Дисертації з теми "Perturbante"

Questa ricerca parte dall’analisi del concetto di Unheimlich con lo scopo di fare emergere il peculiare legame tra la figura del mostro e il sentimento perturbante, utilizzando tale base teorica come chiave interpretativa per alcune opere di arte contemporanea a soggetto mostruoso. Il lavoro si apre con l’indagine linguistica della parola Unheimlich e l’analisi dei testi di E. Jentsch Sulla psicologia dell’Unheimlich, primo saggio dedicato al perturbante, e di S. Freud Il perturbante, più importante trattazione sull’argomento, segue lo studio della teoria di M. Mori, l’Uncanny Valley. Ciò che si intende affermare è che il perturbante è un concetto sempre attuale, che può emergere all’interno negli ambiti più disparati ogni volta che i confini tra ciò che è familiare e ciò che è estraneo vacillano. Successivamente si definisce cos’è un mostro e si evidenzia come l’incontro con esso metta in gioco il limite tra identità e alterità, talvolta oltrepassandolo e come nel cogliere qualcosa di familiare in una creatura spaventosa si scateni l’effetto perturbante. Infine, si vuole affermare che il concetto di Unheimlich può rivelarsi una categoria interpretativa utile per comprendere alcune opere d’arte che coinvolgono e spaventano allo stesso tempo. Vengono presi in considerazione alcuni casi: la mostra The Uncanny ideata dall’artista Mike Kelley, le opere dell’artista Ron Mueck, come esempio di mostro umano; le opere dell’artista Patricia Piccinini per il mostro animale; le opere dell’artista Mariko Mori, per il mostro tecnologico.

2010/2011
L’areale marino costiero del Friuli Venezia Giulia, posto nel settore più orientale del Nord Adriatico, è conosciuto come uno degli ecosistemi maggiormente contaminati dal mercurio (Hg), metallo pesante il cui notevole interesse è legato alla spiccata neuro-tossicità della sua forma organica, il metilmercurio (MeHg), e alle sue proprietà di bioaccumulo e biomagnificazione lungo l’intera catena trofica fino all’uomo (Fitzgerald & Clarkson, 1991; Clarkson, 1999). La fonte principale di Hg è dovuta agli apporti di materiale particellato veicolati nel Golfo di Trieste dal Fiume Isonzo. Quest’ultimo riceve nel suo percorso il risultato del dilavamento cui sono soggetti i terreni e le sponde fluviali dell’area di Idrjia (Slovenia occidentale) da parte di un suo affluente, il torrente Idrijca. In questo sito, per un periodo di circa 500 anni, è stata condotta una intensa attività estrattiva che si è protratta fino alla definitiva chiusura dell’impianto avvenuta nel 1996. E’ stato stimato che circa cinque milioni di tonnellate di roccia mineralizzata a Hg, essenzialmente cinabro (HgS), e, in misura minore, Hg nativo, siano state scavate e che solo una percentuale pari al 73% del Hg ad esse associato (105.000 t) sia stato recuperato (Gosar et al., 1997). Il rimanente è stato dissipato nell’ambiente a causa della scarsa efficienza dei processi di arrostimento del minerale: in conseguenza alle ricadute umide, i terreni circostanti, le sponde e i sedimenti del torrente Idrijca sono stati fortemente contaminati. L’influenza del Hg proveniente dal distretto minerario si è estesa all’intero Golfo di Trieste ma anche all’adiacente Laguna di Marano e Grado. A livello della Laguna, nel periodo compreso tra il 1949 e il 1984, si è sommato un ulteriore apporto dovuto allo scarico incontrollato di reflui contenenti Hg, utilizzato come catalizzatore, nell’impianto cloro-soda sito nella zona industriale di Torviscosa (Daris et al., 1993). Nella Laguna di Marano e Grado la contaminazione è stata accertata sia nei sedimenti sia lungo l’intera catena trofica (Mattassi et al., 1991; Brambati, 1997, 2001) ponendo così seri quesiti sul comportamento (ciclo biogeochimico, trasformazione, bioaccumulo e biomagnificazione) di questo metallo in un ecosistema dove coesistono importanti attività economiche per la popolazione ivi residente (pesca, acquacoltura, venericoltura e turismo). In particolare, come riportato in Sladonja et al. (2011), a partire dagli anni ’80, è stata introdotta in laguna la vongola filippina (Tapes philippinarum), che ha colonizzato quasi tutto l’areale risalendo il cuneo salino dei sistemi fluviali per circa 4-5 km. L’attività di raccolta e commercializzazione del bivalve rappresenta una notevole risorsa a supporto dell'economia delle popolazioni locali, tuttavia è fortemente subordinata alle condizioni ambientali e sanitarie dell’ambiente derivanti dalla condizioni chimico-fisiche dei suoi fondali. In questo contesto, a partire dal mese di Giugno 2008, è stato avviato un progetto di ricerca a carattere multidisciplinare denominato “MIRACLE” (Mercury Interdisciplinary Research for Appropriate Clam farming in Lagoon Environment), coordinato dal Dipartimento di Geoscienze dell'Università di Trieste (responsabile scientifico dott. Stefano Covelli) e finanziato dal Commissario Delegato per l’emergenza Socio-Economico Ambientale determinatasi nella laguna di Marano Lagunare e Grado. Il progetto ha visto il coinvolgimento di numerose unità operative istituzionali e scientifiche a livello nazionale (ARPA FVG, OGS-BIO, ISPRA, Università di Venezia) e internazionale (Istituto “Jožef Stefan" di Lubiana, Stazione di Biologia Marina di Pirano, University of Massachusetts-Lowell). Lo scopo finale era l’individuazione di nuove aree idonee da destinarsi alla venericoltura tenendo conto della diffusa contaminazione da Hg a livello dell’intera area lagunare. In virtù del ruolo centrale svolto nei cicli biogeochimici dell’ambiente marino, una particolare attenzione è stata posta alla caratterizzazione e al comportamento dei sedimenti. I risultati della ricerca approfondita su questa matrice costituiscono l’oggetto della presente dissertazione. L’attività di ricerca ha previsto una intensa fase di campionamento condotta a livello dell’intera Laguna seguita da una parte sperimentale di laboratorio che ha fatto luce su diversi aspetti biogeochimici del Hg. La distribuzione spaziale del metallo nei sedimenti superficiali è stata aggiornata prendendo in esame anche la forma metilata della quale non erano a disposizione dati pregressi a livello di intero areale. Le due forme mercurifere sono state correlate con i principali descrittori geochimici (granulometria, contenuto e qualità della sostanza organica) ponendo una particolare attenzione alle implicazioni che derivano dalla speciazione chimica del metallo tra le forme biodisponibili e refrattarie ai fenomeni di rimobilizzazione. L’indagine è stata successivamente estesa anche ai sedimenti sub-superficiali allo scopo di determinare lo spessore interessato dalla contaminazione. Sulla base dei tassi di sedimentazione, calcolati per la prima volta in laguna, è stata valutata l’evoluzione storica dell’accumulo di Hg, estrapolato l’inventario a livello dell’intero bacino lagunare e considerata la possibile evoluzione della contaminazione. Nella seconda fase della ricerca, sulla base delle possibili destinazioni d’uso del sistema lagunare e i fenomeni fisici a esse associato, sono state prese in esame le dinamiche delle specie mercurifere in colonna d’acqua a seguito di fenomeni di risospensione. Questa seconda parte delle attività è stata svolta allestendo esperimenti in condizioni controllate di laboratorio (mesocosmo) su sedimenti prelevati in due siti scelti laddove le operazioni di dragaggio, necessarie per consentire l’operosità dei canali, vengono eseguite periodicamente.
XXIII Ciclo
1969

