Made available in DSpace on 2014-10-09T12:32:39Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:04Z (GMT). No. of bitstreams: 1 03303.pdf: 2739006 bytes, checksum: 37fea580dbe76269b12b7bdf94c093e8 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Biociencias, Universidade de Sao Paulo - IB/USP

Magister Scientiae - MSc / In this study, the capabilities of Neutron Radiography (NRad) and -Tomography (NTomo), as well as X-ray Radiography (XRad) to investigate chlorides and chlorides corrosion effects within steel reinforced laboratory concrete samples are practically explored. Capabilities of Scanning Electron Microscopy (SEM), Prompt Gamma Neutron Activation Analysis (PGNAA), Particle Induced X-ray Emission (PIXE), Small-Angle Neutron Scattering (SANS), Neutron Diffraction (NDIFF) and X-ray Diffraction (XDIFF) analytical techniques are also explored through review of literature.

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Master of Science in Biomedical Sciences / Department of Diagnostic Medicine/Pathobiology / Jodi L. McGill / The causative agent of tuberculosis (TB) in cattle is Mycobacterium bovis (M. bovis). γδ T cells are a unique subset of nonconventional T cells that play major roles in both the innate and adaptive arms of the immune system. Bovine γδ T cells have the capacity for multiple immune functions during infection with M. bovis. However, the alternative functions of γδ T cells as well as the responses of γδ T cells in vivo at the site of infection remain unclear. To identify novel functions for γδ T cells in response to M. bovis infections, RNA sequencing and transcriptomics analysis was completed on peripheral blood γδ T cells isolated from virulent M. bovis-infected cattle. Differentially expressed genes were confirmed with real-time PCR. In an attempt to model in vivo cell-to-cell interactions at the site of infection, γδ T cells were also isolated from naïve and M. bovis-infected calves and co-cultured with autologous, BCG-infected, monocyte-derived macrophages. γδ T cell chemokine and cytokine expression was analyzed via ELISA and real-time PCR. The characteristic lesions of bovine tuberculosis are well-organized pulmonary granulomas. To determine the relevance of the RNA-sequencing and in vitro co-culture results to in vivo infection, tissue samples from granulomatous lesions in the lungs and mediastinal lymph nodes of virulent M. bovis-infected cattle were collected 3 months after infection. mRNA transcripts for γδ T cells expression of-- IFN-γ, IL-17, IL-10, IL-22, and CCL2 were microscopically evaluated within the granulomas using an in situ hybridization system, RNAScope (Advanced Cell Diagnostics Inc.). Co-culture experiments and transcriptomics analysis revealed increased expression of chemokines and various cytokines by γδ T cells responding to M. bovis infection. The novel in situ hybridization assay revealed that cytokine expression by γδ T cells varied within the lesions, with significant levels of CCL2 and IFN-γ, and low expression of IL-10, IL-22, and IL-17 in situ at this time-point after infection. Co-culture experiments also revealed that γδ T cells from virulent M. bovis-infected cattle have the capacity to directly impact the viability of M. bovis in vitro. Our results suggest that γδ T cells accumulate within the granulomas, and influence host immunity to M. bovis by secretion of cytokines and chemokines, and direct cytotoxicity, in response to infected macrophages.

An experimental study of the low lying excited states of C¹¹ has been made using the B¹⁰(d ,nɣ )C¹¹ reaction at a deuteron bombarding energy of 0.8 Mev. Measurements were made of the n- ɣangular correlations of the ground state gamma transitions from the 6.49 and 4.32 Mev levels, and of the gamma ray branching ratios of the 6.49, 4.81 and 4.32 Mev levels. The apparatus used for the measurements was a combination of a NaI(T1) gamma ray spectrometer and an improved fast neutron time-of-flight spectrometer, developed by the author. Theoretical analysis of the n-ɣ angular correlations showed that the 6.49 Mev and 4.32 Mev levels are formed by the capture of p½ protons This restricts the Jπ values of these levels to (5/2)¯ or (7/2)¯. The parities of the states observed in this experiment are all known to be negative from the high energy stripping data of Cerineo and Maslin et al. A comparison of the experimental branching ratios with the theoretical branching ratios predicted by the intermediate coupling shell model is consistent with the following spin and parity assignments in C¹¹ : g.s. (3/2)¯, 2.00 Mev (1/2)¯, 4.32 Mev (5/2)¯, 4.81 Mev (3/2*)¯ and 6.49 Mev (7/2)¯. These assignments are in agreement with other recent results. The correspondence of these levels in C¹¹ with those of B¹¹ is consistent with the hypothesis of the charge independence of nuclear forces. The experimental results agree in some cases and disagree in others with the intermediate coupling shell model calculations of Kurath. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The reaction D(p, γ )He³ was studied at incident proton energies of less than 50 kev. The method was to bombard heavy ice targets with the proton beam from the 50 kv accelerator. This machine develops an intense beam of 60 to 80 microamps which is necessary to produce a substantial yield despite the low reaction cross section. The angular distribution of the γ-rays was found to follow a (sin²θ +B) pattern as expected from earlier work carried out at higher energies. In the neighborhood of 35 kev the value of B was found, by measurements of the yield at 90° and at 0° to the incident beam direction, to be .283± .110. The total cross section was found to take on the following values: [In column] E(kev), 29.1, 37.5 44.0 ; [In column] σ(cm² ) x 10⁻³², 4.87 ± 1.05, 11.2 ± 2.8, 12.0 ± 4.0 / Science, Faculty of / Physics and Astronomy, Department of / Graduate

