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The Challenges of Globalization: An Interview with Ernesto Zedillo
Latin American Studie
Improving CMB non-Gaussianity estimators using tracers of local structure
Local non-Gaussianity causes correlations between large scale perturbation
modes and the small scale power. The large-scale CMB signal has contributions
from the integrated Sachs Wolfe (ISW) effect, which does not correlate with the
small scale power. If this ISW contribution can be removed, the sensitivity to
local non-Gaussianity is improved. Gravitational lensing and galaxy counts can
be used to trace the ISW contribution; in particular we show that the CMB
lensing potential is highly correlated with the ISW signal. We construct a
nearly-optimal estimator for the local non-Gaussianity parameter \fnl and
investigate to what extent we can use this to decrease the variance on
{\fnl}. We show that the variance can be decreased by up to at Planck
sensitivity using galaxy counts. CMB lensing is a good bias-independent ISW
tracer for future more sensitive observations, though the fractional decrease
in variance is small if good polarization data is also available.Comment: 8 pages, 3 figures. Comments welcom
SVM-based texture classification in optical coherence tomography
This paper describes a new method for automated texture classification for glaucoma detection using high resolution retinal Optical Coherence Tomography (OCT). OCT is a non-invasive technique that produces cross-sectional imagery of ocular tissue. Here, we exploit information from OCT im-ages, specifically the inner retinal layer thickness and speckle patterns, to detect glaucoma. The proposed method relies on support vector machines (SVM), while principal component analysis (PCA) is also employed to improve classification performance. Results show that texture features can improve classification accuracy over what is achieved using only layer thickness as existing methods currently do. Index Terms — classification, support vector machine, optical coherence tomography, texture 1
International chicken trade and increased risk for introducing or reintroducing highly pathogenic avian influenza A (H5N1) to uninfected countries.
Every year billions of chickens are shipped thousands of miles around the globe in order to meet the ever increasing demands for this cheap and nutritious protein source. Unfortunately, transporting chickens internationally can also increase the chance for introducing zoonotic viruses, such as highly pathogenic avian influenza A (H5N1) to new countries. Our study used a retrospective analysis of poultry trading data from 2003 through 2011 to assess the risk of H5N1 poultry infection in an importing country. We found that the risk of infection in an importing country increased by a factor of 1.3 (95% CI: 1.1-1.5) for every 10-fold increase in live chickens imported from countries experiencing at least one H5N1 poultry case during that year. These results suggest that the risk in a particular country can be significantly reduced if imports from countries experiencing an outbreak are decreased during the year of infection or if biosecurity measures such as screening, vaccination, and infection control practices are increased. These findings show that limiting trade of live chickens or increasing infection control practices during contagious periods may be an important step in reducing the spread of H5N1 and other emerging avian influenza viruses
A discrete invitation to quantum filtering and feedback control
The engineering and control of devices at the quantum-mechanical level--such
as those consisting of small numbers of atoms and photons--is a delicate
business. The fundamental uncertainty that is inherently present at this scale
manifests itself in the unavoidable presence of noise, making this a novel
field of application for stochastic estimation and control theory. In this
expository paper we demonstrate estimation and feedback control of quantum
mechanical systems in what is essentially a noncommutative version of the
binomial model that is popular in mathematical finance. The model is extremely
rich and allows a full development of the theory, while remaining completely
within the setting of finite-dimensional Hilbert spaces (thus avoiding the
technical complications of the continuous theory). We introduce discretized
models of an atom in interaction with the electromagnetic field, obtain
filtering equations for photon counting and homodyne detection, and solve a
stochastic control problem using dynamic programming and Lyapunov function
methods.Comment: 76 pages, 12 figures. A PDF file with high resolution figures can be
found at http://minty.caltech.edu/papers.ph
X-Chromosome Inactivation in Rett Syndrome Human Induced Pluripotent Stem Cells
Rett syndrome (RTT) is a neurodevelopmental disorder that affects girls due primarily to heterozygous mutations in the X-linked gene encoding methyl-CpG binding protein 2 (MECP2). Random X-chromosome inactivation (XCI) results in cellular mosaicism in which some cells express wild-type (WT) MECP2 while other cells express mutant MECP2. The generation of patient-specific human induced pluripotent stem cells (hiPSCs) facilitates the production of RTT-hiPSC-derived neurons in vitro to investigate disease mechanisms and identify novel drug treatments. The generation of RTT-hiPSCs has been reported by many laboratories, however, the XCI status of RTT-hiPSCs has been inconsistent. Some report RTT-hiPSCs retain the inactive X-chromosome (post-XCI) of the founder somatic cell allowing isogenic RTT-hiPSCs that express only the WT or mutant MECP2 allele to be isolated from the same patient. Post-XCI RTT-hiPSCs-derived neurons retain this allele-specific expression pattern of WT or mutant MECP2. Conversely, others report RTT-hiPSCs in which the inactive X-chromosome of the founder somatic cell reactivates (pre-XCI) upon reprogramming into RTT-hiPSCs. Pre-XCI RTT-hiPSC-derived neurons exhibit random XCI resulting in cellular mosaicism with respect to WT and mutant MECP2 expression. Here we review and attempt to interpret the inconsistencies in XCI status of RTT-hiPSCs generated to date by comparison to other pluripotent systems in vitro and in vivo and the methods used to analyze XCI. Finally, we discuss the relative strengths and weaknesses of post- and pre-XCI hiPSCs in the context of RTT, and other X-linked and autosomal disorders for translational medicine
FIRE Cirrus on October 28, 1986: LANDSAT; ER-2; King Air; theory
A simultaneous examination was conducted of cirrus clouds in the FIRE Cirrus IFO-I on 10/28/86 using a multitude of remote sensing and in-situ measurements. The focus is cirrus cloud radiative properties and their relationship to cloud microphysics. A key element is the comparison of radiative transfer model calculations and varying measured cirrus radiative properties (emissivity, reflectance vs. wavelength, reflectance vs. viewing angle). As the number of simultaneously measured cloud radiative properties and physical properties increases, more sharply focused tests of theoretical models are possible
Dissolved selenium(VI) removal by zero-valent iron under oxic conditions: Influence of sulfate and nitrate
NSERC: RGPIN-2014-06589Peer ReviewedDissolved Se(VI) removal by three commercially-available zero-valent irons (ZVIs) was examined in oxic batch experiments under circumneutral pH conditions in the presence and absence of NO3- and SO42-. Environmentally relevant Se(VI) (1 mg/L), NO3- ([NO3-N] = 15 mg/L) and SO42- (1800 mg/L) were employed to simulate mining-impacted waters. Ninety percent Se(VI) removal was achieved within 4 to 8 h in the absence of SO42- and NO3-. Similar Se(VI) removal was observed after 10 to 32 h in the presence of NO3-. Dissolved Se(VI) removal rates exhibited the greatest decrease in the presence of SO42-; 90% Se(VI) removal was measured after 50 to 191 h for SO42- and after 150 to 194 h for SO42- plus NO3- depending on the ZVI tested. Despite differences in removal rates among batches and ZVI materials, Se(VI) removal consistently followed first-order reaction kinetics. Scanning electron microscopy, Raman spectroscopy, and X-ray diffraction analyses of reacted solids showed that Fe(0) present in ZVI undergoes oxidation to magnetite [Fe3O4], wüstite [FeO], lepidocrocite [γ-FeOOH], and goethite [α-FeOOH] over time. X-ray absorption near edge structure spectroscopy indicated that Se(VI) was reduced to Se(IV) and Se(0) during removal. These results demonstrate that ZVI can be effectively used control Se(VI) concentrations in mining impacted waters
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