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An Investigation Of Modified Superconductivity Through Structural Alteration Of Mgcni3 And Mgb2, Nathan L. Henderson Apr 2005

An Investigation Of Modified Superconductivity Through Structural Alteration Of Mgcni3 And Mgb2, Nathan L. Henderson

Honors Capstones

No abstract provided.

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Consistent Discretization And Loop Quantum Geometry, Rodolfo Gambini, Jorge Pullin Mar 2005

Consistent Discretization And Loop Quantum Geometry, Rodolfo Gambini, Jorge Pullin

Faculty Publications

We apply the "consistent discretization" approach to general relativity leaving the spatial slices continuous. The resulting theory is free of the diffeomorphism and Hamiltonian constraints, but one can impose the diffeomorphism constraint to reduce its space of solutions and the constraint is preserved exactly under the discrete evolution. One ends up with a theory that has as physical space what is usually considered the kinematical space of loop quantum geometry, given by diffeomorphism invariant spin networks endowed with appropriate rigorously defined diffeomorphism invariant measures and inner products. The dynamics can be implemented as a unitary transformation and the problem of …

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Consistent And Mimetic Discretizations In General Relativity, Cayetano Di Bartolo, Rodolfo Gambini, Jorge Pullin Mar 2005

Consistent And Mimetic Discretizations In General Relativity, Cayetano Di Bartolo, Rodolfo Gambini, Jorge Pullin

Faculty Publications

A discretization of a continuum theory with constraints or conserved quantities is called mimetic if it mirrors the conserved laws or constraints of the continuum theory at the discrete level. Such discretizations have been found useful in continuum mechanics and in electromagnetism. We have recently introduced a new technique for discretizing constrained theories. The technique yields discretizations that are consistent, in the sense that the constraints and evolution equations can be solved simultaneously, but it cannot be considered mimetic since it achieves consistency by determining the Lagrange multipliers. In this paper we would like to show that when applied to …

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Dirac-Type Approach For Consistent Discretizations Of Classical Constrained Theories, Cayetano Di Bartolo, Rodolfo Gambini, Rafael A. Porto, Jorge Pullin Mar 2005

Dirac-Type Approach For Consistent Discretizations Of Classical Constrained Theories, Cayetano Di Bartolo, Rodolfo Gambini, Rafael A. Porto, Jorge Pullin

Faculty Publications

We analyze the canonical treatment of classical constrained mechanical systems formulated with a discrete time. We prove that under very general conditions, it is possible to introduce nonsingular canonical transformations that preserve the constraint surface and the Poisson or Dirac bracket structure. The conditions for the preservation of the constraints are more stringent than in the continuous case and as a consequence some of the continuum constraints become second class upon discretization and need to be solved by fixing their associated Lagrange multipliers. The gauge invariance of the discrete theory is encoded in a set of arbitrary functions that appear …

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New Bounds For Randomized Busing, Steven S. Seiden, Peter P. Chen, R. F. Lax, J. Chen, Guoli Ding Feb 2005

New Bounds For Randomized Busing, Steven S. Seiden, Peter P. Chen, R. F. Lax, J. Chen, Guoli Ding

Faculty Publications

We consider anonymous secure communication, where parties not only wish to conceal their communications from outside observers, but also wish to conceal the very fact that they are communicating. We consider the bus framework introduced by Beimel and Dolev (J. Cryptology 16 (2003) 25), where messages are delivered by a bus traveling on a random walk. We generalize this idea to consider more than one bus. We show that if w buses are allowed, then the expected delivery time for a message can be decreased from Θ(n) to Θ(n/w) in the case of a complete graph. Additionally, we introduce a …

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Racah Coefficients, Subrepresentation Semirings, And Composite Materials, Daniel S. Sage Feb 2005

Racah Coefficients, Subrepresentation Semirings, And Composite Materials, Daniel S. Sage

Faculty Publications

Typically, physical properties of composite materials are strongly dependent on microstructure. However, in exceptional situations, exact relations exist which are microstructure-independent. Grabovsky has constructed an abstract theory of exact relations, reducing the search for exact relations to a purely algebraic problem involving the multiplication of SO (3)-subrepresentations in certain endomorphism algebras. This motivates us to introduce subrepresentation semirings, algebraic structures which formalize subrepresentation multiplication. We study the ideals and subsemirings of these semirings, relating them to properties of the underlying G-algebra and proving classification theorems in the case of endomorphism algebras of representations. For SU (2), we compute these semirings …

