541 research outputs found
The winner’s curse: conditional reasoning & belief formation
We investigate the relevance of conditional reasoning and belief formation for the
occurrence of the winner’s curse with the help of two experimental manipulations.
First, we compare results from a very simple common-value auction game with results
from a transformed version of this game that does not require any conditioning
on future events. In human opponent settings, we observe significant differences
in behavior across the two games. Second, we investigate subjects’ behavior when
they face naĂŻve computerized opponents and after they have faced them. We find
that both strong and weak assistance in belief formation changes subjects’ play
significantly in the auction game. Overall, the results suggest that the difficulty
of conditioning on future events is at least as important in explaining frequent
occurrences of the winner’s curse as is the challenge to form beliefs
linking goal-directed and model-based behavior
In experimental psychology different experiments have been developed to assess
goal–directed as compared to habitual control over instrumental decisions.
Similar to animal studies selective devaluation procedures have been used.
More recently sequential decision-making tasks have been designed to assess
the degree of goal-directed vs. habitual choice behavior in terms of an
influential computational theory of model-based compared to model-free
behavioral control. As recently suggested, different measurements are thought
to reflect the same construct. Yet, there has been no attempt to directly
assess the construct validity of these different measurements. In the present
study, we used a devaluation paradigm and a sequential decision-making task to
address this question of construct validity in a sample of 18 healthy male
human participants. Correlational analysis revealed a positive association
between model-based choices during sequential decisions and goal-directed
behavior after devaluation suggesting a single framework underlying both
operationalizations and speaking in favor of construct validity of both
measurement approaches. Up to now, this has been merely assumed but never been
directly tested in humans
Opposing roles for amygdala and vmPFC in the return of appetitive conditioned responses in humans
Learning accounts of addiction and obesity emphasize the persistent power of Pavlovian reward cues to trigger craving and increase relapse risk. While extinction can reduce conditioned responding, Pavlovian relapse phenomena-the return of conditioned responding following successful extinction-challenge the long-term success of extinction-based treatments. Translational laboratory models of Pavlovian relapse could therefore represent a valuable tool to investigate the mechanisms mediating relapse, although so far human research has mostly focused on return of fear phenomena. To this end we developed an appetitive conditioning paradigm with liquid food rewards in combination with a 3-day design to investigate the return of appetitive Pavlovian responses and the involved neural structures in healthy subjects. Pavlovian conditioning (day 1) was assessed in 62 participants, and a subsample (n = 33) further completed extinction (day 2) and a reinstatement test (day 3). Conditioned responding was assessed on explicit (pleasantness ratings) and implicit measures (reaction time, skin conductance, heart rate, startle response) and reinstatement effects were further evaluated using fMRI. We observed a return of conditioned responding during the reinstatement test, evident by enhanced skin conductance responses, accompanied by enhanced BOLD responses in the amygdala. On an individual level, psychophysiological reinstatement intensity was significantly anticorrelated with ventromedial prefrontal cortex (vmPFC) activation, and marginally anticorrelated with enhanced amygdala-vmPFC connectivity during late reinstatement. Our results extend evidence from return of fear phenomena to the appetitive domain, and highlight the role of the vmPFC and its functional connection with the amygdala in regulating appetitive Pavlovian relapse
Ablation and functionalization of flexographic printing forms using femtosecond lasers for additively manufactured polymer-optical waveguides
An efficient and low-cost approach to manufacture Opto-Mechatronic Interconnect Devices will be obligatory to handle the strongly increasing amount of data. The presented approach is based on a flexographic printing process. To adjust the transferred material the printing form is functionalized by means of laser-induced structures using an ultrashort-pulsed laser. The long-term goal is to adjust the printing result through microstructures in the printing form in order to create spatially resolved material transfer. In this work, first the ablation parameters are investigated at different repetition rates using a femtosecond laser. Further, a line structure is inserted in the material transferring areas of the printing form, which is consequently widened. Its influence on the printing result is presented. © 2020 The Authors. Published by Elsevier B.V
Modeling Human Visual Search Performance on Realistic Webpages Using Analytical and Deep Learning Methods
Modeling visual search not only offers an opportunity to predict the
usability of an interface before actually testing it on real users, but also
advances scientific understanding about human behavior. In this work, we first
conduct a set of analyses on a large-scale dataset of visual search tasks on
realistic webpages. We then present a deep neural network that learns to
predict the scannability of webpage content, i.e., how easy it is for a user to
find a specific target. Our model leverages both heuristic-based features such
as target size and unstructured features such as raw image pixels. This
approach allows us to model complex interactions that might be involved in a
realistic visual search task, which can not be easily achieved by traditional
analytical models. We analyze the model behavior to offer our insights into how
the salience map learned by the model aligns with human intuition and how the
learned semantic representation of each target type relates to its visual
search performance.Comment: the 2020 CHI Conference on Human Factors in Computing System
Exact-Exchange Kohn-Sham formalism applied to one-dimensional periodic electronic systems
The Exact-Exchange (EXX) Kohn-Sham formalism, which treats exchange
interactions exactly within density-functional theory, is applied to
one-dimensional periodic systems. The underlying implementation does not rely
on specific symmetries of the considered system and can be applied to any kind
of periodic structure in one to three dimensions. As a test system,
-polyacetylene, both in form of an isolated chain and in the bulk
geometry has been investigated. Within the EXX scheme, bandstructures and
independent particle response functions are calculated and compared to
experimental data as well as to data calculated by several other methods.
