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Mathematical model

Pawel Kuklik, Benjamin Schäffer, Boris A Hoffmann, Anand N Ganesan, Doreen Schreiber, Julia M Moser, Ruken Ö Akbulak, Arian Sultan, Daniel Steven, Bart Maesen, Ulrich Schotten, Christian Meyer, Stephan Willems
BACKGROUND: Electrogram-based identification of the regions maintaining persistent Atrial Fibrillation (AF) is a subject of ongoing debate. Here, we explore the concept of local electrical dyssynchrony to identify AF drivers. METHODS AND RESULTS: Local electrical dyssynchrony was calculated using mean phase coherence. High-density epicardial mapping along with mathematical model were used to explore the link between local dyssynchrony and properties of wave conduction...
2016: PloS One
Rein M G J Houben, Peter J Dodd
BACKGROUND: The existing estimate of the global burden of latent TB infection (LTBI) as "one-third" of the world population is nearly 20 y old. Given the importance of controlling LTBI as part of the End TB Strategy for eliminating TB by 2050, changes in demography and scientific understanding, and progress in TB control, it is important to re-assess the global burden of LTBI. METHODS AND FINDINGS: We constructed trends in annual risk in infection (ARI) for countries between 1934 and 2014 using a combination of direct estimates of ARI from LTBI surveys (131 surveys from 1950 to 2011) and indirect estimates of ARI calculated from World Health Organisation (WHO) estimates of smear positive TB prevalence from 1990 to 2014...
October 2016: PLoS Medicine
Max Schelker, Caroline Maria Mair, Fabian Jolmes, Robert-William Welke, Edda Klipp, Andreas Herrmann, Max Flöttmann, Christian Sieben
After endocytic uptake, influenza viruses transit early endosomal compartments and eventually reach late endosomes. There, the viral glycoprotein hemagglutinin (HA) triggers fusion between endosomal and viral membrane, a critical step that leads to release of the viral segmented genome destined to reach the cell nucleus. Endosomal maturation is a complex process involving acidification of the endosomal lumen as well as endosome motility along microtubules. While the pH drop is clearly critical for the conformational change and membrane fusion activity of HA, the effect of intracellular transport dynamics on the progress of infection remains largely unclear...
October 2016: PLoS Computational Biology
Maria Kalafateli, Fred Wickham, Maria Burniston, Evangelos Cholongitas, Eleni Theocharidou, Matteo Garcovich, James O'Beirne, Rachel Westbrook, Gioacchino Leandro, Andrew K Burroughs, Emmanuel A Tsochatzis
: Current expressions based on serum creatinine concentration overestimate kidney function in cirrhosis leading to significant differences between "true" and calculated glomerular filtration rate (GFR). We compared the performance of MDRD-4, MDRD-6 and CKD-EPI with "true" GFR and the impact of this difference on MELD calculation. We subsequently developed and validated a GFR equation specifically for cirrhosis and compared the performance of the new derived formula with existing GFR formulas...
October 25, 2016: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
Ryan A Devenyi, Francis A Ortega, Willemijn Groenendaal, Trine Krogh-Madsen, David J Christini, Eric A Sobie
Imbalances of ionic currents can destabilize the cardiac action potential and potentially trigger lethal cardiac arrhythmias. Here we combined mathematical modeling with information-rich dynamic-clamp experiments to elucidate regulation of action potential morphology in guinea pig ventricular myocytes. Parameter sensitivity analysis was used to predict how changes in ionic currents alter action potential duration, and these were tested experimentally using dynamic clamp, a technique that allows for multiple perturbations to be tested in each cell...
October 24, 2016: Journal of Physiology
Arne Liebau, Olivia Pogorzelski, Alec N Salt, Stefan K Plontke
OBJECTIVE: Controlled and uncontrolled studies with primary intratympanic or combined intratympanic and systemic application of glucocorticosteroids for idiopathic sudden hearing loss were analyzed by means of a meta-analysis in an attempt to establish optimal local drug delivery protocols. STUDY DESIGN: A total of 25 studies with 28 treatment groups between January 2000 and June 2014 were selected that adequately described drug delivery protocols. Cochlear drug levels were calculated by a validated computer model of drug dispersion in the inner ear fluids based on the concentration and volume of glucocorticoids applied, the time the drug remained in the middle ear, and the specific timing of injections...