Inicialmente, consideramos o mapa Logístico com os vários fenômenos nele presentes, para depois, ao perturbarmos esse mapa, adicionando periodicamente um termo de amplitude constante, identificarmos os novos fenômenos e as alterações que a introdução da perturbação faz aparecer. Apresentamos o circuito eletrônico de Matsumoto e, em seguida, o consideramos em um regime caótico perturbado por uma tensão elétrica senoidal externa. A introdução desta perturbação faz o circuito permanecer caótico, tornar-se periódico ou quasi-periódico no toro de duas frequências. Aplicamos diversos métodos de controle de caos a três sistemas (mapa Logístico, mapa de Hénon e circuito de Matsumoto). Para a estabilização de uma órbita periódica, consideramos os métodos de Ott-Grebogi-Yorke (OGY), de Romeiras, de Pyragas, de Sinha, de Singer e de H¨ubbler. Para o direcionamento da trajetória para um ponto de equilíbrio, usamos o método de Sinha. Para a transferência da trajetória para um dos atratores coexistentes no sistema de Matsumoto, usamos o método de Jackson-H¨ubbler (OPCL). Usando um conjunto de pertubações constantes em um parâmetro previamente escolhido, mostramos como é possével dirigir rapidamente uma trajetória, de qualquer um dos três sistemas considerados nesta tese, para um determinado alvo. Além disso, é mostrado como esse método pode ser aplicado experimentalmente.
Initially, we consider the Logistic map with its many non-linear phenomena. Then, we use this knowledge to discern new phenomena that shall appear when the map is perturbed, that is the Logistic map perturbed by a periodic and constant term. The Matsumoto\'s circuit is presented and, after we set this circuit to behave chaotically, we perturb it with a sinoidal wave, characterized by its frequency and amplitude. This perturbation is responsible for the appearence of a quasi-periodic and periodic oscillations, or the maintenance of chaos. We presented and applied many methods for controlling chaotic oscillations in three systems (the Logistic and Henon maps, and the Matsumoto\'s circuit), showing many ways for stabilizing a periodic orbit, using the methods of Ott-Grebogi-York (OGY), Romeiras, Singer, Sinhas and Huebbler. For targeting the trajectory to a equilibrium point, the Sinha\'s method was used. To transfer the system trajectory from one to another of the coexisting attractors presented in the Matsumoto\'s circuit, we use the Jackson-Huebbler (OPCL) method. Using a set of constant perturbations, in a previously chosen parameter, we showed how we can rapidly direct a trajectory of any of the considered three systems to a aimed target. Besides, it is shown how this method can be experimentally applied.

Les phénomènes évolutifs qui perturbent l'organisation des gènes dans les génomes eucaryotes sont de deux types : les changements dans l'ordre des gènes, ou réarrangements, et les modifications du contenu en gènes du génome, par duplications, délétions ou gains de gènes. Ces processus sont mal connus, tant au niveau de leurs mécanismes d'apparition que de leur impact fonctionnel et sélectif. Ce travail de thèse s'articule autour de deux projets. Le premier s'intéresse à la distribution des points de cassure de réarrangements évolutifs entre un génome ancestral et ses descendants modernes. Cette distribution a été modélisée en fonction des caractéristiques locales du génome pour mettre en évidence quels facteurs influencent la probabilité de cassure. Nos résultats montrent que la distribution des cassures peut s'expliquer simplement comme une fonction de la longueur des espaces intergéniques, fonction qui est cependant non-linéaire contrairement aux attentes sous un régime aléatoire classique. La répartition des points de cassure dans les génomes semble principalement liée à des propriétés de structure, et n'est que peu soumise à des contraintes de sélection. Elle pourrait être liée à la structure chromatinienne du génome. Le second projet s'inscrit dans le cadre du séquençage du génome du poisson zèbre, et fournit un aperçu global de l'organisation de ce génome. Les génomes de poissons téléostéens sont anciennement dupliqués : l'analyse est axée sur les conséquences de cette duplication. Les résultats montrent que le génome du poisson zèbre présente une organisation assez typique d'un génome téléostéen. Les gènes retenus en deux copies après la duplication du génome appartiennent à des catégories fonctionnelles particulières, et sont biaisés vers des gènes déjà conservés après les duplications 1R et 2R ayant eu lieu au début de l'histoire des vertébrés.

