Chemistry

Ruthenium-diimine sensitizers (Ru-wires) with the structure [Ru(L2)L ]2+, where L is a perfluorobiphenyl bridge connecting 4,4 -dimethylbipyridine to the substrate adamantane or the heme ligand imidazole, bind to cytochrome P450cam with micromolar dissociation constants. Ru-wires can be used to trigger redox reactions on timescales faster than those achievable using conventional stopped-flow techniques: photoinduced heme reduction with an imidazole-terminated Ru-wire occurs in 40 ns. The large v...

Computer Science

Finite element solvers are critical in computer graphics, engineering, medical and biological application areas. For large problems, the use of adaptive refinement methods can tame otherwise intractable computational costs. Current formulations of adaptive finite element mesh refinement seem straightforward, but their implementations prove to be a formidable task. We offer an alternative point of departure which yields equivalent adapted approximation spaces wherever the traditional mesh refinem...

Environmental Science and Engineering

Stratospheric sulfate aerosols (SSA) play an important part in regulating the climate of the earth and in the maintenance of important stratospheric species, including stratospheric ozone. The sources of stratospheric sulfate aerosol sulfur remain an unresolved issue because of uncertainties in the global sulfur budget and model limitations. The origins of SSA particles should be reflected in their isotopic composition. In this thesis project, the sulfur isotopic fractionation factors of process...

Social Science

I estimate the effects of uncertainty about candidates ideological positions and institutionally imposed costs of voting on the likelihood that an individual turns out and votes. I do this using a simple model of turnout and vote choice that reflects the combined, simultaneous nature of vote decision-making. I show that the impact of eliminating the registration deadline and instituting DMV registration in the 1972-2000 presidential elections would have been less than that of eliminating uncerta...

Control and Dynamical Systems

With the advent of powerful computing and efficient computational algorithms, real-time solutions to constrained optimal control problems are nearing a reality. In this thesis, we develop a computationally efficient Nonlinear Trajectory Generation (NTG) algorithm and describe its software implementation to solve, in real-time, nonlinear optimal trajectory generation problems for constrained systems. NTG is a nonlinear trajectory generation software package that combines nonlinear control theory,...

Social Science

I present three models of dynamic agenda formation and policy selection, and demonstrate that in each, outcomes emerge which are in keeping with those predicted by cooperative solution concepts such as the von Neumann-Morgenstern stable set and the core. These outcomes are a consequence of players ``thinking ahead, or conditioning how they bargain on the notion that policies selected today should stand up to tomorrow s agenda. Players are induced into taking the payoffs of others into account wh...

Geological and Planetary Sciences

I use interferometric synthetic aperture radar (InSAR) to create maps of crustal deformation along the coast and within the volcanic arc of central South America. I image deformation associated with six subduction zone earthquakes, four volcanic centers, at least one shallow crustal earthquake, and several salt flats. In addition, I constrain the magnitude and location of post-seismic deformation from the afore-mentioned subduction zone earthquakes. I combine InSAR observations with data from th...

Geological and Planetary Sciences

Waveform and differential travel-time (DTT) of various PKP phases have been utilized to study the velocity variations at the core-mantle boundary (CMB) and the inner-core boundary (ICB). The spatial concentration of events and stations, and the significant variations in PKPab-PKPdf DTT and waveform of PKPab, indicate localized sharp lateral variation of velocity at the CMB as supported by simulations. Modeling of DTT s among PKiKP, PKIKP and PKP-B-diffracted ($B_{diff}$) phases, and waveform of ...

Physics

This thesis is focused on the development of micro-electromechanical systems (MEMS) in III-V nitride semiconductors, with a primary emphasis on gallium-nitride (GaN). Though GaN exhibits unique properties that make it an effective platform for MEMS devices, to date, this field of study has received almost no attention in the nitride community. As a result, the research outlined in this thesis represents the very first steps in the development of GaN for this application.A critical issue for the ...