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Resonant Transmission Near Nonrobust Periodic Slab Modes, Stephen P. Shipman, Stephanos Venakides Feb 2005

Resonant Transmission Near Nonrobust Periodic Slab Modes, Stephen P. Shipman, Stephanos Venakides

Faculty Publications

We present a precise theoretical explanation and prediction of certain resonant peaks and dips in the electromagnetic transmission coefficient of periodically structured slabs in the presence of nonrobust guided slab modes. We also derive the leading asymptotic behavior of the related phenomenon of resonant enhancement near the guided mode. The theory applies to structures in which losses are negligible and to very general geometries of the unit cell. It is based on boundary-integral representations of the electromagnetic fields. These depend on the frequency and on the Bloch wave vector and provide a complex-analytic connection in these parameters between generalized scattering …

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Compositions Of Theta Correspondences, Hongyu He Jan 2005

Compositions Of Theta Correspondences, Hongyu He

Faculty Publications

Theta correspondence θ over ℝ is established by Howe (J. Amer. Math. Soc. 2 (1989) 535). In He (J. Funct. Anal. 199 (2003) 92), we prove that θ preserves unitarity under certain restrictions, generalizing the result of Li (Invent. Math. 97 (1989) 237). The goal of this paper is to elucidate the idea of constructing unitary representation through the propagation of theta correspondences. We show that under a natural condition on the sizes of the related dual pairs which can be predicted by the orbit method (J. Algebra 190 (1997) 518; Representation Theory of Lie Groups, Park City, 1998, pp. …

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Petrology Of Indus River Sands: A Key To Interpret Erosion History Of The Western Himalayan Syntaxis, Eduardo Garzanti, Giovanni Vezzoli, Sergio Andò, Paolo Paparella, Peter D. Clift Jan 2005

Petrology Of Indus River Sands: A Key To Interpret Erosion History Of The Western Himalayan Syntaxis, Eduardo Garzanti, Giovanni Vezzoli, Sergio Andò, Paolo Paparella, Peter D. Clift

Faculty Publications

The Indus River has been progressively transformed in the last decades into a tightly regulated system of dams and channels, to produce food and energy for the rapidly growing population of Pakistan. Nevertheless, Indus River sands as far as the delta largely retain their distinct feldspar- and amphibole-rich composition, which is unique with respect to all other major rivers draining the Alpine-Himalayan belt except for the Brahmaputra. Both the Indus and Brahmaputra Rivers flow for half of their course along the India-Asia suture zone, and receive major contributions from both Asian active-margin batholiths and upper-amphibolite-facies domes rapidly exhumed at the …

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Central Invariants And Frobenius - Schur Indicators For Semisimple Quasi-Hopf Algebras, Geoffrey Mason, Siu Hung Ng Jan 2005

Central Invariants And Frobenius - Schur Indicators For Semisimple Quasi-Hopf Algebras, Geoffrey Mason, Siu Hung Ng

Faculty Publications

In this paper, we obtain a canonical central element νH for each semi-simple quasi-Hopf algebra H over any field k and prove that νH is invariant under gauge transformations. We show that if k is algebraically closed of characteristic zero then for any irreducible representation of H which affords the character χ, χ(νH) takes only the values 0, 1 or -1, moreover if H is a Hopf algebra or a twisted quantum double of a finite group then χ(νH) is the corresponding Frobenius-Schur indicator. We also prove an analog of a theorem of Larson-Radford for split semi-simple quasi-Hopf algebras over …

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Testing Conjectures About Morphological Diversity In Cichlids Of Lakes Malawi And Tanganyika, Prosanta Chakrabarty Jan 2005

Testing Conjectures About Morphological Diversity In Cichlids Of Lakes Malawi And Tanganyika, Prosanta Chakrabarty

Faculty Publications

The morphological diversity of Malawi and Tanganyika cichlids has often been qualitatively described, but rarely have hypotheses based on these descriptions been tested empirically. Using landmark based geometric morphometrics, shapes are analyzed independent of other aspects of the body form (e.g., size). The estimation of shape disparity, the quantitative measure of the variance of these raw shapes, can then be applied in order to objectively test hypotheses about morphological diversity. The shape disparity within and between different groups is explored as well as how it is partitioned within the cichlid body. Tanganyika cichlids are found to have significantly greater shape …