Les phénomènes évolutifs qui perturbent l’organisation des gènes dans les génomes eucaryotes sont de deux types : les changements dans l’ordre des gènes, ou réarrangements, et les modifications du contenu en gènes du génome, par duplications, délétions ou gains de gènes. Ces processus sont mal connus, tant au niveau de leurs mécanismes d’apparition que de leur impact fonctionnel et sélectif. Ce travail de thèse s’articule autour de deux projets. Le premier s’intéresse à la distribution des points de cassure de réarrangements évolutifs entre un génome ancestral et ses descendants modernes. Cette distribution a été modélisée en fonction des caractéristiques locales du génome pour mettre en évidence quels facteurs influencent la probabilité de cassure. Nos résultats montrent que la distribution des cassures peut s’expliquer simplement comme une fonction de la longueur des espaces intergéniques, fonction qui est cependant non-linéaire contrairement aux attentes sous un régime aléatoire classique. La répartition des points de cassure dans les génomes semble principalement liée à des propriétés de structure, et n’est que peu soumise à des contraintes de sélection. Elle pourrait être liée à la structure chromatinienne du génome. Le second projet s’inscrit dans le cadre du séquençage du génome du poisson zèbre, et fournit un aperçu global de l’organisation de ce génome. Les génomes de poissons téléostéens sont anciennement dupliqués : l’analyse est axée sur les conséquences de cette duplication. Les résultats montrent que le génome du poisson zèbre présente une organisation assez typique d’un génome téléostéen. Les gènes retenus en deux copies après la duplication du génome appartiennent à des catégories fonctionnelles particulières, et sont biaisés vers des gènes déjà conservés après les duplications 1R et 2R ayant eu lieu au début de l’histoire des vertébrés
Evolutionary processes disrupting the gene organisation in eukaryotic genomes belong to two categories: changes in the order of the genes, known as rearrangements, and changes in the content of the genome by gene duplications, deletions and gains. The mechanisms through which these events arise, and their functional and selective impact on genomes, are poorly understood. This thesis covers two different projects. Firstly, we investigated the distribution of rearrangement breakpoints between an ancestral genome and its modern descendants. This distribution was modelled according to local genomic characteristics to highlight factors influencing the breakage process. Our results show that the distribution of breakpoints can be simply explained as a function of intergenic spacers length, although in a non-linear fashion differing from classical random expectations. The repartition of breakpoints in genomes seems to be linked to structural properties, and is only marginally affected by selective constraints. It might in fact reflect local chromatin structure in the genome. The second project is part of the joint sequencing effort for the zebrafish genome, and provides an overview of the organisation of this genome. Teleost fish genomes are anciently duplicated: the analysis focuses on the consequences of this duplication. Results show that the zebrafish genome displays a typical teleost fish genome organisation. Genes retained in two copies after the whole genome duplication belong to specific functional categories, and are biased towards genes already conserved as duplicates after the 1R and 2R duplication events that have taken place early in vertebrate history

Many tumour cells are more sensitive to hyperthermia than non-cancerous cells. The nature of this greater thermal sensitivity is not clear. The present study indicates that a likely cause for this increased thermal sensitivity is membrane-associated. Plasma membrane enriched fractions were obtained from two solid rat tumours: D23, a hepatoma, and Mc7, a sarcoma. Lipids from these membranes were extracted, characterized, and compared to equivalent fractions from control tissue (liver). In both cases the tumour membranes had lowered cholesterol: phospholipid ratios. There was little differenceln the phospholipid classes, but there was somecliSigfetice in the fatty acid composition of the individual phospholipids. Fluorescence polarization studies were carried out on whole membranes and indicated that the overall 'order' of the tumour membranes was decreased with respect to the controls. In addition a plasma membrane bound enzyme, the Mg2+ATPase, was found to be considerably more thermolabile in the tumour cells. The addition of the membrane pertubant tetracaine produced a greater degree of disorder in the tumour membranes compared to controls, and enhanced the thermolability of the Mg2+ATPase. These differences are further evidence that the plasma membrane is a likely site for the primary lesion in cell heat injury. Results from in vivo studies support the above mentioned in vitro work. D23 and Mc7 tumours, grown in the foot, were subject to hyperthermia and the simultaneous application of a membrane perturbant, tetracaine. The addition of the tetracaine significantly increased the efficacy of the treatment. When the D23 tumour was grown in ethanol-dependent rats there was no difference in the 'adaptive' response of the tumour, compared to the normal, plasma membranes. There was no difference in the heat sensitivity of foot tumours grown in ethanol-fed rats compared to tumours from pair fed controls.

Un meilleur pilotage des procédés industriels de production continue passe par le contrôle des phénomènes perturbant leur conduite. Les systèmes informatisés de pilotage ne tiennent généralement pas compte des "dysfonctionnements" particuliers à un procédé ou à un mode de production. Ce mémoire s'efforce d'aborder ce problème en prenant pour exemple le fonctionnement d'un four rotatif dans une unité de clinkérisation. Dans ce cas, les perturbations principales sont provoquées par l'altération du réfractaire ou par l'adhérence de la matière (croûtage) sur la paroi interne pouvant conduire à la formation d'anneaux. La mise en place et l'informatisation d'un capteur infrarouge permettent de disposer en continu de profils thermiques sur plusieurs génératrices du four et donc d'observer en temps réel ces phénomènes. Le traitement numérique de ces signaux aide le "cuiseur" à conduire l'unité via des représentations graphiques temporelles ou géométriques et le calcul de paramètres représentatifs de l'évolution du croûtage. La mise en évidence de règles d'interprétation conduit à faire évoluer ce système vers un système de diagnostic de fonctionnement "intelligent". L'architecture proposée montre les modalités de couplage de cet outil au système de conduite.

