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mathematical modeling

Qi Zheng
In around 1943, while writing a classic paper with Luria, Delbrück envisioned two kinds of mutation rates: One was expressed as mutations per bacterium per unit time, the other as mutations per bacterium per division cycle. Due to minor mathematical errors, the precise connection between the two concepts remained elusive for Delbrück. As a result, researchers and educators alike are still grappling with the definition of the mutation rate. Within the context of microbial mutation, the current author proposes an idealized model to bring new clarity to the distinction between the two forms of the mutation rate that Delbrück once attempted to define and characterize...
February 17, 2017: Bulletin of Mathematical Biology
Michelle Baker, Bindi S Brook, Markus R Owen
Osteoarthritis (OA) is a degenerative disease which causes pain and stiffness in joints. OA progresses through excessive degradation of joint cartilage, eventually leading to significant joint degeneration and loss of function. Cytokines, a group of cell signalling proteins, present in raised concentrations in OA joints, can be classified into pro-inflammatory and anti-inflammatory groups. They mediate cartilage degradation through several mechanisms, primarily the up-regulation of matrix metalloproteinases (MMPs), a group of collagen-degrading enzymes...
February 17, 2017: Journal of Mathematical Biology
Anna Angela Barba, Sara Cascone, Diego Caccavo, Gaetano Lamberti, Gianluca Chiarappa, Michela Abrami, Gabriele Grassi, Mario Grassi, Giovanna Tomaiuolo, Stefano Guido, Valerio Brucato, Francesco Carfì Pavia, Giulio Ghersi, Vincenzo La Carrubba, Roberto Andrea Abbiati, Davide Manca
siRNAs are very potent drug molecules, able to silence genes involved in pathologies development. siRNAs have virtually an unlimited therapeutic potential, particularly for the treatment of inflammatory diseases. However, their use in clinical practice is limited because of their unfavorable properties to interact and not to degrade in physiological environments. In particular they are large macromolecules, negatively charged, which undergo rapid degradation by plasmatic enzymes, are subject to fast renal clearance/hepatic sequestration, and can hardly cross cellular membranes...
February 14, 2017: International Journal of Pharmaceutics
Christine Janas, Marc-Philip Mast, Li Kirsamer, Carlo Angioni, Fiona Gao, Werner Mäntele, Jennifer Dressman, Matthias G Wacker
The dispersion releaser (DR) is a dialysis-based setup for the analysis of the drug release from nanosized drug carriers. It is mounted into dissolution apparatus2 of the United States Pharmacopoeia. The present study evaluated the DR technique investigating the drug release of the model compound flurbiprofen from drug solution and from nanoformulations composed of the drug and the polymer materials poly (lactic acid), poly (lactic-co-glycolic acid) or Eudragit(®)RSPO. The drug loaded nanocarriers ranged in size between 185...
February 14, 2017: European Journal of Pharmaceutics and Biopharmaceutics
C Chandra Mohan, K Radha Krishnan, S Babuskin, K Sudharsan, Vajiha Aafrin, U Lalitha Priya, P Mariyajenita, K Harini, D Madhushalini, M Sukumar
In the present study, mathematical models were used to examine the effect of active compound diffusion from edible film (supplemented with S. aromaticum and C. cassia) on the microbial, physical and chemical quality of mutton stored at 4 and 10°C. Cinnamaldehyde and eugenol release from edible film into liquid was found to be 80% and 75% of the equilibrium concentration. Active compound release into meat was 42-51% for cinnamaldehyde and 38-48% for eugenol, in storage temperatures of 4-15°C. Developed mathematical models showed the diffusivity of cinnamaldehyde (0...
February 5, 2017: Meat Science
Suppawong Tuarob, Conrad S Tucker, Soundar Kumara, C Lee Giles, Aaron L Pincus, David E Conroy, Nilam Ram
It is believed that anomalous mental states such as stress and anxiety not only cause suffering for the individuals, but also lead to tragedies in some extreme cases. The ability to predict the mental state of an individual at both current and future time periods could prove critical to healthcare practitioners. Currently, the practical way to predict an individual's mental state is through mental examinations that involve psychological experts performing the evaluations. However, such methods can be time and resource consuming, mitigating their broad applicability to a wide population...
