to the level as the normal enhanced background parenchymal tissues (post-treatment), while 88 patients had "partially response" (PR) in which the high contrast enhancement remain in the tumor regions after treatment. We performed the studies to analyze the correlation among the 22 global kinetic image features and then select a set of 4 optimal features. Applying an artificial neural network trained with the fusion of these 4 kinetic image features, the prediction model yielded an area under ROC curve (AUC) of 0.83+/-0.04. This study demonstrated that by avoiding tumor segmentation, which is often difficult and unreliable, fusion of kinetic image features computed from global breast MR images without tumor segmentation can also generate a useful clinical marker in predicting efficacy of chemotherapy.
Drought stress limits the geographic ranges of two tree species via different physiological mechanisms.

PubMed

Anderegg, Leander D L; HilleRisLambers, Janneke

2016-03-01

Range shifts are among the most ubiquitous ecological responses to anthropogenic climate change and have large consequences for ecosystems. Unfortunately, the ecophysiological forces that constrain range boundaries are poorly understood, making it difficult to mechanistically project range shifts. To explore the physiological mechanisms by which drought stress controls dry range boundaries in trees, we quantified elevational variation in drought tolerance and in drought avoidance-related functional traits of a widespread gymnosperm (ponderosa pine - Pinus ponderosa) and angiosperm (trembling aspen - Populus tremuloides) tree species in the southwestern USA. Specifically, we quantified tree-to-tree variation in growth, water stress (predawn and midday xylem tension), drought avoidance traits (branch conductivity, leaf/needle size, tree height, leaf area-to-sapwood area ratio), and drought tolerance traits (xylem resistance to embolism, hydraulic safety margin, wood density) at the range margins and range center of each species. Although water stress increased and growth declined strongly at lower range margins of both species, ponderosa pine and aspen showed contrasting patterns of clinal trait variation. Trembling aspen increased its drought tolerance at its dry range edge by growing stronger but more carbon dense branch and leaf tissues, implying an increased cost of growth at its range boundary. By contrast, ponderosa pine showed little elevational variation in drought-related traits but avoided drought stress at low elevations by limiting transpiration through stomatal closure, such that its dry range boundary is associated with limited carbon assimilation even in average climatic conditions. Thus, the same climatic factor (drought) may drive range boundaries through different physiological mechanisms - a result that has important implications for process-based modeling approaches to tree biogeography. Further, we show that comparing intraspecific patterns of trait variation across ranges, something rarely done in a range-limit context, helps elucidate a mechanistic understanding of range constraints. © 2015 John Wiley & Sons Ltd.
Analysis of multilayer and single layer X-ray detectors for contrast-enhanced mammography using imaging task

NASA Astrophysics Data System (ADS)

Allec, Nicholas; Abbaszadeh, Shiva; Karim, Karim S.

2011-03-01

A multilayer (single-shot) detector has previously been proposed for contrast-enhanced mammography. The multilayer detector has the benefit of avoiding motion artifacts due to simultaneous acquisition of both high and low energy images. A single layer (dual-shot) detector has the benefit of better control over the energy separation since the incident beams can be produced and filtered separately. In this paper the performance of the multilayer detector is compared to that of a single layer detector using an ideal observer detectability index which is determined from an extended cascaded systems model and a defined imaging task. The detectors are assumed to have amorphous selenium direct conversion layers, however the same theoretical techniques used here may be applied to other types of integrating detectors. The anatomical noise caused by variation of glandularity within the breast is known to dominate the noise power spectrum at low frequencies due to its inverse power law dependence and is thus taken into account in our model to provide an accurate estimate of the detectability index. The conditions leading to the optimal detectability index, such as tube voltage, filtration, and weight factor are reported for both detector designs.
Modeling a color-rendering operator for high dynamic range images using a cone-response function

NASA Astrophysics Data System (ADS)

Choi, Ho-Hyoung; Kim, Gi-Seok; Yun, Byoung-Ju

2015-09-01

Tone-mapping operators are the typical algorithms designed to produce visibility and the overall impression of brightness, contrast, and color of high dynamic range (HDR) images on low dynamic range (LDR) display devices. Although several new tone-mapping operators have been proposed in recent years, the results of these operators have not matched those of the psychophysical experiments based on the human visual system. A color-rendering model that is a combination of tone-mapping and cone-response functions using an XYZ tristimulus color space is presented. In the proposed method, the tone-mapping operator produces visibility and the overall impression of brightness, contrast, and color in HDR images when mapped onto relatively LDR devices. The tone-mapping resultant image is obtained using chromatic and achromatic colors to avoid well-known color distortions shown in the conventional methods. The resulting image is then processed with a cone-response function wherein emphasis is placed on human visual perception (HVP). The proposed method covers the mismatch between the actual scene and the rendered image based on HVP. The experimental results show that the proposed method yields an improved color-rendering performance compared to conventional methods.
Electronic magnification and perceived contrast of video

PubMed Central

Haun, Andrew; Woods, Russell L; Peli, Eli

2012-01-01

Electronic magnification of an image results in a decrease in its perceived contrast. The decrease in perceived contrast could be due to a perceived blur or to limited sampling of the range of contrasts in the original image. We measured the effect on perceived contrast of magnification in two contexts: either a small video was enlarged to fill a larger area, or a portion of a larger video was enlarged to fill the same area as the original. Subjects attenuated the source video contrast to match the perceived contrast of the magnified videos, with the effect increasing with magnification and decreasing with viewing distance. These effects are consistent with expectations based on both the contrast statistics of natural images and the contrast sensitivity of the human visual system. We demonstrate that local regions within videos usually have lower physical contrast than the whole, and that this difference accounts for a minor part of the perceived differences. Instead, visibility of ‘missing content’ (blur) in a video is misinterpreted as a decrease in contrast. We detail how the effects of magnification on perceived contrast can be measured while avoiding confounding factors. PMID:23483111
Choosing the right diagnostic imaging modality in musculoskeletal diagnosis.

PubMed

Aagesen, Andrea L; Melek, Maged

2013-12-01

Radiological studies can confirm or rule out competing diagnoses for musculoskeletal injuries and pain. Obtaining a detailed history and physical examination is pivotal for localizing the pain generator and choosing the most appropriate imaging studies, based on the suspected injured tissue. Judicious use of imaging is important to avoid unnecessary radiation exposure, minimize cost, and avoid therapy targeting asymptomatic imaging abnormalities. This article compares and contrasts the diagnostic imaging commonly used for detecting musculoskeletal injuries. Copyright © 2013 Elsevier Inc. All rights reserved.
Successive and discrete spaced conditioning in active avoidance learning in young and aged zebrafish.

PubMed

Yang, Peng; Kajiwara, Riki; Tonoki, Ayako; Itoh, Motoyuki

2018-05-01

We designed an automated device to study active avoidance learning abilities of zebrafish. Open source tools were used for the device control, statistical computing, and graphic outputs of data. Using the system, we developed active avoidance tests to examine the effects of trial spacing and aging on learning. Seven-month-old fish showed stronger avoidance behavior as measured by color preference index with discrete spaced training as compared to successive spaced training. Fifteen-month-old fish showed a similar trend, but with reduced cognitive abilities compared with 7-month-old fish. Further, in 7-month-old fish, an increase in learning ability during trials was observed with discrete, but not successive, spaced training. In contrast, 15-month-old fish did not show increase in learning ability during trials. Therefore, these data suggest that discrete spacing is more effective for learning than successive spacing, with the zebrafish active avoidance paradigm, and that the time course analysis of active avoidance using discrete spaced training is useful to detect age-related learning impairment. Copyright © 2017 Elsevier Ireland Ltd and Japan Neuroscience Society. All rights reserved.
Psychopaths lack the automatic avoidance of social threat: relation to instrumental aggression.

PubMed

Louise von Borries, Anna Katinka; Volman, Inge; de Bruijn, Ellen Rosalia Aloïs; Bulten, Berend Hendrik; Verkes, Robbert Jan; Roelofs, Karin

2012-12-30

Psychopathy (PP) is associated with marked abnormalities in social emotional behaviour, such as high instrumental aggression (IA). A crucial but largely ignored question is whether automatic social approach-avoidance tendencies may underlie this condition. We tested whether offenders with PP show lack of automatic avoidance tendencies, usually activated when (healthy) individuals are confronted with social threat stimuli (angry faces). We applied a computerized approach-avoidance task (AAT), where participants pushed or pulled pictures of emotional faces using a joystick, upon which the faces decreased or increased in size, respectively. Furthermore, participants completed an emotion recognition task which was used to control for differences in recognition of facial emotions. In contrast to healthy controls (HC), PP patients showed total absence of avoidance tendencies towards angry faces. Interestingly, those responses were related to levels of instrumental aggression and the (in)ability to experience personal distress (PD). These findings suggest that social performance in psychopaths is disturbed on a basic level of automatic action tendencies. The lack of implicit threat avoidance tendencies may underlie their aggressive behaviour. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
Group-size-mediated habitat selection and group fusion-fission dynamics of bison under predation risk.

PubMed

Fortin, Daniel; Fortin, Marie-Eve; Beyer, Hawthorne L; Duchesne, Thierry; Courant, Sabrina; Dancose, Karine

2009-09-01

For gregarious animals the cost-benefit trade-offs that drive habitat selection may vary dynamically with group size, which plays an important role in foraging and predator avoidance strategies. We examined how habitat selection by bison (Bison bison) varied as a function of group size and interpreted these patterns by testing whether habitat selection was more strongly driven by the competing demands of forage intake vs. predator avoidance behavior. We developed an analytical framework that integrated group size into resource selection functions (RSFs). These group-size-dependent RSFs were based on a matched case-control design and were estimated using conditional logistic regression (mixed and population-averaged models). Fitting RSF models to bison revealed that bison groups responded to multiple aspects of landscape heterogeneity and that selection varied seasonally and as a function of group size. For example, roads were selected in summer, but not in winter. Bison groups avoided areas of high snow water equivalent in winter. They selected areas composed of a large proportion of meadow area within a 700-m radius, and within those areas, bison selected meadows. Importantly, the strength of selection for meadows varied as a function of group size, with stronger selection being observed in larger groups. Hence the bison-habitat relationship depended in part on the dynamics of group formation and division. Group formation was most likely in meadows. In contrast, risk of group fission increased when bison moved into the forest and was higher during the time of day when movements are generally longer and more variable among individuals. We also found that stronger selection for meadows by large rather than small bison groups was caused by longer residence time in individual meadows by larger groups and that departure from meadows appears unlikely to result from a depression in food intake rate. These group-size-dependent patterns were consistent with the hypothesis that avoidance of predation risk is the strongest driver of habitat selection.
Clozapine and Olanzapine Exhibit an Intrinsic Anxiolytic Property in Two Conditioned Fear Paradigms: Contrast with Haloperidol and Chlordiazepoxide

PubMed Central

Mead, Alexa; Li, Ming; Kapur, Shitij

2008-01-01

Psychotic fear and anxiety disturbances are seen at a relatively high frequency in patients with schizophrenia. Atypical antipsychotics are believed to show superior efficacy in reducing these symptoms. However, clinical and preclinical evidence regarding their anxiolytic efficacy has been mixed. In this study, we evaluated the possible anxiolytic property of two atypicals clozapine and olanzapine and compared them with typical haloperidol and chlordiazepoxide (a prototype of sedative-anxiolytic drug) in two preclinical models of fear. In Experiment 1, we used a fear-induced passive avoidance and conditioned place aversion paradigm and examined the effects of clozapine (20 mg/kg, sc), haloperidol (0.05 mg/kg, sc) and chlordiazepoxide (10 mg/kg, ip). In Experiments 2 and 3, we used a two-way active avoidance conditioning paradigm and further compared the effects of clozapine (20 mg/kg, sc), haloperidol (0.05 mg/kg, sc), chlordiazepoxide (10 mg/kg, ip) and three doses of olanzapine (0.5, 1.0, and 2.0 mg/kg, sc). Results show that clozapine and chlordiazepoxide, but not haloperidol, significantly attenuated the shock conditioning-induced place aversion, decreased the amount of defecations and the number of the 22 kHz vocalizations. Clozapine also reduced the shock conditioning-induced hyperthermia. Similar to clozapine, olanzapine also significantly decreased the amount of defecations and reduced the shock conditioning-induced hyperthermia, but it did not inhibit the 22 kHz vocalizations. This study demonstrates that clozapine and olanzapine possess an intrinsic anxiolytic property, which is not attributable to its superior anti-“psychotic” effect or its favorable effects on motor functions or learning and memory processes. These findings also suggest that the combined use of passive avoidance and active avoidance conditioning models can be useful in better differentiating typical and atypical antipsychotics as well as anxiolytics. PMID:18547622
Avoidance behavior of juvenile lake sturgeon (Acipenser fulvescens) exposed to Bayluscide 3.2% Granular Sea Lamprey Larvicide

USGS Publications Warehouse

Boogaard, Michael A; Rivera, Jane E; Gaikowski, Mark P

2008-01-01

Avoidance of juvenile lake sturgeons < 100 mm in length in response to application of the Bayluscide 3.2% Granular Sea Lamprey Larvicide was assessed. Clear plexiglas columns (107 cm in height, 30.5 cm in diameter) to evaluate the potential for the normally bottom-dwelling fishes to move vertically in the water column to avoid niclosamide dissolving from the Bayluscide granules. Vertical migration of lake sturgeons to > 15 cm off the bottom of the column was considered avoidance. Lake sturgeons began displaying avoidance behaviors within 4 to 8 min after the granules were applied and continued for up to 60 min. After 60 min, most or all of the sturgeons were near the surface in the treated columns. In contrast, little movement above the 15-cm mark was observed at any time in any of the control columns. The results of this study are similar to a previous study where juvenile lake sturgeons > 100 mm in length showed the ability to avoid granular Bayluscide. Taken together, we conclude that juvenile lake sturgeons of any size range can detect and avoid granular Bayluscide applications.
Culture-general and -specific associations of attachment avoidance and anxiety with perceived parental warmth and psychological control among Turk and Belgian adolescents.

PubMed

Güngör, Derya; Bornstein, Marc H

2010-10-01

Both the adolescent peer attachment and perceived parenting style literatures emphasize the role of the quality of the parent-child relationship in children's healthy adjustment beyond the family, but few studies have investigated links between adolescents' peer attachment and perceptions of parenting. We investigate relations of adolescents' perceptions of warmth and psychological control from parents with avoidance and anxiety in attachment to close friends in two contrasting cultures. Altogether, 262 Turk and 263 Belgian youth between 14 and 18 years of age participated. Cross-culturally, attachment avoidance was negatively related to maternal warmth, and attachment anxiety positively related to maternal and paternal control and negatively to paternal warmth. Beyond these general relations, attachment avoidance was associated with paternal psychological control in Belgians but not in Turks. The study provides cross-cultural evidence for specific relations between peer attachment and perceived parenting and suggests a culture-specific pathway for the development of attachment avoidance.
Chemically Realistic Tetrahedral Lattice Models for Polymer Chains: Application to Polyethylene Oxide.

PubMed

Dietschreit, Johannes C B; Diestler, Dennis J; Knapp, Ernst W

2016-05-10

To speed up the generation of an ensemble of poly(ethylene oxide) (PEO) polymer chains in solution, a tetrahedral lattice model possessing the appropriate bond angles is used. The distance between noncovalently bonded atoms is maintained at realistic values by generating chains with an enhanced degree of self-avoidance by a very efficient Monte Carlo (MC) algorithm. Potential energy parameters characterizing this lattice model are adjusted so as to mimic realistic PEO polymer chains in water simulated by molecular dynamics (MD), which serves as a benchmark. The MD data show that PEO chains have a fractal dimension of about two, in contrast to self-avoiding walk lattice models, which exhibit the fractal dimension of 1.7. The potential energy accounts for a mild hydrophobic effect (HYEF) of PEO and for a proper setting of the distribution between trans and gauche conformers. The potential energy parameters are determined by matching the Flory radius, the radius of gyration, and the fraction of trans torsion angles in the chain. A gratifying result is the excellent agreement of the pair distribution function and the angular correlation for the lattice model with the benchmark distribution. The lattice model allows for the precise computation of the torsional entropy of the chain. The generation of polymer conformations of the adjusted lattice model is at least 2 orders of magnitude more efficient than MD simulations of the PEO chain in explicit water. This method of generating chain conformations on a tetrahedral lattice can also be applied to other types of polymers with appropriate adjustment of the potential energy function. The efficient MC algorithm for generating chain conformations on a tetrahedral lattice is available for download at https://github.com/Roulattice/Roulattice .
Evaluation of the effects of plant-derived essential oils on central nervous system function using discrete shuttle-type conditioned avoidance response in mice.

PubMed

Umezu, Toyoshi

2012-06-01

Although plant-derived essential oils (EOs) have been used to treat various mental disorders, their central nervous system (CNS) acting effects have not been clarified. The present study compared the effects of 20 kinds of EOs with the effects of already-known CNS acting drugs to examine whether the EOs exhibited CNS stimulant-like effects, CNS depressant-like effects, or neither. All agents were tested using a discrete shuttle-type conditioned avoidance task in mice. Essential oils of peppermint and chamomile exhibited CNS stimulant-like effects; that is, they increased the response rate (number of shuttlings/min) of the avoidance response. Linden also increased the response rate, however, the effect was not dose-dependent. In contrast, EOs of orange, grapefruit, and cypress exhibited CNS depressant-like effects; that is, they decreased the response rate of the avoidance response. Essential oils of eucalyptus and rose decreased the avoidance rate (number of avoidance responses/number of avoidance trials) without affecting the response rate, indicating that they may exhibit some CNS acting effects. Essential oils of 12 other plants, including juniper, patchouli, geranium, jasmine, clary sage, neroli, lavender, lemon, ylang-ylang, niaouli, vetivert and frankincense had no effect on the avoidance response in mice. Copyright © 2011 John Wiley & Sons, Ltd.
Contrasting effects of acute and chronic treatment with imipramine and fluoxetine on inhibitory avoidance and escape responses in mice exposed to the elevated T-maze.

PubMed

Gomes, Karina Santos; de Carvalho-Netto, Eduardo Ferreira; Monte, Kátia Cristina Da Silva; Acco, Bruno; Nogueira, Paulo José de Campos; Nunes-de-Souza, Ricardo Luiz

2009-03-30

The elevated T-maze (ETM) is an animal model of anxiety-like behavior that assesses two different defensive behavioral tasks in the same animal-acquisition of inhibitory avoidance and latency to escape from an open and elevated arm. In rats, cute and chronic treatments with anxiolytic-like drugs impair avoidance acquisition while only chronic administration of panicolytic-like drugs impairs open arm withdrawal. To date, only the acute effects of anxiolytic/anxiogenic or panicolytic/panicogenic drugs have been tested in the mouse ETM and the results have partially corroborated those found in the rat ETM. This study investigated the effects of acute (a single intraperitoneal injection 30 min before testing) and chronic (daily i.p. injections for 15 consecutive days) treatment with imipramine or fluoxetine, non-selective and selective serotonin reuptake inhibitors, respectively, on inhibitory avoidance and escape tasks in the mouse ETM. Neither acute nor chronic treatment with imipramine (0, 1, 5 or 10 mg/kg, i.p.) significantly changed the behavioral profile of mice in the two ETM tasks. Interestingly, while acute fluoxetine (0, 5, 10, 20 or 40 mg/kg, i.p.) facilitated inhibitory avoidance and impaired escape latency, chronic treatment (0, 5, 20 or 40 mg/kg, i.p.) with this selective serotonin reuptake inhibitor (SSRI) produced an opposite effect, i.e., it impaired inhibitory avoidance acquisition and facilitated open arm withdrawal. Importantly, acute or chronic treatment with imipramine (except at the highest dose that increased locomotion when given acutely) or fluoxetine failed to alter general locomotor activity in mice as assessed in an ETM in which all arms were enclosed by lateral walls (eETM). These results suggest that inhibitory avoidance acquisition is a useful task for the evaluation of acute and chronic effects of SSRI treatment on anxiety in mice. However, as open arm latency was actually increased and reduced by acute and chronic fluoxetine, respectively, this does not seem to be a useful measure of escape from a proximal threat in this species.
Long-Term Experimental Determination of Solubilities of Micro-Crystalline Nd(III) Hydroxide in High Ionic Strength Solutions: Applications to Nuclear Waste Management [A Pitzer Model for Am(III)/Nd(III) hydroxide solubility in NaCl-H 2O at 298.15 K to high ionic strengths: Experimental validation and model applications

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

Xiong, Yongliang; Kirkes, Leslie Dawn; Marrs, Cassandra

In this paper, the experimental results from long-term solubility experiments on micro crystalline neodymium hydroxide, Nd(OH) 3(micro cr), in high ionic strength solutions at 298.15 K under well-constrained conditions are presented. The starting material was synthesized according to a well-established method in the literature. In contrast with the previous studies in which hydrogen ion concentrations in experiments were adjusted with addition of either an acid or a base, the hydrogen ion concentrations in our experiments are controlled by the dissolution of Nd(OH) 3(micro cr), avoiding the possibility of phase change.

Long-Term Experimental Determination of Solubilities of Micro-Crystalline Nd(III) Hydroxide in High Ionic Strength Solutions: Applications to Nuclear Waste Management [A Pitzer Model for Am(III)/Nd(III) hydroxide solubility in NaCl-H 2O at 298.15 K to high ionic strengths: Experimental validation and model applications

DOE PAGES

Xiong, Yongliang; Kirkes, Leslie Dawn; Marrs, Cassandra

2017-12-01

In this paper, the experimental results from long-term solubility experiments on micro crystalline neodymium hydroxide, Nd(OH) 3(micro cr), in high ionic strength solutions at 298.15 K under well-constrained conditions are presented. The starting material was synthesized according to a well-established method in the literature. In contrast with the previous studies in which hydrogen ion concentrations in experiments were adjusted with addition of either an acid or a base, the hydrogen ion concentrations in our experiments are controlled by the dissolution of Nd(OH) 3(micro cr), avoiding the possibility of phase change.
Trajectories of change across outcomes in intensive treatment for adolescent panic disorder and agoraphobia.

PubMed

Gallo, Kaitlin P; Cooper-Vince, Christine E; Hardway, Christina L; Pincus, Donna B; Comer, Jonathan S

2014-01-01

Much remains to be learned about typical and individual growth trajectories across treatment for adolescent panic disorder with and without agoraphobia and about critical treatment points associated with key changes. The present study examined the rate and shape of change across an 8-day intensive cognitive behavioral therapy for adolescent panic disorder with and without agoraphobia (N = 56). Participants ranged in age from 12 to 17 (M = 15.14, SD = 1.70; 58.9% female, 78.6% Caucasian). Multilevel modeling evaluated within-treatment linear and nonlinear changes across three treatment outcomes: panic severity, fear, and avoidance. Overall panic severity showed linear change, decreasing throughout treatment. In contrast, fear and avoidance ratings both showed cubic change, peaking slightly at the first session of treatment, starting to decrease at the second session of treatment, and with large gains continuing then plateauing at the fourth session. Findings are considered with regard to the extent to which they may elucidate critical treatment components and sessions for adolescents with panic disorder with and without agoraphobia.
Attachment Insecurity and Infidelity in Marriage: Do Studies of Dating Relationships Really Inform Us about Marriage?

PubMed Central

Russell, V. Michelle; Baker, Levi R.; McNulty, James K.

2013-01-01

Attachment theory provides a useful framework for predicting marital infidelity. However, most research has examined the association between attachment and infidelity in unmarried individuals, and we are aware of no research that has examined the role of partner attachment in predicting infidelity. In contrast to research showing that attachment anxiety is unrelated to infidelity among dating couples, 2 longitudinal studies of 207 newlywed marriages demonstrated that own and partner attachment anxiety interacted to predict marital infidelity, such that spouses were more likely to perpetrate infidelity when either they or their partner was high (vs. low) in attachment anxiety. Further, and also in contrast to research on dating couples, own attachment avoidance was unrelated to infidelity whereas partner attachment avoidance was negatively associated with infidelity indicating that spouses were less likely to perpetrate infidelity when their partner was high (vs. low) in attachment avoidance. These effects emerged controlling for marital satisfaction, sexual frequency, and personality, did not differ across husbands and wives, and did not differ across the two studies, with the exception that the negative association between partner attachment avoidance and own infidelity only emerged in one of the two studies. These findings offer a more complete understanding of the implications of attachment insecurity for marital infidelity and suggest that studies of unmarried individuals may not provide complete insights into the implications of various psychological traits and processes for marriage. PMID:23544923
Attachment insecurity and infidelity in marriage: do studies of dating relationships really inform us about marriage?

PubMed

Russell, V Michelle; Baker, Levi R; McNulty, James K

2013-04-01

Attachment theory provides a useful framework for predicting marital infidelity. However, most research has examined the association between attachment and infidelity in unmarried individuals, and we are aware of no research that has examined the role of partner attachment in predicting infidelity. In contrast to research showing that attachment anxiety is unrelated to infidelity among dating couples, 2 longitudinal studies of 207 newlywed marriages demonstrated that own and partner attachment anxiety interacted to predict marital infidelity, such that spouses were more likely to perpetrate infidelity when either they or their partner was high (vs. low) in attachment anxiety. Further, and also in contrast to research on dating couples, own attachment avoidance was unrelated to infidelity, whereas partner attachment avoidance was negatively associated with infidelity, indicating that spouses were less likely to perpetrate infidelity when their partner was high (vs. low) in attachment avoidance. These effects emerged controlling for marital satisfaction, sexual frequency, and personality; did not differ across husbands and wives; and did not differ across the two studies, with the exception that the negative association between partner attachment avoidance and own infidelity only emerged in 1 of the 2 studies. These findings offer a more complete understanding of the implications of attachment insecurity for marital infidelity and suggest that studies of unmarried individuals may not provide complete insights into the implications of various psychological traits and processes for marriage. (PsycINFO Database Record (c) 2013 APA, all rights reserved).
Cheetahs and wild dogs show contrasting patterns of suppression by lions.

PubMed

Swanson, Alexandra; Caro, Tim; Davies-Mostert, Harriet; Mills, Michael G L; Macdonald, David W; Borner, Markus; Masenga, Emmanuel; Packer, Craig

2014-11-01

Top predators can dramatically suppress populations of smaller predators, with cascading effects throughout communities, and this pressure is often unquestioningly accepted as a constraint on mesopredator populations. In this study, we reassess whether African lions suppress populations of cheetahs and African wild dogs and examine possible mechanisms for coexistence between these species. Using long-term records from Serengeti National Park, we tested 30 years of population data for evidence of mesopredator suppression, and we examined six years of concurrent radio-telemetry data for evidence of large-scale spatial displacement. The Serengeti lion population nearly tripled between 1966 and 1998; during this time, wild dogs declined but cheetah numbers remained largely unchanged. Prior to their local extinction, wild dogs primarily occupied low lion density areas and apparently abandoned the long-term study area as the lion population 'saturated' the region. In contrast, cheetahs mostly utilized areas of high lion density, and the stability of the cheetah population indicates that neither high levels of lion-inflicted mortality nor behavioural avoidance inflict sufficient demographic consequences to translate into population-level effects. Population data from fenced reserves in southern Africa revealed a similar contrast between wild dogs and cheetahs in their ability to coexist with lions. These findings demonstrate differential responses of subordinate species within the same guild and challenge a widespread perception that lions undermine cheetah conservation efforts. Paired with several recent studies that document fine-scale lion-avoidance by cheetahs, this study further highlights fine-scale spatial avoidance as a possible mechanism for mitigating mesopredator suppression. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.
Trichotomous goals of elementary school students learning English as a foreign language: a structural equation model.

PubMed

He, Tung-Hsien; Chang, Shan-Mao; Chen, Shu-Hui Eileen; Gou, Wen Johnny

2012-02-01

This study applied structural equation modeling (SEM) techniques to define the relations among trichotomous goals (mastery goals, performance-approach goals, and performance-avoidance goals), self-efficacy, use of metacognitive self-regulation strategies, positive belief in seeking help, and help-avoidance behavior. Elementary school students (N = 105), who were learning English as a foreign language, were surveyed using five self-report scales. The structural equation model showed that self-efficacy led to the adoption of mastery goals but discouraged the adoption of performance-approach goals and performance-avoidance goals. Furthermore, mastery goals increased the use of metacognitive self-regulation strategies, whereas performance-approach goals and performance-avoidance goals reduced their use. Mastery goals encouraged positive belief in help-seeking, but performance-avoidance goals decreased such belief. Finally, performance-avoidance goals directly led to help-avoidance behavior, whereas positive belief assumed a critical role in reducing help-avoidance. The established structural equation model illuminated the potential causal relations among these variables for the young learners in this study.
Perspective traffic display format and airline pilot traffic avoidance

NASA Technical Reports Server (NTRS)

Ellis, Stephen R.; Mcgreevy, Michael W.; Hitchcock, Robert J.

1987-01-01

Part-task experiments have examined perspective projections of cockpit displays of traffic information as a means of presenting aircraft separation information to airline pilots. Ten airline pilots served as subjects in an experiment comparing the perspective projection with plan-view projections of the same air traffic situations. The pilots' task was to monitor the traffic display in order to decide if an avoidance maneuver was needed. Pilots took more time to select avoidance maneuvers with a conventional plan-view display than with an experimental perspective display. In contrast to previous results, if the pilots selected a maneuver with the perspective display, they were more likely to choose one with a vertical component. Tabulation of the outcomes of their initial avoidance decisions with both perspective and plan-view displays showed that they were more likely to achieve required separation with maneuvers chosen with the aid of perspective displays.
Coordination and trade-offs among hydraulic safety, efficiency and drought avoidance traits in Amazonian rainforest canopy tree species.

PubMed

Santiago, Louis S; De Guzman, Mark E; Baraloto, Christopher; Vogenberg, Jacob E; Brodie, Max; Hérault, Bruno; Fortunel, Claire; Bonal, Damien

2018-05-01

Predicting responses of tropical forests to climate change-type drought is challenging because of high species diversity. Detailed characterization of tropical tree hydraulic physiology is necessary to evaluate community drought vulnerability and improve model parameterization. Here, we measured xylem hydraulic conductivity (hydraulic efficiency), xylem vulnerability curves (hydraulic safety), sapwood pressure-volume curves (drought avoidance) and wood density on emergent branches of 14 common species of Eastern Amazonian canopy trees in Paracou, French Guiana across species with the densest and lightest wood in the plot. Our objectives were to evaluate relationships among hydraulic traits to identify strategies and test the ability of easy-to-measure traits as proxies for hard-to-measure hydraulic traits. Xylem efficiency was related to capacitance, sapwood water content and turgor loss point, and other drought avoidance traits, but not to xylem safety (P 50 ). Wood density was correlated (r = -0.57 to -0.97) with sapwood pressure-volume traits, forming an axis of hydraulic strategy variation. In contrast to drier sites where hydraulic safety plays a greater role, tropical trees in this humid tropical site varied along an axis with low wood density, high xylem efficiency and high capacitance at one end of the spectrum, and high wood density and low turgor loss point at the other. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.
Modeling nasopharyngeal carcinoma in three dimensions

PubMed Central

Siva Sankar, Prabu; Che Mat, Mohd Firdaus; Muniandy, Kalaivani; Xiang, Benedict Lian Shi; Ling, Phang Su; Hoe, Susan Ling Ling; Khoo, Alan Soo-Beng; Mohana-Kumaran, Nethia

2017-01-01

Nasopharyngeal carcinoma (NPC) is a type of cancer endemic in Asia, including Malaysia, Southern China, Hong Kong and Taiwan. Treatment resistance, particularly in recurring cases, remains a challenge. Thus, studies to develop novel therapeutic agents are important. Potential therapeutic compounds may be effectively examined using two-dimensional (2D) cell culture models, three-dimensional (3D) spheroid models or in vivo animal models. The majority of drug assessments for cancers, including for NPC, are currently performed with 2D cell culture models. This model offers economical and high-throughput screening advantages. However, 2D cell culture models cannot recapitulate the architecture and the microenvironment of a tumor. In vivo models may recapitulate certain architectural and microenvironmental conditions of a tumor, however, these are not feasible for the screening of large numbers of compounds. By contrast, 3D spheroid models may be able to recapitulate a physiological microenvironment not observed in 2D cell culture models, in addition to avoiding the impediments of in vivo animal models. Thus, the 3D spheroid model offers a more representative model for the study of NPC growth, invasion and drug response, which may be cost-effective without forgoing quality. PMID:28454359
Morphological rational multi-scale algorithm for color contrast enhancement

NASA Astrophysics Data System (ADS)

Peregrina-Barreto, Hayde; Terol-Villalobos, Iván R.

2010-01-01

Contrast enhancement main goal consists on improving the image visual appearance but also it is used for providing a transformed image in order to segment it. In mathematical morphology several works have been derived from the framework theory for contrast enhancement proposed by Meyer and Serra. However, when working with images with a wide range of scene brightness, as for example when strong highlights and deep shadows appear in the same image, the proposed morphological methods do not allow the enhancement. In this work, a rational multi-scale method, which uses a class of morphological connected filters called filters by reconstruction, is proposed. Granulometry is used by finding the more accurate scales for filters and with the aim of avoiding the use of other little significant scales. The CIE-u'v'Y' space was used to introduce our results since it takes into account the Weber's Law and by avoiding the creation of new colors it permits to modify the luminance values without affecting the hue. The luminance component ('Y) is enhanced separately using the proposed method, next it is used for enhancing the chromatic components (u', v') by means of the center of gravity law of color mixing.
Test-area surface tension calculation of the graphene-methane interface: Fluctuations and commensurability

NASA Astrophysics Data System (ADS)

d'Oliveira, H. D.; Davoy, X.; Arche, E.; Malfreyt, P.; Ghoufi, A.

2017-06-01

The surface tension (γ) of methane on a graphene monolayer is calculated by using the test-area approach. By using a united atom model to describe methane molecules, strong fluctuations of surface tension as a function of the surface area of the graphene are evidenced. In contrast with the liquid-vapor interfaces, the use of a larger cutoff does not fully erase the fluctuations in the surface tension. Counterintuitively, the description of methane and graphene from the Optimized Potentials for Liquid Simulations all-atom model and a flexible model, respectively, led to a lessening in the surface tension fluctuations. This result suggests that the origin of fluctuations in γ is due to a model-effect rather than size-effects. We show that the molecular origin of these fluctuations is the result of a commensurable organization between both graphene and methane. This commensurable structure can be avoided by describing methane and graphene from a flexible force field. Although differences in γ with respect to the model have been often reported, it is the first time that the model drastically affects the physics of a system.
An avoidance behavior model for migrating whale populations

NASA Astrophysics Data System (ADS)

Buck, John R.; Tyack, Peter L.

2003-04-01

A new model is presented for the avoidance behavior of migrating marine mammals in the presence of a noise stimulus. This model assumes that each whale will adjust its movement pattern near a sound source to maintain its exposure below its own individually specific maximum received sound-pressure level, called its avoidance threshold. The probability distribution function (PDF) of this avoidance threshold across individuals characterizes the migrating population. The avoidance threshold PDF may be estimated by comparing the distribution of migrating whales during playback and control conditions at their closest point of approach to the sound source. The proposed model was applied to the January 1998 experiment which placed a single acoustic source from the U.S. Navy SURTASS-LFA system in the migration corridor of grey whales off the California coast. This analysis found that the median avoidance threshold for this migrating grey whale population was 135 dB, with 90% confidence that the median threshold was within +/-3 dB of this value. This value is less than the 141 dB value for 50% avoidance obtained when the 1984 ``Probability of Avoidance'' model of Malme et al.'s was applied to the same data. [Work supported by ONR.
Understanding bicycling in cities using system dynamics modelling.

PubMed

Macmillan, Alexandra; Woodcock, James

2017-12-01

Increasing urban bicycling has established net benefits for human and environmental health. Questions remain about which policies are needed and in what order, to achieve an increase in cycling while avoiding negative consequences. Novel ways of considering cycling policy are needed, bringing together expertise across policy, community and research to develop a shared understanding of the dynamically complex cycling system. In this paper we use a collaborative learning process to develop a dynamic causal model of urban cycling to develop consensus about the nature and order of policies needed in different cycling contexts to optimise outcomes. We used participatory system dynamics modelling to develop causal loop diagrams (CLDs) of cycling in three contrasting contexts: Auckland, London and Nijmegen. We combined qualitative interviews and workshops to develop the CLDs. We used the three CLDs to compare and contrast influences on cycling at different points on a "cycling trajectory" and drew out policy insights. The three CLDs consisted of feedback loops dynamically influencing cycling, with significant overlap between the three diagrams. Common reinforcing patterns emerged: growing numbers of people cycling lifts political will to improve the environment; cycling safety in numbers drives further growth; and more cycling can lead to normalisation across the population. By contrast, limits to growth varied as cycling increases. In Auckland and London, real and perceived danger was considered the main limit, with added barriers to normalisation in London. Cycling congestion and "market saturation" were important in the Netherlands. A generalisable, dynamic causal theory for urban cycling enables a more ordered set of policy recommendations for different cities on a cycling trajectory. Participation meant the collective knowledge of cycling stakeholders was represented and triangulated with research evidence. Extending this research to further cities, especially in low-middle income countries, would enhance generalizability of the CLDs.
Laser direct marking applied to rasterizing miniature Data Matrix Code on aluminum alloy

NASA Astrophysics Data System (ADS)

Li, Xia-Shuang; He, Wei-Ping; Lei, Lei; Wang, Jian; Guo, Gai-Fang; Zhang, Teng-Yun; Yue, Ting

2016-03-01

Precise miniaturization of 2D Data Matrix (DM) Codes on Aluminum alloy formed by raster mode laser direct part marking is demonstrated. The characteristic edge over-burn effects, which render vector mode laser direct part marking inadequate for producing precise and readable miniature codes, are minimized with raster mode laser marking. To obtain the control mechanism for the contrast and print growth of miniature DM code by raster laser marking process, the temperature field model of long pulse laser interaction with material is established. From the experimental results, laser average power and Q frequency have an important effect on the contrast and print growth of miniature DM code, and the threshold of laser average power and Q frequency for an identifiable miniature DM code are respectively 3.6 W and 110 kHz, which matches the model well within normal operating conditions. In addition, the empirical model of correlation occurring between laser marking parameters and module size is also obtained, and the optimal processing parameter values for an identifiable miniature DM code of different but certain data size are given. It is also found that an increase of the repeat scanning number effectively improves the surface finish of bore, the appearance consistency of modules, which has benefit to reading. The reading quality of miniature DM code is greatly improved using ultrasonic cleaning in water by avoiding the interference of color speckles surrounding modules.
Blunted hypothalamo-pituitary adrenal axis response to predator odor predicts high stress reactivity.

PubMed

Whitaker, Annie M; Gilpin, Nicholas W

2015-08-01

Individuals with trauma- and stress-related disorders exhibit increases in avoidance of trauma-related stimuli, heightened anxiety and altered neuroendocrine stress responses. Our laboratory uses a rodent model of stress that mimics the avoidance symptom cluster associated with stress-related disorders. Animals are classified as 'Avoiders' or 'Non-Avoiders' post-stress based on avoidance of predator-odor paired context. Utilizing this model, we are able to examine subpopulation differences in stress reactivity. Here, we used this predator odor model of stress to examine differences in anxiety-like behavior and hypothalamo-pituitary adrenal (HPA) axis function in animals that avoid a predator-paired context relative to those that do not. Rats were exposed to predator odor stress paired with a context and tested for avoidance (24h and 11days), anxiety-like behavior (48h and 5days) and HPA activation following stress. Control animals were exposed to room air. Predator odor stress produced avoidance in approximately 65% of the animals at 24h that persisted 11days post-stress. Both Avoiders and Non-Avoiders exhibited a heightened anxiety-like behavior at 48h and 5days post-stress when compared to unstressed Controls. Non-Avoiders exhibited significant increases in circulating adrenocorticotropin hormone (ACTH) and corticosterone (CORT) concentrations immediately following predator odor stress compared to Controls and this response was significantly attenuated in Avoiders. There was an inverse correlation between circulating ACTH/CORT concentrations and avoidance, indicating that lower levels of ACTH/CORT predicted higher levels of avoidance. These results suggest that stress effects on HPA stress axis activation predict long-term avoidance of stress-paired stimuli, and build on previous data showing the utility of this model for exploring the neurobiological mechanisms of trauma- and stress-related disorders. Copyright © 2015. Published by Elsevier Inc.
Economic Costs Avoided by Diagnosing Melanoma Six Months Earlier Justify >100 Benign Biopsies.

PubMed

Aires, Daniel J; Wick, Jo; Shaath, Tarek S; Rajpara, Anand N; Patel, Vikas; Badawi, Ahmed H; Li, Cicy; Fraga, Garth R; Doolittle, Gary; Liu, Deede Y

2016-05-01

New melanoma drugs bring enormous benefits but do so at significant costs. Because melanoma grows deeper and deadlier over time, deeper lesions are costlier due to increased sentinel lymph node biopsy, chemotherapy, and disease-associated income loss. Prior studies have justified pigmented lesion biopsies on a "value per life" basis; by contrast we sought to assess how many biopsies are justified per melanoma found on a purely economic basis. We modeled how melanomas in the United States would behave if diagnosis were delayed by 6 months, eg, not biopsied, only observed until the next surveillance visit. Economic loss from delayed biopsy is the obverse of economic benefit of performing biopsy earlier. Growth rates were based on Liu et al. The results of this study can be applied to all patients presenting to dermatologists with pigmented skin lesions suspicious for melanoma. In-situ melanomas were excluded because no studies to date have modeled growth rates analogous to those for invasive melanoma. We assume conservatively that all melanomas not biopsied initially will be biopsied and treated 6 months later. Major modeled costs are (1) increased sentinel lymph node biopsy, (2) increased chemotherapy for metastatic lesions using increased 5-yr death as metastasis marker, and (3) income loss per melanoma death at $413,370 as previously published. Costs avoided by diagnosing melanoma earlier justify 170 biopsies per melanoma found. Efforts to penalize "unnecessary" biopsies may be economically counterproductive.

J Drugs Dermatol. 2016;15(5):527-532.
The prepared emotional reflex: intentional preparation of automatic approach and avoidance tendencies as a means to regulate emotional responding.

PubMed

Eder, Andreas B; Rothermund, Klaus; Proctor, Robert W

2010-08-01

Advance preparation of action courses toward emotional stimuli is an effective means to regulate impulsive emotional behavior. Our experiment shows that performing intentional acts of approach and avoidance in an evaluation task influences the unintended activation of approach and avoidance tendencies in another task in which stimulus valence is irrelevant. For the evaluation-relevant blocks, participants received either congruent (positive-approach, negative-avoidance) or incongruent (positive-avoidance, negative-approach) mapping instructions. In the evaluation-irrelevant blocks, approach- and avoidance-related lever movements were selected in response to a stimulus feature other than valence (affective Simon task). Response mapping in the evaluation task influenced performance in the evaluation-irrelevant task: An enhanced affective Simon effect was observed with congruent mapping instructions; in contrast, the effect was reversed when the evaluation task required incongruent responses. Thus, action instructions toward affective stimuli received in one task determined affective response tendencies in another task where these instructions were not in effect. These findings suggest that intentionally prepared short-term links between affective valence and motor responses elicit associated responses without a deliberate act of will, operating like a "prepared reflex." Copyright 2010 APA
Feeling loved and integrated or lonely and rejected in everyday life: The role of age and social motivation.

PubMed

Nikitin, Jana; Freund, Alexandra M

2018-06-01

Social approach and social avoidance goals (i.e., approach of positive and avoidance of negative outcomes in social situations) are important predictors of the feeling of being socially integrated or isolated. However, little is known about the development of these goals across adulthood. In a large diary study with N = 744 young (18-39 years), middle-aged (40-59 years), and older adults (60-83 years), we tested the hypothesis that the adaptiveness of social goals changes across adulthood: Social approach goals were hypothesized to be adaptive during young adulthood when adult social relationships are to be established. In contrast, social avoidance goals were hypothesized to become more adaptive with age as people are increasingly motivated to avoid interpersonal tension. Our findings support these hypotheses: Social approach goals were positively and social avoidance goals negatively associated with younger but not with middle-aged and older adults' daily social well-being. These results were robust across different situations (positive, negative) and different types of relationships (close, peripheral). The study highlights the changing role of social approach and avoidance goals for daily social well-being across adulthood. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
Public speaking avoidance as a treatment moderator for social anxiety disorder.

PubMed

Mesri, Bita; Niles, Andrea N; Pittig, Andre; LeBeau, Richard T; Haik, Ethan; Craske, Michelle G

2017-06-01

Cognitive behavioral therapy (CBT) and acceptance and commitment therapy (ACT) have both garnered empirical support for the effective treatment of social anxiety disorder. However, not every patient benefits equally from either treatment. Identifying moderators of treatment outcome can help to better understand which treatment is best suited for a particular patient. Forty-nine individuals who met criteria for social anxiety disorder were assessed as part of a randomized controlled trial comparing 12 weeks of CBT and ACT. Pre-treatment avoidance of social situations (measured via a public speaking task and clinician rating) was investigated as a moderator of post-treatment, 6-month follow-up, and 12-month follow-up social anxiety symptoms, stress reactivity, and quality of life. Public speaking avoidance was found to be a robust moderator of outcome measures, with more avoidant individuals generally benefitting more from CBT than ACT by 12-month follow-up. In contrast, clinician-rated social avoidance was not found to be a significant moderator of any outcome measure. Results were found only at 12-month follow-up. More comprehensive measures of avoidance would be useful for the field moving forward. Findings inform personalized medicine, suggesting that social avoidance measured behaviorally via a public speaking task may be a more robust factor in treatment prescription compared to clinician-rated social avoidance. Published by Elsevier Ltd.
Blunted Hypothalamo-pituitary Adrenal Axis Response to Predator Odor Predicts High Stress Reactivity

PubMed Central

Whitaker, Annie M.; Gilpin, Nicholas W.

2015-01-01

Individuals with trauma- and stress-related disorders exhibit increases in avoidance of trauma-related stimuli, heightened anxiety and altered neuroendocrine stress responses. Our laboratory uses a rodent model of stress that mimics the avoidance symptom cluster associated with stress-related disorders. Animals are classified as ‘Avoiders’ or Non-Avoiders' post-stress based on avoidance of predator-odor paired context. Utilizing this model, we are able to examine subpopulation differences in stress reactivity. Here, we used this predator odor model of stress to examine differences in anxiety-like behavior and hypothalamo-pituitary adrenal (HPA) axis function in animals that avoid a predator-paired context relative to those that do not. Rats were exposed to predator odor stress paired with a context and tested for avoidance (24 hours and 11 days), anxiety-like behavior (48 hours and 5 days) and HPA activation following stress. Control animals were exposed to room air. Predator odor stress produced avoidance in approximately 65% of the animals at 24 hours that persisted 11 days post-stress. Both Avoiders and Non-Avoiders exhibited heightened anxiety-like behavior at 48 hours and 5 days post-stress when compared to unstressed Controls. Non-Avoiders exhibited significant increases in circulating adrenocorticotropin hormone (ACTH) and corticosterone (CORT) concentrations immediately following predator odor stress compared to Controls and this response was significantly attenuated in Avoiders. There was an inverse correlation between circulating ACTH/CORT concentrations and avoidance, indicating that lower levels of ACTH/CORT predicted higher levels of avoidance. These results suggest that stress effects on HPA stress axis activation predict long-term avoidance of stress-paired stimuli, and builds on previous data showing the utility of this model for exploring the neurobiological mechanisms of trauma- and stress-related disorders. PMID:25824191

Metacognitive evaluation in the avoidance of demand.

PubMed

Dunn, Timothy L; Lutes, David J C; Risko, Evan F

2016-09-01

In the current set of experiments our goal was to test the hypothesis that individuals avoid courses of action based on a kind of metacognitive evaluation of demand in a Demand Selection Task (DST). Individuals in Experiment 1 completed a DST utilizing visual stimuli known to yield a dissociation between performance and perceived demand. Patterns of demand avoidance followed that of perceived demand. Experiment 2 provided a replication of the aforementioned results, in addition to demonstrating a second dissociation between a peripheral physiological measure of demand (i.e., blink rates) and demand avoidance. Experiment 3 directly tested the assumption that individuals make use of a general metacognitive evaluation of task demand during selections. A DST was utilized in a forced-choice paradigm that required individuals to either select the most effortful, time demanding, or least accurate of 2 choices. Patterns of selections were similar across all rating dimensions, lending credit to this notion. Findings are discussed within a metacognitive framework of demand avoidance and contrasted to current theories. (PsycINFO Database Record (c) 2016 APA, all rights reserved).
The Big Bang Singularity

NASA Astrophysics Data System (ADS)

Ling, Eric

The big bang theory is a model of the universe which makes the striking prediction that the universe began a finite amount of time in the past at the so called "Big Bang singularity." We explore the physical and mathematical justification of this surprising result. After laying down the framework of the universe as a spacetime manifold, we combine physical observations with global symmetrical assumptions to deduce the FRW cosmological models which predict a big bang singularity. Next we prove a couple theorems due to Stephen Hawking which show that the big bang singularity exists even if one removes the global symmetrical assumptions. Lastly, we investigate the conditions one needs to impose on a spacetime if one wishes to avoid a singularity. The ideas and concepts used here to study spacetimes are similar to those used to study Riemannian manifolds, therefore we compare and contrast the two geometries throughout.
Insecurity, stress, and symptoms of psychopathology: contrasting results from self-reports versus interviews of adult attachment.

PubMed

Fortuna, Keren; Roisman, Glenn I

2008-03-01

This report was designed to clarify links among self-reports of psychiatric symptomatology, stress, and adult attachment insecurity, as operationalized using measures drawn from both the developmental and social psychological literatures. Based on a sample of 160 college students, this study demonstrated that insecurity reflected in the Adult Attachment Interview (AAI) was associated with self-reports of psychiatric symptomatology principally for individuals experiencing high levels of life stress (consistent with a diathesis-stress model) whereas self-reports of attachment-related avoidance and anxiety correlated robustly with psychopathology under conditions of both relatively high and low life stress (consistent with a risk model). Results provide further evidence that social psychological and developmental approaches to the assessment of adult attachment-related variation are associated with domains of adaptation central to Bowlby's account of human development in empirically distinct ways.
How emotion shapes behavior: feedback, anticipation, and reflection, rather than direct causation.

PubMed

Baumeister, Roy F; Vohs, Kathleen D; DeWall, C Nathan; Zhang, Liqing

2007-05-01

Fear causes fleeing and thereby saves lives: this exemplifies a popular and common sense but increasingly untenable view that the direct causation of behavior is the primary function of emotion. Instead, the authors develop a theory of emotion as a feedback system whose influence on behavior is typically indirect. By providing feedback and stimulating retrospective appraisal of actions, conscious emotional states can promote learning and alter guidelines for future behavior. Behavior may also be chosen to pursue (or avoid) anticipated emotional outcomes. Rapid, automatic affective responses, in contrast to the full-blown conscious emotions, may inform cognition and behavioral choice and thereby help guide current behavior. The automatic affective responses may also remind the person of past emotional outcomes and provide useful guides as to what emotional outcomes may be anticipated in the present. To justify replacing the direct causation model with the feedback model, the authors review a large body of empirical findings.
An attachment-based model of complicated grief including the role of avoidance

PubMed Central

Monk, Timothy; Houck, Patricia; Melhem, Nadine; Frank, Ellen; Reynolds, Charles; Sillowash, Russell

2009-01-01

Introduction Complicated grief is a prolonged grief disorder with elements of a stress response syndrome. We have previously proposed a biobehavioral model showing the pathway to complicated grief. Avoidance is a component that can be difficult to assess and pivotal to treatment. Therefore we developed an avoidance questionnaire to characterize avoidance among patients with CG. Methods We further explain our complicated grief model and provide results of a study of 128 participants in a treatment study of CG who completed a 15-item Grief-related Avoidance Questionnaire (GRAQ). Results of Avoidance Assessment Mean (SD) GRAQ score was 25. 0 ± 12.5 with a range of 0–60. Cronbach's alpha was 0.87 and test re-test correlation was 0.88. Correlation analyses showed good convergent and discriminant validity. Avoidance of reminders of the loss contributed to functional impairment after controlling for other symptoms of complicated grief. Discussion In this paper we extend our previously described attachment-based biobehavioral model of CG. We envision CG as a stress response syndrome that results from failure to integrate information about death of an attachment figure into an effectively functioning secure base schema and/or to effectively re-engage the exploratory system in a world without the deceased. Avoidance is a key element of the model. PMID:17629727
Do we need gadolinium-based contrast medium for brain magnetic resonance imaging in children?

PubMed

Dünger, Dennis; Krause, Matthias; Gräfe, Daniel; Merkenschlager, Andreas; Roth, Christian; Sorge, Ina

2018-06-01

Brain imaging is the most common examination in pediatric magnetic resonance imaging (MRI), often combined with the use of a gadolinium-based contrast medium. The application of gadolinium-based contrast medium poses some risk. There is limited evidence of the benefits of contrast medium in pediatric brain imaging. To assess the diagnostic gain of contrast-enhanced sequences in brain MRI when the unenhanced sequences are normal. We retrospectively assessed 6,683 brain MR examinations using contrast medium in children younger than 16 years in the pediatric radiology department of the University Hospital Leipzig to determine whether contrast-enhanced sequences delivered additional, clinically relevant information to pre-contrast sequences. All examinations were executed using a 1.5-T or a 3-T system. In 8 of 3,003 (95% confidence interval 0.12-0.52%) unenhanced normal brain examinations, a relevant additional finding was detected when contrast medium was administered. Contrast enhancement led to a change in diagnosis in only one of these cases. Children with a normal pre-contrast brain MRI rarely benefit from contrast medium application. Comparing these results to the risks and disadvantages of a routine gadolinium application, there is substantiated numerical evidence for avoiding routine administration of gadolinium in a pre-contrast normal MRI examination.
Improved pattern scaling approaches for the use in climate impact studies

NASA Astrophysics Data System (ADS)

Herger, Nadja; Sanderson, Benjamin M.; Knutti, Reto

2015-05-01

Pattern scaling is a simple way to produce climate projections beyond the scenarios run with expensive global climate models (GCMs). The simplest technique has known limitations and assumes that a spatial climate anomaly pattern obtained from a GCM can be scaled by the global mean temperature (GMT) anomaly. We propose alternatives and assess their skills and limitations. One approach which avoids scaling is to consider a period in a different scenario with the same GMT change. It is attractive as it provides patterns of any temporal resolution that are consistent across variables, and it does not distort variability. Second, we extend the traditional approach with a land-sea contrast term, which provides the largest improvements over the traditional technique. When interpolating between known bounding scenarios, the proposed methods significantly improve the accuracy of the pattern scaled scenario with little computational cost. The remaining errors are much smaller than the Coupled Model Intercomparison Project Phase 5 model spread.
Identifying the causes of road crashes in Europe

PubMed Central

Thomas, Pete; Morris, Andrew; Talbot, Rachel; Fagerlind, Helen

2013-01-01

This research applies a recently developed model of accident causation, developed to investigate industrial accidents, to a specially gathered sample of 997 crashes investigated in-depth in 6 countries. Based on the work of Hollnagel the model considers a collision to be a consequence of a breakdown in the interaction between road users, vehicles and the organisation of the traffic environment. 54% of road users experienced interpretation errors while 44% made observation errors and 37% planning errors. In contrast to other studies only 11% of drivers were identified as distracted and 8% inattentive. There was remarkably little variation in these errors between the main road user types. The application of the model to future in-depth crash studies offers the opportunity to identify new measures to improve safety and to mitigate the social impact of collisions. Examples given include the potential value of co-driver advisory technologies to reduce observation errors and predictive technologies to avoid conflicting interactions between road users. PMID:24406942
Coyotes, deer, and wildflowers: diverse evidence points to a trophic cascade

NASA Astrophysics Data System (ADS)

Waser, Nickolas M.; Price, Mary V.; Blumstein, Daniel T.; Arózqueta, S. Reneé; Escobar, Betsabé D. Castro; Pickens, Richard; Pistoia, Alessandra

2014-05-01

Spatial gradients in human activity, coyote activity, deer activity, and deer herbivory provide an unusual type of evidence for a trophic cascade. Activity of coyotes, which eat young mule deer (fawns), decreased with proximity to a remote biological field station, indicating that these predators avoided an area of high human activity. In contrast, activity of adult female deer (does) and intensity of herbivory on palatable plant species both increased with proximity to the station and were positively correlated with each other. The gradient in deer activity was not explained by availabilities of preferred habitats or plant species because these did not vary with distance from the station. Does spent less time feeding when they encountered coyote urine next to a feed block, indicating that increased vigilance may contribute, along with avoidance of areas with coyotes, to lower herbivory away from the station. Judging from two palatable wildflower species whose seed crop and seedling recruitment were greatly reduced near the field station, the coyote-deer-wildflower trophic cascade has the potential to influence plant community composition. Our study illustrates the value of a case-history approach, in which different forms of ecological data about a single system are used to develop conceptual models of complex ecological phenomena. Such an iterative model-building process is a common, but underappreciated, way of understanding how ecological systems work.
The Impact of Geoengineering Aerosols on Stratospheric Temperature and Ozone

NASA Technical Reports Server (NTRS)

Heckendorn, P.; Weisenstein, D.; Fueglistaler, S.; Luo, B. P.; Rozanov, E.; Schraner, M.; Peter, T.; Thomason, L. W.

2009-01-01

Anthropogenic greenhouse gas emissions are warming the global climate at an unprecedented rate. Significant emission reductions will be required soon to avoid a rapid temperature rise. As a potential interim measure to avoid extreme temperature increase, it has been suggested that Earth's albedo be increased by artificially enhancing stratospheric sulfate aerosols. We use a 3D chemistry climate model, fed by aerosol size distributions from a zonal mean aerosol model, to simulate continuous injection of 1-10 Mt/a into the lower tropical stratosphere. In contrast to the case for all previous work, the particles are predicted to grow to larger sizes than are observed after volcanic eruptions. The reason is the continuous supply of sulfuric acid and hence freshly formed small aerosol particles, which enhance the formation of large aerosol particles by coagulation and, to a lesser extent, by condensation. Owing to their large size, these particles have a reduced albedo. Furthermore, their sedimentation results in a non-linear relationship between stratospheric aerosol burden and annual injection, leading to a reduction of the targeted cooling. More importantly, the sedimenting particles heat the tropical cold point tropopause and, hence, the stratospheric entry mixing ratio of H2O increases. Therefore, geoengineering by means of sulfate aerosols is predicted to accelerate the hydroxyl catalyzed ozone destruction cycles and cause a significant depletion of the ozone layer even though future halogen concentrations will be significantly reduced.
The Impact of Geoengineering Aerosols on Stratospheric Temperature and Ozone

NASA Technical Reports Server (NTRS)

Heckendorn, P.; Weisenstein, D.; Fueglistaler, S.; Luo, B. P.; Rozanov, E.; Schraner, M.; Thomason, L. W.; Peter, T.

2011-01-01

Anthropogenic greenhouse gas emissions are warming the global climate at an unprecedented rate. Significant emission reductions will be required soon to avoid a rapid temperature rise. As a potential interim measure to avoid extreme temperature increase, it has been suggested that Earth's albedo be increased by artificially enhancing stratospheric sulfate aerosols. We use a 3D chemistry climate model, fed by aerosol size distributions from a zonal mean aerosol model. to simulate continuous injection of 1-10 Mt/a into the lower tropical stratosphere. In contrast to the case for all previous work, the particles are predicted to grow to larger sizes than are observed after volcanic eruptions. The reason is the continuous supply of sulfuric acid and hence freshly formed small aerosol particles, which enhance the formation of large aerosol particles by coagulation and, to a lesser extent, by condensation. Owing to their large size, these particles have a reduced albedo. Furthermore, their sedimentation results in a non-linear relationship between stratospheric aerosol burden and annual injection, leading to a reduction of the targeted cooling. More importantly, the sedimenting particles heat the tropical cold point tropopause and, hence, the stratospheric entry mixing ratio of H2O increases. Therefore, geoengineering by means of sulfate aerosols is predicted to accelerate the hydroxyl catalyzed ozone destruction cycles and cause a significant depletion of the ozone layer even though future halogen concentrations will he significantly reduced.
Differential Effects of TRPA and TRPV Channels on Behaviors of Caenorhabditis elegans

PubMed Central

Thies, Jennifer; Neutzler, Vanessa; O’Leary, Fidelma; Liu, He

2016-01-01

TRPA and TRPV ion channels are members of the transient receptor potential (TRP) cation channel superfamily, which mediates various sensory transductions. In Caenorhabditis elegans, the TRPV channels are known to affect chemosensation, while the TRPA-1 channel is associated with thermosensation and mechanosensation. We examined thermosensation, chemosensation, and osmosensation in strains lacking TRPA-1 or TRPV channels. We found that TRPV channel knockout worms exhibited similar behavioral deficits associated with thermotaxis as the TRPA-1 channel knockout, suggesting a dual role for TRPV channels. In contrast, chemosensation responses, assessed by both avoidance reversal behavior and NaCl osmosensation, were dependent on TRPV channels but seemed independent of TRPA-1 channel. Our findings suggest that, in addition to TRPA-1 channel, TRPV channels are necessary for thermotaxis and may activate, or modulate, the function of TRPA-1 channels. In contrast, TRPA-1 channels do not have a dual responsibility, as they have no functional role in odorant avoidance or osmosensation. PMID:27168724
Exploring the role of experiential avoidance from the perspective of attachment theory and the dual process model.

PubMed

Shear, M Katherine

2010-01-01

Avoidance can be adaptive and facilitate the healing process of acute grief or it can be maladaptive and hinder this same process. Maladaptive cognitive or behavioral avoidance comprises the central feature of the condition of complicated grief. This article explores the concept of experiential avoidance as it applies to bereavement, including when it is adaptive when it is problematic. Adaptive avoidance is framed using an attachment theory perspective and incorporates insights from the dual process model (DPM). An approach to clinical management of experiential avoidance in the syndrome of complicated grief is included.
Pseudo-hemothorax at computed tomography due to residual contrast media.

