keyword
MENU ▼
Read by QxMD icon Read
search

Dynamic linear model

keyword
https://www.readbyqxmd.com/read/29166106/nodeless-vibrational-amplitudes-and-quantum-nonadiabatic-dynamics-in-the-nested-funnel-for-a-pseudo-jahn-teller-molecule-or-homodimer
#1
William K Peters, Vivek Tiwari, David M Jonas
The nonadiabatic states and dynamics are investigated for a linear vibronic coupling Hamiltonian with a static electronic splitting and weak off-diagonal Jahn-Teller coupling through a single vibration with a vibrational-electronic resonance. With a transformation of the electronic basis, this Hamiltonian is also applicable to the anti-correlated vibration in a symmetric homodimer with marginally strong constant off-diagonal coupling, where the non-adiabatic states and dynamics model electronic excitation energy transfer or self-exchange electron transfer...
November 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29166039/segmental-dynamics-of-polyethylene-alt-propylene-studied-by-nmr-spin-echo-techniques
#2
A Lozovoi, C Mattea, M Hofmann, K Saalwaechter, N Fatkullin, S Stapf
Segmental dynamics of a highly entangled melt of linear polyethylene-alt-propylene with a molecular weight of 200 kDa was studied with a novel proton nuclear magnetic resonance (NMR) approach based upon (1)H → (2)H isotope dilution as applied to a solid-echo build-up function I(SE)(t), which is constructed from the NMR spin echo signals arising from the Hahn echo (HE) and two variations of the solid-echo pulse sequence. The isotope dilution enables the separation of inter- and intramolecular contributions to this function and allows one to extract the segmental mean-squared displacements in the millisecond time range, which is hardly accessible by other experimental methods...
June 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29165995/magnetic-particle-imaging-for-highly-sensitive-quantitative-and-safe-in-vivo-gut-bleed-detection-in-a-murine-model
#3
Elaine Y Yu, Prashant Chandrasekharan, Ran Berzon, Zhi Wei Tay, Xinyi Y Zhou, Amit P Khandhar, R Matthew Ferguson, Scott J Kemp, Bo Zheng, Patrick W Goodwill, Michael F Wendland, Kannan M Krishnan, Spencer Behr, Jonathan Carter, Steven M Conolly
Gastrointestinal (GI) bleeding causes more than 300,000 hospitalizations per year in the United States. Imaging plays a crucial role in accurately locating the source of the bleed for timely intervention. Magnetic Particle Imaging (MPI) is an emerging clinically translatable imaging modality that images superparamagnetic iron-oxide (SPIO) tracers with extraordinary contrast and sensitivity. This linearly quantitative modality has zero background tissue signal and zero signal depth attenuation. MPI is also safe: there is zero ionizing radiation exposure to the patient and clinically approved tracers can be used with MPI...
November 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/29163572/root-and-rhizosphere-bacterial-phosphatase-activity-varies-with-tree-species-and-soil-phosphorus-availability-in-puerto-rico-tropical-forest
#4
Kristine G Cabugao, Collin M Timm, Alyssa A Carrell, Joanne Childs, Tse-Yuan S Lu, Dale A Pelletier, David J Weston, Richard J Norby
Tropical forests generally occur on highly weathered soils that, in combination with the immobility of phosphorus (P), often result in soils lacking orthophosphate, the form of P most easily metabolized by plants and microbes. In these soils, mineralization of organic P can be the major source for orthophosphate. Both plants and microbes encode for phosphatases capable of mineralizing a range of organic P compounds. However, the activity of these enzymes depends on several edaphic factors including P availability, tree species, and microbial communities...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/29161866/a-mathematical-model-of-stem-cell-regeneration-with-epigenetic-state-transitions
#5
Qiaojun Situ, Jinzhi Lei
In this paper, we study a mathematical model of stem cell regeneration with epigenetic state transitions. In the model, the heterogeneity of stem cells is considered through the epigenetic state of each cell, and each epigenetic state defines a subpopulation of stem cells. The dynamics of the subpopulations are modeled by a set of ordinary differential equations in which epigenetic state transition in cell division is given by the transition probability. We present analysis for the existence and linear stability of the equilibrium state...
