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https://www.readbyqxmd.com/read/28550763/mechanical-properties-of-a-nanoporous-membrane-used-in-implantable-medical-devices-correlation-between-experimental-characterization-and-2d-numerical-simulation
#1
F Cristofari, B Piotrowski, R Pesci
Nanoporous membranes are used for the elaboration of implantable medical devices. In order to guaranty their integrity after implantation in a patient body, it is necessary to characterize the microstructure and the mechanical behavior of such membranes. They present randomly distributed pores around 1µm in diameter at the surface. X-ray nanotomography permits to get the geometry of the pores through the thickness with a reduction of the diameter in the core. A multiscale study is done to characterize the membranes: macroscopic tensile tests permit to get the behavior law of the non porous material and in situ tensile tests are carried on in a Scanning Electron Microscope in order to observe the evolution of pores and cracks during loading...
May 18, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28548240/viscoelastic-computational-modeling-of-the-human-head-neck-system-eigenfrequencies-and-time-dependent-analysis
#2
E Boccia, A Gizzi, C Cherubini, M G C Nestola, S Filippi
A subject-specific three-dimensional viscoelastic finite element model of the human head-neck system is presented and investigated based on Computed Tomography and Magnetic Resonance biomedical images. Ad hoc imaging processing tools are developed for the reconstruction of the simulation domain geometry and the internal distribution of bone and soft tissues. Materials viscoelastic properties are characterized point-wise through an image-based interpolating function used then for assigning the constitutive prescriptions of a heterogenous viscoelastic continuum model...
May 26, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28547587/new-quantitative-radiographic-parameters-for-vertical-and-horizontal-instability-in-acromioclavicular-joint-dislocations
#3
Matthias A Zumstein, Philippe Schiessl, Benedikt Ambuehl, Lilianna Bolliger, Johannes Weihs, Martin H Maurer, Beat K Moor, Michael Schaer, Sumit Raniga
PURPOSE: The aim of this study was to identify the most accurate and reliable quantitative radiographic parameters for assessing vertical and horizontal instability in different Rockwood grades of acromioclavicular joint (ACJ) separations. Furthermore, the effect of projectional variation on these parameters was investigated in obtaining lateral Alexander view radiographs. METHODS: A Sawbone model of a scapula with clavicle was mounted on a holding device, and acromioclavicular dislocations as per the Rockwood classification system were simulated with the addition of horizontal posterior displacement...
May 25, 2017: Knee Surgery, Sports Traumatology, Arthroscopy: Official Journal of the ESSKA
https://www.readbyqxmd.com/read/28546104/development-of-a-paediatric-physiologically-based-pharmacokinetic-model-to-assess-the-impact-of-drug-drug-interactions-in-tuberculosis-co-infected-malaria-subjects-a-case-study-with-artemether-lumefantrine-and-the-cyp3a4-inducer-rifampicin
#4
Olusola Olafuyi, Michael Coleman, Raj K S Badhan
The fixed dosed combination of artemether and lumefantrine (AL) is widely used for the treatment of malaria in adults and children in sub-Sahara Africa, with lumefantrine day 7 concentrations being widely used as a marker for clinical efficacy. Both are substrates for CYP3A4 and susceptible to drug-drug interactions (DDIs); indeed, knowledge of the impact of these factors is currently sparse in paediatric population groups. Confounding malaria treatment is the co-infection of patients with tuberculosis. The concomitant treatment of AL with tuberculosis chemotherapy, which includes the CYP3A4 inducer rifampicin, increases the risk of parasite recrudescence and malaria treatment failure...
May 22, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28545933/extracting-multidimensional-stimulus-response-correlations-using-hybrid-encoding-decoding-of-neural-activity
#5
REVIEW
Jacek P Dmochowski, Jason Ki, Paul DeGuzman, Paul Sajda, Lucas C Parra
In neuroscience, stimulus-response relationships have traditionally been analyzed using either encoding or decoding models. Here we propose a hybrid approach that decomposes neural activity into multiple components, each representing a portion of the stimulus. The technique is implemented via canonical correlation analysis (CCA) by temporally filtering the stimulus (encoding) and spatially filtering the neural responses (decoding) such that the resulting components are maximally correlated. In contrast to existing methods, this approach recovers multiple correlated stimulus-response pairs, and thus affords a richer, multidimensional analysis of neural representations...
