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Wyszukujesz frazę "Kimmel, M." wg kryterium: Autor


Tytuł:
Analysis of dynamics of gene exspression using singular value decomposition
Autorzy:
Simek, K.
Kimmel, M.
Tematy:
wielokrotna ekspresja genów
dynamiczny model danych ekspresji genów
pojedynczy rozkład wartości
multiple gene expression
dynamic model of gene expression data
singular value decomposition
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Wydawca:
Uniwersytet Śląski. Wydział Informatyki i Nauki o Materiałach. Instytut Informatyki. Zakład Systemów Komputerowych
Powiązania:
https://bibliotekanauki.pl/articles/332865.pdf  Link otwiera się w nowym oknie
Opis:
Recently, data on multiple gene expression at sequential time points were analyzed, using Singular Value Decomposition (SVD) as a means to capture dominant trends, called characteristic modes, followed by fitting of a linear discrete-time dynamical model in which the expression values at a given time point are linear combinations of the values at a previous time point. We attempt to address several aspects of the method. To obtain the model we formulate a nonlinear optimization problem and present how to solve it numerically using standard MATLAB procedures. We use publicly available data to test the approach. Then, we investigate the sensitivity of the method to missing measurements and its possibilities to reconstruct missing data. Summarizing we point out that approximation of multiple gene expression data preceded by SVD provides some insight into the dynamics but may also lead to unexpected difficulties.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Population Genetics Models for the Statistics of dna Samples Under Different Demographic Scenarios---Maximum Likelihood Versus Approximate Methods
Autorzy:
Polański, A.
Kimmel, M.
Tematy:
demografia
statystyka
DNA samples
demography
coalescence
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Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:
https://bibliotekanauki.pl/articles/908157.pdf  Link otwiera się w nowym oknie
Opis:
The paper reviews the basic mathematical methodology of modeling neutral genetic evolution, including the statistics of the Fisher-Wright process, models of mutation and the coalescence method under various demographic scenarios. The basic approach is the use of maximum likelihood techniques. However, due to computational problems, intuitive or approximate methods are also of great importance.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stochastic Models of Progression of Cancer and Their Use in Controlling Cancer-Related Mortality
Autorzy:
Kimmel, M.
Gorlova, O. Y.
Tematy:
medycyna
statystyka
lung cancer
genetic susceptibility
environmental exposure
tumor growth
statistical modeling
simulation
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Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:
https://bibliotekanauki.pl/articles/908159.pdf  Link otwiera się w nowym oknie
Opis:
A construction of a realistic statistical model of lung cancer risk and progression is proposed. The essential elements of the model are genetic and behavioral determinants of susceptibility, progression of the disease from precursor lesions through early (localized) tumors to disseminated disease, detection by various modalities, and medical intervention. Using model estimates as a foundation, mortality reduction caused by early-detection and intervention programs can be predicted under different scenarios. Genetic indicators of susceptibility to lung cancer should be used to define the highest-risk subgroups of the high-risk behavior population (smokers). The calibration and validation of the model requires applying our techniques to a variety of data sets available, including public registry data of the SEER type, data from the NCI lung cancer chest X-ray screening studies, and the recent ELCAP CT-scan screening study.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Testing for signatures of natural selection at molecular genes level
Autorzy:
Cyran, K.
Polańska, J.
Kimmel, M.