PubMed

Romero, Matías; Bächler, Pablo

2014-01-01

Pleural effusion is a clinical problem that has many causes, with hemothorax being one of them. Computed tomography readily characterizes pleural fluid with determination of the attenuation value, helping to distinguish hemothorax from other types of effusion. Herein, we report the case of a 67-year-old man with end-stage renal disease in which a high-density pleural effusion due to residual contrast media was misinterpreted as hemothorax. Radiologists should consider the possibility of contrast media retention when interpreting a high-density pleural effusion in patients with end-stage renal disease. Recognition of this entity is crucial to avoid misdiagnosis, which might lead to unnecessary testing or procedures. Copyright © 2014 Elsevier Inc. All rights reserved.
Cross-sectional study assessing the addition of contrast sensitivity to visual acuity when testing for fitness to drive

PubMed Central

Spreng, Lucie; Favrat, Bernard; Borruat, François-Xavier; Vaucher, Paul

2018-01-01

Objectives The aim of this study is to quantify the importance of loss of contrast sensitivity (CS) and its relationship to loss of visual acuity (VA), driving restrictions and daytime, on-road driving evaluations in drivers aged 70+. Design A predictive cross-sectional study. Setting Volunteer participants to a drivers’ refresher course for adults aged 70+ delivered by the Swiss Automobile Club in western Switzerland from 2011 to 2013. Participants 162 drivers, male and female, aged 70 years or older. Clinical predictors We used a vision screener to estimate VA and the The Mars Letter Contrast Sensitivity Test to test CS. Outcomes We asked drivers to report whether they found five driving restrictions useful for their condition; restrict driving to known roads, avoid driving on highways, avoid driving in the dark, avoid driving in dense traffic and avoid driving in fog. All participants also underwent a standardised on-road evaluation carried out by a driving instructor. Results Moderate to severe loss of CS for at least one eye was frequent (21.0% (95% CI 15.0% to 28.1%)) and often isolated from a loss of VA (11/162 cases had a VA ≥0.8 decimal and a CS of ≤1.5 log(CS); 6.8% (95% CI 3.4% to 11.8%)). Drivers were more likely (R2=0.116, P=0.004) to report a belief that self-imposed driving restrictions would be useful if they had reduced CS in at least one eye. Daytime evaluation of driving performance seems limited in its ability to correctly identify difficulties related to CS loss (VA: R2=0.004, P=0.454; CS: R2=0.006, P=0.332). Conclusion CS loss is common for older drivers. Screening CS and referring for cataract surgery even in the absence of VA loss could help maintain mobility. Reduced CS and moderate reduction of VA were both poor predictors of daytime on-road driving performances in this research study. PMID:29374663
Deep learning enables reduced gadolinium dose for contrast-enhanced brain MRI.

PubMed

Gong, Enhao; Pauly, John M; Wintermark, Max; Zaharchuk, Greg

2018-02-13

There are concerns over gadolinium deposition from gadolinium-based contrast agents (GBCA) administration. To reduce gadolinium dose in contrast-enhanced brain MRI using a deep learning method. Retrospective, crossover. Sixty patients receiving clinically indicated contrast-enhanced brain MRI. 3D T 1 -weighted inversion-recovery prepped fast-spoiled-gradient-echo (IR-FSPGR) imaging was acquired at both 1.5T and 3T. In 60 brain MRI exams, the IR-FSPGR sequence was obtained under three conditions: precontrast, postcontrast images with 10% low-dose (0.01mmol/kg) and 100% full-dose (0.1 mmol/kg) of gadobenate dimeglumine. We trained a deep learning model using the first 10 cases (with mixed indications) to approximate full-dose images from the precontrast and low-dose images. Synthesized full-dose images were created using the trained model in two test sets: 20 patients with mixed indications and 30 patients with glioma. For both test sets, low-dose, true full-dose, and the synthesized full-dose postcontrast image sets were compared quantitatively using peak-signal-to-noise-ratios (PSNR) and structural-similarity-index (SSIM). For the test set comprised of 20 patients with mixed indications, two neuroradiologists scored blindly and independently for the three postcontrast image sets, evaluating image quality, motion-artifact suppression, and contrast enhancement compared with precontrast images. Results were assessed using paired t-tests and noninferiority tests. The proposed deep learning method yielded significant (n = 50, P < 0.001) improvements over the low-dose images (>5 dB PSNR gains and >11.0% SSIM). Ratings on image quality (n = 20, P = 0.003) and contrast enhancement (n = 20, P < 0.001) were significantly increased. Compared to true full-dose images, the synthesized full-dose images have a slight but not significant reduction in image quality (n = 20, P = 0.083) and contrast enhancement (n = 20, P = 0.068). Slightly better (n = 20, P = 0.039) motion-artifact suppression was noted in the synthesized images. The noninferiority test rejects the inferiority of the synthesized to true full-dose images for image quality (95% CI: -14-9%), artifacts suppression (95% CI: -5-20%), and contrast enhancement (95% CI: -13-6%). With the proposed deep learning method, gadolinium dose can be reduced 10-fold while preserving contrast information and avoiding significant image quality degradation. 3 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018. © 2018 International Society for Magnetic Resonance in Medicine.
When avoiding unpleasant emotions might not be such a bad thing: verbal-autonomic response dissociation and midlife conjugal bereavement.

PubMed

Bonanno, G A; Keltner, D; Holen, A; Horowitz, M J

1995-11-01

It has been widely assumed that emotional avoidance during bereavement leads to either prolonged grief, delayed grief, or delayed somatic symptoms. To test this view, as well as a contrasting adaptive hypothesis, emotional avoidance was measured 6 months after a conjugal loss as negative verbal-autonomic response dissociation (low self-rated negative emotion coupled with heightened cardiovascular activity) and compared with grief measured at 6 and 14 months. The negative dissociation score evidenced reliability and validity but did not evidence the assumed link to severe grief. Rather, consistent with the adaptive hypothesis, negative dissociation at 6 months was associated with minimal grief symptoms across 14 months. Negative dissociation scores were also linked to initially high levels of somatic symptoms, which dropped to a low level by 14 months. Possible explanations for the initial cost and long-term adaptive quality of emotional avoidance during bereavement, as well as implications and limitations of the findings, are discussed.
PCA-based groupwise image registration for quantitative MRI.

PubMed

Huizinga, W; Poot, D H J; Guyader, J-M; Klaassen, R; Coolen, B F; van Kranenburg, M; van Geuns, R J M; Uitterdijk, A; Polfliet, M; Vandemeulebroucke, J; Leemans, A; Niessen, W J; Klein, S

2016-04-01

Quantitative magnetic resonance imaging (qMRI) is a technique for estimating quantitative tissue properties, such as the T1 and T2 relaxation times, apparent diffusion coefficient (ADC), and various perfusion measures. This estimation is achieved by acquiring multiple images with different acquisition parameters (or at multiple time points after injection of a contrast agent) and by fitting a qMRI signal model to the image intensities. Image registration is often necessary to compensate for misalignments due to subject motion and/or geometric distortions caused by the acquisition. However, large differences in image appearance make accurate image registration challenging. In this work, we propose a groupwise image registration method for compensating misalignment in qMRI. The groupwise formulation of the method eliminates the requirement of choosing a reference image, thus avoiding a registration bias. The method minimizes a cost function that is based on principal component analysis (PCA), exploiting the fact that intensity changes in qMRI can be described by a low-dimensional signal model, but not requiring knowledge on the specific acquisition model. The method was evaluated on 4D CT data of the lungs, and both real and synthetic images of five different qMRI applications: T1 mapping in a porcine heart, combined T1 and T2 mapping in carotid arteries, ADC mapping in the abdomen, diffusion tensor mapping in the brain, and dynamic contrast-enhanced mapping in the abdomen. Each application is based on a different acquisition model. The method is compared to a mutual information-based pairwise registration method and four other state-of-the-art groupwise registration methods. Registration accuracy is evaluated in terms of the precision of the estimated qMRI parameters, overlap of segmented structures, distance between corresponding landmarks, and smoothness of the deformation. In all qMRI applications the proposed method performed better than or equally well as competing methods, while avoiding the need to choose a reference image. It is also shown that the results of the conventional pairwise approach do depend on the choice of this reference image. We therefore conclude that our groupwise registration method with a similarity measure based on PCA is the preferred technique for compensating misalignments in qMRI. Copyright © 2015 Elsevier B.V. All rights reserved.
Losses as ecological guides: minor losses lead to maximization and not to avoidance.

PubMed

Yechiam, Eldad; Retzer, Matan; Telpaz, Ariel; Hochman, Guy

2015-06-01

Losses are commonly thought to result in a neuropsychological avoidance response. We suggest that losses also provide ecological guidance by increasing focus on the task at hand, and that this effect may override the avoidance response. This prediction was tested in a series of studies. In Study 1a we found that minor losses did not lead to an avoidance response. Instead, they guided participants to make advantageous choices (in terms of expected value) and to avoid disadvantageous choices. Moreover, losses were associated with less switching between options after the first block of exploration. In Study 1b we found that this effect was not simply a by-product of the increase in visual contrast with losses. In Study 1c we found that the effect of losses did not emerge when alternatives did not differ in their expected value but only in their risk level. In Study 2 we investigated the autonomic arousal dynamics associated with this behavioral pattern via pupillometric responses. The results showed increased pupil diameter following losses compared to gains. However, this increase was not associated with a tendency to avoid losses, but rather with a tendency to select more advantageously. These findings suggest that attention and reasoning processes induced by losses can out-weigh the influence of affective processes leading to avoidance. Copyright © 2015 Elsevier B.V. All rights reserved.
Phase-field-based lattice Boltzmann model for incompressible binary fluid systems with density and viscosity contrasts.

PubMed

Zu, Y Q; He, S

2013-04-01

A lattice Boltzmann model (LBM) is proposed based on the phase-field theory to simulate incompressible binary fluids with density and viscosity contrasts. Unlike many existing diffuse interface models which are limited to density matched binary fluids, the proposed model is capable of dealing with binary fluids with moderate density ratios. A new strategy for projecting the phase field to the viscosity field is proposed on the basis of the continuity of viscosity flux. The new LBM utilizes two lattice Boltzmann equations (LBEs): one for the interface tracking and the other for solving the hydrodynamic properties. The LBE for interface tracking can recover the Chan-Hilliard equation without any additional terms; while the LBE for hydrodynamic properties can recover the exact form of the divergence-free incompressible Navier-Stokes equations avoiding spurious interfacial forces. A series of 2D and 3D benchmark tests have been conducted for validation, which include a rigid-body rotation, stationary and moving droplets, a spinodal decomposition, a buoyancy-driven bubbly flow, a layered Poiseuille flow, and the Rayleigh-Taylor instability. It is shown that the proposed method can track the interface with high accuracy and stability and can significantly and systematically reduce the parasitic current across the interface. Comparisons with momentum-based models indicate that the newly proposed velocity-based model can better satisfy the incompressible condition in the flow fields, and eliminate or reduce the velocity fluctuations in the higher-pressure-gradient region and, therefore, achieve a better numerical stability. In addition, the test of a layered Poiseuille flow demonstrates that the proposed scheme for mixture viscosity performs significantly better than the traditional mixture viscosity methods.

Perfectionism and athlete burnout in junior elite athletes: the mediating role of coping tendencies.

PubMed

Hill, Andrew P; Hall, Howard K; Appleton, Paul R

2010-07-01

Recent research indicates that some dimensions of perfectionism are positively related to athlete burnout, whereas others are negatively related to athlete burnout. The divergent relationship between these dimensions of perfectionism and athlete burnout may be explained by different coping tendencies. The present investigation examined whether different coping tendencies mediate the relationship between self-oriented and socially prescribed perfectionism and burnout. Two-hundred and six junior elite athletes (M age=15.15 years, SD=1.88 years, range=11-22 years) completed measures of self-oriented and socially prescribed perfectionism, coping tendencies, and athlete burnout. Structural equation modeling indicated that the relationship between dimensions of perfectionism and athlete burnout was mediated by different coping tendencies. Higher levels of socially prescribed perfectionism was related to higher levels of avoidant coping which, in turn, was related to higher levels of athlete burnout. In contrast, higher levels of self-oriented perfectionism was related to higher levels of problem-focused coping and lower levels of avoidant coping which, in turn, was related to lower levels of athlete burnout. The findings suggest that different coping tendencies may underpin the divergent relationship between self-oriented and socially prescribed dimensions of perfectionism and athlete burnout.
Predicting the cosmological constant with the scale-factor cutoff measure

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

De Simone, Andrea; Guth, Alan H.; Salem, Michael P.

2008-09-15

It is well known that anthropic selection from a landscape with a flat prior distribution of cosmological constant {lambda} gives a reasonable fit to observation. However, a realistic model of the multiverse has a physical volume that diverges with time, and the predicted distribution of {lambda} depends on how the spacetime volume is regulated. A very promising method of regulation uses a scale-factor cutoff, which avoids a number of serious problems that arise in other approaches. In particular, the scale-factor cutoff avoids the 'youngness problem' (high probability of living in a much younger universe) and the 'Q and G catastrophes'more » (high probability for the primordial density contrast Q and gravitational constant G to have extremely large or small values). We apply the scale-factor cutoff measure to the probability distribution of {lambda}, considering both positive and negative values. The results are in good agreement with observation. In particular, the scale-factor cutoff strongly suppresses the probability for values of {lambda} that are more than about 10 times the observed value. We also discuss qualitatively the prediction for the density parameter {omega}, indicating that with this measure there is a possibility of detectable negative curvature.« less
Age, gender and deterrability: Are younger male drivers more likely to discount the future?

PubMed

Freeman, James; Kaye, Sherrie-Anne; Truelove, Verity; Davey, Jeremy

2017-07-01

Utilizing the Classical Deterrence theory and Stafford and Warr's (1993) reconceptualized model of deterrence, the current study examined whether age, gender, and discounting the future tendencies influence perceptions of being apprehended for speeding offences. Licensed motorists (N=700; 57% female) in Queensland (Australia) were recruited to complete a self-report questionnaire that measured perceptual deterrence, speeding related behaviors and discounting the future tendencies. Data were analyzed utilizing descriptive, bivariate and multivariate regressions. Significant (albeit weak) positive correlations were found between age and perceptions of apprehension certainty. Males were significantly more likely to report higher incidences of speeding (including while avoiding detection) compared to females. In contrast, females were more likely to perceive high levels of apprehension certainty and consider impending penalties to be more severe. At a multivariate level, discounting the future tendencies (in addition to being male, reporting lower levels of perceptual severity and swiftness, and more instances of punishment avoidance) were predictive of lower perceptual certainty levels. This study is one of the first to reveal that being male and having a tendency to discount the consequences of the future may directly influence drivers' perceptual deterrence levels. Copyright © 2017 Elsevier Ltd. All rights reserved.
Opposite roles for neuropeptide S in the nucleus accumbens and bed nucleus of the stria terminalis in learned helplessness rats.

PubMed

Shirayama, Yukihiko; Ishima, Tamaki; Oda, Yasunori; Okamura, Naoe; Iyo, Masaomi; Hashimoto, Kenji

2015-09-15

The role of neuropeptide S (NPS) in depression remains unclear. We examined the antidepressant-like effects of NPS infusions into the shell or core regions of the nucleus accumbens (NAc) and into the bed nucleus of the stria terminalis (BNST) of learned helplessness (LH) rats (an animal model of depression). Infusions of NPS (10 pmol/side) into the NAc shell, but not the NAc core and BNST, exerted antidepressant-like effects in the LH paradigm. Implying that behavioral deficits could be improved in the conditioned avoidance test. Coinfusion of SHA68 (an NPS receptor antagonist, 100 pmol/side) with NPS into the NAc shell blocked these effects. In contrast, NPS receptor antagonism by SHA68 in the BNST induced antidepressant-like effects. Infusions of NPS into the NAc shell or SHA68 into the BNST did not produce memory deficits or locomotor activation in the passive avoidance and open field tests. These results suggest that excitatory and inhibitory actions by the NPS system are integral to the depression in LH animals. Copyright © 2015 Elsevier B.V. All rights reserved.
Learned parasite avoidance is driven by host personality and resistance to infection in a fish–trematode interaction

PubMed Central

Karvonen, Anssi

2016-01-01

Cognitive abilities related to the assessment of risk improve survival. While earlier studies have examined the ability of animals to learn to avoid predators, learned parasite avoidance has received little interest. In a series of behavioural trials with the trematode parasite Diplostomum pseudospathaceum, we asked whether sea trout (Salmo trutta trutta) hosts show associative learning in the context of parasitism and if so, whether learning capacity is related to the likelihood of infection mediated through host personality and resistance. We show that animals are capable of learning to avoid visual cues associated with the presence of parasites. However, avoidance behaviour ceased after the likely activation of host resistance following consecutive exposures during learning, suggesting that resistance to infection outweighs avoidance. Further, we found a positive relationship between learning ability and boldness, suggesting a compensation of risky lifestyles through increased investment in cognitive abilities. By contrast, an increased risk of infection due to low resistance was not balanced by learning ability. Instead, these traits were positively related, which may be explained by inherent physiological qualities controlling both traits. Overall, the results demonstrate that parasitism, in addition to other biological interactions such as predation, is an important selective factor in the evolution of animal cognition. PMID:27605504
In action or inaction? Social approach-avoidance tendencies in major depression.

PubMed

Radke, Sina; Güths, Franziska; André, Julia A; Müller, Bernhard W; de Bruijn, Ellen R A

2014-11-30

In depression, approach deficits often impair everyday social functioning, but empirical findings on performance-based measurements of approach-avoidance behavior remain conflicting. To investigate action tendencies in patients with depression, the current study used an explicit version of the Approach-Avoidance Task (AAT). In this task, participants responded to emotional faces by either pulling a joystick toward (approach) or pushing it away from themselves (avoid). Reaction times to happy and angry expressions with direct and averted gaze were assessed in 30 patients with major depressive disorder and 20 matched healthy controls. In contrast to healthy individuals, depressed patients did not show approach-avoidance tendencies, i.e., there was no dominant behavioral tendency and they reacted to happy and angry expressions likewise. These results indicate that behavioral adjustments to different emotional expressions, gaze directions or motivational demands were lacking in depression. Crucially, this distinguishes depressed patients not only from healthy individuals, but also from other clinical populations that demonstrate aberrant approach-avoidance tendencies, e.g., patients with social anxiety or psychopathy. As responding flexibly to different social signals is integral to social interactions, the absence of any social motivational tendencies seems maladaptive, but may also provide opportunities for modifying action tendencies in a therapeutic context. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
Human Factors Design Guidelines for the Army Tactical Command and Control System (ATTCS) Soldier-Machine Interface. Version 2.0

DTIC Science & Technology

1992-05-01

especially true for friend-enemy or danger-safe designations. Dots, dashes, shapes, and video effects are recommended. Care must be taken to avoid visual...MAY 92 10.3 Screen Design - Format 10.3.1.4 Use of Contrasting Features Use contrasting features such as inverse video and color to call attention to...captions. Do not use reverse video or highlighting for labels. 13.2.3.2 Formatting For single fields, locate the caption to the left of the entry fields
The association between harm avoidance personality traits and self-reported concussion history in South African rugby union players.

PubMed

Mc Fie, Sarah; Abrahams, Shameemah; Patricios, Jon; Suter, Jason; Posthumus, Michael; September, Alison V

2018-01-01

Personality traits have been proposed to affect the risk of sports concussion, but evidence is limited. Cloninger's Tridimensional Personality Questionnaire (TPQ) measures novelty seeking, harm avoidance (HA), and reward dependence traits. The aim of this study was to investigate the relationship between TPQ scores and concussion history in rugby union players. Cross-sectional study. Rugby players from high schools, senior amateur clubs, and professional teams provided a self-reported concussion history and completed the TPQ. Participants reporting no previous concussions formed the control group, while participants reporting concussion formed the case group. A one-way analysis of covariance, with age as a covariate, was used to examine the differences in TPQ scores between groups. Of the 309 participants, 54% reported a minimum of one concussion (junior: 47%; amateur: 52%; professional: 72%). HA scores were significantly higher in junior players without a history of concussion compared to cases (p=0.006). Specifically, the junior control group had higher "anticipatory worry" (p=0.009) and "fear of uncertainty" (p=0.008). In contrast, the professional control group had lower HA scores than cases (p=0.009), while the amateur cohort displayed no differences between control and case groups. This study identified a novel association between HA and concussion in rugby players, adding evidence to the role of personality in a multifactorial risk-model of concussion. The findings suggest that lower HA may lead to increased dangerous play in youth rugby, influencing concussion susceptibility. Contrasting associations in the professional cohort suggest further research is required to understand the role of personality in concussion. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
Contrasting Impact of Future CO2 Emission Scenarios on the Extent of CaCO3 Mineral Undersaturation in the Humboldt Current System

NASA Astrophysics Data System (ADS)

Franco, A. C.; Gruber, N.; Frölicher, T. L.; Kropuenske Artman, L.

2018-03-01

The eastern boundary upwelling systems are among those regions that are most vulnerable to an ocean acidification-induced transition toward undersaturated conditions with respect to mineral CaCO3, but no assessment exists yet for the Humboldt Current System. Here we use a high-resolution (˜7.5 km) regional ocean model to investigate past and future changes in ocean pH and CaCO3 saturation state in this system. We find that within the next few decades, the nearshore waters off Peru are projected to become corrosive year round with regard to aragonite, the more soluble form of CaCO3. The volume of aragonite undersaturated water off Peru will continue to increase in the future irrespective of the amount of CO2 emitted to the atmosphere. In contrast, the development of the saturation state with regard to calcite, a less soluble form of carbonate, depends strongly on the scenario followed. By 2050, calcite undersaturation appears in the nearshore waters off Peru occasionally, but by 2090 in a high-emission scenario (RCP8.5), ˜60% of the water in the euphotic zone will become permanently calcite undersaturated. Most of this calcite undersaturation off Peru can likely be avoided if a low emission scenario (RCP2.6) consistent with the Paris Agreement is followed. The progression of ocean acidification off Chile follows a similar pattern, except that the saturation states are overall higher. But also here, calcite undersaturated waters will become common in the subsurface waters under the RCP8.5 scenario by the end of this century, while this can be avoided under the RCP2.6 scenario.
The dual pathway model of AD/HD: an elaboration of neuro-developmental characteristics.

PubMed

Sonuga-Barke, Edmund J S

2003-11-01

The currently dominant neuro-cognitive model of Attention Deficit Hyperactivity Disorder (AD/HD) presents the condition as executive dysfunction (EDF) underpinned by disturbances in the fronto-dorsal striatal circuit and associated dopaminergic branches (e.g. meso-cortical). In contrast, motivationally-based accounts focus on altered reward processes and implicate fronto-ventral striatal reward circuits and those meso-limbic branches that terminate in the ventral striatum especially the nucleus accumbens. One such account, delay aversion (DEL), presents AD/HD as a motivational style-characterised by attempts to escape or avoid delay-arising from fundamental disturbances in these reward centres. While traditionally regarded as competing, EDF and DEL models have recently been presented as complimentary accounts of two psycho-patho-physiological subtypes of AD/HD with different developmental pathways, underpinned by different cortico-striatal circuits and modulated by different branches of the dopamine system. In the current paper we describe the development of this model in more detail. We elaborate on the neuro-circuitry possibly underpinning these two pathways and explore their developmental significance within a neuro-ecological framework.
Robust estimation-free prescribed performance back-stepping control of air-breathing hypersonic vehicles without affine models

NASA Astrophysics Data System (ADS)

Bu, Xiangwei; Wu, Xiaoyan; Huang, Jiaqi; Wei, Daozhi

2016-11-01

This paper investigates the design of a novel estimation-free prescribed performance non-affine control strategy for the longitudinal dynamics of an air-breathing hypersonic vehicle (AHV) via back-stepping. The proposed control scheme is capable of guaranteeing tracking errors of velocity, altitude, flight-path angle, pitch angle and pitch rate with prescribed performance. By prescribed performance, we mean that the tracking error is limited to a predefined arbitrarily small residual set, with convergence rate no less than a certain constant, exhibiting maximum overshoot less than a given value. Unlike traditional back-stepping designs, there is no need of an affine model in this paper. Moreover, both the tedious analytic and numerical computations of time derivatives of virtual control laws are completely avoided. In contrast to estimation-based strategies, the presented estimation-free controller possesses much lower computational costs, while successfully eliminating the potential problem of parameter drifting. Owing to its independence on an accurate AHV model, the studied methodology exhibits excellent robustness against system uncertainties. Finally, simulation results from a fully nonlinear model clarify and verify the design.
Refining the assessment of internal working models: the Attachment Multiple Model Interview.

PubMed

Miljkovitch, Raphaële; Moss, Ellen; Bernier, Annie; Pascuzzo, Katherine; Sander, Emmanuel

2015-01-01

The Attachment Multiple Model Interview (AMMI) was developed to assess internal working models (IWMs) of specific relationships in adulthood (e.g., with mother, father, and romantic partner). In an initial effort to validate the AMMI, the interview was administered to participants who were followed from age 4 to 23. ANOVA and contrast tests confirmed the AMMI's capacity to discriminate between mother, father, and partner IWMs. AMMI security with each parent was correlated with coherence according to the Adult Attachment Interview, and AMMI disorganization with mother with unresolved trauma (N = 53). AMMI dimensions of security, deactivation, and hyperactivation with the mother were associated with cumulative lifetime scores of security (N = 23), avoidance, and resistance (N = 34), respectively. Intercorrelations between these AMMI scales were also theory-consistent. Associations with the AAI and between AMMI security scores of different relationships are consistent with previous findings suggesting a contribution from both parents in the development of a state of mind, but a more important role of the mother for representations of the partner.
Avoidance response of juvenile Pacific treefrogs to chemical cues of introduced predatory bullfrogs.

PubMed

Chivers, D P; Wildy, E L; Kiesecker, J M; Blaustein, A R

2001-08-01

Bullfrogs (Rana catesbeiana), native to eastern North America, were introduced into Oregon in the 1930's. Bullfrogs are highly efficient predators that are known to eat a variety of prey including other amphibians. In laboratory experiments, we investigated whether juvenile Pacific treefrogs (Hyla regilla) recognize adult bullfrogs as a predatory threat. The ability of prey animals to acquire recognition of an introduced predator has important implications for survival of the prey. We found that treefrogs from a population that co-occurred with bullfrogs showed a strong avoidance of chemical cues of bullfrogs. In contrast, treefrogs from a population that did not co-occur with bullfrogs, did not respond to the bullfrog cues. Additional experiments showed that both populations of treefrogs use chemical cues to mediate predation risk. Treefrogs from both populations avoided chemical alarm cues from injured conspecifics.
The Organization of Words and Symbolic Gestures in 18-Month-Olds’ Lexicons: Evidence from a Disambiguation Task

PubMed Central

Suanda, Sumarga H.; Namy, Laura L.

2012-01-01

Infants’ early communicative repertoires include both words and symbolic gestures. The current study examined the extent to which infants organize words and gestures in a single unified lexicon. As a window into lexical organization, eighteen-month-olds’ (N = 32) avoidance of word-gesture overlap was examined and compared to avoidance of word-word overlap. The current study revealed that when presented with novel words, infants avoided lexical overlap, mapping novel words onto novel objects. In contrast, when presented with novel gestures, infants sought overlap, mapping novel gestures onto familiar objects. The results suggest that infants do not treat words and gestures as equivalent lexical items and that during a period of development when word and symbolic gesture processing share many similarities, important differences also exist between these two symbolic forms. PMID:23539273
An enhanced MMW and SMMW/THz imaging system performance prediction and analysis tool for concealed weapon detection and pilotage obstacle avoidance

NASA Astrophysics Data System (ADS)

Murrill, Steven R.; Jacobs, Eddie L.; Franck, Charmaine C.; Petkie, Douglas T.; De Lucia, Frank C.

2015-10-01

The U.S. Army Research Laboratory (ARL) has continued to develop and enhance a millimeter-wave (MMW) and submillimeter- wave (SMMW)/terahertz (THz)-band imaging system performance prediction and analysis tool for both the detection and identification of concealed weaponry, and for pilotage obstacle avoidance. The details of the MATLAB-based model which accounts for the effects of all critical sensor and display components, for the effects of atmospheric attenuation, concealment material attenuation, and active illumination, were reported on at the 2005 SPIE Europe Security and Defence Symposium (Brugge). An advanced version of the base model that accounts for both the dramatic impact that target and background orientation can have on target observability as related to specular and Lambertian reflections captured by an active-illumination-based imaging system, and for the impact of target and background thermal emission, was reported on at the 2007 SPIE Defense and Security Symposium (Orlando). Further development of this tool that includes a MODTRAN-based atmospheric attenuation calculator and advanced system architecture configuration inputs that allow for straightforward performance analysis of active or passive systems based on scanning (single- or line-array detector element(s)) or staring (focal-plane-array detector elements) imaging architectures was reported on at the 2011 SPIE Europe Security and Defence Symposium (Prague). This paper provides a comprehensive review of a newly enhanced MMW and SMMW/THz imaging system analysis and design tool that now includes an improved noise sub-model for more accurate and reliable performance predictions, the capability to account for postcapture image contrast enhancement, and the capability to account for concealment material backscatter with active-illumination- based systems. Present plans for additional expansion of the model's predictive capabilities are also outlined.
The impact of stress on financial decision-making varies as a function of depression and anxiety symptoms.

PubMed

Robinson, Oliver J; Bond, Rebecca L; Roiser, Jonathan P

2015-01-01

Stress can precipitate the onset of mood and anxiety disorders. This may occur, at least in part, via a modulatory effect of stress on decision-making. Some individuals are, however, more resilient to the effects of stress than others. The mechanisms underlying such vulnerability differences are nevertheless unknown. In this study we attempted to begin quantifying individual differences in vulnerability by exploring the effect of experimentally induced stress on decision-making. The threat of unpredictable shock was used to induce stress in healthy volunteers (N = 47) using a within-subjects, within-session design, and its impact on a financial decision-making task (the Iowa Gambling Task) was assessed alongside anxious and depressive symptomatology. As expected, participants learned to select advantageous decks and avoid disadvantageous decks. Importantly, we found that stress provoked a pattern of harm-avoidant behaviour (decreased selection of disadvantageous decks) in individuals with low levels of trait anxiety. By contrast, individuals with high trait anxiety demonstrated the opposite pattern: stress-induced risk-seeking (increased selection of disadvantageous decks). These contrasting influences of stress depending on mood and anxiety symptoms might provide insight into vulnerability to common mental illness. In particular, we speculate that those who adopt a more harm-avoidant strategy may be better able to regulate their exposure to further environmental stress, reducing their susceptibility to mood and anxiety disorders.
Dynamic clearance measure to evaluate locomotor and perceptuo-motor strategies used for obstacle circumvention in a virtual environment.

PubMed

Darekar, Anuja; Lamontagne, Anouk; Fung, Joyce

2015-04-01

Circumvention around an obstacle entails a dynamic interaction with the obstacle to maintain a safe clearance. We used a novel mathematical interpolation method based on the modified Shepard's method of Inverse Distance Weighting to compute dynamic clearance that reflected this interaction as well as minimal clearance. This proof-of-principle study included seven young healthy, four post-stroke and four healthy age-matched individuals. A virtual environment designed to assess obstacle circumvention was used to administer a locomotor (walking) and a perceptuo-motor (navigation with a joystick) task. In both tasks, participants were asked to navigate towards a target while avoiding collision with a moving obstacle that approached from either head-on, or 30° left or right. Among young individuals, dynamic clearance did not differ significantly between obstacle approach directions in both tasks. Post-stroke individuals maintained larger and smaller dynamic clearance during the locomotor and the perceptuo-motor task respectively as compared to age-matched controls. Dynamic clearance was larger than minimal distance from the obstacle irrespective of the group, task and obstacle approach direction. Also, in contrast to minimal distance, dynamic clearance can respond differently to different avoidance behaviors. Such a measure can be beneficial in contrasting obstacle avoidance behaviors in different populations with mobility problems. Copyright © 2015 Elsevier B.V. All rights reserved.
Conflict management styles in the health professions.

PubMed

Sportsman, Susan; Hamilton, Patti

2007-01-01

The purpose of the study was to determine prevalent conflict management styles chosen by students in nursing and to contrast these styles with those chosen by students in allied health professions. The associations among the level of professional health care education and the style chosen were also determined. A convenience sample of 126 students in a comprehensive university completed the Thomas-Kilmann Conflict Mode Instrument (TKI), which requires respondents to choose behaviors most characteristic of their response to conflict and classifies these behaviors as one of five styles. There was no significant difference between the prevalent conflict management styles chosen by graduate and undergraduate nursing students and those in allied health. Some of the students were already licensed in their discipline; others had not yet taken a licensing exam. Licensure and educational level were not associated with choice of styles. Women and men had similar preferences. The prevalent style for nursing students was compromise, followed by avoidance. In contrast, avoidance, followed by compromise and accommodation, was the prevalent style for allied health students. When compared to the TKI norms, slightly more than one half of all participants chose two or more conflict management styles, commonly avoidance and accommodation at the 75th percentile or above. Only 9.8% of the participants chose collaboration at that level. Implications for nurse educators, researchers, and administrators are discussed.
Automatic and quantitative measurement of collagen gel contraction using model-guided segmentation

NASA Astrophysics Data System (ADS)

Chen, Hsin-Chen; Yang, Tai-Hua; Thoreson, Andrew R.; Zhao, Chunfeng; Amadio, Peter C.; Sun, Yung-Nien; Su, Fong-Chin; An, Kai-Nan

2013-08-01

Quantitative measurement of collagen gel contraction plays a critical role in the field of tissue engineering because it provides spatial-temporal assessment (e.g., changes of gel area and diameter during the contraction process) reflecting the cell behavior and tissue material properties. So far the assessment of collagen gels relies on manual segmentation, which is time-consuming and suffers from serious intra- and inter-observer variability. In this study, we propose an automatic method combining various image processing techniques to resolve these problems. The proposed method first detects the maximal feasible contraction range of circular references (e.g., culture dish) and avoids the interference of irrelevant objects in the given image. Then, a three-step color conversion strategy is applied to normalize and enhance the contrast between the gel and background. We subsequently introduce a deformable circular model which utilizes regional intensity contrast and circular shape constraint to locate the gel boundary. An adaptive weighting scheme was employed to coordinate the model behavior, so that the proposed system can overcome variations of gel boundary appearances at different contraction stages. Two measurements of collagen gels (i.e., area and diameter) can readily be obtained based on the segmentation results. Experimental results, including 120 gel images for accuracy validation, showed high agreement between the proposed method and manual segmentation with an average dice similarity coefficient larger than 0.95. The results also demonstrated obvious improvement in gel contours obtained by the proposed method over two popular, generic segmentation methods.
Adaptive optics in spinning disk microscopy: improved contrast and brightness by a simple and fast method.

PubMed

Fraisier, V; Clouvel, G; Jasaitis, A; Dimitrov, A; Piolot, T; Salamero, J

2015-09-01

Multiconfocal microscopy gives a good compromise between fast imaging and reasonable resolution. However, the low intensity of live fluorescent emitters is a major limitation to this technique. Aberrations induced by the optical setup, especially the mismatch of the refractive index and the biological sample itself, distort the point spread function and further reduce the amount of detected photons. Altogether, this leads to impaired image quality, preventing accurate analysis of molecular processes in biological samples and imaging deep in the sample. The amount of detected fluorescence can be improved with adaptive optics. Here, we used a compact adaptive optics module (adaptive optics box for sectioning optical microscopy), which was specifically designed for spinning disk confocal microscopy. The module overcomes undesired anomalies by correcting for most of the aberrations in confocal imaging. Existing aberration detection methods require prior illumination, which bleaches the sample. To avoid multiple exposures of the sample, we established an experimental model describing the depth dependence of major aberrations. This model allows us to correct for those aberrations when performing a z-stack, gradually increasing the amplitude of the correction with depth. It does not require illumination of the sample for aberration detection, thus minimizing photobleaching and phototoxicity. With this model, we improved both signal-to-background ratio and image contrast. Here, we present comparative studies on a variety of biological samples. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Not accounting for interindividual variability can mask habitat selection patterns: a case study on black bears.

PubMed

Lesmerises, Rémi; St-Laurent, Martin-Hugues

2017-11-01

Habitat selection studies conducted at the population scale commonly aim to describe general patterns that could improve our understanding of the limiting factors in species-habitat relationships. Researchers often consider interindividual variation in selection patterns to control for its effects and avoid pseudoreplication by using mixed-effect models that include individuals as random factors. Here, we highlight common pitfalls and possible misinterpretations of this strategy by describing habitat selection of 21 black bears Ursus americanus. We used Bayesian mixed-effect models and compared results obtained when using random intercept (i.e., population level) versus calculating individual coefficients for each independent variable (i.e., individual level). We then related interindividual variability to individual characteristics (i.e., age, sex, reproductive status, body condition) in a multivariate analysis. The assumption of comparable behavior among individuals was verified only in 40% of the cases in our seasonal best models. Indeed, we found strong and opposite responses among sampled bears and individual coefficients were linked to individual characteristics. For some covariates, contrasted responses canceled each other out at the population level. In other cases, interindividual variability was concealed by the composition of our sample, with the majority of the bears (e.g., old individuals and bears in good physical condition) driving the population response (e.g., selection of young forest cuts). Our results stress the need to consider interindividual variability to avoid misinterpretation and uninformative results, especially for a flexible and opportunistic species. This study helps to identify some ecological drivers of interindividual variability in bear habitat selection patterns.
Action Learning, Performativity and Negative Capability

ERIC Educational Resources Information Center

Edmonstone, John

2016-01-01

The paper examines the concept of negative capability as a human capacity for containment and contrasts it with well-valued positive capability as expressed through performativity in organisations and society. It identifies the problem of dispersal--the complex ways we behave in order to avoid the emotional challenges of living with uncertainty.…
Lexical Entrainment and Lexical Differentiation in Reference Phrase Choice

ERIC Educational Resources Information Center

Van Der Wege, Mija M.

2009-01-01

Speakers reuse prior references to objects when choosing reference phrases, a phenomenon known as lexical entrainment. One explanation is that speakers want to maintain a set of previously established referential precedents. Speakers may also contrast any new referents against this previously established set, thereby avoiding applying the same…
Better Safe than Sorry - Socio-Spatial Group Structure Emerges from Individual Variation in Fleeing, Avoidance or Velocity in an Agent-Based Model

PubMed Central

Evers, Ellen; de Vries, Han; Spruijt, Berry M.; Sterck, Elisabeth H. M.

2011-01-01

In group-living animals, such as primates, the average spatial group structure often reflects the dominance hierarchy, with central dominants and peripheral subordinates. This central-peripheral group structure can arise by self-organization as a result of subordinates fleeing from dominants after losing a fight. However, in real primates, subordinates often avoid interactions with potentially aggressive group members, thereby preventing aggression and subsequent fleeing. Using agent-based modeling, we investigated which spatial and encounter structures emerge when subordinates also avoid known potential aggressors at a distance as compared with the model which only included fleeing after losing a fight (fleeing model). A central-peripheral group structure emerged in most conditions. When avoidance was employed at small or intermediate distances, centrality of dominants emerged similar to the fleeing model, but in a more pronounced way. This result was also found when fleeing after a fight was made independent of dominance rank, i.e. occurred randomly. Employing avoidance at larger distances yielded more spread out groups. This provides a possible explanation of larger group spread in more aggressive species. With avoidance at very large distances, spatially and socially distinct subgroups emerged. We also investigated how encounters were distributed amongst group members. In the fleeing model all individuals encountered all group members equally often, whereas in the avoidance model encounters occurred mostly among similar-ranking individuals. Finally, we also identified a very general and simple mechanism causing a central-peripheral group structure: when individuals merely differed in velocity, faster individuals automatically ended up at the periphery. In summary, a central-peripheral group pattern can easily emerge from individual variation in different movement properties in general, such as fleeing, avoidance or velocity. Moreover, avoidance behavior also affects the encounter structure and can lead to subgroup formation. PMID:22125595
NCAM deficiency in the mouse forebrain impairs innate and learned avoidance behaviours.

PubMed

Brandewiede, J; Stork, O; Schachner, M

2014-06-01

The neural cell adhesion molecule (NCAM) has been implicated in the development and plasticity of neural circuits and the control of hippocampus- and amygdala-dependent learning and behaviour. Previous studies in constitutive NCAM null mutants identified emotional behaviour deficits related to disturbances of hippocampal and amygdala functions. Here, we studied these behaviours in mice conditionally deficient in NCAM in the postmigratory forebrain neurons. We report deficits in both innate and learned avoidance behaviours, as observed in elevated plus maze and passive avoidance tasks. In contrast, general locomotor activity, trait anxiety or neophobia were unaffected by the mutation. Altered avoidance behaviour of the conditional NCAM mutants was associated with a deficit in serotonergic signalling, as indicated by their reduced responsiveness to (±)-8-hydroxy-2-(dipropylamino)-tetralin-induced hypothermia. Another serotonin-dependent behaviour, namely intermale aggression that is massively increased in constitutively NCAM-deficient mice, was not affected in the forebrain-specific mutants. Our data suggest that genetically or environmentally induced changes of NCAM expression in the late postnatal and mature forebrain determine avoidance behaviour and serotonin (5-HT)1A receptor signalling. © 2014 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.
Acculturative stress and experiential avoidance: relations to depression, suicide, and anxiety symptoms among minority college students.

PubMed

Zvolensky, Michael J; Jardin, Charles; Garey, Lorra; Robles, Zuzuky; Sharp, Carla

2016-11-01

Although college campuses represent strategic locations to address mental health disparity among minorities in the US, there has been strikingly little empirical work on risk processes for anxiety/depression among this population. The present investigation examined the interactive effects of acculturative stress and experiential avoidance in relation to anxiety and depressive symptoms among minority college students (n = 1,095; 78.1% female; Mage = 21.92, SD = 4.23; 15.1% African-American (non-Hispanic), 45.3% Hispanic, 32.5% Asian, and 7.1% other races/ethnicities. Results provided empirical evidence of an interaction between acculturative stress and experiential avoidance for suicidal, social anxiety, and anxious arousal symptoms among the studied sample. Inspection of the significant interactions revealed that acculturative stress was related to greater levels of suicidal symptoms, social anxiety, and anxious arousal among minority college students with higher, but not lower, levels of experiential avoidance. However, in contrast to prediction, there was no significant interaction for depressive symptoms. Together, these data provide novel empirical evidence for the clinically-relevant interplay between acculturative stress and experiential avoidance in regard to a relatively wide array of negative emotional states among minority college students.
The Feasibility of Avoiding Future Climate Impacts: Results from the AVOID Programmes

NASA Astrophysics Data System (ADS)

Lowe, J. A.; Warren, R.; Arnell, N.; Buckle, S.

2014-12-01

The AVOID programme and its successor, AVOID2, have focused on answering three core questions: how do we characterise potentially dangerous climate change and impacts, which emissions pathways can avoid at least some of these impacts, and how feasible are the future reductions needed to significantly deviate from a business-as-usual future emissions pathway. The first AVOID project succeeded in providing the UK Government with evidence to inform its position on climate change. A key part of the work involved developing a range of global emissions pathways and estimating and understanding the corresponding global impacts. This made use of a combination of complex general circulation models, simple climate models, pattern-scaling and state-of-the art impacts models. The results characterise the range of avoidable impacts across the globe in several key sectors including river and coastal flooding, cooling and heating energy demand, crop productivity and aspects of biodiversity. The avoided impacts between a scenario compatible with a 4ºC global warming and one with a 2ºC global warming were found to be highly sector dependent and avoided fractions typically ranged between 20% and 70%. A further key aspect was characterising the magnitude of the uncertainty involved, which is found to be very large in some impact sectors although the avoided fraction appears a more robust metric. The AVOID2 programme began in 2014 and will provide results in the run up to the Paris CoP in 2015. This includes new post-IPCC 5th assessment evidence to inform the long-term climate goal, a more comprehensive assessment of the uncertainty ranges of feasible emission pathways compatible with the long-term goal and enhanced estimates of global impacts using the latest generation of impact models and scenarios.
Testing the role of reward and punishment sensitivity in avoidance behavior: a computational modeling approach

PubMed Central

Sheynin, Jony; Moustafa, Ahmed A.; Beck, Kevin D.; Servatius, Richard J.; Myers, Catherine E.

2015-01-01

Exaggerated avoidance behavior is a predominant symptom in all anxiety disorders and its degree often parallels the development and persistence of these conditions. Both human and non-human animal studies suggest that individual differences as well as various contextual cues may impact avoidance behavior. Specifically, we have recently shown that female sex and inhibited temperament, two anxiety vulnerability factors, are associated with greater duration and rate of the avoidance behavior, as demonstrated on a computer-based task closely related to common rodent avoidance paradigms. We have also demonstrated that avoidance is attenuated by the administration of explicit visual signals during “non-threat” periods (i.e., safety signals). Here, we use a reinforcement-learning network model to investigate the underlying mechanisms of these empirical findings, with a special focus on distinct reward and punishment sensitivities. Model simulations suggest that sex and inhibited temperament are associated with specific aspects of these sensitivities. Specifically, differences in relative sensitivity to reward and punishment might underlie the longer avoidance duration demonstrated by females, whereas higher sensitivity to punishment might underlie the higher avoidance rate demonstrated by inhibited individuals. Simulations also suggest that safety signals attenuate avoidance behavior by strengthening the competing approach response. Lastly, several predictions generated by the model suggest that extinction-based cognitive-behavioral therapies might benefit from the use of safety signals, especially if given to individuals with high reward sensitivity and during longer safe periods. Overall, this study is the first to suggest cognitive mechanisms underlying the greater avoidance behavior observed in healthy individuals with different anxiety vulnerabilities. PMID:25639540
[Between the exaggerated and the exasperated clinic. Bridges, differences and rupture in child and youth mental care].

PubMed

Armus, Marcela; Costa, Juan J

2014-01-01

This article intends to approach a series of contrasting concepts regarding different relevant issues for the Child and Youth Mental Health. Diagnosis as a temporary and unstable assessment method. Early detection and treatment as opposed to the possibility of premature diagnoses. The possible or impossible dialogues between psychoanalysis, neuroscience and cognitive sciences. The problems associated with autism and its different theoretical approach models. The development of each of these complex aspects of the practice considers the risk of treating the child as a mere "pathological entity" and dehumanizing him and his condition from the different perspectives, disciplines and discourses, which intend to address the child and his condition. Finally this proposal aims at building bridges of dialogue, overcoming differences in order to avoid rupture.
The Arsenic crisis in Bangladesh (Invited)

NASA Astrophysics Data System (ADS)

Harvey, C.; Ashfaque, K.; Neumann, R. B.; Badruzzaman, B.; Ali, A.

2010-12-01

The Ganges Delta suffers from water-borne disease. Arsenic in the groundwater pumped from drinking water wells is causing severe and widespread disease, and these wells were installed, in part, to avoid pathogens in the surface water supply. I will discuss the hydrogeologic controls of arsenic concentrations in groundwater, specifically the role of enhanced groundwater circulation driven by irrigation pumping and the effects of the solute loads transported into aquifers with recharge through different surface features, such as rice fields, rivers, and ponds. I will contrast the approaches taken in Southeast Asia for studying groundwater contamination with methods used in the U.S. I will compare findings from several sites in the region and consider how improved models of the coupled hydrologic and biogeochemical system can be used to provide safer water.
Image dehazing based on non-local saturation

NASA Astrophysics Data System (ADS)

Wang, Linlin; Zhang, Qian; Yang, Deyun; Hou, Yingkun; He, Xiaoting

2018-04-01

In this paper, a method based on non-local saturation algorithm is proposed to avoid block and halo effect for single image dehazing with dark channel prior. First we convert original image from RGB color space into HSV color space with the idea of non-local method. Image saturation is weighted equally by the size of fixed window according to image resolution. Second we utilize the saturation to estimate the atmospheric light value and transmission rate. Then through the function of saturation and transmission, the haze-free image is obtained based on the atmospheric scattering model. Comparing the results of existing methods, our method can restore image color and enhance contrast. We guarantee the proposed method with quantitative and qualitative evaluation respectively. Experiments show the better visual effect with high efficiency.
A new approach for describing glass transition kinetics.

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

Vasin, N. M.; Shchelkachev, M. G.; Vinokur, V. M.

2010-04-01

We use a functional integral technique generalizing the Keldysh diagram technique to describe glass transition kinetics. We show that the Keldysh functional approach takes the dynamical determinant arising in the glass dynamics into account exactly and generalizes the traditional approach based on using the supersymmetric dynamic generating functional method. In contrast to the supersymmetric method, this approach allows avoiding additional Grassmannian fields and tracking the violation of the fluctuation-dissipation theorem explicitly. We use this method to describe the dynamics of an Edwards-Anderson soft spin-glass-type model near the paramagnet-glass transition. We show that a Vogel-Fulcher-type dynamics arises in the fluctuation regionmore » only if the fluctuation-dissipation theorem is violated in the process of dynamical renormalization of the Keldysh action in the replica space.« less
Integration of Weather Avoidance and Traffic Separation

NASA Technical Reports Server (NTRS)

Consiglio, Maria C.; Chamberlain, James P.; Wilson, Sara R.

2011-01-01

This paper describes a dynamic convective weather avoidance concept that compensates for weather motion uncertainties; the integration of this weather avoidance concept into a prototype 4-D trajectory-based Airborne Separation Assurance System (ASAS) application; and test results from a batch (non-piloted) simulation of the integrated application with high traffic densities and a dynamic convective weather model. The weather model can simulate a number of pseudo-random hazardous weather patterns, such as slow- or fast-moving cells and opening or closing weather gaps, and also allows for modeling of onboard weather radar limitations in range and azimuth. The weather avoidance concept employs nested "core" and "avoid" polygons around convective weather cells, and the simulations assess the effectiveness of various avoid polygon sizes in the presence of different weather patterns, using traffic scenarios representing approximately two times the current traffic density in en-route airspace. Results from the simulation experiment show that the weather avoidance concept is effective over a wide range of weather patterns and cell speeds. Avoid polygons that are only 2-3 miles larger than their core polygons are sufficient to account for weather uncertainties in almost all cases, and traffic separation performance does not appear to degrade with the addition of weather polygon avoidance. Additional "lessons learned" from the batch simulation study are discussed in the paper, along with insights for improving the weather avoidance concept. Introduction
SU-E-I-43: Pediatric CT Dose and Image Quality Optimization

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

Stevens, G; Singh, R

2014-06-01

Purpose: To design an approach to optimize radiation dose and image quality for pediatric CT imaging, and to evaluate expected performance. Methods: A methodology was designed to quantify relative image quality as a function of CT image acquisition parameters. Image contrast and image noise were used to indicate expected conspicuity of objects, and a wide-cone system was used to minimize scan time for motion avoidance. A decision framework was designed to select acquisition parameters as a weighted combination of image quality and dose. Phantom tests were used to acquire images at multiple techniques to demonstrate expected contrast, noise and dose.more » Anthropomorphic phantoms with contrast inserts were imaged on a 160mm CT system with tube voltage capabilities as low as 70kVp. Previously acquired clinical images were used in conjunction with simulation tools to emulate images at different tube voltages and currents to assess human observer preferences. Results: Examination of image contrast, noise, dose and tube/generator capabilities indicates a clinical task and object-size dependent optimization. Phantom experiments confirm that system modeling can be used to achieve the desired image quality and noise performance. Observer studies indicate that clinical utilization of this optimization requires a modified approach to achieve the desired performance. Conclusion: This work indicates the potential to optimize radiation dose and image quality for pediatric CT imaging. In addition, the methodology can be used in an automated parameter selection feature that can suggest techniques given a limited number of user inputs. G Stevens and R Singh are employees of GE Healthcare.« less
Nurses' intention to resign and avoidance of emergency department violence: A moderated mediation model.

PubMed

Li, Yu-Fang; Chao, Minston; Shih, Chih-Ting

2017-10-10

Studies that examined the negative impact of violence in emergency departments on nurses' leave and avoidance behavior are well-documented. However, few studies provided an integrated model of how and when violence influences their leave and avoidance behavior. The study adopted Affective Events Theory to propose and examine a model of violent events, negative emotions, and (leave and avoidance) behaviors on nurses in emergency departments and further analyzed whether the model is salient to nurses' occupational burnout, nursing experience, and nursing rank. The sample included 123 emergency department nurses at a teaching hospital in northern, Taiwan. All participants had experienced violent incidents within the preceding 6 months. Moderated mediation analysis suggested that nurses experienced one of two emotional processes following violent incidents: "violence-negative feelings toward work-intention to resign" or "violence-negative emotion and physical symptoms-avoidance tendencies." Moreover, nurses with high burnout levels expressed weaker intention to resign after violent incidents, while nurses with more experience and higher rank were less likely to avoid violence after violent incidents. Emergency nurses do not simply elect to escape but may engage in avoidance behavior. This study revealed that how violent incidents affect nurses' resignation or avoidance behaviors depends on how they feel. Occupational burnout and nurses' attributes affected their behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.
Emotion avoidance in patients with anorexia nervosa: initial test of a functional model.

PubMed

Wildes, Jennifer E; Ringham, Rebecca M; Marcus, Marsha D

2010-07-01

This study aimed to evaluate emotion avoidance in patients with anorexia nervosa (AN) and to examine whether emotion avoidance helps to explain (i.e., mediates) the relation between depressive and anxiety symptoms and eating disorder (ED) psychopathology in this group. Seventy-five patients with AN completed questionnaires to assess study variables. Rates of emotion avoidance were compared to published data, and regression models were used to test the hypothesis that emotion avoidance mediates the relation between depressive and anxiety symptoms and ED psychopathology in AN. Patients with AN endorsed levels of emotion avoidance that were comparable to or higher than other psychiatric populations and exceeded community controls. As predicted, emotion avoidance significantly explained the relations of depressive and anxiety symptoms to ED psychopathology. Findings confirm that emotion avoidance is present in patients with AN and provide initial support for the idea that anorexic symptoms function, in part, to help individuals avoid aversive emotional states. 2009 by Wiley Periodicals, Inc.
A framework for the identification of long-term social avoidance in longitudinal datasets

PubMed Central

Levengood, Alexis; Foroughirad, Vivienne; Mann, Janet; Krzyszczyk, Ewa

2017-01-01

Animal sociality is of significant interest to evolutionary and behavioural ecologists, with efforts focused on the patterns, causes and fitness outcomes of social preference. However, individual social patterns are the consequence of both attraction to (preference for) and avoidance of conspecifics. Despite this, social avoidance has received far less attention than social preference. Here, we detail the necessary steps to generate a spatially explicit, iterative null model which can be used to identify non-random social avoidance in longitudinal studies of social animals. We specifically identify and detail parameters which will influence the validity of the model. To test the usability of this model, we applied it to two longitudinal studies of social animals (Eastern water dragons (Intellegama lesueurii) and bottlenose dolphins (Tursiops aduncus)) to identify the presence of social avoidances. Using this model allowed us to identify the presence of social avoidances in both species. We hope that the framework presented here inspires interest in addressing this critical gap in our understanding of animal sociality, in turn allowing for a more holistic understanding of social interactions, relationships and structure. PMID:28879006
A framework for the identification of long-term social avoidance in longitudinal datasets.

PubMed

Strickland, Kasha; Levengood, Alexis; Foroughirad, Vivienne; Mann, Janet; Krzyszczyk, Ewa; Frère, Celine H

2017-08-01

Animal sociality is of significant interest to evolutionary and behavioural ecologists, with efforts focused on the patterns, causes and fitness outcomes of social preference. However, individual social patterns are the consequence of both attraction to (preference for) and avoidance of conspecifics. Despite this, social avoidance has received far less attention than social preference. Here, we detail the necessary steps to generate a spatially explicit, iterative null model which can be used to identify non-random social avoidance in longitudinal studies of social animals. We specifically identify and detail parameters which will influence the validity of the model. To test the usability of this model, we applied it to two longitudinal studies of social animals (Eastern water dragons ( Intellegama lesueurii ) and bottlenose dolphins ( Tursiops aduncus )) to identify the presence of social avoidances. Using this model allowed us to identify the presence of social avoidances in both species. We hope that the framework presented here inspires interest in addressing this critical gap in our understanding of animal sociality, in turn allowing for a more holistic understanding of social interactions, relationships and structure.
Integrating environmental and socio-economic indicators of a linked catchment-coastal system using variable environmental intensity.

PubMed

Dymond, John R; Davie, Tim J A; Fenemor, Andrew D; Ekanayake, Jagath C; Knight, Ben R; Cole, Anthony O; de Oca Munguia, Oscar Montes; Allen, Will J; Young, Roger G; Basher, Les R; Dresser, Marc; Batstone, Chris J

2010-09-01

Can we develop land use policy that balances the conflicting views of stakeholders in a catchment while moving toward long term sustainability? Adaptive management provides a strategy for this whereby measures of catchment performance are compared against performance goals in order to progressively improve policy. However, the feedback loop of adaptive management is often slow and irreversible impacts may result before policy has been adapted. In contrast, integrated modelling of future land use policy provides rapid feedback and potentially improves the chance of avoiding unwanted collapse events. Replacing measures of catchment performance with modelled catchment performance has usually required the dynamic linking of many models, both biophysical and socio-economic-and this requires much effort in software development. As an alternative, we propose the use of variable environmental intensity (defined as the ratio of environmental impact over economic output) in a loose coupling of models to provide a sufficient level of integration while avoiding significant effort required for software development. This model construct was applied to the Motueka Catchment of New Zealand where several biophysical (riverine water quantity, sediment, E. coli faecal bacteria, trout numbers, nitrogen transport, marine productivity) models, a socio-economic (gross output, gross margin, job numbers) model, and an agent-based model were linked. An extreme set of land use scenarios (historic, present, and intensive) were applied to this modelling framework. Results suggest that the catchment is presently in a near optimal land use configuration that is unlikely to benefit from further intensification. This would quickly put stress on water quantity (at low flow) and water quality (E. coli). To date, this model evaluation is based on a theoretical test that explores the logical implications of intensification at an unlikely extreme in order to assess the implications of likely growth trajectories from present use. While this has largely been a desktop exercise, it would also be possible to use this framework to model and explore the biophysical and economic impacts of individual or collective catchment visions. We are currently investigating the use of the model in this type of application.
Integrating Environmental and Socio-Economic Indicators of a Linked Catchment-Coastal System Using Variable Environmental Intensity

NASA Astrophysics Data System (ADS)

Dymond, John R.; Davie, Tim J. A.; Fenemor, Andrew D.; Ekanayake, Jagath C.; Knight, Ben R.; Cole, Anthony O.; de Oca Munguia, Oscar Montes; Allen, Will J.; Young, Roger G.; Basher, Les R.; Dresser, Marc; Batstone, Chris J.

2010-09-01

Can we develop land use policy that balances the conflicting views of stakeholders in a catchment while moving toward long term sustainability? Adaptive management provides a strategy for this whereby measures of catchment performance are compared against performance goals in order to progressively improve policy. However, the feedback loop of adaptive management is often slow and irreversible impacts may result before policy has been adapted. In contrast, integrated modelling of future land use policy provides rapid feedback and potentially improves the chance of avoiding unwanted collapse events. Replacing measures of catchment performance with modelled catchment performance has usually required the dynamic linking of many models, both biophysical and socio-economic—and this requires much effort in software development. As an alternative, we propose the use of variable environmental intensity (defined as the ratio of environmental impact over economic output) in a loose coupling of models to provide a sufficient level of integration while avoiding significant effort required for software development. This model construct was applied to the Motueka Catchment of New Zealand where several biophysical (riverine water quantity, sediment, E. coli faecal bacteria, trout numbers, nitrogen transport, marine productivity) models, a socio-economic (gross output, gross margin, job numbers) model, and an agent-based model were linked. An extreme set of land use scenarios (historic, present, and intensive) were applied to this modelling framework. Results suggest that the catchment is presently in a near optimal land use configuration that is unlikely to benefit from further intensification. This would quickly put stress on water quantity (at low flow) and water quality ( E. coli). To date, this model evaluation is based on a theoretical test that explores the logical implications of intensification at an unlikely extreme in order to assess the implications of likely growth trajectories from present use. While this has largely been a desktop exercise, it would also be possible to use this framework to model and explore the biophysical and economic impacts of individual or collective catchment visions. We are currently investigating the use of the model in this type of application.

[Prevention and multimodal therapy of hyperthyroidism].

PubMed

Palitzsch, K-D

2008-12-01

Subclinical and overt hyperthyroidism have been associated with various negative clinical outcomes as for example an increased risk of atrial fibrillation or increased cardiovascular mortality, especially in old age. In order to avoid hyperthyroidism it is strongly recommended not to start any iodine containing drug therapy or to avoid application of contrast agents unless the patient presents with an unremarkable clinical course. TSH suppressive therapy for the treatment of endemic goiter or differentiated low risk thyroid carcinoma is unnecessary, since it favours the development of subclinical hyperthyroidism. Overt hyperthyroidism is treated with antithyroid drugs and/or radioiodine therapy or surgery according to the underlying disease (toxic nodular goiter, Graves' disease).
Non-Contrast-Enhanced Renal Angiography Using Multiple Inversion Recovery and Alternating TR Balanced Steady State Free Precession

PubMed Central

Dong, Hattie Z.; Worters, Pauline W.; Wu, Holden H.; Ingle, R. Reeve; Vasanawala, Shreyas S.; Nishimura, Dwight G.

2014-01-01

Non-contrast enhanced renal angiography techniques based on balanced steady state free precession (SSFP) avoid external contrast agents, take advantage of high inherent blood signal from the T2/T1 contrast mechanism, and have short SSFP acquisition times. However, background suppression is limited; inflow times are inflexible; labeling region is difficult to define when tagging arterial flow; and scan times are long. To overcome these limitations, we propose the use of multiple inversion recovery (MIR) preparatory pulses combined with alternating TR balanced SSFP (ATR-SSFP) to produce renal angiograms. MIR uses selective spatial saturation followed by four global inversion recovery pulses to concurrently null a wide range of background T1 species while allowing for adjustable inflow times; ATR-SSFP maintains vessel contrast and provides added fat suppression. The high level of suppression enables imaging in 3D as well as projective 2D formats, the latter of which has a scan time down to one heartbeat. In vivo studies at 1.5 T demonstrate the superior vessel contrast of this technique. PMID:23172805
Reward and punishment act as distinct factors in guiding behavior

PubMed Central

Kubanek, Jan; Snyder, Lawrence H; Abrams, Richard A

2015-01-01

Behavior rests on the experience of reinforcement and punishment. It has been unclear whether reinforcement and punishment act as oppositely valenced components of a single behavioral factor, or whether these two kinds of outcomes play fundamentally distinct behavioral roles. To this end, we varied the magnitude of a reward or a penalty experienced following a choice using monetary tokens. The outcome of each trial was independent of the outcome of the previous trial, which enabled us to isolate and study the effect on behavior of each outcome magnitude in single trials. As expected, we found that a reward led to a repetition of the previous choice, whereas a penalty led to an avoidance of the previous choice. However, the effects of the reward magnitude and the penalty magnitude revealed a striking asymmetry. The choice repetition effect of a reward strongly scaled with the magnitude of the reward. In a marked contrast, the avoidance effect of a penalty was flat, not influenced by the magnitude of the penalty. These effects were mechanistically described using the Reinforcement Learning model after the model was updated to account for the penalty-based asymmetry. The asymmetry in the effects of the reward magnitude and the punishment magnitude was so striking that it is diffcult to conceive that one factor is just a weighted or transformed form of the other factor. Instead, the data suggest that rewards and penalties are fundamentally distinct factors in governing behavior. PMID:25824862
Reconstruction de defauts a partir de donnees issues de capteurs a courants de foucault avec modele direct differentiel

NASA Astrophysics Data System (ADS)

Trillon, Adrien

Eddy current tomography can be employed to caracterize flaws in metal plates in steam generators of nuclear power plants. Our goal is to evaluate a map of the relative conductivity that represents the flaw. This nonlinear ill-posed problem is difficult to solve and a forward model is needed. First, we studied existing forward models to chose the one that is the most adapted to our case. Finite difference and finite element methods matched very good to our application. We adapted contrast source inversion (CSI) type methods to the chosen model and a new criterion was proposed. These methods are based on the minimization of the weighted errors of the model equations, coupling and observation. They allow an error on the equations. It appeared that reconstruction quality grows with the decay of the error on the coupling equation. We resorted to augmented Lagrangian techniques to constrain coupling equation and to avoid conditioning problems. In order to overcome the ill-posed character of the problem, prior information was introduced about the shape of the flaw and the values of the relative conductivity. Efficiency of the methods are illustrated with simulated flaws in 2D case.
Language use and stereotyping: the role of approach and avoidance motivation goals.

