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https://www.readbyqxmd.com/read/28538996/the-relationship-between-surface-curvature-and-abdominal-aortic-aneurysm-wall-stress
#1
Sergio Ruiz de Galarreta, Aitor Cazon, Raúl Antón, Ender A Finol
The maximum diameter criterion is the most important factor when predicting risk of rupture of abdominal aortic aneurysms (AAA). An elevated wall stress has also been linked to a high risk of aneurysm rupture, yet is an uncommon clinical practice to compute AAA wall stress. The purpose of this study is to assess whether other characteristics of the AAA geometry are statistically correlated with wall stress. Using in-house segmentation and meshing algorithms, thirty patient-specific AAA models were generated for finite element analysis...
May 24, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/28538990/measuring-nonlinear-signal-combination-using-eeg
#2
Darren G M Cunningham, Daniel H Baker, Jonathan W Peirce
Relatively little is known about the processes, both linear and nonlinear, by which signals are combined beyond V1. By presenting two stimulus components simultaneously, flickering at different temporal frequencies (frequency tagging) while measuring steady-state visual evoked potentials, we can assess responses to the individual components, including direct measurements of suppression on each other, and various nonlinear responses to their combination found at intermodulation frequencies. The result is a rather rich dataset of frequencies at which responses can be found...
May 1, 2017: Journal of Vision
https://www.readbyqxmd.com/read/28538985/numerical-approximation-of-elasticity-tensor-associated-with-green-naghdi-rate
#3
Haofei Liu, Wei Sun
Objective stress rates are often used in commercial finite element (FE) programs. However, deriving a consistent tangent modulus tensor (also known as elasticity tensor or material Jacobian) associated with the objective stress rates is challenging when complex material models are utilized. In this paper, an approximation method for the tangent modulus tensor associated with the Green-Naghdi rate of the Kirchhoff stress is employed to simplify the evaluation process. The effectiveness of the approach is demonstrated through the implementation of two user-defined fiber-reinforced hyperelastic material models...
May 24, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/28538836/establishment-of-patient-derived-tumor-xenograft-pdtx-models-using-samples-from-ct-guided-percutaneous-biopsy
#4
Y-P Zhuang, Y-P Zhu, H-Y Wang, L Sun, J Zhang, Y-P Hao, L Wang
This study aimed to investigate the feasibility of the establishment of a human cancer xenograft model using samples from computed tomography (CT)-guided percutaneous biopsy. Fresh tumor tissues obtained from 10 cancer patients by CT-guided percutaneous biopsy were subcutaneously inoculated into NOD-Prkdcem26Il2rgem26Nju (NCG) mice to establish human patient-derived tumor xenograft (PDTX) models. The formation of first and second generation xenografts was observed, and tumor volume was recorded over time. Tumor tissue consistency between the PDTX model and primary tumors in patients was compared using H&E staining and immunohistochemistry...
May 18, 2017: Brazilian Journal of Medical and Biological Research, Revista Brasileira de Pesquisas Médicas e Biológicas
https://www.readbyqxmd.com/read/28538731/a-neural-circuit-architecture-for-angular-integration-in-drosophila
#5
Jonathan Green, Atsuko Adachi, Kunal K Shah, Jonathan D Hirokawa, Pablo S Magani, Gaby Maimon
Many animals keep track of their angular heading over time while navigating through their environment. However, a neural-circuit architecture for computing heading has not been experimentally defined in any species. Here we describe a set of clockwise- and anticlockwise-shifting neurons in the Drosophila central complex whose wiring and physiology provide a means to rotate an angular heading estimate based on the fly's angular velocity. We show that each class of shifting neurons exists in two subtypes, with spatiotemporal activity profiles that suggest different roles for each subtype at the start and end of tethered-walking turns...
