1,869,679 results match your criteria mathematical model


Scenario analysis of COVID-19 transmission dynamics in Malaysia with the possibility of reinfection and limited medical resources scenarios.

Comput Biol Med 2021 Apr 7;133:104372. Epub 2021 Apr 7.

Nano-Optoelectronics Research and Technology Lab (NORLab), School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia.

COVID-19 is a major health threat across the globe, which causes severe acute respiratory syndrome (SARS), and it is highly contagious with significant mortality. In this study, we conduct a scenario analysis for COVID-19 in Malaysia using a simple universality class of the SIR system and extensions thereof (i.e. Read More

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Implications of component size and calibration error on digital templating for total hip arthroplasty. A visual matrix from a simple mathematical model.

Int J Comput Assist Radiol Surg 2021 Apr 17. Epub 2021 Apr 17.

Division of Orthopaedics, Department of Trauma and Orthopaedic Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

Objective: Preoperative digital templating is a standard procedure in total hip arthroplasty. Deviations between template size and final implant size may result from inaccurate calibration, templating as well as intraoperative decisions. So far, the explicit effect of calibration errors on templating has not been addressed adequately. Read More

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Inferring Metal Binding Sites in Flexible Regions of Proteins.

Proteins 2021 Apr 17. Epub 2021 Apr 17.

Department of Computational and Data Sciences, Indian Institute of Science, Bengaluru, India.

Metal ions are central to the molecular function of many proteins. Thus their knowledge in experimentally determined structure is important; however, such structures often lose bound metal ions during sample preparation. Identification of these metal-binding site(s) becomes difficult when the receptor is novel and/or their conformations differ in the bound/unbound states. Read More

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A universal route to explosive phenomena.

Sci Adv 2021 Apr 16;7(16). Epub 2021 Apr 16.

Department of Mathematics, University of Exeter, Exeter, UK.

Critical transitions are observed in many complex systems. This includes the onset of synchronization in a network of coupled oscillators or the emergence of an epidemic state within a population. "Explosive" first-order transitions have caught particular attention in a variety of systems when classical models are generalized by incorporating additional effects. Read More

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A mathematical model to investigate heat transfer in footwear during walking and jogging.

J Therm Biol 2021 Apr 13;97:102778. Epub 2020 Nov 13.

Centre for Biomechanics and Rehabilitation Technologies, Staffordshire University, Leek Road, Stoke on Trent ST4 2DF, UK.

Foot temperature during activities of daily living affects the human performance and well-being. Footwear thermal characteristics affect the foot temperature inside the shoe during activities of daily living. The temperate at the sole of the foot (plantar temperature) is influenced by different thermal properties such as heat capacity, heat diffusivity, and thermal conductivity of the shoe sole in addition to its mechanical properties. Read More

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Comparison of two mathematical models for predicted human thermal responses to hot and humid environments.

J Therm Biol 2021 Apr 11;97:102902. Epub 2021 Mar 11.

LDM Associates, San Jose, CA, USA. Electronic address:

Purpose: We compared the accuracy and design of two thermoregulatory models, the US Army's empirically designed Heat Strain Decision Aid (HSDA) and the rationally based Health Risk Prediction (HRP) for predicting human thermal responses during exercise in hot and humid conditions and wearing chemical protective clothing.

Methods: Accuracy of the HSDA and HRP model predictions of core body and skin temperature (Tc, Ts) were compared to each other and relative to measured outcomes from eight male volunteers (age 24 ± 6 years; height 178 ± 5 cm; body mass 76.6 ± 8. Read More

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Temperature-based phenology model to predict the development, survival, and reproduction of the oriental fruit fly Bactrocera dorsalis.

J Therm Biol 2021 Apr 25;97:102877. Epub 2021 Feb 25.

International Institute of Tropical Agriculture (IITA), BP 2008 (Messa), Yaoundé, Cameroon.

The oriental fruit fly Bactrocera dorsalis (Diptera: Tephritidae) is a major pest of fruit and vegetable production systems on several continents. The pest has invaded many countries, causing considerable impact on fruit production systems and commercialization. In this study we determined the relationship between temperature and development, survival and reproductive parameters of B. Read More

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Quantitative analysis of the relationship of derivatization reagents and detection sensitivity of electrospray ionization-triple quadrupole tandem mass spectrometry: Hydrazines as prototypes.

Anal Chim Acta 2021 May 13;1158:338402. Epub 2021 Mar 13.

