<p>Recent work has shown that hyperpolarized magnetic resonance spectroscopy (HP-MRS) can trace in vivo metabolism of biomolecules and is therefore extremely promising for diagnostic imaging. The most severe challenge this technique faces is the short signal lifetime for hyperpolarization, which is dictated by the spin-lattice (T1) relaxation. In this thesis we show with theory, simulation and experiment that the long-lived nuclear spin states in chemically equivalent or near equivalent spin systems offer a solution to this problem. Spin polarization that has lifetime much longer than T1 (up to 70-fold) has been demonstrated with pulse sequence techniques that are compatible with clinical imaging settings. Multiple classes of molecules have been demonstrated to sustain such long-lived hyperpolarization.</p> / Dissertation

This dissertation presents the results of the first search for heavy, neutral, longlived particles that decay to photons at a hadron collider. We use a sample of +jet+missing transverse energy events in p¯p collisions at ps = 1.96 TeV taken with the Collider Detector at Fermilab. Candidate events are selected based on the arrival time of a high-energy photon at the electromagnetic calorimeter as measured with a timing system that was recently installed. The final result is that we find 2 events, using 570±34 pb−1 of data collected during 2004-2005 at the Fermilab Tevatron, consistent with the background estimate of 1.3±0.7 events. While our search strategy does not rely on model-specific dynamics, we interpret this result in terms of cross section limits in a supersymmetric model with e01! eG and set a world-best e01 mass reach of 101 GeV/c2 at e = 5 ns. We can exclude any +jet+missing transverse energy signal that would produce more than 5.5 events.

This diploma thesis deals with the issue of fair value measurement of tangible long-lived assets under IAS/IFRS. It is objective is to assess the impact of revaluation of long-lived assets from their historical prices to their fair value. The work further characterizes the harmonization of the accounting systems and detailed described IFRS 13 – Fair Value Measurement. The work is focused on company describing particular the valuation methodology as well as specific data on the asset. At the end of the work the potential risks of users of the financial statements are displayed.

The research presented in the dissertation deals with the synthesis, characterization, photophysical, electrochemical, and pump probe studies of porphyrin-fullerene based donor-acceptor conjugates. The first chapter provides insights into the introduction of the thesis, which explains the events that occur in natural photosynthesis and the mimicking process of an artificial photosynthesis based on natural photosynthesis, works done in covalently and non-covalently linked donor acceptor systems, and the penetration of the literature related to the long-lived charge-separated states donor-acceptor conjugates. The second chapter details the physical methods employed to monitor the various photochemical processes in the donor-acceptor moiety. The third chapter focusses on designing and synthesizing a platinum porphyrin-fullerene dyad used for long-lived charged-separated state. The formation of a high-energy, long-lived radical ion pair by electron transfer from the triplet excited state is orchestrated in the dyad. The porphyrin ring is modified with three triphenylamine which act as secondary electron donors. The spin state of the electrons leading to the formation of long-lived charge-separated state is demonstrated by time-resolved optical and EPR spectroscopy. The fourth chapter studies metal ligand axial coordination. Two porphyrins were self-assembled via metal-ligand axial coordination of phenyl imidazole functionalized fulleropyrrolidine. A 1:2 complex formation with ImC60 was observed in the case of (TTP)Co, while for (TPA)4PCo only a 1:1 complex was possible. Spectroelectrochemistry revealed the formation of Co (III) porphyrin cation instead of Co (II) porphyrin radical cation during the oxidation of phenyl imidazole coordinated cobalt porphyrin. Using computational and electrochemical results, an energy level diagram was constructed to visualize the various photochemical events. Using femtosecond transient absorption spectroscopy, it was possible to observe the energy transfer and charge-separation process. The fifth chapter deals with the singlet oxygen generation of platinum and palladium porphyrins. In this chapter, a series of meso-substituted porphyrins are synthesized and metalated by platinum and pallidum porphyrins and characterized by several methods. The ability of both platinum and palladium porphyrins reveals higher electrochemical redox gaps as compared to their free base porphyrins. Both platinum and palladium porphyrins can generate singlet oxygen and probe by monitoring the photoluminescence of 1O2 at 1270 nm. The study highlights the importance of different meso-substituents in triplet porphyrin sensitizers that can estimate the singlet oxygen quantum yield, which is useful for photodynamic therapy, chemical synthesis, and other applications.

