P300 component identification using source analysis techniques:Reduced latency variability

P300 latency variability in normal subjects is a complicating factor in clinical event-related potential studies because it limits diagnostic applicability. The current study was conducted to determine whether identification of P300 (P3A and P3B) components using source analysis techniques can reduce variability in P300 parameters. Data were recorded with a 128-channel EEG system in 18 healthy subjects. The authors used a standard, auditory two-tone oddball paradigm with targets of 2,000 Hz and standards of 1,000 Hz. Two simple source analysis models with one or two rotating dipoles were applied to grand average data and individual data. Dipole time courses were combined with mapping results to extract P3A and P3B component latencies. Latencies obtained with conventional P300 analysis were compared with source analysis results. The source analysis method identified both P3A and P313 components in a substantially larger percentage of subjects (88% vs. 33%) than the conventional method. The source analysis method yielded a later mean P313 latency (357 msec vs. 323 msec, P <0,001) with a smaller standard deviation (9 msec vs. 23 msec, P = 0,003) than the conventional P300 method. The relative contribution of the temporally separate P3A and P313 components to the P300 complex amplitude is highly variable. This explains the larger latency standard deviation in conventional P300 analysis. The source analysis method was able to identify P300 components in a large percentage of the cases. The result is a considerable reduction of P300 latency variability in normal subjects. This could have important consequences for clinical event-related potential research, because diagnostic sensitivity and specificity of P300 latency may improve with this method

Axiotaxy in oxide heterostructures: Preferential orientation of BaCeO3 nanoparticles embedded in superconducting YBa2Cu3O7− thin films

Addressing and controlling texture in crystalline materials is an extremely important issue, since this can largely influence and finally control the materials properties, be it mechanical, electrical, magnetic, etc. In this work, we present an axiotaxial orientation of nanoparticles embedded in an epitaxial oxide heterostructure, signaling the importance of texture studies on nanocomposite thin films. Synchrotron X-ray diffraction studies revealed that embedded BaCeO3 (BCO) nanoparticles within the YBa2Cu3O7−δ (YBCO) superconductor prepared from chemical solutions presented an axiotaxial texture. Incorporated nanostructured defects such as BCO within a YBCO matrix are relevant for the fabrication of enhanced superconducting materials and devices. The YBCO presented the main out-of-plane epitaxial growth and two in-plane secondary orientations, which defined the three distinct axiotaxial axis of rotation of the BCO nanoparticles. In addition, some incorporated BCO grains showed an epitaxial growth orientation produced by a double-axiotaxy, i.e. the BCO nanoparticles exhibit a preferential orientation with respect to two distinct YBCO grains, limiting their rotational freedom. Texture studies like the ones shown here are thus a must to investigate and enhance the effect of the embedded grains on the final properties of the hybrid superconducting thin films.The research leading to these results has received funding from the FWO-Vlaanderen, BOF-UGent (GOA 01G01513) and Hercules foundation (AUGE/09/014). ICMAB also acknowledges the financial support from the Spanish Ministry of Economy and Competitiveness through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015-0496) and COACHSUPENERGY project (MAT2014-51778-C2-1-R), from the European Union for EUROTAPES project (FP7-NMP-Large-2011-280432) and from the Catalan Government (2014-SGR-753). The authors gratefully acknowledge the Synchrotron SOLEIL for allocating the beamtime. Alba Garzón-Manjon, Josep Ros and Susagna Ricart are recognized for their assistance in preparing the CeO2 nanoparticles; Pablo Cayado and Mariona Coll for helping in growing the superconducting layer.Peer reviewe