Department of Chemistry, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, 430072, PR China. Electronic address:

Chemical derivatization-assisted electrospray ionization-triple quadrupole mass spectrometry (ESI-QqQ-MS) has become an efficient tool for the quantification of low-molecular-weight molecules. Many studies found that the derivatives of the same analytes derivatized by different derivatization reagents with the same reaction group had different detection sensitivity, even under the same conditions of electrospray ionization-mass spectrometry (ESI-MS). This phenomenon was suggested to be caused by the different modifying groups in the derivatization reagents. Read More

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Cancer immune control dynamics: a clinical data driven model of systemic immunity in patients with metastatic melanoma.

BMC Bioinformatics 2021 Apr 16;22(1):197. Epub 2021 Apr 16.

Department of Medical Oncology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.

Background: Recent clinical advances in cancer immuno-therapeutics underscore the need for improved understanding of the complex relationship between cancer and the multiple, multi-functional, inter-dependent, cellular and humoral mediators/regulators of the human immune system. This interdisciplinary effort exploits engineering analysis methods utilized to investigate anomalous physical system behaviors to explore immune system behaviors. Cancer Immune Control Dynamics (CICD), a systems analysis approach, attempts to identify differences between systemic immune homeostasis of 27 healthy volunteers versus 14 patients with metastatic malignant melanoma based on daily serial measurements of conventional peripheral blood biomarkers (15 cell subsets, 35 cytokines). Read More

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Anomalous diffusion in nonlinear transformations of the noisy voter model.

Phys Rev E 2021 Mar;103(3-1):032154

Institute of Theoretical Physics and Astronomy, Vilnius University, Saulėtekio 3, LT-10257 Vilnius, Lithuania.

Voter models are well known in the interdisciplinary community, yet they have not been studied from the perspective of anomalous diffusion. In this paper, we show that the original voter model exhibits a ballistic regime. Nonlinear transformations of the observation variable and time scale allow us to observe other regimes of anomalous diffusion as well as normal diffusion. Read More

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Single-cell mechanical analysis and tension quantification via electrodeformation relaxation.

Phys Rev E 2021 Mar;103(3-1):032409

Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, USA.

The mechanical behavior and cortical tension of single cells are analyzed using electrodeformation relaxation. Four types of cells, namely, MCF-10A, MCF-7, MDA-MB-231, and GBM, are studied, with pulse durations ranging from 0.01 to 10 s. Read More

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Irreversible entropy production in low- and high-dissipation heat engines and the problem of the Curzon-Ahlborn efficiency.

Phys Rev E 2021 Mar;103(3-1):032141

Technische Universität München, D-80333 Munich, Germany.

Heat engines performing finite time Carnot cycles are described by positive irreversible entropy functions added to the ideal reversible entropy part. The model applies for macroscopic and microscopic (quantum mechanical) engines. The mathematical and physical conditions for the solution of the power maximization problem are discussed. Read More

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Role of thermal fluctuations in biological copying mechanisms.

Phys Rev E 2021 Mar;103(3-1):032110

Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Strasse 38, 01187 Dresden, Germany.

During transcription, translation, or self-replication of DNA or RNA, information is transferred to the newly formed species from its predecessor. These processes can be interpreted as (generalized) biological copying mechanism as the new biological entities like DNA, RNA, or proteins are representing the information of their parent bodies uniquely. The accuracy of these copying processes is essential, since errors in the copied code can reduce the functionality of the next generation. Read More

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Persistence and extinction of species in a disease-induced ecological system under environmental stochasticity.

Phys Rev E 2021 Mar;103(3-1):032412

Centre for Mathematical Biology and Ecology, Department of Mathematics, Jadavpur University, Kolkata 700032, India.

Population extinction is a serious issue both from the theoretical and practical points of view. We explore here how environmental noise influences persistence and extinction of interacting species in presence of a pathogen even when the populations remain stable in its deterministic counterpart. Multiplicative white noise is introduced in a deterministic predator-prey-parasite system by randomly perturbing three biologically important parameters. Read More

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Dielectrowetting of a thin nematic liquid crystal layer.

Phys Rev E 2021 Mar;103(3-1):032702

Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, New Jersey 07102, USA.

We consider a mathematical model that describes the flow of a nematic liquid crystal (NLC) film placed on a flat substrate, across which a spatially varying electric potential is applied. Due to their polar nature, NLC molecules interact with the (nonuniform) electric field generated, leading to instability of a flat film. Implementation of the long wave scaling leads to a partial differential equation that predicts the subsequent time evolution of the thin film. Read More

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Entropic characterization of the coil-stretch transition of polymers in random flows.

