1,095 research outputs found

    Primary isolated extramedullary plasmacytoma of the colon: a case report

    Get PDF
    The original publication is available at http://www.samj.org.zaA 10th case of extramedullary plasmacytoma (EMP) of the colon is reported. The term 'primary isolated extramedullary plasmacytoma' is preferred to those terms previously used. A broad classification of plasmacytoma of the gastrointestinal tract is suggested and a management policy, based on this classification, is outlined.Publishers' versio

    Phase Stable RF-over-fiber Transmission using Heterodyne Interferometry

    Full text link
    New scientific applications require phase-stabilized RF distribution to multiple remote locations. These include phased-array radio telescopes and short pulse free electron lasers. RF modulated onto a CW optical carrier and transmitted via fiber is capable of low noise, but commercially available systems aren't long term stable enough for these applications. Typical requirements are for less than 50fs long term temporal stability between receivers, which is 0.05 degrees at 3GHz. Good results have been demonstrated for RF distribution schemes based on transmission of short pulses, but these require specialized free-space optics and high stability mechanical infrastructure. We report a method which uses only standard telecom optical and RF components, and achieves less than 20fs RMS error over 300m of standard single-mode fiber. We demonstrate stable transmission of 3GHz over 300m of fiber with less than 0.017 degree (17fs) RMS phase error. An interferometer measures optical phase delay, providing information to a feed-forward correction of RF phase

    Overall evaluation of Skylab imagery for mapping of Latin America

    Get PDF
    The author has identified the following significant results. Skylab imagery is both desired and needed by the Latin American catographic agencies. The imagery is cost beneficial for the production of new mapping and maintenance of existing maps at national topographic series scales. If this information was available on a near time routine coverage basis, it would provide an excellent additional data base to the Latin American cartographic community, specifically Argentina, Bolivia, Chile, Colombia, Dominican Republic, Guatemala, Paraguay, and Venezuela

    Insensitivity of visual short-term memory to irrelevant visual information

    Get PDF
    Several authors have hypothesised that visuo-spatial working memory is functionally analogous to verbal working memory. Irrelevant background speech impairs verbal short-term memory. We investigated whether irrelevant visual information has an analogous effect on visual short-term memory, using a dynamic visual noise (DVN) technique known to disrupt visual imagery (Quinn & McConnell, 1996a). Experiment 1 replicated the effect of DVN on pegword imagery. Experiments 2 and 3 showed no effect of DVN on recall of static matrix patterns, despite a significant effect of a concurrent spatial tapping task. Experiment 4 showed no effect of DVN on encoding or maintenance of arrays of matrix patterns, despite testing memory by a recognition procedure to encourage visual rather than spatial processing. Serial position curves showed a one-item recency effect typical of visual short-term memory. Experiment 5 showed no effect of DVN on short-term recognition of Chinese characters, despite effects of visual similarity and a concurrent colour memory task that confirmed visual processing of the characters. We conclude that irrelevant visual noise does not impair visual short-term memory. Visual working memory may not be functionally analogous to verbal working memory, and different cognitive processes may underlie visual short-term memory and visual imagery

    Particulate organic carbon and nitrogen export from major Arctic rivers

    Get PDF
    Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 30 (2016): 629–643, doi:10.1002/2015GB005351.Northern rivers connect a land area of approximately 20.5 million km2 to the Arctic Ocean and surrounding seas. These rivers account for ~10% of global river discharge and transport massive quantities of dissolved and particulate materials that reflect watershed sources and impact biogeochemical cycling in the ocean. In this paper, multiyear data sets from a coordinated sampling program are used to characterize particulate organic carbon (POC) and particulate nitrogen (PN) export from the six largest rivers within the pan-Arctic watershed (Yenisey, Lena, Ob', Mackenzie, Yukon, Kolyma). Together, these rivers export an average of 3055 × 109 g of POC and 368 × 109 g of PN each year. Scaled up to the pan-Arctic watershed as a whole, fluvial export estimates increase to 5767 × 109 g and 695 × 109 g of POC and PN per year, respectively. POC export is substantially lower than dissolved organic carbon export by these rivers, whereas PN export is roughly equal to dissolved nitrogen export. Seasonal patterns in concentrations and source/composition indicators (C:N, δ13C, Δ14C, δ15N) are broadly similar among rivers, but distinct regional differences are also evident. For example, average radiocarbon ages of POC range from ~2000 (Ob') to ~5500 (Mackenzie) years before present. Rapid changes within the Arctic system as a consequence of global warming make it challenging to establish a contemporary baseline of fluvial export, but the results presented in this paper capture variability and quantify average conditions for nearly a decade at the beginning of the 21st century.National Science Foundation Grant Numbers: 0229302, 0732985; U.S. Geological Survey; Department of Indian and Northern Affairs2016-11-1

