36 research outputs found

    Using IMS hydrophone data for detecting submarine volcanic activity: Insights from Monowai, 26°S Kermadec Arc

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    Only little is known on active volcanism in the ocean. As eruptions are attenuated by seawater and fallout does not regularly reach the sea surface, eruption rates and mechanisms are poorly understood. Estimations on the number of active volcanoes across the modern seas range from hundreds to thousands, but only very few active sites are known. Monowai is a submarine volcanic centre in the northern Kermadec Arc, Southwest Pacific Ocean. During May 2011, it erupted over a period of five days, with explosive activity directly linked to the generation of seismoacoustic tertiary waves (‘T-phases’), recorded at three broadband seismic stations in the region. We show, using windowed cross-correlation and time-difference-of-arrival techniques, that T-phases associated with this eruption are detected as far as Ascension Island, South Atlantic Ocean, where two bottom-moored hydrophone arrays are operated as part of the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). We observe a high incidence of T-phase arrivals during the time of the eruption, with the angle of arrival stabilizing at the geodesic azimuth between the IMS arrays and Monowai. T-phases from the volcanic centre must therefore have propagated through the Sound Fixing And Ranging (SOFAR) channel in the South Pacific and South Atlantic Oceans and over a total geodesic range of approximately 15,800 km, one of the longest source-receiver distances of any naturally occurring underwater signal ever observed

    Seafloor Geodesy in Shallow Water With GPS on an Anchored Spar Buoy

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    Measuring seafloor motion in shallow coastal water is challenging due to strong and highly variable oceanographic effects. Such measurements are potentially useful for monitoring near‐shore coastal subsidence, subsidence due to petroleum withdrawal, strain accumulation/release processes in subduction zones and submerged volcanoes, and certain freshwater applications, such as volcano deformation in caldera‐hosted lakes. We have developed a seafloor geodesy system for this environment based on an anchored spar buoy topped by high‐precision GPS. Orientation of the buoy is measured using a digital compass that provides heading, pitch, and roll information. The combined orientation and GPS tracking data are used to recover the three‐dimensional position of the seafloor marker (anchor). A test system has been deployed in Tampa Bay, Florida, for over 1 year and has weathered several major storms without incident. Even in the presence of strong tidal currents which can deflect the top of the buoy several meters from vertical, daily repeatability in the corrected three‐component position estimates for the anchor is 1–2 cm or better.Published12116–121401IT. Reti di monitoraggio e sorveglianzaJCR Journa

    Social isolation in childhood and adult inflammation: Evidence from the National Child Development Study

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    Background: Social isolation is known to be associated with poorer health amongst adults, including coronary heart disease. It is hypothesized that this association may be mediated by inflammation. There has been little prospective research on the long-term impact of social isolation in childhood on adult health or the pathways which might be involved. The aim of this study was to investigate whether social isolation in childhood is associated with increased adult inflammation and the mechanisms involved across the life course. Methods: This study used multiply-imputed data on 7462 participants of the National Child Development Study in Great Britain. The association between child social isolation (7-11. yrs) and levels of C-reactive protein (CRP) in middle age (44. yrs) was examined. We additionally investigated the role of adult social isolation, psychological distress, health behaviors and socioeconomic factors as potential mediators using path analysis and concurrent measurements made across the life course. Results: Socially isolated children had higher levels of C-reactive protein in mid-life (standardized coefficient. =. 0.05, p≀. 0.001). In addition, children who were socially isolated tended to have lower subsequent educational attainment, be in a less advantaged social class in adulthood, were more likely to be psychologically distressed across adulthood and were more likely to be obese and to smoke. All of these factors partially explained the association between childhood social isolation and CRP. However, this association remained statistically significant after considering all mediators simultaneously. Conclusions: Social isolation in childhood is associated with higher levels of C-reactive protein in mid-life. This is explained in part through complex mechanisms acting across the life course. Identification and interventions targeted toward socially isolated children may help reduce long-term adult health risk

    Protocol of the baseline assessment for the Environments for Healthy Living (EHL) Wales cohort study

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    Background Health is a result of influences operating at multiple levels. For example, inadequate housing, poor educational attainment, and reduced access to health care are clustered together, and are all associated with reduced health. Policies which try to change individual people's behaviour have limited effect when people have little control over their environment. However, structural environmental change and an understanding of the way that influences interact with each other, has the potential to facilitate healthy choices irrespective of personal resources. The aim of Environments for Healthy Living (EHL) is to investigate the impact of gestational and postnatal environments on health, and to examine where structural change can be brought about to optimise health outcomes. The baseline assessment will focus on birth outcomes and maternal and infant health. Methods/Design EHL is a longitudinal birth cohort study. We aim to recruit 1000 pregnant women in the period April 2010 to March 2013. We will examine the impact of the gestational environment (maternal health) and the postnatal environment (housing and neighbourhood conditions) on subsequent health outcomes for the infants born to these women. Data collection will commence during the participants' pregnancy, from approximately 20 weeks gestation. Participants will complete a questionnaire, undergo anthropometric measurements, wear an accelerometer, compile a food diary, and have environmental measures taken within their home. They will also be asked to consent to having a sample of umbilical cord blood taken following delivery of their baby. These data will be complemented by routinely collected electronic data such as health records from GP surgeries, hospital admissions, and child health and development records. Thereafter, participants will be visited annually for follow-up of subsequent exposures and child health outcomes. Discussion The baseline assessment of EHL will provide information concerning the impact of gestational and postnatal environments on birth outcomes and maternal and infant health. The findings can be used to inform the development of complex interventions targeted at structural, environmental factors, intended to reduce ill-health. Long-term follow-up of the cohort will focus on relationships between environmental exposures and the later development of adverse health outcomes, including obesity and diabetes

    Calling: Earth #041- Mel Rodgers, Volcanologist

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    In this episode of Calling: Earth, we talk with Mel Rodgers, Research Assistant Professor in the USF School of Geosciences, about her research of volcanic hazards using geophysics as well as science communication and diversity in the geosciences. More about Mel can be found here: Selected Works Google Scholar USF SGS Faculty Webpag

    Measuring Complex Beach-Dune Morphology and Nearshore Processes Using UAVs

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    We examined various applications of widely available and low-cost Unoccupied Aerial Vehicles (UAVs) in measuring beach morphodynamics and hydrodynamics. With adequate ground control points, UAVs demonstrate promising potential for capturing highly 3-dimensional beach/dune morphology with cm-scale accuracy and mm-scale resolution. Model accuracy and resolution are also controlled by flight altitude, with lower altitude yielding higher accuracy and resolution but at the expense of less spatial coverage. The time-series of UAV images and DEMs provide a valuable tool to document morphology changes of irregularly shaped coastal features, vegetation coverage and spatial distribution of sediment sizes. The efficiency of UAV data collection allows regional scale pre- and post-storm surveys to quantify storm-induced beach/dune changes. The overhead videos from the reasonably stable platform allow measurements of dynamic surf-zone parameters including incident breaking and non-breaking wave angles, limits of uprush and downrush, swash velocities and longshore current velocity. UAVs prove to be a promising addition to the traditional methods for measuring beach morphodynamics and hydrodynamics
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