2,714 research outputs found
Insights from the U-238-th-234 method into the coupling of biological export and the cycling of cadmium, cobalt, and manganese in the southeast Pacific Ocean
Author Posting. © American Geophysical Union, 2019. 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 33(1), (2019): 15-36, doi:10.1029/2018GB005985.Better constraints on the magnitude of particulate export and the residence times of trace elements are required to understand marine food web dynamics, track the transport of anthropogenic trace metals in the ocean, and improve global climate models. While prior studies have been successful in constructing basinâscale budgets of elements like carbon in the upper ocean, the cycling of particulate trace metals is poorly understood. The 238Uâ234Th method is used here with data from the GPâ16 GEOTRACES transect to investigate the upper ocean processes controlling the particulate export of cadmium, cobalt, and manganese in the southeastern Pacific. Patterns in the flux data indicated that particulate cadmium and cobalt behave similarly to particulate phosphorus and organic carbon, with the highest export in the productive coastal region and decreasing flux with depth due to remineralization. The export of manganese was influenced by redox conditions at the low oxygen coastal stations and by precipitation and/or scavenging elsewhere. Residence times with respect to export (total inventory divided by particulate flux) for phosphorus, cadmium, cobalt, and manganese in the upper 100 and 200 m were determined to be on the order of months to years. These GEOTRACESâbased synthesis efforts, combining a host of concentration and tracer data with unprecedented resolution, will help to close the oceanic budgets of trace metals.This work was supported by the National Science Foundation (OCEâ1232669 and OCEâ1518110), and Erin Black was also funded by a NASA Earth and Space Science Graduate Fellowship (NNX13AP31H). The authors would like to thank the captain, crew, and scientists aboard the R/V Thomas G. Thompson. A special thanks to two anonymous reviewers and Virginie Sanial for providing the additional 228Raâbased estimates for Cd. All original data have been made available in either the supporting information or through BCOâDMO (see Website and Database References).2019-06-1
Cost-effectiveness of Dermabond versus sutures for lacerated wound closure: A randomised controlled trial
1. For management of simple lacerated wounds, tissue adhesive (Dermabond) achieved more positive outcomes but incurred higher cost, compared with standard sutures. 2. Dermabond may be more cost-effective than standard sutures from a societal viewpoint. 3. Use of sutures required more nursing time and additional costs from subsequent dressing, whereas use of Dermabond incurred higher equipment costs. 4. Dermabond achieved better appearance outcome and patient satisfaction, compared with sutures. 5. Pain levels were not significantly different in patients treated with Dermabond or sutures
An ITAM-signaling pathway controls cross-presentation of particulate but not soluble antigens in dendritic cells
Dendritic cells (DC) possess a unique capacity for presenting exogenous antigen on major histocompatibility class I, a process that is referred to as cross-presentation, which serves a critical role in microbial and tumor immunity. During cross-presentation, antigens derived from pathogen-infected or tumor cells are internalized and processed by DCs for presentation to cytotoxic T lymphocytes (CTLs). We demonstrate that a signaling pathway initiated by the immunoreceptor tyrosineâbased activation motif (ITAM)âcontaining adaptors DAP12 and FcRÎł utilizes the Vav family of Rho guanine nucleotide exchange factors (GEFs) for processing and cross-presentation of particulate, but not soluble, antigens by DCs. Notably, this novel pathway is crucial for processing and presentation of particulate antigens, such as those associated with Listeria monocytogenes bacteria, yet it is not required for antigen uptake. Mechanistically, we provide evidence that in DCs, Vav GEFs are essential to link ITAM-dependent receptors with the activation of the NOX2 complex and production of reactive oxygen species (ROS), which regulate phagosomal pH and processing of particulate antigens for cross-presentation. Importantly, we show that genetic disruption of the DAP12/FcRÎłâVav pathway leads to antigen presentation defects that are more profound than in DCs lacking NOX2, suggesting that ITAM signaling also controls cross-presentation in a ROS-independent manner
