SidA from Aspergillus fumigatus is an N-hydroxylating monooxygenase that catalyzes the committed step in siderophore biosynthesis. This gene is essential for virulence making it an excellent drug target. In order to design an inhibitor against SidA a greater understanding of the mechanism and structure is needed. We have determined the crystal structure of SidA in complex with NADP+, Ornithine, and FAD at 1.9 ? resolution. The crystal structure has provided insight into substrate and coenzyme selectivity as well as residues essential for catalysis. In particular, we have chosen to study the interactions of Arg 279, shown to interact with the 2'phosphate of the adenine moiety of NADP+ as well as the adenine ring itself. The mutation of this residue to alanine makes the enzyme have little to no selectivity between coenzymes NADPH and NADH which supports the importance of the ionic interaction between Arg279 and the 2'phosphate. Additionally, the mutant enzyme is significantly more uncoupled than WT enzyme with NADPH. We see that the interactions of the guanadinyl group of Arg279 and the adenine ring are also important because KM and Kd values for the mutant enzyme are shifted well above those of wild type with coenzyme NADH. The data is further supported by studies on the reductive and oxidative half reactions. We have also explored the allosteric effect of L-arginine. We provide evidence that an enzyme/coenzyme/L-arginine complex is formed which improves coupling, oxygen reactivity, and reduction in SidA; however more work is needed to fully understand the role of L-arginine as an allosteric effector. / Master of Science in Life Sciences

Staphylococcus aureus causes chronic mastitis in bovines that is difficult to treat with current therapeutics. The goal of this research is to provide information about and improve innate immune responses to infection. Infection can result in host cell apoptosis or programmed cell death. Many pathogens can inhibit apoptosis; thereby acquiring a replicative niche, a reprieve from immune responses, and an escape from treatments. We hypothesize that S. aureus inhibits apoptosis in dendritic cells (DC). To investigate our hypothesis, DC were infected with live S. aureus (LSA), γ-irradiated S. aureus (ISA), or Streptococcus agalactiae (Strep ag.) for 2 hours. Stimulations of DC included ultraviolet light (UV) and lipoteichoic acid (LTA). Results indicate that γ-irradiated S. aureus can inhibit UV-induced apoptosis by upregulating LTA. This research provides information about S. aureus infections, but further research is needed to improve responses to this type of infection. One way to improve innate immune responses to infection is by supplementing bovines with OmniGen-AF®, a probiotic that restores neutrophil function during immunosuppression. To determine the mechanism by which OmniGen-AF® functions, wildtype, MyD88 KO, and TLR4 KO mice were fed either normal chow or supplemented with OmniGen-AF® for two weeks. Mice were immunosuppressed with dexamethasone and challenged with LTA. LTA overcame immunosuppression in a TLR4-depenent manner regardless of supplementation with OmniGen-AF®. Overall this research supplies knowledge about S. aureus inhibition of apoptosis in DC and S. aureus LTA activation of PMN regardless of immunosuppression or supplementation with OmniGen-AF®. / Master of Science

