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Mathematical model

Caetano Souto-Maior, Gabriel Sylvestre, Fernando Braga Stehling Dias, M Gabriela M Gomes, Rafael Maciel-de-Freitas
Infection is a complex and dynamic process involving a population of invading microbes, the host and its responses, aimed at controlling the situation. Depending on the purpose and level of organization, infection at the organism level can be described by a process as simple as a coin toss, or as complex as a multi-factorial dynamic model; the former, for instance, may be adequate as a component of a population model, while the latter is necessary for a thorough description of the process beginning with a challenge with an infectious inoculum up to establishment or elimination of the pathogen...
March 20, 2018: PLoS Neglected Tropical Diseases
Georg Jäger, Sebastian Zug, António Casimiro
The advent of cooperative systems entails a dynamic composition of their components. As this contrasts current, statically composed systems, new approaches for maintaining their safety are required. In that endeavor, we propose an integration step that evaluates the failure model of shared information in relation to an application's fault tolerance and thereby promises maintainability of such system's safety. However, it also poses new requirements on failure models, which are not fulfilled by state-of-the-art approaches...
March 20, 2018: Sensors
D B Krupp, Thomas R Cook
Inequality is widely believed to incite conflict, but the evidence is inconsistent. We argue that the spatial scale of competition-the extent to which individuals compete locally, with their interaction partners, or globally, with the entire population-can help settle the question. We built a mathematical model of the evolution of conflict under inequality and tested its predictions in an experimental game with 1,205 participants. We found that inequality increases conflict, destroys wealth, and engenders risk taking...
March 1, 2018: Psychological Science
María Lovato, José Real Buffelli, Mariana Abrile, Carlos Martín
The application of conventional physicochemical and microbiological techniques for the removal of organic pollutants has limitations for its utilization on wastewaters as landfill leachates because of their high concentration of not easily biodegradable organic compounds. The use of ozone-based technologies is an alternative and complementary treatment for this type of wastewaters. This paper reports the study of the degradation of landfill leachates from different stages of a treatment plant using ozone and ozone + UV...
March 19, 2018: Environmental Science and Pollution Research International
Nicole A Hynson, Kiana L Frank, Rosanna A Alegado, Anthony S Amend, Mohammad Arif, Gordon M Bennett, Andrea J Jani, Matthew C I Medeiros, Yuriy Mileyko, Craig E Nelson, Nhu H Nguyen, Olivia D Nigro, Sladjana Prisic, Sangwoo Shin, Daisuke Takagi, Samuel T Wilson, Joanne Y Yew
Despite increasing acknowledgment that microorganisms underpin the healthy functioning of basically all multicellular life, few cross-disciplinary teams address the diversity and function of microbiota across organisms and ecosystems. Our newly formed consortium of junior faculty spanning fields such as ecology and geoscience to mathematics and molecular biology from the University of Hawai'i at Mānoa aims to fill this gap. We are united in our mutual interest in advancing a new paradigm for biology that incorporates our modern understanding of the importance of microorganisms...
March 2018: MSystems
Miguel Ángel Lozada Aguilar, Andrei Khrennikov, Klaudia Oleschko
As was recently shown by the authors, quantum probability theory can be used for the modelling of the process of decision-making (e.g. probabilistic risk analysis) for macroscopic geophysical structures such as hydrocarbon reservoirs. This approach can be considered as a geophysical realization of Hilbert's programme on axiomatization of statistical models in physics (the famous sixth Hilbert problem). In this conceptual paper , we continue development of this approach to decision-making under uncertainty which is generated by complexity, variability, heterogeneity, anisotropy, as well as the restrictions to accessibility of subsurface structures...
April 28, 2018: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Jakob Rehrl, Anssi-Pekka Karttunen, Niels Nicolaï, Theresa Hörmann, Martin Horn, Ossi Korhonen, Ingmar Nopens, Thomas De Beer, Johannes G Khinast
One major advantage of continuous pharmaceutical manufacturing over traditional batch manufacturing is the possibility of enhanced in-process control, reducing out-of-specification and waste material by appropriate discharge strategies. The decision on material discharge can be based on the measurement of active pharmaceutical ingredient (API) concentration at specific locations in the production line via process analytic technology (PAT), e.g. near-infrared (NIR) spectrometers. The implementation of the PAT instruments is associated with monetary investment and the long term operation requires techniques avoiding sensor drifts...