PubMed

Gil de Montes, Lorena; Ortiz, Garbiñe; Valencia, José F; Larrañaga, Maider; Agirrezabal, Arrate

2012-11-01

The use of more abstract language to describe expected behaviors as opposed to unexpected behaviors has traditionally been considered a way of stereotype maintenance. This tendency is known as linguistic expectancy bias. Two experiments examined the influence of approach and avoidance motivational orientations on the production of this linguistic expectancy bias. It was predicted that approach strategic orientation is likely to describe expectancy consistent behaviors at a higher level of linguistic abstraction than expectancy inconsistent behaviors. In contrast, avoidance strategic orientation is likely to describe both expectancy consistent behaviors and expectancy inconsistent behaviors at a lower level of linguistic abstraction, thus facilitating the disappearance of linguistic expectancy bias. Two experiments confirmed these expectations, using strategic orientation manipulations based either on communication goals or on motor action, and measuring linguistic abstraction either on forced-choice answer format or on free descriptions. Implications for the generalisation of linguistic expectancy bias are discussed.
Identification and reduction of image artifacts in non-contrast-enhanced velocity-selective peripheral angiography at 3T.

PubMed

Shin, Taehoon; Qin, Qin; Park, Jang-Yeon; Crawford, Robert S; Rajagopalan, Sanjay

2016-08-01

To identify and reduce image artifacts in non-contrast-enhanced velocity-selective (VS) magnetization-prepared peripheral MR angiography (MRA) at 3T. To avoid signal loss in the arteries, double and quadruple refocused VS excitation pulse sequences were designed that were robust to a wide range of B0 and B1 offset. To suppress stripe artifact and background signal variation, we successively applied two VS preparations with excitation profiles shifted by half the period of the stripes. VS-MRA using single, double, and quadruple refocused VS preparations was tested in healthy subjects and a patient. In the regions of large B0 and B1 offsets, arterial signal loss was yielded by single refocused VS preparation, but was avoided with double or quadruple refocused preparations. Compared with single VS preparation, the two consecutive preparations with shifted excitation profiles substantially reduced the stripe artifact and background signal variation, as demonstrated by increased mean and decreased standard deviation of relative contrast-to-noise ratio. The proposed VS-MRA identified multilevel disease in the femoral arteries of the patient, as validated by digital subtraction angiography. Two multiple refocused VS magnetization preparations with shifted excitation profiles yield artifact-free peripheral angiograms at 3T. Magn Reson Med 76:466-477, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.
Hawaiian Nonverbal Communication: Two Classroom Applications.

ERIC Educational Resources Information Center

Anthony, Alberta Pualani

Although there are only about 2,000 active speakers of the Hawaiian language, there exists a coherent system of nonverbal behavior which can be identified as Hawaiian and which contrasts sharply with middle class white American behavior. Teachers of Hawaiian children should be aware of this in order to avoid potential misunderstandings in the…
Keep Calm and Contracept! Addressing Young Women's Pleasure in Sexual Health and Contraception Consultations

ERIC Educational Resources Information Center

Hanbury, Ali; Eastham, Rachael

2016-01-01

Clinical sexual health consultations with young women often focus on avoiding "risks;" namely pregnancy and sexually transmitted infection transmission. They also typically fail to explore how contraception use can impact on the capacity to enjoy sexual relationships. In contrast, this paper argues that sexual pleasure should be a…
The Changing Influence of Educational Policy and Race on Metropolitan Inequality, 1970-2010

ERIC Educational Resources Information Center

Johnson, Odis, Jr.

2017-01-01

Schools do not receive much recognition within urban sociological research for the role they perform in shaping the demographic, structural, and social features of neighborhoods, cities, and metropolitan areas. In contrast, this article links schools, and the racial avoidance that operates through educational policy, to the extreme economic…
Embracing Excellence: A Positive Approach to Ethical Decision Making

ERIC Educational Resources Information Center

Hinz, Lisa D.

2011-01-01

Ethics courses may provoke fear and uncertainty in art therapy students and practitioners if taught from a risk management perspective, which focuses on reducing therapist exposure to risk and avoiding harm to clients. In contrast, a positive ethical approach fosters empowerment, embraces limits, and enhances trust between art therapists and their…
Different Futures of Adaptive Collaborative Learning Support

ERIC Educational Resources Information Center

Rummel, Nikol; Walker, Erin; Aleven, Vincent

2016-01-01

In this position paper we contrast a Dystopian view of the future of adaptive collaborative learning support (ACLS) with a Utopian scenario that--due to better-designed technology, grounded in research--avoids the pitfalls of the Dystopian version and paints a positive picture of the practice of computer-supported collaborative learning 25 years…
Observations on School District and Service Consolidation in Michigan. Working Paper #17

ERIC Educational Resources Information Center

Arsen, David

2011-01-01

School district consolidation enjoys a unique status among strategies to reduce education costs. It promises to cut spending, without lowering service quality, by improving the efficiency of service delivery. In contrast to strategies aimed at lowering employee salaries or benefits--which are hard to avoid when cutting spending in any labor…
Sexual Stigma, Coping Styles, and Psychological Distress: A Longitudinal Study of Men Who Have Sex with Men in Beijing, China

PubMed Central

Choi, Kyung-Hee; Steward, Wayne T.; Miège, Pierre; Hudes, Esther; Gregorich, Steven E.

2015-01-01

The direct link between stigma against sexual minorities and psychological distress is well established. However, few studies have examined the potential mediating roles of avoidant and social support coping in the relationships between internalized and anticipated stigma associated with homosexuality and depressive symptoms and anxiety among Chinese men who have sex with men (MSM). We recruited a longitudinal sample of 493 MSM in Beijing, China from 2011 to 2012. Participants completed computer-based questionnaires at baseline, 6 months, and 12 months. We found significant indirect effects of anticipated MSM stigma on symptoms of both depression and anxiety via avoidant coping: anticipated MSM stigma at baseline was significantly associated with avoidant coping (B = 0.523, p < 0.001) at 6 months and, conditional on anticipated MSM stigma, avoidant coping had a significant positive effect on depressive symptoms and anxiety at 12 months (B = 0.069, p = 0.001 and B=0.071, p=0.014). In contrast, no significant indirect effects of anticipated MSM stigma on either psychological distress outcome via social support coping were found. No significant indirect effects of internalized MSM stigma via either avoidant or social support coping were found. These results underscore the need for interventions that address anticipations of stigma and the use of avoidant coping techniques to manage such anticipations. PMID:26679303
Sexual Stigma, Coping Styles, and Psychological Distress: A Longitudinal Study of Men Who Have Sex With Men in Beijing, China.

PubMed

Choi, Kyung-Hee; Steward, Wayne T; Miège, Pierre; Hudes, Esther; Gregorich, Steven E

2016-08-01

The direct link between stigma against sexual minorities and psychological distress is well established. However, few studies have examined the potential mediating roles of avoidant and social support coping in the relationships between internalized and anticipated stigma associated with homosexuality and depressive symptoms and anxiety among Chinese men who have sex with men (MSM). We recruited a longitudinal sample of 493 MSM in Beijing, China from 2011 to 2012. Participants completed computer-based questionnaires at baseline, 6, and 12 months. We found significant indirect effects of anticipated MSM stigma on symptoms of both depression and anxiety via avoidant coping: anticipated MSM stigma at baseline was significantly associated with avoidant coping (B = 0.523, p < 0.001) at 6 months and, conditional on anticipated MSM stigma, avoidant coping had a significant positive effect on depressive symptoms and anxiety at 12 months (B = 0.069, p = 0.001 and B = 0.071, p = 0.014). In contrast, no significant indirect effects of anticipated MSM stigma on either psychological distress outcome via social support coping were found. No significant indirect effects of internalized MSM stigma via either avoidant or social support coping were found. These results underscore the need for interventions that address anticipations of stigma and the use of avoidant coping techniques to manage such anticipations.
Modeling Avoidance in Mood and Anxiety Disorders Using Reinforcement Learning.

PubMed

Mkrtchian, Anahit; Aylward, Jessica; Dayan, Peter; Roiser, Jonathan P; Robinson, Oliver J

2017-10-01

Serious and debilitating symptoms of anxiety are the most common mental health problem worldwide, accounting for around 5% of all adult years lived with disability in the developed world. Avoidance behavior-avoiding social situations for fear of embarrassment, for instance-is a core feature of such anxiety. However, as for many other psychiatric symptoms the biological mechanisms underlying avoidance remain unclear. Reinforcement learning models provide formal and testable characterizations of the mechanisms of decision making; here, we examine avoidance in these terms. A total of 101 healthy participants and individuals with mood and anxiety disorders completed an approach-avoidance go/no-go task under stress induced by threat of unpredictable shock. We show an increased reliance in the mood and anxiety group on a parameter of our reinforcement learning model that characterizes a prepotent (pavlovian) bias to withhold responding in the face of negative outcomes. This was particularly the case when the mood and anxiety group was under stress. This formal description of avoidance within the reinforcement learning framework provides a new means of linking clinical symptoms with biophysically plausible models of neural circuitry and, as such, takes us closer to a mechanistic understanding of mood and anxiety disorders. Copyright © 2017 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
Assessing the ability of operational snow models to predict snowmelt runoff extremes (Invited)

NASA Astrophysics Data System (ADS)

Wood, A. W.; Restrepo, P. J.; Clark, M. P.

2013-12-01

In the western US, the snow accumulation and melt cycle of winter and spring plays a critical role in the region's water management strategies. Consequently, the ability to predict snowmelt runoff at time scales from days to seasons is a key input for decisions in reservoir management, whether for avoiding flood hazards or supporting environmental flows through the scheduling of releases in spring, or for allocating releases for multi-state water distribution in dry seasons of year (using reservoir systems to provide an invaluable buffer for many sectors against drought). Runoff forecasts thus have important benefits at both wet and dry extremes of the climatological spectrum. The importance of the prediction of the snow cycle motivates an assessment of the strengths and weaknesses of the US's central operational snow model, SNOW17, in contrast to process-modeling alternatives, as they relate to simulating observed snowmelt variability and extremes. To this end, we use a flexible modeling approach that enables an investigation of different choices in model structure, including model physics, parameterization and degree of spatiotemporal discretization. We draw from examples of recent extreme events in western US watersheds and an overall assessment of retrospective model performance to identify fruitful avenues for advancing the modeling basis for the operational prediction of snow-related runoff extremes.
Aversive Learning and Appetitive Motivation Toggle Feed-Forward Inhibition in the Drosophila Mushroom Body.

PubMed

Perisse, Emmanuel; Owald, David; Barnstedt, Oliver; Talbot, Clifford B; Huetteroth, Wolf; Waddell, Scott

2016-06-01

In Drosophila, negatively reinforcing dopaminergic neurons also provide the inhibitory control of satiety over appetitive memory expression. Here we show that aversive learning causes a persistent depression of the conditioned odor drive to two downstream feed-forward inhibitory GABAergic interneurons of the mushroom body, called MVP2, or mushroom body output neuron (MBON)-γ1pedc>α/β. However, MVP2 neuron output is only essential for expression of short-term aversive memory. Stimulating MVP2 neurons preferentially inhibits the odor-evoked activity of avoidance-directing MBONs and odor-driven avoidance behavior, whereas their inhibition enhances odor avoidance. In contrast, odor-evoked activity of MVP2 neurons is elevated in hungry flies, and their feed-forward inhibition is required for expression of appetitive memory at all times. Moreover, imposing MVP2 activity promotes inappropriate appetitive memory expression in food-satiated flies. Aversive learning and appetitive motivation therefore toggle alternate modes of a common feed-forward inhibitory MVP2 pathway to promote conditioned odor avoidance or approach. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.
How do walkers behave when crossing the way of a mobile robot that replicates human interaction rules?

PubMed

Vassallo, Christian; Olivier, Anne-Hélène; Souères, Philippe; Crétual, Armel; Stasse, Olivier; Pettré, Julien

2018-02-01

Previous studies showed the existence of implicit interaction rules shared by human walkers when crossing each other. Especially, each walker contributes to the collision avoidance task and the crossing order, as set at the beginning, is preserved along the interaction. This order determines the adaptation strategy: the first arrived increases his/her advance by slightly accelerating and changing his/her heading, whereas the second one slows down and moves in the opposite direction. In this study, we analyzed the behavior of human walkers crossing the trajectory of a mobile robot that was programmed to reproduce this human avoidance strategy. In contrast with a previous study, which showed that humans mostly prefer to give the way to a non-reactive robot, we observed similar behaviors between human-human avoidance and human-robot avoidance when the robot replicates the human interaction rules. We discuss this result in relation with the importance of controlling robots in a human-like way in order to ease their cohabitation with humans. Copyright © 2017 Elsevier B.V. All rights reserved.
Young Men's Aggressive Tactics to Avoid Condom Use: A Test of a Theoretical Model

ERIC Educational Resources Information Center

Davis, Kelly Cue; Logan-Greene, Patricia

2012-01-01

Although research has demonstrated that men's aggression against women and inconsistent condom use are related phenomena, little is known about what factors increase risk for aggression to avoid condom use. The present article tests a theory-based model of condom avoidance through use of sexual aggression. Adult male participants (N = 289) were…
Low Back Pain Subgroups using Fear-Avoidance Model Measures: Results of a Cluster Analysis

PubMed Central

Beneciuk, Jason M.; Robinson, Michael E.; George, Steven Z.

2012-01-01

Objectives The purpose of this secondary analysis was to test the hypothesis that an empirically derived psychological subgrouping scheme based on multiple Fear-Avoidance Model (FAM) constructs would provide additional capabilities for clinical outcomes in comparison to a single FAM construct. Methods Patients (n = 108) with acute or sub-acute low back pain (LBP) enrolled in a clinical trial comparing behavioral physical therapy interventions to classification based physical therapy completed baseline questionnaires for pain catastrophizing (PCS), fear-avoidance beliefs (FABQ-PA, FABQ-W), and patient-specific fear (FDAQ). Clinical outcomes were pain intensity and disability measured at baseline, 4-weeks, and 6-months. A hierarchical agglomerative cluster analysis was used to create distinct cluster profiles among FAM measures and discriminant analysis was used to interpret clusters. Changes in clinical outcomes were investigated with repeated measures ANOVA and differences in results based on cluster membership were compared to FABQ-PA subgrouping used in the original trial. Results Three distinct FAM subgroups (Low Risk, High Specific Fear, and High Fear & Catastrophizing) emerged from cluster analysis. Subgroups differed on baseline pain and disability (p’s<.01) with the High Fear & Catastrophizing subgroup associated with greater pain than the Low Risk subgroup (p<.01) and the greatest disability (p’s<.05). Subgroup × time interactions were detected for both pain and disability (p’s<.05) with the High Fear & Catastrophizing subgroup reporting greater changes in pain and disability than other subgroups (p’s<.05). In contrast, FABQ-PA subgroups used in the original trial were not associated with interactions for clinical outcomes. Discussion These data suggest that subgrouping based on multiple FAM measures may provide additional information on clinical outcomes in comparison to determining subgroup status by FABQ-PA alone. Subgrouping methods for patients with LBP should include multiple psychological factors to further explore if patients can be matched with appropriate interventions. PMID:22510537

Modeling and Simulation of an UAS Collision Avoidance Systems

NASA Technical Reports Server (NTRS)

Oliveros, Edgardo V.; Murray, A. Jennifer

2010-01-01

This paper describes a Modeling and Simulation of an Unmanned Aircraft Systems (UAS) Collision Avoidance System, capable of representing different types of scenarios for UAS collision avoidance. Commercial and military piloted aircraft currently utilize various systems for collision avoidance such as Traffic Alert and Collision A voidance System (TCAS), Automatic Dependent Surveillance-Broadcast (ADS-B), Radar and ElectroOptical and Infrared Sensors (EO-IR). The integration of information from these systems is done by the pilot in the aircraft to determine the best course of action. In order to operate optimally in the National Airspace System (NAS) UAS have to work in a similar or equivalent manner to a piloted aircraft by applying the principle of "detect-see and avoid" (DSA) to other air traffic. Hence, we have taken these existing sensor technologies into consideration in order to meet the challenge of researching the modeling and simulation of an approximated DSA system. A Schematic Model for a UAS Collision Avoidance System (CAS) has been developed ina closed loop block diagram for that purpose. We have found that the most suitable software to carry out this task is the Satellite Tool Kit (STK) from Analytical Graphics Inc. (AGI). We have used the Aircraft Mission Modeler (AMM) for modeling and simulation of a scenario where a UAS is placed on a possible collision path with an initial intruder and then with a second intruder, but is able to avoid them by executing a right tum maneuver and then climbing. Radars have also been modeled with specific characteristics for the UAS and both intruders. The software provides analytical, graphical user interfaces and data controlling tools which allow the operator to simulate different conditions. Extensive simulations have been carried out which returned excellent results.
Two-stage stochastic unit commitment model including non-generation resources with conditional value-at-risk constraints

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

Huang, Yuping; Zheng, Qipeng P.; Wang, Jianhui

2014-11-01

tThis paper presents a two-stage stochastic unit commitment (UC) model, which integrates non-generation resources such as demand response (DR) and energy storage (ES) while including riskconstraints to balance between cost and system reliability due to the fluctuation of variable genera-tion such as wind and solar power. This paper uses conditional value-at-risk (CVaR) measures to modelrisks associated with the decisions in a stochastic environment. In contrast to chance-constrained modelsrequiring extra binary variables, risk constraints based on CVaR only involve linear constraints and con-tinuous variables, making it more computationally attractive. The proposed models with risk constraintsare able to avoid over-conservative solutions butmore » still ensure system reliability represented by loss ofloads. Then numerical experiments are conducted to study the effects of non-generation resources ongenerator schedules and the difference of total expected generation costs with risk consideration. Sen-sitivity analysis based on reliability parameters is also performed to test the decision preferences ofconfidence levels and load-shedding loss allowances on generation cost reduction.« less
Prediction versus aetiology: common pitfalls and how to avoid them.

PubMed

van Diepen, Merel; Ramspek, Chava L; Jager, Kitty J; Zoccali, Carmine; Dekker, Friedo W

2017-04-01

Prediction research is a distinct field of epidemiologic research, which should be clearly separated from aetiological research. Both prediction and aetiology make use of multivariable modelling, but the underlying research aim and interpretation of results are very different. Aetiology aims at uncovering the causal effect of a specific risk factor on an outcome, adjusting for confounding factors that are selected based on pre-existing knowledge of causal relations. In contrast, prediction aims at accurately predicting the risk of an outcome using multiple predictors collectively, where the final prediction model is usually based on statistically significant, but not necessarily causal, associations in the data at hand.In both scientific and clinical practice, however, the two are often confused, resulting in poor-quality publications with limited interpretability and applicability. A major problem is the frequently encountered aetiological interpretation of prediction results, where individual variables in a prediction model are attributed causal meaning. This article stresses the differences in use and interpretation of aetiological and prediction studies, and gives examples of common pitfalls. © The Author 2017. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.
Contrast-enhanced spectral mammography: Does mammography provide additional clinical benefits or can some radiation exposure be avoided?

PubMed

Fallenberg, Eva Maria; Dromain, Clarisse; Diekmann, Felix; Renz, Diane M; Amer, Heba; Ingold-Heppner, Barbara; Neumann, Avidan U; Winzer, Klaus J; Bick, Ulrich; Hamm, Bernd; Engelken, Florian

2014-07-01

The purpose of this study was to compare contrast-enhanced spectral mammography (CESM) with mammography (MG) and combined CESM + MG in terms of detection and size estimation of histologically proven breast cancers in order to assess the potential to reduce radiation exposure. A total of 118 patients underwent MG and CESM and had final histological results. CESM was performed as a bilateral examination starting 2 min after injection of iodinated contrast medium. Three independent blinded radiologists read the CESM, MG, and CESM + MG images with an interval of at least 4 weeks to avoid case memorization. Sensitivity and size measurement correlation and differences were calculated, average glandular dose (AGD) levels were compared, and breast densities were reported. Fisher's exact and Wilcoxon tests were performed. A total of 107 imaging pairs were available for analysis. Densities were ACR1: 2, ACR2: 45, ACR3: 42, and ACR4: 18. Mean AGD was 1.89 mGy for CESM alone, 1.78 mGy for MG, and 3.67 mGy for the combination. In very dense breasts, AGD of CESM was significantly lower than MG. Sensitivity across readers was 77.9 % for MG alone, 94.7 % for CESM, and 95 % for CESM + MG. Average tumor size measurement error compared to postsurgical pathology was -0.6 mm for MG, +0.6 mm for CESM, and +4.5 mm for CESM + MG (p < 0.001 for CESM + MG vs. both modalities). CESM alone has the same sensitivity and better size assessment as CESM + MG and was significantly better than MG with only 6.2 % increase in AGD. The combination of CESM + MG led to systematic size overestimation. When a CESM examination is planned, additional MG can be avoided, with the possibility of saving up to 61 % of radiation dose, especially in patients with dense breasts.
Life as an Ex-Physicist on Wall Street

NASA Astrophysics Data System (ADS)

Derman, Emanuel

2001-06-01

Financial theory looks deceptively like physics because of the techniques it uses. But physics models deal with the relatively unchanging parameters of the external world; in contrast, the parameters of financial theory are people's current estimates of, and sentiments about, future behavior. Life as a Ph.D. on Wall St is therefore very different from the way most people in academic life imagine it to be. For most of us, most of the time, it involves neither finding miraculous and previously undiscovered arbitrages, nor doing boring mindless programming. Instead, it demands an interdisciplinary mix of inventive computation, applied mathematics, financial understanding, self-education and educating others, applied in a hectic environment, to help build and maintain a business. Financial modeling as a practitioner means suffering many interruptions when you want to think quietly, and making many pragmatic compromises dictated by constraints on time and resources. It also means a stimulating and lively environment, using your imagination, avoiding complexity, and always trying to bridge the gap between analysis and intuition (yours and others).
Improved identification of cranial nerves using paired-agent imaging: topical staining protocol optimization through experimentation and simulation

NASA Astrophysics Data System (ADS)

Torres, Veronica C.; Wilson, Todd; Staneviciute, Austeja; Byrne, Richard W.; Tichauer, Kenneth M.

2018-03-01

Skull base tumors are particularly difficult to visualize and access for surgeons because of the crowded environment and close proximity of vital structures, such as cranial nerves. As a result, accidental nerve damage is a significant concern and the likelihood of tumor recurrence is increased because of more conservative resections that attempt to avoid injuring these structures. In this study, a paired-agent imaging method with direct administration of fluorophores is applied to enhance cranial nerve identification. Here, a control imaging agent (ICG) accounts for non-specific uptake of the nerve-targeting agent (Oxazine 4), and ratiometric data analysis is employed to approximate binding potential (BP, a surrogate of targeted biomolecule concentration). For clinical relevance, animal experiments and simulations were conducted to identify parameters for an optimized stain and rinse protocol using the developed paired-agent method. Numerical methods were used to model the diffusive and kinetic behavior of the imaging agents in tissue, and simulation results revealed that there are various combinations of stain time and rinse number that provide improved contrast of cranial nerves, as suggested by optimal measures of BP and contrast-to-noise ratio.
The reluctant innovator: orangutans and the phylogeny of creativity

PubMed Central

van Schaik, C. P.; Burkart, J.; Damerius, L.; Forss, S. I. F.; Koops, K.; van Noordwijk, M. A.; Schuppli, C.

2016-01-01

Young orangutans are highly neophobic, avoid independent exploration and show a preference for social learning. Accordingly, they acquire virtually all their learned skills through exploration that is socially induced. Adult exploration rates are also low. Comparisons strongly suggest that major innovations, i.e. behaviours that have originally been brought into the population through individual invention, are made where ecological opportunities to do so are propitious. Most populations nonetheless have large innovation repertoires, because innovations, once made, are retained well through social transmission. Wild orangutans are therefore not innovative. In striking contrast, zoo-living orangutans actively seek novelty and are highly exploratory and innovative, probably because of positive reinforcement, active encouragement by human role models, increased sociality and an expectation of safety. The explanation for this contrast most relevant to hominin evolution is that captive apes generally have a highly reduced cognitive load, in particular owing to the absence of predation risk, which strongly reduces the costs of exploration. If the orangutan results generalize to other great apes, this suggests that our ancestors could have become more curious once they had achieved near-immunity to predation on the eve of the explosive increase in creativity characterizing the Upper Palaeolithic Revolution. PMID:26926274
The Multivariate Structure of Communication Avoidance.

ERIC Educational Resources Information Center

Bell, Robert A.

1986-01-01

Clarifies the nature of communication avoidance through a structural analysis grounded in facet theory. Presents evidence for a duplex model of avoidance in which theoretical distinctions among modalities of approach-avoidance and context proved empirically relevant. Discusses implications of these findings for the explication, treatment, and…
The relative effectiveness of managed care penetration and the healthcare safety net in reducing avoidable hospitalizations.

PubMed

Pracht, Etienne E; Orban, Barbara L; Comins, Meg M; Large, John T; Asin-Oostburg, Virginia

2011-01-01

Avoidable hospitalizations represent a key indicator for access to, and the quality of, primary care. Therefore, understanding their behavior is essential in terms of management of healthcare resources and costs. This analysis examines the affect of 2 healthcare strategies on the rate of avoidable hospitalization, managed care and the healthcare safety net. The avoidable hospitalizations definition developed by Weissman et al. (1992) was used to identify relevant inpatient episodes. A 2-stage simultaneous equations multivariate regression model with instrumental variables was used to estimate the relative influence of HMO penetration and the composition of local hospital markets on the rate of avoidable hospitalizations. Control variables in the model include healthcare supply and demand, demographic, socioeconomic, and health status characteristics. Increased market presence of public hospitals significantly reduced avoidable hospitalizations. HMO penetration did not influence the rate of avoidable hospitalizations. The results suggest that public investments in healthcare facilities and infrastructure are more effective in reducing avoidable hospitalizations. © 2011 National Association for Healthcare Quality.
Dispositional and Situational Avoidance and Approach as Predictors of Physical Symptom Bother Following Breast Cancer Diagnosis

PubMed Central

Bauer, Margaret R.; Harris, Lauren N.; Wiley, Joshua F.; Crespi, Catherine M.; Krull, Jennifer L.; Weihs, Karen L.; Stanton, Annette L.

2016-01-01

Background Few studies examine whether dispositional approach and avoidance coping and stressor-specific coping strategies differentially predict physical adjustment to cancer-related stress. Purpose This study examines dispositional and situational avoidance and approach coping as unique predictors of the bother women experience from physical symptoms after breast cancer treatment, as well as whether situational coping mediates the prediction of bother from physical symptoms by dispositional coping. Method Breast cancer patients (N=460) diagnosed within the past 3 months completed self-report measures of dispositional coping at study entry and of situational coping and bother from physical symptoms every 6 weeks through 6 months. Results In multilevel structural equation modeling analyses, both dispositional and situational avoidance predict greater symptom bother. Dispositional, but not situational, approach predicts less symptom bother. Supporting mediation models, dispositional avoidance predicts more symptom bother indirectly through greater situational avoidance. Dispositional approach predicts less symptom bother through less situational avoidance. Conclusion Psychosocial interventions to reduce cancer-related avoidance coping are warranted for cancer survivors who are high in dispositional avoidance and/or low in dispositional approach. PMID:26769023
Dispositional and Situational Avoidance and Approach as Predictors of Physical Symptom Bother Following Breast Cancer Diagnosis.

PubMed

Bauer, Margaret R; Harris, Lauren N; Wiley, Joshua F; Crespi, Catherine M; Krull, Jennifer L; Weihs, Karen L; Stanton, Annette L

2016-06-01

Few studies examine whether dispositional approach and avoidance coping and stressor-specific coping strategies differentially predict physical adjustment to cancer-related stress. This study examines dispositional and situational avoidance and approach coping as unique predictors of the bother women experience from physical symptoms after breast cancer treatment, as well as whether situational coping mediates the prediction of bother from physical symptoms by dispositional coping. Breast cancer patients (N = 460) diagnosed within the past 3 months completed self-report measures of dispositional coping at study entry and of situational coping and bother from physical symptoms every 6 weeks through 6 months. In multilevel structural equation modeling analyses, both dispositional and situational avoidance predict greater symptom bother. Dispositional, but not situational, approach predicts less symptom bother. Supporting mediation models, dispositional avoidance predicts more symptom bother indirectly through greater situational avoidance. Dispositional approach predicts less symptom bother through less situational avoidance. Psychosocial interventions to reduce cancer-related avoidance coping are warranted for cancer survivors who are high in dispositional avoidance and/or low in dispositional approach.
Cannabinoids increase conditioned ultrasonic vocalisations and cat odour avoidance in rats: strain differences in drug-induced anxiety.

PubMed

Arnold, Jonathon C; Dielenberg, Robert A; McGregor, Iain S

2010-10-23

Genetic disposition modulates the psychoactive effects of cannabis. Cannabinoids have a greater impact on brain regions that subserve anxiety in Wistar compared to Lewis strain rats. Here we aim to show that this correlates with strain differences in cannabinoid-induced anxiety-related behaviour. Lewis and Wistar rats were administered vehicle or the synthetic cannabinoid receptor agonist, CP 55,940 (10, 25 and 50μg/kg) before testing in the conditioned ultrasonic vocalization (USV), cat odour avoidance or open area avoidance models. Animals were placed in a chamber in which they had previously received footshock. Wistar but not Lewis rats re-exposed under the influence of all CP 55,940 doses emitted significantly more USVs than vehicle-treated rats. In the cat odour avoidance model, rats were exposed to cat odour and given the opportunity to hide in a small box. In Wistar but not Lewis rats, 50μg/kg of CP 55,940 magnified hiding behaviour promoted by cat odour exposure. Animals were also tested in the open area avoidance model which occurred in the same arena as the predatory avoidance model but without cat odour. In Wistar, but not Lewis rats, 25 and 50μg/kg of CP 55,940 increased the avoidance of the open space. CP 55,940 increased anxiety-related behaviour in Wistar rats but not Lewis rats providing a model to dissect the genetic basis of cannabinoid-induced anxiety. We show for the first time that cannabinoids magnify conditioned USVs and cat odour avoidance behaviour dependent on the strain being tested. Crown Copyright © 2010. Published by Elsevier Inc. All rights reserved.
Influence of conspecific and heterospecific aggregation cues and alarm odors on shelter choice by syntopic spiny lobsters.

PubMed

Briones-Fourzán, Patricia; Ramírez-Zaldívar, Eunice; Lozano-Alvarez, Enrique

2008-10-01

In spiny lobsters, conspecific scents ("aggregation cues") may mediate gregarious diurnal sheltering, but scents from injured conspecifics ("alarm odors") may elicit avoidance behavior. In laboratory experiments, individuals of two coexisting species, Panulirus guttatus (a reef-obligate) and P. argus (a temporary reef-dweller), significantly chose shelters emanating conspecific aggregation cues and responded randomly to shelters emanating heterospecific aggregation cues. However, despite evidence that the two species perceived each other's alarm odors to a similar extent, P. guttatus responded randomly to shelters emanating either conspecific or heterospecific alarm odors, whereas P. argus significantly avoided both. This differential influence of alarm odors likely reflects interspecific differences in life history, sociality, and behavior. The less social, reef-obligate P. guttatus lobsters forage close to their reef dens, into which they retract deeply upon perception of risk. This cryptic behavior may offset the need to avoid conspecific (and heterospecific) alarm odors. In contrast, avoidance of conspecific alarm odors by P. argus is consistent with its ontogenetic habitat shifts and greater sociality. Furthermore, because reef-dwelling P. argus lobsters forage across open areas away from the reef, an ability to avoid alarm odors from P. guttatus upon returning to their reef dens may increase their fitness.
Evolution of precopulatory and post-copulatory strategies of inbreeding avoidance and associated polyandry.

PubMed

Duthie, A B; Bocedi, G; Germain, R R; Reid, J M

2018-01-01

Inbreeding depression is widely hypothesized to drive adaptive evolution of precopulatory and post-copulatory mechanisms of inbreeding avoidance, which in turn are hypothesized to affect evolution of polyandry (i.e. female multiple mating). However, surprisingly little theory or modelling critically examines selection for precopulatory or post-copulatory inbreeding avoidance, or both strategies, given evolutionary constraints and direct costs, or examines how evolution of inbreeding avoidance strategies might feed back to affect evolution of polyandry. Selection for post-copulatory inbreeding avoidance, but not for precopulatory inbreeding avoidance, requires polyandry, whereas interactions between precopulatory and post-copulatory inbreeding avoidance might cause functional redundancy (i.e. 'degeneracy') potentially generating complex evolutionary dynamics among inbreeding strategies and polyandry. We used individual-based modelling to quantify evolution of interacting precopulatory and post-copulatory inbreeding avoidance and associated polyandry given strong inbreeding depression and different evolutionary constraints and direct costs. We found that evolution of post-copulatory inbreeding avoidance increased selection for initially rare polyandry and that evolution of a costly inbreeding avoidance strategy became negligible over time given a lower-cost alternative strategy. Further, fixed precopulatory inbreeding avoidance often completely precluded evolution of polyandry and hence post-copulatory inbreeding avoidance, but fixed post-copulatory inbreeding avoidance did not preclude evolution of precopulatory inbreeding avoidance. Evolution of inbreeding avoidance phenotypes and associated polyandry is therefore affected by evolutionary feedbacks and degeneracy. All else being equal, evolution of precopulatory inbreeding avoidance and resulting low polyandry is more likely when post-copulatory inbreeding avoidance is precluded or costly, and evolution of post-copulatory inbreeding avoidance greatly facilitates evolution of costly polyandry. © The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology.
The dense core vesicle protein IA-2, but not IA-2β, is required for active avoidance learning.

PubMed

Carmona, G N; Nishimura, T; Schindler, C W; Panlilio, L V; Notkins, A L

2014-06-06

The islet-antigens IA-2 and IA-2β are major autoantigens in type-1 diabetes and transmembrane proteins in dense core vesicles (DCV). Recently we showed that deletion of both IA-2 and IA-2β alters the secretion of hormones and neurotransmitters and impairs behavior and learning. The present study was designed to evaluate the contribution to learning of each of these genes by using single knockout (SKO) and double knockout (DKO) mice in an active avoidance test. After 5 days of training, wild-type (WT) mice showed 60-70% active avoidance responses, whereas the DKO mice showed only 10-15% active avoidance responses. The degree of active avoidance responses in the IA-2 SKO mice was similar to that of the DKO mice, but in contrast, the IA-2β SKO mice behaved like WT mice showing 60-70% active avoidance responses. Molecular studies revealed a marked decrease in the phosphorylation of the cAMP response element-binding protein (CREB) and Ca(2+)/calmodulin-dependent protein kinase II (CAMKII) in the striatum and hippocampus of the IA-2 SKO and DKO mice, but not in the IA-2β SKO mice. To evaluate the role of CREB and CAMKII in the SKO and DKO mice, GBR-12909, which selectively blocks the dopamine uptake transporter and increases CREB and CAMKII phosphorylation, was administered. GBR-12909 restored the phosphorylation of CREB and CAMKII and increased active avoidance learning in the DKO and IA-2 SKO to near the normal levels found in the WT and IA-2β SKO mice. We conclude that in the absence of the DCV protein IA-2, active avoidance learning is impaired. Published by Elsevier Ltd.
A study on model fidelity for model predictive control-based obstacle avoidance in high-speed autonomous ground vehicles

NASA Astrophysics Data System (ADS)

Liu, Jiechao; Jayakumar, Paramsothy; Stein, Jeffrey L.; Ersal, Tulga

2016-11-01

This paper investigates the level of model fidelity needed in order for a model predictive control (MPC)-based obstacle avoidance algorithm to be able to safely and quickly avoid obstacles even when the vehicle is close to its dynamic limits. The context of this work is large autonomous ground vehicles that manoeuvre at high speed within unknown, unstructured, flat environments and have significant vehicle dynamics-related constraints. Five different representations of vehicle dynamics models are considered: four variations of the two degrees-of-freedom (DoF) representation as lower fidelity models and a fourteen DoF representation with combined-slip Magic Formula tyre model as a higher fidelity model. It is concluded that the two DoF representation that accounts for tyre nonlinearities and longitudinal load transfer is necessary for the MPC-based obstacle avoidance algorithm in order to operate the vehicle at its limits within an environment that includes large obstacles. For less challenging environments, however, the two DoF representation with linear tyre model and constant axle loads is sufficient.
Effect of 'chronic' versus 'acute' ketamine administration and its 'withdrawal' effect on behavioural alterations in mice: implications for experimental psychosis.

PubMed

Chatterjee, Manavi; Ganguly, Surajit; Srivastava, Mukesh; Palit, Gautam

2011-01-01

Lack of appropriate animal models simulating core behavioural aspects of human psychosis is a major limitation in schizophrenia research. The use of drugs, that is believed to act through N-methyl d-aspartate receptor, has been demonstrated to mimic relatively broader range of behavioural symptoms in putative animal models. Our goal in this study has been to further evaluate one such drug, ketamine in mice and characterize some selective behavioural phenotypes associated with the drug dosage, treatment period and withdrawal effects to extend the understanding of this model. Our results indicate that acute treatment of ketamine (100 mg/kg, i.p.) induced hyperlocomotory response and reduced the 'transfer-latency time' in passive avoidance test but did not have any effect in the forced swim test (negative symptoms). In contrast, chronic administration of ketamine not only produced significant 'hyperactivity' response but also enhanced the immobility period in animals during the forced swim test and reduced the latency period in the passive avoidance test. Further, these behavioural alterations persisted at least for 10 days after the withdrawal of ketamine treatment. These observations were substantiated by using standard typical and atypical antipsychotic drugs, haloperidol (0.25 mg/kg, i.p.), clozapine (10 mg/kg, i.p.) and risperidone (0.025 mg/kg, i.p.). Therefore, the present study suggests that the chronic treatment with ketamine has the potential of exhibiting changes in broader range of behavioural domains than the acute treatment. Hence, animals chronically treated with ketamine might serve as a useful tool to study the underlying pathogenic mechanisms associated with some symptoms in schizophrenia and other psychiatric disorders. Copyright © 2010 Elsevier B.V. All rights reserved.
Leaf mass per area is independent of vein length per area: avoiding pitfalls when modelling phenotypic integration (reply to Blonder et al. 2014).

PubMed

Sack, Lawren; Scoffoni, Christine; John, Grace P; Poorter, Hendrik; Mason, Chase M; Mendez-Alonzo, Rodrigo; Donovan, Lisa A

2014-10-01

It has been recently proposed that leaf vein length per area (VLA) is the major determinant of leaf mass per area ( MA), and would thereby determine other traits of the leaf economic spectrum (LES), such as photosynthetic rate per mass (A(mass)), nitrogen concentration per mass (N(mass)) and leaf lifespan (LL). In a previous paper we argued that this 'vein origin' hypothesis was supported only by a mathematical model with predestined outcomes, and that we found no support for the 'vein origin' hypothesis in our analyses of compiled data. In contrast to the 'vein origin' hypothesis, empirical evidence indicated that VLA and LMA are independent mechanistically, and VLA (among other vein traits) contributes to a higher photosynthetic rate per area (A(area)), which scales up to driving a higher A(mass), all independently of LMA, N(mass) and LL. In their reply to our paper, Blonder et al. (2014) raised questions about our analysis of their model, but did not address our main point, that the data did not support their hypothesis. In this paper we provide further analysis of an extended data set, which again robustly demonstrates the mechanistic independence of LMA from VLA, and thus does not support the 'vein origin' hypothesis. We also address the four specific points raised by Blonder et al. (2014) regarding our analyses. We additionally show how this debate provides critical guidance for improved modelling of LES traits and other networks of phenotypic traits that determine plant performance under contrasting environments. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.
Peripheral Processing Facilitates Optic Flow-Based Depth Perception

PubMed Central

Li, Jinglin; Lindemann, Jens P.; Egelhaaf, Martin

2016-01-01

Flying insects, such as flies or bees, rely on consistent information regarding the depth structure of the environment when performing their flight maneuvers in cluttered natural environments. These behaviors include avoiding collisions, approaching targets or spatial navigation. Insects are thought to obtain depth information visually from the retinal image displacements (“optic flow”) during translational ego-motion. Optic flow in the insect visual system is processed by a mechanism that can be modeled by correlation-type elementary motion detectors (EMDs). However, it is still an open question how spatial information can be extracted reliably from the responses of the highly contrast- and pattern-dependent EMD responses, especially if the vast range of light intensities encountered in natural environments is taken into account. This question will be addressed here by systematically modeling the peripheral visual system of flies, including various adaptive mechanisms. Different model variants of the peripheral visual system were stimulated with image sequences that mimic the panoramic visual input during translational ego-motion in various natural environments, and the resulting peripheral signals were fed into an array of EMDs. We characterized the influence of each peripheral computational unit on the representation of spatial information in the EMD responses. Our model simulations reveal that information about the overall light level needs to be eliminated from the EMD input as is accomplished under light-adapted conditions in the insect peripheral visual system. The response characteristics of large monopolar cells (LMCs) resemble that of a band-pass filter, which reduces the contrast dependency of EMDs strongly, effectively enhancing the representation of the nearness of objects and, especially, of their contours. We furthermore show that local brightness adaptation of photoreceptors allows for spatial vision under a wide range of dynamic light conditions. PMID:27818631
The Economic Impact of Malignant Catarrhal Fever on Pastoralist Livelihoods

PubMed Central

Lankester, Felix; Lugelo, Ahmed; Kazwala, Rudovick; Keyyu, Julius; Cleaveland, Sarah; Yoder, Jonathan

2015-01-01

This study is the first to partially quantify the potential economic benefits that a vaccine, effective at protecting cattle against malignant catarrhal fever (MCF), could accrue to pastoralists living in East Africa. The benefits would result from the removal of household resource and management costs that are traditionally incurred avoiding the disease. MCF, a fatal disease of cattle caused by a virus transmitted from wildebeest calves, has plagued Maasai communities in East Africa for generations. The threat of the disease forces the Maasai to move cattle to less productive grazing areas to avoid wildebeest during calving season when forage quality is critical. To assess the management and resource costs associated with moving, we used household survey data. To estimate the costs associated with changes in livestock body condition that result from being herded away from wildebeest calving grounds, we exploited an ongoing MCF vaccine field trial and we used a hedonic price regression, a statistical model that allows estimation of the marginal contribution of a good’s attributes to its market price. We found that 90 percent of households move, on average, 82 percent of all cattle away from home to avoid MCF. In doing so, a herd’s productive contributions to the household was reduced, with 64 percent of milk being unavailable for sale or consumption by the family members remaining at the boma (the children, women, and the elderly). In contrast cattle that remained on the wildebeest calving grounds during the calving season (and survived MCF) remained fully productive to the family and gained body condition compared to cattle that moved away. This gain was, however, short-lived. We estimated the market value of these condition gains and losses using hedonic regression. The value of a vaccine for MCF is the removal of the costs incurred in avoiding the disease. PMID:25629896

Increased levels of conditioned fear and avoidance behavior coincide with changes in phosphorylation of the protein kinase B (AKT) within the amygdala in a mouse model of extremes in trait anxiety.

PubMed

Yen, Yi-Chun; Mauch, Christoph P; Dahlhoff, Maik; Micale, Vincenzo; Bunck, Mirjam; Sartori, Simone B; Singewald, Nicolas; Landgraf, Rainer; Wotjak, Carsten T

2012-07-01

Patients diagnosed for anxiety disorders often display faster acquisition and slower extinction of learned fear. To gain further insights into the mechanisms underlying these phenomenona, we studied conditioned fear in mice originating form a bi-directional selective breeding approach, which is based on elevated plus-maze behavior and results in CD1-derived high (HAB), normal (NAB), and low (LAB) anxiety-related behavior mice. HAB mice displayed pronounced cued-conditioned fear compared to NAB/CD1 and LAB mice that coincided with increased phosphorylation of the protein kinase B (AKT) in the basolateral amygdala 45 min after conditioning. No similar changes were observed after non-associative immediate shock presentations. Fear extinction of recent but not older fear memories was preserved. However, HAB mice were more prone to relapse of conditioned fear with the passage of time. HAB mice also displayed higher levels of contextual fear compared to NAB and LAB mice and exaggerated avoidance following step-down avoidance training. Interestingly, HAB mice showed lower and LAB mice higher levels of acoustic startle responses compared to NAB controls. The increase in arousal observed in LAB mice coincided with the general absence of conditioned freezing. Taken together, our results suggest that the genetic predisposition to high anxiety-related behavior may increase the risk of forming traumatic memories, phobic-like fear and avoidance behavior following aversive encounters, with a clear bias towards passive coping styles. In contrast, genetic predisposition to low anxiety-related and high risk-taking behavior seems to be associated with an increase in active coping styles. Our data imply changes in AKT phosphorylation as a therapeutic target for the prevention of exaggerated fear memories. Copyright © 2012 Elsevier Inc. All rights reserved.
FMCSA safety program effectiveness measurement : Intervention Model in fiscal year 2007

DOT National Transportation Integrated Search

2011-04-01

This report presents results from FMCSAs Roadside Intervention Model for fiscal year 2007. The model estimates the number of crashes avoided, as well as injuries avoided and lives saved, as a result of the Agencys roadside inspection program. T...
Inbreeding parents should invest more resources in fewer offspring.

PubMed

Duthie, A Bradley; Lee, Aline M; Reid, Jane M

2016-11-30

Inbreeding increases parent-offspring relatedness and commonly reduces offspring viability, shaping selection on reproductive interactions involving relatives and associated parental investment (PI). Nevertheless, theories predicting selection for inbreeding versus inbreeding avoidance and selection for optimal PI have only been considered separately, precluding prediction of optimal PI and associated reproductive strategy given inbreeding. We unify inbreeding and PI theory, demonstrating that optimal PI increases when a female's inbreeding decreases the viability of her offspring. Inbreeding females should therefore produce fewer offspring due to the fundamental trade-off between offspring number and PI. Accordingly, selection for inbreeding versus inbreeding avoidance changes when females can adjust PI with the degree that they inbreed. By contrast, optimal PI does not depend on whether a focal female is herself inbred. However, inbreeding causes optimal PI to increase given strict monogamy and associated biparental investment compared with female-only investment. Our model implies that understanding evolutionary dynamics of inbreeding strategy, inbreeding depression, and PI requires joint consideration of the expression of each in relation to the other. Overall, we demonstrate that existing PI and inbreeding theories represent special cases of a more general theory, implying that intrinsic links between inbreeding and PI affect evolution of behaviour and intrafamilial conflict. © 2016 The Authors.
Analysis of contributing factors associated to related patients safety incidents in Intensive Care Medicine.

PubMed

Martín Delgado, M C; Merino de Cos, P; Sirgo Rodríguez, G; Álvarez Rodríguez, J; Gutiérrez Cía, I; Obón Azuara, B; Alonso Ovies, Á

2015-01-01

To explore contributing factors (CF) associated to related critical patients safety incidents. SYREC study pos hoc analysis. A total of 79 Intensive Care Departments were involved. The study sample consisted of 1.017 patients; 591 were affected by one or more incidents. The CF were categorized according to a proposed model by the National Patient Safety Agency from United Kingdom that was modified. Type, class and severity of the incidents was analyzed. A total 2,965 CF were reported (1,729 were associated to near miss and 1,236 to adverse events). The CF group more frequently reported were related patients factors. Individual factors were reported more frequently in near miss and task related CF in adverse events. CF were reported in all classes of incidents. The majority of CF were reported in the incidents classified such as less serious, even thought CF patients factors were associated to serious incidents. Individual factors were considered like avoidable and patients factors as unavoidable. The CF group more frequently reported were patient factors and was associated to more severe and unavoidable incidents. By contrast, individual factors were associated to less severe and avoidable incidents. In general, CF most frequently reported were associated to near miss. Copyright © 2014 Elsevier España, S.L.U. and SEMICYUC. All rights reserved.
Behaviourally-inhibited temperament and female sex, two vulnerability factors for anxiety disorders, facilitate conditioned avoidance (also) in humans

PubMed Central

Sheynin, Jony; Beck, Kevin D.; Pang, Kevin C.H.; Servatius, Richard J.; Shikari, Saima; Ostovich, Jacqueline; Myers, Catherine E.

2014-01-01

Acquisition and maintenance of avoidance behaviour is a key feature of all human anxiety disorders. Animal models have been useful in understanding how anxiety vulnerability could translate into avoidance learning. For example, behaviourally-inhibited temperament and female sex, two vulnerability factors for clinical anxiety, are associated with faster acquisition of avoidance responses in rodents. However, to date, the translation of such empirical data to human populations has been limited since many features of animal avoidance paradigms are not typically captured in human research. Here, using a computer-based task that captures many features of rodent escape-avoidance learning paradigms, we investigated whether avoidance learning would be faster in humans with inhibited temperament and/or female sex and, if so, whether this facilitation would take the same form. Results showed that, as in rats, both vulnerability factors were associated with facilitated acquisition of avoidance behaviour in humans. Specifically, inhibited temperament was specifically associated with higher rate of avoidance responding, while female sex was associated with longer avoidance duration. These findings strengthen the direct link between animal avoidance work and human anxiety vulnerability, further motivating the study of animal models while also providing a simple testbed for a direct human testing. PMID:24412263
The Neural Correlates of Anomalous Habituation to Negative Emotional Pictures in Borderline and Avoidant Personality Disorder Patients

PubMed Central

Koenigsberg, Harold W.; Denny, Bryan T.; Fan, Jin; Liu, Xun; Guerreri, Stephanie; Jo Mayson, Sarah; Rimsky, Liza; New, Antonia S.; Goodman, Marianne; Siever, Larry J

2013-01-01

Objective Extreme emotional reactivity is a defining feature of borderline personality disorder, yet the neural-behavioral mechanisms underlying this affective instability are poorly understood. One possible contributor would be diminished ability to engage the mechanism of emotional habituation. We tested this hypothesis by examining behavioral and neural correlates of habituation in borderline patients, healthy controls, and a psychopathological control group of avoidant personality disorder patients. Method During fMRI scan acquisition, borderline patients, healthy controls and avoidant personality disorder patients viewed novel and repeated pictures, providing valence ratings at each presentation. Statistical parametric maps of the contrasts of activation during repeat versus novel negative picture viewing were compared between groups. Psychophysiological interaction analysis was employed to examine functional connectivity differences between groups. Results Unlike healthy controls, neither borderline nor avoidant personality disorder participants showed increased activity in dorsal anterior cingulate cortex when viewing repeat versus novel pictures. This failure to increase dorsal anterior cingulate activity was associated with greater affective instability in borderline participants. In addition, borderline and avoidant participants showed smaller insula-amygdala connectivity increases than healthy participants and did not show habituation in ratings of the emotional intensity of the images as did healthy participants. Borderline patients differed from avoidant patients in insula-ventral anterior cingulate connectivity during habituation. Conclusions Borderline patients fail to habituate to negative pictures as do healthy participants and differ from both healthy controls and avoidant patients in neural activity during habituation. A failure to effectively engage emotional habituation processes may contribute to affective instability in borderline patients. PMID:24275960
The equivalence of numbers: The social value of avoiding health decline: An experimental web-based study

PubMed Central

Schwappach, David LB

2002-01-01

Background Health economic analysis aimed at informing policy makers and supporting resource allocation decisions has to evaluate not only improvements in health but also avoided decline. Little is known however, whether the "direction" in which changes in health are experienced is important for the public in prioritizing among patients. This experimental study investigates the social value people place on avoiding (further) health decline when directly compared to curative treatments in resource allocation decisions. Methods 127 individuals completed an interactive survey that was published in the World Wide Web. They were confronted with a standard gamble (SG) and three person trade-off tasks, either comparing improvements in health (PTO-Up), avoided decline (PTO-Down), or both, contrasting health changes of equal magnitude differing in the direction in which they are experienced (PTO-WAD). Finally, a direct priority ranking of various interventions was obtained. Results Participants strongly prioritized improving patients' health rather than avoiding decline. The mean substitution rate between health improvements and avoided decline (WAD) ranged between 0.47 and 0.64 dependent on the intervention. Weighting PTO values according to the direction in which changes in health are experienced improved their accuracy in predicting a direct prioritization ranking. Health state utilities obtained by the standard gamble method seem not to reflect social values in resource allocation contexts. Conclusion Results suggest that the utility of being cured of a given health state might not be a good approximation for the societal value of avoiding this health state, especially in cases of competition between preventive and curative interventions. PMID:11879529
Self-Concealment, Avoidance of Psychological Services, and Perceived Likelihood of Seeking Professional Help.

ERIC Educational Resources Information Center

Cepeda-Benito, Antonio; Short, Paul

1998-01-01

New information about the role of self-concealment in the decision to seek psychological services is investigated. Different types of distress selectively predict students' perceived likelihood of seeking help according to the problems for which help would be sought (N=732). Results are discussed in contrast to previous researchers' findings. (EMK)
Memory Consequences of Looking Back to Notice Change: Retroactive and Proactive Facilitation

ERIC Educational Resources Information Center

Jacoby, Larry L.; Wahlheim, Christopher N.; Kelley, Colleen M.

2015-01-01

Three experiments contrasted recollection of change with differentiation as means of avoiding retroactive interference and proactive interference. We manipulated the extent to which participants looked back to notice change between pairs of cues and targets (A-B, A-D) and measured the effects on later cued recall of either the first or second…
An Application of Functional Analytic Psychotherapy in a Case of Anxiety Panic Disorder without Agoraphobia

ERIC Educational Resources Information Center

Bermudez, Miguel Angel Lopez; Garcia, Rafael Ferro; Calvillo, Manuel

2010-01-01

Traditional methods of diagnosis are of little therapeutic use when diagnostic criteria are based upon topographical rather than functional aspects of behavior. Also, this sentence in the original seemed rather awkward and a bit unclear. In contrast to this, several authors have put forward experience avoidance disorders as an alternative which…
Febuxostat in the management of gout: a cost-effectiveness analysis.

PubMed

Smolen, Lee J; Gahn, James C; Mitri, Ghaith; Shiozawa, Aki

2016-01-01

To determine the cost-effectiveness of febuxostat vs allopurinol for the management of gout. A stochastic microsimulation cost-effectiveness model with a US private-payer perspective and 5-year time horizon was developed. Model flow based on guideline and real-world treatment paradigms incorporated gout flare, serum uric acid (sUA) testing, treatment titration, discontinuation, and adverse events, chronic kidney disease (CKD) incidence and progression, and type 2 diabetes mellitus (T2DM) incidence. Outcomes were estimated for the general gout population and for gout patients with CKD stages 3/4. Modeled treatment interventions were daily oral febuxostat 40-80 mg and allopurinol 100-300 mg. Baseline patient characteristics were taken from epidemiologic studies, efficacy data from randomized controlled trials, adverse event rates from package inserts, and costs from the literature, government sources, and expert opinion. Eight clinically-relevant incremental cost-effectiveness ratios were estimated: per patient reaching target sUA, per flare avoided, per CKD incidence, progression, stages 3/4 progression, and stage 5 progression avoided, per incident T2DM avoided, and per death avoided. Five-year incremental cost-effectiveness ratios for the general gout population were $5377 per patient reaching target sUA, $1773 per flare avoided, $221,795 per incident CKD avoided, $29,063 per CKD progression avoided, $36,018 per progression to CKD 3/4 avoided, $71,426 per progression to CKD 5 avoided, $214,277 per incident T2DM avoided, and $217,971 per death avoided. In patients with CKD 3/4, febuxostat dominated allopurinol for all cost-effectiveness outcome measures. Febuxostat may be a cost-effective alternative to allopurinol, especially for patients with CKD stages 3 or 4.
Extending the the behavioral immune system to political psychology: are political conservatism and disgust sensitivity really related?

PubMed

Tybur, Joshua M; Merriman, Leslie A; Hooper, Ann E Caldwell; McDonald, Melissa M; Navarrete, Carlos David

2010-10-26

Previous research suggests that several individual and cultural level attitudes, cognitions, and societal structures may have evolved to mitigate the pathogen threats posed by intergroup interactions. It has been suggested that these anti-pathogen defenses are at the root of conservative political ideology. Here, we test a hypothesis that political conservatism functions as a pathogen-avoidance strategy. Across three studies, we consistently find no relationship between sensitivity to pathogen disgust and multiple measures of political conservatism. These results are contrasted with theoretical perspectives suggesting a relationship between conservatism and pathogen avoidance, and with previous findings of a relationship between conservatism and disgust sensitivity.
An Avoidance-Based Rodent Model of Exposure With Response Prevention Therapy for Obsessive-Compulsive Disorder.

PubMed

Rodriguez-Romaguera, Jose; Greenberg, Benjamin D; Rasmussen, Steven A; Quirk, Gregory J

2016-10-01

Obsessive-compulsive disorder is treated with exposure with response prevention (ERP) therapy, in which patients are repeatedly exposed to compulsive triggers but prevented from expressing their compulsions. Many compulsions are an attempt to avoid perceived dangers, and the intent of ERP is to extinguish compulsions. Patients failing ERP therapy are candidates for deep brain stimulation (DBS) of the ventral capsule/ventral striatum, which facilitates patients' response to ERP therapy. An animal model of ERP would be useful for understanding the neural mechanisms of extinction in obsessive-compulsive disorder. Using a platform-mediated signaled avoidance task, we developed a rodent model of ERP called extinction with response prevention (Ext-RP), in which avoidance-conditioned rats are given extinction trials while blocking access to the avoidance platform. Following 3 days of Ext-RP, rats were tested with the platform unblocked to evaluate persistent avoidance. We then assessed if pharmacologic inactivation of lateral orbitofrontal cortex (lOFC) or DBS of the ventral striatum reduced persistent avoidance. Following Ext-RP training, most rats showed reduced avoidance at test (Ext-RP success), but a subset persisted in their avoidance (Ext-RP failure). Pharmacologic inactivation of lOFC eliminated persistent avoidance, as did DBS applied to the ventral striatum during Ext-RP. DBS of ventral striatum has been previously shown to inhibit lOFC activity. Thus, activity in lOFC, which is known to be hyperactive in obsessive-compulsive disorder, may be responsible for impairing patients' response to ERP therapy. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
Predicting the dynamics of bacterial growth inhibition by ribosome-targeting antibiotics

NASA Astrophysics Data System (ADS)

Greulich, Philip; Doležal, Jakub; Scott, Matthew; Evans, Martin R.; Allen, Rosalind J.

2017-12-01

Understanding how antibiotics inhibit bacteria can help to reduce antibiotic use and hence avoid antimicrobial resistance—yet few theoretical models exist for bacterial growth inhibition by a clinically relevant antibiotic treatment regimen. In particular, in the clinic, antibiotic treatment is time-dependent. Here, we use a theoretical model, previously applied to steady-state bacterial growth, to predict the dynamical response of a bacterial cell to a time-dependent dose of ribosome-targeting antibiotic. Our results depend strongly on whether the antibiotic shows reversible transport and/or low-affinity ribosome binding (‘low-affinity antibiotic’) or, in contrast, irreversible transport and/or high affinity ribosome binding (‘high-affinity antibiotic’). For low-affinity antibiotics, our model predicts that growth inhibition depends on the duration of the antibiotic pulse, and can show a transient period of very fast growth following removal of the antibiotic. For high-affinity antibiotics, growth inhibition depends on peak dosage rather than dose duration, and the model predicts a pronounced post-antibiotic effect, due to hysteresis, in which growth can be suppressed for long times after the antibiotic dose has ended. These predictions are experimentally testable and may be of clinical significance.
Majorization Minimization by Coordinate Descent for Concave Penalized Generalized Linear Models

PubMed Central

Jiang, Dingfeng; Huang, Jian

2013-01-01

Recent studies have demonstrated theoretical attractiveness of a class of concave penalties in variable selection, including the smoothly clipped absolute deviation and minimax concave penalties. The computation of the concave penalized solutions in high-dimensional models, however, is a difficult task. We propose a majorization minimization by coordinate descent (MMCD) algorithm for computing the concave penalized solutions in generalized linear models. In contrast to the existing algorithms that use local quadratic or local linear approximation to the penalty function, the MMCD seeks to majorize the negative log-likelihood by a quadratic loss, but does not use any approximation to the penalty. This strategy makes it possible to avoid the computation of a scaling factor in each update of the solutions, which improves the efficiency of coordinate descent. Under certain regularity conditions, we establish theoretical convergence property of the MMCD. We implement this algorithm for a penalized logistic regression model using the SCAD and MCP penalties. Simulation studies and a data example demonstrate that the MMCD works sufficiently fast for the penalized logistic regression in high-dimensional settings where the number of covariates is much larger than the sample size. PMID:25309048
Predicting the dynamics of bacterial growth inhibition by ribosome-targeting antibiotics

PubMed Central

Greulich, Philip; Doležal, Jakub; Scott, Matthew; Evans, Martin R; Allen, Rosalind J

2017-01-01

Understanding how antibiotics inhibit bacteria can help to reduce antibiotic use and hence avoid antimicrobial resistance—yet few theoretical models exist for bacterial growth inhibition by a clinically relevant antibiotic treatment regimen. In particular, in the clinic, antibiotic treatment is time-dependent. Here, we use a theoretical model, previously applied to steady-state bacterial growth, to predict the dynamical response of a bacterial cell to a time-dependent dose of ribosome-targeting antibiotic. Our results depend strongly on whether the antibiotic shows reversible transport and/or low-affinity ribosome binding (‘low-affinity antibiotic’) or, in contrast, irreversible transport and/or high affinity ribosome binding (‘high-affinity antibiotic’). For low-affinity antibiotics, our model predicts that growth inhibition depends on the duration of the antibiotic pulse, and can show a transient period of very fast growth following removal of the antibiotic. For high-affinity antibiotics, growth inhibition depends on peak dosage rather than dose duration, and the model predicts a pronounced post-antibiotic effect, due to hysteresis, in which growth can be suppressed for long times after the antibiotic dose has ended. These predictions are experimentally testable and may be of clinical significance. PMID:28714461
Functional Nanoparticles for Magnetic Resonance Imaging

PubMed Central

Mao, Xinpei; Xu, Jiadi; Cui, Honggang

2016-01-01

Nanoparticle-based magnetic resonance imaging (MRI) contrast agents have received much attention over the past decade. By virtue of a high payload of magnetic moieties, enhanced accumulation at disease sites, and a large surface area for additional modification with targeting ligands, nanoparticle-based contrast agents offer promising new platforms to further enhance the high resolution and sensitivity of MRI for various biomedical applications. T2* superparamagnetic iron oxide nanoparticles (SPIONs) first demonstrated superior improvement on MRI sensitivity. The prevailing SPION attracted growing interest in the development of refined nanoscale versions of MRI contrast agents. Afterwards, T1-based contrast agents were developed, and became the most studied subject in MRI due to the positive contrast they provide that avoids the susceptibility associated with MRI signal reduction. Recently, chemical exchange saturation transfer (CEST) contrast agents have emerged and rapidly gained popularity. The unique aspect of CEST contrast agents is that their contrast can be selectively turned “on” and “off” by radiofrequency (RF) saturation. Their performance can be further enhanced by incorporating a large number of exchangeable protons into well-defined nanostructure. Besides activatable CEST contrast agents, there is growing interest in developing nanoparticle-based activatable MRI contrast agents responsive to stimuli (pH, enzyme, etc.), which improves sensitivity and specificity. In this review, we summarize the recent development of various types of nanoparticle-based MRI contrast agents, and have focused our discussions on the key advantages of introducing nanoparticles in MRI. PMID:27040463
Location of the adsorption transition for lattice polymers

NASA Astrophysics Data System (ADS)

Madras, Neal

2017-02-01

We consider various lattice models of polymers: lattice trees, lattice animals, and self-avoiding walks. The polymer interacts with a surface (hyperplane), receiving an energy reward of β for each site in the surface. It is known that there is an adsorption transition at a critical value of β. We present a new proof of the result of Hammersley et al (1982 J. Phys. A: Math. Gen. 15 539-71) that the transition occurs at a strictly positive value of β when the surface is impenetrable, i.e. when the polymer is restricted to a half-space. In contrast, for a penetrable surface, it is an open problem to prove that the transition occurs at β =0 . We reduce this problem to proving that the fraction of N-site polymers whose span is less than N/{{log}2}N is not too small.
Cosmological models in energy-momentum-squared gravity

NASA Astrophysics Data System (ADS)

Board, Charles V. R.; Barrow, John D.

