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Letteratura scientifica selezionata sul tema "Intrinsic noise"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 11 febbraio 2022

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Articoli di riviste sul tema "Intrinsic noise"

Yang, Ren Di, e Yan Li Zhang. "Denoising of ECG Signal Based on Empirical Mode Decomposition and Adaptive Noise Cancellation". Applied Mechanics and Materials 40-41 (novembre 2010): 140–45. http://dx.doi.org/10.4028/www.scientific.net/amm.40-41.140.

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To remove the noises in ECG and to overcome the disadvantage of the denoising method only based on empirical mode decomposition (EMD), a combination of EMD and adaptive noise cancellation is introduced in this paper. The noisy ECG signals are firstly decomposed into intrinsic mode functions (IMFs) by EMD. Then the IMFs corresponding to noises are used to reconstruct signal. The reconstructed signal as the reference input of adaptive noise cancellation and the noisy ECG as the basic input, the de-noised ECG signal is obtained after adaptive filtering. The de-noised ECG has high signal-to-noise ratio, preferable correlation coefficient and lower mean square error. Through analyzing these performance parameters and testing the denoising method using MIT-BIH Database, the conclusion can be drawn that the combination of EMD and adaptive noise cancellation has considered the frequency distribution of ECG and noises, eliminate the noises effectively and need not to select a proper threshold.

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Sun, Mengyi, e Jianzhi Zhang. "Allele-specific single-cell RNA sequencing reveals different architectures of intrinsic and extrinsic gene expression noises". Nucleic Acids Research 48, n. 2 (4 dicembre 2019): 533–47. http://dx.doi.org/10.1093/nar/gkz1134.

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Abstract Gene expression noise refers to the variation of the expression level of a gene among isogenic cells in the same environment, and has two sources: extrinsic noise arising from the disparity of the cell state and intrinsic noise arising from the stochastic process of gene expression in the same cell state. Due to the low throughput of the existing method for measuring the two noise components, the architectures of intrinsic and extrinsic expression noises remain elusive. Using allele-specific single-cell RNA sequencing, we here estimate the two noise components of 3975 genes in mouse fibroblast cells. Our analyses verify predicted influences of several factors such as the TATA-box and microRNA targeting on intrinsic or extrinsic noises and reveal gene function-associated noise trends implicating the action of natural selection. These findings unravel differential regulations, optimizations, and biological consequences of intrinsic and extrinsic noises and can aid the construction of desired synthetic circuits.

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XIE, ZHI, e DON KULASIRI. "ON EXPLORING EFFECTS OF MOLECULAR NOISE IN A SIMPLE VIRAL INFECTION MODEL". International Journal of Biomathematics 03, n. 01 (marzo 2010): 1–19. http://dx.doi.org/10.1142/s1793524510000891.

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Intrinsic and extrinsic noises are all believed to be important in the development and function of many living organisms. In this study, we investigate the sources of the intrinsic noise and the influence of the extrinsic noise on an intracellular viral infection system. The contribution of the intrinsic noise from each reaction is measured by means of a special form of stochastic differential equations (SDEs), chemical Langevin equation. The intrinsic noise of the system is a linear sum of the noise in each of the reactions. The intrinsic noise mainly arises from the degradation of mRNA and the transcription processes. We then study the effects of extrinsic noise by the means of a general form of SDE. It is found that the noise of the viral components grows logarithmically with the increasing noise intensities. The system is most susceptible to the noise in the virus assembly process. A high level of noise in this process can even inhibit the growth of the viruses. This study also demonstrates the utility of SDEs in analyzing genetic regulatory networks perturbed by either inherent or parametric stochasticity.

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Liu, Shengjun, Qi Wang e Hai Feng. "The correlation between intrinsic noise and extrinsic noise". Physica A: Statistical Mechanics and its Applications 392, n. 20 (ottobre 2013): 5138–42. http://dx.doi.org/10.1016/j.physa.2013.06.032.

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Hayden, David, Ye Yuan e Jorge Goncalves. "Network Identifiability from Intrinsic Noise". IEEE Transactions on Automatic Control 62, n. 8 (agosto 2017): 3717–28. http://dx.doi.org/10.1109/tac.2016.2640219.

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KHALDI, KAIS, MONIA TURKI-HADJ ALOUANE e ABDEL-OUAHAB BOUDRAA. "VOICED SPEECH ENHANCEMENT BASED ON ADAPTIVE FILTERING OF SELECTED INTRINSIC MODE FUNCTIONS". Advances in Adaptive Data Analysis 02, n. 01 (gennaio 2010): 65–80. http://dx.doi.org/10.1142/s1793536910000409.