May 22, 2017: NeuroImage
https://www.readbyqxmd.com/read/28544976/long-range-transport-of-xe-133-emissions-under-convective-and-non-convective-conditions
#6
J Kuśmierczyk-Michulec, M Krysta, M Kalinowski, E Hoffmann, J Baré
To investigate the transport of xenon emissions, the Provisional Technical Secretariat (PTS) operates an Atmospheric Transport Modelling (ATM) system based on the Lagrangian Particle Dispersion Model FLEXPART. The air mass trajectory ideally provides a "link" between a radionuclide release and a detection confirmed by radionuclide measurements. This paper investigates the long-range transport of Xe-133 emissions under convective and non-convective conditions, with special emphasis on evaluating the changes in the simulated activity concentration values due to the inclusion of the convective transport in the ATM simulations...
May 22, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/28544882/inference-and-evolutionary-analysis-of-genome-scale-regulatory-networks-in-large-phylogenies
#7
Christopher Koch, Jay Konieczka, Toni Delorey, Ana Lyons, Amanda Socha, Kathleen Davis, Sara A Knaack, Dawn Thompson, Erin K O'Shea, Aviv Regev, Sushmita Roy
Changes in transcriptional regulatory networks can significantly contribute to species evolution and adaptation. However, identification of genome-scale regulatory networks is an open challenge, especially in non-model organisms. Here, we introduce multi-species regulatory network learning (MRTLE), a computational approach that uses phylogenetic structure, sequence-specific motifs, and transcriptomic data, to infer the regulatory networks in different species. Using simulated data from known networks and transcriptomic data from six divergent yeasts, we demonstrate that MRTLE predicts networks with greater accuracy than existing methods because it incorporates phylogenetic information...
May 24, 2017: Cell Systems
https://www.readbyqxmd.com/read/28544854/algorithms-for-imputing-partially-observed-recurrent-events-with-applications-to-multiple-imputation-in-pattern-mixture-models
#8
Yongqiang Tang
Five algorithms are described for imputing partially observed recurrent events modeled by a negative binomial process, or more generally by a mixed Poisson process when the mean function for the recurrent events is continuous over time. We also discuss how to perform the imputation when the mean function of the event process has jump discontinuities. The validity of these algorithms is assessed by simulations. These imputation algorithms are potentially very useful in the implementation of pattern mixture models, which have been popularly used as sensitivity analysis under the non-ignorability assumption in clinical trials...
May 25, 2017: Journal of Biopharmaceutical Statistics
https://www.readbyqxmd.com/read/28543951/determination-of-genetic-relatedness-from-low-coverage-human-genome-sequences-using-pedigree-simulations
#9
Michael D Martin, Flora Jay, Sergi Castellano, Montgomery Slatkin
We develop and evaluate methods for inferring relatedness among individuals from low-coverage DNA sequences of their genomes, with particular emphasis on sequences obtained from fossil remains. We suggest the major factors complicating the determination of relatedness among ancient individuals are sequencing depth, the number of overlapping sites, the sequencing error rate, and the presence of contamination from present-day genetic sources. We develop a theoretical model that facilitates the exploration of these factors and their relative effects, via measurement of pairwise genetic distances, without calling genotypes, and determine the power to infer relatedness under various scenarios of varying sequencing depth, present-day contamination, and sequencing error...
May 25, 2017: Molecular Ecology
https://www.readbyqxmd.com/read/28542952/compensatory-and-decompensatory-alterations-in-cardiomyocyte-ca-2-dynamics-in-hearts-with-diastolic-dysfunction-following-aortic-banding
#10
Sara Gattoni, Åsmund Treu Røe, Jan Magnus Aronsen, Ivar Sjaastad, William E Louch, Nicolas P Smith, Steven A Niederer
KEY POINTS: At the cellular level cardiac hypertrophy causes remodelling, leading to changes in ionic channel, pump and exchanger densities and kinetics. Previous studies have focused on quantifying changes in channels, pumps and exchangers without quantitatively linking these changes with emergent cellular scale functionality. Two biophysical cardiac cell models were created, parameterized and validated and are able to simulate electrophysiology and calcium dynamics in myocytes from control sham operated rats and aortic-banded rats exhibiting diastolic dysfunction...
