Read by QxMD icon Read

Mathematical modelling

Bashar Ibrahim
The mitotic spindle orientation and position is crucial for the fidelity of chromosome segregation during asymmetric cell division to generate daughter cells with different sizes or fates. This mechanism is best understood in the budding yeast Saccharomyces cerevisiae, named the spindle position checkpoint (SPOC). The SPOC inhibits cells from exiting mitosis until the mitotic spindle is properly oriented along the mother-daughter polarity axis. Despite many experimental studies, the mechanisms underlying SPOC regulation remains elusive and unexplored theoretically...
May 21, 2018: Mathematical Biosciences
Shi Zhao, Yijun Lou, Alice P Y Chiu, Daihai He
Japanese encephalitis virus (JEV) is a zoonotic mosquito-borne virus, persisting in pigs, Ardeid birds and Culex mosquitoes. It is endemic to China and Southeastern Asia. The case-fatality ratio (CFR) or the rate of permanent psychiatric sequelae is 30% among symptomatic patients. There were no reported local JEV human cases between 2006 to 2010 in Hong Kong, but it was followed by a resurgence of cases from 2011 to 2017. The mechanism behind this "skip-and-resurgence" patterns is unclear. This work aims to reveal the mechanism behind the "skip-and-resurgence" patterns using mathematical modelling and likelihood-based inference techniques...
May 21, 2018: Journal of Theoretical Biology
Savanna Dorsey, Sylvain Tollis, Jing Cheng, Labe Black, Stephen Notley, Mike Tyers, Catherine A Royer
To understand how commitment to cell division in late G1 phase (Start) is controlled by growth and nutrients in budding yeast, we determined the absolute concentrations of the G1/S transcription factors SBF (composed of Swi4 and Swi6) and MBF (composed of Mbp1 and Swi6), the transcriptional repressor Whi5, and the G1 cyclins, Cln1 and Cln2, in single live yeast cells using scanning number and brightness (sN&B) microscopy. In rich medium, Whi5, Mbp1, and Swi6 concentrations were independent of cell size, whereas Swi4 concentration doubled in G1 phase, leading to a size-dependent decrease in the Whi5/Swi4 ratio...
May 23, 2018: Cell Systems
R Pálek, V Liška, L Eberlová, H Mírka, M Svoboda, S Haviar, M Emingr, O Brzoň, P Mik, V Třeška
INTRODUCTION: Corrosion casts (CCs) are used for the visualization and assessment of hollow structures. CCs with filled capillaries enable (with the help of imaging methods) to obtain data for mathematical organ perfusion modelling. As the processing is more difficult in case of organs with greater volume of the vasculature, mainly organs from small animals have been cast up to now. The aim of this study was to optimize the protocol of corrosion casting of different organs of pig. Porcine organs are relatively easily accessible and frequently used in experimental medicine...
2018: Rozhledy V Chirurgii: Měsíčník Československé Chirurgické Společnosti
Sajjad Farashi, Pezhman Sasanpour, Hashem Rafii-Tabar
Purpose-Although the effect of electromagnetic fields on biological systems has attracted attraction in recent years, there has not been any conclusive result concerning the effects of interaction and the underlying mechanisms involved. Besides the complexity of biological systems, the parameters of the applied electromagnetic field have not been estimated in most of the experiments. Material and Method-In this study, we have used computational approach in order to find the excitation parameters of an external electric field which produces sensible effects in the function of insulin secretory machinery, whose failure triggers the diabetes disease...
May 24, 2018: International Journal of Radiation Biology
Kevin M Kniffin, Andrew S Hanks
Teamwork has increasingly become prevalent in professional fields such as academic science, perhaps partly because research shows that teams tend to produce superior work. Although research on teamwork has typically focused on its impact on work products, we complement that work by examining the degree to which teamwork influences salary, hours worked, and overall job satisfaction. Drawing on microdata collected through the National Science Foundation's Survey of Doctorate Recipients as well as the Survey of Earned Doctorates, we find that doctoral degree holders in science, technology, engineering, and mathematics (STEM) fields tend to earn substantially higher salaries and work more hours when they engage in teamwork...
May 2018: American Psychologist
Erin C Conrad, James M Mossner, Kelvin L Chou, Parag G Patil
BACKGROUND/AIMS: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves motor symptoms of Parkinson disease (PD). However, motor outcomes can be variable, perhaps due to inconsistent positioning of the active contact relative to an unknown optimal locus of stimulation. Here, we determine the optimal locus of STN stimulation in a geometrically unconstrained, mathematically precise, and atlas-independent manner, using Unified Parkinson Disease Rating Scale (UPDRS) motor outcomes and an electrophysiological neuronal stimulation model...
