19 research outputs found

    Frontal subduction of the Mid-Atlantic Bight shelf water at the onshore edge of a warm-core ring

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    Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans, 123(11), (2018): 7795-7818. doi: 10.1029/2018JC013794.This work studies the subduction of the shelf water along the onshore edge of a warm‐core ring that impinges on the edge of the Mid‐Atlantic Bight continental shelf. The dynamical analysis is based on observations by satellites and from the Ocean Observatories Initiative Pioneer Array observatory as well as idealized numerical model simulations. They together show that frontogenesis‐induced submesoscale frontal subduction with order‐one Rossby and Froude numbers occurs on the onshore edge of the ring. The subduction flow results from the onshore migration of the warm‐core ring that intensifies the density front on the interface of the ring and shelf waters. The subduction is a part of the cross‐front secondary circulation trying to relax the intensifying density front. The dramatically different physical and biogeochemical properties of the ring and shelf waters provide a great opportunity to visualize the subduction phenomenon. Entrained by the ring‐edge current, the subducted shelf water is subsequently transported offshore below a surface layer of ring water and alongside of the surface‐visible shelf‐water streamer. It explains the historical observations of isolated subsurface packets of shelf water along the ring periphery in the slope sea. Model‐based estimate suggests that this type of subduction‐associated subsurface cross‐shelfbreak transport of the shelf water could be substantial relative to other major forms of shelfbreak water exchange. This study also proposes that outward spreading of the ring‐edge front by the frontal subduction may facilitate entrainment of the shelf water by the ring‐edge current and enhances the shelf‐water streamer transport at the shelf edge.W. G. Z. was supported by the National Science Foundation under grants OCE‐1657853, OCE‐1657803, and OCE 1634965. JP is grateful for the support of the Woods Hole Oceanographic Institution Summer Student Fellow Program in 2016 and 2017. W. G. Z. thanks Kenneth Brink, Glen Gawarkiewicz, Rocky Geyer, Steven Lentz, Dennis McGillicuddy, Robert Todd, and John Trowbridge for helpful discussions during the course of the study or useful comments on earlier versions of the manuscript. The satellite sea surface temperature data were obtained from the University of Delaware Ocean Exploration, Remote Sensing, Biogeography Lab (led by Matthew Oliver), through the Mid‐Atlantic Coastal Ocean Observing System (MARACOOS) data server (http://tds.maracoos.org/thredds/catalog.html). The OOI Pioneer Array mooring and glider data presented in this paper were downloaded from the National Science Foundation OOI data portal (http://ooinet.oceanobservatories.org) in July–August 2016.2019-04-1

    The changing nature of shelf-break exchange revealed by the OOI Pioneer Array

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    Author Posting. © The Oceanography Society, 2018. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 31, no. 1 (2018): 60–70, doi:10.5670/oceanog.2018.110.Although the continental shelf and slope south of New England have been the subject of recent studies that address decadal-scale warming and interannual variability of water mass properties, it is not well understood how these changes affect shelf-break exchange processes. In recent years, observations of anomalous shelf and slope conditions obtained from the Ocean Observatories Initiative Pioneer Array and other regional observing programs suggest that onshore intrusions of warm, salty waters are becoming more prevalent. Mean cross-shelf transects constructed from Pioneer Array glider observations collected from April 2014 through December 2016 indicate that slope waters have been warmer and saltier. We examine shelf-break exchange events and anomalous onshore intrusions of warm, salty water associated with warm core rings located near the shelf break in spring 2014 and winter 2017 using observations from the Pioneer Array and other sources. We also describe an additional cross-shelf intrusion of ring water in September 2014 to demonstrate that the occurrence of high-salinity waters extending across the continental shelf is rare. Observations from the Pioneer Array and other sources show warm core ring and Gulf Stream water masses intrude onto the continental shelf more frequently and penetrate further onshore than in previous decades.GG, WZ, RT, and MD were supported by the National Science Foundation under grant OCE-1657853. WZ was also supported by grant OCE-1634965. JP is grateful for the support of the Woods Hole Oceanographic Institution Summer Student Fellow Program. AMM was supported by a grant from the MacArthur Foundation. GG and AMM were also supported by a grant from the van Beuren Charitable Foundation for collection and analysis of hydrographic data collected by the CFRF Shelf Research Fleet

