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Time-Frequency Representations Of High Order Harmonics, Mette B. Gaarde Jan 2001

Time-Frequency Representations Of High Order Harmonics, Mette B. Gaarde

Faculty Publications

We calculate time-frequency representations (TFRs) of high-order short pulse harmonics generated in the interaction between neon atoms and an intense laser field, including macroscopic effects of propagation and phase matching in the non-linear medium. The phase structure of the harmonics is often complicated and the TFR can help to resolve the different components of this structure. The harmonic pulses exhibit an overall negative chirp, which can be attributed in part to the intensity dependence of the harmonic dipole phase. In some cases, the harmonic field separates in the time-frequency domain and clearly exhibits two different chirps. We also compute an …

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Polymer Processing In Microgravity: An Overview, James Patton Downey, John A. Pojman Jan 2001

Polymer Processing In Microgravity: An Overview, James Patton Downey, John A. Pojman

Faculty Publications

Understanding how polymer processing can be different in microgravity requires an understanding of how gravity can affect polymer reactions and processes. We review here the fundamentals of buoyancy-driven (Rayleigh-Bénard) and surface-tension driven (Marangoni) convection. We consider the polymer processes that are affected by convection and review polymer experiments that demonstrate convective effects in 1 g and microgravity.

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Phylogeny Of The Celastraceae Inferred From Phytochrome B Gene Sequence And Morphology, Mark P. Simmons, Curtis C. Clevinger, Vincent Savolainen, Robert H. Archer, Sarah Mathews, Jeff J. Doyle Jan 2001

Phylogeny Of The Celastraceae Inferred From Phytochrome B Gene Sequence And Morphology, Mark P. Simmons, Curtis C. Clevinger, Vincent Savolainen, Robert H. Archer, Sarah Mathews, Jeff J. Doyle

Faculty Publications

Phylogenetic relationships within Celastraceae were inferred using a simultaneous analysis of 61 morphological characters and 1123 base pairs of phytochrome B exon 1 from the nuclear genome. No gaps were interred, and the gene tree topology suggests that the primers were specific to a single locus that did not duplicate among the lineages sampled. This region of phytochrome B was most useful for examining relationships among closely related genera. Fifty-one species from 38 genera of Celastraceae were sampled. The Celastraceae sensu lato (including Hippocrateaceae) were resolved as a monophyletic group. Loesener's subfamilies and tribes of Celastraceae were not supported. The …

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Effect Of Ph And Salt Bridges On Structural Assembly: Molecular Structures Of The Monomer And Intertwined Dimer Of The Eps8 Sh3 Domain, K. V. Radha Kishan, M. E. Newcomer, T. H. Rhodes, S. D. Guilliot Jan 2001

Effect Of Ph And Salt Bridges On Structural Assembly: Molecular Structures Of The Monomer And Intertwined Dimer Of The Eps8 Sh3 Domain, K. V. Radha Kishan, M. E. Newcomer, T. H. Rhodes, S. D. Guilliot

Faculty Publications

The SH3 domain of Eps8 was previously found to form an intertwined, domain-swapped dimer. We report here a monomeric structure of the EPS8 SH3 domain obtained from crystals grown at low pH, as well as an improved domain-swapped dimer structure at 1.8 Å resolution. In the domain-swapped dimer the asymmetric unit contains two "hybrid-monomers." In the low pH form there are two independently folded SH3 molecules per asymmetric unit. The formation of intermolecular salt bridges is thought to be the reason for the formation of the dimer. On the basis of the monomer SH3 structure, it is argued that Eps8 …

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The Genetics Of Reproductive Isolation And The Potential For Gene Exchange Between Drosophila Pseudoobscura And D. Persimilis Via Backcross Hybrid Males, Mohamed A.F. Noor, Katherine L. Grams, Lisa A. Bertucci, Yvette Almendarez, Jane Reiland, Kelley R. Smith Jan 2001

The Genetics Of Reproductive Isolation And The Potential For Gene Exchange Between Drosophila Pseudoobscura And D. Persimilis Via Backcross Hybrid Males, Mohamed A.F. Noor, Katherine L. Grams, Lisa A. Bertucci, Yvette Almendarez, Jane Reiland, Kelley R. Smith