Macrophage migration inhibitory factor stimulated by Helicobacter pylori increases proliferation of gastric epithelial cells
AIM: Helicobacter pylori (H pylori) is associated with increased gastric inflammatory and epithelial expression of macrophage migration inhibitory factor (MIF) and gastric epithelial cell proliferation. This study aimed at determining whether H pylori directly stimulates release of MIF in monocytes, whether the cag pathogenicity island (PAI) is involved for this function, and whether MIF stimulated by H pylori increases gastric epithelial cell proliferation in vitro. METHODS: A cytotoxic wild-type H pylori strain (TN2)and its three isogenic mutants (TN2âłcag, TN2âłcagA and TN2âłcagE) were co-cultured with cells of a human monocyte cell line, THP-1, for 24 h at different organism/cell ratios. MIF in the supernatants was measured by an ELISA. Cells of a human gastric cancer cell line, MKN45, were then co-cultured with the supernatants, with and without monoclonal anti-MIF antibody for 24 h. The cells were further incubated for 12 h after addition of (3)H-thymidine, and the levels of incorporation of (3)H-thymidine were measured with a liquid scintillation counter. RESULTS: The wild-type strain and the isogenic mutants, TN2âłcagA and TN2âłcagE, increased MIF release at organism/cell ratios of 200/1 and 400/1, but not at the ratios of 50/1 and 100/1. However, the mutant TN2âłcag did not increase the release of MIF at any of the four ratios. (3)H-thymidine readings for MKN-45 cells were significantly increased with supernatants derived from the wild-type strain and the mutants TN2âłcagA and TN2âłcagE, but not from the mutant TN2âłcag. Moreover, in the presence of monoclonal anti-MIF antibody, the stimulatory effects of the wild-type strain on cell proliferation disappeared. CONCLUSION: H pylori stimulates MIF release in monocytes, likely through its cag PAI, but not related to cagA or cagE. H pylori-stimulated monocyte culture supernatant increases gastric cell proliferation, which is blocked by anti-MIF antibody, suggesting that MIF plays an important role in H pylori-induced gastric epithelial cell proliferation
Near-field iron and carbon chemistry of non-buoyant hydrothermal plume particles, Southern East Pacific Rise 15°S
Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Marine Chemistry 201 (2018): 183-197, doi:10.1016/j.marchem.2018.01.011.Iron (Fe)-poor surface waters limit phytoplankton growth and their ability to remove carbon (C)
from the atmosphere and surface ocean. Over the past few decades, research has focused on
constraining the global Fe cycle and its impacts on the global C cycle. Hydrothermal vents have
become a highly debated potential source of Fe to the surface ocean. Two main mechanisms for
transport of Fe over long distances have been proposed: Fe-bearing nanoparticles and organic C
complexation with Fe in the dissolved (dFe) and particulate (pFe) pools. However, the ubiquity
and importance of these processes is unknown at present, and very few vents have been
investigated for Fe-Corg interactions or the transport of such materials away from the vent. Here
we describe the near-field contributions (first ~100 km from ridge) of pFe and Corg to the
Southern East Pacific Rise (SEPR) plume, one of the largest known hydrothermal plume features
in the global ocean. Plume particles (> 0.2 ÎŒm) were collected as part of the U.S. GEOTRACES
Eastern Pacific Zonal Transect cruise (GP16) by in-situ filtration. Sediment cores were also
collected to investigate the properties of settling particles. In this study, X-ray absorption near
edge structure (XANES) spectroscopy was used in two complementary X-ray synchrotron
approaches, scanning transmission X-ray microscopy (STXM) and X-ray microprobe, to
investigate the Fe and C speciation of particles within the near-field non-buoyant SEPR plume.
When used in concert, STXM and X-ray microprobe provide fine-scale and representative
information on particle morphology, elemental co-location, and chemical speciation. Bulk
chemistry depth profiles for particulate Corg (POC), particulate manganese (pMn), and pFe
indicated that the source of these materials to the non-buoyant plume is hydrothermal in origin.