Physics

Both the Laser Interferometer Gravitational Wave Observatory (LIGO) and the Laser Interferometer Space Antenna (LISA) will over the next decade detect gravitational waves emitted by the motion of compact objects (e.g. black hole and neutron star binaries). This thesis presents methods to improve (i) LIGO detector quality, (ii) our knowledge of waveforms for certain LIGO and LISA sources, and (iii) models for the rate of detectability of a particular LISA source.1) Plunge of compact object into a...

Applied Mathematics

Optical coherence tomography (OCT) is a non-invasive imaging technique based on the use of light sources exhibiting a low degree of coherence. Low coherence interferometric microscopes have been successful in producing internal images of thin pieces of biological tissue; typically samples of the order of 1 milimeter in depth have been imaged, with a resolution of the order of 10 to 20 microns in some portions of the sample. In this thesis, I deal with the imaging problem of determining the inter...

Physics

This thesis describes the design and observations with the Bolocam instrument. Bolocam is a 144-element bolometer array designed to detect the Sunyaev Zel dovich effect, used at the Caltech Submillimeter Observatory. Bolocam can be configured to observe at 1.1, 1.4, and 2.1 mm. We conducted a galaxy cluster survey at 2.1 mm, where clusters are detected as decrements against the Cosmic Microwave Background. The survey consisted of two blank fields, for a total of one square degree of coverage. We...

Biology

Neural crest cells are unique to vertebrates and generate most of the adult structures that distinguish them from their closest invertebrate relatives, the cephalochordates. To elucidate the molecular bases of neural crest evolution, I analyzed the expression, function, and cis-regulation of amphioxus genes with vertebrate homologs having established roles in neural crest development. By comparing these amphioxus genes with their agnathan and gnathostome homologs, I have uncovered genetic change...

Aeronautics

The conical transformation of variables of M.D. Haskind and S. V. Falkovich is applied to the steady-state problem of thin delta wings with subsonic leading edges in a supersonic flow. It is shown that solutions may be obtained, in terms of elliptic functions, for lifting wings of zero thickness with prescribed angle-of-attack distribution, and for symmetric non-lifting where the perturbation pressure is prescribed on the wing surface (thickness case, mean-surface assumption); the wing boundary ...

Geological and Planetary Sciences

I present an analysis of visible and near-infrared adaptive optics images and spectra of Titan taken over 43 nights between October 1997 and January 2003 with the AEOS 3.6-m, Palomar Hale 5-m, and W.M. Keck 10-m telescopes. These observations reveal a seasonally changing stratospheric haze layer, two distinct regions of condensate clouds in the southern hemisphere, the albedo of Titan s surface, and the zonal wind field of the stratosphere.Transient convective CH<sub>4</sub&...

Chemistry

The development of a new iminium-activation approach towards asymmetric organic catalysis is described. This strategy has been successfully applied to a 1,3-dipolar cycloaddition reaction to produce the first enantioselective catalytic [3+2]cycloaddition between nitrones and a,b-unsaturated aldehydes. This methodology highlights the ability of this new organocatalytic strategy to access chemical transformations not attainable though traditional Lewis acid catalysis.We have also applied this imin...

Aeronautics

Contributions to vortex methods for the computation of incompressible unsteady flows are presented. Three methods are investigated, both theoretically and numerically.The first method to be considered is the inviscid method of vortex filaments in three dimensions, and the following topics are presented: (a) review of the method of regularized vortex filaments and of convergence results for multiple-filament computations, (b) modeling of a vortex tube by a single filament convected with the regul...

Aeronautics

This dissertation is concerned with the development of a general computational framework for mesh adaption such as is required in the three-dimensional lagrangian finite element simulation of strongly nonlinear, possibly dynamic, problems. It is shown that, for a very general constitutive framework, the solutions of the incremental boundary value problem obey a minimum principle, provided that the constitutive updates are formulated appropriately. This minimum principle is taken as a basis for a...

