747 research outputs found
Competing Ferromagnetic and Charge-Ordered States in Models for Manganites: the Origin of the CMR Effect
The one-orbital model for manganites with cooperative phonons and
superexchange coupling has been investigated via large-scale Monte
Carlo (MC) simulations. Results for two-orbitals are also briefly discussed.
Focusing on electronic density =0.75, a regime of competition between
ferromagnetic (FM) metallic and charge-ordered (CO) insulating states was
identified. In the vicinity of the associated bicritical point, colossal
magnetoresistance (CMR) effects were observed. The CMR is associated with the
development of short-distance correlations among polarons, above the spin
ordering temperatures, resembling the charge arrangement of the low-temperature
CO state.Comment: 4 pages, 4 figures, accepted for publication in the Phys. Rev. Let
I Probe, Therefore I Am: Designing a Virtual Journalist with Human Emotions
By utilizing different communication channels, such as verbal language,
gestures or facial expressions, virtually embodied interactive humans hold a
unique potential to bridge the gap between human-computer interaction and
actual interhuman communication. The use of virtual humans is consequently
becoming increasingly popular in a wide range of areas where such a natural
communication might be beneficial, including entertainment, education, mental
health research and beyond. Behind this development lies a series of
technological advances in a multitude of disciplines, most notably natural
language processing, computer vision, and speech synthesis. In this paper we
discuss a Virtual Human Journalist, a project employing a number of novel
solutions from these disciplines with the goal to demonstrate their viability
by producing a humanoid conversational agent capable of naturally eliciting and
reacting to information from a human user. A set of qualitative and
quantitative evaluation sessions demonstrated the technical feasibility of the
system whilst uncovering a number of deficits in its capacity to engage users
in a way that would be perceived as natural and emotionally engaging. We argue
that naturalness should not always be seen as a desirable goal and suggest that
deliberately suppressing the naturalness of virtual human interactions, such as
by altering its personality cues, might in some cases yield more desirable
results.Comment: eNTERFACE16 proceeding
Challenging people's political views and values makes them think even harder and produce better arguments to defend themselves
To many, American politics and society seem more polarized than they have ever been. Why, then do people cling so tightly to their values, identities and attitudes? In new research, Cengiz Erisen, David P. Redlawsk, and Elif Erisen looked at the effects of presenting people with information that conflicted or refuted their own ideologies. They found that far from convincing ..
The Role of Visual Features in Text-Based CAPTCHAs: An fNIRS Study for Usable Security
To mitigate dictionary attacks or similar undesirable automated attacks to
information systems, developers mostly prefer using CAPTCHA challenges as Human
Interactive Proofs (HIPs) to distinguish between human users and scripts.
Appropriate use of CAPTCHA requires a setup that balances between robustness
and usability during the design of a challenge. The previous research reveals
that most usability studies have used accuracy and response time as measurement
criteria for quantitative analysis. The present study aims at applying optical
neuroimaging techniques for the analysis of CAPTCHA design. The functional
Near-Infrared Spectroscopy technique was used to explore the hemodynamic
responses in the prefrontal cortex elicited by CAPTCHA stimulus of varying
types. )e findings suggest that regions in the left and right dorsolateral and
right dorsomedial prefrontal cortex respond to the degrees of line occlusion,
rotation, and wave distortions present in a CAPTCHA. The systematic addition of
the visual effects introduced nonlinear effects on the behavioral and
prefrontal oxygenation measures, indicative of the emergence of Gestalt effects
that might have influenced the perception of the overall CAPTCHA figure.Comment: 24 pages, 32 figures, Computational Intelligence and Neuroscienc
The Basal Ganglia Is Necessary for Learning Spectral, but Not Temporal, Features of Birdsong
SummaryExecuting a motor skill requires the brain to control which muscles to activate at what times. How these aspects of control—motor implementation and timing—are acquired, and whether the learning processes underlying them differ, is not well understood. To address this, we used a reinforcement learning paradigm to independently manipulate both spectral and temporal features of birdsong, a complex learned motor sequence, while recording and perturbing activity in underlying circuits. Our results uncovered a striking dissociation in how neural circuits underlie learning in the two domains. The basal ganglia was required for modifying spectral, but not temporal, structure. This functional dissociation extended to the descending motor pathway, where recordings from a premotor cortex analog nucleus reflected changes to temporal, but not spectral, structure. Our results reveal a strategy in which the nervous system employs different and largely independent circuits to learn distinct aspects of a motor skill
Study of Short-distance Spin and Charge Correlations and Local Density-of-States in the CMR regime of the One-Orbital Model for Manganites
The metal-insulator transition, and the associated magnetic transition, in
the colossal magnetoresistance (CMR) regime of the one-orbital model for
manganites is here studied using Monte Carlo (MC) techniques. Both cooperative
oxygen lattice distortions and a finite superexchange coupling among the
spins are included in our investigations. Charge and spin
correlations are studied. In the CMR regime, a strong competition between the