May 21, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28542705/a-pump-free-microfluidic-3d-perfusion-platform-for-the-efficient-differentiation-of-human-hepatocyte-like-cells
#11
Louis Jun Ye Ong, Lor Huai Chong, Lin Jin, Pawan Kumar Singh, Poh Seng Lee, Hanry Yu, Abhishek Ananthanarayanan, Hwa Liang Leo, Yi-Chin Toh
The practical application of microfluidic liver models for in vitro drug testing is partly hampered by their reliance on human primary hepatocytes, which are limited in number and have batch-to-batch variation. Human stem cell-derived hepatocytes offer an attractive alternative cell source, although their 3D differentiation and maturation in a microfluidic platform have not yet been demonstrated. We develop a pump-free microfluidic 3D perfusion platform to achieve long-term and efficient differentiation of human liver progenitor cells into hepatocyte-like cells (HLCs)...
May 20, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28542336/does-ngal-reduce-costs-a-cost-analysis-of-urine-ngal-ungal-serum-creatinine-scr-for-acute-kidney-injury-aki-diagnosis
#12
Amay Parikh, John A Rizzo, Pietro Canetta, Catherine Forster, Meghan Sise, Omar Maarouf, Eugenia Singer, Antje Elger, Saban Elitok, Kai Schmidt-Ott, Jonathon Barasch, Thomas L Nickolas
INTRODUCTION: Urine neutrophil gelatinase-associated lipocalin (uNGAL) is a sensitive and specific diagnostic test for acute kidney injury (AKI) in the Emergency Department (ED), but its economic impact has not been investigated. We hypothesized that uNGAL used in combination with serum creatinine (sCr) would reduce costs in the management of AKI in patients presenting to the ED in comparison to using sCr alone. MATERIALS AND METHODS: A cost simulation model was developed for clinical algorithms to diagnose AKI based on sCr alone vs...
2017: PloS One
https://www.readbyqxmd.com/read/28541904/diffusion-based-model-for-synaptic-molecular-communication-channel
#13
Tooba Khan, Bilgesu A Bilgin, Ozgur B Akan
Computational methods have been extensively used to understand underlying dynamics of molecular communication methods employed by nature. One very effective and popular approach is to utilize a Monte Carlo simulation. Although it is very reliable, this method can have a very high computational cost, which in some cases renders the simulation impractical. Therefore, in this paper, for the special case of an excitatory synaptic molecular communication channel, we present a novel mathematical model for the diffusion and binding of neurotransmitters that takes into account the effects of synaptic geometry in three-dimensional space and re-absorption of neurotransmitters by the transmitting neuron...
May 23, 2017: IEEE Transactions on Nanobioscience
https://www.readbyqxmd.com/read/28541602/three-dimensional-printing-in-cardiology-current-applications-and-future-challenges
#14
Hongxing Luo, Jarosław Meyer-Szary, Zhongmin Wang, Robert Sabiniewicz, Yuhao Liu
Three-dimensional (3D) printing has attracted a huge interest in recent years. Broadly speaking, it refers to the technology which converts a predesigned virtual model to a touchable object. In clinical medicine, it usually converts a series of two-dimensional medical images acquired through computed tomography, magnetic resonance imaging or 3D echocardiography into a physical model. Medical 3D printing consists of three main steps: image acquisition, virtual reconstruction and 3D manufacturing. It is a promising tool for preoperative evaluation, medical device design, hemodynamic simulation and medical education, it is also likely to reduce operative risk and increase operative success...
May 25, 2017: Cardiology Journal
https://www.readbyqxmd.com/read/28541529/statistical-algorithms-improve-accuracy-of-gene-fusion-detection
#15
Gillian Hsieh, Rob Bierman, Linda Szabo, Alex Gia Lee, Donald E Freeman, Nathaniel Watson, E Alejandro Sweet-Cordero, Julia Salzman
Gene fusions are known to play critical roles in tumor pathogenesis. Yet, sensitive and specific algorithms to detect gene fusions in cancer do not currently exist. In this paper, we present a new statistical algorithm, MACHETE (Mismatched Alignment CHimEra Tracking Engine), which achieves highly sensitive and specific detection of gene fusions from RNA-Seq data, including the highest Positive Predictive Value (PPV) compared to the current state-of-the-art, as assessed in simulated data. We show that the best performing published algorithms either find large numbers of fusions in negative control data or suffer from low sensitivity detecting known driving fusions in gold standard settings, such as EWSR1-FLI1...