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Mitochondrial Variation In Bolivian Populations Of The Variable Antshrike (Thamnophilus Caerulescens), Robb T. Brumfield Jan 2005

Mitochondrial Variation In Bolivian Populations Of The Variable Antshrike (Thamnophilus Caerulescens), Robb T. Brumfield

Faculty Publications

The Variable Antshrike (Thamnophilus caerulescens) is arguably the most polytypic thamnophilid, with males ranging from almost entirely jet black to nearly white. The four subspecies that occur in Bolivia are strikingly divergent in male plumage: T. c. aspersiventer (black with white-barred belly), T. c. connectens (black back and bib with white belly), T. c. dinellii (gray throat and back with rufous belly), and T. c. paraguayensis (light gray with white belly). To assess the genetic structure of those taxa in Bolivia, sequence variation at the mitochondrial cytochrome-b gene was screened in 126 individuals collected across transects spanning the plumage and …

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Norleucine, A Natural Occurrence In A Novel Ergot Alkaloid Γ-Ergokryptinine, L. Cvak, A. Jegorov, P. Sedmera, I. Císařová, J. Čejka, B. Kratochvíl, S. Pakhomova Jan 2005

Norleucine, A Natural Occurrence In A Novel Ergot Alkaloid Γ-Ergokryptinine, L. Cvak, A. Jegorov, P. Sedmera, I. Císařová, J. Čejka, B. Kratochvíl, S. Pakhomova

Faculty Publications

A novel natural peptide ergot alkaloid γ-ergokryptinine containing norleucine has been isolated from ergot sclerotia of the field-growing parasitic fungus Claviceps purpurea CCM 8059. Its structure was deduced from the NMR and mass spectral data. The final structural proof was provided by the crystal structure determination, which is the first X-ray structure of a natural Nle-containing secondary metabolite. The conformations of three ergopeptinines: γ-ergokryptinine, ergoladinine, and α-ergokryptinine were compared. © Springer-Verlag 2005.

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Ethnicity And Human Genetic Linkage Maps, Eric Jorgenson, Hua Tang, Maya Gadde, Mike Province, Mark Leppert, Sharon Kardia, Nicholas Schork, Richard Cooper, D. C. Rao, Eric Boerwinkle, Neil Risch Jan 2005

Ethnicity And Human Genetic Linkage Maps, Eric Jorgenson, Hua Tang, Maya Gadde, Mike Province, Mark Leppert, Sharon Kardia, Nicholas Schork, Richard Cooper, D. C. Rao, Eric Boerwinkle, Neil Risch

Faculty Publications

Human genetic linkage maps are based on rates of recombination across the genome. These rates in humans vary by the sex of the parent from whom alleles are inherited, by chromosomal position, and by genomic features, such as GC content and repeat density. We have examined-for the first time, to our knowledge-racial/ethnic differences in genetic maps of humans. We constructed genetic maps based on 353 microsatellite markers in four racial/ethnic groups: whites, African Americans, Mexican Americans, and East Asians (Chinese and Japanese). These maps were generated using 9,291 subjects from 2,900 nuclear families who participated in the National Heart, Lung, …

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Components, Volume 1 (2005), Lsu Center For Computation & Technology Jan 2005

Components, Volume 1 (2005), Lsu Center For Computation & Technology

Components

No abstract provided.

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Equations Of Parametric Surfaces With Base Points Via Syzygies, William A. Adkins, J. William Hoffman, Hao Hao Wang Jan 2005

Equations Of Parametric Surfaces With Base Points Via Syzygies, William A. Adkins, J. William Hoffman, Hao Hao Wang

Faculty Publications

Let S be a tensor product parametrized surface in P ; that is, S is given as the image of φ : P × P → P . This paper will show that the use of syzygies in the form of a combination of moving planes and moving quadrics provides a valid method for finding the implicit equation of S when certain base points are present. This work extends the algorithm provided by Cox [Cox, D.A., 2001. Equations of parametric curves and surfaces via syzygies. In: Symbolic Computation: Solving Equations in Algebra, Geometry, and Engineering. Contemporary Mathematics vol. 286, pp. …

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Some Aspects Of Jonathan Swift's Perspective On Language, W. K. Percival Jan 2005

Some Aspects Of Jonathan Swift's Perspective On Language, W. K. Percival

1650-1850: Ideas, Aesthetics, and Inquiries in the Early Modern Era

No abstract provided.

