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https://www.readbyqxmd.com/read/28099997/on-joint-estimation-of-gaussian-graphical-models-for-spatial-and-temporal-data
#1
Zhixiang Lin, Tao Wang, Can Yang, Hongyu Zhao
In this article, we first propose a Bayesian neighborhood selection method to estimate Gaussian Graphical Models (GGMs). We show the graph selection consistency of this method in the sense that the posterior probability of the true model converges to one. When there are multiple groups of data available, instead of estimating the networks independently for each group, joint estimation of the networks may utilize the shared information among groups and lead to improved estimation for each individual network...
January 18, 2017: Biometrics
https://www.readbyqxmd.com/read/28054599/estimating-risks-of-inapparent-avian-exposure-for-human-infection-avian-influenza-virus-a-h7n9-in-zhejiang-province-china
#2
Erjia Ge, Renjie Zhang, Dengkui Li, Xiaolin Wei, Xiaomeng Wang, Poh-Chin Lai
Inapparent avian exposure was suspected for the sporadic infection of avian influenza A(H7N9) occurring in China. This type of exposure is usually unnoticed and difficult to model and measure. Infected poultry with avian influenza H7N9 virus typically remains asymptomatic, which may facilitate infection through inapparent poultry/bird exposure, especially in a country with widespread practice of backyard poultry. The present study proposed a novel approach that integrated ecological and case-control methods to quantify the risk of inapparent avian exposure on human H7N9 infection...
January 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28045950/a-rough-set-bounded-spatially-constrained-asymmetric-gaussian-mixture-model-for-image-segmentation
#3
Zexuan Ji, Yubo Huang, Quansen Sun, Guo Cao, Yuhui Zheng
Accurate image segmentation is an important issue in image processing, where Gaussian mixture models play an important part and have been proven effective. However, most Gaussian mixture model (GMM) based methods suffer from one or more limitations, such as limited noise robustness, over-smoothness for segmentations, and lack of flexibility to fit data. In order to address these issues, in this paper, we propose a rough set bounded asymmetric Gaussian mixture model with spatial constraint for image segmentation...
2017: PloS One
https://www.readbyqxmd.com/read/28041980/a-family-of-locally-constrained-cca-models-for-detecting-activation-patterns-in-fmri
#4
Xiaowei Zhuang, Zhengshi Yang, Tim Curran, Richard Byrd, Rajesh Nandy, Dietmar Cordes
Canonical correlation analysis (CCA) has been used in functional Magnetic Resonance Imaging (fMRI) for improved detection of activation by incorporating time series from multiple voxels in a local neighborhood. To improve the specificity of local CCA methods, spatial constraints were previously proposed. In this study, constraints are generalized by introducing a family model of spatial constraints for CCA to further increase both sensitivity and specificity in fMRI activation detection. The proposed locally-constrained CCA (cCCA) model is formulated in terms of a multivariate constrained optimization problem and solved efficiently with numerical optimization techniques...
December 29, 2016: NeuroImage
https://www.readbyqxmd.com/read/28030651/retinal-lateral-inhibition-provides-the-biological-basis-of-long-range-spatial-induction
#5
Jihyun Yeonan-Kim, Marcelo Bertalmío
Retinal lateral inhibition is one of the conventional efficient coding mechanisms in the visual system that is produced by interneurons that pool signals over a neighborhood of presynaptic feedforward cells and send inhibitory signals back to them. Thus, the receptive-field (RF) of a retinal ganglion cell has a center-surround receptive-field (RF) profile that is classically represented as a difference-of-Gaussian (DOG) adequate for efficient spatial contrast coding. The DOG RF profile has been attributed to produce the psychophysical phenomena of brightness induction, in which the perceived brightness of an object is affected by that of its vicinity, either shifting away from it (brightness contrast) or becoming more similar to it (brightness assimilation) depending on the size of the surfaces surrounding the object...