May 23, 2018: Stereotactic and Functional Neurosurgery
Ivana Filipović, Siniša Markov, Vladimir Filipović, Jelena Filipović, Ana Vidaković, Nebojša Novković, Vesna Rafajlovska
AIMS: The goal of this research is to model the effects of two osmotic solutions factors on reduction of selected microorganisms, and to assess the application in osmotic dehydration process of animal raw materials from the aspect of microbiological safety. METHODS AND RESULTS: Sugar beet molasses and aquatic osmotic solution were prepared and inoculated with E. coli, L. monocytogenes and Salmonella spp. Varied factors of osmotic solutions were: time, temperature and concentration of osmotic solutions...
May 23, 2018: Journal of Applied Microbiology
Maher A Dayeh, George Livadiotis, Saber Elaydi
Dementia associated with the Alzheimer's disease is thought to be correlated with the conversion of the β - Amyloid (Aβ) peptides from soluble monomers to aggregated oligomers and insoluble fibrils. We present a discrete-time mathematical model for the aggregation of Aβ monomers into oligomers using concepts from chemical kinetics and population dynamics. Conditions for the stability and instability of the equilibria of the model are established. A formula for the number of monomers that is required for producing oligomers is also given...
2018: PloS One
Rebekah H Borse, Charisma Y Atkins, Manoj Gambhir, Eduardo A Undurraga, Jesse D Blanton, Emily B Kahn, Jessie L Dyer, Charles E Rupprecht, Martin I Meltzer
BACKGROUND: Dog rabies annually causes 24,000-70,000 deaths globally. We built a spreadsheet tool, RabiesEcon, to aid public health officials to estimate the cost-effectiveness of dog rabies vaccination programs in East Africa. METHODS: RabiesEcon uses a mathematical model of dog-dog and dog-human rabies transmission to estimate dog rabies cases averted, the cost per human rabies death averted and cost per year of life gained (YLG) due to dog vaccination programs (US 2015 dollars)...
May 23, 2018: PLoS Neglected Tropical Diseases
Guoyan Sun, Lingling Zhao, Qingliang Zhao, Limin Gao
There have been few investigations dealing with the force model on grinding brittle materials. However, the dynamic material removal mechanisms have not yet been sufficiently explicated through the grain-workpiece interaction statuses while considering the brittle material characteristics. This paper proposes an improved grinding force model for Zerodur, which contains ductile removal force, brittle removal force, and frictional force, corresponding to the ductile and brittle material removal phases, as well as the friction process, respectively...
May 10, 2018: Applied Optics
Yohan Bignon, Alexi Alekov, Nadia Frachon, Olivier Lahuna, Carine Jean-Baptiste Doh-Egueli, Georges Deschênes, Rosa Vargas-Poussou, Stéphane Lourdel
Dent disease in an X-linked recessive renal tubular disorder characterized by low-molecular-weight proteinuria, hypercalciuria, nephrolithiasis, nephrocalcinosis and progressive renal failure. Inactivating mutations of CLCN5, the gene encoding the 2Cl- /H+ exchanger ClC-5 have been reported in patients with Dent disease 1. In vivo studies in mice harboring an artificial mutation in the "gating glutamate" of ClC-5 (c.632A > C, p.Glu211Ala) and mathematical modeling suggest that endosomal chloride concentration could be an important parameter in endocytosis, rather than acidification as earlier hypothesized...
May 23, 2018: Human Mutation
A V Chizhov, D V Amakhin, A V Zaizev, L G Magazanik
The mechanisms of interictal discharges (IID) were studied under the conditions of the 4-aminopyridine model of spontaneous epileptiform activity in surviving rat brain slice preparations. Addition of the agents blocking GABA and NMDA receptors failed to inhibit IID generation in the entorhinal cortex. A mathematical model of IID has been developed on the basis of the excitatory neuron interaction mediated by the AMPA receptor. Short-term synaptic depression and slow afterspike-hyperpolarization are the key factors required to terminate a single IID...
March 2018: Doklady Biological Sciences: Proceedings of the Academy of Sciences of the USSR, Biological Sciences Sections
J A Sanz-Herrera, L Soria, E Reina-Romo, Y Torres, A R Boccaccini
Dissolution phenomena are ubiquitously present in biomaterials in many different fields. Despite the advantages of simulation-based design of biomaterials in medical applications, additional efforts are needed to derive reliable models which describe the process of dissolution. A phenomenologically based model, available for simulation of dissolution in biomaterials, is introduced in this paper. The model turns into a set of reaction-diffusion equations implemented in a finite element numerical framework. First, a parametric analysis is conducted in order to explore the role of model parameters on the overall dissolution process...
