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Spatial dependence analysis

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https://www.readbyqxmd.com/read/28337627/biological-impacts-of-local-vs-regional-land-use-on-a-small-tributary-of-the-seine-river-france-insights-from-a-food-web-approach-based-on-stable-isotopes
#1
Nicolas Hette-Tronquart, Thierry Oberdorff, Evelyne Tales, Amandine Zahm, Jérôme Belliard
As part of the landscape, streams are influenced by land use. Here, we contributed to the understanding of the biological impacts of land use on streams, investigating how landscape effects vary with spatial scales (local vs. regional). We adopted a food web approach integrating both biological structure and functioning, to focus on the overall effect of land use on stream biocœnosis. We selected 17 sites of a small tributary of the Seine River (France) for their contrasted land use, and conducted a natural experiment by sampling three organic matter sources, three macroinvertebrate taxa, and most of the fish community...
March 23, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28337605/application-of-diet-theory-reveals-context-dependent-foraging-preferences-in-an-herbivorous-coral-reef-fish
#2
John Hanmer, J Wilson White, Joseph R Pawlik
Dietary preferences of grazers can drive spatial variability in top-down control of autotroph communities, because diet composition may depend on the relative availability of autotroph species. On Caribbean coral reefs, parrotfish grazing is important in limiting macroalgae, but parrotfish dietary preferences are poorly understood. We applied diet-switching analysis to quantify the foraging preferences of the redband parrotfish (Sparisoma aurofrenatum). At 12 Caribbean reefs, we observed 293 redband parrotfish in 5-min feeding bouts and quantified relative benthic algal cover using quadrats...
March 23, 2017: Oecologia
https://www.readbyqxmd.com/read/28336426/sar-simulations-safety
#3
Thomas M Fiedler, Mark E Ladd, Andreas K Bitz
At ultra-high fields, the assessment of radiofrequency (RF) safety presents several new challenges compared to low-field systems. Multi-channel RF transmit coils in combination with parallel transmit techniques produce time-dependent and spatially varying power loss densities in the tissue. Further, in ultra-high-field systems, localized field effects can be more pronounced due to a transition from the quasistationary to the electromagnetic field regime. Consequently, local information on the RF field is required for reliable RF safety assessment as well as for monitoring of RF exposure during MR examinations...
March 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28333648/mobile-stride-length-estimation-with-deep-convolutional-neural-networks
#4
Julius Hannink, Thomas Kautz, Cristian Pasluosta, Jens Barth, Samuel Schulein, Karl-Gunter Gassmann, Jochen Klucken, Bjoern Eskofier
OBJECTIVE: Accurate estimation of spatial gait characteristics is critical to assess motor impairments resulting from neurological or musculoskeletal disease. Currently, however, methodological constraints limit clinical applicability of state-ofthe- art double integration approaches to gait patterns with a clear zero-velocity phase. METHODS: We describe a novel approach to stride length estimation that uses deep convolutional neural networks to map stride-specific inertial sensor data to the resulting stride length...
March 9, 2017: IEEE Journal of Biomedical and Health Informatics
https://www.readbyqxmd.com/read/28333589/a-unified-theory-of-neuro-mri-data-shows-scale-free-nature-of-connectivity-modes
#5
Vitaly L Galinsky, Lawrence R Frank
A primary goal of many neuroimaging studies that use magnetic resonance imaging (MRI) is to deduce the structure-function relationships in the human brain using data from the three major neuro-MRI modalities: high-resolution anatomical, diffusion tensor imaging, and functional MRI. To date, the general procedure for analyzing these data is to combine the results derived independently from each of these modalities. In this article, we develop a new theoretical and computational approach for combining these different MRI modalities into a powerful and versatile framework that combines our recently developed methods for morphological shape analysis and segmentation, simultaneous local diffusion estimation and global tractography, and nonlinear and nongaussian spatial-temporal activation pattern classification and ranking, as well as our fast and accurate approach for nonlinear registration between modalities...
