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Search Results: 1 - 10 of 184317 matches for " Silvia E Smith "
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Comparative Genomic and Phylogenetic Approaches to Characterize the Role of Genetic Recombination in Mycobacterial Evolution
Silvia E. Smith, Patrice Showers-Corneli, Caitlin N. Dardenne, Henry H. Harpending, Darren P. Martin, Robert G. Beiko
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0050070
Abstract: The genus Mycobacterium encompasses over one hundred named species of environmental and pathogenic organisms, including the causative agents of devastating human diseases such as tuberculosis and leprosy. The success of these human pathogens is due in part to their ability to rapidly adapt to their changing environment and host. Recombination is the fastest way for bacterial genomes to acquire genetic material, but conflicting results about the extent of recombination in the genus Mycobacterium have been reported. We examined a data set comprising 18 distinct strains from 13 named species for evidence of recombination. Genomic regions common to all strains (accounting for 10% to 22% of the full genomes of all examined species) were aligned and concatenated in the chromosomal order of one mycobacterial reference species. The concatenated sequence was screened for evidence of recombination using a variety of statistical methods, with each proposed event evaluated by comparing maximum-likelihood phylogenies of the recombinant section with the non-recombinant portion of the dataset. Incongruent phylogenies were identified by comparing the site-wise log-likelihoods of each tree using multiple tests. We also used a phylogenomic approach to identify genes that may have been acquired through horizontal transfer from non-mycobacterial sources. The most frequent associated lineages (and potential gene transfer partners) in the Mycobacterium lineage-restricted gene trees are other members of suborder Corynebacterinae, but more-distant partners were identified as well. In two examined cases of potentially frequent and habitat-directed transfer (M. abscessus to Segniliparus and M. smegmatis to Streptomyces), observed sequence distances were small and consistent with a hypothesis of transfer, while in a third case (M. vanbaalenii to Streptomyces) distances were larger. The analyses described here indicate that whereas evidence of recombination in core regions within the genus is relatively sparse, the acquisition of genes from non-mycobacterial lineages is a significant feature of mycobacterial evolution.
Applicable Quality Models in Higher Education in Argentina  [PDF]
Lidia Giuffré, Silvia E. Ratto
Creative Education (CE) , 2013, DOI: 10.4236/ce.2013.410A005
Abstract: The aim of this paper is the study of quality management systems applied to higher education. The specific objectives are to present different models of approach to the concept of quality education applicable in Argentina: to study the legal framework governing university education, and to introduce considerations about its evaluation. The National Education Law 26026/2006 is clear about State responsibility to ensure quality education for all residents, and implementation of assessment policy to secure it. Accreditation is the process commonly used to give public account of the degree of compliance of higher education institutions. Periodic accreditation of undergraduate careers, whose titles correspond to professions regulated by the State, is performed. External evaluations present evaluation reports that are public.
Empowerment perceptions of educational managers from previously disadvantaged primary and high schools: An explorative study
E Smith
South African Journal of Education , 2006,
Abstract: The perceptions of educational manag ers from previously disadvantaged primary and high schools in the Nelson Mandela Metropole regarding the issue of empowerment are outlined and the perceptions of educational managers in terms of various aspects of empowerment at different levels reflected. A literature study, including an internet-based search, and empirical research were undertaken. In the empirical study, a self-administered questionnaire was distributed to 135 educational managers in the Nelson Mandela Metropole. To investigate the relationship between the independent and dependent variables, 12 null hypotheses were tested by means of statistical methods such as analysis of variance and correlation coefficients. The empirical results revealed highly significant relationships or differences between the variables. It is recommended that empowerment should be carefully managed and not used as a quick-fix solution to solve the problems in education. Empowerment should filter down through the school system from department level to the level of individual learner. Practical guidelines are provided and educational policy implications highlighted for implementation of empowerment in schools.