Faculty Publications

Hybrid male sterility, hybrid inviability, sexual isolation, and a hybrid male courtship dysfunction reproductively isolate Drosophila pseudoobscura and D. persimilis. Previous studies of the genetic bases of these isolating mechanisms have yielded only limited information about how much and what areas of the genome are susceptible to interspecies introgression. We have examined the genetic basis of these barriers to gene exchange in several thousand backcross hybrid male progeny of these species using 14 codominant molecular genetic markers spanning the five chromosomes of these species, focusing particularly on the autosomes. Hybrid male sterility, hybrid inviability, and the hybrid male courtship dysfunction …

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Estimating The Unbiased Estimator Θ For Population Genetic Survey Data, Jacqueline J. Weicker, Robb T. Brumfield, Kevin Winker Jan 2001

Estimating The Unbiased Estimator Θ For Population Genetic Survey Data, Jacqueline J. Weicker, Robb T. Brumfield, Kevin Winker

Faculty Publications

We consider a method of approximating Weir and Cockerham's θ, an unbiased estimator of genetic population structure, using values readily available from published studies using biased estimators (Wright's FST or Nei's GST). The estimation algorithm is shown to be useful for both model populations and real-world avian populations. However, the correlation between Wright's FST and Weir and Cockerham's θ is strong when compared among 39 empirical avian datasets. Thus, the advantage of approximating an unbiased estimator is unclear considering the small actual effect of θ's bias-removing power on empirical datasets.

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Evolutionary Implications Of Divergent Clines In An Avian (Manacus: Aves) Hybrid Zone, Robb T. Brumfield, Robert W. Jernigan, David B. Mcdonald, Michael J. Braun Jan 2001

Evolutionary Implications Of Divergent Clines In An Avian (Manacus: Aves) Hybrid Zone, Robb T. Brumfield, Robert W. Jernigan, David B. Mcdonald, Michael J. Braun

Faculty Publications

A previous study of the hybrid zone in western Panama between white-collared (Manacus candei) and golden-collared manakins (M. vitellinus) documented the unidirectional introgression of vitellinus male secondary sexual traits across the zone. Here, we examine the hybrid zone in greater genetic and morphological detail. Statistical comparisons of clines are performed using maximum-likelihood and nonparametric bootstrap methods. Our results demonstrate that an array of six molecular and two morphometric markers agree in cline position and width. Clines for male collar and belly color are similar in width to the first eight clines, but are shifted in position by at least five …

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Sexual Selection On Plumage And Behavior In An Avian Hybrid Zone: Experimental Tests Of Male-Male Interactions, David B. Mcdonald, Robert P. Clay, Robb T. Brumfield, Michael J. Braun Jan 2001

Sexual Selection On Plumage And Behavior In An Avian Hybrid Zone: Experimental Tests Of Male-Male Interactions, David B. Mcdonald, Robert P. Clay, Robb T. Brumfield, Michael J. Braun

Faculty Publications

In western Panama, an unusual hybrid zone exists between white-collared manakins, Manacus candei, and golden-collared manakins, M. vitellinus. Unidirectional introgression of plumage traits from vitellinus into candei has created a region in which all definitively plumaged males have a collar that is lemon-colored. These males are nearly indistinguishable from white-collared candei genetically and morphometrically, but strongly resemble golden-collared vitellinus due to the introgression of secondary sexual plumage traits, particularly the lemon-colored collar. The introgression could be explained by sexual selection for golden-collared traits or by a series of mechanisms that do not invoke sexual selection (e.g., neutral diffusion, dominant allele). …

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Membrane Lipid Biosynthesis In Chlamydomonas Reinhardtii. In Vitro Biosynthesis Of Diacylglyceryltrimethylhomoserine, T. S. Moore, Z. Du, Z. Chen Jan 2001

Membrane Lipid Biosynthesis In Chlamydomonas Reinhardtii. In Vitro Biosynthesis Of Diacylglyceryltrimethylhomoserine, T. S. Moore, Z. Du, Z. Chen

Faculty Publications

Diacylglyceryltrimethylhomo-Ser (DGTS) is an abundant lipid in the membranes of many algae, lower plants, and fungi. It commonly has an inverse concentration relationship with phosphatidylcholine, thus seemingly capable of replacing this phospholipid in these organisms. In some places this replacement is complete; Chlamydomonas reinhardtii is such an organism, and was used for these investigations. We have assayed headgroup incorporation to form DGTS in vitro. The precursor for both the homo-Ser moiety and the methyl groups was found to be S-adenosyl-L-Met. DGTS formation was associated with microsomal fractions and is not in plastids. By analogy with phosphatidylcholine and phosphatidylethanolamine biosynthesis in …