Phys Rev E 2021 Mar;103(3-1):033107

Weizmann Institute of Science, 76100 Rehovot, Israel.

Polymer molecules in a flow undergo a coil-stretch phase transition on an increase of the velocity gradients. Model-independent identification and characterization of the transition in a random flow has been lacking so far. Here we suggest to use the entropy of the extension statistics as a proper measure due to strong fluctuations around the transition. Read More

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Analysis of electrostimulation and electroporation by high repetition rate bursts of nanosecond stimuli.

Bioelectrochemistry 2021 Apr 1;140:107811. Epub 2021 Apr 1.

Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA. Electronic address:

Exposures to short-duration, strong electric field pulses have been utilized for stimulation, ablation, and the delivery of molecules into cells. Ultrashort, nanosecond duration pulses have shown unique benefits, but they require higher field strengths. One way to overcome this requirement is to use trains of nanosecond pulses with high repetition rates, up to the MHz range. Read More

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Municipal waste management: A complex network approach with an application to Italy.

Waste Manag 2021 Apr 13;126:597-607. Epub 2021 Apr 13.

University of Macerata, Department of Economics and Law, Via Crescimbeni, 14, 62100 Macerata, Italy. Electronic address:

The paper contributes to the debate concerning the management of municipal solid waste by providing an analysis of two key aspects of waste management - namely, waste separation and dispatch to treatment plants. Our analysis aims at detecting the extent to which actual behavior in (close-by) municipalities is similar with respect to those two aspects. To pursue our scope, a complex network approach is followed. Read More

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A predictive framework based on brain volume trajectories enabling early detection of Alzheimer's disease.

Comput Med Imaging Graph 2021 Apr 2;90:101910. Epub 2021 Apr 2.

Data used in the preparation of this article was obtained from the Australian Imaging Biomarkers and Lifestyle Flagship Study of Ageing (AIBL) funded by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) which was made available at the ADNI database. The AIBL researchers contributed data but did not participate in analysis or writing of this report. AIBL researchers are listed at www.aibl.csiro.au.

We present a framework for constructing predictive models of cognitive decline from longitudinal MRI examinations, based on mixed effects models and machine learning. We apply the framework to detect conversion from cognitively normal (CN) to mild cognitive impairment (MCI) and from MCI to Alzheimer's disease (AD), using a large collection of subjects sourced from the Alzheimer's Disease Neuroimaging Initiative (ADNI) and the Australian Imaging, Biomarkers and Lifestyle Flagship Study of Aging (AIBL). We extract subcortical segmentation and cortical parcellation from corresponding T1-weighted images using FreeSurfer v. Read More

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Dual-isotope-based source apportionment of nitrate in 30 rivers draining into the Bohai Sea, north China.

Environ Pollut 2021 Apr 12;283:117112. Epub 2021 Apr 12.

State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China.

Excessive nitrate (NO) in rivers can lead to water quality deterioration, and can also be directly input into estuaries and oceans, thus posing a serious threat to the stability of their ecosystems. In this study, the concentration, isotopes and sources of NO in 30 rivers discharging into the Bohai Sea were comprehensively investigated. The mean concentration of NO-N was 2. Read More

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Modelling uniaxial non-uniform yeast colony growth: comparing an agent-based model and continuum approximations.

J Theor Biol 2021 Apr 13:110715. Epub 2021 Apr 13.

School of Mathematical Sciences, The University of Adelaide, Adelaide 5005, Australia.

Biological experiments have shown that yeast can be restricted to grow in a uniaxial direction, vertically upwards from an agar plate to form a colony. The growth occurs as a consequence of cell proliferation driven by a nutrient supply at the base of the colony, and the height of the colony has been observed to increase linearly with time. Within the colony the nutrient concentration is non-constant and yeast cells throughout the colony will therefore not have equal access to nutrient, resulting in non-uniform growth. Read More

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Modelling aspects of consciousness: a topological perspective.

Authors:
Mike Steel

J Theor Biol 2021 Apr 13:110713. Epub 2021 Apr 13.

Biomathematics Research Centre, University of Canterbury, Christchurch, New Zealand. Electronic address:

Attention Schema Theory (AST) is a recent proposal to provide a scientific explanation for the basis of subjective awareness. In AST, the brain constructs a representation of attention taking place in its own (and others') mind ('the attention schema'). Moreover, this representation is incomplete for efficiency reasons. Read More

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Co-adaptive behavior of interacting populations in a habitat selection game significantly impacts ecosystem functions.

J Theor Biol 2021 Apr 13:110663. Epub 2021 Apr 13.