Changes in Diatom Biodiversity in Lake Sinclair, Baldwin County, Georgia, USA  [PDF]
Marká E. Smith, Kalina M. Manoylov
Journal of Water Resource and Protection (JWARP) , 2013, DOI: 10.4236/jwarp.2013.57074
Abstract:

The effects of increased water temperature on algal community composition were investigated in Lake Sinclair, Baldwin County, Georgia, USA. The lake received waste cooling water from a coal burning power plant. Discharges of recycled lake water were, on average, 15°C ± 1.5°C (and up to 23°C) warmer than typical ambient temperatures. Seasonal changes in algal composition were observed, and the warmer sample site had a greater diversity of diatom species year round independent of changes in temperature. Thermal pollution created a high percent dissimilarity between diatoms at the warmer site and the remainder of the lake. Species turnover observed in natural samples was not detected for the warmer site. Anthropogenic thermal pollution was implicated as the factor inducing changes in the natural algal community composition, which may impact other trophic levels and ultimately the overall ecology of Lake Sinclair.

Sequential gene profiling of basal cell carcinomas treated with imiquimod in a placebo-controlled study defines the requirements for tissue rejection
Monica C Panelli, Mitchell E Stashower, Herbert B Slade, Kina Smith, Christopher Norwood, Andrea Abati, Patricia Fetsch, Armando Filie, Shelley-Ann Walters, Calvin Astry, Eleonora Aricó, Yingdong Zhao, Silvia Selleri, Ena Wang, Francesco M Marincola
Genome Biology , 2007, DOI: 10.1186/gb-2007-8-1-r8
Abstract: We report a paired analysis of adjacent punch biopsies obtained pre- and post-treatment from 36 patients with BCC subjected to local application of imiquimod (n = 22) or vehicle cream (n = 14) in a blinded, randomized protocol. Four treatments were assessed (q12 applications for 2 or 4 days, or q24 hours for 4 or 8 days). RNA was amplified and hybridized to 17.5 K cDNA arrays. All treatment schedules similarly affected the transcriptional profile of BCC; however, the q12 × 4 days regimen, associated with highest effectiveness, induced the most changes, with 637 genes unequivocally stimulated by imiquimod. A minority of transcripts (98 genes) confirmed previous reports of interferon-α involvement. The remaining 539 genes portrayed additional immunological functions predominantly involving the activation of cellular innate and adaptive immune-effector mechanisms. Importantly, these effector signatures recapitulate previous observations of tissue rejection in the context of cancer immunotherapy, acute allograft rejection and autoimmunity.This study, based on a powerful and reproducible model of cancer eradication by innate immune mechanisms, provides the first insights in humans into the early transcriptional events associated with immune rejection. This model is likely representative of constant immunological pathways through which innate and adaptive immune responses combine to induce tissue destruction.In 2004, Aldara? (imiquimod 5% cream, 3M Pharmaceutical, St Paul, MN, USA) labeling was extended by the Food and Drug Administration to include treatment of superficial basal cell carcinoma (BCC) based upon randomized controlled trials demonstrating complete histological clearance in 78% to 87% of superficial BCC treated topically 5 days per week for 6 weeks [1,2]. Pilot-scale and investigator initiated trials had shown 90% to 100% clearance with q12 hours (twice per day) dosing [3].Imiquimod belongs to a family of synthetic small nucleotide-like molecules with potent
EL USO DE HONGOS MICORRíZICOS ARBUSCULARES COMO UNA ALTERNATIVA PARA LA AGRICULTURA
BARRERA B,SILVIA E;
Biotecnología en el Sector Agropecuario y Agroindustrial , 2009,
Abstract: the arbuscular mycorrrhizal fungi (amf) are soil fungi which form mutualistic symbiosis with the roots of plants. the amf give to the host a variety of benefits with respect to the non-host plants, for example, increased uptake of immobile or low availability nutrients from the soil, enhanced resistance to soil-bome pest and diseases, improved resistance to abiotic stress. the establishment of the symbiosis between amf and host plants involves a sequence of recognition events leading to the morphological and physiological integrations of the two symbionts. the use of the amf as biotechnology tool is important, hence the need to know about the effect that soil physical-chemical conditions causing them, to achieve a better profit in agriculture. we can talk about specificity between amf and host due the responses of amf to the soil edaphic conditions, plant's metabolisms, root architecture and ecological strategies of the amf. the use of amf in agriculture contribute to improve the nutritional level of the plant, however, monocultures in the agroecosystem, may be causing a decline in the amf diversity and as a result these microorganism could be offering beneficial effects, but restricted to the host.