February 14, 2017: Journal of Biomedical Informatics
Naomi Burke, Gerard Burke, Fionnuala Breathnach, Fionnuala Mcauliffe, John J Morrison, Michael Turner, Samina Dornan, John R Higgins, Amanda Cotter, Michael Geary, Peter Mcparland, Sean Daly, Fiona Cody, Pat Dicker, Elizabeth Tully, Fergal D Malone
BACKGROUND: In contemporary practice many nulliparous women require intervention during childbirth such as operative vaginal delivery or Cesarean delivery (CD). Despite the knowledge that the rising CD rate is associated with increasing maternal age, obesity and larger infant birthweight, we lack a reliable method to predict the requirement for such potentially hazardous obstetric procedures during labor and delivery. This issue is important as there are higher rates of morbidity and mortality associated with unplanned CD performed in labor compared to scheduled Cesarean deliveries...
February 14, 2017: American Journal of Obstetrics and Gynecology
Wenrui Hao, Shihua Gong, Shuonan Wu, Jinchao Xu, Michael R Go, Avner Friedman, Dai Zhu
Abdominal aortic aneurysm (AAA) is a localized enlargement of the abdominal aorta, such that the diameter exceeds 3 cm. The natural history of AAA is progressive growth leading to rupture, an event that carries up to 90% risk of mortality. Hence there is a need to predict the growth of the diameter of the aorta based on the diameter of a patient's aneurysm at initial screening and aided by non-invasive biomarkers. IL-6 is overexpressed in AAA and was suggested as a prognostic marker for the risk in AAA. The present paper develops a mathematical model which relates the growth of the abdominal aorta to the serum concentration of IL-6...
2017: PloS One
Jeong-In Hwang, Sung-Eun Lee, Jang-Eok Kim
Pesticides that persist in soils may be taken up by the roots of plants. One way to assess plant uptake is to theoretically predict the extent of plant uptake using a mathematical model. In this study, a model was developed to predict plant uptake of pesticide residues in soils using various parameters, such as pesticide mobility within soil, plant transpiration stream, root-soil transfer rate, plant growth, and pesticide dissipation in either soils or plants. The accuracy of the model was evaluated by comparing the modeled concentrations with measured uptake concentrations of chlorpyrifos (CP) in lettuce, grown on treated soils with concentrations of approximately 10 and 20 mg kg-1 CP...
2017: PloS One
Yun Xia, Shuangqian Yan, Xian Zhang, Peng Ma, Wei Du, Xiaojun Feng, Bi-Feng Liu
Digital loop-mediated isothermal amplification (dLAMP) is an attractive approach for absolute quantification of nucleic acids with high sensitivity and selectivity. Theoretical and numerical analysis of dLAMP provides necessary guidance for the design and analysis of dLAMP devices. In this work, a mathematical model was proposed based on Monte Carlo method and the theories of Poisson statistics and chemometrics. To examine the established model, we fabricated a spiral chip with 1200 uniform and discrete reaction chambers (9...
February 17, 2017: Analytical Chemistry
Lu Peng, Dumitru Trucu, Ping Lin, Alastair Thompson, Mark A J Chaplain
Known as one of the hallmarks of cancer (Hanahan and Weinberg in Cell 100:57-70, 2000) cancer cell invasion of human body tissue is a complicated spatio-temporal multiscale process which enables a localised solid tumour to transform into a systemic, metastatic and fatal disease. This process explores and takes advantage of the reciprocal relation that solid tumours establish with the extracellular matrix (ECM) components and other multiple distinct cell types from the surrounding microenvironment. Through the secretion of various proteolytic enzymes such as matrix metalloproteinases or the urokinase plasminogen activator (uPA), the cancer cell population alters the configuration of the surrounding ECM composition and overcomes the physical barriers to ultimately achieve local cancer spread into the surrounding tissue...
February 16, 2017: Bulletin of Mathematical Biology
Thomas Millat, Klaus Winzer
Clostridial acetone-butanol-ethanol (ABE) fermentation features a remarkable shift in the cellular metabolic activity from acid formation, acidogenesis, to the production of industrial-relevant solvents, solventogensis. In recent decades, mathematical models have been employed to elucidate the complex interlinked regulation and conditions that determine these two distinct metabolic states and govern the transition between them. In this review, we discuss these models with a focus on the mechanisms controlling intra- and extracellular changes between acidogenesis and solventogenesis...