Defining the circadian clock of Drosophila melanogaster in natural and shift-work regimes The Drosophila clock is based on a system of interconnected feedback loops where some positive elements (the proteins CLOCK (CLK) and CYCLE (CYC)) induce the synthesis of the negative elements (the proteins PERIOD (PER) and TIMELESS (TIM)) which in turn inhibit the action of the positive ones in a 24 hour cycle (Zordan et al., 2003). These loops are controlled by post transcriptional and translational regulation. The clock is mostly resetted by external stimuli, like light and temperature (Zeitgeber) (Lin et al 2001; Dunlap, 1999). Different per and tim transcripts have been reported to be regulated by temperature. For per a termal sensitive splicing of 89 bases in the 3’ UTR (Untranslated region) of the mRNA generates the perunspliced and the perspliced mRNA. The splicing induces an earlier evening activity at cold temperature (Collins et al., 2004; Majercak et al., 2004). A termal sensitive splicing in tim originates two transcripts: timnornal and timcold. In timcold the last intron of 858 bases is not removed via splicing at cold temperature (Boothroyd et al., 2007). Till now all the previous studies concerning the circadian clocks have been carried out in laboratory, which cannot reflect the complexity of the stimuli that are present in the natural environment. This work provides new insights at behavioural and molecular level about circadian clocks in natural regimes. The observations carried in natural conditions highlighted that a number of established findings from the laboratory may not be relevant in the wild, and that natural conditions appear to compensate for many of the defects observed in the laboratory in clock mutants (per01, tim01, tim03 , per01; tim01, perS, perL, clkjerk, Pdf01, cry0), revealing a surprising independence of rhythmic behaviour from core clock genes. All clock genotypes can show morning (M) and evening (E) peaks, and starting at moderate temperatures, they show an additional peak, called afternoon ‘anti-siesta’. The M component appears to be mostly a temperature-dependent response to dim light levels during the twilights. The evening activity is related to the photoperiod. The E component appear more modulated by the clock: many clock mutants show evening anticipation revealing the effects of a residual clock programme or at least the capability to activate a physiological response. Moreover, from the analysis of the transcriptional profiles of per and tim in natural conditions it has been observed that the proportion of the perspliced and timcold mRNA increases as the temperature decreases. D. melanogaster is also considered a good model to study sleep. Sleep in mammals is a phenomenon depending on the interaction between the homeostatic and the circadian systems. A sleep-like state characterized by posture, behavioural quiescence and elevated stimulation threshold, all characters which are used to define the sleep state in mammals, has been identified in Drosophila (Hendricks et al., 2000; Shaw et al., 2000). Recent studies have pointed out the deleterious effects generated by the disturbance of sleep and circadian clock on the health of shift-workers (Cho, 2001; Knutsson, 2003; Esquirol et al., 2009; Puttonen et al., 2010). To investigate the effects of a chronic impairment of sleep, at behavioural and molecular level, we used Drosophila as a model. To this purpose different shift-work regimes were superimposed to a fly population by means of a “shift-work machine” in which the “working activity” consists in maintaining the equilibrium contrasting continuous mechanical shocks. The effects of the shift-work regimes were studied by monitoring locomotor activity, mortality, anatomical and behavioural traits in controls and in shift-workers. The overall results show behavioural and anatomical effects induced by the shift-work. On the basis of these findings it can be suggest that Drosophila should be considered as a useful model to investigate on the effects of chronic perturbations of the endogenous clock.
L’orologio circadiano di Drosophila melanogaster in condizioni naturali e in regimi artificiali perturbati L’orologio circadiano di Drosophila melanogaster è basato su un sistema di loop molecolari interconnessi dove elementi “positivi” (le proteine CLOCK (CLK) e CYCLE (CYC)) inducono la trascrizione di elementi “negativi” (le proteine PERIOD (PER) e TIMELESS (TIM)) che a loro volta sono in grado di inibire la loro stessa trascrizione generando un periodo di circa 24 ore (Zordan et al., 2003). Questi loop circadiani sono regolati sia a livello trascrizionale che traduzionale e possono interagire con l’ambiente ricevendo stimoli luminosi e termici (Zeitgeber) in grado di sincronizzare l’orologio con i ritmi ambientali esterni (Lin et al 2001; Dunlap, 1999). I geni period e timeless originano diverse varianti di splicing dell’mRNA. Lo splicing temperatura sensibile di un introne di 89 paia di basi nella regione 3’ UTR (Untranslated region) del gene period determina la formazione di due tipi di mRNA: perunspliced e perspliced. La forma perspliced è prevalente a basse temperature e si accumula più rapidamente rispetto alla forma perunspliced, accelerando tutto il meccanismo molecolare circadiano. In conseguenza di ciò in condizioni di laboratorio (LD12:12) a basse temperature (18°C) la fase dell’attività locomotoria serale delle mosche è anticipata (Collins et al., 2004; Majercak et al., 2004). Anche per il gene timeless sono state individuate due varianti di splicing dell’mRNA: timnornal e timcold. Nella variante timcold viene ritenuto, a basse temperature, l’ultimo introne di 858 paia di basi. Anche in questo caso si tratta di uno splicing temperatura regolato (Boothroyd et al., 2007). Finora l’orologio circadiano è stato studiato in condizioni di laboratorio, condizioni che non riflettono la complessità e la variabilità degli stimoli presenti nell’ambiente esterno. Questo lavoro di tesi ha affrontato per la prima volta lo studio dell’orologio endogeno circadiano di Drosophila melanogaster in condizioni naturali mediante un’analisi a livello comportamentale e molecolare. Le osservazioni condotte hanno mostrato come il modello dell’orologio circadiano definito dagli esperimenti di laboratorio sia difficilmente applicabile in condizioni naturali e come molti aspetti dell’attività locomotoria, un fenotipo controllato dall’orologio endogeno, benché osservati in condizioni di laboratorio nelle linee mutanti per i principali geni orologio siano assenti in natura. Molti dei genotipi mutanti analizzati (per01, tim01, tim03, per01tim01, perS, perL, clkjerk, Pdf01, cry0) si sono dimostrati ritmici in condizioni naturali con una chiara attività mattutina e serale. La componente mattutina del comportamento è risultata essere, in condizioni naturali, una risposta regolata dal variare dei parametri ambientali esterni (luce e temperatura), mentre l’attività serale è apparsa maggiormente controllata dall’orologio endogeno. A livello molecolare è stato osservato un andamento ciclico dell’espressione dei geni period e timeless in condizioni naturali e la proporzione delle diverse varianti di splicing della trascrizione dei due geni sul totale dell’mRNA espresso è risultata temperatura dipendente sia in condizioni di laboratorio che in natura. D. melanogaster è anche un ottimo modello per lo studio del sonno e dei suoi disturbi. Il sonno nei mammiferi è il risultato dell’interazione tra un processo omeostatico e uno circadiano. Tutte le caratteristiche proprie del sonno come la postura, la diminuzione del livello di attenzione e l’insorgere di una soglia di risveglio sono state riconosciute e ridefinite nelle mosche (Hendricks et al., 2000; Shaw et al., 2000). Studi recenti hanno inoltre dimostrato come la deregolazione cronica del sonno si traduca in conseguenze negative per la salute aumentando il rischio di cancro e di molte malattie legate al sonno (Cho, 2001; Knutsson, 2003; Esquirol et al., 2009; Puttonen et al., 2010). La seconda parte del mio lavoro di tesi ha cercato di definire un modello per applicare e studiare gli effetti della turnazione nel lavoro (shift-work cronico) nelle mosche. E’ stata costruita un’apparecchiatura per mimare con le mosche regimi artificiali di shift-work. Le analisi condotte hanno mostrato che lo shift-work cronico nelle mosche produce effetti negativi sulla sopravvivenza e su alcuni fenotipi comportamentali associati alla percezione visiva del movimento. Nel loro insieme i risultati ottenuti hanno dimostrato come Drosophila possa essere considerata un buon modello per questo tipo di studi.