Made available in DSpace on 2014-12-17T15:14:43Z (GMT). No. of bitstreams: 1 AndreSWTS_capa_ate_secao2.pdf: 3305591 bytes, checksum: 5f27842b5915ba4ade82c5d3c89c759b (MD5) Previous issue date: 2007-12-07 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The e?ect of ?nite size on the magnetic properties of ferromagnetic particles systems is a recurrent subject. One of the aspects wide investigated is the superparamagnetic limit where the temperature destroys the magnetic order of ferromagnetic small particles. Above the block temperature the thermal value of the magnetic moment of the particle vanishes, due to thermal ?uctuations. The value of the blocking temperature diminishes when the size of the particle is reduced, re?ecting the reduction of the anisotropy energy barrier between the uniform states along the uniaxial axis. The increasing demand for high density magnetic media has recently attracted great research interest in periodic arrangements of nanometric ferromagnetics particles, approach in the superparamagnetic limit. An interesting conjecture is the possibility of stabilization of the magnetic order of small ferromagnetic particles (F) by interface coupling with antiferromagnetic (AF) substrate. These F/AF systems may also help to elucidate some details of the e?ect of exchange bias, because the e?ect of interface roughness and the paper of domain walls, either in the substrate or the particle, are signi?cantly reduced. We investigate the magnetic phases of small ferromagnetic particles on a antiferromagnetic substrate. We use a self-consistent local ?eld method, incorporating the interface ?eld and the dipole interaction between the spins of the ferromagnetic particle. Our results indicate that increasing the area of the interface favors the formation of the uniform state. Howere above a critical height value appears a state non-uniform is formed where the spins of in the particle s free surface are rotated with respect to the interface spins direction. We discuss the impact of the competition between the dipolar and interface ?eld on the magnetic charge, that controls the ?eld of ?ux leakage of the particle, and on the format of the hysteresis curves. Our results indicate that the liquid magnetic charge is not a monotonically increasing function of the height of the particle. The exchange bias may display anomalous features, induced for the dipolar ?eld of the spins near the F/AF interface / O efeito de tamanho ?nito nas propriedades magn?ticas de sistemas de part?culas ferromagn?ticos ? um tema recorrente. Um dos aspectos largamente investigados ? o limite superparamagn?tico em que a temperatura desestabiliza a ordem magn?tica de part?culas ferromagn?ticas pequenas. Acima da temperatura de bloqueio o valor m?dio t?rmico do momento magn?tico da part?cula se torna nulo, devido a ?utua??es t?rmicas. A temperatura de bloqueio diminui quando o tamanho da part?cula ? reduzido, re?etindo a queda na barreira de energia de anisotropia entre os estados de magnetiza??o uniforme ao longo do eixo uniaxial. A demanda crescente por meios de grava??o magn?tica de alta densidade tem atualmente despertado grande interesse de pesquisa em arranjos peri?dicos de part?culas ferromagn?ticas de dimens?es nanom?tricas, beirando o limite superparamagn?tico. Uma conjectura interessante, levantada experimentalmente, se refere ? possibilidade de estabiliza??o da ordem magn?tica de part?culas ferromagn?ticos (F) via o acoplamento de interface com substratos antiferromagn?ticos (AF) com temperatura de N?el acima da temperatura ambiente. Esses sistemas se prestam igualmente para elucidar alguns detalhes do efeito de Exchange bias , dado que, o efeito de rugosidade de interface e o papel de paredes de dom?nio, seja no substrato ou na part?cula, s?o reduzidos. Investigamos as fases magn?ticas de uma pequena part?cula ferromagn?tica, com diversas geometrias e disposi??es de deposi??o sobre um substrato antiferromagn?tico. Usamos um m?todo de campo local auto-consistente, incorporando o campo de interface e a intera??o dipolar entre os spins da part?cula ferromagn?tica. Nossos resultados indicam que aumentando a ?rea da interface favorece a forma??o do estado uniforme. Por?m se a altura da part?cula ? superior a um valor cr?tico surge um estado n?o-uniforme em que os spins se orientam de modo a minimizar a carga magn?tica super?cial. Discutimos o impacto que a competi??o entre esses efeitos tem na carga magn?tica l?quida, que controla o campo de fuga da part?cula e no formato das curvas de histerese. Nossos resultados indicam que a carga l?quida n?o ? uma fun??o monot?nicamente crescente da altura da part?cula e que o deslocamento da histerese pode sofrer altera??es relevantes, induzidas pelo campo dipolar, fugindo do padr?o esperado normalmente em sistemas F/AF extensos

Relay-based cooperation promises significant gains in a wireless network as it provides an inde-pendent path between a source and a destination. Using simple single antenna nodes, it exploits the spatial diversity provided by the geographically separated nodes in a network to improve the robustness of the communication system against fading. Among the cooperative commu¬nication schemes, the amplify-and-forward (AF) relaying scheme is considered to be easy to implement since the relay does not need to decode its received signal. Instead, it just forwards to the destination the signal it receives from the source. We analyze the performance of fixed-gain AF relaying with imperfect channel knowledge that is acquired through an AF relay-specific training protocol. The analysis is challenging because the received signal at the destination contains the product (or cascade) of source-relay (SR) and relay-destination (RD) complex baseband channel gains, and additional products terms that arise due to imperfect estimation related errors. We focus on the time-efficient cascaded channel estimation (CCE) protocol to acquire the channel estimates at the destination. Using it, the destination can only estimate the product of SR and RD complex baseband channel gains, but not the two separately. Our analysis encompasses a single AF relay system and an opportunistic system with mul¬tiple AF relays, among which one is selected to forward its received signal to the destination, based on its SR and RD complex baseband channel gains. For a single relay system, we first de¬velop a novel SEP expression and a tight SEP upper bound. We then analyze the opportunistic multi-relay system, in which both selection and coherent demodulation use imperfect channel estimates. A distinctive aspect of our approach is the use of as few simplifying approximations as possible. It results in a new analysis that is accurate at signal-to-noise-ratios as low as 1 dB for single and multi-relay systems. Further, the training protocol is an integral part of the model and analysis. Using an insightful asymptotic analysis, we then present a simple, closed-form, nearly-optimal solution for allocation of energy between pilot and data symbols at the source and relay(s). Further, the optimal energy allocation between a source and a relay is characterized when both together operate under a sum energy constraint, as has often been assumed in the literature. In summary, the sum total of the results in this work provides a rigorous and accurate performance characterization and optimization of cascaded channel estimation for AF relaying.

