Search results for "SIMULATION"
showing 10 items of 5095 documents
The Evonik-Mainz Eye Care-Study (EMECS): Development of an Expert System for Glaucoma Risk Detection in a Working Population
2015
Purpose To develop an expert system for glaucoma screening in a working population based on a human expert procedure using images of optic nerve head (ONH), visual field (frequency doubling technology, FDT) and intraocular pressure (IOP). Methods 4167 of 13037 (32%) employees between 40 and 65 years of Evonik Industries were screened. An experienced glaucoma expert (JW) assessed papilla parameters and evaluated all individual screening results. His classification into “no glaucoma”, “possible glaucoma” and “probable glaucoma” was defined as “gold standard”. A screening model was developed which was tested versus the gold-standard. This model took into account the assessment of the ONH. Valu…
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…
The Inactivation Principle: Mathematical Solutions Minimizing the Absolute Work and Biological Implications for the Planning of Arm Movements
2008
An important question in the literature focusing on motor control is to determine which laws drive biological limb movements. This question has prompted numerous investigations analyzing arm movements in both humans and monkeys. Many theories assume that among all possible movements the one actually performed satisfies an optimality criterion. In the framework of optimal control theory, a first approach is to choose a cost function and test whether the proposed model fits with experimental data. A second approach (generally considered as the more difficult) is to infer the cost function from behavioral data. The cost proposed here includes a term called the absolute work of forces, reflecti…
Can't simply roll it out: Evaluating a real-world virtual reality intervention to reduce driving under the influence.
2020
Driving under the influence (DUI) increases the risk of crashes. Emerging technologies, such as virtual reality (VR), represent potentially powerful and attractive tools for the prevention of risky behaviours, such as DUI. Therefore, they are embraced in prevention efforts with VR interventions primed to grow in popularity in near future. However, little is known about the actual effectiveness of such DUI-targeting VR interventions. To help fill the knowledge gap, this study explored the effects of one VR intervention as delivered in the real world. Using pre and post test design, including an intervention group (n = 98) and a control group (n = 39), the intervention evaluation examined you…
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…
A model-based meta-analysis of sofosbuvir-based treatments in chronic hepatitis C patients.
2016
The objective of this study was to compare the efficacy of sofosbuvir-based treatments in patients with chronic hepatitis C virus (HCV) infection using a model-based meta-analysis (MBMA). A bibliographic search was performed to identify clinical trials involving sofosbuvir as a unique direct-acting antiviral (DAA) agent or together with daclatasvir, ledipasvir or simeprevir for the treatment of diagnosed HCV infection. The time course of the virological response (VR) was modelled to estimate the effect of treatment and the influence of population characteristics on the longitudinal efficacy profile. The model was validated and simulations of 10 different treatment schedules were performed. …
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…
Patient-Specific Rehearsal Feasibility Before Endovascular Repair of Ruptured Abdominal Aortic Aneurysm.
2019
Purpose: To evaluate the feasibility of a patient-specific rehearsal (PsR) before emergency endovascular aneurysm repairs (eEVAR) and its influence on the operation. Materials and Methods: From February 2016 to October 2016, 10 consecutive patients (mean age 75 +/- 7.4 years; 9 men) presenting with a ruptured abdominal aortic aneurysm (rAAA) suitable for standard EVAR were enrolled in the study. A 3-dimensional (3D) model of the abdominal aorta was generated on a virtual reality simulator based on the patient's computed tomography (CT) images. Following the patient-specific simulation setup, PsR was conducted during patient admission or in parallel with the preoperative eEVAR workup. Measur…