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Spatial dependence analysis

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https://www.readbyqxmd.com/read/29150760/slow-passage-through-a-hopf-bifurcation-in-excitable-nerve-cables-spatial-delays-and-spatial-memory-effects
#1
L M Bilinsky, S M Baer
It is well established that in problems featuring slow passage through a Hopf bifurcation (dynamic Hopf bifurcation) the transition to large-amplitude oscillations may not occur until the slowly changing parameter considerably exceeds the value predicted from the static Hopf bifurcation analysis (temporal delay effect), with the length of the delay depending upon the initial value of the slowly changing parameter (temporal memory effect). In this paper we introduce new delay and memory effect phenomena using both analytic (WKB method) and numerical methods...
November 17, 2017: Bulletin of Mathematical Biology
https://www.readbyqxmd.com/read/29136638/a-free-boundary-model-of-a-motile-cell-explains-turning-behavior
#2
Masoud Nickaeen, Igor L Novak, Stephanie Pulford, Aaron Rumack, Jamie Brandon, Boris M Slepchenko, Alex Mogilner
To understand shapes and movements of cells undergoing lamellipodial motility, we systematically explore minimal free-boundary models of actin-myosin contractility consisting of the force-balance and myosin transport equations. The models account for isotropic contraction proportional to myosin density, viscous stresses in the actin network, and constant-strength viscous-like adhesion. The contraction generates a spatially graded centripetal actin flow, which in turn reinforces the contraction via myosin redistribution and causes retraction of the lamellipodial boundary...
November 14, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/29136345/regional-lung-function-testing-in-children-using-electrical-impedance-tomography
#3
Barbara Vogt, Sarah Löhr, Zhanqi Zhao, Christian Falkenberg, Tobias Ankermann, Norbert Weiler, Inéz Frerichs
OBJECTIVE: To evaluate regional lung function in lung-healthy children before and after exercise challenge using electrical impedance tomography (EIT). METHODS: Regional lung function was examined using EIT in 100 lung-healthy children (three age subgroups: 74-121, 122-155, 156-195 months) at baseline and 10 min after exercise. Global lung function was assessed by spirometry using Z-Scores of FEV1 , FVC, FEV1 /FVC, and FEF75 . The same lung function measures were determined in 912 EIT image pixels to enable the spatial and temporal ventilation distribution analysis...
November 14, 2017: Pediatric Pulmonology
https://www.readbyqxmd.com/read/29135967/modifying-the-morphology-of-silicon-surfaces-by-laser-induced-liquid-assisted-colloidal-lithography
#4
Magdalena Ulmeanu, Robert L Harniman, Petko Petkov, Michael N R Ashfold
Single, or isolated small arrays of, spherical silica colloidal particles (with refractive index ncolloid = 1.47 and radius R = 350 nm or 1.5 μm) were placed on a silicon substrate and immersed in carbon tetrachloride (nliquid = 1.48) or toluene (nliquid = 1.52). Areas of the sample were then exposed to a single laser pulse (8 ps duration, wavelength λ = 355 nm), and the spatial intensity modulation of the near field in the vicinity of the particles revealed via the resulting patterning of the substrate surface...
November 14, 2017: Materials
https://www.readbyqxmd.com/read/29134961/the-impact-of-combinations-of-alcohol-nicotine-and-cannabis-on-dynamic-brain-connectivity
#5
Victor M Vergara, Barbara J Weiland, Kent Hutchison, Vince D Calhoun
Alcohol, nicotine and cannabis are among the most commonly used drugs. A prolonged and combined use of these substances can alter normal brain wiring in different ways depending on the consumed cocktail mixture. Brain connectivity alterations and their change with time can be assessed using functional magnetic resonance imaging (fMRI) because of its spatial and temporal content. Here, we estimated dynamic functional network connectivity (dFNC) as derived from fMRI data to investigate the effects of single or combined use of alcohol, nicotine and cannabis...
