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Search Results: 1 - 10 of 130834 matches for " William T. Prater "
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Examining the Effects of Common Laboratory Methods on the Sensitivity of Carbon Fiber Electrodes in Amperometric Recordings of Dopamine  [PDF]
William T. Prater, Malli Swamy, Megan D. Beane, Deranda B. Lester
Journal of Behavioral and Brain Science (JBBS) , 2018, DOI: 10.4236/jbbs.2018.83007
Abstract: Carbon fiber microelectrodes (CFEs) are useful when combined with electrochemical techniques for measuring changes in neurotransmitter concentrations. We addressed conflicting details regarding the use of CFEs. Experimental groups consisted of CFEs at different ages (1 week, 1 month, or 2 months), cleaned in solvents (isopropanol or xylene), and exposed to in vitro use (flow cell calibrations) or in vivo use (in brain tissue). In order to determine if any of these factors affect CFE sensitivity, the present study utilized fixed potential amperometry and a flow injection system to calibrate CFEs for the measurement of dopamine. The sensitivity index (nA/μM per 100 μm of exposed carbon fiber) was not affected by the age of CFEs or pre-cleaning with xylene or isopropanol. CFE sensitivity of the in vitro exposure group also did not differ from untreated CFEs, indicating the calibration process did not alter sensitivity. However, in vivo use in brain tissue did reduce sensitivity. This effect was negated and sensitivity restored by cleaning CFEs in isopropanol or xylene following in vivo brain recordings. Given that variations in CFE sensitivity can skew results, our findings can help standardize CFE use and explain discrepancies between researchers.
Sparse generalized Fourier series via collocation-based optimization
Ashley Prater
Mathematics , 2015,
Abstract: Generalized Fourier series with orthogonal polynomial bases have useful applications in several fields, including differential equations, pattern recognition, and image and signal processing. However, computing the generalized Fourier series can be a challenging problem even for relatively well behaved functions. In this paper a method for approximating a sparse collection of Fourier-like coefficients is presented that uses a collocation technique combined with an optimization problem inspired by recent results in compressed sensing research. The discussion includes approximation error rates and numerical examples to illustrate the effectiveness of the method. One example displays the accuracy of the generalized Fourier series approximation for several test functions, while the other is an application of the generalized Fourier series approximation to rotation-invariant pattern recognition in images.
Separation of undersampled composite signals using the Dantzig selector with overcomplete dictionaries
Ashley Prater,Lixin Shen
Statistics , 2015,
Abstract: In many applications one may acquire a composition of several signals that may be corrupted by noise, and it is a challenging problem to reliably separate the components from one another without sacrificing significant details. Adding to the challenge, in a compressive sensing framework, one is given only an undersampled set of linear projections of the composite signal. In this paper, we propose using the Dantzig selector model incorporating an overcomplete dictionary to separate a noisy undersampled collection of composite signals, and present an algorithm to efficiently solve the model. The Dantzig selector is a statistical approach to finding a solution to a noisy linear regression problem by minimizing the $\ell_1$ norm of candidate coefficient vectors while constraining the scope of the residuals. If the underlying coefficient vector is sparse, then the Dantzig selector performs well in the recovery and separation of the unknown composite signal. In the following, we propose a proximity operator based algorithm to recover and separate unknown noisy undersampled composite signals through the Dantzig selector. We present numerical simulations comparing the proposed algorithm with the competing Alternating Direction Method, and the proposed algorithm is found to be faster, while producing similar quality results. Additionally, we demonstrate the utility of the proposed algorithm in several experiments by applying it in various domain applications including the recovery of complex-valued coefficient vectors, the removal of impulse noise from smooth signals, and the separation and classification of a composition of handwritten digits.
Is Peritoneal Cytology a Prognostic Factor in Endometrial Cancer?  [PDF]
Jonathan Foote, William T. Creasman
Journal of Cancer Therapy (JCT) , 2015, DOI: 10.4236/jct.2015.68073
Abstract: The International Federation of Gynecology and Obstetrics (FIGO) changed the surgical staging criteria for endometrial cancer in 2009, namely combining FIGO 1988 Stage IA and IB in FIGO 2009 Stage IA, eliminating cervical glandular involvement from Stage II, and removing peritoneal cytology as criteria from Stage IIIA (3). This review of the literature sheds light on the continued debate among authorities on the utility of peritoneal cytology in surgical staging of endometrial cancer. At the time FIGO removed peritoneal cytology from the staging criteria in 2009, there was little to no evidence to support its removal. In fact, FIGO continues to recommend obtaining peritoneal cytology, which is in contradiction to their staging criteria. While a few small studies support the idea that peritoneal cytology does not preclude a worse prognosis, a number of large scale studies with at least 300 patients demonstrate a clear association between survival and the presence of malignant peritoneal cytology (11 - 12, 15 - 19). In one of the largest studies, investigators reviewed 14,704 from the SEER’s database, demonstrating that malignant peritoneal cytology is associated with decreased survival across Stage I/II disease even when controlled for histology, grade, and other risk factors. Malignant peritoneal cytology should be considered when counseling patients on the risk of recurrence and overall survival of endometrial cancer. However, the role of adjuvant treatment in this setting remains unclear.