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Resistance To Aflatoxin Accumulation In Kernels Of Maize Inbreds Selected For Ear Rot Resistance In West And Central Africa, R. L. Brown, Z. Y. Chen, A. Menkir, T. E. Cleveland, K. Cardwell, J. Kling, D. G. White Jan 2001

Resistance To Aflatoxin Accumulation In Kernels Of Maize Inbreds Selected For Ear Rot Resistance In West And Central Africa, R. L. Brown, Z. Y. Chen, A. Menkir, T. E. Cleveland, K. Cardwell, J. Kling, D. G. White

Faculty Publications

Thirty-six inbred lines selected in West and Central Africa for moderate to high resistance to maize ear rot under conditions of severe natural infection were screened for resistance to aflatoxin contamination using the previously established kernel screening assay. Results showed that more than half the inbreds accumulated aflatoxins at levels as low as or lower than the resistant U.S. lines GT-MAS:gk or M182. In 10 selected aflatoxin-resistant or aflatoxin-susceptible inbreds, Aspergillus flavus growth, which was quantified using an A. flavus transformant containing a GUS-β-tubulin reporter gene construct, was, in general, positively related to aflatoxin accumulation. However, one aflatoxin-resistant inbred supported …

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Variation In In Vitro Α-Amylase And Protease Activity Is Related To The Virulence Of Aspergillus Flavus Isolates, R. L. Brown, Z. Y. Chen, T. E. Cleveland, P. J. Cotty, J. W. Cary Jan 2001

Variation In In Vitro Α-Amylase And Protease Activity Is Related To The Virulence Of Aspergillus Flavus Isolates, R. L. Brown, Z. Y. Chen, T. E. Cleveland, P. J. Cotty, J. W. Cary

Faculty Publications

Variation in the ability of Aspergillus flavus isolates to spread between cotton boll locules was previously shown to be at least partially related to variation in the production of a specific polygalacturonase (pectinase P2C). To determine if nonpectolytic hydrolase differences between low- and high-virulence isolates exist and, thus, could also potentially contribute to virulence differences, the present investigation was undertaken. Two A, flavus isolates, AFl2 with low virulence and lacking pectinase P2C and AF13 with high virulence and producing pectinase P2C, were compared for production of nonpectolytic hydrolases after growth in 10% potato dextrose broth. Activity of amylases, cellulases, xylanases, …

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Comparison Of Constitutive And Inducible Maize Kernel Proteins Of Genotypes Resistant Or Susceptible To Aflatoxin Production, Z. Y. Chen, R. L. Brown, T. E. Cleveland, K. E. Damann, J. S. Russin Jan 2001

Comparison Of Constitutive And Inducible Maize Kernel Proteins Of Genotypes Resistant Or Susceptible To Aflatoxin Production, Z. Y. Chen, R. L. Brown, T. E. Cleveland, K. E. Damann, J. S. Russin

Faculty Publications

Maize genotypes resistant or susceptible to aflatoxin production or contamination were compared for differences in both constitutive and inducible proteins. Five additional constitutive proteins were found to be associated with resistance in over 8 of the 10 genotypes examined. Among these, the 58- and 46-kDa proteins were identified as globulin-1 and globulin-2, respectively. Differences in the ability to induce specific antifungal proteins, such as the higher synthesis of the 22-kDa zeamatin in resistant genotypes, were also observed between resistant and susceptible kernels incubated under germinating conditions (31°C, 100% humidity). Both constitutive and inducible proteins appear to be necessary for kernel …

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Sweetpotato Periderm Components Inhibit In Vitro Growth Of Root Rotting Fungi, Jr Harrison, J. K. Peterson, C. A. Clark, M. E. Snook Jan 2001

Sweetpotato Periderm Components Inhibit In Vitro Growth Of Root Rotting Fungi, Jr Harrison, J. K. Peterson, C. A. Clark, M. E. Snook

Faculty Publications

Sweetpotato [Ipomoea batatas (L.) Lam.] periderm components were tested for their effect on four fungi that infect sweetpotato roots: Fusarium oxysporum Schlecht. f. sp. batatas (Wollenw.) Snyd. & Hans. and F. solani (Sacc.) Mart., both of which cause stem and root disease; and Lasiodiplodea theobromae (Pat.) Griffon & Maubl. and Rhizopus stolonifer (Ehr. ex Fr.) Lind., both of which cause storage root disease. Sequential extracts of 'Regal' sweetpotato periderm with hexane, methanol, and 50% methanol were inhibitory to the four fungi when incorporated into potato dextrose agar medium in petri dish bioassays. The methanol and 50% methanol extracts were much …