November 14, 2017: Neuropsychopharmacology: Official Publication of the American College of Neuropsychopharmacology
https://www.readbyqxmd.com/read/29134540/acute-connexin43-temporal-and-spatial-expression-in-response-to-ischemic-stroke
#6
Moises Freitas-Andrade, Jennifer She, John Bechberger, Christian C Naus, Wun Chey Sin
Connexin43 (Cx43) gap junctions expressed in astrocytes can significantly impact neuronal survival in stroke. However, little is known regarding Cx43 spatial and temporal expression during the initial stages of brain ischemia. Using immunohistochemistry and Western blot analysis, we examined Cx43 spatial and temporal expression as a function of neuronal injury within the first 24 h after permanent middle cerebral artery occlusion (pMCAO). Western blot analysis showed a significant increase in Cx43 protein expression in the core ischemic area at 2 and 3 h after pMCAO...
November 13, 2017: Journal of Cell Communication and Signaling
https://www.readbyqxmd.com/read/29133203/expression-and-functional-characterization-of-tachykinin-related-peptides-in-the-blood-feeding-bug-rhodnius-prolixus
#7
A N S Haddad, M S Defferrari, S Hana, S G Szeto, A B Lange
Tachykinins (tachykinin-related peptides, TRPs) are multifunctional neuropeptides that have widespread distribution in the central nervous system (CNS) and in the gastrointestinal tract of many insects, and most have been shown to stimulate contractions of visceral muscles. Invertebrate TRPs carry a characteristic conserved C-terminal pentapeptide (FXGXR-amide) and most of them share some amino acid sequence similarities (approx. 45%) with the vertebrate and mammalian tachykinin family. We have functionally characterized the tachykinins in R...
November 10, 2017: Peptides
https://www.readbyqxmd.com/read/29130901/quantification-of-fat-fraction-in-lumbar-vertebrae-correlation-with-age-and-implications-for-bone-marrow-dosimetry-in-molecular-radiotherapy
#8
Maikol Salas-Ramirez, Johannes Tran-Gia, Christian Kesenheimer, Andreas Max Weng, Aleksander Kosmala, Anke Heidemeier, Herbert Koestler, Michael Lassmann
Absorbed dose to active bone marrow is a predictor of hematological toxicity in molecular radiotherapy. Due to the complex composition of bone marrow tissue, the necessity to improve the personalized dosimetry has led to the application of non-conventional imaging methods in nuclear medicine. The aim of this study is to apply magnetic resonance imaging (MRI) for quantification of the fat fraction in lumbar vertebrae and to analyze its implications for bone marrow dosimetry. Methods First, a highly accelerated two-point Dixon MRI sequence for fat-water separation was validated in a 3T system against the magnetic resonance spectroscopy (MRS) gold standard...
November 13, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29126468/enhancing-carbohydrate-ion-yield-by-controlling-crystalline-structures-in-matrix-assisted-laser-desorption-ionization-mass-spectrometry
#9
Hsun Lee, Yin-Hung Lai, Yu-Meng Ou, Chien-Wei Tsao, Ya-Jin Jheng, Shu-Yun Kuo, Huan-Tsung Chang, Yi-Sheng Wang
Carbohydrate analysis is challenging due to lack of sensitive detection and efficient separation methods. Although matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is a sensitive tool, the low ionization efficiency of carbohydrates makes mass analyses inefficient. This work systematically examines the correlation between MALDI-MS sensitivity and carbohydrate sample morphology. Depending on the properties of the matrix used, the morphology changes through sample recrystallization after drying or imposition of hydrodynamic flows during droplet drying...
