Read by QxMD icon Read

mathematical modeling

Tatjana Trcek, Samir Rahman, Daniel Zenklusen
Cellular mRNA levels are determined by the rates of mRNA synthesis and mRNA decay. Typically, mRNA degradation kinetics are measured on a population of cells that are either chemically treated or genetically engineered to inhibit transcription. However, these manipulations can affect the mRNA decay process itself by inhibiting regulatory mechanisms that govern mRNA degradation, especially if they occur on short time-scales. Recently, single molecule fluorescent in situ hybridization (smFISH) approaches have been implemented to quantify mRNA decay rates in single, unperturbed cells...
2018: Methods in Molecular Biology
Daniel Câmara De Souza, Morgan Craig, Tyler Cassidy, Jun Li, Fahima Nekka, Jacques Bélair, Antony R Humphries
A comparison of the transit compartment ordinary differential equation modelling approach to distributed and discrete delay differential equation models is studied by focusing on Quartino's extension to the Friberg transit compartment model of myelosuppression, widely relied upon in the pharmaceutical sciences to predict the neutrophil response after chemotherapy, and on a QSP delay differential equation model of granulopoiesis. An extension to the Quartino model is provided by considering a general number of transit compartments and introducing an extra parameter that allows for the decoupling of the maturation time from the production rate of cells...
December 13, 2017: Journal of Pharmacokinetics and Pharmacodynamics
Shuai Shi, Zheng You, Kaichun Zhao, Zhaoyao Wang, Chenguang Ouyang, Yongkui Cao
To achieve six degree-of-freedom autonomous navigation of an inboard spacecraft, a novel algorithm called iterative closest imaging point (ICIP) is proposed, which deals with the pose estimation problem of a vision navigation system (VNS). This paper introduces the basics of the ICIP algorithm, including mathematical model, algorithm architecture, and convergence theory. On this basis, a navigation method is proposed. This method realizes its initialization using a Gaussian mixture model-based Kalman filter, which simultaneously solves the 3D-to-2D point correspondences and the camera pose...
December 12, 2017: Scientific Reports
Stephanie Nelli, Sirawaj Itthipuripat, Ramesh Srinivasan, John T Serences
Rhythmic neural activity in the alpha band (8-13 Hz) is thought to have an important role in the selective processing of visual information. Typically, modulations in alpha amplitude and instantaneous frequency are thought to reflect independent mechanisms impacting dissociable aspects of visual information processing. However, in complex systems with interacting oscillators such as the brain, amplitude and frequency are mathematically dependent. Here, we record electroencephalography in human subjects and show that both alpha amplitude and instantaneous frequency predict behavioral performance in the same visual discrimination task...
December 12, 2017: Nature Communications
Weini Huang, Arne Traulsen, Benjamin Werner, Teppo Hiltunen, Lutz Becks
Trade-offs play an important role in evolution. Without trade-offs, evolution would maximize fitness of all traits leading to a "master of all traits". The shape of trade-offs has been shown to determine evolutionary trajectories and is often assumed to be static and independent of the actual evolutionary process. Here we propose that coevolution leads to a dynamical trade-off. We test this hypothesis in a microbial predator-prey system and show that the bacterial growth-defense trade-off changes from concave to convex, i...
December 12, 2017: Nature Communications
Shigeyuki Magi, Kazunari Iwamoto, Noriko Yumoto, Michio Hiroshima, Takeshi Nagashima, Rieko Ohki, Amaya Garcia-Munoz, Natalia Volinsky, Alexander von Kriegsheim, Yasushi Sako, Koichi Takahashi, Shuhei Kimura, Boris N Kholodenko, Mariko Okada-Hatakeyama
Feedback control is a key mechanism in signal transduction, intimately involved in regulating the outcome of the cellular response. Here we report a novel mechanism by which PHLDA1, Pleckstrin homology-like domain, family A, member 1, negatively regulates ErbB receptor signaling by inhibition of receptor oligomerization. We have found that the ErbB3 ligand, heregulin, induces PHILDA1 expression in MCF-7 cells. Transcriptionally-induced PHLDA1 protein directly binds to ErbB3, while knockdown of PHLDA1 increases complex formation between ErbB3 and ErbB2...
December 12, 2017: Journal of Biological Chemistry
M E Duarte-González, O Y Echeverri, J M Guevara, R Palazzo
The organization of the genetic information and its ability to be conserved and translated to proteins with low error rates have been the subject of study by scientists from different disciplines. Recently, it has been proposed that living organisms display an intra-cellular transmission system of genetic information, similar to a model of digital communication system, in which there is the ability to detect and correct errors. In this work, the concept of Concatenated Genetic Encoder is introduced and applied to the analysis of protein sequences as a tool for exploring evolutionary relationships...
