Tesi sul tema "Limitation du fer"

La fixation de N2, ou diazotrophie, est un processus biogéochimique majeur en raison de son apport en azote nouveau dans la couche de surface de l’océan. Cependant ses facteurs de contrôle restent mal connus. Le fer, dont les concentrations de surface sont faibles, est un élément potentiellement limitant de la fixation de N2 du fait du contenu en fer important de la nitrogénase. En raison de leur découverte récente, peu d’études ont été menées sur les cyanobactéries diazotrophes unicellulaires (UCYN) pouvant être responsables de ~50% de la fixation de N2 à l’échelle globale. Des expériences en culture ont permis de caractériser et quantifier pour la première fois la réponse d’une UCYN, Crocosphaera watsonii, face à la limitation en fer. En condition de limitation en fer, il a été observé une réduction de la croissance et des taux de fixation de N2 ainsi qu’une stratégie d’adaptation des cellules avec une diminution de leur volume. La stimulation de la croissance et de l’activité de C. watsonii cultivées en condition de limitation en fer suite à l’ajout d’une pluie saharienne artificielle a permis de mettre en évidence qu’une partie au moins du fer issu de poussières désertiques est biodisponible. En Atlantique subtropical Nord, où nous avons déterminé une forte contribution de la fixation de N2 à la production nouvelle, nous avons observé une limitation de la fixation de N2 et de la production primaire principalement par les phosphates et mis en évidence le rôle des métaux traces dans le contrôle de la fixation de N2. Un ajout de pluie saharienne a permis de stimuler systématiquement la fixation de N2 et la production primaire
Despite the biogeochemical importance of N2 fixation, which represents the largest source of newly-Fixed nitrogen to the open ocean, some uncertainties remain about its controlling factors. Iron (Fe) is widely suspected as a key controlling factor due to the high Fe content of the nitrogenase complex and to its low concentration in oceanic surface seawaters. N2 fixation rates associated with unicellular N2 fixing cyanobacteria (UCYN) were estimated to be ~50% of the total N2 fixation at global scale, but as they have been recently discovered few studies have been conducted on these organisms. We performed culture experiments in order to quantify for the first time the response of an UCYN, Crocosphaera watsonii, to Fe limitation. Reduction of ambient Fe concentration led to significant decreases in growth rate and N2 fixation rates per cell and we observed an adaptive strategy to Fe limitation with a cell volume reduction. Then, the enhancement of growth and activity of C. watsonii under Fe limitation condition after artificial Saharan rain addition highlighted that at least a part of the Fe released by the dust is bioavailable. In subtropical North Atlantic, an important contribution of N2 fixation to new production was observed and we showed that primary production and N2 fixation were globally P-Limited. We revealed that trace metals play a key role in controlling N2 fixation in this area. Saharan rain addition stimulated N2 fixation, presumably by supplying these nutrients. All these results contribute to our knowledge of the control of oceanic N2 fixation and provide new insight about interactions between Fe, nitrogen and carbon biogeochemical cycles

Le fer (Fe) est un élément essentiel de la croissance microbienne marine, mais est présent sous forme de trace dans les eaux de surface des océans. Chez les bactéries hétérotrophes, la limitation en Fe affecte particulièrement la production d'ATP et il a été démontré que les bactéries appliquent diverses stratégies pour faire face à la présence de limitation en Fe. Les outils génétiques nous ont permis de tester deux stratégies potentielles au sein de l'organisme modèle Photobacterium angustum S14. Le shunt glyoxylique, une voie métabolique trouvée dans les bactéries aérobies contournant plusieurs étapes de TCA, s’est révélée être régulée à la hausse sous une limitation en Fe et nous proposons que la dérivation du shunt glyoxylique réoriente le métabolisme cellulaire de la chaîne de transport d’électrons, augmentant de ce fait l'efficacité métabolique de la cellule soumise à la limitation en Fe. La protéorhodopsine, une pompe à protons activée par la lumière trouvée dans plusieurs bactéries hétérotrophes, peut atténuer le stress lié au Fe si le gradient de proton produit est couplé à l'ATP synthase. Nos résultats ont montré que la protéorhodopsine augmentait à mesure que les cellules approchaient de la phase stationnaire dans des conditions à la fois remplies de Fe et limitant en Fe, mais étaient absentes pendant la phase exponentielle. Les travaux futurs visant à élucider le rôle de la protéorhodopsine, et en particulier en ce qui concerne la limitation du Fe, devraient donc être axés sur la phase stationnaire d'une cellule bactérienne. Les résultats de ce manuscrit de thèse ont contribué à la littérature actuelle sur la polyvalence des bactéries marines hétérotrophes pour faire face à la limitation en Fe et le rôle de la protéorhodopsine et du shunt glyoxylique dans l'environnement marin
Iron (Fe) is an essential element for marine microbial growth but is present in trace amounts in the surface waters of the ocean. In heterotrophic bacteria, Fe-limitation particularly impacts ATP production and have been shown to implement various strategies to cope in the presence of Fe-limitation. Genetic tools enabled us to test two potential strategies within the model organism Photobacterium angustum S14. The glyoxylate shunt, a metabolic pathway found in aerobic bacteria bypassing several steps within the classic tricarboxylic acid (TCA) was shown to be upregulated under Fe-limitation and we propose that the glyoxylate shunt was able to redirect a cell’s metabolism away from Fe-limiting steps within the electron transport, thereby increasing the metabolic efficiency of the cell under Fe-limitation. Proteorhodopsin, a light activated proton pump found in several heterotrophic bacteria, could alleviate Fe-stress if the produced proton gradient is coupled to ATP synthase. Our results showed that proteorhodopsin is upregulated as cells approached the stationary phase under both Fe-replete and Fe-limiting conditions but was absent during the exponential phase. Future work in elucidating the role of proteorhodopsin, and particularly under Fe-limitation, should therefore focus on the stationary phase of a bacterial cell. The results from this thesis manuscript contributed to a culminating body of work surrounding the versatility of marine heterotrophic bacteria in coping with Fe-limitation and is an appropriate addition to the literature surrounding the role of proteorhodopsin and the glyoxylate shunt within the marine environment

La fixation de N2, ou diazotrophie, est un processus biogéochimique majeur en raison de son apport en azote nouveau dans la couche de surface de l’océan. Cependant ses facteurs de contrôle restent mal connus. Le fer, dont les concentrations de surface sont faibles, est un élément potentiellement limitant de la fixation de N2 du fait du contenu en fer important de la nitrogénase. En raison de leur découverte récente, peu d’études ont été menées sur les cyanobactéries diazotrophes unicellulaires (UCYN) pouvant être responsables de ~50% de la fixation de N2 à l’échelle globale. Des expériences en culture ont permis de caractériser et quantifier pour la première fois la réponse d’une UCYN, Crocosphaera watsonii, face à la limitation en fer. En condition de limitation en fer, il a été observé une réduction de la croissance et des taux de fixation de N2 ainsi qu’une stratégie d’adaptation des cellules avec une diminution de leur volume. La stimulation de la croissance et de l’activité de C. watsonii cultivées en condition de limitation en fer suite à l’ajout d’une pluie saharienne artificielle a permis de mettre en évidence qu’une partie au moins du fer issu de poussières désertiques est biodisponible. En Atlantique subtropical Nord, où nous avons déterminé une forte contribution de la fixation de N2 à la production nouvelle, nous avons observé une limitation de la fixation de N2 et de la production primaire principalement par les phosphates et mis en évidence le rôle des métaux traces dans le contrôle de la fixation de N2. Un ajout de pluie saharienne a permis de stimuler systématiquement la fixation de N2 et la production primaire
Despite the biogeochemical importance of N2 fixation, which represents the largest source of newly-Fixed nitrogen to the open ocean, some uncertainties remain about its controlling factors. Iron (Fe) is widely suspected as a key controlling factor due to the high Fe content of the nitrogenase complex and to its low concentration in oceanic surface seawaters. N2 fixation rates associated with unicellular N2 fixing cyanobacteria (UCYN) were estimated to be ~50% of the total N2 fixation at global scale, but as they have been recently discovered few studies have been conducted on these organisms. We performed culture experiments in order to quantify for the first time the response of an UCYN, Crocosphaera watsonii, to Fe limitation. Reduction of ambient Fe concentration led to significant decreases in growth rate and N2 fixation rates per cell and we observed an adaptive strategy to Fe limitation with a cell volume reduction. Then, the enhancement of growth and activity of C. watsonii under Fe limitation condition after artificial Saharan rain addition highlighted that at least a part of the Fe released by the dust is bioavailable. In subtropical North Atlantic, an important contribution of N2 fixation to new production was observed and we showed that primary production and N2 fixation were globally P-Limited. We revealed that trace metals play a key role in controlling N2 fixation in this area. Saharan rain addition stimulated N2 fixation, presumably by supplying these nutrients. All these results contribute to our knowledge of the control of oceanic N2 fixation and provide new insight about interactions between Fe, nitrogen and carbon biogeochemical cycles