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In this paper a new method for voiced speech enhancement combining the Empirical Mode Decomposition (EMD) and the Adaptive Center Weighted Average (ACWA) filter is introduced. Noisy signal is decomposed adaptively into intrinsic oscillatory components called Intrinsic Mode Functions (IMFs). Since voiced speech structure is mostly distributed on both medium and low frequencies, the shorter scale IMFs of the noisy signal are beneath noise, however the longer scale ones are less noisy. Therefore, the main idea of the proposed approach is to only filter the shorter scale IMFs, and to keep the longer scale ones unchanged. In fact, the filtering of longer scale IMFs will introduce distortion rather than reducing noise. The denoising method is applied to several voiced speech signals with different noise levels and the results are compared with wavelet approach, ACWA filter and EMD–ACWA (filtering of all IMFs using ACWA filter). Relying on exhaustive simulations, we show the efficiency of the proposed method for reducing noise and its superiority over other denoising methods, i.e. to improve Signal-to-Noise Ratio (SNR), and to offer better listening quality based on a Perceptual Evaluation of Speech Quality (PESQ). The present study is limited to signals corrupted by additive white Gaussian noise.

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Shen, Tao, Zhangcai Long e Bo Chen. "External noise suppression by intrinsic noise in a neuron". Results in Physics 15 (dicembre 2019): 102615. http://dx.doi.org/10.1016/j.rinp.2019.102615.

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VÁZQUEZ-JIMÉNEZ, AARÓN, MOISÉS SANTILLÁN e JESÚS RODRÍGUEZ-GONZÁLEZ. "CHARACTERIZATION OF INTRINSIC AND EXTRINSIC NOISE EFFECTS IN POSITIVELY REGULATED GENES". Journal of Biological Systems 27, n. 03 (settembre 2019): 383–98. http://dx.doi.org/10.1142/s0218339019500165.

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Gene regulation is fundamental for cell survival. This regulation must be both robust to noise and sensitive enough to external stimuli to elicit the proper responses. In this work, we study, through stochastic numerical simulations, how a gene regulatory network with a positive feedback loop responds to environmental changes in the presence of intrinsic and extrinsic noises. Noise effects were characterized by measuring the statistical differences between two protein time series resulting from identical systems subject to the same source of extrinsic noise. A robust analysis was implemented by modifying the kinetic system parameters. We found that the common source of time-varying extrinsic fluctuations leads to a correlation in the systems it affects. The correlation and the extrinsic and intrinsic noise components are modulated by the update period and noise intensity parameters. Our results suggest that noise perception is controlled through the parameters associated with the response time: degradation rates and promoter dissociation constant.

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Szasz, Oliver, Gyula Peter Szigeti e Andras Szasz. "Intrinsic Noise Monitoring of Complex Systems". Open Journal of Biophysics 07, n. 04 (2017): 197–215. http://dx.doi.org/10.4236/ojbiphy.2017.74015.

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Prebianca, Flavio, Holokx A. Albuquerque e Marcus W. Beims. "Describing intrinsic noise in Chua's circuit". Physics Letters A 382, n. 35 (settembre 2018): 2420–23. http://dx.doi.org/10.1016/j.physleta.2018.05.054.

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Più fonti

Tesi sul tema "Intrinsic noise"

Qu, Song. "Non-Intrinsic Differential-Mode Noise in Switching Power Supplies and Its Implications to EMI Filter Design". Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/9788.

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Electromagnetic Interference (EMI) problems in switching power supplies have been traditionally treated with cut-and-try approaches. In recent years, advancement has been made to better understand the problems and minimize the cut-and-try portion of the design process. However, there are still phenomena difficult to explain in many practical design situations. Often, the problems may be solved by luck but many puzzles remain unsolved. If not fully understood, these puzzles are very likely to come back to haunt the designers. According to the conventional theory, there are two modes of noise: the Differential-Mode (DM) noise and the Common-Mode (CM) noise. Recently, a new noise-coupling mode called Non-Intrinsic Differential-Mode (NIDM) noise was uncovered accidentally in the process of explaining certain EMI filter action [1]. This phenomenon has never been thoroughly studied. The focus of the present thesis is to investigate the NIDM phenomenon and its implications to practical EMI filter design issues. The generation mechanism and basic characteristics of this phenomenon will be briefly reviewed, which is crucial to the understanding of the remaining parts of the research. Two essential diagnostic tools are introduced. One is the DM/CM noise separator and the other is the zero-span mode operation of a spectrum analyzer. The results of the investigation will be presented. The results will be presented using practical examples, which tie the phenomenon to filter design issues. In some examples, explanations are given to dispel the puzzles commonly encountered in the practice. A filter design procedure is suggested for off-line power supplies. This procedure incorporates the NIDM phenomenon into an existing design procedure. Only first-order and second-order filter topologies are included in the discussion.
Master of Science

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Hortsch, Sayuri Katharina [Verfasser], Andreas [Akademischer Betreuer] Kremling, Andreas [Gutachter] Kremling e Christina [Gutachter] Kuttler. "Model-based characterization of intrinsic noise in multistable genetic circuits / Sayuri Katharina Hortsch ; Gutachter: Andreas Kremling, Christina Kuttler ; Betreuer: Andreas Kremling". München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1171425600/34.

