44 research outputs found

    Non-Standard Errors

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    In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence-generating process (EGP). We claim that EGP variation across researchers adds uncertainty: Non-standard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for better reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants

    Experimental estimation of assimilation rates of meiofauna feeding on 14C-labelled benthic diatoms

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    International audienceKnowledge of the trophic position of meiofauna in marine sediments is still contradictory primarily due to the scarcity of experimental data. The present study analyses diatom-feeders among the meiofauna. The assimilation rate of carbon by meiofauna was determined through a grazing experiment using in situ collected diatoms pre-labelled with 14 C. The assimilation rates of diatom carbon were estimated for the bulk meiofaunal community (0.84 ng C.ind −1 .h −1), for the bulk harpacticoid copepods (1.92 ng C.ind. −1 h −1) and for two dominant nematode species (Metachromadora remanei 1.26 ng C ind −1 h −1 , Daptonema oxycerca 1.35 ngC.ind. −1 h −1). Experimental results were extrapolated to compute the consumption of meiofauna in situ that would attain up to 12% of primary benthic production in the Brouage mudflat (Marennes-Oléron Bay, southwest Atlantic coast)

    Stable isotope analysis of food source and trophic position of intertidal nematodes and copepods

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    Four dominant nematode species and various copepods from an intertidal mudflat in Marennes-Oleron Bay were analyzed for delta C-13 and delta N-15 ratios together with their potential food source, the microphytobenthos. It was shown that microphytobenthic C is passed to nematodes either by grazing or predation on herbivorous meiofauna by other nematodes. Diatoms of different sizes exhibited different C-13 content, which can be reflected in herbivorous meiofauna, such as the nematodes Daptonema oxycerca and Metachromadora remanei and the bulk of copepods, indicating they can select different sizes of diatoms. Results confirm the need to analyze meiofauna feeding habits at the species or genera level since the delta N-15 and delta C-13 signatures differed substantially among meiofaunal species

    Long-term outcomes and determinants of restenosis after renal artery angioplasty in hypertensive patients with renovascular disease

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    Abstract Introduction Restenosis (RS) following percutaneous angioplasty (PTA) of renal artery stenosis (RAS) might have an unfavorable impact on renal function and blood pressure (BP) outcomes. Aim To evaluate prevalence and predictors of RS in patients treated with PTA for RAS, and relationship between BP and renal function (RF) changes with RS. Material and methods We analyzed freedom from RS in 210 patients (64.6±12.8; range:20–85y.o.), who underwent 248 successful stent-assisted PTAs in RAS. The change in levels of serum creatinine (SCC), eGFR, systolic/diastolic BPs (SBP/DBP) were analyzed prior to PTA, at 6-, 12-months and final follow-up visits, and whenever RS was diagnosed. Results RS was identified in 30 (14.3%) patients and 36 (14.5%) lesions. The Kaplan-Meier RS-free survival curves in fibromuscular dysplasia, atherosclerosis and vasculitis were: 100% and 100%; 95.6 and 83.9%, while 71.4 and 39.7% at 1 and 7-years, respectively. Patients with RS, as compared to RS-free patients, presented with lesser response in changes of: SBP (1.4±17.6 vs −15.8±25.8mmHg; p=0.01), DBP (2.64±10.1 vs. −6.5±14.1mmHg; p=0.002), SCC (22.4±55.2 vs −3.6±43.9μmol/L; p=0.002) and eGFR (−1.85±18 vs. −5.34±19.5mmHg; p=0.045). In multivariate Cox regression analysis, independent predictors of RS occurred: lack of BP decrease (HR: 4.19, 95% CI: 1.67–10.3; p=0.002), lack of eGFR increase of less than ≤0.17 ml/min/1.73m2 (HR: 2.93, 95% CI: 1.08–7.91; p=0.033), stent diameter ≤5mm (HR: 2.76, 95% CI: 1.09–6.97; p=0.031) and vasculitis (HR: 5.61, 95% CI: 1.83–17.2; p=0.003). RS was treated in 24 patients with RS recurrence in 20%. Conclusions RS rate differs depending on RAS etiology. Lack of SBP/DBP and eGFR improvement, vasculitis, and stent diameter are associated with RS risk. Repeated PTA is effective, but recurrent RS occurs in 20% of cases. Kaplan-Meier RS-free survival curves Funding Acknowledgement Type of funding source: None </jats:sec

