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Spatial modeling

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https://www.readbyqxmd.com/read/28108871/quantitative-spm-analysis-involving-an-adaptive-template-may-be-easily-applied-to-18-f-fdg-pet-images-of-the-rat-brain
#1
Sylvain Poussier, Fatiha Maskali, Gaelle Vexiau, Antoine Verger, Henri Boutley, Gilles Karcher, Emmanuel Raffo, Pierre-Yves Marie
PURPOSE: The Statistical Parametric Mapping (SPM) software is frequently used for the quantitative analysis of patients' brain images obtained from 2-deoxy-2-[(18)F]fluoro-D-glucose positron emission tomography ([(18)F]FDG PET). However, its adaptation to small animals is difficult, particularly for the initial step of spatial normalization which requires a specific brain anatomical template. This study was aimed at determining whether SPM analysis can be applied to rat, and more specifically to the lithium-pilocarpine model of epilepsy, by using an adaptive template...
January 20, 2017: Molecular Imaging and Biology: MIB: the Official Publication of the Academy of Molecular Imaging
https://www.readbyqxmd.com/read/28108759/from-microhabitat-of-floral-nectar-up-to-biogeographic-scale-novel-insights-on-neutral-and-niche-bacterial-assemblies
#2
Yana Aizenberg-Gershtein, Ido Izhaki, Malka Halpern
Microbial model systems are very useful in addressing macro-ecological questions. Two major theories exist to date, to explain the community structure of organisms: (1) the dispersal (neutral) assembly theory which predicts that community similarity decreases with increasing geographic distance, independent of any environmental variables, and (2) the niche assembly theory which predicts that the communities' compositions are more homogeneous among sites characterized by similar environmental conditions. Our study system offered a unique opportunity to investigate the relative role of environmental conditions and spatial factors in shaping community composition...
January 20, 2017: Microbial Ecology
https://www.readbyqxmd.com/read/28108306/bone-remodeling-as-a-spatial-evolutionary-game
#3
Marc D Ryser, Kevin A Murgas
Bone remodeling is a complex process involving cell-cell interactions, biochemical signaling and mechanical stimuli. Early models of the biological aspects of remodeling were non-spatial and focused on the local dynamics at a fixed location in the bone. Several spatial extensions of these models have been proposed, but they generally suffer from two limitations: first, they are not amenable to analysis and are computationally expensive, and second, they neglect the role played by bone-embedded osteocytes. To address these issues, we developed a novel model of spatial remodeling based on the principles of evolutionary game theory...
January 17, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28108101/development-of-a-high-resolution-voxelised-head-phantom-for-medical-physics-applications
#4
REVIEW
V Giacometti, S Guatelli, M Bazalova-Carter, A B Rosenfeld, R W Schulte
Computational anthropomorphic phantoms have become an important investigation tool for medical imaging and dosimetry for radiotherapy and radiation protection. The development of computational phantoms with realistic anatomical features contribute significantly to the development of novel methods in medical physics. For many applications, it is desirable that such computational phantoms have a real-world physical counterpart in order to verify the obtained results. In this work, we report the development of a voxelised phantom, the HIGH_RES_HEAD, modelling a paediatric head based on the commercial phantom 715-HN (CIRS)...
January 17, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28107653/re-assessing-acalculia-distinguishing-spatial-and-purely-arithmetical-deficits-in-right-hemisphere-damaged-patients
#5
S Benavides-Varela, D Piva, F Burgio, L Passarini, G Rolma, F Meneghello, C Semenza
Arithmetical deficits in right-hemisphere damaged patients have been traditionally considered secondary to visuo-spatial impairments, although the exact relationship between the two deficits has rarely been assessed. The present study implemented a voxelwise lesion analysis among 30 right-hemisphere damaged patients and a controlled, matched-sample, cross-sectional analysis with 35 cognitively normal controls regressing three composite cognitive measures on standardized numerical measures. The results showed that patients and controls significantly differ in Number comprehension, Transcoding, and Written operations, particularly subtractions and multiplications...
