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Mathematical modelling

Yong Hu, Hai-Long Wu, Xiao-Li Yin, Hui-Wen Gu, Rong Xiao, Li-Xia Xie, Zhi Liu, Huan Fang, Li Wang, Ru-Qin Yu
The aim of the present work was to develop a rapid and interference-free method based on liquid chromatography-mass spectrometry (LC-MS) for the simultaneous determination of nine B-group vitamins in various energy drinks. A smart and green strategy that modeled the three-way data array of LC-MS with second-order calibration methods based on alternating trilinear decomposition (ATLD) and alternating penalty trilinear decomposition (APTLD) algorithms was developed. By virtue of "mathematical separation" and "second-order advantage", the proposed strategy successfully solved the co-eluted peaks and unknown interferents in LC-MS analysis with the elution time less than 4...
April 1, 2018: Talanta
Willi Cawello, Marina Braun, Jens-Otto Andreas
BACKGROUND AND OBJECTIVE: Pharmacokinetic studies using deconvolution methods and non-compartmental analysis to model clinical absorption of drugs are not well represented in the literature. The purpose of this research was (1) to define the system of equations for description of rotigotine (a dopamine receptor agonist delivered via a transdermal patch) absorption based on a pharmacokinetic model and (2) to describe the kinetics of rotigotine disposition after single and multiple dosing...
January 13, 2018: European Journal of Drug Metabolism and Pharmacokinetics
Fan He, P M Biesheuvel, Martin Z Bazant, T Alan Hatton
Capacitive deionization (CDI) for water treatment, which relies on the capture of charged species to sustain the electrical double layers (EDLs) established within porous electrodes under an applied electrical potential, can be enhanced by the chemical attachment of fixed charged groups to the porous electrode electrodes (ECDI). It has recently been demonstrated that further improvements in capacity and energy storage can be gained by functionalization of the electrode surfaces with redox polymers in which the charge on the electrodes can be modulated through Faradaic reactions under different cell voltages in a capacitive process that can be called "Faradaic CDI" (FaCDI)...
January 3, 2018: Water Research
Charles Whittaker, Martin Walker, Sébastien D S Pion, Cédric B Chesnais, Michel Boussinesq, María-Gloria Basáñez
Endemic to Central Africa, loiasis - or African eye worm (caused by the filarial nematode Loa loa) - affects more than 10 million people. Despite causing ocular and systemic symptoms, it has typically been considered a benign condition, only of public health relevance because it impedes mass drug administration-based interventions against onchocerciasis and lymphatic filariasis in co-endemic areas. Recent research has challenged this conception, demonstrating excess mortality associated with high levels of infection, implying that loiasis warrants attention as an intrinsic public health problem...
January 10, 2018: Trends in Parasitology
Jaydeep Sinha, Stephen B Duffull, Hesham S Al-Sallami
Fat-free mass (FFM) represents the lean component of the body devoid of fat. It has been shown to be a useful predictor of drug dose requirements, particularly in obesity where the excess fat mass does not contribute to drug clearance. However, measuring FFM involves complex and/or expensive experimental methodologies that preclude their use in routine clinical practice. Thus, models to predict FFM from readily measurable variables, such as body weight and height, have been developed and are used in both population pharmacokinetic modelling and clinical practice...
January 12, 2018: Clinical Pharmacokinetics
Richard J Lindsay, Bogna J Pawlowska, Ivana Gudelj
Microbial cooperation drives ecological and epidemiological processes and is affected by the ecology and demography of populations. Population density influences the selection for cooperation, with spatial structure and the type of social dilemma, namely public-goods production or self-restraint, shaping the outcome. While existing theories predict that in spatially structured environments increasing population density can select either for or against cooperation, experimental studies with both public-goods production and self-restraint systems have only ever shown that increasing population density favours cheats...
January 12, 2018: ISME Journal
Jaruwan Marudkla, Wen-Chien Lee, Siwaporn Wannawilai, Yusuf Chisti, Sarote Sirisansaneeyakul
Acetic acid, a potential growth inhibitor, commonly occurs in lignocellulosic hydrolysates. The growth of Cupriavidus necator DSM 545 and production of poly(3-hydroxybutyrate) (PHB) by this bacterium in a glucose-based medium supplemented with various initial concentrations of acetic acid are reported. The bacterium could use both glucose and acetic acid to grow and produce PHB, but acetic acid inhibited growth once its initial concentration exceeded 0.5 g/L. As acetic acid is an unavoidable contaminant in hydrolysates used as sugar sources in commercial fermentations, a mathematical model was developed to describe its impact on growth and the production of PHB...
