Thèses sur le sujet « Translation de signal à signal »
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Ponnala, Lalit. « Analysis of Genetic Translation using Signal Processing ». NCSU, 2007. http://www.lib.ncsu.edu/theses/available/etd-02072007-174200/.
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A series of free energy estimates can be calculated from the ribosome's progressive interaction with mRNA sequences during the process of translation elongation in eubacteria. A sinusoidal pattern of roughly constant phase has been detected in these free energy signals. Frameshifts of the +1 type occur when the ribosome skips an mRNA base in the 5'-3' direction, and can be associated with local phase-shifts in the free energy signal. We propose a mathematical model that captures the mechanism of frameshift based on the information content of the signal parameters and the relative abundance of tRNA in the bacterial cell. The model shows how translational speed can modulate translational accuracy to accomplish programmed +1 frameshifts and could have implications for the regulation of translational efficiency. Results are presented using experimentally verified frameshift genes across eubacteria.
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Girault, Benjamin. « Signal Processing on Graphs - Contributions to an Emerging Field ». Thesis, Lyon, École normale supérieure, 2015. http://www.theses.fr/2015ENSL1046/document.
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Ce manuscrit introduit dans une première partie le domaine du traitement du signal sur graphe en commençant par poser les bases d'algèbre linéaire et de théorie spectrale des graphes. Nous définissons ensuite le traitement du signal sur graphe et donnons des intuitions sur ses forces et faiblesses actuelles comparativement au traitement du signal classique. En seconde partie, nous introduisons nos contributions au domaine. Le chapitre 4 cible plus particulièrement l'étude de la structure d'un graphe par l'analyse des signaux temporels via une transformation graphe vers série temporelle. Ce faisant, nous exploitons une approche unifiée d'apprentissage semi-supervisé sur graphe dédiée à la classification pour obtenir une série temporelle lisse. Enfin, nous montrons que cette approche s'apparente à du lissage de signaux sur graphe. Le chapitre 5 de cette partie introduit un nouvel opérateur de translation sur graphe définit par analogie avec l'opérateur classique de translation en temps et vérifiant la propriété clé d'isométrie. Cet opérateur est comparé aux deux opérateurs de la littérature et son action est décrite empiriquement sur quelques graphes clés. Le chapitre 6 décrit l'utilisation de l'opérateur ci-dessus pour définir la notion de signal stationnaire sur graphe. Après avoir étudié la caractérisation spectrale de tels signaux, nous donnons plusieurs outils essentiels pour étudier et tester cette propriété sur des signaux réels. Le dernier chapitre s'attache à décrire la boite à outils \matlab développée et utilisée tout au long de cette thèseThis dissertation introduces in its first part the field of signal processing on graphs. We start by reminding the required elements from linear algebra and spectral graph theory. Then, we define signal processing on graphs and give intuitions on its strengths and weaknesses compared to classical signal processing. In the second part, we introduce our contributions to the field. Chapter 4 aims at the study of structural properties of graphs using classical signal processing through a transformation from graphs to time series. Doing so, we take advantage of a unified method of semi-supervised learning on graphs dedicated to classification to obtain a smooth time series. Finally, we show that we can recognize in our method a smoothing operator on graph signals. Chapter 5 introduces a new translation operator on graphs defined by analogy to the classical time shift operator and verifying the key property of isometry. Our operator is compared to the two operators of the literature and its action is empirically described on several graphs. Chapter 6 describes the use of the operator above to define stationary graph signals. After giving a spectral characterization of these graph signals, we give a method to study and test stationarity on real graph signals. The closing chapter shows the strength of the matlab toolbox developed and used during the course of this PhD
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Messaoud, Safa. « Translating Discrete Time SIMULINK to SIGNAL ». Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/49299.
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As Cyber Physical Systems (CPS) are getting more complex and safety critical, Model Based
Design (MBD), which consists of building formal models of a system in order to be used in
verification and correct-by-construction code generation, is becoming a promising methodology
for the development of the embedded software of such systems. This design paradigm
significantly reduces the development cost and time while guaranteeing better robustness,
capability and correctness with respect to the original specifications, when compared with
the traditional ad-hoc design methods. SIMULINK has been the most popular tool for embedded
control design in research as well as in industry, for the last decades. As SIMULINK
does not have formal semantics, the application of the model based design methodology and
tools to its models is very limited. In this thesis, we present a semantic translator that
transform discrete time SIMULINK models into SIGNAL programs. The choice of SIGNAL
is motivated by its polychronous formalism that enhances synchronous programming with
asynchronous concurrency, as well as, by the ability of its compiler of generating deterministic
multi thread code. Our translation involves three major steps: clock inference, type
inference and hierarchical top-down translation. We validate the semantic preservation of
our prototype tool by testing it on different SIMULINK models.Master of Science
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Mittermayr, Lukas Verfasser], et Dario Michael [Akademischer Betreuer] [Leister. « Identification of factors involved in the translation : dependant signal transduction process / Lukas Mittermayr. Betreuer : Dario Leister ». München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/1070464910/34.
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De, Laurentiis Evelina Ines. « Kinetic analyses on two translational GTPases : LepA and EF-Tu ». Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Chemistry and Biochemistry, 2013. http://hdl.handle.net/10133/3450.
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Protein synthesis is an essential process for all living organisms and is an effective major target for current antibiotics. Elongation factor Tu (EF-Tu) is a highly conserved and essential protein that functions during protein synthesis. EF-Ts interacts with EF-Tu to help maintain a functionally active state of EF-Tu required for cell growth. Although EF-Ts is essential for Escherichia coli, its sequence is poorly conserved. LepA is a highly conserved protein within bacteria and has a similar structure to EF-Tu. In spite of this, LepA has been shown to be non-essential under ideal conditions and the function of LepA still remains elusive. An analysis on the structurally unique aspects of LepA, EF-Tu and EF-Ts was performed here in an effort to gain an understanding on the functions of these proteins. This knowledge, in combination with their unique structural components will provide important tools in developing new and effective antibiotics.xiii, 177 leaves : col. ill. ; 29 cm
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Jacquet, Gottfried. « Hybrid physics-based/data-based seismic ground motion generator of a site ». Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST035.
