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Background Ovarian follicular fluid serves as the microenvironment for a maturing oocyte prior to ovulation. Previous studies have shown that gilts fed a high fibre (HF) diet before ovulation have improved fertility compared to gilts fed a control (C) diet, including a higher proportion of metaphase II oocytes following in vitro maturation (IVM). Hypothesis The molecular composition of porcine follicular fluid (pFF) was altered by the diet and that these alterations conferred the fertility benefits. Aims The aim of this study was to compare the protein composition of pFF from pigs fed a control diet with pFF of pigs fed a high fibre diet, to identify whether a high fibre diet fed to pigs during their oestrous cycle altered the composition of pFF. Additionally, the pFF of fertile animals was compared with the pFF of non-fertile animals to identify whether pFF composition was associated with fertility; fertile animals produced an embryo following in vitro fertilisation (IVF). Differences in the molecular composition were to be used to ascertain the potential underlying mechanism(s) involved in dietary induced improvements to oocyte maturation. Results The protein composition of pooled pFF from 12 HF-pigs and 12 C-pigs was compared by liquid chromatography tandem mass spectrometry (LC-MS/MS). Additionally, within each dietary group, the composition of pooled pFF from pigs whose oocytes produced blastocysts following in vitro fertilisation (C-Bl and HF-Bl) was compared with pFF from pigs whose oocytes did not produce blastocysts (C-No and HF-No respectively; n=6 per group). These proteomic analyses identified differentially expressed proteins, associated with several canonical pathways including acute phase response signalling, complement system and LXR/RXR activation, as determined by Ingenuity Pathway Analysis. Quantitative western blots revealed the differential expression of candidates associated with these canonical pathways. Plasminogen expression was lower (P≤0.05) in pFF of HF-pigs compared to pFF of C-pigs. In pFF from C-Bl gilts, apolipoprotein A4 (P≤0.01) and apolipoprotein M (P≤0.05) expression were higher compared to pFF from C-No gilts. Plasmin expression was lower (P≤0.05) in pFF from HF-Bl gilts compared to pFF from C-Bl gilts. Due to the interest in the differentially expressed apolipoproteins (involved in cholesterol and lipid efflux), a targeted metabolomic analysis was carried out to measure the concentration of nine fatty acids (FAs) in pFF of individual pigs in C-No, C-Bl, HF-No, HF-Bl groups (n=6 per group); adrenic, arachadonic, arachidic, dihomo- γ-linolenic, docosapentaenoic, erucic, linoleic, palmitoleic and oleic acids were measured by LC-MS/MS. The analysis revealed the lower concentration of linoleic acid (LA, p≤0.05) and higher concentration of erucic acid (P≤0.05) in HF-pFF compared to C-pFF. Following the results of the targeted metabolomic analysis, cumulus-oocytecomplexes (COCs) were matured in TCM 199 medium supplemented with 0 (No-LA), 50, 100 or 200 μM LA for 44 hours (n = 320 per treatment). COC diameters were measured and the COCs were categorised into "full", "partial" or "no" expansion. COCs were denuded, fixed and stained to determine their stage of maturation. IVM with 200 μM LA resulted in the reduced diameter of COCs (p≤0.01), fewer COCs with full cumulus expansion (p≤0.05) and fewer metaphase II oocytes (p≤0.05). Discussion Plasminogen is the precursor to plasmin, a proteolytic enzyme involved in weakening the follicular wall prior to ovulation. The lower expression of plasminogen and plasmin in pFF of high fibre pigs implies a delay in the accumulation of the inflammatory proteins required for ovulation. The delay in ovulation can result in the lengthening of the oocyte maturation process, leading to more mature oocytes, as observed in the previous studies. A disruption in the expression of apolipoproteins may also occur in high fibre-fed pigs. The increase in apolipoproteins associated with blastocyst development was only observed with pFF of control pigs but not high fibre pigs. An alteration in lipid homeostasis in the high fibre pigs could potentially affect oocyte energy consumption. LA concentration was also lower in pFF of high fibre pigs. LA is an essential fatty acid, indicating that the difference in concentration is directly from the diet. The lower levels of LA can potentially be beneficial to oocyte maturation, which is substantiated by the negative effects of a high LA concentration on IVM of abattoir derived oocytes.

