231 research outputs found

    The Effects Of N, P And Crude Oil On The Decomposition Of Spartina Alterniflora Belowground Biomass

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    We conducted a laboratory experiment to examine how the decomposition of particulate belowground organic matter from a salt marsh is enhanced, or not, by different mixtures of crude oil, nitrogen (N), or phosphorus (P) acting individually or synergistically. The experiment was conducted in 3.8 L sampling chambers producing varying quantities of gas whose volume was used as a surrogate measure of organic decomposition under anaerobic conditions. Gas production after 28 days, from highest to lowest, was +NP = +N \u3e\u3e\u3e +P, or +oil. The gas production under either +P or +oil conditions was indistinguishable from gas production in the control chamber. Nitrogen, not phosphorus, or +NP, was the dominant factor controlling organic decomposition rates in these experiments. The implication for organic salt marsh soils is that shoreline erosion is enhanced by salt marsh oiling, presumably by its toxicity, but not by its effect on the decomposition rates of plant biomass belowground. Nutrient additions, on the other hand, may compromise the soil strength, creating a stronger disparity in soil strength between upper and lower soil layers leading to marsh loss. Nutrient amendments intended to decrease oil concentration in the marsh may not have the desired effect, and are likely to decrease soil strength, thereby enhancing marsh-to-water conversions in organic salt marsh soils

    Influence of Coriolis Force Upon Bottom Boundary Layers in a Large‐Scale Gravity Current Experiment: Implications for Evolution of Sinuous Deep‐Water Channel Systems

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    Oceanic density currents in many deep‐water channels are strongly influenced by the Coriolis force. The dynamics of the bottom boundary layer in large geostrophic flows and low Rossby number turbidity currents are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large‐scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements or in previous small‐scale rotating laboratory experiments. We present results from a large, 13‐m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near‐bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as RoR = /Rf, where is the depth and time‐averaged velocity, R is the radius of channel curvature, and f is the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left‐ and right‐turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes

    Subject specific demands of teaching: Implications for out-of-field teachers

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    This chapter provides a framework for thinking about the subject-specific nature of teaching in terms of the knowledge, modes of inquiry and discursive practices that delineate one subject from another in the traditional school curriculum. The chapter will explore how these disciplinary traits are translated into teaching as curriculum, knowledge and pedagogy, and how this subject-specificity of teaching is juxtaposed against the more generic aspects of teaching. The chapter explores the idea that if a teacher’s expertise can be situated within a field, then they can also be positioned out-of-field. Implications for teaching out-of-field are discussed in terms of the subject-specific knowledge, processes and skills, and the difficulties associated with teacher practice. English and Australian illustrations of teacher practices from in-field and out-of-field situations are provided, in particular highlighting the demands of moving across subject boundaries. Cross-fertilisation is especially evident when subjects are integrated, therefore, the issues associated with integrated curriculum are discussed where the traditional subject boundaries are being challenged as schools are reorganised to integrate subjects through, for example, STEM teaching, or holistic curriculum designs

    Exchange rate volatility and capital inflows: role of financial development

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    There is vast literature examining the impact of exchange rate volatility on various macroeconomic aggregates such as economic growth, trade flows, domestic investment, and more recently capital flows. However, these studies have ignored the role of financial development while examining the impact of exchange rate volatility on capital flows. This study aims to analyze the impact of exchange rate volatility on capital inflows towards developing countries by incorporating the role of financial development over the time period 1980–2013. In this regard, the behavior of two types of capital flows is examined: physical capital inflows measured as foreign direct investment, and financial inflows quantified through remittance inflows. The empirical investigation comprises the direct as well as indirect effect of exchange rate volatility on capital inflows. The study employs dynamic system GMM estimation technique to empirically estimate the effect of exchange rate volatility on capital inflows. The empirical results of the study identify that exchange rate volatility dampens both physical and financial inflows towards developing countries. The indirect impact of exchange rate volatility through financial development, however, turns out positive and statistically significant. This finding reflects that financial development helps in reduc- ing the harmful impact of exchange rate volatility on capital inflows. Hence, the study concludes that a developed financial system is an important channel through which developing countries may improve capital inflows in the long run.info:eu-repo/semantics/publishedVersio

    Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015

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    SummaryBackground The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context. Methods We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defined criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors—the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specific DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI). Findings Between 1990 and 2015, global exposure to unsafe sanitation, household air pollution, childhood underweight, childhood stunting, and smoking each decreased by more than 25%. Global exposure for several occupational risks, high body-mass index (BMI), and drug use increased by more than 25% over the same period. All risks jointly evaluated in 2015 accounted for 57·8% (95% CI 56·6–58·8) of global deaths and 41·2% (39·8–42·8) of DALYs. In 2015, the ten largest contributors to global DALYs among Level 3 risks were high systolic blood pressure (211·8 million [192·7 million to 231·1 million] global DALYs), smoking (148·6 million [134·2 million to 163·1 million]), high fasting plasma glucose (143·1 million [125·1 million to 163·5 million]), high BMI (120·1 million [83·8 million to 158·4 million]), childhood undernutrition (113·3 million [103·9 million to 123·4 million]), ambient particulate matter (103·1 million [90·8 million to 115·1 million]), high total cholesterol (88·7 million [74·6 million to 105·7 million]), household air pollution (85·6 million [66·7 million to 106·1 million]), alcohol use (85·0 million [77·2 million to 93·0 million]), and diets high in sodium (83·0 million [49·3 million to 127·5 million]). From 1990 to 2015, attributable DALYs declined for micronutrient deficiencies, childhood undernutrition, unsafe sanitation and water, and household air pollution; reductions in risk-deleted DALY rates rather than reductions in exposure drove these declines. Rising exposure contributed to notable increases in attributable DALYs from high BMI, high fasting plasma glucose, occupational carcinogens, and drug use. Environmental risks and childhood undernutrition declined steadily with SDI; low physical activity, high BMI, and high fasting plasma glucose increased with SDI. In 119 countries, metabolic risks, such as high BMI and fasting plasma glucose, contributed the most attributable DALYs in 2015. Regionally, smoking still ranked among the leading five risk factors for attributable DALYs in 109 countries; childhood underweight and unsafe sex remained primary drivers of early death and disability in much of sub-Saharan Africa. Interpretation Declines in some key environmental risks have contributed to declines in critical infectious diseases. Some risks appear to be invariant to SDI. Increasing risks, including high BMI, high fasting plasma glucose, drug use, and some occupational exposures, contribute to rising burden from some conditions, but also provide opportunities for intervention. Some highly preventable risks, such as smoking, remain major causes of attributable DALYs, even as exposure is declining. Public policy makers need to pay attention to the risks that are increasingly major contributors to global burden. Funding Bill & Melinda Gates Foundation

    Safety and Efficacy of the Addition of Lapatinib to Perioperative Chemotherapy for Resectable HER2-Positive Gastroesophageal Adenocarcinoma: A Randomized Phase 2 Clinical Trial

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    Importance: Perioperative chemotherapy and surgery are a standard of care for operable gastroesophageal adenocarcinoma. Anti-HER2 therapy improves survival in patients with advanced HER2-positive disease. The safety and feasibility of adding lapatinib to perioperative chemotherapy should be assessed. Objectives: To assess the safety of adding lapatinib to epirubicin, cisplatin, and capecitabine (ECX) chemotherapy and to establish a recommended dose regimen for a phase 3 trial. Design, Setting, and Participants: Phase 2 randomized, open-label trial comparing standard ECX (sECX: 3 preoperative and 3 postoperative cycles of ECX with modified ECX plus lapatinib (mECX+L). This multicenter national trial was conducted in 29 centers in the United Kingdom in patients with histologically proven, HER2-positive, operable gastroesophageal adenocarcinoma. Registration for ERBB/HER2 testing took place from February 25, 2013, to April 19, 2016, and randomization took place between May 24, 2013, and April 21, 2016. Data were analyzed May 10, 2017, to May 25, 2017. Interventions: Patients were randomized 1:1 open-label to sECX (3 preoperative and 3 postoperative cycles of 50 mg/m2 of intravenous epirubicin on day 1, 60 mg/m2 intravenous cisplatin on day 1, 1250 mg/m2 of oral capecitabine on days 1 through 21) or mECX+L (ECX plus lapatinib days 1 through 21 in each cycle and as 6 maintenance doses). The first 10 patients in the mECX+L arm were treated with 1000 mg/m2 of capecitabine and 1250 mg of lapatinib per day, after which preoperative toxic effects were reviewed according to predefined criteria to determine doses for subsequent patients. Main Outcomes and Measures: Proportion of patients experiencing grade 3 or 4 diarrhea with mECX+L. A rate of 20% or less was considered acceptable. No formal comparison between arms was planned. Results: Between February 2013, and April 2016, 441 patients underwent central HER2 testing and 63 (14%) were classified as HER2 positive. Forty-six patients were randomized; 44 (24 sECX, 20 mECX+L) are included in this analysis. Two of the first 10 patients in the mECX+L arm reported preoperative grade 3 diarrhea; thus, no dose increase was made. The primary endpoint of preoperative grade 3 or 4 diarrhea rates were 0 of 24 in the sECX arm (0%) and 4 of 20 in the mECX+L arm (21%). One of 24 in the sECX arm and 3 of 20 in the mECX+L arm stopped preoperative treatment early, and for 4 of 19 in the mECX+L arm, lapatinib dose was reduced. Postoperative complication rates were similar in each arm. Conclusions and Relevance: Administration of 1250 mg of lapatinib per day in combination with ECX chemotherapy was feasible with some increase in toxic effects, which did not compromise operative management. Trial Registration: ISRCTN.org identifier: 46020948; clinicaltrialsregister.eu identifier: 2006-000811-12

    Kinetic CRAC uncovers a role for Nab3 in determining gene expression profiles during stress

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    RNA-binding proteins play a key role in shaping gene expression profiles during stress, however, little is known about the dynamic nature of these interactions and how this influences the kinetics of gene expression. To address this, we developed kinetic cross-linking and analysis of cDNAs (\u3c7CRAC), an ultraviolet cross-linking method that enabled us to quantitatively measure the dynamics of protein\u2013RNA interactions in vivo on a minute time-scale. Here, using \u3c7CRAC we measure the global RNA-binding dynamics of the yeast transcription termination factor Nab3 in response to glucose starvation. These measurements reveal rapid changes in protein\u2013RNA interactions within 1\u2009min following stress imposition. Changes in Nab3 binding are largely independent of alterations in transcription rate during the early stages of stress response, indicating orthogonal transcriptional control mechanisms. We also uncover a function for Nab3 in dampening expression of stress-responsive genes. \u3c7CRAC has the potential to greatly enhance our understanding of in vivo dynamics of protein\u2013RNA interactions
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