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mathematical modeling

Liu Changshi, Zhang Jianxin
The voltage-dependent current is a crucial parameter for determining the electrical properties of microelectronic devices. In this study, we aimed to extend a generic dc model to successfully explain the drain current (Id ) for metal-oxide semiconductors (MOSs) and thin-film transistors (TFTs) based on the gate voltage (Vg ), where the threshold voltage (Vth ) could also be obtained from this model in a nature manner. This dc model meets the requirements for compact modeling, including modeling computer circuit simulators...
April 4, 2018: Applied Radiation and Isotopes
António M M Rodrigues, Tiffany B Taylor
Identifying the ecological and demographic factors that promote the evolution of cooperation is a major challenge for evolutionary biologists. Explanations for the adaptive evolution of cooperation seek to determine which factors make reproduction in cooperative groups more favourable than independent breeding or other selfish strategies. A vast majority of the hypotheses posit that cooperative groups emerge in the context of philopatry, high costs of dispersal, high population density, and environmental stability...
April 21, 2018: Journal of Evolutionary Biology
Walid Djema, Catherine Bonnet, Frédéric Mazenc, Jean Clairambault, Emilia Fridman, Pierre Hirsch, François Delhommeau
OBJECTIVE: Modeling and analysis of cell population dynamics enhance our understanding of cancer. Here we introduce and explore a new model that may apply to many tissues. ANALYSES: An age-structured model describing coexistence between mutated and ordinary stem cells is developed and explored. The model is transformed into a nonlinear time-delay system governing the dynamics of healthy cells, coupled to a nonlinear differential-difference system describing dynamics of unhealthy cells...
April 17, 2018: Journal of Theoretical Biology
Gustavo Andrés Baquero-Rodríguez, Jaime Andrés Lara-Borrero, Daniel Nolasco, Diego Rosso
  In this review, the factors affecting the transfer of oxygen in activated sludge processes using fine-pore diffusers for water resource recovery are critically discussed. In water resource recovery facilities, the energy required for aeration constitutes 50% to 80% of the total energy consumed by the plant. This critical review highlights the use of fine-pore diffuser aeration and emphasizes the significance of accounting for the following factors: diffuser aging and fouling, diffuser layout, diffuser type, selector benefits, local environmental conditions (temperature and atmospheric pressure), influent wastewater variability, dissolved oxygen control systems, and airflow rates...
May 1, 2018: Water Environment Research: a Research Publication of the Water Environment Federation
Can Zhou, Guiling Deng, Junhui Li, Ji'an Duan
To improve the jet performance of a bi-piezoelectric jet dispenser, mathematical and simulation models were established according to the operating principle. In order to improve the accuracy and reliability of the simulation calculation, a viscosity model of the fluid was fitted to a fifth-order function with shear rate based on rheological test data, and the needle displacement model was fitted to a nine-order function with time based on real-time displacement test data. The results show that jet performance is related to the diameter of the nozzle outlet and the cone angle of the nozzle, and the impacts of the flow channel structure were confirmed...
April 20, 2018: Sensors
M Azari, A V Le, M Lübken, M Denecke
A mathematical model for a granular biofilm reactor for leachate treatment was validated by long-term measured data to investigate the mechanisms and drivers influencing biological nitrogen removal and microbial consortia dynamics. The proposed model, based on Activated Sludge Model (ASM1), included anaerobic ammonium oxidation (anammox), nitrifying and heterotrophic denitrifying bacteria which can attach and grow on granular activated carbon (GAC) particles. Two kinetic descriptions for the model were proposed: with and without soluble microbial products (SMP) and extracellular polymeric substance (EPS)...
April 2018: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Denis A Adamchik, Valery V Matrosov, Victor B Kazantsev
Dynamics of a homogeneous neural population interacting with active extracellular medium were considered. The corresponding mathematical model was tuned specifically to describe the behavior of interneurons with tonic GABA conductance under the action of non-stationary ambient GABA. The feedback provided by the GABA mediated transmembrane current enriched the repertoire of population activity by enabling the oscillatory behavior. This behavior appeared in the form of relaxation oscillations which can be considered as a specific type of brainwaves...
2018: Frontiers in Computational Neuroscience
Astrid S Pechstein, Joachim Schöberl
The tangential-displacement normal-normal-stress (TDNNS) method is a finite element method for mixed elasticity. As the name suggests, the tangential component of the displacement vector as well as the normal-normal component of the stress are the degrees of freedom of the finite elements. The TDNNS method was shown to converge of optimal order, and to be robust with respect to shear and volume locking. However, the method is slightly nonconforming, and an analysis with respect to the natural norms of the arising spaces was still missing...
2018: Numerische Mathematik
Naritatsu Saito
No abstract text is available yet for this article.
April 20, 2018: EuroIntervention
Anežka Kotěrová, David Navega, Michal Štepanovský, Zdeněk Buk, Jaroslav Brůžek, Eugénia Cunha
The assessment of age-at-death is an important and challenging part of investigations of human skeletal remains. The main objective of the present study was to apply different mathematical approaches in order to reach more accurate and reliable results in age estimation. A multi-ethnic dataset (n=941) of evaluated age-related changes on the pubic symphysis and the auricular surface of the hip bone was used. Two research groups examined nine different mathematical approaches. The best results were reached by Multi-linear regression, followed by the Collapsed regression model, with MAE values of 9...