2017-12-01

We study the cosmological effects of adding terms of higher order in the usual energy-momentum tensor to the matter Lagrangian of general relativity. This is in contrast to most studies of higher-order gravity which focus on generalizing the Einstein-Hilbert curvature contribution to the Lagrangian. The resulting cosmological theories give rise to field equations of similar form to several particular theories with different fundamental bases, including bulk viscous cosmology, loop quantum gravity, k -essence, and brane-world cosmologies. We find a range of exact solutions for isotropic universes, discuss their behaviors with reference to the early- and late-time evolution, accelerated expansion, and the occurrence or avoidance of singularities. We briefly discuss extensions to anisotropic cosmologies and delineate the situations where the higher-order matter terms will dominate over anisotropies on approach to cosmological singularities.
Allergic reactions to iodinated contrast media: premedication considerations for patients at risk.

PubMed

Schopp, Jennifer G; Iyer, Ramesh S; Wang, Carolyn L; Petscavage, Jonelle M; Paladin, Angelisa M; Bush, William H; Dighe, Manjiri K

2013-08-01

The objectives of this article are to review allergy-type reactions to iodinated contrast media and the protocols utilized to prevent or reduce the occurrence of these adverse reactions in high-risk patients. We will begin by discussing the types or classifications of the adverse reactions to iodinated contrast media. We will then discuss reaction mechanisms, identify the patients at highest risk for adverse reactions, and clarify common misperceptions about the risk. Finally, we will discuss the actions of the medications used to help reduce or prevent allergy-type reactions to iodinated contrast media, the protocols used to help reduce or prevent contrast reactions in high-risk patients, and the potential side effects of these medications. We will also discuss the high-risk patient who has received premedication due to a prior index reaction and discuss the risk of having a subsequent reaction, termed "breakthrough reaction." Identifying patient at high risk for an "allergy-type" reaction to contrast media is an essential task of the radiologist. Prevention of or reduction of the risk of an adverse reaction is critical to patient safety. If an examination can be performed without contrast in a patient at high risk for an allergy-type reaction, it may be appropriate to avoid contrast. However, there are situations where contrast media is necessary, and the radiologist plays a vital role in preventing or mitigating an allergy-type reaction.

Robust Models for Optic Flow Coding in Natural Scenes Inspired by Insect Biology

PubMed Central

Brinkworth, Russell S. A.; O'Carroll, David C.

2009-01-01

The extraction of accurate self-motion information from the visual world is a difficult problem that has been solved very efficiently by biological organisms utilizing non-linear processing. Previous bio-inspired models for motion detection based on a correlation mechanism have been dogged by issues that arise from their sensitivity to undesired properties of the image, such as contrast, which vary widely between images. Here we present a model with multiple levels of non-linear dynamic adaptive components based directly on the known or suspected responses of neurons within the visual motion pathway of the fly brain. By testing the model under realistic high-dynamic range conditions we show that the addition of these elements makes the motion detection model robust across a large variety of images, velocities and accelerations. Furthermore the performance of the entire system is more than the incremental improvements offered by the individual components, indicating beneficial non-linear interactions between processing stages. The algorithms underlying the model can be implemented in either digital or analog hardware, including neuromorphic analog VLSI, but defy an analytical solution due to their dynamic non-linear operation. The successful application of this algorithm has applications in the development of miniature autonomous systems in defense and civilian roles, including robotics, miniature unmanned aerial vehicles and collision avoidance sensors. PMID:19893631
Rapid evolution of mimicry following local model extinction.

PubMed

Akcali, Christopher K; Pfennig, David W

2014-06-01

Batesian mimicry evolves when individuals of a palatable species gain the selective advantage of reduced predation because they resemble a toxic species that predators avoid. Here, we evaluated whether-and in which direction-Batesian mimicry has evolved in a natural population of mimics following extirpation of their model. We specifically asked whether the precision of coral snake mimicry has evolved among kingsnakes from a region where coral snakes recently (1960) went locally extinct. We found that these kingsnakes have evolved more precise mimicry; by contrast, no such change occurred in a sympatric non-mimetic species or in conspecifics from a region where coral snakes remain abundant. Presumably, more precise mimicry has continued to evolve after model extirpation, because relatively few predator generations have passed, and the fitness costs incurred by predators that mistook a deadly coral snake for a kingsnake were historically much greater than those incurred by predators that mistook a kingsnake for a coral snake. Indeed, these results are consistent with prior theoretical and empirical studies, which revealed that only the most precise mimics are favoured as their model becomes increasingly rare. Thus, highly noxious models can generate an 'evolutionary momentum' that drives the further evolution of more precise mimicry-even after models go extinct. © 2014 The Author(s) Published by the Royal Society. All rights reserved.
Rapid evolution of mimicry following local model extinction

PubMed Central

Akcali, Christopher K.; Pfennig, David W.

2014-01-01

Batesian mimicry evolves when individuals of a palatable species gain the selective advantage of reduced predation because they resemble a toxic species that predators avoid. Here, we evaluated whether—and in which direction—Batesian mimicry has evolved in a natural population of mimics following extirpation of their model. We specifically asked whether the precision of coral snake mimicry has evolved among kingsnakes from a region where coral snakes recently (1960) went locally extinct. We found that these kingsnakes have evolved more precise mimicry; by contrast, no such change occurred in a sympatric non-mimetic species or in conspecifics from a region where coral snakes remain abundant. Presumably, more precise mimicry has continued to evolve after model extirpation, because relatively few predator generations have passed, and the fitness costs incurred by predators that mistook a deadly coral snake for a kingsnake were historically much greater than those incurred by predators that mistook a kingsnake for a coral snake. Indeed, these results are consistent with prior theoretical and empirical studies, which revealed that only the most precise mimics are favoured as their model becomes increasingly rare. Thus, highly noxious models can generate an ‘evolutionary momentum’ that drives the further evolution of more precise mimicry—even after models go extinct. PMID:24919704
Avoiding and tolerating latency in large-scale next-generation shared-memory multiprocessors

NASA Technical Reports Server (NTRS)

Probst, David K.

1993-01-01

A scalable solution to the memory-latency problem is necessary to prevent the large latencies of synchronization and memory operations inherent in large-scale shared-memory multiprocessors from reducing high performance. We distinguish latency avoidance and latency tolerance. Latency is avoided when data is brought to nearby locales for future reference. Latency is tolerated when references are overlapped with other computation. Latency-avoiding locales include: processor registers, data caches used temporally, and nearby memory modules. Tolerating communication latency requires parallelism, allowing the overlap of communication and computation. Latency-tolerating techniques include: vector pipelining, data caches used spatially, prefetching in various forms, and multithreading in various forms. Relaxing the consistency model permits increased use of avoidance and tolerance techniques. Each model is a mapping from the program text to sets of partial orders on program operations; it is a convention about which temporal precedences among program operations are necessary. Information about temporal locality and parallelism constrains the use of avoidance and tolerance techniques. Suitable architectural primitives and compiler technology are required to exploit the increased freedom to reorder and overlap operations in relaxed models.
Polarized object detection in crabs: a two-channel system.

PubMed

Basnak, Melanie Ailín; Pérez-Schuster, Verónica; Hermitte, Gabriela; Berón de Astrada, Martín

2018-05-25

Many animal species take advantage of polarization vision for vital tasks such as orientation, communication and contrast enhancement. Previous studies have suggested that decapod crustaceans use a two-channel polarization system for contrast enhancement. Here, we characterize the polarization contrast sensitivity in a grapsid crab . We estimated the polarization contrast sensitivity of the animals by quantifying both their escape response and changes in heart rate when presented with polarized motion stimuli. The motion stimulus consisted of an expanding disk with an 82 deg polarization difference between the object and the background. More than 90% of animals responded by freezing or trying to avoid the polarized stimulus. In addition, we co-rotated the electric vector (e-vector) orientation of the light from the object and background by increments of 30 deg and found that the animals' escape response varied periodically with a 90 deg period. Maximum escape responses were obtained for object and background e-vectors near the vertical and horizontal orientations. Changes in cardiac response showed parallel results but also a minimum response when e-vectors of object and background were shifted by 45 deg with respect to the maxima. These results are consistent with an orthogonal receptor arrangement for the detection of polarized light, in which two channels are aligned with the vertical and horizontal orientations. It has been hypothesized that animals with object-based polarization vision rely on a two-channel detection system analogous to that of color processing in dichromats. Our results, obtained by systematically varying the e-vectors of object and background, provide strong empirical support for this theoretical model of polarized object detection. © 2018. Published by The Company of Biologists Ltd.
Vision-based mobile robot navigation through deep convolutional neural networks and end-to-end learning

NASA Astrophysics Data System (ADS)

Zhang, Yachu; Zhao, Yuejin; Liu, Ming; Dong, Liquan; Kong, Lingqin; Liu, Lingling

2017-09-01

In contrast to humans, who use only visual information for navigation, many mobile robots use laser scanners and ultrasonic sensors along with vision cameras to navigate. This work proposes a vision-based robot control algorithm based on deep convolutional neural networks. We create a large 15-layer convolutional neural network learning system and achieve the advanced recognition performance. Our system is trained from end to end to map raw input images to direction in supervised mode. The images of data sets are collected in a wide variety of weather conditions and lighting conditions. Besides, the data sets are augmented by adding Gaussian noise and Salt-and-pepper noise to avoid overfitting. The algorithm is verified by two experiments, which are line tracking and obstacle avoidance. The line tracking experiment is proceeded in order to track the desired path which is composed of straight and curved lines. The goal of obstacle avoidance experiment is to avoid the obstacles indoor. Finally, we get 3.29% error rate on the training set and 5.1% error rate on the test set in the line tracking experiment, 1.8% error rate on the training set and less than 5% error rate on the test set in the obstacle avoidance experiment. During the actual test, the robot can follow the runway centerline outdoor and avoid the obstacle in the room accurately. The result confirms the effectiveness of the algorithm and our improvement in the network structure and train parameters
Comparing Posttraumatic Stress Disorder's Symptom Structure between Deployed and Nondeployed Veterans

ERIC Educational Resources Information Center

Engdahl, Ryan M.; Elhai, Jon D.; Richardson, J. Don; Frueh, B. Christopher

2011-01-01

We tested two empirically validated 4-factor models of posttraumatic stress disorder (PTSD) symptoms using the PTSD Checklist: King, Leskin, King, and Weathers' (1998) model including reexperiencing, avoidance, emotional numbing, and hyperarousal factors, and Simms, Watson, and Doebbeling's (2002) model including reexperiencing, avoidance,…
Absence of “Warm-Up” during Active Avoidance Learning in a Rat Model of Anxiety Vulnerability: Insights from Computational Modeling

PubMed Central

Myers, Catherine E.; Smith, Ian M.; Servatius, Richard J.; Beck, Kevin D.

2014-01-01

Avoidance behaviors, in which a learned response causes omission of an upcoming punisher, are a core feature of many psychiatric disorders. While reinforcement learning (RL) models have been widely used to study the development of appetitive behaviors, less attention has been paid to avoidance. Here, we present a RL model of lever-press avoidance learning in Sprague-Dawley (SD) rats and in the inbred Wistar Kyoto (WKY) rat, which has been proposed as a model of anxiety vulnerability. We focus on “warm-up,” transiently decreased avoidance responding at the start of a testing session, which is shown by SD but not WKY rats. We first show that a RL model can correctly simulate key aspects of acquisition, extinction, and warm-up in SD rats; we then show that WKY behavior can be simulated by altering three model parameters, which respectively govern the tendency to explore new behaviors vs. exploit previously reinforced ones, the tendency to repeat previous behaviors regardless of reinforcement, and the learning rate for predicting future outcomes. This suggests that several, dissociable mechanisms may contribute independently to strain differences in behavior. The model predicts that, if the “standard” inter-session interval is shortened from 48 to 24 h, SD rats (but not WKY) will continue to show warm-up; we confirm this prediction in an empirical study with SD and WKY rats. The model further predicts that SD rats will continue to show warm-up with inter-session intervals as short as a few minutes, while WKY rats will not show warm-up, even with inter-session intervals as long as a month. Together, the modeling and empirical data indicate that strain differences in warm-up are qualitative rather than just the result of differential sensitivity to task variables. Understanding the mechanisms that govern expression of warm-up behavior in avoidance may lead to better understanding of pathological avoidance, and potential pathways to modify these processes. PMID:25183956
Extending Antecedents of Achievement Goals: The Double-Edged Sword Effect of Social-Oriented Achievement Motive and Gender Differences

ERIC Educational Resources Information Center

Nie, Youyan; Liem, Gregory Arief D.

2013-01-01

Underpinned by the hierarchical model of approach and avoidance motivation, the study examined the differential relations of individual-oriented and social-oriented achievement motives to approach and avoidance achievement goals (mastery-approach, performance-approach, mastery-avoidance, performance-avoidance). A total of 570 Chinese high school…
Avoidance learning: a review of theoretical models and recent developments

PubMed Central

Krypotos, Angelos-Miltiadis; Effting, Marieke; Kindt, Merel; Beckers, Tom

2015-01-01

Avoidance is a key characteristic of adaptive and maladaptive fear. Here, we review past and contemporary theories of avoidance learning. Based on the theories, experimental findings and clinical observations reviewed, we distill key principles of how adaptive and maladaptive avoidance behavior is acquired and maintained. We highlight clinical implications of avoidance learning theories and describe intervention strategies that could reduce maladaptive avoidance and prevent its return. We end with a brief overview of recent developments and avenues for further research. PMID:26257618
Internet Addiction and Psychosocial Maladjustment: Avoidant Coping and Coping Inflexibility as Psychological Mechanisms.

PubMed

Cheng, Cecilia; Sun, Peizhen; Mak, Kwok-Kei

2015-09-01

This 6 month prospective study systematically tested some multivariate models that advanced the understanding of the psychological mechanisms underlying Internet addiction and psychosocial maladjustment. On the basis of previous theories, avoidant coping and coping inflexibility were proposed as underlying mechanisms. Participants were 271 Chinese undergraduates (75% women, Mage=20.49) who took part in both phases of this study. Structural equation modeling was performed to obtain the best fit models for both the cross-sectional and the prospective data. The cross-sectional model testing revealed statistically significant mediating effects for both avoidant coping (β=0.149 [95% CI 0.071-0.226], p=0.002) and coping flexibility (β=0.048 [95% CI 0.013-0.081], p=0.032). The prospective model testing further showed that avoidant coping mediated the relationship between Internet addiction and Time 2 psychosocial maladjustment (β=0.141 [95% CI 0.065-0.216], p=0.005), as well as that between coping flexibility and Time 2 psychosocial maladjustment (β=-0.096 [95% CI -0.161 to -0.031], p=0.015). This study was the first to establish theory-driven models, which unveiled an inflexible, avoidant coping style as psychological mechanisms that explained the link between Internet addiction and psychosocial maladjustment.
The mechanisms underlying overgeneral autobiographical memory: An evaluative review of evidence for the CaR-FA-X model

PubMed Central

Sumner, Jennifer A.

2011-01-01

Overgeneral autobiographical memory (OGM) has been found to be an important cognitive phenomenon with respect to depression and trauma-related psychopathology (e.g., posttraumatic stress disorder), and researchers have been interested in better understanding the factors that contribute to this proposed vulnerability factor. The most prominent model of mechanisms underlying OGM to date is Williams et al.’s (2007) CaR-FA-X model. This model proposes that three processes influence OGM: capture and rumination, functional avoidance, and impaired executive control. The author reviews the current state of support for the CaR-FA-X model by evaluating 38 studies that have examined OGM and one or more mechanisms of the model. Collectively, these studies reveal robust support for associations between OGM and both rumination and impaired executive control. OGM also appears to be a cognitive avoidance strategy, and there is evidence that avoiding the retrieval of specific memories reduces distress after an aversive event, at least in the short term. Important issues that have been left unresolved are highlighted, including the nature of the capture phenomenon, the role of trauma in functional avoidance, and the developmental nature of functional avoidance. Recommendations for future research that will enhance understanding of the factors that contribute to OGM are suggested. PMID:22142837
Coronagraph Focal-Plane Phase Masks Based on Photonic Crystal Technology: Recent Progress and Observational Strategy

NASA Technical Reports Server (NTRS)

Murakami, Naoshi; Nishikawa, Jun; Sakamoto, Moritsugu; Ise, Akitoshi; Oka, Kazuhiko; Baba, Naoshi; Murakami, Hiroshi; Tamura, Motohide; Traub, Wesley A.; Mawet, Dimitri;

2012-01-01

Photonic crystal, an artificial periodic nanostructure of refractive indices, is one of the attractive technologies for coronagraph focal-plane masks aiming at direct imaging and characterization of terrestrial extrasolar planets. We manufactured the eight-octant phase mask (8OPM) and the vector vortex mask (VVM) very precisely using the photonic crystal technology. Fully achromatic phase-mask coronagraphs can be realized by applying appropriate polarization filters to the masks. We carried out laboratory experiments of the polarization-filtered 8OPM coronagraph using the High-Contrast Imaging Testbed (HCIT), a state-of-the-art coronagraph simulator at the Jet Propulsion Laboratory (JPL). We report the experimental results of 10-8-level contrast across several wavelengths over 10% bandwidth around 800nm. In addition, we present future prospects and observational strategy for the photonic-crystal mask coronagraphs combined with differential imaging techniques to reach higher contrast. We proposed to apply a polarization-differential imaging (PDI) technique to the VVM coronagraph, in which we built a two-channel coronagraph using polarizing beam splitters to avoid a loss of intensity due to the polarization filters. We also proposed to apply an angular-differential imaging (ADI) technique to the 8OPM coronagraph. The 8OPM/ADI mode avoids an intensity loss due to a phase transition of the mask and provides a full field of view around central stars. We present results of preliminary laboratory demonstrations of the PDI and ADI observational modes with the phase-mask coronagraphs.

Fear-avoidance beliefs and parental responses to pain in adolescents with chronic pain.

PubMed

Wilson, Anna C; Lewandowski, Amy S; Palermo, Tonya M

2011-01-01

The fear-avoidance model of chronic pain posits that fear of pain is associated with fear and avoidance of activity, which can lead to deconditioning and persistence of pain and disability. Despite being well supported in adults, little is known about the role of fear-avoidance beliefs regarding physical activity in children. Research has shown that parental protectiveness contributes to activity limitations in children; however, no studies have examined relationships between protectiveness, and fear and avoidance. To conduct a cross-sectional study to provide additional information regarding the reliability and validity of the Fear-Avoidance Beliefs Questionnaire physical activity subscale among adolescents with chronic pain; examine fear-avoidance beliefs and depressive symptoms as concurrent predictors of physical activity limitations; and test competing models using fear-avoidance beliefs as mediators and moderators of the association between parental protectiveness and activity limitations. Adolescents (n=42) 11 to 17 years of age with chronic pain completed questionnaires assessing pain intensity, fear-avoidance beliefs, depressive symptoms and physical activity limitations. Their parents completed questionnaires regarding protectiveness and adolescent activity limitations. The Fear-Avoidance Beliefs Questionnaire physical activity subscale was useful for assessing fear-avoidance beliefs in the present population. In support of hypotheses, greater fear-avoidance beliefs were associated with greater activity limitations, above pain intensity and depressive symptoms. Support was found for fear-avoidance beliefs as mediators of the association between parental protectiveness and activity limitations. Tests of moderation were not significant. Fear-avoidance beliefs may be an important target for interventions focused on decreasing activity limitations in youth with chronic pain. Future research should investigate these associations longitudinally.
Neuronal and non-neuronal signals regulate Caernorhabditis elegans avoidance of contaminated food.

PubMed

Anderson, Alexandra; McMullan, Rachel

2018-07-19

One way in which animals minimize the risk of infection is to reduce their contact with contaminated food. Here, we establish a model of pathogen-contaminated food avoidance using the nematode worm Caernorhabditis elegans We find that avoidance of pathogen-contaminated food protects C. elegans from the deleterious effects of infection and, using genetic approaches, demonstrate that multiple sensory neurons are required for this avoidance behaviour. In addition, our results reveal that the avoidance of contaminated food requires bacterial adherence to non-neuronal cells in the tail of C. elegans that are also required for the cellular immune response. Previous studies in C. elegans have contributed significantly to our understanding of molecular and cellular basis of host-pathogen interactions and our model provides a unique opportunity to gain basic insights into how animals avoid contaminated food.This article is part of the Theo Murphy meeting issue 'Evolution of pathogen and parasite avoidance behaviours'. © 2018 The Authors.
Behavioral and experiential avoidance in patients with hoarding disorder.

PubMed

Ayers, Catherine R; Castriotta, Natalie; Dozier, Mary E; Espejo, Emmanuel P; Porter, Ben

2014-09-01

This study examined the relationship between experiential and behavioral avoidance and hoarding symptom severity, controlling for anxiety and depression symptoms, in 66 adult individuals (M age = 61.41; SD = 9.03) with HD. Hierarchical regression was used to test the associations between hoarding severity, as defined by the Savings Inventory-Revised (SI-R) total and its three subscales, and avoidance, as defined by the Acceptance and Action Questionnaire II (AAQ-II) and two scales from the Brief COPE (Self-Distraction and Behavioral Disengagement) when controlling for anxiety and depression symptoms. Experiential avoidance (AAQ-II) and behavioral avoidance (Brief COPE subscales Self-Distraction and Behavioral Disengagement) uniquely accounted for aspects of hoarding severity (SI-R) in regression models. Behavioral avoidance contributed significant additional variance to the SI-R Clutter subscale, whereas experiential avoidance was uniquely predictive of additional variance in the SI-R Difficulty Discarding and the SI-R Acquisition subscales. Future research should examine the effect of experiential avoidance on hoarding behaviors experimentally. Given that the AAQ-II and Self-Distraction and Behavioral Disengagement subscales were not correlated, these findings suggest that experiential and behavioral avoidance are two distinct processes contributing to the severity of specific HD. Results support the utility of avoidance in the cognitive-behavioral model for HD. Copyright © 2014 Elsevier Ltd. All rights reserved.
An integrative formal model of motivation and decision making: The MGPM*.

PubMed

Ballard, Timothy; Yeo, Gillian; Loft, Shayne; Vancouver, Jeffrey B; Neal, Andrew

2016-09-01

We develop and test an integrative formal model of motivation and decision making. The model, referred to as the extended multiple-goal pursuit model (MGPM*), is an integration of the multiple-goal pursuit model (Vancouver, Weinhardt, & Schmidt, 2010) and decision field theory (Busemeyer & Townsend, 1993). Simulations of the model generated predictions regarding the effects of goal type (approach vs. avoidance), risk, and time sensitivity on prioritization. We tested these predictions in an experiment in which participants pursued different combinations of approach and avoidance goals under different levels of risk. The empirical results were consistent with the predictions of the MGPM*. Specifically, participants pursuing 1 approach and 1 avoidance goal shifted priority from the approach to the avoidance goal over time. Among participants pursuing 2 approach goals, those with low time sensitivity prioritized the goal with the larger discrepancy, whereas those with high time sensitivity prioritized the goal with the smaller discrepancy. Participants pursuing 2 avoidance goals generally prioritized the goal with the smaller discrepancy. Finally, all of these effects became weaker as the level of risk increased. We used quantitative model comparison to show that the MGPM* explained the data better than the original multiple-goal pursuit model, and that the major extensions from the original model were justified. The MGPM* represents a step forward in the development of a general theory of decision making during multiple-goal pursuit. (PsycINFO Database Record (c) 2016 APA, all rights reserved).
N-acetylcysteine in contrast-induced acute kidney injury: clinical use against principles of evidence-based clinical medicine!

PubMed

Sadat, Umar

2014-01-01

Contrast-induced acute kidney injury (CI-AKI) is one of the most widely discussed and debated topic in cardiovascular medicine and N-acetylcysteine (NAC) is the most widely used pharmacological agent assessed in clinical trials for offering renal protection against CI-AKI. Results of these clinical trials are though split between those that favor its use and vice versa. In this brief communication we discuss the latest research advances regarding the use of NAC against CI-AKI. Recent clinical evidence and overview of in-depth statistical analyses of relevant clinical trials and their meta-analyses do not support the use of NAC in prophylaxis against CI-AKI. Adequate hydration before and after contrast media exposure, along with avoidance of nephrotoxic drugs, remains the recommended prophylaxis against CI-AKI.
Carbon Dioxide Angiography: Scientific Principles and Practice

PubMed Central

Cho, Kyung Jae

2015-01-01

Carbon dioxide (CO2) is a colorless, odorless gas which occurs naturally in the atmosphere and human body. With the advent of digital subtraction angiography, the gas has been used as a safe and useful alternative contrast agent in both arteriography and venography. Because of its lack of renal toxicity and allergic potential, CO2 is a preferred contrast agent in patients with renal failure or contrast allergy, and particularly in patients who require large volumes of contrast medium for complex endovascular procedures. Understanding of the unique physical properties of CO2 (high solubility, low viscosity, buoyancy, and compressibility) is essential in obtaining a successful CO2 angiogram and in guiding endovascular intervention. Unlike iodinated contrast material, CO2 displaces the blood and produces a negative contrast for digital subtraction imaging. Indications for use of CO2 as a contrast agent include: aortography and runoff, detection of bleeding, renal transplant arteriography, portal vein visualization with wedged hepatic venous injection, venography, arterial and venous interventions, and endovascular aneurysm repair. CO2 should not be used in the thoracic aorta, the coronary artery, and cerebral circulation. Exploitation of CO2 properties, avoidance of air contamination and facile catheterization technique are important to the safe and effective performance of CO2 angiography and CO2-guided endovascular intervention. PMID:26509137
Spatiotemporal noise characterization for chirped-pulse amplification systems

PubMed Central

Ma, Jingui; Yuan, Peng; Wang, Jing; Wang, Yongzhi; Xie, Guoqiang; Zhu, Heyuan; Qian, Liejia

2015-01-01

Optical noise, the core of the pulse-contrast challenge for ultra-high peak power femtosecond lasers, exhibits spatiotemporal (ST) coupling induced by angular dispersion. Full characterization of such ST noise requires two-dimensional measurements in the ST domain. Thus far, all noise measurements have been made only in the temporal domain. Here we report the experimental characterization of the ST noise, which is made feasible by extending cross-correlation from the temporal domain to the ST domain. We experimentally demonstrate that the ST noise originates from the optical surface imperfections in the pulse stretcher/compressor and exhibits a linear ST coupling in the far-field plane. The contrast on the far-field axis, underestimated in the conventional measurements, is further improved by avoiding the far-field optics in the stretcher. These results enhance our understanding of the pulse contrast with respect to its ST-coupling nature and pave the way toward the design of high-contrast ultra-high peak power lasers. PMID:25648187

Hue-preserving and saturation-improved color histogram equalization algorithm.

PubMed

Song, Ki Sun; Kang, Hee; Kang, Moon Gi

2016-06-01

In this paper, an algorithm is proposed to improve contrast and saturation without color degradation. The local histogram equalization (HE) method offers better performance than the global HE method, whereas the local HE method sometimes produces undesirable results due to the block-based processing. The proposed contrast-enhancement (CE) algorithm reflects the characteristics of the global HE method in the local HE method to avoid the artifacts, while global and local contrasts are enhanced. There are two ways to apply the proposed CE algorithm to color images. One is luminance processing methods, and the other one is each channel processing methods. However, these ways incur excessive or reduced saturation and color degradation problems. The proposed algorithm solves these problems by using channel adaptive equalization and similarity of ratios between the channels. Experimental results show that the proposed algorithm enhances contrast and saturation while preserving the hue and producing better performance than existing methods in terms of objective evaluation metrics.
A Bayesian approach to modeling 2D gravity data using polygon states

NASA Astrophysics Data System (ADS)

Titus, W. J.; Titus, S.; Davis, J. R.

2015-12-01

We present a Bayesian Markov chain Monte Carlo (MCMC) method for the 2D gravity inversion of a localized subsurface object with constant density contrast. Our models have four parameters: the density contrast, the number of vertices in a polygonal approximation of the object, an upper bound on the ratio of the perimeter squared to the area, and the vertices of a polygon container that bounds the object. Reasonable parameter values can be estimated prior to inversion using a forward model and geologic information. In addition, we assume that the field data have a common random uncertainty that lies between two bounds but that it has no systematic uncertainty. Finally, we assume that there is no uncertainty in the spatial locations of the measurement stations. For any set of model parameters, we use MCMC methods to generate an approximate probability distribution of polygons for the object. We then compute various probability distributions for the object, including the variance between the observed and predicted fields (an important quantity in the MCMC method), the area, the center of area, and the occupancy probability (the probability that a spatial point lies within the object). In addition, we compare probabilities of different models using parallel tempering, a technique which also mitigates trapping in local optima that can occur in certain model geometries. We apply our method to several synthetic data sets generated from objects of varying shape and location. We also analyze a natural data set collected across the Rio Grande Gorge Bridge in New Mexico, where the object (i.e. the air below the bridge) is known and the canyon is approximately 2D. Although there are many ways to view results, the occupancy probability proves quite powerful. We also find that the choice of the container is important. In particular, large containers should be avoided, because the more closely a container confines the object, the better the predictions match properties of object.
No evidence for inbreeding avoidance in a natural population of song sparrows (Melospiza melodia).

PubMed

Keller, L F; Arcese, P

1998-09-01

We studied mate choice and inbreeding avoidance a natural population of song sparrows (Melospiza melodia) on Mandarte Island, Canada. Inbreeding occurred regularly: 59% all matings were between known relatives. We tested for inbreeding avoidance by comparing the observed levels of inbreeding to those expected if mate choice had been random with respect to relatedness. Independent of our assumptions about the availability of mates in the random mating model, we found that the expected and observed distributions of inbreeding coefficients were similar, as was the expected and observed frequency of close (f >/= 0.125) inbreeding. Furthermore, there was no difference in relatedness observed pairs and those that would have resulted had birds mated instead with their nearest neighbors. The only evidence to suggest any inbreeding avoidance was a reduced rate of parent-offspring matings as compared to one random mating model but not the other. Hence, despite substantial inbreeding depression in this population, we found little evidence for inbreeding avoidance through mate choice. We present a simple model to suggest that variation in inbreeding avoidance behaviors in birds may arise from differences in survival rates: in species with low survival rates, the costs of forfeiting matings to avoid inbreeding may exceed the costs of inbreeding.
A switching formation strategy for obstacle avoidance of a multi-robot system based on robot priority model.

PubMed

Dai, Yanyan; Kim, YoonGu; Wee, SungGil; Lee, DongHa; Lee, SukGyu

2015-05-01

This paper describes a switching formation strategy for multi-robots with velocity constraints to avoid and cross obstacles. In the strategy, a leader robot plans a safe path using the geometric obstacle avoidance control method (GOACM). By calculating new desired distances and bearing angles with the leader robot, the follower robots switch into a safe formation. With considering collision avoidance, a novel robot priority model, based on the desired distance and bearing angle between the leader and follower robots, is designed during the obstacle avoidance process. The adaptive tracking control algorithm guarantees that the trajectory and velocity tracking errors converge to zero. To demonstrate the validity of the proposed methods, simulation and experiment results present that multi-robots effectively form and switch formation avoiding obstacles without collisions. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.
FMCSA safety program effectiveness measurement: intervention model fiscal year 2009.

DOT National Transportation Integrated Search

2013-04-01

The Federal Motor Carrier Safety Administration (FMCSA), in cooperation with the researcher, has developed an analytic model to measure the effectiveness of roadside inspections and traffic enforcements in terms of crashes avoided, injuries avoided, ...
Context-dependent crypsis: a prey's perspective of a color polymorphic predator.

PubMed

Rodríguez-Morales, D; Rico-Gray, V; García-Franco, J G; Ajuria-Ibarra, H; Hernández-Salazar, L T; Robledo-Ospina, L E; Rao, D

2018-05-12

Many animals use body coloration as a strategy to communicate with conspecifics, prey, and predators. Color is a trade-off for some species, since they should be visible to conspecifics but cryptic to predators and prey. Some flower-dwelling predators, such as crab spiders, are capable of choosing the color of flowers where they ambush flower visitors and pollinators. In order to avoid being captured, visitors evaluate flowers visually before landing. The crab spider Mecaphesa dubia is a polymorphic species (white/purple color morphs), which inhabits the flower heads of a dune plant, Palafoxia lindenii. Using full-spectrum photography of spiders and flowers, we evaluated how honeybees perceived the spiders at different distances. Using visual modeling, we obtained the chromatic and achromatic contrasts of the spiders on flower heads as perceived by honeybees. Purple morphs were found mainly on the receptacle area and white morphs were equally likely to be found in the flowers and receptacle. According to theoretical modeling, white morphs were visible to honeybees from a distance of 10 cm in receptacle area but appeared to be cryptic in the flower area. Purple morphs were cryptic on the receptacle and less so when they were on the flowers. Spiders on flower heads are predicted to be more easily detected by honeybees using chromatic contrast. Our study shows that the conspicuousness of flower dwelling spiders to honeybees depends on the color morph, the distance of observation, and the position of spider on the flower head.
Multi-resolution analysis for region of interest extraction in thermographic nondestructive evaluation

NASA Astrophysics Data System (ADS)

Ortiz-Jaramillo, B.; Fandiño Toro, H. A.; Benitez-Restrepo, H. D.; Orjuela-Vargas, S. A.; Castellanos-Domínguez, G.; Philips, W.

2012-03-01

Infrared Non-Destructive Testing (INDT) is known as an effective and rapid method for nondestructive inspection. It can detect a broad range of near-surface structuring flaws in metallic and composite components. Those flaws are modeled as a smooth contour centered at peaks of stored thermal energy, termed Regions of Interest (ROI). Dedicated methodologies must detect the presence of those ROIs. In this paper, we present a methodology for ROI extraction in INDT tasks. The methodology deals with the difficulties due to the non-uniform heating. The non-uniform heating affects low spatial/frequencies and hinders the detection of relevant points in the image. In this paper, a methodology for ROI extraction in INDT using multi-resolution analysis is proposed, which is robust to ROI low contrast and non-uniform heating. The former methodology includes local correlation, Gaussian scale analysis and local edge detection. In this methodology local correlation between image and Gaussian window provides interest points related to ROIs. We use a Gaussian window because thermal behavior is well modeled by Gaussian smooth contours. Also, the Gaussian scale is used to analyze details in the image using multi-resolution analysis avoiding low contrast, non-uniform heating and selection of the Gaussian window size. Finally, local edge detection is used to provide a good estimation of the boundaries in the ROI. Thus, we provide a methodology for ROI extraction based on multi-resolution analysis that is better or equal compared with the other dedicate algorithms proposed in the state of art.
Context-dependent crypsis: a prey's perspective of a color polymorphic predator

NASA Astrophysics Data System (ADS)

Rodríguez-Morales, D.; Rico-Gray, V.; García-Franco, J. G.; Ajuria-Ibarra, H.; Hernández-Salazar, L. T.; Robledo-Ospina, L. E.; Rao, D.

2018-06-01

Many animals use body coloration as a strategy to communicate with conspecifics, prey, and predators. Color is a trade-off for some species, since they should be visible to conspecifics but cryptic to predators and prey. Some flower-dwelling predators, such as crab spiders, are capable of choosing the color of flowers where they ambush flower visitors and pollinators. In order to avoid being captured, visitors evaluate flowers visually before landing. The crab spider Mecaphesa dubia is a polymorphic species (white/purple color morphs), which inhabits the flower heads of a dune plant, Palafoxia lindenii. Using full-spectrum photography of spiders and flowers, we evaluated how honeybees perceived the spiders at different distances. Using visual modeling, we obtained the chromatic and achromatic contrasts of the spiders on flower heads as perceived by honeybees. Purple morphs were found mainly on the receptacle area and white morphs were equally likely to be found in the flowers and receptacle. According to theoretical modeling, white morphs were visible to honeybees from a distance of 10 cm in receptacle area but appeared to be cryptic in the flower area. Purple morphs were cryptic on the receptacle and less so when they were on the flowers. Spiders on flower heads are predicted to be more easily detected by honeybees using chromatic contrast. Our study shows that the conspicuousness of flower dwelling spiders to honeybees depends on the color morph, the distance of observation, and the position of spider on the flower head.
Habitat selection by Eurasian lynx (Lynx lynx) is primarily driven by avoidance of human activity during day and prey availability during night.

PubMed

Filla, Marc; Premier, Joseph; Magg, Nora; Dupke, Claudia; Khorozyan, Igor; Waltert, Matthias; Bufka, Luděk; Heurich, Marco

2017-08-01

The greatest threat to the protected Eurasian lynx ( Lynx lynx ) in Central Europe is human-induced mortality. As the availability of lynx prey often peaks in human-modified areas, lynx have to balance successful prey hunting with the risk of encounters with humans. We hypothesized that lynx minimize this risk by adjusting habitat choices to the phases of the day and over seasons. We predicted that (1) due to avoidance of human-dominated areas during daytime, lynx range use is higher at nighttime, that (2) prey availability drives lynx habitat selection at night, whereas high cover, terrain inaccessibility, and distance to human infrastructure drive habitat selection during the day, and that (3) habitat selection also differs between seasons, with altitude being a dominant factor in winter. To test these hypotheses, we analyzed telemetry data (GPS, VHF) of 10 lynx in the Bohemian Forest Ecosystem (Germany, Czech Republic) between 2005 and 2013 using generalized additive mixed models and considering various predictor variables. Night ranges exceeded day ranges by more than 10%. At night, lynx selected open habitats, such as meadows, which are associated with high ungulate abundance. By contrast, during the day, lynx selected habitats offering dense understorey cover and rugged terrain away from human infrastructure. In summer, land-cover type greatly shaped lynx habitats, whereas in winter, lynx selected lower altitudes. We concluded that open habitats need to be considered for more realistic habitat models and contribute to future management and conservation (habitat suitability, carrying capacity) of Eurasian lynx in Central Europe.
Adventure Therapy with American Indian Youth. AEE White Papers

ERIC Educational Resources Information Center

Association for Experiential Education (NJ1), 2011

2011-01-01

The American Indian population is a young one; the median age is 28.0, with 34% under 18 years old. In contrast, the median age for the overall U.S. population is 35.3, with 26% younger than 18 (Hawkins, Cummins, & Marlatt, 2004). It is difficult to avoid resorting to statistical hyperbole when describing the problems facing American Indian and…
From "Fear-Based" Choice to "Freedom-Based" Choice: Georgia's Tuition Grants Act, 1960-1997

ERIC Educational Resources Information Center

Wearne, Eric

2013-01-01

Georgia's General Assembly passed the 1961 "Tuition Grants Act" as a method for avoiding school desegregation. In 1993, an Atlanta attorney attempted to use the Act to provide private school vouchers. This study compares and contrasts arguments for and against the Act, and public support for the Act, in 1961 and 1993, using Robinson's…
Explaining the Effect of a Grid by Using an Optical Analog to an X-ray Radiographic Imaging System

ERIC Educational Resources Information Center

Honnicke, M. G.; Gavinho, L.; Cusatis, C.

2008-01-01

Compton scattering and diffuse scattering degenerate the contrast in radiographic images. To avoid such scattering effects, a grid, between the patient and the film is currently used to improve the image quality. Teaching this topic to medical physics students requires demonstration experiments. In this paper, an optical analog to an x-ray…
In Search of the Socially Critical in Health Education: Exploring the Views of Health and Physical Education Preservice Teachers in Australia

ERIC Educational Resources Information Center

Wright, Jan; O'Flynn, Gabrielle; Welch, Rosie

2018-01-01

Purpose: Health education still tends to be dominated by an approach designed to achieve individual behaviour change through the provision of knowledge to avoid risk. In contrast, a critical inquiry approach educates children and young people to develop their capacity to engage critically with knowledge, through reasoning, problem solving and…
Java Architecture for Detect and Avoid Extensibility and Modeling

NASA Technical Reports Server (NTRS)

Santiago, Confesor; Mueller, Eric Richard; Johnson, Marcus A.; Abramson, Michael; Snow, James William

2015-01-01

Unmanned aircraft will equip with a detect-and-avoid (DAA) system that enables them to comply with the requirement to "see and avoid" other aircraft, an important layer in the overall set of procedural, strategic and tactical separation methods designed to prevent mid-air collisions. This paper describes a capability called Java Architecture for Detect and Avoid Extensibility and Modeling (JADEM), developed to prototype and help evaluate various DAA technological requirements by providing a flexible and extensible software platform that models all major detect-and-avoid functions. Figure 1 illustrates JADEM's architecture. The surveillance module can be actual equipment on the unmanned aircraft or simulators that model the process by which sensors on-board detect other aircraft and provide track data to the traffic display. The track evaluation function evaluates each detected aircraft and decides whether to provide an alert to the pilot and its severity. Guidance is a combination of intruder track information, alerting, and avoidance/advisory algorithms behind the tools shown on the traffic display to aid the pilot in determining a maneuver to avoid a loss of well clear. All these functions are designed with a common interface and configurable implementation, which is critical in exploring DAA requirements. To date, JADEM has been utilized in three computer simulations of the National Airspace System, three pilot-in-the-loop experiments using a total of 37 professional UAS pilots, and two flight tests using NASA's Predator-B unmanned aircraft, named Ikhana. The data collected has directly informed the quantitative separation standard for "well clear", safety case, requirements development, and the operational environment for the DAA minimum operational performance standards. This work was performed by the Separation Assurance/Sense and Avoid Interoperability team under NASA's UAS Integration in the NAS project.
The role of negative reinforcement eating expectancies in the relation between experiential avoidance and disinhibition.

PubMed

Schaumberg, Katherine; Schumacher, Leah M; Rosenbaum, Diane L; Kase, Colleen A; Piers, Amani D; Lowe, Michael R; Forman, Evan M; Butryn, Meghan L

2016-04-01

Eating-related disinhibition (i.e., a tendency to overeat in response to various stimuli) is associated with weight gain and poorer long-term weight loss success. Theoretically, experiential avoidance (i.e., the desire or attempts to avoid uncomfortable internal experiences), may predispose individuals to developing negative reinforcement eating expectancies (i.e., the belief that eating will help to mitigate distress), which in turn promote disinhibition. Such relationships are consistent with an acquired preparedness model, which posits that dispositions influence learning and subsequent behavior. Drawing from this framework, the current study represents the first investigation of relations between negative reinforcement eating expectancies, experiential avoidance (both general and food-specific) and disinhibited eating. In particular, the mediating role of negative reinforcement eating expectancies in the relation between experiential avoidance and disinhibited eating was examined. Participants (N=107) were overweight and obese individuals presenting for behavioral weight loss treatment who completed measures of general and food-related experiential avoidance, negative reinforcement eating expectancies, and disinhibition. Experiential avoidance and negative reinforcement eating expectancies significantly related to disinhibition. Furthermore, the relation between experiential avoidance and disinhibition was mediated by negative reinforcement eating expectancies. The current study supports an acquired preparedness model for disinhibition, such that the relation between experiential avoidance and disinhibition is accounted for by expectations that eating will alleviate distress. Findings highlight the potential role of eating expectancies in models accounting for obesity risk, and identify negative reinforcement eating expectancies as a potential treatment target for reducing disinhibition. Copyright © 2016. Published by Elsevier Ltd.
Learning to avoid spiders: fear predicts performance, not competence.

PubMed

Luo, Xijia; Becker, Eni S; Rinck, Mike

2018-01-05

We used an immersive virtual environment to examine avoidance learning in spider-fearful participants. In 3 experiments, participants were asked to repeatedly lift one of 3 virtual boxes, under which either a toy car or a spider appeared and then approached the participant. Participants were not told that the probability of encountering a spider differed across boxes. When the difference was large (Exps. 1 and 2), spider-fearfuls learned to avoid spiders by lifting the few-spiders-box more often and the many-spiders-box less often than non-fearful controls did. However, they hardly managed to do so when the probability differences were small (Exp. 3), and they did not escape from threat more quickly (Exp. 2). In contrast to the observed performance differences, spider-fearfuls and non-fearfuls showed equal competence, that is comparable post-experimental knowledge about the probability to encounter spiders under the 3 boxes. The limitations and implications of the present study are discussed.
Mefloquine in the nucleus accumbens promotes social avoidance and anxiety-like behavior in mice.

PubMed

Heshmati, Mitra; Golden, Sam A; Pfau, Madeline L; Christoffel, Daniel J; Seeley, Elena L; Cahill, Michael E; Khibnik, Lena A; Russo, Scott J

2016-02-01

Mefloquine continues to be a key drug used for malaria chemoprophylaxis and treatment, despite reports of adverse events like depression and anxiety. It is unknown how mefloquine acts within the central nervous system to cause depression and anxiety or why some individuals are more vulnerable. We show that intraperitoneal injection of mefloquine in mice, when coupled to subthreshold social defeat stress, is sufficient to produce depression-like social avoidance behavior. Direct infusion of mefloquine into the nucleus accumbens (NAc), a key brain reward region, increased stress-induced social avoidance and anxiety behavior. In contrast, infusion into the ventral hippocampus had no effect. Whole cell recordings from NAc medium spiny neurons indicated that mefloquine application increases the frequency of spontaneous excitatory postsynaptic currents, a synaptic adaptation that we have previously shown to be associated with increased susceptibility to social defeat stress. Together, these data demonstrate a role for the NAc in mefloquine-induced depression and anxiety-like behaviors. Copyright © 2015 Elsevier Ltd. All rights reserved.
Contrast gain control: a bilinear model for chromatic selectivity.

PubMed

Singer, B; D'Zmura, M

1995-04-01

We report the results of psychophysical experiments on color contrast induction. In earlier work [Vision Res. 34, 3111 (1994)], we showed that modulating the spatial contrast of an annulus in time induces an apparent modulation of the contrast of a central disk, at isoluminance. Here we vary the chromatic properties of disk and annulus systematically in a study of the interactions among the luminance and the color-opponent channels. Results show that induced contrast depends linearly on both disk and annulus contrast, at low and moderate contrast levels. This dependence leads us to propose a bilinear model for color contrast gain control. The model predicts the magnitude and the chromatic properties of induced contrast. In agreement with experimental results, the model displays chromatic selectivity in contrast gain control and a negligible effect of contrast modulation at isoluminance on the appearance of achromatic contrast. We show that the bilinear model for chromatic selectivity may be realized as a feed-forward multiplicative gain control. Data collected at high contrast levels are fit by embellishing the model with saturating nonlinearities in the contrast gain control of each color channel.
Stability of attachment-related anxiety and avoidance and their relationships with the five-factor model and the psychobiological model of personality.

PubMed

Picardi, Angelo; Caroppo, Emanuele; Toni, Alessandro; Bitetti, Daniela; Di Maria, Giuseppe

2005-09-01

The stability of attachment-related anxiety and avoidance and their relationship with influential personality models are issues worth further investigation. Studying discriminant validity with respect to aspects of personality deemed as prevalently heritable, such as temperament, is particularly important. Our aims were to examine the stability of attachment dimensions and to study their relationship with psychological distress, the Big Five factors, and temperament and character dimensions. The Experiences in Close Relationships (ECR) questionnaire, the State-Trait Anxiety Inventory (STAI), the Zung depression scale (ZDS), the Temperament and Character Inventory (TCI-125), and the Big Five Questionnaire (BFQ) were administered to 222 undergraduate and graduate students. After 1 month, 115 participants completed again the ECR, the STAI, and the ZDS. Attachment-related anxiety was modestly correlated with depression and anxiety, while attachment-related avoidance was modestly correlated with depression. The test-retest reliability of ECR scores was high. Changes in attachment-related anxiety were not related to changes in depression or anxiety, and changes in attachment-related avoidance were modestly correlated with changes in depression. In separate multiple regression models also including gender and age, attachment-related anxiety was correlated with harm avoidance, reward dependence, low novelty seeking, low self-directedness and low cooperativeness; low energy/extraversion and low emotional stability; attachment-related avoidance was correlated with low reward dependence and tended to be correlated with low self-directedness. These findings corroborate the reliability and the convergent and discriminant validity of the ECR, and support the notion that the attachment dimensions are only modestly related to psychological distress and are not redundant with constructs developed within influential personality models such as the five-factor model and the psychobiological model.
In-Session Caregiver Behavior Predicts Symptom Change in Youth Receiving Trauma-Focused Cognitive Behavioral Therapy (TF-CBT)

PubMed Central

Yasinski, Carly; Hayes, Adele; Ready, C. Beth; Cummings, Jorden A.; Berman, Ilana S.; McCauley, Thomas; Webb, Charles; Deblinger, Esther

2016-01-01

Objective Involving caregivers in trauma-focused treatments for youth has been shown to result in better outcomes, but it is not clear which in-session caregiver behaviors enhance or inhibit this effect. The current study examined the associations between caregiver behaviors during Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) and youth cognitive processes and symptoms. Method Participants were a racially diverse sample of Medicaid-eligible youth (ages 7–17) and their non-offending caregivers (N= 71 pairs) who received TF-CBT through an effectiveness study in a community setting. Caregiver and youth processes were coded from audio-recorded sessions, and outcomes were measured using the Child Behavior Checklist (CBCL) and UCLA PTSD Reaction Index for DSM-IV (UPID) at 3, 6, 9, and 12 months post-intake. Results Piecewise linear growth curve modeling revealed that during the trauma narrative phase of TF-CBT, caregivers’ cognitive-emotional processing of their own and their child's trauma-related reactions predicted decreases in youth internalizing and externalizing symptoms over treatment. Caregiver support predicted lower internalizing symptoms over follow-up. In contrast, caregiver avoidance and blame of the child predicted worsening of youth internalizing and externalizing symptoms over follow-up. Caregiver avoidance early in treatment also predicted worsening of externalizing symptoms over follow-up. During the narrative phase, caregiver blame and avoidance were correlated with more child overgeneralization of trauma beliefs, and blame was also associated with less child accommodation of balanced beliefs. Conclusions The association between in-session caregiver behaviors and youth symptomatology during and after TF-CBT highlights the importance of assessing and targeting these behaviors to improve clinical outcomes. PMID:27618641

In-session caregiver behavior predicts symptom change in youth receiving trauma-focused cognitive behavioral therapy (TF-CBT).

PubMed

Yasinski, Carly; Hayes, Adele M; Ready, C Beth; Cummings, Jorden A; Berman, Ilana S; McCauley, Thomas; Webb, Charles; Deblinger, Esther

2016-12-01

Involving caregivers in trauma-focused treatments for youth has been shown to result in better outcomes, but it is not clear which in-session caregiver behaviors enhance or inhibit this effect. The current study examined the associations between caregiver behaviors during Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) and youth cognitive processes and symptoms. Participants were a racially diverse sample of Medicaid-eligible youth (ages 7-17) and their nonoffending caregivers (N = 71 pairs) who received TF-CBT through an effectiveness study in a community setting. Caregiver and youth processes were coded from audio-recorded sessions, and outcomes were measured using the Child Behavior Checklist (CBCL) and UCLA PTSD Reaction Index for Diagnostic and Statistical Manual for Mental Disorders-Fourth Edition (DSM-IV; UPID) at 3, 6, 9, and 12 months postintake. Piecewise linear growth curve modeling revealed that during the trauma narrative phase of TF-CBT, caregivers' cognitive-emotional processing of their own and their child's trauma-related reactions predicted decreases in youth internalizing and externalizing symptoms over treatment. Caregiver support predicted lower internalizing symptoms over follow-up. In contrast, caregiver avoidance and blame of the child predicted worsening of youth internalizing and externalizing symptoms over follow-up. Caregiver avoidance early in treatment also predicted worsening of externalizing symptoms over follow-up. During the narrative phase, caregiver blame and avoidance were correlated with more child overgeneralization of trauma beliefs, and blame was also associated with less child accommodation of balanced beliefs. The association between in-session caregiver behaviors and youth symptomatology during and after TF-CBT highlights the importance of assessing and targeting these behaviors to improve clinical outcomes. (PsycINFO Database Record (c) 2016 APA, all rights reserved).
Successful pharmacotherapy for the treatment of severe feeding aversion with mechanistic insights from cross-species neuronal remodeling

PubMed Central

Sharp, W G; Allen, A G; Stubbs, K H; Criado, K K; Sanders, R; McCracken, C E; Parsons, R G; Scahill, L; Gourley, S L

2017-01-01

Pediatric feeding disorders affect up to 5% of children, causing severe food intake problems that can result in serious medical and developmental outcomes. Behavioral intervention (BI) is effective in extinguishing feeding aversions, and also expert-dependent, time/labor-intensive and not well understood at a neurobiological level. Here we first conducted a double-blind, placebo-controlled trial comparing BI with BI plus d-cycloserine (DCS). DCS is a partial N-methyl-d-aspartate (NMDA) receptor agonist shown to augment extinction therapies in multiple anxiety disorders. We examined whether DCS enhanced extinction of feeding aversion in 15 children with avoidant/restrictive food intake disorder (ages 20–58 months). After five treatment days, BI improved feeding by 37%. By contrast, BI+DCS improved feeding by 76%. To gain insight into possible mechanisms of successful intervention, we next tested the neurobiological consequences of DCS in a murine model of feeding aversion and avoidance. In mice with conditioned food aversion, DCS enhanced avoidance extinction across a broad dose range. Confocal fluorescence microscopy and three-dimensional neuronal reconstruction indicated that DCS enlarged dendritic spine heads—the primary sites of excitatory plasticity in the brain—within the orbitofrontal prefrontal cortex, a sensory-cognition integration hub. DCS also increased phosphorylation of the plasticity-associated extracellular signal-regulated kinase 1/2. In summary, DCS successfully augments the extinction of food aversion in children and mice, an effect that may involve plasticity in the orbitofrontal cortex. These results warrant a larger-scale efficacy study of DCS for the treatment of pediatric feeding disorders and further investigations of neural mechanisms. PMID:28632204
Coral snake mimicry: live snakes not avoided by a mammalian predator.

PubMed

Beckers, Gabriel J L; Leenders, Twan A A M; Strijbosch, Henk

1996-06-01

The occurrence of coral snake coloration among unrelated venomous and non-venomous New World snake species has often been explained in terms of warning coloration and mimicry. The idea that snake predators would avoid coral snakes in nature seems widely established and is postulated in many discussions on coral snake mimicry. However, the few workers that have tested a potential aposematic function of the conspicuous colour pattern focused exclusively on behaviour of snake predators towards coloured abstract models. Here we report on behaviour of temporarily caged, wild coatis (Nasua narica) when confronted with co-occurring live snakes, among which were two species of venomous coral snakes. Five different types of responses have been observed, ranging from avoidance to predation, yet none of the coatis avoided either of the two coral snake species or other species resembling these. As in earlier studies coatis appeared to avoid coral snake models, our findings show that results from studies with abstract snake models cannot unconditionally serve as evidence for an aposematic function of coral snake coloration.
Cognitive and neural correlates of depression-like behaviour in socially defeated mice: an animal model of depression with cognitive dysfunction.

PubMed

Yu, Tao; Guo, Ming; Garza, Jacob; Rendon, Samantha; Sun, Xue-Li; Zhang, Wei; Lu, Xin-Yun

2011-04-01

Human depression is associated with cognitive deficits. It is critical to have valid animal models in order to investigate mechanisms and treatment strategies for these associated conditions. The goal of this study was to determine the association of cognitive dysfunction with depression-like behaviour in an animal model of depression and investigate the neural circuits underlying the behaviour. Mice that were exposed to social defeat for 14 d developed depression-like behaviour, i.e. anhedonia and social avoidance as indicated by reduced sucrose preference and decreased social interaction. The assessment of cognitive performance of defeated mice demonstrated impaired working memory in the T-maze continuous alternation task and enhanced fear memory in the contextual and cued fear-conditioning tests. In contrast, reference learning and memory in the Morris water maze test were intact in defeated mice. Neuronal activation following chronic social defeat was investigated by c-fosin-situ hybridization. Defeated mice exhibited preferential neural activity in the prefrontal cortex, cingulate cortex, hippocampal formation, septum, amygdala, and hypothalamic nuclei. Taken together, our results suggest that the chronic social defeat mouse model could serve as a valid animal model to study depression with cognitive impairments. The patterns of neuronal activation provide a neural basis for social defeat-induced changes in behaviour.
Self-concept in fairness and rule establishment during a competitive game: a computational approach

PubMed Central

Lee, Sang Ho; Kim, Sung-Phil; Cho, Yang Seok

2015-01-01

People consider fairness as well as their own interest when making decisions in economic games. The present study proposes a model that encompasses the self-concept determined by one's own kindness as a factor of fairness. To observe behavioral patterns that reflect self-concept and fairness, a chicken game experiment was conducted. Behavioral data demonstrates four distinct patterns; “switching,” “mutual rush,” “mutual avoidance,” and “unfair” patterns. Model estimation of chicken game data shows that a model with self-concept predicts those behaviors better than previous models of fairness, suggesting that self-concept indeed affects human behavior in competitive economic games. Moreover, a non-stationary parameter analysis revealed the process of reaching consensus between the players in a game. When the models were fitted to a continuous time window, the parameters of the players in a pair with “switching” and “mutual avoidance” patterns became similar as the game proceeded, suggesting that the players gradually formed a shared rule during the game. In contrast, the difference of parameters between the players in the “unfair” and “mutual rush” patterns did not become stable. The outcomes of the present study showed that people are likely to change their strategy until they reach a mutually beneficial status. PMID:26441707
Maladaptive behavioral consequences of conditioned fear-generalization: a pronounced, yet sparsely studied, feature of anxiety pathology.

PubMed

van Meurs, Brian; Wiggert, Nicole; Wicker, Isaac; Lissek, Shmuel

2014-06-01

Fear-conditioning experiments in the anxiety disorders focus almost exclusively on passive-emotional, Pavlovian conditioning, rather than active-behavioral, instrumental conditioning. Paradigms eliciting both types of conditioning are needed to study maladaptive, instrumental behaviors resulting from Pavlovian abnormalities found in clinical anxiety. One such Pavlovian abnormality is generalization of fear from a conditioned danger-cue (CS+) to resembling stimuli. Though lab-based findings repeatedly link overgeneralized Pavlovian-fear to clinical anxiety, no study assesses the degree to which Pavlovian overgeneralization corresponds with maladaptive, overgeneralized instrumental-avoidance. The current effort fills this gap by validating a novel fear-potentiated startle paradigm including Pavlovian and instrumental components. The paradigm is embedded in a computer game during which shapes appear on the screen. One shape paired with electric-shock serves as CS+, and other resembling shapes, presented in the absence of shock, serve as generalization stimuli (GSs). During the game, participants choose whether to behaviorally avoid shock at the cost of poorer performance. Avoidance during CS+ is considered adaptive because shock is a real possibility. By contrast, avoidance during GSs is considered maladaptive because shock is not a realistic prospect and thus unnecessarily compromises performance. Results indicate significant Pavlovian-instrumental relations, with greater generalization of Pavlovian fear associated with overgeneralization of maladaptive instrumental-avoidance. Copyright © 2014 Elsevier Ltd. All rights reserved.
Socially acquired predator avoidance: is it just classical conditioning?

PubMed

Griffin, Andrea S

2008-06-15

Associative learning theories presume the existence of a general purpose learning process, the structure of which does not mirror the demands of any particular learning problem. In contrast, learning scientists working within an Evolutionary Biology tradition believe that learning processes have been shaped by ecological demands. One potential means of exploring how ecology may have modified properties of acquisition is to use associative learning theory as a framework within which to analyse a particular learning phenomenon. Recent work has used this approach to examine whether socially transmitted predator avoidance can be conceptualised as a classical conditioning process in which a novel predator stimulus acts as a conditioned stimulus (CS) and acquires control over an avoidance response after it has become associated with alarm signals of social companions, the unconditioned stimulus (US). I review here a series of studies examining the effect of CS/US presentation timing on the likelihood of acquisition. Results suggest that socially acquired predator avoidance may be less sensitive to forward relationships than traditional classical conditioning paradigms. I make the case that socially acquired predator avoidance is an exciting novel one-trial learning paradigm that could be studied along side fear conditioning. Comparisons between social and non-social learning of danger at both the behavioural and neural level may yield a better understanding of how ecology might shape properties and mechanisms of learning.
Nitric oxide facilitates active avoidance learning via enhancement of glutamate levels in the hippocampal dentate gyrus.

PubMed

Wang, Shi; Pan, De-Xi; Wang, Dan; Wan, Peng; Qiu, De-Lai; Jin, Qing-Hua

2014-09-01

The hippocampus is a key structure for learning and memory in mammals, and long-term potentiation (LTP) is an important cellular mechanism responsible for learning and memory. Despite a number of studies indicating that nitric oxide (NO) is involved in the formation and maintenance of LTP as a retrograde messenger, few studies have used neurotransmitter release as a visual indicator in awake animals to explore the role of NO in learning-dependent long-term enhancement of synaptic efficiency. Therefore, in the present study, the effects of l-NMMA (a NO synthase inhibitor) and SNP (a NO donor) on extracellular glutamate (Glu) concentrations and amplitudes of field excitatory postsynaptic potential (fEPSP) were measured in the hippocampal dentate gyrus (DG) region during the acquisition and extinction of active-avoidance behavior in freely-moving conscious rats. In the control group, the extracellular concentration of Glu in the DG was significantly increased during the acquisition of active-avoidance behavior and gradually returned to baseline levels following extinction training. In the experimental group, the change in Glu concentration was significantly reduced by local microinjection of l-NMMA, as was the acquisition of the active-avoidance behavior. In contrast, the change in Glu concentration was significantly enhanced by SNP, and the acquisition of the active-avoidance behavior was significantly accelerated. Furthermore, in all groups, the changes in extracellular Glu were accompanied by corresponding changes in fEPSP amplitude and active-avoidance behavior. Our results suggest that NO in the hippocampal DG facilitates active avoidance learning via enhancements of glutamate levels and synaptic efficiency in rats. Copyright © 2014 Elsevier B.V. All rights reserved.
Response inhibition predicts painful task duration and performance in healthy individuals performing a cold pressor task in a motivational context.