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Murrugarra, Tomairo David M. "Algebraic Methods for Modeling Gene Regulatory Networks". Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/28388.

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So called discrete models have been successfully used in engineering and computational systems biology. This thesis discusses algebraic methods for modeling and analysis of gene regulatory networks within the discrete modeling context. The first chapter gives a background for discrete models and put in context some of the main research problems that have been pursued in this field for the last fifty years. It also outlines the content of each subsequent chapter. The second chapter focuses on the problem of inferring dynamics from the structure (topology) of the network. It also discusses the characterization of the attractor structure of a network when a particular class of functions control the nodes of the network. Chapters~3 and 4 focus on the study of multi-state nested canalyzing functions as biologically inspired functions and the characterization of their dynamics. Chapter 5 focuses on stochastic methods, specifically on the development of a stochastic modeling framework for discrete models. Stochastic discrete modeling is an alternative approach from the well-known mathematical formalizations such as stochastic differential equations and Gillespie algorithm simulations. Within the discrete setting, a framework that incorporates propensity probabilities for activation and degradation is presented. This approach allows a finer analysis of discrete models and provides a natural setup for cell population simulations. Finally, Chapter 6 discusses future research directions inspired by the work presented here.
Ph. D.

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Xie, Zhi. "Modelling genetic regulatory networks: a new model for circadian rhythms in Drosophila and investigation of genetic noise in a viral infection process". Phd thesis, Lincoln University. Agriculture and Life Sciences Division, 2007. http://theses.lincoln.ac.nz/public/adt-NZLIU20070712.144258/.

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In spite of remarkable progress in molecular biology, our understanding of the dynamics and functions of intra- and inter-cellular biological networks has been hampered by their complexity. Kinetics modelling, an important type of mathematical modelling, provides a rigorous and reliable way to reveal the complexity of biological networks. In this thesis, two genetic regulatory networks have been investigated via kinetic models. In the first part of the study, a model is developed to represent the transcriptional regulatory network essential for the circadian rhythms in Drosophila. The model incorporates the transcriptional feedback loops revealed so far in the network of the circadian clock (PER/TIM and VRI/PDP1 loops). Conventional Hill functions are not used to describe the regulation of genes, instead the explicit reactions of binding and unbinding processes of transcription factors to promoters are modelled. The model is described by a set of ordinary differential equations and the parameters are estimated from the in vitro experimental data of the clocks components. The simulation results show that the model reproduces sustained circadian oscillations in mRNA and protein concentrations that are in agreement with experimental observations. It also simulates the entrainment by light-dark cycles, the disappearance of the rhythmicity in constant light and the shape of phase response curves resembling that of experimental results. The model is robust over a wide range of parameter variations. In addition, the simulated E-box mutation, perS and perL mutants are similar to that observed in the experiments. The deficiency between the simulated mRNA levels and experimental observations in per01, tim01 and clkJrk mutants suggests some differences in the model from reality. Finally, a possible function of VRI/PDP1 loops is proposed to increase the robustness of the clock. In the second part of the study, the sources of intrinsic noise and the influence of extrinsic noise are investigated on an intracellular viral infection system. The contribution of the intrinsic noise from each reaction is measured by means of a special form of stochastic differential equation, the chemical Langevin equation. The intrinsic noise of the system is the linear sum of the noise in each of the reactions. The intrinsic noise arises mainly from the degradation of mRNA and the transcription processes. Then, the effects of extrinsic noise are studied by means of a general form of stochastic differential equation. It is found that the noise of the viral components grows logarithmically with increasing noise intensities. The system is most susceptible to noise in the virus assembly process. A high level of noise in this process can even inhibit the replication of the viruses. In summary, the success of this thesis demonstrates the usefulness of models for interpreting experimental data, developing hypotheses, as well as for understanding the design principles of genetic regulatory networks.

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Saygun, Yakup. "Computational Stochastic Morphogenesis". Thesis, Uppsala universitet, Avdelningen för beräkningsvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-257096.