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L'estimation précise de la réponse sismique suite à un tremblement de terre permet de sauver des vies. Toutefois, la limitation des ressources informatiques et la variabilité méconnue et mal caractérisée de la géologie et du con- texte sismotectonique posent des défis significatifs pour les simulations à l'échelle d'une ville ou d'une région. Cette thèse propose une nouvelle approche combinant les méthodes d'apprentissage adverse (adversarial) et les simulations basées sur la physique pour surmonter ces limitations, en s'appuyant sur le cadre SeismoALICE, (F. GATTI et D. CLOUTEAU: "Towards blending Physics-Based numerical simulations and seismic databases using Generative Adversarial Network", CMAME 2020). En raison des fluctuations aléatoires des propriétés mécaniques du milieu géologique, les simulations numériques ne peuvent donner des résultats que pour les basses fréquences (BF) jusqu'à 5 voire 10 Hz. La fréquence de conception des structures et des équipements en génie civil atteint en revanche 40 Hz. Cette thèse vise à simuler des signaux sismiques plus riches en fréquences [0 - 30 Hz] à partir de la connaissance des signaux à basses fréquences et d'une base de données de signaux enregistrés. Dans ce but, nous développons un encodeur et un décodeur adaptés aux signaux sismiques utilisant une variante des techniques d'attention, nommée Conformer, pour capturer les corrélations de longue durée présentes dans les accélérogrammes. Le discriminateur, assurant que les signaux simulés ressemblent à des signaux enregistrés, a fait l'objet d'un développement poussé, permettant d'optimiser l'encodeur et le décodeur par le biais d'une technique de min-max au cœur des méthodes adverses d'apprentissage machine. Pour forcer a reconstruction des signaux, nous adaptons aux séries temporelles la Focal Frequency Loss (FFL) et la Hyper-Spherical Loss (HSL), qui sont plus performantes pour ce type de données. Ensuite, nous complétons les signaux BF jusqu'à 30 Hz en explorant différents cas de génération : mapping one-to-one et mapping one-to-many pour évaluer la plausibilité des reconstructions de la base de données. Cinq méthodes ont été élaborées : Signal-to-Signal Translation, SeismoALICE with shared latent space, SeismoALICE with factorized latent space, BicycleGAN for time series et Multi-Modal Signal Translation. Leur performance a été évaluée avec le Goodness-of-Fit de Kristeková. Nous avons prouvé en manipulant les variables cachées qu'il est possible de diviser l'information en deux groupes de variables de distributions Gaussiennes, l'un pour les basses fréquences et l'autre pour les hautes fréquences. Cette interprétabilité a permis de manipuler l'espace latent et de contrôler le mapping one-to-many. Les modèles, entraînés sur 128 000 signaux sismiques de la base de données des séismes de Stanford (STEAD), dé- montrent leur performance avec des qualités de prédiction allant de bonnes à excellentes. Finalement, leur efficacité a été démontrée par une application au séisme du Teil de 2019 (en Ardèche dans la région Auvergne-Rhone-Alpes, France). Ce travail ouvre la voie à une prédiction plus précise et plus efficace des signaux sismiques en intégrant de manière transparente les connaissances basées sur la physique et l'apprentissage machineAccurately estimating the seismic response following an earthquake can save lives. However, limited computational resources and poorly characterized and unknown variability in geology and seismotectonic context pose significant challenges for simulations at the scale of a city or region. This thesis proposes a new approach com- bining adversarial learning methods and physics-based simulations to overcome these limitations, based on the SeismoALICE framework (F. GATTI and D. CLOUTEAU: "Towards blending Physics-Based numerical simulations and seismic databases using Generative Adversarial Network," CMAME 2020). Because of the random fluctuations in the mechanical properties of the geological medium, numerical simulations can only give results for low frequencies (LF) down to 5 or even 10 Hz. The design frequency for civil engineering structures and equipment, on the other hand, reaches 40 Hz. This thesis aims to simulate seismic signals with a higher frequency range [0 - 30 Hz] using knowledge of low-frequency signals and a database of recorded signals. To this end, we are developing an encoder and decoder adapted to seismic signals using a Conformer variant of attention techniques to capture the long-duration correlations present in accelerograms. The discriminator, which ensures that simulated signals resemble recorded signals, has been the subject of extensive development, enabling the encoder and decoder to be optimized using a min-max technique at the heart of adversarialmachine learning methods. To force signal recon- struction, we adapt Focal Frequency Loss (FFL) and Hyper-Spherical Loss (HSL), which are more efficient for this data type, to time series. We then complement the LF signals up to 30 Hz by ex- ploring different generation cases, one-to-one map- ping, and one-to-many mapping to assess the plausibility of the reconstructions in the database. Five methods were developed: Signal-to-Signal Translation, SeismoALICE with shared latent space, SeismoALICE with factorized latent space, BicycleGAN for time series, and Multi-Modal Signal Translation. Their performance was evaluated using Kristeková's Goodness-of-Fit. By manipulating the hidden variables, we proved that it is possible to divide the information into two groups of variables with Gaussian distributions, one for low frequencies and the other for high frequencies. This interpretability made it possible to manipulate the latent space and control the one-to-many mapping. The models, trained on 128,000 seismic signals from the Stanford Earthquake Database (STEAD), demonstrated their performance, with prediction qualities ranging from good to excellent. Finally, their effectiveness was demonstrated by application to the 2019 Le Teil earthquake (in the Ardèche region of Auvergne-Rhone-Alpes, France). This work paves the way for more accurate and efficient prediction of seismic signals by seamlessly integrating physics-based knowledge and machine learning
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Kerins, Michael John, Ajay Amar Vashisht, Benjamin Xi-Tong Liang, Spencer Jordan Duckworth, Brandon John Praslicka, James Akira Wohlschlegel et Aikseng Ooi. « Fumarate Mediates a Chronic Proliferative Signal in Fumarate Hydratase-Inactivated Cancer Cells by Increasing Transcription and Translation of Ferritin Genes ». AMER SOC MICROBIOLOGY, 2017. http://hdl.handle.net/10150/624216.
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Germ line mutations of the gene encoding the tricarboxylic acid (TCA) cycle enzyme fumarate hydratase (FH) cause a hereditary cancer syndrome known as hereditary leiomyomatosis and renal cell cancer (HLRCC). HLRCC-associated tumors harbor biallelic FH inactivation that results in the accumulation of the TCA cycle metabolite fumarate. Although it is known that fumarate accumulation can alter cellular signaling, if and how fumarate confers a growth advantage remain unclear. Here we show that fumarate accumulation confers a chronic proliferative signal by disrupting cellular iron signaling. Specifically, fumarate covalently modifies cysteine residues on iron regulatory protein 2 (IRP2), rendering it unable to repress ferritin mRNA translation. Simultaneously, fumarate increases ferritin gene transcription by activating the NRF2 (nuclear factor [erythroid-derived 2]-like 2) transcription factor. In turn, increased ferritin protein levels promote the expression of the promitotic transcription factor FOXM1 (Forkhead box protein M1). Consistently, clinical HLRCC tissues showed increased expression levels of both FOXM1 and its proliferation-associated target genes. This finding demonstrates how FH inactivation can endow cells with a growth advantage.
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Hamirally, Sofia. « Mechanistic studies of the translational readthrough signal of Moloney murine leukemia virus ». Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619933.
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Colberg, Clara Ottilie Freifrau Loeffelholz von. « Etudes au microscope électronique du transport des protéines durant la traduction chez E. Coli, et de la terminaison de la traduction chez l'homme ». Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENV038/document.