Retinale Venenverschlüsse sind eine der häufigsten vaskulären Netzhauterkrankungen. Bei der Entstehung und dem Verlauf von venösen Gefäßverschlüssen im Auge spielen kardiovaskuläre Risikofaktoren eine entscheidende Rolle. Patienten mit einem retinalen Venenverschluss weisen vermehrt vaskuläre Risikofaktoren für arterielle Gefäßkrankheiten auf, weswegen es von hoher klinischer Relevanz ist, diese frühzeitig zu erkennen und zu behandeln. Bisher gibt es kein einheitliches Untersuchungsschema zur Ursachenabklärung eines retinalen Venenverschlusses. Ziel ist es, Empfehlungen einer zukünftigen Routinediagnostik für venöse Gefäßverschlüsse im Auge auszusprechen. In der FIND-AF-EYE-Studie wurde erstmals durch eine umfangreiche Diagnostik an insgesamt 101 Patienten mit retinalen Gefäßverschlüssen eine systematische Abklärung kardiovaskulärer Risikofaktoren kontrolliert durchgeführt. Die Diagnostik umfasste eine duplexsonographische Untersuchung der A. carotis, eine Echokardiographie, eine 24 h-Blutdruckmessung, ein 7 d-LZ-EKG und eine laborchemische Erhebung des Lipid- und Glukosestatus. Bei der Auswertung der 41 Patienten mit venösen Gefäßverschlüssen im Auge konnte wie auch in vergleichbaren Studien gezeigt werden, dass vor allem die arterielle Hypertonie, der Nikotinkonsum, die Hyperlipidämie und der Diabetes mellitus die wichtigsten kardiovaskulären Risikofaktoren darstellen. Zudem wurde durch die verlängerte elektrokardiographische Aufzeichnungsdauer über sieben Tage mehr als ein Drittel aller Patienten mit Herzrhythmusstörungen identifiziert. Anhand der Ergebnisse der vorliegenden Studie sind apparative Untersuchungen wie eine 24 h-Blutdruckmessung, eine Echokardiographie und ein 7-Tage-Langzeit-EKG unverzichtbar. Laborchemisch sollten ein Lipidstatus und ein Blutzuckerprofil routinemäßig erhoben werden. Zur Einschätzung des kardiovaskulären Risikos des Patienten erscheint eine Untersuchung der A. carotis sinnvoll. Um die Morbidität und die Mortalität zu senken bedarf es einer interdisziplinären Ursachenabklärung, welches die enge Zusammenarbeit zwischen Ophthalmologen und Internisten erfordert. Vergleicht man die FIND-AF-EYE-Studie mit der bereits publizierten FIND-AF-Studie litten die Patienten der FIND-AF-Studie signifikant häufiger an einer Karotisstenose. Zusammenfassend lässt sich sagen, dass akuten arteriellen Verschlüssen, wie beispielsweise einer zerebralen Ischämie, in den meisten Fällen thromboembolische Ereignisse zugrunde liegen. Kardiovaskuläre Risikofaktoren spielen aber auch bei venösen Gefäßverschlüssen im Auge eine wichtige Rolle. Hierbei führen sie zu arteriosklerotischen Veränderungen der eng benachbarten Zentralarterie. Durch die Kompression kommt es somit zur Thrombenbildung in der Zentralvene.

