The closer, the better? Processing relations between picture elements in historical paintings

The present eye-tracking study investigated how audio explanations influence perception and the cognitive processing of historical paintings. Spatially close and distant pairs of picture elements and their semantic relations were named in an audio text either immediately after each other or with descriptions of other elements in between. It was assumed that the number of backward fixation counts on the first of the two mentioned related picture elements should be higher if they are spatially close rather than spatially distant. There should also be more backward fixation counts if the elements are named temporally close rather than temporally distant. Similar predictions were made for the retention of these picture elements and their relations. A 2x2x2 within-subject design (n=36) with spatial distance (close vs. distant), temporal distance (close vs. distant) and painting (Leutze vs. West) revealed more background fixation counts for spatially close compared to spatially distant elements but just for the Leutze painting. Accordingly, the relations between the spatially close pairs were retained better than between the spatially distant pairs in the Leutze painting but vice versa for the West painting. The results are discussed with regard to the spatial contiguity principle of multimedia learning and research on text coherence

Efficiency Optimization in Burst-Mode Buck DC/DC Converters for Sensor Nodes

© 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In autonomous sensor nodes, switching dc/dc converters are usually employed to power the sensor electronics and also to maintain the operating voltage of an energy transducer around its maximum power point. In such a context, this paper optimizes the power efficiency of buck dc/dc converters when operating in burst mode, which is preferable than the conventional pulse-width modulation technique in lowpower sensor applications. The optimization is carried out by selecting an optimal inductor current to efficiently transfer the energy from the input to the output during the burst. Such optimization is applied when regulating the converter’s output voltage, which corresponds to the supply voltage of the sensor electronics, and also the input voltage, which corresponds to the operating voltage of the energy transducer that is here a photovoltaic module. The theoretical analysis and the experimental results reported herein prove the existence of such an optimal inductor current in both scenarios. Experimental tests with a commercial buck dc/dc converter (TPS62750) show that the use of this optimal inductor current provides up to 9% increase in efficiency, thus prolonging the operating lifetime of the sensor node.Peer ReviewedPostprint (published version

Consuming multiple linked data sources: Challenges and Experiences

Linked Data has provided the means for a large number of considerable knowledge resources to be published and interlinked utilising Semantic Web technologies. However it remains difficult to make use of this ‘Web of Data’ fully, due to its inherently distributed and often inconsistent nature. In this paper we introduce core challenges faced when consuming multiple sources of Linked Data, focussing in particular on the problem of querying. We compare both URI resolution and federated query approaches, and outline the experiences gained in the development of an application which utilises a hybrid approach to consume Linked Data from the unbounded web

Effective deep brain stimulation co-modulate cross-frequency coupling [Abstract]

Objective: The disruption of pathological signals in the cortico-basal ganglia- network has been hypothesized as a mechanism of action of deep brain stimulation (DBS). However, a comprehensive model for DBS modulating oscillations is still missing. Background: Besides considering gamma as physiologic and pro-kinetic, it has been suggested that finely tuned gamma oscillations between 60-90Hz reflect dynamic processing, possibly by inducing local inhibition or facilitation. Most studies investigating gamma focused on oscillations within the STN, motor cortex (M1), supplementary motor area (SMA), and the pallidum (Allert et al., 2018). Furthermore, elements of the BG-thalamocortical network like the premotor (PMC) or prefrontal cortices (PFC) and the sub-cortical network of cerebellum (CB) have been neglected to date. Method: We recorded resting state high-density 256-channels EEG of 31 PD-patients during DBS at the clinically most effective frequency (i.e 130Hz or 160Hz). We compared spectral power and cross-frequency coupling (frequency to power) of cortical and subcortical regions using a beamformer algorithm for coherent sources (Muthuraman et al., 2018). Two clinically ineffective frequencies have been tested as control conditions. Results: We demonstrated that clinically effective STN-DBS alters oscillatory activity in a wide-spread network of cortical and subcortical regions. A reduction of beta and increase of gamma power is attested in the cortical (M1, SMA, PMC, PFC) and sub-cortical network nodes (STN, CB). Additionally, we found increased cross-frequency coupling of narrowband gamma frequencies to the stimulation frequency in the same nodes of the cortico-subcortical network. No such dynamics were revealed within control regions (i.e. posterior parietal cortex). Furthermore, stimulating at lower or higher frequencies did not significantly alter the networks’ source power spectra or cross-frequency coupling. Conclusion: We were able to show a modulation of beta- and gamma-power and cross-frequency coupling during DBS with HD-EEG in a cortical-sub cortical network. DBS does not exclusively influence motor-function but also the physiological processing related to facilitation and dynamic adaptation, in line with the proposed function of gamma oscillations

