As of September 2007, there were over 67,000 U.S. bridges in the National Bridge Inventory classified as having unknown foundations. The bridges spanning rivers are of critical importance due to the risks of potential scour. In fact, over half of all bridge collapses are due to scour. Not only are these failures costly, they can be deadly for the traveling public. On April 5, 1987, ten people were killed in New York when a pier collapsed on the Schoharie Creek Bridge causing two spans of the deck to fall into the creek. Several other fatal collapses have occurred since the Schoharie Creek Bridge failure. Detecting scour is only part of the assessment that must take place to determine risk of failure and knowing the foundation depth is a critical component of the assessment. While this issue is not new, current techniques are typically invasive or costly. This research explores the feasibility and effectiveness of induced polarization (IP) and electrical resistivity imaging (ERI), near surface geophysical methods, for determining the depth of unknown foundations. In this work, forward models are created to ascertain the effects of the bridge layout on data quality such as varying depths and the impact of adjacent foundations on the foundation in question. Next, an experimental study is conducted at a National Geotechnical Experimentation Site (NGES) to further identify key parameters for the testing design and setup in order to obtain optimal surveys of bridge foundations. The conclusions of the forward modeling and NGES investigations are used to plan the field surveys on four bridges with known foundations. The outcomes of the four bridges show that IP and ERI can be used in concert with one another to estimate the type and depth of bridge foundations. The results of the field surveys are used to create a probability of non-exceedance curve for future predictions of unknown bridge foundations using the methods described in this research.

Quantum key distribution (QKD) allows two remote parties to generate secret keys for cryptographic purposes. Its security has been proven with some assumptions. However, practical realizations may not comply with all the assumptions, leading to various attacks. Founded on the observation that almost all attacks are on the detection part, measurement-device-independent QKD (MDI-QKD) was proposed to remove all such attacks. This thesis presents an implementation of the protocol. In our implementation, key bit information was encoded in the polarization states of weak coherent pulses at 1542 nm wavelength in optical fibers, and decoy state techniques were employed. We ensured stable polarization preparation and alignment and developed a QKD system over 10 km of standard Telecom fibers at 500 KHz repetition rate. Our work demonstrates the practicality of MDI-QKD protocol of removing all attacks, existing and yet to be discovered, on the detection part of a QKD system.

The radiative mechanism responsible for the prompt gamma-ray burst (GRB) emission remains elusive. For the last decade, optically thin synchrotron emission from shocks internal to the GRB jet appeared to be the most plausible explanation. However, the synchrotron interpretation is incompatible with a significant fraction of GRB observations, highlighting the need for new ideas. In this thesis, it is shown that the narrow, dominating component of the prompt emission from the bright GRB090902B is initially consistent only with emission released at the optically thick jet photosphere. However, this emission component then broadens in time into a more typical GRB spectrum, which calls for an explanation. In this thesis, a previously unconsidered way of broadening the spectrum of photospheric emission, based on considerations of the lateral jet structure, is presented and explored. Expressions for the spectral features, as well as polarization properties, of the photospheric emission observed from structured, relativistic jets are derived analytically under simplifying assumptions on the radiative transfer close to the photosphere. The full, polarized radiative transfer is solved through Monte Carlo simulations, using a code which has been constructed for this unique purpose. It is shown that the typical observed GRB spectrum can be obtained from the photosphere, without the need for additional, commonly assumed, physical processes (e.g. energy dissipation, particle acceleration, or additional radiative processes). Furthermore, contrary to common expectations, it is found that the observed photospheric emission can be highly linearly polarized (up to $\sim 40 \, \%$). In particular, it is shown that a shift of $\pi/2$ of the angle of polarization is the only shift allowed by the proposed model, consistent with the only measurement preformed to date. A number of ways to test the theory is proposed, mainly involving simultaneous spectral and polarization measurements. The simplest measurement, which tests not only the proposed theory but also common assumptions on the jet structure, involves only two consecutive measurements of the angle of polarization during the prompt emission. / <p>QC 20131204</p>

Quantum key distribution (QKD) allows two remote parties to generate secret keys for cryptographic purposes. Its security has been proven with some assumptions. However, practical realizations may not comply with all the assumptions, leading to various attacks. Founded on the observation that almost all attacks are on the detection part, measurement-device-independent QKD (MDI-QKD) was proposed to remove all such attacks. This thesis presents an implementation of the protocol. In our implementation, key bit information was encoded in the polarization states of weak coherent pulses at 1542 nm wavelength in optical fibers, and decoy state techniques were employed. We ensured stable polarization preparation and alignment and developed a QKD system over 10 km of standard Telecom fibers at 500 KHz repetition rate. Our work demonstrates the practicality of MDI-QKD protocol of removing all attacks, existing and yet to be discovered, on the detection part of a QKD system.

No description available.