February 16, 2017: Applied Microbiology and Biotechnology
M Eusebia Guerrero-Sánchez, D Alberto Mercado-Ravell, Rogelio Lozano, C Daniel García-Beltrán
This paper presents the problem of safe and fast transportation of packages by an Unmanned Aerial Vehicle (UAV) kind quadrotor. A mathematical model and a control strategy for a special class of underactuated mechanical systems, composed of a quadrotor transporting a cable-suspended payload, are proposed. The Euler-Lagrange formulation is used to obtain the dynamic model of the system, where the integrated dynamics of the quadrotor, cable and payload are considered. An Interconnection and Damping Assignment-Passivity Based Control (IDA-PBC) is chosen because of its inherent robustness against parametric uncertainty and unmodeled dynamics...
February 13, 2017: ISA Transactions
Manuel Gehlen, Vartan Kurtcuoglu, Marianne Schmid Daners
BACKGROUND: Postural changes are related to changes in cerebrospinal fluid (CSF) dynamics. While sitting up leads to a decrease in cranial CSF pressure, it also causes shifts in the craniospinal CSF volume and compliance distribution. We hypothesized that jugular vein collapse in upright posture is a major contributor to these shifts in CSF volume and compliance. METHODS: To test this hypothesis, we implemented a mathematical lumped-parameter model of the CSF system and the relevant parts of the cardiovascular system...
February 16, 2017: Fluids and Barriers of the CNS
Arkadiusz Jędrzejewski
We investigate the q-voter model with stochastic noise arising from independence on complex networks. Using the pair approximation, we provide a comprehensive, mathematical description of its behavior and derive a formula for the critical point. The analytical results are validated by carrying out Monte Carlo experiments. The pair approximation prediction exhibits substantial agreement with simulations, especially for networks with weak clustering and large average degree. Nonetheless, for the average degree close to q, some discrepancies originate...
January 2017: Physical Review. E
Felix Droste, Benjamin Lindner
The response properties of excitable systems driven by colored noise are of great interest, but are usually mathematically only accessible via approximations. For this reason, dichotomous noise, a rare example of a colored noise leading often to analytically tractable problems, has been extensively used in the study of stochastic systems. Here, we calculate exact expressions for the power spectrum and the susceptibility of a leaky integrate-and-fire neuron driven by asymmetric dichotomous noise. While our results are in excellent agreement with simulations, they also highlight a limitation of using dichotomous noise as a simple model for more complex fluctuations: Both power spectrum and susceptibility exhibit an undamped periodic structure, the origin of which we discuss in detail...
January 2017: Physical Review. E
Irina Ginzburg
The effect of the heterogeneity in the soil structure or the nonuniformity of the velocity field on the modeled resident time distribution (RTD) and breakthrough curves is quantified by their moments. While the first moment provides the effective velocity, the second moment is related to the longitudinal dispersion coefficient (k_{T}) in the developed Taylor regime; the third and fourth moments are characterized by their normalized values skewness (Sk) and kurtosis (Ku), respectively. The purpose of this investigation is to examine the role of the truncation corrections of the numerical scheme in k_{T}, Sk, and Ku because of their interference with the second moment, in the form of the numerical dispersion, and in the higher-order moments, by their definition...
January 2017: Physical Review. E
Yong Zhuang, Alex Arenas, Osman Yağan
We present the mathematical analysis of generalized complex contagions in a class of clustered multiplex networks. The model is intended to understand spread of influence, or any other spreading process implying a threshold dynamics, in setups of interconnected networks with significant clustering. The contagion is assumed to be general enough to account for a content-dependent linear threshold model, where each link type has a different weight (for spreading influence) that may depend on the content (e.g., product, rumor, political view) that is being spread...
January 2017: Physical Review. E
E Mema, L Kondic, L J Cummings
We consider a mathematical model that consists of a nematic liquid crystal layer sandwiched between two parallel bounding plates, across which an external field is applied. We investigate how the number and type of solutions for the director orientation within the layer change as the field strength, anchoring conditions, and material properties of the nematic liquid crystal layer vary. In particular, we focus on how the inclusion of flexoelectric effects alters the Freedericksz and saturation thresholds.
January 2017: Physical Review. E
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