Η παρούσα διδακτορική διατριβή έχει ως στόχο την ανάλυση και έλεγχο ρευστοδυναμικών συστημάτων χρησιμοποιώντας έξυπνα υλικά όπως πιεζοκρύσταλλοι για τον σχεδιασμό επενεργητών. Στο Μέρος Ι, εκτιμάται η απόδοση μιας πρωτότυπης πιεζο-υδραυλικής αντλίας με χρήση Πεπερασμένων Στοιχείων. Η συγκεκριμένη διάταξη αποτελείται από ένα έμβολο και δύο παθητικές βαλβίδες με συχνότητα λειτουργίας μεγαλύτερη των 100Hz. Το αναπτυχθέν μοντέλο πεπερασμένων στοιχείων λαμβάνει υπόψιν την συμπιεστότητα του ρευστού, την περιορισμένη διάδοση του κύματος πίεσης, τυρβώδη ροή και αμφίδρομη αλληλεπίδραση ρευστού-στερεού των βαλβίδων. Με τα αποτελέσματα των προσομοιώσεων υπολογίστηκε η απόδοση της αντλίας και ακολούθησε παραμετρική βελτιστοποίηση κύριων παραμέτρων της βαλβίδας. Έτσι, έγινε εφικτή η λειτουργία σε υψηλότερες συχνότητες (500Hz) με βελτιωμένη απόδοση. Στην συνέχεια, μελετήθηκε ιδεατό σύστημα με ενεργές βαλβίδες ώστε να αναπτυχθούν τεχνικές ελέγχου του χρονισμού των βαλβίδων. Οι προσομοιώσεις έδειξαν σημαντικά περιθώρια βελτίωσης με ενεργές βαλβίδες, ενώ ανέδειξαν την σημασία της διάδοσης του κύματος, ιδιαίτερα κατά τον συντονισμό. Στο Μέρος ΙΙ, προτάθηκε ένας πρωτότυπος επενεργητής, βασισμένος στην εκμετάλλευση του συντονισμού του ρευστού. Αυτή η προσέγγιση επιτρέπει την μηχανική ολοκλήρωση της αντλίας μέσα στον επενεργητή, ενώ απαιτείται μόνο μια βαλβίδα υψηλής συχνότητας σε αντίθεση με υπάρχοντα συστήματα όπου απαιτούνται δύο (εισαγωγής, εξαγωγής). Ο πρωτότυπος επενεργητής μοντελοποιήθηκε με απευθείας διακριτοποίηση των εξισώσεων Navier Stokes με συμπιεστότητα και εξήχθη ένα μοντέλο χώρου κατάστασης. Παράλληλα με το μοντέλο πιεζοκρυστάλλων και της ροής της βαλβίδας ολοκληρώθηκε το μοντέλο του επενεργητή, ενώ τα βασικά στοιχεία του μοντέλου επιβεβαιώθηκαν με πειραματικά δεδομένα. Επίσης επιβεβαιώθηκε η αρχή λειτουργίας του προτεινόμενου συστήματος του επενεργητή με πειραματικές μετρήσεις. Στην τελευταία ενότητα της διατριβής αναλύονται βασικά στοιχεία με στόχο την βελτίωση της λειτουργίας του επενεργητή. / The present PhD thesis has a key object the analysis and control of fluid dynamics systems taking advantage of the smart material properties like piezocrystals for the design of actuators. In Part I, the performance of a prototype piezohydraulic pump is estimated using the Finite Element Method. The specific setup consists of a piston and two passive valves with an operating frequency greater than 100Hz. The developed Finite Element Model takes into account fluid's compressibility, the limited pressure wave propagation, turbulent flow and Fluid Structure Interaction of the valves with the fluid. Simulation results were used to calculate the pump's performance and a parametric optimization of valve's key parameters is performed. Much higher operating frequencies (500Hz) with improved performance is achieved. In the sequel, studies on a ideal active valve system are undertaken and control techniques of valve timing are developed. Simulations revealed the potential benefit from an active valve system and also revealed the importance of accounting wave propagation phenomena, especially during resonance. In Part II, a novel fluid actuator based on the exploitation of fluid resonance is proposed. This approach allows the integration of the pump within the actuator, whereas only one high frequency valve is needed, in contrast with existing systems where two high frequency valves are needed (inlet, outlet). The novel actuator is modeled using a direct discretization of the compressible Navier Stokes equations and a state space model is derived. Along with the piezoelectric and valve flow model a complete model of the actuator is formulated. The key components of the model are verified with experimental data from a prototype actuator. Also, the concept of the new actuator is proved by experimental measurements. At the last section of the thesis key aspects of the systems for further improvement of the actuator are proposed.