Morphological Characterization of Amaranthus palmeri x A. spinosus Hybrids  [PDF]
William T. Molin, Vijay K. Nandula
American Journal of Plant Sciences (AJPS) , 2017, DOI: 10.4236/ajps.2017.86103
Abstract: The growth of clones of seven Amaranthus palmeri x A. spinosus hybrids was compared to type specimens of A. palmeri and A. spinosus
Finding Dantzig selectors with a proximity operator based fixed-point algorithm
Ashley Prater,Lixin Shen,Bruce W. Suter
Statistics , 2015,
Abstract: In this paper, we study a simple iterative method for finding the Dantzig selector, which was designed for linear regression problems. The method consists of two main stages. The first stage is to approximate the Dantzig selector through a fixed-point formulation of solutions to the Dantzig selector problem. The second stage is to construct a new estimator by regressing data onto the support of the approximated Dantzig selector. We compare our method to an alternating direction method, and present the results of numerical simulations using both the proposed method and the alternating direction method on synthetic and real data sets. The numerical simulations demonstrate that the two methods produce results of similar quality, however the proposed method tends to be significantly faster.
Identification of a Cardiac Disease Modifier Gene Using Forward Genetics in the Mouse
William T. Pu
PLOS Genetics , 2009, DOI: 10.1371/journal.pgen.1000643
Abstract:
Supramolecular Hydrogen-Bond Motifs in Chiral and Racemic Molecular Salts: A Comparison of (S)-2-Methyl Piperizinium Hydrogen Phosphite Monohydrate, C5H14N2·HPO3·H2O and (R,S)-2-Methyl Piperizinium Hydrogen Phosphite 2.23 Hydrate, C5H14N2·HPO3·2.23H2O
William T. A. Harrison
Crystals , 2011, DOI: 10.3390/cryst1040236
Abstract: The crystal structures of C 5H 14N 2·HPO 3·H 2O ( 1) and C 5H 14N 2·HPO 3·2.23H 2O ( 2) are described and compared. Compound 1 contains homochiral ( S)-2-methyl piperizinium cations, hydrogen phosphite ions and water molecules. The components are linked by N–H?O and O–H?O hydrogen bonds into a three-dimensional network. In compound 2, racemic ( R, S)-2-methyl piperizinium cations combine with the same anions and water molecules to generate a far more complex, high symmetry “supramolecular” structure, which features distinctive R 6 6(12) loops and helical C(2) chain hydrogen-bonding motifs involving the water molecules. Crystal data: 1 (C 5H 17N 2O 4P), M r = 200.18, orthorhombic, P2 12 12 1 (No. 19), Z = 4, a = 8.564 (5) ?, b = 9.593 (6) ?, c = 11.607 (6) ?, V = 953.6 (9) ? 3, R( F) = 0.066, wR( F 2) = 0.081. 2 (C 5H 19.47N 2O 5.24P), M r = 222.49, trigonal, (No. 148), Z = 18, a = 31.075 (2) ?, c = 6.1875 (4) ?, V = 5174.5 (6) ? 3, R( F) = 0.044, wR( F 2) = 0.107.
Breve rese?a del Dr. Armando Carnot Veunlens: el "Médico de los Pobres"
Tápanes Galvan,William;
Revista M??dica Electr?3nica , 2010,
Abstract: this work refers to the life and work of the matanzas physician armando carnot veulen, graduated in 1905 as dental surgeon, and in 1907 as doctor in medicine. his medical work was mainly distinguished by helping and caring several labor unions of matanzas and the low classes of the society. for that reason he was known as the physician of the poors.
On whitehead's second lemma for Lie algebras
William T. Fletcher
International Journal of Mathematics and Mathematical Sciences , 1982, DOI: 10.1155/s016117128200060x
Abstract: A proof of Whitehead's second lemma which is independent of the first Whitehead lemma is given.
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