PubMed

Karsdorp, P A; Geenen, R; Vlaeyen, J W S

2014-01-01

Long-term avoidance of painful activities has shown to be dysfunctional in chronic pain. Pain may elicit escape or avoidance responses automatically, particularly when pain-related fear is high. A conflict may arise between opposing short-term escape/avoidance goals to reduce pain and long-term approach goals to receive a reward. An inhibitory control system may resolve this conflict. It was hypothesized that reduced response inhibition would be associated with greater escape/avoidance during pain, particularly among subjects with higher pain-related fear. Response inhibition was measured with the stop-signal task, and pain-related fear with the Fear of Pain Questionnaire. Participants completed a tone-detection task (TDT) in which they could earn money while being exposed to cold pressor pain. Escape/avoidance was operationalized as the hand immersion time during a cold pressor task (CPT) and the performance on the TDT. Poorer response inhibition was associated with shorter CPT immersion duration and with worse TDT performance. Pain after the CPT was associated with pain-related fear, but not with response inhibition. No supportive evidence was found for the hypothesis that the relation between inhibition and escape/avoidance would be most pronounced for those with higher pain-related fear. In contrast, the relation between response inhibition and number of hits on the TDT was most pronounced for those with lower pain-related fear. The findings suggest that individuals with a stronger ability to inhibit responses in a stop-signal task are better able to inhibit escape/avoidance responses elicited by pain, in the service of a conflicting approach goal. © 2013 European Pain Federation - EFIC®
Masculinity impediments: Internalized masculinity contributes to healthcare avoidance in men and women.

PubMed

Himmelstein, Mary S; Sanchez, Diana T

2016-07-01

Gender beliefs contribute to men's healthcare avoidance, but little research examines these outcomes in women. This article models healthcare avoidance related to masculine contingencies of self-worth in men and women. Nested path modelling tested relationships between social role beliefs, masculine contingencies of self-worth, barriers to help seeking and avoidance of health care in university and non-university-student adult samples. Results indicated social role beliefs predicted masculine contingencies of self-worth in men but not in women. Regardless of gender, masculine contingencies of self-worth predicted barriers to help seeking, which predicted healthcare avoidance in both men and women. Thus, masculine contingencies of self-worth have downstream consequences for men and women through barriers to help seeking. © The Author(s) 2014.
Functional network organizations of two contrasting temperament groups in dimensions of novelty seeking and harm avoidance.

PubMed

Kyeong, Sunghyon; Kim, Eunjoo; Park, Hae-Jeong; Hwang, Dong-Uk

2014-08-05

Novelty seeking (NS) and harm avoidance (HA) are two major dimensions of temperament in Cloninger׳s neurobiological model of personality. Previous neurofunctional and biological studies on temperament dimensions of HA and NS suggested that the temperamental traits have significant correlations with cortical and subcortical brain regions. However, no study to date has investigated the functional network modular organization as a function of the temperament dimension. The temperament dimensions were originally proposed to be independent of one another. However, a meta-analysis based on 16 published articles found a significant negative correlation between HA and NS (Miettunen et al., 2008). Based on this negative correlation, the current study revealed the whole-brain connectivity modular architecture for two contrasting temperament groups. The k-means clustering algorithm, with the temperamental traits of HA and NS as an input, was applied to divide the 40 subjects into two temperament groups: 'high HA and low NS' versus 'low HA and high NS'. Using the graph theoretical framework, we found a functional segregation of whole brain network architectures derived from resting-state functional MRI. In the 'high HA and low NS' group, the regulatory brain regions, such as the prefrontal cortex (PFC), are clustered together with the limbic system. In the 'low HA and high NS' group, however, brain regions lying on the dopaminergic pathways, such as the PFC and basal ganglia, are partitioned together. These findings suggest that the neural basis of inhibited, passive, and inactive behaviors in the 'high HA and low NS' group was derived from the increased network associations between the PFC and limbic clusters. In addition, supporting evidence of topological differences between the two temperament groups was found by analyzing the functional connectivity density and gray matter volume, and by computing the relationships between the morphometry and function of the brain. Copyright © 2014 Elsevier B.V. All rights reserved.
What Happens after Inbreeding Avoidance? Inbreeding by Rejected Relatives and the Inclusive Fitness Benefit of Inbreeding Avoidance

PubMed Central

Duthie, A. Bradley; Reid, Jane M.

2015-01-01

Avoiding inbreeding, and therefore avoiding inbreeding depression in offspring fitness, is widely assumed to be adaptive in systems with biparental reproduction. However, inbreeding can also confer an inclusive fitness benefit stemming from increased relatedness between parents and inbred offspring. Whether or not inbreeding or avoiding inbreeding is adaptive therefore depends on a balance between inbreeding depression and increased parent-offspring relatedness. Existing models of biparental inbreeding predict threshold values of inbreeding depression above which males and females should avoid inbreeding, and predict sexual conflict over inbreeding because these thresholds diverge. However, these models implicitly assume that if a focal individual avoids inbreeding, then both it and its rejected relative will subsequently outbreed. We show that relaxing this assumption of reciprocal outbreeding, and the assumption that focal individuals are themselves outbred, can substantially alter the predicted thresholds for inbreeding avoidance for focal males. Specifically, the magnitude of inbreeding depression below which inbreeding increases a focal male’s inclusive fitness increases with increasing depression in the offspring of a focal female and her alternative mate, and it decreases with increasing relatedness between a focal male and a focal female’s alternative mate, thereby altering the predicted zone of sexual conflict. Furthermore, a focal male’s inclusive fitness gain from avoiding inbreeding is reduced by indirect opportunity costs if his rejected relative breeds with another relative of his. By demonstrating that variation in relatedness and inbreeding can affect intra- and inter-sexual conflict over inbreeding, our models lead to novel predictions for family dynamics. Specifically, parent-offspring conflict over inbreeding might depend on the alternative mates of rejected relatives, and male-male competition over inbreeding might lead to mixed inbreeding strategies. Making testable quantitative predictions regarding inbreeding strategies occurring in nature will therefore require new models that explicitly capture variation in relatedness and inbreeding among interacting population members. PMID:25909185
Post-traumatic stress disorder, social anxiety disorder, and depression in survivors of the Kosovo War: Experiential avoidance as a contributor to distress and quality of life

PubMed Central

Kashdan, Todd B.; Morina, Nexhmedin; Priebe, Stefan

2009-01-01

Few studies have been conducted on psychological disorders other than post-traumatic stress disorder (PTSD) in war survivors. The aim of this study was to examine PTSD, social anxiety disorder (SAD), and major depressive disorder (MDD) and their associations with distress and quality of life in 174 Albanian civilian survivors of the Kosovo war. This included testing of conceptual models suggesting that experiential avoidance might influence associations between anxiety and mood disorders with psychological functioning. Each of the three psychiatric disorders was associated with greater experiential avoidance and psychological distress, and lower quality of life. Being a refugee was associated with a higher likelihood of having SAD and MDD. We found evidence for experiential avoidance as a partial mediator of the respective effects of SAD and PTSD on quality of life; experiential avoidance did not mediate the effects of disorders on global distress. We also found support for a moderation model showing that only war survivors without SAD and low experiential avoidance reported elevated quality of life; people with either SAD or excessive reliance on experiential avoidance reported compromised, low quality of life. This is the third independent study, each using a different methodology, to find empirical support for this moderation model (Kashdan & Breen, 2008; Kashdan & Steger, 2006). Overall, we provided initial evidence for the importance of addressing PTSD, SAD, MDD, and experiential avoidance in primarily civilian war survivors. PMID:18676121
Venturing out safely: The biogeography of Homo erectus dispersal out of Africa.

PubMed

Carotenuto, F; Tsikaridze, N; Rook, L; Lordkipanidze, D; Longo, Laura; Condemi, Silvana; Raia, P

2016-06-01

The dispersal of Homo erectus out of Africa at some 1.9 million years ago is one of the most important, crucial, and yet controversial events in human evolution. Current opinions about this episode expose the contrast between those who see H. erectus as a highly social, cooperative species seeking out new ecological opportunities to exploit, and those preferring a passive, climate driven explanation for such an event. By using geostatistics techniques and probabilistic models, we characterised the ecological context of H. erectus dispersal, from its East African origin to the colonization of Eurasia, taking into account both the presence of other large mammals and the physical characteristics of the landscape as potential factors. Our model indicated that H. erectus followed almost passively the large herbivore fauna during its dispersal. In Africa, the dispersal was statistically associated with the presence of large freshwater bodies (Rift Valley Lakes). In Eurasia, the presence of H. erectus was associated with the occurrence of geological outcrops likely yielding unconsolidated flint. During the early phase of dispersal, our model indicated that H. erectus actively avoided areas densely populated by large carnivores. This pattern weakened as H. erectus dispersed over Europe, possibly because of the decreasing presence of carnivores there plus the later acquisition of Acheulean technology. During this later phase, H. erectus was associated with limestone and shaley marl, and seems to have been selecting for high-elevation sites. While our results do not directly contradict the idea that H. erectus may have been an active hunter, they clearly point to the fact that predator avoidance may have conditioned its long-distance diffusion as it moved outside Africa. The modelled dispersal route suggests that H. erectus remained preferentially associated with low/middle latitude (i.e., comparatively warm) sites throughout its colonization history. Copyright © 2016 Elsevier Ltd. All rights reserved.
Prediction of intrinsic motivation and sports performance using 2 x 2 achievement goal framework.

PubMed

Li, Chiung-Huang; Chi, Likang; Yeh, Suh-Ruu; Guo, Kwei-Bin; Ou, Cheng-Tsung; Kao, Chun-Chieh

2011-04-01

The purpose of this study was to examine the influence of 2 x 2 achievement goals on intrinsic motivation and performance in handball. Participants were 164 high school athletes. All completed the 2 x 2 Achievement Goals Questionnaire for Sport and the Intrinsic Motivation subscale of the Sport Motivation Scale; the coach for each team rated his athletes' overall sports performance. Using simultaneous-regression analyses, mastery-approach goals positively predicted both intrinsic motivation and performance in sports, whereas performance-avoidance goals negatively predicted sports performance. These results suggest that athletes who pursue task mastery and improvement of their competence perform well and enjoy their participation. In contrast, those who focus on avoiding normative incompetence perform poorly.
Binocular contrast discrimination needs monocular multiplicative noise

PubMed Central

Ding, Jian; Levi, Dennis M.

2016-01-01

The effects of signal and noise on contrast discrimination are difficult to separate because of a singularity in the signal-detection-theory model of two-alternative forced-choice contrast discrimination (Katkov, Tsodyks, & Sagi, 2006). In this article, we show that it is possible to eliminate the singularity by combining that model with a binocular combination model to fit monocular, dichoptic, and binocular contrast discrimination. We performed three experiments using identical stimuli to measure the perceived phase, perceived contrast, and contrast discrimination of a cyclopean sine wave. In the absence of a fixation point, we found a binocular advantage in contrast discrimination both at low contrasts (<4%), consistent with previous studies, and at high contrasts (≥34%), which has not been previously reported. However, control experiments showed no binocular advantage at high contrasts in the presence of a fixation point or for observers without accommodation. We evaluated two putative contrast-discrimination mechanisms: a nonlinear contrast transducer and multiplicative noise (MN). A binocular combination model (the DSKL model; Ding, Klein, & Levi, 2013b) was first fitted to both the perceived-phase and the perceived-contrast data sets, then combined with either the nonlinear contrast transducer or the MN mechanism to fit the contrast-discrimination data. We found that the best model combined the DSKL model with early MN. Model simulations showed that, after going through interocular suppression, the uncorrelated noise in the two eyes became anticorrelated, resulting in less binocular noise and therefore a binocular advantage in the discrimination task. Combining a nonlinear contrast transducer or MN with a binocular combination model (DSKL) provides a powerful method for evaluating the two putative contrast-discrimination mechanisms. PMID:26982370
Binocular contrast discrimination needs monocular multiplicative noise.

PubMed

Ding, Jian; Levi, Dennis M

2016-01-01

The effects of signal and noise on contrast discrimination are difficult to separate because of a singularity in the signal-detection-theory model of two-alternative forced-choice contrast discrimination (Katkov, Tsodyks, & Sagi, 2006). In this article, we show that it is possible to eliminate the singularity by combining that model with a binocular combination model to fit monocular, dichoptic, and binocular contrast discrimination. We performed three experiments using identical stimuli to measure the perceived phase, perceived contrast, and contrast discrimination of a cyclopean sine wave. In the absence of a fixation point, we found a binocular advantage in contrast discrimination both at low contrasts (<4%), consistent with previous studies, and at high contrasts (≥34%), which has not been previously reported. However, control experiments showed no binocular advantage at high contrasts in the presence of a fixation point or for observers without accommodation. We evaluated two putative contrast-discrimination mechanisms: a nonlinear contrast transducer and multiplicative noise (MN). A binocular combination model (the DSKL model; Ding, Klein, & Levi, 2013b) was first fitted to both the perceived-phase and the perceived-contrast data sets, then combined with either the nonlinear contrast transducer or the MN mechanism to fit the contrast-discrimination data. We found that the best model combined the DSKL model with early MN. Model simulations showed that, after going through interocular suppression, the uncorrelated noise in the two eyes became anticorrelated, resulting in less binocular noise and therefore a binocular advantage in the discrimination task. Combining a nonlinear contrast transducer or MN with a binocular combination model (DSKL) provides a powerful method for evaluating the two putative contrast-discrimination mechanisms.
Associating crash avoidance maneuvers with driver attributes and accident characteristics: a mixed logit model approach.

PubMed

Kaplan, Sigal; Prato, Carlo Giacomo

2012-01-01

The current study focuses on the propensity of drivers to engage in crash avoidance maneuvers in relation to driver attributes, critical events, crash characteristics, vehicles involved, road characteristics, and environmental conditions. The importance of avoidance maneuvers derives from the key role of proactive and state-aware road users within the concept of sustainable safety systems, as well as from the key role of effective corrective maneuvers in the success of automated in-vehicle warning and driver assistance systems. The analysis is conducted by means of a mixed logit model that represents the selection among 5 emergency lateral and speed control maneuvers (i.e., "no avoidance maneuvers," "braking," "steering," "braking and steering," and "other maneuvers) while accommodating correlations across maneuvers and heteroscedasticity. Data for the analysis were retrieved from the General Estimates System (GES) crash database for the year 2009 by considering drivers for which crash avoidance maneuvers are known. The results show that (1) the nature of the critical event that made the crash imminent greatly influences the choice of crash avoidance maneuvers, (2) women and elderly have a relatively lower propensity to conduct crash avoidance maneuvers, (3) drowsiness and fatigue have a greater negative marginal effect on the tendency to engage in crash avoidance maneuvers than alcohol and drug consumption, (4) difficult road conditions increase the propensity to perform crash avoidance maneuvers, and (5) visual obstruction and artificial illumination decrease the probability to carry out crash avoidance maneuvers. The results emphasize the need for public awareness campaigns to promote safe driving style for senior drivers and warning about the risks of driving under fatigue and distraction being comparable to the risks of driving under the influence of alcohol and drugs. Moreover, the results suggest the need to educate drivers about hazard perception, designing a forgiving infrastructure within a sustainable safety systems, and rethinking in-vehicle collision warning systems. Future research should address the effectiveness of crash avoidance maneuvers and joint modeling of maneuver selection and crash severity.
Towards social autonomous vehicles: Efficient collision avoidance scheme using Richardson's arms race model.

PubMed

Riaz, Faisal; Niazi, Muaz A

2017-01-01

This paper presents the concept of a social autonomous agent to conceptualize such Autonomous Vehicles (AVs), which interacts with other AVs using social manners similar to human behavior. The presented AVs also have the capability of predicting intentions, i.e. mentalizing and copying the actions of each other, i.e. mirroring. Exploratory Agent Based Modeling (EABM) level of the Cognitive Agent Based Computing (CABC) framework has been utilized to design the proposed social agent. Furthermore, to emulate the functionality of mentalizing and mirroring modules of proposed social agent, a tailored mathematical model of the Richardson's arms race model has also been presented. The performance of the proposed social agent has been validated at two levels-firstly it has been simulated using NetLogo, a standard agent-based modeling tool and also, at a practical level using a prototype AV. The simulation results have confirmed that the proposed social agent-based collision avoidance strategy is 78.52% more efficient than Random walk based collision avoidance strategy in congested flock-like topologies. Whereas practical results have confirmed that the proposed scheme can avoid rear end and lateral collisions with the efficiency of 99.876% as compared with the IEEE 802.11n-based existing state of the art mirroring neuron-based collision avoidance scheme.
Towards social autonomous vehicles: Efficient collision avoidance scheme using Richardson’s arms race model

PubMed Central

Niazi, Muaz A.

2017-01-01

This paper presents the concept of a social autonomous agent to conceptualize such Autonomous Vehicles (AVs), which interacts with other AVs using social manners similar to human behavior. The presented AVs also have the capability of predicting intentions, i.e. mentalizing and copying the actions of each other, i.e. mirroring. Exploratory Agent Based Modeling (EABM) level of the Cognitive Agent Based Computing (CABC) framework has been utilized to design the proposed social agent. Furthermore, to emulate the functionality of mentalizing and mirroring modules of proposed social agent, a tailored mathematical model of the Richardson’s arms race model has also been presented. The performance of the proposed social agent has been validated at two levels–firstly it has been simulated using NetLogo, a standard agent-based modeling tool and also, at a practical level using a prototype AV. The simulation results have confirmed that the proposed social agent-based collision avoidance strategy is 78.52% more efficient than Random walk based collision avoidance strategy in congested flock-like topologies. Whereas practical results have confirmed that the proposed scheme can avoid rear end and lateral collisions with the efficiency of 99.876% as compared with the IEEE 802.11n-based existing state of the art mirroring neuron-based collision avoidance scheme. PMID:29040294

The mechanisms underlying overgeneral autobiographical memory: an evaluative review of evidence for the CaR-FA-X model.

PubMed

Sumner, Jennifer A

2012-02-01

Overgeneral autobiographical memory (OGM) has been found to be an important cognitive phenomenon with respect to depression and trauma-related psychopathology (e.g., posttraumatic stress disorder), and researchers have been interested in better understanding the factors that contribute to this proposed vulnerability factor. The most prominent model of mechanisms underlying OGM to date is Williams et al.'s (2007) CaR-FA-X model. This model proposes that three processes influence OGM: capture and rumination, functional avoidance, and impaired executive control. The author reviews the current state of support for the CaR-FA-X model by evaluating 38 studies that have examined OGM and one or more mechanisms of the model. Collectively, these studies reveal robust support for associations between OGM and both rumination and impaired executive control. OGM also appears to be a cognitive avoidance strategy, and there is evidence that avoiding the retrieval of specific memories reduces distress after an aversive event, at least in the short term. Important issues that have been left unresolved are highlighted, including the nature of the capture phenomenon, the role of trauma in functional avoidance, and the developmental nature of functional avoidance. Recommendations for future research that will enhance understanding of the factors that contribute to OGM are suggested. Copyright © 2011 Elsevier Ltd. All rights reserved.
Using signals associated with safety in avoidance learning: computational model of sex differences

PubMed Central

Beck, Kevin D.; Pang, Kevin C.H.; Myers, Catherine E.

2015-01-01

Avoidance behavior involves learning responses that prevent upcoming aversive events; these responses typically extinguish when the aversive events stop materializing. Stimuli that signal safety from aversive events can paradoxically inhibit extinction of avoidance behavior. In animals, males and females process safety signals differently. These differences help explain why women are more likely to be diagnosed with an anxiety disorder and exhibit differences in symptom presentation and course compared to men. In the current study, we extend an existing model of strain differences in avoidance behavior to simulate sex differences in rats. The model successfully replicates data showing that the omission of a signal associated with a period of safety can facilitate extinction in females, but not males, and makes novel predictions that this effect should depend on the duration of the period, the duration of the signal itself, and its occurrence within that period. Non-reinforced responses during the safe period were also found to be important in the expression of these patterns. The model also allowed us to explore underlying mechanisms for the observed sex effects, such as whether safety signals serve as occasion setters for aversive events, to determine why removing them can facilitate extinction of avoidance. The simulation results argue against this account, and instead suggest the signal may serve as a conditioned reinforcer of avoidance behavior. PMID:26213650
DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, J. Y.; Riley, W. J.

We present a generic flux limiter to account for mass limitations from an arbitrary number of substrates in a biogeochemical reaction network. The flux limiter is based on the observation that substrate (e.g., nitrogen, phosphorus) limitation in biogeochemical models can be represented as to ensure mass conservative and non-negative numerical solutions to the governing ordinary differential equations. Application of the flux limiter includes two steps: (1) formulation of the biogeochemical processes with a matrix of stoichiometric coefficients and (2) application of Liebig's law of the minimum using the dynamic stoichiometric relationship of the reactants. This approach contrasts with the ad hoc down-regulationmore » approaches that are implemented in many existing models (such as CLM4.5 and the ACME (Accelerated Climate Modeling for Energy) Land Model (ALM)) of carbon and nutrient interactions, which are error prone when adding new processes, even for experienced modelers. Through an example implementation with a CENTURY-like decomposition model that includes carbon, nitrogen, and phosphorus, we show that our approach (1) produced almost identical results to that from the ad hoc down-regulation approaches under non-limiting nutrient conditions, (2) properly resolved the negative solutions under substrate-limited conditions where the simple clipping approach failed, (3) successfully avoided the potential conceptual ambiguities that are implied by those ad hoc down-regulation approaches. We expect our approach will make future biogeochemical models easier to improve and more robust.« less
On avoided words, absent words, and their application to biological sequence analysis.

PubMed

Almirantis, Yannis; Charalampopoulos, Panagiotis; Gao, Jia; Iliopoulos, Costas S; Mohamed, Manal; Pissis, Solon P; Polychronopoulos, Dimitris

2017-01-01

The deviation of the observed frequency of a word w from its expected frequency in a given sequence x is used to determine whether or not the word is avoided . This concept is particularly useful in DNA linguistic analysis. The value of the deviation of w , denoted by [Formula: see text], effectively characterises the extent of a word by its edge contrast in the context in which it occurs. A word w of length [Formula: see text] is a [Formula: see text]-avoided word in x if [Formula: see text], for a given threshold [Formula: see text]. Notice that such a word may be completely absent from x . Hence, computing all such words naïvely can be a very time-consuming procedure, in particular for large k . In this article, we propose an [Formula: see text]-time and [Formula: see text]-space algorithm to compute all [Formula: see text]-avoided words of length k in a given sequence of length n over a fixed-sized alphabet. We also present a time-optimal [Formula: see text]-time algorithm to compute all [Formula: see text]-avoided words (of any length) in a sequence of length n over an integer alphabet of size [Formula: see text]. In addition, we provide a tight asymptotic upper bound for the number of [Formula: see text]-avoided words over an integer alphabet and the expected length of the longest one. We make available an implementation of our algorithm. Experimental results, using both real and synthetic data, show the efficiency and applicability of our implementation in biological sequence analysis. The systematic search for avoided words is particularly useful for biological sequence analysis. We present a linear-time and linear-space algorithm for the computation of avoided words of length k in a given sequence x . We suggest a modification to this algorithm so that it computes all avoided words of x , irrespective of their length, within the same time complexity. We also present combinatorial results with regards to avoided words and absent words.
Path-Integral Monte Carlo Determination of the Fourth-Order Virial Coefficient for a Unitary Two-Component Fermi Gas with Zero-Range Interactions

NASA Astrophysics Data System (ADS)

Yan, Yangqian; Blume, D.

2016-06-01

The unitary equal-mass Fermi gas with zero-range interactions constitutes a paradigmatic model system that is relevant to atomic, condensed matter, nuclear, particle, and astrophysics. This work determines the fourth-order virial coefficient b4 of such a strongly interacting Fermi gas using a customized ab initio path-integral Monte Carlo (PIMC) algorithm. In contrast to earlier theoretical results, which disagreed on the sign and magnitude of b4 , our b4 agrees within error bars with the experimentally determined value, thereby resolving an ongoing literature debate. Utilizing a trap regulator, our PIMC approach determines the fourth-order virial coefficient by directly sampling the partition function. An on-the-fly antisymmetrization avoids the Thomas collapse and, combined with the use of the exact two-body zero-range propagator, establishes an efficient general means to treat small Fermi systems with zero-range interactions.
Prosody and parsing in coordination structures.

PubMed

Schepman, A; Rodway, P

2000-05-01

The effect of prosodic boundary cues on the off-line disambiguation and on-line parsing of coordination structures was examined. It was found that relative clauses were attached to coordinated object noun phrases in preference to second conjuncts in sentences like: The lawyer greeted the powerful barrister and the wise judge who was/were walking to the courtroom. Naive speakers signalled the syntactic contrast between the two structures by a prosodic break between the conjuncts when the relative clause was attached to the second conjunct. Listeners were able to use this prosodic information in both off-line syntactic disambiguation and on-line syntactic parsing. The findings are compatible with a model in which prosody has a strong immediate effect on parsing. It is argued that the current experimental design has avoided confounds present in earlier studies on the on-line integration of prosodic and syntactic information.
Turbulent boundary layer on a convex, curved surface

NASA Technical Reports Server (NTRS)

Gillis, J. C.; Johnston, J. P.; Kays, W. M.; Moffat, R. J.

1980-01-01

The effects of strong convex curvature on boundary layer turbulence were investigated. The data gathered on the behavior of Reynolds stress suggested the formulation of a simple turbulence model. Three sets of data were taken on two separate facilities. Both rigs had flow from a flat surface, over a convex surface with 90 deg of turning, and then onto a flat recovery surface. The geometry was adjusted so that, for both rigs, the pressure gradient along the test surface was zero - thus avoiding any effects of streamwise acceleration on the wall layers. Results show that after a sudden introduction of curvature, the shear stress in the outer part of the boundary layer is sharply diminished and is even slightly negative near the edge. The wall shear also drops off quickly downstream. In contrast, when the surface suddenly becomes flat again, the wall shear and shear stress profiles recover very slowly towards flat wall conditions.
Challenging Nurses’ Cultural Competence of Disability to Improve Interpersonal Interactions

PubMed Central

Roscigno, Cecelia I.

2013-01-01

Worldwide, at least 6.9 billion people have an impairment producing health condition (IPHC). Insensitive encounters with health care providers (HCPs) can result in negative appraisals, fear, and avoidance, but little is known about what things are commonly perceived as insensitive. A review of published narratives describing negative encounters with HCPs was conducted. Narrative analysis was used to compare, contrast, and synthesize six themes describing the common negative encounters: (a) ignoring or minimizing their knowledge; (b) detached interpersonal interactions; (c) placing a negative skew on their life quality; (d) a lack of HCP knowledge related to their complete needs; (e) assuming they should be asexual and childless; and, (f) an inherent power differential. The medical model of disability is perceived by individuals with IPHCs to inform negative encounters perceived as insensitive. This preliminary knowledge is important so we can address education needs, plan future research questions, and establish clinical practice improvements. PMID:23291869
The habenula encodes negative motivational value associated with primary punishment in humans.

PubMed

Lawson, Rebecca P; Seymour, Ben; Loh, Eleanor; Lutti, Antoine; Dolan, Raymond J; Dayan, Peter; Weiskopf, Nikolaus; Roiser, Jonathan P

2014-08-12

Learning what to approach, and what to avoid, involves assigning value to environmental cues that predict positive and negative events. Studies in animals indicate that the lateral habenula encodes the previously learned negative motivational value of stimuli. However, involvement of the habenula in dynamic trial-by-trial aversive learning has not been assessed, and the functional role of this structure in humans remains poorly characterized, in part, due to its small size. Using high-resolution functional neuroimaging and computational modeling of reinforcement learning, we demonstrate positive habenula responses to the dynamically changing values of cues signaling painful electric shocks, which predict behavioral suppression of responses to those cues across individuals. By contrast, negative habenula responses to monetary reward cue values predict behavioral invigoration. Our findings show that the habenula plays a key role in an online aversive learning system and in generating associated motivated behavior in humans.
Modeling the risk of phosphorus runoff following single and split phosphorus fertilizer applications in two contrasting catchments.

PubMed

Burkitt, Lucy L; Dougherty, Warwick J; Corkrey, Ross; Broad, Shane T

2011-01-01

The potential loss of P in runoff is a function of the combined effects of fertilizer-soil interactions and climatic characteristics. In this study, we applied a Bayesian approach to experimental data to model the annualized long-term risk of P runoff following single and split P fertilizer applications using two example catchments with contrasting rainfall/runoff patterns. Split P fertilizer strategies are commonly used in intensive pasture production in Australia and our results showed that three applications of 13.3 kg P ha(-1) resulted in a greater risk of P runoff compared with a single application of 40 kg P ha(-1) when long-term surface runoff data were incorporated into a Bayesian P risk model. Splitting P fertilizer applications increased the likelihood of a coincidence of fertilizer application and runoff occurring. We found that the overall risk of P runoff is also increased in catchments where the rainfall/runoff pattern is less predictable, compared with catchments where rainfall/runoff is winter dominant. The findings of our study also question the effectiveness of current recommendations to avoid applying fertilizer if runoff is likely to occur in the next few days, as we found that total P concentrations at the half-life were still very high (18.2 and 8.2 mg P L(-1)) following single and split P treatments, respectively. Data from the current study also highlight that omitting P fertilizer on soils that already have adequate soil test P concentrations is an effective method of reducing P loss in surface runoff. If P fertilizer must be applied, we recommend less frequent applications and only during periods of the year when the risk of surface P runoff is low.
Rapid Catalyst Capture Enables Metal-Free para-Hydrogen-Based Hyperpolarized Contrast Agents.

PubMed

Barskiy, Danila A; Ke, Lucia A; Li, Xingyang; Stevenson, Vincent; Widarman, Nevin; Zhang, Hao; Truxal, Ashley; Pines, Alexander

2018-05-10

Hyperpolarization techniques based on the use of para-hydrogen provide orders of magnitude signal enhancement for magnetic resonance spectroscopy and imaging. The main drawback limiting widespread applicability of para-hydrogen-based techniques in biomedicine is the presence of organometallic compounds (the polarization transfer catalysts) in solution with hyperpolarized contrast agents. These catalysts are typically complexes of platinum-group metals, and their administration in vivo should be avoided. Herein, we show how extraction of a hyperpolarized compound from an organic phase to an aqueous phase combined with a rapid (less than 10 s) Ir-based catalyst capture by metal scavenging agents can produce pure para-hydrogen-based hyperpolarized contrast agents, as demonstrated by high-resolution nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The presented methodology enables fast and efficient means of producing pure hyperpolarized aqueous solutions for biomedical and other uses.
Flow-gated radial phase-contrast imaging in the presence of weak flow.

PubMed

Peng, Hsu-Hsia; Huang, Teng-Yi; Wang, Fu-Nien; Chung, Hsiao-Wen

2013-01-01

To implement a flow-gating method to acquire phase-contrast (PC) images of carotid arteries without use of an electrocardiography (ECG) signal to synchronize the acquisition of imaging data with pulsatile arterial flow. The flow-gating method was realized through radial scanning and sophisticated post-processing methods including downsampling, complex difference, and correlation analysis to improve the evaluation of flow-gating times in radial phase-contrast scans. Quantitatively comparable results (R = 0.92-0.96, n = 9) of flow-related parameters, including mean velocity, mean flow rate, and flow volume, with conventional ECG-gated imaging demonstrated that the proposed method is highly feasible. The radial flow-gating PC imaging method is applicable in carotid arteries. The proposed flow-gating method can potentially avoid the setting up of ECG-related equipment for brain imaging. This technique has potential use in patients with arrhythmia or weak ECG signals.
Carbon source-sink limitations differ between two species with contrasting growth strategies.

PubMed

Burnett, Angela C; Rogers, Alistair; Rees, Mark; Osborne, Colin P

2016-11-01

Understanding how carbon source and sink strengths limit plant growth is a critical knowledge gap that hinders efforts to maximize crop yield. We investigated how differences in growth rate arise from source-sink limitations, using a model system comparing a fast-growing domesticated annual barley (Hordeum vulgare cv. NFC Tipple) with a slow-growing wild perennial relative (Hordeum bulbosum). Source strength was manipulated by growing plants at sub-ambient and elevated CO 2 concentrations ([CO 2 ]). Limitations on vegetative growth imposed by source and sink were diagnosed by measuring relative growth rate, developmental plasticity, photosynthesis and major carbon and nitrogen metabolite pools. Growth was sink limited in the annual but source limited in the perennial. RGR and carbon acquisition were higher in the annual, but photosynthesis responded weakly to elevated [CO 2 ] indicating that source strength was near maximal at current [CO 2 ]. In contrast, photosynthetic rate and sink development responded strongly to elevated [CO 2 ] in the perennial, indicating significant source limitation. Sink limitation was avoided in the perennial by high sink plasticity: a marked increase in tillering and root:shoot ratio at elevated [CO 2 ], and lower non-structural carbohydrate accumulation. Alleviating sink limitation during vegetative development could be important for maximizing growth of elite cereals under future elevated [CO 2 ]. © 2016 John Wiley & Sons Ltd.
Giant lipid vesicles under electric field pulses assessed by non invasive imaging.

PubMed

Mauroy, Chloé; Portet, Thomas; Winterhalder, Martin; Bellard, Elisabeth; Blache, Marie-Claire; Teissié, Justin; Zumbusch, Andreas; Rols, Marie-Pierre

2012-10-01

We present experimental results regarding the effects of electric pulses on giant unilamellar vesicles (GUVs). We have used phase contrast and coherent anti-Stokes Raman scattering (CARS) microscopy as relevant optical approaches to gain insight into membrane changes under electropermeabilization. No addition of exogenous molecules (lipid analogue, fluorescent dye) was needed. Therefore, experiments were performed on pure lipid systems avoiding possible artefacts linked to their use. Structural membrane changes were assessed by loss of contrast inside the GUVs due to sucrose and glucose mixing. Our observations, performed at the single vesicle level, indicate these changes are under the control of the number of pulses and field intensity. Larger number of pulses enhances membrane alterations. A threshold value of the field intensity must be applied to allow exchange of molecules between GUVs and the external medium. This threshold depends on the size of the vesicles, the larger GUVs being affected at lower electric field strengths than the smaller ones. Our experimental data are well described by a simple model in which molecule entry is driven by direct exchange. The CARS microscopic study of the effect of pulse duration confirms that pulses, in the ms time range, induce loss of lipids and membrane deformations facing the electrodes. Copyright © 2012 Elsevier B.V. All rights reserved.
In Vivo Demonstration of Cancer Molecular Imaging with Ultrasound Radiation Force and Buried-Ligand Microbubbles

PubMed Central

Borden, Mark A.; Streeter, Jason E.; Sirsi, Shashank R.; Dayton, Paul A.

2015-01-01

In designing targeted contrast agent materials for imaging, the need to present a targeting ligand for recognition and binding by the target is counterbalanced by the need to minimize interactions with plasma components and to avoid recognition by the immune system. We have previously reported on a microbubble imaging probe for ultrasound molecular imaging that uses a buried-ligand surface architecture to minimize unwanted interactions and immunogenicity. Here we examine for the first time the utility of this approach for in vivo molecular imaging. In accordance with previous results, we showed a threefold increase in circulation persistence through the tumor of a fibrosarcoma model in comparison with controls. The buried-ligand microbubbles were then activated for targeted adhesion through the application of noninvasive ultrasound radiation forces applied specifically to the tumor region. Using a clinical ultrasound scanner, microbubbles were activated, imaged, and silenced. The results showed visually conspicuous images of tumor neovasculature and a twofold increase in ultrasound radiation force enhancement of acoustic contrast intensity for buried-ligand microbubbles, whereas no such increase was found for exposed-ligand microbubbles. We therefore conclude that the use of acoustically active buried-ligand microbubbles for ultrasound molecular imaging bridges the demand for low immunogenicity with the necessity of maintaining targeting efficacy and imaging conspicuity in vivo. PMID:23981781
[Emergency medecine : myths in hospital care].

PubMed

Maillard, Alain; Beysard, Nicolas

2017-08-09

Many of our medical procedures are conditioned by beliefs or experiences by our mentors, which we pass on to the younger, for example: gradually emptying a full bladder to avoid hypotension or haemorrhage, hydrating the alcoholic so that the blood alcohol level decreases faster, always obtaining an arterial blood gas instead of a venous one and not injecting iodinated intravenous contrast in patients allergic to shellfish.
Stranger Fear and Early Risk for Social Anxiety in Preschoolers with Fragile X Syndrome Contrasted to Autism Spectrum Disorder

ERIC Educational Resources Information Center

Scherr, Jessica F.; Hogan, Abigail L.; Hatton, Deborah; Roberts, Jane E.

2017-01-01

This study investigated behavioral indicators of social fear in preschool boys with fragile X syndrome (FXS) with a low degree of autism spectrum disorder (ASD) symptoms (FXS-Low; n = 29), FXS with elevated ASD symptoms (FXS-High; n = 25), idiopathic ASD (iASD; n = 11), and typical development (TD; n = 36). Gaze avoidance, escape behaviors, and…
Allometry, nitrogen status, and carbon stable isotope composition of Pinus ponderosa seedlings in two growing media with contrasting nursery irrigation regimes

Treesearch

R. Kasten Dumroese; Deborah S. Page-Dumroese; Robert E. Brown

2011-01-01

Nursery irrigation regimes that recharged container capacity when target volumetric water content reached 72%, 58%, and 44% (by volume) influenced Pinus ponderosa Douglas ex Lawson & C. Lawson growth more than either a 1:1 (by volume) Sphagnum peat - vermiculite (PV) or a 7:3 (by volume) Sphagnum peat - sawdust (PS) medium. Exponential fertilization avoided...
Time-dependent wave splitting and source separation

NASA Astrophysics Data System (ADS)

Grote, Marcus J.; Kray, Marie; Nataf, Frédéric; Assous, Franck

2017-02-01

Starting from classical absorbing boundary conditions, we propose a method for the separation of time-dependent scattered wave fields due to multiple sources or obstacles. In contrast to previous techniques, our method is local in space and time, deterministic, and avoids a priori assumptions on the frequency spectrum of the signal. Numerical examples in two space dimensions illustrate the usefulness of wave splitting for time-dependent scattering problems.
Braking Analysis For Collision Avoidance-- Autonomous Braking System Performance Modeling And Benefits Analysis

DOT National Transportation Integrated Search

1996-05-24

THIS REPORT IS AN ANALYSIS OF THE BENEFITS OF A COLLISION AVOIDANCE SYSTEM IN REDUCING REAR-END CRASHES. THE COLLISION AVOIDANCE SYSTEM CONSIDERED IN THIS STUDY UTILIZES THE SIGNAL FROM A FORWARD LOOKING SENSOR TO ACTIVATE THE TRACTION CONTROL VALVE ...

The mnemonic mover: nostalgia regulates avoidance and approach motivation.

PubMed

Stephan, Elena; Wildschut, Tim; Sedikides, Constantine; Zhou, Xinyue; He, Wuming; Routledge, Clay; Cheung, Wing-Yee; Vingerhoets, Ad J J M

2014-06-01

In light of its role in maintaining psychological equanimity, we proposed that nostalgia--a self-relevant, social, and predominantly positive emotion--regulates avoidance and approach motivation. We advanced a model in which (a) avoidance motivation triggers nostalgia and (b) nostalgia, in turn, increases approach motivation. As a result, nostalgia counteracts the negative impact of avoidance motivation on approach motivation. Five methodologically diverse studies supported this regulatory model. Study 1 used a cross-sectional design and showed that avoidance motivation was positively associated with nostalgia. Nostalgia, in turn, was positively associated with approach motivation. In Study 2, an experimental induction of avoidance motivation increased nostalgia. Nostalgia then predicted increased approach motivation. Studies 3-5 tested the causal effect of nostalgia on approach motivation and behavior. These studies demonstrated that experimental nostalgia inductions strengthened approach motivation (Study 3) and approach behavior as manifested in reduced seating distance (Study 4) and increased helping (Study 5). The findings shed light on nostalgia's role in regulating the human motivation system.
On Detailed Contrast of Biomedical Object in X-ray Dark-Field Imaging

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

Shimao, Daisuke; Mori, Koichi; Sugiyama, Hiroshi

2007-01-19

Over the past 10 years, refraction-based X-ray imaging has been studied together with a perspective view to clinical application. X-ray Dark-Field Imaging that utilizes a Laue geometry analyzer has recently been proposed and has the proven ability to depict articular cartilage in an intact human finger. In the current study, we researched detailed image contrast using X-ray Dark-Field Imaging by observing the edge contrast of an acrylic rod as a simple case, and found differences in image contrast between the right and left edges of the rod. This effect could cause undesirable contrast in the thin articular cartilage on themore » head of the phalanx. To avoid overlapping with this contrast at the articular cartilage, which would lead to a wrong diagnosis, we suggest that a joint surface on which articular cartilage is located should be aligned in the same sense as the scattering vector of the Laue case analyzer crystal. Defects of articular cartilage were successfully detected under this condition. When utilized under appropriate imaging conditions, X-ray Dark-Field Imaging will be a powerful tool for the diagnosis of arthropathy, as minute changes in articular cartilage may be early-stage features of this disease.« less
Synergistic Combination of Unquenching and Plasmonic Fluorescence Enhancement in Fluorogenic Nucleic Acid Hybridization Probes.

PubMed

Vietz, Carolin; Lalkens, Birka; Acuna, Guillermo P; Tinnefeld, Philip

2017-10-11

Fluorogenic nucleic acid hybridization probes are widely used for detecting and quantifying nucleic acids. The achieved sensitivity strongly depends on the contrast between a quenched closed form and an unquenched opened form with liberated fluorescence. So far, this contrast was improved by improving the quenching efficiency of the closed form. In this study, we modularly combine these probes with optical antennas used for plasmonic fluorescence enhancement and study the effect of the nanophotonic structure on the fluorescence of the quenched and the opened form. As quenched fluorescent dyes are usually enhanced more by fluorescence enhancement, a detrimental reduction of the contrast between closed and opened form was anticipated. In contrast, we could achieve a surprising increase of the contrast with full additivity of quenching of the dark form and fluorescence enhancement of the bright form. Using single-molecule experiments, we demonstrate that the additivity of the two mechanisms depends on the perfect quenching in the quenched form, and we delineate the rules for new nucleic acid probes for enhanced contrast and absolute brightness. Fluorogenic hybridization probes optimized not only for quenching but also for the brightness of the open form might find application in nucleic acid assays with PCR avoiding detection schemes.
A singularity free approach to post glacial rebound calculations

NASA Technical Reports Server (NTRS)

Fang, Ming; Hager, Bradford H.

1994-01-01

Calculating the post glacial response of a viscoelastic Earth model using the exponential decay normal mode technique leads to intrinsic singularities if viscosity varies continuously as a function of radius. We develop a numerical implementation of the Complex Real Fourier transform (CRFT) method as an accurate and stable procedure to avoid these singularities. Using CRFT, we investigate the response of a set of Maxwell Earth models to surface loading. We find that the effect of expanding a layered viscosity structure into a continuously varying structure is to destroy the modes associated with the boundary between layers. Horizontal motion is more sensitive than vertical motion to the viscosity structure just below the lithosphere. Horizontal motion is less sensitive to the viscosity of the lower mantle than the vertical motion is. When the viscosity increases at 670 km depth by a factor of about 60, the response of the lower mantle is close to its elastic limit. Any further increase of the viscosity contrast at 670 km depth or further increase of viscosity as a continuous function of depth starting from 670 km depth is unlikely to be resolved.
Plant toxicity, adaptive herbivory, and plant community dynamics

USGS Publications Warehouse

Feng, Z.; Liu, R.; DeAngelis, D.L.; Bryant, J.P.; Kielland, K.; Stuart, Chapin F.; Swihart, R.K.

2009-01-01

We model effects of interspecific plant competition, herbivory, and a plant's toxic defenses against herbivores on vegetation dynamics. The model predicts that, when a generalist herbivore feeds in the absence of plant toxins, adaptive foraging generally increases the probability of coexistence of plant species populations, because the herbivore switches more of its effort to whichever plant species is more common and accessible. In contrast, toxin-determined selective herbivory can drive plant succession toward dominance by the more toxic species, as previously documented in boreal forests and prairies. When the toxin concentrations in different plant species are similar, but species have different toxins with nonadditive effects, herbivores tend to diversify foraging efforts to avoid high intakes of any one toxin. This diversification leads the herbivore to focus more feeding on the less common plant species. Thus, uncommon plants may experience depensatory mortality from herbivory, reducing local species diversity. The depensatory effect of herbivory may inhibit the invasion of other plant species that are more palatable or have different toxins. These predictions were tested and confirmed in the Alaskan boreal forest. ?? 2009 Springer Science+Business Media, LLC.
Impact of night-shift work on the prevalence of erosive esophagitis in shipyard male workers.

PubMed

Chung, Tae Heum; Lee, Jiho; Kim, Moon Chan

2016-08-01

Whether night-shift work is a risk factor for gastroesophageal reflux disease is controversial. The aim of this study was to investigate the association between night-shift work and other factors, and erosive esophagitis. A cross-sectional study with 6040 male shipyard workers was performed. Esophagogastroduodenoscopic examination and a survey about night-shift work status, lifestyle, medical history, educational status, and marital status were conducted in all workers. The odds ratios of erosive esophagitis according to night-shift work status were calculated by using the logistic regression model. The prevalence of erosive esophagitis increased in the night-shift workers [odds ratio, 95 % confidence interval: 1.41 (1.03-1.94)]. According to multiple logistic regression models, night-shift work, obesity, smoking, and alcohol consumption of ≥140 g/week were significant risk factors for erosive esophagitis. By contrast, Helicobacter pylori infection was negatively associated with erosive esophagitis. Night-shift work is suggested to be a risk factor for erosive esophagitis. Avoidance of night-shift work and lifestyle modification should be considered for prevention and management of gastroesophageal reflux disease.
Exothermic dark matter

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

Graham, Peter W.; Saraswat, Prashant; Harnik, Roni

2010-09-15

We propose a novel mechanism for dark matter to explain the observed annual modulation signal at DAMA/LIBRA which avoids existing constraints from every other dark matter direct detection experiment including CRESST, CDMS, and XENON10. The dark matter consists of at least two light states with mass {approx}few GeV and splittings {approx}5 keV. It is natural for the heavier states to be cosmologically long-lived and to make up an O(1) fraction of the dark matter. Direct detection rates are dominated by the exothermic reactions in which an excited dark matter state downscatters off of a nucleus, becoming a lower energy state.more » In contrast to (endothermic) inelastic dark matter, the most sensitive experiments for exothermic dark matter are those with light nuclei and low threshold energies. Interestingly, this model can also naturally account for the observed low-energy events at CoGeNT. The only significant constraint on the model arises from the DAMA/LIBRA unmodulated spectrum but it can be tested in the near future by a low-threshold analysis of CDMS-Si and possibly other experiments including CRESST, COUPP, and XENON100.« less
Fulfill Promises and Avoid Breaches to Retain Satisfied, Committed Nurses.

PubMed

Rodwell, John; Ellershaw, Julia

2016-07-01

This study examines two commonly proposed mechanisms, violation and trust, to see if they mediate the relationships between the components of the psychological contract (i.e., promises, fulfillment, and breach) and their impact on the work-related outcomes of job satisfaction, intent to quit, and organizational commitment. Online surveys were completed by 459 Australian nurses. Structural equation modeling revealed that breach and fulfillment have direct and mediated effects on the outcomes, whereas promises had no impact. Violation partially mediated the relationship between breach and job satisfaction and intent to quit, while trust partially mediated the relationships between fulfillment and organizational commitment, and breach and organizational commitment. Negative experiences (i.e., breaches) were related to both increased feelings of violation and decreased feelings of trust. In contrast, positive experiences (i.e., fulfillment) increased trust but did not significantly reduce feelings of violation. Nurse and organizational managers can use these findings to improve communication with nurses so as to minimize the negative effects of breach and maximize the positive effects of fulfillment and thus improve attitudes. Nurse managers need to be careful to make promises regarding their nurses' employment that they can fulfill and to particularly avoid breaking the psychological contract. The potentially disproportionate negative effect of breach means that a breach can undo a lot of efforts to fulfill employment-related promises. © 2016 Sigma Theta Tau International.
Human shields mediate sexual conflict in a top predator.

PubMed

Steyaert, S M J G; Leclerc, M; Pelletier, F; Kindberg, J; Brunberg, S; Swenson, J E; Zedrosser, A

2016-06-29

Selecting the right habitat in a risky landscape is crucial for an individual's survival and reproduction. In predator-prey systems, prey often can anticipate the habitat use of their main predator and may use protective associates (i.e. typically an apex predator) as shields against predation. Although never tested, such mechanisms should also evolve in systems in which sexual conflict affects offspring survival. Here, we assessed the relationship between offspring survival and habitat selection, as well as the use of protective associates, in a system in which sexually selected infanticide (SSI), rather than interspecific predation, affects offspring survival. We used the Scandinavian brown bear (Ursus arctos) population with SSI in a human-dominated landscape as our model system. Bears, especially adult males, generally avoid humans in our study system. We used resource selection functions to contrast habitat selection of GPS-collared mothers that were successful (i.e. surviving litters, n = 19) and unsuccessful (i.e. complete litter loss, n = 11) in keeping their young during the mating season (2005-2012). Habitat selection was indeed a predictor of litter survival. Successful mothers were more likely to use humans as protective associates, whereas unsuccessful mothers avoided humans. Our results suggest that principles of predator-prey and fear ecology theory (e.g. non-consumptive and cascading effects) can also be applied to the context of sexual conflict. © 2016 The Authors.
Modeling quality of life in patients with rheumatic diseases: the role of pain catastrophizing, fear-avoidance beliefs, physical disability, and depression.

PubMed

Shim, Eun-Jung; Hahm, Bong-Jin; Go, Dong Jin; Lee, Kwang-Min; Noh, Hae Lim; Park, Seung-Hee; Song, Yeong Wook

2018-06-01

To examine factors in the fear-avoidance model, such as pain, pain catastrophizing, fear-avoidance beliefs, physical disability, and depression and their relationships with physical and psychological quality of life in patients with rheumatic diseases. The data were obtained from 360 patients with rheumatic diseases who completed self-report measures assessing study variables. Structural equation modeling was used to examine the hypothesized relationships among factors specified in the fear-avoidance model predicting physical and psychological quality of life. Final models fit the data well, explaining 96% and 82% of the variance in physical and psychological quality of life, respectively. Higher pain catastrophizing was related to stronger fear-avoidance beliefs that had a direct negative association with physical disability and depression, which, in turn, negatively affected physical quality of life. Pain severity was also directly related to physical disability. Physical disability also affected physical quality of life indirectly through depression. The hypothesized relationships specified in the model were also confirmed for psychological quality of life. However, physical disability had an indirect association with psychological quality of life via depression. The current results underscore the significant role of cognitive, affective, and behavioral factors in perceived physical disability and their mediated detrimental effect on physical and psychological quality of life in patients with rheumatic diseases. Implications for rehabilitation The fear-avoidance model is applicable to the prediction of quality of life in patients with rheumatic diseases. As pain-catastrophizing and fear-avoidance beliefs are important factors linked to physical disability and depression, intervening these cognitive factors is necessary to improve physical function and depression in patients with rheumatic diseases. Considering the strong association between depression and physical and psychological quality of life, the assessment and treatment of the former should be included in the rehabilitation of patients with rheumatic diseases. Interventions targeting physical function and depression are likely to be effective in terms of improving physical and psychological quality of life in patients with rheumatic diseases.
Ballooning of the papilla during contrast injection: the semaphore of a choledochocele.

PubMed

Kim, M H; Myung, S J; Lee, S K; Yoo, B M; Seo, D W; Lee, M H; Jung, S A; Kim, Y S; Min, Y I

1998-09-01

Choledochocele is a rare abnormality involving the intramural segment of the common bile duct. ERCP is essential to demonstrate a choledochocele. The aim of this study was to investigate the duodenoscopic and cholangiographic findings during ERCP. Over a 4-year period, 17 symptomatic patients (8 men, 9 women; age range 45 to 83 years) were identified as having choledochoceles. The diagnosis of choledochocele was made by both duodenoscopic and cholangiographic findings. As a characteristic duodenoscopic finding, the enlarged bulging papilla was noted in 8 patients (47%), whereas a normal-appearing papilla was noted in 9 patients (53%) before the injection of contrast media. However, in all 17 patients progressive enlargement or ballooning of the papilla was noted during contrast injection. The maximum diameter of the choledochocele, determined by cholangiography, was significantly larger (19 +/-4 mm) in patients with initially bulging papilla than in those with normal-appearing papilla (9+/-3 mm) (p < 0.05). Ballooning of the papilla during contrast injection may be a specific duodenoscopic finding for choledochocele. To avoid missing the diagnosis of a choledochocele, especially when it is small, it is important to watch the papilla carefully during contrast injection.
Incidence of intravenous contrast extravasation: increased risk for patients with deep brachial catheter placement from the emergency department.

PubMed

Hardie, Andrew D; Kereshi, Borko

2014-06-01

Deep brachial intravenous catheter (IV) placement can be performed in emergency department patients with difficult vascular access, but the safety of deep brachial IV for iodinated contrast administration has not been assessed. This study compares the relative risk for extravasation of deep brachial IV compared with antecubital IV during power injected computed tomography (CT) examinations. A departmental practice quality improvement was performed to assess the rate of IV extravasation for all CT examinations during a 1 year period. De-identified data was analyzed with a waiver of informed consent to identify the rate and relative risk of iodinated contrast extravasation by catheter type. A total of 10,750 injections were performed, with 82 extravasation events (0.8 %). There were 51 extravasations of antecubital IV from approximately 8,599 placed (0.6 %). For 123 deep brachial IV placed, there were eight extravasations (6.5 %). The relative risk of a deep brachial IV extravasation was 9.4 compared to 0.4 for antecubital placement. Deep brachial IV demonstrated a markedly higher rate of contrast extravasation than antecubital IV. For power injected iodinated contrast administration, it is recommended to avoid the use of deep brachial IV whenever possible.
In vivo small animal micro-CT using nanoparticle contrast agents

PubMed Central

Ashton, Jeffrey R.; West, Jennifer L.; Badea, Cristian T.

2015-01-01

Computed tomography (CT) is one of the most valuable modalities for in vivo imaging because it is fast, high-resolution, cost-effective, and non-invasive. Moreover, CT is heavily used not only in the clinic (for both diagnostics and treatment planning) but also in preclinical research as micro-CT. Although CT is inherently effective for lung and bone imaging, soft tissue imaging requires the use of contrast agents. For small animal micro-CT, nanoparticle contrast agents are used in order to avoid rapid renal clearance. A variety of nanoparticles have been used for micro-CT imaging, but the majority of research has focused on the use of iodine-containing nanoparticles and gold nanoparticles. Both nanoparticle types can act as highly effective blood pool contrast agents or can be targeted using a wide variety of targeting mechanisms. CT imaging can be further enhanced by adding spectral capabilities to separate multiple co-injected nanoparticles in vivo. Spectral CT, using both energy-integrating and energy-resolving detectors, has been used with multiple contrast agents to enable functional and molecular imaging. This review focuses on new developments for in vivo small animal micro-CT using novel nanoparticle probes applied in preclinical research. PMID:26581654
Statistical Evaluation of CRM-Simulated Cloud and Precipitation Structures Using Multi- sensor TRMM Measurements and Retrievals

NASA Astrophysics Data System (ADS)

Posselt, D.; L'Ecuyer, T.; Matsui, T.

2009-05-01

Cloud resolving models are typically used to examine the characteristics of clouds and precipitation and their relationship to radiation and the large-scale circulation. As such, they are not required to reproduce the exact location of each observed convective system, much less each individual cloud. Some of the most relevant information about clouds and precipitation is provided by instruments located on polar-orbiting satellite platforms, but these observations are intermittent "snapshots" in time, making assessment of model performance challenging. In contrast to direct comparison, model results can be evaluated statistically. This avoids the requirement for the model to reproduce the observed systems, while returning valuable information on the performance of the model in a climate-relevant sense. The focus of this talk is a model evaluation study, in which updates to the microphysics scheme used in a three-dimensional version of the Goddard Cumulus Ensemble (GCE) model are evaluated using statistics of observed clouds, precipitation, and radiation. We present the results of multiday (non-equilibrium) simulations of organized deep convection using single- and double-moment versions of a the model's cloud microphysical scheme. Statistics of TRMM multi-sensor derived clouds, precipitation, and radiative fluxes are used to evaluate the GCE results, as are simulated TRMM measurements obtained using a sophisticated instrument simulator suite. We present advantages and disadvantages of performing model comparisons in retrieval and measurement space and conclude by motivating the use of data assimilation techniques for analyzing and improving model parameterizations.
Analysis of Well-Clear Boundary Models for the Integration of UAS in the NAS

NASA Technical Reports Server (NTRS)

Upchurch, Jason M.; Munoz, Cesar A.; Narkawicz, Anthony J.; Chamberlain, James P.; Consiglio, Maria C.

2014-01-01

The FAA-sponsored Sense and Avoid Workshop for Unmanned Aircraft Systems (UAS) defnes the concept of sense and avoid for remote pilots as "the capability of a UAS to remain well clear from and avoid collisions with other airborne traffic." Hence, a rigorous definition of well clear is fundamental to any separation assurance concept for the integration of UAS into civil airspace. This paper presents a family of well-clear boundary models based on the TCAS II Resolution Advisory logic. Analytical techniques are used to study the properties and relationships satisfied by the models. Some of these properties are numerically quantifed using statistical methods.
Healthcare avoidance: a critical review.

PubMed

Byrne, Sharon K

2008-01-01

The purpose of this study is to provide a critical review and synthesis of theoretical and research literature documenting the impact of avoidance on healthcare behaviors, identify the factors that influence healthcare avoidance and delay in the adult population, and propose a direction for future research. The Theory of Reasoned Action, Theory of Planned Behavior, Theory of Care-Seeking Behavior, the Transtheoretical Model, and the Behavioral Model of Health Services Use/Utilization are utilized to elaborate on the context within which individual intention to engage in healthcare behaviors occurs. Research literature on the concept of healthcare avoidance obtained by using computerized searches of CINAHL, MEDLINE, PSYCH INFO, and HAPI databases, from 1995 to 2007, were reviewed. Studies were organized by professional disciplines. Healthcare avoidance is a common and highly variable experience. Multiple administrative, demographic, personal, and provider factors are related to healthcare avoidance, for example, distrust of providers and/or the science community, health beliefs, insurance status, or socioeconomic/income level. Although the concept is recognized by multiple disciplines, limited research studies address its impact on healthcare decision making. More systematic research is needed to determine correlates of healthcare avoidance. Such studies will help investigators identify patients at risk for avoidant behaviors and provide the basis for health-promoting interventions. Methodological challenges include identification of characteristics of individuals and environments that hinder healthcare behaviors, as well as, the complexity of measuring healthcare avoidance. Studies need to systematically explore the influence of avoidance behaviors on specific healthcare populations at risk.
3D morphometry using automated aortic segmentation in native MR angiography: an alternative to contrast enhanced MRA?

PubMed

Müller-Eschner, Matthias; Müller, Tobias; Biesdorf, Andreas; Wörz, Stefan; Rengier, Fabian; Böckler, Dittmar; Kauczor, Hans-Ulrich; Rohr, Karl; von Tengg-Kobligk, Hendrik

2014-04-01

Native-MR angiography (N-MRA) is considered an imaging alternative to contrast enhanced MR angiography (CE-MRA) for patients with renal insufficiency. Lower intraluminal contrast in N-MRA often leads to failure of the segmentation process in commercial algorithms. This study introduces an in-house 3D model-based segmentation approach used to compare both sequences by automatic 3D lumen segmentation, allowing for evaluation of differences of aortic lumen diameters as well as differences in length comparing both acquisition techniques at every possible location. Sixteen healthy volunteers underwent 1.5-T-MR Angiography (MRA). For each volunteer, two different MR sequences were performed, CE-MRA: gradient echo Turbo FLASH sequence and N-MRA: respiratory-and-cardiac-gated, T2-weighted 3D SSFP. Datasets were segmented using a 3D model-based ellipse-fitting approach with a single seed point placed manually above the celiac trunk. The segmented volumes were manually cropped from left subclavian artery to celiac trunk to avoid error due to side branches. Diameters, volumes and centerline length were computed for intraindividual comparison. For statistical analysis the Wilcoxon-Signed-Ranked-Test was used. Average centerline length obtained based on N-MRA was 239.0±23.4 mm compared to 238.6±23.5 mm for CE-MRA without significant difference (P=0.877). Average maximum diameter obtained based on N-MRA was 25.7±3.3 mm compared to 24.1±3.2 mm for CE-MRA (P<0.001). In agreement with the difference in diameters, volumes obtained based on N-MRA (100.1±35.4 cm(3)) were consistently and significantly larger compared to CE-MRA (89.2±30.0 cm(3)) (P<0.001). 3D morphometry shows highly similar centerline lengths for N-MRA and CE-MRA, but systematically higher diameters and volumes for N-MRA.
3D morphometry using automated aortic segmentation in native MR angiography: an alternative to contrast enhanced MRA?

PubMed Central

Müller-Eschner, Matthias; Müller, Tobias; Biesdorf, Andreas; Wörz, Stefan; Rengier, Fabian; Böckler, Dittmar; Kauczor, Hans-Ulrich; Rohr, Karl

2014-01-01

Introduction Native-MR angiography (N-MRA) is considered an imaging alternative to contrast enhanced MR angiography (CE-MRA) for patients with renal insufficiency. Lower intraluminal contrast in N-MRA often leads to failure of the segmentation process in commercial algorithms. This study introduces an in-house 3D model-based segmentation approach used to compare both sequences by automatic 3D lumen segmentation, allowing for evaluation of differences of aortic lumen diameters as well as differences in length comparing both acquisition techniques at every possible location. Methods and materials Sixteen healthy volunteers underwent 1.5-T-MR Angiography (MRA). For each volunteer, two different MR sequences were performed, CE-MRA: gradient echo Turbo FLASH sequence and N-MRA: respiratory-and-cardiac-gated, T2-weighted 3D SSFP. Datasets were segmented using a 3D model-based ellipse-fitting approach with a single seed point placed manually above the celiac trunk. The segmented volumes were manually cropped from left subclavian artery to celiac trunk to avoid error due to side branches. Diameters, volumes and centerline length were computed for intraindividual comparison. For statistical analysis the Wilcoxon-Signed-Ranked-Test was used. Results Average centerline length obtained based on N-MRA was 239.0±23.4 mm compared to 238.6±23.5 mm for CE-MRA without significant difference (P=0.877). Average maximum diameter obtained based on N-MRA was 25.7±3.3 mm compared to 24.1±3.2 mm for CE-MRA (P<0.001). In agreement with the difference in diameters, volumes obtained based on N-MRA (100.1±35.4 cm3) were consistently and significantly larger compared to CE-MRA (89.2±30.0 cm3) (P<0.001). Conclusions 3D morphometry shows highly similar centerline lengths for N-MRA and CE-MRA, but systematically higher diameters and volumes for N-MRA. PMID:24834406
Human hippocampus arbitrates approach-avoidance conflict.

