Assessment of Sequential Extractions: Implications for Isotopic Composition of Authigenic Oxides and Detrital Residues as Paleoceanographic Proxies

Constraints on characteristics of past oceans-- ocean circulation, sedimentation processes, and sources of dissolved trace metals-- are vital because they contribute to our understanding of heat transport, atmospheric conditions, and productivity. Proxies that record information about these processes in marine sediment are key to understanding the ocean’s role in past climate. This dissertation looks in depth at how the Neodymium (Nd) and Lead (Pb) isotopic composition (IC) of fish debris, sequentially extracted oxide coatings, and “detrital” residues are used as proxies for ocean circulation and sediment composition. We first present a reconstruction of ocean circulation in the Cenozoic Pacific Ocean employing Neodymium IC of fossil fish Debris and oxide coatings based on Deep Sea Drilling Program (DSDP), Ocean Drilling Program (ODP), and Integrated Ocean Drilling Program (IODP) sites spanning the North and South Pacific. The South Pacific becomes slowly less radiogenic, after 35Ma as the gradient between the North and South Pacific increases. This, combined with the North Pacific becoming more radiogenic (seemingly because of nonconservative mixing of Nd) indicates that there is a fundamental transition in the North Pacific from surface ventilated deep-water formation to circulation dominated by sluggish diffusive mixing. There are two main results from The South Pacific becomes slowly less radiogenic, after 35Ma the gradient between the North and South Pacific increases. This indicates a fundamental transition in the North Pacific from surface ventilated deep-water formation to circulation dominated by sluggish diffusive mixing. Then I preform an assessment of the fidelity and reproducibility of the leaching procedure we use to isolate the Fe-Mn oxyhydroxide coatings.. Our procedure entails a two-step leach with a Hydroxylamine-Hydrochloride mixture: Leach 1 targets the Fe-Mn oxide coatings and is 1 hour, and Leach 2, is 24 hours designed to remove remaining Fe-Mn oxides from the detrital residue. In order to analyze leach reproducibility we performed replicate analysis of a USGS certified reference material (MAG-1) and an in house internal standard from the central Atlantic (INTL-STD-A). We also performed an assessment of the geochemistry of two sites (IODP Sites 1149 and U1370) from the Pacific. Finally we evaluate which geochemical phases are mobilized by each step of our sequential leaching procedure at Site 1149 and U1370. We utilize a novel multivariate statistical assessment of major, trace and rare earth elements to identify their sources and the sources relationship with the Nd and Pb isotopic composition

Game of Stones:feasibility randomised controlled trial of how to engage men with obesity in text message and incentive interventions for weight loss

Objectives To examine the acceptability and feasibility of narrative text messages with or without financial incentives to support weight loss for men. Design Individually randomised three-arm feasibility trial with 12 months’ follow-up. Setting Two sites in Scotland with high levels of disadvantage according to Scottish Index for Multiple Deprivation (SIMD). Participants Men with obesity (n=105) recruited through community outreach and general practitioner registers. Interventions Participants randomised to: (A) narrative text messages plus financial incentive for 12 months (short message service (SMS)+I), (B) narrative text messages for 12 months (SMS only), or (C) waiting list control. Outcomes Acceptability and feasibility of recruitment, retention, intervention components and trial procedures assessed by analysing quantitative and qualitative data at 3, 6 and 12 months. Results 105 men were recruited, 60% from more disadvantaged areas (SIMD quintiles 1 or 2). Retention at 12 months was 74%. Fewer SMS+I participants (64%) completed 12-month assessments compared with SMS only (79%) and control (83%). Narrative texts were acceptable to many men, but some reported negative reactions. No evidence emerged that level of disadvantage was related to acceptability of narrative texts. Eleven SMS+I participants (31%) successfully met or partially met weight loss targets. The cost of the incentive per participant was £81.94 (95% CI £34.59 to £129.30). Incentives were acceptable, but improving health was reported as the key motivator for weight loss. All groups lost weight (SMS+I: −2.51 kg (SD=4.94); SMS only: −1.29 kg (SD=5.03); control: −0.86 kg (SD=5.64) at 12 months). Conclusions This three-arm weight management feasibility trial recruited and retained men from across the socioeconomic spectrum, with the majority from areas of disadvantage, was broadly acceptable to most participants and feasible to deliver

Geochemical approaches to the quantification of dispersed volcanic ash in marine sediment