Il existe encore des incertitudes importantes concernant le cycle biogéochimique du fer, sa nature et la quantification de ses sources. Ce fer dissous (dFe) est considéré comme étant la forme la plus biodisponible ce qui a induit la sous-évaluation du rôle du fer particulaire (pFe) comme une source potentielle de dFe. Pourtant, la remise en suspension des sédiments libère davantage de pFe que de dFe. Dans ce contexte, ma thèse remet en question la vision traditionnelle du rôle du fer particulaire inorganique sédimentaire (pFeinorg) et propose la première modélisation de ce dernier comme source externe de dFe. Le modèle numérique PISCES a donc été adapté pour tenir compte d’un flux supplémentaire de fer en s’appuyant sur une climatologie de la dynamique à partir de la configuration NEMOPISCES globale à 2 degrés de résolution. Les simulations mettent en exergue la sensibilité de la biomasse phytoplanctonique à la forme de fer provenant des sédiments ; les limitations en macronutriments et celles en fer sont considérablement modifiées, ainsi que les gradients côte–large de chlorophylle. Le transport plus efficace du fer en tant que pFeinorg permet d’atteindre des régions éloignées de sa source. Son accumulation et sa dissolution dans les zones de convergences induisent via downwelling l’enrichissement de la surbsurface ; à ceci s’ajoute le processus de chute de la particule. Cependant, ces processus demeurent peu étudiés. Les tests de sensibilité ont montré que le gain (absence de chute) ou la perte (chute rapide) en fer dans l’océan, ou encore la prépondérance du pFe sur le dFe seraient modulés par le taux de dissolution. En revanche, la distribution de la chlorophylle est mieux représentée dans la mesure où les processus qui régissent la distribution du PFeinorg et du dFe qui en dérive sont, de concert, pris en compte. Une manière de mieux représenter les répercussions du fer sur les cycles biogéochimiques marins, serait de mieux contraindre les processus liés au PFeinorg
There are still substantial uncertainties in the iron biogeochemical cycle, including those related to the nature and magnitude of its external sources.Dissolved iron (dFe) is considered to be the most bioavailable form, which led to the underestimation of the role of particulate iron (pFe) as a potential source of dFe. Yet sediment resuspension releases more pFe than dFe. In this context, my thesis challenge the traditional view of the role of sedimentary inorganic particulate iron (pFeinorg) and proposes the first modeling of pFeinorg as a new external source of dFe. For this purpose, the PISCES numerical model has been adapted to take into account an additional iron flux based on a climatology of dynamics from the global NEMO-PISCES configuration at 2 degrees of resolution. Simulations highlight the sensitivity of phytoplankton biomass to the sedimentderived form of iron ; macronutrient limitations and iron limitations are considerably modified, as are coastal – open ocean chlorophyll gradients.The iron is more efficiently transported as a pFeinorg, allowing it to reach regions far from its source. Its accumulation and dissolution in the zones convergence zones would allow via downwelling to enrich the subsurface; in addition to this, the process of particle sinking. However, few studies have been conducted on these processes. Sensitivity tests have shown that the gain (no sinking velocity) or loss (relatively fast sinking velocity) of iron in the ocean or the preponderance of particulate iron over dissolved iron would be modulated by the dissolution rate. However the distribution of chlorophyll is better represented to the extent that the processes governing the distribution of pFeinorg and the dFe derived from it are jointly taken into account. One way to better represent the impact of iron on marine biogeochemical cycles would be to better constrain the processes associated with pFeinorg

Il est désormais établi que la disponibilité en fer (Fe) contrôle environ 50% de la production primaire des océans du monde. Cependant, les processus régissant l’intensité des puits et des sources du Fe ainsi que la prédominance relative de ces sources au sein des divers bassins océaniques, sont elles-mêmes peu contraintes. Par ailleurs, une fois entrées dans le système océanique, la disponibilité et l’accessibilité des diverses formes de Fe pour les organismes marins restent incertaines. La réactivité du Fe au sein de l’environnement marin dépend de son état d’oxydoréduction et de complexation. Le fer dissous (DFe) est souvent considéré comme la fraction la plus biodisponible pour le phytoplancton et les ligands organiques du Fe augmentent vraisemblablement le temps de résidence du Fe et permettent des concentrations de DFe bien plus élevées que sa solubilité inorganique ne le permet dans l’eau de mer (10 pmol L-1).Dans ce contexte et s’inscrivant dans le programme international GEOTRACES, cette thèse a pour but principal d’implémenter notre savoir du cycle biogéochimique du Fe dans l’océan et ses interactions avec la structure des communautés phytoplanctoniques, en particulier afin de mieux contraindre les formes biodisponibles du Fe. Ainsi, les objectifs de cette thèse reposent sur trois questions scientifiques : 1) Quelles sont les distributions, sources, et puits de Fe ? 2) Quel est le lien entre la structure des communautés phytoplanctoniques et les concentrations en DFe ? 3) Comment la spéciation organique du DFe impacte ses concentrations et sa biodisponibilité ? Ces trois questions ont été explorées sur de deux zones d’études contrastées : l’océan Nord Atlantique (GEOVIDE, GA01 GEOTRACES voyage, PIs G. Sarthou and P. Lherminier) étant occasionnellement et saisonnièrement appauvri en Fe et l’océan Austral (HEOBI, GIpr05 GEOTRACES voyage, PIs A. Bowie, T. Trull, Z. Chase) l’étant de manière permanente
It is now recognized that iron (Fe) availability dictates the efficiency of the global biological carbon pump such that any perturbation of Fe sources will lead to changes in the carbon cycles with consequences on both other major nutrient cycles and the climate system, controlling about 50% of the worldwide ocean primary production. However, the underlying processes themselves that affect the pathways releasing and trapping Fe, and the relative predominance of Fe sources among the different ocean basins are still poorly constrained. More importantly, the extent to which both the chemical and the physical speciation of Fe are available and accessible for marine organisms, once it enters the ocean, remains uncertain. The reactivity of Fe within the marine environment will depend on its redox and complexation state, with DFe generally considered the most bioavailable form for phytoplankton and Fe-binding organic ligands likely increasing the residence time of Fe that enables enhanced DFe concentrations way above its inorganic solubility in seawater (c.a. 10 pmol L-1).In this context and as part of the international GEOTRACES program, this thesis aims at improving our knowledge on Fe biogeochemical cycle in the ocean and its interactions with the phytoplankton community structure to better constrain the bioavailable forms of Fe. The objectives of this thesis revolve around three scientific questions: 1) What are the distributions, sources, and sinks of dissolved iron? 2) What is the link between the phytoplankton community structure and dissolved iron concentrations? 3) How the organic speciation of dissolved iron affects its concentrations and bioavailability for the phytoplankton community? These three questions were investigated through two contrasted areas: the North Atlantic Ocean (GEOVIDE, GA01 GEOTRACES voyage, PIs G. Sarthou and P. Lherminier) and the Southern Ocean (HEOBI, GIpr05 GEOTRACES voyage, PIs A. Bowie, T. Trull, Z. Chase) the former being occasionally seasonally depleted in Fe, the latter permanently