December 26, 2016: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/28107629/discovery-of-1-2-3-triazole-derivatives-for-multimodality-pet-ct-cryoimaging-of-myelination-in-the-central-nervous-system
#6
Chunying Wu, Brendan Eck, Sheng Zhang, Junqing Zhu, Anand Dev Tiwari, Yifan Zhang, Yunjie Zhu, Jinming Zhang, Bin Wang, Xizhen Wang, Xu Wang, Jingqiang You, Jian Wang, Yihui Guan, Xingdang Liu, Xin Yu, Bruce D Trapp, Robert Miller, Jerry Silver, David Wilson, Yanming Wang
Myelin pathology is present in many neurological conditions such as multiple sclerosis (MS) and traumatic spinal cord injury (SCI). To facilitate development of novel therapies aimed at myelin repair, we set out to develop imaging agents that permit direct quantification of myelination in vivo. In this work, we designed and synthesized a series of fluorescent fluorinated myelin imaging agents that can be used for in vivo positron emission tomography (PET) imaging combined with subsequent post-mortem fluorescent cryoimaging...
January 20, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28107436/a-micro-ct-study-in-patients-with-breast-microcalcifications-using-a-mathematical-algorithm-to-assess-3d-structure
#7
David Kenkel, Zsuzsanna Varga, Heike Heuer, Konstantin J Dedes, Nicole Berger, Lukas Filli, Andreas Boss
PURPOSE: The aim of this study was to evaluate the relevance of the three-dimensional (3D) structure of breast microcalcifications (MC) as a predictor of malignancy using highly resolved micro-computed tomography (micro-CT) datasets of biopsy samples. MATERIAL AND METHODS: The study included 28 women with suspicious MC in their mammogram undergoing vacuum-assisted biopsy. Directly after the intervention, the specimens were scanned in a micro-CT with an isometric spatial resolution of 9 μm...
2017: PloS One
https://www.readbyqxmd.com/read/28107358/modeling-an-excitable-biosynthetic-tissue-with-inherent-variability-for-paired-computational-experimental-studies
#8
Tanmay A Gokhale, Jong M Kim, Robert D Kirkton, Nenad Bursac, Craig S Henriquez
To understand how excitable tissues give rise to arrhythmias, it is crucially necessary to understand the electrical dynamics of cells in the context of their environment. Multicellular monolayer cultures have proven useful for investigating arrhythmias and other conduction anomalies, and because of their relatively simple structure, these constructs lend themselves to paired computational studies that often help elucidate mechanisms of the observed behavior. However, tissue cultures of cardiomyocyte monolayers currently require the use of neonatal cells with ionic properties that change rapidly during development and have thus been poorly characterized and modeled to date...
January 20, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28107207/dynamic-mechanical-interactions-between-neighboring-airspaces-determine-cyclic-opening-and-closure-in-injured-lung
#9
Ludovic Broche, Gaetano Perchiazzi, Liisa Porra, Angela Tannoia, Mariangela Pellegrini, Savino Derosa, Alessandra Sindaco, João Batista Borges, Loïc Degrugilliers, Anders Larsson, Göran Hedenstierna, Anthony S Wexler, Alberto Bravin, Sylvia Verbanck, Bradford J Smith, Jason H T Bates, Sam Bayat
OBJECTIVES: Positive pressure ventilation exposes the lung to mechanical stresses that can exacerbate injury. The exact mechanism of this pathologic process remains elusive. The goal of this study was to describe recruitment/derecruitment at acinar length scales over short-time frames and test the hypothesis that mechanical interdependence between neighboring lung units determines the spatial and temporal distributions of recruitment/derecruitment, using a computational model. DESIGN: Experimental animal study...
January 19, 2017: Critical Care Medicine
https://www.readbyqxmd.com/read/28106764/effective-alternating-direction-optimization-methods-for-sparsity-constrained-blind-image-deblurring
#10
Naixue Xiong, Ryan Wen Liu, Maohan Liang, Di Wu, Zhao Liu, Huisi Wu
Single-image blind deblurring for imaging sensors in the Internet of Things (IoT) is a challenging ill-conditioned inverse problem, which requires regularization techniques to stabilize the image restoration process. The purpose is to recover the underlying blur kernel and latent sharp image from only one blurred image. Under many degraded imaging conditions, the blur kernel could be considered not only spatially sparse, but also piecewise smooth with the support of a continuous curve. By taking advantage of the hybrid sparse properties of the blur kernel, a hybrid regularization method is proposed in this paper to robustly and accurately estimate the blur kernel...