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Effect Of Commercial Fat Replacers On The Microstructure Of Low-Fat Cheddar Cheese, Kayanush J. Aryana, Zahur U. Haque Jan 2001

Effect Of Commercial Fat Replacers On The Microstructure Of Low-Fat Cheddar Cheese, Kayanush J. Aryana, Zahur U. Haque

Faculty Publications

This objective of this study was to determine the effect of protein-and carbohydrate-based fat replacers on the microstructure of low-fat Cheddar cheese. Microstructure was studied by transmission and scanning electron microscopy. Protein-based fat replacers were Dairy LoTM (DL) and SimplesseTM (SIMP), while the carbohydrate-based fat replacers were NovagelTM (NOV) and StellarTM (STEL). Low-fat Cheddar cheese was manufactured using these commercial fat replacers and aged for 6 months at 5 °C. Low-fat control (LFC) and low-fat Cheddar cheese made with SIMP and DL showed a rippled surface microstructure while incorporation of NOV and STEL resulted in cheese with an undulated and …

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Linkage And Association Analysis Of Angiotensin I-Converting Enzyme (Ace)-Gene Polymorphisms With Ace Concentration And Blood Pressure, Xiaofeng Zhu, Nourdine Bouzekri, Lorraine Southam, Richard S. Cooper, Adebowale Adeyemo, Colin A. Mckenzie, Amy Luke, Guangjie Chen, Robert C. Elston, Ryk Ward Jan 2001

Linkage And Association Analysis Of Angiotensin I-Converting Enzyme (Ace)-Gene Polymorphisms With Ace Concentration And Blood Pressure, Xiaofeng Zhu, Nourdine Bouzekri, Lorraine Southam, Richard S. Cooper, Adebowale Adeyemo, Colin A. Mckenzie, Amy Luke, Guangjie Chen, Robert C. Elston, Ryk Ward

Faculty Publications

Considerable effort has been expended to determine whether the gene for angiotensin I-converting enzyme (ACE) confers susceptibility to cardiovascular disease. In this study, we genotyped 13 polymorphisms in the ACE gene in 1,343 Nigerians from 332 families. To localize the genetic effect, we first performed linkage and association analysis of all the markers with ACE concentration. In multipoint variance-component analysis, this region was strongly linked to ACE concentration (maximum LOD score 7.5). Likewise, most of the polymorphisms in the ACE gene were significantly associated with ACE (P < .0013). The two most highly associated polymorphisms, ACE4 and ACE8, accounted for 6% and 19% of the variance in ACE, respectively. A two-locus additive model with an additive x additive interaction of these polymorphisms explained most of the ACE variation associated with this region. We next analyzed the relationship between these two polymorphisms (ACE4 and ACE8) and blood pressure (BP). Although no evidence of linkage was detected, significant association was found for both systolic and diastolic BP when a two-locus additive model developed for ACE concentration was used. Further analyses demonstrated that an epistasis model provided the best fit to the BP variation. In conclusion, we found that the two polymorphisms explaining the greatest variation in ACE concentration are significantly associated with BP, through interaction, in this African population sample. Our study also demonstrates that greater statistical power can be anticipated with association analysis versus linkage, when markers in strong linkage disequilibrium with a trait locus have been identified. Furthermore, alllelic interaction may play an important role in the dissection of complex traits such as BP.

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Effect Of Sweetpotato Genotype, Storage Time And Production Site On Feeding And Oviposition Behavior Of The Sweetpotato Weevil, Cylas Formicarius (Coleoptera: Apoinidae), L. Mao, R. N. Story, A. M. Hammond, D. R. Labonte Jan 2001

Effect Of Sweetpotato Genotype, Storage Time And Production Site On Feeding And Oviposition Behavior Of The Sweetpotato Weevil, Cylas Formicarius (Coleoptera: Apoinidae), L. Mao, R. N. Story, A. M. Hammond, D. R. Labonte

