100 research outputs found

    Deforestation of watersheds of Panama : nutrient retention and export to streams

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    © The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeochemistry 115 (2013): 299-315, doi:10.1007/s10533-013-9836-2.A series of eight watersheds on the Pacific coast of Panama where conversion of mature lowland wet forest to pastures by artisanal burning provided watershed-scale experimental units with a wide range of forest cover (23, 29, 47, 56, 66, 73, 73, 91, and 92%). We used these watersheds as a landscape-scale experiment to assess effects of degree of deforestation on within-watershed retention and hydrological export of atmospheric inputs of nutrients. Retention was estimated by comparing rainfall nutrient concentrations (volume-weighted to allow for evapotranspiration) to concentrations in freshwater reaches of receiving streams. Retention of rain-derived nutrients in these Panama watersheds averaged 77, 85, 80, and 62% for nitrate, ammonium, dissolved organic N, and phosphate, respectively. Retention of rain-derived inorganic nitrogen, however, depended on watershed cover: retention of nitrate and ammonium in pasture-dominated watersheds was 95 and 98%, while fully forested watersheds retained 65 and 80% of atmospheric nitrate and ammonium inputs. Watershed forest cover did not affect retention of dissolved organic nitrogen and phosphate. Exports from more forested watersheds yielded DIN/P near 16, while pasture-dominated watersheds exported N/P near 2. The differences in magnitude of exports and ratios suggest that deforestation in these Panamanian forests results in exports that affect growth of plants and algae in the receiving stream and estuarine ecosystems. Watershed retention of dissolved inorganic nitrogen calculated from wet plus dry atmospheric deposition varied from 90% in pasture- to 65% in forest-dominated watersheds, respectively. Discharges of DIN to receiving waters from the watersheds therefore rose from 10% of atmospheric inputs for pasture-dominated watersheds, to about 35% of atmospheric inputs for fully forested watersheds. These results from watersheds with no agriculture or urbanization, but different conversion of forest to pasture by burning, show significant, deforestation-dependent retention within tropical watersheds, but also ecologically significant, and deforestation-dependent, exports that are biologically significant because of the paucity of nutrients in receiving tropical stream and coastal waters.This work was funded by NSF Grant BIO- 084241

    Temperature and residence time controls on an estuarine harmful algal bloom : modeling hydrodynamics and Alexandrium fundyense in Nauset estuary

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    Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Estuaries and Coasts 38 (2015): 2240-2258, doi:10.1007/s12237-015-9949-z.A highly resolved, 3-d model of hydrodynamics and Alexandrium fundyense in an estuarine embayment has been developed to investigate the physical and biological controls on a recurrent harmful algal bloom. Nauset estuary on Cape Cod (MA, USA) consists of three salt ponds connected to the ocean through a shallow marsh and network of tidal channels. The model is evaluated using quantitative skill metrics against observations of physical and biological conditions during three spring blooms. The A. fundyense model is based on prior model applications for the nearby Gulf of Maine, but notable modifications were made to be consistent with the Nauset observations. The dominant factors controlling the A. fundyense bloom in Nauset were the water temperature, which regulates organism growth rates, and the efficient retention of cells due to bathymetric constraints, stratification, and cell behavior (diel vertical migration). Spring-neap variability in exchange altered residence times, but for cell retention to be substantially longer than the cell doubling time required both active vertical migration and stratification that inhibits mixing of cells into the surface layer by wind and tidal currents. Unlike in the Gulf of Maine, the model results were relatively insensitive to cyst distributions or germination rates. Instead, in Nauset, high apparent rates of vegetative cell division by retained populations dictated bloom development. Cyst germination occurred earlier in the year than in the Gulf of Maine, suggesting that Nauset cysts have different controls on germination timing. The model results were relatively insensitive to nutrient concentrations, due to eutrophic conditions in the highly impacted estuary or due to limitations in the spatial and temporal resolution of nutrient sampling. Cell loss rates were inferred to be extremely low during the growth phase of the bloom, but increased rapidly during the final phase due to processes that remain uncertain. The validated model allows a quantitative assessment of the factors that contribute to the development of a recurrent harmful algal bloom and provides a framework for assessing similarly impacted coastal systems.This work was supported by the National Science Foundation (OCE-0430724, OCE-0911031, and OCE-1314642) and National Institutes of Health (NIEHS-1P50-ES021923-01) through the Woods Hole Center for Oceans and Human Health, and by National Park Service (NPS) Cooperative Agreement H238015504.2016-03-1

    Eutrophication and macroalgal blooms in temperate and tropical coastal waters: Nutrient enrichment experiments with Ulva spp.