Les microRNA sont de petites molécules d’ARN non-codantes de 22nt qui s’apparient avec des ARN messagers cibles et induisent leur dégradation, ou inhibent leur traduction. Ils jouent un rôle essentiel dans le contrôle du développement et de la différenciation cellulaire, et leur dérégulation induit des défauts de développement et des maladies génétiques. La compréhension des mécanismes de biogenèse et d’action des miRNA constitue donc une étape essentielle vers la compréhension et le traitement de ces désordres. J’ai construit un système indicateur « automiR » qui permet de suivre l’activité de miRNA artificiels dirigés contre la protéine fluorescente GFP. Dans ce système, les miRNA artificiels s’associent à la protéine Argonaute-2 pour réprimer l’expression de la GFP par clivage de l’ARN messager, et non à la protéine Argonaute-1 partenaire d’une majorité de miRNA chez la drosophile. Cette particularité constitue l’atout principal du système automiR. Il est maintenant établi qu’une fraction des miRNA agit via AGO2, mais cette voie de répression des gènes reste mal caractérisée. J’ai établi une lignée cellulaire exprimant le système automiR et je l’ai utilisée pour cribler des mutations et des produits chimiques inhibant les miRNA. Le crible génétique m’a permis identifier 20 gènes dont le rôle dans la répression par les miRNA n’avait pas encore été décrit. Leur caractérisation a révélé qu’ils sont requis, en aval de la biogenèse des miRNA, pour leur activité répressive. Le crible chimique m’a permis d’indentifier 64 composés inhibant l’activité des miRNA représentant de nouvelles thérapeutiques potentielles pour lutter contre les désordres liés à la surexpression de miRNA

La cycline A2 est un régulateur essentiel du cycle cellulaire qui, en association avec des kinases dépendantes des cyclines (CDK) régule la réplication de l'ADN et l’entré des cellules en mitose. Dans de nombreux types de cancers humains, la cycline A2 a été considérée comme un facteur de prolifération contribuant à la cancérogenèse de par ses fonctions dans la régulation du cycle cellulaire. Récemment, la complexité des fonctions de cycline A2 a été révélée. Certaines études in vitro ont démontré que l'inactivation de la cycline A2 induit une augmentation de la motilité cellulaire et de l'invasion dans les fibroblastes consécutive à une activation défective de RhoA. De plus, il a été montré que l'inactivation de la cycline A2 induit la EMT par l’intermédiaire d’une augmentation de l'activité transcriptionnelle de la β-caténine, mais aussi via la voie TGFβ/Prefoldin. Ces études suggèrent que des niveaux réduits de cycline A2 sont liés à une invasion accrue et à l’apparition de métastases dans certains types de cancer. A l’aide d’un modèle de souris mutante pour la cycline A2, une étude récente a établi une fonction de cette dernière, indépendante des CDK, dans la réparation des cassures double brin de l'ADN et a montré que la perte de la cycline A2 favorise l’apparition de cancers de la peau et du poumon. L’ensemble de ces études met en évidence l’existence de multiples fonctions pour la cycline A2. Mon travail de thèse a consisté à explorer le rôle de la cycline A2 dans l'homéostasie du colon et le développement du Le cancer colorectal.Pour évaluer la valeur pronostique de la cycline A2 dans le CCR, nous avons analysé l'expression de la cycline A2 par IHC sur un grand nombre d'échantillons tumoraux dérivés de patients atteints de CCR de différents stades. Nous avons trouvé que les niveaux élevés de la cycline A2 sont corrélés avec un mauvais pronostic et une survie plus faible chez les patients atteints de CCR de stade I et II. Cependant, une diminution de l'expression de la cycline A2 a été détectée aux stades III et IV par comparaison aux biopsies de CCR de stade I et II. Il est tentant de proposer que le profil d'expression de la cycline A2 reflète ses rôles distincts au cours de la cancérogenèse du côlon, comme la prolifération cellulaire au stade précoce, lorsqu'elle est fortement exprimée, mais favorise l'invasion et l'agressivité à des stades plus avancés, lorsque ses niveaux d’expression sont réduits.En complément de cette étude clinique, nous avons généré des modèles murins porteurs d’une mutation constitutive ou inductible de la cycline A2 dans l’épithélium intestinal. Nous avons montré que la déplétion de la cycline A2 dans l'épithélium intestinal de la souris provoque une rupture de la crypte colique, une inflammation, une augmentation de la prolifération des cellules épithéliales et l’apparition de dysplasies de bas et haut grade, reconnues comme lésions précancéreuses dans le CCR. Ces observations suggèrent un rôle majeur pour la cycline A2 dans la régulation de l'homéostasie du côlon et l'initiation de la tumorigénèse. Une analyse plus poussée a révélé une proportion accrue de lésions au niveau de l'ADN et une activation aberrante de la β-caténine, anomalies couramment détectées chez les patients humains atteints de CCR et considérées comme les premières altérations de cette pathologie. En outre, nous avons détecté une expression élevée de NFkB et YAP1 chez les souris mutantes pour la cycline A2, voies qui jouent un rôle critique dans la régénération tissulaire et peuvent conduire la dédifférenciation des cellules épithéliales du côlon contribuant ainsi à la tumorigenèse. Finalement, les souris mutantes cycline A2 ont été soumises à un protocole de colite associé au cancer et ont développé une proportion accrue d'inflammation, mais aussi de dysplasies et d'adénocarcinomes, en taille et en nombre, suggérant que la perte de la cycline A2 participe à la carcinogenèse colorectale chez la souris
Cyclin A2 is an essential cell cycle regulator required for accurate DNA replication and mitotic entry in association with cyclin-dependent kinases (CDKs). In multiple types of human cancers, cyclin A2 was considered as a proliferation driver contributing to carcinogenesis based on its function to promote cell cycle.Recently, the complexity of cyclin A2 functions has been revealed. Some in vitro studies demonstrated that cyclin A2 inactivation induces increased cell motility and invasiveness of mouse fibroblasts due to defective RhoA activation. Moreover, cyclin A2 inactivation has been shown to induce EMT through the upregulation of β-catenin transcriptional activity, but also via the TGFβ/Prefoldin pathway. These studies suggest that reduced levels of cyclin A2 are linked to increased invasiveness and metastasis in some cancer types. Using a cyclin A2 mutant mouse model, a recent study established the CDK-independent function of cyclin A2 in the repair of double-stranded DNA breaks and showed that loss of cyclin A2 promotes tumorigenesis in skin and lung due to deficient DSBs repair.Altogether, these studies highlight the multiple functions cyclin A2 can execute. The aim of my thesis was to explore the role of cyclin A2 in colon homeostasis and colorectal cancer development.To evaluate the prognostic value of cyclin A2 in CRC, we analyzed cyclin A2 expression by IHC on tumor samples derived from CRC patients of different stages. We found that high levels of cyclin A2 correlate with bad prognosis and lower survival in patients with stage I and II CRC. However, decreased cyclin A2 expression was detected in stage III and IV by comparison to stage I and II CRC biopsies. Complementary to the clinical study, we generated tissue-specific mutant mouse models bearing either a constitutive or inducible cyclin A2 deletion in the intestinal epithelium. We showed that depletion of cyclin A2 in mouse intestinal epithelium causes colonic crypt disruption, inflammation, increased proliferation of epithelial cells and occurrence of low- and high-grade dysplasia, recognized as precancerous lesions of CRC. These observations suggest a major role for cyclin A2 in the regulation of normal colon homeostasis and tumor initiation. Further analysis revealed an increased proportion of DNA damage and aberrant activation of β-catenin, commonly detected in human patients with CRC and which are considered as the first occurring alterations in this pathology. Furthermore, we detected elevated expression of NFkB and YAP1 in the colons of cyclin A2 mutant mice, pathways that have been previously shown to play critical roles for tissue regeneration after tissue damage and to drive dedifferentiation of colonic epithelial cells thus contributing to tumorigenesis. Finally, cyclin A2 mutant mice were subjected to a modified colitis-associated CRC model and developed increased proportion of inflammation, but also dysplasia and adenocarcinomas, in size and numbers, suggesting that loss of cyclin A2 contributes to inflammation-associated colorectal carcinogenesis in mice