PubMed

Bach, Dominik R; Guitart-Masip, Marc; Packard, Pau A; Miró, Júlia; Falip, Mercè; Fuentemilla, Lluís; Dolan, Raymond J

2014-03-03

Animal models of human anxiety often invoke a conflict between approach and avoidance. In these, a key behavioral assay comprises passive avoidance of potential threat and inhibition, both thought to be controlled by ventral hippocampus. Efforts to translate these approaches to clinical contexts are hampered by the fact that it is not known whether humans manifest analogous approach-avoidance dispositions and, if so, whether they share a homologous neurobiological substrate. Here, we developed a paradigm to investigate the role of human hippocampus in arbitrating an approach-avoidance conflict under varying levels of potential threat. Across four experiments, subjects showed analogous behavior by adapting both passive avoidance behavior and behavioral inhibition to threat level. Using functional magnetic resonance imaging (fMRI), we observe that threat level engages the anterior hippocampus, the human homolog of rodent ventral hippocampus. Testing patients with selective hippocampal lesions, we demonstrate a causal role for the hippocampus with patients showing reduced passive avoidance behavior and inhibition across all threat levels. Our data provide the first human assay for approach-avoidance conflict akin to that of animal anxiety models. The findings bridge rodent and human research on passive avoidance and behavioral inhibition and furnish a framework for addressing the neuronal underpinnings of human anxiety disorders, where our data indicate a major role for the hippocampus. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.
What predicts the strength of simultaneous color contrast?

PubMed Central

Ratnasingam, Sivalogeswaran; Anderson, Barton L.

2017-01-01

The perceived color of a uniform image patch depends not only on the spectral content of the light that reaches the eye but also on its context. One of the most extensively studied forms of context dependence is a simultaneous contrast display: a center-surround display containing a homogeneous target embedded in a homogenous surround. A number of models have been proposed to account for the chromatic transformations of targets induced by such surrounds, but they were typically derived in the restricted context of experiments using achromatic targets with surrounds that varied along the cardinal axes of color space. There is currently no theoretical consensus that predicts the target color that produces the largest perceived color difference for two arbitrarily chosen surround colors, or what surround would give the largest color induction for an arbitrarily chosen target. Here, we present a method for assessing simultaneous contrast that avoids some of the methodological issues that arise with nulling and matching experiments and diminishes the contribution of temporal adaption. Observers were presented with pairs of center-surround patterns and ordered them from largest to smallest in perceived dissimilarity. We find that the perceived difference for two arbitrarily chosen surrounds is largest when the target falls on the line connecting the two surrounds in color space. We also find that the magnitude of induction is larger for larger differences between chromatic targets and surrounds of the same hue. Our results are consistent with the direction law (Ekroll & Faul, 2012b), and with a generalization of Kirschmann's fourth law, even for viewing conditions that do not favor temporal adaptation. PMID:28245494

Robot environment expert system

NASA Technical Reports Server (NTRS)

Potter, J. L.

1985-01-01

The Robot Environment Expert System uses a hexidecimal tree data structure to model a complex robot environment where not only the robot arm moves, but also the robot itself and other objects may move. The hextree model allows dynamic updating, collision avoidance and path planning over time, to avoid moving objects.
Positive affect predicts avoidance goals in social interaction anxiety: testing a hierarchical model of social goals.

PubMed

Trew, Jennifer L; Alden, Lynn E

2012-01-01

Models of self-regulation suggest that social goals may contribute to interpersonal and affective difficulties, yet little research has addressed this issue in the context of social anxiety. The present studies evaluated a hierarchical model of approach and avoidance in the context of social interaction anxiety, with affect as a mediating factor in the relationship between motivational tendencies and social goals. This model was refined in one undergraduate sample (N = 186) and cross-validated in a second sample (N = 195). The findings support hierarchical relationships between motivational tendencies, social interaction anxiety, affect, and social goals, with higher positive affect predicting fewer avoidance goals in both samples. Implications for the treatment of social interaction anxiety are discussed.
A Neural Model of Visually Guided Steering, Obstacle Avoidance, and Route Selection

ERIC Educational Resources Information Center

Elder, David M.; Grossberg, Stephen; Mingolla, Ennio

2009-01-01

A neural model is developed to explain how humans can approach a goal object on foot while steering around obstacles to avoid collisions in a cluttered environment. The model uses optic flow from a 3-dimensional virtual reality environment to determine the position of objects on the basis of motion discontinuities and computes heading direction,…
Massive stars in advanced evolutionary stages, and the progenitor of GW150914

NASA Astrophysics Data System (ADS)

Hamann, Wolf-Rainer; Oskinova, Lidia; Todt, Helge; Sander, Andreas; Hainich, Rainer; Shenar, Tomer; Ramachandran, Varsha

2017-11-01

The recent discovery of a gravitational wave from the merging of two black holes of about 30 solar masses each challenges our incomplete understanding of massive stars and their evolution. Critical ingredients comprise mass-loss, rotation, magnetic fields, internal mixing, and mass transfer in close binary systems. The imperfect knowledge of these factors implies large uncertainties for models of stellar populations and their feedback. In this contribution we summarize our empirical studies of Wolf-Rayet populations at different metallicities by means of modern non-LTE stellar atmosphere models, and confront these results with the predictions of stellar evolution models. At the metallicity of our Galaxy, stellar winds are probably too strong to leave remnant masses as high as ~30 M⊙, but given the still poor agreement between evolutionary tracks and observation even this conclusion is debatable. At the low metallicity of the Small Magellanic Cloud, all WN stars which are (at least now) single are consistent with evolving quasi-homogeneously. O and B-type stars, in contrast, seem to comply with standard evolutionary models without strong internal mixing. Close binaries which avoided early merging could evolve quasi-homogeneously and lead to close compact remnants of relatively high masses that merge within a Hubble time.
Synthesized interstitial lung texture for use in anthropomorphic computational phantoms

NASA Astrophysics Data System (ADS)

Becchetti, Marc F.; Solomon, Justin B.; Segars, W. Paul; Samei, Ehsan

2016-04-01

A realistic model of the anatomical texture from the pulmonary interstitium was developed with the goal of extending the capability of anthropomorphic computational phantoms (e.g., XCAT, Duke University), allowing for more accurate image quality assessment. Contrast-enhanced, high dose, thorax images for a healthy patient from a clinical CT system (Discovery CT750HD, GE healthcare) with thin (0.625 mm) slices and filtered back- projection (FBP) were used to inform the model. The interstitium which gives rise to the texture was defined using 24 volumes of interest (VOIs). These VOIs were selected manually to avoid vasculature, bronchi, and bronchioles. A small scale Hessian-based line filter was applied to minimize the amount of partial-volumed supernumerary vessels and bronchioles within the VOIs. The texture in the VOIs was characterized using 8 Haralick and 13 gray-level run length features. A clustered lumpy background (CLB) model with added noise and blurring to match CT system was optimized to resemble the texture in the VOIs using a genetic algorithm with the Mahalanobis distance as a similarity metric between the texture features. The most similar CLB model was then used to generate the interstitial texture to fill the lung. The optimization improved the similarity by 45%. This will substantially enhance the capabilities of anthropomorphic computational phantoms, allowing for more realistic CT simulations.
Role of dopamine D2 receptors in human reinforcement learning.

PubMed

Eisenegger, Christoph; Naef, Michael; Linssen, Anke; Clark, Luke; Gandamaneni, Praveen K; Müller, Ulrich; Robbins, Trevor W

2014-09-01

Influential neurocomputational models emphasize dopamine (DA) as an electrophysiological and neurochemical correlate of reinforcement learning. However, evidence of a specific causal role of DA receptors in learning has been less forthcoming, especially in humans. Here we combine, in a between-subjects design, administration of a high dose of the selective DA D2/3-receptor antagonist sulpiride with genetic analysis of the DA D2 receptor in a behavioral study of reinforcement learning in a sample of 78 healthy male volunteers. In contrast to predictions of prevailing models emphasizing DA's pivotal role in learning via prediction errors, we found that sulpiride did not disrupt learning, but rather induced profound impairments in choice performance. The disruption was selective for stimuli indicating reward, whereas loss avoidance performance was unaffected. Effects were driven by volunteers with higher serum levels of the drug, and in those with genetically determined lower density of striatal DA D2 receptors. This is the clearest demonstration to date for a causal modulatory role of the DA D2 receptor in choice performance that might be distinct from learning. Our findings challenge current reward prediction error models of reinforcement learning, and suggest that classical animal models emphasizing a role of postsynaptic DA D2 receptors in motivational aspects of reinforcement learning may apply to humans as well.
Role of Dopamine D2 Receptors in Human Reinforcement Learning

PubMed Central

Eisenegger, Christoph; Naef, Michael; Linssen, Anke; Clark, Luke; Gandamaneni, Praveen K; Müller, Ulrich; Robbins, Trevor W

2014-01-01

Influential neurocomputational models emphasize dopamine (DA) as an electrophysiological and neurochemical correlate of reinforcement learning. However, evidence of a specific causal role of DA receptors in learning has been less forthcoming, especially in humans. Here we combine, in a between-subjects design, administration of a high dose of the selective DA D2/3-receptor antagonist sulpiride with genetic analysis of the DA D2 receptor in a behavioral study of reinforcement learning in a sample of 78 healthy male volunteers. In contrast to predictions of prevailing models emphasizing DA's pivotal role in learning via prediction errors, we found that sulpiride did not disrupt learning, but rather induced profound impairments in choice performance. The disruption was selective for stimuli indicating reward, whereas loss avoidance performance was unaffected. Effects were driven by volunteers with higher serum levels of the drug, and in those with genetically determined lower density of striatal DA D2 receptors. This is the clearest demonstration to date for a causal modulatory role of the DA D2 receptor in choice performance that might be distinct from learning. Our findings challenge current reward prediction error models of reinforcement learning, and suggest that classical animal models emphasizing a role of postsynaptic DA D2 receptors in motivational aspects of reinforcement learning may apply to humans as well. PMID:24713613
Implicit Priors in Galaxy Cluster Mass and Scaling Relation Determinations

NASA Technical Reports Server (NTRS)

Mantz, A.; Allen, S. W.

2011-01-01

Deriving the total masses of galaxy clusters from observations of the intracluster medium (ICM) generally requires some prior information, in addition to the assumptions of hydrostatic equilibrium and spherical symmetry. Often, this information takes the form of particular parametrized functions used to describe the cluster gas density and temperature profiles. In this paper, we investigate the implicit priors on hydrostatic masses that result from this fully parametric approach, and the implications of such priors for scaling relations formed from those masses. We show that the application of such fully parametric models of the ICM naturally imposes a prior on the slopes of the derived scaling relations, favoring the self-similar model, and argue that this prior may be influential in practice. In contrast, this bias does not exist for techniques which adopt an explicit prior on the form of the mass profile but describe the ICM non-parametrically. Constraints on the slope of the cluster mass-temperature relation in the literature show a separation based the approach employed, with the results from fully parametric ICM modeling clustering nearer the self-similar value. Given that a primary goal of scaling relation analyses is to test the self-similar model, the application of methods subject to strong, implicit priors should be avoided. Alternative methods and best practices are discussed.
Measured and modelled leaf and stand-scale productivity across a soil moisture gradient and a severe drought.

PubMed

Wright, J K; Williams, M; Starr, G; McGee, J; Mitchell, R J

2013-02-01

Environmental controls on carbon dynamics operate at a range of interacting scales from the leaf to landscape. The key questions of this study addressed the influence of water and nitrogen (N) availability on Pinus palustris (Mill.) physiology and primary productivity across leaf and canopy scales, linking the soil-plant-atmosphere (SPA) model to leaf and stand-scale flux and leaf trait/canopy data. We present previously unreported ecophysiological parameters (e.g. V(cmax) and J(max)) for P. palustris and the first modelled estimates of its annual gross primary productivity (GPP) across xeric and mesic sites and under extreme drought. Annual mesic site P. palustris GPP was ∼23% greater than at the xeric site. However, at the leaf level, xeric trees had higher net photosynthetic rates, and water and light use efficiency. At the canopy scale, GPP was limited by light interception (canopy level), but co-limited by nitrogen and water at the leaf level. Contrary to expectations, the impacts of an intense growing season drought were greater at the mesic site. Modelling indicated a 10% greater decrease in mesic GPP compared with the xeric site. Xeric P. palustris trees exhibited drought-tolerant behaviour that contrasted with mesic trees' drought-avoidance behaviour. © 2012 Blackwell Publishing Ltd.
Disease avoidance as a functional basis for stigmatization

PubMed Central

Oaten, Megan; Stevenson, Richard J.; Case, Trevor I.

2011-01-01

Stigmatization is characterized by chronic social and physical avoidance of a person(s) by other people. Infectious disease may produce an apparently similar form of isolation—disease avoidance—but on symptom remission this often abates. We propose that many forms of stigmatization reflect the activation of this disease-avoidance system, which is prone to respond to visible signs and labels that connote disease, irrespective of their accuracy. A model of this system is presented, which includes an emotional component, whereby visible disease cues directly activate disgust and contamination, motivating avoidance, and a cognitive component, whereby disease labels bring to mind disease cues, indirectly activating disgust and contamination. The unique predictions of this model are then examined, notably that people who are stigmatized evoke disgust and are contaminating. That animals too show avoidance of diseased conspecifics, and that disease-related stigma targets are avoided in most cultures, also supports this evolutionary account. The more general implications of this approach are then examined, notably how it can be used to good (e.g. improving hygiene) or bad (e.g. racial vilification) ends, by yoking particular labels with cues that connote disease and disgust. This broadening of the model allows for stigmatization of groups with little apparent connection to disease. PMID:22042920
Self-control, self-regulation, and doping in sport: a test of the strength-energy model.

PubMed

Chan, Derwin K; Lentillon-Kaestner, Vanessa; Dimmock, James A; Donovan, Robert J; Keatley, David A; Hardcastle, Sarah J; Hagger, Martin S

2015-04-01

We applied the strength-energy model of self-control to understand the relationship between self-control and young athletes' behavioral responses to taking illegal performance-enhancing substances, or "doping." Measures of trait self-control, attitude and intention toward doping, intention toward, and adherence to, doping-avoidant behaviors, and the prevention of unintended doping behaviors were administered to 410 young Australian athletes. Participants also completed a "lollipop" decision-making protocol that simulated avoidance of unintended doping. Hierarchical linear multiple regression analyses revealed that self-control was negatively associated with doping attitude and intention, and positively associated with the intention and adherence to doping-avoidant behaviors, and refusal to take or eat the unfamiliar candy offered in the "lollipop" protocol. Consistent with the strength-energy model, athletes with low self-control were more likely to have heightened attitude and intention toward doping, and reduced intention, behavioral adherence, and awareness of doping avoidance.
The 2 × 2 Standpoints Model of Achievement Goals

PubMed Central

Korn, Rachel M.; Elliot, Andrew J.

2016-01-01

In the present research, we proposed and tested a 2 × 2 standpoints model of achievement goals grounded in the development-demonstration and approach-avoidance distinctions. Three empirical studies are presented. Study 1 provided evidence supporting the structure and psychometric properties of a newly developed measure of the goals of the 2 × 2 standpoints model. Study 2 documented the predictive utility of these goal constructs for intrinsic motivation: development-approach and development-avoidance goals were positive predictors, and demonstration-avoidance goals were a negative predictor of intrinsic motivation. Study 3 documented the predictive utility of these goal constructs for performance attainment: Demonstration-approach goals were a positive predictor and demonstration-avoidance goals were a negative predictor of exam performance. The conceptual and empirical contributions of the present research were discussed within the broader context of existing achievement goal theory and research. PMID:27242641
Linear-constraint wavefront control for exoplanet coronagraphic imaging systems

NASA Astrophysics Data System (ADS)

Sun, He; Eldorado Riggs, A. J.; Kasdin, N. Jeremy; Vanderbei, Robert J.; Groff, Tyler Dean

2017-01-01

A coronagraph is a leading technology for achieving high-contrast imaging of exoplanets in a space telescope. It uses a system of several masks to modify the diffraction and achieve extremely high contrast in the image plane around target stars. However, coronagraphic imaging systems are very sensitive to optical aberrations, so wavefront correction using deformable mirrors (DMs) is necessary to avoid contrast degradation in the image plane. Electric field conjugation (EFC) and Stroke minimization (SM) are two primary high-contrast wavefront controllers explored in the past decade. EFC minimizes the average contrast in the search areas while regularizing the strength of the control inputs. Stroke minimization calculates the minimum DM commands under the constraint that a target average contrast is achieved. Recently in the High Contrast Imaging Lab at Princeton University (HCIL), a new linear-constraint wavefront controller based on stroke minimization was developed and demonstrated using numerical simulation. Instead of only constraining the average contrast over the entire search area, the new controller constrains the electric field of each single pixel using linear programming, which could led to significant increases in speed of the wavefront correction and also create more uniform dark holes. As a follow-up of this work, another linear-constraint controller modified from EFC is demonstrated theoretically and numerically and the lab verification of the linear-constraint controllers is reported. Based on the simulation and lab results, the pros and cons of linear-constraint controllers are carefully compared with EFC and stroke minimization.
Avoidance in hypochondriasis.

PubMed

Doherty-Torstrick, Emily R; Walton, Kate E; Barsky, Arthur J; Fallon, Brian A

2016-10-01

The DSM-5 diagnosis of illness anxiety disorder adds avoidance as a component of a behavioral response to illness fears - one that was not present in prior DSM criteria of hypochondriasis. However, maladaptive avoidance as a necessary or useful criterion has yet to be empirically supported. 195 individuals meeting DSM-IV criteria for hypochondriasis based on structured interview completed a variety of self-report and clinician-administered assessments. Data on maladaptive avoidance were obtained using the six-item subscale of the clinician-administered Hypochondriasis - Yale Brown Obsessive Compulsive Scale - Modified. To determine if avoidance emerged as a useful indicator in hypochondriasis, we compared the relative fit of continuous latent trait, categorical latent class, and hybrid factor mixture models. A two-class factor mixture model fit the data best, with Class 1 (n=147) exhibiting a greater level of severity of avoidance than Class 2 (n=48). The more severely avoidant group was found to have higher levels of hypochondriacal symptom severity, functional impairment, and anxiety, as well as lower quality of life. These results suggest that avoidance may be a valid behavioral construct and a useful component of the new diagnostic criteria of illness anxiety in the DSM-5, with implications for somatic symptom disorder. Copyright © 2016 Elsevier Inc. All rights reserved.
What is the underestimation of radiation dose to the pediatric thyroid gland from contrast enhanced CT, if contrast medium uptake is not taken into account?

PubMed

Perisinakis, Kostas; Pouli, Styliani; Tzedakis, Antonis; Spanakis, Kostas; Hatzidakis, Adam; Raissaki, Maria; Damilakis, John

2018-05-01

To assess the underestimation of radiation dose to the thyroid of children undergoing contrast enhanced CT if contrast medium uptake is not taken into account. 161 pediatric head, head & neck and chest CT examinations were retrospectively studied to identify those involving pre- and post-contrast imaging and thyroid inclusion in imaged volume. CT density of thyroid tissue in HU was measured in non-enhanced (NECT) and corresponding contrast-enhanced CT (CECT) images. Resulting CT number increase (ΔHU) was recorded for each patient and corresponded to a % w/w iodine concentration. The relation of %w/w iodine concentration to %dose increase induced by iodinated contrast uptake was derived by Monte Carlo simulation experiments. The thyroid gland was visible in 11 chest and 3 neck CT examinations involving both pre- and post-contrast imaging. The %w/w concentration of iodine in the thyroid tissue at the time of CECT acquisition was found to be 0.13%-0.58% w/w (mean = 0.26%). The %increase of dose to thyroid tissue was found to be linearly correlated to%w/w iodine uptake. The increase in radiation dose to thyroid due to contrast uptake ranged from 12% to 44%, with a mean value of 23%. The radiation dose to the pediatric thyroid from CECT exposure may be underestimated by up to 44% if contrast medium uptake is not taken into account. Meticulous demarcation of imaged volume in pediatric chest CT examinations is imperative to avoid unnecessary direct exposure of thyroid, especially in CT examinations following intravenous administration of contrast medium. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
Stability of Balloon-Retention Gastrostomy Tubes with Different Concentrations of Contrast Material: In Vitro Study

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

Lopera, Jorge E., E-mail: Lopera@uthscsa.ed; Alvarez, Alex; Trimmer, Clayton

2009-01-15

The purpose of this study was to determine the performance of two balloon-retention-type gastrostomy tubes when the balloons are inflated with two types of contrast materials at different concentrations. Two commonly used balloon-retention-type tubes (MIC and Tri-Funnel) were inflated to the manufacturer's recommended volumes (4 and 20 cm{sup 3}, respectively) with normal saline or normal saline plus different concentrations of contrast material. Five tubes of each brand were inflated with normal saline and 0%, 25%, 50%, 75%, and 100% contrast material dilutions, using either nonionic hyperosmolar contrast, or nonionic iso-osmolar contrast. The tubes were submerged in a glass basin containingmore » a solution with a pH of 4. Every week the tubes were visually inspected to determine the integrity of the balloons, and the diameter of the balloons was measured with a caliper. The tests were repeated every week for a total of 12 weeks. The MIC balloons deflated slightly faster over time than the Tri-Funnel balloons. The Tri-Funnel balloons remained relatively stable over the study period for the different concentrations of contrast materials. The deflation rates of the MIC balloons were proportionally related to the concentration of saline and inversely related to the concentration of the contrast material. At high contrast material concentrations, solidification of the balloons was observed. In conclusion, this in vitro study confirms that the use of diluted amounts of nonionic contrast materials is safe for inflating the balloons of two types of balloon-retention feeding tubes. High concentrations of contrast could result in solidification of the balloons and should be avoided.« less
Post-traumatic stress disorder, social anxiety disorder, and depression in survivors of the Kosovo War: experiential avoidance as a contributor to distress and quality of life.

PubMed

Kashdan, Todd B; Morina, Nexhmedin; Priebe, Stefan

2009-03-01

Few studies have been conducted on psychological disorders other than post-traumatic stress disorder (PTSD) in war survivors. The aim of this study was to examine PTSD, social anxiety disorder (SAD), and major depressive disorder (MDD) and their associations with distress and quality of life in 174 Albanian civilian survivors of the Kosovo War. This included testing of conceptual models suggesting that experiential avoidance might influence associations between anxiety and mood disorders with psychological functioning. Each of the three psychiatric disorders was associated with greater experiential avoidance and psychological distress, and lower quality of life. Being a refugee was associated with a higher likelihood of having SAD and MDD. We found evidence for experiential avoidance as a partial mediator of the respective effects of SAD and PTSD on quality of life; experiential avoidance did not mediate the effects of disorders on global distress. We also found support for a moderation model showing that only war survivors without SAD and low experiential avoidance reported elevated quality of life; people with either SAD or excessive reliance on experiential avoidance reported compromised, low quality of life. This is the third independent study, each using a different methodology, to find empirical support for this moderation model [Kashdan, T. B., & Breen, W. E. (2008). Social anxiety and positive emotions: a prospective examination of a self-regulatory model with tendencies to suppress or express emotions as a moderating variable. Behavior Therapy, 39, 1-12; Kashdan, T. B., & Steger, M. F. (2006). Expanding the topography of social anxiety: an experience sampling assessment of positive emotions and events, and emotion suppression. Psychological Science, 17, 120-128]. Overall, we provided initial evidence for the importance of addressing PTSD, SAD, MDD, and experiential avoidance in primarily civilian war survivors.
Polar bears (Ursus maritimus), the most evolutionary advanced hibernators, avoid significant bone loss during hibernation.

PubMed

Lennox, Alanda R; Goodship, Allen E

2008-02-01

Some hibernating animals are known to reduce muscle and bone loss associated with mechanical unloading during prolonged immobilisation,compared to humans. However, here we show that wild pregnant polar bears (Ursus maritimus) are the first known animals to avoid significant bone loss altogether, despite six months of continuous hibernation. Using serum biochemical markers of bone turnover, we showed that concentrations for bone resorption are not significantly increased as a consequence of hibernation in wild polar bears. This is in sharp contrast to previous studies on other hibernating species, where for example, black bears (Ursus americanus), show a 3-4 fold increase in serum bone resorption concentrations posthibernation,and must compensate for this loss through rapid bone recovery on remobilisation, to avoid the risk of fracture. In further contrast to black bears, serum concentrations of bone formation markers were highly significantly increased in pregnant female polar bears compared to non-pregnant,thus non-hibernating females both prior to and after hibernation. However, bone formation concentrations in new mothers were significantly reduced compared to pre-hibernation concentrations. The de-coupling of bone turnover in favour of bone formation prior to hibernation, suggests that wild polar bears may posses a unique physiological mechanism for building bone in protective preparation against expected osteopenia associated with disuse,starvation, and hormonal drives to mobilise calcium for reproduction, during hibernation. Understanding this physiological mechanism could have profound implications for a natural solution for the prevention of osteoporosis in animals subjected to captivity with inadequate space for exercise,humans subjected to prolonged bed rest while recovering from illness, or astronauts exposed to antigravity during spaceflight.© 2008 Elsevier Inc. All rights reserved.
It's the Motive That Counts: Perceived Sacrifice Motives and Gratitude in Romantic Relationships.

PubMed

Visserman, Mariko L; Righetti, Francesca; Impett, Emily A; Keltner, Dacher; Van Lange, Paul A M

2017-06-12

Gratitude is robustly linked to many positive outcomes for individuals and relationships (e.g., greater life and relationship satisfaction). However, little is known about how romantic partners come to feel grateful for each other's pro-relational acts, such as when a partner makes a sacrifice. The present research examines how perceptions of partner sacrifice motives evoke gratitude. We distinguish between partner, relationship, and self-focused motives, and how they are guided by approach or avoidance orientations. We expected that perceiving a partner to sacrifice for partner-focused approach motives (i.e., to promote the partner's well-being) should evoke gratitude, as this type of motive may signal a genuine departure from self-interest. Moreover, we expected these motives to provoke greater perceptions of partner responsiveness, which should partially explain why they elicit gratitude. In contrast, perceiving a partner to sacrifice for relationship-focused motives (e.g., to promote the well-being of the relationship), or self-focused motives (e.g., to feel good about oneself), should not evoke gratitude-irrespective of an approach or avoidance orientation-as these motives may, to some extent, be perceived as tainted by self-interest. Two studies of romantic couples (N = 413), using diary methods (Studies 1 and 2) and having couples converse about a major sacrifice in the laboratory (Study 2), consistently showed that perceived partner-focused approach motives promote gratitude and that this association is partly mediated by perceived partner responsiveness. In contrast, relationship and self-focused motives (approach and avoidance oriented) were not associated with gratitude. Implications regarding perceiving and displaying sacrifice motives are discussed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
An Avoidance Model for Short-Range Order Induced by Soft Repulsions in Systems of Rigid Rods

NASA Astrophysics Data System (ADS)

Han, Jining; Herzfeld, Judith

1996-03-01

The effects of soft repulsions on hard particle systems are calculated using an avoidance model which improves upon the simple mean field approximation. Avoidance reduces, but does not eliminate, the energy due to soft repulsions. On the other hand, it also reduces the configurational entropy. Under suitable conditions, this simple trade-off yields a free energy that is lower than the mean field value. In these cases, the variationally determined avoidance gives an estimate for the short-range positional order induced by soft repulsions. The results indicate little short-range order for isotropically oriented rods. However, for parallel rods, short-range order increases to significant levels as the particle axial ratio increases. The implications for long- range positional ordering are also discussed. In particular, avoidance may explain the smectic ordering of tobacco mosaic virus at volume fractions lower than those necessary for smectic ordering of hard particles.

Key conclusions from AVOID Work Stream One

NASA Astrophysics Data System (ADS)

Warren, Rachel

2010-05-01

AVOID work stream (WS1)one has produced emission scenarios that simulate potential future global emission pathways for greenhouse gases during the 21st century. The study explored the influence of three key features of such pathways: (1) the year in which emissions peak globally, (2) the rate of emission reduction, and (3) the minimum level to which emissions are eventually reduced. It examined the resultant climate change, climate change impacts and economic implications using computer simulations. Avoided impacts, carbon taxes and GDP change increase throughout the 21st century in the models. AVOID-WS1 showed that in the absence of climate policy it is very likely that global mean temperatures would exceed 3 degrees and there are evens chances that the temperature would rise by 4 degrees relative to pre-industrial times. Scenarios that peak emissions in 2016 were more effective at constraining temperatures to below 3 degrees than those that peaked in 2030: one ‘2016' scenario achieved a probability of 45% of avoiding breaching of a 2 degree threshold. Scenarios peaking in 2030 were inconsistent with constraining temperatures to below 2 degrees. Correspondingly, scenarios that peak in 2030 are more effective at avoiding climate impacts than scenarios that peak in 2016, for all sectors that we studied. Hence the date at which emissions peak is more important than the rate of subsequent emissions reduction in determining the avoided impacts. Avoided impacts increase with time, being negligible in the 2030s, significant by the 2050s and large by the 2080s. Finally, the choice of GCM influences the magnitude of the avoided impacts strongly, so that the uncertainties in our estimates of avoided impacts for each scenario are larger than the difference between the scenarios. Our economic analysis is based on models which differ greatly in the assumptions that they make, but generally show that the date at which emissions peak is a stronger driver of induced GDP changes, and, with some exceptions, carbon taxes, than the rate at which emissions are subsequently reduced. In models which assume perfect rationality and foresight and/or assume the economy to be equilibrium with full employment, then mitigation could cause GDP to decrease. In models which do not make these assumptions, mitigation could cause GDP to increase. In either case the effects are small (a few % of GDP lost or gained in 2100) and insignificant when compared with the 600-1200% increase in global GDP forecast between 2000 and 2100 in the SRES A1B reference scenario used in this study. Estimates of carbon taxes required differ widely between models.
Cost-effectiveness of natalizumab vs fingolimod for the treatment of relapsing-remitting multiple sclerosis: analyses in Sweden.

PubMed

O'Day, Ken; Meyer, Kellie; Stafkey-Mailey, Dana; Watson, Crystal

2015-04-01

To assess the cost-effectiveness of natalizumab vs fingolimod over 2 years in relapsing-remitting multiple sclerosis (RRMS) patients and patients with rapidly evolving severe disease in Sweden. A decision analytic model was developed to estimate the incremental cost per relapse avoided of natalizumab and fingolimod from the perspective of the Swedish healthcare system. Modeled 2-year costs in Swedish kronor of treating RRMS patients included drug acquisition costs, administration and monitoring costs, and costs of treating MS relapses. Effectiveness was measured in terms of MS relapses avoided using data from the AFFIRM and FREEDOMS trials for all patients with RRMS and from post-hoc sub-group analyses for patients with rapidly evolving severe disease. Probabilistic sensitivity analyses were conducted to assess uncertainty. The analysis showed that, in all patients with MS, treatment with fingolimod costs less (440,463 Kr vs 444,324 Kr), but treatment with natalizumab results in more relapses avoided (0.74 vs 0.59), resulting in an incremental cost-effectiveness ratio (ICER) of 25,448 Kr per relapse avoided. In patients with rapidly evolving severe disease, natalizumab dominated fingolimod. Results of the sensitivity analysis demonstrate the robustness of the model results. At a willingness-to-pay (WTP) threshold of 500,000 Kr per relapse avoided, natalizumab is cost-effective in >80% of simulations in both patient populations. Limitations include absence of data from direct head-to-head studies comparing natalizumab and fingolimod, use of relapse rate reduction rather than sustained disability progression as the primary model outcome, assumption of 100% adherence to MS treatment, and exclusion of adverse event costs in the model. Natalizumab remains a cost-effective treatment option for patients with MS in Sweden. In the RRMS patient population, the incremental cost per relapse avoided is well below a 500,000 Kr WTP threshold per relapse avoided. In the rapidly evolving severe disease patient population, natalizumab dominates fingolimod.
Adiabatic Quantum Search in Open Systems.

PubMed

Wild, Dominik S; Gopalakrishnan, Sarang; Knap, Michael; Yao, Norman Y; Lukin, Mikhail D

2016-10-07

Adiabatic quantum algorithms represent a promising approach to universal quantum computation. In isolated systems, a key limitation to such algorithms is the presence of avoided level crossings, where gaps become extremely small. In open quantum systems, the fundamental robustness of adiabatic algorithms remains unresolved. Here, we study the dynamics near an avoided level crossing associated with the adiabatic quantum search algorithm, when the system is coupled to a generic environment. At zero temperature, we find that the algorithm remains scalable provided the noise spectral density of the environment decays sufficiently fast at low frequencies. By contrast, higher order scattering processes render the algorithm inefficient at any finite temperature regardless of the spectral density, implying that no quantum speedup can be achieved. Extensions and implications for other adiabatic quantum algorithms will be discussed.
Stranger Fear and Early Risk for Social Anxiety in Preschoolers with Fragile X Syndrome Contrasted to Autism Spectrum Disorder.

PubMed

Scherr, Jessica F; Hogan, Abigail L; Hatton, Deborah; Roberts, Jane E

2017-12-01

This study investigated behavioral indicators of social fear in preschool boys with fragile X syndrome (FXS) with a low degree of autism spectrum disorder (ASD) symptoms (FXS-Low; n = 29), FXS with elevated ASD symptoms (FXS-High; n = 25), idiopathic ASD (iASD; n = 11), and typical development (TD; n = 36). Gaze avoidance, escape behaviors, and facial fear during a stranger approach were coded. Boys with elevated ASD symptoms displayed more avoidant gaze, looking less at the stranger and parent than those with low ASD symptoms across etiologies. The iASD group displayed more facial fear than the other groups. Results suggest etiologically distinct behavioral patterns of social fear in preschoolers with elevated ASD symptoms.
Navigating the interdependence dilemma: Attachment goals and the use of communal norms with potential close others.

PubMed

Bartz, Jennifer A; Lydon, John E

2006-07-01

Four studies investigated attachment in the context of new relationship development. Anxiously attached individuals overwhelmingly used communal norms and avoided using exchange norms when interacting with a potential close other; however, when a potential close other used communal norms, anxious individuals experienced increased interpersonal anxiety. Anxious individuals also used discrete communal behaviors to diagnose relationship potential. By contrast, secure individuals were more comfortable in potential communal situations. Moreover, implicit thoughts about closeness were associated with improved performance on a mental concentration task for secure individuals, whereas implicit closeness thoughts were associated with poorer performance for anxious individuals. Finally, avoidant individuals disliked the potential close other when the other used communal norms and downplayed relational motives for the other's communal behavior. Copyright 2006 APA, all rights reserved.
A Model of Parental Achievement-Oriented Psychological Control in Academically Gifted Students

ERIC Educational Resources Information Center

Garn, Alex C.; Jolly, Jennifer L.

2015-01-01

This study investigated achievement-oriented parent socialization as it pertains to school avoidance in a sample of gifted students. A serial mediation model examining relationships among parental achievement-oriented psychological control (APC), fear of academic failure, academic amotivation, and school avoidance was tested. The sample included…
Radiological contrast media in the breastfeeding woman: a position paper of the Italian Society of Radiology (SIRM), the Italian Society of Paediatrics (SIP), the Italian Society of Neonatology (SIN) and the Task Force on Breastfeeding, Ministry of Health, Italy.

PubMed

Cova, Maria Assunta; Stacul, Fulvio; Quaranta, Roberto; Guastalla, Pierpaolo; Salvatori, Guglielmo; Banderali, Giuseppe; Fonda, Claudio; David, Vincenzo; Gregori, Massimo; Zuppa, Antonio Alberto; Davanzo, Riccardo

2014-08-01

Breastfeeding is a well-recognised investment in the health of the mother-infant dyad. Nevertheless, many professionals still advise breastfeeding mothers to temporarily discontinue breastfeeding after contrast media imaging. Therefore, we performed this review to provide health professionals with basic knowledge and skills for appropriate use of contrast media. A joint working group of the Italian Society of Radiology (SIRM), Italian Society of Paediatrics (SIP), Italian Society of Neonatology (SIN) and Task Force on Breastfeeding, Ministry of Health, Italy prepared a review of the relevant medical literature on the safety profile of contrast media for the nursing infant/child. Breastfeeding is safe for the nursing infant of any post-conceptional age after administration of the majority of radiological contrast media to the mother; only gadolinium-based agents considered at high risk of nephrogenic systemic fibrosis (gadopentetate dimeglumine, gadodiamide, gadoversetamide) should be avoided in the breastfeeding woman as a precaution; there is no need to temporarily discontinue breastfeeding or to express and discard breast milk following the administration of contrast media assessed as compatible with breastfeeding. Breastfeeding women should receive unambiguous professional advice and clear encouragement to continue breastfeeding after imaging with the compatible contrast media. • Breastfeeding is a well-known investment in the health of the mother-infant dyad. • Breastfeeding is safe after administration of contrast media to the mother. • There is no need to temporarily discontinue breastfeeding following administration of contrast media.
The real-world problem of care coordination: a longitudinal qualitative study with patients living with advanced progressive illness and their unpaid caregivers.

PubMed

Daveson, Barbara A; Harding, Richard; Shipman, Cathy; Mason, Bruce L; Epiphaniou, Eleni; Higginson, Irene J; Ellis-Smith, Clare; Henson, Lesley; Munday, Dan; Nanton, Veronica; Dale, Jeremy R; Boyd, Kirsty; Worth, Allison; Barclay, Stephen; Donaldson, Anne; Murray, Scott

2014-01-01

To develop a model of care coordination for patients living with advanced progressive illness and their unpaid caregivers, and to understand their perspective regarding care coordination. A prospective longitudinal, multi-perspective qualitative study involving a case-study approach. Serial in-depth interviews were conducted, transcribed verbatim and then analyzed through open and axial coding in order to construct categories for three cases (sites). This was followed by continued thematic analysis to identify underlying conceptual coherence across all cases in order to produce one coherent care coordination model. Fifty-six purposively sampled patients and 27 case-linked unpaid caregivers. Three cases from contrasting primary, secondary and tertiary settings within Britain. Coordination is a deliberate cross-cutting action that involves high-quality, caring and well-informed staff, patients and unpaid caregivers who must work in partnership together across health and social care settings. For coordination to occur, it must be adequately resourced with efficient systems and services that communicate. Patients and unpaid caregivers contribute substantially to the coordination of their care, which is sometimes volunteered at a personal cost to them. Coordination is facilitated through flexible and patient-centered care, characterized by accurate and timely information communicated in a way that considers patients' and caregivers' needs, preferences, circumstances and abilities. Within the midst of advanced progressive illness, coordination is a shared and complex intervention involving relational, structural and information components. Our study is one of the first to extensively examine patients' and caregivers' views about coordination, thus aiding conceptual fidelity. These findings can be used to help avoid oversimplifying a real-world problem, such as care coordination. Avoiding oversimplification can help with the development, evaluation and implementation of real-world coordination interventions for patients and their unpaid caregivers in the future.
Impact of the Montreal Protocol on Antarctic Surface Mass Balance

NASA Astrophysics Data System (ADS)

Previdi, M. J.; Polvani, L. M.

2016-12-01

We investigate the impact of the Montreal Protocol, and associated phase-out of ozone-depleting substances (ODSs), on the surface mass balance (SMB) of Antarctica, using simulations from the Community Earth System Model-Whole Atmosphere Community Climate Model (CESM-WACCM). The effect of ODSs on Antarctic SMB is first established by contrasting two sets of WACCM integrations (each with 6 ensemble members) for the period 1956-2005: one set that includes the full suite of natural and anthropogenic forcings, and a second set identical to the first but with atmospheric concentrations of ODSs held fixed at year 1955 levels. We find that holding ODSs fixed reduces the simulated increase in Antarctic SMB by nearly 60% in the ensemble mean, due to a suppression of Antarctic-mean warming. Having established this SMB impact of ODSs, we next examine three sets of future WACCM integrations (each with 3 ensemble members) for the period 2006-2065. The first two of these are the CMIP5 RCP4.5 and RCP8.5 integrations that include decreases in ODSs due to the implementation of the Montreal Protocol, and increases in other well-mixed greenhouse gases such as CO2. The third set of future integrations represents a hypothetical "world avoided" scenario in which the Montreal Protocol is assumed to have never been implemented, resulting in drastic increases in ODSs during the next several decades. In the world avoided, the simulated increase in Antarctic SMB is substantially larger than the other two scenarios, exceeding the SMB increases occurring under RCP4.5 and RCP8.5 by a factor of 3.7 and 1.9, respectively. The implications of this for future global sea-level rise will be discussed.
Improving In Vivo High-Resolution CT Imaging of the Tumour Vasculature in Xenograft Mouse Models through Reduction of Motion and Bone-Streak Artefacts

PubMed Central

Kersemans, Veerle; Kannan, Pavitra; Beech, John S.; Bates, Russell; Irving, Benjamin; Gilchrist, Stuart; Allen, Philip D.; Thompson, James; Kinchesh, Paul; Casteleyn, Christophe; Schnabel, Julia; Partridge, Mike; Muschel, Ruth J.; Smart, Sean C.

2015-01-01

Introduction Preclinical in vivo CT is commonly used to visualise vessels at a macroscopic scale. However, it is prone to many artefacts which can degrade the quality of CT images significantly. Although some artefacts can be partially corrected for during image processing, they are best avoided during acquisition. Here, a novel imaging cradle and tumour holder was designed to maximise CT resolution. This approach was used to improve preclinical in vivo imaging of the tumour vasculature. Procedures A custom built cradle containing a tumour holder was developed and fix-mounted to the CT system gantry to avoid artefacts arising from scanner vibrations and out-of-field sample positioning. The tumour holder separated the tumour from bones along the axis of rotation of the CT scanner to avoid bone-streaking. It also kept the tumour stationary and insensitive to respiratory motion. System performance was evaluated in terms of tumour immobilisation and reduction of motion and bone artefacts. Pre- and post-contrast CT followed by sequential DCE-MRI of the tumour vasculature in xenograft transplanted mice was performed to confirm vessel patency and demonstrate the multimodal capacity of the new cradle. Vessel characteristics such as diameter, and branching were quantified. Results Image artefacts originating from bones and out-of-field sample positioning were avoided whilst those resulting from motions were reduced significantly, thereby maximising the resolution that can be achieved with CT imaging in vivo. Tumour vessels ≥ 77 μm could be resolved and blood flow to the tumour remained functional. The diameter of each tumour vessel was determined and plotted as histograms and vessel branching maps were created. Multimodal imaging using this cradle assembly was preserved and demonstrated. Conclusions The presented imaging workflow minimised image artefacts arising from scanner induced vibrations, respiratory motion and radiopaque structures and enabled in vivo CT imaging and quantitative analysis of the tumour vasculature at higher resolution than was possible before. Moreover, it can be applied in a multimodal setting, therefore combining anatomical and dynamic information. PMID:26046526
Modified, Packaged Tortillas Have Long Shelf Life

NASA Technical Reports Server (NTRS)

Bourland, Charles; Glaus-Late, Kimberly

1995-01-01

Tortillas made from modified recipe and sealed in low-pressure nitrogen in foil pouches in effort to increase their shelf life at room temperature. Preliminary tests show that shelf life of these tortillas at least five months; in contrast, commercial tortillas last only few days. Part of water in recipe replaced with glycerin. Particularly necessary to avoid Clostridium botulinum, which grows in anaerobic environments and produces deadly toxin that causes botulism.
A bio-inspired kinematic controller for obstacle avoidance during reaching tasks with real robots.

PubMed

Srinivasa, Narayan; Bhattacharyya, Rajan; Sundareswara, Rashmi; Lee, Craig; Grossberg, Stephen

2012-11-01

This paper describes a redundant robot arm that is capable of learning to reach for targets in space in a self-organized fashion while avoiding obstacles. Self-generated movement commands that activate correlated visual, spatial and motor information are used to learn forward and inverse kinematic control models while moving in obstacle-free space using the Direction-to-Rotation Transform (DIRECT). Unlike prior DIRECT models, the learning process in this work was realized using an online Fuzzy ARTMAP learning algorithm. The DIRECT-based kinematic controller is fault tolerant and can handle a wide range of perturbations such as joint locking and the use of tools despite not having experienced them during learning. The DIRECT model was extended based on a novel reactive obstacle avoidance direction (DIRECT-ROAD) model to enable redundant robots to avoid obstacles in environments with simple obstacle configurations. However, certain configurations of obstacles in the environment prevented the robot from reaching the target with purely reactive obstacle avoidance. To address this complexity, a self-organized process of mental rehearsals of movements was modeled, inspired by human and animal experiments on reaching, to generate plans for movement execution using DIRECT-ROAD in complex environments. These mental rehearsals or plans are self-generated by using the Fuzzy ARTMAP algorithm to retrieve multiple solutions for reaching each target while accounting for all the obstacles in its environment. The key aspects of the proposed novel controller were illustrated first using simple examples. Experiments were then performed on real robot platforms to demonstrate successful obstacle avoidance during reaching tasks in real-world environments. Copyright © 2012 Elsevier Ltd. All rights reserved.
Prospective evaluation of oral gastrografin in postoperative small bowel obstruction.

PubMed

Kapoor, Sorabh; Jain, Gaurav; Sewkani, Ajit; Sharma, Sandesh; Patel, Kailash; Varshney, Subodh

2006-04-01

Orally administered gastrografin has been used for early resolution of postoperative small bowel obstruction (POSBO) and to reduce the need for surgery in various studies. However the studies have reported conflicting results as patients with complete obstruction and equivocal diagnosis of bowel strangulation were also included. We carried out a prospective study to evaluate the efficacy of gastrografin in patients with partial adhesive small bowel obstruction. Patients with suspected strangulation, complete obstruction, obstructed hernia, bowel malignancy, and radiation enteritis were excluded. Sixty-two patients with partial adhesive small bowel obstruction were given an initial trial of conservative management of 48 h. Thirty-eight patients improved within 48 h and the other 24 were given 100 ml of undiluted gastrografin through the nasogastric tube. In 22 patients the contrast reached the colon within 24 h. In the remaining two patients the contrast failed to reach the colon and these underwent surgery. The use of gastrografin avoided surgical intervention in 91.3% (22 of 24) patients who failed conservative management of POSBO. Gastrografin also decreased the overall requirement for surgical management of POSBO from the reported rate of 25 to 30% to 3.2% (2 of 62). Use of gastrografin in patients with partial POSBO helps in resolution of symptoms and avoids the need for surgical management in the majority of patients.
The psychology of doing nothing: forms of decision avoidance result from reason and emotion.

PubMed

Anderson, Christopher J

2003-01-01

Several independent lines of research bear on the question of why individuals avoid decisions by postponing them, failing to act, or accepting the status quo. This review relates findings across several different disciplines and uncovers 4 decision avoidance effects that offer insight into this common but troubling behavior: choice deferral, status quo bias, omission bias, and inaction inertia. These findings are related by common antecedents and consequences in a rational-emotional model of the factors that predispose humans to do nothing. Prominent components of the model include cost-benefit calculations, anticipated regret, and selection difficulty. Other factors affecting decision avoidance through these key components, such as anticipatory negative emotions, decision strategies, counterfactual thinking, and preference uncertainty, are also discussed.
Binocular combination of phase and contrast explained by a gain-control and gain-enhancement model

PubMed Central

Ding, Jian; Klein, Stanley A.; Levi, Dennis M.

2013-01-01

We investigated suprathreshold binocular combination, measuring both the perceived phase and perceived contrast of a cyclopean sine wave. We used a paradigm adapted from Ding and Sperling (2006, 2007) to measure the perceived phase by indicating the apparent location (phase) of the dark trough in the horizontal cyclopean sine wave relative to a black horizontal reference line, and we used the same stimuli to measure perceived contrast by matching the binocular combined contrast to a standard contrast presented to one eye. We found that under normal viewing conditions (high contrast and long stimulus duration), perceived contrast is constant, independent of the interocular contrast ratio and the interocular phase difference, while the perceived phase shifts smoothly from one eye to the other eye depending on the contrast ratios. However, at low contrasts and short stimulus durations, binocular combination is more linear and contrast summation is phase-dependent. To account for phase-dependent contrast summation, we incorporated a fusion remapping mechanism into our model, using disparity energy to shift the monocular phases towards the cyclopean phase in order to align the two eyes' images through motor/sensory fusion. The Ding-Sperling model with motor/sensory fusion mechanism gives a reasonable account of the phase dependence of binocular contrast combination and can account for either the perceived phase or the perceived contrast of a cyclopean sine wave separately; however it requires different model parameters for the two. However, when fit to both phase and contrast data simultaneously, the Ding-Sperling model fails. Incorporating interocular gain enhancement into the model results in a significant improvement in fitting both phase and contrast data simultaneously, successfully accounting for both linear summation at low contrast energy and strong nonlinearity at high contrast energy. PMID:23397038
Exploratory behaviour in the open field test adapted for larval zebrafish: impact of environmental complexity.

PubMed

Ahmad, Farooq; Richardson, Michael K

2013-01-01

This study aimed to develop and characterize a novel (standard) open field test adapted for larval zebrafish. We also developed and characterized a variant of the same assay consisting of a colour-enriched open field; this was used to assess the impact of environmental complexity on patterns of exploratory behaviours as well to determine natural colour preference/avoidance. We report the following main findings: (1) zebrafish larvae display characteristic patterns of exploratory behaviours in the standard open field, such as thigmotaxis/centre avoidance; (2) environmental complexity (i.e. presence of colours) differentially affects patterns of exploratory behaviours and greatly attenuates natural zone preference; (3) larvae displayed the ability to discriminate colours. As reported previously in adult zebrafish, larvae showed avoidance towards blue and black; however, in contrast to the reported adult behaviour, larvae displayed avoidance towards red. Avoidance towards yellow and preference for green and orange are shown for the first time, (4) compared to standard open field tests, exposure to the colour-enriched open field resulted in an enhanced expression of anxiety-like behaviours. To conclude, we not only developed and adapted a traditional rodent behavioural assay that serves as a gold standard in preclinical drug screening, but we also provide a version of the same test that affords the possibility to investigate the impact of environmental stress on behaviour in larval zebrafish while representing the first test for assessment of natural colour preference/avoidance in larval zebrafish. In the future, these assays will improve preclinical drug screening methodologies towards the goal to uncover novel drugs. This article is part of a Special Issue entitled: insert SI title. Copyright © 2012 Elsevier B.V. All rights reserved.
Sensitivity of the Endogeic Tropical Earthworm Pontoscolex corethrurus to the Presence of Heavy Crude Oil.

PubMed

Del Carmen Cuevas-Díaz, María; Vázquez-Luna, Dinora; Martínez-Hernández, Sergio; Guzmán-López, Oswaldo; Ortíz-Ceballos, Angel I

2017-08-01

Contamination of soil with petroleum is common in oil-producing areas across the tropical regions of the world. There is limited knowledge on the sensitivity of endogeic tropical earthworms to the contamination of soil with total petroleum hydrocarbons (TPH) present in crude oil. Pontoscolex corethrurus is a dominant species in tropical agroecosystems around oil-processing facilities. The sensitivity of P. corethrurus to soil artificially contaminated with "Maya" Mexican heavy crude oil was investigated through avoidance and acute ecotoxicity tests, using the following measured concentrations: 0 (reference soil), 551, 969, 4845, 9991 and 14,869 mg/kg. The avoidance test showed that P. corethrurus displayed a significant avoidance behavior to heavy crude oil at a concentration of 9991 mg/kg or higher. In contrast, acute toxicity tests indicate that the median lethal concentration (LC 50 ) was 3067.32 mg/kg; however, growth (weight loss) was more sensitive than mortality. Our study revealed that P. corethrurus is sensitive to TPH, thus highlighting the importance of P. corethrurus for petroleum ecotoxicological tests.
Contrasting motivational orientation and evaluative coding accounts: on the need to differentiate the effectors of approach/avoidance responses.

PubMed

Kozlik, Julia; Neumann, Roland; Lozo, Ljubica

2015-01-01

Several emotion theorists suggest that valenced stimuli automatically trigger motivational orientations and thereby facilitate corresponding behavior. Positive stimuli were thought to activate approach motivational circuits which in turn primed approach-related behavioral tendencies whereas negative stimuli were supposed to activate avoidance motivational circuits so that avoidance-related behavioral tendencies were primed (motivational orientation account). However, recent research suggests that typically observed affective stimulus-response compatibility phenomena might be entirely explained in terms of theories accounting for mechanisms of general action control instead of assuming motivational orientations to mediate the effects (evaluative coding account). In what follows, we explore to what extent this notion is applicable. We present literature suggesting that evaluative coding mechanisms indeed influence a wide variety of affective stimulus-response compatibility phenomena. However, the evaluative coding account does not seem to be sufficient to explain affective S-R compatibility effects. Instead, several studies provide clear evidence in favor of the motivational orientation account that seems to operate independently of evaluative coding mechanisms. Implications for theoretical developments and future research designs are discussed.
Contrasting motivational orientation and evaluative coding accounts: on the need to differentiate the effectors of approach/avoidance responses

PubMed Central

Kozlik, Julia; Neumann, Roland; Lozo, Ljubica

2015-01-01

Several emotion theorists suggest that valenced stimuli automatically trigger motivational orientations and thereby facilitate corresponding behavior. Positive stimuli were thought to activate approach motivational circuits which in turn primed approach-related behavioral tendencies whereas negative stimuli were supposed to activate avoidance motivational circuits so that avoidance-related behavioral tendencies were primed (motivational orientation account). However, recent research suggests that typically observed affective stimulus–response compatibility phenomena might be entirely explained in terms of theories accounting for mechanisms of general action control instead of assuming motivational orientations to mediate the effects (evaluative coding account). In what follows, we explore to what extent this notion is applicable. We present literature suggesting that evaluative coding mechanisms indeed influence a wide variety of affective stimulus–response compatibility phenomena. However, the evaluative coding account does not seem to be sufficient to explain affective S–R compatibility effects. Instead, several studies provide clear evidence in favor of the motivational orientation account that seems to operate independently of evaluative coding mechanisms. Implications for theoretical developments and future research designs are discussed. PMID:25983718
The effects of social stress and cortisol responses on the preconscious selective attention to social threat.

PubMed

Roelofs, Karin; Bakvis, Patricia; Hermans, Erno J; van Pelt, Johannes; van Honk, Jack

2007-04-01

The purpose of the present study was to investigate the effects of social stress and stress-induced cortisol on the preconscious selective attention to social threat. Twenty healthy participants were administered a masked emotional Stroop task (comparing color-naming latencies for angry, neutral and happy faces) in conditions of rest and social stress. Stress was induced by means of the Trier social stress test. Based on the stress-induced increase in cortisol levels, participants were allocated post hoc (median-split) to a high and low responders group. In contrast to low responders, high responders showed a negative or avoidant attentional bias to threat (i.e. shorter latencies for angry than neutral faces) in the rest condition. Most importantly, although low responders became avoidant, the high responders became vigilant to the angry faces after stress induction. There were no such effects for happy faces. Our findings are in line with previous studies in both animals and humans, that associate high glucocorticoid stress-responsiveness with diminished avoidance and prolonged freezing reactions during stress.

Technical Note: A generic law-of-the-minimum flux limiter for simulating substrate limitation in biogeochemical models

DOE PAGES

Tang, J. Y.; Riley, W. J.

2016-02-05

We present a generic flux limiter to account for mass limitations from an arbitrary number of substrates in a biogeochemical reaction network. The flux limiter is based on the observation that substrate (e.g., nitrogen, phosphorus) limitation in biogeochemical models can be represented as to ensure mass conservative and non-negative numerical solutions to the governing ordinary differential equations. Application of the flux limiter includes two steps: (1) formulation of the biogeochemical processes with a matrix of stoichiometric coefficients and (2) application of Liebig's law of the minimum using the dynamic stoichiometric relationship of the reactants. This approach contrasts with the ad hoc down-regulationmore » approaches that are implemented in many existing models (such as CLM4.5 and the ACME (Accelerated Climate Modeling for Energy) Land Model (ALM)) of carbon and nutrient interactions, which are error prone when adding new processes, even for experienced modelers. Through an example implementation with a CENTURY-like decomposition model that includes carbon, nitrogen, and phosphorus, we show that our approach (1) produced almost identical results to that from the ad hoc down-regulation approaches under non-limiting nutrient conditions, (2) properly resolved the negative solutions under substrate-limited conditions where the simple clipping approach failed, (3) successfully avoided the potential conceptual ambiguities that are implied by those ad hoc down-regulation approaches. We expect our approach will make future biogeochemical models easier to improve and more robust.« less
Waking the undead: Implications of a soft explosive model for the timing of placental mammal diversification.

PubMed

Springer, Mark S; Emerling, Christopher A; Meredith, Robert W; Janečka, Jan E; Eizirik, Eduardo; Murphy, William J

2017-01-01

The explosive, long fuse, and short fuse models represent competing hypotheses for the timing of placental mammal diversification. Support for the explosive model, which posits both interordinal and intraordinal diversification after the KPg mass extinction, derives from morphological cladistic studies that place Cretaceous eutherians outside of crown Placentalia. By contrast, most molecular studies favor the long fuse model wherein interordinal cladogenesis occurred in the Cretaceous followed by intraordinal cladogenesis after the KPg boundary. Phillips (2016) proposed a soft explosive model that allows for the emergence of a few lineages (Xenarthra, Afrotheria, Euarchontoglires, Laurasiatheria) in the Cretaceous, but otherwise agrees with the explosive model in positing the majority of interordinal diversification after the KPg mass extinction. Phillips (2016) argues that rate transference errors associated with large body size and long lifespan have inflated previous estimates of interordinal divergence times, and further suggests that most interordinal divergences are positioned after the KPg boundary when rate transference errors are avoided through the elimination of calibrations in large-bodied and/or long lifespan clades. Here, we show that rate transference errors can also occur in the opposite direction and drag forward estimated divergence dates when calibrations in large-bodied/long lifespan clades are omitted. This dragging forward effect results in the occurrence of more than half a billion years of 'zombie lineages' on Phillips' preferred timetree. By contrast with ghost lineages, which are a logical byproduct of an incomplete fossil record, zombie lineages occur when estimated divergence dates are younger than the minimum age of the oldest crown fossils. We also present the results of new timetree analyses that address the rate transference problem highlighted by Phillips (2016) by deleting taxa that exceed thresholds for body size and lifespan. These analyses recover all interordinal divergence times in the Cretaceous and are consistent with the long fuse model of placental diversification. Finally, we outline potential problems with morphological cladistic analyses of higher-level relationships among placental mammals that may account for the perceived discrepancies between molecular and paleontological estimates of placental divergence times. Copyright © 2016 Elsevier Inc. All rights reserved.
Avoidant coping partially mediates the relationship between patient problem behaviors and depressive symptoms in spousal Alzheimer caregivers.

PubMed

Mausbach, Brent T; Aschbacher, Kirstin; Patterson, Thomas L; Ancoli-Israel, Sonia; von Känel, Roland; Mills, Paul J; Dimsdale, Joel E; Grant, Igor

2006-04-01

Caring for a loved one with Alzheimer disease is a highly stressful experience that is associated with significant depressive symptoms. Previous studies indicate a positive association between problem behaviors in patients with Alzheimer disease (e.g., repeating questions, restlessness, and agitation) and depressive symptoms in their caregivers. Moreover, the extant literature indicates a robust negative relationship between escape-avoidance coping (i.e., avoiding people, wishing the situation would go away) and psychiatric well-being. The purpose of this study was to test a mediational model of the associations between patient problem behaviors, escape-avoidance coping, and depressive symptoms in Alzheimer caregivers. Ninety-five spousal caregivers (mean age: 72 years) completed measures assessing their loved ones' frequency of problem behaviors, escape-avoidance coping, and depressive symptoms. A mediational model was tested to determine if escape-avoidant coping partially mediated the relationship between patient problem behaviors and caregiver depressive symptoms. Patient problem behaviors were positively associated with escape-avoidance coping (beta = 0.38, p < 0.01) and depressive symptoms (beta = 0.26, p < 0.05). Escape-avoidance coping was positively associated with depressive symptoms (beta = 0.33, p < 0.01). In a final regression analysis, the impact of problem behaviors on depressive symptoms was less after controlling for escape-avoidance coping. Sobel's test confirmed that escape-avoidance coping significantly mediated the relationship between problem behaviors and depressive symptoms (z = 2.07, p < 0.05). Escape-avoidance coping partially mediates the association between patient problem behaviors and depressive symptoms among elderly caregivers of spouses with dementia. This finding provides a specific target for psychosocial interventions for caregivers.
Modeling the effects of contrast enhancement on target acquisition performance

NASA Astrophysics Data System (ADS)

Du Bosq, Todd W.; Fanning, Jonathan D.

2008-04-01

Contrast enhancement and dynamic range compression are currently being used to improve the performance of infrared imagers by increasing the contrast between the target and the scene content, by better utilizing the available gray levels either globally or locally. This paper assesses the range-performance effects of various contrast enhancement algorithms for target identification with well contrasted vehicles. Human perception experiments were performed to determine field performance using contrast enhancement on the U.S. Army RDECOM CERDEC NVESD standard military eight target set using an un-cooled LWIR camera. The experiments compare the identification performance of observers viewing linearly scaled images and various contrast enhancement processed images. Contrast enhancement is modeled in the US Army thermal target acquisition model (NVThermIP) by changing the scene contrast temperature. The model predicts improved performance based on any improved target contrast, regardless of feature saturation or enhancement. To account for the equivalent blur associated with each contrast enhancement algorithm, an additional effective MTF was calculated and added to the model. The measured results are compared with the predicted performance based on the target task difficulty metric used in NVThermIP.
Is there an association between fear avoidance beliefs, and pain and disability in patients with orofacial pain?

PubMed

Edmond, S L; Enriquez, C S; Millner, M H; Nasri-Heir, C; Heir, G M

2017-06-01

Numerous psychosocial factors have been shown to contribute to the development and perpetuation of orofacial pain. One well-recognized model for explaining the link between psychosocial factors and chronic pain is the fear avoidance model. To date, this proposed link has not been studied in subjects with orofacial pain. During the initial evaluation of subjects with orofacial pain, we collected data on fear avoidance beliefs using the Fear Avoidance Beliefs Questionnaire, and disability and pain. At between 6 and 8 weeks follow-up, we re-collected these data, as well as data addressing subjects' perceived change in their condition. Data were analyzed using correlation coefficients and linear regression. Fear avoidance beliefs at intake were inversely correlated with intake disability, There were no significant associations between fear avoidance beliefs at initial evaluation or in changes in fear avoidance beliefs during the 6-8 weeks follow-up period; and changes in disability, pain or perceived change in condition at 6-8 weeks follow-up. Of note, fear avoidance beliefs increased over the follow-up period, despite improvements in all outcome measures. There was insufficient evidence to suggest that high levels of fear avoidance beliefs at initial evaluation are associated with higher levels of disability or pain at intake, or with change in disability, pain or perceived change in condition at 6-8 weeks follow-up. Similarly, there was insufficient evidence to suggest that changes in fear avoidance beliefs during treatment are associated with any of these outcome measures. © 2017 John Wiley & Sons Ltd.
Predictors and outcome of pain-related avoidance of activities in persons with early symptomatic knee osteoarthritis: a five-year followup study.