October 2017: Mathematical Biosciences and Engineering: MBE
https://www.readbyqxmd.com/read/29159598/etox-allies-an-automated-pipeline-for-linear-interaction-energy-based-simulations
#6
Luigi Capoferri, Marc van Dijk, Ariën S Rustenburg, Tsjerk A Wassenaar, Derk P Kooi, Eko A Rifai, Nico P E Vermeulen, Daan P Geerke
BACKGROUND: Computational methods to predict binding affinities of small ligands toward relevant biological (off-)targets are helpful in prioritizing the screening and synthesis of new drug candidates, thereby speeding up the drug discovery process. However, use of ligand-based approaches can lead to erroneous predictions when structural and dynamic features of the target substantially affect ligand binding. Free energy methods for affinity computation can include steric and electrostatic protein-ligand interactions, solvent effects, and thermal fluctuations, but often they are computationally demanding and require a high level of supervision...
November 21, 2017: Journal of Cheminformatics
https://www.readbyqxmd.com/read/29157746/particle-filter-based-target-tracking-algorithm-for-magnetic-resonance-guided-respiratory-compensation-robustness-and-accuracy-assessment
#7
Alexandra E Bourque, Stéphane Bedwani, Jean-François Carrier, Cynthia Ménard, Pim Borman, Clemens Bos, Bas W Raaymakers, Nikolai Mickevicius, Eric Paulson, Rob H N Tijssen
PURPOSE: To assess overall robustness and accuracy of a modified particle filter-based tracking algorithm for magnetic resonance (MR)-guided radiation therapy treatments. METHODS AND MATERIALS: An improved particle filter-based tracking algorithm was implemented, which used a normalized cross-correlation function as the likelihood calculation. With a total of 5 healthy volunteers and 8 patients, the robustness of the algorithm was tested on 24 dynamic magnetic resonance imaging (MRI) time series with varying resolution, contrast, and signal-to-noise ratio...
October 12, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/29156149/quantitative-evaluation-of-vertebral-microvascular-permeability-and-fat-fraction-in-alloxan-induced-diabetic-rabbits
#8
Lei Hu, Yun Fei Zha, Li Wang, Liang Li, Dong Xing, Wei Gong, Jiao Wang, Yuan Lin, Fei Fei Zeng, Xue Song Lu
Purpose To determine longitudinal relationships between lumbar vertebral bone marrow permeability and marrow adipose tissue in a rabbit diabetes model by using quantitative dynamic contrast agent-enhanced (DCE) magnetic resonance (MR) imaging and iterative decomposition of water and fat with the echo asymmetry and least-squares estimation quantitation (IDEAL IQ) sequence. Materials and Methods Twenty rabbits were randomly assigned to the diabetic (n = 10) or control (n = 10) group. All rabbits underwent sagittal MR imaging of the lumbar region at fixed time points (0, 4, 8, 12, and 16 weeks after alloxan injection)...
November 20, 2017: Radiology
https://www.readbyqxmd.com/read/29156088/climate-mediated-changes-in-marine-ecosystem-regulation-during-el-ni%C3%A3-o
#9
Martin Lindegren, David M Checkley, J Anthony Koslow, Ralf Goericke, Mark D Ohman
The degree to which ecosystems are regulated through bottom-up, top-down or direct physical processes represents a long-standing issue in ecology, with important consequences for resource management and conservation. In marine ecosystems, the role of bottom-up and top-down forcing has been shown to vary over spatio-temporal scales, often linked to highly variable and heterogeneously distributed environmental conditions. Ecosystem dynamics in the Northeast Pacific have been suggested to be predominately bottom-up regulated...
November 20, 2017: Global Change Biology
https://www.readbyqxmd.com/read/29155811/an-efficient-moments-based-inference-method-for-within-host-bacterial-infection-dynamics
#10
David J Price, Alexandre Breuzé, Richard Dybowski, Piero Mastroeni, Olivier Restif
Over the last ten years, isogenic tagging (IT) has revolutionised the study of bacterial infection dynamics in laboratory animal models. However, quantitative analysis of IT data has been hindered by the piecemeal development of relevant statistical models. The most promising approach relies on stochastic Markovian models of bacterial population dynamics within and among organs. Here we present an efficient numerical method to fit such stochastic dynamic models to in vivo experimental IT data. A common approach to statistical inference with stochastic dynamic models relies on producing large numbers of simulations, but this remains a slow and inefficient method for all but simple problems, especially when tracking bacteria in multiple locations simultaneously...
