In treatment of cancer using high energetic radiation the problem arises how to irradiate the tumor without damaging the healthy tissue in the immediate vicinity. In order to do this, intensity modulated radiation therapy (IMRT) is used. In this thesis, the general goal is to modulate the homogeneous radiation field delivered by an external accelerator using a multileaf collimator in comparison with beam modifying devices. In order to generate intensity modulated fields in a static mode with multileaf collimators, the heuristic algorithm of Galvin, Chen and Smith is used. This method aims at finding a segmentation with a small number of segments, taking account of mechanical constraints such as leaves can move only in one direction, on one row, the right and left leaves cannot overlap (Interleaf Collision) and also every element between the leaf and the side of the collimator to which the leaf is connected is also covered (no holes in leaves). During the implementation of the algorithm, the initial intensity matrix with the desired radiation rates is inserted and using essential transformations, a positive combination of special matrices, segments, corresponding to fixed positions of multileaf collimator are obtained. All calculations end with the superposition of segments which leads to the creation of the 3-D matrix that will be used to irradiate the tumor. The algorithm is implemented in C++. The calculations are fast and the procedure is user friendly. The model is implemented for the case of protection the spinal cord while treating a tumor in the neck area. Furthermore, dose distributions obtained with this model and beam modifying devices in the neck area were compared. / Κατά τη θεραπεία του καρκίνου με χρήση υψηλής ενέργειας ακτινοβολίας, πρόβλημα αποτελεί ο περιορισμός της ακτινοβολίας στον όγκο στόχο και ο περιορισμός της συμμετοχής του υγιούς ιστού, της γειτονικής περιοχής, στο ελάχιστο. Προκειμένου να επιλυθεί το πρόβλημα αυτό χρησιμοποιείται ακτινοθεραπεία με πεδία ακτινοβολίας διαμορφωμένης έντασης (Ιntensity Μodulated Radiαtion Therapy – IMRT), με τη βοήθεια των κατευθυντήρων πολλαπλών φύλλων (Multileaf Collimators- MLC). Στόχος της συγκεκριμένης διπλωματικής εργασίας είναι η διαμόρφωση του ομοιογενούς πεδίου ακτινοβολίας, που διανέμεται μέσω του γραμμικού επιταχυντή χρησιμοποιώντας κατευθυντήρα πολλαπλών φύλλων και η σύγκριση των αποτελεσμάτων της προσομοίωσης με τις συσκευές διαμόρφωσης δέσμης (Beam Modifying Devices). Προκειμένου να παραχθούν τα διαμορφωμένης έντασης πεδία ακτινοβολίας, σε στατική μορφή, χρησιμοποιήθηκε ο αλγόριθμος των Galvin, Chen και Smith. H μέθοδος αποσκοπεί στην τμηματοποίηση του πίνακα με τα επιθυμητά ποσοστά ακτινοβολίας σε έναν μικρό αριθμό τμημάτων “segments”, λαμβάνοντας υπόψιν μηχανικούς περιορισμούς. (i) Τα φύλλα δύναται να κινηθούν μόνο κατά μήκος μιας διεύθυνσης, (ii) σε μια γραμμή, το αριστερό και το δεξί φύλλο δεν μπορούν να επικαλυφτούν (Interleaf Collision) και (iii) κάθε στοιχείο μεταξύ του φύλλου και της πλευράς του διαμορφωτή, με την οποία είναι συνδεδεμένο, είναι πάντα καλυμμένο (Νo holes in leaves). Κατά την υλοποίηση του αλγορίθμου, εισάγεται ο αρχικός πίνακας με τα επιθυμητά ποσοστά ακτινοβολίας και με τη χρήσης κατάλληλων μετασχηματισμών, προκύπτει ένας συνδυασμός από ειδικούς πίνακες (segments), οι οποίοι αντιστοιχούν σε θέσεις των κατευθυντήρων πολλαπλών φύλλων και θα χρησιμοποιηθούν για την ακτινοβόληση του όγκου. Ο αλγόριθμος υλοποιήθηκε σε C++. Οι υπολογισμοί είναι γρήγοροι και η διεργασία είναι φιλική προς το χρήστη. Το μοντέλο υλοποιήθηκε για την περίπτωση προστασίας της σπονδυλικής στήλης κατά τη θεραπεία όγκου στην περιοχή του λαιμού. Τέλος, οι κατανομές δόσεις που προέκυψαν με την προαναφερθέν μοντέλο συγκρίθηκαν με αυτές των συσκευών διαμόρφωσης δέσμης.

