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Search Results: 1 - 10 of 169873 matches for " Ayanna E. Lewis "
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Confounders in Adenoma Detection at Initial Screening Colonoscopy: A Factor in the Assessment of Racial Disparities as a Risk for Colon Cancer  [PDF]
Yakira David, Lorenzo Ottaviano, Jihye Park, Sadat Iqbal, Michelle Likhtshteyn, Samir Kumar, Helen Lyo, Ayanna E. Lewis, Brandon E. Lung, Jesse T. Frye, Li Huang, Ellen Li, Jie Yang, Laura Martello, Shivakumar Vignesh, Joshua D. Miller, Michele Follen, Evan B. Grossman
Journal of Cancer Therapy (JCT) , 2019, DOI: 10.4236/jct.2019.104022
Abstract: Background and Aims: The incidence and mortality of colorectal cancer is persistently highest in Black/African-Americans in the United States. While access to care, barriers to screening, and poverty might explain these findings, there in increased interest in examining biological factors that impact the colonic environment. Our group is examining biologic factors that contribute to disparities in development of adenomas prospectively. In preparation for this and to characterize a potential patient population, we conducted a retrospective review of initial screening colonoscopies in a cohort of patients. Methods: A retrospective review was performed on initial average risk screening colonoscopies on patients (age 45 - 75 years) during 2012 at three institutions. Descriptive statistics and multivariable logistic regression models were used to examine the relationship between potential risk factors and the detection of adenomas. Results: Of the 2225 initial screening colonoscopies 1495 (67.2%) were performed on Black/African-Americans and 566 (25.4%) on Caucasians. Multivariable logistic regression revealed that older age, male sex, current smoking and teaching gastroenterologists were associated with higher detection of adenomas and these were less prevalent among Black/African-Americas except for age. Neither race, ethnicity, BMI, diabetes mellitus, HIV nor insurance was associated with adenoma detection. Conclusion: In this sample, there was no association between race and adenoma detection. While this may be due to a lower prevalence of risk factors for adenomas in this sample, our findings were
On the Variability of Neural Network Classification Measures in the Protein Secondary Structure Prediction Problem
Eric Sakk,Ayanna Alexander
Applied Computational Intelligence and Soft Computing , 2013, DOI: 10.1155/2013/794350
Abstract:
On the Variability of Neural Network Classification Measures in the Protein Secondary Structure Prediction Problem
Eric Sakk,Ayanna Alexander
Applied Computational Intelligence and Soft Computing , 2013, DOI: 10.1155/2013/794350
Abstract: We revisit the protein secondary structure prediction problem using linear and backpropagation neural network architectures commonly applied in the literature. In this context, neural network mappings are constructed between protein training set sequences and their assigned structure classes in order to analyze the class membership of test data and associated measures of significance. We present numerical results demonstrating that classifier performance measures can vary significantly depending upon the classifier architecture and the structure class encoding technique. Furthermore, an analytic formulation is introduced in order to substantiate the observed numerical data. Finally, we analyze and discuss the ability of the neural network to accurately model fundamental attributes of protein secondary structure. 1. Introduction The protein secondary structure prediction problem can be phrased as a supervised pattern recognition problem [1–5] for which training data is readily available from reliable databases such as the Protein Data Bank (PDB) or CB513 [6]. Based upon training examples, subsequences derived from primary sequences are encoded based upon a discrete set of classes. For instance, three class encodings are commonly applied in the literature in order to numerically represent the secondary structure set (alpha helix , beta sheet , coil ) [7–11]. By applying a pattern recognition approach, subsequences of unknown classification can then be tested to determine the structure class to which they belong. Phrased in this way, backpropagation neural networks [7, 12–14], and variations on the neural network theme [8, 10, 11, 15–18] have been applied to the secondary structure prediction problem with varied success. Furthermore, many tools currently applying hybrid methodologies such as PredictProtein [19, 20], JPRED [8, 17, 21], SCRATCH [22, 23] and PSIPRED [24, 25] rely on the neural network paradigm as part of their prediction scheme. One of the main reasons for applying the neural network approach in the first place is that they tend be good universal approximators [26–30] and, theoretically, have the potential to create secondary structure models. In other words, after a given network architecture has been chosen and presented with a robust set of examples, the optimal parameters associated with the trained network, in principle, define an explicit function that can map a given protein sequence to its associated secondary structure. If the structure predicted by the network function is generally correct and consistent for an arbitrary input
Effects of Different Land Use Systems on Selected Physico-Chemical Properties of Soils in Northwestern Ethiopia
Yihenew G. Selassie,Getachew Ayanna
Journal of Agricultural Science , 2013, DOI: 10.5539/jas.v5n4p112
Abstract: Information about effects of different land use systems on soil physico-chemical properties is crucial for best land management practices. This study was, therefore, conducted to evaluate the same on Nitosols of Achefer District, Northwestern Ethiopia. The landuse systems studied included grassland, cultivated land, plantation forest and natural forest. The research was superimposed on land use systems that were located nearby on similar soil, contour line and slope classes. Undisturbed core and disturbed composite soil samples were collected randomly from two sites with three replications for each landuse system at two varying depths (0-15 cm and 15-30 cm). The undisturbed soil samples were analysed for bulk density, particle density, porosity and moisture content at different pressures; while the composite soil samples were analyzed for pH, organic carbon, total N and available P. Results of the study indicated that the lowest bulk and particle densities, the highest total porosity, and higher moisture content at both field capacity and permanent wilting percentage were found under natural forest land use system. In contrast, the highest bulk and particle densities, the lowest total porosity and lower water contents at both field capacity and permanent wilting percentage were obtained under the cultivated landuse system. Soil pH was moderately acidic under all landuse systems. The lowest organic carbon, total N, and C:N ratio were recorded under cultivated land; whereas the highest values of the same parameters were found under natural forest. In all landuse systems, organic carbon and total N decreased with soil depth. The highest and lowest available P contents were recorded under natural forest and grassland, respectively. From the results of the study it was possible to conclude that conversion of forest lands to cultivated and grasslands had detrimental effects on the soil physico-chemical properties under subsistance farming systems of the study area. It is, therefore, recommended that appropriate and integrated land management options for different land use syetems are required to sustain agricultural productivity while protecting the environment.