November 20, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/29155024/linearization-improves-the-repeatability-of-quantitative-dynamic-contrast-enhanced-mri
#11
Kyle M Jones, Mark D Pagel, Julio Cárdenas-Rodríguez
PURPOSE: The purpose of this study was to compare the repeatabilities of the linear and nonlinear Tofts and reference region models (RRM) for dynamic contrast-enhanced MRI (DCE-MRI). MATERIALS AND METHODS: Simulated and experimental DCE-MRI data from 12 rats with a flank tumor of C6 glioma acquired over three consecutive days were analyzed using four quantitative and semi-quantitative DCE-MRI metrics. The quantitative methods used were: 1) linear Tofts model (LTM), 2) non-linear Tofts model (NTM), 3) linear RRM (LRRM), and 4) non-linear RRM (NRRM)...
November 15, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/29152994/decreased-connectivity-and-increased-bold-complexity-in-the-default-mode-network-in-individuals-with-chronic-fatigue-syndrome
#12
Zack Y Shan, Kevin Finegan, Sandeep Bhuta, Timothy Ireland, Donald R Staines, Sonya M Marshall-Gradisnik, Leighton R Barnden
The chronic fatigue syndrome / myalgic encephalomyelitis (CFS) is a debilitating disease with unknown pathophysiology and no diagnostic test. This study investigated the default mode network (DMN) in order to understand the pathophysiology of CFS and to identify potential biomarkers. Using functional MRI (fMRI) collected from 72 subjects (45 CFS and 27 controls) with a temporal resolution of 0.798s, we evaluated the default mode network using static functional connectivity (FC), dynamic functional connectivity (DFC) and DFC complexity, blood oxygenation level dependent (BOLD) activation maps and complexity of activity...
November 20, 2017: Brain Connectivity
https://www.readbyqxmd.com/read/29152178/the-genetics-of-phenotypic-plasticity-xv-genetic-assimilation-the-baldwin-effect-and-evolutionary-rescue
#13
Samuel M Scheiner, Michael Barfield, Robert D Holt
We used an individual-based simulation model to examine the role of phenotypic plasticity on persistence and adaptation to two patterns of environmental variation, a single, abrupt step change and continual, linear change. Our model tested the assumptions and predictions of the theory of genetic assimilation, explored the evolutionary dynamics of the Baldwin effect, and provided expectations for the evolutionary response to climate change. We found that genetic assimilation as originally postulated is not likely to occur because the replacement of plasticity by fixed genetic effects takes much longer than the environment is likely to remain stable...
November 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/29150759/from-experiment-to-theory-what-can-we-learn-from-growth-curves
#14
Irina Kareva, Georgy Karev
Finding an appropriate functional form to describe population growth based on key properties of a described system allows making justified predictions about future population development. This information can be of vital importance in all areas of research, ranging from cell growth to global demography. Here, we use this connection between theory and observation to pose the following question: what can we infer about intrinsic properties of a population (i.e., degree of heterogeneity, or dependence on external resources) based on which growth function best fits its growth dynamics? We investigate several nonstandard classes of multi-phase growth curves that capture different stages of population growth; these models include hyperbolic-exponential, exponential-linear, exponential-linear-saturation growth patterns...
November 17, 2017: Bulletin of Mathematical Biology
https://www.readbyqxmd.com/read/29150622/evidence-of-quantum-phase-transition-in-real-space-vacuum-entanglement-of-higher-derivative-scalar-quantum-field-theories
#15
S Santhosh Kumar, S Shankaranarayanan
In a bipartite set-up, the vacuum state of a free Bosonic scalar field is entangled in real space and satisfies the area-law- entanglement entropy scales linearly with area of the boundary between the two partitions. In this work, we show that the area law is violated in two spatial dimensional model Hamiltonian having dynamical critical exponent z = 3. The model physically corresponds to next-to-next-to-next nearest neighbour coupling terms on a lattice. The result reported here is the first of its kind of violation of area law in Bosonic systems in higher dimensions and signals the evidence of a quantum phase transition...
November 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29149869/characterisation-of-sucking-dynamics-of-breastfeeding-preterm-infants-a-cross-sectional-study
#16
Donna T Geddes, Kok Chooi, Kathryn Nancarrow, Anna R Hepworth, Hazel Gardner, Karen Simmer
BACKGROUND: Full breastfeeding is the ultimate aim for preterm infants to ensure they receive the full benefits of human milk however, preterm infants face a number of challenges associated with their immaturity and associated morbidities. In order to facilitate oral feeding, it is essential to have a sound knowledge of the sucking dynamics of the breastfed infant. The aim of this study was to measure and describe the sucking dynamics of the preterm breastfeeding infant. METHODS: A prospective cross sectional observational study was carried out at King Edward Memorial Hospital, Perth...
