1,527 research outputs found

    Middle and late woodland period cultural transmission, residential mobility, and aggregation in the deep South

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    Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 24, 2010).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Dissertation advisor: Michael J. O'Brien.Vita.Ph. D. University of Missouri--Columbia 2009.This research attempts to reconstruct the extent of prehistoric human interaction within the lower Chattahoochee-Apalachicola River valley and neighboring Gulf Coast for the period spanning 200 B.C. to A.D. 1000. Using evolutionary models of population dynamics, intergroup cultural transmission (i.e., interaction) is inferred from changes in intra-assemblage ceramic decorative diversity and interassemblage ceramic distance across a 1000-year ceramic sequence. Two periods, ca. A.D. 200-370 and ca. A.D. 700-810, are noted for their high levels of decorative diversity and are interpreted to be periods during which intergroup cultural transmission increased. Interassemblage ceramic distance did not behave in the manner expected, and the deviations suggest that group residential strategies may be fluctuating in sync with pulses in interaction. In particular, the period ca. A.D. 370-700 may be characterized by a marked increase in residential mobility. Reconstructed PDSI values, a proxy composite measure of temperature and rainfall, are examined to search for a possible cause for changes in residential strategies. Two of the three periods of greatest below average PDSI values correspond to inferred increases in residential mobility at ca. A.D. 370 and ca. A.D. 810.Includes bibliographical reference

    Dissolved oxygen dynamics during a phytoplankton bloom in the Ross Sea polynya

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    The Ross Sea polynya is one of the most productive regions in the Southern Ocean. However, limited access and high spatio-temporal variability of physical and biological processes limit the use of conventional oceanographic methods to measure early season primary productivity. High-resolution observations from two Seagliders provide insights into the timing of a bloom in the southern Ross Sea polynya in December 2010. Changes in chlorophyll and oxygen concentrations are used to assess bloom dynamics. Using a ratio of dissolved oxygen to carbon, net primary production is estimated over the duration of the bloom showing a sensitive balance between net autotrophy and heterotrophy. The two gliders, observing spatially distinct regions during the same period, found net community production rates of -0.9±0.7 and 0.7±0.4 g C m-2 d-1. The difference highlights the spatial variability of biological processes and is probably caused by observing different stages of the bloom. The challenge of obtaining accurate primary productivity estimates highlights the need for increased observational efforts, particularly focusing on subsurface processes not resolved using surface or remote observations. Without an increased observational effort and the involvement of emerging technologies, it will not be possible to determine the seasonal trophic balance of the Ross Sea polynya and quantify the shelf's importance in carbon export

    Transcription Is Required to Establish Maternal Imprinting at the Prader-Willi Syndrome and Angelman Syndrome Locus

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    The Prader-Willi syndrome (PWS [MIM 17620]) and Angelman syndrome (AS [MIM 105830]) locus is controlled by a bipartite imprinting center (IC) consisting of the PWS-IC and the AS-IC. The most widely accepted model of IC function proposes that the PWS-IC activates gene expression from the paternal allele, while the AS-IC acts to epigenetically inactivate the PWS-IC on the maternal allele, thus silencing the paternally expressed genes. Gene order and imprinting patterns at the PWS/AS locus are well conserved from human to mouse; however, a murine AS-IC has yet to be identified. We investigated a potential regulatory role for transcription from the Snrpn alternative upstream exons in silencing the maternal allele using a murine transgene containing Snrpn and three upstream exons. This transgene displayed appropriate imprinted expression and epigenetic marks, demonstrating the presence of a functional AS-IC. Transcription of the upstream exons from the endogenous locus correlates with imprint establishment in oocytes, and this upstream exon expression pattern was conserved on the transgene. A transgene bearing targeted deletions of each of the three upstream exons exhibited loss of imprinting upon maternal transmission. These results support a model in which transcription from the Snrpn upstream exons directs the maternal imprint at the PWS-IC

    Ocean processes at the Antarctic continental slope

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    The Antarctic continental shelves and slopes occupy relatively small areas, but, nevertheless, are important for global climate, biogeochemical cycling and ecosystem functioning. Processes of water mass transformation through sea ice formation/melting and ocean-atmosphere interaction are key to the formation of deep and bottom waters as well as determining the heat flux beneath ice shelves. Climate models, however, struggle to capture these physical processes and are unable to reproduce water mass properties of the region. Dynamics at the continental slope are key for correctly modelling climate, yet their small spatial scale presents challenges both for ocean modelling and for observational studies. Cross-slope exchange processes are also vital for the flux of nutrients such as iron from the continental shelf into the mixed layer of the Southern Ocean. An © 2014 The Authors

    ‘Trying to pin down jelly’ - exploring intuitive processes in quality assessment for meta-ethnography