Fluorinated compounds are environmentally persistent and have been demonstrated to bioaccumulate and contribute to climate change. The focus of this work was to better understand the atmospheric chemistry of poly- and per-fluorinated compounds in order to appreciate their impacts on the environment. Several fluorinated compounds exist for which data on climate impacts do not exist. Radiative efficiencies (REs) and atmospheric lifetimes of two new long-lived greenhouse gases (LLGHGs) were determined using smog chamber techniques: perfluoropolyethers and perfluoroalkyl amines. Through this, it was observed that RE was not directly related to the number of carbon-fluorine bonds. A structure-activity relationship was created to allow the determination of RE solely from the chemical structure of the compound. Also, a novel method was developed to detect polyfluorinated LLGHGs in the atmosphere. Using carbotrap, thermal desorption and cryogenic extraction coupled to GC-MS, atmospheric measurements can be made for a number of previously undetected compounds. A perfluoroalkyl amine was detected in the atmosphere using this technique, which is the compound with the highest RE ever detected in the atmosphere. Perfluorocarboxylic acids (PFCAs) are water soluble and non-volatile, suggesting they are not susceptible to long-range transport. A hypothesis was derived to explain the ubiquitous distribution of these compounds involving atmospheric formation of PFCAs from volatile precursors. Using smog chamber techniques with offline analysis, perfluorobutenes and fluorotelomer iodides were shown to yield PFCAs from atmospheric oxidation. Dehydrofluorination of perfluorinated alcohols (PFOHs) is poorly understood in the mechanism of PFCA atmospheric formation. Using density functional techniques, overtone-induced photolysis was shown to lead to dehydrofluorination of PFOHs. In the presence of water, this mechanism could be a sink of PFOHs in the atmosphere. Confirmation of the importance of volatile precursors was derived from examination of snow from High Arctic ice caps. This provided the first empirical evidence of atmospheric deposition. Through the analytes observed, fluxes and temporal trends, it was concluded that atmospheric oxidation of volatile precursors is an important source of PFCAs to the Arctic.

L’océan et l’atmosphère sont des environnements fluides stratifiés en densité, en référentiel tournant : la force de Coriolis due à la rotation de la planète influence l’écoulement. De grands tourbillons lenticulaires évoluent dans ces environnements, avec parfois de grandes durées de vie comme les Meddies de l’Océan Atlantique.Dans la continuité des expériences de Griffiths & Linden (1981) et Hedstrom & Armi (1988), ces tourbillons sont reproduits en laboratoire en injectant ou aspirant localement du fluide dans une couche d’eau salée tournante, linéairement stratifiée en densité. A l’ordre dominant, les tourbillons sont à l’équilibre cyclo-géostrophique et hydrostatique, d’où l’on dérive la loi de leur rapport d’aspect, validée par les expériences et les observations. Un modèle complet de tourbillon à l’équilibre incluant les recirculations internes est proposé, en partant d’un profil Gaussien pour la vitesse azimutale, puis validé numériquement. A partir de ce modèle, un bilan d’énergie permet alors de décrire la décroissance des tourbillons.Certains tourbillons naturels comme les Meddies présentent des structures fines associées à de forts gradients de densité à leur frontière, que l’on reproduit en laboratoire autour de tourbillons entretenus par une injection continue de fluide. Ces structures en couches sont la manifestation de l’instabilité de McIntyre, instabilité qui apparaît lorsque les diffusivités visqueuse et moléculaire sont sensiblement différentes. L’analyse de stabilité linéaire de McIntyre appliquée au modèle Gaussien de tourbillon permet de retrouver les tailles et temps d’apparition associés au couches qui entourent les Meddies. / The ocean and the atmosphere are density stratified fluid environments in a rotating frame: the Coriolis force, due to the rotation of the planet, influences the flow. Huge lenticular vortices evolve in these environments, sometimes with very long lifetimes as the Meddies of the Atlantic Ocean.Based on Griffiths & Linden (1981) and Hedstrom & Armi (1988) experiments, such vortices are experimentally reproduced by locally injecting or sucking up fluid in a rotating layer of salty water, linearly density stratified. At dominant order, the vortices are in cyclo-geostrophic and hydrostatic balance, from which the law for their vertical aspect ratio is derived, validated by experiments and observations. A more complete model of vortex in equilibrium is proposed from a Gaussian profile for the azimuthal velocity, including internal secondary circulations, and then numerically validated. From this model, an energy balance allows us to describe the vortices decay.Some natural vortices, as the Meddies, have fine-structures associated to high density gradients at their frontier, that we experimentally reproduce around vortices maintained through a continuous injection of fluid. This layered structure is the expression of McIntyre's instability, which appears when viscous and molecular diffusivities are significantly different. The linear stability analysis of McIntyre applied to the Gaussian model of vortex allows us to recover the sizes and duration of appearance of the layers that surround the Meddies when eddy viscosities measured in the ocean are used.

The diploma thesis compares different accounting methods in the three accounting systems in the long-lived assets area. The dominant accounting system in the thesis is the IFRS. In the first part long-lived assets are described according IFRS. The US GAAP and Czech accounting law are shown only main differences. The diploma thesis describes and explains the cause of differences between all three systems and shows the impact on the financial statements. In the second part of the thesis the outcomes of financial research on companies which presents their financial results according IFRS are presented.