The plume particles at stations within the first ~100 km down-stream of the ridge were
composites of mineral (oxidized Fe) and biological materials (organic C, Corg). Iron chemistry
in the plume and in the core-top suspended sediment fluff layer were both dominated by Fe(III)
phases, such as Fe(III) oxyhydroxides and Fe(III) phyllosilicates. Particulate sulfur (pS) was a
rare component of our plume and sediment samples. When pS was detected, it was in the form of
an Fe sulfide mineral phase, composing †0.4% of the Fe on a per atom basis. The resuspended
sediment fluff layer contained a mixture of inorganic (coccolith fragments) and Corg bearing
(lipid-rich biofilm-like) materials. The particle morphology and co-location of C and Fe in the
sediment was different from that in plume particles. This indicates that if the Fe-Corg composite
particles settle rapidly to the sediments, then they experience strong alteration during settling and/or within the sediments. Overall, our observations indicate that the particles within the first ~
100 km of the laterally advected plume are S-depleted, Fe(III)-Corg composites indicative of a
chemically oxidizing plume with strong biological modification. These findings confirm that the
Fe-Corg relationships observed for non-buoyant plume particles within ~ 100 m of the vent site
are representative of particles within this region of the non-buoyant plume (~100 km). These
findings also point to dynamic alteration of Fe-Corg bearing particles during transport and
settling. The specific biogeochemical processes at play, and the implications for nutrient cycling
in the ocean are currently unknown and represent an area of future investigation
Seasonality of Influenza A(H3N2) Virus: A Hong Kong Perspective (1997â2006)
BACKGROUND: The underlying basis for the seasonality of influenza A viruses is still uncertain. Phylogenetic studies investigated this phenomenon but have lacked sequences from more subtropical and tropical regions, particularly from Southeast Asia. METHODOLOGY/PRINCIPAL FINDINGS: 281 complete hemagglutinin (HA) and neuraminidase (NA) sequences were obtained from influenza A(H3N2) viruses, collected over 10 years (1997-2006) from Hong Kong. These dated sequences were analyzed with influenza A(H3N2) vaccine strain sequences (Syd/5/97, Mos/10/99, Fuj/411/02, Cal/7/04) and 315 other publicly available dated sequences from elsewhere, worldwide. In addition, the NA sequence alignment was inspected for the presence of any naturally occurring, known, neuraminidase inhibitor (NAI) resistance-associated amino acid mutations (R292K and E119V). Before 2001, the Hong Kong HA and NA sequences clustered more closely with the older vaccine sequences (Syd/5/97, Mos/10/99) than did sequences from elsewhere. After 2001, this trend reversed with significant clusters containing HA and NA sequences from different locations, isolated at different times, suggesting that viral migration may account for much of the influenza A(H3N2) seasonality during this 10-year period. However, at least one example from Hong Kong was found suggesting that in some years, influenza A(H3N2) viruses may persist in the same location, perhaps continuing to circulate, sub-clinically, at low levels between seasons, to re-emerge in the influenza season the following year, relatively unchanged. None of these Hong Kong influenza A(H3N2) NA sequences contained any of the known NAI-resistance associated mutations. CONCLUSIONS/SIGNIFICANCE: The seasonality of influenza A(H3N2) may be largely due to global migration, with similar viruses appearing in different countries at different times. However, occasionally, some viruses may remain within a single location and continue to circulate within that population, to re-emerge during the next influenza season, with relatively little genetic change. Naturally occurring NAI resistance mutations were absent or, at least, very rare in this population
News from the Muon (g-2) Experiment at BNL
The magnetic moment anomaly a_mu = (g_mu - 2) / 2 of the positive muon has
been measured at the Brookhaven Alternating Gradient Synchrotron with an
uncertainty of 0.7 ppm. The new result, based on data taken in 2000, agrees
well with previous measurements. Standard Model evaluations currently differ
from the experimental result by 1.6 to 3.0 standard deviations.Comment: Talk presented at RADCOR - Loops and Legs 2002, Kloster Banz,
Germany, September 8-13 2002, to be published in Nuclear Physics B (Proc.
Suppl.); 5 pages, 3 figure
The Muon Anomalous Magnetic Moment and the Standard Model
The muon anomalous magnetic moment measurement, when compared with theory,
can be used to test many extensions to the standard model. The most recent
measurement made by the Brookhaven E821 Collaboration reduces the uncertainty
on the world average of a_mu to 0.7 ppm, comparable in precision to theory.
This paper describes the experiment and the current theoretical efforts to
establish a correct standard model reference value for the muon anomaly.Comment: Plenary Talk; PANIC'02 XVI Particles and Nuclear International
Conference, Osaka, Japan; Sept. 30 - Oct. 4, 2002; Report describes the
published 0.7 ppm result and updates the theory statu
Search for Lorentz and CPT Violation Effects in Muon Spin Precession
The spin precession frequency of muons stored in the storage ring has
been analyzed for evidence of Lorentz and CPT violation. Two Lorentz and CPT
violation signatures were searched for: a nonzero
(=); and a sidereal variation of
. No significant effect is found, and the following
limits on the standard-model extension parameters are obtained: GeV; GeV; and the 95% confidence level limits
GeV and
GeV.Comment: 5 pages, 3 figures, submitted to Physical Review Letters, Modified to
answer the referees suggestion
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