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Search Results: 1 - 10 of 117846 matches for " T Beasley "
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Global Aspects of Abelian Duality in Dimension Three
Chris Beasley
Physics , 2014, DOI: 10.1007/JHEP08(2014)146
Abstract: In three dimensions, an abelian gauge field is related by duality to a free, periodic scalar field. Though usually considered on Euclidean space, this duality can be extended to a general three-manifold M, in which case topological features of M become important. Here I comment upon several of these features as related to the partition function on M. In a companion article, arXiv:1405.2483, I discuss similarly the algebra of operators on a surface of genus g.
Abelian Duality at Higher Genus
Chris Beasley
Physics , 2014, DOI: 10.1007/JHEP07(2014)157
Abstract: In three dimensions, a free, periodic scalar field is related by duality to an abelian gauge field. Here I explore aspects of this duality when both theories are quantized on a Riemann surface of genus g. At higher genus, duality involves an identification of winding with momentum on the Jacobian variety of the Riemann surface. I also consider duality for monopole and loop operators on the surface and exhibit the operator algebra, a refinement of the Wilson-'t Hooft algebra.
Localization for Wilson Loops in Chern-Simons Theory
Chris Beasley
Mathematics , 2009,
Abstract: We reconsider Chern-Simons gauge theory on a Seifert manifold M, which is the total space of a nontrivial circle bundle over a Riemann surface, possibly with orbifold points. As shown in previous work with Witten, the path integral technique of non-abelian localization can be used to express the partition function of Chern-Simons theory in terms of the equivariant cohomology of the moduli space of flat connections on M. Here we extend this result to apply to the expectation values of Wilson loop operators which wrap the circle fibers of M. Under localization, such a Wilson loop operator reduces naturally to the Chern character of an associated universal bundle over the moduli space. Along the way, we demonstrate that the stationary-phase approximation to the Wilson loop path integral is exact for torus knots, an observation made empirically by Lawrence and Rozansky prior to this work.
A proposed metric for assessing the measurement quality of individual microarrays
Kyoungmi Kim, Grier P Page, T Mark Beasley, Stephen Barnes, Katherine E Scheirer, David B Allison
BMC Bioinformatics , 2006, DOI: 10.1186/1471-2105-7-35
Abstract: We hypothesized that an index of the degree of spatiality of gene expression measurements associated with their physical geographic locations on an array could indicate the summary of the physical reliability of the microarray. We introduced a novel way to formulate this index using a statistical analysis tool. Our approach regressed gene expression intensity measurements on a polynomial response surface of the microarray's Cartesian coordinates. We demonstrated this method using a fixed model and presented results from real and simulated datasets.We demonstrated the potential of such a quantitative metric for assessing the reliability of individual arrays. Moreover, we showed that this procedure can be incorporated into laboratory practice as a means to set quality control specifications and as a tool to determine whether an array has sufficient quality to be retained in terms of spatial correlation of gene expression measurements.Gene expression microarrays are a powerful tool used in molecular biology and genetics for understanding gene expression change in biological processes under normal and pathological conditions [1]. Intensity measurements of gene expression are associated with significant variations as a result of the complex and multi-stage processing involved in microarray experiments. Beyond the variability that may be introduced during the fabrication of arrays as a result of print substrate quality and printing pin anomalies, several processing steps – mRNA sample extraction, amplification and labeling, hybridization, and scanning – may introduce substantial variation in measurements [2]. Although several studies have characterized the potential impact of these latter sources of variation on measurements of gene expression [2-4], methods for assessing the physical measurement quality of individual microarrays are not widely available. If technical replicates for a biological case are available, the degree of concordance between technical replicates ca
