Read by QxMD icon Read

Mathematical modelling

Samir Kc, Wolfgang Lutz
This paper applies the methods of multi-dimensional mathematical demography to project national populations based on alternative assumptions on future, fertility, mortality, migration and educational transitions that correspond to the five shared socioeconomic pathways (SSP) storylines. In doing so it goes a significant step beyond past population scenarios in the IPCC context which considered only total population size. By differentiating the human population not only by age and sex-as is conventionally done in demographic projections-but also by different levels of educational attainment the most fundamental aspects of human development and social change are being explicitly addressed through modeling the changing composition of populations by these three important individual characteristics...
January 2017: Global Environmental Change: Human and Policy Dimensions
Yael Salzer, Gilles de Hollander, Birte U Forstmann
The Simon task is one of the most prominent interference tasks and has been extensively studied in experimental psychology and cognitive neuroscience. Despite years of research, the underlying mechanism driving the phenomenon and its temporal dynamics are still disputed. Within the framework of the review, we adopt a model-based cognitive neuroscience approach. We first go over key findings in the literature of the Simon task, discuss competing qualitative cognitive theories and the difficulty of testing them empirically...
February 23, 2017: Neuroscience and Biobehavioral Reviews
Hendrik Richter
Players of coevolutionary games may update not only their strategies but also their networks of interaction. Based on interpreting the payoff of players as fitness, dynamic landscape models are proposed. The modeling procedure is carried out for Prisoner's Dilemma (PD) and Snowdrift (SD) games that both use either birth-death (BD) or death-birth (DB) strategy updating. The main focus is on using dynamic fitness landscapes as a mathematical model of coevolutionary game dynamics. Hence, an alternative tool for analyzing coevolutionary games becomes available, and landscape measures such as modality, ruggedness and information content can be computed and analyzed...
February 23, 2017: Bio Systems
Pierre Magal, Zhengyang Zhang
In this article we build a mathematical model for forest growth and we compare this model with a computer forest simulator named SORTIE. The main ingredient taken into account in both models is the competition for light between trees. The parameters of the mathematical model are estimated by using SORTIE model, when the parameter values of SORTIE model correspond to the ones previously evaluated for the Great Mountain Forest in USA. We see that the best fit of the parameters of the mathematical model is obtained when the competition for light influences only the growth rate of trees...
February 23, 2017: Journal of Theoretical Biology
W Nakahashi
Traumatic lesions are often observed in ancient skeletal remains. Since ancient medical technology was immature, severely traumatized individuals may have frequently lost the physical ability for cultural skills that demand complex body movements. I develop a mathematical model to analyze the effect of trauma on cultural transmission and apply it to Neanderthal culture using Neanderthal fossil data. I estimate from the data that the proportion of adult individuals who suffered traumatic injuries before death was approximately 0...
February 4, 2017: Homo: Internationale Zeitschrift Für die Vergleichende Forschung Am Menschen
Jong Chan Lee, Zahra Ghasemi, Chang-Sei Kim, Hao-Min Cheng, Chen-Huan Chen, Shih-Hsien Sung, Ramakrishna Mukkamala, Jin-Oh Hahn
We investigated the relationship between carotid artery blood pressure (BP) and distal pulse volume waveforms (PVRs) via subject-specific mathematical modeling. We conceived three physical models to define the relationship: a tube-load model augmented with a gain (TLG), Voigt (TLV) and standard linear solid (TLS) models. We compared these models using PVRs measured via BP cuffs at an upper arm and an ankle as well as carotid artery tonometry waveform collected from 133 subjects. At both upper arm and ankle, PVR was related to carotid artery tonometry by TLV and TLS models better than by TLG model; when root-mean-squared over all the subjects, the systolic and diastolic BP errors between measured carotid artery tonometry waveform and the one estimated from distal PVR reduced from 4...
February 22, 2017: IEEE Journal of Biomedical and Health Informatics
Fabien Crauste, Julien Mafille, Lilia Boucinha, Sophia Djebali, Olivier Gandrillon, Jacqueline Marvel, Christophe Arpin
Primary immune responses generate short-term effectors and long-term protective memory cells. The delineation of the genealogy linking naive, effector, and memory cells has been complicated by the lack of phenotypes discriminating effector from memory differentiation stages. Using transcriptomics and phenotypic analyses, we identify Bcl2 and Mki67 as a marker combination that enables the tracking of nascent memory cells within the effector phase. We then use a formal approach based on mathematical models describing the dynamics of population size evolution to test potential progeny links and demonstrate that most cells follow a linear naive→early effector→late effector→memory pathway...