Aeronautics

The electromagnetic wave equations for the fields, potentials and Hertz vectors are derived and a Lorentz gauge is given for space-time dependent media. Electromagnetic wave propagation, electric and magnetic dipole radiation, and Cerenkov and transition radiation in sinusoidally space-time periodic dielectric, plasma and uniaxial plasma are studied and numerous radiation patterns are given. A special radiation effect in the uniaxial plasma is investigated. Finally the study is extended to gener...

Aeronautics

The present work starts with a study of isotropic turbulence which was introduced by G. I. Taylor in 1935. The different notions of averages are critically examined. The notion of stochastic average is then introduced and the general transport equation is developed. After a detailed study of kinematics of turbulence, the concept of correlation and spectrum, the correspondence between the Karman-Howarth equation and the spectrum equation is made. The turbulence decay is studied. A theory for turb...

Engineering and Applied Science

The present finite element study addresses several issues of interest pertaining to the phenomenon of dynamic crack propagation in elastic-plastic solids. Three classes of materials, namely elastic-perfectly plastic materials, linear hardening materials and power-law hardening materials, are considered. The materials are assumed to obey the von Mises yield criterion and the associated flow rule.Under conditions of Mode I, plane stress, steady state and small scale yielding, we investigated the s...

Applied Mechanics

NOTE: Text or symbols not renderable in plain ASCII are indicated by[...]. Abstract is included in .pdf document.A detailed finite element analysis of crack initiation and stable crack extension is performed under Mode I plane stress, small-scale yielding conditions. A small strain, J[subscript 2] incremental plasticity theory is employed and both elastic-perfectly plastic materials and power law hardening materials are considered.Some issues pertaining to the stationary plane stress crack probl...

Chemistry

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.PART ISelective [superscript 13]C enrichment of C-2 of the single histidine residue of the serine protease [alpha]-lytic protease has allowed direct study of the Asp-His-Ser catalytic triad by magnetic resonance techniques. Both the chemical shift of C-2 and the coupling between C-2 and its directly bonded hydrogen have been observed as a function of pH. The results indicate that onl...

Aeronautics

With the very rapid development of jet propulsion systems, the attainment of speeds which seemed to be well beyond reach a few years ago now appears to be at hand. The war has produced many examples of guided missiles traveling at supersonic speeds such as the famed German A-4 rocket, more commonly referred to in this country as the V-2. Today a supersonic airplane is no longer a designer s dream but practically an accomplished fact. Despite the impressive array of symbols of apparent mastery of...

Aeronautics

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.In Part I, the integral method of Lees and Reeves is applied to study a supersonic laminar boundary layer along a two-dimensional adiabatic curved ramp. The present method of solution requires no prior knowledge of the separation point and can be used to treat relatively weak interaction, including a fully attached flow. It starts with small perturbations of the self-induced interact...

Physics

Part I.The theory of time-independent accretion disks around compact objects is developed, generalizing the stationary models of various authors to allow time dependence on the radial-flow time scale. Equations are derived for the time evolution of matter surface density [Sigma] and for implicit expressions of relevant disk variables in terms of [Sigma]. Analytic and numerical studies of these equations yield numerical models of mass accretion from a disk onto a compact object and a discovery of...

Engineering and Applied Science

PART I.Closed form solutions have been derived for the focal plane diffraction patterns of (a) a convergent spherical wave illuminating a segment of a circular aperture and (b) a convergent Gaussian beam diffracted by an infinite edge. The theoretical results agree with the experiments showing that the edge produces a spike of light with intensity variation inversely proportional to the squared distance from the center, that the pattern is symmetric in the focal plane, and that in the case of th...

Aeronautics

In the flow over the upper surface of a wing, a discrepancy between the predicted and actual point of transition from laminar to turbulent boundary layer had been found. This effect may be due to the comparatively small radius of curvature of the upper surface of the wing. The present tests were undertaken to investigate this effect.As no available channel was suitable for this work, a new channel with two working sections was built. One working section had a wall with a twenty inch radius of cu...

Aeronautics

In the flow over the upper surface of a wing, a discrepancy between the predicted and actual point of transition from laminar to turbulent boundary layer had been found. This effect may be due to the comparatively small radius of curvature of the upper surface of the wing. The present tests were undertaken to investigate this effect.As no available channel was suitable for this work, a new channel with two working sections was built. One working section had a wall with a twenty inch radius of cu...