In this study, we investigated the molecular characteristics of hydrates which were synthesized from gas mixtures containing the two isomers of butane, or the pentane isomers neopentane and isopentane, in excess methane. Thereto various techniques, including Raman spectroscopy, powder and single crystal X-ray diffraction and 13C NMR spectroscopy were employed. It turned out that shape and conformation of the guest molecule and hydrate structure both influence each other. In case of the mixed butane hydrate it could be confirmed that n-butane is enclathrated in its gauche conformation. This was verified by Raman spectroscopy, single crystal X-ray diffraction and calculated data. While isopentane is known as a structure H former, our results from powder X-ray diffraction, 13C NMR and ab initio calculations show that it can be also incorporated into structure II when the hydrate is formed from a neopentane/isopentane/methane gas mixture.

Lakštinėse spausdinimo mašinose spausdinant spalvotus atvaizdus svarbu mašinos atskirose sekcijose atspaudų sutapimą išlaikyti šimtųjų milimetro dalių tikslumu. Be to, spausdinamų atvaizdų geometrinis nesutapimas abiejose lapo pusėse neturi viršyti 0,1 mm. Viena iš pagrindinių nesutapimo priežaščių yra mechaninio krumpliaratinio perdavimo mechanizmo iš vienos sekcijos į kitą sukamieji virpesiai, kuriuos sukelia krumpliaračių paklaidos ir pasipriešinimo momentų pokyčiai tarp ofsetinių ir forminių cilindrų. Darbe analiziniu – kompiuteriniu būdu nagrinėjama šių virpesių įtaka lapo perdavimo tikslumui. Konkrečiam tyrimui pasirinkta „Heidelberg“ spausdinimo mašina GTO 52, tačiau darbe taikoma tyrimo metodika tinka ir kitoms mašinoms. Sudarytas elektros pavara valdomo lapų perdavimo mechanizmo dinaminis modelis su 16 laisvės laipsnių. Sistemos matematinis modelis (virpesių lygtys ir struktūrinė schema) sudarytas kompiuterizuotu būdu MATLAB/SIMULINK programų terpėje, kurioje atliktas sistemoje vykstančių dinaminių procesų modeliavimas. Pavaroje kylančios paklaidos apibūdinamos sukamųjų virpesių amplitudinėmis – dažninėmis charakteristikomis. Nagrinėjama šių charakteristikų pobūdžio, rezonansinių virpesių ir jų dažnių įtaka lapo perdavimo paklaidos dydžiui. / It is important in printing machines to maintain very high print quality (hundredths of a millimeter) in printing colorful prints. Also mismatches of prints in both sides of sheet must not exceed 0,1 millimeter. One of the reasons of mismatching is mechanical gear transfers mechanisms, from one printing unit to another, rotational oscillations, which are generated by gear errors and resistance moment changes between offset and print cylinder. These oscillations influence to sheet transfer accuracy are examined in analytical – computer way. For particular examination there was selected “Heidelberg” printing press GTO 52, but the examination method can be used for other presses. There was formed dynamic model with 16 degrees of freedom. Mathematical model of the system (oscillation equations and flowchart) was formed with MATLAB/SIMULINK program, in which dynamical process modeling was done. Errors in drive described as an amplitude frequency response. There was examined these response nature, resonant oscillations and its frequency influence to sheets transfer errors size.