PubMed

Holla, Jasmijn F M; van der Leeden, Marike; Knol, Dirk L; Roorda, Leo D; Hilberdink, Wim K H A; Lems, Willem F; Steultjens, Martijn P M; Dekker, Joost

2015-01-01

It has been hypothesized that pain and low vitality lead to an increase in avoidance of activities in persons with early symptomatic knee osteoarthritis (OA), and that avoidance of activities leads to an increase in activity limitations. The present study aimed to evaluate these hypotheses. Baseline, 2-year, and 5-year followup data of 828 participants from the Cohort Hip and Cohort Knee Study with early symptomatic knee OA were used. Autoregressive generalized estimating equations and linear regression models were used to analyze the longitudinal and cross-sectional associations between self-reported knee pain, vitality, pain-related avoidance of activities, and activity limitations. The models were adjusted for the covariates age, sex, education level, body mass index, comorbidity, radiographic severity, and hip pain. In longitudinal analyses, knee pain and vitality predicted a subsequent increase in avoidance of activities. Pain-related avoidance of activities predicted a subsequent increase in activity limitations; however, this relationship lost statistical significance (P = 0.089) after adjustment for covariates. Cross-sectional analyses showed strong relationships between knee pain, low vitality, pain-related avoidance of activities, and activity limitations at all time points. In persons with early symptomatic knee OA, knee pain and low vitality lead to a subsequent increase in avoidance of activities. Pain-related avoidance of activities is related to activity limitations at inception of symptoms, but also years later. Therefore, it can be recommended to monitor and target avoidance of activities at various stages of the disease. Copyright © 2015 by the American College of Rheumatology.
Primary epiploic appendagitis and successful outpatient management

PubMed Central

Schnedl, Wolfgang J.; Krause, Robert; Wallner-Liebmann, Sandra J.; Tafeit, Erwin; Mangge, Harald; Tillich, Manfred

2012-01-01

Summary Background Primary epiploic appendagitis (PEA) is a rare cause of abdominal acute or subacute complaints. Diagnosis of PEA is made with ultrasonography (US) or when computed tomography (CT) reveals a characteristic lesion. Case Report We report on two patients with PEA. In one patient PEA was first seen with US and confirmed with contrast enhanced CT, and in the second patient CT without contrast enhancement demonstrated PEA. In both patients an outpatient recovery with conservative non-surgical treatment is described. Conclusions Medical personnel should be aware of this rare disease, which mimics many other intra-abdominal acute and subacute conditions. A correct diagnosis of PEA with imaging procedures enables conservative and successful outpatient management avoiding unnecessary surgical intervention and additional costs. PMID:22648258
A Flexible Latent Class Approach to Estimating Test-Score Reliability

ERIC Educational Resources Information Center

van der Palm, Daniël W.; van der Ark, L. Andries; Sijtsma, Klaas

2014-01-01

The latent class reliability coefficient (LCRC) is improved by using the divisive latent class model instead of the unrestricted latent class model. This results in the divisive latent class reliability coefficient (DLCRC), which unlike LCRC avoids making subjective decisions about the best solution and thus avoids judgment error. A computational…
Communicating to Farmers about Skin Cancer: The Behavior Adaptation Model.

ERIC Educational Resources Information Center

Parrott, Roxanne; Monahan, Jennifer; Ainsworth, Stuart; Steiner, Carol

1998-01-01

States health campaign messages designed to encourage behavior adaptation have greater likelihood of success than campaigns promoting avoidance of at-risk behaviors that cannot be avoided. Tests a model of health risk behavior using four different behaviors in a communication campaign aimed at reducing farmers' risk for skin cancer--questions…
Measuring Experiential Avoidance: A Preliminary Test of a Working Model

ERIC Educational Resources Information Center

Hayes, Steven C.; Strosahl, Kirk; Wilson, Kelly G.; Bissett, Richard T.; Pistorello, Jacqueline; Toarmino, Dosheen; Polusny, Melissa A.; Dykstra, Thane A.; Batten, Sonja V.; Bergan, John; Stewart, Sherry H.; Zvolensky, Michael J.; Eifert, Georg H.; Bond, Frank W.; Forsyth, John P.; Karekla, Maria; Mccurry, Susan M.

2004-01-01

The present study describes the development of a short, general measure of experiential avoidance, based on a specific theoretical approach to this process. A theoretically driven iterative exploratory analysis using structural equation modeling on data from a clinical sample yielded a single factor comprising 9 items. A fully confirmatory factor…
Robot body self-modeling algorithm: a collision-free motion planning approach for humanoids.

PubMed

Leylavi Shoushtari, Ali

2016-01-01

Motion planning for humanoid robots is one of the critical issues due to the high redundancy and theoretical and technical considerations e.g. stability, motion feasibility and collision avoidance. The strategies which central nervous system employs to plan, signal and control the human movements are a source of inspiration to deal with the mentioned problems. Self-modeling is a concept inspired by body self-awareness in human. In this research it is integrated in an optimal motion planning framework in order to detect and avoid collision of the manipulated object with the humanoid body during performing a dynamic task. Twelve parametric functions are designed as self-models to determine the boundary of humanoid's body. Later, the boundaries which mathematically defined by the self-models are employed to calculate the safe region for box to avoid the collision with the robot. Four different objective functions are employed in motion simulation to validate the robustness of algorithm under different dynamics. The results also confirm the collision avoidance, reality and stability of the predicted motion.
Obstacle avoidance in social groups: new insights from asynchronous models

PubMed Central

Croft, Simon; Budgey, Richard; Pitchford, Jonathan W.; Wood, A. Jamie

2015-01-01

For moving animals, the successful avoidance of hazardous obstacles is an important capability. Despite this, few models of collective motion have addressed the relationship between behavioural and social features and obstacle avoidance. We develop an asynchronous individual-based model for social movement which allows social structure within groups to be included. We assess the dynamics of group navigation and resulting collision risk in the context of information transfer through the system. In agreement with previous work, we find that group size has a nonlinear effect on collision risk. We implement examples of possible network structures to explore the impact social preferences have on collision risk. We show that any social heterogeneity induces greater obstacle avoidance with further improvements corresponding to groups containing fewer influential individuals. The model provides a platform for both further theoretical investigation and practical application. In particular, we argue that the role of social structures within bird flocks may have an important role to play in assessing the risk of collisions with wind turbines, but that new methods of data analysis are needed to identify these social structures. PMID:25833245
Disentangling and modeling interactions in fish with burst-and-coast swimming reveal distinct alignment and attraction behaviors

PubMed Central

Calovi, Daniel S.; Litchinko, Alexandra; Lopez, Ugo; Chaté, Hugues; Sire, Clément

2018-01-01

The development of tracking methods for automatically quantifying individual behavior and social interactions in animal groups has open up new perspectives for building quantitative and predictive models of collective behavior. In this work, we combine extensive data analyses with a modeling approach to measure, disentangle, and reconstruct the actual functional form of interactions involved in the coordination of swimming in Rummy-nose tetra (Hemigrammus rhodostomus). This species of fish performs burst-and-coast swimming behavior that consists of sudden heading changes combined with brief accelerations followed by quasi-passive, straight decelerations. We quantify the spontaneous stochastic behavior of a fish and the interactions that govern wall avoidance and the reaction to a neighboring fish, the latter by exploiting general symmetry constraints for the interactions. In contrast with previous experimental works, we find that both attraction and alignment behaviors control the reaction of fish to a neighbor. We then exploit these results to build a model of spontaneous burst-and-coast swimming and interactions of fish, with all parameters being estimated or directly measured from experiments. This model quantitatively reproduces the key features of the motion and spatial distributions observed in experiments with a single fish and with two fish. This demonstrates the power of our method that exploits large amounts of data for disentangling and fully characterizing the interactions that govern collective behaviors in animals groups. PMID:29324853
A global multiscale mathematical model for the human circulation with emphasis on the venous system.

PubMed

Müller, Lucas O; Toro, Eleuterio F

2014-07-01

We present a global, closed-loop, multiscale mathematical model for the human circulation including the arterial system, the venous system, the heart, the pulmonary circulation and the microcirculation. A distinctive feature of our model is the detailed description of the venous system, particularly for intracranial and extracranial veins. Medium to large vessels are described by one-dimensional hyperbolic systems while the rest of the components are described by zero-dimensional models represented by differential-algebraic equations. Robust, high-order accurate numerical methodology is implemented for solving the hyperbolic equations, which are adopted from a recent reformulation that includes variable material properties. Because of the large intersubject variability of the venous system, we perform a patient-specific characterization of major veins of the head and neck using MRI data. Computational results are carefully validated using published data for the arterial system and most regions of the venous system. For head and neck veins, validation is carried out through a detailed comparison of simulation results against patient-specific phase-contrast MRI flow quantification data. A merit of our model is its global, closed-loop character; the imposition of highly artificial boundary conditions is avoided. Applications in mind include a vast range of medical conditions. Of particular interest is the study of some neurodegenerative diseases, whose venous haemodynamic connection has recently been identified by medical researchers. Copyright © 2014 John Wiley & Sons, Ltd.
Predicting all-cause risk of 30-day hospital readmission using artificial neural networks.

PubMed

Jamei, Mehdi; Nisnevich, Aleksandr; Wetchler, Everett; Sudat, Sylvia; Liu, Eric

2017-01-01

Avoidable hospital readmissions not only contribute to the high costs of healthcare in the US, but also have an impact on the quality of care for patients. Large scale adoption of Electronic Health Records (EHR) has created the opportunity to proactively identify patients with high risk of hospital readmission, and apply effective interventions to mitigate that risk. To that end, in the past, numerous machine-learning models have been employed to predict the risk of 30-day hospital readmission. However, the need for an accurate and real-time predictive model, suitable for hospital setting applications still exists. Here, using data from more than 300,000 hospital stays in California from Sutter Health's EHR system, we built and tested an artificial neural network (NN) model based on Google's TensorFlow library. Through comparison with other traditional and non-traditional models, we demonstrated that neural networks are great candidates to capture the complexity and interdependency of various data fields in EHRs. LACE, the current industry standard, showed a precision (PPV) of 0.20 in identifying high-risk patients in our database. In contrast, our NN model yielded a PPV of 0.24, which is a 20% improvement over LACE. Additionally, we discussed the predictive power of Social Determinants of Health (SDoH) data, and presented a simple cost analysis to assist hospitalists in implementing helpful and cost-effective post-discharge interventions.
Predicting all-cause risk of 30-day hospital readmission using artificial neural networks

PubMed Central

2017-01-01

Avoidable hospital readmissions not only contribute to the high costs of healthcare in the US, but also have an impact on the quality of care for patients. Large scale adoption of Electronic Health Records (EHR) has created the opportunity to proactively identify patients with high risk of hospital readmission, and apply effective interventions to mitigate that risk. To that end, in the past, numerous machine-learning models have been employed to predict the risk of 30-day hospital readmission. However, the need for an accurate and real-time predictive model, suitable for hospital setting applications still exists. Here, using data from more than 300,000 hospital stays in California from Sutter Health’s EHR system, we built and tested an artificial neural network (NN) model based on Google’s TensorFlow library. Through comparison with other traditional and non-traditional models, we demonstrated that neural networks are great candidates to capture the complexity and interdependency of various data fields in EHRs. LACE, the current industry standard, showed a precision (PPV) of 0.20 in identifying high-risk patients in our database. In contrast, our NN model yielded a PPV of 0.24, which is a 20% improvement over LACE. Additionally, we discussed the predictive power of Social Determinants of Health (SDoH) data, and presented a simple cost analysis to assist hospitalists in implementing helpful and cost-effective post-discharge interventions. PMID:28708848
Higher threat avoidance costs reduce avoidance behaviour which in turn promotes fear extinction in humans.

PubMed

Rattel, Julina A; Miedl, Stephan F; Blechert, Jens; Wilhelm, Frank H

2017-09-01

Theoretical models specifying the underlying mechanisms of the development and maintenance of anxiety and related disorders state that fear responses acquired through classical Pavlovian conditioning are maintained by repeated avoidance behaviour; thus, it is assumed that avoidance prevents fear extinction. The present study investigated behavioural avoidance decisions as a function of avoidance costs in a naturalistic fear conditioning paradigm. Ecologically valid avoidance costs - manipulated between participant groups - were represented via time-delays during a detour in a gamified computer task. After differential acquisitions of shock-expectancy to a predictive conditioned stimulus (CS+), participants underwent extinction where they could either take a risky shortcut, while anticipating shock signaled by the CS+, or choose a costly avoidance option (lengthy detour); thus, they were faced with an approach-avoidance conflict. Groups with higher avoidance costs (longer detours) showed lower proportions of avoiders. Avoiders gave heightened shock-expectancy ratings post-extinction, demonstrating 'protecting from extinction', i.e. failure to extinguish. Moreover, there was an indirect effect of avoidance costs on protection from extinction through avoidance behaviour. No moderating role of trait-anxiety was found. Theoretical implications of avoidance behaviour are discussed, considering the involvement of instrumental learning in the maintenance of fear responses. Copyright © 2016 Elsevier Ltd. All rights reserved.
Gaze Duration Biases for Colours in Combination with Dissonant and Consonant Sounds: A Comparative Eye-Tracking Study with Orangutans.

PubMed

Mühlenbeck, Cordelia; Liebal, Katja; Pritsch, Carla; Jacobsen, Thomas

2015-01-01

Research on colour preferences in humans and non-human primates suggests similar patterns of biases for and avoidance of specific colours, indicating that these colours are connected to a psychological reaction. Similarly, in the acoustic domain, approach reactions to consonant sounds (considered as positive) and avoidance reactions to dissonant sounds (considered as negative) have been found in human adults and children, and it has been demonstrated that non-human primates are able to discriminate between consonant and dissonant sounds. Yet it remains unclear whether the visual and acoustic approach-avoidance patterns remain consistent when both types of stimuli are combined, how they relate to and influence each other, and whether these are similar for humans and other primates. Therefore, to investigate whether gaze duration biases for colours are similar across primates and whether reactions to consonant and dissonant sounds cumulate with reactions to specific colours, we conducted an eye-tracking study in which we compared humans with one species of great apes, the orangutans. We presented four different colours either in isolation or in combination with consonant and dissonant sounds. We hypothesised that the viewing time for specific colours should be influenced by dissonant sounds and that previously existing avoidance behaviours with regard to colours should be intensified, reflecting their association with negative acoustic information. The results showed that the humans had constant gaze durations which were independent of the auditory stimulus, with a clear avoidance of yellow. In contrast, the orangutans did not show any clear gaze duration bias or avoidance of colours, and they were also not influenced by the auditory stimuli. In conclusion, our findings only partially support the previously identified pattern of biases for and avoidance of specific colours in humans and do not confirm such a pattern for orangutans.
Gaze Duration Biases for Colours in Combination with Dissonant and Consonant Sounds: A Comparative Eye-Tracking Study with Orangutans

PubMed Central

Mühlenbeck, Cordelia; Liebal, Katja; Pritsch, Carla; Jacobsen, Thomas

2015-01-01

Research on colour preferences in humans and non-human primates suggests similar patterns of biases for and avoidance of specific colours, indicating that these colours are connected to a psychological reaction. Similarly, in the acoustic domain, approach reactions to consonant sounds (considered as positive) and avoidance reactions to dissonant sounds (considered as negative) have been found in human adults and children, and it has been demonstrated that non-human primates are able to discriminate between consonant and dissonant sounds. Yet it remains unclear whether the visual and acoustic approach–avoidance patterns remain consistent when both types of stimuli are combined, how they relate to and influence each other, and whether these are similar for humans and other primates. Therefore, to investigate whether gaze duration biases for colours are similar across primates and whether reactions to consonant and dissonant sounds cumulate with reactions to specific colours, we conducted an eye-tracking study in which we compared humans with one species of great apes, the orangutans. We presented four different colours either in isolation or in combination with consonant and dissonant sounds. We hypothesised that the viewing time for specific colours should be influenced by dissonant sounds and that previously existing avoidance behaviours with regard to colours should be intensified, reflecting their association with negative acoustic information. The results showed that the humans had constant gaze durations which were independent of the auditory stimulus, with a clear avoidance of yellow. In contrast, the orangutans did not show any clear gaze duration bias or avoidance of colours, and they were also not influenced by the auditory stimuli. In conclusion, our findings only partially support the previously identified pattern of biases for and avoidance of specific colours in humans and do not confirm such a pattern for orangutans. PMID:26466351
"An integrative formal model of motivation and decision making: The MGPM*": Correction to Ballard et al. (2016).

PubMed

2017-02-01

Reports an error in "An integrative formal model of motivation and decision making: The MGPM*" by Timothy Ballard, Gillian Yeo, Shayne Loft, Jeffrey B. Vancouver and Andrew Neal ( Journal of Applied Psychology , 2016[Sep], Vol 101[9], 1240-1265). Equation A3 contained an error. This correct equation is provided in the erratum. (The following abstract of the original article appeared in record 2016-28692-001.) We develop and test an integrative formal model of motivation and decision making. The model, referred to as the extended multiple-goal pursuit model (MGPM*), is an integration of the multiple-goal pursuit model (Vancouver, Weinhardt, & Schmidt, 2010) and decision field theory (Busemeyer & Townsend, 1993). Simulations of the model generated predictions regarding the effects of goal type (approach vs. avoidance), risk, and time sensitivity on prioritization. We tested these predictions in an experiment in which participants pursued different combinations of approach and avoidance goals under different levels of risk. The empirical results were consistent with the predictions of the MGPM*. Specifically, participants pursuing 1 approach and 1 avoidance goal shifted priority from the approach to the avoidance goal over time. Among participants pursuing 2 approach goals, those with low time sensitivity prioritized the goal with the larger discrepancy, whereas those with high time sensitivity prioritized the goal with the smaller discrepancy. Participants pursuing 2 avoidance goals generally prioritized the goal with the smaller discrepancy. Finally, all of these effects became weaker as the level of risk increased. We used quantitative model comparison to show that the MGPM* explained the data better than the original multiple-goal pursuit model, and that the major extensions from the original model were justified. The MGPM* represents a step forward in the development of a general theory of decision making during multiple-goal pursuit. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Childhood Sexual Abuse, Attachments in Childhood and Adulthood, and Coercive Sexual Behaviors in Community Males.

PubMed

Langton, Calvin M; Murad, Zuwaina; Humbert, Bianca

2017-04-01

Associations between self-reported coercive sexual behavior against adult females, childhood sexual abuse (CSA), and child-parent attachment styles, as well as attachment with adult romantic partners, were examined among 176 adult community males. Attachment style with each parent and with romantic partners was also investigated as a potential moderator. Using hierarchical multiple regression analysis, avoidant attachment with mothers in childhood (and also with fathers, in a second model) accounted for a significant amount of the variance in coercive sexual behavior controlling for scores on anxious ambivalent and disorganized/disoriented attachment scales, as predicted. Similarly, in a third model, avoidance attachment in adulthood was a significant predictor of coercive sexual behavior controlling for scores on the anxiety attachment in adulthood scale. These main effects for avoidant and avoidance attachment were not statistically significant when CSA and control variables (other types of childhood adversity, aggression, antisociality, and response bias) were added in each of the models. But the interaction between scales for CSA and avoidance attachment in adulthood was significant, demonstrating incremental validity in a final step, consistent with a hypothesized moderating function for attachment in adulthood. The correlation between CSA and coercive sexual behavior was .60 for those with the highest third of avoidance attachment scores (i.e., the most insecurely attached on this scale), .24 for those with scores in the middle range on the scale, and .01 for those with the lowest third of avoidance attachment scores (i.e., the most securely attached). Implications for study design and theory were discussed.
Excess of Radiation Burden for Young Testicular Cancer Patients using Automatic Exposure Control and Contrast Agent on Whole-body Computed Tomography Imaging.

PubMed

Niiniviita, Hannele; Kulmala, Jarmo; Pölönen, Tuukka; Määttänen, Heli; Järvinen, Hannu; Salminen, Eeva

2017-06-01

The aim of the study was to assess patient dose from whole-body computed tomography (CT) in association with patient size, automatic exposure control (AEC) and intravenous (IV) contrast agent. Sixty-five testicular cancer patients (mean age 28 years) underwent altogether 279 whole-body CT scans from April 2000 to April 2011. The mean number of repeated examinations was 4.3. The GE LightSpeed 16 equipped with AEC and the Siemens Plus 4 CT scanners were used for imaging. Whole-body scans were performed with (216) and without (63) IV contrast. The ImPACT software was used to determine the effective and organ doses. Patient doses were independent (p < 0.41) of patient size when the Plus 4 device (mean 7.4 mSv, SD 1.7 mSv) was used, but with the LightSpeed 16 AEC device, the dose (mean 14 mSv, SD 4.6 mSv) increased significantly (p < 0.001) with waist cirfumference. Imaging with the IV contrast agent caused significantly higher (13% Plus 4, 35% LightSpeed 16) exposure than non-contrast imaging (p < 0.001). Great caution on the use of IV contrast agent and careful set-up of the AEC modulation parameters is recommended to avoid excessive radiation exposure on the whole-body CT imaging of young patients.
Epidemics in adaptive networks with community structure

NASA Astrophysics Data System (ADS)

Shaw, Leah; Tunc, Ilker

2010-03-01

Models for epidemic spread on static social networks do not account for changes in individuals' social interactions. Recent studies of adaptive networks have modeled avoidance behavior, as non-infected individuals try to avoid contact with infectives. Such models have not generally included realistic social structure. Here we study epidemic spread on an adaptive network with community structure. We model the effect of heterogeneous communities on infection levels and epidemic extinction. We also show how an epidemic can alter the community structure.
Autonomous dynamic obstacle avoidance for bacteria-powered microrobots (BPMs) with modified vector field histogram

PubMed Central

Kim, Hoyeon; Cheang, U. Kei

2017-01-01

In order to broaden the use of microrobots in practical fields, autonomous control algorithms such as obstacle avoidance must be further developed. However, most previous studies of microrobots used manual motion control to navigate past tight spaces and obstacles while very few studies demonstrated the use of autonomous motion. In this paper, we demonstrated a dynamic obstacle avoidance algorithm for bacteria-powered microrobots (BPMs) using electric field in fluidic environments. A BPM consists of an artificial body, which is made of SU-8, and a high dense layer of harnessed bacteria. BPMs can be controlled using externally applied electric fields due to the electrokinetic property of bacteria. For developing dynamic obstacle avoidance for BPMs, a kinematic model of BPMs was utilized to prevent collision and a finite element model was used to characteristic the deformation of an electric field near the obstacle walls. In order to avoid fast moving obstacles, we modified our previously static obstacle avoidance approach using a modified vector field histogram (VFH) method. To validate the advanced algorithm in experiments, magnetically controlled moving obstacles were used to intercept the BPMs as the BPMs move from the initial position to final position. The algorithm was able to successfully guide the BPMs to reach their respective goal positions while avoiding the dynamic obstacles. PMID:29020016
Autonomous dynamic obstacle avoidance for bacteria-powered microrobots (BPMs) with modified vector field histogram.

PubMed

Kim, Hoyeon; Cheang, U Kei; Kim, Min Jun

2017-01-01

In order to broaden the use of microrobots in practical fields, autonomous control algorithms such as obstacle avoidance must be further developed. However, most previous studies of microrobots used manual motion control to navigate past tight spaces and obstacles while very few studies demonstrated the use of autonomous motion. In this paper, we demonstrated a dynamic obstacle avoidance algorithm for bacteria-powered microrobots (BPMs) using electric field in fluidic environments. A BPM consists of an artificial body, which is made of SU-8, and a high dense layer of harnessed bacteria. BPMs can be controlled using externally applied electric fields due to the electrokinetic property of bacteria. For developing dynamic obstacle avoidance for BPMs, a kinematic model of BPMs was utilized to prevent collision and a finite element model was used to characteristic the deformation of an electric field near the obstacle walls. In order to avoid fast moving obstacles, we modified our previously static obstacle avoidance approach using a modified vector field histogram (VFH) method. To validate the advanced algorithm in experiments, magnetically controlled moving obstacles were used to intercept the BPMs as the BPMs move from the initial position to final position. The algorithm was able to successfully guide the BPMs to reach their respective goal positions while avoiding the dynamic obstacles.
[Consumer's psychological processes of hoarding and avoidant purchasing after the Tohoku earthquake].

PubMed

Ohtomo, Shoji; Hirose, Yukio

2014-02-01

This study examined psychological processes of consumers that had determined hoarding and avoidant purchasing behaviors after the Tohoku earthquake within a dual-process model. The model hypothesized that both intentional motivation based on reflective decision and reactive motivation based on non-reflective decision predicted the behaviors. This study assumed that attitude, subjective norm and descriptive norm in relation to hoarding and avoidant purchasing were determinants of motivations. Residents in the Tokyo metropolitan area (n = 667) completed internet longitudinal surveys at three times (April, June, and November, 2011). The results indicated that intentional and reactive motivation determined avoidant purchasing behaviors in June; only intentional motivation determined the behaviors in November. Attitude was a main determinant of the motivations each time. Moreover, previous behaviors predicted future behaviors. In conclusion, purchasing behaviors were intentional rather than reactive behaviors. Furthermore, attitude and previous behaviors were important determinants in the dual-process model. Attitude and behaviors formed in April continued to strengthen the subsequent decisions of purchasing behavior.
Experiential avoidance mediates the link between maternal attachment style and theory of mind.

PubMed

Vanwoerden, Salome; Kalpakci, Allison H; Sharp, Carla

2015-02-01

Theoretical and empirical models suggest a relation between attachment style and theory of mind (ToM) in childhood and adulthood; however, this link has not been evaluated to the same extent in adolescence. Additionally, these models typically fail to consider mechanisms by which attachment style affects ToM abilities. The present study sought to test a mediational model in which experiential avoidance mediates the relation between maternal attachment style and ToM. A sample of 282 adolescents (Mage=15.42years, SD=1.44, 62.8% female) was recruited from an inpatient psychiatric hospital. Findings revealed that maternal attachment style in females was related to ToM, through experiential avoidance. Specifically, those with a disorganized maternal attachment were most likely to engage in experiential avoidant cognitive and emotional strategies, which in turn related to lower levels of ToM ability. Implications and areas for future research are discussed. Copyright © 2014 Elsevier Inc. All rights reserved.
Assessment of the effects of different sample perfusion procedures on phase-contrast tomographic images of mouse spinal cord

NASA Astrophysics Data System (ADS)

Stefanutti, E.; Sierra, A.; Miocchi, P.; Massimi, L.; Brun, F.; Maugeri, L.; Bukreeva, I.; Nurmi, A.; Begani Provinciali, G.; Tromba, G.; Gröhn, O.; Giove, F.; Cedola, A.; Fratini, M.

2018-03-01

Synchrotron X-ray Phase Contrast micro-Tomography (SXrPCμT) is a powerful tool in the investigation of biological tissues, including the central nervous system (CNS), and it allows to simultaneously detect the vascular and neuronal network avoiding contrast agents or destructive sample preparations. However, specific sample preparation procedures aimed to optimize the achievable contrast- and signal-to-noise ratio (CNR and SNR, respectively) are required. Here we report and discuss the effects of perfusion with two different fixative agents (ethanol and paraformaldehyde) and with a widely used contrast medium (MICROFIL®) on mouse spinal cord. As a main result, we found that ethanol enhances contrast at the grey/white matter interface and increases the contrast in correspondence of vascular features and fibres, thus providing an adequate spatial resolution to visualise the vascular network at the microscale. On the other hand, ethanol is known to induce tissue dehydration, likely reducing cell dimensions below the spatial resolution limit imposed by the experimental technique. Nonetheless, neurons remain well visible using either perfused paraformaldehyde or MICROFIL® compound, as these latter media do not affect tissues with dehydration effects. Paraformaldehyde appears as the best compromise: it is not a contrast agent, like MICROFIL®, but it is less invasive than ethanol and permits to visualise well both cells and blood vessels. However, a quantitative estimation of the relative grey matter volume of each sample has led us to conclude that no significant alterations in the grey matter extension compared to the white matter occur as a consequence of the perfusion procedures tested in this study.
Overgeneral autobiographical memory in healthy young and older adults: Differential age effects on components of the capture and rumination, functional avoidance, and impaired executive control (CaRFAX) model.

PubMed

Ros, Laura; Latorre, Jose M; Serrano, Juan P; Ricarte, Jorge J

2017-08-01

The CaRFAX model (Williams et al., 2007) has been used to explain the causes of overgeneral autobiographical memory (OGM; the difficulty to retrieve specific autobiographical memories), a cognitive phenomenon generally related with different psychopathologies. This model proposes 3 different mechanisms to explain OGM: capture and rumination (CaR), functional avoidance (FA) and impaired executive functions (X). However, the complete CaRFAX model has not been tested in nonclinical populations. This study aims to assess the usefulness of the CaRFAX model to explain OGM in 2 healthy samples: a young sample and an older sample, to test for possible age-related differences in the underlying causes of OGM. A total of 175 young (age range: 19-36 years) and 175 older (age range: 53-88 years) participants completed measures of brooding rumination (CaR), functional avoidance (FA), and executive tasks (X). Using structural equation modeling, we found that memory specificity is mainly associated with lower functional avoidance and higher executive functions in the older group, but only with executive functions in young participants. We discuss the different roles of emotional regulation strategies used by young and older people and their relation to the CaRFAX model to explain OGM in healthy people. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
Reference tissue quantification of DCE-MRI data without a contrast agent calibration

NASA Astrophysics Data System (ADS)

Walker-Samuel, Simon; Leach, Martin O.; Collins, David J.

2007-02-01

The quantification of dynamic contrast-enhanced (DCE) MRI data conventionally requires a conversion from signal intensity to contrast agent concentration by measuring a change in the tissue longitudinal relaxation rate, R1. In this paper, it is shown that the use of a spoiled gradient-echo acquisition sequence (optimized so that signal intensity scales linearly with contrast agent concentration) in conjunction with a reference tissue-derived vascular input function (VIF), avoids the need for the conversion to Gd-DTPA concentration. This study evaluates how to optimize such sequences and which dynamic time-series parameters are most suitable for this type of analysis. It is shown that signal difference and relative enhancement provide useful alternatives when full contrast agent quantification cannot be achieved, but that pharmacokinetic parameters derived from both contain sources of error (such as those caused by differences between reference tissue and region of interest proton density and native T1 values). It is shown in a rectal cancer study that these sources of uncertainty are smaller when using signal difference, compared with relative enhancement (15 ± 4% compared with 33 ± 4%). Both of these uncertainties are of the order of those associated with the conversion to Gd-DTPA concentration, according to literature estimates.
Weighting of topologically different interactions in a model of two-dimensional polymer collapse.

PubMed

Bedini, Andrea; Owczarek, Aleksander L; Prellberg, Thomas

2013-01-01

We study by computer simulation a recently introduced generalized model of self-interacting self-avoiding trails on the square lattice that distinguishes two topologically different types of self-interaction: namely, crossings where the trail passes across itself and collisions where the lattice path visits the same site without crossing. This model generalizes the canonical interacting self-avoiding trail model of polymer collapse, which has a strongly divergent specific heat at its transition point. We confirm the recent prediction that the asymmetry does not affect the universality class for a range of asymmetry. Certainly, where the weighting of collisions outweighs that of crossings this is well supported numerically. When crossings are weighted heavily relative to collisions, the collapse transition reverts to the canonical θ-point-like behavior found in interacting self-avoiding walks.
Computational Model of a Positive BDNF Feedback Loop in Hippocampal Neurons Following Inhibitory Avoidance Training

ERIC Educational Resources Information Center

Zhang, Yili; Smolen, Paul; Alberini, Cristina M.; Baxter, Douglas A.; Byrne, John H.

2016-01-01

Inhibitory avoidance (IA) training in rodents initiates a molecular cascade within hippocampal neurons. This cascade contributes to the transition of short- to long-term memory (i.e., consolidation). Here, a differential equation-based model was developed to describe a positive feedback loop within this molecular cascade. The feedback loop begins…
Approach bias for food cues in obese individuals.

PubMed

Kemps, Eva; Tiggemann, Marika

2015-01-01

This study aimed to investigate the existence of an approach bias for food cues in obese individuals. A community sample of 56 obese women and 56 normal weight controls completed an approach-avoidance variant of the implicit association task. The obese participants were faster to respond to trials that paired food words with approach words, and trials that paired non-food words with avoid words, than the converse pairings, thus, demonstrating an approach bias for food. This bias was evident for both high caloric and low caloric food words, and was not attributable to a state of deprivation or feelings of hunger. By contrast, the normal weight controls did not show any such bias. The results are consistent with recent neurocognitive perspectives of obesity. At a practical level, approach biases for food may present a potential target for modifying (excessive) food intake.
Ketamine facilitates extinction of avoidance behavior and enhances synaptic plasticity in a rat model of anxiety vulnerability: Implications for the pathophysiology and treatment of anxiety disorders.

PubMed

Fortress, Ashley M; Smith, Ian M; Pang, Kevin C H

2018-05-08

Anxiety disorders and posttraumatic stress disorder (PTSD) share a common feature of pathological avoidance behavior. The Wistar Kyoto (WKY) rat has been used as a model of anxiety vulnerability, expressing a behaviorally inhibited temperament, acquiring avoidance behavior more rapidly and displaying extinction-resistant avoidance compared to Sprague Dawley (SD) rats. Subanesthetic levels of ketamine have gained attention as a rapid antidepressant in treatment-resistant depression. While traditional antidepressants are commonly used to treat anxiety disorders and PTSD, the therapeutic utility of ketamine for these disorders is much less understood. The hippocampus is critical for the actions of antidepressants, is a structure of implicated in anxiety disorders and PTSD, and is necessary for extinction of avoidance in SD rats. WKY rats have impaired hippocampal long-term potentiation (LTP), suggesting that persistent avoidance in WKY rats may be due to deficient hippocampal synaptic plasticity. In the present study, we hypothesized that ketamine would facilitate extinction of avoidance learning in WKY rats, and do so by enhancing hippocampal synaptic plasticity. As predicted, ketamine facilitated extinction of avoidance behavior in a subset of WKY rats (responders), with effects lasting at least three weeks. Additionally, LTP in these rats was enhanced by ketamine. Ketamine was not effective in facilitating avoidance extinction or in modifying LTP in WKY non-responders. The results suggest that subanesthetic levels of ketamine may be useful for treating anxiety disorders by reducing avoidance behaviors when combined with extinction conditions. Moreover, ketamine may have its long-lasting behavioral effects through enhancing hippocampal synaptic plasticity. Copyright © 2018. Published by Elsevier Ltd.
Particle swarm optimization-based local entropy weighted histogram equalization for infrared image enhancement

NASA Astrophysics Data System (ADS)

Wan, Minjie; Gu, Guohua; Qian, Weixian; Ren, Kan; Chen, Qian; Maldague, Xavier

2018-06-01

Infrared image enhancement plays a significant role in intelligent urban surveillance systems for smart city applications. Unlike existing methods only exaggerating the global contrast, we propose a particle swam optimization-based local entropy weighted histogram equalization which involves the enhancement of both local details and fore-and background contrast. First of all, a novel local entropy weighted histogram depicting the distribution of detail information is calculated based on a modified hyperbolic tangent function. Then, the histogram is divided into two parts via a threshold maximizing the inter-class variance in order to improve the contrasts of foreground and background, respectively. To avoid over-enhancement and noise amplification, double plateau thresholds of the presented histogram are formulated by means of particle swarm optimization algorithm. Lastly, each sub-image is equalized independently according to the constrained sub-local entropy weighted histogram. Comparative experiments implemented on real infrared images prove that our algorithm outperforms other state-of-the-art methods in terms of both visual and quantized evaluations.
The influence of ambient light on the driver

NASA Astrophysics Data System (ADS)

Klinger, Karsten D.; Lemmer, Uli

2008-04-01

Increasingly, cars are fitted with interior ambient lighting which is switched on while driving. This special kind of interior light emphasizes the interior design of the car, it makes a car look special and gives the buyers a new option to personalize their automobiles. But how does ambient interior light influence the driver? We conducted a series of over 50 tests to study the influence of interior ambient light on contrast perception under different illumination levels, colors and positions of the illuminated areas. Our tests show that in many cases the ambient lighting can improve the visual contrast for seeing objects in the headlamp beam. But the test persons mentioned that the tested brightness looked too bright and that they felt glared. The measured values instead proved that no disability glare exists. Therefore, provided that the drivers can adjust the intensity of the ambient light to avoid glare, the ambient light has no negative effect on the drivers' contrast perception.
Modelling anaerobic co-digestion in Benchmark Simulation Model No. 2: Parameter estimation, substrate characterisation and plant-wide integration.

PubMed

Arnell, Magnus; Astals, Sergi; Åmand, Linda; Batstone, Damien J; Jensen, Paul D; Jeppsson, Ulf

2016-07-01

Anaerobic co-digestion is an emerging practice at wastewater treatment plants (WWTPs) to improve the energy balance and integrate waste management. Modelling of co-digestion in a plant-wide WWTP model is a powerful tool to assess the impact of co-substrate selection and dose strategy on digester performance and plant-wide effects. A feasible procedure to characterise and fractionate co-substrates COD for the Benchmark Simulation Model No. 2 (BSM2) was developed. This procedure is also applicable for the Anaerobic Digestion Model No. 1 (ADM1). Long chain fatty acid inhibition was included in the ADM1 model to allow for realistic modelling of lipid rich co-substrates. Sensitivity analysis revealed that, apart from the biodegradable fraction of COD, protein and lipid fractions are the most important fractions for methane production and digester stability, with at least two major failure modes identified through principal component analysis (PCA). The model and procedure were tested on bio-methane potential (BMP) tests on three substrates, each rich on carbohydrates, proteins or lipids with good predictive capability in all three cases. This model was then applied to a plant-wide simulation study which confirmed the positive effects of co-digestion on methane production and total operational cost. Simulations also revealed the importance of limiting the protein load to the anaerobic digester to avoid ammonia inhibition in the digester and overloading of the nitrogen removal processes in the water train. In contrast, the digester can treat relatively high loads of lipid rich substrates without prolonged disturbances. Copyright © 2016 Elsevier Ltd. All rights reserved.
Geoscience in the Big Data Era: Are models obsolete?

NASA Astrophysics Data System (ADS)

Yuen, D. A.; Zheng, L.; Stark, P. B.; Morra, G.; Knepley, M.; Wang, X.

2016-12-01

In last few decades, the velocity, volume, and variety of geophysical data have increased, while the development of the Internet and distributed computing has led to the emergence of "data science." Fitting and running numerical models, especially based on PDEs, is the main consumer of flops in geoscience. Can large amounts of diverse data supplant modeling? Without the ability to conduct randomized, controlled experiments, causal inference requires understanding the physics. It is sometimes possible to predict well without understanding the system—if (1) the system is predictable, (2) data on "important" variables are available, and (3) the system changes slowly enough. And sometimes even a crude model can help the data "speak for themselves" much more clearly. For example, Shearer (1991) used a 1-dimensional velocity model to stack long-period seismograms, revealing upper mantle discontinuities. This was a "big data" approach: the main use of computing was in the data processing, rather than in modeling, yet the "signal" became clear. In contrast, modelers tend to use all available computing power to fit even more complex models, resulting in a cycle where uncertainty quantification (UQ) is never possible: even if realistic UQ required only 1,000 model evaluations, it is never in reach. To make more reliable inferences requires better data analysis and statistics, not more complex models. Geoscientists need to learn new skills and tools: sound software engineering practices; open programming languages suitable for big data; parallel and distributed computing; data visualization; and basic nonparametric, computationally based statistical inference, such as permutation tests. They should work reproducibly, scripting all analyses and avoiding point-and-click tools.
Immediate reactions following iodinated contrast media injection: a study of 38 cases.

PubMed

Dewachter, Pascale; Laroche, Dominique; Mouton-Faivre, Claudie; Bloch-Morot, Evelyne; Cercueil, Jean-Pierre; Metge, Liliane; Carette, Marie-France; Vergnaud, Marie-Claude; Clément, Olivier

2011-03-01

To investigate the pathomechanisms involved in cases of immediate hypersensitivity reactions occurring after the administration of iodinated contrast media. Patients having presented clinical signs of immediate hypersensitivity suggesting allergy after iodinated contrast medium were investigated. Histamine and tryptase concentrations were measured, and/or skin tests were performed. Patients with positive skin tests to the culprit contrast agent were classified as IgE-mediated allergic hypersensitivity (Group I) and patients with negative skin tests as non-allergic hypersensitivity (Group II). 38 patients were included. Most reactions appeared after non-ionic (n = 32). Reactions were more frequently severe following ionic than non-ionic (p = 0.014). Skin testing was not performed in 11 patients. Skin tests with the culprit contrast agent were negative in 26% of the patients (Group II, n = 7) whereas they were found positive with the contrast agent in 73% of the patients (Group I, n = 19). Latex-induced reaction was diagnosed in one patient, and was consequently excluded from the cohort. In Group I, the frequency of cross-reactivity with the other commercialized iodinated contrast media was low (7%). Cardiovascular signs were present in Group I (52.6%, n = 10), and absent in Group II (p = 0.023). Histamine and tryptase concentrations were higher in patients who had cardiovascular signs (p < 0.02). Immediate reactions with clinical signs suggesting allergy along with positive skin tests with the administered contrast agent confirm immediate allergic hypersensitivity (anaphylaxis) to this agent. Consequently, the culprit contrast agent should be definitely avoided as well as cross-reactive ICM in order to prevent further recurrences. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.
Attachment insecurity, biased perceptions of romantic partners' negative emotions, and hostile relationship behavior.

PubMed

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

2015-05-01

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

Heart rate variability moderates the association between attachment avoidance and self-concept reorganization following marital separation.

PubMed

Sbarra, David A; Borelli, Jessica L

2013-06-01

Despite substantial evidence indicating that relationships shape people's self-concept, relatively little is known about how people reorganize their sense of self when relationships end and whether this varies as a function of people's beliefs about relationships. In this report, we examine the prospective association between self-report adult attachment style and self-concept recovery among 89 adults following a recent marital separation. People high in attachment avoidance are characterized by the tendency to deactivate (i.e., suppress) painful attachment-related thoughts and feelings, and, following Fagundes, Diamond, and Allen (2012), we hypothesized that highly avoidant people would show better or worse self-concept outcomes depending on their ability to successfully regulate their emotional experience during a divorce-related mental recall task. We operationalized self-regulation using respiratory sinus arrhythmia (RSA) and found that highly avoidant people who showed RSA increases across our divorce-related mental activation task (DMAT) evidenced improvements in their self-concept over three months. In contrast, highly avoidant adults who showed RSA decreases during the DMAT showed no improvement (or a worsening) in their self-concept disruptions over the subsequent three months. These results suggest that RSA, an index of heart rate variability, may provide a window into self-regulation that has the potential to shed new light on why some people cope well or poorly following the loss of a relationship. Discussion centers on the potential mechanisms of action that explain why some people are able to successfully deactivate attachment-related thoughts and feelings whereas other people are not. Copyright © 2012. Published by Elsevier B.V.
Cannabis intoxication inhibits avoidance action tendencies: a field study in the Amsterdam coffee shops.

PubMed

Cousijn, Janna; Snoek, Robin W M; Wiers, Reinout W

2013-09-01

Experimental laboratory studies suggest that the approach bias (relatively fast approach responses) toward substance-related materials plays an important role in problematic substance use. How this bias is moderated by intention to use versus recent use remains unknown. Moreover, the relationship between approach bias and other motivational processes (satiation and craving) and executive functioning remains unclear. The aim of this study was to investigate the cannabis approach bias before and after cannabis use in real-life setting (Amsterdam coffee shops) and to assess the relationship between approach bias, craving, satiation, cannabis use, and response inhibition. Cannabis, tobacco, and neutral approach and avoidance action tendencies were measured with the Approach Avoidance Task and compared between 42 heavy cannabis users with the intention to use and 45 heavy cannabis users shortly after cannabis use. The classical Stroop was used to measure response inhibition. Multiple regression analyses were conducted to investigate relationships between approach bias, satiation, craving, cannabis use, and response inhibition. In contrast to the hypotheses, heavy cannabis users with the intention to use did not show a cannabis approach bias, whereas intoxicated cannabis users did show an approach bias regardless of image category. This could be attributed to a general slowing of avoidance action tendencies. Moreover, craving was negatively associated with the approach bias, and no relationships were observed between the cannabis approach bias, satiation, prior cannabis use, and response inhibition. Cannabis intoxication in a real-life setting inhibited general avoidance. Expression of the cannabis approach bias appeared not to be modulated by satiation or response inhibition.
Perception of global image contrast involves transparent spatial filtering and the integration and suppression of local contrasts (not RMS contrast)

PubMed Central

2017-01-01

When adjusting the contrast setting on a television set, we experience a perceptual change in the global image contrast. But how is that statistic computed? We addressed this using a contrast-matching task for checkerboard configurations of micro-patterns in which the contrasts and spatial spreads of two interdigitated components were controlled independently. When the patterns differed greatly in contrast, the higher contrast determined the perceived global contrast. Crucially, however, low contrast additions of one pattern to intermediate contrasts of the other caused a paradoxical reduction in the perceived global contrast. None of the following metrics/models predicted this: max, linear sum, average, energy, root mean squared (RMS), Legge and Foley. However, a nonlinear gain control model, derived from contrast detection and discrimination experiments, incorporating wide-field summation and suppression, did predict the results with no free parameters, but only when spatial filtering was removed. We conclude that our model describes fundamental processes in human contrast vision (the pattern of results was the same for expert and naive observers), but that above threshold—when contrast pedestals are clearly visible—vision's spatial filtering characteristics become transparent, tending towards those of a delta function prior to spatial summation. The global contrast statistic from our model is as easily derived as the RMS contrast of an image, and since it more closely relates to human perception, we suggest it be used as an image contrast metric in practical applications. PMID:28989735
Pain-catastrophizing and fear-avoidance beliefs as mediators between post-traumatic stress symptoms and pain following whiplash injury - A prospective cohort study.

PubMed

Andersen, T E; Karstoft, K-I; Brink, O; Elklit, A

2016-09-01

Knowledge about the course of recovery after whiplash injury is important. Most valuable is identification of prognostic factors that may be reversed by intervention. The mutual maintenance model outlines how post-traumatic stress symptoms (PTSS) and pain may be mutually maintained by attention bias, fear, negative affect and avoidance behaviours. In a similar vein, the fear-avoidance model describes how pain-catastrophizing (PCS), fear-avoidance beliefs (FA) and depression may result in persistent pain. These mechanisms still need to be investigated longitudinally in a whiplash cohort. A longitudinal cohort design was used to assess patients for pain intensity and psychological distress after whiplash injury. Consecutive patients were all contacted within 3 weeks after their whiplash injury (n = 198). Follow-up questionnaires were sent 3 and 6 months post-injury. Latent Growth Mixture Modelling was used to identify distinct trajectories of recovery from pain. Five distinct trajectories were identified. Six months post-injury, 64.6% could be classified as recovered and 35.4% as non-recovered. The non-recovered (the medium stable, high stable and very high stable trajectories) displayed significantly higher levels of PTSS, PCS, FA and depression at all time points compared to the recovered trajectories. Importantly, PCS and FA mediated the effect of PTSS on pain intensity. The present study adds important knowledge about the development of psychological distress and pain after whiplash injury. The finding, that PCS and FA mediated the effect of PTSS on pain intensity is a novel finding with important implications for prevention and management of whiplash-associated disorders. WHAT DOES THIS STUDY ADD?: The study confirms the mechanisms as outlined in the fear-avoidance model and the mutual maintenance model. The study adds important knowledge of pain-catastrophizing and fear-avoidance beliefs as mediating mechanisms in the effect of post-traumatic stress on pain intensity. Hence, cognitive behavioural techniques targeting avoidance behaviour and catastrophizing may be beneficial preventing the development of chronic pain. © 2016 European Pain Federation - EFIC®
Comparing Angular and Curved Shapes in Terms of Implicit Associations and Approach/Avoidance Responses.

PubMed

Palumbo, Letizia; Ruta, Nicole; Bertamini, Marco

2015-01-01

Most people prefer smoothly curved shapes over more angular shapes. We investigated the origin of this effect using abstract shapes and implicit measures of semantic association and preference. In Experiment 1 we used a multidimensional Implicit Association Test (IAT) to verify the strength of the association of curved and angular polygons with danger (safe vs. danger words), valence (positive vs. negative words) and gender (female vs. male names). Results showed that curved polygons were associated with safe and positive concepts and with female names, whereas angular polygons were associated with danger and negative concepts and with male names. Experiment 2 used a different implicit measure, which avoided any need to categorise the stimuli. Using a revised version of the Stimulus Response Compatibility (SRC) task we tested with a stick figure (i.e., the manikin) approach and avoidance reactions to curved and angular polygons. We found that RTs for approaching vs. avoiding angular polygons did not differ, even in the condition where the angles were more pronounced. By contrast participants were faster and more accurate when moving the manikin towards curved shapes. Experiment 2 suggests that preference for curvature cannot derive entirely from an association of angles with threat. We conclude that smoothly curved contours make these abstract shapes more pleasant. Further studies are needed to clarify the nature of such a preference.
Comparing Angular and Curved Shapes in Terms of Implicit Associations and Approach/Avoidance Responses

PubMed Central

Palumbo, Letizia; Ruta, Nicole; Bertamini, Marco

2015-01-01

Most people prefer smoothly curved shapes over more angular shapes. We investigated the origin of this effect using abstract shapes and implicit measures of semantic association and preference. In Experiment 1 we used a multidimensional Implicit Association Test (IAT) to verify the strength of the association of curved and angular polygons with danger (safe vs. danger words), valence (positive vs. negative words) and gender (female vs. male names). Results showed that curved polygons were associated with safe and positive concepts and with female names, whereas angular polygons were associated with danger and negative concepts and with male names. Experiment 2 used a different implicit measure, which avoided any need to categorise the stimuli. Using a revised version of the Stimulus Response Compatibility (SRC) task we tested with a stick figure (i.e., the manikin) approach and avoidance reactions to curved and angular polygons. We found that RTs for approaching vs. avoiding angular polygons did not differ, even in the condition where the angles were more pronounced. By contrast participants were faster and more accurate when moving the manikin towards curved shapes. Experiment 2 suggests that preference for curvature cannot derive entirely from an association of angles with threat. We conclude that smoothly curved contours make these abstract shapes more pleasant. Further studies are needed to clarify the nature of such a preference. PMID:26460610
Palatable food avoidance and acceptance learning with different stressors in female rats.

PubMed

Liang, N-C; Smith, M E; Moran, T H

2013-04-03

Stress activates the hypothalamus-pituitary-adrenal (HPA) axis leading to the release of glucocorticoids (GC). Increased activity of the HPA axis and GC exposure has been suggested to facilitate the development of obesity and metabolic syndrome. Nonetheless, different stressors can produce distinct effects on food intake and may support different directions of food learning e.g. avoidance or acceptance. This study examined whether interoceptive (LiCl and exendin-4) and restraint stress (RS) support similar or distinct food learning. Female rats were exposed to different stressors after their consumption of a palatable food (butter icing). After four palatable food-stress pairings, distinct intakes of the butter icing were observed in rats treated with different stressors. Rats that received butter icing followed by intraperitoneal injections of LiCl (42.3mg/kg) and exendin-4 (10μg/kg) completely avoided the palatable food with subsequent presentations. In contrast, rats experiencing RS paired with the palatable food increased their consumption of butter icing across trials and did so to a greater degree than rats receiving saline injections. These data indicate that interoceptive and psychosocial stressors support conditioned food avoidance and acceptance, respectively. Examination of c-Fos immunoreactivity revealed distinct neural activation by interoceptive and psychosocial stressors that could provide the neural basis underlying opposite direction of food acceptance learning. Published by Elsevier Ltd.
Palatable food avoidance and acceptance learning with different stressors in female rats

PubMed Central

Liang, Nu-Chu; Smith, Megan E.; Moran, Timothy H.

2013-01-01

Stress activates the hypothalamus- pituitary-adrenal (HPA) axis leading to the release of glucocorticoids (GC). Increased activity of the HPA axis and GC exposure has been suggested to facilitate the development of obesity and metabolic syndrome. Nonetheless, different stressors can produce distinct effects on food intake and may support different directions of food learning e.g. avoidance or acceptance. This study examined whether interoceptive (LiCl and exendin-4) and restraint stress support similar or distinct food learning. Female rats were exposed to different stressors after their consumption of a palatable food (butter icing). After 4 palatable food-stress pairings, distinct intakes of the butter icing were observed in rats treated with different stressors. Rats that received butter icing followed by intraperitoneal injections of LiCl (42.3 mg/Kg) and exendin-4 (10 μg/Kg) completely avoided the palatable food with subsequent presentations. In contrast, rats experiencing restraint stress paired with the palatable food increased their consumption of butter icing across trials and did so to a greater degree than rats receiving saline injections. These data indicate that interoceptive and psychosocial stressors support conditioned food avoidance and acceptance, respectively. Examination of c-Fos immunoreactivity revealed distinct neural activation by interoceptive and psychosocial stressors that could provide the neural basis underlying opposite direction of food acceptance learning. PMID:23380501
Is desiccation tolerance and avoidance reflected in xylem and phloem anatomy of two co-existing arid-zone coniferous trees?: Xylem and Phloem Anatomy

DOE PAGES

Sevanto, Sanna Annika; Ryan, Max; Turin Dickman, L.; ...

2018-03-22

Plants close their stomata during drought to avoid excessive water loss, but species differ in respect to the drought severity at which stomata close. The stomatal closure point is related to xylem anatomy and vulnerability to embolism, but it also has implications for phloem transport, and possibly phloem anatomy to allow sugar transport at low water potentials. Desiccation tolerant plants that close their stomata at severe drought should have smaller xylem conduits and/or fewer and smaller inter-conduit pits to reduce vulnerability to embolism, but more phloem tissue and larger phloem conduits compared to plants that avoid desiccation. These anatomical differencesmore » could be expected to increase in response to long-term reduction in precipitation. To test these hypotheses we used tridimensional synchroton X-ray microtomograph and light microscope imaging of combined xylem and phloem tissues of two coniferous species: one-seed juniper (Juniperus monosperma) and piñon pine (Pinus edulis) subjected to precipitation manipulation treatments. These species show different xylem vulnerability to embolism, contrasting desiccation tolerance, and stomatal closure points. Our results support the hypothesis that desiccation tolerant plants require higher phloem transport capacity than desiccation avoiding plants, but this can be gained through various anatomical adaptations in addition to changing conduit or tissue size.« less
Drosophila TRPA1 channel is required to avoid the naturally occurring insect repellent citronellal.

PubMed

Kwon, Young; Kim, Sang Hoon; Ronderos, David S; Lee, Youngseok; Akitake, Bradley; Woodward, Owen M; Guggino, William B; Smith, Dean P; Montell, Craig

2010-09-28

Plants produce insect repellents, such as citronellal, which is the main component of citronellal oil. However, the molecular pathways through which insects sense botanical repellents are unknown. Here, we show that Drosophila use two pathways for direct avoidance of citronellal. The olfactory coreceptor OR83b contributes to citronellal repulsion and is essential for citronellal-evoked action potentials. Mutations affecting the Ca(2+)-permeable cation channel TRPA1 result in a comparable defect in avoiding citronellal vapor. The TRPA1-dependent aversion to citronellal relies on a G protein (Gq)/phospholipase C (PLC) signaling cascade rather than direct detection of citronellal by TRPA1. Loss of TRPA1, Gq, or PLC causes an increase in the frequency of citronellal-evoked action potentials in olfactory receptor neurons. Absence of the Ca(2+)-activated K(+) channel (BK channel) Slowpoke results in a similar impairment in citronellal avoidance and an increase in the frequency of action potentials. These results suggest that TRPA1 is required for activation of a BK channel to modulate citronellal-evoked action potentials and for aversion to citronellal. In contrast to Drosophila TRPA1, Anopheles gambiae TRPA1 is directly and potently activated by citronellal, thereby raising the possibility that mosquito TRPA1 may be a target for developing improved repellents to reduce insect-borne diseases such as malaria. Copyright © 2010 Elsevier Ltd. All rights reserved.
Is desiccation tolerance and avoidance reflected in xylem and phloem anatomy of two co-existing arid-zone coniferous trees?: Xylem and Phloem Anatomy

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

Sevanto, Sanna Annika; Ryan, Max; Turin Dickman, L.

Plants close their stomata during drought to avoid excessive water loss, but species differ in respect to the drought severity at which stomata close. The stomatal closure point is related to xylem anatomy and vulnerability to embolism, but it also has implications for phloem transport, and possibly phloem anatomy to allow sugar transport at low water potentials. Desiccation tolerant plants that close their stomata at severe drought should have smaller xylem conduits and/or fewer and smaller inter-conduit pits to reduce vulnerability to embolism, but more phloem tissue and larger phloem conduits compared to plants that avoid desiccation. These anatomical differencesmore » could be expected to increase in response to long-term reduction in precipitation. To test these hypotheses we used tridimensional synchroton X-ray microtomograph and light microscope imaging of combined xylem and phloem tissues of two coniferous species: one-seed juniper (Juniperus monosperma) and piñon pine (Pinus edulis) subjected to precipitation manipulation treatments. These species show different xylem vulnerability to embolism, contrasting desiccation tolerance, and stomatal closure points. Our results support the hypothesis that desiccation tolerant plants require higher phloem transport capacity than desiccation avoiding plants, but this can be gained through various anatomical adaptations in addition to changing conduit or tissue size.« less
Evidence for negative feature guidance in visual search is explained by spatial recoding.

PubMed

Beck, Valerie M; Hollingworth, Andrew

2015-10-01

Theories of attention and visual search explain how attention is guided toward objects with known target features. But can attention be directed away from objects with a feature known to be associated only with distractors? Most studies have found that the demand to maintain the to-be-avoided feature in visual working memory biases attention toward matching objects rather than away from them. In contrast, Arita, Carlisle, and Woodman (2012) claimed that attention can be configured to selectively avoid objects that match a cued distractor color, and they reported evidence that this type of negative cue generates search benefits. However, the colors of the search array items in Arita et al. (2012) were segregated by hemifield (e.g., blue items on the left, red on the right), which allowed for a strategy of translating the feature-cue information into a simple spatial template (e.g., avoid right, or attend left). In the present study, we replicated the negative cue benefit using the Arita et al. (2012), method (albeit within a subset of participants who reliably used the color cues to guide attention). Then, we eliminated the benefit by using search arrays that could not be grouped by hemifield. Our results suggest that feature-guided avoidance is implemented only indirectly, in this case by translating feature-cue information into a spatial template. (c) 2015 APA, all rights reserved).
Carbon source-sink limitations differ between two species with contrasting growth strategies: Source-sink limitations vary with growth strategy

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

Burnett, Angela C.; Rogers, A.; Rees, M.

When we understand how carbon source and sink strengths limit plant growth we realized how critical the knowledge gap is in hindering efforts to maximize crop yield. Here, we investigated how differences in growth rate arise from source–sink limitations, using a model system comparing a fast-growing domesticated annual barley (Hordeum vulgare cv. NFC Tipple) with a slow-growing wild perennial relative (Hordeum bulbosum). Source strength was manipulated by growing plants at sub-ambient and elevated CO 2 concentrations ([CO 2]). Limitations on vegetative growth imposed by source and sink were diagnosed by measuring relative growth rate, developmental plasticity, photosynthesis and major carbonmore » and nitrogen metabolite pools. Growth was sink limited in the annual but source limited in the perennial. RGR and carbon acquisition were higher in the annual, but photosynthesis responded weakly to elevated [CO 2] indicating that source strength was near maximal at current [CO 2]. In contrast, photosynthetic rate and sink development responded strongly to elevated [CO 2] in the perennial, indicating significant source limitation. Sink limitation was avoided in the perennial by high sink plasticity: a marked increase in tillering and root:shoot ratio at elevated [CO 2], and lower non-structural carbohydrate accumulation. Finally, by alleviating sink limitation during vegetative development could be important for maximizing growth of elite cereals under future elevated [CO 2].« less
Carbon source-sink limitations differ between two species with contrasting growth strategies: Source-sink limitations vary with growth strategy

DOE PAGES

Burnett, Angela C.; Rogers, A.; Rees, M.; ...

2016-09-22

When we understand how carbon source and sink strengths limit plant growth we realized how critical the knowledge gap is in hindering efforts to maximize crop yield. Here, we investigated how differences in growth rate arise from source–sink limitations, using a model system comparing a fast-growing domesticated annual barley (Hordeum vulgare cv. NFC Tipple) with a slow-growing wild perennial relative (Hordeum bulbosum). Source strength was manipulated by growing plants at sub-ambient and elevated CO 2 concentrations ([CO 2]). Limitations on vegetative growth imposed by source and sink were diagnosed by measuring relative growth rate, developmental plasticity, photosynthesis and major carbonmore » and nitrogen metabolite pools. Growth was sink limited in the annual but source limited in the perennial. RGR and carbon acquisition were higher in the annual, but photosynthesis responded weakly to elevated [CO 2] indicating that source strength was near maximal at current [CO 2]. In contrast, photosynthetic rate and sink development responded strongly to elevated [CO 2] in the perennial, indicating significant source limitation. Sink limitation was avoided in the perennial by high sink plasticity: a marked increase in tillering and root:shoot ratio at elevated [CO 2], and lower non-structural carbohydrate accumulation. Finally, by alleviating sink limitation during vegetative development could be important for maximizing growth of elite cereals under future elevated [CO 2].« less
Learned helplessness: validity and reliability of depressive-like states in mice.

PubMed

Chourbaji, S; Zacher, C; Sanchis-Segura, C; Dormann, C; Vollmayr, B; Gass, P

2005-12-01

The learned helplessness paradigm is a depression model in which animals are exposed to unpredictable and uncontrollable stress, e.g. electroshocks, and subsequently develop coping deficits for aversive but escapable situations (J.B. Overmier, M.E. Seligman, Effects of inescapable shock upon subsequent escape and avoidance responding, J. Comp. Physiol. Psychol. 63 (1967) 28-33 ). It represents a model with good similarity to the symptoms of depression, construct, and predictive validity in rats. Despite an increased need to investigate emotional, in particular depression-like behaviors in transgenic mice, so far only a few studies have been published using the learned helplessness paradigm. One reason may be the fact that-in contrast to rats (B. Vollmayr, F.A. Henn, Learned helplessness in the rat: improvements in validity and reliability, Brain Res. Brain Res. Protoc. 8 (2001) 1-7)--there is no generally accepted learned helplessness protocol available for mice. This prompted us to develop a reliable helplessness procedure in C57BL/6N mice, to exclude possible artifacts, and to establish a protocol, which yields a consistent fraction of helpless mice following the shock exposure. Furthermore, we validated this protocol pharmacologically using the tricyclic antidepressant imipramine. Here, we present a mouse model with good face and predictive validity that can be used for transgenic, behavioral, and pharmacological studies.
High-performance C-arm cone-beam CT guidance of thoracic surgery

NASA Astrophysics Data System (ADS)

Schafer, Sebastian; Otake, Yoshito; Uneri, Ali; Mirota, Daniel J.; Nithiananthan, Sajendra; Stayman, J. W.; Zbijewski, Wojciech; Kleinszig, Gerhard; Graumann, Rainer; Sussman, Marc; Siewerdsen, Jeffrey H.