October 21, 2016: Otology & Neurotology
Chih-Yuan Lin, Fu Chen, Li-Hsien Yeh, Jyh-Ping Hsu
Modern applications of nanotechnology such as salinity gradient power and ionic diodes usually involve the transport of ionic species in a system comprising a nanopore connecting two large reservoirs. The charge properties on the nanopore surface plays a key role, and they need to be estimated by fitting a mathematical model for the system to measurable quantities such as ionic current or conductance. This model can also be used to simulate the system behavior under various conditions. However, the large difference between the linear size of a nanopore and that of a reservoir makes relevant analyses difficult...
October 25, 2016: Physical Chemistry Chemical Physics: PCCP
Roberto Burro
BACKGROUND: Several scientific psychologists consider the approach for the study of perceptive problems of the Experimental Phenomenology is problematic, namely that the phenomenological demonstrations are subjectively based and they do not produce quantifiable results. AIM: The aim of this study is to show that Experimental Phenomenology can lead to conclusions objective and quantifiable and propose a procedure allowing to obtain objective measuring using the Rasch mathematical model able to describe the experimental data gathered in Experimental Phenomenology procedures...
2016: SpringerPlus
Yiliao Song, Yong Wang, Feng Liu, Yixin Zhang
Construction and demolition waste (C&DW) is currently a worldwide issue, and the situation is the worst in China due to a rapid increase in the construction industry and the short life span of China's buildings. To create an opportunity out of this problem, comprehensive prevention measures and effective management strategies are urgently needed. One major gap in the literature of waste management is a lack of estimations on future C&DW generation. Therefore, this paper presents a forecasting procedure for C&DW in China that can forecast the quantity of each component in such waste...
October 21, 2016: Waste Management
Ji-Sun Kim, Han-Byeol Oh, A-Hee Kim, Jun-Sik Kim, Eun-Suk Lee, Jin-Young Baek, Ki Sung Lee, Soon-Cheol Chung, Jae-Hoon Jun
Glucose concentration is closely related to the metabolic activity of cells and it is the most important substance as the energy source of a living body which plays an important role in the human body. This paper proposes an optical method that can measure the concentration of glucose. The change in glucose concentration was observed by using CIE diagram, and wavelength and purity values were detected. Also, even small changes in glucose concentration can be evaluated through mathematical modeling. This system is simple, economical, and capable of quantifying optical signals with numerical values for glucose sensing...
October 24, 2016: Bioengineered
Andreas Widder, Christian Kuehn
In this paper, we focus on the influence of heterogeneity and stochasticity of the population on the dynamical structure of a basic susceptible-infected-susceptible (SIS) model. First we prove that, upon a suitable mathematical reformulation of the basic reproduction number, the homogeneous system and the heterogeneous system exhibit a completely analogous global behaviour. Then we consider noise terms to incorporate the fluctuation effects and the random import of the disease into the population and analyse the influence of heterogeneity on warning signs for critical transitions (or tipping points)...
October 1, 2016: Mathematical Biosciences and Engineering: MBE
Anthony Tongen, Maria Zubillaga, Jorge E Rabinovich
Population dynamic models often include males in the calculation of population change, but even in those cases males have rarely been introduced to represent polygyny (harem social structure), where it is particularly important to include males in the reproductive performance of the population. In this article we develop an adaptable matrix population modeling framework for species that have a harem-like social structure under an assumption that the transitions from newborn to juvenile and juvenile to adult both take one time step...
October 1, 2016: Mathematical Biosciences and Engineering: MBE
K E Starkov, Svetlana Bunimovich-Mendrazitsky
Understanding the global interaction dynamics between tumor and the immune system plays a key role in the advancement of cancer therapy. Bunimovich-Mendrazitsky et al. (2015) developed a mathematical model for the study of the immune system response to combined therapy for bladder cancer with Bacillus Calmette-Guérin (BCG) and interleukin-2 (IL-2) . We utilized a mathematical approach for bladder cancer treatment model for derivation of ultimate upper and lower bounds and proving dissipativity property in the sense of Levinson...