December 9, 2017: Bio Systems
Dongping Zeng, Yong Kang, Lu Xie, Xiaoxiao Xia, Zefeng Wang, Wenchuan Liu
Needle-free injection, as an alternative drug delivery strategy, owns great potential. It is able to reduce complaints about needle phobia and avoid the occurring of accidental needle stick injuries. The nozzle diameter is inherently important in determining the injection dose, injection depth and pain associated with needle-free injections. In this work, needle-free injectors with nozzle diameters of 0.17 mm, 0.20 mm, 0.30 mm, 0.40mm, 0.50 mm were studied in the simulation and experiment. This paper optimizes the mathematical model for spring powered needle-free injection by considering the hydraulic loss due to the abrupt change in the nozzle exit area and the friction force between the piston and ampoule...
December 9, 2017: Journal of Pharmaceutical Sciences
Susan E Luczak, Ashley L Hawkins, Zheng Dai, Raphael Wichmann, Chunming Wang, I Gary Rosen
Biosensors have been developed to measure transdermal alcohol concentration (TAC), but converting TAC into interpretable indices of blood/breath alcohol concentration (BAC/BrAC) is difficult because of variations that occur in TAC across individuals, drinking episodes, and devices. We have developed mathematical models and the BrAC Estimator software for calibrating and inverting TAC into quantifiable BrAC estimates (eBrAC). The calibration protocol to determine the individualized parameters for a specific individual wearing a specific device requires a drinking session in which BrAC and TAC measurements are obtained simultaneously...
December 2, 2017: Addictive Behaviors
Renée Dagenais, Arden R Barry, Mary H H Ensom
BACKGROUND AND PURPOSE: To determine whether an analogy relating a city bus to the well-stirred model for high extraction drugs administered intravenously improves pharmacy students' self-perceived and objectively-assessed understanding. EDUCATIONAL ACTIVITY AND SETTING: Fifty-two entry-to-practice pharmacy students enrolled in an elective clinical pharmacokinetics course completed a questionnaire and quiz before and after the bus analogy presentation. Pre- and post test questionnaires consisted of five items measuring (on five-point unipolar scale) students' self-perceived understanding of the model...
July 2017: Currents in Pharmacy Teaching & Learning
Holly M Hasler, Natacha Akshoomoff
Children born very preterm (VPT) are at risk for academic, behavioral, and/or emotional problems. Mathematics is a particular weakness and better understanding of the relationship between preterm birth and early mathematics ability is needed, particularly as early as possible to aid in early intervention. Preschoolers born VPT (n = 58) and those born full term (FT; n = 29) were administered a large battery of measures within 6 months of beginning kindergarten. A multiple-mediation model was utilized to characterize the difference in skills underlying mathematics ability between groups...
December 12, 2017: Child Neuropsychology: a Journal on Normal and Abnormal Development in Childhood and Adolescence
Ulf Träff, Linda Olsson, Kenny Skagerlund, Rickard Östergren
A modified pathways to mathematics model was used to examine the cognitive mechanisms underlying arithmetic skills in third graders. A total of 269 children were assessed on tasks tapping the four pathways and arithmetic skills. A path analysis showed that symbolic number processing was directly supported by the linguistic and approximate quantitative pathways. The direct contribution from the four pathways to arithmetic proficiency varied; the linguistic pathway supported single-digit arithmetic and word problem solving, whereas the approximate quantitative pathway supported only multi-digit calculation...
December 9, 2017: Journal of Experimental Child Psychology
Leigh F Johnson, Margaret T May, Rob E Dorrington, Morna Cornell, Andrew Boulle, Matthias Egger, Mary-Ann Davies
BACKGROUND: Substantial reductions in adult mortality have been observed in South Africa since the mid-2000s, but there has been no formal evaluation of how much of this decline is attributable to the scale-up of antiretroviral treatment (ART), as previous models have not been calibrated to vital registration data. We developed a deterministic mathematical model to simulate the mortality trends that would have been expected in the absence of ART, and with earlier introduction of ART. METHODS AND FINDINGS: Model estimates of mortality rates in ART patients were obtained from the International Epidemiology Databases to Evaluate AIDS-Southern Africa (IeDEA-SA) collaboration...
