1,065 research outputs found
Organic sulfur: a spatially variable and understudied component of marine organic matter
Ā© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Longnecker, K., Oswald, L., Soule, M. C. K., Cutter, G. A., & Kujawinski, E. B. Organic sulfur: a spatially variable and understudied component of marine organic matter. Limnology and Oceanography Letters, (2020), doi:10.1002/lol2.10149.Sulfur (S) is a major heteroatom in organic matter. This project evaluated spatial variability in the concentration and molecularālevel composition of organic sulfur along gradients of depth and latitude. We measured the concentration of total organic sulfur (TOS) directly from whole seawater. Our data reveal high variability in organic sulfur, relative to established variability in total organic carbon or nitrogen. The deep ocean contained significant amounts of organic sulfur, and the concentration of TOS in North Atlantic Deep Water (NADW) decreased with increasing age while total organic carbon remained stable. Analysis of dissolved organic matter extracts by ultrahigh resolution mass spectrometry revealed that 6% of elemental formulas contained sulfur. The sulfurācontaining compounds were structurally diverse, and showed higher numbers of sulfurācontaining elemental formulas as NADW moved southward. These measurements of organic sulfur in seawater provide the foundation needed to define the factors controlling organic sulfur in the global ocean.We thank Catherine Carmichael, Winifred Johnson, and Gretchen Swarr for assistance with sample collection and processing, and Joe Jennings for the analysis of inorganic nutrients. The help of the captain and crew of the R/V Knorr and the other cruise participants during the āDeepDOMā cruise is appreciated. Two anonymous reviewers and Patricia Soranno provided thorough comments that greatly improved the manuscript. The ultrahigh resolution mass spectrometry samples were analyzed at the WHOI FTāMS Users' Facility that is funded by the National Science Foundation (grant OCEā0619608) and the Gordon and Betty Moore Foundation (GMBF1214). This project was funded by NSF grants OCEā1154320 (to EBK and KL), the W.M. Marquet Award (to KL), and OCEā1435708 (to GAC). The authors declare no conflicts of interest
A Comparison Between the Theoretical and Measured Longitudinal Stability Characteristics of an Airplane
This report covers an investigation of the application of the theory of dynamic longitudinal stability, based on the assumption of small oscillations, to oscillations an airplane is likely to undergo in flight. The investigation was conducted with a small parasol monoplane for the fixed-stick condition. The period and damping of longitudinal oscillations were determined by direct measurements of oscillations in flight and also by calculation in which the factors that enter the theoretical stability equation were determined in flight. A comparison of the above-mentioned characteristics obtained by these two methods indicates that the theory is applicable to the conditions encountered in flight
Rapid ascent and emplacement of basaltic lava during the 2005ā06 eruption of the East Pacific Rise at ca. 9Ā°51ā²N as inferred from CO2 contents
Ā© The Author(s), 2016. This is the author's version of the work and is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Earth and Planetary Science Letters 453 (2016): 152-160, doi:10.1016/j.epsl.2016.08.007.Eruption rates at the midāocean ridges (MORs) are believed to strongly
control the morphology and length of lava flows emplaced along the ridge axis, and thus
the structure and porosity of the upper oceanic crust. Eruption rate also represents one of
the few tools to gain insight into the driving pressures within sub-ridge magmatic
systems. As eruption rate is inferred to vary systematically along the global mid-ocean
ridge, understanding of how to assess eruption rate in submarine systems and how it
maps to observable features of the ridge axis would provide a powerful tool to understand
Earth's largest magmatic system. Eruption rates at MORs are poorly constrained,
however, because of a lack of direct observations, preventing the duration of an eruption
to be quantified. This study uses decompression experiments of MORB samples and
numerical modeling of CO2 degassing to reconstruct the timescales for magma ascent and
lava emplacement during the 2005ā06 eruption of the East Pacific Rise at ca. 9Ā°51āN.