October 1, 2016: Mathematical Biosciences and Engineering: MBE
Danilo T Perez-Rivera, Veronica L Torres-Torres, Abraham E Torres-Colon, Maytee Cruz-Aponte
Diabetes mellitus is a disease characterized by a range of metabolic complications involving an individual's blood glucose levels, and its main regulator, insulin. These complications can vary largely from person to person depending on their current biophysical state. Biomedical research day-by-day makes strides to impact the lives of patients of a variety of diseases, including diabetes. One large stride that is being made is the generation of techniques to assist physicians to ``personalize medicine''. From available physiological data, biological understanding of the system, and dimensional analysis, a differential equation-based mathematical model was built in a sequential matter, to be able to elucidate clearly how each parameter correlates to the patient's current physiological state...
October 1, 2016: Mathematical Biosciences and Engineering: MBE
Oscar Patterson-Lomba, Muntaser Safan, Sherry Towers, Jay Taylor
Urban areas, with large and dense populations, offer conditions that favor the emergence and spread of certain infectious diseases. One common feature of urban populations is the existence of large socioeconomic inequalities which are often mirrored by disparities in access to healthcare. Recent empirical evidence suggests that higher levels of socioeconomic inequalities are associated with worsened public health outcomes, including higher rates of sexually transmitted diseases (STD's) and lower life expectancy...
October 1, 2016: Mathematical Biosciences and Engineering: MBE
Jianquan Li, Yiqun Li, Yali Yang
The epidemic characteristics, including the epidemic final size, peak, and turning point, of two classical SIR models with disease-induced death are investigated when a small initial value of the infective population is released. The models have mass-action (i.e. bilinear), or density dependent (i.e. standard) incidence, respectively. For the two models, the conditions that determining whether the related epidemic characteristics of an epidemic outbreak appear are explicitly determine by rigorous mathematical analysis...
October 1, 2016: Mathematical Biosciences and Engineering: MBE
Anarina L Murillo, Muntaser Safan, Carlos Castillo-Chavez, Elizabeth D Capaldi Phillips, Devina Wadhera
Eating behaviors among a large population of children are studied as a dynamic process driven by nonlinear interactions in the sociocultural school environment. The impact of food association learning on diet dynamics, inspired by a pilot study conducted among Arizona children in Pre-Kindergarten to 8th grades, is used to build simple population-level learning models. Qualitatively, mathematical studies are used to highlight the possible ramifications of instruction, learning in nutrition, and health at the community level...
August 1, 2016: Mathematical Biosciences and Engineering: MBE
Azizeh Jabbari, Carlos Castillo-Chavez, Fereshteh Nazari, Baojun Song, Hossein Kheiri
A two-strain tuberculosis (TB) transmission model incorporating antibiotic-generated TB resistant strains and long and variable waiting periods within the latently infected class is introduced. The mathematical analysis is carried out when the waiting periods are modeled via parametrically friendly gamma distributions, a reasonable alternative to the use of exponential distributed waiting periods or to integral equations involving ``arbitrary'' distributions. The model supports a globally-asymptotically stable disease-free equilibrium when the reproduction number is less than one and an endemic equilibriums, shown to be locally asymptotically stable, or l...
August 1, 2016: Mathematical Biosciences and Engineering: MBE
Qihua Huang, Hao Wang
The question of the effects of environmental toxins on ecological communities is of great interest from both environmental and conservational points of view. Mathematical models have been applied increasingly to predict the effects of toxins on a variety of ecological processes. Motivated by the fact that individuals with different sizes may have different sensitivities to toxins, we develop a toxin-mediated size-structured model which is given by a system of first order fully nonlinear partial differential equations (PDEs)...
August 1, 2016: Mathematical Biosciences and Engineering: MBE
H T Banks, John E Banks, R A Everett, John D Stark
We develop statistical and mathematical based methodologies for determining (as the experiment progresses) the amount of information required to complete the estimation of stable population parameters with pre-specified levels of confidence. We do this in the context of life table models and data for growth/death for three species of Daphniids as investigated by J. Stark and J. Banks [17]. The ideas developed here also have wide application in the health and social sciences where experimental data are often expensive as well as difficult to obtain...
August 1, 2016: Mathematical Biosciences and Engineering: MBE
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