5,906 research outputs found
Early sensitivity for eyes within faces: A new neuronal account of holistic and featural processing
The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.neuroimage.2014.04.042. © 2014. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Eyes are central to face processing however their role in early face encoding as reflected by the N170 ERP component is unclear. Using eye tracking to enforce fixation on specific facial features, we found that the N170 was larger for fixation on the eyes compared to fixation on the forehead, nasion, nose or mouth, which all yielded similar amplitudes. This eye sensitivity was seen in both upright and inverted faces and was lost in eyeless faces, demonstrating it was due to the presence of eyes at fovea. Upright eyeless faces elicited largest N170 at nose fixation. Importantly, the N170 face inversion effect (FIE) was strongly attenuated in eyeless faces when fixation was on the eyes but was less attenuated for nose fixation and was normal when fixation was on the mouth. These results suggest the impact of eye removal on the N170 FIE is a function of the angular distance between the fixated feature and the eye location. We propose the Lateral Inhibition, Face Template and Eye Detector based (LIFTED) model which accounts for all the present N170 results including the FIE and its interaction with eye removal. Although eyes elicit the largest N170 response, reflecting the activity of an eye detector, the processing of upright faces is holistic and entails an inhibitory mechanism from neurons coding parafoveal information onto neurons coding foveal information. The LIFTED model provides a neuronal account of holistic and featural processing involved in upright and inverted faces and offers precise predictions for further testing.This study was supported by grants from the Natural Sciences and Engineering Research Council of Canada (NSERC Discovery Grant #418431)the Canada Foundation for Innovation (CFI)the Ontario Research Fund (ORF)and the Canada Research Chair program to RJI
Carbon Dioxide Reduction Technology Trade Study
For long-term human missions, a closed-loop atmosphere revitalization system (ARS) is essential to minimize consumables. A carbon dioxide (CO2) reduction technology is used to reclaim oxygen (O2) from metabolic CO2 and is vital to reduce the delivery mass of metabolic O2. A key step in closing the loop for ARS will include a proper CO2 reduction subsystem that is reliable and with low equivalent system mass (ESM). Sabatier and Bosch CO2 reduction are two traditional CO2 reduction subsystems (CRS). Although a Sabatier CRS has been delivered to International Space Station (ISS) and is an important step toward closing the ISS ARS loop, it recovers only 50% of the available O2 in CO2. A Bosch CRS is able to reclaim all O2 in CO2. However, due to continuous carbon deposition on the catalyst surface, the penalties of replacing spent catalysts and reactors and crew time in a Bosch CRS are significant. Recently, technologies have been developed for recovering hydrogen (H2) from Sabatier-product methane (CH4). These include methane pyrolysis using a microwave plasma, catalytic thermal pyrolysis of CH4 and thermal pyrolysis of CH4. Further, development in Sabatier reactor designs based on microchannel and microlith technology could open up opportunities in reducing system mass and enhancing system control. Improvements in Bosch CRS conversion have also been reported. In addition, co-electrolysis of steam and CO2 is a new technology that integrates oxygen generation and CO2 reduction functions in a single system. A co-electrolysis unit followed by either a Sabatier or a carbon formation reactor based on Bosch chemistry could improve the overall competitiveness of an integrated O2 generation and CO2 reduction subsystem. This study evaluates all these CO2 reduction technologies, conducts water mass balances for required external supply of water for 1-, 5- and 10-yr missions, evaluates mass, volume, power, cooling and resupply requirements of various technologies. A system analysis and comparison among the technologies was made based on ESM, technology readiness level and reliability. Those technologies with potential were recommended for development
Atmospheric Dust Inputs, Iron Cycling, and Biogeochemical Connections in the South Pacific Ocean from Thorium Isotopes
One of the primary sources of micronutrients to the sea surface in remote ocean regions is the deposition of atmospheric dust. Geographic patterns in biogeochemical processes such as primary production and nitrogen fixation that require micronutrients like iron (Fe) are modulated in part by the spatial distribution of dust supply. Global models of dust deposition rates are poorly calibrated in the open ocean, owing to the difficulty of determining dust fluxes in sparsely sampled regions. We present new estimates of dust and Fe input rates from measurements of dissolved and particulate thorium isotopes ²³⁰Th and ²³²Th on the FS Sonne SO245 section (GEOTRACES process study GPpr09) in the South Pacific. We first discuss high‐resolution upper water column profiles of Th isotopes and the implications for the systematics of dust flux reconstructions from seawater Th measurements. We find dust fluxes in the center of the highly oligotrophic South Pacific Gyre that are the lowest of any mean annual dust input rates measured in the global oceans, but that are 1–2 orders of magnitude higher than those estimated by global dust models. We also determine dust‐borne Fe fluxes and reassess the importance of individual Fe sources to the surface South Pacific Gyre, finding that dust dissolution, not vertical or lateral diffusion, is the primary Fe source. Finally, we combine our estimates of Fe flux in dust with previously published cellular and enzymatic quotas to determine theoretical upper limits on annual average nitrogen fixation rates for a given Fe deposition rate
Atmospheric Dust Inputs, Iron Cycling, and Biogeochemical Connections in the South Pacific Ocean from Thorium Isotopes