Samples collected from the lava flow are all supersaturated in dissolved CO2 contents,
but CO2 decreases with distance from the vent, presumably as a consequence of
progressive CO2 diffusion into growing bubbles. Samples collected at the vent contain
~105 vesicles per cm3. Pieces of these samples were experimentally heated to 1225Ā°C at
high pressure and then decompressed at controlled rates. Results, plus those from
numerical modeling of diffusive bubble growth, indicate that magma rose from the axial
magma chamber to the seafloor in ā¤1 hour and at a rate of ā„2ā3 km hr-1. Our modeling,
as validated by experimental decompression of MORB samples with ~106 vesicles cm-3,
also suggests that CO2 degassed from the melt within ~10ā100 minutes as the vesicular
lava traveled ~ 1.7 km along the seafloor, implying a volumetric flow rate on order of
103ā4 m3 s-1. Given an ascent rate of ā„0.2 m s-1, the width of a rectangular dike feeding
the lava would have been ~1ā2 meters wide. MORB samples from the Pacific ridge are
generally more supersaturated in dissolved CO2 than those from slower spreading
Atlantic and Indian ridges. Our results suggest that Pacific MORBs ascend to the
seafloor faster than Atlantic or Indian MORBsThis project was partially
funded by a grant to J.E.G. from the U.S. National Science Foundation (OCE-1333882).2017-08-2
Organic Sulfur: A Spatially Variable and Understudied Component of Marine Organic Matter
Sulfur (S) is a major heteroatom in organic matter. This project evaluated spatial variability in the concentration and molecular-level composition of organic sulfur along gradients of depth and latitude. We measured the concentration of total organic sulfur (TOS) directly from whole seawater. Our data reveal high variability in organic sulfur, relative to established variability in total organic carbon or nitrogen. The deep ocean contained significant amounts of organic sulfur, and the concentration of TOS in North Atlantic Deep Water (NADW) decreased with increasing age while total organic carbon remained stable. Analysis of dissolved organic matter extracts by ultrahigh resolution mass spectrometry revealed that 6% of elemental formulas contained sulfur. The sulfurcontaining compounds were structurally diverse, and showed higher numbers of sulfur-containing elemental formulas as NADW moved southward. These measurements of organic sulfur in seawater provide the foundation needed to define the factors controlling organic sulfur in the global ocean
Loratadine dysregulates cell cycle progression and enhances the effect of radiation in human tumor cell lines
Metabolite composition of sinking particles differs from surface suspended particles across a latitudinal transect in the South Atlantic
Ā© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in [citation], doi:[doi].
Johnson, W. M., Longnecker, K., Soule, M. C. K., Arnold, W. A., Bhatia, M. P., Hallam, S. J., Van Mooy, B. A. S., & Kujawinski, E. B. Metabolite composition of sinking particles differs from surface suspended particles across a latitudinal transect in the South Atlantic. Limnology and Oceanography, (2019), doi:10.1002/lno.11255.Marine sinking particles transport carbon from the surface and bury it in deepāsea sediments, where it can be sequestered on geologic time scales. The combination of the surface ocean food web that produces these particles and the particleāassociated microbial community that degrades them creates a complex set of variables that control organic matter cycling. We use targeted metabolomics to characterize a suite of small biomolecules, or metabolites, in sinking particles and compare their metabolite composition to that of the suspended particles in the euphotic zone from which they are likely derived. These samples were collected in the South Atlantic subtropical gyre, as well as in the equatorial Atlantic region and the Amazon River plume. The composition of targeted metabolites in the sinking particles was relatively similar throughout the transect, despite the distinct oceanic regions in which they were generated. Metabolites possibly derived from the degradation of nucleic acids and lipids, such as xanthine and glycine betaine, were an increased mole fraction of the targeted metabolites in the sinking particles relative to surface suspended particles, while algalāderived metabolites like the osmolyte dimethylsulfoniopropionate were a smaller fraction of the observed metabolites on the sinking particles. These compositional changes are shaped both by the removal of metabolites associated with detritus delivered from the surface ocean and by production of metabolites by the sinking particleāassociated microbial communities. Furthermore, they provide a basis for examining the types and quantities of metabolites that may be delivered to the deep sea by sinking particles.The authors would like to thank the captain and crew of the R/V Knorr and R/V Atlantic Explorer, as well as Justin Ossolinski, Catherine Carmichael, and Sean Sylva for helping to make this dataāset possible. Special thanks to Colleen Durkin for sharing her data and providing feedback on the manuscript. Funding for this work came from the National Science Foundation (NSF Grant OCEā1154320 to EBK and KL) and a WHOI Ocean Ventures Fund award to WMJ. The instruments in the WHOI FTāMS Facility were purchased with support from the Gordon & Betty Moore Foundation and NSF. Support for WMJ was provided by a National Defense Science and Engineering Fellowship. Sequencing was performed under the auspices of the US Department of Energy (DOE) JGI Community Science Program (CSP) project (CSP 1685) supported by the Office of Science of US DOE Contract DEāAC02ā 05CH11231. Additional work related to sample collection and processing was supported by the G. Unger Vetlesen and Ambrose Monell Foundations, the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Institute for Advanced Study (CIFAR), and the Canada Foundation for Innovation through grants awarded to SJH. MPB was supported by a CIFAR Global Scholarship and NSERC postdoctoral fellowship