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La particule de reconnaissance du signal (signal recognition particle-SRP) et son récepteur (FtsY chez Escherichia coli) médiatise le processus simultané de traduction-ciblage de la protéine en dirigeant le complexe ribosome-nascent chain (RNCs) vers la membrane de destination. La reconnaissance par la SRP d'une charge RNC à transporter dépend de la présence de la partie N-terminale. L'assemblage de Ftsy au complexe RNC-PRS entraine plusieurs changements de configuration de SRP et de FtsY durant le cycle de direction. D'abord un stade « précoce » sans GTP est adopté. Celui-ci est stabilisé par le RNC. Ensuite une configuration « fermée » avec GTP est formée. Cette dernière peut s'activer pour hydrolyser GTP, elle entre alors dans sa configuration « active ». La succession de ces trois étapes conduit à la libération du complexe SRP-récepteur d'avec le ribosome et de sa protéine en cours de traduction, et leur mise à disposition au pore de la membrane. Dans ce projet, notre intérêt se limite à la traduction par le ribosome de la séquence signale EspP (RNCEspP). In vivo, EspP est une protéine dont le ciblage vers le récepteur membranaire se réalise après la traduction. Cependant il arrive que RNCEspP se lie au complexe SRP-FtsY, faisant échouer le ciblage. Nous avons étudié les bases structurales du rejet de RNCEspP par SRP et FtsY. Pour cela nous avons effectué la comparaison de la structure RNCEspP-SRP-FtsY obtenue par observation au cryo-microscope électronique avec d'autres complexes ribosome-SRP-récepteurs traduisant la charge FtsQ, qui est elle normalement ciblé par SRP. Nous avons cherché à observer la différence de structure entre les complexes SRP-FtsY dans les deux cas. Deux différences majeurs entre les complexes de ciblages contenants les séquences RNCFtsQ et RNCEspP ont été observés. Premièrement, dans le cas de la structure de RNCEspP le domaine M -Ffh est attaché à l'hélice 59 du ribosome, alors que celui-ci est détaché dans le cas de la structure de RNCFtsQ. Nous pensons que le domaine M empêche la libération de la séquence de signal, étape nécessaire à la réalisation du ciblage. Deuxièmement, dans le cas de la structure du complexe avec RNCEspP l'arrangement Ffh-FtsY avec le domaine NG était flexible. Ceci indiquerait que le complexe “précoce” formé sur RNCEspP est moins stable que celui formé sur RNCFtsQ. Une étude biochimique utilisant le transfert d'énergie via résonance fluorescente a corroboré ce résultat, montrant que FTS Y est lié avec une affinité moindre dans le cas du complexe précoce formé sur RNCEspP et que la reconfiguration au stade de complexe fermé est moins efficace. Une analyse biochimique plus poussée des variantes de la séquence de EspP montre que la partie N-Terminale de la séquence est la principale cause de rejet du cycle de ciblage via SRP.Dans un second projet, nous avons étudié la configuration “fermée” de SRP et ftsY en complexe avec une charge RNC stabilisée par un analogue non-hydrolysable de GTP (GMP-PCP). Pour franchir la barrière cinétique qui permet de passer du complexe précoce au complexe fermé, nous avons utilisé une version tronquée de FtsY, à laquelle la séquence terminale avait été amputée de tout le domaine acide (A-) ainsi que de la première hélice alpha du domaine NG. De plus, pour la formation du complexe, nous avons utilisé une construction contenant les 50 premiers acides aminés du leader peptidase (RNCLep50). En l'absence de nucléotides, notre reconstruction au cryo-EM a montré une configuration similaire à celle du stade précoce, dans laquelle Ftsy et Ffh- domaine NG, sont proche du tetraloop de la 4.5 S ARN. Une incubation avec GMP-PCP induit un détachement du domaine NG d'avec la queue du tetraloop. Il semblerait que les domaines NG soient flexibles dans l'état clos, et non attaché à la terminaison ouverte de l'ARNThe signal recognition particle (SRP) and its receptor (FtsY in Escherichia coli) mediate co-translational protein targeting by delivering ribosome nascent chain complexes (RNCs) to the target membrane. Recognition of an RNC cargo by SRP is dependent on an N-terminal signal sequence. Binding of FtsY to the RNC-SRP complex leads to several conformational changes of SRP and FtsY during the targeting cycle: first, an “early” GTP-independent state is adopted which is stabilized by the RNC, subsequently a “closed” GTP- dependent conformation is formed which can activate itself to hydrolyze GTP (the “activated” state). Faithful completion of all three steps leads to release of the cargo from SRP-FtsY and hand over of the RNC to the translocation pore.It has been shown for E. coli that cargos can be rejected from the SRP pathway during all targeting steps. In the first project, our interest concentrates on ribosomes translating the EspP signal sequence (RNCEspP). In vivo, EspP is a post-translationally targeted protein, but RNCEspP has been shown to be bound by SRP and FtsY leading to a non-productive “early”-like RNCEspP-SRP-FtsY complex. Using single particle cryo-electron microscopy (EM), we analysed the structural basis for the rejection of RNCEspP by SRP and FtsY. Comparison of our RNCEspP-SRP-FtsY cryo-EM structure to other available cryo-EM structures of co-translational targeting complexes containing the correct cargo RNCFtsQ unravelled differences in the SRP-FtsY structure between a correct cargo and an incorrect cargo. Two major differences between the targeting complexes containing the cargos RNCFtsQ and RNCEspP were observed: first, the Ffh M-domain was attached to ribosomal RNA helix 59 of RNCEspP, while it was detached from this site in the case of RNCFtsQ. It could be that such an ordered M-domain is hampering the release of the signal sequence which is required for successful completion of targeting. Second, the Ffh-FtsY NG-domain arrangement was flexible in the complex with RNCEspP in comparison to RNCFtsQ indicating that the "early"-like complex formed on RNCEspP is less stable. Biochemical data using fluorescence resonance energy transfer corroborated these results, showing that FtsY is bound with lower affinity in the RNCEspP “early” complex and that the rearrangement to the “closed” conformation is less efficient. Further biochemical analysis of EspP signal sequence variants showed that mainly the N-terminal extension of the EspP signal sequence is responsible for its rejection from the SRP pathway
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Ma, Chon Teng. « Biopotential readout front-end circuits using frequency-translation filtering techniques ». Thesis, University of Macau, 2010. http://umaclib3.umac.mo/record=b2182904.
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Ngô, Van Chan. « Formal verification of a synchronous data-flow compiler : from Signal to C ». Phd thesis, Université Rennes 1, 2014. http://tel.archives-ouvertes.fr/tel-01067477.
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Synchronous languages such as Signal, Lustre and Esterel are dedicated to designing safety-critical systems. Their compilers are large and complicated programs that may be incorrect in some contexts, which might produce silently bad compiled code when compiling source programs. The bad compiled code can invalidate the safety properties that are guaranteed on the source programs by applying formal methods. Adopting the translation validation approach, this thesis aims at formally proving the correctness of the highly optimizing and industrial Signal compiler. The correctness proof represents both source program and compiled code in a common semantic framework, then formalizes a relation between the source program and its compiled code to express that the semantics of the source program are preserved in the compiled code.
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Tran, Thi Bich-Ha. « Modélisation du bruit d'intensité des lasers InGaAsP : étude de la translation du bruit basse fréquence dans la bande du signal de modulation ». Toulouse, ENSAE, 1997. http://www.theses.fr/1997ESAE0010.
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Le bruit relatif d'intensité (RIN) d'un laser à semiconducteur est un facteur déterminant dans la conception de systèmes de communication analogiques à fibres optiques. Le phénomène de remontée du RIN aux relativement basses fréquences (<1 GHz) est expliqué par l'introduction d'un gain non linéaire asymétrique dans les équations d'évolution traduisant un couplage entre les modes longitudinaux d'un laser qu'il soit multimode (Fabry-Pérot) ou quasi-monomode (DFB). En présence d'une modulation d'amplitude, la partie basse fréquence du spectre du RIN est transférée dans la bande du signal par battement avec lui. Il en résulte une dégradation des performances du système de transmission analogique en terme de rapport signal-sur-bruit. Pour décrire précisément le comportement du RIN en l'absence ou en présence de modulation sinusoïdale directe, nous avons développé un modèle (bimode) de laser InGaAsP. Ce modèle, qui prend également en compte l'influence de la température pour prédire les variations du RIN et du courant de seuil avec celle-ci, a été validé par de nombreuses caractérisations expérimentales. Afin de pouvoir simuler le comportement en bruit d'un laser dans son environnement réel d'utilisation, nous avons élaboré à partir du modèle physique, un modèle électrique original que nous avons implanté dans le logiciel MDS.
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Lupi, Rosita. « Characterization of post translational modification of heterotrimeric G proteins ». Thesis, Open University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343748.
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Della, Corte Giuseppe. « Text and Speech Alignment Methods for Speech Translation Corpora Creation : Augmenting English LibriVox Recordings with Italian Textual Translations ». Thesis, Uppsala universitet, Institutionen för lingvistik och filologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-413064.
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The recent uprise of end-to-end speech translation models requires a new generation of parallel corpora, composed of a large amount of source language speech utterances aligned with their target language textual translations. We hereby show a pipeline and a set of methods to collect hundreds of hours of English audio-book recordings and align them with their Italian textual translations, using exclusively public domain resources gathered semi-automatically from the web. The pipeline consists in three main areas: text collection, bilingual text alignment, and forced alignment. For the text collection task, we show how to automatically find e-book titles in a target language by using machine translation, web information retrieval, and named entity recognition and translation techniques. For the bilingual text alignment task, we investigated three methods: the Gale–Church algorithm in conjunction with a small-size hand-crafted bilingual dictionary, the Gale–Church algorithm in conjunction with a bigger bilingual dictionary automatically inferred through statistical machine translation, and bilingual text alignment by computing the vector similarity of multilingual embeddings of concatenation of consecutive sentences. Our findings seem to indicate that the consecutive-sentence-embeddings similarity computation approach manages to improve the alignment of difficult sentences by indirectly performing sentence re-segmentation. For the forced alignment task, we give a theoretical overview of the preferred method depending on the properties of the text to be aligned with the audio, suggesting and using a TTS-DTW (text-to-speech and dynamic time warping) based approach in our pipeline. The result of our experiments is a publicly available multi-modal corpus composed of about 130 hours of English speech aligned with its Italian textual translation and split in 60561 triplets of English audio, English transcript, and Italian textual translation. We also post-processed the corpus so as to extract 40-MFCCs features from the audio segments and released them as a data-set.