Le rôle clef du fer dans le cycle biogéochimique du carbone et de l’azote dans l’océan a été mis en évidence au cours de la dernière décennie. Une des découvertes majeures récentes en océanographie biologique est la limitation de la croissance du phytoplancton par la disponibilité en fer dans au moins 40% de l’océan mondial. Or, la chimie de cet élément dans l’océan est particulièrement complexe et la forme sous laquelle il est disponible pour le phytoplancton reste encore mal connue. Plusieurs mécanismes sont utilisés par le phytoplancton marin pour améliorer la solubilité du fer en eau de mer et parvenir à absorber les quantités suffisantes en fer nécessaires à leur survie. Un de ces mécanismes implique la production de radicaux superoxyde en milieu extracellulaire, ce qui accroît la bio-disponibilité du fer en eau de mer en réduisant la forme Fe(III) sous forme Fe(II), plus bio-disponible aux cellules de phytoplancton. Les objectifs principaux de ce travail étaient de i) développer une méthode appropriée pour détecter la production de superoxyde en milieu extracellular par n’importe quelle cellule de phytoplancton marin, et ii) examiner la relation entre la production extracellulaire de superoxyde et l’absorption du fer par la cyanobactérie Trichodesmium erythraeum IMS101. Une méthode de détection du superoxyde a été développée, qui utilise du red-CLA ou du MCLA, deux sondes chimiluminescentes spécifiques à la détection du superoxyde, qui ont donné des résultats fiables, même sur de très faibles quantités d’échantillons. En effet, comparée aux autres méthodes employées, la détection de la production du superoxyde par microplaques permet de réduire le volume d’échantillon par 10, et de réduire le temps d’analyse de tréplicats d’un échantillon, d’un blanc et de trois standards à 10 minutes. De plus, cette méthode présente une large gamme de travail avec une limite de détection de 0,076 pmol/s, ce qui lui confère un grand avantage pour le travail sur le phytoplancton marin. Les taux de production de superoxyde en milieu extracellulaire par la cyanobatérie Trichodesmium erythraeum ont été mesurés en condition de laboratoire et allaient de 0,93 à 16,21 pmol/trichome/h. La limitation en fer des cellules de Trichodesmium résultat en une augmentation de ce taux de production, qui a été multiplié par un facteur 2,9 entre les cellules non limitées et les cellules limitées en fer. Il a aussi été montré que la production de superoxyde suivait un rythme diurne avec une forte augmentation du taux de production en milieu du cycle « jour», spécialement marqué pour les cultures maintenues en milieu pauvre en fer. Les taux de production extracellulaire de superoxyde et d’absorption du fer par Trichodesmium ont été mesurés simultanément sur des cultures pré-limitées ou non limitées en fer. Les taux d’absorption étaient 10 fois plus élevés pour les cultures non limitées, sauf lorsqu’un composé réducteur (acide ascorbique) était ajouté. Dans ce cas, les taux d’absorption des deux cultures étaient similaires. De plus, les deux cultures ont montré une plus grande aptitude à absorber le fer lié à des ligands faibles comme le citrate. Dans l’ensemble, les résultats ont montré une relation entre la production de superoxyde et l’absorption de fer par Trichodesmium, mais aucune influence directe entre ces deux processus n’a pu être démontrée. La méthode de détection du superoxyde par microplaque a été utilisée lors de campagnes sur la Grande Barrière de corail en Australie. L’analyse de deux blooms de Trichodesmium a montré de forts taux de production de superoxyde, en cohérence avec les analyses effectuées au laboratoire. De plus, l’utilisation de cette méthode (entre autres) a permis de démontrer une accumulation d’espèces Fe(II) en concentrations biologiquement significatives, quand la concentration en superoxyde dans l’eau de mer était inférieure à 1 nM. Par contre, lorsque cette concentration se trouvait supérieure à 1nM, la plupart des espèces réduites (Fe(II)) étaient réoxidées, ce qui résultait en un fort taux de production de peroxyde d’hydrogène du à la dismutation du superoxyde. Dans l’ensemble, cette étude a permis le développement d’une méthode de détection de la production de superoxyde par le phytoplancton marin en milieu extracellulaire qui peut être utilisée au laboratoire ou en conditions d’étude sur le terrain. Nous avons aussi démontré que les cellules de Trichodesmium erythraeum IMS101 produisent de grandes quantités de superoxyde, en particulier lorsqu’elles sont limitées en fer. L’étude des taux d’absorption du fer par ces même cellules a démontré une forte relation entre ce processus et la production de superoxyde par les cellules: ces résultats sont en accord avec l’hypothèse que le modèle d’absorption du fer par le phytoplancton marin «Fe’» serait fortement influencé par ce type d’organisme capable de modifier l’équilibre redox du milieu présent à la surface des cellules
It is hypothesised that, under iron limitation, phytoplankton cells develop biochemical mechanisms to increase their iron uptake efficiency with one of these mechanisms involving the production of superoxide in the extracellular environment that increases the bioavailability of iron in seawater by reducing Fe(III) to the more soluble Fe(II). The main objectives of this work were 1) to develop an appropriate method to detect extracellular production of superoxide by marine phytoplankton, and 2) to examine the relationship between extracellular production of superoxide and iron acquisition by Trichodesmium erythraeum. A method to measure superoxyde production is described using red-CLA and MCLA probes, yielding considerable improvement for analysis compared to other available methods. Extracellular superoxide production and iron uptake rates were measured simultaneously on iron replete and iron deplete Trichodesmium erythraeum IMS 101 laboratory cultures : iron starvation leads to a 2. 9-fold increase in superoxide production rate and 10-fold decrease in the iron uptake rate (except when a reducing compound was added) compared to iron replete cultures. Extracellular superoxide production shows a pronounced circadian rythm in iron deplete cultures, but less so in iron replete cultures. Overall, no direct impact of extracellular superoxide production by Trichodesmium is observed, but both processes are shown to be related. Both iron deplete and iron replete cultures demonstrate greater ability to uptake iron bound to weaker iron-binding ligands such as citrate. Application of the method to field studies in the Great Barrier Reef lagoon showed an accumulation of biologically significant concentrations of reduced trace metals including Fe(II) when the concentration of superoxide was lower than 1 nM. When the concentration of superoxide was higher than 1 nM, most of the reduced species were oxidised resulting in high rates of hudrogen peroxide production rates, consistent with laboratory studies. Overall, this thesis permitted the development of a method to detect superoxide production rates by marine phytoplankton cells that could be used routinely in field studies. The observations are in accord with the conclusion that fit the ongoing hypothesis that the extablished Fe' uptake model for phytoplankton would be strongly influenced by such organisms that are able to modify the redox equilibrium of the solution at their cells surface