December 2017: PLoS Medicine
Tom H Williamson, Jean-Yves Guillemaut, Sheldon K Hall, Joseph C Hutter, Tony Goddard
PURPOSE: To determine the concentrations of different gas tamponades in air to achieve 100% fill of the vitreous cavity postoperatively and to examine the influence of eye volume on these concentrations. METHODS: A mathematical model of the mass transfer dynamics of tamponade and blood gases (O2, N2, and CO2) when injected into the eye was used. Mass transfer surface areas were calculated from published anatomical data. The model has been calibrated from published volumetric decay and composition results for three gases sulphahexafluoride (SF6), hexafluoroethane (C2F6), or perfluoropropane (C3F8)...
December 11, 2017: Retina
Hui Du, Xiaobo Chen, Juntong Xi, Chengyi Yu, Bao Zhao
Large-scale surfaces are prevalent in advanced manufacturing industries, and 3D profilometry of these surfaces plays a pivotal role for quality control. This paper proposes a novel and flexible large-scale 3D scanning system assembled by combining a robot, a binocular structured light scanner and a laser tracker. The measurement principle and system construction of the integrated system are introduced. A mathematical model is established for the global data fusion. Subsequently, a robust method is introduced for the establishment of the end coordinate system...
December 12, 2017: Sensors
Ziyi Yang, Mengyuan Zhou, Xing Wang, Yunyun Zhao, Zhifeng Chen, Yi Lan, Tao Xu, Yu Zhao, Ling Zhao
We retrieve and analyze the articles on body surface temperature of acupoints in the recent 50 years. Surface temperatures have been compared between acupoints and nonacupoints, and among acupoints in different states. The impacts of interventions for acupoint temperature are explored, including acupuncture,moxibustion and cupping, etc. We summarize the features and the rules of acupoint skin temperature. It is considered that there exists distribution rule for healthy people's acupoint skin temperature. That means acupoints have higher surface temperature than nonacupoints...
January 12, 2017: Zhongguo Zhen Jiu, Chinese Acupuncture & Moxibustion
Wenjuan Cai, Yongshuai Li, Fei Liu, Jianwen Luo
OBJECTIVE: Accurate evaluation of the degree of hindlimb ischemia is challenging but essential for the diagnosis and treatment of peripheral vascular insufficiency. The aim of the study is to apply a multiparametric method for the quantitative estimation of mouse models with different degrees of hindlimb ischemia based on a dynamic fluorescence imaging-based strategy. APPROACH: An adjustable hydraulic occluder was placed around the thigh root of one hindlimb to induce six different degrees of hindlimb ischemia...
December 12, 2017: Physiological Measurement
Hai V Pham-The, Nguyen-Hai Nam, Doan-Viet Nga, Dang Thanh Hai, Karel Dieguez-Santana, Yovani Marrero-Poncee, Juan A Castillo-Garit, Gerardo M Casanola-Martin, Huong Le-Thi-Thu
Quantitative Structure - Activity Relationship (QSAR) modeling has been widely used in medicinal chemistry and computational toxicology for many years. Today, as the amount of data on chemicals is increasing dramatically, QSAR methods have become pivotal for the purpose of handling the data, identifying a decision, and gathering useful information from data processing. The advances in this field have paved a way for numerous alternative approaches that require deep mathematics in order to enhance the learning capability of QSAR models...
December 11, 2017: Current Topics in Medicinal Chemistry
Mika Naganawa, Jean-Dominique Gallezot, Samantha Rossano, Richard E Carson
Positron emission tomography, an imaging tool using radiolabeled tracers in humans and preclinical species, has been widely used in recent years in drug development, particularly in the central nervous system. One important goal of PET in drug development is assessing the occupancy of various molecular targets (e.g., receptors, transporters, enzymes) by exogenous drugs. The current linear mathematical approaches used to determine occupancy using PET imaging experiments are presented. These algorithms use results from multiple regions with different target content in two scans, a baseline (pre-drug) scan and a post-drug scan...
December 11, 2017: Bulletin of Mathematical Biology
A Demetri Pananos, Thomas M Bury, Clara Wang, Justin Schonfeld, Sharada P Mohanty, Brendan Nyhan, Marcel Salathé, Chris T Bauch
Vaccine refusal can lead to renewed outbreaks of previously eliminated diseases and even delay global eradication. Vaccinating decisions exemplify a complex, coupled system where vaccinating behavior and disease dynamics influence one another. Such systems often exhibit critical phenomena-special dynamics close to a tipping point leading to a new dynamical regime. For instance, critical slowing down (declining rate of recovery from small perturbations) may emerge as a tipping point is approached. Here, we collected and geocoded tweets about measles-mumps-rubella vaccine and classified their sentiment using machine-learning algorithms...
December 11, 2017: Proceedings of the National Academy of Sciences of the United States of America
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"