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    Background: Studies that systematically search for and synthesise qualitative research are becoming more evident in health care, and they can make an important contribution to patient care. However, there is still no agreement as to whether, or how we should appraise studies for inclusion. We aimed to explore the intuitive processes that determined the ‘quality’ of qualitative research for inclusion in qualitative research syntheses. We were particularly interested to explore the way that knowledge was constructed. Methods: We used qualitative methods to explore the process of quality appraisal within a team of seven qualitative researchers funded to undertake a meta-ethnography of chronic non-malignant musculoskeletal pain. Team discussions took place monthly between October 2010 and June 2012 and were recorded and transcribed. Data was coded and organised using constant comparative method. The development of our conceptual analysis was both iterative and collaborative. The strength of this team approach to quality came from open and honest discussion, where team members felt free to agree, disagree, or change their position within the safety of the group. Results: We suggest two core facets of quality for inclusion in meta-ethnography - (1) Conceptual clarity; how clearly has the author articulated a concept that facilitates theoretical insight. (2) Interpretive rigour; fundamentally, can the interpretation ‘be trusted?’ Our findings showed that three important categories help the reader to judge interpretive rigour: (ii) What is the context of the interpretation? (ii) How inductive is the interpretation? (iii) Has the researcher challenged their interpretation? Conclusions: We highlight that methods alone do not determine the quality of research for inclusion into a meta-ethnography. The strength of a concept and its capacity to facilitate theoretical insight is integral to meta-ethnography, and arguably to the quality of research. However, we suggest that to be judged ‘good enough’ there also needs to be some assurance that qualitative findings are more than simply anecdotal. Although our conceptual model was developed specifically for meta-ethnography, it may be transferable to other research methodologies

    Uptake and transport of novel amphiphilic polyelectrolyte-insulin nanocomplexes by caco-2 cells - towards oral insulin

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    “The original publication is available at www.springerlink.com”. Copyright SpringerPurpose: The influence of polymer architecture on cellular uptake and transport across Caco-2 cells of novel amphiphilic polyelectrolyte-insulin nanocomplexes was investigated. Method: Polyallylamine (PAA) (15 kDa) was grafted with palmitoyl chains (Pa) and subsequently modified with quaternary ammonium moieties (QPa). These two amphiphilic polyelectrolytes (APs) were tagged with rhodamine and their uptake by Caco-2 cells or their polyelectrolyte complexes (PECs) with fluorescein isothiocyanate-insulin (FITC-insulin) uptake were investigated using fluorescence microscopy. The integrity of the monolayer was determined by measurement of transepithelial electrical resistance (TEER). Insulin transport through Caco-2 monolayers was determined during TEER experiments. Result: Pa and insulin were co-localised in the cell membranes while QPa complexes were found within the cytoplasm. QPa complex uptake was not affected by calcium, cytochalasin D or nocodazole. Uptake was reduced by co-incubation with sodium azide, an active transport inhibitor. Both polymers opened tight junctions reversibly where the TEER values fell by up to 35 % within 30 minutes incubation with Caco-2 cells. Insulin transport through monolayers increased when QPa was used (0.27 ngmL-1 of insulin in basal compartment) compared to Pa (0.14 ngmL-1 of insulin in basal compartment) after 2 hours. Conclusion: These APs have been shown to be taken up by Caco-2 cells and reversibly open tight cell junctions. Further work is required to optimise these formulations with a view to maximising their potential to facilitate oral delivery of insulin.Peer reviewe

    Astabiotics: Antimicrobial Signal Transduction Activators

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    poster abstractThe increasing prevalence of multi-drug resistant Gram-negative bacteria is a major public health concern. All available antibiotics are inhibitors of targets essential for virulence or growth. CpxRA is a highly conserved bacterial signal transduction system that responds to extracytoplasmic membrane stress. CpxA is a sensor with kinase and phosphatase activity; upon activation, CpxA donates a phosphate group to CpxR, activating a transcriptional response. Activation of CpxRA reduces the flow of protein traffic through the cytoplasmic membrane, dramatically reducing the expression of virulence determinants. Activation of CpxRA abolishes the virulence of Salmonella Typhimurium in mice. We found that activation of CpxRA crippled the ability of Haemophilus ducreyi to cause disease in experimentally infected human volunteers. Using an Escherichia coli reporter strain, we developed a high throughput screen to detect compounds that activate CpxRA. In a pilot screen of 36,000 compounds, we identified 1 class of compounds that shifts the equilibrium of CpxA to kinase activity, activating CpxR. Based on its potency, the calculated effective dose of the lead compound (a nitroindole) was 10 mg/kg. Female mice tolerated 100 mg/kg of the nitroindole given twice a day for 3 days. A CpxRA activating mutant constructed in uropathogenic E. coli (UPEC) was severely impaired in a murine urinary tract infection model; thus, activation of CpxRA is a valid treatment strategy for UPEC. However, when female mice were challenged with UPEC and treated with 100 mg/kg of the nitroindole using the schedule above, there were no differences in the recovered CFU in the urine, bladder, and kidney of sham and compound-treated mice. Future studies will include medicinal optimization of the nitroindole and identification and optimization other leads that activate CpxRA. Although our pilot test of efficacy was negative, astabiotics have great potential as broad-spectrum, adjunctive therapies to existing antimicrobials for treatment of Gram-negative infections

    A Racial/Ethnic Performance Disparity on the Facial Recognition Test

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    The Facial Recognition Test is a widely used psychometric instrument for assessing visuoperceptual functioning. Only two prior studies have examined the effects of race/ethnicity on this test. Given that the United States has become more culturally diverse since the creation of the test, it is important to re-visit the effects of this demographic variable on performance. Participants were 75 males and 75 females between the ages of 18 and 43 years (M = 21.91, SD = 5.33). Racial/ethnic categories utilized by the U.S. Census Bureau were equally represented. No gender differences were observed. The race/ethnicity main effect was significant. The gender x race/ethnicity interaction was not significant. The data revealed a clear racial/ethnic performance disparity on the Facial Recognition Test
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