How tidal processes impact the transfer of sediment from source to sink : Mekong River collaborative studies

Author Posting. © Oceanography Society, 2017. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 30, no. 3 (2017): 22–33, doi:10.5670/oceanog.2017.311.Significant sediment transformation and trapping occur along the tidal and estuarine reaches of large rivers, complicating sediment source signals transmitted to the coastal ocean. The collaborative Mekong Tropical Delta Study explored the tidally influenced portion of the Mekong River to investigate processes that impact mud- and sand-sized sediment transport and deposition associated with varying fluvial and marine influences. Researchers participating in this 2014–2015 project found that as sand and mud progress down the tidal portion of the river, sands in suspension can settle during reduced or slack flows as river discharge becomes progressively more affected by tides in the seaward direction. Consequently, deposits on the tidal river bed are connected to sand transport in the channel. In contrast, fine mud particles remain in suspension until they reach an interface zone where waters are still fresh, but the downstream saline estuary nonetheless impacts the flows. In this interface zone, as within the estuary, fine particles tend to settle, draping the sand beds with mud and limiting the connection between the bed and suspended sand. In the Mekong system, the interface and estuarine zones migrate along the distributary channels seasonally, resulting in variable trapping dynamics and channel bed texture. Therefore, the signature of fluvial-sediment discharge is altered on its path to the coastal ocean, and the disconnected mud and sand supply functions at the river mouth should result in distinct offshore depositional signatures.This research was funded by the US Office of Naval Research (grant numbers: N00014-15-1-2011, N00014- 13-1-0127, N00014-13-1-0781, N00014-14-1-0145)

West Nile Virus Viremia in Wild Rock Pigeons

Feral rock pigeons were screened for neutralizing antibodies to West Nile virus (WNV) during late winter/spring and summer of 2002 and 2003. Additionally, virus isolation from serum was attempted from 269 birds collected during peak transmission periods. The observed viremia levels and seroprevalence indicate that this species could be involved in amplifying WNV in urban settings

Myrtle Grove Delta Building Diversion: Numerical Modeling of Hydrodynamics and Sediment Transport in Lower Mississippi Nearmyrtle Grove River Bend

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Sedimentation and survival of the Mekong Delta: A case study of decreased sediment supply and accelerating rates of relative sea level rise

The Mekong Delta, early in the twenty-first century, is at a tipping point for sustainability. The delta is threatened by the implications of (1) damming and land-use changes in the drainage basin, (2) a burgeoning delta population in a nation (Vietnam) undergoing rapid development, (3) accelerating rates of rising sea level, and (4) an uncertain future climate that may impact tropical-cyclone frequency and monsoonal precipitation patterns in the basin. These threats are present in other great rivers that emerge from the Himalayas. Two primary threats are examined in light of recent joint Vietnam-US studies in the largest distributary (Song Hau) of the Mekong River, in the shore-fringing mangroves, and on the adjacent subaqueous delta. We consider the implications of declining sediment loads from the catchment (as well as modification of the annual hydrograph) and flooding and salinity intrusion associated with relative sea level rise (eustatic + subsidence). This 2014–2015 study shows the interconnectivity in fluvial sediment supply to these parts of the delta: declining sediment loads and rising sea levels will likely impact distributary channel morphology and will alter estuarine circulation and sediment-trapping efficiency, all of which have feedbacks on sediment provision to the mangrove forests and the shelf

Arts practice and research: locating alterity and expertise.