Microbial Communities Under Distinct Thermal and Geochemical Regimes in Axial and Off-Axis Sediments of Guaymas Basin
Cold seeps and hydrothermal vents are seafloor habitats fueled by subsurface energy sources. Both habitat types coexist in Guaymas Basin in the Gulf of California, providing an opportunity to compare microbial communities with distinct physiologies adapted to different thermal regimes. Hydrothermally active sites in the southern Guaymas Basin axial valley, and cold seep sites at Octopus Mound, a carbonate mound with abundant methanotrophic cold seep fauna at the Central Seep location on the northern off-axis flanking regions, show consistent geochemical and microbial differences between hot, temperate, cold seep, and background sites. The changing microbial actors include autotrophic and heterotrophic bacterial and archaeal lineages that catalyze sulfur, nitrogen, and methane cycling, organic matter degradation, and hydrocarbon oxidation. Thermal, biogeochemical, and microbiological characteristics of the sampling locations indicate that sediment thermal regime and seep-derived or hydrothermal energy sources structure the microbial communities at the sediment surface
Tumor cell heterogeneity and resistance; report from the 2018 CoffeyāHolden Prostate Cancer Academy Meeting
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147081/1/pros23729.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147081/2/pros23729_am.pd
Microbial communities under distinct thermal and geochemical regimes in axial and off-axis sediments of Guaymas Basin
Ā© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Teske, A., Wegener, G., Chanton, J. P., White, D., MacGregor, B., Hoer, D., de Beer, D., Zhuang, G., Saxton, M. A., Joye, S. B., Lizarralde, D., Soule, S. A., & Ruff, S. E. Microbial communities under distinct thermal and geochemical regimes in axial and off-axis sediments of Guaymas Basin. Frontiers in Microbiology, 12, (2021): 633649, https://doi.org/10.3389/fmicb.2021.633649.Cold seeps and hydrothermal vents are seafloor habitats fueled by subsurface energy sources. Both habitat types coexist in Guaymas Basin in the Gulf of California, providing an opportunity to compare microbial communities with distinct physiologies adapted to different thermal regimes. Hydrothermally active sites in the southern Guaymas Basin axial valley, and cold seep sites at Octopus Mound, a carbonate mound with abundant methanotrophic cold seep fauna at the Central Seep location on the northern off-axis flanking regions, show consistent geochemical and microbial differences between hot, temperate, cold seep, and background sites. The changing microbial actors include autotrophic and heterotrophic bacterial and archaeal lineages that catalyze sulfur, nitrogen, and methane cycling, organic matter degradation, and hydrocarbon oxidation. Thermal, biogeochemical, and microbiological characteristics of the sampling locations indicate that sediment thermal regime and seep-derived or hydrothermal energy sources structure the microbial communities at the sediment surface.Research on Guaymas Basin in the Teske lab is supported by NSF Molecular and cellular Biology grant 1817381 āCollaborative Research: Next generation physiology: a systems-level understanding of microbes driving carbon cycling in marine sedimentsā. Sampling in Guaymas Basin was supported by collaborative NSF Biological Oceanography grants 1357238 and 1357360 āCollaborative Research: Microbial carbon cycling and its interaction with sulfur and nitrogen transformations in Guaymas Basin hydrothermal sedimentsā to AT and SJ, respectively. SER was supported by an AITF/Eyes High Postdoctoral Fellowship and start-up funds provided by the Marine Biological Laboratory
Failure or success? Defensive strategies and piecemeal change among racial inequalities in the Brazilian banking sector
We analyze how Brazilian Black Movement organizations and banks deployed different mechanisms like cooperation, cooptation, and confrontation that generated affirmative action initiatives in the banking sector at the beginning of this century. Black movement organizations triggered an institutional change by connecting fields and exploring a constellation of strategies. However, Brazilian banks adopted defensive strategies aiming to accommodate their interests. We find that only piecemeal change occurred, as the fieldās structures ā resource distribution and power ā remained unscratched. We conclude by noting how the success of social movement strategies can depend upon the framing and sense-giving work that social movements conduct in their continuous jockeying activity toward incumbents
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