One of the primary sources of micronutrients to the sea surface in remote ocean regions is the deposition of atmospheric dust. Geographic patterns in biogeochemical processes such as primary production and nitrogen fixation that require micronutrients like iron (Fe) are modulated in part by the spatial distribution of dust supply. Global models of dust deposition rates are poorly calibrated in the open ocean, owing to the difficulty of determining dust fluxes in sparsely sampled regions. We present new estimates of dust and Fe input rates from measurements of dissolved and particulate thorium isotopes ²³⁰Th and ²³²Th on the FS Sonne SO245 section (GEOTRACES process study GPpr09) in the South Pacific. We first discuss high‐resolution upper water column profiles of Th isotopes and the implications for the systematics of dust flux reconstructions from seawater Th measurements. We find dust fluxes in the center of the highly oligotrophic South Pacific Gyre that are the lowest of any mean annual dust input rates measured in the global oceans, but that are 1–2 orders of magnitude higher than those estimated by global dust models. We also determine dust‐borne Fe fluxes and reassess the importance of individual Fe sources to the surface South Pacific Gyre, finding that dust dissolution, not vertical or lateral diffusion, is the primary Fe source. Finally, we combine our estimates of Fe flux in dust with previously published cellular and enzymatic quotas to determine theoretical upper limits on annual average nitrogen fixation rates for a given Fe deposition rate
Topological rigidity and H_1-negative involutions on tori
We prove there is only one involution (up to conjugacy) on the n-torus which
acts as on the first homology group when is of the form
, is of the form , or is less than . In all other cases we prove
there are infinitely many such involutions up to conjugacy, but each of them
has exactly fixed points and is conjugate to a smooth involution. The key
technical point is that we completely compute the equivariant structure set for
the corresponding crystallographic group action on in terms of
the Cappell -groups arising from its infinite dihedral
subgroups. We give a complete analysis of equivariant topological rigidity for
this family of groups.Comment: 50 pages, to appear in Geometry & Topolog
Introduction of cardiotocograph monitoring improves birth outcomes in women with preeclampsia in Ghana
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135511/1/ijgo103.pd
A Chandra Study: Are Dwarf Carbon Stars Spun Up and Rejuvenated by Mass Transfer?
Carbon stars (with C/O> 1) were long assumed to all be giants, because only
AGB stars dredge up significant carbon into their atmospheres. The case is
nearly iron-clad now that the formerly mysterious dwarf carbon (dC) stars are
actually far more common than C giants, and have accreted carbon-rich material
from a former AGB companion, yielding a white dwarf and a dC star that has
gained both significant mass and angular momentum. Some such dC systems have
undergone a planetary nebula phase, and some may evolve to become CH, CEMP, or
Ba giants. Recent studies indicate that most dCs are likely from older,
metal-poor kinematic populations. Given the well-known anti-correlation of age
and activity, dCs would not be expected to show significant X-ray emission
related to coronal activity. However, accretion spin-up might be expected to
rejuvenate magnetic dynamos in these post mass-transfer binary systems. We
describe our Chandra pilot study of six dCs selected from the SDSS for Halpha
emission and/or a hot white dwarf companion, to test whether their X-ray
emission strength and spectral properties are consistent with a rejuvenated
dynamo. We detect all 6 dCs in the sample, which have X-ray luminosities
ranging from logLx= 28.5 - 29.7, preliminary evidence that dCs may be active at
a level consistent with stars that have short rotation periods of several days
or less. More definitive results require a sample of typical dCs with deeper
X-ray observations to better constrain their plasma temperatures.Comment: 13 pages, 5 figures. Revised and resubmitted June 20, accepted June
21, 2019 to Ap
A k-shell decomposition method for weighted networks
We present a generalized method for calculating the k-shell structure of
weighted networks. The method takes into account both the weight and the degree
of a network, in such a way that in the absence of weights we resume the shell
structure obtained by the classic k-shell decomposition. In the presence of
weights, we show that the method is able to partition the network in a more
refined way, without the need of any arbitrary threshold on the weight values.
Furthermore, by simulating spreading processes using the
susceptible-infectious-recovered model in four different weighted real-world
networks, we show that the weighted k-shell decomposition method ranks the
nodes more accurately, by placing nodes with higher spreading potential into
shells closer to the core. In addition, we demonstrate our new method on a real
economic network and show that the core calculated using the weighted k-shell
method is more meaningful from an economic perspective when compared with the
unweighted one.Comment: 17 pages, 6 figure
Fractal spectral triples on Kellendonk's -algebra of a substitution tiling
We introduce a new class of noncommutative spectral triples on Kellendonk's
-algebra associated with a nonperiodic substitution tiling. These spectral
triples are constructed from fractal trees on tilings, which define a geodesic
distance between any two tiles in the tiling. Since fractals typically have
infinite Euclidean length, the geodesic distance is defined using
Perron-Frobenius theory, and is self-similar with scaling factor given by the
Perron-Frobenius eigenvalue. We show that each spectral triple is
-summable, and respects the hierarchy of the substitution system. To
elucidate our results, we construct a fractal tree on the Penrose tiling, and
explicitly show how it gives rise to a collection of spectral triples.Comment: Updated to agree with published versio
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