May 22, 2017: Nature
https://www.readbyqxmd.com/read/28538593/dynamic-response-of-the-lumbar-spine-to-whole-body-vibration-under-a-compressive-follower-preload
#6
Li-Xin Guo, Wei Fan
STUDY DESIGN: A finite element study of dynamic response of the lumbar spine to whole-body vibration. OBJECTIVE: To develop and validate a finite element model for exploring the impact of whole-body vibration on the entire lumbar spine with a compressive follower preload applied. SUMMARY OF BACKGROUND DATA: Several finite element studies have investigated the biodynamic characteristics of the human lumbar spine when exposed to whole-body vibration...
May 22, 2017: Spine
https://www.readbyqxmd.com/read/28538188/identification-and-characterization-of-a-class-of-malat1-like-genomic-loci
#7
Bin Zhang, Yuntao S Mao, Sarah D Diermeier, Irina V Novikova, Eric P Nawrocki, Tom A Jones, Zsolt Lazar, Chang-Shung Tung, Weijun Luo, Sean R Eddy, Karissa Y Sanbonmatsu, David L Spector
The MALAT1 (Metastasis-Associated Lung Adenocarcinoma Transcript 1) gene encodes a noncoding RNA that is processed into a long nuclear retained transcript (MALAT1) and a small cytoplasmic tRNA-like transcript (mascRNA). Using an RNA sequence- and structure-based covariance model, we identified more than 130 genomic loci in vertebrate genomes containing the MALAT1 3' end triple-helix structure and its immediate downstream tRNA-like structure, including 44 in the green lizard Anolis carolinensis. Structural and computational analyses revealed a co-occurrence of components of the 3' end module...
May 23, 2017: Cell Reports
https://www.readbyqxmd.com/read/28538153/new-continuum-approaches-for-determining-protein-induced-membrane-deformations
#8
David Argudo, Neville P Bethel, Frank V Marcoline, Charles W Wolgemuth, Michael Grabe
The influence of the membrane on transmembrane proteins is central to a number of biological phenomena, notably the gating of stretch activated ion channels. Conversely, membrane proteins can influence the bilayer, leading to the stabilization of particular membrane shapes, topological changes that occur during vesicle fission and fusion, and shape-dependent protein aggregation. Continuum elastic models of the membrane have been widely used to study protein-membrane interactions. These mathematical approaches produce physically interpretable membrane shapes, energy estimates for the cost of deformation, and a snapshot of the equilibrium configuration...
May 23, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28538143/openrbc-a-fast-simulator-of-red-blood-cells-at%C3%A2-protein-resolution
#9
Yu-Hang Tang, Lu Lu, He Li, Constantinos Evangelinos, Leopold Grinberg, Vipin Sachdeva, George Em Karniadakis
We present OpenRBC, a coarse-grained molecular dynamics code, which is capable of performing an unprecedented in silico experiment-simulating an entire mammal red blood cell lipid bilayer and cytoskeleton as modeled by multiple millions of mesoscopic particles-using a single shared memory commodity workstation. To achieve this, we invented an adaptive spatial-searching algorithm to accelerate the computation of short-range pairwise interactions in an extremely sparse three-dimensional space. The algorithm is based on a Voronoi partitioning of the point cloud of coarse-grained particles, and is continuously updated over the course of the simulation...
May 23, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28538021/global-surgery-current-evidence-for-improving-surgical-care
#10
Jennifer C Fuller, David A Shaye
PURPOSE OF REVIEW: The field of global surgery is undergoing rapid transformation, owing to several recent prominent reports positioning it as a cost-effective means of relieving global disease burden. The purpose of this article is to review the recent advances in the field of global surgery. RECENT FINDINGS: Efforts to grow the global surgical workforce and procedural capacity have focused on innovative methods to increase surgeon training, enhance international collaboration, leverage technology, optimize existing health systems, and safely implement task-sharing...