Compared to results from the local-density approximation, the EXX method leads
to an increased value for the band gap, in line with similar observations for
three-dimensional semiconductors. An inclusion of correlation potentials within
the local density approximation or generalized gradient approximations leads to
only negligible effects in the bandstructure. The EXX band gaps are in good
agreement with experimental data for bulk -polyacetylene. Packing
effects of the chains in bulk -polyacetylene are found to lower the band
gap by about 0.5 eV
Is the Post-Radical Prostatectomy Gleason Score a Valid Predictor of Mortality after Neoadjuvant Hormonal Treatment?
Purpose: To evaluate the validity of the Gleason score after neoadjuvant hormonal treatment as predictor of diseasespecific mortality after radical prostatectomy. Patients and Methods: A total of 2,880 patients with a complete data set and a mean follow-up of 10.3 years were studied; 425 of them (15%) had a history of hormonal treatment prior to surgery. The cumulative incidence of deaths from prostate cancer was determined by univariate and multivariate competing risk analysis. Cox proportional hazard models for competing risks were used to study combined effects of the variables on prostate cancer-specific mortality. Results: A higher portion of specimens with a history of neoadjuvant hormonal treatment were assigned Gleason scores of 8–10 (28 vs. 17%, p < 0.0001). The mortality curves in the Gleason score strata <8 vs. 8–10 were at large congruent in patients with and without neoadjuvant hormonal treatment. In patients with neoadjuvant hormonal treatment, a Gleason score of 8–10 was an independent predictor of prostate cancer-specific mortality; the hazard ratio was, however, somewhat lower than in patients without neoadjuvant hormonal treatment. Conclusion: This study suggests that the prognostic value of the post-radical prostatectomy Gleason score is not meaningfully jeopardized by heterogeneous neoadjuvant hormonal treatment in a routine clinical setting
The Association Between Persistent White-Matter Abnormalities and Repeat Injury After Sport-Related Concussion
Objective: A recent systematic review determined that the physiological effects of concussion may persist beyond clinical recovery. Preclinical models suggest that ongoing physiological effects are accompanied by increased cerebral vulnerability that is associated with risk for subsequent, more severe injury. This study examined the association between signal alterations on diffusion tensor imaging following clinical recovery of sport-related concussion in athletes with and without a subsequent second concussion. Methods: Average mean diffusivity (MD) was calculated in a region of interest (ROI) in which concussed athletes (n = 82) showed significantly elevated MD acutely after injury (<48 h), at an asymptomatic time point, 7 days post-return to play (RTP), and 6 months relative to controls (n = 69). The relationship between MD in the identified ROI and likelihood of sustaining a subsequent concussion over a 1-year period was examined with a binary logistic regression (re-injured, yes/no). Results: Eleven of 82 concussed athletes (13.4%) sustained a second concussion within 12 months of initial injury. Mean MD at 7 days post-RTP was significantly higher in those athletes who went on to sustain a repeat concussion within 1 year of initial injury than those who did not (p = 0.048; d = 0.75). In this underpowered sample, the relationship between MD at 7 days post-RTP and likelihood of sustaining a secondary injury approached significance [χ2 (1) = 4.17, p = 0.057; B = 0.03, SE = 0.017; OR = 1.03, CI = 0.99, 1.07]. Conclusions: These preliminary findings raise the hypothesis that persistent signal abnormalities in diffusion imaging metrics at RTP following concussion may be predictive of a repeat concussion. This may reflect a window of cerebral vulnerability or increased susceptibility following concussion, though understanding the clinical significance of these findings requires further study
Technical Developments and Ex Vivo Demonstration in a Mouse Model of Neuroinflammation
Neuroinflammation can be monitored using fluorine-19 (19F)-containing
nanoparticles and 19F MRI. Previously we studied neuroinflammation in
experimental autoimmune encephalomyelitis (EAE) using room temperature (RT)
19F radiofrequency (RF) coils and low spatial resolution 19F MRI to overcome
constraints in signal-to-noise ratio (SNR). This yielded an approximate
localization of inflammatory lesions. Here we used a new 19F transceive
cryogenic quadrature RF probe (19F-CRP) that provides the SNR necessary to
acquire superior spatially-resolved 19F MRI. First we characterized the
signal-transmission profile of the 19F-CRP. The 19F-CRP was then benchmarked
against a RT 19F/1H RF coil. For SNR comparison we used reference compounds
including 19F-nanoparticles and ex vivo brains from EAE mice administered with
19F-nanoparticles. The transmit/receive profile of the 19F-CRP diminished with
increasing distance from the surface. This was counterbalanced by a
substantial SNR gain compared to the RT coil. Intraparenchymal inflammation in
the ex vivo EAE brains was more sharply defined when using 150 ÎĽm isotropic
resolution with the 19F-CRP, and reflected the known distribution of EAE
histopathology. At this spatial resolution, most 19F signals were undetectable
using the RT coil. The 19F-CRP is a valuable tool that will allow us to study
neuroinflammation with greater detail in future in vivo studies
Quantum optimal control in quantum technologies. Strategic report on current status, visions and goals for research in Europe
Quantum optimal control, a toolbox for devising and implementing the shapes of external fields that accomplish given tasks in the operation of a quantum device in the best way possible, has evolved into one of the cornerstones for enabling quantum technologies. The last few years have seen a rapid evolution and expansion of the field. We review here recent progress in our understanding of the controllability of open quantum systems and in the development and application of quantum control techniques to quantum technologies. We also address key challenges and sketch a roadmap for future developments
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