Read by QxMD icon Read

mathematical modeling

Min Ma, Fuwei Pi, Jiasheng Wang, Jian Ji, Xiulan Sun
Humans are most likely to be exposed to microcystins (MCs) combined with other water pollutants rather than to individual compounds through the consumption of contaminated drinking water or through recreational activities, such as swimming. However, the combined effects of MC-LR, estradiol (EST), and ractopamine (RAC) have not been extensively researched. The goal of this study was to investigate the combined effects of these compounds. For this purpose, cytotoxicity was evaluated in HepG2 cells treated with single or combined doses of MC-LR, EST, and RAC based on concentration addition (CA), independent action (IA), and Chou-Talalay's combination-index (CI) methods...
October 23, 2016: Chemosphere
Catherine Hankins, Mitchell Warren, Emmanuel Njeuhmeli
Over 11 million voluntary medical male circumcisions (VMMC) have been performed of the projected 20.3 million needed to reach 80% adult male circumcision prevalence in priority sub-Saharan African countries. Striking numbers of adolescent males, outside the 15-49-year-old age target, have been accessing VMMC services. What are the implications of overall progress in scale-up to date? Can mathematical modeling provide further insights on how to efficiently reach the male circumcision coverage levels needed to create and sustain further reductions in HIV incidence to make AIDS no longer a public health threat by 2030? Considering ease of implementation and cultural acceptability, decision makers may also value the estimates that mathematical models can generate of immediacy of impact, cost-effectiveness, and magnitude of impact resulting from different policy choices...
2016: PloS One
David A Winkler, Tu C Le
Neural networks have generated valuable Quantitative Structure-Activity/Property Relationships (QSAR/QSPR) models for a wide variety of small molecules and materials properties. They have grown in sophistication and many of their initial problems have been overcome by modern mathematical techniques. QSAR studies have almost always used so-called "shallow" neural networks in which there is a single hidden layer between the input and output layers. Recently, a new and potentially paradigm-shifting type of neural network based on Deep Learning has appeared...
October 26, 2016: Molecular Informatics
Simona Mancini, René-Marc Mège, Benoit Sarels, Pierre-Olivier Strale
We present a phenomenological model intended to describe at the protein population level the formation of cell-cell junctions by the local recruitment of homophilic cadherin adhesion receptors. This modeling may have a much wider implication in biological processes since many adhesion receptors, channel proteins and other membrane-born proteins associate in clusters or oligomers at the cell surface. Mathematically, it consists in a degenerate reaction-diffusion system of two partial differential equations modeling the time-space evolution of two cadherin populations over a surface: the first one represents the diffusing cadherins and the second one concerns the fixed ones...
October 25, 2016: Journal of Mathematical Biology
Amber Kunkel, Forrest W Crawford, James Shepherd, Ted Cohen
OBJECTIVE: Extending the duration of isoniazid preventive therapy (IPT) among people living with HIV (PLHIV) may improve its effectiveness at both individual and population levels, but could also increase selective pressure in favor of isoniazid-resistant tuberculosis (TB) strains. The objective of this study was to determine the relative importance of these two effects. METHODS: Transmission dynamic model. DESIGN: We created a mathematical model of TB transmission incorporating HIV incidence and treatment, mixed strain latent TB infections, and four different phenotypes of TB drug resistance (pan-susceptible, isoniazid monoresistant, rifampicin monoresistant, and multidrug resistant)...
November 13, 2016: AIDS
Michael A Lee, Naveed Bakh, Gili Bisker, Emery N Brown, Michael S Strano
Cortisol is an important glucocorticoid hormone whose biochemistry influences numerous physiological and pathological processes. Moreover, it is a biomarker of interest for a number of conditions, including posttraumatic stress disorder, Cushing's syndrome, Addison's disease, and others. An implantable biosensor capable of real time monitoring of cortisol concentrations in adipose tissue may revolutionize the diagnosis and treatment of these disorders, as well as provide an invaluable research tool. Toward this end, a mathematical model, informed by the physiological literature, is developed to predict dynamic cortisol concentrations in adipose, muscle, and brain tissues, where a significant number of important processes with cortisol occur...
October 26, 2016: Advanced Healthcare Materials
Ensheng Weng, Caroline E Farrior, Ray Dybzinski, Stephen W Pacala
Earth system models are incorporating plant trait diversity into their land components to better predict vegetation dynamics in a changing climate. However, extant plant trait distributions will not allow extrapolations to novel community assemblages in future climates; that will require a mechanistic understanding of the trade-offs that determine trait diversity. In this study, we show how physiological trade-offs involving leaf mass per unit area (LMA), leaf lifespan, leaf nitrogen, and leaf respiration may explain the distribution patterns of evergreen and deciduous trees in the temperate and boreal zones based on (1) an evolutionary analysis of a simple mathematical model and (2) simulation experiments of an individual-based dynamic vegetation model (i...