Tematy:
testowanie kwalifikacyjne
ludzkie geny nowotworowe
selection testing
human cancer genes
ATM
RECQL
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Wydawca:
Uniwersytet Śląski. Wydział Informatyki i Nauki o Materiałach. Instytut Informatyki. Zakład Systemów Komputerowych
Powiązania:
https://bibliotekanauki.pl/articles/333073.pdf  Link otwiera się w nowym oknie
Opis:
The paper presents the methodology used for detecting the signatures of natural selection at the molecular level from single nucleotide polymorphism data. The results obtained from widely used approach, based on statistical testing departures from neutral evolution model, can be obscured by the presence of alternative hypotheses generating the similar to natural selection results of the tests. These hypotheses include population growth and geographic substructure. Especially for human population these alternatives are of non-negligible importance. In the paper we show how to deal with this problem, both by the analysis of a battery of statistical tests giving indication about the age of the predominant mutations, and by application of non conventional null hypotheses that assume different population scenarios. Since the critical values of the tests are known only for panmicting, constant size population, the second approach demands the intensive computer simulations of coalescence process to obtain analogous critical values for different scenarios used as a null. The methodology with the problem of detecting signatures of natural selection in four genes implicated in human familial cancers has been illustrated.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Are infinite dimensional models applicable in modelling and analysis of cancer chemotherapy?
Autorzy:
Świerniak, A.
Kimmel, M.
Śmieja, J.
Rzeszowska-Wolny, J.
Tematy:
odporność na leki
nieskończenie wymiarowy system
przekształcenia Laplace'a
drug resistance
branching random walk
infinite-dimensional systems
Laplace transforms
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Wydawca:
Uniwersytet Śląski. Wydział Informatyki i Nauki o Materiałach. Instytut Informatyki. Zakład Systemów Komputerowych
Powiązania:
https://bibliotekanauki.pl/articles/333061.pdf  Link otwiera się w nowym oknie
Opis:
Drug resistance and phase dependence have been regarded by many authors as the main obstacles against successful cancer chemotherapy. We propose a model which takes into account both these phenomena and give a tool to use phase specificity as an advantage rather than a fault and make it resistant of drug resistance. It combines models that so far have been studied separately, taking into account both the phenomenon of gene amplification and drug specificity in chemotherapy, in their different aspects. The mathematical description is given by an infinite dimensional state equation with a system matrix, the form of which enables decomposition of the model into two interacting subsystems. While the first one, of finite dimension, can have any form, the second one is infinite dimensional and tridiagonal.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Qualitative analysis of controlled drug resistance model - inverse Laplace and and semigroup approach
Autorzy:
Świerniak, A.
Polański, A.
Kimmel, M.
Bobrowski, A.
Śmieja, J.
Tematy:
modele biomedyczne
proces gałązkowy
stabilność
układy nieskończenie wymiarowe
biomedical models
branching processes
infinite dimensional systems
stability
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Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Powiązania:
https://bibliotekanauki.pl/articles/205965.pdf  Link otwiera się w nowym oknie
Opis:
In this paper we study some properties of infinite models of the controlled evolution of drug resistance. We combine asymptotic techniques used in previous studies of similar models with methods of control theory and of semigroup theory. It enables us to find conditions for stability of the model both when the sensitive population is annihilated and when there exists a permanent influx from the sensivite compartment into drug resistant one. The conditions are expressed in terms of relationships between amplification and deamplification ratios as well as average life times of cells and intensity of anticancer drug action.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asymptotic analysis of three random branching walk models arising in molecular biology
Analiza asymptotyczna trzech modeli błądzenia z rozgałęzieniami z dziedziny biologii molekularnej
Autorzy:
Świerniak, A.
Polański, A.
Śmieja, J.
Kimmel, M.
Rzeszowska-Wolny, J.
Tematy:
analiza asymptotyczna
modelowanie biomatematyczne
procesy rozgałęzień
systemy nieskończenie wymiarowe
asymptotic analysis
biomathematical modelling
branching processes
infinite dimensional systems
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Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Powiązania:
https://bibliotekanauki.pl/articles/206737.pdf  Link otwiera się w nowym oknie
Opis:
Using asymptotic techniques based on Laplace transforms, spectral analysis and theory of feedback systems, we characterise the asymptotic behaviour of the repeat loci in microsatellite DNA and cancer cells with increasing number of copies of genes responsible for coding proteins causing drug removal or metabolisation as well as telomeres shortening, which is supposed to be the mechanism of ageing and death. These three problems are described by models in the form of infinitely many differential linear or bilinear first order equations, resulting from branching random walk processes used to represent the evolution of particles in these problems.