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Self-organizing patterns arise in a variety of ways in nature, the complex patterning observed on animal coats is such an example. It is already known that the mechanisms responsible for pattern formation starts at the developmental stage of an embryo. However, the actual process determining cell fate has been, and still is, unknown. The mathematical interest for pattern formation emerged from the theories formulated by the mathematician and computer scientist Alan Turing in 1952. He attempted to explain the mechanisms behind morphogenesis and how the process of spatial cell differentiation from homogeneous cells lead to organisms with different complexities and shapes. Turing formulated a mathematical theory and proposed a reaction-diffusion system where morphogens, a postulated chemically active substance, moderated the whole mechanism. He concluded that this process was stable as long as diffusion was neglected; otherwise this would lead to a diffusion-driven instability, which is the fundamental part of pattern formation. The mathematical theory describing this process consists of solving partial differential equations and Turing considered deterministic reaction-diffusion systems. This thesis will start with introducing the reader to the problem and then gradually build up the mathematical theory needed to get an understanding of the stochastic reaction-diffusion systems that is the focus of the thesis. This study will to a large extent simulate stochastic systems using numerical computations and in order to be computationally feasible a compartment-based model will be used. Noise is an inherent part of such systems, so the study will also discuss the effects of noise and morphogen kinetics on different geometries with boundaries of different complexities from one-dimensional cases up to three-dimensions.

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Andrade, Maria Glória Caño de. "Estudo de transistores de porta tripla de corpo". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-10062013-150025/.

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O objetivo principal deste trabalho é o estudo de transistores MuGFETs de porta tripla de Corpo de canal tipo-n com e sem a aplicação da configuração DTMOS. Este estudo será realizado através de simulações numéricas tridimensionais e por caracterizações elétricas. A corrente de dreno, a transcondutância, a resistência, a tensão de limiar, a inclinação de sublimiar e a Redução da Barreira Induzida pelo Dreno (DIBL) serão analisadas em modo DTMOS e em configuração de polarização convencional. Importantes figuras de mérito para o desempenho analógico como transcondutância-sobre-corrente de dreno, a condutância de saída, a tensão Early e o ganho de tensão intrínseco serão estudados tanto experimentalmente como através de simulações numéricas tridimensionais para diferentes concentrações de dopantes no canal. Os resultados indicam que a configuração DTMOS apresenta as características elétricas superiores (4 e 10 %) e maior eficiência dos transistores. Além disso, os dispositivos DTMOS com alta concentração de dopantes no canal apresentaram um desempenho analógico muito melhor quando comparados ao transistor de porta tripla de Corpo em modo de operação convencional. O ruído de baixa frequência (LF) é pela primeira vez experimentalmente analisado na região linear e saturação. A origem do ruído é analisada de maneira a compreender os mecanismos físicos envolvidos neste tipo de ruído. As medições mostraram que os espectros do sinal dos dispositivos de porta tripla de Corpo e DTMOS são compostos por flutuações referentes ao número de portadores devido ao ruído flicker e por ondas de ruído de geração e recombinação no dielétrico de porta que se torna maior com o aumento da tensão de porta. No entanto, o principal fato desta análise é que o dispositivo DTMOS apresentou praticamente a mesma magnitude do ruído LF na região linear e de saturação que o dispositivo de Corpo. A energia de 60 MeV na fluência de p/1012 cm-2 de radiações de prótons é também estudada experimentalmente em termos das características elétricas, desempenho do analógico e ruído LF nos dispositivos de porta tripla de Corpo e DTMOS. Os resultados indicam que combinado com as suas melhores características elétricas e um ótimo desempenho analógico do DTMOS, faz o transistor de porta tripla de Corpo um candidato muito competitivo para aplicações analógicas em ruído de baixa frequência antes e depois da irradiação. A vantagem da técnica DTMOS em transistores de porta tripla em ambientes onde os dispositivos têm de suportar alta radiação é devido à menor penetração do campo de dreno que reduz o efeito das cargas induzidas pelo óxido de isolação (STI). Finalmente, o transistor de Corpo de porta tripla de canal tipo-n é experimentalmente estudado como célula de memória, isto é, como 1T-DRAM (Memória de Acesso Aleatório Dinâmico com 1 transistor). Para escrever e ler 1 é utilizado um modo de programação que utiliza o efeito do transistor bipolar parasitário (BJT) enquanto a polarização direta da junção do corpo e do dreno é usada para escrever 0. As correntes de leitura e escrita aumentam com o aumento da tensão do corpo (VB) porque as cargas induzidas pelo efeito BJT é armazenada dentro da aleta. Quando o corpo do transistor está flutuante, o dispositivo retém mais cargas dentro da sua aleta. Além disso, transistor de Corpo pode ser utilizado como 1T-DRAM com eletrodo de porta e substrato flutuando. Neste caso, o dispositivo funciona como um biristor (sem porta).
The main goal of this work is to investigate the n-channel MuGFETs (triple-gate) Bulk transistors with and without the application of DTMOS operation. This work will be done through three-dimensional numerical simulation and by electrical characterizations. The drain current, transconductance, resistance, threshold voltage, subthreshold swing and Drain Induced Barrier Lowering (DIBL) will be analyzed in the DTMOS mode and the standard biasing configuration. Important figures of merit for the analog performance such as transconductance-over-drain current, output conductance, Early voltage and intrinsic voltage gain will be studied experimentally and through three-dimensional numerical simulations for different channel doping concentrations. The results indicate that the DTMOS configuration has superior electrical characteristics (4 e 10 %) and higher transistor efficiency. In addition, DTMOS devices with a high channel doping concentration exhibit much better analog performance compared to the normal operation mode. Low-Frequency (LF) noise is for the first time experimentally investigated in linear and saturation region. The origin of the noise will be analyzed in order to understand the physical mechanisms involved in this type of noise. Measurements showed that the signal spectra for Bulk and DTMOS are composed of number fluctuations related flicker noise with on top generation and recombination noise humps, which become more pronounced at higher gate voltage. However, the most important finding is the fact that DTMOS devices showed practically the same LF noise magnitude in linear and saturation region than standard Bulk device. Proton irradiation with energy of 60 MeV and fluence of p/1012 cm-2 is also experimentally studied in terms of electric characteristic, analog performance and the LF noise in Bulk and DTMOS triple gate devices. The results indicate that the combined of the better electrical characteristics and an excellent analog performance of DTMOS devices, makes it a very competitive candidate for low-noise RF analog applications before and after irradiation. The advantage of dynamic threshold voltage in triple gate transistors in environments where the devices have to withstand high-energy radiation is due to its lower drain electric field penetration that lowers the effect of the radiation-induced charges in the STI (shallow trench isolation) regions adjacent to the fin. Finally, the n-channel triple gate Bulk device is used for memory application, that is, 1T-DRAM (Dynamic Random Access Memory with 1 Transistor). Bipolar junction transistor (BJT) programming mode is used to write and read 1 while the forward biasing of the body-drain junction is used to write 0. The reading and writing current increases with increasing body bias (VB) because the load induced by the BJT effect is stored within the fin. When the body of the transistor is floating, the device retains more charge within its fin. In addition, transistor could also operate as 1T-DRAM with both gate and bulk contacts floating, which is similar to the biristor (gateless) behavior.