Ancestry-informative markers on chromosomes 2, 8 and 15 are associated with insulin-related traits in a racially diverse sample of children
Yann C Klimentidis, Jasmin Divers, Krista Casazza, T Beasley, David B Allison, Jose R Fernandez
Human Genomics , 2011, DOI: 10.1186/1479-7364-5-2-79
Abstract: Type 2 diabetes prevalence in the paediatric population is increasing, while age at onset is decreasing [1,2]. Type 2 diabetes also disproportionately affects racial/ethnic minorities in the USA [3]. Twin and familial studies have shown a substantial genetic component to the disease, as well as its related phenotypes [4-10]. Although much is known about environmental contributions to type 2 diabetes, only a very small proportion of the variation due to genetic factors is currently explainable by identified genetic polymorphisms [11-13]. Similarly, little is known about the specific genetic factors that may contribute to population differences in diabetes prevalence. Because the origins of type 2 diabetes are likely to be rooted in childhood, a better understanding of genetic determinants among paediatric populations could lead to a better insight into the aetiology of type 2 diabetes and eventually improved prediction and prevention of the disease.Endo-phenotypes can be useful in closely dissecting the genetic basis of eventual disease status [14]. For type 2 diabetes, several such measurable phenotypes exist, typically examining measures of glucose and insulin homeostasis. These measures serve as indicators of reduced insulin response and action that may presage type 2 diabetes [15,16]. Furthermore, previous studies have suggested a genetic basis for racial/ethnic differences in insulin dynamics [17,18]. Examining the genetic basis for these detailed phenotypes therefore allows for a much better understanding of the link between the genetic and metabolic pathways that underlie the development of type 2 diabetes.Since the loci recently identified by genome-wide association studies (GWAS)[19-21] occurred predominantly among individuals of European descent, there is considerable uncertainty as to whether these associations translate to other populations. Hispanic Americans (HAs) and African Americans (AAs) suffer from higher rates of type 2 diabetes than European Amer
Diffusion Weighted Imaging Evaluated the Early Therapy Effect of Tamoxifen in an MNU-Induced Mammary Cancer Rat Model
Guihua Zhai, Clinton J. Grubbs, Cecil R. Stockard, Heidi R. Umphrey, T. Mark Beasley, Hyunki Kim
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0064445
Abstract: Purpose To assess the optimal time point of diffusion-weighted imaging (DWI) for early prognosis of breast cancer following tamoxifen therapy using a methylnitrosourea (MNU)-induced ER-positive breast-cancer model. Methods Two groups of Sprague-Dawley rats (n = 15 for group 1; n = 10 for group 2) were used. All animals (50 days old) were intravenously injected with MNU (50 mg/kg body weight) to induce ER-positive mammary tumors. When tumors were approximately 2 cm in diameter, DWI was performed on days 0, 3, and 7, and intratumoral apparent diffusion coefficient (ADC) values were measured. Therapy started on day 0 with tamoxifen (10 mg/kg diet) and continued for 4 weeks for group 1, but only 1 week for group 2, while tumor volume was measured by caliper twice weekly. All animals of group 2 were euthanized on day 7 after imaging, and Ki-67, TUNEL, ERα, and ERβ staining were performed on tumor tissue. Results DW images of MNU-induced mammary tumors were successfully obtained with minimal motion artifact. For group 1, ADC change for 3 days after therapy initiation (ADC3D) was significantly correlated with tumor-volume change until day 11, but the significant correlation between ADC change for 7 days (ADC7D) and the tumor-volume change was observed until day 18. Similarly, for group 2, either ADC7D or ADC3D was significantly correlated with the tumor-volume change, but the higher significance was observed for ADC7D. Furthermore, ADC7D was significantly correlated with apoptotic (TUNEL stained), proliferative (Ki-67 stained), and ERβ-positive cell densities, but ADC3D was not significantly correlated with any of those. Conclusions ADC7D might be a more reliable surrogate imaging biomarker than ADC3D to assess effectiveness of tamoxifen therapy for ER-positive breast cancer, which may enable personalized treatment. The significant correlation between ADC7D and ERβ-positive cell density suggests that ERβ may play an important role as a therapeutic indicator of tamoxifen.