Faculty Publications

The effect of sweetpotato genotype, storage time and production site on Cylas formicarius (Fab.) feeding and oviposition was investigated. Sweetpotato genotype had a significant effect on feeding and oviposition rates in both no-choice and choice arenas. Beauregard and Centennial were uniformly susceptible across all age groups. W-250 had the least number of feeding punctures and eggs at 7 and 25 days after harvest. At 85 days after harvest, W-244 had the least number of feeding punctures and eggs, while W-250 was not significantly different from Beauregard and Centennial. Roots of the same genotype grown in different locations differed in the …

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The Asymptotic Equivalence Of The Fisher Information Matrices For Type I And Type Ii Censored Data From Location-Scale Families, Luis A. Escobar, William Q. Meeker Jan 2001

The Asymptotic Equivalence Of The Fisher Information Matrices For Type I And Type Ii Censored Data From Location-Scale Families, Luis A. Escobar, William Q. Meeker

Faculty Publications

Type I and Type II censored data arise frequently in controlled laboratory studies concerning time to a particular event (e.g., death of an animal or failure of a physical device). Log-location-scale distributions (e.g., Weibull, log-normal, and loglogistic) are commonly used to model the resulting data. Maximum likelihood (ML) is generally used to obtain parameter estimates when the data are censored. The Fisher information matrix can be used to obtain large-sample approximate variances and covariances of the ML estimates or to estimate these variances and covariances from data. The derivations of the Fisher information matrix proceed differently for Type I (time …

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Similarity Is Relative: Hierarchy Of Genetic Similarities In The Formosan Subterranean Termite (Isoptera: Rhinotermitidae) In Hawaii, C. Husseneder, J. K. Grace Jan 2001

Similarity Is Relative: Hierarchy Of Genetic Similarities In The Formosan Subterranean Termite (Isoptera: Rhinotermitidae) In Hawaii, C. Husseneder, J. K. Grace

Faculty Publications

Termites (Isoptera) have a strong hierarchical structure due to their social organization. To interpret genetic differences within and among termite populations it is first necessary to create a quantitative scale to determine the meaning of "different." To accomplish this, the entire hierarchy of genetic similarities in a Hawaiian population of Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae) was defined by multilocus DNA fingerprinting using the oligonucleotide (GTG)5 as a probe. The genetic background similarity in the population, based on the genetic similarity between unrelated termites, was 0.21 and falls in the range of other natural invertebrate and vertebrate populations. The mean genetic …

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Seasonal Distribution And Parasitism Of Scapteriscus Spp. (Orthoptera: Gryllotalpidae) In Southeastern Louisiana, D. C. Henne, S. J. Johnson Jan 2001

Seasonal Distribution And Parasitism Of Scapteriscus Spp. (Orthoptera: Gryllotalpidae) In Southeastern Louisiana, D. C. Henne, S. J. Johnson

Faculty Publications

Mole crickets of the genus Scapteriscus were accidentally introduced into the southern United States almost a century ago and are considered to be economically important pests in southern U.S. regions. Mole crickets were sampled using acoustic traps in Baton Rouge and New Orleans, Louisiana in the fall of 1998, the spring and fall of 1999, and the spring of 2000. In southeastern Louisiana Scapteriscus borellii has a seasonal flight period starting in late February and continuing into June. A lesser flight period occurs in the fall, starting in mid-September and continuing into November. S. vicinus was captured only from late …

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Bollworm (Lepidoptera: Noctuidae) Survival On 'Bollgard' And 'Bollgard Ii' Cotton Flower Bud And Flower Components, J. Gore, B. R. Leonard, J. J. Adamczyk Jan 2001

Bollworm (Lepidoptera: Noctuidae) Survival On 'Bollgard' And 'Bollgard Ii' Cotton Flower Bud And Flower Components, J. Gore, B. R. Leonard, J. J. Adamczyk

Faculty Publications

Genetically modified cotton, Gossypium hirsutum L., cultivars ('Bollgard') that produce crystalline proteins from Bacillus thuringiensis (Berliner) are valuable tools for managing lepidopteran insect pests in the United States. However, high numbers of bollworm, Helicoverpa zea (Boddie), larvae have been observed feeding in white flowers of these cultivars. Fresh tissue bioassays were conducted to investigate bollworm survival on Bollgard and 'Bollgard II' cottons. Bollworm survival was higher on square and flower anthers than on other floral structures on 'Deltapine 5415' (conventional cotton) and 'NuCOTN 33B' (Bollgard). Bollworm survival at 72 h was higher on all floral structures from Deltapine 5415 than …

