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Search Results: 1 - 10 of 220142 matches for " Shana C. Kerr "
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The Ccr4-Not Complex Interacts with the mRNA Export Machinery
Shana C. Kerr,Nowel Azzouz,Stephen M. Fuchs,Martine A. Collart,Brian D. Strahl,Anita H. Corbett,R. Nicholas Laribee
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0018302
Abstract: The Ccr4-Not complex is a key eukaryotic regulator of gene transcription and cytoplasmic mRNA degradation. Whether this complex also affects aspects of post-transcriptional gene regulation, such as mRNA export, remains largely unexplored. Human Caf1 (hCaf1), a Ccr4-Not complex member, interacts with and regulates the arginine methyltransferase PRMT1, whose targets include RNA binding proteins involved in mRNA export. However, the functional significance of this regulation is poorly understood.
The Structural Basis and Functional Consequences of Interactions Between Tetrodotoxin and Voltage-Gated Sodium Channels
Shana L. Geffeney,C. Ruben
Marine Drugs , 2006, DOI: 10.3390/md403143
Abstract: Tetrodotoxin (TTX) is a highly specific blocker of voltage-gated sodium channels. The dissociation constant of block varies with different channel isoforms. Until recently, channel resistance was thought to be primarily imparted by amino acid substitutions at a single position in domain I. Recent work reveals a novel site for tetrodotoxin resistance in the P-region of domain IV.
Categorizing US State Drinking Practices and Consumption Trends
William C. Kerr
International Journal of Environmental Research and Public Health , 2010, DOI: 10.3390/ijerph7010269
Abstract: US state alcohol consumption patterns and trends are examined in order to identify groups of states with similar drinking habits or cultures. Rates of heavy drinking and current abstention and per capita apparent consumption levels are used to categorize states. Six state groupings were identified: North Central and New England with the highest consumption and heavy drinking levels; Middle Atlantic, Pacific and South Coast with moderate drinking levels; and Dry South with the lowest drinking levels. Analyses of relationships between beer and spirits series for states within groups as compared to those in different groups failed to clearly indicate group cohesiveness.
The New Kid on the Block: The Northern Ontario Medical School
Jonathan Kerr,Linda C. Ashby
University of Toronto Medical Journal , 2004, DOI: 10.5015/utmj.v81i2.726
Innovative Educational Practice: Using Virtual Labs in the Secondary Classroom.
Marcel Satsky Kerr,Kimberly Rynearson,Marcus C. Kerr
Journal of Educators Online , 2004,
Abstract: Two studies investigated the effectiveness of teaching science labs online to secondary students. Study 1 compared achievement among students instructed using hands-on Chemistry labs versus those instructed using virtual Chemistry labs (eLabs). Study 2 compared the same groups of students again while both teachers instructed using hands-on Chemistry labs to determine whether teacher or student characteristics may have affected Study 1’s findings. Participants were high school Chemistry students from a Central Texas Independent School District. Results indicated that: students learn science effectively online, schools may experience cost savings from delivering labs online, and students gain valuable technology skills needed later in college and in the workplace.
Frequency Matrix Approach Demonstrates High Sequence Quality in Avian BARCODEs and Highlights Cryptic Pseudogenes
Mark Y. Stoeckle, Kevin C. R. Kerr
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043992
Abstract: The accuracy of DNA barcode databases is critical for research and practical applications. Here we apply a frequency matrix to assess sequencing errors in a very large set of avian BARCODEs. Using 11,000 sequences from 2,700 bird species, we show most avian cytochrome c oxidase I (COI) nucleotide and amino acid sequences vary within a narrow range. Except for third codon positions, nearly all (96%) sites were highly conserved or limited to two nucleotides or two amino acids. A large number of positions had very low frequency variants present in single individuals of a species; these were strongly concentrated at the ends of the barcode segment, consistent with sequencing error. In addition, a small fraction (0.1%) of BARCODEs had multiple very low frequency variants shared among individuals of a species; these were found to represent overlooked cryptic pseudogenes lacking stop codons. The calculated upper limit of sequencing error was 8×10?5 errors/nucleotide, which was relatively high for direct Sanger sequencing of amplified DNA, but unlikely to compromise species identification. Our results confirm the high quality of the avian BARCODE database and demonstrate significant quality improvement in avian COI records deposited in GenBank over the past decade. This approach has potential application for genetic database quality control, discovery of cryptic pseudogenes, and studies of low-level genetic variation.