Urininkontinens är ett problem alla kan drabbas av. Det innebär att personen läcker urin eller kissar på sig. Det ses som ett vanligt folkhälsoproblem i hela världen och det förekommer mest hos kvinnor. Det påverkar kvinnorna och hämmar dem i det dagliga livet. Hämningen grundar sig i rädsla och oro för att läcka samt lukta urin. Kvinnorna med urininkontinens upplever att ämnet är tabubelagt samt nedtystat och associeras med skamkänslor. De känner en daglig påverkan av urininkontinensen och den planerade livsplanen spricker med en överhängande känsla av maktlöshet samt frustration. De försöker hitta olika sätt att acceptera sina symtom men flertalet av kvinnorna ser symtomen som en oundviklig del av livet. Ett problem som kommer med stigande ålder eller en åkomma efter förlossning. Kvinnor som är äldre än femtio år har lättare att acceptera sin urininkontinens än de som är trettio år. De okontrollerade symtomen ger kvinnorna en känsla av förlorad kroppskontroll och sårbarhet. Detta kan leda till dåligt självförtroende och depression. Kvinnorna begränsas i sociala sammanhang och de hindras att utföra fysiska aktiviteter till följd av nervositet att läcka samt lukta urin. Detta upplevs som en förlust i vardagen. Kvinnorna uttrycker även en försämring i deras sexuella relationer och de känner en svårighet att vara spontana i sexuella aktiviteter. Mindre feminitet och en känsla av att inte vara fräsch uttrycks också av kvinnorna. Till följd av detta känner de en sämre självkänsla. Olika strategier används för att fungera i det dagliga livet. Vilket kan innebära att de anpassar sin klädsel och förbereder sig med extra inkontinensskydd för att dölja fläckar från läckage. De tar även alltid reda på tillgång till toaletter i offentliga miljöer. Ett annat problem dessa kvinnor upplever är ett ignorant bemötande av vårdpersonal och brist på kunskap om urininkontinens. Kvinnorna önskar en mer förstående attityd och bättre kommunikation i vården för att få möjlighet till rätt behandling. Vården har mycket att förbättra i mötet med dessa kvinnor både professionellt samt kunskapsmässigt och i öppenheten till ämnet. Det går inte att förvänta sig att kvinnorna tar sina egna besvär på allvar när inte vårdpersonalen gör det.
Background: Urinary incontinence denotes an involuntary leakage from the bladder which can affect women of all ages, but leakage problems are often more common with rising age. It is a common issue, however there is a large unrecorded number of women who do not seek medical attention for their urinary incontinence. Urinary incontinence is very costly for the society because of the medical and social disability it causes the affected. Aim: To illuminate the experiences of women living with urinary incontinence Method: A literary study was done where nine scientific articles were examined and analyzed according to a five step model. Results: The women experienced their urinary incontinence as taboo and shameful. The issue was too intimate and private and therefore unnatural to talk about. Their leakage lead to fear and nervousness which made them end up in a vulnerable situation. This affected them on several emotional levels both psychosocial, psychological and physical. The women experienced an ignorance and a nonchalant attitude from their care providers which caused an hesitancy in their search of healthcare. They experienced that their bodies were unreliable which lead to a reduced spontaneity and restrictions in life. Conclusion: Urinary incontinence is not solely an issue with leaking urine, it is affecting the women's lives as a whole on many levels. The hindrance that the urinary incontinence caused the women on a daily basis made them feel a sense of loss and affected their joy and zest of life. It requires an improvement of healthcare praxis in order to meet these women in a professional and trustworthy manner.

Sverige har en lagstadgad anmälningsplikt som är obligatorisk för alla som i sitt arbete kommer i kontakt med barn. Lagen är tydlig med att alla misstänka missförhållanden skall anmälas. Forskning visar att anmälningsplikten inte alltid fungerar och att det bara är en liten del av de barn som riskerar att fara illa som kommer till socialtjänstens kännedom. Vidare forskning visar att få anmälningar kommer från hälso- och sjukvården. Syftet var att beskriva sjuksköterskans erfarenheter i mötet med barn som far illa eller riskerar att fara illa. Litteraturstudien genomfördes med kvalitativ design och sökningar har gjorts i CINAHL, MEDLINE och PsycINFO. Åtta artiklar ansågs relevanta. Under analysen framkom tre teman: en emotionell utmaning, att känna sig begränsad och att våga agera. Resultatet visar att sjuksköterskan blir berörd i mötet med barn som far illa. Vidare beskriver sjuksköterskan osäkerhet, bristande kunskap och brister i organisationen. Sjuksköterskans professionella trygghet beskrivs utifrån kunskap och förvärvad erfarenhet. Det är angeläget att sjuksköterskans yrkeskompetens upprätthålls samt att det finns stöd att tillgå för att utveckla omvårdnaden kring barn som far illa.
In Sweden, everyone who comes in contact with children through their work has a statutory obligation to report child abuse. The law clearly states that any suspected child abuse must be reported. Research shows that the reporting does not always work. Only a small proportion of the children who might be victims of abuse come to the knowledge of Social Services. Further research shows that few notifications come from individuals within the health care system. The aim of this literature review was to describe nurses’ experiences of encounters with chil-dren who are victims of abuse or who are at risk of being abused. A qualitative design was used. CINAHL, MEDLINE and PsycINFO were used to select the articles, eight of which met the selection criteria. During the analysis, three themes emerged: An Emotional Challenge, Feeling Limited, and Daring to Act. The results show that the nurses are emotionally affected by their contact with abused children. The nurses also describe feelings of insecurity, a lack of knowledge, and organizational deficiencies. The nurses’ professional security is described as stemming from knowledge and experience. It is very important that the nurses’ professional competence is maintained and that there is support available in order to develop the care of abused children.

Fed-batch processes are the industrial norm for the production of recombinant proteins such as monoclonal antibodies (MAb) from Chinese hamster ovary (CHO) cells. Optimization of such processes is an important objective of industry process development groups. Amino acid availability is a key factor that is controlled to achieve the desired product yield and quality. In order to improve fed-batch productivity, the individual effects of limiting the three depleted amino acids were investigated for three antibody expressing CHO cell lines. Specifically, the effects of limiting glutamine, asparagine and cysteine on the cell growth, metabolism, antibody productivity and quality were investigated. Cysteine limitation was found to be detrimental to both the cell proliferation and the productivity for all three CHO cell lines. In contrast, asparagine limitation had no significant effect on either their growth or productivity. Glutamine limitation resulted in a reduction in growth but not in cell specific productivity, again for all three cell lines. Neither glutamine nor asparagine limitation significantly affected the MAb glycosylation. However, the fucosylation ratio was reduced in the absence of cysteine. It was confirmed that cysteine is a rate limiting factor for the productivity and growth of the three CHO cell lines. Replenishing cysteine after 1 day of the limitation allowed the cells to regain their growth and productivity; however, this was not observed after 2 days of cysteine limitation. Under cysteine limitation there was increased oxidative damage to the mitochondria, possibly caused by reduced synthesis of co-enzyme A which is essential for functionality of the TCA cycle. Finally, a fed-batch protocol was developed to improve the MAb productivity of CHO-DXB11 cells and the results were compared to the results with a commercial feed. Although use of the commercial feed resulted in higher maximum cell and final MAb concentrations, maintaining the levels of cysteine yielded cell specific production rates that were comparable to the commercial feed culture. Overall, the results of this study showed that amino acid limitations have varied effects on the performance of CHO cell cultures, such that it is important to focus process development efforts on the critical amino acids.
Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate

Research shows that children often confuse facial expressions of fear with surprise and disgust with anger. According to the perceptual-attentional limitations hypothesis, facial expressions are confused because they share action units (Camras, 1980; Wiggers, 1982). Experiment 1 tested this hypothesis for the confusion between fear and surprise and Experiment 2 for the confusion between disgust and anger. Eye movements were monitored in both experiments. In experiment 1, the results showed that children were more accurate when two distinctive action units were presented than when the brow lowerer was the only distinctive action unit differentiating between fear and surprise. Furthermore, the results showed that participants spent more time fixating on the mouth than the eyebrows. They made more saccades when the only distinctive cue was in the eyebrows. In experiment 2, participants identified the emotion as anger when the mouth was open, and disgust when the mouth was closed, spending more time on the mouth when the mouth was open. These findings suggest that facial expressions are confused, not only because of the amount of visual similarities they share, but also because children do not allocate their attention to facial regions equally; they tend to focus on the mouth.

