Anatomically realistic volume conductor models of the human head are important for accurate forward modeling of the electric field during transcranial brain stimulation (TBS), electro- (EEG) and ...magnetoencephalography (MEG). In particular, the skull compartment exerts a strong influence on the field distribution due to its low conductivity, suggesting the need to represent its geometry accurately. However, automatic skull reconstruction from structural magnetic resonance (MR) images is difficult, as compact bone has a very low signal in magnetic resonance imaging (MRI). Here, we evaluate three methods for skull segmentation, namely FSL BET2, the unified segmentation routine of SPM12 with extended spatial tissue priors, and the skullfinder tool of BrainSuite. To our knowledge, this study is the first to rigorously assess the accuracy of these state-of-the-art tools by comparison with CT-based skull segmentations on a group of ten subjects. We demonstrate several key factors that improve the segmentation quality, including the use of multi-contrast MRI data, the optimization of the MR sequences and the adaptation of the parameters of the segmentation methods. We conclude that FSL and SPM12 achieve better skull segmentations than BrainSuite. The former methods obtain reasonable results for the upper part of the skull when a combination of T1- and T2-weighted images is used as input. The SPM12-based results can be improved slightly further by means of simple morphological operations to fix local defects. In contrast to FSL BET2, the SPM12-based segmentation with extended spatial tissue priors and the BrainSuite-based segmentation provide coarse reconstructions of the vertebrae, enabling the construction of volume conductor models that include the neck. We exemplarily demonstrate that the extended models enable a more accurate estimation of the electric field distribution during transcranial direct current stimulation (tDCS) for montages that involve extraencephalic electrodes. The methods provided by FSL and SPM12 are integrated into pipelines for the automatic generation of realistic head models based on tetrahedral meshes, which are distributed as part of the open-source software package SimNIBS for field calculations for transcranial brain stimulation.
•Assessment of three methods for the automatic skull segmentation from MR images.•Rigorous test of their accuracy by comparison against CT data of the same subjects.•FSL and SPM12 can achieve reasonable accuracy for the upper part of the head.•A combination of T1- and T2-weighted images, rather than a single T1, is suggested.•Accuracy strongly benefits from optimization of the MRI sequence parameters.
► Direct borohydride fuel cell with Pt anode and Prussian Blue (PB)-coated Pt cathode. ► Influence of temperature and fuel (NaBH4+NaOH) and oxidant (H2O2+HCl) compositions. ► Best conditions at 55°C, ...with 1.0M NaBH4+4.0M NaOH and 5.0M H2O2+1.5M HCl. ► PB improves performance of DBFC as compared to single Pt cathode electrocatalyst. ► DBFC using PB cathode attains peak power densities up to 200mWcm−2.
Direct borohydride fuel cells (DBFCs) are receiving much attention during the last decade. Many researchers are now focused on DBFCs operating on sodium borohydride (NaBH4) as the fuel and hydrogen peroxide (H2O2) as the oxidant. In the present work, direct NaBH4/H2O2 fuel cells consisting of platinum (Pt) anodes, a Prussian Blue (PB)-coated Pt or a Pt cathode, and a Nafion N117 membrane as the separator, are assembled. The effect of different operational conditions, namely the fuel (NaBH4+NaOH) and oxidant (H2O2+HCl) compositions, as well as the operation temperature, on the performance of these DBFCs is investigated. The obtained results are evaluated and the most suitable conditions for the operation of these NaBH4/H2O2 systems are proposed. The use of the PB-coated electrode can lead to up to a 50% increase in the peak power density, as compared to the cell using a single Pt cathode. At 65°C, the DBFC using the PB-modified electrode attained over 200mWcm−2, at a cell voltage of 0.8V.
Emotional education is an outstanding place of the actual culture and social needs. Technology, emotion and change are three conceptual keys of our society of information. These are the theoretical ...referents of this report. From here emphasize emotional view as value to educate. The main goal of the paper is the research done in the outstanding of the emotional dimension (feeling), next to the perception, think, applied, persistence and social understanding as inclination of basic needs for both the students and adults interior life. We delimitate the concept and reach of the emotional education establishing some finalities, we suggest contents and describe concrete strategies such as the ORA process, the cinema, the questioning, the music in order to teacher take it to the practice.