January 9, 2018: Journal of Biotechnology
Jonay Toledo, Jose D Piñeiro, Rafael Arnay, Daniel Acosta, Leopoldo Acosta
In this paper, a study of the odometric system for the autonomous cart Verdino, which is an electric vehicle based on a golf cart, is presented. A mathematical model of the odometric system is derived from cart movement equations, and is used to compute the vehicle position and orientation. The inputs of the system are the odometry encoders, and the model uses the wheels diameter and distance between wheels as parameters. With this model, a least square minimization is made in order to get the nominal best parameters...
January 12, 2018: Sensors
Ke Xu, Roger Bonnecaze, Matthew Balhoff
We show that smaller gas bubbles grow at the expense of larger bubbles and all bubbles approach the same surface curvature after long times in porous media. This anticoarsening effect is contrary to typical Ostwald ripening and leads to uniformly sized bubbles in a homogeneous medium. Evolution dynamics of bubble populations were measured, and mathematical models were developed that fit the experimental data well. Ostwald ripening is shown to be the driving mechanism in this anticoarsening phenomenon; however, the relationship between surface curvature and bubble size determined by the pore-throat geometric confinement reverses the ripening direction...
December 29, 2017: Physical Review Letters
Ana-Hermina Ghenu, Alexandre Blanckaert, Roger K Butlin, Jonna Kulmuni, Claudia Bank
In many diploid species the sex chromosomes play a special role in mediating reproductive isolation. In haplodiploids, where females are diploid and males haploid, the whole genome behaves similarly to the X/Z chromosomes of diploids. Therefore, haplodiploid systems can serve as a model for the role of sex chromosomes in speciation and hybridization. A previously described population of Finnish Formica wood ants displays genome-wide signs of ploidally and sexually antagonistic selection resulting from hybridization...
January 12, 2018: Molecular Ecology
Enzheng Zhang, Benyong Chen, Hao Zheng, Liping Yan, Xueying Teng
A laser heterodyne interferometer with rotational error compensation is proposed for precision displacement measurement. In this interferometer, the rotational error of the measured object is obtained by using an angle detecting unit which is composed of a semi-reflective film, a polarizing beam splitter, a quarter-wave plate, a convex lens and a two-dimensional position sensitive detector. And the obtained rotational angle is used for compensating its influence on displacement measurement result. The optical configuration of the proposed interferometer is designed, and the mathematical model for displacement measurement with rotational error compensation is established...
January 8, 2018: Optics Express
Omnia M Nawwar, Hossam M H Shalaby, Ramesh K Pokharel
A strip waveguide-based bi-directional mode-division multiplexer is proposed. A mathematical model has been proposed to analyze the performance, and the results are simulated. The design concept of this device to (de)multiplex three modes simultaneously has been studied previously for slab waveguides, both mathematically using the perturbative mode-coupled theory and by simulation using 2D FDTD Solutions (FDTD, finite difference time domain). As slab waveguides are not suitable for extracting fabrication parameters for most silicon-on-insulator applications, we apply the concept to a more practical device that involves strip waveguides rather than slab waveguides...
January 1, 2018: Applied Optics
O Fleck, T Savin
Blood occlusions in the retinal microvasculature contribute to the pathology of many disease states within the eye. These events can cause haemorrhaging and retinal detachment, leading to a loss of vision in the affected patient. Here, we present a physical approach to characterising the collective cell dynamics leading to plug formation, through the use of a bespoke microfluidic device, and through the derivation of a probabilistic model. Our microfluidic device is based on a filtration design that can tune the particle volume fraction of a flowing suspension within a conduit, with sizes similar to arterioles...
January 12, 2018: Eye
Ben B Hui, Caitlin P Reulein, Rebecca J Guy, Basil Donovan, Jane S Hocking, Matthew G Law, David G Regan
OBJECTIVES: Trichomonas vaginalis (TV) is the most common curable STI worldwide and is associated with increased risk of HIV acquisition and serious reproductive morbidities. The prevalence of TV infection is very low in Australian cities, and this is thought to be at least partly due to incidental detection and treatment of TV in women participating in the cervical cytology screening programme. In 2017, the national cervical screening programme will transition to a new model based on testing for high-risk (HR) human papillomavirus (HPV), with a reduced frequency and commencement at an older age...