Objective: The increased survival rate amongst female breast cancer survivors creates a need for an understanding of chronic disability after surgery. The objective of this study is to explore the association between impairments (e.g., pain, mobility, strength) and the personality trait, fear of physical activity, and chronic daily activity limitations for women who had their surgery at least six months prior to the study. Hypothesis: The study hypothesis is that women with high levels of physical impairments and the personality trait of fear of physical activity will also have higher levels of daily activity limitations six months or more after their breast cancer surgery. Design: A cross-sectional design. Outcome Measures: Disabilities of Shoulder, Arm, and Hand (DASH), Visual Analog Scale for Pain (VAS-Pain), Fear Avoidance Belief Questionnaire – Physical Activity (FABQ-PA), and objective measures of shoulder mobility and strength. Participants: Women who had been diagnosed and undergone surgery for breast cancer, stage 1-3. They must have had their surgery at least six months previously and have completed chemotherapy or radiation therapy. Both English- and French-speaking women from the Ottawa-Gatineau region were eligible. Results: Data from twelve women were analysed with a mean age of 58.0±8.9 years and post-operative time of 4.0± 2.8 years. DASH scores mean was 12.2 ± 11.38. VAS-Pain (rs=0.819; p<.001), FABQ-Physical Activity (rs=0.746; p<.005) were significantly associated with DASH score, whereas non-significant associations were found with supraspinatus strength (rs = 0.182; p < .572) or infraspinatus strength (rs=0.553; p<.062) using the Spearman Rho test. Also, no significant relationships were observed between range of motion (hand-behind-back; p =.366; hand-behind-head; p=.390) and DASH scores using a Kruskal-Wallis test. Conclusion: The results of this exploratory study suggest that the reported daily activity limitations of women who have had breast cancer surgery may be related to the participant pain perception and/or fear of physical activity.

I present new optical and infrared photometry for a statistically complete sample of seven sources selected at 1.1 mm. Comparing their photometric redshifts with redshifts from previous 850 μm selected surveys indicates that 1.1 mm selected surveys may be better at finding high redshift sources. I also perform a banded Ve/Va analysis on the sample, and find no evidence for a redshift cutoff in the space density of sources. However, the sample size is very small. I perform the same analysis on a statistically complete sample of 38 galaxies selected at 850 μm. I find a evidence for a drop off in space density of sources beyond between z∼1-2 as well as for the existence of two differently evolving sub-populations separated in luminosity. I present a sample of SPIRE sources, selected at 250 μm, with a set of previously collected ancillary photometry and either spectroscopic or photometric redshifts. I find that only ∼1/4 of the sources at redshifts z∼1 show evidence of undergoing a major merger. I find evidence to support a downsizing model of galaxy evolution, where the most massive galaxies form first. I find some correlation with star formation rate and the gas mass of a galaxy, therefore the drop in cosmic star formation rate since z = 1 may be caused by a coinciding drop in the average gas mass of galaxies over this era. Finally, I discuss the possibility of using imaging spectrometers to break through the confusion limit. Taking the SAFARI instrument as a test case I find that I can uniquely identify galaxies by their redshift, determined via an automated method. I find that this method works for galaxies with fluxes as much as ten times below the traditional continuum confusion limit. I also find that I can uniquely identify spectrally confused sources

L’objectif de notre travail était d’étudier les bascules métaboliques chez Yarrowia li-polytica d’un métabolisme purement oxydatif vers l’accumulation de lipides puis à l’excretion d’acide citrique.Le développement d’un procédé D-stat et d’un mode de conduite fed-batch nous a permis, dans un premier temps, de quantifier les ratios N/C caractéristiques pour chacune des bascules étudiées. Nos résultats montrent que les ratios rN/rC critiques aux bascules métaboliques sont de 0,085 molN.Cmol-1 et de 0,018-0,022 molN.Cmol-1 pour l’accumulation de lipides et production de citrate, respectivement.L’analyse systémique des cultures réalisées nous a permis de mettre en évidence des mécanismes de co-régulation de certaines enzymes du métabolisme lipidique ainsi qu’une prépondérance de mécanismes post-transcriptionnels dans l’établissement des bascules étudiées.Enfin, l’utilisation de souches génétiquement modifiées au niveau de l’ATP citrate lyase, la malate déshydrogénase et de la glycérol-3-phosphate déshydogénase a permis d’évaluer l’impact de ces enzymes sur le métabolisme lipidique
This thesis aimed at studying the metabolic shifts in Yarrowia lipolytica from the pure oxidative metabolism to lipid accumulation and citric acid excretion.The development of a D-stat culture and of a monitoring fed-batch strategy allowed us to determine the N/C ratio characteristic for each of metabolic shifts. rN/rC ratio were determined equal to 0,085 molN.Cmol-1 and 0,018-0,022 molN.Cmol-1 for the lipid accumu-lation and the citric acid production, respectively.Systemic analysis of the cultivations showed coregulation phenomena among some enzymes of the lipidic metabolism and post-transcriptional modifications in the onset of the metabolic shifts.Finally, the impact of enzymes (ATP citrate lyase, malate dehydrogenase and gly-cérol-3-phosphate dehydrogenase) on the lipidic metabolism was evaluated through systemic analysis of 3 genetically modified strains

Rhodotorula glutinis (Rhodosporidium toruloides) est une levure oléagineuse dont les fortes capacités d’accumulation lipidique à partir de glucose comme source carbonée ont fait de la souche un modèle d’étude. La capacité de cette levure à utiliser le glycérol ou le xylose en simple ou co-substrat avec le glucose est toutefois encore peu explorée. De l’analyse des travaux antérieurs il a été possible de dégager les verrous scientifiques qui nécessitent une amélioration des connaissances du comportement physiologique de cette levure pour la conversion des substrats cités. Des stratégies expérimentales adaptées à la quantification rationnelle des dynamiques de Rhodotorula glutinis en conditions de croissance et accumulation lipidique à partir de xylose et de glycérol en simple ou co-substrats avec le glucose ont été développées. Des résultats originaux ont été obtenus dont :- la mise en évidence des potentialités de co-consommation des substrats xylose et glucose ou glycérol et glucose sans accumulation de substrat ni production de métabolites en conditions contrôlées des flux de substrats. Il a été possible de déterminer la vitesse spécifique maximale de consommation du carbone de la souche qui diminue lorsque la part de xylose ou glycérol augmente dans l’apport de carbone total.- la quantification de la dynamique de croissance sur xylose et glycérol pur en terme de taux de croissance et de rendement : sur xylose µmax= 0.034h-1 et RS/X= 0.28 Cmolx.Cmolxylose-1; sur glycérol µmax=0.04h-1 RS/X=0.31Cmolx.Cmolglycérol-1.- la quantification des vitesses spécifiques et rendements de production de lipides à partir de xylose ou de glycérol en simple ou co-substrat avec du glucose : 20%xylose-80%glucose : qp=0.065CmolTAG.Cmolbiomasse.h-1, RS/P=0.3CmoleTAG.Cmolesubstrat-1 100%xylose : qp=0.035065CmolTAG.Cmolbiomasse.h-1, RS/P=0.31CmoleTAG.Cmolesubstrat-1, 25% glycérol-75%glucose : qp=0.07065CmolTAG.Cmolbiomasse.h-1, RS/P=0.25CmoleTAG.Cmolesubstrat-1 , 100% glycérol : qp=0.03065CmolTAG.Cmolbiomasse.h-1, RS/P= 0.29CmoleTAG.Cmolesubstrat-1.- L’impact de la nature des substrats sur le profil lipidique de Rhodotorula glutinis demeure léger : il apparait que le xylose entraîne une surproduction de C16:0 et C18:3et le glycérol favorise l’accumulation de C18:0
Rhodotorula glutinis (Rhodosporidium toruloides) is an oleaginous yeast. The micro-organism has demonstrated high lipid accumulation when utilizing glucose as a substrate, and has become a model for oil production. Glycerol and xylose are interesting as substrates for production of oil from renewable resources, but the capacity of R. glutinis to utilize glycerol and xylose as substrates has not been characterized well. Fermentation strategies were designed to quantify growth and lipid accumulation dynamics of R. glutinis when utilizing glycerol and xylose - either as pure substrates, or as co-substrates with glucose. Several original results have been found, including: - Co-consumption of xylose or glycerol along with glucose was observed, without carbon substrate accumulation or byproduct formation, when the carbon feed rate was carefully controlled. The specific carbon consumption rate decreases when the proportion of the second substrate (glycerol or xylose) increases in the feed, relative to glucose. - Growth capacities were characterized on pure xylose and pure glycerol in terms of growth rate and carbon yields: on xylose μmax= 0.034h-1 and RS/X= 0.28 Cmolx.Cmolxylose-1; on glycerol μmax=0.04h-1 RS/X=0.31Cmolx.Cmolglycerol-1. - specific production rate of lipid production and substrate to product carbon conversion yields from xylose or glycerol as single or cosubstrate with glucose were determinated: 20%xylose-80%glucose : qp=0.065CmolTAG.Cmolbiomasse.h-1, RS/P=0.3CmoleTAG.Cmolesubstrat-1 100%xylose : qp=0.035065CmolTAG.Cmolbiomasse.h-1, RS/P=0.31CmoleTAG.Cmolesubstrat-1, 25% glycerol-75%glucose : qp=0.07065CmolTAG.Cmolbiomasse.h-1, RS/P=0.25CmoleTAG.Cmolesubstrat-1 , 100% glycerol : qp=0.03065CmolTAG.Cmolbiomasse.h-1, RS/P= 0.29CmoleTAG.Cmolesubstrat-1. - Substrate diversification slightly impacts Rhodotorula glutinis´s lipid profile: xylose leads to an overproduction of C16:0 and C18:3 and glycerol increases C18:0 accumulation