January 18, 2017: Sensors
https://www.readbyqxmd.com/read/28106559/abca1-deficiency-affects-basal-cognitive-deficits-and-dendritic-density-in-mice
#11
Nicholas F Fitz, Alexis Y Carter, Victor Tapias, Emilie L Castranio, Ravindra Kodali, Iliya Lefterov, Radosveta Koldamova
ATP-binding cassette transporter A1 (ABCA1) mediates cholesterol efflux to lipid-free apolipoproteins and regulates the generation of high density lipoproteins. Previously, we have shown that lack of Abca1 significantly increases amyloid deposition and cognitive deficits in Alzheimer's disease model mice expressing human amyloid-β protein precursor (APP). The goal of this study was to determine if ABCA1 plays a role in memory deficits caused by amyloid-β (Aβ) oligomers and examine neurite architecture of pyramidal hippocampal neurons...
January 18, 2017: Journal of Alzheimer's Disease: JAD
https://www.readbyqxmd.com/read/28106457/gravitational-waves-from-oscillons-after-inflation
#12
Stefan Antusch, Francesco Cefalà, Stefano Orani
We investigate the production of gravitational waves during preheating after inflation in the common case of field potentials that are asymmetric around the minimum. In particular, we study the impact of oscillons, comparatively long lived and spatially localized regions where a scalar field (e.g., the inflaton) oscillates with large amplitude. Contrary to a previous study, which considered a symmetric potential, we find that oscillons in asymmetric potentials associated with a phase transition can generate a pronounced peak in the spectrum of gravitational waves that largely exceeds the linear preheating spectrum...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28106430/exclusion-and-hierarchy-of-time-scales-lead-to-spatial-segregation-of-molecular-motors-in-cellular-protrusions
#13
I Pinkoviezky, N S Gov
Molecular motors that carry cargo along biopolymer filaments within cells play a crucial role in the functioning of the cell. In particular, these motors are essential for the formation and maintenance of the cellular protrusions that play key roles in motility and specific functionalities, such as the stereocilia in hair cells. Typically, there are several species of motors, carrying different cargos, that share the same track. Furthermore, it was observed that in the mature stereocilia, the different motors occupy well-segregated bands as a function of distance from the tip...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28106418/spatiotemporal-dynamics-and-reliable-computations-in-recurrent-spiking-neural-networks
#14
Ryan Pyle, Robert Rosenbaum
Randomly connected networks of excitatory and inhibitory spiking neurons provide a parsimonious model of neural variability, but are notoriously unreliable for performing computations. We show that this difficulty is overcome by incorporating the well-documented dependence of connection probability on distance. Spatially extended spiking networks exhibit symmetry-breaking bifurcations and generate spatiotemporal patterns that can be trained to perform dynamical computations under a reservoir computing framework...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28106224/polaronic-transport-in-iron-phosphate-glasses-containing-hfo2-and-ceo2
#15
Ana Šantić, Radha D Banhatti, Luka Pavić, Hüseyin Ertap, Mustafa Yüksek, Mevlüt Karabulut, Andrea Moguš-Milanković
The electrical and dielectric properties of three series of glasses, xHfO2-(40 - x)Fe2O3-60P2O5, 0 ≤ x ≤ 8 mol%, xCeO2-(40 - x)Fe2O3-60P2O5, 0 ≤ x ≤ 8 mol%, and xHfO2-(38 - x)Fe2O3-2B2O3-60P2O5 2 ≤ x ≤ 6 mol%, have been investigated by impedance spectroscopy over a wide frequency and temperature range. As expected, these glasses exhibit polaronic conductivity which strongly depends on the fraction of ferrous ions, Fe(2+)/Fetot. Following a detailed discussion on the DC conductivity, we use the MIGRATION concept to model their conductivity spectra...
