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Seasonality modulates the predictive skills of diatom based salinity transfer functions.

ABSTRACT: The value of diatoms as bioindicators in contemporary and palaeolimnological studies through transfer function development has increased in the last decades. While such models represent a tremendous advance in (palaeo) ecology, they leave behind important sources of uncertainties that are often ignored. In the present study we tackle two of the most important sources of uncertainty in the development of diatom salinity inference models: the effect of secondary variables associated to seasonality and the comparison of conventional cross-validation methods with a validation based on independent datasets. Samples (diatoms and environmental variables) were taken in spring, summer and autumn in the freshwater and brackish ditches of the province of North Holland in 1993. Different locations of the same province were sampled again in 2008-2010 to validate the models. We found that the abundance of the dominant species significantly changed between the seasons, leading to inconsistent estimates of species optima and tolerances. A model covering intra-annual variability (all seasons combined) provides averages of species optima and tolerances, reduces the effect of secondary variables due to the seasonality effects, thus providing the strongest relationship between salinity and diatom species. In addition, the ¨all-season¨ model also reduces the edge effects usually found in all unimodal-based calibration methods. While based on cross-validation all four models seem to perform relatively well, a validation with an independent dataset emphasizes the importance of using models covering intra-annual variability to perform realistic reconstructions.

SUBMITTER: Goldenberg Vilar A

PROVIDER: S-EPMC6245675 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Seasonality modulates the predictive skills of diatom based salinity transfer functions.

Goldenberg Vilar Alejandra A Donders Timme T Cvetkoska Aleksandra A Wagner-Cremer Friederike F

PloS one 20181120 11

The value of diatoms as bioindicators in contemporary and palaeolimnological studies through transfer function development has increased in the last decades. While such models represent a tremendous advance in (palaeo) ecology, they leave behind important sources of uncertainties that are often ignored. In the present study we tackle two of the most important sources of uncertainty in the development of diatom salinity inference models: the effect of secondary variables associated to seasonality ...[more]

PMID: 30458002

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Project description:CONTEXT:Dyad practice may be as effective as individual practice during clinical skills training, improve students' confidence, and reduce costs of training. However, there is little evidence that dyad training is non-inferior to single-student practice in terms of skills transfer. OBJECTIVES:This study was conducted to compare the effectiveness of simulation-based ultrasound training in pairs (dyad practice) with that of training alone (single-student practice) on skills transfer. METHODS:In a non-inferiority trial, 30 ultrasound novices were randomised to dyad (n = 16) or single-student (n = 14) practice. All participants completed a 2-hour training programme on a transvaginal ultrasound simulator. Participants in the dyad group practised together and took turns as the active practitioner, whereas participants in the single group practised alone. Performance improvements were evaluated through pre-, post- and transfer tests. The transfer test involved the assessment of a transvaginal ultrasound scan by one of two clinicians using the Objective Structured Assessment of Ultrasound Skills (OSAUS). RESULTS:Thirty participants completed the simulation-based training and 24 of these completed the transfer test. Dyad training was found to be non-inferior to single-student training: transfer test OSAUS scores were significantly higher than the pre-specified non-inferiority margin (delta score 7.8%, 95% confidence interval -3.8-19.6%; p = 0.04). More dyad (71.4%) than single (30.0%) trainees achieved OSAUS scores above a pre-established pass/fail level in the transfer test (p = 0.05). There were significant differences in performance scores before and after training in both groups (pre- versus post-test, p < 0.01) with large effect sizes (Cohen's d = 3.85) and no significant interactions between training type and performance (p = 0.59). The dyad group demonstrated higher training efficiency in terms of simulator score per number of attempts compared with the single-student group (p = 0.03). CONCLUSION:Dyad practice improves the efficiency of simulation-based training and is non-inferior to individual practice in terms of skills transfer.

Project description:Background and aimsOver the last decade, the importance of plant biomechanical properties in shaping wave dissipation efficiency of marsh vegetation has gained growing attention. Here we provide the first analyses of how biomechanical stem properties vary with seasons and along environmental gradients in coastal and estuarine marshes, which is essential to enable accurate assessments of flood defence value of marsh vegetation.MethodsWe quantified both spatial and seasonal variation in stem flexibility and breakability for a variety of common marsh vegetation (Spartina anglica, Scirpus maritimus, Phragmites australis, Elymus athericus, Suaeda maritima, Aster tripolium, Saliconia procumbens) distributed along both salinity and inundation gradients.Key resultsIncreasing salinity tends to induce a shift from species with tall shoots, high flexural stiffness (stem resistance to bending; N mm2) towards species with shorter and more flexible stems. The same trend was found with increasing inundation stress (i.e. decreasing elevation) from the higher part of the low marsh towards the pioneer zone. Stem breakability (the force required to break or fold a stem, N) followed the same pattern of stem stiffness due to the positive relationship between flexural strength (material resistance to flexure, N mm-2) and Young's bending modulus (material resistance to bending; N mm-2). Shifts in stem stiffness and breakability at the community level were found to relate positively to the variation in canopy height between species, highlighting the concurrence of changes in morphological and biomechanical traits under environmental changes. Compared to the differences between species, within-species variability between sampling locations and between seasons is generally minor.ConclusionsOur findings imply that environmental changes may significantly modify wave attenuation capacity of coastal vegetation by inducing species shifts. This emphasizes the need to understand the response of community composition to climate change and human disturbances, when using nature-based flood protection by coastal vegetation as an adaptive response to global change.

Project description:BACKGROUND:Curricular constraints require being selective about the type of content trainees practice in their formal training. Teaching trainees procedural knowledge about "how" to perform steps of a skill along with conceptual knowledge about "why" each step is performed can support skill retention and transfer (i.e., the ability to adapt knowledge to novel problems). However, how best to organize how and why content for procedural skills training is unknown. OBJECTIVES:We examined the impact of different approaches to integrating why and how content on trainees' skill retention and transfer of simulation-based lumbar puncture (LP). DESIGN AND PARTICIPANTS:We randomized medical students (N?=?66) to practice LP for 1 h using one of three videos. One video presented only the how content for LP (Procedural Only). Two other videos presented how and why content (e.g., anatomy) in two ways: Integrated in Sequence, with why content followed by how content, or Integrated for Causation, with how and why content integrated throughout. MAIN MEASURES:Pairs of blinded raters scored participants' retention and transfer LP performances on a global rating scale (GRS), and written tests assessed participants' procedural and conceptual knowledge. KEY RESULTS:Simple mediation regression analyses showed that participants receiving an integrated instructional video performed significantly better on transfer through their intervention's positive impact on conceptual knowledge (all p?<?0.01). Further, the Integrated for Causation group performed significantly better on transfer than the Integrated in Sequence group (p?<?0.01), again mediated by improved conceptual knowledge. We observed no mediation of participants' skill retention (all p?>?0.01). CONCLUSIONS:When teaching supports cognitive integration of how and why content, trainees are able to transfer learning to new problems because of their improved conceptual understanding. Instructional designs for procedural skills that integrate how and why content can help educators optimize what trainees learn from each repetition of practice.

Dataset Information

Seasonality modulates the predictive skills of diatom based salinity transfer functions.

Publications

Seasonality modulates the predictive skills of diatom based salinity transfer functions.

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