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Deloupy, Alexandre. "Expression stochastique des gènes chez Bacillus subtilis". Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS443.

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Une population d'individus génétiquement identiques partageant le même environnement présente une certaine variabilité phénotypique résiduelle. Cette hétérogénéité découle de la nature stochastique, ou aléatoire, de l'expression des gènes, également appelée bruit. Cette stochasticité résulte d'une part de la rencontre aléatoire d'espèces chimiques pendant la transcription et la traduction (bruit intrinsèque), et d'autre part des fluctuations dans la concentration de ces substances chimiques (bruit extrinsèque). Un modèle stochastique ne faisant intervenir que le bruit intrinsèque prédit que la force du bruit phénotypique varie linéairement avec l'efficacité de la traduction, mais qu'il ne dépend pas du taux de transcription. Cette prédiction s'est révélée compatible avec des données portant sur un nombre limité de souches et de conditions, mais n'a jamais été entièrement testée sur un grand nombre de souches ayant différentes efficacités de transcription et de traduction. Notre objectif est d'aller plus loin dans le test de cette prédiction en utilisant une collection d'une quarantaine de souches de la bactérie Bacillus subtilis où la protéine GFP est exprimée sous le contrôle de différents promoteurs, TSS et RBS. Pour chaque souche, l'hétérogénéité entre cellules est étudiée en quantifiant le signal de fluorescence au niveau de la cellule unique, à l'aide de techniques de cytométrie en flux et de microscopie en épifluorescence. Nos résultats montrent que, contrairement aux attentes, la force du bruit phénotypique montre une forte corrélation positive avec l'efficacité transcriptionnelle. Nous avons démontré que sur une large gamme d'expression couvrant la majeure partie du protéome de B. subtilis, le bruit d'expression est dominé par les sources de bruit extrinsèques. Par conséquent, les modèles stochastiques d'expression génique ne conviennent pas pour quantifier les effets de la traduction et de la transcription sur le bruit d'expression génétique
A population of genetically identical individuals sharing the same environment exhibits some residual phenotypic variability. Such heterogeneity arises from the stochastic, or random, nature of gene expression also referred as noise. This stochasticity results on the one hand from the random encounter of chemical species during both transcription and translation (intrinsic noise), and on the other hand from the fluctuations in the concentration of these chemicals (extrinsic noise). A stochastic model involving only intrinsic noise predicts that phenotypic noise strength varies linearly with translational efficiency but does not depend on transcriptional one. This prediction was shown to be compatible with data on a limited number of strains and conditions but has never been fully tested on a large collection of strains with different transcription and translation efficiencies. We aim to go further in the test of this prediction by using a collection of ~40 strains of the bacterium Bacillus subtilis where GFP is expressed under the control of different Promoters, TSS and RBS. For each strain, cell-to-cell heterogeneity is investigated by quantifying fluorescence signal at the single cell level, based on flow cytometry techniques and epifluorescence microscopy. Our results show that, contrary to expectations, phenotypic noise strength shows a strong positive correlation with transcriptional efficiency. We demonstrated that over a wide range of expression covering most of the proteome of B. subtilis, the expression noise is dominated by external noise sources. Therefore, stochastic models of gene expression are not suitable for quantifying the effects of translation and transcription on gene expression noise