2016: PloS One
https://www.readbyqxmd.com/read/27939095/a-multiscale-bayesian-data-integration-approach-for-mapping-air-dose-rates-around-the-fukushima-daiichi-nuclear-power-plant
#6
Haruko M Wainwright, Akiyuki Seki, Jinsong Chen, Kimiaki Saito
This paper presents a multiscale data integration method to estimate the spatial distribution of air dose rates in the regional scale around the Fukushima Daiichi Nuclear Power Plant. We integrate various types of datasets, such as ground-based walk and car surveys, and airborne surveys, all of which have different scales, resolutions, spatial coverage, and accuracy. This method is based on geostatistics to represent spatial heterogeneous structures, and also on Bayesian hierarchical models to integrate multiscale, multi-type datasets in a consistent manner...
February 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/27905976/comparative-approaches-for-assessing-access-to-alcohol-outlets-exploring-the-utility-of-a-gravity-potential-approach
#7
Tony H Grubesic, Ran Wei, Alan T Murray, William Alex Pridemore
BACKGROUND: A growing body of research recommends controlling alcohol availability to reduce harm. Various common approaches, however, provide dramatically different pictures of the physical availability of alcohol. This limits our understanding of the distribution of alcohol access, the causes and consequences of this distribution, and how best to reduce harm. The aim of this study is to introduce both a gravity potential measure of access to alcohol outlets, comparing its strengths and weaknesses to other popular approaches, and an empirically-derived taxonomy of neighborhoods based on the type of alcohol access they exhibit...
August 2, 2016: Population Health Metrics
https://www.readbyqxmd.com/read/27894026/the-effect-of-road-network-patterns-on-pedestrian-safety-a-zone-based-bayesian-spatial-modeling-approach
#8
Qiang Guo, Pengpeng Xu, Xin Pei, S C Wong, Danya Yao
Pedestrian safety is increasingly recognized as a major public health concern. Extensive safety studies have been conducted to examine the influence of multiple variables on the occurrence of pedestrian-vehicle crashes. However, the explicit relationship between pedestrian safety and road network characteristics remains unknown. This study particularly focused on the role of different road network patterns on the occurrence of crashes involving pedestrians. A global integration index via space syntax was introduced to quantify the topological structures of road networks...
November 25, 2016: Accident; Analysis and Prevention
https://www.readbyqxmd.com/read/27882869/aerotaxis-in-the-closest-relatives-of-animals
#9
Julius B Kirkegaard, Ambre Bouillant, Alan O Marron, Kyriacos C Leptos, Raymond E Goldstein
As the closest unicellular relatives of animals, choanoflagellates serve as useful model organisms for understanding the evolution of animal multicellularity. An important factor in animal evolution was the increasing ocean oxygen levels in the Precambrian, which are thought to have influenced the emergence of complex multicellular life. As a first step in addressing these conditions, we study here the response of the colony-forming choanoflagellate Salpingoeca rosetta to oxygen gradients. Using a microfluidic device that allows spatio-temporal variations in oxygen concentrations, we report the discovery that S...
November 24, 2016: ELife
https://www.readbyqxmd.com/read/27873066/diverse-foraging-opportunities-drive-the-functional-response-of-local-and-landscape-scale-bear-predation-on-pacific-salmon
#10
Thomas P Quinn, Curry J Cunningham, Aaron J Wirsing
The relationship between prey abundance and predation is often examined in single habitat units or populations, but predators may occupy landscapes with diverse habitats and foraging opportunities. The vulnerability of prey within populations may depend on habitat features that hinder predation, and increased density of conspecifics in both the immediate vicinity and the broader landscape. We evaluated the relative effects of physical habitat, local, and neighborhood prey density on predation by brown bears on sockeye salmon in a suite of 27 streams using hierarchical Bayesian functional response models...