March 23, 2017: Neural Computation
https://www.readbyqxmd.com/read/28331597/pollinator-population-size-and-pollination-ecosystem-service-responses-to-enhancing-floral-and-nesting-resources
#6
Johanna Häussler, Ullrika Sahlin, Charlotte Baey, Henrik G Smith, Yann Clough
Modeling pollination ecosystem services requires a spatially explicit, process-based approach because they depend on both the behavioral responses of pollinators to the amount and spatial arrangement of habitat and on the within- and between-season dynamics of pollinator populations in response to land use. We describe a novel pollinator model predicting flower visitation rates by wild central-place foragers (e.g., nesting bees) in spatially explicit landscapes. The model goes beyond existing approaches by: (1) integrating preferential use of more rewarding floral and nesting resources; (2) considering population growth over time; (3) allowing different dispersal distances for workers and reproductives; (4) providing visitation rates for use in crop pollination models...
March 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28328503/fast-spin-echo-imaging-based-ept-with-k-space-weighting-via-t-sub-2-sub-relaxation-rept
#7
Jaewook Shin, Min-Oh Kim, Sungmin Cho, Dong-Hyun Kim
Magnetic resonance electrical property tomography (MREPT) is a technique used to extract the electrical properties of tissues (conductivity in particular) using a magnetic resonance imaging (MRI) system. In this work, we propose an improved data acquisition scheme for electrical property tomography technique by utilizing T2 modulation in fast spin echo (FSE) imaging. This technique was motivated by numerical analysis of conductivity reconstruction in the frequency domain; results reveal the spatial frequency-dependent noise texture of conventional methods...
March 17, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28328034/extraction-efficiency-and-implications-for-absolute-quantitation-of-propranolol-in-mouse-brain-liver-and-kidney-tissue-sections-using-droplet-based-liquid-microjunction-surface-sampling-high-performance-liquid-chromatography-electrospray-ionization-tandem-mass
#8
Vilmos Kertesz, Taylor M Weiskittel, Marissa Vavrek, Carol Freddo, Gary J Van Berkel
RATIONALE: Currently, the absolute quantitation aspects of droplet-based surface sampling for tissue analysis using a fully automated autosampler/high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) system have not been fully evaluated. Knowledge of extraction efficiency and its reproducibility is required to judge the potential of the method for absolute quantitation of analytes from tissue sections. METHODS: Adjacent tissue sections of propranolol-dosed mouse brain (10-μm-thick), kidney (10-μm-thick) and liver (8-, 10-, 16- and 24-μm-thick) were obtained...
July 30, 2016: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28325028/tracking-intrinsic-connectivity-brain-network-features-during-successive-pseudo-resting-states-and-interoceptive-task-fmri
#9
Behnaz Jarrahi, Dante Mantini
Advanced multivariate analyses of functional magnetic resonance imaging (fMRI) data based on blood oxygen level-dependent (BOLD) contras have revealed that the human brain organizes its activities into multiple intrinsic connectivity networks (ICNs). Several fMRI studies have evaluated the modulations of these networks during different cognitive or emotional tasks using blind source separation techniques particularly the independent component analysis (ICA). In this exploratory study, we applied ICA methodology to examine ICN modulations under different interoceptive conditions...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28325027/identifying-the-effects-of-visceral-interoception-on-human-brain-connectome-a-multivariate-analysis-of-covariance-of-fmri-data
#10
Behnaz Jarrahi, Dante Mantini
Sources of variations in the neural circuitry of the human brain and interrelationship between intrinsic connectivity networks (ICNs) are still a matter of debate and ongoing research. Here, we applied a multivariate analysis of covariance (MANCOVA) based on high-dimensional independent component analysis (ICA) to identify the effects of interoception and related variables on human brain connectome. Fifteen healthy right-handed subjects (all females, age range 21 - 48 years; mean age = 30.3, SD = 8.7 years) underwent a blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) that included continuous intravesical saline infusion and drainage...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28324222/bdnf-mrna-splice-variants-differentially-impact-ca1-and-ca3-dendrite-complexity-and-spine-morphology-in-the-hippocampus
#11
Kristen R Maynard, John W Hobbs, Mahima Sukumar, Alisha S Kardian, Dennisse V Jimenez, Robert J Schloesser, Keri Martinowich
Brain-derived neurotrophic factor (BDNF) is an activity-dependent neurotrophin critical for neuronal plasticity in the hippocampus. BDNF is encoded by multiple transcripts with alternative 5' untranslated regions (5'UTRS) that display activity-induced targeting to distinct subcellular compartments. While individual Bdnf 5'UTR transcripts influence dendrite morphology in cultured hippocampal neurons, it is unknown whether Bdnf splice variants impact dendrite arborization in functional classes of neurons in the intact hippocampus...