Although mosquito monitoring systems in the form of dry-ice bated CDC light traps and sentinel chickens are used by mosquito control personnel in Polk County, Florida, the placement of these are random and do not necessarily reflect prevalent areas of vector mosquito populations. This can result in significant health, economic, and social impacts during disease outbreaks. Of these vector mosquitoes Culex nigripalpus, Culex erraticus, Coquillettidia perturbans, and Aedes vexans are present in Polk County and known to transmit multiple diseases, posing a public health concern. This study seeks to evaluate the effect of Land use Land cover (LULC) unique features and precipitation on spatial and temporal distribution of Cx. nigripalpus, Cx. erraticus, Cq. perturbans, and Ae. vexans in Polk County, Florida, during 2013 and 2014, using negative binomial regression on count data from eight environmentally unique light traps retrieved from Polk County Mosquito Control. The negative binomial regression revealed a statistical association among mosquito species for precipitation and LULC features during the two-year study period, with precipitation proving to be the most significant factor in mosquito count numbers. The findings from this study can aid in more precise targeting of mosquito species, saving time and resources on already stressed public health services.

BACKGROUND: il morbo di Parkinson è una patologia neurodegenerativa caratterizzata da un ampio spettro di sintomi clinici; tra questi i deficit del cammino e del controllo posturale rappresentano la componente preminente dell’alterato quadro motorio tipico di questa patologia. Tra gli interventi non farmacologici il treadmill rappresenta un’opzione terapeutica dalla quale si stanno sviluppando nuovi approcci, quali l’aggiunta di destabilizzazioni posturali. OBIETTIVO: confrontare l’efficacia del training tramite treadmill perturbato, con il training convenzionale tramite treadmill, in soggetti affetti da morbo di Parkinson, per quanto concerne gli outcome del cammino e del controllo posturale. DISEGNO DI STUDIO: revisione sistematica di Randomized Controlled Trials, redatta secondo la checklist del PRISMA statement. FONTI DEI DATI: banche dati elettroniche indagate PubMed, CENTRAL, PEDro, Trip Medical Database, CINAHL. Ricerche aggiuntive sono state condotte tramite l’analisi delle citazioni bibliografiche di articoli trattanti i medesimi argomenti. La ricerca è stata condotta da Marzo 2020 al 15 Ottobre 2020. CRITERI DI ELEGGIBILITA’: sono stati consultati RCT che indagassero la comparazione tra il PTT e il CTT, in soggetti affetti da morbo di Parkinson, per quanto concerne gli outcome riguardanti il miglioramento del cammino e del controllo posturale. RISULTATI: 5 studi inclusi. L’analisi complessiva dei risultati non indica una superiore efficacia PTT, rispetto al CTT, nella riabilitazione di pazienti affetti da morbo di Parkinson. Entrambe le tipologie di intervento mostrano miglioramenti significativi relativamente al cammino, e miglioramenti non rilevanti riguardo al controllo posturale. Risultano però delle “tendenze positive” a favore dell’intervento con PTT per alcuni parametri sia del cammino, sia del controllo posturale. CONCLUSIONI: il riscontro di “tendenze positive” nel PTT fornisce uno spunto rilavante per la pratica clinica e per ricerche future.