Subclasses of close-to-convex functions
E. M. Silvia
International Journal of Mathematics and Mathematical Sciences , 1983, DOI: 10.1155/s0161171283000393
Abstract: Let ° ’ |[C,D], ¢ ’1 ¢ ‰ ¤D Keywords univalent --- convex --- starlike --- subordination --- convolution.
EL USO DE HONGOS MICORRíZICOS ARBUSCULARES COMO UNA ALTERNATIVA PARA LA AGRICULTURA ARBUSCULAR MYCORRHIZAL FUNGI AS ALTERNATIVE TO SUSTENTABLE AGRICULTURE
SILVIA E BARRERA B
Biotecnología en el Sector Agropecuario y Agroindustrial , 2009,
Abstract: Los hongos micorrízicos arbusculares (HMA) son organismos del suelo que viven simbióticamente con la mayoría de plantas. Ellos les aportan beneficios, dándoles ventajas con respecto a las plantas no micorrizadas, como por ejemplo facilitándole a la planta la toma de nutrientes de baja disponibilidad o de poca movilidad en el suelo, evitando la acción de microorganismo patógenos en la raíz, aumentando la tolerancia de la planta a condiciones de stress abiótico en el suelo, entre otros beneficios. El establecimiento de la simbiosis entre el hongo y la planta lleva a una secuencia de etapas de reconocimiento causando cambios tanto morfológicos como fisiológicos en los dos organismos que interactúan. Como herramienta biotecnológica el uso de estos microorganismos es de gran importancia, por lo que se requiere conocer acerca del efecto que las condiciones físico-químicas del suelo causan en ellos, para lograr un mejor beneficio en la agricultura. Se puede hablar de especificidad entre HMA y hospederos debido a la respuesta de los HMA a las condiciones edáficas del suelo y a otras características, como el metabolismo de las plantas, la arquitectura de la raíz y las estrategias ecológicas de los hongos. El uso de HMA en la agricultura contribuye a mejorar el nivel nutricional de la planta, sin embargo, la condición de monocultivo en los agroecosistemas, puede estar causando una disminución en la diversidad de HMA y como consecuencia, estos microorganismos podrían estar brindando un efecto aunque benéfico, limitado a los hospederos. The arbuscular mycorrrhizal fungi (AMF) are soil fungi which form mutualistic symbiosis with the roots of plants. The AMF give to the host a variety of benefits with respect to the non-host plants, for example, increased uptake of immobile or low availability nutrients from the soil, enhanced resistance to soil-bome pest and diseases, improved resistance to abiotic stress. The establishment of the symbiosis between AMF and host plants involves a sequence of recognition events leading to the morphological and physiological integrations of the two symbionts. The use of the AMF as biotechnology tool is important, hence the need to know about the effect that soil physical-chemical conditions causing them, to achieve a better profit in agriculture. We can talk about specificity between AMF and host due the responses of AMF to the soil edaphic conditions, plant's metabolisms, root architecture and ecological strategies of the AMF. The use of AMF in agriculture contribute to improve the nutritional level of the plant, however, monocultures
Rese a de "The Labor of Development. Workers and the Transformation of Capitalism in Kerala, India" de Patrick Heller
Silvia E. Giorguli Saucedo
Estudios Demográficos y Urbanos , 2004,
Abstract:
Estructuras familiares y oportunidades educativas de los ni os y ni as en México
Silvia E. Giorguli Saucedo
Estudios Demográficos y Urbanos , 2002,
Abstract:
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