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Musallam, Sam. « Nonlinearity and signal processing in vestibulo-only cells and the translational vestibulo-ocular reflex ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ63768.pdf.
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Sarkissian, Madathia. « Signaling Events Leading to CPEB-Mediated Translation : a Dissertation ». eScholarship@UMMS, 2004. http://escholarship.umassmed.edu/gsbs_diss/305.
Texte intégralRésumé :
Fully grown oocytes' of the African clawed frog, Xenopus laevis, are arrested at the diplotene stage of meiotic prophase I, which resembles the G2 phase of the mitotic cell cycle. Re-entry into the meiotic divisions is initiated by hormonal signaling normally provided by progesterone. Progesterone signaling leads to the activation of maturation promoting factor (MPF), a heterodimer consisting of the protein kinase cdk1 and cyclin B1; this complex promotes the oocyte's entry into M phase of meiosis I. A crucial event required for MPF activation is cytoplasmic polyadenylation element (CPE)-mediated translation of specific dormant mRNAs such as c-mos and cyclin B1. The CPE, which resides in mRNA 3' untranslated region (UTR), is bound by the CPE binding protein (CPEB), which in turn is bound by Maskin. Maskin is bound to the 5' cap binding protein eIF4E. This type of closed-loop mRNA structure inhibits the recruitment and assembly of the translation initiation complex at the 5'UTR of CPE containing mRNAs. To alleviate this inhibition, CPEB undergoes phosphorylation on S174 by the serine/threonine kinase Aurora A. Phosphorylated CPEB promotes the recruitment of specific polyadenylation factors leading to the polyadenylation of the dormant mRNA, resulting in the disassociation of Maskin from eIF4E. eIF4E is subsequently bound by translation initiation factors leading to mRNA assembly into polysomes and synthesis of the encoded protein.
Insulin signaling has also been shown to induce oocyte maturation. However, this signaling cascade uniquely requires the activation of two upstream components, PI3 kinase and PKC zeta. In this thesis, I show that insulin induced oocyte maturation requires the same CPE-mediated mRNA translation mechanism as had been described for progesterone signaling. I also show that Aurora A kinase activation and S174 phosphorylation play an essential role in insulin-induced CPE-mediated mRNA translation. Interestingly, inhibition of PI3 kinase and PKC zeta inhibits CPE-mediated polyadenylation only in the insulin-signaling pathway; the progesterone pathway is unaffected. These results clearly indicate that different upstream signaling components control CPE-mediated translation between progesterone and insulin signaling cascades. However, both pathways are antagonized by over expressed GSK-3, leading to inhibition of oocyte maturation. Furthermore, I found that GSK-3 inhibits Aurora A kinase activity by directly phosphorylating Aurora A on serine 290/291, promoting an inhibitory autophosphorylation event on serine 349. The importance of a GSK-3/Aurora A interaction is underscored by the finding that GSK-3, Axin, and Aurora A reside in a complex in immature oocytes. During progesterone or insulin signaling, GSK-3 dissociates from Aurora A allowing Aurora A to become active, leading to CPEB phosphorylation, CPE-mediated mRNA translation and oocyte maturation.
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Flores, Janine Kate. « Characterisation of the human signal recognition particle protein component, SRP68/72, and its role in co-translational translocation ». Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18698.
Texte intégralRésumé :
One of the most fundamental processes within the cell is ensuring that translated proteins are compartmentalised to their appropriate cellular location. To ensure that this process occurs efficiently, the cell employs several pathways to transport each protein to their designated area. There are two main systems for protein transport, which occur during (co-translational) or after (post-translational) the process of translation. These protein transport systems are well characterised; however, the complexes that mediate these pathways are not well understood. In this project, we are interested in the human ribonucleoprotein complex involved in co-translational translocation known as the signal recognition particle (SRP), which facilitates transport of nascent proteins destined for the endoplasmic reticulum (ER) from the cytosol. To achieve this, the SRP has two functional domains that are involved in either elongation arrest (Alu domain) or the recognition of the signal sequence/ER targeting (S domain). In this thesis, the aim was to understand the structure and function of the heterodimer known as SRP68/72, which are two of the four proteins that form the S domain, along with half of the SRP RNA. The first aim was to understand its role in the complex by determining its structure. To achieve this, the components of the S domain were expressed, purified, and reconstituted in vitro with purified SRP RNA for crystallisation trials. To elucidate the function of this domain as well as its assembly, the RNA: protein interactions of the SRP proteins and RNA were explored using RNA electrophoretic mobility shift assays, microscale thermophoresis, and site-directed mutagenesis. Overall, these results have provided an insight into the binding mechanisms of the complex, which suggest that the SRP proteins rely on the SRP RNA’s structure to bind.
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Pasdeloup, Bastien. « Extending convolutional neural networks to irregular domains through graph inference ». Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0048/document.
Texte intégralRésumé :
Tout d'abord, nous présentons des méthodes permettant d'inférer un graphe à partir de signaux, afin de modéliser le support des données à classifier. Ensuite, des translations préservant les voisinages des sommets sont identifiées sur le graphe inféré. Enfin, ces translations sont utilisées pour déplacer un noyau convolutif sur le graphe, afin dedéfinir un réseau de neurones convolutif adapté aux données d'entrée.Nous avons illustré notre méthodologie sur une base de données d'images. Sans utiliser de connaissances sur les signaux, nous avons pu inférer un graphe proche d'une grille. Les translations sur ce graphe sont proches des translations Euclidiennes, ce qui nous a permis de définir un réseau de neurones convolutif très similaire à ce que l'on aurait pu obtenir en utilisant l'information que les signaux sont des images. Ce réseau, entraîné sur les données initiales, a dépassé lesperformances des méthodes de l'état de l'art de plus de 13 points, tout en étant simple et facilement améliorable.La méthode que nous avons introduite est une généralisation des réseaux de neurones convolutifs, car ceux-ci sont des cas particuliers de notre approche quand le graphe est une grille. Nos travaux ouvrent donc de nombreuses perspectives, car ils fournissent une méthode efficace pour construire des réseaux adaptés aux donnéesThis manuscript sums up our work on extending convolutional neuralnetworks to irregular domains through graph inference. It consists of three main chapters, each giving the details of a part of a methodology allowing the definition of such networks to process signals evolving on graphs with unknown structures.First, graph inference from data is explored, in order to provide a graph modeling the support of the signals to classify. Second, translation operators that preserve neighborhood properties of the vertices are identified on the inferred graph. Third, these translations are used to shift a convolutional kernel on the graph in order to define a convolutional neural network that is adapted to the input data.We have illustrated our methodology on a dataset of images. While not using any particular knowledge on the signals, we have been able to infer a graph that is close to a grid. Translations on this graph resemble Euclidean translations. Therefore, this has allowed us to define an adapted convolutional neural network that is very close what one would obtain when using the information that signals are images. This network, trained on the initial data, has out performed state of the art methods by more than 13 points, while using a very simple and easily improvable architecture.The method we have introduced is a generalization of convolutional neural networks. As a matter of fact, they can be seen as aparticularization of our approach in the case where the graph is a grid. Our work thus opens the way to numerous perspectives, as it provides an efficient way to build networks that are adapted to the data
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Tang, Xiaofang. « Regulation of Wingless secretion, distribution and signaling ». University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1353100929.