The SLICE, CHESS, and SISTINE Ultraviolet Spectrographs: Rocket-borne Instrumentation Supporting Future Astrophysics Missions
Kevin France,Keri Hoadley,Brian T. Fleming,Robert Kane,Nicholas Nell,Matthew Beasley,James C. Green
Physics , 2015,
Abstract: NASA's suborbital program provides an opportunity to conduct unique science experiments above Earth's atmosphere and is a pipeline for the technology and personnel essential to future space astrophysics, heliophysics, and atmospheric science missions. In this paper, we describe three astronomy payloads developed (or in development) by the Ultraviolet Rocket Group at the University of Colorado. These far-ultraviolet (100 - 160 nm) spectrographic instruments are used to study a range of scientific topics, from gas in the interstellar medium (accessing diagnostics of material spanning five orders of magnitude in temperature in a single observation) to the energetic radiation environment of nearby exoplanetary systems. The three instruments, SLICE, CHESS, and SISTINE form a progression of instrument designs and component-level technology maturation. SLICE is a pathfinder instrument for the development of new data handling, storage, and telemetry techniques. CHESS and SISTINE are testbeds for technology and instrument design enabling high-resolution (R > 100,000) point source spectroscopy and high throughput imaging spectroscopy, respectively, in support of future Explorer, Probe, and Flagship-class missions. The CHESS and SISTINE payloads support the development and flight testing of large-format photon-counting detectors and advanced optical coatings: NASA's top two technology priorities for enabling a future flagship observatory (e.g., the LUVOIR Surveyor concept) that offers factors of roughly 50 - 100 gain in ultraviolet spectroscopy capability over the Hubble Space Telescope. We present the design, component level laboratory characterization, and flight results for these instruments.
The Effects of Feeding on Hematological and Plasma Biochemical Profiles in Green (Chelonia mydas) and Kemp's Ridley (Lepidochelys kempii) Sea Turtles
Eric T. Anderson,Larry J. Minter,Elsburgh O. Clarke III,Raymond M. Mroch III,Jean F. Beasley,Craig A. Harms
Veterinary Medicine International , 2011, DOI: 10.4061/2011/890829
Abstract: In mammals, lipemic blood from sampling too soon after an animal feeds can have substantial effects on biochemical values. Plasma biochemical values in reptiles may be affected by species, age, season, and nutritional state. However, fasting status is not routinely considered when sampling reptile blood. In this paper, we evaluated 2-hour postprandial blood collection in two sea turtle species to investigate the effects of feeding on hematological and plasma biochemical values. Feeding had no significant effects on hematological values in either species, nor did it have an effect on plasma biochemistry values in Kemp's ridley sea turtles. In postprandial green turtles, total protein, albumin, ALP, AST, ALT, amylase, and cholesterol increased significantly, and chloride decreased significantly. Although statistically significant changes were observed, the median percent differences between pre- and postprandial values did not exceed 10% for any of these analytes and would not likely alter the clinical interpretation. 1. Introduction Green sea turtles (Chelonia mydas) are found in tropical to semitropical waters around the world and are the second most abundant sea turtle found off the Eastern United Sates [1, 2]. Juvenile green turtles found in coastal waters are in a transition phase from a more carnivorous diet (shrimp, snails, and ctenophores) to a primarily herbivorous diet (sea grasses), which creates a physiological status unique from other sea turtles [3]. Kemp’s ridley sea turtles (Lepidochelys kempii) are the smallest and most endangered of all sea turtles. They are found in waters along the eastern coast of North America, ranging from Mexico to as far north as New York and Massachusetts [2]. Kemp’s ridley turtles are carnivorous and opportunistic, feeding primarily on crabs, mollusks, and fish [3]. Juvenile green and Kemp’s ridley turtles use shallow coastal waters for foraging grounds, making them susceptible to a number of human-induced traumas (e.g., boat strike and fishing interactions) and natural disease processes (e.g., cold-stunning). Hundreds of juvenile turtles are found dead or severely debilitated each year, with many being brought into rehabilitation centers for treatments. Hematology and plasma biochemistries are valuable for monitoring animal health; however, environmental and procedural factors can have variable affects on reported values. Postprandial blood collection can yield lipemic samples due to increases in serum triglycerides in the form of chylomycrons. Several biochemical analytes change with diet, feeding, and lipemia