Unravelling Charge Carrier Mobility in d₀ ‐Metal‐based Spinels

Enabling high Mg ion mobility, spinel-type materials are promising candidates for cathode or solid electrolyte applications. To elucidate the factors governing the observed high mobility of multivalent ions, periodic DFT calculations of various charge carriers (A=Li, Na, K, Mg, Ca, Zn and Al) in the ASc₂S₄ and ASc₂Se₄ spinel compounds were performed, resulting in the identification of a Brønsted-Evans-Polanyi-type scaling relation for the migration barriers of the various charge carriers. Combining this scaling relation with the derivation of a descriptor, solely based on easily accessible observables, constitutes a conceptual framework to investigate ion mobility in d₀-metal-based spinel chalcogenides with significantly reduced computational effort. This approach was exemplarily verified for various d₀-metal-based spinel chalcogenide compounds AB₂X₄ (B=Sc, Y, Ga, In, Er and Tm; X=O, S and Se) and led to the identification of d₀-metal-based CaB₂O₄ spinels as promising compounds possibly enabling high Ca ion mobility

Dynamics in binary cluster crystals

As a result of the application of coarse-graining procedures to describe complex fluids, the study of systems consisting of particles interacting through bounded, repulsive pair potentials has become of increasing interest in the last years. A well known example is the so-called Generalized Exponential Model (GEM-$m$), for which the interaction between particles is described by the potential $v(r)=\epsilon\exp[-(r/\sigma)^m]$. Interactions with $m > 2$ lead to the formation of a novel phase of soft matter consisting of cluster crystals. Recent studies on the phase behavior of binary mixtures of GEM-$m$ particles have provided evidence for the formation of novel kinds of alloys, depending on the cross interactions between the two species. This work aims to study the dynamic behavior of such binary mixtures by means of extensive molecular dynamics simulations, and in particular to investigate the effect of the addition of non-clustering particles on the dynamic scenario of one-component cluster crystals. Analogies and differences with the one-component case are revealed and discussed by analyzing self- and collective dynamic correlators.Comment: 17 pages, 8 figures, submitted to JSTA

Deciphering the network effects of deep brain stimulation in Parkinson's disease

Introduction Deep brain stimulation of the subthalamic nucleus (STN-DBS) is an established therapy for Parkinson's disease (PD). However, a more detailed characterization of the targeted network and its grey matter (GM) terminals that drive the clinical outcome is needed. In this direction, the use of MRI after DBS surgery is now possible due to recent advances in hardware, opening a window for the clarification of the association between the affected tissue, including white matter fiber pathways and modulated GM regions, and the DBS-related clinical outcome. Therefore, we present a computational framework for reconstruction of targeted networks on postoperative MRI. Methods We used a combination of preoperative whole-brain T1-weighted (T1w) and diffusion-weighted MRI data for morphometric integrity assessment and postoperative T1w MRI for electrode reconstruction and network reconstruction in 15 idiopathic PD patients. Within this framework, we made use of DBS lead artifact intensity profiles on postoperative MRI to determine DBS locations used as seeds for probabilistic tractography to cortical and subcortical targets within the motor circuitry. Lastly, we evaluated the relationship between brain microstructural characteristics of DBS-targeted brain network terminals and postoperative clinical outcomes. Results The proposed framework showed robust performance for identifying the DBS electrode positions. Connectivity profiles between the primary motor cortex (M1), supplementary motor area (SMA), and DBS locations were strongly associated with the stimulation intensity needed for the optimal clinical outcome. Local diffusion properties of the modulated pathways were related to DBS outcomes. STN-DBS motor symptom improvement was highly associated with cortical thickness in the middle frontal and superior frontal cortices, but not with subcortical volumetry. Conclusion These data suggest that STN-DBS outcomes largely rely on the modulatory interference from cortical areas, particularly M1 and SMA, to DBS locations