November 21, 2016: Oecologia
https://www.readbyqxmd.com/read/27859257/does-spatial-access-to-primary-care-affect-emergency-department-utilization-for-nonemergent-conditions
#11
Jamie Fishman, Sara McLafferty, William Galanter
OBJECTIVE: To examine the contributions of individual- and neighborhood-level spatial access to care to the utilization of emergency departments (EDs) for preventable conditions through implementation of novel local spatial access measures. DATA SOURCES/STUDY SETTING: Emergency department admissions data are from four HealthLNK member hospitals in Chicago from 2007 to 2011. Primary care physician office and clinic locations were obtained from the American Medical Association and the City of Chicago...
November 17, 2016: Health Services Research
https://www.readbyqxmd.com/read/27855155/forecasting-influenza-outbreaks-in-boroughs-and-neighborhoods-of-new-york-city
#12
Wan Yang, Donald R Olson, Jeffrey Shaman
The ideal spatial scale, or granularity, at which infectious disease incidence should be monitored and forecast has been little explored. By identifying the optimal granularity for a given disease and host population, and matching surveillance and prediction efforts to this scale, response to emergent and recurrent outbreaks can be improved. Here we explore how granularity and representation of spatial structure affect influenza forecast accuracy within New York City. We develop network models at the borough and neighborhood levels, and use them in conjunction with surveillance data and a data assimilation method to forecast influenza activity...
November 2016: PLoS Computational Biology
https://www.readbyqxmd.com/read/27824500/programs-as-polypeptides
#13
Lance R Williams
Object-oriented combinator chemistry (OOCC) is an artificial chemistry with composition devices borrowed from object-oriented and functional programming languages. Actors in OOCC are embedded in space and subject to diffusion; since they are neither created nor destroyed, their mass is conserved. Actors use programs constructed from combinators to asynchronously update their own states and the states of other actors in their neighborhoods. The fact that programs and combinators are themselves reified as actors makes it possible to build programs that build programs from combinators of a few primitive types using asynchronous spatial processes that resemble chemistry as much as computation...
2016: Artificial Life
https://www.readbyqxmd.com/read/27815763/the-association-between-neighborhood-environment-and-mortality-results-from-a-national-study-of-veterans
#14
Karin Nelson, Greg Schwartz, Susan Hernandez, Joseph Simonetti, Idamay Curtis, Stephan D Fihn
BACKGROUND: As the largest integrated US health system, the Veterans Health Administration (VHA) provides unique national data to expand knowledge about the association between neighborhood socioeconomic status (NSES) and health. Although living in areas of lower NSES has been associated with higher mortality, previous studies have been limited to higher-income, less diverse populations than those who receive VHA care. OBJECTIVE: To describe the association between NSES and all-cause mortality in a national sample of veterans enrolled in VHA primary care...
November 4, 2016: Journal of General Internal Medicine
https://www.readbyqxmd.com/read/27789526/an-integrated-3-dimensional-genome-modeling-engine-for-data-driven-simulation-of-spatial-genome-organization
#15
Przemysław Szałaj, Zhonghui Tang, Paul Michalski, Michal J Pietal, Oscar J Luo, Michał Sadowski, Xingwang Li, Kamen Radew, Yijun Ruan, Dariusz Plewczynski
ChIA-PET is a high-throughput mapping technology that reveals long-range chromatin interactions and provides insights into the basic principles of spatial genome organization and gene regulation mediated by specific protein factors. Recently, we showed that a single ChIA-PET experiment provides information at all genomic scales of interest, from the high-resolution locations of binding sites and enriched chromatin interactions mediated by specific protein factors, to the low resolution of nonenriched interactions that reflect topological neighborhoods of higher-order chromosome folding...
