29 research outputs found
Comparative study of motor cortical excitability changes following anodal tDCS or highâfrequency tRNS in relation to stimulation duration
Background
In this study, we investigate the capacity of two different nonâinvasive brain stimulation (NIBS) techniques (anodal transcranial direct current stimulation (anodal tDCS) and highâfrequency transcranial random noise stimulation (hfâtRNS)) regarding the relationship between stimulation duration and their efficacy in inducing longâlasting changes in motor cortical excitability.
Methods
Fifteen healthy subjects attended six experimental sessions (90 experiments in total) and underwent both anodal tDCS of 7, 13, and 20 min duration, as well as highâfrequency 1mAâtRNS of 7, 13, and 20 min stimulation duration. Sessions were performed in a randomized order and subjects were blinded to the applied methods.
Results
For anodal tDCS, no significant stable increases of motor cortical excitability were observed for either stimulation duration. In contrast, for hf âtRNS a stimulation duration of 7 min resulted in a significant increase of motor cortical excitability lasting from 20 to 60 min poststimulation. While an intermediate duration of 13 min hfâtRNS failed to induce lasting changes in motor cortical excitability, a longer stimulation duration of 20 min hfâtRNS led only to significant increases at 50 min poststimulation which did not outlast until 60 min poststimulation.
Conclusion
HfâtRNS for a duration of 7 min induced robust increases of motor cortical excitability, suggesting an indirect proportional relationship between stimulation duration and efficacy. While hfâtRNS appeared superior to anodal tDCS in this study, further systematic and randomized experiments are necessary to evaluate the generalizability of our observations and to address current intensity as a further modifiable contributor to the variability of transcranial brain stimulation
Precise orbit determination based on COST-G time-variable gravity fields
The Combination Service for Time-variable Gravity fields (COST-G) provides monthly gravity fields, combined from the individual solutions of the COST-G analysis centers and additional partner analysis centers derived from GRACE/GRACE-FO inter-satellite GPS and K-band ranging data. The Precise Orbit Determination (POD) of Earth observation satellites in Low Earth Orbits (LEO) relies on accurate and up-to-date information on the EarthĂą?Ts gravity field and its time-variations. We study POD results of the Sentinel-2B, -3B and -6A satellites based either on the monthly COST-G combinations, available with a latency of 2-3 months, or on Fitted Signal Models (FSM) derived on the basis of the COST-G time-series of monthly gravity fields, which allow for the prediction of secular and seasonal gravity variations over several months and therefore may be used in operational LEO POD. Special focus is put on the fit interval of the FSM and the impact of episodic events, e.g. the massive ice melt in Greenland in the summer of 2019, on the performance of the gravity-predictions for POD
Soliton microcomb based spectral domain optical coherence tomography
Spectral domain optical coherence tomography (SD-OCT) is a widely used and
minimally invaive technique for bio-medical imaging [1]. SD-OCT typically
relies on the use of superluminescent diodes (SLD), which provide a low-noise
and broadband optical spectrum. Recent advances in photonic chipscale frequency
combs [2, 3] based on soliton formation in photonic integrated microresonators
provide an chipscale alternative illumination scheme for SD-OCT. Yet to date,
the use of such soliton microcombs in OCT has not yet been analyzed. Here we
explore the use of soliton microcombs in spectral domain OCT and show that, by
using photonic chipscale Si3N4 resonators in conjunction with 1300 nm pump
lasers, spectral bandwidths exceeding those of commercial SLDs are possible. We
demonstrate that the soliton states in microresonators exhibit a noise floor
that is ca. 3 dB lower than for the SLD at identical power, but can exhibit
significantly lower noise performance for powers at the milliWatt level. We
perform SD-OCT imaging on an ex vivo fixed mouse brain tissue using the soliton
microcomb, alongside an SLD for comparison, and demonstrate the principle
viability of soliton based SD-OCT. Importantly, we demonstrate that classical
amplitude noise of all soliton comb teeth are correlated, i.e. common mode, in
contrast to SLD or incoherent microcomb states [4], which should, in theory,
improve the image quality. Moreover, we demonstrate the potential for circular
ranging, i.e. optical sub-sampling [5, 6], due to the high coherence and
temporal periodicity of the soliton state. Taken together, our work indicates
the promising properties of soliton microcombs for SD-OCT
COST-G: towards a new GRACE and GRACE-FO combination
The combination service for time-variable gravity fields (COST-G) provides the full time-series of monthly GRACE gravity fields: COST-G GRACE RL01, combined in reprocessing mode, and a steadily growing time-series of monthly GRACE-FO gravity fields: COST-G GRACE-FO RL01 OP, combined on an operational basis. Both time-series are currently considered for re-combination. In case of GRACE, new high-quality time-series from Chinese analysis centers are available for combination. In case of GRACE-FO, a revision of the weighting scheme, developed in the frame of the Horizon2020 project Global Gravity-based Groundwater Product (G3P), and the availability of reprocessed GRACE-FO time-series from AIUB, CSR, GFZ, and JPL, lead to a significant improvement of the combined gravity fields. We present the preliminary re-combined GRACE and GRACE-FO time-series and quantify the differences with respect to the COST-G RL01 series in terms of signal and noise content
Two-Year Progress of Pilot Research Activities in Teaching Digital Thinking Project (TDT)
This article presents a progress report from the last two years of the Teaching Digital Thinking (TDT) project. This project aims to implement new concepts, didactic methods, and teaching formats for sustainable digital transformation in Austrian Universitiesâ curricula by introducing new digital competencies. By equipping students and teachers with 21st-century digital competencies, partner universities can contribute to solving global challenges and organizing pilot projects. In line with the overall project aims, this article presents the ongoing digital transformation activities, courses, and research in the project, which have been carried out by the five partner universities since 2020, and briefly discusses the results. This article presents a summary of the research and educational activities carried out within two parts: complementary research and pilot projects
Method for recording color images and laser direct imaging signals of object, involves generating colored images, where common complementary metal-oxide semiconductor sensor has multiple sensor elements
NOVELTY - The method involves generating colored images, where a common complementary metal-oxide semiconductor sensor (7) has multiple sensor elements. A light with different wavelengths is supplied separately for recording color images. A radiation with another wavelength is supplied separately from the light with the wave length for recording a Laser direct imaging signals of the sensor elements
The second release of COST-G GRACE-FO combined monthly gravity fields
The Combination Service for Time-variable Gravity fields (COST-G) provides monthly gravity fields of the GRACE, GRACE-FO and Swarm satellite missions, which are derived by combination of the individual time-series of the analysis centers around the world. The GRACE-FO combination has been operationalized and further developed in the frame of the Horizon 2020 project Global Gravity-based Groundwater Product (G3P). A significant reduction of noise could be achieved by the adaption of the weighting scheme, the inclusion of the new AIUB-GRACE-FO-RL02 time-series, which makes use of empirical noise modelling techniques, and the use of an alternative accelerometer transplant product, which improved the determination of the C30 gravity field coefficient, important for the derivation of ice mass change in polar regions. We present the new time-series of combined GRACE-FO monthly gravity fields and compare it in terms of signal and noise content to the original RL01 combination