May 22, 2018: Biomechanics and Modeling in Mechanobiology
Ling Wang, Yao Chen, Kun Tang, Jie Lin, Hong Zhang
Purpose: To establish an 18 F-fluorodeoxyglucose (18 F-FDG) positron emission tomography/computed tomography (PET/CT) mathematical prediction model to improve the diagnosis of solitary pulmonary nodules (SPNs). Materials and Methods: We retrospectively reviewed 177 consecutive patients who underwent 18 F-FDG PET/CT for evaluation of SPNs. The mathematical model was established by logistic regression analysis. The diagnostic capabilities of the model were calculated, and the areas under the receiver operating characteristic curve (AUC) were compared with Mayo and VA model...
2018: BioMed Research International
Héctor Martínez-García, Miguel Aragón-Sánchez, María G Sáenz-Romo, Luis R Román-Fernández, Ariadna Veas-Bernal, Vicente S Marco-Mancebón, Ignacio Pérez-Moreno
Complete development of Orius majusculus Reuter (Heteroptera: Anthocoridae) at nine constant temperatures, between 12 and 34°C, was evaluated under laboratory conditions. The maximum developmental period of 90.75 d occurred at 12°C, whereas the minimum of 11.34 d occurred at 30°C. From 30 to 34°C, the developmental period increased to 13.50 d. Between 21 and 33°C the survival rate was more than 80%. The optimal temperature when considering developmental rate and survival was between 24 and 30°C. At constant temperatures, four models were developed, one of which was linear and three nonlinear (Logan type III, Lactin, and Brière)...
May 19, 2018: Journal of Economic Entomology
Carl Malina, Christer Larsson, Jens Nielsen
Mitochondria are dynamic organelles of endosymbiotic origin that are essential components of eukaryal cells. They contain their own genetic machinery, have multicopy genomes and like their bacterial ancestors they consist of two membranes. However, the majority of the ancestral genome has been lost or transferred to the nuclear genome of the host, preserving only a core set of genes involved in oxidative phosphorylation. Mitochondria perform numerous biological tasks ranging from bioenergetics to production of protein co-factors, including heme and iron-sulfur clusters...
August 1, 2018: FEMS Yeast Research
Sarah Gregory, Jeffrey D Long, Stefan Klöppel, Adeel Razi, Elisa Scheller, Lora Minkova, Eileanoir B Johnson, Alexandra Durr, Raymund A C Roos, Blair R Leavitt, James A Mills, Julie C Stout, Rachael I Scahill, Sarah J Tabrizi, Geraint Rees
The initial stages of neurodegeneration are commonly marked by normal levels of cognitive and motor performance despite the presence of structural brain pathology. Compensation is widely assumed to account for this preserved behaviour, but despite the apparent simplicity of such a concept, it has proven incredibly difficult to demonstrate such a phenomenon and distinguish it from disease-related pathology. Recently, we developed a model of compensation whereby brain activation, behaviour and pathology, components key to understanding compensation, have specific longitudinal trajectories over three phases of progression...
May 17, 2018: Brain: a Journal of Neurology
Luigi C Capozzi, Roberto Pisano
The freezing step plays a central role in reaching the most stringent requirements of quality, homogeneity and standardization of freeze-dried products. In this paper, a systematic procedure has been proposed to obtain a quantitative estimation of the pore-size variability of lyophilized products resulting from uncontrollable variations of the nucleation temperature. This procedure consisted in collecting the nucleation temperature from a statistically significant number of samples and correlating each nucleation temperature to the corresponding product morphology, using a mathematical model, to obtain a statistical description of the lyophilized product structure...
May 19, 2018: European Journal of Pharmaceutics and Biopharmaceutics
Mario Banuelos, Suzanne Sindi
Transposable elements (TEs), segments of DNA capable of self-replication, are abundant in the genomes of most organisms and thus serve as a record of past mutational events. While some work suggests TEs may serve a regulatory function for the host, most empirical and theoretical studies have shown that TEs often have deleterious effects on a host. Because they are not essential, the host genome consists of both full-length (actively replicating) and partial length (inactive remnant) copies of TEs. We developed a novel mathematical formulation of TE dynamics by modeling the density of full and partial length copies resulting from mutations (insertions and deletions) and TE replication within the host genome...
May 19, 2018: Mathematical Biosciences
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"