March 16, 2018: International Journal of Pharmaceutics
Mengyi Zhao, Songmao Zhang, Weizhuo Li, Guowei Chen
BACKGROUND: The goal of ontology matching is to identify correspondences between entities from different yet overlapping ontologies so as to facilitate semantic integration, reuse and interoperability. As a well developed mathematical model for analyzing individuals and structuring concepts, Formal Concept Analysis (FCA) has been applied to ontology matching (OM) tasks since the beginning of OM research, whereas ontological knowledge exploited in FCA-based methods is limited. This motivates the study in this paper, i...
March 19, 2018: Journal of Biomedical Semantics
Agnes Beckmann, Yousef Heider, Marcus Stoffel, Bernd Markert
The underlying research work introduces a study of the mechanical properties of polycarbonate urethane (PCU), used in the construction of various medical devices. This comprises the discussion of a suitable material model, the application of elemental experiments to identify the related parameters and the numerical simulation of the applied experiments in order to calibrate and validate the mathematical model. In particular, the model of choice for the simulation of PCU response is the non-linear viscoelastic Bergström-Boyce material model, applied in the finite-element (FE) package Abaqus®...
March 9, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Rick J Jansen, Bruce H Alexander, Richard B Hayes, Anthony B Miller, Sholom Wacholder, Timothy R Church
When some individuals are screen-detected before the beginning of the study, but otherwise would have been diagnosed symptomatically during the study, this results in different case-ascertainment probabilities among screened and unscreened participants, referred to here as lead-time-biased case-ascertainment (LTBCA). In fact, this issue can arise even in risk-factor studies nested within a randomized screening trial; even though the screening intervention is randomly allocated to trial arms, there is no randomization to potential risk-factors and uptake of screening can differ by risk-factor strata...
2018: PloS One
Kanes Sucharitakul, Marie-Claude Boily, Dobromir Dimitrov, Kate M Mitchell
BACKGROUND: Many mathematical models have investigated the population-level impact of expanding antiretroviral therapy (ART), using different assumptions about HIV disease progression on ART and among ART dropouts. We evaluated the influence of these assumptions on model projections of the number of infections and deaths prevented by expanded ART. METHODS: A new dynamic model of HIV transmission among men who have sex with men (MSM) was developed, which incorporated each of four alternative assumptions about disease progression used in previous models: (A) ART slows disease progression; (B) ART halts disease progression; (C) ART reverses disease progression by increasing CD4 count; (D) ART reverses disease progression, but disease progresses rapidly once treatment is stopped...
2018: PloS One
Soroush Safaei, Pablo J Blanco, Lucas O Müller, Leif R Hellevik, Peter J Hunter
We propose a detailed CellML model of the human cerebral circulation that runs faster than real time on a desktop computer and is designed for use in clinical settings when the speed of response is important. A lumped parameter mathematical model, which is based on a one-dimensional formulation of the flow of an incompressible fluid in distensible vessels, is constructed using a bond graph formulation to ensure mass conservation and energy conservation. The model includes arterial vessels with geometric and anatomical data based on the ADAN circulation model...
2018: Frontiers in Physiology
Yu Xia, Xianghua Wen, Bing Zhang, Yunfeng Yang
Understanding diversity and assembly patterns of microbial communities in activated sludge (AS) is pivotal for addressing fundamental ecological questions and wastewater treatment engineering. Recent applications of molecular methods especially next generation sequencing (NGS) have led to the explosion of information about AS community diversity, including the identification of uncultured taxa, and characterization of low-abundance but environmentally important populations such as antibiotic resistant bacteria and pathogens...
March 15, 2018: Biotechnology Advances
Guantian Li, Fan Zhu
Quinoa starch granules are small (~0.5 to 3 μm) with potential for some food and other applications. To better exploit it as a new starch resource, this study reports the steady shear and dynamic oscillatory properties of 9 quinoa starches varying in composition and structure. Steady shear analysis shows that the flow curves could be well described by 4 selected mathematic models. Temperature sweep analysis reveals that the quinoa starch encounters a 4-stage process including 2 phase transitions. Structure-function relationship analysis showed that composition, and unit and internal chain length distribution of amylopectin have significant impact on the rheological properties (e...
