We begin with a result on the refocussing of null geodesics in space-times. We show that all oriented refocussing 2-dimensional Lorentz manifolds are also strongly refocussing. We also introduce a theory of virtual Legendrian knots. We show that...
While anthropogenic emissions of the toxic element mercury (Hg) to the atmosphere are currently rising, major uncertainties remain in determining the relative impacts of anthropogenic activity and natural processes on the global Hg cycle. In this...
The Greenland Ice Sheet (GrIS) is responding sensitively to climate change and its meltwater has the potential to influence global sea level. Recently, large changes in the GrIS have occurred including increased velocities of outlet glaciers and...
This thesis constitutes the first steps in the author's program to investigate the question of when a homotopy of 2-cocycles ω = {ω[subscript t]}[subscript t∊[0,1]] on a locally compact Hausdorff groupoid Ɠ induces an isomorphism of the...
A series of conformationally restricted bis(9-amino-acridine) derivatives were designed, synthesized, and then evaluated for their chemical and biological behavior. The novel compounds were prepared by treating selected diamines with a...
Medical imaging methods have become increasingly important in diagnosing diseases and assisting therapeutic treatment. In particular, early detection of breast cancer is considered as a critical factor in reducing the mortality rate of women....
Polynomials. Finite fields (Algebra). Algebraic functions. Number theory.
The ring of univariate polynomials over a finite field shares many foundational arithmetic properties with the ring of rational integers. This similarity makes it possible for many problems in elementary number theory to be translated 'through the...
In this thesis we study 1=k-geodesics, those closed geodesics that minimize on any subinterval of length L=k, where L is the length of the geodesic. These curves arise as critical points of the uniform energy, a function introduced in Morse theory...
For ordinary knots in R 3 , there are no degree one Vassiliev invariants. For virtual knots, however, the space of degree one Vassiliev invariants is infinite dimensional. We introduce a sequence of three degree one Vassiliev invariants of virtual...
The new APM South Equatorial Strip Catalog $({-}17\sp\circ.5<\delta<2\sp\circ.5)$ is used to select a sample of early-type galaxies in three directions: (1) 15h10-16h10; (2) 20h30-21h50; (3) 00h10-01h30. The distances and peculiar motions of...
Motivated by quantum mechanics and geometric optics, it is a long-standing problem whether the length spectrum of a compact Riemannian manifold can be recovered from its Laplace spectrum. One route to proving that the length spectrum depends on the...
In this thesis, we present different approaches to tying knots using robots by enforcing different types of constraints. We attack the problem from three different directions; mechanical design, motion planning with simple control strategies, and...
In this thesis we develop a theory of Fourier analysis and fast Fourier transforms (FFTs) for finite inverse semigroups. Our results generalize results in the theory of Fourier analysis for finite groups. There is a general method for generating...
Partially ordered sets and permutations are combinatorial structures having vast applications in theoretical computer science. In this thesis, we study various computational and algorithmic problems related to these structures. The first chapter of...
We study motion planning problems, finding trajectories that connect two configurations of a system, from two different perspectives: optimality and survivability. For the problem of finding optimal trajectories, we provide a model in which the...
CD antigens. T cells -- Receptors. Receptor-ligand complexes. Transplantation immunology. Immunological tolerance -- Molecular aspects. Antigens
Voltage-dependent sodium channels (Na v ) are critical determinants of the ability of a neuron to generate and propagate action potentials. While a large family of Na v isoforms has been identified, the impact of specific isoforms on the electrical...
Coding theory. Characters of groups. Error-correcting codes (Information theory). Polynomials.
We introduce vector-valued character theory, a higher dimensional generalization of character theory. We then use vector-valued characters to extend the MacWilliams equivalence theorem for linear codes to a class of additive codes, called...
Monocytes and macrophages play a key role in a number of immune functions including inflammation, antigen presentation and the clearance of microorganisms and free hemoglobin. Two surface receptors which are important for these functions are CD163...
Infections by pathogenenic microbes are an increasing problem due to a lack of universal vaccines and growing resistance to current antibiotics. The constant battle for researchers in the fight against pathogens is to design new and improved drugs...
Order picking systems -- Automation -- Computer simulation.
This research ventures into areas beyond traditional control frameworks in its focus. It integrates holonic concepts into a hierarchical control framework of a complex automated order fulfillment technology. Simulation of an actual full-scale order...
Plants -- Effect of iron on. Iron -- Metabolism -- Molecular aspects. Chloroplasts. Plant mitochondria. Homeostasis. Plant enzymes. Reduction (Chemistry). Iron chelates.
Manifolds (Mathematics) Geodesics (Mathematics) Space and time.
We investigate weak and strong refocusing of light rays in a space-time and related concepts. A strongly causal space-time ( X^ n +1 , g ) is emphstrongly refocusing at x ∈ X if there is a point y ≠ x such that all null-geodesics through y pass...