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    Receiving coastal waters and estuaries are among the most nutrient-enriched environments on earth, and one of the symptoms of the resulting eutrophication is the proliferation of opportunistic, fast-growing marine seaweeds. Here, we used a widespread macroalga often involved in blooms, Ulva spp., to investigate how supply of nitrogen (N) and phosphorus (P), the two main potential growth-limiting nutrients, influence macroalgal growth in temperate and tropical coastal waters ranging from low- to high-nutrient supplies. We carried out N and P enrichment field experiments on Ulva spp. in seven coastal systems, with one of these systems represented by three different subestuaries, for a total of nine sites. We showed that rate of growth of Ulva spp. was directly correlated to annual dissolved inorganic nitrogen (DIN) concentrations, where growth increased with increasing DIN concentration. Internal N pools of macroalgal fronds were also linked to increased DIN supply, and algal growth rates were tightly coupled to these internal N pools. The increases in DIN appeared to be related to greater inputs of wastewater to these coastal waters as indicated by high δ15N signatures of the algae as DIN increased. N and P enrichment experiments showed that rate of macroalgal growth was controlled by supply of DIN where ambient DIN concentrations were low, and by P where DIN concentrations were higher, regardless of latitude or geographic setting. These results suggest that understanding the basis for macroalgal blooms, and management of these harmful phenomena, will require information as to nutrient sources, and actions to reduce supply of N and P in coastal waters concerned.Fil: Teichberg, Mirta. Leibniz Center For Tropical Marine Research; AlemaniaFil: Fox, Sophia E.. Marine Biological Laboratory; Estados UnidosFil: Olsen, Ylva S.. Bangor University; Reino UnidoFil: Valiela, Ivan. Marine Biological Laboratory; Estados UnidosFil: Martinetto, Paulina Maria del Rosario. Universidad Nacional de Mar del Plata; ArgentinaFil: Iribarne, Oscar Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Muto, Elizabeti Yuriko. Universidade de Sao Paulo; BrasilFil: Petti, Monica A.V.. Universidade de Sao Paulo; BrasilFil: Corbisier, Thaïs N.. Universidade de Sao Paulo; BrasilFil: Soto-Jiménez, Martín. Universidad Nacional Autónoma de México; MéxicoFil: Páez-Osuna, Federico. Universidad Nacional Autónoma de México; MéxicoFil: Castro, Paula. University Of Coimbra; BrasilFil: Freitas, Helena. University Of Coimbra; BrasilFil: Zitelli, Andreina. Università Iuav Di Venezia; ItaliaFil: Cardinaletti, Massimo. Gruppo Veritas; ItaliaFil: Tagliapietra, Davide. Consiglio Nazionale delle Ricerche; Itali

    Rapid growth and concerted sexual transitions by a bloom of the harmful dinoflagellate Alexandrium fundyense (Dinophyceae)

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    © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Limnology and Oceanography 60 (2015): 2059–2078, doi:10.1002/lno.10155.Transitions between life cycle stages by the harmful dinoflagellate Alexandrium fundyense are critical for the initiation and termination of its blooms. To quantify these transitions in a single population, an Imaging FlowCytobot (IFCB), was deployed in Salt Pond (Eastham, Massachusetts), a small, tidally flushed kettle pond that hosts near annual, localized A. fundyense blooms. Machine-based image classifiers differentiating A. fundyense life cycle stages were developed and results were compared to manually corrected IFCB samples, manual microscopy-based estimates of A. fundyense abundance, previously published data describing prevalence of the parasite Amoebophrya, and a continuous culture of A. fundyense infected with Amoebophrya. In Salt Pond, a development phase of sustained vegetative division lasted approximately 3 weeks and was followed by a rapid and near complete conversion to small, gamete cells. The gametic period (∼3 d) coincided with a spike in the frequency of fusing gametes (up to 5% of A. fundyense images) and was followed by a zygotic phase (∼4 d) during which cell sizes returned to their normal range but cell division and diel vertical migration ceased. Cell division during bloom development was strongly phased, enabling estimation of daily rates of division, which were more than twice those predicted from batch cultures grown at similar temperatures in replete medium. Data from the Salt Pond deployment provide the first continuous record of an A. fundyense population through its complete bloom cycle and demonstrate growth and sexual induction rates much higher than are typically observed in culture.National Science Foundation Grant Number: OCE-0430724, OCE-0911031, and OCE-1314642; National Institutes of Health Grant Number: NIEHS-1P50-ES021923-01; National Park Service (NPS) Cooperative Agreement Grant Number: H238015504; Gordon and Betty Moore Foundation Grant Number: #2649 to HMS; IOF Grant Number: MOHAB PIOF-GA-25226