Nuclear magnetic resonance (NMR) yields remarkably detailed structural information about virtually any molecule. However, its application to non-equilibrium systems is hampered by a lack of sensitivity. To increase the amount of signal that can be obtained from a NMR experiment, various hyperpolarization schemes have been previously introduced. One such technique is dynamic nuclear polarization (DNP), which can enhance NMR sensitivity by several orders of magnitude. The work detailed here focuses on the development of methods utilizing DNP to study non-equilibrium systems such as chemical and biochemical reactions in real-time. To work with hyperpolarized samples, we have designed and constructed a rapid injection and mixing system. This system allows samples to be transported between superconducting magnets used for polarization and for NMR spectroscopy in less than two seconds. Rapid transport is essential for successful use of samples with short spin-lattice relaxation times. For the study of reactions under non-equilibrium conditions, the system provides the additional capability for samples to be mixed with a second, unpolarized reagent. A chromogenic trypsin catalyzed ester hydrolysis reaction was used to validate the DNP-NMR technique as a tool for kinetic analysis. It is shown that the DNP-NMR method agrees with the conventional UV method within the uncertainty of the measurement. Hyperpolarization in this modality presents both challenges and opportunities, each of which motivate the development of new NMR techniques. In addition to the determination of kinetics, DNP-NMR is amenable to mechanistic analysis of a reaction. We have developed a technique based on selective inversion of spin-polarization, which allows for mapping of atoms between reactant and product of a reaction. This scheme was applied to a Grignard reaction, demonstrating applicability to organic reactions. Signal averaging, as it is applied for conventional multi-dimensional correlation spectroscopy cannot always be applied easily when using hyperpolarized sample. For the rapid measurement of heteronuclear correlation spectra, we have developed a technique utilizing the differential scaling of scalar coupling under off-resonance irradiation. Although DNP-NMR yields spectra of outstanding quality even with small quantities of sample, peak intensities are not quantitative. It is nevertheless possible to compare peak multiplets obtained from fractionally isotope labeled samples. Using biosynthetically labeled lipids from E. Coli cells, we showed that the resulting labeling patterns reflect their biosynthetic pathways. As a final case-study employing several of these newly developed methods, the uronate isomerase catalyzed isomerization of glucuronate into fructuronate was studied. The ability to follow the reaction in real-time while directly observing all anomeric forms of the reactant and product permits the independent determination of kinetics for each anomeric form of substrate and product. This study revealed the anomeric specificity of the enzyme.

The work described in this thesis is concerned with the development and application of real-time photo-CIDNP (Chemically Induced Dynamic Nuclear Polarisation) to the study of protein structure and folding. Chapters 1 and 2 introduce the protein folding problem, and its study by NMR, then go on to elucidate the mechanisms behind the photo-CIDNP phenomenon. Chapter 3 applies photo-CIDNP spectroscopy to the study of a small cytochrome protein. The difficulties of performing these experiments on chromophore-containing proteins are discussed. Chapter 4 begins with the development of a rapid mixing device for use in real-time NMR and CIDNP studies. Experiments used to characterise the device are presented. This chapter then goes on to describe CIDNP pulse labelling experiments, used to investigate the surface structure of some molten globule states of two a-lactalbumins. This chapter concludes with an application of the rapid mixing device to the real-time refolding of hen egg white lysozyme. Chapter 5 extends the work of the previous chapter, studying the real-time refolding of bovine pancreatic ribonuclease A. Refolding studies are performed from different denaturing conditions, and the effects of sample heating during the real-time CIDNP experiment are discussed. Chapter 6 describes the use of illumination during an NMR experiment to study the conformational changes in a plant blue light receptor protein, phototropin. The structural changes are characterised with 2-dimensional NMR spectroscopy and photo-CIDNP. The kinetics of the ground state recovery are also investigated by real-time NMR spectroscopy. Chapter 7 uses calculated hyperfine coupling constants and a radical pair diffusion model from the literature to simulate the nuclear polarisation obtained for the amino acid tryptophan. Comparisons are made between theory and experiment. Chapter 8 describes the structural characterisation of a homologous series of de novo peptides, designed for subsequent use in EPR experiments when derivatised with a suitable spin label.

The product state specific stereodynamics of the photon–initiated reaction of O(¹D₂) with H₂ has been investigated by polarised Doppler–resolved laser induced fluorescence, under room temperature bulb conditions. Product state resolved differential cross sections, excitation functions and rotational angular momentum alignments are reported for the following product channels, O(¹D₂) + H₂(¹Σ⁺_g ; v = 0) -> OH(X²Pi; v' = 0;N' = 14; f) + H(²S). at a mean collision energy of 12 kJ mol^-1. The data are compared with extensive state resolved quasi–classical trajectory (QCT) calculations of the linear and angular momentum distributions and excitation functions conducted on the Schinke–Lester (SL1) and K ab initio ground state (1¹A') potential energy surfaces. Overall, good agreement is obtained between the QCT calculated and experimentally determined stereodynamical features. The results are discussed in light of other recent work on this prototypical insertion reaction, and on the related systems of O(¹D₂) + HD and CH₄.

A complete renormalization scheme for the Glashow-Salam-Weinberg model is presented. As input parameters the scheme uses the fine structure constant, α, the muon decay constant, G_μ and the Z° mass, M_Z which are known or will be measured to high accuracy in the near future. These are used along with the Higgs and fermion masses to obtain the W mass, M_W. The full one-loop weak radiative corrections to the longitudinal polarization asymmetry, A_pol, and the forward-backward asymmetry, A_fb, in e⁺e^- → μ⁺μ^- are then calculated both on and off resonance. On resonance the results depend extremely sensitively on the Z mass, M_Z, and to a lesser extent on the top quark mass, m_t, and the Higgs mass, M_H, showing that this is a good place to test the standard model at the one loop level. The results are displayed over the full range of the parameters allowed by experimental and theoretical constraints. It is suggested that sufficiently accurate experiments may be able to set an upper bound on one of m_t or M_H if the other is known. It is noted that on resonance A_pol is only weakly dependent on the beam pipe and on the nature of the outgoing fermions. Comparison is made with other calculations of A_fb and the agreement is found to be good. The predictions are also compared with measurements of A_fb off resonance and are found in all cases to lie within the experimental errors. Previous analyses that indicated a possible discrepancy are shown to be incorrect.

No description available.