December 2016: Genome Research
https://www.readbyqxmd.com/read/27705854/accurate-lungs-segmentation-on-ct-chest-images-by-adaptive-appearance-guided-shape-modeling
#16
Ahmed Soliman, Fahmi Khalifa, Ahmed Elnakib, Mohamed Abou El-Ghar, Neal Dunlap, Brian Wang, Georgy Gimel'farb, Robert Keynton, Ayman El-Baz
To accurately segment pathological and healthy lungs for reliable computer-aided disease diagnostics, a stack of chest CT scans is modeled as a sample of a spatially inhomogeneous joint 3D Markov-Gibbs random field (MGRF) of voxel-wise lung and chest CT image signals (intensities). The proposed learnable MGRF integrates two visual appearance sub-models with an adaptive lung shape submodel. The first-order appearance submodel accounts for both the original CT image and its Gaussian scale space (GSS) filtered version to specify local and global signal properties, respectively...
January 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/27703155/persistence-of-long-distance-insect-mediated-pollen-movement-for-a-tropical-canopy-tree-species-in-remnant-forest-patches-in-an-urban-landscape
#17
A M E Noreen, M A Niissalo, S K Y Lum, E L Webb
As deforestation and urbanization continue at rapid rates in tropical regions, urban forest patches are essential repositories of biodiversity. However, almost nothing is known about gene flow of forest-dependent tree species in urban landscapes. In this study, we investigated gene flow in the insect-pollinated, wind-dispersed tropical tree Koompassia malaccensis in and among three remnant forest patches in the urbanized landscape of Singapore. We genotyped the vast majority of adults (N=179) and a large number of recruits (N=2103) with 8 highly polymorphic microsatellite markers...
December 2016: Heredity
https://www.readbyqxmd.com/read/27701020/how-much-are-built-environments-changing-and-where-patterns-of-change-by-neighborhood-sociodemographic-characteristics-across-seven-u-s-metropolitan-areas
#18
Jana A Hirsch, Joe Grengs, Amy Schulz, Sara D Adar, Daniel A Rodriguez, Shannon J Brines, Ana V Diez Roux
Investments in neighborhood built environments could increase physical activity and overall health. Disproportionate distribution of these changes in advantaged neighborhoods could inflate health disparities. Little information exists on where changes are occurring. This paper aims to 1) identify changes in the built environment in neighborhoods and 2) investigate associations between high levels of change and sociodemographic characteristics. Using Geographic Information Systems, neighborhood land-use, local destinations (for walking, social engagement, and physical activity), and sociodemographics were characterized in 2000 and 2010 for seven U...
November 2016: Social Science & Medicine
https://www.readbyqxmd.com/read/27660649/a-modified-brain-mr-image-segmentation-and-bias-field-estimation-model-based-on-local-and-global-information
#19
Wang Cong, Jianhua Song, Kuan Luan, Hong Liang, Lei Wang, Xingcheng Ma, Jin Li
Because of the poor radio frequency coil uniformity and gradient-driven eddy currents, there is much noise and intensity inhomogeneity (bias) in brain magnetic resonance (MR) image, and it severely affects the segmentation accuracy. Better segmentation results are difficult to achieve by traditional methods; therefore, in this paper, a modified brain MR image segmentation and bias field estimation model based on local and global information is proposed. We first construct local constraints including image neighborhood information in Gaussian kernel mapping space, and then the complete regularization is established by introducing nonlocal spatial information of MR image...
2016: Computational and Mathematical Methods in Medicine
https://www.readbyqxmd.com/read/27649221/analysis-of-pollution-hazard-intensity-a-spatial-epidemiology-case-study-of-soil-pb-contamination
#20
Hoehun Ha, Peter A Rogerson, James R Olson, Daikwon Han, Ling Bian, Wanyun Shao
Heavy industrialization has resulted in the contamination of soil by metals from anthropogenic sources in Anniston, Alabama. This situation calls for increased public awareness of the soil contamination issue and better knowledge of the main factors contributing to the potential sources contaminating residential soil. The purpose of this spatial epidemiology research is to describe the effects of physical factors on the concentration of lead (Pb) in soil in Anniston AL, and to determine the socioeconomic and demographic characteristics of those residing in areas with higher soil contamination...
September 14, 2016: International Journal of Environmental Research and Public Health
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