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Sara E Borrelli, Denis Walsh, Helen Spiby
OBJECTIVE: To explore first-time mothers' expectations of labour and birth, coping strategies they adopt during pregnancy towards childbirth and coping strategies they expect to use during labour and birth. DESIGN: A qualitative Straussian grounded theory methodology was adopted, with data collected through semi-structured interviews in the third trimester of pregnancy. Ethical approval was gained. Data analysis included the processes of coding and conceptualising data, with constant comparison between data, literature and memos...
May 7, 2018: Midwifery
Adora M DSouza, Anas Z Abidin, Udaysankar Chockanathan, Giovanni Schifitto, Axel Wismüller
Functional connectivity analysis of functional MRI (fMRI) can represent brain networks and reveal insights into interactions amongst different brain regions. However, most connectivity analysis approaches adopted in practice are linear and non-directional. In this paper, we demonstrate the advantage of a data-driven, directed connectivity analysis approach called Mutual Connectivity Analysis using Local Models (MCA-LM) that approximates connectivity by modeling nonlinear dependencies of signal interaction, over more conventionally used approaches, such as Pearson's and partial correlation, Patel's conditional dependence measures, etcetera...
May 16, 2018: NeuroImage
Claudio Chiastra, Maik J Grundeken, Carlos Collet, Wei Wu, Joanna J Wykrzykowska, Giancarlo Pennati, Gabriele Dubini, Francesco Migliavacca
The treatment of coronary bifurcations is challenging for interventional cardiologists. The Tryton stent (Tryton Medical, Inc., USA) is one of the few devices specifically designed for coronary bifurcations that underwent large clinical trials. Although the manufacturer provides specific recommendations to position the stent in the bifurcation side branch (SB) according to four radio-opaque markers under angiographic guidance, wrong device positioning may accidentally occur. In this study, the virtual bench testing approach was used to investigate the impact of wrong positioning of the Tryton stent in coronary bifurcations in terms of geometrical and biomechanical criteria...
May 17, 2018: Cardiovascular Engineering and Technology
Jessica Götzfried, Natalia F Smirnova, Carmela Morrone, Brice Korkmaz, Ali Önder Yildirim, Oliver Eickelberg, Dieter E Jenne
BACKGROUND: Vascular damage and primary graft dysfunction increase with prolonged preservation times of transplanted donor lungs. Hence, storage and conservation of donated lungs in protein-free, dextran-containing electrolyte solutions, like Perfadex, is limited to about 6 hours. We hypothesized that transplanted lungs are protected against neutrophil-mediated proteolytic damage by adding α1 -anti-trypsin (AAT), a highly abundant human plasma proteinase inhibitor, to Perfadex. METHODS: A realistic clinically oriented murine model of lung transplantation was used to simulate the ischemia-reperfusion process...
March 30, 2018: Journal of Heart and Lung Transplantation
Sara Gholampourkashi, Joanna E Cygler, Bernie Lavigne, Emily Heath
PURPOSE: To verify the accuracy of 4D Monte Carlo (MC) simulations, using the 4DdefDOSXYZnrc user code, in a deforming anatomy. We developed a tissue-equivalent and reproducible deformable lung phantom and evaluated 4D simulations of delivered dose to the phantom by comparing calculations against measurements. METHODS: A novel deformable phantom consisting of flexible foam, emulating lung tissue, inside a Lucite external body was constructed. A removable plug, containing an elastic tumor that can hold film and other dosimeters, was inserted in the phantom...
May 15, 2018: Physica Medica: PM
Leila Nasri, Milad Baghersad, Richard Gruss, Nico Sung Won Marucchi, Alan S Abrahams, Johnathon P Ehsani
INTRODUCTION: Despite the advantages of video-based product reviews relative to text-based reviews in detecting possible safety hazard issues, video-based product reviews have received no attention in prior literature. This study focuses on online video-based product reviews as possible sources to detect safety hazards. METHODS: We use two common text mining methods - sentiment and smoke words - to detect safety issues mentioned in videos on the world's most popular video sharing platform, YouTube...