Neben der konventionellen Digitalen Subtraktions-Angiografie (DSA) werden insbesondere seit Einführung der Angiografiesysteme mit Flachdetektor-Technologie zunehmend auch Rotationsangiografien und DYNA-CTs durchgeführt. Ziel der Studie ist die Bestimmung der Strahlenexposition für den Untersucher bei DSA-Serien im Vergleich zu Rotationsangiografien an einem biplanen Angiografiesystem unter Berücksichtigung gerätetechnischer Strahlenschutzvorrichtungen. Die Untersuchung erfolgte an einem biplanen Angiographiesystem mit Flachdetektor-Technologie (AxiomArtis dBA, Siemens). Die Strahlenexposition wurde als Ortsdosis in Höhe der Augen, Schilddrüse und Gonaden eines stehenden Untersuchers mit dem Dosimeter UMO LB 123 (Berthold) bestimmt. Alle Messungen wurden sowohl mit als auch ohne deckengeführtes Strahlenschutzschild und Unterkörperschutz mit Aufsatz durchgeführt. Die Messorte wurden in unterschiedlichen Abständen und Winkeln zum Isozentrum gewählt. Der Patient wurde durch ein Alderson-Phantom simuliert. Die Messergebnisse ergaben eine 90%ige Reduzierung der Strahlenexposition des Untersuchers durch die Strahlenschutzvorrichtung am Tisch. Für einen wirksamen Gonadenschutz ist der Aufsatz zum Unterkörperschutz unverzichtbar. Die optimale Schutzwirkung ist nur an der Position des Untersuchers nachweisbar; Personal direkt neben dem Untersucher ist einer bis zu 10mal größeren Strahlenexposition ausgesetzt. Die Strahlenexposition des Untersuchers ist bei der Durchführung einer Rotationsangiografie (8s DS H) auch unter Berücksichtigung aller gerätetechnischen Strahlenschutzvorrichtungen 9 bis 10fach höher, verglichen zu einer DSA-Serie in Standardprojektionen (6s, 3 Bilder/s). Die Strahlenexposition des Untersuchers an einem biplanen Angiografiesystem kann durch gerätetechnische Strahlenschutzvorrichtungen erheblich reduziert werden. Hochdosisprotokolle für Rotationsangiografien sollten auf ihre Notwendigkeit überprüft werden.

Copper is an integral component of key metabolic enzymes. Numerous physiological processes depend on a fine balance between the biosynthetic incorporation of copper into proteins and the export of excess copper from the cell. The homeostatic control of copper requires the activity of the copper transporting ATPases (Cu-ATPases). In Wilson disease the disruption in the function of the Cu-ATPase ATP7B results in the accumulation of excess copper and a marked deficiency of copper-dependent enzymes. In this work, the structure of ATP7B has been modeled by homology using the Ca-ATPase X-ray structure, enabling a mechanism of copper transport by ATP7B to be proposed. The fourth transmembrane helix (TM4) of Ca-ATPase contains conserved residues critical to cation binding and is predicted to correspond to TM6 of the ATP7B homology model, containing the highly conserved CXXCPC motif. The interaction with Cu(I) and the importance of the 3 cysteines in TM6 of ATP7B has been shown using model peptides. ATP7B has a large cytoplasmic N-terminus comprised of six copper-binding domains (WCBD1-6), each capable of binding one Cu(I). Protein-protein interactions between WCBDs and the copper chaperone Atox1 has been shown, contrary to previous reports, to occur even in the absence of copper. 15N relaxation measurements on the apo and Cu(I)-bound WCBD4-6 show that there is minimal change in the dynamic properties and the relative orientation of the domains in the two states. The domain 4-5 linker remains flexible, and domain 5-6 is not a rigid dimer, with flexibility between the domains. Copper transfer to and between WCBD1-6 likely occurs via protein interactions facilitated by the flexibility of the domains with respect to each other. The flexible linkers connecting the domains are important in giving the domains motional freedom to interact with Atox1, to transfer copper to other domains, and finally to transfer copper to the transmembrane site for transport across the membrane.