Transmission Control Protocol (TCP) has been recognized as the most important transport-layer protocol for the Internet. It is distinguished by its reliable transmission, flow control, and congestion control. However, the issue of fair bandwidth-sharing among competing flows was not properly addressed in TCP. As web-based applications and interactive applications grow more popular, the number of short-lived flows conveyed on the Internet continues to rise. With conventional TCP, short-lived flows will be unable to obtain a fair share of available bandwidth. As a result, short-lived flows will suffer from longer delays and a lower service rate. It is essential for the Internet to come up with an effective solution to this problem in order to accommodate the new traffic patterns. With a more equitable sharing of bottleneck bandwidth as its goal, two cross-layer stateless queue management schemes featuring Drop Maximum (DM) and Early Drop Maximum (EDM) are developed and presented in this dissertation. The fundamental idea is to drop packets from those flows having more than an equal share of bandwidth and retain low level of queue occupancy. The congestion window size of a TCP sender is carried in the options field on each packet. These proposed schemes will be exercised on routers and make its decision on packet dropping according to the congestion windows. In case of link congestion, the queued packet with the largest congestion window will be dropped from the queue. This will lower the sending rate of its sender and release part of the occupied bandwidth for the use of other competing flows. By so doing, the entire system will approach an equilibrium point with a rapid and fair distribution of bandwidth. As a stateless approach, these proposed schemes inherit numerous advantages in implementation and scalability. Extensive simulations were conducted to verify the feasibility and the effectiveness of the proposed schemes. For the simple proposed packet discard scheme, Drop Maximum outperforms the other two stateless buffer management schemes, i.e. Drop Tail and Random Early Drop, in the scenario of homogeneous flows. However, in heterogeneous flows, Random Early Drop gains superiority to packet discard schemes due to its additional buffer occupancy control mechanism. To overcome the lack of proper buffer occupancy control, Early Drop Maximum is thus proposed. As shown in the simulation results, this proposed scheme outperforms existing stateless techniques, including Drop Tail, Drop Maximum and Random Early Drop, in many respects, such as a fair sharing of available bandwidth and a short response time for short-lived flows.