Aeronautics

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.The usual equations for the flow of a compressible fluid are non-linear in character and difficult to solve. It has been found that if the components of velocity are taken as independent variables, the resulting equations are linear. These equations are developed and new forms introduced.A new function, [] is introduced and a method advanced for effecting the transformation from the ...

Aeronautics

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.The usual equations for the flow of a compressible fluid are non-linear in character and difficult to solve. It has been found that if the components of velocity are taken as independent variables, the resulting equations are linear. These equations are developed and new forms introduced.A new function, [] is introduced and a method advanced for effecting the transformation from the ...

Chemistry

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.The enzyme-inhibitor dissociation constants, i. e. , K[subscript I] values, for alpha-chymotrypsin and two competitive inhibitors, indole-2-carboxylate and cinchoninamide, have been determined at pH 7. 9 and 25[degrees].A new colorimetric procedure for the determination of proteolytic activity employing the reaction of ninhydrin with ammonia has been developed.A study has been made o...

Chemistry

A general, systematic approach for calculating accurate energetics for chemical processes within the framework of ab initio electronic structure theory is presented. The correlation-consistent configuration interaction (CCCI) method utilizes generalized valence bond wavefunctions as the starting point for the CI, which emphasizes the inclusion of only the dominant correlations dictated by the physics of the problem. The CI expansion truncates quickly, so that processes involving polyatomic molec...

Applied Physics

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.This thesis presents investigations of novel semiconductor heterostructure devices based on quantum mechanical tunneling. Due to their small characteristic dimensions, these devices have extremely fast charge transport properties. Thus, it is expected that tunnel structure devices will be well-suited to high frequency and optoelectronic applications. The work presented here can be di...

Physics

This thesis describes a number of advancements in the III-V nitride material system achieved at Caltech. Major improvements in optimized growth of III-V nitride materials by radio frequency molecular beam epitaxy are presented. The first GaN based MEMs devices are reported, and their fabrication and characterization are detailed. The growth of InN is discussed, and the morphology and crystal quality are presented. In addition, the switching behavior of the first GaN thyristor is reported. The su...

Aeronautics

The process of stall propagation in an axial flow compressor is represented by nonlinear airfoil lift and drag characteristics, with a time lag associated with the stalling mechanism. A pair of nonlinear integro-differential equations express the lift and drag as a function of time for a given airfoil in an isolated plane cascade representing an annulus with only a finite number of blades. Approximate solutions of these integro-differential equations are obtained by considering only the fundamen...

Engineering and Applied Science

This thesis presents a method for the solution of the supersonic flutter problem for elastic delta wings with supersonic leading edges.In Part I, the necessary aerodynamic equations are developed, first in integral form, and then in a power series expansion in order to obtain a practical expression for the pressure at a point on the wing due to the motion of the wing surface in a supersonic air stream.Part II gives a method for computing the lifts on a partitioned wing, and sets up cell division...

Engineering and Applied Science

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.Picosecond time-resolved rotational coherence spectroscopy is developed as a probe of excited state rotational level structure and alignment. The measurement technique employs a combination of supersonic cooling by molecular beam expansion, coherent picosecond pulsed laser excitation, and time-resolved and polarization-analyzed detection of spectrally dispersed fluorescence. The requ...

Chemistry

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.The rates of dissociation of I[subscript 2] in N[subscript 2] and CO[subscript 2], and Br[subscript 2] in A were measured at temperatures around 1300[degrees]K by heating room temperature mixtures by means of shock waves and observing the subsequent reactions. The rates of recombination of both I[subscript 2] and Br[subscript 2] were found to decrease with increasing temperature. The...

Chemistry

This dissertation presents two techniques for ultrasensitive high-resolution nuclear magnetic resonance. The first exploits the spin order inherent in spin-symmetry enriched H2 to achieve orders of magnitude improvement in the sensitivity of surface NMR over traditional techniques. The second uses a Larmor beat method to allow real-time optical detection of NMR transients in single epitaxial heterostructures and achieves orders of magnitude improvement in spectral resolution over previous steady...