    Clinical response scores to predict blood pressure and renal function improvement following renal artery stenting for atherosclerotic renal artery stenosis

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    Abstract Background It is little known about predictors of systolic (SBP) and diastolic (DBP) blood pressure or renal function (eGFR) improvement in patients with atherosclerotic renal artery stenosis (ARAS) undergoing stent-assisted angioplasty (PTA). Therefore, we aimed to build a prediction scores that would indicate characteristics of patient subsets with ARAS most likely to have clinical improvement following PTA. Methods 201 patients who underwent PTA for ARAS (2003–2018) were categorized as eGFR or SBP/DBP responders based on eGFR increase of ≥11 ml/min/1.73m2, decrease of SBP ≥20mmHg and DBP ≥5mmHg at 12-months following PTA. The remaining patients were classified as non-responders. The performance of logistic regression models were evaluated by basic decision characteristics. Continuous data have been transformed into binary coding with help of operating characteristic (ROC) curve. Predictive models have been constructed for each followed by construction of predictive models in each of 3 categories. Results Logistic regression analysis showed that: baseline SBP&amp;gt;145 mmHg, DBP &amp;gt;82 mmHg, previous myocardial infarction and Renal-Aotric-Ratio &amp;gt;5.1 were independent influencing factors of SBP response, with relative risk percentage shares of 69.8%; 12.1%; 10.9%; and 7.2%, respectively (sensitivity: 82%, specificity: 86.3%, positive (PPV):82% and negative (NPV) predictive values: 86.3%). The DBP decrease prediction model included baseline SBP &amp;gt;145 mmHg and DBP &amp;gt;82 mmHg, the ARAS progression, index kidney length &amp;gt;106 mm, and bilateral PTA with respective shares of 35.0%; 21.8%; 18.2%; 13.3% and 11.8%. (sensitivity: 76%, specificity: 77.8%, PPV: 80.7% and NPV: 72.6%). The eGFR increase was associated with baseline serum creatinine &amp;gt;122 μmol/L but eGFR greater than 30 ml/min/1.73m2, index kidney length &amp;gt;98 mm, end-diastolic velocity in index renal artery, renal resistive index &amp;lt;0.74, and requirement for &amp;gt;3 BP medications, with respective shares of 24.4%; 24.4%; 21.2%; 15% and 15% (sensitivity: 33.3%, specificity: 93.5%, PPV: 65.6% and NPV: 78.9%). Conclusions Current study identified clinical characteristics of patients who most likely to respond to PTA for ARAS. The sutability of the score should be verified in a prospective cohort of patients referred to PTA of ARAS Funding Acknowledgement Type of funding source: None </jats:sec

    How do food sources drive meiofauna community structure in soft bottom coastal food webs?

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    International audienceMeiofauna have a strong role in the functioning of coastal ecosystems but how their food sources affect their community structure remains unclear, likely due to the influence of abiotic parameters and the small size of these organisms. The meiofauna and their potential food sources were sampled in several intertidal habitats (i.e., mudflat, seagrass bed, sandflat) of the Marennes-Oléron Bay, France, and the Sylt-Rømø Bight, Germany, to assess the relationships between habitat characteristics and meiofauna community structure. Biomass and quality (carbon/chlorophyll a ratios) of food sources were estimated. Meiofauna community structure based on density and biomass was determined, as well as nematode diversity and feeding types. Meiofauna density and biomass varied highly within habitats and within ecosystems, ranging from 1.7 × 10⁵ to 3.4 × 10⁶ ind. m⁻² and from 0.057 to 1.541 gC m⁻², respectively. Benthic microalgae and sediment organic matter are important drivers in these food webs as the density of two important trophic groups of nematodes, non-selective deposit feeders and epigrowth feeders, varied in accordance with these food sources. No clear relationship was observed between bacterial biomass and selective deposit feeders (i.e., bacterivores) probably due to the high production rate of bacteria. Complementary information about production rates of food source as well as data from trophic markers would provide complimentary information to better understand flows of organic matter in intertidal habitats, particularly for opportunistic species such as non-selective deposit feeders
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