This is the peer reviewed version of the following article: Grennan, S. (2015). Arts Practice and Research: Locating Alterity and Expertise. International Journal of Art & Design Education, 34(2), 249-259. doi: 10.1111/jade.1776 , which has been published in final form athttp://onlinelibrary.wiley.com/doi/10.1111/jade.1776/epdf. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingThere is still no agreed pedagogic definition of practice-based research. However, there is not a dearth of definitions, but rather a wide variety, predicated upon the developing programmes of individual places of study. This article will examine these definitions in terms of underlying concepts of intentionality and alterity and the ways in which instrumental use of them affects study. The article will discuss a number of existing models for the theorising and adjudication of practice as research, and the questions that underpin their development. First, are non-text outputs, and the methods of their production, able to communicate knowledge rather than simply constituting knowledge? Second, by what criteria can this knowledge be adjudicated within an academic environment? Third, what is the status of these outputs and methods relative to the production of text? It will propose that interrogation of these models will advance little in discussions that focus on media. Text or nottext is beside the point. Rather, the relationship between research and practice can be explored as a relationship between intentionality and alterity, based in an essentially social conception of communities of expertise, including academic communities of expertise. Finally, the article will describe an attempt by the author to undertake a drawing activity in response to a research question, in order to assess the possibilities of articulating practice specifically in order to demonstrate expert knowledge of the field in which a research question occurs

Contrasting watershed-scale trends in runoff and sediment yield complicate rangeland water resources planning

Rangelands cover a large portion of the earth's land surface and are undergoing dramatic landscape changes. At the same time, these ecosystems face increasing expectations to meet growing water supply needs. To address major gaps in our understanding of rangeland hydrologic function, we investigated historical watershed-scale runoff and sediment yield in a dynamic landscape in central Texas, USA. We quantified the relationship between precipitation and runoff and analyzed reservoir sediment cores dated using cesium-137 and lead-210 radioisotopes. Local rainfall and streamflow showed no directional trend over a period of 85 years, resulting in a rainfall–runoff ratio that has been resilient to watershed changes. Reservoir sedimentation rates generally were higher before 1963, but have been much lower and very stable since that time. Our findings suggest that (1) rangeland water yields may be stable over long periods despite dramatic landscape changes while (2) these same landscape changes influence sediment yields that impact downstream reservoir storage. Relying on rangelands to meet water needs demands an understanding of how these dynamic landscapes function and a quantification of the physical processes at work

A catastrophic meltwater flood event and the formation of the Hudson Shelf Valley

This paper is not subject to U.S. copyright. The definitive version was published in Palaeogeography, Palaeoclimatology, Palaeoecology 246 (2007): 120-136, doi:10.1016/j.palaeo.2006.10.030.The Hudson Shelf Valley (HSV) is the largest physiographic feature on the U.S. mid-Atlantic continental shelf. The 150-km long valley is the submerged extension of the ancestral Hudson River Valley that connects to the Hudson Canyon. Unlike other incised valleys on the mid-Atlantic shelf, it has not been infilled with sediment during the Holocene. Analyses of multibeam bathymetry, acoustic backscatter intensity, and high-resolution seismic reflection profiles reveal morphologic and stratigraphic evidence for a catastrophic meltwater flood event that formed the modern HSV. The valley and its distal deposits record a discrete flood event that carved 15-m high banks, formed a 120-km2 field of 3- to 6-m high bedforms, and deposited a subaqueous delta on the outer shelf. The HSV is inferred to have been carved initially by precipitation and meltwater runoff during the advance of the Laurentide Ice Sheet, and later by the drainage of early proglacial lakes through stable spillways. A flood resulting from the failure of the terminal moraine dam at the Narrows between Staten Island and Long Island, New York, allowed glacial lakes in the Hudson and Ontario basins to drain across the continental shelf. Water level changes in the Hudson River basin associated with the catastrophic drainage of glacial lakes Iroquois, Vermont, and Albany around 11,450 14C year BP (~ 13,350 cal BP) may have precipitated dam failure at the Narrows. This 3200 km3 discharge of freshwater entered the North Atlantic proximal to the Gulf Stream and may have affected thermohaline circulation at the onset of the Intra-Allerød Cold Period. Based on bedform characteristics and fluvial morphology in the HSV, the maximum freshwater flux during the flood event is estimated to be ~ 0.46 Sv for a duration of ~ 80 days.Support for N. Driscoll was provided by the Office of Naval Research and the National Science Foundatio