October 26, 2016: Global Change Biology
Patrycja Boguta, Piotr M Pieczywek, Zofia Sokołowska
The main aim of this study was the application of excitation-emission fluorescence matrices (EEMs) combined with two decomposition methods: parallel factor analysis (PARAFAC) and nonnegative matrix factorization (NMF) to study the interaction mechanisms between humic acids (HAs) and Zn(II) over a wide concentration range (0-50 mg·dm(-3)). The influence of HA properties on Zn(II) complexation was also investigated. Stability constants, quenching degree and complexation capacity were estimated for binding sites found in raw EEM, EEM-PARAFAC and EEM-NMF data using mathematical models...
October 22, 2016: Sensors
Vladimir García-Morales
A simple discontinuous map is proposed as a generic model for nonlinear dynamical systems. The orbit of the map admits exact solutions for wide regions in parameter space and the method employed (digit manipulation) allows the mathematical design of useful signals, such as regular or aperiodic oscillations with specific waveforms, the construction of complex attractors with nontrivial properties as well as the coexistence of different basins of attraction in phase space with different qualitative properties...
September 2016: Chaos
Abhishek Banerjee, Arnab Dey, Narayanan Chandrakumar
Solution-state Overhauser dynamic nuclear polarization (ODNP) at moderate fields, performed by saturating the electron spin resonance (ESR) of a free radical added to the sample of interest, is well known to lead to significant NMR signal enhancements in the steady state, owing to electron-nuclear cross-relaxation. Here it is shown that under conditions which limit radical access to the molecules of interest, the time course of establishment of ODNP can provide a unique window into internuclear cross-relaxation, and reflects relatively slow molecular motions...
October 26, 2016: Angewandte Chemie
Jennifer L Richards, Carolyn Drews-Botsch, Jessica M Sales, William Dana Flanders, Michael R Kramer
BACKGROUND: Preterm children face higher risk of cognitive and academic deficits compared with their full-term peers. The objective of this study was to describe early childhood cognitive ability and kindergarten academic achievement across gestational age at birth in a population-based longitudinal cohort. METHODS: The study population included singletons born at 24-42 weeks gestation enrolled in the Early Childhood Longitudinal Study-Birth Cohort (n = 6150 for 2-year outcome, n = 4450 for kindergarten outcome)...
October 25, 2016: Paediatric and Perinatal Epidemiology
Hok Pan Yuen, Andrew Mackinnon
Joint modelling has emerged to be a potential tool to analyse data with a time-to-event outcome and longitudinal measurements collected over a series of time points. Joint modelling involves the simultaneous modelling of the two components, namely the time-to-event component and the longitudinal component. The main challenges of joint modelling are the mathematical and computational complexity. Recent advances in joint modelling have seen the emergence of several software packages which have implemented some of the computational requirements to run joint models...
2016: PeerJ
Matthew R Myers, Prasanna Hariharan, Suvajyoti Guha, Jing Yan
Respiratory protective devices (RPDs) are critical for reducing the spread of infection via inhalable droplets. In determining the type of RPD to deploy, it is important to know the reduction in the infection rate that the RPD enables for the given pathogen and population. This paper extends a previously developed susceptible-infected-recovered (SIR) epidemic model to analyse the effect of a protection strategy. An approximate solution to the modified SIR equations, which compares well with a full numerical solution to the equations, was used to derive a simple threshold equation for predicting when growth of the infected population will occur for a given protection strategy...
October 25, 2016: Mathematical Medicine and Biology: a Journal of the IMA
Qingjie Wang, Dong Wang, Gaoliang Yan, Yong Qiao, Ling Sun, Boqian Zhu, Xin Wang, Chengchun Tang
The modulation of sino-atrial node (SAN) automaticity is an essential mechanism of heart rate generation that is still not completely understood. Recent studies highlighted the importance of protein serotonylation by intracellular 5-HT during varies physiological actions. Nevertheless, the functional role of protein serotonylation in controlling SAN automaticity is largely unexplored. In this study, we screened the cardiomyocytes proteins and found that sarco(endo)plasmic reticulum Ca ATPase type 2a (SERCA2a) can be serotonylated...
October 22, 2016: Biochemical and Biophysical Research Communications
John F Schnelle, L Dale Schroyer, Avantika A Saraf, Sandra F Simmons
BACKGROUND: Nursing aides provide most of the labor-intensive activities of daily living (ADL) care to nursing home (NH) residents. Currently, most NHs do not determine nurse aide staffing requirements based on the time to provide ADL care for their unique resident population. The lack of an objective method to determine nurse aide staffing requirements suggests that many NHs could be understaffed in their capacity to provide consistent ADL care to all residents in need. Discrete event simulation (DES) mathematically models key work parameters (eg, time to provide an episode of care and available staff) to predict the ability of the work setting to provide care over time and offers an objective method to determine nurse aide staffing needs in NHs...
November 1, 2016: Journal of the American Medical Directors Association
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
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"