Copper is an integral component of key metabolic enzymes. Numerous physiological processes depend on a fine balance between the biosynthetic incorporation of copper into proteins and the export of excess copper from the cell. The homeostatic control of copper requires the activity of the copper transporting ATPases (Cu-ATPases). In Wilson disease the disruption in the function of the Cu-ATPase ATP7B results in the accumulation of excess copper and a marked deficiency of copper-dependent enzymes. In this work, the structure of ATP7B has been modeled by homology using the Ca-ATPase X-ray structure, enabling a mechanism of copper transport by ATP7B to be proposed. The fourth transmembrane helix (TM4) of Ca-ATPase contains conserved residues critical to cation binding and is predicted to correspond to TM6 of the ATP7B homology model, containing the highly conserved CXXCPC motif. The interaction with Cu(I) and the importance of the 3 cysteines in TM6 of ATP7B has been shown using model peptides. ATP7B has a large cytoplasmic N-terminus comprised of six copper-binding domains (WCBD1-6), each capable of binding one Cu(I). Protein-protein interactions between WCBDs and the copper chaperone Atox1 has been shown, contrary to previous reports, to occur even in the absence of copper. 15N relaxation measurements on the apo and Cu(I)-bound WCBD4-6 show that there is minimal change in the dynamic properties and the relative orientation of the domains in the two states. The domain 4-5 linker remains flexible, and domain 5-6 is not a rigid dimer, with flexibility between the domains. Copper transfer to and between WCBD1-6 likely occurs via protein interactions facilitated by the flexibility of the domains with respect to each other. The flexible linkers connecting the domains are important in giving the domains motional freedom to interact with Atox1, to transfer copper to other domains, and finally to transfer copper to the transmembrane site for transport across the membrane.

The present thesis is devoted to theoretical studies of resonant X-ray scattering and propagation of strong X-ray pulses. In the first part of the thesis the nuclear dynamics of different molecules is studied using resonant X-ray Raman and resonant Auger scattering techniques. We show that the shortening of the scattering duration by the detuning results in a purification of the Raman spectra from overtones and soft vibrational modes. The simulations are in a good agreement with measurements, performed at the MAX-II and the Swiss Light Source with vibrational resolution. We explain why the scattering to the ground state nicely displays the vibrational structure of liquid acetone in contrast to excited final state. Theory of resonant X-ray scattering by liquids is developed. We show that, contrary to aqueous acetone, the environmental broadening in pure liquid acetone is twice smaller than the broadening by soft vibrational modes significantly populated at room temperature. Similar to acetone, the "elastic" band of X-ray Raman spectra of molecular oxygen is strongly affected by the Thomson scattering. The Raman spectrum demonstrates spatial quantum beats caused by two interfering wave packets with different momenta as the oxygen atoms separate. It is found that the vibrational scattering anisotropy caused by the interference of the "inelastic" Thomson and resonant scattering channels in O2. A new spin selection rule is established in inelastic X-ray Raman spectra of O2. It is shown that the breakdown of the symmetry selection rule based on the parity of the core hole, as the core hole and excited electron swap parity. Multimode calculations explain the two thresholds of formation of the resonant Auger spectra of the ethene molecule by the double-edge structure of absorption spectrum caused by the out-of- and in-plane modes. We predict the rotational Doppler effect and related broadening of X-ray photoelectron and resonant Auger spectra, which has the same magnitude as its counterpart-the translational Doppler effect. The second part of the thesis explores the interaction of the medium with strong X-ray free-electron laser (XFEL) fields. We perform simulations of nonlinear propagation of femtosecond XFEL pulses in atomic vapors by solving coupled Maxwell's and density matrix equations. We show that self-seeded stimulated X-ray Raman scattering strongly influences the temporal and spectral structure of the XFEL pulse. The generation of Stokes and four-wave mixing fields starts from the seed field created during pulse propagation due to the formation of extensive ringing pattern with long spectral tail. We demonstrate a compression into the attosecond region and a slowdown of the XFEL pulse up to two orders of magnitude. In the course of pulse propagation, the Auger yield is strongly suppressed due to the competitive channel of stimulated emission. We predict a strong X-ray fluorescence from the two-core-hole states of Ne created in the course of the two-photon X-ray absorption. / QC 20110426