January 11, 2018: Sexually Transmitted Infections
Ravi Vaidyanathan, Hanora Van Ert, Kazi T Haq, Stefano Morotti, Samuel Esch, Elise C McCune, Eleonora Grandi, Lee L Eckhardt
BACKGROUND: In human cardiac ventricle, IK1 is mainly comprised Kir2.1, but Kir2.2 and Kir2.3 heterotetramers occur and modulate IK1. Long-QT syndrome-9-associated CAV3 mutations cause decreased Kir2.1 current density, but Kir2.x heterotetramers have not been studied. Here, we determine the effect of long-QT syndrome-9-CAV3 mutation F97C on Kir2.x homo- and heterotetramers and model-associated arrhythmia mechanisms. METHODS AND RESULTS: Super-resolution microscopy, co-immunoprecipitation, cellular electrophysiology, on-cell Western blotting, and simulation of Purkinje and ventricular myocyte mathematical models were used...
January 2018: Circulation. Arrhythmia and Electrophysiology
Guoxin Hu, Junwei Li, Yuanyuan Shan, Xiaoheng Li, Qiqi Zhu, Huitao Li, Yiyan Wang, Xiaofang Chen, Qingquan Lian, Ren-Shan Ge
Phthalate diesters, including di-(2-ethylhexyl) phthalate (DEHP) and diethyl phthalate (DEP), are chemicals to which humans are ubiquitously exposed. Humans are exposed simultaneously to multiple environmental chemicals, including DEHP and DEP. There is little information available about how each chemical may interact to each other if they were exposed at same time. The present study investigated effects of the combinational exposure of rats to DEP and DEHP on fetal Leydig cell development. The results showed that the gestational (GD12-20) exposure of DEP + DEHP resulted in synergistic and/or dose-additive effects on the development of fetal Leydig cell...
January 8, 2018: Toxicology
Ling Liu, Yuliang Cheng, Xiulan Sun, Fuwei Pi
Near-infrared (NIR) spectroscopy as a tool for direct and quantitatively screening the minute polymorphic transitions of bioactive fatty acids was assessed basing on a thermal heating process of oleic acid. Temperature-dependent NIR spectral profiles indicate that dynamical variances of COOH group dominate its γ → α phase transition, while the transition from active α to β phase mainly relates to the conformational transfer of acyl chain. Through operating multivariate curve resolution-alternating least squares with factor analysis, instantaneous contribution of each active polymorph during the transition process was illustrated for displaying the progressive evolutions of functional groups...
January 6, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Jan Poleszczuk, Malgorzata Debowska, Wojciech Dabrowski, Alicja Wojcik-Zaluska, Wojciech Zaluska, Jacek Waniewski
Cardiovascular diseases are the leading cause of death worldwide. Pulse wave analysis (PWA) technique, which reconstructs and analyses aortic pressure waveform based on non-invasive peripheral pressure recording, became an important bioassay for cardiovascular assessment in a general population. The aim of our study was to establish a pulse wave propagation modeling framework capable of matching clinical PWA data from healthy individuals on a per-subject basis. Radial pressure profiles from 20 healthy individuals (10 males, 10 females), with mean age of 42 ± 10 years, were recorded using applanation tonometry (SphygmoCor, AtCor Medical, Australia) and used to estimate subject-specific parameters of mathematical model of blood flow in the system of fifty-five arteries...
2018: PloS One
Eri Yamada, Shinji Nakaoka, Lukas Klein, Elisabeth Reith, Simon Langer, Kristina Hopfensperger, Shingo Iwami, Gideon Schreiber, Frank Kirchhoff, Yoshio Koyanagi, Daniel Sauter, Kei Sato
The HIV-1-encoded accessory protein Vpu exerts several immunomodulatory functions, including counteraction of the host restriction factor tetherin, downmodulation of CD4, and inhibition of NF-κB activity to facilitate HIV-1 infection. However, the relative contribution of individual Vpu functions to HIV-1 infection in vivo remained unclear. Here, we used a humanized mouse model and HIV-1 strains with selective mutations in vpu to demonstrate that the anti-tetherin activity of Vpu is a prerequisite for efficient viral spread during the early phase of infection...
January 10, 2018: Cell Host & Microbe
Niels Waller
Kristof's Theorem (Kristof, 1970 ) describes a matrix trace inequality that can be used to solve a wide-class of least-square optimization problems without calculus. Considering its generality, it is surprising that Kristof's Theorem is rarely used in statistics and psychometric applications. The underutilization of this method likely stems, in part, from the mathematical complexity of Kristof's ( 1964 , 1970 ) writings. In this article, I describe the underlying logic of Kristof's Theorem in simple terms by reviewing four key mathematical ideas that are used in the theorem's proof...
January 11, 2018: Multivariate Behavioral Research
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