26 research outputs found
Enhancing task fMRI preprocessing via individualized model-based filtering of intrinsic activity dynamics
Brain responses recorded during fMRI are thought to reflect both rapid, stimulus-evoked activity and the propagation of spontaneous activity through brain networks. In the current work, we describe a method to improve the estimation of task-evoked brain activity by first filtering-out the intrinsic propagation of pre-event activity from the BOLD signal. We do so using Mesoscale Individualized NeuroDynamic (MINDy; Singh et al. 2020b) models built from individualized resting-state data to subtract the propagation of spontaneous activity from the task-fMRI signal (MINDy-based Filtering). After filtering, time-series are analyzed using conventional techniques. Results demonstrate that this simple operation significantly improves the statistical power and temporal precision of estimated group-level effects. Moreover, use of MINDy-based filtering increased the similarity of neural activation profiles and prediction accuracy of individual differences in behavior across tasks measuring the same construct (cognitive control). Thus, by subtracting the propagation of previous activity, we obtain better estimates of task-related neural effects
Direct observational evidence of the multi-scale, dynamical mass accretion toward a high-mass star forming hub-filament system
There is growing evidence that high-mass star formation and hub-filament
systems (HFS) are intricately linked. The gas kinematics along the filaments
and the forming high-mass star(s) in the central hub are in excellent agreement
with the new generation of global hierarchical high-mass star formation models.
In this paper, we present an observational investigation of a typical HFS
cloud, G310.142+0.758 (G310 hereafter) which reveals unambiguous evidence of
mass inflow from the cloud scale via the filaments onto the forming
protostar(s) at the hub conforming with the model predictions. Continuum and
molecular line data from the ATOMS and MALT90 surveys are used that cover
different spatial scales. Three filaments (with total mass ) are identified converging toward the central hub region where
several signposts of high-mass star formation have been observed. The hub
region contains a massive clump () harbouring a central
massive core. Additionally, five outflow lobes are associated with the central
massive core implying a forming cluster. The observed large-scale, smooth and
coherent velocity gradients from the cloud down to the core scale, and the
signatures of infall motion seen in the central massive clump and core, clearly
unveil a nearly-continuous, multi-scale mass accretion/transfer process at a
similar mass infall rate of over all scales,
feeding the central forming high-mass protostar(s) in the G310 HFS cloud.Comment: Accepted to publish in ApJ. 10 pages with 6 figures and 2 table
modQ: a modular EQ engine with asymmetric filter profiles
The modQ modular EQ engine pairs a novel filter topology with a highly-scalable engine framework to deliver a platform that is equally suited to precision tone-shaping as it is to processing dozens of simultaneous audio streams. The ability to create asymmetrical filter profiles eliminates the complexity associated with overlaying traditional filters while the processing framework delivers resiliency and scalability features unlike any other platform currently available, allowing customers and end users to focus on content and product delivery
In Situ Observation of Hematite Nanoparticle Aggregates Using Liquid Cell Transmission Electron Microscopy
Aggregation of nanoparticles
impacts their reactivity, stability,
transport, and fate in aqueous environments, but limited methods are
available to characterize structural features and movement of aggregates
in liquid. Here, liquid cell transmission electron microscopy (LCTEM)
was utilized to directly observe the size, morphology, and motion
of aggregates that were composed of 9 and 36 nm hematite nanoparticles,
respectively, in water or NaCl solution. When mass concentrations
were same, the aggregates of 9 nm nanoparticles were statistically
more compact and slightly larger than those of 36 nm nanoparticles.
Aggregates in both samples were typically nonspherical. Increasing
ionic strength resulted in larger aggregates, and also enhanced the
stability of aggregates under electron-beam irradiation. In water,
small aggregates moved randomly and approached repeatedly to large
aggregates before final attachment. In NaCl solution, small aggregates
moved directly toward large aggregates and attached to the latter
quickly. This observation provided a direct confirmation of the DLVO
theory that the energy barrier to aggregation is higher in water than
in salt solutions. This study not only presented the influences of
particle size and ionic strength on aggregation state, but also demonstrated
that LCTEM is a promising method to link aggregation state to dynamic
processes of nanoparticles
Enhancing the Anti-Dispersion Capability of the AO-OFDM System via a Well-Designed Optical Filter at the Transmitter
This paper proposes a novel method to improve the anti-dispersion ability of the all-optical orthogonal frequency division multiplexing (AO-OFDM) system. By replacing the Sinc-shaped filter with a Gauss-shaped filter for sub-carrier generation and inserting a cyclic prefix (CP), the impact of dispersion on the system can be significantly mitigated. Formula derivation and numerical analysis of the pulse-shaping function of the AO-OFDM system in the time domain for each cycle indicated that the pulse-shaping function generated by the Gauss-shaped filter was less affected by the dispersion effect than that of the Sinc-shaped filter. Meanwhile, less inter-carrier crosstalk between carriers was also observed. After carrying out system transmission simulations employing these two different filters, we found that the AO-OFDM system based on the Gauss-shaped filter could greatly improve the anti-dispersion ability compared with the system based on a Sinc-shaped filter. When the parameter settings in both schemes were identical, that is, the number of subcarriers was 32 and the power of a single subcarrier was −13 dBm, the bit error rate (BER) of the system based on the proposed Gauss-shaped filter after 60 km SMF transmission was only 1.596 × 10−3, while the BER of the traditional Sinc-shaped filter based system scheme was as high as 8.545 × 10−2
The Dual Mechanisms of Cognitive Control (DMCC) Project
Results Supplement for “The Dual Mechanisms of Cognitive Control (DMCC) Project” by Todd S. Braver, Alexander Kizhner, Rongxiang Tang, Michael C. Freund, and Joset A. Etze