May 19, 2017: Current Opinion in Otolaryngology & Head and Neck Surgery
https://www.readbyqxmd.com/read/28537747/examination-of-the-mechanism-of-the-yield-of-n2o-from-nitroxyl-hno-in-the-solution-phase-by-theoretical-calculations
#11
Kaiqiang Zhang, Stefan T Thynell
The dimerization of HNO and subsequent yield of N2O in aqueous solution are studied based on the theoretical calculations and kinetic simulations. The initial dimerization reactions were computed at various levels of theory and large divergence was observed in the predictions of the gas-phase free energies. The T1 diagnostics at CCSD(T)/aug-cc-pVTZ suggests multireference characteristics of the HNO dimers and the transition states. The solution-phase free energies were obtained using the wB97XD method and the SMD solvation model...
May 24, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28537092/eating-away-from-home-influences-on-the-dietary-quality-of-adolescents-with-overweight-or-obesity
#12
Allison W Watts, Maria Valente, Andrew Tu, Louise C Mâsse
PURPOSE: To examine the influence of peers and the source of meals and snacks on the dietary quality of adolescents seeking obesity treatment. METHODS: Baseline surveys were completed by 173 adolescents with overweight or obesity (11-16 years old) enrolled in an e-health intervention in Vancouver, British Columbia. Dietary quality was assessed with three 24-h dietary recalls used to compute a Healthy Eating Index adapted to the Canadian context (HEI-C). Multiple linear regression examined associations between HEI-C scores and the frequency of: (i) meals prepared away from home, (ii) purchasing snacks from vending machines or stores, (iii) eating out with friends, and (iv) peers modeling healthy eating...
May 24, 2017: Canadian Journal of Dietetic Practice and Research
https://www.readbyqxmd.com/read/28535495/understanding-the-heterogeneity-of-cervical-cancer-screening-non-participants-data-from-a-national-sample-of-british-women
#13
Laura A V Marlow, Amanda J Chorley, Jessica Haddrell, Rebecca Ferrer, Jo Waller
BACKGROUND: Uptake of cervical cancer screening in the United Kingdom (UK) is falling year on year, and a more sophisticated understanding of non-participation may help design interventions to reverse this trend. This study ascertained the prevalence of different non-participant types using the Precaution Adoption Process Model (PAPM). METHODS: Home-based computer-assisted interviews were carried out with 3113 screening-eligible women in Britain. Survey items assessed self-reported screening uptake and intention to attend in future...
May 20, 2017: European Journal of Cancer
https://www.readbyqxmd.com/read/28535263/gene-expression-variability-and-the-analysis-of-large-scale-rna-seq-studies-with-the-mdseq
#14
Di Ran, Z John Daye
Rapidly decreasing cost of next-generation sequencing has led to the recent availability of large-scale RNA-seq data, that empowers the analysis of gene expression variability, in addition to gene expression means. In this paper, we present the MDSeq, based on the coefficient of dispersion, to provide robust and computationally efficient analysis of both gene expression means and variability on RNA-seq counts. The MDSeq utilizes a novel reparametrization of the negative binomial to provide flexible generalized linear models (GLMs) on both the mean and dispersion...
May 23, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28535199/genotype-phenotype-correlation-in-patients-with-isovaleric-acidemia-comparative-structural-modelling-and-computational-analysis-of-novel-variants
#15
Osama K Zaki, George Priya Doss C, Salsabil A Ali, Ghadeer G Murad, Shaima A Elashi, Maryam Sa Ebnou, D Thirumal Kumar, Ola Khalifa, Radwa Gamal, Heba S A El Abd, Bilal N Nasr, Hatem Zayed
Isovaleric acidemia (IVA) is an autosomal recessive inborn error of leucine metabolism. It is caused by a deficiency in the mitochondrial isovaleryl-CoA dehydrogenase (IVD) enzyme. In this study, we investigated eight patients with IVA. The patients diagnoses were confirmed by urinary organic acid analysis and the blood C5-Carnitine value. A molecular genetic analysis of the IVD gene revealed nine different variants: five were missense variants (c.1193G>A; p. R398Q, c.1207T>A; p. Y403N, c.872C>T; p...