Performance of Clinical Algorithms for Smear-Negative Tuberculosis in HIV-Infected Persons in Ho Chi Minh City, Vietnam
Duc T. M. Nguyen,Hung Q. Nguyen,R. Palmer Beasley,Charles E. Ford,Lu-Yu Hwang,Edward A. Graviss
Tuberculosis Research and Treatment , 2012, DOI: 10.1155/2012/360852
Abstract: Background. Tuberculosis (TB) disease diagnosis in Vietnam relies on symptom screening, chest radiography (CXR), and acid fast bacilli (AFB) sputum smear which have a poor sensitivity in HIV patients. We evaluated the performance of clinical algorithms in screening and diagnosing AFB smear-negative TB in HIV patients. Methods. We enrolled 399 HIV-positive patients seeking care at a HIV clinic in Ho Chi Minh City (HCMC), Vietnam. Participants’ demographics, medical history, common TB symptoms, CXR, and laboratory tests were collected. Results. Of 399 HIV patients, 390 had initial AFB-negative smears and 22/390 patients had positive cultures. Symptom screening missed 54% (12/22) of smear-negative pulmonary TB (PTB) cases. Multivariate analysis found CD4+ cell level and CXR were significant PTB predictors. An algorithm combining four TB symptoms and TST presented a high sensitivity (100%), but poorly specific (24%) diagnostic performance for smear-negative PTB. Conclusion. Up to 54% of PTB cases in the HIV-infected population may be missed in the routine screening and diagnostic procedures used in Vietnam. Symptom screening was a poor overall diagnostic measure in detecting smear-negative TB in HIV patients. Our study results suggest that routine sputum cultures should be implemented to achieve a more accurate diagnosis of TB in HIV patients. 1. Introduction HIV-infected patients with tuberculosis (TB) coinfection may present with atypical manifestations of pulmonary TB (PTB) and a higher rate of negative sputum smears for acid fast bacilli (AFB) [1–3]. Though being less infectious than AFB smear-positive PTB, AFB smear-negative PTB is still a potentially important source of TB transmission and predicts a worse prognosis for HIV-infected patients [4–6]. Therefore, early and accurate diagnosis of sputum smear-negative PTB for HIV-infected patients is urgently important for not only improving the patient’s life expectancy, but also preventing disease transmission to the general population. The diagnosis of TB disease in developing countries like Vietnam relies mainly on symptom screening, chest radiography (CXR), and AFB sputum smear, which have a poor sensitivity in HIV-positive patients [3, 7]. Sputum culture is not routinely available for smear-negative patients, especially at district-level public health institutions [7]. Moreover, current data on the performance of clinical, radiographic, and laboratory characteristics in predicting AFB smear-negative PTB for HIV-infected patients are still limited and inconsistent [6, 8]. This reasoning led us to
Non-Fermi liquid behavior of SrRuO_3 -- evidence from infrared conductivity
P. Kostic,Y. Okada,Z. Schlesinger,J. W. Reiner,L. Klein,A. Kapitulnik,T. H. Geballe,M. R. Beasley
Physics , 1998, DOI: 10.1103/PhysRevLett.81.2498
Abstract: The reflectivity of the itinerant ferromagnet SrRuO_3 has been measured between 50 and 25,000 cm-1 at temperatures ranging from 40 to 300 K, and used to obtain conductivity, scattering rate, and effective mass as a function of frequency and temperature. We find that at low temperatures the conductivity falls unusually slowly as a function of frequency (proportional to \omega^{-1/2}), and at high temperatures it even appears to increase as a function of frequency in the far-infrared limit. The data suggest that the charge dynamics of SrRuO_3 are substantially different from those of Fermi-liquid metals.
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