385 research outputs found

    Accounting for black carbon lowers estimates of blue carbon storage services

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    The canopies and roots of seagrass, mangrove, and saltmarsh protect a legacy of buried sedimentary organic carbon from resuspension and remineralisation. This legacy’s value, in terms of mitigating anthropogenic emissions of CO2, is based on total organic carbon (TOC) inventories to a depth likely to be disturbed. However, failure to subtract allochthonous recalcitrant carbon overvalues the storage service. Simply put, burial of oxidation-resistant organics formed outside of the ecosystem provides no additional protection from remineralisation. Here, we assess whether black carbon (BC), an allochthonous and recalcitrant form of organic carbon, is contributing to a significant overestimation of blue carbon stocks. To test this supposition, BC and TOC contents were measured in different types of seagrass and mangrove sediment cores across tropical and temperate regimes, with different histories of air pollution and fire together with a reanalysis of published data from a subtropical system. The results suggest current carbon stock estimates are positively biased, particularly for low-organic-content sandy seagrass environs, by 18 ± 3% (±95% confidence interval) and 43 ± 21% (±95% CI) for the temperate and tropical regions respectively. The higher BC fractions appear to originate from atmospheric deposition and substantially enrich the relatively low TOC fraction within these environs

    Antioxidant Activity of the Phenolic Leaf Extracts from Monechma ciliatum in Stabilization of Corn Oil

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    The total phenolic content and the antioxidan potential of methanolic extract (ME), ethyl acetate extract (EAE), and hexane extract (HE) from Monechma ciliatum leaves (MCL) were evaluated. The Folin-Ciocalteu, b-carotene bleaching, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and the accelerated oxidation methods were used for evaluation. Both the extraction yield and the antioxidant activity (AOA) were strongly dependent on the solvent. Among the extracts, ME exhibited highest total phenolic compounds (TPC) and IC50 values for DPPH, followed by EAE and HE, respectively. Peroxide value (PV), anisidine value (AV) conjugated dienes (CD), and thiobarbituric acid reactive substances (TBARS) were taken as the parameters for evaluation of stabilization efficacy of MCL extracts and results revealed MCL to be a potent antioxidant for the stabilization of corn oil. As a general trend, increased AOA was observed for increased extract concentration. The predominant phenolic compounds identified by HPLC-DAD in MCL extracts were p-coumaric acid, vanillin and ferulic acid

    Antioxidant Activity of the Phenolic Leaf Extracts from Monechma ciliatum in Stabilization of Corn Oil

    Get PDF
    The total phenolic content and the antioxidan potential of methanolic extract (ME), ethyl acetate extract (EAE), and hexane extract (HE) from Monechma ciliatum leaves (MCL) were evaluated. The Folin-Ciocalteu, b-carotene bleaching, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and the accelerated oxidation methods were used for evaluation. Both the extraction yield and the antioxidant activity (AOA) were strongly dependent on the solvent. Among the extracts, ME exhibited highest total phenolic compounds (TPC) and IC50 values for DPPH, followed by EAE and HE, respectively. Peroxide value (PV), anisidine value (AV) conjugated dienes (CD), and thiobarbituric acid reactive substances (TBARS) were taken as the parameters for evaluation of stabilization efficacy of MCL extracts and results revealed MCL to be a potent antioxidant for the stabilization of corn oil. As a general trend, increased AOA was observed for increased extract concentration. The predominant phenolic compounds identified by HPLC-DAD in MCL extracts were p-coumaric acid, vanillin and ferulic acid

    Exile

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    Byron rehearsed going into exile in 1809, when he was twenty-one years old. Before setting sail for Lisbon, he wrote, “I leave England without regret, I shall return to it without pleasure. – I am like Adam the first convict sentenced to transportation, but I have no Eve, and have eaten no apple but what was sour as a crab and thus ends my first Chapter” (BLJ 1: 211). Byron’s sardonic perception of himself as a biblical exile foreshadowed the allusive character of his second longer-term exile at the age of twenty-eight, when his carefully staged exit required an audience (some of the same friends and servants), expensive props (a replica of Napoleon’s carriage) and a literary precursor. On his last evening in England, Byron visited the burial place of the satirist Charles Churchill, and lay down on his grave. It was a performance of immense weariness with life and solidarity with an embittered outcast.Postprin