November 17, 2017: BMC Pregnancy and Childbirth
https://www.readbyqxmd.com/read/29148964/twenty-five-years-of-the-binary-power-law-for-characterizing-heterogeneity-of-disease-incidence
#17
Laurence V Madden, Gareth Hughes, Wanderson Bucker Moraes, Xiangming Xu, William W Turechek
Spatial pattern, an important epidemiological property of plant diseases, can be quantified at different scales using a range of methods. The spatial heterogeneity (or overdispersion) of disease incidence among sampling units is an especially important measure of small-scale pattern. As an alternative to Taylor's power law for the heterogeneity of counts with no upper bound, the binary power law (BPL) was proposed in 1992 as a model to represent the heterogeneity of disease incidence (number of plant units diseased out of n observed in each sampling unit, or the proportion diseased in each sampling unit)...
November 17, 2017: Phytopathology
https://www.readbyqxmd.com/read/29148556/co2-adsorption-on-anatase-tio2-101-surfaces-a-combination-of-uhv-ftirs-and-first-principles-studies
#18
Yunjun Cao, Min Yu, Shandong Qi, Tingting Wang, Shiming Huang, Zhengfeng Ren, Shishen Yan, Shujun Hu, Mingchun Xu
The CO2 adsorption and dynamic behaviors on single crystal anatase TiO2(101) surfaces were investigated by UHV-FTIRS and first-principles calculations. The IRRAS results at 90 K show that the ν3(OCO) asymmetric stretching vibration of adsorbed CO2 exhibits band splitting at rather low CO2 coverage in p-polarized IR spectra for the IR beam incident along the [101[combining macron]] direction. Co-adsorbed CO can prevent such band splitting. Ab initio molecular dynamics (AIMD) simulations revealed that the adsorbed CO2 at finite temperature does not keep a stationary adsorption state but keeps a certain swing motion: one end of the linear CO2 molecule binds to surface Ti5c sites and the other end swings within the (010) plane with a tilted angle distribution ranging from 10° to 60° relative to the [101[combining macron]] direction...
November 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29143112/assessment-of-the-zonal-variation-of-perfusion-parameters-in-the-femoral-head-a-3-t-dynamic-contrast-enhanced-mri-pilot-study
#19
Jean-François Budzik, Guillaume Lefebvre, Hélène Behal, Sébastien Verclytte, Pierre Hardouin, Pedro Teixeira, Anne Cotten
OBJECTIVE: The objective was to describe MR perfusion characteristics of the femoral head, with a focus on the subchondral bone. MATERIALS AND METHODS: This prospective monocentric study was approved by our local Ethics Committee. Written informed consent was obtained from all subjects. Dynamic contrast-enhanced MRI of the right hip was performed in 59 adults with suspected spondyloarthritis (32 women, 28 men). Mean age was 37.5 (±12.5) years. Regions of interest were drawn in the femoral head epiphysis, in the subchondral areas the most exposed to mechanical load (superolateral, anterosuperior, and posterior zones) and in areas less exposed to mechanical load (inferior subchondral zone and center of the femoral head)...
November 15, 2017: Skeletal Radiology
https://www.readbyqxmd.com/read/29142333/approaches-to-macroevolution-1-general-concepts-and-origin-of-variation
#20
David Jablonski
Approaches to macroevolution require integration of its two fundamental components, i.e. the origin and the sorting of variation, in a hierarchical framework. Macroevolution occurs in multiple currencies that are only loosely correlated, notably taxonomic diversity, morphological disparity, and functional variety. The origin of variation within this conceptual framework is increasingly understood in developmental terms, with the semi-hierarchical structure of gene regulatory networks (GRNs, used here in a broad sense incorporating not just the genetic circuitry per se but the factors controlling the timing and location of gene expression and repression), the non-linear relation between magnitude of genetic change and the phenotypic results, the evolutionary potential of co-opting existing GRNs, and developmental responsiveness to nongenetic signals (i...
2017: Evolutionary Biology
keyword
keyword
9827
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"