Wykorzystując techniki asymptotyczne oparte na transformatach Laplace'a, analizę spektralną oraz teorię układów ze sprzężeniem zwrotnym w artykule scharakteryzowano zachowanie asymptotyczne powtórek w DNA mikrosatelitarnym oraz w komórkach rakowych z rosnącą liczbą kopii genów odpowiedzialnych za kodowanie białek powodujących usuwanie lub przemianę metaboliczną leków, a także skracanie telomerów, o którym się sądzi, że jest mechanizmem starzenia się i śmierci. Te trzy zagadnienia są opisywane przy pomocy modeli w postaci nieskończonej liczby liniowych lub biliniowych równań pierwszego rzędu, wynikających z procesów błądzenia, stosowanych do opisu ewolucji cząstek w tych zagadnieniach.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sampling Properties of Estimators of Nucleotide Diversity at Discovered snp Sites
Autorzy:
Renwick, A.
Bonnen, P. E.
Trikka, D.
Nelson, D. L.
Chakraborty, R.
Kimmel, M.
Tematy:
genetyka
statystyka
single nucleotide polymorphisms
ascertainment bias
nucleotide diversity
molecular evolution
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Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:
https://bibliotekanauki.pl/articles/908150.pdf  Link otwiera się w nowym oknie
Opis:
SNP sites are generally discovered by sequencing regions of the human genome in a limited number of individuals. This may leave SNP sites present in the region, but containing rare mutant nucleotides, undetected. Consequently, estimates of nucleotide diversity obtained from assays of detected SNP sites are biased. In this research we present a statistical model of the SNP discovery process, which is used to evaluate the extent of this bias. This model involves the symmetric Beta distribution of variant frequencies at SNP sites, with an additional probability that there is no SNP at any given site. Under this model of allele frequency distributions at SNP sites, we show that nucleotide diversity is always underestimated. However, the extent of bias does not seem to exceed 10-15% for the analyzed data. We find that our model of allele frequency distributions at SNP sites is consistent with SNP statistics derived based on new SNP data at ATM, BLM, RQL and WRN gene regions. The application of the theory to these new SNP data as well as to the literature data at the LPL gene region indicates that in spite of ascertainment biases, the observed differences of nucleotide diversity across these gene regions are real. This provides interesting evidence concerning the heterogeneity of the rates of nucleotide substitution across the genome.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theory of Red Blood Cell Oscillations in an Ultrasound Field
Autorzy:
Johansen, K.
Kimmel, E.
Postema, M.
Tematy:
spatio-temporal cell dynamics
Rayleigh-Plesset equation
spherical cell
red blood cell
erythrocyte
sonophore
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Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/178064.pdf  Link otwiera się w nowym oknie
Opis:
Manipulating particles in the blood pool with noninvasive methods has been of great interest in therapeutic delivery. Recently, it was demonstrated experimentally that red blood cells can be forced to translate and accumulate in an ultrasound field. This acoustic response of the red blood cells has been attributed to sonophores, gas pockets that are formed under the influence of a sound field in the inner-membrane leaflets of biological cells. In this paper, we propose a simpler model: that of the compressible membrane. We derive the spatio-temporal cell dynamics for a spherically symmetric single cell, whilst regarding the cell bilayer membrane as two monolayer Newtonian viscous liquids, separated by a thin gas void. When applying the newly-derived equations to a red blood cell, it is observed that the void inside the bilayer expands to multiples of its original thickness, even at clinically safe acoustic pressure amplitudes. For causing permanent cell rupture during expansion, however, the acoustic pressure amplitudes needed would have to surpass the inertial cavitation threshold by a factor 10. Given the incompressibility of the inner monolayer, the radial oscillations of a cell are governed by the same set of equations as those of a forced antibubble. Evidently, these equations must hold for liposomes under sonication, as well.
Dostawca treści:
Biblioteka Nauki
Artykuł

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