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Chen, Li. « TAK1-Mediated Post-Translational Modifications Modulate Immune Response : A Dissertation ». eScholarship@UMMS, 2015. https://escholarship.umassmed.edu/gsbs_diss/786.
Texte intégralRésumé :
Innate immunity is the first line of defense against invading pathogens. It provides immediate protection by initiating both cellular and humoral immune reactions in response to a wide range of infections. It is also important to the development of long-lasting and pathogen-specific adaptive immunity. Thus, studying of the innate immunity, especially the pathogen recognition and signaling modulation, is crucial for understanding the intrinsic mechanisms underlying the host defense, as well as contributing the development of the fight against infectious diseases. Drosophila is an ideal model organism for study of innate immunity. Comparing to mammals, Drosophila immunity is relative conserved and less redundant. A variety of molecular and genetic tools available add further convenience to the research in this system. My work is focused on the signaling modulation by post-translational modification after activation. In these studies I demonstrated in the center of Imd pathway, the Imd protein undergoes proteolytic cleavage, K63-polyubiquitination, phosphorylation, K63-deubiquitination and K48-polyubiquitination/degradation in a stimulation-dependent manner. These modifications of Imd play a crucial role in regulating signaling in response to infection. The characterization of ubiquitin-editing event provides a new insight into the molecular mechanisms underlying the activation and termination of insect immune signaling pathway.
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Chen, Li. « TAK1-Mediated Post-Translational Modifications Modulate Immune Response : A Dissertation ». eScholarship@UMMS, 2005. http://escholarship.umassmed.edu/gsbs_diss/786.
Texte intégralRésumé :
Innate immunity is the first line of defense against invading pathogens. It provides immediate protection by initiating both cellular and humoral immune reactions in response to a wide range of infections. It is also important to the development of long-lasting and pathogen-specific adaptive immunity. Thus, studying of the innate immunity, especially the pathogen recognition and signaling modulation, is crucial for understanding the intrinsic mechanisms underlying the host defense, as well as contributing the development of the fight against infectious diseases. Drosophila is an ideal model organism for study of innate immunity. Comparing to mammals, Drosophila immunity is relative conserved and less redundant. A variety of molecular and genetic tools available add further convenience to the research in this system. My work is focused on the signaling modulation by post-translational modification after activation. In these studies I demonstrated in the center of Imd pathway, the Imd protein undergoes proteolytic cleavage, K63-polyubiquitination, phosphorylation, K63-deubiquitination and K48-polyubiquitination/degradation in a stimulation-dependent manner. These modifications of Imd play a crucial role in regulating signaling in response to infection. The characterization of ubiquitin-editing event provides a new insight into the molecular mechanisms underlying the activation and termination of insect immune signaling pathway.
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Cortes, Fernando da Rocha Paixao. « Analysis, design and implementation of analog/RF blocks suitable for a multi-band analog interface for CMOS SOCs ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/13132.
Texte intégralRésumé :
O desenvolvimento de tecnologias de integração para circuitos integrados junto com a demanda de cada vez mais processamento digital de sinais, como em sistemas de telecomunicações e aplicações SOC, resultaram na crescente necessidade de circuitos mistos em tecnologia CMOS integrados em um único chip. Em um trabalho anterior, a arquitetura de uma interface analógica para ser usada em aplicações SOC mistas foi desenvolvida e implementada. Basicamente esta interface é composta por uma célula analógica fixa (fixed analog cell – FAC), que translada o sinal de entrada para uma freqüência de processamento fixa, e por um bloco digital que processa este sinal. Primeiramente, as especificações de sistema foram determinadas considerando o processamento de sinais de três bandas de freqüência diferentes: FM, vídeo e celular, seguido por simulações de alto-nível do sistema da FAC. Então, uma arquitetura heteródina integrada CMOS para o front-end que integrará a FAC, composto por 2 mixers ativos e um amplificador de ganho variável, foi apresentada, enumerando-se e propondo-se soluções para os desafios de projeto e metodologia. Os blocos analógicos/RF, juntamente com o front-end, foram projetados e implementados em tecnologia CMOS IBM 0.18μm, apresentando-se simulações e medidas de um protótipo físico.The development of IC technologies coupled with the demand for more digital signal processing integrated in a single chip has created an increasing need for design of mixed-signal systems in CMOS technology. Previously, a general analog interface architecture targeted to mixed-signal systems on-chip applications was developed and implemented, which is composed by a fixed analog cell (FAC), that translates the input signal to a processing frequency, and a digital block, that processes the signal. The focus of this thesis is to analyze, design and implement analog/RF building blocks suitable for this system. First, a set of system specifications is developed and verified through system level simulations for the FAC system, aiming the signal processing of three target applications: FM, video and digital cellular frequency bands. Then, a fully CMOS integrated dual-conversion heterodyne front-end architecture with 2 active mixers and a variable-gain amplifier is presented, enumerating and proposing solutions for the design challenges and methodology. The stand-alone building blocks and the front-end system are designed and implemented in IBM 0.18μm CMOS process, presenting simulations and experimental data from an actual physical prototype.
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Li, Yiming. « Ryanodine receptors in calcium signaling pathways ». Scholarly Commons, 2008. https://scholarlycommons.pacific.edu/uop_etds/710.
Texte intégralRésumé :
Calcium (Ca2+) plays an important role as a second messenger, transmitting the message of arrival of stimuli such as hormones and neurotransmitters to the intracellular system that carries out the cellular response to the stimulus. The universality of Ca2+ as an intracellular messenger depends on its enormous versatility. This versatility is exploited to control processes as diverse as fertilization, proliferation, development, learning and memory, contraction and secretion, and must be accomplished within the context of Ca2+ being highly toxic.
Ryanodine receptors (RyRs) and inositol trisphosphate receptors (IP3Rs) are Ca2+ -release channels located on intracellular membranes of the endoplasmic reticulum (ER)/sarcoplasmic reticulum (SR) that perform essential functions as key targets of hormone/neurotransmitter action to initiate intracellular Ca2+ signals. The purpose of this project was to study the role of RyR2 in Ca2+ signaling in the NG115-401L neuronal cell line. siRNA transfection methods were employed to knockdown RyR2 expression levels in NG115-401L cells. We used reverse transcription and real-time PCR to evaluate RyR2 gene expression in transfected/untransfected cells. We also evaluated cytosolic Ca2+ changes induced by RyR activators or regulators, using fura-2 AM as the Ca2+ indicator. Successful RyR2 gene knockdown allowed us to carry out some initial experiments to characterize the specific roles played by the RyR2 receptor isoform. We examined cell responses to FK-506 under the condition of RyR2 knockdown, finding that RyR2 appears to confer selectivity to this response. Finally, the effects of siRNA transfection and FK-506 treatment on NG115-401L cell growth were evaluated. These experimental results may contribute to future studies of RyR2, and help develop novel treatments for RyR2-base d dysfunctional diseases.
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Roulston, Claire. « Occurrence & ; function of cellular 2A sequences ». Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/7062.
Texte intégralRésumé :
This thesis describes experiments investigating the translational recoding activities and the novel dual signalling properties of eukaryotic ribosome skipping 2A sequences. Over twenty years ago, the 19 amino acid 2A region of a Picornavirus; namely, Foot-and-Mouth Disease Virus (FMDV) polypeptide was shown to possess apparent “self-cleaving” abilities, cutting at its own C-terminus during translation (Ryan et al., 1991). Active FMDV 2A-like sequences were subsequently found in a number of related viruses (Luke et al., 2008), with several now utilised as essential biotechnology multi-gene transfer tools (Luke et al., 2010b). Then, in 2006, eukaryotic 2A-like sequences were identified from trypanosome non-LTR sequences. These were found to be functional in vitro (Heras et al., 2006). I have been able to identify over 400 putative eukaryotic 2A-like sequences through searching the freely available online proteomic and genomic databases. Data is presented to show that these 2As were encoded in frame with non-LTRs, or metabolic, or immune function genes, from a wide range of eukaryotic organisms; but I could not discern any obvious phylogenetic distribution for 2A. I have discovered that the majority of eukaryotic 2A sequences tested can mediate ribosome skipping in vitro. Modelling in silico indicated that active 2A-like sequences possessed the propensity to form a central alpha-helical region, whereas the models suggested that inactive 2A-like sequences would be essentially unstructured. I also report that some of these eukaryotic 2A peptides constitute a novel form of dual protein targeting as they play a dual role as exocytic pathway signal peptides mediating extracellular protein trafficking. I have shown that this protein trafficking ability is evolutionarily conserved, with an echinoderm sequence able to direct protein targeting in both plant and mammalian cells. I therefore propose that these novel eukaryotic 2A sequences could potentially become extremely valuable in biotechnological engineering.