November 22, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29126093/temporal-spatial-characteristics-and-source-apportionment-of-pm2-5-as-well-as-its-associated-chemical-species-in-the-beijing-tianjin-hebei-region-of-china
#10
Jiajia Gao, Kun Wang, Yong Wang, Shuhan Liu, Chuanyong Zhu, Jiming Hao, Huanjia Liu, Shenbing Hua, Hezhong Tian
PM2.5 and its major chemical compositions were sampled and analyzed in January, April, July and October of 2014 at Beijing (BJ), Tianjin (TJ), Langfang (LF) and Baoding (BD) in order to probe the temporal and spatial characteristics as well as source apportionment of PM2.5 in the Beijing-Tianjin-Hebei (BTH) region. The results showed that PM2.5 pollution was severe in the BTH region. The average annual concentrations of PM2.5 at four sampling sites were in the range of 126-180 μg/m(3), with more than 95% of sampling days exceeding 35 μg/m(3), the limit ceiling of average annual concentration of PM2...
November 7, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/29124249/relating-coccidioidomycosis-valley-fever-incidence-to-soil-moisture-conditions
#11
E J Coopersmith, J E Bell, K Benedict, J Shriber, O McCotter, M H Cosh
Coccidioidomycosis (also called Valley fever) is caused by a soilborne fungus, Coccidioides spp., in arid regions of the southwestern United States. Though some who develop infections from this fungus remain asymptomatic, others develop respiratory disease as a consequence. Less commonly, severe illness and death can occur when the infection spreads to other regions of the body. Previous analyses have attempted to connect the incidence of coccidioidomycosis to broadly available climatic measurements, such as precipitation or temperature...
April 17, 2017: Geohealth
https://www.readbyqxmd.com/read/29123324/three-decades-of-landsat-derived-spring-surface-water-dynamics-in-an-agricultural-wetland-mosaic-implications-for-migratory-shorebirds
#12
Danica Schaffer-Smith, Jennifer J Swenson, Blake Barbaree, Matthew E Reiter
Satellite measurements of surface water offer promise for understanding wetland habitat availability at broad spatial and temporal scales; reliable habitat is crucial for the persistence of migratory shorebirds that depend on wetland networks. We analyzed water extent dynamics within wetland habitats at a globally important shorebird stopover site for a 1983-2015 Landsat time series, and evaluated the effect of climate on water extent. A range of methods can detect open water from imagery, including supervised classification approaches and thresholds for spectral bands and indices...
May 2017: Remote Sensing of Environment
https://www.readbyqxmd.com/read/29123121/the-photoelastic-coefficient-p-12-of-h-implanted-gaas-as-a-function-of-defect-density
#13
Andrey Baydin, Halina Krzyzanowska, Rustam Gatamov, Joy Garnett, Norman Tolk
The photoelastic phenomenon has been widely investigated as a fundamental elastooptical property of solids. This effect has been applied extensively to study stress distribution in lattice-mismatched semiconductor heterostructures. GaAs based optoelectronic devices (e.g. solar cells, modulators, detectors, and diodes) used in space probes are subject to damage arising from energetic proton (H(+)) irradiation. For that reason, the effect of proton irradiation on photoelastic coefficients of GaAs is of primary importance to space applied optoelectronics...
November 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29113621/assessment-of-water-physicochemical-parameters-in-the-strimtori-firiza-reservoir-in-n-w-romania
#14
(no author information available yet)
The paper assesses the surface water quality of the Firiza-Stramtori reservoir by analyzing 14 physicochemical parameters among 9 metals in 18 sampling points. A series of possible reservoir pollutants were identified,depending on the nature of the pollutants and their loading. The novelty of the paper consists in the broad spectrum of investigations which includes spatial distribution,cluster analysis and mathematical modeling. This paper presents an innovative method of assessing the distributions of the metal loads as maps of metal distribution that are in accordance with the developed mathematical models that aim to present the pollutant distribution and the degree of correlation between the physicochemical indicators...
April 6, 2017: Water Environment Research: a Research Publication of the Water Environment Federation
https://www.readbyqxmd.com/read/29110633/network-analysis-for-count-data-with-excess-zeros
#15
Hosik Choi, Jungsoo Gim, Sungho Won, You Jin Kim, Sunghoon Kwon, Changyi Park
BACKGROUND: Undirected graphical models or Markov random fields have been a popular class of models for representing conditional dependence relationships between nodes. In particular, Markov networks help us to understand complex interactions between genes in biological processes of a cell. Local Poisson models seem to be promising in modeling positive as well as negative dependencies for count data. Furthermore, when zero counts are more frequent than are expected, excess zeros should be considered in the model...