L’animation basée sur la physique peut générer des systèmes aux comportements complexes et réalistes. Malheureusement, contrôler de tels systèmes est une tâche ardue. Dans le cas de la simulation de fluide, le processus de contrôle est particulièrement complexe. Bien que de nombreuses méthodes et outils ont été mis au point pour simuler et faire le rendu de fluides, trop peu de méthodes offrent un contrôle efficace et intuitif sur une simulation de fluide. Étant donné que le coût associé au contrôle vient souvent s’additionner au coût de la simulation, appliquer un contrôle sur une simulation à plus haute résolution rallonge chaque itération du processus de création. Afin d’accélérer ce processus, l’édition peut se faire sur une simulation basse résolution moins coûteuse. Nous pouvons donc considérer que la création d’un fluide contrôlé peut se diviser en deux phases: une phase de contrôle durant laquelle un artiste modifie le comportement d’une simulation basse résolution, et une phase d’augmentation de détail durant laquelle une version haute résolution de cette simulation est générée. Cette thèse présente deux projets, chacun contribuant à l’état de l’art relié à chacune de ces deux phases. Dans un premier temps, on introduit un nouveau système de contrôle de liquide représenté par un modèle particulaire. À l’aide de ce système, un artiste peut sélectionner dans une base de données une parcelle de liquide animé précalculée. Cette parcelle peut ensuite être placée dans une simulation afin d’en modifier son comportement. À chaque pas de simulation, notre système utilise la liste de parcelles actives afin de reproduire localement la vision de l’artiste. Une interface graphique intuitive a été développée, inspirée par les logiciels de montage vidéo, et permettant à un utilisateur non expert de simplement éditer une simulation de liquide. Dans un second temps, une méthode d’augmentation de détail est décrite. Nous proposons d’ajouter une étape supplémentaire de suivi après l’étape de projection du champ de vitesse d’une simulation de fumée eulérienne classique. Durant cette étape, un champ de perturbations de vitesse non-divergent est calculé, résultant en une meilleure correspondance des densités à haute et à basse résolution. L’animation de fumée résultante reproduit fidèlement l’aspect grossier de la simulation d’entrée, tout en étant augmentée à l’aide de détails simulés. / Physics-based animation can generate dynamic systems of very complex and realistic behaviors. Unfortunately, controlling them is a daunting task. In particular, fluid simulation brings up particularly difficult problems to the control process. Although many methods and tools have been developed to convincingly simulate and render fluids, too few methods provide efficient and intuitive control over a simulation. Since control often comes with extra computations on top of the simulation cost, art-directing a high-resolution simulation leads to long iterations of the creative process. In order to shorten this process, editing could be performed on a faster, low-resolution model. Therefore, we can consider that the process of generating an art-directed fluid could be split into two stages: a control stage during which an artist modifies the behavior of a low-resolution simulation, and an upresolution stage during which a final high-resolution version of this simulation is driven. This thesis presents two projects, each one improving on the state of the art related to each of these two stages. First, we introduce a new particle-based liquid control system. Using this system, an artist selects patches of precomputed liquid animations from a database, and places them in a simulation to modify its behavior. At each simulation time step, our system uses these entities to control the simulation in order to reproduce the artist’s vision. An intuitive graphical user interface inspired by video editing tools has been developed, allowing a nontechnical user to simply edit a liquid animation. Second, a tracking solution for smoke upresolution is described. We propose to add an extra tracking step after the projection of a classical Eulerian smoke simulation. During this step, we solve for a divergence-free velocity perturbation field resulting in a better matching of the low-frequency density distribution between the low-resolution guide and the high-resolution simulation. The resulting smoke animation faithfully reproduces the coarse aspect of the low-resolution input, while being enhanced with simulated small-scale details.