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Ahmed, A. « Signal separation ». Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595390.
Texte intégralRésumé :
The problem of signal separation is a very broad and fundamental one. A powerful paradigm within which signal separation can be achieved is the assumption that the signals/sources are statistically independent of one another. This is known as Independent Component Analysis , (ICA). In this thesis, the theoretical aspects and derivation of ICA are examined, from which disparate approaches to signal separation are drawn together in a unifying framework. This is followed by a review of signal separation techniques based on ICA. Second order statistics based output decorrelation methods are employed to try to solve the challenging problem of separating convolutively mixed signals, in the context of mainly audio source separation and the Cocktail Party Problem. Various optimisation techniques are devised to implement second order signal separation of both artificially mixed signals and real mixtures. A study of the advantages and limitations of decorrelation methods is made and some theoretical insights are drawn into a major identifiability problem associated with convolutive source separation using second order statistics only. Motivated by the fact that many signals in real life, especially audio signals, exhibit large degrees of non-stationarity, decorrelation algorithms that take into consideration aspects of non-stationarity are devised. Next, a model based approach to source separation is considered. The problem of non-stationary ICA (nsICA) is addressed, where the mixing system is scalar but time-varying. The density of the sources are modelled as finite mixtures of Gaussians. Simulation based Bayesian methods, notably Markov Chain Monte Carlo (MCMC) techniques, are employed to separate both synthetic and real data that have been mixed by non-stationary mixing matrices. Satisfactory results have been obtained with very few data points, using batch methods, such as Gibbs sampling. The techniques of Sequential Monte Carlo (SMC) methods, or particle filtering, are employed to this problem as well, in the context of both blind and semi-blind signal separation, which involve tracking the time varying mixing system.
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Rosskopf, John J. « CIS-acting signals for replication of Nodamura virus RNA1 ». To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Englehart, Kevin. « Signal representation for classification of the transient myoelectric signal ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0016/NQ46463.pdf.
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Englehart, K. « Signal representation for classification of the transient myoelectric signal ». Thesis, University of New Brunswick, 1998. http://hdl.handle.net/1882/808.
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Neuman, Bartosz P. « Signal processing in diffusion MRI : high quality signal reconstruction ». Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/27691/.
Texte intégralRésumé :
Magnetic Resonance Imaging (MRI) is a medical imaging technique which is especially sensitive to different soft tissues, producing a good contrast between them. It allows for in vivo visualisation of internal structures in detail and became an indispensable tool in diagnosing and monitoring the brain related diseases and pathologies. Amongst others, MRI can be used to measure random incoherent motion of water molecules, which in turn allows to infer structural information. One of the main challenges in processing and analysing four dimensional diffusion MRI images is low signal quality. To improve the signal quality, either denoising algorithm or angular and spatial regularisations are utilised. Regularisation method based on Laplace--Beltrami smoothing operator was successfully applied to diffusion signal. In this thesis, a new regularisation strength selection scheme for diffusion signal regularisation is introduced. A mathematical model of diffusion signal is used in Monte--Carlo simulations, and a regularisation strength that optimally reconstructs the diffusion signal is sought. The regularisation values found in this research show a different trend than the currently used L-curve analysis, and further improve reconstruction accuracy. Additionally, as an alternative to regularisation methods a backward elimination regression for spherical harmonics is proposed. Instead of using the regularisation term as a low-pass filter, the statistical t-test is classifying regression terms into reliable and corrupted. Four algorithms that use this information are further introduced. As the result, a selective filtering is constructed that retains the angular sharpness of the signal, while at the same time reducing corruptive effect of measurement noise. Finally, a statistical approach for estimating diffusion signal is investigated. Based on the physical properties of water diffusion a prior knowledge for the diffusion signal is constructed. The spherical harmonic transform is then formulated as a Bayesian regression problem. Diffusion signal reconstructed with the addition of such prior knowledge is accurate, noise resilient, and of high quality.
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Liljekvist, Erika, et Oscar Hedlund. « Uncovering Signal : Simplifying Forensic Investigations of the Signal Application ». Thesis, Högskolan i Halmstad, Akademin för informationsteknologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-44835.
Texte intégralRésumé :
The increasing availability of easy-to-use end-to-end encrypted messaging applications has made it possible for more people to conduct their conversations privately. This is something that criminals have taken advantage of and it has proven to make digital forensic investigations more difficult as methods of decrypting the data are needed. In this thesis, data from iOS and Windows devices is extracted and analysed, with focus on the application Signal. Even though other operating systems are compatible with the Signal application, such as Android, it is outside the scope of this thesis. The results of this thesis provide access to data stored in the encrypted application Signalwithout the need for expensive analysis tools. This is done by developing and publishing the first open-source script for decryption and parsing of the Signal database. The script is available for anyone at https://github.com/decryptSignal/decryptSignal.
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Lönn, Peter. « Regulation of TGF-β Signaling by Post-Translational Modifications ». Doctoral thesis, Uppsala universitet, Ludwiginstitutet för cancerforskning, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-128855.
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Transforming growth factor-β (TGF-β) signaling is initiated when the ligand binds to type II and type I serine/threonine kinase receptors at the cell surface. Activated TGF-β type I receptors phosphorylate R-Smads which relocate, together with co-Smads, to the cell nucleus and regulate transcription. Enhancement or repression of Smad-specific gene targets leads to intracellular protein compositions which organize functional complexes and thus govern cellular processes such as proliferation, migration and differentiation. TGF-β/Smad signaling relays are regulated by various post-translational modifications. From receptors to gene promoters, intricate interplays between phosphorylation, acetylation, ubiquitination and numerous other modifications, control Smad signaling initiation and duration. However, many steps in the cascade, including receptor internalization, Smad nuclear shuttling and transcriptional termination, still remain elusive. The open gaps in our understanding of these mechanisms most likely involve additional post-translational regulations. Thus, the aim of the present investigation was to identify novel modulators of TGF-β/Smad signaling. In the first part of this thesis, we show the importance of ADP-ribosylation in Smad-mediated transcription. We identified poly(ADP-ribose) polymerase 1 (PARP-1) as a Smad interacting protein. Our work revealed that PARP-1 forms direct interactions with Smad3/4, and PARylates residues in their MH1 domains. This modification restricts Smads from binding to DNA and attenuates Smad-activated transcription. PARylation is reversed by the glycohydrolase PARG. We provide evidence that PARG can de-ADP-ribosylate Smads, which enhances Smad-promoted gene regulation. In the second part, we examine a Smad-dependent gene target of TGF-β signaling, salt inducible kinase 1 (SIK). After induction, SIK cooperates with Smad7 and Smurf2 to downregulate the TGF-β type I receptor. The mechanism relies on both the kinase and UBA domain of SIK as well as the E3-ligase activity of Smurf2. In summary, we have unveiled two enzyme-dependent TGF-β/Smad modulatory mechanisms; SIK promoted receptor turnover and PARP-1/PARG-regulated Smad signaling.
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Friberg, Markus. « Algorithms for analyzing signals in DNA : applications to transcription and translation / ». Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17096.