November 6, 2017: BMC Genetics
https://www.readbyqxmd.com/read/29109680/diversity-of-evoked-astrocyte-ca-2-dynamics-quantified-through-experimental-measurements-and-mathematical-modeling
#16
Marsa Taheri, Gregory Handy, Alla Borisyuk, John A White
Astrocytes are a major cell type in the mammalian brain. They are not electrically excitable, but generate prominent Ca(2+) signals related to a wide variety of critical functions. The mechanisms driving these Ca(2+) events remain incompletely understood. In this study, we integrate Ca(2+) imaging, quantitative data analysis, and mechanistic computational modeling to study the spatial and temporal heterogeneity of cortical astrocyte Ca(2+) transients evoked by focal application of ATP in mouse brain slices...
2017: Frontiers in Systems Neuroscience
https://www.readbyqxmd.com/read/29109036/the-role-of-the-p3-and-cnv-components-in-voluntary-and-automatic-temporal-orienting-a-high-spatial-resolution-erp-study
#17
Giovanni Mento
A main distinction has been proposed between voluntary and automatic mechanisms underlying temporal orienting (TO) of selective attention. Voluntary TO implies the endogenous directing of attention induced by symbolic cues. Conversely, automatic TO is exogenously instantiated by the physical properties of stimuli. A well-known example of automatic TO is sequential effects (SEs), which refer to the adjustments in participants' behavioral performance as a function of the trial-by-trial sequential distribution of the foreperiod between two stimuli...
November 9, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/29108080/-utilization-of-outpatient-emergency-care-in-westphalia-lippe-a-health-geographic-analysis
#18
Sebastian Völker
Identification of geographical variations in the utilization of outpatient emergency care facilities is the most effective tool to locate regions with the greatest potential for increasing quality and efficiency in emergency care. The aim of the study was to estimate utilization of emergency care facilities in a regression model, taking into account local dependencies and agglomeration effects. The basis of this ecological study was formed by all outpatient emergency patient contacts in 2013 (n=1,927,471), which were aggregated according to the place of residence to the 231 municipalities of the supply area of the Association of Statutory Health Insurance Physicians Westphalia-Lippe...
November 6, 2017: Das Gesundheitswesen
https://www.readbyqxmd.com/read/29107888/expected-but-omitted-stimuli-affect-crossmodal-interaction
#19
Marcello Costantini, Daniele Migliorati, Brunella Donno, Miroslav Sirota, Francesca Ferri
One of the most important ability of our brain is to integrate input from different sensory modalities to create a coherent representation of the environment. Does expectation affect such multisensory integration? In this paper, we tackled this issue by taking advantage from the crossmodal congruency effect (CCE). Participants made elevation judgments to visual target while ignoring tactile distractors. We manipulated the expectation of the tactile distractor by pairing the tactile stimulus to the index finger with a high-frequency tone and the tactile stimulus to the thumb with a low-frequency tone in 80% of the trials...
November 3, 2017: Cognition
https://www.readbyqxmd.com/read/29102198/blowing-dust-and-highway-safety-in-the-southwestern-united-states-characteristics-of-dust-emission-hotspots-and-management-implications
#20
Junran Li, Tarek Kandakji, Jeffrey A Lee, John Tatarko, John Blackwell, Thomas E Gill, Joe D Collins
Despite the widespread media attention of chain-reaction traffic incidents and property damage caused by windblown dust in the U.S. and elsewhere in the world, very few studies have provided in-depth analysis on this issue. Remote sensing and field observations reveal that wind erosion in the southwestern U.S. typically occurs in localized source areas, characterized as "hotspots", while most of the landscape is not eroding. In this study, we identified the spatial and temporal distribution patterns of hotspots that may contribute dust blowing onto highways in the southwestern U...
October 25, 2017: Science of the Total Environment
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