    Genetic and seasonal determinants of vitamin D status in Confederated Salish and Kootenai Tribes (CSKT) participants

    Get PDF
    Background: Vitamin D is a hormone produced in the skin upon ultraviolet B (UVB) radiation. Vitamin D is a crucial regulator of calcium and phosphate levels for bone mineralization and other physiological roles. Vitamin D levels vary globally in human populations due to genetics, geography, and other demographic factors. It is estimated that 20-85 % of the variability in vitamin D levels is driven by genetic variation. To improve our understanding of contributors to vitamin D levels, we conducted a candidate-gene study in partnership with the Confederated Salish and Kootenai Tribes (CSKT). Methods: We recruited 472 CSKT study participants on the Flathead Reservation in Montana. Demographic factors included age, BMI, and gender (185 male and 287 female; ≥ 18 years old). Genomic DNA and plasma were isolated from whole blood. We sequenced 14 vitamin D regulatory candidate genes: CASR, CUBN, CYP2R1, CYP3A4,CYP24A1, CYP27B1, DHCR7, GC, RXRA, RXRB, RXRG, SULT2A1, UGT1A4, and VDR. We also measured plasma levels of vitamin D and vitamin D metabolites by liquid chromatography/mass-spectrometry (LC/MS), including the clinical marker of vitamin D status, 25-hydroxyvitamin D3 [25(OH)D3]. We tested demographic factors as well as common and rare genetic variants for statistical associations with vitamin D levels using bioinformatics software and R statistical programming language code. Results: We identified 7,370 total genetic variants with 8% (n = 585) of them being novel. We identified 60 genetic variants that may be of clinical significance (disease associated or predicted to influence medication response). Vitamin D levels were below sufficiency [25(OH)D3 + 25(OH)D2 levels \u3c 20 ng/mL] in 56 % of CSKT participants across the year. We observed seasonal vitamin D and metabolite level fluctuations in a seasonal, sinusoidal statistical model with peak concentrations in June – August and trough concentrations in December – February. In linear regression analysis, we found that age, BMI, season, and 5 variants in CUBN and CYP3A4 were significantly associated with 25(OH)D3 concentration (p-value\u3c 0.05). In logistic regression, we found that 4 variants in CUBN, CYP3A4, and UGT1A4 were associated with 25(OH)D sufficiency status [25(OH)D3 + 25(OH)D2 levels of 20 ng/mL] (p-value\u3c 0.05). Multivariate linear regression analysis revealed that genetic variation alone explained ~13% of the variability in 25(OH)D3 concentration in CSKT participants. Genetic variation and environmental factors together explained ~23 % of the variability in 25(OH)D3 concentration in CSKT participants. It is likely that genetic variation in additional genes and other environmental factors (e.g., dietary vitamin D intake) that were not included in this study explain the remaining variability in 25(OH)D3 concentration. Conclusion: This research addresses the need for increased inclusion of American Indian and Alaska Natives in precision medicine health research. We are the first to describe the contribution of season and genetics to vitamin D levels in an American Indian population. Our next steps will be to use these findings to perform mechanistic studies and develop interventional strategies for the CSKT people

    Depths and Thermal Habitat Used by Large versus Small Northern Pike in Three Minnesota Lakes

    Full text link
    We monitored depths and temperatures used by large (>71‐cm) versus small Northern Pike Esox lucius in three north‐central Minnesota lakes with either acoustic telemetry or archival tags. Individual Northern Pike demonstrated flexibility in depths used within a season and between years. The fish had some tolerance for low levels of dissolved oxygen (<3 mg/L), but depth selection was generally constrained by low dissolved oxygen in summer and winter. The fish more fully exploited all available depths during winter and thermal turnover periods. During July and August, large Northern Pike tended to follow the thermocline into cooler water as upper water layers warmed. Selection ratios indicated that large Northern Pike preferred water temperatures of 16–21°C during August when temperatures up to 28°C were available. In two lakes providing dense overhead cover from water lilies in shallow water, small Northern Pike used warmer, shallower water compared with large fish during summer. In a third lake providing no such cover, small fish were more often in deeper, cooler water. For small Northern Pike, temperature seemed to be a secondary habitat consideration behind the presence of shallow vegetated cover. This study provided detailed temperature selection information that will be useful when considering temperature as an ecological resource for different sizes of Northern Pike.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141595/1/tafs1629.pd
    corecore