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Selection, Egg Viability, And Fecundity Of The Sugarcane Borer (Lepidoptera: Crambidae) With Tebufenozide, L. M. Rodriguez, J. A. Ottea, T. E. Reagan Jan 2001

Selection, Egg Viability, And Fecundity Of The Sugarcane Borer (Lepidoptera: Crambidae) With Tebufenozide, L. M. Rodriguez, J. A. Ottea, T. E. Reagan

Faculty Publications

Two separate attempts to select the sugarcane borer, Diatraea saccharalis (F.), for resistance to tebufenozide were unsuccessful. Both selected colonies were lost after the fourth generation due to a lack of oviposition. Differences were not detected in fecundity or percent egg viability for 5-d-old third instars exposed to concentrations (EC5, EC15, and EC30) of tebufenozide for 7 d. Decreases (P ≤ 0.01) in mean female pupal weights were detected in larvae exposed to EC15 and EC30 concentrations. An ovicidal impact using serial dilutions of tebufenozide (10, 100, and 200 ppm) also was detected. Percent viability was reduced from 98% for …

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Global Methylation Profiling Of Lung Cancer Identifies Novel Methylated Genes, Zunyan Dai, Romola R. Lakshmanan, Wei Guo Zhu, Dominic J. Smiraglia, Laura J. Rush, Michael C. Frühwald, Romulo M. Brena, Bin Li, Fred A. Wright, Patrick Ross, Gregory A. Otterson, Christoph Plass Jan 2001

Global Methylation Profiling Of Lung Cancer Identifies Novel Methylated Genes, Zunyan Dai, Romola R. Lakshmanan, Wei Guo Zhu, Dominic J. Smiraglia, Laura J. Rush, Michael C. Frühwald, Romulo M. Brena, Bin Li, Fred A. Wright, Patrick Ross, Gregory A. Otterson, Christoph Plass

Faculty Publications

Epigenetic changes, including DNA methylation, are a common finding in cancer. In lung cancers methylation of cytosine residues may affect tumor initiation and progression in several ways, including the silencing of tumor suppressor genes through promoter methylation and by providing the targets for adduct formation of polycyclic aromatic hydrocarbons present in combustion products of cigarette smoke. Although the importance of aberrant DNA methylation is well established, the extent of DNA methylation in lung cancers has never been determined. Restriction landmark genomic scanning (RLGS) is a highly reproducible two-dimensional gel electrophoresis that allows the determination of the methylation status of up …

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Seiberg-Witten Invariants Of 4-Manifolds With Free Circle Actions, Scott Baldridge Jan 2001

Seiberg-Witten Invariants Of 4-Manifolds With Free Circle Actions, Scott Baldridge

Faculty Publications

The main results of this paper describes a formula for the Seiberg-Witten invariant of a 4-manifold which admits a nontrivial free circle action. We use this theorem to produce a nonsymplectic 4-manifold with a free circle action whose orbit space fibers over circle. We also describe a nontrivial 3-manifold which is not the orbit space of any symplectic 4-manifold with a free circle action. A corollary of the main theorem is a formula for the 3-dimensional Seiberg-Witten invariants of the total space of a circle bundle over a surface. © World Scientific Publishing Company.

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Totally Ordered Commutative Monoids, K. Evans, M. Konikoff, J. J. Madden, R. Mathis, G. Whipple Jan 2001

Totally Ordered Commutative Monoids, K. Evans, M. Konikoff, J. J. Madden, R. Mathis, G. Whipple

Faculty Publications

A totally ordered monoid - or tomonoid, for short - is a commutative semigroup with identity S equipped with a total order ≤s that is translation invariant, i.e., that satisfies: ∀x, y, z ∈, x ≤s y ⇒ x + z ≤s y + z. We call a tomonoid that is a quotient of some totally ordered free commutative monoid formally integral. Our most significant results concern characterizations of this condition by means of constructions in the lattice Zn that are reminiscent of the geometric interpretation of the Buchberger algorithm that occurs in integer programming. In particular, we show that …

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Causal Compactification And Hardy Spaces For Spaces Of Hermitian Type, Frank Betten, Gestur Ólafsson Jan 2001

Causal Compactification And Hardy Spaces For Spaces Of Hermitian Type, Frank Betten, Gestur Ólafsson