March 21, 2017: Brain Structure & Function
https://www.readbyqxmd.com/read/28320311/a-receptor-based-analysis-of-local-ecosystems-in-the-human-brain
#12
Skirmantas Janušonis
BACKGROUND: As a complex system, the brain is a self-organizing entity that depends on local interactions among cells. Its regions (anatomically defined nuclei and areas) can be conceptualized as cellular ecosystems, but the similarity of their functional profiles is poorly understood. The study used the Allen Human Brain Atlas to classify 169 brain regions into hierarchically-organized environments based on their expression of 100 G protein-coupled neurotransmitter receptors, with no a priori reference to the regions' positions in the brain's anatomy or function...
March 20, 2017: BMC Neuroscience
https://www.readbyqxmd.com/read/28317230/cortical-surface-based-threshold-free-cluster-enhancement-and-cortexwise-mediation
#13
Tristram A Lett, Lea Waller, Heike Tost, Ilya M Veer, Arash Nazeri, Susanne Erk, Eva J Brandl, Katrin Charlet, Anne Beck, Sabine Vollstädt-Klein, Anne Jorde, Falk Kiefer, Andreas Heinz, Andreas Meyer-Lindenberg, M Mallar Chakravarty, Henrik Walter
Threshold-free cluster enhancement (TFCE) is a sensitive means to incorporate spatial neighborhood information in neuroimaging studies without using arbitrary thresholds. The majority of methods have applied TFCE to voxelwise data. The need to understand the relationship among multiple variables and imaging modalities has become critical. We propose a new method of applying TFCE to vertexwise statistical images as well as cortexwise (either voxel- or vertexwise) mediation analysis. Here we present TFCE_mediation, a toolbox that can be used for cortexwise multiple regression analysis with TFCE, and additionally cortexwise mediation using TFCE...
March 20, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28315613/parietomotor-connectivity-in-the-contralesional-hemisphere-after-stroke-a-paired-pulse-tms-study
#14
Etienne Allart, Arnaud Delval, Alexandre Caux-Dedeystere, Julien Labreuche, Romain Viard, Renaud Lopes, Hervé Devanne
OBJECTIVES: To assess the contralesional connectivity between the posterior parietal cortex (PPC) and the motor cortex (M1) in stroke patients, and to probe putative relationships with spatial neglect and motor impairment. METHODS: In 12 right-side stroke patients and 12 age-matched healthy controls, we used paired-pulse transcranial magnetic stimulation to assess the contralesional connectivity between three left-side PPC sites (the anterior intraparietal sulcus (aIPS), the posterior intraparietal sulcus and the superior parieto-occipital cortex (SPOC)) and M1...
March 1, 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28303187/ecological-consequences-of-colony-structure-in-dynamic-ant-nest-networks
#15
Samuel Ellis, Daniel W Franks, Elva J H Robinson
Access to resources depends on an individual's position within the environment. This is particularly important to animals that invest heavily in nest construction, such as social insects. Many ant species have a polydomous nesting strategy: a single colony inhabits several spatially separated nests, often exchanging resources between the nests. Different nests in a polydomous colony potentially have differential access to resources, but the ecological consequences of this are unclear. In this study, we investigate how nest survival and budding in polydomous wood ant (Formica lugubris) colonies are affected by being part of a multi-nest system...