May 23, 2017: Human Molecular Genetics
https://www.readbyqxmd.com/read/28535149/quantitative-computational-models-of-molecular-self-assembly-in-systems-biology
#16
Marcus Thomas, Russell Schwartz
Molecular self-assembly is the dominant form of chemical reaction in living systems, yet efforts at systems biology modeling are only beginning to appreciate the need for and challenges to accurate quantitative modeling of self-assembly. Self-assembly reactions are essential to nearly every important process in cell and molecular biology and handling them is thus a necessary step in building comprehensive models of complex cellular systems. They present exceptional challenges, however, to standard methods for simulating complex systems...
May 23, 2017: Physical Biology
https://www.readbyqxmd.com/read/28534805/a-novel-approach-to-implement-takagi-sugeno-fuzzy-models
#17
Chia-Wen Chang, Chin-Wang Tao
This paper proposes new algorithms based on the fuzzy c-regressing model algorithm for Takagi-Sugeno (T-S) fuzzy modeling of the complex nonlinear systems. A fuzzy c-regression state model (FCRSM) algorithm is a T-S fuzzy model in which the functional antecedent and the state-space-model-type consequent are considered with the available input-output data. The antecedent and consequent forms of the proposed FCRSM consists mainly of two advantages: one is that the FCRSM has low computation load due to only one input variable is considered in the antecedent part; another is that the unknown system can be modeled to not only the polynomial form but also the state-space form...
May 16, 2017: IEEE Transactions on Cybernetics
https://www.readbyqxmd.com/read/28534802/organ-location-determination-and-contour-sparse-representation-for-multi-organ-segmentation
#18
Siqi Li, Huiyan Jiang, Yu-Dong Yao, Benqiang Yang
Organ segmentation on computed tomography (CT) images is of great importance in medical diagnoses and treatment. This paper proposes organ location determination and contour sparse representation methods (OLD-CSR) for multiorgan segmentation (liver, kidney, and spleen) on abdomen CT images using an extreme learning machine (ELM) classifier. First, a location determination method is designed to obtain location information of each organ, which is used for coarse segmentation. Second, for coarse-to-fine segmentation, a contour gradient and rate change based feature point extraction method is proposed...
May 17, 2017: IEEE Journal of Biomedical and Health Informatics
https://www.readbyqxmd.com/read/28534790/neighborhood-based-stopping-criterion-for-contrastive-divergence
#19
Enrique Romero Merino, Ferran Mazzanti Castrillejo, Jordi Delgado Pin
Restricted Boltzmann Machines (RBMs) are general unsupervised learning devices to ascertain generative models of data distributions. RBMs are often trained using the Contrastive Divergence (CD) learning algorithm, an approximation to the gradient of the data log-likelihood (logL). A simple reconstruction error is often used as a stopping criterion for CD, although several authors have raised doubts concerning the feasibility of this procedure. In many cases, the evolution curve of the reconstruction error is monotonic, while the logL is not, thus indicating that the former is not a good estimator of the optimal stopping point for learning...
May 17, 2017: IEEE Transactions on Neural Networks and Learning Systems
https://www.readbyqxmd.com/read/28534781/reviving-the-two-state-markov-chain-approach
#20
Andrzej Mizera, Jun Pang, Qixia Yuan
Probabilistic Boolean networks (PBNs) is a well-established computational framework for modelling biological systems. The steady-state dynamics of PBNs is of crucial importance in the study of such systems. However, for large PBNs, which often arise in systems biology, obtaining the steady-state distribution poses a significant challenge. In this paper, we revive the two-state Markov chain approach to solve this problem. This paper contributes in three aspects. First, we identify a problem of generating biased results with the approach and we propose a few heuristics to avoid such a pitfall...
May 16, 2017: IEEE/ACM Transactions on Computational Biology and Bioinformatics
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