Volcanic ash has long been recognized in marine sediment, and given the prevalence of oceanic and continental arc volcanism around the globe in regard to widespread transport of ash, its presence is nearly ubiquitous. However, the presence/absence of very fine-grained ash material, and identification of its composition in particular, is challenging given its broad classification as an “aluminosilicate” component in sediment. Given this challenge, many studies of ash have focused on discrete layers (that is, layers of ash that are of millimeter-to-centimeter or greater thickness, and their respective glass shards) found in sequences at a variety of locations and timescales and how to link their presence with a number of Earth processes. The ash that has been mixed into the bulk sediment, known as dispersed ash, has been relatively unstudied, yet represents a large fraction of the total ash in a given sequence. The application of a combined geochemical and statistical technique has allowed identification of this dispersed ash as part of the original ash contribution to the sediment. In this paper, we summarize the development of these geochemical/statistical techniques and provide case studies from the quantification of dispersed ash in the Caribbean Sea, equatorial Pacific Ocean, and northwest Pacific Ocean. These geochemical studies (and their sedimentological precursors of smear slides) collectively demonstrate that local and regional arc-related ash can be an important component of sedimentary sequences throughout large regions of the ocean

Searching for Inflow Towards Massive Starless Clump Candidates Identified in the Bolocam Galactic Plane Survey

Recent Galactic plane surveys of dust continuum emission at long wavelengths have identified a population of dense, massive clumps with no evidence for on-going star formation. These massive starless clump candidates are excellent sites to search for the initial phases of massive star formation before the feedback from massive star formation effects the clump. In this study, we search for the spectroscopic signature of inflowing gas toward starless clumps, some of which are massive enough to form a massive star. We observed 101 starless clump candidates identified in the Bolocam Galactic Plane Survey (BGPS) in HCO+ J = 1-0 using the 12m Arizona Radio Observatory telescope. We find a small blue excess of E = (Nblue - Nred)/Ntotal = 0.03 for the complete survey. We identified 6 clumps that are good candidates for inflow motion and used a radiative transfer model to calculate mass inflow rates that range from 500 - 2000 M /Myr. If the observed line profiles are indeed due to large-scale inflow motions, then these clumps will typically double their mass on a free fall time. Our survey finds that massive BGPS starless clump candidates with inflow signatures in HCO+ J = 1-0 are rare throughout our Galaxy.Comment: 14 pages, 9 figure

Text Messages With Financial Incentives for Men With Obesity : A Randomized Clinical Trial

Peer reviewe

Text messaging and financial incentives to encourage weight loss in men with obesity: the Game of Stones feasibility RCT

Funding: This project was funded by the National Institute for Health Research (NIHR) Public Health Research programme and will be published in full in Public Health Research; Vol. 8, No. 11. See the NIHR Journals Library website for further project information.Peer reviewedPublisher PD

Regional-scale input of dispersed and discrete volcanic ash to the Izu-Bonin and Mariana subduction zones

We have geochemically and statistically characterized bulk marine sediment and ash layers at Ocean Drilling Program Site 1149 (Izu-Bonin Arc) and Deep Sea Drilling Project Site 52 (Mariana Arc), and have quantified that multiple dispersed ash sources collectively comprise ~30-35% of the hemipelagic sediment mass entering the Izu-Bonin-Mariana subduction system. Multivariate statistical analyses indicate that the bulk sediment at Site 1149 is a mixture of Chinese Loess, a second compositionally distinct eolian source, a dispersed mafic ash, and a dispersed felsic ash. We interpret the source of these ashes as respectively being basalt from the Izu-Bonin Front Arc (IBFA) and rhyolite from the Honshu Arc. Sr-, Nd-, and Pb isotopic analyses of the bulk sediment are consistent with the chemical/statistical-based interpretations. Comparison of the mass accumulation rate of the dispersed ash component to discrete ash layer parameters (thickness, sedimentation rate, and number of layers) suggests that eruption frequency, rather than eruption size, drives the dispersed ash record. At Site 52, the geochemistry and statistical modeling indicates that Chinese Loess, IBFA, dispersed BNN (boninite from Izu-Bonin), and a dispersed felsic ash of unknown origin are the sources. At Site 1149 the ash layers and the dispersed ash are compositionally coupled, whereas at Site 52 they are decoupled in that there are no boninite layers, yet boninite is dispersed within the sediment. Changes in the volcanic and eolian inputs through time indicate strong arc- and climate-related controls