87 research outputs found
Border forces and friction control epithelial closure dynamics
Epithelization, the process whereby an epithelium covers a cell-free surface,
is not only central to wound healing but also pivotal in embryonic
morphogenesis, regeneration, and cancer. In the context of wound healing, the
epithelization mechanisms differ depending on the sizes and geometries of the
wounds as well as on the cell type while a unified theoretical decription is
still lacking. Here, we used a barrier-based protocol that allows for making
large arrays of well-controlled circular model wounds within an epithelium at
confluence, without injuring any cells. We propose a physical model that takes
into account border forces, friction with the substrate, and tissue rheology.
Despite the presence of a contractile actomyosin cable at the periphery of the
wound, epithelization was mostly driven by border protrusive activity. Closure
dynamics was quantified by an epithelization coefficient
defined as the ratio of the border protrusive stress to the friction
coefficient between epithelium and substrate. The same assay and model
showed a high sensitivity to the RasV12 mutation on human epithelial cells,
demonstrating the general applicability of the approach and its potential to
quantitatively characterize metastatic transformations.Comment: 44 pages, 17 figure
Cosmic Acceleration from Causal Backreaction with Recursive Nonlinearities
We revisit the causal backreaction paradigm, in which the need for Dark
Energy is eliminated via the generation of an apparent cosmic acceleration from
the causal flow of inhomogeneity information coming in towards each observer
from distant structure-forming regions. This second-generation formalism
incorporates "recursive nonlinearities": the process by which
already-established metric perturbations will then act to slow down all future
flows of inhomogeneity information. Here, the long-range effects of causal
backreaction are now damped, weakening its impact for models that were
previously best-fit cosmologies. Nevertheless, we find that causal backreaction
can be recovered as a replacement for Dark Energy via the adoption of larger
values for the dimensionless `strength' of the clustering evolution functions
being modeled -- a change justified by the hierarchical nature of clustering
and virialization in the universe, occurring on multiple cosmic length scales
simultaneously. With this, and with one new model parameter representing the
slowdown of clustering due to astrophysical feedback processes, an alternative
cosmic concordance can once again be achieved for a matter-only universe in
which the apparent acceleration is generated entirely by causal backreaction
effects. One drawback is a new degeneracy which broadens our predicted range
for the observed jerk parameter , thus removing what had
appeared to be a clear signature for distinguishing causal backreaction from
Cosmological Constant CDM. As for the long-term fate of the universe,
incorporating recursive nonlinearities appears to make the possibility of an
`eternal' acceleration due to causal backreaction far less likely; though this
does not take into account gravitational nonlinearities or the large-scale
breakdown of cosmological isotropy, effects not easily modeled within this
formalism.Comment: 53 pages, 7 figures, 3 tables. This paper is an advancement of
previous research on Causal Backreaction; the earlier work is available at
arXiv:1109.4686 and arXiv:1109.515
Evidence for Unresolved Gamma-Ray Point Sources in the Inner Galaxy
We present a new method to characterize unresolved point sources (PSs),
generalizing traditional template fits to account for non-Poissonian photon
statistics. We apply this method to Fermi Large Area Telescope gamma-ray data
to characterize PS populations at high latitudes and in the Inner Galaxy. We
find that PSs (resolved and unresolved) account for ~50% of the total
extragalactic gamma-ray background in the energy range ~1.9 to 11.9 GeV. Within
10 of the Galactic Center with , we find that ~5-10%
of the flux can be accounted for by a population of unresolved PSs, distributed
consistently with the observed ~GeV gamma-ray excess in this region. The excess
is fully absorbed by such a population, in preference to dark-matter
annihilation. The inferred source population is dominated by near-threshold
sources, which may be detectable in future searches.Comment: 7+22 pages, 4+18 figures; v2, minor changes, new Pass 8 data analyzed
(conclusions unchanged); v3, PRL version, substantive improvements and
additional checks (conclusion unchanged
Best Practices and Recommendations for Crowdsourced QoE - Lessons learned from the Qualinet Task Force Crowdsourcing
Crowdsourcing is a popular approach that outsources tasks via the Internet to a large number of users. Commercial crowdsourcing platforms provide a global pool of users employed for performing short and simple online tasks. For quality assessment of multimedia services and applications, crowdsourcing enables new possibilities by moving the subjective test into the crowd resulting in larger diversity of the test subjects, faster turnover of test campaigns, and reduced costs due to low reimbursement costs of the participants. Further, crowdsourcing allows easily addressing additional features like real-life environments. This white paper summarizes the recommendations and best practices for crowdsourced quality assessment of multimedia applications from the Qualinet Task Force on âCrowdsourcingâ. The European Network on Quality of Experience in Multimedia Systems and Services Qualinet (COST Action IC 1003, see www.qualinet.eu) established this task force in 2012 which has more than 30 members. The recommendation paper resulted from the experience in designing, implementing, and conducting crowdsourcing experiments as well as the analysis of the crowdsourced user ratings and context data
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Going Viral During a Pandemic: Civil Society and Social Media in Kazakhstan
The covid-19 pandemic forged a more intensely digital world, complicating civil society actorsâ menu of options for channeling and framing their advocacy goals. As both a product and study of pandemic-era politics, this dissertation is concerned with understanding how the internet and social media shape associational life in Kazakhstan. I draw on three forms of ethnographic data collected online between October 2020 and February 2022, including semi-structured interviews, visual analysis of social media posts, and digital participant observation.