Les acides gras polyinsatures (agpi) presentent un interet indeniable dans differents secteurs d'activite economique et leur production par voie microbiologique presente l'avantage de la maitrise du spectre de ces produits. La caracterisation cinetique et stchiometrique de la croissance et de la synthese des acides gras a ete effectuee chez rhodotorula glutinis. L'influence d'une carence en azote et en quelques autres elements nutritifs (phosphore, zinc et fer) sur la cinetique de l'accumulation lipidique a ete quantifiee en cultures discontinues. La synthese des agpi est directement couplee a la croissance, ce qui explique l'appauvrissement en agpi du spectre des acides gras lors de l'accumulation lipidique. Differentes conditions d'environnement physico-chimique (ph, temperature, pression osmotique) ne modifient pas la vitesse specifique de synthese des agpi, mais affectent la croissance et la formation des acides gras satures; il en resulte un enrichissement du contenu intracellulaire en agpi. Ces conditions optimales ont ete transposees a la conduite de culture en mode fed-batch a forte concentration en cellules (jusqu'a 150 g/l). La mise en uvre de ce type de cultures a necessite la mise au point de logiciels gerant l'apport en substrat selon differentes possibilites. En rendant possible la determination en temps reel de l'etat du systeme (taux specifique de croissance et rendement de conversion), ils permettent la fiabilisation des cultures a concentrations elevees en cellules et la maximisation des productivites en acides gras et agpi

L’accumulation de lipides chez une espèce levurienne Yarrowia lipolytica souche sauvage a été caractérisée par l’analyse dynamique et systémique des différents états métaboliques identifiés lors des cultures sous conditions environnementales parfaitement maitrisées, à hautes densités cellulaires selon deux stratégies bien distinctes. En premier lieu sur substrat osidique avec le phosphore comme élément inducteur de l’accumulation de lipides, stratégie originale pour déclencher l’accumulation de lipides chez cette souche. Et deuxièmement sur co-susbtrats glucose et oléate et sans aucune limitation nutritionnelle.Ces stratégies de conduites ont permis de dégager les points suivants :- La limitation phosphore déclenche une accumulation en lipides mais aussi en polysaccharides de réserves mobilisables mais non transitoire contrairement à la limitation azote.- La teneur en phosphore de la biomasse catalytique est très variable. De ce fait, le taux de croissance de la biomasse catalytique n’est pas contrôlable par le débit en phosphore.- Le phosphore joue un rôle dans la régulation de l’entrée de glucose dans la cellule, et permet d’éviter la production de citrate lorsque les voies de production de biomasse et de lipides sont en débordement sur une large gamme de rapport C/P (de 0 à 8000 Cmole.mole-1).- La capacité maximale d’accumulation en réserves carbonées chez Y. lipolytica wT est identique quelle que soit la méthode d’accumulation (limitation azote, limitation phosphore, co-substrats glucose / oléate) et est égale à 0,5 Cmole/CmoleX-1. Il existe donc un phénomène de régulation de la levure encore inconnu et limitant l’accumulation en réserves carbonées chez cette souche.Ces résultats ont permis d’identifier des points clés dans l’accumulation en réserves carbonées de cette espèce levurienne et de proposer un mode de conduite original faisant l’objet d’un dépôt de brevet
Lipid accumulation by the yeast Yarrowia lipolytica wT was characterized by dynamic and systemic analysis of different metabolic states in a microbial culture under fully controlled environmental conditions with high cell concentration and under two different strategies:Glucose as the substrate and phosphorus limitation as an inducer of lipid accumulation, an original strategy for lipid accumulation in Y. lipolytica wT.A co-substrate strategy with glucose and oleic acid and without any nutritional limitation.These strategies allowed showing the following points:- Phosphorus limitation triggers a lipid accumulation and a non-transient accumulation of reserve polysaccharide that can be consumed by biomass when necessary, contrary to nitrogen limitation- Phosphorus rate in catalytic biomass shows great variations. Catalytic growth rate cannot be governed by phosphorus input. - Phosphorus has a role in regulating cellular glucose uptake and allows avoiding citric acid production due to overflow of carbon input over a large range of C/P ratios (0 to 8000 Cmol.mol-1)- Maximum capacity of reserve carbon accumulation in Y. lipolytica wT is similar for any culture strategy tested (under nitrogen limitation, phosphorus limitation or with glucose and oleic acid co-substrates) and is equal to 0,5 Cmol/CmolX-1. There is an unknown phenomenon of carbon regulation limiting reserve carbon accumulation in Y. lipolytica wT. Results allowed identifying key points in reserve carbon accumulation in this particular yeast strain and suggesting an original process, claim of a patent

Polyhydroxyalkanoates (PHA) are a family of biodegradable polyesters naturally synthesised by some bacteria and archaea. PHA have high industrial value as bioplastics for packaging and biomedical applications. However, their broader use is hindered by high production costs and uncontrolled variation of polymer properties. The extreme halophile Haloferax mediterranei shows bioprocess advantages that can be exploited for the low cost production of the PHA copolymer Poly(3-hydroxbutyrate-co-3-hydroxyvalterate) (PHBV). The focus of this thesis is to identify process variables responsible for the uncontrolled variation of PHA properties in order to progress towards the robust production of PHBV using H. mediterranei. The outcome of the investigation is a novel cultivation strategy for the reliable synthesis of PHBV copolymers with controlled composition and microstructure showing minor differences in material characteristics. Initially, growth kinetics and PHBV synthesis were characterised under nitrogen-excess and nitrogen-limiting conditions in ammonium and for the first time, nitrate. The nitrogen source and concentration influenced PHBV accumulation and variations in polymer composition were observed with ammonium, highlighting the importance of the control of cultivation conditions. Volatile fatty acids (VFA) were found to be a more direct approach to determine PHBV composition and for the first time were used as substrates in H. mediterranei cultures. When the cells were grown in C4:0/C5:0 mixtures, the 3HV fraction in the PHBV was proportional to the percentage of C5:0 in the feed mixture, allowing the synthesis of copolymers with a predefined composition ranging from pure PHB to pure PHV. The cultivation strategy proved effective for the synthesis of HV rich PHBV, which is not easily obtained due to the 3HV precursor toxicity. The polymer microstructure was controlled using different feeding strategies: co-feeding generated random copolymers, while sequential feeding created block and blend copolymers. The synthesis of block copolymers is of interest because the materials show enhanced yield strength and mechanical strength, making such materials more suitable for commodity uses. Bespoke random, block, and blend copolymers with 0−100 mol% 3HV were synthesized and their thermal and mechanical properties studied. Lastly, high temperature cultivation and several surfactants were tested to enhance the production of bespoke PHBV from VFA. PHBV productivity and accumulation was greatly improved in a fed-batch bioreactor fermentation at 37°C with Tween-80 and the maximum PHBV content 58.9% was obtained. The polymers from shake-flasks and from bioreactors showed minor variations in their material properties, demonstrating the scalability and the robustness of the process developed. Further understanding of the different process variables affecting polymer synthesis and composition was gained in this thesis. It is now possible to produce PHBV with controllable composition, microstructure and minor differences in material characteristics. The novel and robust production strategy developed address the bioprocess challenge of minimising the uncontrolled variation of polymer characteristics that is currently hindering the wider use of PHA hence allowing the production of high quality polymers for commodity goods, packaging and biomedical applications.