ferromagnetic metallic and antiferromagnetic charge-ordered insulating states
is observed. This competition is shown to be important to understand the
resistivity peak that appears near the critical temperature. Moreover, it is
argued that the system is dynamically inhomogeneous, with short-range charge
and spin correlations that slowly evolve with MC time, producing the glassy
characteristics of the CMR state. The local density-of-states (LDOS) is also
investigated, and a pseudogap (PG) is found to exist in the CMR temperature
range. The width of the PG in the LDOS is calculated and directly compared with
recent scanning-tunneling-spectroscopy (STS) experimental results. The
agreement between our calculation and the experiment suggests that the
depletion of the conductance at low bias observed experimentally is a
reflection on the existence of a PG in the LDOS spectra, as opposed to a hard
gap. The apparent homogeneity observed via STS techniques could be caused by
the slow time characteristics of this probe. Faster experimental methods should
unveil a rather inhomogeneous state in the CMR regime, as already observed in
neutron scattering experiments.Comment: 13 pages, 10 figure
Gold Coast diagnostic criteria increase sensitivity in amyotrophic lateral sclerosis
Objective: This study evaluates diagnostic accuracy of the proposed ‘Gold Coast’ (GC) diagnostic criteria for amyotrophic lateral sclerosis (ALS). Methods: Five European centres retrospectively sampled consecutive patients referred for electromyography on suspicion of ALS. Patients were classified according to the GC criteria, the revised El Escorial (rEE) criteria and the Awaji (AW) criteria without and with the ‘Possible’ category (+ Poss). Reference standard was ALS confirmed by disease progression at follow-up. Results: Of 404 eligible patients 272 were diagnosed as ALS, 94 had mimicking disorders, 35 were lost for follow-up, and three had insufficient data. Sensitivity for the GC criteria was 88.2% (95% CI: 83.8-91.8%), which was higher than for previous criteria, of which the AW + Poss criteria reached the highest sensitivity of 77.6% (95% CI: 72.2–82.4%) (p < 0.001). Specificity was high for all criteria. The increase in sensitivity for the GC criteria was mainly due to the inclusion of 28 patients with progressive muscular atrophy (PMA). Conclusions: The simpler GC criteria increase the sensitivity, primarily due to considering PMA as a form of ALS with high specificity preserved. Significance: This validation study supports that GC criteria should be used in clinical practice and may be used for inclusion in trials
3D segmentation of intervertebral discs: from concept to the fabrication of patient-specific scaffolds
Aim: To develop a methodology for producing patient-specific scaffolds that mimic the annulus fibrosus (AF) of the human intervertebral disc (IVD) by means of combining magnetic resonance imaging (MRI) and 3D bioprinting. Methods: In order to obtain the AF 3D model from patientâ s volumetric MRI dataset, the RheumaSCORE segmentation software was used. Polycaprolactone scaffolds with three different internal architectures were fabricated by 3D bioprinting, and characterized by micro-computed tomography.
Results: The demonstrated methodology of a geometry reconstruction pipeline enabled to successfully obtain an accurate AF model and 3D print patient-specific scaffolds with different internal architectures.
Conclusion: The results guide us towards patient-specific IVD tissue engineering as demonstrated a way of manufacturing personalized scaffolds using patient's MRI data.The authors would like to acknowledge the financial support provided by the Portuguese Foundation for Science and Technology (FCT) through the project EPIDisc (UTAPEXPL/BBB-ECT/0050/2014),
funded in the Framework of the ‘International Collaboratory for Emerging Technologies, CoLab’, UT
justin|Portugal Program. FCT is also acknowledged for the PhD scholarship attributed to IF Cengiz (SFRH/
BD/99555/2014) and the financial support provided to J Silva-Correia (SFRH/BPD/100590/2014 and IF/00115/2015).
JM Oliveira also thanks the FCT for the funds provided under the program Investigador FCT (IF/00423/2012 and IF/01285/2015). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.
No writing assistance was utilized in the production of this manuscript.info:eu-repo/semantics/publishedVersio
The effect of initial pH and retention time on boron removal by continuous electrocoagulation process
In this study, factors influencing boron removal via the continuous electrocoagulation process were investigated at lab-scale. Different influent pH values (4, 5, 6, 7.45 and 9) and contact times (10, 25, 50 and 100 min) were examined as variable parameters. Plate-type aluminium electrodes with 5 mm distance between them were used. All the experiments were conducted in continuous mode and the current density was kept constant at 5 A throughout the whole experimental period. The initial boron concentration was selected to be 1000 mg L-1. The first set of experiments concerning the influence of the influent pH showed that the highest boron removal (67%) was obtained at pH=6 since it was the optimal pH for boron precipitation through aluminium borate formation. Under the constant current density of the study and with the initial pH adjusted to 6, increasing the duration of the electrocoagulation process from 10 to 100 min resulted in raising the boron removal from 45 to 79% during the second set of experiments. The greater duration of the electrocagulation process enabled higher aluminium dissolution, thus allowing the existence of a higher number of coagulants within the reactor. Moreover, it enhanced boron precipitation because of the longer contact time between the boron ions and the coagulants. After optimizing significant parameters such as the influent pH and the electrocagulation duration, the continuous electrocoagulation process was found to constitute an effective alternative for boron removal
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