Introduction The embrace of PET by medical clinicians has been reluctant (ΔT ≈ 20 yr) primarily due to the scale of the infrastructure that is needed. The capital cost of a cyclotron (≈ 106 USD) is now dwarfed by the demand for compliance to recent regulatory standards. This is a recurring expense, not only imposing an order-of-magnitude increase in staffing and operating costs, but damping the enthusiasm of researchers recalling the brisk pace of research in earlier days. Now an academic site, with little interest or opportunity to scale up production for wider distribution, is burdened by the new regulatory terrain of good manufacturing practice (GMP), mandated for translational studies that will reach only a few subjects. With our production resources held within a basic science department, the Medical Physics cyclotron facility at the University of Wisconsin has sought a sustainable pathway. We now anchor the operating budget by providing high-value, long-lived radionuclides to off-site users, to buffer the fluctuations of local demand for conventional PET synthons. Material and Methods: The tools of the trade The radioisotopes discussed here belong to the 3-d and 4-d sub shell, but are now moving into the rare-earths, with applications ranging from - targeted molecular imaging agents, - internal radionuclide therapy using to Auger electron-emitters, - to basic physics experiments using 163Ho (t1/2 ≈ 4500 yr) to determine the mass of the neutrino. Rather than focusing on the dozens of radionuclides produced, a number of tools deserve mention, as they support a variety of targets, reactions and products. These will be listed in order (A-G) from cyclotron to extraction to analysis. A. Two cyclotrons are used, a legacy RDS 112 (#1; 1985) and a GE PETtrace (2009). Neutron and gamma detectors are monitored during the long irradia-tions, signaling any subtle changes in the running conditions. (1). The PET-trace is fitted with a quick-change variable degrader target (2), as well as a beam-line with a 5-port (0 o, ±15 o, ±30 o) vertical switching magnet (3). The downward directed beam ports provide support for solid targets (e.g. Ga, S, Se, Te) that melt at low temperature. The irradiation of gas targets employs a generalized manifold to handle inert gases such as 36Ar for the production of 34mCl, as well as natural Kr and Xe for making Rb and Cs isotopes to act as fission product surrogates. These products are captured on a stainless steel target chamber liner, and rinsed off with warm water. The alkali metals are convenient tracers to study the ion exchange trapping process, pivotal in future 99Mo production from solution reactors (4). B. The preparation of malleable solid targets employs a 10-ton hydraulic bench press, and a jeweler’s mill to roll out foils from pellets, pressed between Nb foils to avoid contamination. C. Binary alloys are smelted in a programmable 1600o tube furnace under argon flow (eg. NiGa4). Alternatively, an induction furnace now permits highly localized heating of the binary metal charge, while allowing mechanical agitation during the smelting process. D. Electroplating onto gold discs is used for various enriched target material or the alloys above where quantitative recovery is essential, or where heat transfer from high beam current is demanding. E. The separation chemistry, prior to che-lation to targeted molecular imaging agents, is performed in LabView-driven, home-built “black boxes” resident in mini-cells (Radiation Shielding Inc.). F. Analysis of the targets after irradiation makes use of HPGe spectroscopy for gammas and characteristic X-rays of decay (e.g. rare earths). The elemental constitution of target alloys is deter-mined prior to irradiation by X-ray fluorescence analysis, excited by 109Cd and 241Am sources. G. Finally, broad-band elemental analysis at the ppb level now makes use of a microwave plasma atomic emission spectrometer (Agilent 4200), to be de-scribed elsewhere in this meeting. Results and Conclusions The tools above (A-G) are employed in the pro-duction of the expanded list of radionuclides offered by our cyclotron group to both local and off-site colleagues. The list below is ordered in terms of decreasing use, from regular production for national distribution (64Cu, 89Zr), to weekly inhouse use (44Sc, 66,68Ga, 68,69,71Ge, 72As, 61Cu, 86Y), to infrequent production for multi-site collaborations (163Ho, 95mTc, 206Bi): Radionuclide Target Employs 64Cu 64Ni/Au A, D, G 89Zr natY A, E, G 44Sc natCa A, B, E, F, G 66, 68Ga Zn/Ag A, B, D, E, F, G 68, 69, 71Ge Ga, GaO2 A, B, C, E,F 72As GeO2 A, B, E, F 52Mn natCr A, E, F, G 76, 81mBr SeO A, E, F 34mCl, Rb, Cs noble gas A, E, F 95mTc,163Ho Mo, Dy A, E, F TABLE 1. Target materials and processes. The production of long-lived radionuclides lends itself to crowd-sourcing, with distributed irradia-tion at virtually any site with a suitable accelera-tor and a relaxed beam schedule. A number of unique challenges do arise that don’t appear in the usual production of conventional cyclotron products such as 11C or 18F. Contamination by stable metals, inadvertently introduced by target pressing or beam-induced sputtering from degraders, can cause serious interference downstream limiting effective specific activity. Long-lived manganese isotopes are ubiquitous. And some very high value products are simply not within the reach of small cyclotrons, such as 52Fe and 67Cu, being too far off the line of beta stability. In conclusion, the research leading to a doctoral degree necessarily must focus on the physics and chemistry of novel radionuclides and tracers. On the other hand, clinical and translational research needs established imaging agents, with little room for innovation within the regulatory constraints. Our experience at Wisconsin has led us to a balancing act, with our routine production of clinical doses countered with our research program to provide high-value radionu-clides for our collaborative work with our basic science colleagues.

Fluorinated compounds are environmentally persistent and have been demonstrated to bioaccumulate and contribute to climate change. The focus of this work was to better understand the atmospheric chemistry of poly- and per-fluorinated compounds in order to appreciate their impacts on the environment. Several fluorinated compounds exist for which data on climate impacts do not exist. Radiative efficiencies (REs) and atmospheric lifetimes of two new long-lived greenhouse gases (LLGHGs) were determined using smog chamber techniques: perfluoropolyethers and perfluoroalkyl amines. Through this, it was observed that RE was not directly related to the number of carbon-fluorine bonds. A structure-activity relationship was created to allow the determination of RE solely from the chemical structure of the compound. Also, a novel method was developed to detect polyfluorinated LLGHGs in the atmosphere. Using carbotrap, thermal desorption and cryogenic extraction coupled to GC-MS, atmospheric measurements can be made for a number of previously undetected compounds. A perfluoroalkyl amine was detected in the atmosphere using this technique, which is the compound with the highest RE ever detected in the atmosphere. Perfluorocarboxylic acids (PFCAs) are water soluble and non-volatile, suggesting they are not susceptible to long-range transport. A hypothesis was derived to explain the ubiquitous distribution of these compounds involving atmospheric formation of PFCAs from volatile precursors. Using smog chamber techniques with offline analysis, perfluorobutenes and fluorotelomer iodides were shown to yield PFCAs from atmospheric oxidation. Dehydrofluorination of perfluorinated alcohols (PFOHs) is poorly understood in the mechanism of PFCA atmospheric formation. Using density functional techniques, overtone-induced photolysis was shown to lead to dehydrofluorination of PFOHs. In the presence of water, this mechanism could be a sink of PFOHs in the atmosphere. Confirmation of the importance of volatile precursors was derived from examination of snow from High Arctic ice caps. This provided the first empirical evidence of atmospheric deposition. Through the analytes observed, fluxes and temporal trends, it was concluded that atmospheric oxidation of volatile precursors is an important source of PFCAs to the Arctic.