    Building a Quantum Engineering Undergraduate Program

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    Contribution: A roadmap is provided for building a quantum engineering education program to satisfy U.S. national and international workforce needs. Background: The rapidly growing quantum information science and engineering (QISE) industry will require both quantum-aware and quantum-proficient engineers at the bachelor\u27s level. Research Question: What is the best way to provide a flexible framework that can be tailored for the full academic ecosystem? Methodology: A workshop of 480 QISE researchers from across academia, government, industry, and national laboratories was convened to draw on best practices; representative authors developed this roadmap. Findings: 1) For quantum-aware engineers, design of a first quantum engineering course, accessible to all STEM students, is described; 2) for the education and training of quantum-proficient engineers, both a quantum engineering minor accessible to all STEM majors, and a quantum track directly integrated into individual engineering majors are detailed, requiring only three to four newly developed courses complementing existing STEM classes; 3) a conceptual QISE course for implementation at any postsecondary institution, including community colleges and military schools, is delineated; 4) QISE presents extraordinary opportunities to work toward rectifying issues of inclusivity and equity that continue to be pervasive within engineering. A plan to do so is presented, as well as how quantum engineering education offers an excellent set of education research opportunities; and 5) a hands-on training plan on quantum hardware is outlined, a key component of any quantum engineering program, with a variety of technologies, including optics, atoms and ions, cryogenic and solid-state technologies, nanofabrication, and control and readout electronics

    Building a Quantum Engineering Undergraduate Program

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    The rapidly growing quantum information science and engineering (QISE) industry will require both quantum-aware and quantum-proficient engineers at the bachelor's level. We provide a roadmap for building a quantum engineering education program to satisfy this need. For quantum-aware engineers, we describe how to design a first quantum engineering course accessible to all STEM students. For the education and training of quantum-proficient engineers, we detail both a quantum engineering minor accessible to all STEM majors, and a quantum track directly integrated into individual engineering majors. We propose that such programs typically require only three or four newly developed courses that complement existing engineering and science classes available on most larger campuses. We describe a conceptual quantum information science course for implementation at any post-secondary institution, including community colleges and military schools. QISE presents extraordinary opportunities to work towards rectifying issues of inclusivity and equity that continue to be pervasive within engineering. We present a plan to do so and describe how quantum engineering education presents an excellent set of education research opportunities. Finally, we outline a hands-on training plan on quantum hardware, a key component of any quantum engineering program, with a variety of technologies including optics, atoms and ions, cryogenic and solid-state technologies, nanofabrication, and control and readout electronics. Our recommendations provide a flexible framework that can be tailored for academic institutions ranging from teaching and undergraduate-focused two- and four-year colleges to research-intensive universities.Comment: 25 pages, 2 figure

    Macrophyte abundance in Waquoit Bay : effects of land-derived nitrogen loads on seasonal and multi-year biomass patterns

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    Author Posting. © The Author(s), 2008. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Estuaries and Coasts 31 (2008): 532-541, doi:10.1007/s12237-008-9039-6.Anthropogenic inputs of nutrients to coastal waters have rapidly restructured coastal ecosystems. To examine the response of macrophyte communities to land-derived nitrogen loading, we measured macrophyte biomass monthly for six years in three estuaries subject to different nitrogen loads owing to different land uses on the watersheds. The set of estuaries sampled had nitrogen loads over the broad range of 12 to 601 kg N ha-1 y-1. Macrophyte biomass increased as nitrogen loads increased, but the response of individual taxa varied. Specifically, biomass of Cladophora vagabunda and Gracilaria tikvahiae increased significantly as nitrogen loads increased. The biomass of other macroalgal taxa tended to decrease with increasing load, and the relative proportion of these taxa to total macrophyte biomass also decreased. The seagrass, Zostera marina, disappeared from the higher loaded estuaries, but remained abundant in the estuary with the lowest load. Seasonal changes in macroalgal standing stock were also affected by nitrogen load, with larger fluctuations in biomass across the year and higher minimum biomass of macroalgae in the higher loaded estuaries. There were no significant changes in macrophyte biomass over the six years of this study, but there was a slight trend of increasing macroalgal biomass in the latter years. Macroalgal biomass was not related to irradiance or temperature, but Z. marina biomass was highest during the summer months when light and temperatures peak. Irradiance might, however, be a secondary limiting factor controlling macroalgal biomass in the higher loaded estuaries by restricting the depth of the macroalgal canopy. The relationship between the bloom-forming macroalgal species, C. vagabunda and G. tikvahiae, and nitrogen loads suggested a strong connection between development on watersheds and macroalgal blooms and loss of seagrasses. The influence of watershed land uses largely overwhelmed seasonal and inter-annual differences in standing stock of macrophytes in these temperate estuaries.This research was supported by the National Oceanic and Atmospheric Administration (NOAA), Cooperative Institute for Coastal and Estuarine Environmental Technologies (CICEET-UNH#99-304, NOAA NA87OR512), NOAA National Estuarine Research Reserve Graduate Research Fellowship NERRS GRF, #NA77OR0228), and an Environmental Protection Agency (EPA) STAR Fellowship for Graduate Environmental Study (U-915335-01-0) awarded to J. Hauxwell. S. Fox was supported by a NOAA NERRS GRF (#NA03NOS4200132) and an EPA STAR Graduate Research Fellowship. We also thank the Quebec-Labrador Foundation Atlantic Center for the Environment's Sounds Conservancy Program and the Boston University Ablon/Bay Committee for their awarding research funds