The magnetization processes of antiferromagnetically (AF) coupled Co/Pt multilayers on extended substrates and of Co/Pd multilayers deposited on arrays of 58 nm spheres are investigated via magnetic force microscopy at room temperature by imaging the domain configuration in magnetic fields. Adding AF exchange to such perpendicular anisotropy systems changes the typical energy balance that controls magnetic band domain formation, thus resulting in two competing reversal modes for the system. In the ferromagnetic (FM) dominated regime the magnetization forms FM band domains, vertically correlated. By applying a magnetic field, a transition from band to bubble domains is observed. In the AF-exchange dominated regime, by applying a field or varying the temperature it is possible to alter the magnetic correlation from horizontal (AF state) to vertical (FM state) via the formation of specific multidomain states, called metamagnetic domains. A theoretical model, developed for complex multilayers is applied to the experimentally studied multilayer architecture, showing a good agreement. Magnetic nanoparticles have attracted considerable interest in recent years due to possible applications in high density data storage technology. Requirements are a well defined and localized magnetic switching behavior and a large thermal stability in zero fields. The thermal stability of [Co/Pt]N multilayers with different numbers of repeats (N), deposited on nanospheres is studied by magnetic viscosity measurements. The magnetic activation volume, representing the effect of thermal activation on the switching process, is estimated. It is found that the activation volume is much smaller than the volume of the nanosphere and almost independent of the number of bilayers supporting an inhomogeneous magnetization reversal process.

Uppsatsen utforskar några omständigheter kring vilka de omfattande förändringarna i Stockholms centrala delar vid mitten av 1900-talet dokumenterats, i första hand genom fotografiska bilder. I de "minnesböcker" där dessa bilder står i förgrunden får "Klarakvarteren" i en viss mening stå som symbol för det moderna Stockholm i och med anläggandet av den nya centralstationen på 1870-talet, samt genom att utgöra den självklara platsen för otaliga tidningsredaktioner, hotell och kaféer. Som sinnebilden för det moderna stadslivet i Stockholm är "Klarakvarteren" förbundna med en annan viktig aspekt av moderniteten: den fotografiska bilden. "Klarakvarteren" finns idag, i spåren efter den omfattande omdaningen av stadskärnan, i allt väsentligt enbart kvar som minnesbilder i form av text och fotografier. Genom att undersöka en i sammanhanget central fotografisk bok, med en längre essä av Per Wästberg tillika fotografier av Lennart af Petersens, som i många år arbetat som fotograf för Stockholms stad, hoppas föreliggande uppsats kunna väcka frågor kring hur minnen, fotografier och tillvaron i den moderna staden kan sägas gå samman i dessa "minnesböcker" som publicerats under, liksom efter, dessa storskaliga arkitektoniska förändringar. / This essay explores some of the circumstances under which the extensive changes in central Stockholm in the mid 20th century were documented, primarily by means of photographic pictures. In a certain sense, "Klarakvarteren" stands as a symbol of  modernity, and in certain books featuring these documentary photographs "Klarakvarteren" has, as such, been epitomized as the centre of modern Stockholm following the construction of the new Central station in the 1870s, in addition to being the obvious location of numerous editorial offices and many hotels and cafés. As a symbol of modern city life in Stockholm, "Klarakvarteren" also relates to another key feature of modernity: the photographic image. Following the total reconstruction of the city centre, "Klarakvarteren" in this day essentially consists of memory images in the form of texts or photographs. In examining a central photographic book featuring an extensive essay by author Per Wästberg as well as pictures by Lennart af Petersens, long in service as photographer with the City of Stockholm, this essay hopes to uncover how certain questions of memory, photographic images and modern urban life are intertwined in respect to these "memory books" published during, as well as after, these large-scale architectural changes.

