Constructing Reference Metrics on Multicube Representations of Arbitrary Manifolds

Reference metrics are used to define the differential structure on multicube representations of manifolds, i.e., they provide a simple and practical way to define what it means globally for tensor fields and their derivatives to be continuous. This paper introduces a general procedure for constructing reference metrics automatically on multicube representations of manifolds with arbitrary topologies. The method is tested here by constructing reference metrics for compact, orientable two-dimensional manifolds with genera between zero and five. These metrics are shown to satisfy the Gauss-Bonnet identity numerically to the level of truncation error (which converges toward zero as the numerical resolution is increased). These reference metrics can be made smoother and more uniform by evolving them with Ricci flow. This smoothing procedure is tested on the two-dimensional reference metrics constructed here. These smoothing evolutions (using volume-normalized Ricci flow with DeTurck gauge fixing) are all shown to produce reference metrics with constant scalar curvatures (at the level of numerical truncation error).Comment: 37 pages, 16 figures; additional introductory material added in version accepted for publicatio

Enumerating Flux Vacua with Enhanced Symmetries

We study properties of flux vacua in type IIB string theory in several simple but illustrative models. We initiate the study of the relative frequencies of vacua with vanishing superpotential W=0 and with certain discrete symmetries. For the models we investigate we also compute the overall rate of growth of the number of vacua as a function of the D3-brane charge associated to the fluxes, and the distribution of vacua on the moduli space. The latter two questions can also be addressed by the statistical theory developed by Ashok, Denef and Douglas, and our results are in good agreement with their predictions. Analysis of the first two questions requires methods which are more number-theoretic in nature. We develop some elementary techniques of this type, which are based on arithmetic properties of the periods of the compactification geometry at the points in moduli space where the flux vacua are located.Comment: 83 pages, 8 figures, harvmac. v2: references added, typos fixed, brief discussion of complex conjugation in sec. 5 adde

An organism of words body language in the letters, diaries, and novels of D. H. Lawrence and Virginia Woolf

This thesis investigates body language in the letters, diaries, and novels of D. H. Lawrence and Virginia Woolf It engages with literary critical readings of their work, research from non-verbal communication studies, and philosophical accounts of the body in order to offer detailed readings of their presentation of non-verbal behaviour. Throughout the thesis, the term "body language" is used to describe the writing of the body and non-verbal communication within certain texts and the way in which the language of these texts is inflected by the body. One particular concern of the study is the importance of embodiment to the writing of perception in these works. The phenomenological writing of Maurice Merleau-Ponty is therefore a touchstone for readings which foreground the senses and a sensuous engagement with space. This strand of the thesis is informed by theories of space as well as situating itself amongst contemporary accounts of the Modern period that consider the influence of technology on these very senses. A further concern of the thesis, then, is to examine the vocabulary developed and employed by these Modern writers in order to write this new relationship of the human with technology and space. Their turn towards a posthuman poetics of perception gives voice to these new imbrications and to their appraisal, through the senses, of what it means to be human. This is in keeping with the general purpose of the thesis, namely, to evaluate the techniques and styles that these authors use in order to write the body and body language, ones in which they confront the paradox of writing non-verbal behaviour within their inherently verbal modes

String universality in ten dimensions

We show that the ${\cal N}=1$ supergravity theories in ten dimensions with gauge groups $U(1)^{496}$ and $E_8 \times U(1)^{248}$ are not consistent quantum theories. Cancellation of anomalies cannot be made compatible with supersymmetry and abelian gauge invariance. Thus, in ten dimensions all supersymmetric theories of gravity without known inconsistencies are realized in string theory.Comment: 7 pages, 1 figure, LaTeX. v2: typos corrected on version appearing in PR

S18RS SGFB No. 8 (Rentable Chargers)

A FINANCE BILL To allocate a maximum of two hundred fifty-nine dollars and eighty cents ($259.80) from the Student Government Initiatives Account to fund rentable chargers for the LSU Student Union Information Des

How different can h-cobordant manifolds be?

We study the homeomorphism types of manifolds h-cobordant to a fixed one. Our investigation is partly motivated by the notion of special manifolds introduced by Milnor in his study of lens spaces. In particular we revisit and clarify some of the claims concerning h-cobordisms of these manifolds.Comment: 16 pages. Typo corrected and reference adde

Growth and optical characterisation of multilayers of InGaN quantum dots

We report on the growth (using metal-organic vapour phase epitaxy) and optical characterization of single and multiple layers of InGaN quantum dots (QDs), which were formed by annealing InGaN epilayers at the growth temperature in nitrogen. The size and density of the nanostructures have been found to be fairly similar for uncapped single and three layer QD samples if the GaN barriers between the dot layers are grown at the same temperature as the InGaN epilayer. The distribution of nanostructure heights of the final QD layer of three is wider and is centred around a larger size if the GaN barriers are grown at two temperatures (first a thin layer at the dot growth temperature, then a thicker layer at a higher temperature). Micro-photoluminescence studies at 4.2 K of capped samples have confirmed the QD nature of the capped nanostructures by the observation of sharp emission peaks with full width at half maximum limited by the resolution of the spectrometer. We have also observed much more QD emission per unit area in a sample with three QD layers, than in a sample with a single QD layer, as expected

Modulation of CXCR4, CXCL12, and Tumor Cell Invasion Potential In Vitro by Phytochemicals.

CXCR4 is a chemokine receptor frequently overexpressed on primary tumor cells. Organs to which these cancers metastasize secrete CXCL12, the unique ligand for CXCR4, which stimulates invasion and metastasis to these sites. Similar to our previous work with the chemoprotective phytochemical, 3,3'-diindolylmethane (DIM), we show here that genistein also downregulates CXCR4 and CXCL12 and subsequently lowers the migratory and invasive potentials of breast and ovarian cancer cells. Moreover, genistein and DIM elicit a significantly greater cumulative effect in lowering CXCR4 and CXCL12 levels than either compound alone. Our data suggest a novel mechanism for the protective effects of phytochemicals against cancer progression and indicate that in combination, these compounds may prove even more efficacious