I demonstrate how Kazakhstani civil society actors devise strategies to pursue reform, how they debate theories of political change, and how they exercise agency in a political system that seeks to control the public sphere. I argue that civil society groups use social media platforms to leverage power differentials across levels of administration to advance rights claims and negotiate for reform. Activists and rights defenders flock to various social media platforms because of each siteâs unique technological infrastructure. They leverage different logics of visibility and bridge physical and digital forms of contentious politics to demand accountability from an authoritarian government.
In addition to providing a more complete understanding of civil society dynamics in Kazakhstan, this study suggests that, in repressive contexts, civil society actors who opt for within-system engagement have not necessarily been coopted and activists do not always take dissent underground. This dissertation is an example of digital political ethnography, which stands to grow not only as a standalone method, but also a bridge to big data analysis in political science. I demonstrate the importance of an ethnographic sensibility while approaching the internet as a site of inquiry to understand political subjectivity
A Proposal for a Three Detector Short-Baseline Neutrino Oscillation Program in the Fermilab Booster Neutrino Beam
A Short-Baseline Neutrino (SBN) physics program of three LAr-TPC detectors
located along the Booster Neutrino Beam (BNB) at Fermilab is presented. This
new SBN Program will deliver a rich and compelling physics opportunity,
including the ability to resolve a class of experimental anomalies in neutrino
physics and to perform the most sensitive search to date for sterile neutrinos
at the eV mass-scale through both appearance and disappearance oscillation
channels. Using data sets of 6.6e20 protons on target (P.O.T.) in the LAr1-ND
and ICARUS T600 detectors plus 13.2e20 P.O.T. in the MicroBooNE detector, we
estimate that a search for muon neutrino to electron neutrino appearance can be
performed with ~5 sigma sensitivity for the LSND allowed (99% C.L.) parameter
region. In this proposal for the SBN Program, we describe the physics analysis,
the conceptual design of the LAr1-ND detector, the design and refurbishment of
the T600 detector, the necessary infrastructure required to execute the
program, and a possible reconfiguration of the BNB target and horn system to
improve its performance for oscillation searches.Comment: 209 pages, 129 figure
BCRâs CDP Digital Imaging Best Practices, Version 2.0
This is the published version.These Best Practices â also referred to as the CDP Best Practices -- have been created through the collaboration of working groups pulled from library, museum and archive practitioners. Version 1 was created through funding from the Institute for Museum and Library Services through a grant to the University of Denver and the Colorado Digitization Program in 2003. Version 2 of the guidelines were published by BCR in 2008 and represents a significant update of practices under the leadership of their CDP Digital Imaging Best Practices Working Group.
The intent has been to help standardize and share protocols governing the implementation of digital projects. The result of these collaborations is a set of best practice documents that cover issues such as digital imaging, Dublin Core metadata and digital audio. These best practice documents are intended to help with the design and implementation of digitization projects. Because they were collaboratively designed by experts in the field, you can be certain they include the best possible information, in addition to having been field tested and proven in practice. These best practice documents are an ongoing collaborative project, and LYRASIS will add information and new documents as they are developed
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The E and B EXperiment: A balloon-borne cosmic microwave background anisotropy probe
The E and B Experiment (EBEX), is a balloon-borne sub-orbital cosmic microwave background polarimeter, designed to measure polarization levels in the microwave spectrum. EBEX recently completed an 11-day Antarctic long duration balloon (LDB) science flight in January, 2013. ~1000 transition edge sensor bolometric detectors in three frequency bands centered at 150, 250 and 410 GHz sampled a large segment of the southern sky. Over 1.5TB of data were collected during the LDB flight. In this thesis, we describe the design and performance of the EBEX software components monitoring and controlling the system during the flight, including automation, telemetry, data storage and readout array management. We also describe the design and development of a novel attitude reconstruction system for a balloon-borne pointed observation platform based on a daytime star camera and 3-axis gyroscopes. The data gathered during the LDB flight are analyzed and the results presented showing attitude reconstruction error at less than 20" RMS for an 80 second interval
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