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Al, Roumi Fosca. "Théorie Lagrangienne Relativiste de la Formation des Grandes Structures : description Intrinsèque des Perturbations et Gravitoélectromagnétisme". Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10136/document.

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La dynamique de formation des structures de l'Univers est habituellement décrite dans le cadre du modèle standard de Cosmologie. Cependant, pour que les observations cosmologiques soient cohérentes avec le modèle standard, il est nécessaire de supposer l'existence d'une grande proportion d'éléments de nature inconnue dans le contenu de l'Univers. Pour tenter de résoudre cette énigme, nous ne considèrerons pas d'autres sources dans le contenu de l'Univers que celles ordinaires et resterons dans le cadre de la Relativité Générale. Nous développerons néanmoins une description plus réaliste de la formation de structures dans le cadre de la théorie d'Einstein. Ainsi, contrairement au modèle standard de Cosmologie, nous ne supposerons pas que l'Univers moyenné est une solution homogène et isotrope des équations d'Einstein. Lors de mon travail sous la direction de Thomas Buchert, j'ai participé au développement d'un formalisme perturbatif permettant une description plus réaliste de la dynamique de l'espace-temps. J'ai également contribué à l'obtention de solutions relativistes à la partie gravitoélectrique des équations d'Einstein en généralisant les solutions perturbatives newtoniennes. Ces travaux ont été réalisés dans le cadre d'une approche lagrangienne intrinsèque, évitant ainsi de définir les grandeurs physiques sur un fond plat. L'approche gravitoélectromagnétique que j'ai adoptée m'a permis une interprétation nouvelle et performante des solutions des équations d'Einstein. Enfin, j'ai étudié l'impact de la topologie sur la dynamique des ondes gravitationelles à l'aide d'une description globale de l'hypersurface spatiale, permise par des théorèmes mathématiques puissants
The dynamics of structure formation in the Universe is usually described by Newtonian numerical simulations and analytical models in the frame of the Standard Model of Cosmology. The structures are then defined on a homogeneous and isotropic background. Such a description has major drawbacks since, to be self-consistent, it entails a large amount of dark components in the content of the Universe. To address the problem of dark matter and dark energy, we will neither suppose that exotic sources contribute to the content of the Universe, nor that General Relativity is obsolete. We will develop a more realistic description of structure formation in the frame of General Relativity and thus no longer assume that the average model is a homogeneous-isotropic solution of the Einstein equations, as claimed by the Standard Model of Cosmology. During my work under the supervision of Thomas Buchert, I contributed to the development of the perturbative formalism that enables a more realistic description of spacetime dynamics. In the framework of the intrinsic Lagrangian approach, which avoids defining physical quantities on a flat background, I contributed to the building of relativistic solutions to the gravitoelectric part of the Einstein equations from the generalization of the Newtonian perturbative solutions. Moreover, the gravitoelectromagnetic approach I worked with has provided a new understanding of the dynamics of the analytical solutions to the field equations. Finally, treating globally the spatial manifold, I used powerful mathematical tools and theorems to describe the impact of topology on the dynamics of gravitational waves

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Chung, Tien-Shen, e 鍾天伸. "Intrinsic noise in genetic regulation networks". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/23227796124027063488.

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碩士
中原大學
應用物理研究所
95
In this thesis, we investigate the intrinsic noise in transcription and translation level of genetic regulation networks without environmental conditions. The genetic regulation networks can be mathematically described by rate equations. To obtain the stochastic features of the system, the macroscopic rate equation is first rewritten as the stochastic master equation, and then expansion method is used to obtain the linear noise Fokker-Planck equation. We use the linear noise Fokker-Planck equation to analyze the stochastic fluctuations in the regulation networks of single gene and toggle switch. The noise strength is measured by Fano Factor which is defined as variance over mean, and the correlation of noise is also analyzed. The effect of regulation strength on the characteristics of noises and discussed.

