792 research outputs found
Multiscale and multimodal network dynamics underpinning working memory
Working memory (WM) allows information to be stored and manipulated over
short time scales. Performance on WM tasks is thought to be supported by the
frontoparietal system (FPS), the default mode system (DMS), and interactions
between them. Yet little is known about how these systems and their
interactions relate to individual differences in WM performance. We address
this gap in knowledge using functional MRI data acquired during the performance
of a 2-back WM task, as well as diffusion tensor imaging data collected in the
same individuals. We show that the strength of functional interactions between
the FPS and DMS during task engagement is inversely correlated with WM
performance, and that this strength is modulated by the activation of FPS
regions but not DMS regions. Next, we use a clustering algorithm to identify
two distinct subnetworks of the FPS, and find that these subnetworks display
distinguishable patterns of gene expression. Activity in one subnetwork is
positively associated with the strength of FPS-DMS functional interactions,
while activity in the second subnetwork is negatively associated. Further, the
pattern of structural linkages of these subnetworks explains their differential
capacity to influence the strength of FPS-DMS functional interactions. To
determine whether these observations could provide a mechanistic account of
large-scale neural underpinnings of WM, we build a computational model of the
system composed of coupled oscillators. Modulating the amplitude of the
subnetworks in the model causes the expected change in the strength of FPS-DMS
functional interactions, thereby offering support for a mechanism in which
subnetwork activity tunes functional interactions. Broadly, our study presents
a holistic account of how regional activity, functional interactions, and
structural linkages together support individual differences in WM in humans
Using Social Media to Promote STEM Education: Matching College Students with Role Models
STEM (Science, Technology, Engineering, and Mathematics) fields have become
increasingly central to U.S. economic competitiveness and growth. The shortage
in the STEM workforce has brought promoting STEM education upfront. The rapid
growth of social media usage provides a unique opportunity to predict users'
real-life identities and interests from online texts and photos. In this paper,
we propose an innovative approach by leveraging social media to promote STEM
education: matching Twitter college student users with diverse LinkedIn STEM
professionals using a ranking algorithm based on the similarities of their
demographics and interests. We share the belief that increasing STEM presence
in the form of introducing career role models who share similar interests and
demographics will inspire students to develop interests in STEM related fields
and emulate their models. Our evaluation on 2,000 real college students
demonstrated the accuracy of our ranking algorithm. We also design a novel
implementation that recommends matched role models to the students.Comment: 16 pages, 8 figures, accepted by ECML/PKDD 2016, Industrial Trac
Paracrine-Rescued Lobulogenesis in Chimeric Outgrowths Comprising Progesterone-Receptor-Null Mammary Epithelium and Redirected Wild-Type Testicular Cells
We have previously shown that non-mammary and tumorigenic cells can respond to the signals of the mammary niche and alter their cell fate to that of mammary epithelial progenitor cells. Here we tested the hypothesis that paracrine signals from mammary epithelial cells expressing progesterone receptor (PR) are dispensable for redirection of testicular cells, and that re-directed wild-type testicular-derived mammary cells can rescue lobulogenesis of PR-null mammary epithelium by paracrine signaling during pregnancy. We injected PR-null epithelial cells mixed with testicular cells from wild-type adult male mice into cleared fat-pads of recipient mice. The testicular cells were redirected in vivo to mammary epithelial cell fate during regeneration of the mammary epithelium, and persisted in second-generation outgrowths. In the process, the redirected testicular cells rescued the developmentally deficient PR-null cells, signaling them through the paracrine factor RANKL to produce alveolar secretory structures during pregnancy. This is the first demonstration that paracrine signaling required for alveolar development is not required for cellular reprogramming in the mammary gland, and that reprogrammed testicular cells can provide paracrine signals to the surrounding mammary epithelium
LLiST - a new star tracker camera for tip-tilt correction at IOTA
The tip-tilt correction system at the Infrared Optical Telescope Array (IOTA)
has been upgraded with a new star tracker camera. The camera features a
backside-illuminated CCD chip offering doubled overall quantum efficiency and a
four times higher system gain compared to the previous system. Tests carried
out to characterize the new system showed a higher system gain with a lower
read-out noise electron level. Shorter read-out cycle times now allow to
compensate tip-tilt fluctuations so that their error imposed on visibility
measurements becomes comparable to, and even smaller than, that of higher-order
aberrations.Comment: To be published in "New Frontiers in Stellar Interferometry", W. A.
Traub, ed., SPIE Proceedings Series, Vol. 5491, paper [5491-126]; 10 pages, 6
figures, 1 table; Latex spie class, uses packages graphicx and url; bib style
spiebib; keywords: interferometry, tip-tilt correctio
The AzTEC mm-Wavelength Camera
AzTEC is a mm-wavelength bolometric camera utilizing 144 silicon nitride
micromesh detectors. Herein we describe the AzTEC instrument architecture and
its use as an astronomical instrument. We report on several performance metrics
measured during a three month observing campaign at the James Clerk Maxwell
Telescope, and conclude with our plans for AzTEC as a facility instrument on
the Large Millimeter Telescope.Comment: 13 pages, 15 figures, accepted for publication in Monthly Notice
Evaluation of MOSFETs for entrance dose dosimetry for 6 and 10 MV photons with a custom made build up cap
Copyright © 2007 ACPSEM. All rights reserved. The dcoument attached has been archived with permission from the publisher.Commercially available MOSFETs, Thomson and Nielsen TN502-RD, were evaluated for suitability as an entrance dose in vivo dosimeter for 6MV and 10MV. Detector response was normally distributed around a mean (skewness=-0.01±0.24, kurtosis=-0.09±0.48) with a mean of 110.6 mV/Gy, with a standard deviation of 2.4% at 0.86 Gy. The standard deviation of readings increased with decreasing dose and increased at a rate greater than inverse square. The linearity coefficient was 0.9999. No significant dependence on angle, field size, dose rate, energy or time was observed. As such, they would be useful for entrance dose in vivo dosimetry. With a custom made build up cap corrections were required for field size, wedge, beam energy and tray factors, showing that build up cap design is an important consideration for entrance dose in vivo dosimetry using MOSFETs.J. P. Morton, M. Bhat, A. Kovendy and T. Williamshttp://www.acpsem.org.au/journal/abstract/abstract_3002.html#abs0
YREC: The Yale Rotating Stellar Evolution Code
The stellar evolution code YREC is outlined with emphasis on its applications
to helio- and asteroseismology. The procedure for calculating calibrated solar
and stellar models is described. Other features of the code such as a non-local
treatment of convective core overshoot, and the implementation of a
parametrized description of turbulence in stellar models, are considered in
some detail. The code has been extensively used for other astrophysical
applications, some of which are briefly mentioned at the end of the paper.Comment: 10 pages, 2 figures, ApSS accepte
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