2012-02-01

Localizing sub-palpable nodules in minimally invasive video-assisted thoracic surgery (VATS) presents a significant challenge. To overcome inherent problems of preoperative nodule tagging using CT fluoroscopic guidance, an intraoperative C-arm cone-beam CT (CBCT) image-guidance system has been developed for direct localization of subpalpable tumors in the OR, including real-time tracking of surgical tools (including thoracoscope), and video-CBCT registration for augmentation of the thoracoscopic scene. Acquisition protocols for nodule visibility in the inflated and deflated lung were delineated in phantom and animal/cadaver studies. Motion compensated reconstruction was implemented to account for motion induced by the ventilated contralateral lung. Experience in CBCT-guided targeting of simulated lung nodules included phantoms, porcine models, and cadavers. Phantom studies defined low-dose acquisition protocols providing contrast-to-noise ratio sufficient for lung nodule visualization, confirmed in porcine specimens with simulated nodules (3-6mm diameter PE spheres, ~100-150HU contrast, 2.1mGy). Nodule visibility in CBCT of the collapsed lung, with reduced contrast according to air volume retention, was more challenging, but initial studies confirmed visibility using scan protocols at slightly increased dose (~4.6-11.1mGy). Motion compensated reconstruction employing a 4D deformation map in the backprojection process reduced artifacts associated with motion blur. Augmentation of thoracoscopic video with renderings of the target and critical structures (e.g., pulmonary artery) showed geometric accuracy consistent with camera calibration and the tracking system (2.4mm registration error). Initial results suggest a potentially valuable role for CBCT guidance in VATS, improving precision in minimally invasive, lungconserving surgeries, avoid critical structures, obviate the burdens of preoperative localization, and improve patient safety.
Generating Enhanced Natural Environments and Terrain for Interactive Combat Simulations (GENETICS)

DTIC Science & Technology

2005-09-01

split to avoid T-junctions ........................................................................52 Figure 2-23 Longest edge bisection...database. This feature allows trainers the flexibility to use the same terrain repeatedly or use a new one each time, forcing trainees to avoid ...model are favored to create a good surface approximation. Cracks are avoided by projecting primitives and their respective textures onto multiple
Subjective health complaints, functional ability, fear avoidance beliefs, and days on sickness benefits after work rehabilitation - a mediation model.

PubMed

Øyeflaten, Irene; Opsahl, Jon; Eriksen, Hege R; Braathen, Tore Norendal; Lie, Stein Atle; Brage, Søren; Ihlebæk, Camilla M; Breivik, Kyrre

2016-05-23

Long-term sick leave and withdrawal from working life is a concern in western countries. In Norway, comprehensive inpatient work rehabilitation may be offered to sick listed individuals at risk of long-term absence from work. Knowledge about prognostic factors for work outcomes after long-term sick leave and work rehabilitation is still limited. The aim of this study was to test a mediation model for various hypothesized biopsychosocial predictors of continued sick leave after inpatient work rehabilitation. One thousand one hundred fifty-five participants on long-term sick leave from eight different work rehabilitation clinics answered comprehensive questionnaires at arrival to the clinic, and were followed with official register data on sickness benefits for 3 years. Structural equation models were conducted, with days on sickness benefits after work rehabilitation as the outcome. Fear avoidance beliefs for work mediated the relation between both musculoskeletal complaints and education on days on sickness benefits after work rehabilitation. The relation between musculoskeletal complaints and fear avoidance beliefs for work was furthermore fully mediated by poor physical function. Previous sick leave had a strong independent effect on continued sick leave after work rehabilitation. Fear avoidance beliefs for work did not mediate the small effect of pseudoneurological complaints on continued sick leave. Poor coping/interaction ability was neither related to continued sick leave nor fear avoidance beliefs for work. The mediation model was partly supported by the data, and provides some possible new insight into how fear avoidance beliefs for work and functional ability may intervene with subjective health complaints and days on sickness benefits after work rehabilitation.
Strategies for Pre-Emptive Mid-Air Collision Avoidance in Budgerigars

PubMed Central

Schiffner, Ingo; Srinivasan, Mandyam V.

2016-01-01

We have investigated how birds avoid mid-air collisions during head-on encounters. Trajectories of birds flying towards each other in a tunnel were recorded using high speed video cameras. Analysis and modelling of the data suggest two simple strategies for collision avoidance: (a) each bird veers to its right and (b) each bird changes its altitude relative to the other bird according to a preset preference. Both strategies suggest simple rules by which collisions can be avoided in head-on encounters by two agents, be they animals or machines. The findings are potentially applicable to the design of guidance algorithms for automated collision avoidance on aircraft. PMID:27680488
Neural Mechanisms of Grief Regulation

PubMed Central

Freed, Peter J.; Yanagihara, Ted K.; Hirsch, Joy; Mann, J. John

2009-01-01

Background: The death of an attachment figure triggers intrusive thoughts of the deceased, sadness, and yearning for reunion. Recovery requires reduction of symptoms. We hypothesized that symptoms might correlate with a capacity to regulate attention toward reminders of the deceased, and activity in, and functional connectivity between, prefrontal regulatory regions and the amygdala. Methods: Twenty recently bereaved subjects rated intrusive thoughts of the deceased versus a capacity to avoid thoughts (grief style). Reaction time was measured while subjects completed an Emotional Stroop (ES) task contrasting deceased-related with control words during functional magnetic resonance imaging (fMRI). Subjects subsequently visualized the death of the deceased and rated induced emotions. Results: Subjects demonstrated attentional bias toward deceased-related words. Bias magnitude correlated with amygdala, insula, dorsolateral prefrontal cortex (DLPFC) activity. Amygdala activity predicted induced sadness intensity. A double dissociation between grief style and both prefrontal and amygdala subregion activity was found. Intrusiveness correlated with activation of ventral amygdala and rostral anterior cingulate (rACC); avoidance correlated with deactivation of dorsal amygdala and DLPFC. A double dissociation between regulatory region and task-dependent functional connectivity (FC) was found. High DLPFC-amygdala FC correlated with reduced attentional bias, while low rACC-amygdala FC predicted sadness intensity. Conclusions: Results are consistent with a model in which activity in and functional connectivity between the amygdala and prefrontal regulatory regions indexes differences in mourners' regulation of attention and sadness during pangs of grief, and may be used to distinguish between clinically relevant differences in grief style. PMID:19249748

Water avoidance stress induces frequency through cyclooxygenase-2 expression: a bladder rat model.

PubMed

Yamamoto, Keisuke; Takao, Tetsuya; Nakayama, Jiro; Kiuchi, Hiroshi; Okuda, Hidenobu; Fukuhara, Shinichiro; Yoshioka, Iwao; Matsuoka, Yasuhiro; Miyagawa, Yasushi; Tsujimura, Akira; Nonomura, Norio

2012-02-01

Water avoidance stress is a potent psychological stressor and it is associated with visceral hyperalgesia, which shows degeneration of the urothelial layer mimicking interstitial cystitis. Cyclooxygenase-2 inhibitors have been recognized to ameliorate frequency both in clinical and experimental settings. We investigated the voiding pattern and cyclooxygenase-2 expression in a rat bladder model of water avoidance stress. After being subjected to water avoidance stress or a sham procedure, rats underwent metabolic cage analysis and cystometrography. Real time reverse transcription polymerase chain reaction was carried out to examine cyclooxygenase-2 messenger ribonucleic acid in bladders of rats. Protein expression of cyclooxygenase-2 was analyzed with immunohistochemistry and western blotting. Furthermore, the effects of the cyclooxygenase-2 inhibitor, etodolac, were investigated by carrying out cystometrography, immunohistochemistry and western blotting. Metabolic cage analysis and cystometrography showed significantly shorter intervals and less volume of voiding in water avoidance stress rats. Significantly higher expression of cyclooxygenase-2 messenger ribonucleic acid was verified by reverse transcription polymerase chain reaction. Immunohistochemistry and western blotting showed significantly higher cyclooxygenase-2 protein levels in water avoidance stress bladders. Furthermore, immunohistochemistry showed high cyclooxygenase-2 expression exclusively in smooth muscle cells. All water avoidance stress-induced changes were reduced by cyclooxygenase-2 inhibitor pretreatment. Chronic stress might cause frequency through cyclooxygenase-2 gene upregulation in bladder smooth muscle cells. Further study of cyclooxygenase-2 in the water avoidance stress bladder might provide novel therapeutic modalities for interstitial cystitis. © 2011 The Japanese Urological Association.
Low back pain patients' responses to videos of avoided movements.

PubMed

Pincus, T; Henderson, J

2013-02-01

Fear avoidance (FA) has been identified as a risk factor for poor prognosis and a target for intervention in patients with low back pain (LBP), but the mechanisms involved need clarification. Experimental studies would benefit from the use of carefully developed and controlled stimuli representing avoided movements in back pain, and matched stimuli of movements to provide a credible control stimuli. Existing stimuli depicting avoided movements in LBP are static, do not include a set of control stimuli and do not control for possible systematic observer biases. Two studies were carried out aiming to develop and test LBP patients' responses to videos of models depicting commonly avoided movements associated with back pain, and those associated with a control condition, wrist pain. Two samples of LBP patients rated how much pain and harm each movement would cause them. They also reported how often they avoided the movement. The findings from the first study (n = 99) indicate that using videos of commonly avoided movements in low back pain is viable, and that movements associated with wrist pain provide an acceptable control stimuli. Participants in the second study (n = 85) consistently rated movements depicted by females as causing more harm, and more frequently avoided than the same movements depicted by males. The use of video stimuli could advance research into the processes associated with FA through experimental paradigms. However, although small, the model gender effects should be carefully considered. © 2012 European Federation of International Association for the Study of Pain Chapters.
Measuring situational avoidance in older drivers: An application of Rasch analysis.

PubMed

Davis, Jessica; Conlon, Elizabeth; Ownsworth, Tamara; Morrissey, Shirley

2016-02-01

Situational avoidance is a form of driving self-regulation at the strategic level of driving behaviour. It has typically been defined as the purposeful avoidance of driving situations perceived as challenging or potentially hazardous. To date, assessment of the psychometric properties of existing scales that measure situational avoidance has been sparse. This study examined the contribution of Rasch analysis to the situational avoidance construct. Three hundred and ninety-nine Australian drivers (M=66.75, SD=10.14, range: 48-91 years) completed the Situational Avoidance Questionnaire (SAQ). Following removal of the item Parallel Parking, the scale conformed to a Rasch model, showing good person separation, sufficient reliability, little disordering of thresholds, and no evidence of differential item functioning by age or gender. The residuals were independent supporting the assumption of unidimensionality and in conforming to a Rasch model, SAQ items were found to be hierarchical or cumulative. Increased avoidance was associated with factors known to be related to driving self-regulation more broadly, including older age, female gender, reduced driving space and frequency, reporting a change in driving in the past five years and poorer indices of health (i.e., self-rated mood, vision and cognitive function). Overall, these results support the use of the SAQ as a psychometrically sound measure of situational avoidance. Application of Rasch analysis to this area of research advances understanding of the driving self-regulation construct and its practice by drivers in baby boomer and older adult generations. Copyright © 2015 Elsevier Ltd. All rights reserved.
Reconstruction of 2D PET data with Monte Carlo generated system matrix for generalized natural pixels

NASA Astrophysics Data System (ADS)

Vandenberghe, Stefaan; Staelens, Steven; Byrne, Charles L.; Soares, Edward J.; Lemahieu, Ignace; Glick, Stephen J.

2006-06-01

In discrete detector PET, natural pixels are image basis functions calculated from the response of detector pairs. By using reconstruction with natural pixel basis functions, the discretization of the object into a predefined grid can be avoided. Here, we propose to use generalized natural pixel reconstruction. Using this approach, the basis functions are not the detector sensitivity functions as in the natural pixel case but uniform parallel strips. The backprojection of the strip coefficients results in the reconstructed image. This paper proposes an easy and efficient way to generate the matrix M directly by Monte Carlo simulation. Elements of the generalized natural pixel system matrix are formed by calculating the intersection of a parallel strip with the detector sensitivity function. These generalized natural pixels are easier to use than conventional natural pixels because the final step from solution to a square pixel representation is done by simple backprojection. Due to rotational symmetry in the PET scanner, the matrix M is block circulant and only the first blockrow needs to be stored. Data were generated using a fast Monte Carlo simulator using ray tracing. The proposed method was compared to a listmode MLEM algorithm, which used ray tracing for doing forward and backprojection. Comparison of the algorithms with different phantoms showed that an improved resolution can be obtained using generalized natural pixel reconstruction with accurate system modelling. In addition, it was noted that for the same resolution a lower noise level is present in this reconstruction. A numerical observer study showed the proposed method exhibited increased performance as compared to a standard listmode EM algorithm. In another study, more realistic data were generated using the GATE Monte Carlo simulator. For these data, a more uniform contrast recovery and a better contrast-to-noise performance were observed. It was observed that major improvements in contrast recovery were obtained with MLEM when the correct system matrix was used instead of simple ray tracing. The correct modelling was the major cause of improved contrast for the same background noise. Less important factors were the choice of the algorithm (MLEM performed better than ART) and the basis functions (generalized natural pixels gave better results than pixels).
A meta-analysis of fear-avoidance and pain intensity: The paradox of chronic pain.

PubMed

Kroska, Emily B

2016-10-01

The fear-avoidance model of chronic pain has established avoidance as a predictor of negative outcomes in chronic pain patients. Avoidance, or deliberate attempts to suppress or prevent unwanted experiences (e.g., pain), has been studied extensively, with multiple reviews implicating this behavior as a predictor of disability, physical disuse, and depression. Despite hundreds of studies examining the associations between different components of this model (i.e., catastrophizing, fear, avoidance, depression), the association between fear-avoidance and pain intensity has remained unclear. The present study seeks to clarify this association across samples. The present analyses synthesize the literature (articles from PsycInfo, PubMed, and ProQuest) to determine if fear-avoidance and pain intensity are consistently correlated across studies, samples, and measures. Eligible studies measured pain intensity and fear-avoidance cross-sectionally in chronic pain patients. The search resulted in 118 studies eligible for inclusion. A random-effects model was used to estimate the weighted mean effect size. Comprehensive Meta-Analysis software was used for all analyses. Moderation analyses elucidate the variables that affect the strength of this association. Meta-regression and meta-ANOVA analyses were conducted to examine moderating variables. Moderator variables include demographic characteristics, pain characteristics, study characteristics, and national cultural characteristics (using Hofstede's cultural dimensions). Publication bias was examined using the funnel plot and the p-curve. Results indicate a small-to-moderate positive association between fear-avoidance and pain intensity. The results were stable across characteristics of the sample, including mean age, gender distribution, marital status, and duration of pain. Moderation analyses indicate that the measures utilized and cultural differences affect the strength of this association. Weaker effect sizes were observed for studies that utilized measures of experiential avoidance when compared to studies that utilized pain-specific fear-avoidance measures. Studies that utilized multiple measures of fear-avoidance had stronger effect sizes than studies that utilized a single measure of fear-avoidance. Three of Hofstede's cultural dimensions moderated the association, including Power Distance Index, Individualism versus Collectivism, and Indulgence versus Restraint. The present meta-analysis synthesizes the results from studies examining the association between fear-avoidance and pain intensity among individuals with chronic pain. The positive association indicates that those with increased fear-avoidance have higher pain intensity, and those with higher pain intensity have increased fear-avoidance. Findings indicate that cultural differences and measurement instruments are important to consider in understanding the variables that affect this association. The significant cultural variations may indicate that it is important to consider the function of avoidance behavior in different cultures in an effort to better understand each patient's cultural beliefs, as well as how these beliefs are related to pain and associated coping strategies. The results from the current meta-analysis can be used to inform interventions for patients with chronic pain. In particular, those with more intense pain or increased fear-avoidance should be targeted for prevention and intervention work. Within the intervention itself, avoidance should be undermined and established as an ineffective strategy to manage pain in an effort to prevent disability, depression, and physical deconditioning. Copyright Â© 2016 Scandinavian Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.
Predicting the ethanol potential of wheat straw using near-infrared spectroscopy and chemometrics: The challenge of inherently intercorrelated response functions

DOE PAGES

Rinnan, Asmund; Bruun, Sander; Lindedam, Jane; ...

2017-02-07

Here, the combination of NIR spectroscopy and chemometrics is a powerful correlation method for predicting the chemical constituents in biological matrices, such as the glucose and xylose content of straw. However, difficulties arise when it comes to predicting enzymatic glucose and xylose release potential, which is matrix dependent. Further complications are caused by xylose and glucose release potential being highly intercorrelated. This study emphasizes the importance of understanding the causal relationship between the model and the constituent of interest. It investigates the possibility of using near-infrared spectroscopy to evaluate the ethanol potential of wheat straw by analyzing more than 1000more » samples from different wheat varieties and growth conditions. During the calibration model development, the prime emphasis was to investigate the correlation structure between the two major quality traits for saccharification of wheat straw: glucose and xylose release. The large sample set enabled a versatile and robust calibration model to be developed, showing that the prediction model for xylose release is based on a causal relationship with the NIR spectral data. In contrast, the prediction of glucose release was found to be highly dependent on the intercorrelation with xylose release. If this correlation is broken, the model performance breaks down. A simple method was devised for avoiding this breakdown and can be applied to any large dataset for investigating the causality or lack of causality of a prediction model.« less
Predicting the ethanol potential of wheat straw using near-infrared spectroscopy and chemometrics: The challenge of inherently intercorrelated response functions

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

Rinnan, Asmund; Bruun, Sander; Lindedam, Jane

Here, the combination of NIR spectroscopy and chemometrics is a powerful correlation method for predicting the chemical constituents in biological matrices, such as the glucose and xylose content of straw. However, difficulties arise when it comes to predicting enzymatic glucose and xylose release potential, which is matrix dependent. Further complications are caused by xylose and glucose release potential being highly intercorrelated. This study emphasizes the importance of understanding the causal relationship between the model and the constituent of interest. It investigates the possibility of using near-infrared spectroscopy to evaluate the ethanol potential of wheat straw by analyzing more than 1000more » samples from different wheat varieties and growth conditions. During the calibration model development, the prime emphasis was to investigate the correlation structure between the two major quality traits for saccharification of wheat straw: glucose and xylose release. The large sample set enabled a versatile and robust calibration model to be developed, showing that the prediction model for xylose release is based on a causal relationship with the NIR spectral data. In contrast, the prediction of glucose release was found to be highly dependent on the intercorrelation with xylose release. If this correlation is broken, the model performance breaks down. A simple method was devised for avoiding this breakdown and can be applied to any large dataset for investigating the causality or lack of causality of a prediction model.« less
Chloride and salicylate influence prestin-dependent specific membrane capacitance: support for the area motor model.

PubMed

Santos-Sacchi, Joseph; Song, Lei

2014-04-11

The outer hair cell is electromotile, its membrane motor identified as the protein SLC26a5 (prestin). An area motor model, based on two-state Boltzmann statistics, was developed about two decades ago and derives from the observation that outer hair cell surface area is voltage-dependent. Indeed, aside from the nonlinear capacitance imparted by the voltage sensor charge movement of prestin, linear capacitance (Clin) also displays voltage dependence as motors move between expanded and compact states. Naturally, motor surface area changes alter membrane capacitance. Unit linear motor capacitance fluctuation (δCsa) is on the order of 140 zeptofarads. A recent three-state model of prestin provides an alternative view, suggesting that voltage-dependent linear capacitance changes are not real but only apparent because the two component Boltzmann functions shift their midpoint voltages (Vh) in opposite directions during treatment with salicylate, a known competitor of required chloride binding. We show here using manipulations of nonlinear capacitance with both salicylate and chloride that an enhanced area motor model, including augmented δCsa by salicylate, can accurately account for our novel findings. We also show that although the three-state model implicitly avoids measuring voltage-dependent motor capacitance, it registers δCsa effects as a byproduct of its assessment of Clin, which increases during salicylate treatment as motors are locked in the expanded state. The area motor model, in contrast, captures the characteristics of the voltage dependence of δCsa, leading to a better understanding of prestin.
Model-based analysis of avoidance of ozone stress by stomatal closure in Siebold's beech (Fagus crenata)

PubMed Central

Hoshika, Yasutomo; Watanabe, Makoto; Inada, Naoki; Koike, Takayoshi

2013-01-01

Background and Aims Resistance of plants to ozone stress can be classified as either avoidance or tolerance. Avoidance of ozone stress may be explained by decreased stomatal conductance during ozone exposure because stomata are the principal interface for entry of ozone into plants. In this study, a coupled photosynthesis–stomatal model was modified to test whether the presence of ozone can induce avoidance of ozone stress by stomatal closure. Methods The response of Siebold's beech (Fagus crenata), a representative deciduous tree species, to ozone was studied in a free-air ozone exposure experiment in Japan. Photosynthesis and stomatal conductance were measured under ambient and elevated ozone. An optimization model of stomata involving water, CO2 and ozone flux was tested using the leaf gas exchange data. Key Results The data suggest that there are two phases in the avoidance of ozone stress via stomatal closure for Siebold's beech: (1) in early summer ozone influx is efficiently limited by a reduction in stomatal conductance, without any clear effect on photosynthetic capacity; and (2) in late summer and autumn the efficiency of ozone stress avoidance was decreased because the decrease in stomatal conductance was small and accompanied by an ozone-induced decline of photosynthetic capacity. Conclusions Ozone-induced stomatal closure in Siebold's beech during early summer reduces ozone influx and allows the maximum photosynthetic capacity to be reached, but is not sufficient in older leaves to protect the photosynthetic system. PMID:23904447
Limitations of contrast enhancement for infrared target identification

NASA Astrophysics Data System (ADS)

Du Bosq, Todd W.; Fanning, Jonathan D.

2009-05-01

Contrast enhancement and dynamic range compression are currently being used to improve the performance of infrared imagers by increasing the contrast between the target and the scene content. Automatic contrast enhancement techniques do not always achieve this improvement. In some cases, the contrast can increase to a level of target saturation. This paper assesses the range-performance effects of contrast enhancement for target identification as a function of image saturation. Human perception experiments were performed to determine field performance using contrast enhancement on the U.S. Army RDECOM CERDEC NVESD standard military eight target set using an un-cooled LWIR camera. The experiments compare the identification performance of observers viewing contrast enhancement processed images at various levels of saturation. Contrast enhancement is modeled in the U.S. Army thermal target acquisition model (NVThermIP) by changing the scene contrast temperature. The model predicts improved performance based on any improved target contrast, regardless of specific feature saturation or enhancement. The measured results follow the predicted performance based on the target task difficulty metric used in NVThermIP for the non-saturated cases. The saturated images reduce the information contained in the target and performance suffers. The model treats the contrast of the target as uniform over spatial frequency. As the contrast is enhanced, the model assumes that the contrast is enhanced uniformly over the spatial frequencies. After saturation, the spatial cues that differentiate one tank from another are located in a limited band of spatial frequencies. A frequency dependent treatment of target contrast is needed to predict performance of over-processed images.
GNSS/Electronic Compass/Road Segment Information Fusion for Vehicle-to-Vehicle Collision Avoidance Application

PubMed Central

Cheng, Qi; Xue, Dabin; Wang, Guanyu; Ochieng, Washington Yotto

2017-01-01

The increasing number of vehicles in modern cities brings the problem of increasing crashes. One of the applications or services of Intelligent Transportation Systems (ITS) conceived to improve safety and reduce congestion is collision avoidance. This safety critical application requires sub-meter level vehicle state estimation accuracy with very high integrity, continuity and availability, to detect an impending collision and issue a warning or intervene in the case that the warning is not heeded. Because of the challenging city environment, to date there is no approved method capable of delivering this high level of performance in vehicle state estimation. In particular, the current Global Navigation Satellite System (GNSS) based collision avoidance systems have the major limitation that the real-time accuracy of dynamic state estimation deteriorates during abrupt acceleration and deceleration situations, compromising the integrity of collision avoidance. Therefore, to provide the Required Navigation Performance (RNP) for collision avoidance, this paper proposes a novel Particle Filter (PF) based model for the integration or fusion of real-time kinematic (RTK) GNSS position solutions with electronic compass and road segment data used in conjunction with an Autoregressive (AR) motion model. The real-time vehicle state estimates are used together with distance based collision avoidance algorithms to predict potential collisions. The algorithms are tested by simulation and in the field representing a low density urban environment. The results show that the proposed algorithm meets the horizontal positioning accuracy requirement for collision avoidance and is superior to positioning accuracy of GNSS only, traditional Constant Velocity (CV) and Constant Acceleration (CA) based motion models, with a significant improvement in the prediction accuracy of potential collision. PMID:29186851
GNSS/Electronic Compass/Road Segment Information Fusion for Vehicle-to-Vehicle Collision Avoidance Application.

PubMed

Sun, Rui; Cheng, Qi; Xue, Dabin; Wang, Guanyu; Ochieng, Washington Yotto

2017-11-25

The increasing number of vehicles in modern cities brings the problem of increasing crashes. One of the applications or services of Intelligent Transportation Systems (ITS) conceived to improve safety and reduce congestion is collision avoidance. This safety critical application requires sub-meter level vehicle state estimation accuracy with very high integrity, continuity and availability, to detect an impending collision and issue a warning or intervene in the case that the warning is not heeded. Because of the challenging city environment, to date there is no approved method capable of delivering this high level of performance in vehicle state estimation. In particular, the current Global Navigation Satellite System (GNSS) based collision avoidance systems have the major limitation that the real-time accuracy of dynamic state estimation deteriorates during abrupt acceleration and deceleration situations, compromising the integrity of collision avoidance. Therefore, to provide the Required Navigation Performance (RNP) for collision avoidance, this paper proposes a novel Particle Filter (PF) based model for the integration or fusion of real-time kinematic (RTK) GNSS position solutions with electronic compass and road segment data used in conjunction with an Autoregressive (AR) motion model. The real-time vehicle state estimates are used together with distance based collision avoidance algorithms to predict potential collisions. The algorithms are tested by simulation and in the field representing a low density urban environment. The results show that the proposed algorithm meets the horizontal positioning accuracy requirement for collision avoidance and is superior to positioning accuracy of GNSS only, traditional Constant Velocity (CV) and Constant Acceleration (CA) based motion models, with a significant improvement in the prediction accuracy of potential collision.
Motion-based signaling in sympatric species of Australian agamid lizards.

PubMed

Ramos, Jose A; Peters, Richard A

2017-08-01

Signaling species occurring in sympatry are often exposed to similar environmental constraints, so similar adaptations to enhance signal efficacy are expected. However, potentially opposing selective pressures might be present to ensure species recognition. Here, we analyzed the movement-based signals of two pairs of sympatric lizard species to consider how reliable communication is maintained while avoiding misidentification. Our novel approach allows us to quantify signal contrast with plant motion noise at any site we measure, including those utilized by other species. Ctenophorus caudicinctus and Gowidon longirostris differed in display complexity and motor pattern use. They also differed in overall morphology, but their signal contrast scores are strikingly similar. These results demonstrate similar adaptations to their shared environment while maintaining species recognition cues. In contrast, Ctenophorus fordi and Ctenophorus pictus are much closer in appearance, but C. pictus produces considerably higher signal contrast scores, which we suggest is attributable to the absence of territoriality in C. fordi. Taken together, our data provide evidence for adaptation to the local environment in movement-based signals, while also meeting species recognition requirements, but the selective pressure to deal with local conditions is mediated by signal function.
Noncontrast-enhanced renal angiography using multiple inversion recovery and alternating TR balanced steady-state free precession.

PubMed

Dong, Hattie Z; Worters, Pauline W; Wu, Holden H; Ingle, R Reeve; Vasanawala, Shreyas S; Nishimura, Dwight G

2013-08-01

Noncontrast-enhanced renal angiography techniques based on balanced steady-state free precession avoid external contrast agents, take advantage of high inherent blood signal from the T 2 / T 1 contrast mechanism, and have short steady-state free precession acquisition times. However, background suppression is limited; inflow times are inflexible; labeling region is difficult to define when tagging arterial flow; and scan times are long. To overcome these limitations, we propose the use of multiple inversion recovery preparatory pulses combined with alternating pulse repetition time balanced steady-state free precession to produce renal angiograms. Multiple inversion recovery uses selective spatial saturation followed by four nonselective inversion recovery pulses to concurrently null a wide range of background T 1 species while allowing for adjustable inflow times; alternating pulse repetition time steady-state free precession maintains vessel contrast and provides added fat suppression. The high level of suppression enables imaging in three-dimensional as well as projective two-dimensional formats, the latter of which has a scan time as short as one heartbeat. In vivo studies at 1.5 T demonstrate the superior vessel contrast of this technique. © 2012 Wiley Periodicals, Inc.
In the absence of a "landscape of fear": How lions, hyenas, and cheetahs coexist.

PubMed

Swanson, Alexandra; Arnold, Todd; Kosmala, Margaret; Forester, James; Packer, Craig

2016-12-01

Aggression by top predators can create a "landscape of fear" in which subordinate predators restrict their activity to low-risk areas or times of day. At large spatial or temporal scales, this can result in the costly loss of access to resources. However, fine-scale reactive avoidance may minimize the risk of aggressive encounters for subordinate predators while maintaining access to resources, thereby providing a mechanism for coexistence. We investigated fine-scale spatiotemporal avoidance in a guild of African predators characterized by intense interference competition. Vulnerable to food stealing and direct killing, cheetahs are expected to avoid both larger predators; hyenas are expected to avoid lions. We deployed a grid of 225 camera traps across 1,125 km 2 in Serengeti National Park, Tanzania, to evaluate concurrent patterns of habitat use by lions, hyenas, cheetahs, and their primary prey. We used hurdle models to evaluate whether smaller species avoided areas preferred by larger species, and we used time-to-event models to evaluate fine-scale temporal avoidance in the hours immediately surrounding top predator activity. We found no evidence of long-term displacement of subordinate species, even at fine spatial scales. Instead, hyenas and cheetahs were positively associated with lions except in areas with exceptionally high lion use. Hyenas and lions appeared to actively track each, while cheetahs appear to maintain long-term access to sites with high lion use by actively avoiding those areas just in the hours immediately following lion activity. Our results suggest that cheetahs are able to use patches of preferred habitat by avoiding lions on a moment-to-moment basis. Such fine-scale temporal avoidance is likely to be less costly than long-term avoidance of preferred areas: This may help explain why cheetahs are able to coexist with lions despite high rates of lion-inflicted mortality, and highlights reactive avoidance as a general mechanism for predator coexistence.
Negative symptoms in schizophrenia result from a failure to represent the expected value of rewards: Behavioral and computational modeling evidence

PubMed Central

Gold, James M.; Waltz, James A.; Matveeva, Tatyana M.; Kasanova, Zuzana; Strauss, Gregory P.; Herbener, Ellen S.; Collins, Anne G.E.; Frank, Michael J.

2015-01-01

Context Negative symptoms are a core feature of schizophrenia, but their pathophysiology remains unclear. Objective Negative symptoms are defined by the absence of normal function. However, there must be a productive mechanism that leads to this absence. Here, we test a reinforcement learning account suggesting that negative symptoms result from a failure to represent the expected value of rewards coupled with preserved loss avoidance learning. Design Subjects performed a probabilistic reinforcement learning paradigm involving stimulus pairs in which choices resulted in either reward or avoidance of loss. Following training, subjects indicated their valuation of the stimuli in a transfer task. Computational modeling was used to distinguish between alternative accounts of the data. Setting A tertiary care research outpatient clinic. Patients A total of 47 clinically stable patients with a diagnosis of schizophrenia or schizoaffective disorder and 28 healthy volunteers participated. Patients were divided into high and low negative symptom groups. Main Outcome measures 1) The number of choices leading to reward or loss avoidance and 2) performance in the transfer phase. Quantitative fits from three different models were examined. Results High negative symptom patients demonstrated impaired learning from rewards but intact loss avoidance learning, and failed to distinguish rewarding stimuli from loss-avoiding stimuli in the transfer phase. Model fits revealed that high negative symptom patients were better characterized by an “actor-critic” model, learning stimulus-response associations, whereas controls and low negative symptom patients incorporated expected value of their actions (“Q-learning”) into the selection process. Conclusions Negative symptoms are associated with a specific reinforcement learning abnormality: High negative symptoms patients do not represent the expected value of rewards when making decisions but learn to avoid punishments through the use of prediction errors. This computational framework offers the potential to understand negative symptoms at a mechanistic level. PMID:22310503
A Family of Well-Clear Boundary Models for the Integration of UAS in the NAS

NASA Technical Reports Server (NTRS)

Munoz, Cesar A.; Narkawicz, Anthony; Chamberlain, James; Consiglio, Maria; Upchurch, Jason

2014-01-01

The FAA-sponsored Sense and Avoid Workshop for Unmanned Aircraft Systems (UAS) defines the concept of sense and avoid for remote pilots as "the capability of a UAS to remain well clear from and avoid collisions with other airborne traffic." Hence, a rigorous definition of well clear is fundamental to any separation assurance concept for the integration of UAS into civil airspace. This paper presents a family of well-clear boundary models based on the TCAS II Resolution Advisory logic. For these models, algorithms that predict well-clear violations along aircraft current trajectories are provided. These algorithms are analogous to conflict detection algorithms but instead of predicting loss of separation, they predict whether well-clear violations will occur during a given lookahead time interval. Analytical techniques are used to study the properties and relationships satisfied by the models.
Neural Correlates Differ in High and Low Fear-Avoidant Chronic Low Back Pain Patients When Imagining Back-Straining Movements.

PubMed

Barke, Antonia; Preis, Mira A; Schmidt-Samoa, Carsten; Baudewig, Jürgen; Kröner-Herwig, Birgit; Dechent, Peter

2016-08-01

The fear-avoidance model postulates that in an initial acute phase chronic low back pain (CLBP) patients acquire a fear of movement that results in avoidance of physical activity and contributes to the pain becoming chronic. The current functional magnetic resonance imaging study investigated the neural correlates of imagining back-straining and neutral movements in CLBP patients with high (HFA) and low fear avoidance (LFA) and healthy pain-free participants. Ninety-three persons (62 CLBP patients, 31 healthy controls; age 49.7 ± 9.2 years) participated. The CLBP patients were divided into an HFA and an LFA group using the Tampa Scale of Kinesiophobia. The participants viewed pictures of back-straining and neutral movements and were instructed to imagine that they themselves were executing the activity shown. When imagining back-straining movements, HFA patients as well as healthy controls showed stronger anterior hippocampus activity than LFA patients. The neural activations of HFA patients did not differ from those of healthy controls. This may indicate that imagining back-straining movements triggered pain-related evaluations in healthy controls and HFA participants, but not in LFA participants. Although heightened pain expectancy in HFA compared with LFA patients fits well with the fear-avoidance model, the difference between healthy controls and LFA patients was unexpected and contrary to the fear-avoidance model. Possibly, negative evaluations of the back-straining movements are common but the LFA patients use some kind of strategy enabling them to react differently to the back-straining events. It appears that low fear-avoidant back pain patients use some kind of strategy or underlying mechanism that enables them to react with less fear in the face of potentially painful movements. This warrants further investigation because countering fear and avoidance provide an important advantage with respect to disability. Copyright © 2016 American Pain Society. Published by Elsevier Inc. All rights reserved.
Predictors of satisfaction in geographically close and long-distance relationships.

PubMed

Lee, Ji-yeon; Pistole, M Carole

2012-04-01

In this study, the authors examined geographically close (GCRs) and long-distance (LDRs) romantic relationship satisfaction as explained by insecure attachment, self-disclosure, gossip, and idealization. After college student participants (N = 536) completed a Web survey, structural equation modeling (SEM) multigroup analysis revealed that the GCR and LDR models were nonequivalent, as expected. Self-disclosure mediated the insecure attachment-idealization path differently in GCRs and in LDRs. Self-disclosure was positively associated with idealization in GCRs and negatively associated with idealization in LDRs, with the insecure attachment-idealization and the insecure attachment-satisfaction paths negative for both GCRs and LDRs. Furthermore, the insecure attachment-idealization path was stronger than the mediated path, especially for LDRs; the insecure attachment-satisfaction path was stronger than the mediation model for GCRs and LDRs. In other words, the GCR and LDR models differed despite some similarities. For both, with higher insecure (i.e., anxious and avoidant) attachment, the person discloses less to the partner, idealizes the partner less, and is less satisfied with the relationship. Also, people who idealize are more satisfied. In contrast, in LDRs only, with higher insecure attachment, the people tend to gossip more. With higher insecure attachment and with higher self-disclosure, people idealize more in GCRs but idealize less in LDRs. Overall, attachment insecurity explained more idealization and satisfaction in LDRs than in GCRs. Implications are discussed.
Inequalities in pediatric avoidable hospitalizations between Aboriginal and non-Aboriginal children in Australia: a population data linkage study.

PubMed

Falster, Kathleen; Banks, Emily; Lujic, Sanja; Falster, Michael; Lynch, John; Zwi, Karen; Eades, Sandra; Leyland, Alastair H; Jorm, Louisa

2016-10-21

Australian Aboriginal children experience a disproportionate burden of social and health disadvantage. Avoidable hospitalizations present a potentially modifiable health gap that can be targeted and monitored using population data. This study quantifies inequalities in pediatric avoidable hospitalizations between Australian Aboriginal and non-Aboriginal children. This statewide population-based cohort study included 1 121 440 children born in New South Wales, Australia, between 1 July 2000 and 31 December 2012, including 35 609 Aboriginal children. Using linked hospital data from 1 July 2000 to 31 December 2013, we identified pediatric avoidable, ambulatory care sensitive and non-avoidable hospitalization rates for Aboriginal and non-Aboriginal children. Absolute and relative inequalities between Aboriginal and non-Aboriginal children were measured as rate differences and rate ratios, respectively. Individual-level covariates included age, sex, low birth weight and/or prematurity, and private health insurance/patient status. Area-level covariates included remoteness of residence and area socioeconomic disadvantage. There were 365 386 potentially avoidable hospitalizations observed over the study period, most commonly for respiratory and infectious conditions; Aboriginal children were admitted more frequently for all conditions. Avoidable hospitalization rates were 90.1/1000 person-years (95 % CI, 88.9-91.4) in Aboriginal children and 44.9/1000 person-years (44.8-45.1) in non-Aboriginal children (age and sex adjusted rate ratio = 1.7 (1.7-1.7)). Rate differences and rate ratios declined with age from 94/1000 person-years and 1.9, respectively, for children aged <2 years to 5/1000 person-years and 1.8, respectively, for ages 12- < 14 years. Findings were similar for the subset of ambulatory care sensitive hospitalizations, but in contrast, non-avoidable hospitalization rates were almost identical in Aboriginal (10.1/1000 person-years, (9.6-10.5)) and non-Aboriginal children (9.6/1000 person-years (9.6-9.7)). We observed substantial inequalities in avoidable hospitalizations between Aboriginal and non-Aboriginal children regardless of where they lived, particularly among young children. Policy measures that reduce inequities in the circumstances in which children grow and develop, and improved access to early intervention in primary care, have potential to narrow this gap.

"A cigarette a day keeps the goodies away": smokers show automatic approach tendencies for smoking--but not for food-related stimuli.

PubMed

Machulska, Alla; Zlomuzica, Armin; Adolph, Dirk; Rinck, Mike; Margraf, Jürgen

2015-01-01

Smoking leads to the development of automatic tendencies that promote approach behavior toward smoking-related stimuli which in turn may maintain addictive behavior. The present study examined whether automatic approach tendencies toward smoking-related stimuli can be measured by using an adapted version of the Approach-Avoidance Task (AAT). Given that progression of addictive behavior has been associated with a decreased reactivity of the brain reward system for stimuli signaling natural rewards, we also used the AAT to measure approach behavior toward natural rewarding stimuli in smokers. During the AAT, 92 smokers and 51 non-smokers viewed smoking-related vs. non-smoking-related pictures and pictures of natural rewards (i.e. highly palatable food) vs. neutral pictures. They were instructed to ignore image content and to respond to picture orientation by either pulling or pushing a joystick. Within-group comparisons revealed that smokers showed an automatic approach bias exclusively for smoking-related pictures. Contrary to our expectations, there was no difference in smokers' and non-smokers' approach bias for nicotine-related stimuli, indicating that non-smokers also showed approach tendencies for this picture category. Yet, in contrast to non-smokers, smokers did not show an approach bias for food-related pictures. Moreover, self-reported smoking attitude could not predict approach-avoidance behavior toward nicotine-related pictures in smokers or non-smokers. Our findings indicate that the AAT is suited for measuring smoking-related approach tendencies in smokers. Furthermore, we provide evidence for a diminished approach tendency toward food-related stimuli in smokers, suggesting a decreased sensitivity to natural rewards in the course of nicotine addiction. Our results indicate that in contrast to similar studies conducted in alcohol, cannabis and heroin users, the AAT might only be partially suited for measuring smoking-related approach tendencies in smokers. Nevertheless, our findings are of special importance for current etiological models and smoking cessation programs aimed at modifying nicotine-related approach tendencies in the context of a nicotine addiction.
“A Cigarette a Day Keeps the Goodies Away”: Smokers Show Automatic Approach Tendencies for Smoking—But Not for Food-Related Stimuli

PubMed Central

Adolph, Dirk; Rinck, Mike; Margraf, Jürgen

2015-01-01

Smoking leads to the development of automatic tendencies that promote approach behavior toward smoking-related stimuli which in turn may maintain addictive behavior. The present study examined whether automatic approach tendencies toward smoking-related stimuli can be measured by using an adapted version of the Approach-Avoidance Task (AAT). Given that progression of addictive behavior has been associated with a decreased reactivity of the brain reward system for stimuli signaling natural rewards, we also used the AAT to measure approach behavior toward natural rewarding stimuli in smokers. During the AAT, 92 smokers and 51 non-smokers viewed smoking-related vs. non-smoking-related pictures and pictures of natural rewards (i.e. highly palatable food) vs. neutral pictures. They were instructed to ignore image content and to respond to picture orientation by either pulling or pushing a joystick. Within-group comparisons revealed that smokers showed an automatic approach bias exclusively for smoking-related pictures. Contrary to our expectations, there was no difference in smokers’ and non-smokers’ approach bias for nicotine-related stimuli, indicating that non-smokers also showed approach tendencies for this picture category. Yet, in contrast to non-smokers, smokers did not show an approach bias for food-related pictures. Moreover, self-reported smoking attitude could not predict approach-avoidance behavior toward nicotine-related pictures in smokers or non-smokers. Our findings indicate that the AAT is suited for measuring smoking-related approach tendencies in smokers. Furthermore, we provide evidence for a diminished approach tendency toward food-related stimuli in smokers, suggesting a decreased sensitivity to natural rewards in the course of nicotine addiction. Our results indicate that in contrast to similar studies conducted in alcohol, cannabis and heroin users, the AAT might only be partially suited for measuring smoking-related approach tendencies in smokers. Nevertheless, our findings are of special importance for current etiological models and smoking cessation programs aimed at modifying nicotine-related approach tendencies in the context of a nicotine addiction. PMID:25692468
Contribution of parents' adult attachment and separation attitudes to parent-adolescent conflict resolution.

PubMed

García-Ruiz, Marta; Rodrigo, María José; Hernández-Cabrera, Juan A; Máiquez, María Luisa

2013-12-01

This study examined the contribution to parent-adolescent conflict resolution of parental adult attachment styles and attitudes toward adolescent separation. Questionnaires were completed by 295 couples with early to late adolescent children. Structural equation models were used to test self and partner influences on conflict resolution for three attachment orientations: confidence (model A), anxiety (model B) and avoidance (model C). Model A showed self influences between parents' confidence orientation and negotiation and also via positive attitudes towards separation. Also, the fathers' use of negotiation was facilitated by the mothers' confidence orientation and vice versa, indicating partner influences as well. Model B showed self influences between parents' anxiety orientation and the use of dominance and withdrawal and also via negative attitudes towards separation. Model C showed self influences between parents' avoidance orientation and dominance and withdrawal, and a partner influence between fathers' avoidance and mothers' use of dominance. The results indicated that the parents' adult attachment system and the parenting system were related in the area of conflict resolution, and that self influences were stronger than partner influences. © 2013 The Scandinavian Psychological Associations.
Flavor network and the principles of food pairing

NASA Astrophysics Data System (ADS)

Ahn, Yong-Yeol; Ahnert, Sebastian; Bagrow, James; Barabasi, Albert-Laszlo

2011-03-01

We construct and investigate a flavor network capturing the chemical similarity between the culinary ingredients. We found that Western cuisines have a statistically significant tendency to use ingredient pairs that share many flavor compounds, in line with the food pairing hypothesis used by some chefs and molecular gastronmists. By contrast, East Asian cuisine tend to avoid compound sharing ingredients. We identify key ingredients in each cuisine that help us to explore the differences and similarities between regional cuisines.
A thermodynamically consistent discontinuous Galerkin formulation for interface separation

DOE PAGES

Versino, Daniele; Mourad, Hashem M.; Dávila, Carlos G.; ...

2015-07-31

Our paper describes the formulation of an interface damage model, based on the discontinuous Galerkin (DG) method, for the simulation of failure and crack propagation in laminated structures. The DG formulation avoids common difficulties associated with cohesive elements. Specifically, it does not introduce any artificial interfacial compliance and, in explicit dynamic analysis, it leads to a stable time increment size which is unaffected by the presence of stiff massless interfaces. This proposed method is implemented in a finite element setting. Convergence and accuracy are demonstrated in Mode I and mixed-mode delamination in both static and dynamic analyses. Significantly, numerical resultsmore » obtained using the proposed interface model are found to be independent of the value of the penalty factor that characterizes the DG formulation. By contrast, numerical results obtained using a classical cohesive method are found to be dependent on the cohesive penalty stiffnesses. The proposed approach is shown to yield more accurate predictions pertaining to crack propagation under mixed-mode fracture because of the advantage. Furthermore, in explicit dynamic analysis, the stable time increment size calculated with the proposed method is found to be an order of magnitude larger than the maximum allowable value for classical cohesive elements.« less
Supply chain carbon footprinting and responsibility allocation under emission regulations.

PubMed

Chen, Jin-Xiao; Chen, Jian

2017-03-01

Reduction of greenhouse gas emissions has become an enormous challenge for any single enterprise and its supply chain because of the increasing concern on global warming. This paper investigates carbon footprinting and responsibility allocation for supply chains involved in joint production. Our study is conducted from the perspective of a social planner who aims to achieve social value optimization. The carbon footprinting model is based on operational activities rather than on firms because joint production blurs the organizational boundaries of footprints. A general model is proposed for responsibility allocation among firms who seek to maximize individual profits. This study looks into ways for the decentralized supply chain to achieve centralized optimality of social value under two emission regulations. Given a balanced allocation for the entire supply chain, we examine the necessity of over-allocation to certain firms under specific situations and find opportunities for the firms to avoid over-allocation. The comparison of the two regulations reveals that setting an emission standard per unit of product will motivate firms to follow the standard and improve their emission efficiencies. Hence, a more efficient and promising policy is needed in contrast to existing regulations on total production. Copyright © 2016 Elsevier Ltd. All rights reserved.
Evasive mimicry: when (if ever) could mimicry based on difficulty of capture evolve?

PubMed

Ruxton, G D; Speed, M; Sherratt, T N

2004-10-22

We elucidate the conditions under which an easy-to-catch edible prey species may evolve to resemble another edible species that is much more difficult to capture ('evasive Batesian mimicry'), and the conditions under which two or more edible but hard-to-catch species evolve a common resemblance ('evasive Mullerian mimicry'). Using two complementary mathematical models, we argue that both phenomena are logically possible but that several factors will limit the prevalence of these forms of mimicry in nature. Evasive Batesian mimicry is most likely to arise when it is costly in time or energy for the predator species to pursue evasive prey, when mimics are encountered less frequently than evasive models and where there are abundant alternative prey. Evasive Mullerian mimicry, by contrast, is most likely to arise when evasive prey species differ in abundance, predators are slow to learn to avoid evasive prey and evading capture is costly to the prey. Unequivocal evidence for evasive Batesian or Mullerian mimicry has not yet been demonstrated in the field, and we argue that more empirical work is needed to test whether putative examples are indeed a result of selection to signal difficulty of capture.
Spiking Cortical Model Based Multimodal Medical Image Fusion by Combining Entropy Information with Weber Local Descriptor

PubMed Central

Zhang, Xuming; Ren, Jinxia; Huang, Zhiwen; Zhu, Fei

2016-01-01

Multimodal medical image fusion (MIF) plays an important role in clinical diagnosis and therapy. Existing MIF methods tend to introduce artifacts, lead to loss of image details or produce low-contrast fused images. To address these problems, a novel spiking cortical model (SCM) based MIF method has been proposed in this paper. The proposed method can generate high-quality fused images using the weighting fusion strategy based on the firing times of the SCM. In the weighting fusion scheme, the weight is determined by combining the entropy information of pulse outputs of the SCM with the Weber local descriptor operating on the firing mapping images produced from the pulse outputs. The extensive experiments on multimodal medical images show that compared with the numerous state-of-the-art MIF methods, the proposed method can preserve image details very well and avoid the introduction of artifacts effectively, and thus it significantly improves the quality of fused images in terms of human vision and objective evaluation criteria such as mutual information, edge preservation index, structural similarity based metric, fusion quality index, fusion similarity metric and standard deviation. PMID:27649190
Transmission of severe acute respiratory syndrome in dynamical small-world networks

NASA Astrophysics Data System (ADS)

Masuda, Naoki; Konno, Norio; Aihara, Kazuyuki

2004-03-01

The outbreak of severe acute respiratory syndrome (SARS) is still threatening the world because of a possible resurgence. In the current situation that effective medical treatments such as antiviral drugs are not discovered yet, dynamical features of the epidemics should be clarified for establishing strategies for tracing, quarantine, isolation, and regulating social behavior of the public at appropriate costs. Here we propose a network model for SARS epidemics and discuss why superspreaders emerged and why SARS spread especially in hospitals, which were key factors of the recent outbreak. We suggest that superspreaders are biologically contagious patients, and they may amplify the spreads by going to potentially contagious places such as hospitals. To avoid mass transmission in hospitals, it may be a good measure to treat suspected cases without hospitalizing them. Finally, we indicate that SARS probably propagates in small-world networks associated with human contacts and that the biological nature of individuals and social group properties are factors more important than the heterogeneous rates of social contacts among individuals. This is in marked contrast with epidemics of sexually transmitted diseases or computer viruses to which scale-free network models often apply.
Spiking Cortical Model Based Multimodal Medical Image Fusion by Combining Entropy Information with Weber Local Descriptor.

PubMed

Zhang, Xuming; Ren, Jinxia; Huang, Zhiwen; Zhu, Fei

2016-09-15

Multimodal medical image fusion (MIF) plays an important role in clinical diagnosis and therapy. Existing MIF methods tend to introduce artifacts, lead to loss of image details or produce low-contrast fused images. To address these problems, a novel spiking cortical model (SCM) based MIF method has been proposed in this paper. The proposed method can generate high-quality fused images using the weighting fusion strategy based on the firing times of the SCM. In the weighting fusion scheme, the weight is determined by combining the entropy information of pulse outputs of the SCM with the Weber local descriptor operating on the firing mapping images produced from the pulse outputs. The extensive experiments on multimodal medical images show that compared with the numerous state-of-the-art MIF methods, the proposed method can preserve image details very well and avoid the introduction of artifacts effectively, and thus it significantly improves the quality of fused images in terms of human vision and objective evaluation criteria such as mutual information, edge preservation index, structural similarity based metric, fusion quality index, fusion similarity metric and standard deviation.
Development of an adaptive bilateral filter for evaluating color image difference

NASA Astrophysics Data System (ADS)

Wang, Zhaohui; Hardeberg, Jon Yngve

2012-04-01

Spatial filtering, which aims to mimic the contrast sensitivity function (CSF) of the human visual system (HVS), has previously been combined with color difference formulae for measuring color image reproduction errors. These spatial filters attenuate imperceptible information in images, unfortunately including high frequency edges, which are believed to be crucial in the process of scene analysis by the HVS. The adaptive bilateral filter represents a novel approach, which avoids the undesirable loss of edge information introduced by CSF-based filtering. The bilateral filter employs two Gaussian smoothing filters in different domains, i.e., spatial domain and intensity domain. We propose a method to decide the parameters, which are designed to be adaptive to the corresponding viewing conditions, and the quantity and homogeneity of information contained in an image. Experiments and discussions are given to support the proposal. A series of perceptual experiments were conducted to evaluate the performance of our approach. The experimental sample images were reproduced with variations in six image attributes: lightness, chroma, hue, compression, noise, and sharpness/blurriness. The Pearson's correlation values between the model-predicted image difference and the observed difference were employed to evaluate the performance, and compare it with that of spatial CIELAB and image appearance model.
Chaos, creativity, and substance abuse: the nonlinear dynamics of choice.

PubMed

Zausner, Tobi

2011-04-01

Artists create their work in conditions of disequilibrium, states of creative chaos that may appear turbulent but are capable of bringing forth new order. By absorbing information from the environment and discharging it negentropically as new work, artists can be modeled as dissipative systems. A characteristic of chaotic systems is a heightened sensitivity to stimuli, which can generate either positive experiences or negative ones that can lead some artists to substance abuse and misguided searches for a creative chaos. Alcohol and drug use along with inadequately addressed co-occurring emotional disorders interfere with artists' quest for the nonlinearity of creativity. Instead, metaphorically modeled by a limit cycle of addiction and then a spiral to disorder, the joys of a creative chaos become an elusive chimera for them rather than a fulfilling experience. Untreated mental illness and addiction to substances have shortened the lives of artists such as Vincent Van Gogh, Frida Kahlo, Henri de Toulouse-Lautrec, and Jackson Pollock, all of whom committed suicide. In contrast Edvard Munch and John Callahan, who chose to address their emotional problems and substance abuse, continued to live and remain creative. Choosing to access previously avoided moments of pain can activate the nonlinear power of self-transformation.
Automatic optimal filament segmentation with sub-pixel accuracy using generalized linear models and B-spline level-sets

PubMed Central

Xiao, Xun; Geyer, Veikko F.; Bowne-Anderson, Hugo; Howard, Jonathon; Sbalzarini, Ivo F.

2016-01-01

Biological filaments, such as actin filaments, microtubules, and cilia, are often imaged using different light-microscopy techniques. Reconstructing the filament curve from the acquired images constitutes the filament segmentation problem. Since filaments have lower dimensionality than the image itself, there is an inherent trade-off between tracing the filament with sub-pixel accuracy and avoiding noise artifacts. Here, we present a globally optimal filament segmentation method based on B-spline vector level-sets and a generalized linear model for the pixel intensity statistics. We show that the resulting optimization problem is convex and can hence be solved with global optimality. We introduce a simple and efficient algorithm to compute such optimal filament segmentations, and provide an open-source implementation as an ImageJ/Fiji plugin. We further derive an information-theoretic lower bound on the filament segmentation error, quantifying how well an algorithm could possibly do given the information in the image. We show that our algorithm asymptotically reaches this bound in the spline coefficients. We validate our method in comprehensive benchmarks, compare with other methods, and show applications from fluorescence, phase-contrast, and dark-field microscopy. PMID:27104582
The effect of partial reinforcement on instrumental successive negative contrast in inbred Roman High- (RHA-I) and Low- (RLA-I) Avoidance rats.

PubMed

Cuenya, L; Sabariego, M; Donaire, R; Fernández-Teruel, A; Tobeña, A; Gómez, M J; Mustaca, A; Torres, C

2012-03-20

Frustration is an emotional response that can be induced by the sudden devaluation of a reinforcer in the presence of greater reinforcement expectancies (e.g. instrumental successive negative contrast, iSNC). This emotional response seems to be similar to anxiety and can be attenuated by previous experiences of reward loss (e.g. partial reinforcement, PR, as opposed to continuous reinforcement, CR). In this study we used iSNC and PR procedures in order to compare the performance of two strains of rats psychogenetically selected on the basis of their emotional reactivity: the inbred Roman High- (RHA-I, low anxiety) and Low- (RLA-I, high anxiety) Avoidance rats. Animals were exposed to a straight alley, where they were changed from 12 pellets in the preshift phase (presented in 100% of trials-CR vs. 50% of trials-PR) to 2 pellets in the postshift phase, or exposed to 2 pellets throughout the training. The results indicated that the iSNC only appeared in RLA-I rats exposed to CR, as opposed to RLA-I animals exposed to PR and to RHA-I rats exposed to PR or CR. These data seem to support the implication of emotional responses in both iSNC and PR situations, and indicate that the behavioral reactivity to reward loss experiences is modulated by genetic variables. Published by Elsevier Inc.
[Safety and efficacy of percutaneous patent ductus arteriosus closure solely under thoracic echocardiography guidance].

PubMed

Pan, Xiangbin; Ouyang, Wenbin; Li, Shoujun; Guo, Gaili; Liu, Yao; Zhang, Dawei; Zhang, Fengwen; Pang, Kunjing; Fang, Nengxin; Hu, Shengshou

2015-01-01

To avoid the radiation injuries and use of contrast agent, we assessed the safety and efficacy of percutaneous patent ductus arteriosus closure solely under thoracic echocardiography guidance. From June 2013 to June 2014, thirty patients (mean age: (6.3 ± 2.5) years, mean body weight:(22.5 ± 7.3) kg) with pure patent ductus arteriosus were continuously included in this study. The mean diameter of patent ductus arteriosus was (3.8 ± 0.9) mm. Patients were all treated by percutaneous patent ductus arteriosus closure via right femoral artery solely under thoracic echocardiography guidance. The efficacy of the procedure was evaluated by thoracic echocardiography. Follow-up was performed at one month after procedure. All 30 cases were successfully treated with percutaneous patent ductus arteriosus closure solely under thracic echocardiography guidance. The procedural time was (32.8 ± 5.7) minutes. The mean diameter of Amplatzer ADO II was (4.9 ± 1.0) mm. Postoperative trivial residual shunt occurred in six patients immediately after the procedure. All patients survived without peripheral vascular injury or complications such as cardiac perforation. Hospitalization time was (3.4 ± 0.7) days. At one-month follow-up, no complications such as residual shunt or pericardial effusion were observed. Echocardiography guided percutaneous patent ductus arteriosus closure by femoral artery approach is safe and effective, and can avoid X-ray and the use of contrast agents.
Neutrinoless double-β decay of Se82 in the shell model: Beyond the closure approximation

NASA Astrophysics Data System (ADS)

Sen'kov, R. A.; Horoi, M.; Brown, B. A.

2014-05-01

We recently proposed a method [R. A. Senkov and M. Horoi, Phys. Rev. C 88, 064312 (2013), 10.1103/PhysRevC.88.064312] to calculate the standard nuclear matrix elements for neutrinoless double-β decay (0νββ) of Ca48 going beyond the closure approximation. Here we extend this analysis to the important case of Se82, which was chosen as the base isotope for the upcoming SuperNEMO experiment. We demonstrate that by using a mixed method that considers information from closure and nonclosure approaches, one can get excellent convergence properties for the nuclear matrix elements, which allows one to avoid unmanageable computational costs. We show that in contrast with the closure approximation the mixed approach has a very weak dependence on the average closure energy. The matrix elements for the heavy neutrino-exchange mechanism that could contribute to the 0νββ decay of Se82 are also presented.
Locations of ectopic beats coincide with spatial gradients of NADH in a regional model of low-flow reperfusion.

PubMed

Kay, Matthew; Swift, Luther; Martell, Brian; Arutunyan, Ara; Sarvazyan, Narine

2008-05-01

We studied the origins of ectopic beats during low-flow reperfusion after acute regional ischemia in excised rat hearts. The left anterior descending coronary artery was cannulated. Perfusate was delivered to the cannula using an high-performance liquid chromatography pump. This provided not only precise control of flow rate but also avoided mechanical artifacts associated with vessel occlusion and deocclusion. Optical mapping of epicardial transmembrane potential served to identify activation wavefronts. Imaging of NADH fluorescence was used to quantify local ischemia. Our experiments suggest that low-flow reperfusion of ischemic myocardium leads to a highly heterogeneous ischemic substrate and that the degree of ischemia between adjacent patches of tissue changes in time. In contrast to transient ectopic activity observed during full-flow reperfusion, persistent ectopic arrhythmias were observed during low-flow reperfusion. The origins of ectopic beats were traceable to areas of high spatial gradients of changes in NADH fluorescence caused by low-flow reperfusion.
Distal mdx muscle groups exhibiting up-regulation of utrophin and rescue of dystrophin-associated glycoproteins exemplify a protected phenotype in muscular dystrophy

NASA Astrophysics Data System (ADS)

Dowling, Paul; Culligan, Kevin; Ohlendieck, Kay

2002-02-01

Unique unaffected skeletal muscle fibres, unlike necrotic torso and limb muscles, may pave the way for a more detailed understanding of the molecular pathogenesis of inherited neuromuscular disorders and help to develop new treatment strategies for muscular dystrophies. The sparing of extraocular muscle in Duchenne muscular dystrophy is mostly attributed to the special protective properties of extremely fast-twitching small-diameter fibres, but here we show that distal muscles also represent a particular phenotype that is more resistant to necrosis. Immunoblot analysis of membranes isolated from the well established dystrophic animal model mdx shows that, in contrast to dystrophic limb muscles, the toe musculature exhibits an up-regulation of the autosomal dystrophin homologue utrophin and a concomitant rescue of dystrophin-associated glycoproteins. Thus distal mdx muscle groups provide a cellular system that naturally avoids myofibre degeneration which might be useful in the search for naturally occurring compensatory mechanisms in inherited skeletal muscle diseases.
Facing two faces: Defense activation varies as a function of personal relevance.

PubMed

Bublatzky, Florian; Alpers, Georg W

2017-04-01

It can be unsettling to be watched by a group of people, and when they express anger or hostility, this can prime defensive behavior. In contrast, when others smile at us, this may be comforting. This study tested to which degree the impact of facial expressions (happy, neutral, and angry) varies with the personal relevance of a social situation. Modelling a triadic situation, two faces looked either directly at the participant, faced each other, or they were back to back. Results confirmed that this variation constitutes a gradient of personal relevance (directed frontally > towards > away), as reflected by corresponding defensive startle modulation and autonomic nervous system activity. This gradient was particularly pronounced for angry faces and it was steeper in participants with higher levels of social anxiety. Thus, sender-recipient constellations modulate the processing of facial emotions in favor of adequate behavioral responding (e.g., avoidance) in group settings. Copyright © 2017 Elsevier B.V. All rights reserved.
Path integral Monte Carlo determination of the fourth-order virial coefficient for unitary two-component Fermi gas with zero-range interactions

NASA Astrophysics Data System (ADS)

Yan, Yangqian; Blume, D.

2016-05-01

The unitary equal-mass Fermi gas with zero-range interactions constitutes a paradigmatic model system that is relevant to atomic, condensed matter, nuclear, particle, and astro physics. This work determines the fourth-order virial coefficient b4 of such a strongly-interacting Fermi gas using a customized ab inito path integral Monte Carlo (PIMC) algorithm. In contrast to earlier theoretical results, which disagreed on the sign and magnitude of b4, our b4 agrees with the experimentally determined value, thereby resolving an ongoing literature debate. Utilizing a trap regulator, our PIMC approach determines the fourth-order virial coefficient by directly sampling the partition function. An on-the-fly anti-symmetrization avoids the Thomas collapse and, combined with the use of the exact two-body zero-range propagator, establishes an efficient general means to treat small Fermi systems with zero-range interactions. We gratefully acknowledge support by the NSF.

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