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Shariat-Yazdi, Ramin. « Mixed signal design flow a mixed signal PLL case study / ». Waterloo, Ont. : University of Waterloo, [Dept. of Electrical and Computer Engineering], 2001. http://etd.uwaterloo.ca/etd/rshariatyazdi2001.pdf.
Texte intégralRésumé :
Thesis (M.A.Sc.) - University of Waterloo, 2001."A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Master of Applied Science in Electrical and Computer Engineering". Includes bibliographical references.
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Figueroa, Toro Miguel E. « Adaptive signal processing and correlational learning in mixed-signal VLSI / ». Thesis, Connect to this title online ; UW restricted, 2005. http://hdl.handle.net/1773/6856.
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Shariat, Yazdi Ramin. « Mixed signal design flow, a mixed signal PLL case study ». Thesis, University of Waterloo, 2001. http://hdl.handle.net/10012/916.
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Mixed-signal designs are becoming more and more complex every day. In order to adapt to the new market requirements, a formal process for design and verification of mixed signal systems i. e. top-down design and bottom-up verification methodology is required. This methodology has already been established for digital design. The goal of this research is to propose a new design methodology for mixed signal systems. In the first two chapters of this thesis, the need for a mixed signal design flow based on top-down design methodology will be discussed. The proposed design flow is based on behavioral modeling of the mixed signal system using one of the mixed signal behavioral modeling languages. These models can be used for design and verification through different steps of the design from system level modeling to final physical design. The other advantage of the proposed flow is analog and digital co-design. In the remaining chapters of this thesis, the proposed design flow was verified by designing an 800 MHz mixed signal PLL. The PLL uses a charge pump phase frequency detector, a single capacitor loop filter, and a feed forward error correction architecture using an active damping control circuit instead of passive resistor in loop filter. The design was done in 0. 18- µ m CMOS process technology.
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李潔安 et Kit-on Niko Li. « Comprehensive restoration plan for Signal Tower at Signal Hill, Tsimshatsui ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B42181549.
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Chen, Cheng. « Simultaneous transmission of baseband signal and in band RF signal ». Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708805.
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Hoppe, Elizabeth A. « Improving Signal Clarity through Interference Suppression and Emergent Signal Detection ». Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/39325.
Texte intégralRésumé :
Microphone arrays have seen wide usage in a variety of fields; especially in sonar, acoustic source monitoring and localization, telecommunications, and diagnostic medicine.
The goal of most of these applications is to detect or extract a signal of interest. This task is complicated by the presence of interferers and noise, which corrupts the recorded array signals. This dissertation explores two new techniques that increase signal clarity: interferer suppression and emergent signal detection.
Spatial processing is often used to suppress interferers that are spatially distinct from the signal of interest. If the signal of interest and the interferer are statistically independent, blind source separation can be used to statistically extract the signal of interest. The first new method to improve signal clarity presented in this work combines spatial processing with blind source separation to suppress interferers. This technique allows for the separation of independent sources that are not necessarily simultaneously mixed or spatially distinct. Simulations and experiments are used to show the capability of the new algorithm for a variety of conditions. The major contributions in this dissertation under this topic are to use independent component analysis to extract the signal of interest from a set of array signals, and to improve existing independent component analysis algorithms to allow for time delayed mixing.
This dissertation presents a novel method of improving signal clarity through emergent signal detection. By determining which time frames contain the signal of interest, frames that contain only interferers and noise can be eliminated. When a new signal of interest emerges in a measurement of a mixed set of sources, the principal component subspace is altered. By examining the change in the subspace, the emergent signal can be robustly detected. This technique is highly effective for signals that have a near constant sample variance, but is successful at detecting a wide variety of signals, including voice signals. To improve performance, the algorithm uses a feed-forward processing technique. This is helpful for the VAD application because voice does not have a constant sample variance. Experiments and simulations are used to demonstrate the performance of the new technique.Ph. D.
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Wang, Limin. « The ECG signal processing by ADSP-21062 digital signal processor ». Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=840.
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Thesis (M.S.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains vi, 110 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 66-68).
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Li, Kit-on Niko. « Comprehensive restoration plan for Signal Tower at Signal Hill, Tsimshatsui ». Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B42181549.
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Howell, Brian. « Signal transducing molecules ». Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39347.
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The involvement of protein phosphorylation and gene regulation in signal transduction pathways are examined. In particular the role of the novel STY kinase in signal transduction networks is suggested, followed by a study of the liver-specific and inducible expression of the carbamyl phosphate synthetase I (CPSI) gene. In a screen of an embryonal carcinoma (EC) cell cDNA expression library with an antibody to phosphotyrosine, the STY kinase was identified. STY is represented by a single 1.8 kb transcript in undifferentiated P19 cells. During differentiation of these cells, mRNAs of 3.2 and 5.6 are induced and persist to adulthood. Sequence analysis of the STY kinase revealed a catalytic domain homologous to kinases with serine/threonine phosphorylating specificity especially those involved in cell-cycle control, such as the FUS3 gene. Biochemical analysis of recombinant STY synthesized in bacteria or in vitro indicated a serine-, threonine-, and tyrosine-phosphorylating capability, suggesting that it belongs to a previously unappreciated family of kinases.The promoter region of the liver specific, glucocorticoid and cAMP inducible gene, CPSI was analyzed for transcriptional activity. Sequences extending from the in vivo start site of CPSI gene to $-$1200 bp, were shown to support in vitro transcription with liver nuclear extracts. A region proximal to transcription initiation, from $-$104 to $-$124 was shown to specifically interact with the abundant liver nuclear factor C/EBP. Double stranded oligonucleotides corresponding this cis element abolishes in vitro transcription reactions in a competitive manner. The C/EBP and related factors, LAP and LIP, interaction with CPSI promoter elements has implications in the developmental, liver-specific, as well as the inducible aspects of CPSI gene expression.
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Mishin, A. « Biomagnetic signal analysis ». Thesis, Swansea University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638202.
Texte intégralRésumé :
Most of this thesis is an account of the effort to develop new methods for biomagnetic data analysis. Variations of the heart rate reflect the neural heart control mechanisms which are performed via the electrical modulation of the sinoatrial node by the autonomic nervous system. This modulation involves the interaction of several physiological mechanisms that operate on differing time scales. Using SQUID (superconducting quantum interference device) instrumentation, the fetal cardiogram can be measured with great accuracy and a high temporal resolution, thereby providing the opportunity to assess the neural function in the fetus non-invasively by analysing heart rate variability (HRV). However, a quantitative analysis of HRV requires several other physiological parameters such as blood pressure, respiration etc. to be analysed simultaneously with HRV. These parameters are obviously inaccessible in the fetus although they are routinely recorded in premature neonates treated in the intensive care units. Using a time domain correlation method, the behaviour of different HRV components was quantitatively studied for both fetuses and premature neonates and a number of consistent features were found. The correlation between neonatal HRV, respiration and arterial blood pressure was studied with the ultimate goal of constructing a numerical model of HRV. It was also observed that different types of ventilation equipment used in neonatal intensive care cause different patterns of respiration/HRV correlation, which may be indicative of the efficacy of the ventilator. Investigation of the spontaneous activity of the human brain and in particular alpha rhythm is another area where SQUID-based biomagnetic techniques can make an important contribution. In the final chapter of this work the multichannel alpha magnetoencephalogram (MEG) is considered as a sequences of MEG maps. A neural-net based algorithm for segmentation of MEG records into words is presented. Using this method three recurring words were found in an eight-second magnetoecephalogram. This could be of value for active testing of the functional role of the cortex in neurological experiments.
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Chan, D. C. B. « Blind signal separation ». Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597415.