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Lin, Yi-Min, e 林益民. "Lossy Substrate De-embedding Method for RF MOSFET Intrinsic Noise Extraction". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/45213202486085666236.

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碩士
國立交通大學
電子工程系所
94
For sub-100nm MOSFETs with the gate length scaling to 80 nm and 65 nm, the unit current gain cut off frequency (fT) can achieve as high as 100 GHz and 165 GHz, respectively. However, the as-measured noise figure shows no much difference between 80 nm and 65 nm devices. The minimum noise figure (NFmin) is even higher than 5dB at 10GHz under gate bias responsible for the maximum fT. Strong finger number dependence of noise figure was also observed. All the mentioned phenomena can not be simply explained by gate resistance reduction through multi-finger structure. It suggests that noise de-embedding is required for the as-measured noise parameters. In this thesis, the basic noise theory of MOSFET, noise measurement principles and instruments will be covered in the first place. Conventional noise correlation matrix de-embedding method will be reviewed. Regarding the intrinsic MOSFET model, I-V and C-V model calibration have been done based on the measured I-V, transconductance, and admittance by Y-parameters. Then discussion of different probing pad effect on device characterization and the corresponding equivalent circuit model has been established and extensively verified. A new equivalent circuit de-embedding method was proposed. Modeling of as-measured S-parameters and noise parameters was done by incorporating the pad model with a well calibrated MOSEFT model. The lossy pad and lossy substrate de-embedding has been conducted to obtain the intrinsic characteristic. Finally, the intrinsic performance of the device will be analyzed and discussed.

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Libri sul tema "Intrinsic noise"

Fermüller, Cornelia. Motion Illusions in Man and Machine. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780199794607.003.0006.

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At the level of mathematical abstraction, computing image motion amounts to an estimation problem and can be analyzed using the tools of statistics and signal processing. As shown in this chapter, intrinsic limitations to the estimation processes make it impossible to derive veridical estimates for all images. Image motion is estimated erroneously, and as a result higher level processes compute erroneous three-dimensional motion and moving scenes. Specifically, two limitations are discussed: (a) due to noise in image data, there is statistical bias that affects anisotropic patterns and (2) the filters computing changes in time are asymmetric (causal), using data only from the past but not the future, and misestimate on locally asymmetric intensity signals of certain spatial frequencies. Since these limitations are not an artifact of the hardware but are inherent to the computations, they will affect any system and thus create illusions in man and machine.

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Alvesson, Mats, Yiannis Gabriel e Roland Paulsen. Return to Meaning. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198787099.001.0001.

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This book argues that we are currently witnessing not merely a decline in the quality of social science research, but a proliferation of meaningless research of no value to society and modest value to its authors—apart from securing employment and promotion. The explosion of published outputs, at least in social science, creates a noisy, cluttered environment which makes meaningful research difficult, as different voices compete to capture the limelight even briefly. Older, but more impressive contributions are easily neglected as the premium is to write and publish, not read and learn. The result is a widespread cynicism among academics on the value of academic research, sometimes including their own. Publishing comes to be seen as a game of hits and misses, devoid of intrinsic meaning and value and of no wider social uses whatsoever. This is what the book views as the rise of nonsense in academic research, which represents a serious social problem. It undermines the very point of social science. This problem is far from ‘academic’. It affects many areas of social and political life entailing extensive waste of resources and inflated student fees as well as costs to taxpayers. The book’s second part offers a range of proposals aimed at restoring meaning at the heart of social science research, and drawing social science back, address the major problems and issues that face our societies.

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Capitoli di libri sul tema "Intrinsic noise"

Fish, Peter J. "Intrinsic Noise". In Electronic Noise and Low Noise Design, 72–90. London: Macmillan Education UK, 1993. http://dx.doi.org/10.1007/978-1-349-23060-0_4.

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Weik, Martin H. "intrinsic noise". In Computer Science and Communications Dictionary, 833. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_9552.

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Wang, Ruiqi. "Noise, Intrinsic and Extrinsic". In Encyclopedia of Systems Biology, 1527. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4419-9863-7_353.

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Hanke, Ulrik, Yu Galperin e K. A. Chao. "Intrinsic Noise in Coulomb-Blockaded Devices". In Quantum Dynamics of Submicron Structures, 411–26. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0019-9_32.

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Hazelwood, Richard A., e Patrick C. Macey. "Intrinsic Directional Information of Ground Roll Waves". In The Effects of Noise on Aquatic Life II, 447–53. New York, NY: Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4939-2981-8_53.

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Mackey, Michael C., Moisés Santillán, Marta Tyran-Kamińska e Eduardo S. Zeron. "Noise Effects in Gene Regulation: Intrinsic Versus Extrinsic". In Lecture Notes on Mathematical Modelling in the Life Sciences, 49–69. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-45318-7_4.