Faculty Publications

Let G/H be a compactly causal symmetric space with causal compactification Φ : G/H → Š1, where Š1 is the Bergman-Šilov boundary of a tube type domain G1/K1. The Hardy space H2(C) of G/H is the space of holomorphic functions on a domain Ξ(C°) ⊂ Gℂ/Hℂ with L2-boundary values on G/H. We extend Φ to imbed Ξ(C°) into G1/K1, such that Ξ(C°) = {z ∈ G1/K1 | ψm(z) ≠ 0}, with ψm explicitly known. We use this to construct an isometry I of the classical Hardy space Hcl on G1/K1 into H2(C) or into a Hardy space H̃2(C) defined on …

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Useful Alternative To The Multipole Expansion Of Potentials, H. S. Cohl, A. R.P. Rau, J. E. Tohline, D. A. Browne, J. E. Cazes, E. I. Barnes Jan 2001

Useful Alternative To The Multipole Expansion Of Potentials, H. S. Cohl, A. R.P. Rau, J. E. Tohline, D. A. Browne, J. E. Cazes, E. I. Barnes

Faculty Publications

Few-body problems involving Coulomb or gravitational interactions between pairs of particles, whether in classical or quantum physics, are generally handled through a standard multipole expansion of the two-body potentials. We develop an alternative based on an old, but hitherto forgotten, expression for the inverse distance between two points that builds on azimuthal symmetry. This alternative should have wide applicability throughout physics and astronomy, both for computation and for the insights it provides through its emphasis on different symmetries and structures than are familiar from the standard treatment. We compare and contrast the two methods, develop addition theorems for Legendre functions …

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The Bennequin Number Of N-Trivial Closed N-Braids Is Negative, Oliver T. Dasbach, Lin Xiao-Song Jan 2001

The Bennequin Number Of N-Trivial Closed N-Braids Is Negative, Oliver T. Dasbach, Lin Xiao-Song

Faculty Publications

A famous result of Bennequin states that for any braid representative of the unknot the Bennequin number is negative. We will extend this result to all n-trivial closed n-braids. This is a class of infinitely many knots closed under taking mirror images. Our proof relies on a non-standard parameterization of the HOMFLY polynomial. Another interesting corollary of this parameterization is that if all Vassiliev invariants up to degree c vanish on a knot of crossing number c, then this knot has trivial HOMFLY polynomial.

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Viscosity Solutions Of The Bellman Equation For Exit Time Optimal Control Problems With Non-Lipschitz Dynamics, Michael Malisoff Jan 2001

Viscosity Solutions Of The Bellman Equation For Exit Time Optimal Control Problems With Non-Lipschitz Dynamics, Michael Malisoff

Faculty Publications

We study the Bellman equation for undiscounted exit time optimal control problems with fully nonlinear Lagrangians and fully nonlinear dynamics using the dynamic programming approach. We allow problems whose non-Lipschitz dynamics admit more than one solution trajectory for some choices of open loop controls and initial positions. We prove a uniqueness theorem which characterizes the value functions of these problems as the unique viscosity solutions of the corresponding Bellman equations that satisfy appropriate boundary conditions. We deduce that the value function for Sussmann’s Reflected Brachystochrone Problem for an arbitrary singleton target is the unique viscosity solution of the corresponding Bellman …

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Excitation Of Neutron Star Oscillations By An Orbiting Particle, Johannes Ruoff, Pablo Laguna, Jörge Pullin Jan 2001

Excitation Of Neutron Star Oscillations By An Orbiting Particle, Johannes Ruoff, Pablo Laguna, Jörge Pullin

Faculty Publications

The excitation of neutron stars is expected to be an important source of gravitational radiation. Therefore it is of fundamental importance to investigate mechanisms that trigger oscillations in neutron stars in order to characterize the emitted radiation. We present results from a numerical study of the even-parity gravitational radiation generated from a particle orbiting a neutron star. In contrast to previous calculations performed in the Fourier domain, we use the direct time evolution of the perturbation equations. We focus our investigation on those conditions on the orbital parameters that favor the excitation of w-modes. We find that for astrophysically realistic …

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Comment On "Photodetachment In Combined Static And Dynamic Electric Fields" “Multiple Letters”, I. I. Fabrikant, M. V. Frolov, N. L. Manakov, A. F. Starace, A. R.P. Rau, C. Rangan Jan 2001

Comment On "Photodetachment In Combined Static And Dynamic Electric Fields" “Multiple Letters”, I. I. Fabrikant, M. V. Frolov, N. L. Manakov, A. F. Starace, A. R.P. Rau, C. Rangan

Faculty Publications

No abstract provided.

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