Nella prima parte dello studio si è descritto il mantenimento dell’equilibrio in seguito a perturbazioni indotte da stimoli esterni. La risposta posturale è stata analizzata dal punto di vista dinamico, cinematico ed elettromiografico, ottenendo una descrizione completa dei meccanismi adottati per contrastare la perdita di equilibrio. Vari parametri sono stati estratti dallo spostamento del centro di pressione e del centro di massa e sulla base dell’attività muscolare acquisita mediante elettromiografia di superficie, con lo scopo di ottenere indici che correlino con le diverse caratteristiche della perturbazione. Sulla base dei dati cinematici sono state descritte le strategie posturali adottate per contrastare la perturbazione indotta, allo scopo di quantificare se differenti condizioni perturbative facciano sorgere differenti risposte, che prevedono l’uso di differenti strategie articolari. Infine il controllo dell’equilibrio è stato descritto attraverso un modello a doppio pendolo inverso, attraverso tecniche che, sebbene ben note ed impiegate in altri ambiti, risultano poco usate per la descrizione della postura in condizioni dinamiche. Nella seconda parte si è indagato il controllo della dinamica del cammino in termini di attività muscolare, acquisita su centinaia di passi consecutivi, permettendo un nuovo tipo di descrizione non basata solamente su parametri temporali ma anche sulla frequenza con cui ogni modalità di attivazione muscolare di presenta durante il cammino. I principali risultati includono la quantificazione dei pattern di co-contrazione dei flessori di caviglia e la loro ricorrenza durante il cammino. Si sono inoltre descritte le differenze legate al genere riguardanti l’attività dei principali muscoli dell’intero arto inferiore. Basandosi sui precedenti risultati si sono poi quantificate le differenze legate al genere nei pattern di co-contrazione degli antagonisti che regolano la meccanica dell’articolazione di caviglia durante il cammino.
In the first part of this work a characterization of the upright stance recovery after balance perturbation administered through external stimuli was performed. Balance response has been analyzed in dynamics, kinematics and electromyographic terms, in order to obtain a complete description of which mechanisms are employed to withstand sudden stance perturbations. A series of parameters have been extracted from center of pressure and center of mass displacement and from electromyographic signals, acquired from lower limb and trunk muscles, in order to obtain a series of indexes which can correlate with the different characteristic of perturbations. From kinematic data, a description of the postural strategies adopted to withstand perturbations has been performed, in order to observe whether different perturbation conditions evoke different responses, employing different articular joints. Eventually, a first attempt to model perturbed upright stance through a double-link inverted pendulum is proposed, applying control systems seldom employed in describing this kind of dynamic motor task. In the second part, the motor control during the walking task was described in terms of muscular activity. Myoelectric signals were acquired in hundreds of consecutive strides, obtaining a new type of description, not only in terms of temporal parameters of muscles activity but also in terms of the occurrence frequency of each muscular activation modality during gait. The main outcomes include the description of co-contraction activity between ankle flexor muscles and the assessment of the recurrence of each co-activation pattern during walking. Furthermore, a description of the whole lower limb muscles behavior was performed, aimed to the quantification of gender-based differences in muscular recruitment during gait. Then, these two aspects were joined in assessing gender-related differences in co-contraction activity of muscles which control the ankle joint mechanics during walking.

This disertation presents optimization algorithm with probability direction vector. This algorithm, in its basic form, belongs to category of stochastic optimization algorithms. It uses statistically effected perturbation of individual through state space. This work also represents modification of basic idea to the form of swarm optimization algoritm. This approach contains form of stochastic cooperation. This is one of the new ideas of this algorithm. Population of individuals cooperates only through modification of probability direction vector and not directly. Statistical tests are used to compare resultes of designed algorithms with commonly used algorithms Simulated Annealing and SOMA. This part of disertation also presents experimental data from other optimization problems. Disertation ends with chapter which seeks optimal set of control variables for each designed algorithm.

The aim of this thesis is to calculate the stiffness and damping coefficients for radial hydrodynamic bearings. Cylindrical and lemon hydrodynamic bearings are considered. The solution to this problem mainly depends on the hydrodynamic pressure in the bearing. The numerical solution of the Reynolds equation is used to calculate the pressure. The effect of variable viscosity and density of the lubricant due to temperature changes is considered. The static equilibrium position of the journal centre is also solved. The stiffness and damping coefficients are determined using small amplitude journal motions about the equilibrium position. Three methods for determining these coefficients are presented. The outcome of this thesis is an algorithm for the calculation of stiffness and damping coefficients for cylindrical and lemon bearings. Results for lemon bearings are presented and comparison with the commercial software DynRot BR is made. The benefit of this thesis is the creation of an algorithm for the calculation of journal centre equilibrium position, a new way of incorporating the temperature changes in the viscosity and the density of the lubricant, and the modification of a method for calculating stiffness and damping coefficients based on experimental analogy.

碩士
中山醫學大學
生物醫學科學學系碩士班
100
Nitric oxide (NO) is a simple molecule that produced by nitric oxide synthase (NOS). Lipopolysaccharide (LPS) and interferon-γ (IFN-γ) stimulate the activation of inducible nitric oxide synthase (iNOS) and produce large amount of NO. In this study, the effect of cytochalasin D (an actin filament disrupting agent) , β,β’-Iminodipropionitrile (IDPN, an intermediate filaments disrupting agent), nocodazole (a microtubule disrupting agent) on LPS and IFN-γ-stimulated NO production in MES-13 cells were investigated. At different concentrations tested, the cell morphology and cell viability of LPS/ IFN-γ- treated MES-13 cells were dramatically altered after the treatment of cytochalasin D or nocodazole but not IDPN. NO production and iNOS protein expression showed no significant difference when treated with cytochalasin D. Nocodazole treatment reduced cell viabiblity, NO production and iNOS protein expression. Without affecting cell viability of MES-13 cells, IDPN decresed NO production, iNOS protein expression, and iNOS mRNA expression. IDPN decreased iNOS gene expressions through attenuated ERK1/2 MAPK activation, but had no effect on the p38 and JNK MAPKs, and attenuated nuclear fraction translocation of NF-κB. Thus, our data indicate that IDPN block LPS/IFN-γ- stimulated iNOS expression via inhibition of the ERK and NF-κB signaling pathways in MES-13 cells.

