845 research outputs found

    The evidence for jet-cloud interactions in a sample of high/intermediate-redshift radio galaxies

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    We present the result obtained from a study, based on long-slit spectroscopy, of the kinematics and ionization mechanisms of the line-emitting gas for a sample of four high/intermediate-redshift radio galaxies. In two of the galaxies (3C352 and 3C435A) the radio sources are of the same scale as the emission-line regions, whereas in the other two (3C34 and 3C330) the radio sources are extended on a larger scale than the emission-line structures. We see evidence for shock-acceleration of the emission-line gas in the extended regions of all the galaxies, even in the largest radio sources of our sample, in which the radio hot spots have passed the extended gas of the galaxies. The extended regions present highly disturbed kinematics (line-splitting and/or underlying broad components), which are difficult to explain if we do not consider a strong interaction between the radio-emitting components and the ambient gas. However, the dominant ionization mechanism of the line-emitting gas remains uncertain. We have compared the optical diagnostic line ratios of the galaxies in our sample with both AGN-photoionization and shock-ionization models. We find a lack of consistency in explaining the main ionization mechanism of the emission-line gas. This suggest that, if the extended regions are shock-ionized, some of the assumptions implicit in the shock models may need to be reconsidered. In addition, we have investigated the nebular continuum cointribution to the UV excess in the galaxies of our sample. We find a substantial nebular emission contribution to the UV continuum in all the cases. However, after the subtraction iof the nebular component, a significant UV excess remains in the extended nebulae of most of the objects.Comment: 33 pages, 24 figures, accepted for publication in MNRAS. (Abstract shortened for astro-ph

    Susceptibility to Flooding in Abdon Calderon of Canton Portoviejo Parish

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    This research was developed in the field of risk management against floods with the application of Geographic Information Systems (GIS) to assess the susceptibility to flooding in the central part of the Abdón Calderón parish of the Portoviejo canton where there are geographical and climatic characteristics that create favorable conditions for the occurrence of this phenomenon (slopes, edaphic composition with significant presence of clay and existence of patterns of intense rainfall in the winter season. Work was proposed to determine the susceptibility to flooding to which the research area is subject through the analysis of cartographic data and the thematic maps of slope and soil with a weighting methodology of the importance of the mentioned variables according to the qualitative evaluation. Iva carried out preliminarily through observation visits and taking of reference data in situ. The result was the obtaining of a susceptibility map where the high, medium and low susceptibility level can be observed in the downtown part of the Abdón Calderón parish

    Africanized Honey Bee in Oklahoma

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    The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311.Entomology and Plant Patholog

    Africanized honey bee in Oklahoma

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    The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

    On the representation of subsea aquitards in models of offshore fresh groundwater

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    This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 24 month embargo from date of publication (Nov 2017) in accordance with the publisher’s archiving policyFresh groundwater is widespread globally in offshore aquifers, and is particularly dependent on the properties of offshore aquitards, which inhibit seawater-freshwater mixing thereby allowing offshore freshwater to persist. However, little is known of the salinity distribution in subsea aquitards, especially in relation to the offshore freshwater distribution. This is critical for the application of recent analytical solutions to subsea freshwater extent given requisite assumptions about aquitard salinity. In this paper, we use numerical simulation to explore the extent of offshore freshwater in simplified situations of subsea aquifers and overlying aquitards, including in relation to the upward leakage of freshwater. The results show that available analytical solutions significantly overestimate the offshore extent of upwelling freshwater due to the presumption of seawater in the aquitard, whereas the seawater wedge toe is less sensitive to the assumed aquitard salinity. We also explore the use of implicit, conductance-based representations of the aquitard (i.e., using the popular SEAWAT code), and find that SEAWAT's implicit approach (i.e., GHB package) can represent the offshore distance of upwelling freshwater using a novel parameterization strategy. The results show that an estimate of the upward freshwater flow that is required to freshen the aquitard is associated with the dimensionless Rayleigh number, whereby the critical Rayleigh number that distinguishes fresh and saline regions (based on the position of the 0.5 isochlor) within the aquitard is approximately 2

    Development of Functional Microfold (M) Cells from Intestinal Stem Cells in Primary Human Enteroids.

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    Background & aimsIntestinal microfold (M) cells are specialized epithelial cells that act as gatekeepers of luminal antigens in the intestinal tract. They play a critical role in the intestinal mucosal immune response through transport of viruses, bacteria and other particles and antigens across the epithelium to immune cells within Peyer's patch regions and other mucosal sites. Recent studies in mice have demonstrated that M cells are generated from Lgr5+ intestinal stem cells (ISCs), and that infection with Salmonella enterica serovar Typhimurium increases M cell formation. However, it is not known whether and how these findings apply to primary human small intestinal epithelium propagated in an in vitro setting.MethodsHuman intestinal crypts were grown as monolayers with growth factors and treated with recombinant RANKL, and assessed for mRNA transcripts, immunofluorescence and uptake of microparticles and S. Typhimurium.ResultsFunctional M cells were generated by short-term culture of freshly isolated human intestinal crypts in a dose- and time-dependent fashion. RANKL stimulation of the monolayer cultures caused dramatic induction of the M cell-specific markers, SPIB, and Glycoprotein-2 (GP2) in a process primed by canonical WNT signaling. Confocal microscopy demonstrated a pseudopod phenotype of GP2-positive M cells that preferentially take up microparticles. Furthermore, infection of the M cell-enriched cultures with the M cell-tropic enteric pathogen, S. Typhimurium, led to preferential association of the bacteria with M cells, particularly at lower inoculum sizes. Larger inocula caused rapid induction of M cells.ConclusionsHuman intestinal crypts containing ISCs can be cultured and differentiate into an epithelial layer with functional M cells with characteristic morphological and functional properties. This study is the first to demonstrate that M cells can be induced to form from primary human intestinal epithelium, and that S. Typhimurium preferentially infect these cells in an in vitro setting. We anticipate that this model can be used to generate large numbers of M cells for further functional studies of these key cells of intestinal immune induction and their impact on controlling enteric pathogens and the intestinal microbiome

    ME 3902: Online Project-Based Engineering Experimentation

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    This course is designed to develop experimental skills in engineering measurement methods, based on electronic instrumentation and microcontrollers such as the Raspberry Pi and Arduino. Lectures are concerned with engineering analysis/design and principles of instrumentation, while the laboratory modules allow for the use of these devices in experiments. Lecture topics include discussions of standards, measurement/sensing devices, experiment planning, data acquisition/analysis, and report writing. Laboratory experiments address mechanical, energy, and materials measurements, and instrumentation. The course culminates with an open-ended project which will illuminate the skills gained by the student to utilize multiple sensors and equipment to monitor and/or control physical situations

    Study of scintillation in natural and synthetic quartz and methacrylate

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    Samples from different materials typically used as optical windows or light guides in scintillation detectors were studied in a very low background environment, at the Canfranc Underground Laboratory, searching for scintillation. A positive result can be confirmed for natural quartz: two distinct scintillation components have been identified, not being excited by an external gamma source. Although similar effect has not been observed neither for synthetic quartz nor for methacrylate, a fast light emission excited by intense gamma flux is evidenced for all the samples in our measurements. These results could affect the use of these materials in low energy applications of scintillation detectors requiring low radioactive background conditions, as they entail a source of background.Comment: Accepted for publication in Optical Material
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