Pseudopterosin Biosynthesis: Aromatization of the Diterpene Cyclase Product, Elisabethatriene
Amber C. Kohl,Russell G. Kerr
Marine Drugs , 2003, DOI: 10.3390/md101054
Abstract: Putative precursors in pseudopterosin biosynthesis, the hydrocarbons isoelisabethatriene (10) and erogorgiaene (11), have been identified from an extract of Pseudopterogorgia elisabethae collected in the Florida Keys. Biosynthetic experiments designed to test the utilization of these compounds in pseudopterosin production revealed that erogorgiaene is transformed to pseudopterosins A-D. Together with our previous data, it is now apparent that early steps in pseudopterosin biosynthesis involve the cyclization of geranylgeranyl diphosphate to elisabethatriene followed by the dehydrogenation and aromatization to erogorgiaene.
Revista Brasileira de Fruticultura , 2001, DOI: 10.1590/S0100-29452001000200027
Abstract: through molecular studies, the genetic distance among 12 genotypes of a. comosus for rapd markers (random amplified polymorphic dna) was determined using 11 primers (decamers) of the operon technologies inc. from the 12 genotypes, 1 came from jamaica, 2 from the state of acre (quinari and rbr-1), 2 from the state of maranh?o (turia?u and s?o domigos), 3 the state of piauí (cefas, floriano-1 and floriano-2), 2 from the state of bahia (monte alegre-1 and monte alegre-2) and 2 from minas gerais (pérola and smooth cayenne). by the analysis of cluster, using the method of upgma, a great divergence was verified among the genotypes of a. comosus studied or tima separation in two groups of a genetic distance of 31,1%.
Revista Brasileira de Fruticultura , 2001,
Abstract: Por meio de estudos moleculares, este trabalho determinou a distancia genética entre 12 genótipos de A. comosus por marcadores RAPD (Random Amplified Polymorphic DNA), utilizando 11 "primers" decameros da OPERON Technologies Inc. Dos 12 genótipos , 1 foi proveniente da Jamaica, 2 do Estado do Acre (Quinari e RBR-1), 2 do Estado do Maranh o (Turia u e S o Domingos), 3 do Estado do Piauí (Cefas, Floriano-1 e Floriano-2), 2 do Estado da Bahia (Monte Alegre-1 e Monte Alegre-2) e 2 de Minas Gerais (Pérola e Smouth Cayenne). Pela análise de "cluster", utilizando o método de UPGMA, foi constatada uma grande divergência entre os genótipos de A. comosus estudados com a separa o destes em dois grupos a uma distancia genética de 31,1%.
The Effectiveness of "Teach for America" and Other Under-certified Teachers
Ildiko Laczko-Kerr,David C. Berliner
Education Policy Analysis Archives , 2002,
Abstract: The academic achievements of students taught by under-certified primary school teachers were compared to the academic achievements of students taught by regularly certified primary school teachers. This sample of under-certified teachers included three types of under-qualified personnel: emergency, temporary and provisionally certified teachers. One subset of these under-certified teachers was from the national program "Teach For America (TFA)." Recent college graduates are placed by TFA where other under-qualified under-certified teachers are often called upon to work, namely, low-income urban and rural school districts. Certified teachers in this study were from accredited universities and all met state requirements for receiving the regular initial certificate to teach. Recently hired under-certified and certified teachers (N=293) from five low-income school districts were matched on a number of variables, resulting in 109 pairs of teachers whose students all took the mandated state achievement test. Results indicate 1) that students of TFA teachers did not perform significantly different from students of other under-certified teachers, and 2) that students of certified teachers out-performed students of teachers who were under-certified. This was true on all three subtests of the SAT 9—reading, mathematics and language arts. Effect sizes favoring the students of certified teachers were substantial. In reading, mathematics, and language, the students of certified teachers outperformed students of under-certified teachers, including the students of the TFA teachers, by about 2 months on a grade equivalent scale. Students of under-certified teachers make about 20% less academic growth per year than do students of teachers with regular certification. Traditional programs of teacher preparation apparently result in positive effects on the academic achievement of low-income primary school children. Present policies allowing under-certified teachers, including those from the TFA program, to work with our most difficult to teach children appear harmful. Such policies increase differences in achievement between the performance of poor children, often immigrant and minority children, and those children who are more advantaged.
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