The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the Working Group V-MOD appointed by the International Association of Geomagnetism and ...Aeronomy (IAGA). It updates the previous IGRF generation with a definitive main field model for epoch 2010.0, a main field model for epoch 2015.0, and a linear annual predictive secular variation model for 2015.0-2020.0. Here, we present the equations defining the IGRF model, provide the spherical harmonic coefficients, and provide maps of the magnetic declination, inclination, and total intensity for epoch 2015.0 and their predicted rates of change for 2015.0-2020.0. We also update the magnetic pole positions and discuss briefly the latest changes and possible future trends of the Earth’s magnetic field.
Recent research on neural and behavioral consequences of transcranial direct current stimulation (tDCS) has highlighted the impact of individual factors, such as brain anatomy which determines ...current field distribution and may thus significantly impact stimulation effects. Computational modeling approaches may significantly advance our understanding of such factors, but the association of simulation-based tDCS-induced fields and neurophysiological outcomes has not been investigated.
To provide empirical evidence for the relationship between tDCS-induced neurophysiological outcomes and individually induced electric fields.
We applied tDCS during eyes-closed resting-state functional resonance imaging (rsfMRI) and assessed pre-post magnetic resonance spectroscopy (MRS) in 24 participants. We aimed to quantify effects of 15-min tDCS using the “classical” left SM1-right supraorbital area montage on sensorimotor network (SMN) strength and gamma-aminobutyric acid (GABA) and glutamate concentrations, implementing a cross-over counterbalanced design with three stimulation conditions. Additional structural anatomical MRI sequences and recordings of individual electrode configurations allowed individual electric field simulations based on realistic head models of all participants for both conditions.
On a neurophysiological level, we observed the expected reduction of GABA concentrations and increase in SMN strength, both during anodal and cathodal compared to sham tDCS, replicating previous results. The magnitudes of neurophysiological modulations induced by tDCS were significantly associated with simulation-based electric field strengths within the targeted left precentral gyrus.
Our findings corroborate previous reports on tDCS-induced neurophysiological modulations and further advance the understanding of underlying mechanisms by providing first empirical evidence for the association of the injected electric field and neuromodulatory effects.
•GABA concentrations were reduced after anodal and cathodal compared to sham tDCS.•Functional coupling in the sensorimotor network was increased.•Neurophysiological modulations were associated with electric field strengths.
Presentación DE LA TORRE DE LA TORRE, Saturnino; NAVARRA, Joan MALLART
Revista española de pedagogía,
09/2000, Letnik:
58, Številka:
217
Journal Article
This study aims to describe the eligibility for biologic therapies for severe asthma (SA) in a cohort of patients attending the Program for Control of Asthma (ProAR) in Bahia, Brazil.
Data from SA ...patients (≥18 years old) attending the ProAR, that were included in a case-control study conducted from 2013 to 2015, were used to reassess patients according to a modified ERS/ATS 2014 SA criteria. Patients were then classified according to the eligibility for SA biological therapy based on current prescription labels.
From 544 patients in the cohort, 531 (97.6%) were included and 172 (32.4%) were identified as SA patients according to the ERS/ATS 2014 modified criteria. Of these 172 patients, 69 (40.1%) were ineligible for any of the biologicals approved for asthma (omalizumab, mepolizumab, reslizumab and benralizumab), 60 (34.9%) patients were eligible for one of the biological therapies, and 10 (5.8%) patients were eligible for all biological therapies.
More than half of patients with SA were eligible for biologic therapy in our study, but none of them received this form of treatment. Almost half of them were not eligible to any of the approved biologics, however. The variability and overlap in patients' eligibility highlight the importance of evaluating each patient individually for a more personalized treatment approach. While there is a need to increase access for some of those eligible that may really need a biologic treatment, continuous efforts are required to develop alternatives to those who are not eligible.
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