February 16, 2017: Cell Systems
Yuewu Liu, Xiufen Zou
In vitro, the recombinant HIV-1 Gag protein can generate spherical particles with a diameter of 25-30 nm in a fully defined system. It has approximately 80 building blocks, and its intermediates for assembly are abundant in geometry. Accordingly, there are a large number of nonlinear equations in the classical model. Therefore, it is difficult to compute values of geometry parameters for intermediates and make the mathematical analysis using the model. In this work, we develop a new model of HIV-like particle assembly in vitro by using six-fold symmetry of HIV-like particle assembly to decrease the number of geometry parameters...
February 22, 2017: Mathematical Biosciences
Maeve L McCarthy, Dorothy Wallace, Howard H Whiteman, Evan T Rheingold, Ann M Dunham, Olivia Prosper, Michelle Chen, Eileen Hu-Wang
Phenotypic plasticity is the ability of an organism to change its phenotype in response to changes in the environment. General mathematical descriptions of the phenomenon rely on an abstract measure of "viability" that, in this study, is instantiated in the case of the Tiger Salamander, Ambystoma tigrinum. This organism has a point in its development when, upon maturing, it may take two very different forms. One is a terrestrial salamander (metamorph)that visits ponds to reproduce and eat, while the other is an aquatic form (paedomorph) that remains in the pond to breed and which consumes a variety of prey including its own offspring...
February 22, 2017: Mathematical Biosciences
Hitomi I Sano, Tamami Toki, Yasuhiro Naito, Masaru Tomita
The developmental program of the heart requires accurate regulation to ensure continuous circulation and simultaneous cardiac morphogenesis, because any functional abnormalities may progress to congenital heart malformation. Notably, energy metabolism in fetal ventricular cells is regulated in a manner that differs from adult ventricular cells: fetal cardiomyocytes generally have immature mitochondria and fetal ventricular cells show greater dependence on glycolytic ATP production. However, although various characteristics of energy metabolism in fetal ventricular cells have been reported, to our knowledge, a quantitative description of the contributions of these factors to fetal ventricular cell functions has not yet been established...
February 22, 2017: Journal of Theoretical Biology
Mark P Connolly, Nikolaos Kotsopoulos, Maarten J Postma, Aomesh Bhatt
Governments have an enormous economic and political stake in the health of their populations. Population health is not only fundamental to economic growth but also affects short-term and long-term government expenditure on health care, disability, and other social programs and influences direct and indirect tax receipts. Fiscal transfers between citizen and state are mostly ignored in conventional welfare economics analyses based on the hypothesis that there are no winners or losers through transference of wealth...
February 2017: Value in Health: the Journal of the International Society for Pharmacoeconomics and Outcomes Research
N Simon, J-M Azorin, R Belzeaux, M Adida, A Kaladjian
Drug development of new compounds implies to define the dosage as well as the conditions of their use (indication, treatment duration, drug interactions, warnings …). This information requires the identification of the time course response. The decisions made during the clinical phases are now based on mathematical models. These models are continuously described and improved during all phases of the drug development using data collected in healthy volunteers and patients. Their objectives are to describe the most precisely, the link between the compound characteristics (pharmacology), the patient demographics and the effects...
December 2016: L'Encéphale
Andrea Guala, Carlo Camporeale, Luca Ridolfi, Luca Mesin
Everyday clinical cardiovascular evaluation is still largely based on brachial systolic and diastolic pressures. However, several clinical studies have demonstrated the higher diagnostic capacities of the aortic pressure, as well as the need to assess the aortic mechanical properties (e.g., by measuring the aortic pulse wave velocity). In order to fill this gap, we propose to exploit a set of easy-to-obtain physical characteristics to estimate the aortic pressure and pulse wave velocity. To this aim, a large population of virtual subjects is created by a validated mathematical model of the cardiovascular system...