May 24, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28541226/haptic-feedback-in-needle-insertion-modeling-and-simulation-review
#16
Gourishetti Ravali, Muniyandi Manivannan
Needle insertion being the most basic skill in medical care, training has to be imparted not only for physicians but also for nurses and paramedics. In most needle insertion procedures haptic feedback from the needle is the main stimulus that novices are to be trained in. For better patient safety, the classical methods of training the haptic skills have to be replaced with simulators based on new robotic and graphics technologies. This paper reviews the current advances in needle insertion modeling. It is classified into three sections: needle insertion models, tissue deformation models, and needle-tissue interaction models...
May 23, 2017: IEEE Reviews in Biomedical Engineering
https://www.readbyqxmd.com/read/28540719/one-step-toward-a-new-generation-of-c-mos-compatible-oxide-p-n-junctions-structure-of-the-lsmo-zno-interface-elucidated-by-an-experimental-and-theoretical-synergic-work
#17
Daniele Pullini, Mauro Francesco Sgroi, Agnes Nora Mahmoud, Nicolas Gauquelin, Lorenzo Maschio, Anna Maria Ferrari, Rik Groenen, Cas Damen, Guus Rijnders, Karel H W van den Bos, Sandra Van Aert, Johan Verbeeck
Heterostructures formed by La0.7Sr0.3MnO3/ZnO (LSMO/ZnO) interfaces exhibit extremely interesting electronic properties making them promising candidatea for novel oxide p-n junctions with multifunctional features. In this work, the structure of the interface is studied through a combined experimental/theoretical approach, . Hetero-structures were grown epitaxially and homogeneously on 4" silicon wafers, characterized by advanced electron microscopy imaging and spectroscopy, and simulated by ab-initio DFT calculations...
May 25, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28540638/in-silico-dose-prediction-for-long-acting-rilpivirine-and-cabotegravir-administration-to-children-and-adolescents
#18
Rajith K R Rajoli, David J Back, Steve Rannard, Caren Freel Meyers, Charles Flexner, Andrew Owen, Marco Siccardi
BACKGROUND AND OBJECTIVES: Long-acting injectable antiretrovirals represent a pharmacological alternative to oral formulations and an innovative clinical option to address adherence and reduce drug costs. Clinical studies in children and adolescents are characterised by ethical and logistic barriers complicating the identification of dose optimisation. Physiologically-based pharmacokinetic modelling represents a valuable tool to inform dose finding prior to clinical trials. The objective of this study was to simulate potential dosing strategies for existing long-acting injectable depot formulations of cabotegravir and rilpivirine in children and adolescents (aged 3-18 years) using physiologically-based pharmacokinetic modelling...
May 24, 2017: Clinical Pharmacokinetics
https://www.readbyqxmd.com/read/28540366/recombination-in-perovskite-solar-cells-significance-of-grain-boundaries-interface-traps-and-defect-ions
#19
Tejas S Sherkar, Cristina Momblona, Lidón Gil-Escrig, Jorge Ávila, Michele Sessolo, Henk J Bolink, L Jan Anton Koster
Trap-assisted recombination, despite being lower as compared with traditional inorganic solar cells, is still the dominant recombination mechanism in perovskite solar cells (PSCs) and limits their efficiency. We investigate the attributes of the primary trap-assisted recombination channels (grain boundaries and interfaces) and their correlation to defect ions in PSCs. We achieve this by using a validated device model to fit the simulations to the experimental data of efficient vacuum-deposited p-i-n and n-i-p CH3NH3PbI3 solar cells, including the light intensity dependence of the open-circuit voltage and fill factor...
May 12, 2017: ACS Energy Letters
https://www.readbyqxmd.com/read/28539930/nonlinear-porous-diffusion-modeling-of-hydrophilic-ionic-agrochemicals-in-astomatous-plant-cuticle-aqueous-pores-a-mechanistic-approach
#20
Eloise C Tredenick, Troy W Farrell, W Alison Forster, Steven T P Psaltis
The agricultural industry requires improved efficacy of sprays being applied to crops and weeds in order to reduce their environmental impact and deliver improved financial returns. Enhanced foliar uptake is one means of improving efficacy. The plant leaf cuticle is known to be the main barrier to diffusion of agrochemicals within the leaf. The usefulness of a mathematical model to simulate uptake of agrochemicals in plant cuticles has been noted previously in the literature, as the results of each uptake experiment are specific to each formulation of active ingredient, plant species and environmental conditions...
2017: Frontiers in Plant Science
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