January 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28106166/rapid-generation-of-hypomorphic-mutations
#16
Laura L Arthur, Joyce J Chung, Preetam Jankirama, Kathryn M Keefer, Igor Kolotilin, Slavica Pavlovic-Djuranovic, Douglas L Chalker, Vojislava Grbic, Rachel Green, Rima Menassa, Heather L True, James B Skeath, Sergej Djuranovic
Hypomorphic mutations are a valuable tool for both genetic analysis of gene function and for synthetic biology applications. However, current methods to generate hypomorphic mutations are limited to a specific organism, change gene expression unpredictably, or depend on changes in spatial-temporal expression of the targeted gene. Here we present a simple and predictable method to generate hypomorphic mutations in model organisms by targeting translation elongation. Adding consecutive adenosine nucleotides, so-called polyA tracks, to the gene coding sequence of interest will decrease translation elongation efficiency, and in all tested cell cultures and model organisms, this decreases mRNA stability and protein expression...
January 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28106139/spatio-temporal-tolerance-of-visuo-tactile-illusions-in-artificial-skin-by-recurrent-neural-network-with-spike-timing-dependent-plasticity
#17
Alexandre Pitti, Ganna Pugach, Philippe Gaussier, Sotaro Shimada
Perceptual illusions across multiple modalities, such as the rubber-hand illusion, show how dynamic the brain is at adapting its body image and at determining what is part of it (the self) and what is not (others). Several research studies showed that redundancy and contingency among sensory signals are essential for perception of the illusion and that a lag of 200-300 ms is the critical limit of the brain to represent one's own body. In an experimental setup with an artificial skin, we replicate the visuo-tactile illusion within artificial neural networks...
January 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28105805/towards-3d-chemical-imaging-of-ternary-cu-sn-pb-alloys-using-femtosecond-laser-ablation-ionization-mass-spectrometry
#18
Valentine Grimaudo, Pavel Moreno-Garcia, Andreas Riedo, Stefan Meyer, Marek Tulej, Maike Brigitte Neuland, Miklós Mohos, Christoph Gütz, Siegfried R R Waldvogel, Peter Wurz, Peter Broekmann
Femtosecond Laser Ablation/Ionization Mass Spectrometry (LIMS) has been applied to probe the spatial element composition of three ternary Cu-Sn-Pb model bronze alloys (lead bronzes: CuSn10Pb10, CuSn7Pb15 and CuSn5Pb20), which were recently identified as high performance cathode materials in the context of electro-organic synthesis (dehalogenation, deoxygenation) of pharmaceutically relevant building blocks. The quantitative and spatially resolved element analysis of such cathode materials will help understanding the observed profound differences in their electrochemical reactivity and stability...
January 4, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28104085/direct-current-stimulation-modulates-ltp-and-ltd-activity-dependence-and-dendritic-effects
#19
Greg Kronberg, Morgan Bridi, Ted Abel, Marom Bikson, Lucas C Parra
BACKGROUND: Transcranial direct current stimulation (tDCS) has been reported to improve various forms of learning in humans. Stimulation is often applied during training, producing lasting enhancements that are specific to the learned task. These learning effects are thought to be mediated by altered synaptic plasticity. However, the effects of DCS during the induction of endogenous synaptic plasticity remain largely unexplored. OBJECTIVE/HYPOTHESIS: Here we are interested in the effects of DCS applied during synaptic plasticity induction...
January 2017: Brain Stimulation
https://www.readbyqxmd.com/read/28103552/extending-the-utility-of-the-parabolic-approximation-in-medical-ultrasound-using-wide-angle-diffraction-modeling
#20
Joshua E Soneson
Wide-angle parabolic models are commonly used in geophysics and underwater acoustics but have seen little application in medical ultrasound. Here a wide-angle model for continuous-wave high-intensity ultrasound beams is derived which approximates the diffraction process more accurately than the commonly-used Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation without increasing implementation complexity or computing time. A method for preventing the high spatial frequencies often present in source boundary conditions from corrupting the solution is presented...
January 16, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
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