February 21, 2017: Medical Engineering & Physics
Yutaro Ogawa, Ikuhiro Yamaguchi, Kiyoshi Kotani, Yasuhiko Jimbo
Cognitive functions such as sensory processing and memory processes lead to phase synchronization in the electroencephalogram or local field potential between different brain regions. There are a lot of computational researches deriving phase locking values (PLVs), which are an index of phase synchronization intensity, from neural models. However, these researches derive PLVs numerically. To the best of our knowledge, there have been no reports on the derivation of a theoretical PLV. In this study, we propose an analytical method for deriving theoretical PLVs from a cortico-thalamic neural mass model described by a delay differential equation...
February 24, 2017: Journal of Computational Neuroscience
Ignacio Rodriguez-Brenes, Antonina V Kurtova, Christopher Lin, Yu-Cheng Lee, Jing Xiao, Martha P Mims, Keith Syson Chan, Dominik Wodarz
Chemotherapy has been shown to enrich cancer stem cells in tumors. Recently, we demonstrated that administration of chemotherapy to human bladder cancer xenografts could trigger a wound-healing response that mobilizes quiescent tumor stem cells into active proliferation, leading to a loss of sensitivity to chemotherapy. Different bladder cancer xenografts, however, demonstrate differential sensitivities to chemotherapy, the basis of which is not understood. Using mathematical models, we show here that characteristics of the tumor cell hierarchy can be crucial for determining the sensitivity of tumors to drug therapy, under the assumption that stem cell enrichment is the primary basis for drug resistance...
February 24, 2017: Cancer Research
Daiki Hirai, Yasunori Iwao, Shin-Ichiro Kimura, Shuji Noguchi, Shigeru Itai
Metastable crystals and the amorphous state of poorly water-soluble drugs in solid dispersions (SDs), are subject to a solid-liquid interface reaction upon exposure to a solvent. The dissolution behavior during the solid-liquid interface reaction often shows that the concentration of drugs is supersaturated, with a high initial drug concentration compared with the solubility of stable crystals but finally approaching the latter solubility with time. However, a method for measuring the precipitation rate of stable crystals and/or the potential solubility of metastable crystals or amorphous drugs has not been established...
February 21, 2017: International Journal of Pharmaceutics
Hassan Khassehkhan, Hermann J Eberl
We study a previously introduced mathematical model of amensalistic control of the foodborne pathogen Listeria monocytogenes by the generally regarded as safe lactic acid bacteria Lactococcus lactis in a chemostat setting under nutrient rich growth conditions. The control agent produces lactic acids and thus affects pH in the environment such that it becomes detrimental to the pathogen while it is much more tolerant to these self-inflicted environmental changes itself. The mathematical model consists of five nonlinear ordinary differential equations for both bacterial species, the concentration of lactic acids, the pH and malate...
September 9, 2016: Foods (Basel, Switzerland)
Kazuki Matsui, Yasuhiro Tsume, Susumu Takeuchi, Amanda Searls, Gordon L Amidon
Weakly basic drugs exhibit a pH-dependent dissolution profile in the gastrointestinal (GI) tract, making it difficult to predict their oral absorption profile. The aim of this study was to investigate the utility of the Gastrointestinal Simulator (GIS), a novel in vivo predictive dissolution (iPD) methodology, in predicting the in vivo behavior of the weakly basic drug, dipyridamole, when coupled with in silico analysis. The GIS is a multi-compartmental dissolution apparatus, which represents physiological gastric emptying in the fasted state...
February 23, 2017: Molecular Pharmaceutics
Anbang Zhao, Lin Ma, Xuefei Ma, Juan Hui
In this paper, an improved azimuth angle estimation method with a single acoustic vector sensor (AVS) is proposed based on matched filtering theory. The proposed method is mainly applied in an active sonar detection system. According to the conventional passive method based on complex acoustic intensity measurement, the mathematical and physical model of this proposed method is described in detail. The computer simulation and lake experiments results indicate that this method can realize the azimuth angle estimation with high precision by using only a single AVS...
February 20, 2017: Sensors
Yan Wang, Jinbiao Fan, Jing Zu, Peng Xu
To solve the problem of resonance during quasi-static calibration of high-g accelerometers, we deduce the relationship between the minimum excitation pulse width and the resonant frequency of the calibrated accelerometer according to the second-order mathematical model of the accelerometer, and improve the quasi-static calibration theory. We establish a quasi-static calibration testing system, which uses a gas gun to generate high-g acceleration signals, and apply a laser interferometer to reproduce the impact acceleration...
February 20, 2017: Sensors
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"