This thesis is an engineering design of an intelligent fast-charger for lead-acid accumulators. It contains calculations of each component. The switching power supply is the mainstay of the charger that makes the charger portable, lightweight and small. The Intelligent fast-charger for lead-acid accumulators charges the accumulator by method of constant voltage with current limitation of 0,5A, 5A, 10A, 50A. 50A current is used in winter during starting of a car, when the battery can´t provide sufficient current. There are three LEDs placed on the front side of the charger reflecting status of the device. The device comprises safety protection for the charger, supply network and battery.

La messa in sicurezza, miglioramento e adeguamento sismico del patrimonio edilizio esistente costituiscono da sempre uno dei settori più importanti dell’ingegneria civile. Ad oggi molte sono le tecnologie utilizzate per il miglioramento del livello di sicurezza sismico ma poche sono versatili e di facile realizzazione, impedendo spesso la fruizione del fabbricato. Per far fronte a tali esigenze nasce il progetto regionale “TimeSafe”, sinonimo di “Tecnologie integrate ed innovative a limitato impatto ed invasività per il miglioramento sismico di edifici senza interruzione d’uso”. All’interno del progetto TimeSafe si sviluppano nuove tecnologie, tra loro integrate e a bassa invasività, che consentono la realizzazione per fasi di un rinforzo esterno con lo scopo di aumentare sia il livello di sicurezza sismico della struttura sia altre prestazioni come ad esempio quella energetica. Fondamentale importanza è stata data all’ottenere un basso impatto e alla personalizzazione del sistema in modo da garantire il suo impiego nella maggior parte dei contesti edilizi. Lo scopo del presente elaborato di tesi riguarda la modellazione numerica di dettaglio di un singolo modulo rappresentativo della struttura, avendo come obiettivo la previsione del reale comportamento del rinforzo e fungere da supporto alle imminenti prove di laboratorio. In particolare lo studio verterà dapprima sulla validazione dei due software Midas FEA e Midas FEA NX, per poi passare allo studio del singolo modulo di rinforzo. Si passerà quindi alla realizzazione di modelli semplificati e di dettaglio attraverso i quali si andranno a definire il comportamento del rinforzo e la quantità di armatura da considerare nell’elemento parete. Concludendo, al fine di considerare l’applicabilità di tale rinforzo in zone sismiche differenti, si sono eseguite delle analisi di sensibilità variando la sezione dei pilastri e la quantità di armatura in essi inserita, calcolati attraverso una valutazione parametrica.

L’accumulation d’acylglycérols par des espèces levuriennes induite par la limitation de l’élément azote a été caractérisée par l’analyse dynamique et systémique des différents états métaboliques identifiés lors de cultures sous conditions environnementales parfaitement maîtrisées, à hautes densités cellulaires. La mise en place d’un procédé de culture original en mode fed-batch a permis de dégager différents points majeurs : - la limitation en azote déclenche une accumulation transitoire de polysaccharides de réserve mobilisables avant l’induction de la synthèse d’acyl-CoA et de l’accumulation lipidique - pour les cultures de Yarrowia lipolytica, le développement d’un régulateur type ‘PID’ contrôlant l’apport de substrat basé sur le rapport (conduite brevetée) a permis de maintenir une dynamique d’accumulation lipidique optimale sur substrat osidique sans production concomitante d’acide citrique - pour Y. Lipolytica, l’utilisation d’une alimentation contrôlée en co-substrat glucose/glycérol permet d’atteindre des performances en termes de rendement et de productivité lipidique inégalées (0,37glip. GX-1, 70gX. L-1 en 75h) - les potentialités de stockage des acylglycérols sont étroitement dépendantes de la teneur mais également du profil d’insaturation des acides gras libres accumulés. La synergie entre génie microbiologique et génie génétique a permis, sur des cultures contrôlées de souches mutantes démonstratives, une approche intégrative des études macro et microcinétiques et des réponses transcriptomiques
Acylglycerols accumulation by yeast species induced by a nitrogen limitation was characterized by the dynamic and systemic analysis of the different metabolic states in microbial culture under fully controlled environmental conditions with high cell concentrations. The setting up of an original process of a fed-batch mode culture allowed identifying several major points: - Nitrogen limitation triggers a transient accumulation of reserve polysaccharides before induction of the acyl-CoA synthesis and lipid accumulation - For the cultures of Yarrowia lipolytica, the development of a PID-like control regulating the substrate flow based on the ratio (patent) kept an optimal lipid accumulation with osidic substrate without concomitant citric acid production - For Y. Lipolytica, the use of controlled flow in co-substrate glucose / glycerol culture achieved unmatched performances of yield and productivity (0,37glip. GX-1, 70gX. L-1 in 75h) - The potentialities of acylglycerols storage are closely dependent on the content and also on the profile of accumulated free fatty acids. The synergy between microbial engineering and genetic engineering made possible, with controlled culture demonstrative mutant species, an integrative approach of macro and microkinetic and transcriptomic responses

Extracellular neuroelectronic interfacing has important applications in the fields of neural prosthetics, biological computation and whole-cell biosensing for drug screening and toxin detection. While the field of neuroelectronic interfacing holds great promise, the recording of high-fidelity signals from extracellular devices has long suffered from the problem of low signal-to-noise ratios and changes in signal shapes due to the presence of highly dispersive dielectric medium in the neuron-microelectrode cleft. This has made it difficult to correlate the extracellularly recorded signals with the intracellular signals recorded using conventional patch-clamp electrophysiology. For bringing about an improvement in the signal-to-noise ratio of the signals recorded on the extracellular microelectrodes and to explore strategies for engineering the neuron-electrode interface there exists a need to model, simulate and characterize the cell-sensor interface to better understand the mechanism of signal transduction across the interface. Efforts to date for modeling the neuron-electrode interface have primarily focused on the use of point or area contact linear equivalent circuit models for a description of the interface with an assumption of passive linearity for the dynamics of the interfacial medium in the cell-electrode cleft. In this dissertation, results are presented from a nonlinear dynamic characterization of the neuroelectronic junction based on Volterra-Wiener modeling which showed that the process of signal transduction at the interface may have nonlinear contributions from the interfacial medium. An optimization based study of linear equivalent circuit models for representing signals recorded at the neuron-electrode interface subsequently proved conclusively that the process of signal transduction across the interface is indeed nonlinear. Following this a theoretical framework for the extraction of the complex nonlinear material parameters of the interfacial medium like the dielectric permittivity, conductivity and diffusivity tensors based on dynamic nonlinear Volterra-Wiener modeling was developed. Within this framework, the use of Gaussian bandlimited white noise for nonlinear impedance spectroscopy was shown to offer considerable advantages over the use of sinusoidal inputs for nonlinear harmonic analysis currently employed in impedance characterization of nonlinear electrochemical systems. Signal transduction at the neuron-microelectrode interface is mediated by the interfacial medium confined to a thin cleft with thickness on the scale of 20-110 nm giving rise to Knudsen numbers (ratio of mean free path to characteristic system length) in the range of 0.015 and 0.003 for ionic electrodiffusion. At these Knudsen numbers, the continuum assumptions made in the use of Poisson-Nernst-Planck system of equations for modeling ionic electrodiffusion are not valid. Therefore, a lattice Boltzmann method (LBM) based multiphysics solver suitable for modeling ionic electrodiffusion at the mesoscale neuron-microelectrode interface was developed. Additionally, a molecular speed dependent relaxation time was proposed for use in the lattice Boltzmann equation. Such a relaxation time holds promise for enhancing the numerical stability of lattice Boltzmann algorithms as it helped recover a physically correct description of microscopic phenomena related to particle collisions governed by their local density on the lattice. Next, using this multiphysics solver simulations were carried out for the charge relaxation dynamics of an electrolytic nanocapacitor with the intention of ultimately employing it for a simulation of the capacitive coupling between the neuron and the planar microelectrode on a microelectrode array (MEA). Simulations of the charge relaxation dynamics for a step potential applied at t = 0 to the capacitor electrodes were carried out for varying conditions of electric double layer (EDL) overlap, solvent viscosity, electrode spacing and ratio of cation to anion diffusivity. For a large EDL overlap, an anomalous plasma-like collective behavior of oscillating ions at a frequency much lower than the plasma frequency of the electrolyte was observed and as such it appears to be purely an effect of nanoscale confinement. Results from these simulations are then discussed in the context of the dynamics of the interfacial medium in the neuron-microelectrode cleft. In conclusion, a synergistic approach to engineering the neuron-microelectrode interface is outlined through a use of the nonlinear dynamic modeling, simulation and characterization tools developed as part of this dissertation research.
Ph.D.
Doctorate
Physics
Sciences
Physics