February 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28300198/social-contagions-on-interdependent-lattice-networks
#16
Panpan Shu, Lei Gao, Pengcheng Zhao, Wei Wang, H Eugene Stanley
Although an increasing amount of research is being done on the dynamical processes on interdependent spatial networks, knowledge of how interdependent spatial networks influence the dynamics of social contagion in them is sparse. Here we present a novel non-Markovian social contagion model on interdependent spatial networks composed of two identical two-dimensional lattices. We compare the dynamics of social contagion on networks with different fractions of dependency links and find that the density of final recovered nodes increases as the number of dependency links is increased...
March 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28300186/renal-medulla-is-more-sensitive-to-cisplatin-than-cortex-revealed-by-untargeted-mass-spectrometry-based-metabolomics-in-rats
#17
Pei Zhang, Jia-Qing Chen, Wan-Qiu Huang, Wei Li, Yin Huang, Zun-Jian Zhang, Feng-Guo Xu
Nephrotoxicity has long been the most severe and life-threatening side-effect of cisplatin, whose anticancer effect is therefore restricted. Previous pathological studies have shown that both renal cortex and medulla could be injured by cisplatin. Our TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling) assay results further uncovered that medulla subjected more severe injury than cortex. In order to depict the underlying metabolic mechanism of spatial difference in response to cisplatin, in the present study, mass spectrometry-based untargeted metabolomics approach was applied to profile renal cortex and medulla metabolites of rat after receiving a single dose of cisplatin (2...
March 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28299642/cerebromicrovascular-dysfunction-predicts-cognitive-decline-and-gait-abnormalities-in-a-mouse-model-of-whole-brain-irradiation-induced-accelerated-brain-senescence
#18
Zoltan Ungvari, Stefano Tarantini, Peter Hertelendy, M Noa Valcarcel-Ares, Gabor A Fülöp, Sreemathi Logan, Tamas Kiss, Eszter Farkas, Anna Csiszar, Andriy Yabluchanskiy
Whole brain irradiation (WBI) is a mainstream therapy for patients with both identifiable brain metastases and prophylaxis for microscopic malignancies. However, it also promotes accelerated senescence in healthy tissues and leads to progressive cognitive dysfunction in up to 50% of tumor patients surviving long term after treatment, due to γ-irradiation-induced cerebromicrovascular injury. Moment-to-moment adjustment of cerebral blood flow (CBF) via neuronal activity-dependent cerebromicrovascular dilation (functional hyperemia) has a critical role in maintenance of healthy cognitive function...
February 2017: Geroscience
https://www.readbyqxmd.com/read/28299188/genome-wide-measurement-of-spatial-expression-in-patterning-mutants-of-drosophila-melanogaster
#19
Peter A Combs, Michael B Eisen
Patterning in the Drosophila melanogaster embryo is affected by multiple maternal factors, but the effect of these factors on spatial gene expression has not been systematically analyzed. Here we characterize the effect of the maternal factors Zelda, Hunchback and Bicoid by cryosectioning wildtype and mutant blastoderm stage embryos and sequencing mRNA from each slice. The resulting atlas of spatial gene expression highlights the intersecting roles of these factors in regulating spatial patterns, and serves as a resource for researchers studying spatial patterning in the early embryo...
2017: F1000Research
https://www.readbyqxmd.com/read/28297949/criticality-and-turbulence-in-a-resistive-magnetohydrodynamic-current-sheet
#20
Alexander J Klimas, Vadim M Uritsky
Scaling properties of a two-dimensional (2d) plasma physical current-sheet simulation model involving a full set of magnetohydrodynamic (MHD) equations with current-dependent resistivity are investigated. The current sheet supports a spatial magnetic field reversal that is forced through loading of magnetic flux containing plasma at boundaries of the simulation domain. A balance is reached between loading and annihilation of the magnetic flux through reconnection at the current sheet; the transport of magnetic flux from boundaries to current sheet is realized in the form of spatiotemporal avalanches exhibiting power-law statistics of lifetimes and sizes...
February 2017: Physical Review. E
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