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Rambler And Cully Rochester's Satire And The Self-Presentation Of The Restoration Rake, John O'Neill Jan 2005

Rambler And Cully Rochester's Satire And The Self-Presentation Of The Restoration Rake, John O'Neill

1650-1850: Ideas, Aesthetics, and Inquiries in the Early Modern Era

No abstract provided.

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Book Reviews Jan 2005

Book Reviews

1650-1850: Ideas, Aesthetics, and Inquiries in the Early Modern Era

No abstract provided.

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The Epoch Of The Constellations On The Farnese Atlas And Their Origin In Hipparchus's Lost Catalogue, E. Bradley Schaefer Jan 2005

The Epoch Of The Constellations On The Farnese Atlas And Their Origin In Hipparchus's Lost Catalogue, E. Bradley Schaefer

Faculty Publications

No abstract provided.

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Composite Cosine Transforms, E. Ournycheva, B. Rubin Jan 2005

Composite Cosine Transforms, E. Ournycheva, B. Rubin

Faculty Publications

The cosine transforms of functions on the unit sphere play an important role in convex geometry, Banach space theory, stochastic geometry and other areas. Their higher-rank generalization to Grassmann manifolds represents an interesting mathematical object useful for applications. More general integral transforms are introduced that reveal distinctive features of higher-rank objects in full generality. These new transforms are called the composite cosine transforms, by taking into account that their kernels agree with the composite power function of the cone of positive definite symmetric matrices. It is shown that injectivity of the composite cosine transforms can be studied using standard tools …

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Gauss-Manin Connections For Arrangements, Ii Nonresonant Weights, Daniel C. Cohen, Peter Orlik Jan 2005

Gauss-Manin Connections For Arrangements, Ii Nonresonant Weights, Daniel C. Cohen, Peter Orlik

Faculty Publications

We study the Gauss-Manin connection for the moduli space of an arrangement of complex hyperplanes in the cohomology of a nonresonant complex rank one local system. Aomoto and Kita determined this Gauss-Manin connection for arrangements in general position. We use their results and an algorithm constructed in this paper to determine this Gauss-Manin connection for all arrangements.

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Detailed Geochronology Of The Mississippi Sound During The Late Holocene, Brian Velardo Jan 2005

Detailed Geochronology Of The Mississippi Sound During The Late Holocene, Brian Velardo

LSU Master's Theses

The Mississippi Sound is a bar-built estuary that parallels the Mississippi Coast. It is bounded on the west by the St. Bernard lobe of the Mississippi River delta, Mobile Bay to the east, and the Gulf Coast barrier islands to the south. Few studies have investigated the late Holocene history of Mississippi Sound. In the present study, historical deposition in the Sound has been investigated using core data collected throughout the western, central, and eastern Mississippi Sound. The sediments within Mississippi Sound compose a complex depositional system that have responded to changes in sea level and hydrodynamics. Two factors that …

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Fracture Behavior Of Wood Plastic Composite (Wpc), Gi Young Jeong Jan 2005

Fracture Behavior Of Wood Plastic Composite (Wpc), Gi Young Jeong

LSU Master's Theses

In this study, the effect of notch length on impact strength and fracture toughness was examined to exploit the use of wood plastic composite (WPC) as structural materials. Impact and fracture toughness test methods and estimation procedures were carried out. To evaluate the impact strength of WPC, five different notch sizes with two different fiber orientations on the load head were prepared. In terms of fracture mechanics, notch length was converted to stress concentration factor and the relationship between stress concentration factor and impact strength was determined. Fracture surface of impact specimens was investigated to evaluate the fracture mechanism of …

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An In-Situ Capping Design For The Remediation Of Petroleum Contaminated Sediments, Melanie Krystle Harris Jan 2005

An In-Situ Capping Design For The Remediation Of Petroleum Contaminated Sediments, Melanie Krystle Harris

LSU Master's Theses

Historical disposal practices used by oil companies have caused the accumulation of contaminated sediments in their nearby lakes and ponds. These companies are now faced with the challenge of remediating the bodies of water that contain these contaminated sediments. The contaminants that remain in the sediment continue to pose a threat to human health and the environment. For example, high concentrations of polycyclic aromatic hydrocarbons (PAHs), which are still present in the bottom sediments can have toxic effects on aquatic life. One form of remediation for this problem is In-Situ Capping (ISC), which is defined as a method whereby material …

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Transform Techniques And Non-Stationarity With An Emphasis On Network Applications, Phat Piron Jan 2005