A study of the T(α,ɤ)Li⁷ reaction has been made at mean alpha particle energies of 1320, 560 and 350 Kev in a solid tritium-zirconium target. At the 1320 Kev energy the absolute 90° differential cross-section for transitions to the ground state has been found to be 1.89x10⁻³¹ cm² per steradian from analyses of spectra obtained in a 2¾"x4½” NaI crystal. At this energy the ratio of the differential cross-section for transitions to the first excited state to that for transitions to the ground state was found to be 0.446. This ratio was observed to remain the same at all detector angles. The excitation function roughly determined by additional runs at 560 and 350 Kev mean energy followed the form obtained by Riley of this laboratory in 1958. Angular distribution measurements at 1320 Kev gave the result that both the above mentioned gamma rays have the same angular dependence, this being 1-0.11 cos² θ + 0.39 cos⁴ θ. At 560 Kev mean energy their anisotropy was measured to be about 5%. A background from the target has been found to have an angular distribution at 1320 Kev mean alpha particle energy of 1+0.35 cos θ in laboratory co-ordinates. Both its excitation function, determined roughly from runs at 560 and 350 Kev, and its anisotropy followed a form in agreement with neutron counter measurements. It is suggested that this background is caused by neutrons from some still unknown reaction in the target. An investigation was also made of a standard thick-walled brass Geiger-Muller counter to determine its efficiency for photon energies from 0.5 to 20 Mev. A smooth curve was obtained showing efficiency increasing with gamma ray energy thus agreeing in form with previous experimental and theoretical results. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Des modèles de Gravité Quantique (QG) prédisent une violation de l'invariance de Lorentz (LIV), se manifestant par une dispersion de la lumière dans le vide. Si un tel effet existe, des photons d'énergies différentes émis en même temps par une source distante sont détectés sur Terre à des moments différents. Les émissions transitoires à (très) hautes énergies provenant de sources astrophysiques lointaines, comme les sursauts gamma (GRBs) et les blazars sont utilisées pour contraindre cet effet LIV. Cet ouvrage présente les études menées avec deux télescopes gamma majeurs : H.E.S.S. -- pour lequel une étude de la qualité des données étalonnées a été réalisée -- et Fermi-LAT. Les énergies et les temps d'arrivée de photons individuels ont été utilisés pour contraindre le paramètre de dispersion dans le vide ainsi que l'échelle d'énergie E_QG à laquelle des effets LIV peuvent apparaitre. La méthode de maximum de vraisemblance est décrite, avec une étude détaillée des systématiques. Une modification dans le cas de fond non négligeable est appliquée aux données de l'éruption d'un blazar observé par H.E.S.S. : les limites obtenues sur E_QG sont moins contraignantes que les meilleures limites précédentes, mais elles se trouvent à un redshift non couvert à ce jour. Quatre GRBs observés par Fermi-LAT ont aussi été analysés, en déterminant la courbe de lumière de deux manières : ajustements gaussiens et estimation par densité de noyaux. Les meilleures limites sur E_QG pour le cas linéaire/subluminal sont obtenus avec GRB090510 : E_QG,1 > 7,6 E_Planck. Des limites plus robustes, tenant compte des effets intrinsèques à la source, ont également été produites. / Some Quantum Gravity (QG) theories allow for a violation of Lorentz invariance (LIV), manifesting as a dependence on the velocity of light in vacuum on its energy. If such a dependence exists, then photons of different energies emitted together by a distant source will arrive at the Earth at different times. (Very) high energy transient emissions from distant astrophysical sources such as Gamma-ray Bursts (GRBs) and blazars can be used to search for and constrain LIV. This work presents the studies obtained with two leading Gamma-ray telescopes: H.E.S.S. -- for which a study of the quality of the calibrated data was performed -- and Fermi-LAT. The energies and arrival times of individual photons were used to constrain the vacuum dispersion parameter and the energy scale EQG at which QG effects causing LIV may arise. The maximum likelihood method is described, with detailed studies of the systematics. A modification for a non-negligible background is provided and applied to the data of an AGN flare observed by H.E.S.S.: the obtained limits on the QG energy scale are less constraining than the previous best limits obtained with blazars; yet, the new limits lie a redshift range not covered this far. Four bright and quasi background-free GRBs observed by the Fermi-LAT were also analysed, with two different template light curve determinations -- Gaussian fits and Kernel Density Estimates. The best limits on the E_QG scale for the linear/subluminal case are from the shortest burst, GRB090510: E_QG,1 > 7.6 E_Planck. More robust limits, considering the intrinsic effects possibly occurring at the source, were also derived.

Experimental measurements in conjunction with stochastic simulations are used to determine hydrogen atom yields in the gamma and heavy ions radiolysis of aqueous solutions of formate and deuterated formate ions. In radiolysis, the hydrogen atom is produced directly by the fragmentation of water excited states, and during the diffusion-kinetic evolution of the radiation track by the intra-track reaction of eaq⁻ with Haq⁺ up to the microsecond timescale. The yield of H• is relatively small, but it is fundamentally very important. An accurate examination of the H atom yields after radiolysis will make possible a better understanding of the initial steps of the radiolytic decomposition of water. The competition between H atom combination reactions and its formation by reaction of eaq⁻ with Haq⁺ makes predictions of the H atom kinetics very difficult. Hydrogen atom yields were determined by difference measurements of H2 yields and directmeasurements of HD yields when using deuterated formate as H• scavenger. While the total H₂ yield measured is always greater for alpha than for gamma radiolysis, the H atom yield is observed to be smaller. The addition of selected scavengers of the hydrated electron and its precursors reveals a stronger correlation of the H atom formation on the precursor to the hydrated electron rather than the hydrated electron itself. Scavengable H• yields strongly decrease as the concentration of the electron scavenger increases. Stochastic track chemistry calculations were used to analyze the measured experimental yields and to elucidate the underlying kinetics.