VKR Centre for Ocean Life, Technical University of Denmark, 2800 Kongens Lyngby, Denmark. Electronic address:

Individuals of different interacting populations often adjust to prevailing conditions by changing their behavior simultaneously, with consequences for trophic relationships throughout the system. While we now have a good theoretical understanding of how individuals adjust their behavior, the population dynamical consequences of co-adaptive behaviors are rarely described. Further, mechanistic descriptions of ecosystem functions are based on population models that seldom take behavior into account. Read More

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Modelling strategies to organize healthcare workforce during pandemics: application to COVID-19.

J Theor Biol 2021 Apr 13:110718. Epub 2021 Apr 13.

Department for Visceral Surgery and Medicine, Bern University Hospital, University of Bern, Switzerland; Bern Center for Precision Medicine, Switzerland.

Protection of the healthcare workforce is of paramount importance for the care of patients in the setting of a pandemic such as coronavirus disease 2019 (COVID-19). Healthcare workers are at increased risk of becoming infected. The ideal organisational strategy to protect the workforce in a situation in which social distancing cannot be maintained remains to be determined. Read More

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Impact of intervention on the spread of COVID-19 in India: A model based study.

J Theor Biol 2021 Apr 13:110711. Epub 2021 Apr 13.

Agricultural and Ecological Research Unit, Indian Statistical Institute, 203, B. T. Road, Kolkata 700108, India.

The outbreak of coronavirus disease 2019 (COVID-19), caused by the virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has already created emergency situations in almost every country of the world. The disease spreads all over the world within a very short period of time after its first identification in Wuhan, China in December, 2019. In India, the outbreak, starts on 2 March, 2020 and after that the cases are increasing exponentially. Read More

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Motif lengths of circular codes in coding sequences.

J Theor Biol 2021 Apr 13:110708. Epub 2021 Apr 13.

Competence Center for mathematical and algorithmical methods in Biology, Biotechnology and Medicine, Mannheim University of Applied Sciences, 68163 Mannheim, Germany. Electronic address:

Protein synthesis is a crucial process in any cell. Translation, in which mRNA is translated into proteins, can lead to several errors, notably frame shifts where the ribosome accidentally skips or re-reads one or more nucleotides. So-called circular codes are capable of discovering frame shifts and their codons can be found disproportionately often in coding sequences. Read More

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Bifurcation analyses and potential landscapes of a cortex-basal ganglia-thalamus model.

IET Syst Biol 2021 Apr 16. Epub 2021 Apr 16.

School of Statistics and Mathematics, Inner Mongolia University of Finance and Economics, Hohhot, China.

The dynamics of cortical neuronal activity plays important roles in controlling body movement and is regulated by connection weights between neurons in a cortex-basal ganglia-thalamus (BGCT) loop. Beta-band oscillation of cortical activity is closely associated with the movement disorder of Parkinson's disease, which is caused by an imbalance in the connection weights of direct and indirect pathways in the BGCT loop. In this study, the authors investigate how the dynamics of cortical activity are modulated by connection weights of direct and indirect pathways in the BGCT loop under low dopamine levels through bifurcation analyses and potential landscapes. Read More

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La Crosse virus spread within the mosquito population in Knox County, TN.

PLoS One 2021 16;16(4):e0249811. Epub 2021 Apr 16.

Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN, United States of America.

In Appalachia, La Crosse virus (LACV) is a leading pediatric arbovirus and public health concern for children under 16 years. LACV is transmitted via the bite of an infected Aedes mosquito. Thus, it is imperative to understand the dynamics of the local vector population in order to assess risk and transmission. Read More

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Prediction With Unpredictable Feature Evolution.

IEEE Trans Neural Netw Learn Syst 2021 Apr 16;PP. Epub 2021 Apr 16.

Learning with feature evolution studies the scenario where the features of the data streams can evolve, i.e., old features vanish and new features emerge. Read More

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Elastoplastic Approach Based on Microscopic Insights for the Steady State and Transient Dynamics of Sheared Disordered Solids.

Phys Rev Lett 2021 Apr;126(13):138005

Univ. Grenoble Alpes, CNRS, LIPhy, 38000 Grenoble, France.

We develop a framework to study the mechanical response of athermal amorphous solids via a coupling of mesoscale and microscopic models. Using measurements of coarse-grained quantities from simulations of dense disordered particulate systems, we present a coherent elastoplastic model approach for deformation and flow of yield stress materials. For a given set of parameters, this model allows us to match consistently transient and steady state features of driven disordered systems with diverse preparation histories under both applied shear-rate and creep protocols. Read More

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