Texte intégralRésumé :
The separation of independent sources from mixed observed data is a fundamental and challenging signal processing problem. In many practical situations, one or more desired signals need to be recovered from the mixtures only. A typical example is speech recordings made in an acoustic environment in the presence of background noise and/or competing speakers. Other examples include EEG signals, passive sonar applications and cross-talk in data communications. The audio signal separation problem is sometimes referred to as The Cocktail Party Problem. When several people in the same room are conversing at the same time, it is remarkable that a person is able to choose to concentrate on one of the speakers and listen to his or her speech flow unimpeded. This ability, usually referred to as the binaural cocktail party effect, results in part from binaural (two-eared) hearing. In contrast, a person with a severe hearing loss in one ear finds it is difficult to focus on a particular speaker under the same circumstances. A signal separation pre-process would be desirable in such circumstances. Signal separation techniques can also be applied in many other areas such as noise reduction, speech recognition and multi-media applications. The term 'Blind Signal Separation' refers to the lack of any propagation model: only statistical independence of the sources is assumed. The lack of other prior information underlines the difficulty of the problem. Observations may be modelled as linear mixtures of a number of source signals, i.e. a linear multi-input multi-output system. In this dissertation, the general n-source n-sensor (n x n) linear time invariant wide-band system is studied, in which, n random signals are received at n sensors and these signals originated from n sources. The problem is to recover the sources from observed signals only. Various block-based iterative algorithms are proposed which use output decorrelation as a signal separation criterion. These algorithms search for a linear transformation that minimises the statistical correlation between the components. Some existing solutions are reviewed and compared.
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Lee, Li 1975. « Distributed signal processing ». Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/86436.
Texte intégral
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Eldar, Yonina Chana 1973. « Quantum signal processing ». Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/16805.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2002.Includes bibliographical references (p. 337-346).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Quantum signal processing (QSP) as formulated in this thesis, borrows from the formalism and principles of quantum mechanics and some of its interesting axioms and constraints, leading to a novel paradigm for signal processing with applications in areas ranging from frame theory, quantization and sampling methods to detection, parameter estimation, covariance shaping and multiuser wireless communication systems. The QSP framework is aimed at developing new or modifying existing signal processing algorithms by drawing a parallel between quantum mechanical measurements and signal processing algorithms, and by exploiting the rich mathematical structure of quantum mechanics, but not requiring a physical implementation based on quantum mechanics. This framework provides a unifying conceptual structure for a variety of traditional processing techniques, and a precise mathematical setting for developing generalizations and extensions of algorithms. Emulating the probabilistic nature of quantum mechanics in the QSP framework gives rise to probabilistic and randomized algorithms. As an example we introduce a probabilistic quantizer and derive its statistical properties. Exploiting the concept of generalized quantum measurements we develop frame-theoretical analogues of various quantum-mechanical concepts and results, as well as new classes of frames including oblique frame expansions, that are then applied to the development of a general framework for sampling in arbitrary spaces. Building upon the problem of optimal quantum measurement design, we develop and discuss applications of optimal methods that construct a set of vectors.
(cont.) We demonstrate that, even for problems without inherent inner product constraints, imposing such constraints in combination with least-squares inner product shaping leads to interesting processing techniques that often exhibit improved performance over traditional methods. In particular, we formulate a new viewpoint toward matched filter detection that leads to the notion of minimum mean-squared error covariance shaping. Using this concept we develop an effective linear estimator for the unknown parameters in a linear model, referred to as the covariance shaping least-squares estimator. Applying this estimator to a multiuser wireless setting, we derive an efficient covariance shaping multiuser receiver for suppressing interference in multiuser communication systems.
by Yonina Chana Eldar.
Ph.D.
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Valero, Daniel. « Wireless Signal Conditioning ». Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc862776/.
Texte intégralRésumé :
This thesis presents a new approach to extend and reduce the transmission range in wireless systems. Conditioning is defined as purposeful electromagnetic interference that affects a wireless signal as it propagates through the air. This interference can be used constructively to enhance a signal and increase its energy, or destructively to reduce energy. The constraints and limitations of the technology are described as a system model, and a flow chart is used to describe the circuit process. Remaining theoretical in nature, practical circuit implementations are foregone in the interest of elementary simulations depicting the interactions of modulated signals as they experience phase mismatch. Amplitude modulation and frequency modulation are explored with using both positive and negative conditioning, and conclusions to whether one is more suitable than the other are made.
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Burke, Christine. « From the signal ». Thesis, University of Iowa, 2017. https://ir.uiowa.edu/etd/5432.
Texte intégralRésumé :
from the signal is a piece for two simultaneously existing trios, where Trio 1 is comprised of clarinet, trumpet and percussion, and Trio 2 of violin, viola and violoncello. I use open form, indeterminacy, and non standard methods of notation to neutralize narrative form, creating instead a static world where sounds interact without implying purpose or direction.
The ideas of identity and concealment are central to from the signal, as each trio embodies a set of timbral characteristics that are respectively unique but exposed in different ways. Trio 1’s direct, strident material is an orchestrated amplification/extension of the slow progression of an EBow down the string of an acoustic guitar (played by the percussionist), while Trio 2’s softer sounds explore notions of space and closeness as they relate to pitch. The title refers to the roles of the percussionist and violinist, as they are responsible for leading and pacing their respective trios throughout the piece.
This piece may raise questions about power dynamics, relationships and balance, but is in no way an attempt to make a conclusion about these things. My intent is rather to create a musical situation where listeners are invited to consider the ramifications of such juxtaposition for themselves (drawing their own conclusions, or not). from the signal was written for the Chicago Civic Orchestra Composers Project, and will be premiered on May 28th, 2017.
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Manmontri, Uttachai. « A gradient-based approach to unsupervised signal separation using signal properties ». Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442068.
Texte intégral
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Lei, Chi-un, et 李志遠. « VLSI macromodeling and signal integrity analysis via digital signal processing techniques ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B45700588.
Texte intégral
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Clewell, Matthew John. « Reducing signal coupling and crosstalk in monolithic, mixed-signal integrated circuits ». Thesis, Kansas State University, 2013. http://hdl.handle.net/2097/18138.
Texte intégralRésumé :
Master of ScienceDepartment of Electrical Engineering
William B. Kuhn
Designers of mixed-signal systems must understand coupling mechanisms at the system, PC board, package and integrated circuit levels to control crosstalk, and thereby minimize degradation of system performance. This research examines coupling mechanisms in a RF-targeted high-resistivity partially-depleted Silicon-on-Insulator (SOI) IC process and applying similar coupling mitigation strategies from higher levels of design, proposes techniques to reduce coupling between sub-circuits on-chip. A series of test structures was fabricated with the goal of understanding and reducing the electric and magnetic field coupling at frequencies up to C-Band. Electric field coupling through the active-layer and substrate of the SOI wafer is compared for a variety of isolation methods including use of deep-trench surrounds, blocking channel-stopper implant, blocking metal-fill layers and using substrate contact guard-rings. Magnetic coupling is examined for on-chip inductors utilizing counter-winding techniques, using metal shields above noisy circuits, and through the relationship between separation and the coupling coefficient. Finally, coupling between bond pads employing the most effective electric field isolation strategies is examined. Lumped element circuit models are developed to show how different coupling mitigation strategies perform. Major conclusions relative to substrate coupling are 1) substrates with resistivity 1 kΩ·cm or greater act largely as a high-K insulators at sufficiently high frequency, 2) compared to capacitive coupling paths through the substrate, coupling through metal-fill has little effect and 3) the use of substrate contact guard-rings in multi-ground domain designs can result in significant coupling between domains if proper isolation strategies such as the use of deep-trench surrounds are not employed. The electric field coupling, in general, is strongly dependent on the impedance of the active-layer and frequency, with isolation exceeding 80 dB below 100 MHz and relatively high coupling values of 40 dB or more at upper S-band frequencies, depending on the geometries and mitigation strategy used. Magnetic coupling was found to be a strong function of circuit separation and the height of metal shields above the circuits. Finally, bond pads utilizing substrate contact guard-rings resulted in the highest degree of isolation and the lowest pad load capacitance of the methods tested.