Search results for "Computer simulation"
showing 10 items of 1054 documents
Distributed analysis of simultaneous EEG-fMRI time-series: modeling and interpretation issues
2009
Functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) represent brain activity in terms of a reliable anatomical localization and a detailed temporal evolution of neural signals. Simultaneous EEG-fMRI recordings offer the possibility to greatly enrich the significance and the interpretation of the single modality results because the same neural processes are observed from the same brain at the same time. Nonetheless, the different physical nature of the measured signals by the two techniques renders the coupling not always straightforward, especially in cognitive experiments where spatially localized and distributed effects coexist and evolve temporally at different …
Relationship between perception of smile esthetics and orthodontic treatment in Spanish patients
2018
Este artículo se encuentra disponible en la página web de la revista en la siguiente URL: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0201102 One of the main objectives of orthodontic treatment is to achieve an esthetic smile. This study set out to analyze differences in the perception of smile esthetics among patients before and after receiving orthodontic treatment. 250 Spanish patients analyzed a single photograph in which, by means of computer software, midline diastema, black triangle, gingival margin of the left central incisor, and gingival (ªgummyº) smile were altered. Each patient analyzed these images before and after undergoing orthodontic treatment. Patient…
Bayesian model to detect phenotype-specific genes for copy number data
2012
Abstract Background An important question in genetic studies is to determine those genetic variants, in particular CNVs, that are specific to different groups of individuals. This could help in elucidating differences in disease predisposition and response to pharmaceutical treatments. We propose a Bayesian model designed to analyze thousands of copy number variants (CNVs) where only few of them are expected to be associated with a specific phenotype. Results The model is illustrated by analyzing three major human groups belonging to HapMap data. We also show how the model can be used to determine specific CNVs related to response to treatment in patients diagnosed with ovarian cancer. The …
Numerical simulation of glottal flow
2012
In cases of permanent immobility of both vocal folds patients have difficulties with breathing but rarely with voicing. However, clinical experience shows that the shape of the larynx (voice box) seems to have a significant influence on the degree of airflow and breathing pattern. In order to find an optimal geometry of the larynx in terms of easiness for breathing after the surgical change of vocal folds or false vocal cords (ventricular folds), a set of numerical simulations of glottal flow for weakly compressible Navier-Stokes equations has been performed. We compare airflow resistance and volumetric flow rate for several geometry concepts for inspiration as well as expiration. Finally, …
An ancestral recombination graph for diploid populations with skewed offspring distribution
2013
A large offspring number diploid biparental multilocus population model of Moran type is our object of study. At each timestep, a pair of diploid individuals drawn uniformly at random contribute offspring to the population. The number of offspring can be large relative to the total population size. Similar `heavily skewed' reproduction mechanisms have been considered by various authors recently. Each diploid parental individual contributes exactly one chromosome to each diploid offspring, and hence ancestral lineages can only coalesce when in distinct individuals. A separation of timescales phenomenon is thus observed. A result of M\"{o}hle (1998) is extended to obtain convergence of the an…
Validation of the Strain Assessment of a Phantom of Abdominal Aortic Aneurysm: Comparison of Results Obtained From Magnetic Resonance Imaging and Ste…
2018
Predicting aortic aneurysm ruptures is a complex problem that has been investigated by many research teams over several decades. Work on this issue is notably complex and involves both the mechanical behavior of the artery and the blood flow. Magnetic resonance imaging (MRI) can provide measurements concerning the shape of an organ and the blood that flows through it. Measuring local distortion of the artery wall is the first essential factor to evaluate in a ruptured artery. This paper aims to demonstrate the feasibility of this measure using MRI on a phantom of an abdominal aortic aneurysm (AAA) with realistic shape. The aortic geometry is obtained from a series of cine-MR images and reco…
Hsp10 nuclear localization and changes in lung cells response to cigarette smoke suggest novel roles for this chaperonin
2014
Heat-shock protein (Hsp)10 is the co-chaperone for Hsp60 inside mitochondria, but it also resides outside the organelle. Variations in its levels and intracellular distribution have been documented in pathological conditions, e.g. cancer and chronic obstructive pulmonary disease (COPD). Here, we show that Hsp10 in COPD undergoes changes at the molecular and subcellular levels in bronchial cells from human specimens and derived cell lines, intact or subjected to stress induced by cigarette smoke extract (CSE). Noteworthy findings are: (i) Hsp10 occurred in nuclei of epithelial and lamina propria cells of bronchial mucosa from non-smokers and smokers; (ii) human bronchial epithelial (16HBE) a…
Facial patterns in Cercopithecoidea and Hominoidea: a geometric approach.
2006
The maxillofacial and orbital compartments of the primate skull contribute to the ontogenetic and phylogenetic variability of the viscerocranium and are of crucial evolutionary relevance. As the form of organisms changes depending on endo- and exogenous factors, metrical evaluation of specific adaptations and incorporation of the results into a biological framework could be helpful in identifying valid characters for separation of taxa (e.g. family, genus, and species) and in understanding divergence and convergence. During the last two decades a morphometric "revolution" heralded by Rohlf & Marcus (1993), Adams et al. (2004) and Oxnard (2004) brought about a synthesis of traditional quanti…
Spectral clustering of shape and probability prior models for automatic prostate segmentation.
2013
Imaging artifacts in Transrectal Ultrasound (TRUS) images and inter-patient variations in prostate shape and size challenge computer-aided automatic or semi-automatic segmentation of the prostate. In this paper, we propose to use multiple mean parametric models derived from principal component analysis (PCA) of shape and posterior probability information to segment the prostate. In contrast to traditional statistical models of shape and intensity priors, we use posterior probability of the prostate region determined from random forest classification to build, initialize and propagate our model. Multiple mean models derived from spectral clustering of combined shape and appearance parameters…
A pharmacokinetic approach to model-guided design of infliximab schedules in ulcerative colitis patients
2015
Background: Infliximab, an anti-tumour necrosis factor approved for treatment of Crohn's disease and ulcerative colitis, is administered at predefined interdose-intervals. On insufficient response or loss of response, treatment can be intensified. The lack or loss of response is likely related to complex pharmacokinetics of infliximab. Aims: To explore optimal dosing strategies of infliximab in treatment-naïve patients with ulcerative colitis through predictive Monte Carlo simulations based on a validated population PK model. Methods: A population of 2,000 treatment-naïve patients was generated by Montecarlo simulation. Six dosing strategies for maintenance therapy were simulated on this po…