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Mapping the Fungal Battlefield: Using in situ Chemistry and Deletion Mutants to Monitor Interspecific Chemical Interactions Between Fungi

Fungi grow in competitive environments, and to cope, they have evolved strategies, such as the ability to produce a wide range of secondary metabolites. This begs two related questions. First, how do secondary metabolites influence fungal ecology and interspecific interactions? Second, can these interspecific interactions provide a way to “see” how fungi respond, chemically, within a competitive environment? To evaluate these, and to gain insight into the secondary metabolic arsenal fungi possess, we co-cultured Aspergillus fischeri, a genetically tractable fungus that produces a suite of mycotoxins, with Xylaria cubensis, a fungus that produces the fungistatic compound and FDA-approved drug, griseofulvin. To monitor and characterize fungal chemistry in situ, we used the droplet-liquid microjunction-surface sampling probe (droplet probe). The droplet probe makes a microextraction at defined locations on the surface of the co-culture, followed by analysis of the secondary metabolite profile via liquid chromatography-mass spectrometry. Using this, we mapped and compared the spatial profiles of secondary metabolites from both fungi in monoculture versus co-culture. X. cubensis predominantly biosynthesized griseofulvin and dechlorogriseofulvin in monoculture. In contrast, under co-culture conditions a deadlock was formed between the two fungi, and X. cubensis biosynthesized the same two secondary metabolites, along with dechloro-5′-hydroxygriseofulvin and 5′-hydroxygriseofulvin, all of which have fungistatic properties, as well as mycotoxins like cytochalasin D and cytochalasin C. In contrast, in co-culture, A. fischeri increased the production of the mycotoxins fumitremorgin B and verruculogen, but otherwise remained unchanged relative to its monoculture. To evaluate that secondary metabolites play an important role in defense and territory establishment, we co-cultured A. fischeri lacking the master regulator of secondary metabolism laeA with X. cubensis. We found that the reduced secondary metabolite biosynthesis of the ΔlaeA strain of A. fischeri eliminated the organism’s ability to compete in co-culture and led to its displacement by X. cubensis. These results demonstrate the potential of in situ chemical analysis and deletion mutant approaches for shedding light on the ecological roles of secondary metabolites and how they influence fungal ecological strategies; co-culturing may also stimulate the biosynthesis of secondary metabolites that are not produced in monoculture in the laboratory

Targeting DNA Damage Response and Replication Stress in Pancreatic Cancer

Background and aims: Continuing recalcitrance to therapy cements pancreatic cancer (PC) as the most lethal malignancy, which is set to become the second leading cause of cancer death in our society. The study aim was to investigate the association between DNA damage response (DDR), replication stress and novel therapeutic response in PC to develop a biomarker driven therapeutic strategy targeting DDR and replication stress in PC. Methods: We interrogated the transcriptome, genome, proteome and functional characteristics of 61 novel PC patient-derived cell lines to define novel therapeutic strategies targeting DDR and replication stress. Validation was done in patient derived xenografts and human PC organoids. Results: Patient-derived cell lines faithfully recapitulate the epithelial component of pancreatic tumors including previously described molecular subtypes. Biomarkers of DDR deficiency, including a novel signature of homologous recombination deficiency, co-segregates with response to platinum (P < 0.001) and PARP inhibitor therapy (P < 0.001) in vitro and in vivo. We generated a novel signature of replication stress with which predicts response to ATR (P < 0.018) and WEE1 inhibitor (P < 0.029) treatment in both cell lines and human PC organoids. Replication stress was enriched in the squamous subtype of PC (P < 0.001) but not associated with DDR deficiency. Conclusions: Replication stress and DDR deficiency are independent of each other, creating opportunities for therapy in DDR proficient PC, and post-platinum therapy