    Donepezil Impairs Memory in Healthy Older Subjects: Behavioural, EEG and Simultaneous EEG/fMRI Biomarkers

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    Rising life expectancies coupled with an increasing awareness of age-related cognitive decline have led to the unwarranted use of psychopharmaceuticals, including acetylcholinesterase inhibitors (AChEIs), by significant numbers of healthy older individuals. This trend has developed despite very limited data regarding the effectiveness of such drugs on non-clinical groups and recent work indicates that AChEIs can have negative cognitive effects in healthy populations. For the first time, we use a combination of EEG and simultaneous EEG/fMRI to examine the effects of a commonly prescribed AChEI (donepezil) on cognition in healthy older participants. The short- and long-term impact of donepezil was assessed using two double-blind, placebo-controlled trials. In both cases, we utilised cognitive (paired associates learning (CPAL)) and electrophysiological measures (resting EEG power) that have demonstrated high-sensitivity to age-related cognitive decline. Experiment 1 tested the effects of 5 mg/per day dosage on cognitive and EEG markers at 6-hour, 2-week and 4-week follow-ups. In experiment 2, the same markers were further scrutinised using simultaneous EEG/fMRI after a single 5 mg dose. Experiment 1 found significant negative effects of donepezil on CPAL and resting Alpha and Beta band power. Experiment 2 replicated these results and found additional drug-related increases in the Delta band. EEG/fMRI analyses revealed that these oscillatory differences were associated with activity differences in the left hippocampus (Delta), right frontal-parietal network (Alpha), and default-mode network (Beta). We demonstrate the utility of simple cognitive and EEG measures in evaluating drug responses after acute and chronic donepezil administration. The presentation of previously established markers of age-related cognitive decline indicates that AChEIs can impair cognitive function in healthy older individuals. To our knowledge this is the first study to identify the precise neuroanatomical origins of EEG drug markers using simultaneous EEG/fMRI. The results of this study may be useful for evaluating novel drugs for cognitive enhancement

    ENIGMA-anxiety working group : Rationale for and organization of large-scale neuroimaging studies of anxiety disorders

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    Altres ajuts: Anxiety Disorders Research Network European College of Neuropsychopharmacology; Claude Leon Postdoctoral Fellowship; Deutsche Forschungsgemeinschaft (DFG, German Research Foundation, 44541416-TRR58); EU7th Frame Work Marie Curie Actions International Staff Exchange Scheme grant 'European and South African Research Network in Anxiety Disorders' (EUSARNAD); Geestkracht programme of the Netherlands Organization for Health Research and Development (ZonMw, 10-000-1002); Intramural Research Training Award (IRTA) program within the National Institute of Mental Health under the Intramural Research Program (NIMH-IRP, MH002781); National Institute of Mental Health under the Intramural Research Program (NIMH-IRP, ZIA-MH-002782); SA Medical Research Council; U.S. National Institutes of Health grants (P01 AG026572, P01 AG055367, P41 EB015922, R01 AG060610, R56 AG058854, RF1 AG051710, U54 EB020403).Anxiety disorders are highly prevalent and disabling but seem particularly tractable to investigation with translational neuroscience methodologies. Neuroimaging has informed our understanding of the neurobiology of anxiety disorders, but research has been limited by small sample sizes and low statistical power, as well as heterogenous imaging methodology. The ENIGMA-Anxiety Working Group has brought together researchers from around the world, in a harmonized and coordinated effort to address these challenges and generate more robust and reproducible findings. This paper elaborates on the concepts and methods informing the work of the working group to date, and describes the initial approach of the four subgroups studying generalized anxiety disorder, panic disorder, social anxiety disorder, and specific phobia. At present, the ENIGMA-Anxiety database contains information about more than 100 unique samples, from 16 countries and 59 institutes. Future directions include examining additional imaging modalities, integrating imaging and genetic data, and collaborating with other ENIGMA working groups. The ENIGMA consortium creates synergy at the intersection of global mental health and clinical neuroscience, and the ENIGMA-Anxiety Working Group extends the promise of this approach to neuroimaging research on anxiety disorders

    New genetic loci link adipose and insulin biology to body fat distribution.

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    Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms
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