碩士
國立臺灣大學
土木工程學研究所
106
The modeling of the concentration of suspended sediment necessarily involves with uncertainty. The main goal of this research is to predict the output concentration of suspended sediment in Xindian river in Taipei, Taiwan. Mike 21 Hydrodynamic Model (HD) and Mike 21 Sediment Transport (ST) model are utilized to the modeling, and the study area is focused on Xindian river watershed. First, under the boundary discharge and normal depth conditions, the output depth-averaged horizontal flow velocity can be obtained from the Hydrodynamic Model, then the output of Hydrodynamic Model input to ST to simulate the output concentration. Second, the historical stage-discharge rating curve data and concentration-discharge rating curve are used for calibration validation. The Manning number and dispersion coefficient are the main items to be calibrated. Finally, after calibration and validation, a flood design with 1000 cubic meter per second (cms) is adopted to predict the concentration using a state-of-the-art method for uncertainty analysis called the perturbance moment method (PMM). The PMM is more efficient than the Monte-Carlo simulation (MCS). In MCS, calculations may become cumbersome when they involve multiple uncertain parameters and variables. In the PMM, the entire probability distribution of a random variable is redistributed among three points., and the statistical moments (such as mean value and standard deviation) for the output can be presented by the representative points and perturbance moments based on the parallel axis theorem. With assumed independent parameters and variables, the computation time of the PMM is significantly lower than MCS for a comparable modeling accuracy. This research, takes natural and parameter uncertainty into account, with natural uncertainty grain size are considered since the grain size is the input data in the ST model and for the parameter uncertainty the Manning number and dispersion coefficient are considered since they are main parameters for the calibration in the HD model and ST model. After evaluating the moments of output suspended sediment concentration by PMM, the range of the suspended sediment concentration prediction will be obtained.

In the present work we study gravitational waves in the approximation of high frequency, and their interaction with matter waves with comparable frequency. We generalize the formalism of R. A. Isaacson to the case of non-vacuum spacetimes. We formulate and study a technique of so called averaging, which helps us to separate slow changes and high-frequency fluctuations of various tensor fields. The described methods are used in examples with a given particular metric - so called background metric. We thus study the interaction of high-frequency gravitational waves on the Robinson- Trautman background and the high-frequency electromagnetic waves. Further, we seek a perfect fluid with high-frequency energy-momentum tensor that could coexist with high-frequency gravitational waves on the flat Friedmann-Lemaˆıtre-Robertson-Walker background; again, we examine the relation between those potential gravitational and matter waves.

Title: Ray-based Born approximation Author: Libor Šachl Department: Department of Geophysics Supervisor: RNDr. Luděk Klimeš, DrSc. Supervisor's e-mail address: klimes@seis.karlov.mff.cuni.cz Abstract: One of the aims of this thesis was coding of program grdborn.for for computing the 2D and 3D ray-based Born approximation of the first order in an inhomoge- nous isotropic medium without attenuation. The computation of 3D amplitudes using the 2D Born approximation is based on the correction term, which is de- rived. The program is further used in computing the Born approximation in various models. We test its performance in three simple models. We study the effect of the discretization, the spurious waves introduced by the finite size of the grid etc. In the next step, we focus on the computations in more compli- cated models. We compute the Born seismograms in 2D heterogenous models. We study the diffracted waves, the effects of caustics etc. Keywords: Born approximation, ray theory, velocity model, perturbation 1

In this work, we study the backreaction of high-frequency gravitational waves on cosmological backgrounds. To describe the wave, we use the Isa- acson formalism, specifically the WKB approximation, which allows us to express the backreaction through an effective stress-energy tensor of the gra- vitational wave. First, we consider the inhomogeneous cosmological model of Charach and Malin, which contains gravitational waves and a massless scalar field mini- mally coupled to gravity. We show that although this is a spatially compacti- fied solution, it is possible to add a high-frequency perturbation and solve Einstein's equations with the effective stress-energy tensor in a consistent way. The bacreaction is of the same order as the influence of the scalar field. Second, we add multiple incoherent high-frequency waves to the homoge- neous Kasner background, and discuss the relation to the late-time limit of the Gowdy (vacuum Charach and Malin) model. 1

In this thesis, we study the influence of non-gravitational perturbations induced by the Yarkovsky/YORP effect and solar radiation pressure (SRP) on the orbital evolution of selected asteroids, asteroid families and pairs. These perturbations are of great importance if one wants to perform precise and long-term propagation of meter-sized and kilometer-sized bodies. Although they have found many applications in the Solar System, here, we particularly investigated how they influence the orbit of near-Earth asteroid (99942) Apophis and what is their role in the age determination of asteroid families and pairs. Our numerical simulations showed that the perturbations of Apophis' orbit caused by the SRP are orders of magnitude smaller than those produced by the Yarkovsky effect. The age determination of asteroid families and pairs was another pillar of this work. Over the past decade it turned out that the Yarkovsky effect must be taken into account for backward propagation of pair/family members. We modified the current method for estimating the age of asteroid pairs to be suitable for weakly convergent cases and discovered 7 young pairs with similar-sized components, which is in contradiction with the current theory of pair formation. In addition, we focused on an interesting pair of asteroids -...

This thesis extends the basic ordinary differential equations (ODE) course, specifically considering perturbations of ODEs. We introduce uniformly asympto- tic approximation and uniformly ordered approximation. We provide a perturba- tion-based method of computing derivatives of ODE solutions with respect to: an initial value, a parameter, and initial time. We present the method of averaging, error estimate, and a theorem about the existence and stability of a periodic so- lution to ODEs in periodic standard form. Furthermore, we apply the method of averaging to determine the period of a periodic solution of Duffing equation without forcing or damping. All the terms and methods of perturbation theory used in the thesis are accompanied with examples. 1