Search results for "modeling"
showing 10 items of 4489 documents
Editorial: Special issue on Simulation in Transportation
2020
Transportation systems and related policies are complex and cross-sectoral, covering different socio-economic and management aspects, and involving multiple stakeholders (such as users, operators, and public policymakers). Mobility and accessibility are central to economic and societal well-being, yet the process of doing so may have significant impacts on land use, environment, and public health. Furthermore, the many feedbacks involved occur at varying degrees of spatial, temporal, and socio-demographic granularity and levels of uncertainty. Simulation models are well established in transportation-related operational research and management science, and the alternative approaches of Syste…
One is not enough: On the effects of reference genome for the mapping and subsequent analyses of short-reads.
2020
Mapping of high-throughput sequencing (HTS) reads to a single arbitrary reference genome is a frequently used approach in microbial genomics. However, the choice of a reference may represent a source of errors that may affect subsequent analyses such as the detection of single nucleotide polymorphisms (SNPs) and phylogenetic inference. In this work, we evaluated the effect of reference choice on short-read sequence data from five clinically and epidemiologically relevant bacteria (Klebsiella pneumoniae, Legionella pneumophila, Neisseria gonorrhoeae, Pseudomonas aeruginosa and Serratia marcescens). Publicly available whole-genome assemblies encompassing the genomic diversity of these species…
Seven Mathematical Models of Hemorrhagic Shock
2021
Although mathematical modelling of pressure-flow dynamics in the cardiocirculatory system has a lengthy history, readily finding the appropriate model for the experimental situation at hand is often a challenge in and of itself. An ideal model would be relatively easy to use and reliable, besides being ethically acceptable. Furthermore, it would address the pathogenic features of the cardiovascular disease that one seeks to investigate. No universally valid model has been identified, even though a host of models have been developed. The object of this review is to describe several of the most relevant mathematical models of the cardiovascular system: the physiological features of circulator…
Reverse-engineering post-transcriptional regulation of gap genes in Drosophila melanogaster
2013
16 páginas, 6 figuras, 1 tabla
A practical methodology to perform global sensitivity analysis for 2D hydrodynamic computationally intensive simulations
2021
Sensitivity analysis is a commonly used technique in hydrological modeling for different purposes, including identifying the influential parameters and ranking them. This paper proposes a simplified sensitivity analysis approach by applying the Taguchi design and the ANOVA technique to 2D hydrodynamic flood simulations, which are computationally intensive. This approach offers an effective and practical way to rank the influencing parameters, quantify the contribution of each parameter to the variability of the outputs, and investigate the possible interaction between the input parameters. A number of 2D flood simulations have been carried out using the proposed combinations by Taguchi (L27…
Using Machine Learning to Characterize Atrial Fibrotic Substrate From Intracardiac Signals With a Hybrid in silico and in vivo Dataset
2021
[EN] In patients with atrial fibrillation, intracardiac electrogram signal amplitude is known to decrease with increased structural tissue remodeling, referred to as fibrosis. In addition to the isolation of the pulmonary veins, fibrotic sites are considered a suitable target for catheter ablation. However, it remains an open challenge to find fibrotic areas and to differentiate their density and transmurality. This study aims to identify the volume fraction and transmurality of fibrosis in the atrial substrate. Simulated cardiac electrograms, combined with a generalized model of clinical noise, reproduce clinically measured signals. Our hybrid dataset approach combines in silico and clinic…
TRACX2: a RAAM -like autoencoder modeling graded chunking in infant visual -sequence learning
2017
International audience; Even newborn infants are able to extract structure from a stream of sensory inputs and yet, how this is achieved remains largely a mystery. We present a connectionist autoencoder model, TRACX2, that learns to extract sequence structure by gradually constructing chunks, storing these chunks in a distributed manner across its synaptic weights, and recognizing these chunks when they re-occur in the input stream. Chunks are graded rather than all-or-none in nature and during learning their component parts become ever more tightly bound together. TRACX2 successfully models data from four experiments from the infant visual statistical-learning literature, including tasks i…
Long-term determinants of changes in television viewing time in adults : Prospective analyses from the Young Finns Study
2018
Purpose: The long‐term effects of sociodemographic and health characteristics on television viewing (TV) time changes have not been identified in adulthood. We aimed to examine the modifiable and non‐modifiable determinants of changes in TV‐time in young adults over 10 years.Methods: Participants (N = 2929) aged 24‐39 years were recruited between 2001 and 2011 from the Cardiovascular Risk in Young Finns Study. Data were collected using questionnaires and a medical examination. The determinants of changes in TV‐time were estimated using latent growth modeling for men and women separately.Results: For men, inverse associations with initial levels of TV‐time were observed for students becoming…
Non-invasive localization of atrial ectopic beats by using simulated body surface P-wave integral maps
2017
Non-invasive localization of continuous atrial ectopic beats remains a cornerstone for the treatment of atrial arrhythmias. The lack of accurate tools to guide electrophysiologists leads to an increase in the recurrence rate of ablation procedures. Existing approaches are based on the analysis of the P-waves main characteristics and the forward body surface potential maps (BSPMs) or on the inverse estimation of the electric activity of the heart from those BSPMs. These methods have not provided an efficient and systematic tool to localize ectopic triggers. In this work, we propose the use of machine learning techniques to spatially cluster and classify ectopic atrial foci into clearly diffe…
Epigenetic Regulation of Early- and Late-Response Genes in Acute Pancreatitis
2015
Abstract Chromatin remodeling seems to regulate the patterns of proinflammatory genes. Our aim was to provide new insights into the epigenetic mechanisms that control transcriptional activation of early- and late-response genes in initiation and development of severe acute pancreatitis as a model of acute inflammation. Chromatin changes were studied by chromatin immunoprecipitation analysis, nucleosome positioning, and determination of histone modifications in promoters of proinflammatory genes in vivo in the course of taurocholate-induced necrotizing pancreatitis in rats and in vitro in rat pancreatic AR42J acinar cells stimulated with taurocholate or TNF-α. Here we show that the upregulat…