碩士
國立交通大學
電子物理系所
99
We successfully set up a high resolution far-field optical microscope, which can break through the optical diffraction limit, observe the non-fluorescence, and non-destroy the sample. In addition, the far-field optical microscope use the wavelength 473 nm to be the probing source with objective (NA=0.8), but it can observe the sample structure with 150 nm now, and the image resolution also achieved 10 nm. In the thesis, we implement it with a sample which is aluminum coated on indium tin oxide (ITO), and our theory had been proved by the testing sample.

Streszczenie Naturalne, niezaburzone antropogenicznie torfowiska pełnią niezwykle istotne funkcje. Są to, jedne z największych globalnych magazynów węgla, a w skali zlewni stanowią ważne miejsce retencji pierwiastków biogennych. Typowe dla torfowisk stałe wysokie uwodnienie oraz wycofywanie z obiegu pierwiastków biogennych wywołują w zbiorowisku roślinnym stresy anoksji oraz niskiej żyzności. Czynniki te ograniczają produkcję pierwotną i zwiększają szanse przetrwana na torfowiskach gatunków roślin słabych konkurencyjnie, często zagrożonych. Równocześnie torfowiska należą dziś do ekosystemów najszybciej degradujących się za sprawą działalności człowieka. W wyniku osuszenia powierzchniowe warstwy torfu ulegają mineralizacji, co powoduje emisję węgla do atmosfery oraz eutrofizację wód powierzchniowych. Ponadto na skutek zaniku czynników stresowych silnie konkurencyjne gatunki wypierają słabsze gatunki wyspecjalizowane. Aby ograniczyć negatywne skutki degradacji torfowisk rozpoczęto realizację projektów restytucji przyrodniczej tych ekosystemów. Początkowo metodą stosowaną w tych zabiegach było podniesienie poziomu wody poprzez zablokowanie rowów odwadniających. Metodę tą krytykowano jednak za jej negatywny wpływ na efekt cieplarniany (okresowe znaczne zwiększanie emisji metanu) oraz z powodu wzrostu żyzności (następującego równocześnie ze zwiększeniem uwilgotnienia), który uniemożliwia odtworzenie populacji rzadkich gatunków torfowiskowych. Drugą rzadziej stosowaną w restytucji torfowisk niskich metodą jest usuwanie wierzchniej, zdegradowanej warstwy torfu. Skuteczność tej metody w odtwarzaniu zbiorowisk roślinnych typowych dla torfowisk niskich została dobrze udokumentowana. Jednak do dziś nie wiadomo, jak metoda ta wpływa na relatywną dostępność poszczególnych pierwiastków biogennych, co może mieć duże znaczenie dla rozwoju fitocenoz. Co więcej, wiedza o wpływie tej metody na odtworzenie usług ekosystemowych torfowisk, takich jak wpływ na bilans gazów cieplarnianych czy obieg pierwiastków w zlewni, jest skąpa i oparta na pośrednim wnioskowaniu. Celem niniejszej rozprawy doktorskiej była ocena skuteczności restytucji torfowiska niskiego metodą usuwania zdegradowanej warstwy gleby w zakresie jej wpływu na: (1) warunki wzrostu roślin; (2) przywrócenie usług ekosystemowych związanych z obiegiem pierwiastków; (3) efekt cieplarniany, oraz porównanie tej metody z metodą powtórnego nawodnienia zdegradowanego torfowiska. Terenem badań było torfowisko Bagno Całowanie, na którym realizowany był projekt restytucji przyrodniczej, obejmujący m. in. usunięcie warstwy zdegradowanego torfu z powierzchni ok. 2 ha. Badania prowadziłem na tym obszarze oraz na zlokalizowanych wokół niego powierzchniach kontrolnych (zdegradowane, przesuszone partie torfowiska), referencyjnych (refugia roślinności nawiązującej do mechowisk zlokalizowane w obszarach dawnego wydobycia torfu) oraz poletkach eksperymentalnych, na których imitowano restytucję metodą powtórnego nawodnienia. Uzyskane przeze mnie wyniki wskazują, że metoda usuwania warstwy zdegradowanego torfu, w odróżnieniu od metody powtórnego nawodnienia zdegradowanego torfowiska, pozwala ograniczyć stężenia pierwiastków biogennych w roztworze glebowym oraz nie wywołuje zwiększenia emisji metanu. Z drugiej strony okazało się, że zastosowanie tej metody nie doprowadziło do odtworzenia warunków siedliskowych charakteryzujących się zasobnością w kationy metali zbliżoną do ekosystemów referencyjnych. Ponadto, względna dostępność fosforu w stosunku do azotu nie została ograniczona w stopniu wystarczającym, by odtworzyć warunki, w których produkcja pierwotna byłaby limitowana niedoborem tego pierwiastka (co sprzyjałoby zagrożonym gatunkom roślin). Ponadto, gdy w analizie wpływu na efekt cieplarniany uwzględniłem także efekt mineralizacji usuniętej zdegradowanej warstwy torfu, metoda usuwania warstwy zdegradowanej okazała się mniej korzystna dla klimatu (wskutek emisji dwutlenku węgla do atmosfery) niż metoda powtórnego nawodnienia. Pomimo wykazanych w pracy wad usuwania warstwy zdegradowanego torfu, ta metoda może zostać uznana za bardziej efektywną pod względem odtwarzania usług ekosystemowych oraz warunków występowania słabych konkurencyjnie gatunków roślin od powtórnego nawodnienia w ogólnym porównaniu obydwu metod. Ograniczenie stężeń azotanów i fosforanów sprzyja odtworzeniu niskoproduktywnych ekosystemów torfowiskowych. Ponadto w następstwie restytucji ograniczony zostaje ładunek azotu trafiający do zlewni, w której znajduje się torfowisko, a ilość dopływającego do niej fosforu pozostaje bez zmian. Problem wpływu dwutlenku węgla z mineralizującego się, usuniętego zdegradowanego torfu, na efekt cieplarniany może zaś zostać rozwiązany, jeśli torf ten zostanie wykorzystany w rolnictwie, leśnictwie lub ogrodnictwie jako substytut torfu wydobytego z niezaburzonych hydrologicznie torfowisk. W ten sposób emisje gazów cieplarnianych wywołane przez działania restytucji zostaną skompensowane przez ograniczenie emisji na innym obszarze.