April 4, 2018: Forensic Science International
Matthew T McKenna, Jared A Weis, Amy Brock, Vito Quaranta, Thomas E Yankeelov
Medical oncology is in need of a mathematical modeling toolkit that can leverage clinically-available measurements to optimize treatment selection and schedules for patients. Just as the therapeutic choice has been optimized to match tumor genetics, the delivery of those therapeutics should be optimized based on patient-specific pharmacokinetic/pharmacodynamic properties. Under the current approach to treatment response planning and assessment, there does not exist an efficient method to consolidate biomarker changes into a holistic understanding of treatment response...
April 16, 2018: Translational Oncology
Marcus T Wilson, Ben D Fulcher, Park K Fung, P A Robinson, Alex Fornito, Nigel C Rogasch
Transcranial magnetic stimulation (TMS) is a widely used noninvasive brain stimulation method capable of inducing plastic reorganisation of cortical circuits in humans. Changes in neural activity following TMS are often attributed to synaptic plasticity via process of long-term potentiation and depression (LTP/LTD). However, the precise way in which synaptic processes such as LTP/LTD modulate the activity of large populations of neurons, as stimulated en masse by TMS, are unclear. The recent development of biophysical models, which incorporate the physiological properties of TMS-induced plasticity mathematically, provide an excellent framework for reconciling synaptic and macroscopic plasticity...
April 5, 2018: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
Albert Szparaga, Tomasz Kowalkowski, Bogusław Buszewski
The article contains a description of both the mathematical modeling of particles separation in self-adjustable channel for Split Flow Thin Cell Fractionation (SPLITT), and the channel design concept. The channel is designed to work in full feed depletion mode (FFD-SPLITT). By using different diameters of outlets, the channel has the ability to self-adjust the flow rates at the outlets. Moreover, in order to increase the throughput of the sample only one splitter, positioned at the end of the separation cell, was used...
March 23, 2018: Journal of Chromatography. A
Brian W Darvell, Brian H Gilding
OBJECTIVE: Miniature magnets are used in dentistry, principally for the retention of prosthetic devices. The relationship between force and separation of a magnet and its keeper, or, equivalently, two such magnets, has been neither defined theoretically nor described practically in any detail suitable for these applications. The present paper addresses this lacuna. METHODS: A magnet is considered as a conglomeration of magnetic poles distributed over a surface or a solid in three-dimensional space, with the interaction of poles governed by the Coulomb law...
April 16, 2018: Dental Materials: Official Publication of the Academy of Dental Materials
Peter Kumberger, Karina Durso-Cain, Susan L Uprichard, Harel Dahari, Frederik Graw
Mathematical models based on ordinary differential equations (ODE) that describe the population dynamics of viruses and infected cells have been an essential tool to characterize and quantify viral infection dynamics. Although an important aspect of viral infection is the dynamics of viral spread, which includes transmission by cell-free virions and direct cell-to-cell transmission, models used so far ignored cell-to-cell transmission completely, or accounted for this process by simple mass-action kinetics between infected and uninfected cells...
April 17, 2018: Viruses
Courtney L Davis, Rezwanul Wahid, Franklin R Toapanta, Jakub K Simon, Marcelo B Sztein
[This corrects the article DOI: 10.1371/journal.pone.0189571.].
2018: PloS One
Don Li, Michael J Hautus, Douglas Elliffe
Models that generate event records have very general scope regarding the dimensions of the target behavior that we measure. From a set of predicted event records, we can generate predictions for any dependent variable that we could compute from the event records of our subjects. In this sense, models that generate event records permit us a freely multivariate analysis. To explore this proposition, we conducted a multivariate examination of Catania's Operant Reserve on single VI schedules in transition using a Markov Chain Monte Carlo scheme for Approximate Bayesian Computation...
April 19, 2018: Journal of the Experimental Analysis of Behavior
Benan Shu, Shaopeng Wu, Lijie Dong, Qing Wang, Quantao Liu
This work aims to develop an original alginate micro-emulsion combining with droplets microfluidic method to produce multinuclear Ca-alginate microcapsules containing rejuvenator for the self-healing of bituminous binder. The sizes of the Ca-alginate microcapsules could be easily controlled by tuning flow rates of the continuous and dispersed phases. The addition of a surfactant Tween80 not only improved the stability of the emulsion, but it also effectively reduced the size of the microcapsules. Size predictive mathematical model of the microcapsules was proposed through the analysis of fluid force...
April 19, 2018: Materials
Effrosyni Doutsi, Lionel Fillatre, Marc Antonini, Julien Gaulmin
This paper introduces a novel filter, which is inspired by the human retina. The human retina consists of three different layers: the Outer Plexiform Layer (OPL), the inner plexiform layer, and the ganglionic layer. Our inspiration is the linear transform which takes place in the OPL and has been mathematically described by the neuroscientific model "virtual retina." This model is the cornerstone to derive the non-separable spatio-temporal OPL retina-inspired filter, briefly renamed retina-inspired filter, studied in this paper...
July 2018: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Svetlana Postnova, Steven W Lockley, Peter A Robinson
A model of arousal dynamics is applied to predict objective performance and subjective sleepiness measures, including lapses and reaction time on a visual Performance Vigilance Test (vPVT), performance on a mathematical addition task (ADD), and the Karolinska Sleepiness Scale (KSS). The arousal dynamics model is comprised of a physiologically based flip-flop switch between the wake- and sleep-active neuronal populations and a dynamic circadian oscillator, thus allowing prediction of sleep propensity. Published group-level experimental constant routine (CR) and forced desynchrony (FD) data are used to calibrate the model to predict performance and sleepiness...
April 2018: Journal of Biological Rhythms
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