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this research was to evaluate the forage production, stocking rate and nutritive value of elephant grass in organic and conventional systems. In the organic system, were combined species with complementary growth periods; the elephant grass was planted in rows 3 m apart from each other; between rows of elephant grass, the annual ryegrass was seeding in the cool season and the development of spontaneous growing species in the warm season. In the conventional production two pastures were studied, one with the same strategy of organic production but with mineral fertilization, and the other elephant grass was cultivated alone. It was applied 120 kg of N ha-1 with mineral and organic fertilizer (manure of cattle and pig slurry) in the conventional and organic systems, respectively. Lactating Holstein cows were used in the evaluation. The experimental design was completely randomized with three treatments (grazing systems), three replicates (paddocks) with repeated measures (grazing cycles). The pre and post forage mass parameters, botanical and structural composition, forage production and stocking rate were evaluated. Forage samples were collected by the hand-plucking method to determine the organic matter, mineral matter, crude protein, neutral detergent fiber, in situ organic matter digestibility. During the experimental period (370 days), nine grazing cycles were performed in organic and conventional systems (elephant grass in association of other plants) and eight grazing cycles in the conventional system (elephant grass alone). Forage production, stocking rate and crude protein of elephant grass were 31.9; 32.6; 24.2 t of dry matter ha-1; 3.4; 2.1; 4.6 animal units ha-1 and 16.6; 14.9; 13.6 %, respectively for the grazing systems. Considering the herbage yield, better performance were foud on mixture pastures. Higher values of crude protein were observed in the organic system. / Objetivou-se com esta pesquisa avaliar a produção de forragem, taxa de lotação e valor nutritivo do capim elefante nos sistemas orgânico e convencional. No sistema orgânico, combinaram-se espécies com períodos de crescimento complementares; o capim elefante foi plantado em linhas com 3 m de distância uma da outra; entre as fileiras de capim elefante, durante o período hibernal, foi semeado o azevém e no período estival permitiu-se o desenvolvimento de espécies de crescimento espontâneo. Na produção convencional foram estudadas duas pastagens, uma com a mesma estratégia da produção orgânica, porém com adubação mineral e outra de capim elefante sob cultivo estreme. Foram aplicados 120 kg de N ha-1 com adubação mineral e orgânica (esterco bovino e dejetos de suínos) nos sistemas convencional e orgânico, respectivamente. Vacas da raça Holandesa foram utilizadas na avaliação. O delineamento experimental foi o inteiramente casualizado, com três tratamentos (sistemas forrageiros), três repetições (piquetes) com medidas repetidas no tempo (ciclos de pastejo). Foram avaliados parâmetros de massa de forragem de pré e pós pastejo, composições botânica e estrutural, produção de forragem e taxa de lotação. Foram coletadas amostras de forragem por simulação de pastejo para a determinação da matéria orgânica, matéria mineral, proteína bruta, fibra em detergente neutro e digestibilidade in situ da matéria orgânica. Durante o período experimental (370 dias) foram efetuados nove ciclos de pastejo nos sistemas orgânico e convencional (capim elefante em associação com outras plantas) e oito ciclos de pastejo no sistema convencional (capim elefante em cultivo singular). A produção de forragem, a taxa de lotação e o teor de proteína foram de 31,9; 32,3; 24,2 t de matéria seca ha-1; 3,4; 2,1 e 4,6 unidades animais ha-1 e 16,6; 14,9; 13,6 %, respectivamente para os sistemas forrageiros. Considerando a produção de forragem, pastos com misturas forrageiras apresentaram melhor desempenho. Foram observados maiores valores de proteína bruta no sistema orgânico.