    The Lake Poets

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    “If Southey had not been comparatively good,” writes Herbert F. Tucker, “he would never have drawn out Byron’s best in those satirical volleys that were undertaken, at bottom, in order to reprehend not the want of talent but its wastage.” And if Wordsworth and Coleridge had not been dangerously talented, Byron might have spared them some of his stinging sallies. In Table Talk Coleridge proclaimed the conclusion of the “intellectual war” Byron threatened in Don Juan (XI. 62: 496), declaring Wordsworth the poet who “will wear the crown,” triumphing over Byron and his ilk for the poetic laurels of the Romantic period. But Byron was not simply an opponent of his contemporaries. His responses to the Lake poets, particularly to Wordsworth, ran the gamut from “reverence” (HVSV, 129) then “nausea” (Medwin, 237) to Don Juan’s comical though cutting disdain, in under a decade. Focusing on Byron’s relationship with Wordsworth and Coleridge, I will show how Byron’s poetry and drama reveal the range and complexity of his dialogue with his older peers, where, even at their most apparently divergent, the conversation between the poets reveals the depth of the engagement across their works

    Systematic review on the prevalence, frequency and comparative value of adverse events data in social media

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    Aim: The aim of this review was to summarize the prevalence, frequency and comparative value of information on the adverse events of healthcare interventions from user comments and videos in social media. Methods: A systematic review of assessments of the prevalence or type of information on adverse events in social media was undertaken. Sixteen databases and two internet search engines were searched in addition to handsearching, reference checking and contacting experts. The results were sifted independently by two researchers. Data extraction and quality assessment were carried out by one researcher and checked by a second. The quality assessment tool was devised in-house and a narrative synthesis of the results followed. Results: From 3064 records, 51 studies met the inclusion criteria. The studies assessed over 174 social media sites with discussion forums (71%) being the most popular. The overall prevalence of adverse events reports in social media varied from 0.2% to 8% of posts. Twenty-nine studies compared the results from searching social media with using other data sources to identify adverse events. There was general agreement that a higher frequency of adverse events was found in social media and that this was particularly true for ‘symptom’ related and ‘mild’ adverse events. Those adverse events that were under-represented in social media were laboratory-based and serious adverse events. Conclusions: Reports of adverse events are identifiable within social media. However, there is considerable heterogeneity in the frequency and type of events reported, and the reliability or validity of the data has not been thoroughly evaluated

    Misperceptions About β-Blockers and Diuretics

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    Based on a series of clinical trials showing no difference in the effectiveness or tolerability of most major classes of antihypertensive medications, the Joint National Commission on High Blood Pressure Treatment recommends that physicians prescribe β-blockers or diuretics as initial hypertensive therapy unless there are compelling indications for another type of medication. Nevertheless, many physicians continue to favor more expensive medications like angiotensin-converting enzyme (ACE) inhibitors and calcium channel blockers as first line agents. The persistent use of these agents raises questions as to whether physicians perceive ACE inhibitors and calcium channel blockers to be better than β-blockers and diuretics. METHODS:  We surveyed 1,200 primary care physicians in 1997, and another 500 primary care physicians in 2000, and asked them to estimate the relative effectiveness and side effects of 4 classes of medication in treating a hypothetical patient with uncomplicated hypertension: ACE inhibitors, β-blockers, calcium channel blockers, and diuretics. In addition, we asked them to indicate whether they ever provided free samples of hypertension medications to their patients. RESULTS:  Perceptions of the relative effectiveness and side effects of the 4 classes of hypertension medications did not significantly change over the 3 years, nor did prescription recommendations. Physicians perceive that diuretics are less effective at lowering blood pressure than the other 3 classes ( P  < .001). They also perceive that β-blockers are less tolerated than the other 3 classes ( P  < .001). In a multivariate model, perceptions of effectiveness and tolerability displayed significant associations with prescription preference independent of background variables. The only other variable to contribute significantly to the model was provision of free medication samples to patients. CONCLUSIONS:  Despite numerous clinical trials showing no difference in the effectiveness or side-effect profiles of these 4 classes of drugs, most physicians believed that diuretics were less effective and β-blockers were less tolerated than other medications. Moreover, their prescription practices were associated with their provision of free samples provided by pharmaceutical representatives, even after adjusting for other demographic characteristics. Efforts to increase physicians’ prescribing of β-blockers and diuretics may need to be directed at overcoming misunderstandings about the effectiveness and tolerability of these medicines. J GEN INTERN MED 2003;18:977–983.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75385/1/j.1525-1497.2003.20414.x.pd
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