Gene Ontology: looking backwards and forwards
Suzanna E Lewis
Genome Biology , 2004, DOI: 10.1186/gb-2004-6-1-103
Abstract: Long ago, in the pre-genome era, biological databases had to come to terms with a formidable amount of work. After Crick and Watson elucidated the structure of DNA, the field of molecular biology exploded and an ever-increasing amount of information needed to be carefully managed and organized. This was particularly true after the invention of methods to sequence DNA in the late 1970s [1,2] and, consequently, the initiation of the genome sequencing programs in the late 1980s, all of which led to an even faster acceleration of work in this field. Keeping pace with molecular developments were biological data-management efforts. These first began emerging in the 1960s when Margaret Dayhoff [3] published the Atlas of Protein Sequence and Structure [4], which later went online as the Protein Identification Resource (PIR [5]). More than 30 years ago, in the 1970s, the first protein-structure database, Protein Data Bank (PDB [6]), was founded [7] and the Jackson Laboratory developed the first mammalian genetics database [8]. A few years later the first depositories for nucleotide sequences were established - with the EMBL 'Data Library' [9] beginning in 1981 [10] at Heidelberg, Germany and GenBank [11] in 1982 [12] at Los Alamos, New Mexico - followed soon afterwards by the formal establishment of the PIR in 1984 [13] for proteins. By the late 1980s and 1990s biological databases were popping up everywhere: in 1986 SwissProt [14]; in 1989 Caenorhabditis elegans AceDB [15]; in 1991 Arabidopsis AtDB [16]; in 1992 [17] The Institute for Genomic Research (TIGR) [18]; in 1993 FlyBase [19]; and in 1994 [20], Saccharomyces Genome Database (SGD) [21]. These groups all took advantage of concurrent technological advances and pioneered the use of the internet, the worldwide web, and relational database management systems (RDBMSs) and standard query language (SQL), when these technologies first became available during the 1980s and 1990s [22-24]. Thus, many biological databases bloome
The encyclopaedic impulse; Accounts of the origin of the rajadom of Sikka by two Sikkanese authors
E.D. Lewis
Bijdragen tot de Taal-, Land- en Volkenkunde , 1999,
Abstract:
Word and act in the curing rituals of the Ata Tana ’Ai of Flores
E.D. Lewis
Bijdragen tot de Taal-, Land- en Volkenkunde , 1989,
Abstract:
The tyranny of the text; Oral tradition and the power of writing in Sikka and Tana ?Ai, Flores
E.D. Lewis
Bijdragen tot de Taal-, Land- en Volkenkunde , 1998,
Abstract:
Ritual and reflexes of lost sovereignty in Sikka, a regency of Flores in eastern Indonesia
E.D. Lewis
Bijdragen tot de Taal-, Land- en Volkenkunde , 2008,
Abstract: In 1993 some among the Sikkanese population of the town of Maumere on the north coast of Flores in eastern Indonesia attended a ritual to reconcile the members of two branches of the family of the rajas of Sikka, a dynasty that had once ruled the district. The two branches had fallen out over differences in opinion about the last succession to the office of raja a few years before the end of the rajadom in the late 1950s. A description of the ritual, which was conducted in an urban rather than a village setting, and an analysis of the performance demonstrate much about the persistence of elements of the old Sikkanese religion in modern Sikkanese society. The contemporary Sikkanese are Christians and the regency of Sikka is part of the modern Indonesian nation-state.
Canadian Medical Residency Guide: Taking control of your future medical career
Jennifer E. Lewis
University of Toronto Medical Journal , 2006, DOI: 10.5015/utmj.v83i2.321
Abstract:
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