Physics

Experiments are described as performed with a twenty channel pair spectrometer. This instrument uses a 30 ton electromagnet to measure the energies of electron pairs produced by electromagnetic quanta, giving a measurement of the energies of the quanta. These electron pairs are detected by a V shaped array of scintillators located within the magnet gap. A novel network of coincidence circuits, due to Matthew L. Sands, results in a considerable reduction in electronics complexity. With this spect...

Chemical Engineering

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.Equipment is described that was used in making velocity and temperature measurements at various points within an air stream flowing in a smooth, rectangular channel 0.675 inch in height, 12 3/8 inches in width, and 162 inches in length. The aspect ratio of the channel was such that flow along the center line was essentially two-dimensional. In addition to equipment for velocity and t...

Aeronautics

A thermal theory of laminar flame propagation for hydrocarbon-oxygen flames is described. The method of analysis follows the earlier work of von Karman and his collaborators. The problem is greatly simplified by the introduction of several approximations and assumptions.In Section III the problem is formulated and approximate solutions are given for hydrocarbon-oxygen flames, assuming a second order rate-controlling step. Approximate analytic solutions have been obtained for all mixture ratios.H...

Engineering and Applied Science

This thesis is a general investigation of some of the properties of free and forced vibrations in linear, non-conservative systems. Particular emphasis is placed upon the problems which arise in normal mode studies made on the electric analog computer at the California Institute of Technology.In Part I the major problems are defined, and limitations of the study are discussed. Part II is a review of the basic theory of normal modes included primarily to establish familiarity with the notation to...

Chemistry

In Part I the determination of the structure of oxygen fluoride by the method of electron diffraction is described.In Part II the calculation of complex atomic scattering amplitudes and their ease in electron diffraction is discussed. Section A provides an outline of the theory and a summary of the calculations which have been made. In Section B some experimental work, the failure of the Born approximation, and the early calculations are described. In Section C the calculation of complex atomic ...

Aeronautics

This research consists in the experimental and theoretical investigation of the finite deflection and buckling of two similar structures; the low arch or slightly curved beam and the shallow spherical dome, both subjected to lateral loads. These structures are of interest because the large interaction between bending and axial forces causes their load-deflection behavior to become nonlinear at very low values of the deflection. Due to the wide difference in the methods of solution of these two p...

Aeronautics

A simplified theoretical treatment has been developed for the burning of single drops of monopropellants. Evaporation constants and the ratios of flame to droplet radii have been calculated for the following monopropellants burning in an inert atmosphere: hydrogen peroxide, nitromethane, hydrazine, ethylene oxide, ozone and nitrous oxide. Compared with the results of similar calculations for fuels burning in air, much smaller flame radii were obtained, while the evaporation constants were found ...

Chemistry

The addition of water to the triple bond of 3-hexyne catalyzed by sulfuric acid and mercuric sulfate was studied. The aqueous hexyne was found to undergo mercury-catalyzed autoxidation. The product of the hydration reaction, 3-hexanone, was shown by spectrophotometric methods to react with mercuric sulfate to form a stable complex. The production of 3-hexanone was followed spectrophotometrically and the rate was found to be approximately first order with respect to 3-hexyne, hydrogen ion, and me...

Biology

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.1. The requirement for floral initiation in Cestrum nocturnum is satisfied if plants receive long days followed by short days. Continuous short or long days or short days preceding long days are ineffective.2. A minimum of 5-7 long days followed by two short days is required for the production of flowers.3. The sequence of reactions necessary for floral initiation in Cestrum is as fo...

Physics

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.A photoelectric method for the measurement of ionization of cloud chamber tracks has been developed. The principal feature of the method is the use of a comparison track of known ionization in the same part of the chamber. A microphotometer slit is made to scan the track perpendicular to its direction and a tracing of the transmission of the track relative to the background transmiss...