Les systèmes de communication FSO sont des candidats potentiels pour de solutions de transmission spatiale à large bande. C’est pourquoi la présente thèse s’inscrit dans une contribution d’une nouvelle architecture de réseau FSO dans le cas d’une liaison de communication entre un satellite géostationnaire et une station terrienne. Elle traite aussi de l’influence de l’angle zénithal sur la qualité de la liaison optique en raison de la variation de la scintillation due à la complexité de l’atmosphère. Nous avons établi un nouveau canal de communication tenant compte de la subdivision de l’atmosphère en deux grandes zones de turbulence. Pour améliorer la performance de la liaison, nous avons d’abord placé un relais AF optiques ente le satellite et la station terrienne, ensuite nous avons introduit un paramètre construit `a partir de valeurs : p et 1-p. Le paramètre p correspond au ratio de la distance entre la station terrienne et le relais sur la distance de 36 000 Km correspondant a` l’orbite GEO. Dans notre cas, le relais est placé a 1000 Km a l’exosphère, le paramètre p = 1/36 et enfin la technique de diversité spatiale est appliquée en réception. Les résultats de simulation ont confirmé que les architectures des systèmes proposés sont meilleures que les performances de liaisons optiques directes. / Free space optical systems are potential candidates of large band spatial transmission solutions. In this thesis, FSO network architecture in the case of geo- stationary satellite to earth communication link is investigated and the influence of zenith angle on the quality of the link has been evaluated. Because of the variation of scintillation due to the complexity of the atmosphere, the optical space to earth communication link channel model has been developped. In order to overcome the main limitations of the prop- agation, optical relays with low earth orbit satellites and spatial diversity on earth could improve the link performance. To improve the link performance, an aggregated simulation model turbulence has been built based on parameters ”p” and ”1-p” introduced in the combined model a↵ecting the considered channels. The parameter ” p ” corresponds to the ratio of the distance from the earth to the relay over the total distance of 36 000Km. In the case of 1000 Km for a relay in the exosphere, p = 1/36. Simulation results show that the proposed network system architecture has outperformed the direct link performance

Ett bokformgivningsprojekt som visar färg- och formteorierna i boken Thought Forms (1905) som ett tidigt konst- och designteoretiskt verk. Boken Thought Forms (1905) av Annie Besant and C. W. Leadbeater är en teosofisk bok som presenterar ”tankeformer” som visar hur tankar och känslor ser ut för den klärvoajanta. Boken tros ha inspirerat abstrakta konstnärer som till exempel Vasilij Kandinski och Hilma af Klint som båda var medlemmar i det teosofiska samfundet. Genom en serie på tre böcker presenterar jag färg- och formsystemen i Thought Forms som ett tidigt konst- och designteoretisk verk. Projektet är lika delar en undersökning av känslor och andliga idéers påverkan på formgivning som ett ut utforskande av bokformens påverkan på läsningen av ett innehåll. Projektet består av tre handgjorda böcker som presenterar bilderna, förgläran och formerna ur Thought Forms: Deconstructing Thought Forms: The Figures Deconstructing Thought Forms: The Colours  Deconstructing Thought Forms: The Shapes / A book design project that shows the theories of color and form in the book Thought Forms from 1905 as an early of art- and design theoretical work. The book Thought Forms by Annie Besant and C. W. Leadbeater is a theosophical book that shows "thought forms". Colourful shapes formed by thoughts and feelings, only visible for the clairvoyant. The book is believed to have inspired abstract artists such as Wassily Kandinsky and Hilma af Klint, who were both members of the Theosophical Society. Through a series of three books, I present the color and shape systems from Thought Forms as an early art and design theoretical work. This project is both an investigation of the influence of emotions and spiritual ideas on design as an exploration of the book designs effect on how we receive a content.    The result is a series of three books: Deconstructing Thought Forms: The Figures  Deconstructing Thought Forms: The Colors Deconstructing Thought Forms: The Shapes

The magnetization processes of antiferromagnetically (AF) coupled Co/Pt multilayers on extended substrates and of Co/Pd multilayers deposited on arrays of 58 nm spheres are investigated via magnetic force microscopy at room temperature by imaging the domain configuration in magnetic fields. Adding AF exchange to such perpendicular anisotropy systems changes the typical energy balance that controls magnetic band domain formation, thus resulting in two competing reversal modes for the system. In the ferromagnetic (FM) dominated regime the magnetization forms FM band domains, vertically correlated. By applying a magnetic field, a transition from band to bubble domains is observed. In the AF-exchange dominated regime, by applying a field or varying the temperature it is possible to alter the magnetic correlation from horizontal (AF state) to vertical (FM state) via the formation of specific multidomain states, called metamagnetic domains. A theoretical model, developed for complex multilayers is applied to the experimentally studied multilayer architecture, showing a good agreement. Magnetic nanoparticles have attracted considerable interest in recent years due to possible applications in high density data storage technology. Requirements are a well defined and localized magnetic switching behavior and a large thermal stability in zero fields. The thermal stability of [Co/Pt]N multilayers with different numbers of repeats (N), deposited on nanospheres is studied by magnetic viscosity measurements. The magnetic activation volume, representing the effect of thermal activation on the switching process, is estimated. It is found that the activation volume is much smaller than the volume of the nanosphere and almost independent of the number of bilayers supporting an inhomogeneous magnetization reversal process.