June 2018: Journal of Safety Research
Andreas Brechtel, Philipp Gramlich, Daniel Ritterskamp, Barbara Drossel, Thilo Gross
We study diffusion-driven pattern formation in networks of networks, a class of multilayer systems, where different layers have the same topology, but different internal dynamics. Agents are assumed to disperse within a layer by undergoing random walks, while they can be created or destroyed by reactions between or within a layer. We show that the stability of homogeneous steady states can be analyzed with a master stability function approach that reveals a deep analogy between pattern formation in networks and pattern formation in continuous space...
March 2018: Physical Review. E
Shunda Chen, Davide Donadio, Giuliano Benenti, Giulio Casati
Thermal rectification is of importance not only for fundamental physics, but also for potential applications in thermal manipulations and thermal management. However, thermal rectification effect usually decays rapidly with system size. Here, we show that a mass-graded system, with two diffusive leads separated by a ballistic spacer, can exhibit large thermal rectification effect, with the rectification factor independent of system size. The underlying mechanism is explained in terms of the effective size-independent thermal gradient and the match or mismatch of the phonon bands...
March 2018: Physical Review. E
Ingeborg M Storm, Martien A Cohen Stuart, Renko de Vries, Frans A M Leermakers
A self-consistent field analysis for tunable contributions to the persistence length of isolated semiflexible polymer chains including electrostatically driven coassembled deoxyribonucleic acid (DNA) bottlebrushes is presented. When a chain is charged, i.e., for polyelectrolytes, there is, in addition to an intrinsic rigidity, an electrostatic stiffening effect, because the electric double layer resists bending. For molecular bottlebrushes, there is an induced contribution due to the grafts. We explore cases beyond the classical phantom main-chain approximation and elaborate molecularly more realistic models where the backbone has a finite volume, which is necessary for treating coassembled bottlebrushes...
March 2018: Physical Review. E
Salman Sohrabi, Yaling Liu
Pseudopotential lattice Boltzmann methods (LBMs) can simulate a phase transition in high-density ratio multiphase flow systems. If coupled with thermal LBMs through equation of state, they can be used to study instantaneous phase transition phenomena with a high-temperature gradient where only one set of formulations in an LBM system can handle liquid, vapor, phase transition, and heat transport. However, at lower temperatures an unrealistic spurious current at the interface introduces instability and limits its application in real flow system...
March 2018: Physical Review. E
Ville Jäntti, Tuomo Ylinen, Narayan Puthanmadam Subramaniyam, Kotoe Kamata, Arvi Yli-Hankala, Pasi Kauppinen, Eila Sonkajärvi
Purpose - Anesthesiologists have increasingly started to use EEG based indexes to estimate the level and type of unconsciousness. However, the physiology and biophysics are poorly understood in anesthesiological literature. Methods - EEG was recorded from electrodes on the surface of head, including scalp, as well as DBS (deep brain stimulation) electrodes implanted deep in the brain. Mathematical modeling with a realistic head model was performed to create illustrative images of the sensitivity of electrode montages...
May 18, 2018: International Journal of Radiation Biology
Tran Dieu Hang, Minh Tho Nguyen
(Abstract) Interaction, dissociation and dehydrogenation reactions of water monomer and dimer with pure and mixed tetrameric silicon clusters Si3X with X = Si, Be, Mg, Ca were investigated using high accuracy quantum chemical calculations. While geometries were optimized using the DFT/B3LYP functional with the aug-cc-pVTZ basis set, reaction energy profiles were constructed making use of the coupled-cluster theory with extrapolation to complete basis set, CCSD(T)/CBS. Cleavage of the O-H bond in water dimer is found to be more favored than that of water monomer in the reaction with Si4...
May 18, 2018: Journal of Physical Chemistry. A
Lourens Poorter, Carolina V Castilho, Juliana Schietti, Rafael S Oliveira, Flávia R C Costa
The functional trait approach has, as a central tenet, that plant traits are functional and shape individual performance, but this has rarely been tested in the field. Here, we tested the individual-based trait approach in a hyperdiverse Amazonian tropical rainforest and evaluated intraspecific variation in trait values, plant strategies at the individual level, and whether traits are functional and predict individual performance. We evaluated > 1300 tree saplings belonging to > 383 species, measured 25 traits related to growth and defense, and evaluated the effects of environmental conditions, plant size, and traits on stem growth...