    Successful Long-Term Preservation of Rat Sperm by Freeze-Drying

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    Background: Freeze-drying sperm has been developed as a new preservation method where liquid nitrogen is no longer necessary. An advantage of freeze-drying sperm is that it can be stored at 4uC and transported at room temperature. Although the successful freeze-drying of sperm has been reported in a number of animals, the possibility of long-term preservation using this method has not yet been studied. Methodology/Principal Findings: Offspring were obtained from oocytes fertilized with rat epididymal sperm freeze-dried using a solution containing 10 mM Tris and 1 mM EDTA adjusted to pH 8.0. Tolerance of testicular sperm to freeze-drying was increased by pre-treatment with diamide. Offspring with normal fertility were obtained from oocytes fertilized with freeze-dried epididymal sperm stored at 4uC for 5 years. Conclusions and Significance: Sperm with –SS – cross-linking in the thiol-disulfide of their protamine were highly tolerant to freeze-drying, and the fertility of freeze-dried sperm was maintained for 5 years without deterioration. This is the first report to demonstrate the successful freeze-drying of sperm using a new and simple method for long-term preservation

    Comparative Analysis of Planktonic Productivity in Trinidad Bay and Nearshore Environments in Northern California During the 2017 Upwelling Season

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    Oscillatory NAD(P)H Waves and Calcium Oscillations in Neutrophils? A Modeling Study of Feasibility

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    The group of Howard Petty has claimed exotic metabolic wave phenomena together with mutually phase-coupled NAD(P)H- and calcium-oscillations in human neutrophils. At least parts of these phenomena are highly doubtful due to extensive failure of reproducibility by several other groups and hints that unreliable data from the Petty lab are involved in publications concerning circular calcium waves. The aim of our theoretical spatiotemporal modeling approach is to propose a possible and plausible biochemical mechanism which would, in principle, be able to explain metabolic oscillations and wave phenomena in neutrophils. Our modeling suggests the possibility of a calcium-controlled glucose influx as a driving force of metabolic oscillations and a potential role of polarized cell geometry and differential enzyme distribution for various NAD(P)H wave phenomena. The modeling results are supposed to stimulate further controversial discussions of such phenomena and potential mechanisms and experimental efforts to finally clarify the existence and biochemical basis of any kind of temporal and spatiotemporal patterns of calcium signals and metabolic dynamics in human neutrophils. Independent of Petty's observations, they present a general feasibility study of such phenomena in cells

    Fungi reduce preference and performance of insect herbivores on challenged plants

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    Although insect herbivores and fungal pathogens frequently share the same individual host plant, we lack general insights in how fungal infection affects insect preference and performance. We addressed this question in a meta-analysis of 1,113 case studies gathered from 101 primary papers that compared preference or performance of insect herbivores on control vs. fungus challenged plants. Generally, insects preferred, and performed better on, not challenged plants, regardless of experimental conditions. Insect response to fungus infection significantly differed according to fungus lifestyle, insect feeding guild and the spatial scale of the interaction (local/distant). Insect performance was reduced on plants challenged by biotrophic pathogens or endophytes but not by necrotrophic pathogens. For both chewing and piercing-sucking insects, performance was reduced on challenged plants when interactions occurred locally but not distantly. In plants challenged by biotrophic pathogens, both preference and performance of herbivores were negatively impacted, whereas infection by necrotrophic pathogens reduced herbivore preference more than performance and endophyte infection reduced only herbivore performance. Our study demonstrates that fungi are may be important but hitherto overlooked drivers of plant-herbivore interactions, suggesting both direct and plant-mediated effects of fungi on insect's behavior and development