March 15, 2018: International Journal of Biological Macromolecules
Chenju Yi, Jérémy Theillon, Annette Koulakoff, Hugues Berry, Christian Giaume
Intercellular communication through gap junction channels plays a key role in cellular homeostasis and in synchronizing physiological functions, a feature that is modified in number of pathological situations. In the brain, astrocytes are the cell population that expresses the highest amount of gap junction proteins, named connexins. Several techniques have been used to assess the level of gap junctional communication in astrocytes, but so far they remain very difficult to apply in adult brain tissue. Here, using specific loading of astrocytes with sulforhodamine 101, we adapted the gap-FRAP (Fluorescence Recovery After Photobleaching) to acute hippocampal slices from 9 month-old adult mice...
March 15, 2018: Journal of Neuroscience Methods
D Cingolani, F Fatone, N Frison, M Spinelli, A L Eusebi
Recovery of high quality water from municipal landfill leachate was studied by three-stage disc tube reverse osmosis optimized in pilot-scale. Following UF-membrane-assisted activated sludge plant, overall 46.5 tons of leachate were post-treated in real environment and analyzed for conventional contaminants and hazardous compounds (e.g. heavy metals, boron, selenium) throughout operation of membrane system. Operating pressure ranged from 21 to 76 bar, while permeate flux varied in the range 7.1-32.5 L m-2  h-1 ...
March 15, 2018: Waste Management
Mehran Mazandarani, Naser Pariz
This paper deals with sub-optimal control of a fuzzy linear dynamical system. The aim is to keep the state variables of the fuzzy linear dynamical system close to zero in an optimal manner. In the fuzzy dynamical system, the fuzzy derivative is considered as the granular derivative; and all the coefficients and initial conditions can be uncertain. The criterion for assessing the optimality is regarded as a granular integral whose integrand is a quadratic function of the state variables and control inputs. Using the relative-distance-measure (RDM) fuzzy interval arithmetic and calculus of variations, the optimal control law is presented as the fuzzy state variables feedback...
March 16, 2018: ISA Transactions
Yao Li, Zhiqiang Yue, Hua Yu, Xiaojian Liu, Li Tao, Zhijie Zhu, Fangtian Fan, Cunsi Shen, Aiyun Wang, Wenxing Chen, Yin Lu
PURPOSE: A computational model based on clinical data from pancreatic cancer patients has been successfully created and used for predicting tumor sizes in primary and metastasis sites and survival time from kinetics of tumor cells, such as growth rate, metastasis rate and mutation rate, etc. Whether this computational model could be fitted or necessary modification of some parameters for fitting in mice is unknown. Here, we developed a computational model in mice for spontaneous metastasis to simulate the process of tumor metastasis based on the mathematical frameworks...
March 14, 2018: Journal of Pharmacological and Toxicological Methods
Clement Aldebert, Bob W Kooi, David Nerini, Jean-Christophe Poggiale
Many current issues in ecology require predictions made by mathematical models, which are built on somewhat arbitrary choices. Their consequences are quantified by sensitivity analysis to quantify how changes in model parameters propagate into an uncertainty in model predictions. An extension called structural sensitivity analysis deals with changes in the mathematical description of complex processes like predation. Such processes are described at the population scale by a specific mathematical function taken among similar ones, a choice that can strongly drive model predictions...
March 14, 2018: Journal of Theoretical Biology
Tanja Stadler, Alexandra Gavryushkina, Rachel C M Warnock, Alexei J Drummond, Tracy A Heath
A birth-death-sampling model gives rise to phylogenetic trees with samples from the past and the present. Interpreting "birth" as branching speciation, "death" as extinction, and "sampling" as fossil preservation and recovery, this model - also referred to as the fossilized birth-death (FBD) model - gives rise to phylogenetic trees on extant and fossil samples. The model has been mathematically analyzed and successfully applied to a range of datasets on different taxonomic levels, such as penguins, plants, and insects...
March 14, 2018: Journal of Theoretical Biology
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