May 18, 2018: New Phytologist
Projesh Kumar Roy, Markus Heyde, Andreas Heuer
The recent experimental discovery of a semi two-dimensional silica glass has offered a realistic description of the random network theory of a silica glass structure, initially discussed by Zachariasen. To study the structure formation of silica in two dimensions, we introduce a two-body force field, based on a soft core Yukawa potential. The different configurations, sampled via Molecular dynamics simulations, can be directly compared with the experimental structures, which have been provided in the literature...
May 18, 2018: Physical Chemistry Chemical Physics: PCCP
S Trautmann, M Richard-Lacroix, A Dathe, H Schneidewind, J Dellith, W Fritzsche, V Deckert
The optical response of realistic 3D plasmonic substrates composed of randomly shaped particles of different size and interparticle distance distributions in addition to nanometer scale surface roughness is intrinsically challenging to simulate due to computational limitations. Here, we present a Finite Element Method (FEM)-based methodology that bridges in-depth theoretical investigations and experimental optical response of plasmonic substrates composed of such silver nanoparticles. Parametrized scanning electron microscopy (SEM) images of surface enhanced Raman spectroscopy (SERS) active substrate and tip-enhanced Raman spectroscopy (TERS) probes are used to simulate the far-and near-field optical response...
May 18, 2018: Nanoscale
John A Lees, Michelle Kendall, Julian Parkhill, Caroline Colijn, Stephen D Bentley, Simon R Harris
Background : Phylogenetic reconstruction is a necessary first step in many analyses which use whole genome sequence data from bacterial populations. There are many available methods to infer phylogenies, and these have various advantages and disadvantages, but few unbiased comparisons of the range of approaches have been made. Methods : We simulated data from a defined "true tree" using a realistic evolutionary model. We built phylogenies from this data using a range of methods, and compared reconstructed trees to the true tree using two measures, noting the computational time needed for different phylogenetic reconstructions...
2018: Wellcome Open Research
Christin Janouch, Uwe Drescher, Konstantin Wechsler, Mathias Haeger, Otmar Bock, Claudia Voelcker-Rehage
Laboratory-based research revealed that gait involves higher cognitive processes, leading to performance impairments when executed with a concurrent loading task. Deficits are especially pronounced in older adults. Theoretical approaches like the multiple resource model highlight the role of task similarity and associated attention distribution problems. It has been shown that in cases where these distribution problems are perceived relevant to participant's risk of falls, older adults prioritize gait and posture over the concurrent loading task...
2018: Frontiers in Psychology
Zachary C Thumser, Andrew B Slifkin, Dylan T Beckler, Paul D Marasco
Fitts' law models the relationship between amplitude, precision, and speed of rapid movements. It is widely used to quantify performance in pointing tasks, study human-computer interaction, and generally to understand perceptual-motor information processes, including research to model performance in isometric force production tasks. Applying Fitts' law to an isometric grip force task would allow for quantifying grasp performance in rehabilitative medicine and may aid research on prosthetic control and design...
2018: Frontiers in Psychology
James C Martin, Jennifer A Nichols
Fish, birds, and lizards sometimes perform locomotor activities with maximized muscle power. Whether humans maximize muscular power is unknown because current experimental techniques cannot be applied non-invasively. This study uses simulated muscle work loops to examine whether voluntary maximal cycling is characterized by maximized muscle power. The simulated work loops leverage experimentally measured joint angles, anatomically realistic muscle parameters (muscle-tendon lengths, velocities, and moment arms), and a published muscle model to calculate powers and forces for thirty-eight muscles...
May 17, 2018: Journal of Experimental Biology
William S Enns-Bray, Stephen J Ferguson, Benedikt Helgason
There is currently a knowledge gap in scientific literature concerning the strain rate dependent properties of trabecular bone at intermediate strain rates. Meanwhile, strain rates between 10 and 200/s have been observed in previous dynamic finite element models of the proximal femur loaded at realistic sideways fall speeds. This study aimed to quantify the effect of strain rate (ε̇) on modulus of elasticity (E), ultimate stress (σu ), failure energy (Uf ), and minimum stress (σm ) of trabecular bone in order to improve the biofidelity of material properties used in dynamic simulations of sideways fall loading on the hip...
May 3, 2018: Journal of Biomechanics
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