The aim of this thesis was to investigate contrasting pasture management strategies on the foraging behaviour, pasture production, carcass characteristics, herbage intake, faecal gas emissions and methane emission by sheep grazing Italian ryegrass (Lolium multiflorum) pastures. The experiment was carried out in 2014 and 2015. The experimental design was a randomized complete block with four replicates and two grazing strategy treatments (traditional rotational stocking method – RT meaning pre- and post-grazing target heights of 25 and 5 cm, respectively and, “rotatinuous stocking” – RN with pre- and post-grazing target heights of 18 and 11 cm, respectively). The grazing management was based on a 1-day strip-grazing regime. Male castrated sheep were used. The actual average sward heights for the RN treatment were 17.9 and 11.1 cm (pre- and post-grazing, respectively) and 27.1 and 7.8 cm for the RT (pre- and post-grazing, respectively). The stocking period in 2014 was 146 and 140 days (RN and RT, respectively) and in 2015 it was 155 and 146 days (RN and RT, respectively). The diurnal animal activities (grazing, ruminating and resting time) did not differ between treatments, with average of 439.6, 166.9 and 85.0 minutes, respectively. The bite rate, feeding station per min and steps per min were greater at the RN than the RT treatment. Grazing time and bite rate were greater in the afternoon than morning in both treatments. Therefore, the daily herbage intake by sheep grazing Italian ryegrass was greater for the RN than the RT treatment (CHAPTER II). The herbage production in the RN was 28% higher than the RT treatment. Individual average daily gain and live weight gain per hectare were greater in the RN than the RT treatment (CHAPTER III). RN treatment presented greater final live weight, carcass and commercial cut weights from grazing sheep than RT treatment (CHAPTER IV). RN treatment had a faecal chemical quality greater than RT treatment, resulting in a greater daily nitrogen excretion per animal and greater faecal CH4 and N2O emissions (CHAPTER VI). The “rotatinuous stocking” (RN) was the better grazing management strategy for mitigation of CH4 emissions by sheep grazing Italian ryegrass, emitting 64% less CH4 per unit area and 170% less CH4 per unit of animal product than the traditional rotational stocking method (RT) (CHAPTER V).

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The exchange bias (EB) phenomen occurs due to the coupling between ferromagnetic and antiferromagnetic material and the main characteristics are the rise of unidirectional anisotropy and the rotational hysteresis in torque curves. In this work we have investigated how the unidirectional anisotropy and the rotational hysteresis are influenced by the change of some characteristics in thin films samples. Among these are the stacking of layers, the roughness at the interface between the two materials, the difference in the ferromagnetic layer thickness and the difference between the antiferromagnetic materials. The study was made by using magnetic torque measurements which were interpreted using a granular model for the EB. The parameters obtained from the fitting of the model to the torque curves has also permitted to reproduce data obtained by different magnetic techniques, especially in samples where the unidirectional anisotropy is greater than the uniaxial anisotropy. In NiFe=IrMn samples, the unidirectional anisotropy is favored by stacking layers, by increasing of the interfacial roughness and by the decrease of the ferromagnetic layer thickness, while the rotational hysteresis is substantially increased as the interfacial roughness increases. For the NiFe=FeMn sample the highest values of unidirectional anisotropy and rotational hysteresis were found, as well as a dependence of these parameters with the measuring magnetic field. / O fenômeno de "exchange bias" (EB) ocorre quando um material ferromagnético está acoplado a um material antiferromagnético e apresenta como características principais o surgimento de uma anisotropia unidirecional e a histerese rotacional em curvas de torque. Nesse trabalho foi investigado como a anisotropia unidirecional e a histerese rotacional são influenciadas pela mudança de algumas características em amostras na forma de filme finos. Entre essas características estão o empilhamento de camadas, a rugosidade na interface entre os dois materiais, a diferença na espessura da camada ferromagnética e a diferença entre os materiais antiferromagnéticos. O estudo foi realizado através de medidas de magnetometria de torque nas amostras, as quais foram interpretadas usando um modelo granular para o EB. Os parâmetros resultantes do ajuste do modelo às curvas de torque permitiram também reproduzir dados obtidos por outras técnicas de caracterização magnética, sobretudo em amostras que apresentam a anisotropia unidirecional maior do que a anisotropia uniaxial. Em amostras de NiFe=IrMn, a predominância da anisotropia unidirecional é favorecida pelo empilhamento de camadas, pelo aumento da rugosidade interfacial e pela diminuição da espessura da camada ferromagnética, enquanto a histerese rotacional apresenta aumento significativo somente com o aumento da rugosidade. Em uma amostra de NiFe=FeMn foram encontrados valores maiores tanto para a anisotropia unidirecional quanto para a histerese rotacional, bem como uma dependência desses com o campo de medida.