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Saito, Atsushi, Manabu Abe, Akinobu Irie, Gin-ichiro Oya e Katsuyoshi Hamasaki. "Low Frequency Noise Properties of Bi2Sr2CaCu2Oy Intrinsic Josephson Junctions". In Advances in Superconductivity XII, 1120–22. Tokyo: Springer Japan, 2000. http://dx.doi.org/10.1007/978-4-431-66877-0_331.

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Adamu-Lema, F., C. Monzio Compagnoni, O. Badami, V. Georgiev e A. Asenov. "RTN and Its Intrinsic Interaction with Statistical Variability Sources in Advanced Nano-Scale Devices: A Simulation Study". In Noise in Nanoscale Semiconductor Devices, 441–66. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-37500-3_13.

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Soyel, Hamit, Kamil Yurtkan, Hasan Demirel e Peter W. McOwan. "Brain MR Image Denoising for Rician Noise Using Intrinsic Geometrical Information". In Lecture Notes in Electrical Engineering, 275–84. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-22635-4_25.

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Sternad, Dagmar, Meghan E. Huber e Nikita Kuznetsov. "Acquisition of Novel and Complex Motor Skills: Stable Solutions Where Intrinsic Noise Matters Less". In Advances in Experimental Medicine and Biology, 101–24. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-1338-1_8.

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Atti di convegni sul tema "Intrinsic noise"

Stienstra, A., A. S. Badger e P. W. Maxwell. "Intrinsic noise in geophones". In 55th EAEG Meeting. European Association of Geoscientists & Engineers, 1993. http://dx.doi.org/10.3997/2214-4609.201411481.

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Buvin, G. M., e A. M. Shvachkin. "Microwave Diode Intrinsic LF Noise Measurements". In 2007 17th International Crimean Conference - Microwave & Telecommunication Technology. IEEE, 2007. http://dx.doi.org/10.1109/crmico.2007.4368910.

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Rigling, Brian D. "Intrinsic processing gains in noise radar". In 2006 International Waveform Diversity & Design Conference. IEEE, 2006. http://dx.doi.org/10.1109/wdd.2006.8321462.

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Corral, Elena Pascual, Raúl Rengel, María J. Martín, Massimo Macucci e Giovanni Basso. "Intrinsic Noise Sources in a Schottky Barrier MOSFET: a Monte Carlo Analysis". In NOISE AND FLUCTUATIONS: 20th International Conference on Noice and Fluctuations (ICNF-2009). AIP, 2009. http://dx.doi.org/10.1063/1.3140465.

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Tóth, L., M. Koós e I. Pócsik. "Electrical conductivity noise in intrinsic a-Si:H at low frequencies". In Noise in physical systems and 1/. AIP, 1993. http://dx.doi.org/10.1063/1.44589.

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Duan, Lingze. "Intrinsic Thermodynamic Noise in Passive Fiber Systems". In Frontiers in Optics. Washington, D.C.: OSA, 2012. http://dx.doi.org/10.1364/fio.2012.fth1d.7.

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Yin, Haibing, Yadong Liu, Zongtan Zhou, Ming Li, Yucheng Wang e Dewen Hu. "Structured noise analysis in intrinsic optical imaging". In 2010 9th IEEE International Conference on Cognitive Informatics (ICCI). IEEE, 2010. http://dx.doi.org/10.1109/coginf.2010.5599711.

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Allen, B. F., F. Picon, S. Dalibard, N. Magnenat-Thalmann e D. Thalmann. "Localizing a mobile robot with intrinsic noise". In 2012 3DTV-Conference: The True Vision - Capture, Transmission and Display of 3D Video (3DTV-CON 2012). IEEE, 2012. http://dx.doi.org/10.1109/3dtv.2012.6365480.

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Ren, L., e F. N. Hooge. "Intrinsic and extrinsic 1/f noise sources in irradiated n-GaAs". In Noise in physical systems and 1/. AIP, 1993. http://dx.doi.org/10.1063/1.44629.

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García-Loureiro, A. J. "Intrinsic fluctuations induced by a high-κ gate dielectric in sub-100 nm Si MOSFETs". In NOISE AND FLUCTUATIONS: 18th International Conference on Noise and Fluctuations - ICNF 2005. AIP, 2005. http://dx.doi.org/10.1063/1.2036740.

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Rapporti di organizzazioni sul tema "Intrinsic noise"

Webb, Kevin J. Development of a Noise Intrinsic Equivalent Circuit Model Using Experimental and Numerical Techniques. Fort Belvoir, VA: Defense Technical Information Center, novembre 2005. http://dx.doi.org/10.21236/ada441362.

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