Transform Techniques And Non-Stationarity With An Emphasis On Network Applications, Phat Piron

LSU Master's Theses

The recent years brought a phenomenal development of Internet. It is, therefore, important to find some ways to improve the performances. The first step in this direction is the characterization and modeling of the network traffic. It has been tested that the network traffic behaves like a self-similar process, while packets interarrivals time possess the long-range dependence property. In particular, we model them by using fractional Brownian motion and fractional Gaussian noise, respectively. Note that, the former is just the cumulative sum of the latter. By using these concepts, the traffic characterization reduces to the estimation of one value: the …

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3-Dimensional Flow Measurements In Square Coaxial Jets, Thomas Lagarde Jan 2005

3-Dimensional Flow Measurements In Square Coaxial Jets, Thomas Lagarde

LSU Master's Theses

Results from un-forced experiments conducted in the three-dimensional flow emanating from coaxial contoured nozzles with square cross section and parallel sides are presented and discussed. Two experiments were conducted with the inner to outer jet nominal velocity ratio equal to l=0.5 and l=1.5. The Reynolds number of the outer jet based on the hydraulic diameter of the outer nozzle exit was in both cases 16,000. A multi-position hot-wire anemometry method was used for measurements in the three-dimensional turbulent flow using a dual film sensor (X-probe). A methodology was developed and implemented to derive the mean-velocity components and Reynolds stresses corrected …

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Secure 3g User Authentication In Ad-Hoc Serving Networks, Lyn L. Evans Jan 2005

Secure 3g User Authentication In Ad-Hoc Serving Networks, Lyn L. Evans

LSU Master's Theses

The convergence of cellular and IP technologies has pushed the integration of 3G and WLAN networks to the forefront. With 3G networks' failure to deliver feasible bandwidth to the customer and the emerging popularity, ease of use and high throughput of 802.11 WLANs, integrating secure access to 3G services from WLANs has become a primary focus. 3G user authentication initiated from WLANs has been defined by an enhancement to the extensible authentication protocol, EAP, used to transport user authentication requests over WLANs. The EAP-AKA protocol executes the 3G USIM user challenge and response authentication process over the IP backbone for …

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A Programmable Cmos Decimator For Sigma-Delta Analog-To-Digital Converter And Charge Pump Circuits, Raghavendra Reddy Anantha Jan 2005

A Programmable Cmos Decimator For Sigma-Delta Analog-To-Digital Converter And Charge Pump Circuits, Raghavendra Reddy Anantha

LSU Master's Theses

PROGRAMMABLE DECIMATOR FOR SIGMA-DELTA ANALOG-TO-DIGITAL CONVERTER: In this work a programmable decimator design has been presented in 1.5 μm n-well CMOS process for integration with an existing modulator to form a sigma-delta analog-to-digital converter (ADC). The decimator is implemented using a second order Cascaded Integrator Comb (CIC) filter and can be programmed to work with two different oversampling ratios of 64 and 16. The input to the decimator is provided from a first order modulator. With oversampling ratios of 64 and 16, an output resolution of 10-bit and 7-bit, respectively are achieved for the ADC. The ADC can be operated …

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Automated Operation Minimization Of Tensor Contraction Expressions In Electronic Structure Calculations, Albert Hartono, Alexander Sibiryakov, Marcel Nooijen, Gerald Baumgartner, David E. Bernholdt, So Hirata, Chi Chung Lam, Russell M. Pitzer, J. Ramanujam, P. Sadayappan Jan 2005

Automated Operation Minimization Of Tensor Contraction Expressions In Electronic Structure Calculations, Albert Hartono, Alexander Sibiryakov, Marcel Nooijen, Gerald Baumgartner, David E. Bernholdt, So Hirata, Chi Chung Lam, Russell M. Pitzer, J. Ramanujam, P. Sadayappan

Faculty Publications

Complex tensor contraction expressions arise in accurate electronic structure models in quantum chemistry, such as the Coupled Cluster method. Transformations using algebraic properties of commutativity and associativity can be used to significantly decrease the number of arithmetic operations required for evaluation of these expressions, but the optimization problem is NP-hard. Operation minimization is an important optimization step for the Tensor Contraction Engine, a tool being developed for the automatic transformation of high-level tensor contraction expressions into efficient programs. In this paper, we develop an effective heuristic approach to the operation minimization problem, and demonstrate its effectiveness on tensor contraction expressions …

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