placeholder
and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Document type
Language
Year
  • 1
    Language: English
    In: arXiv.org, 2022-05-26
    Description: In a recent opinion article, Muff et al. recapitulate well-known objections to the Neyman-Pearson Null-Hypothesis Significance Testing (NHST) framework and call for reforming our practices in statistical reporting. We agree with them on several important points: the significance threshold P〈0.05 is only a convention, chosen as a compromise between type I and II error rates; transforming the p-value into a dichotomous statement leads to a loss of information; and p-values should be interpreted together with other statistical indicators, in particular effect sizes and their uncertainty. In our view, a lot of progress in reporting results can already be achieved by keeping these three points in mind. We were surprised and worried, however, by Muff et al.'s suggestion to interpret the p-value as a "gradual notion of evidence". Muff et al. recommend, for example, that a P-value 〉 0.1 should be reported as "little or no evidence" and a P-value of 0.001 as "strong evidence" in favor of the alternative hypothesis H1.
    Subject(s): Hypotheses ; Reforming ; Reporting
    E-ISSN: 2331-8422
    Source: ProQuest Central
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: Ecography (Copenhagen), 2017-02, Vol.40 (2), p.267-280
    Description: Macroecology and biogeography are concerned with understanding biodiversity patterns across space and time. In the past, the two disciplines have addressed this question mainly with correlative approaches, despite frequent calls for more mechanistic explanations. Recent advances in computational power, theoretical understanding, and statistical tools are, however, currently facilitating the development of more system‐oriented, mechanistic models. We review these models, identify different model types and theoretical frameworks, compare their processes and properties, and summarize emergent findings. We show that ecological (physiology, demographics, dispersal, biotic interactions) and evolutionary processes, as well as environmental and human‐induced drivers, are increasingly modelled mechanistically; and that new insights into biodiversity dynamics emerge from these models. Yet, substantial challenges still lie ahead for this young research field. Among these, we identify scaling, calibration, validation, and balancing complexity as pressing issues. Moreover, particular process combinations are still understudied, and so far models tend to be developed for specific applications. Future work should aim at developing more flexible and modular models that not only allow different ecological theories to be expressed and contrasted, but which are also built for tight integration with all macroecological data sources. Moving the field towards such a ‘systems macroecology’ will test and improve our understanding of the causal pathways through which eco‐evolutionary processes create diversity patterns across spatial and temporal scales.
    Subject(s): Analysis ; Biodiversity ; Biogeography ; Computer simulation ; Computer-generated environments ; Macroecology ; Models
    ISSN: 0906-7590
    E-ISSN: 1600-0587
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
    Source: ProQuest Central
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: Critical care (London, England), 2017-02-15, Vol.21 (1), p.32-32
    Description: Point-of-care testing (POCT) of coagulation has been proven to be of great value in accelerating emergency treatment. Specific POCT for direct oral anticoagulants (DOAC) is not available, but the effects of DOAC on established POCT have been described. We aimed to determine the diagnostic accuracy of Hemochron® Signature coagulation POCT to qualitatively rule out relevant concentrations of apixaban, rivaroxaban, and dabigatran in real-life patients. We enrolled 68 patients receiving apixaban, rivaroxaban, or dabigatran and obtained blood samples at six pre-specified time points. Coagulation testing was performed using prothrombin time/international normalized ratio (PT/INR), activated partial thromboplastin time (aPTT), and activated clotting time (ACT+ and ACT-low range) POCT cards. For comparison, laboratory-based assays of diluted thrombin time (Hemoclot) and anti-Xa activity were conducted. DOAC concentrations were determined by liquid chromatography-tandem mass spectrometry. Four hundred and three samples were collected. POCT results of PT/INR and ACT+ correlated with both rivaroxaban and dabigatran concentrations. Insufficient correlation was found for apixaban. Rivaroxaban concentrations at 〈30 and 〈100 ng/mL were detected with 〉95% specificity at PT/INR POCT ≤1.0 and ≤1.1 and ACT+ POCT ≤120 and ≤130 s. Dabigatran concentrations at 〈30 and 〈50 ng/mL were detected with 〉95% specificity at PT/INR POCT ≤1.1 and ≤1.2 and ACT+ POCT ≤100 s. Hemochron® Signature POCT can be a fast and reliable alternative for guiding emergency treatment during rivaroxaban and dabigatran therapy. It allows the rapid identification of a relevant fraction of patients that can be treated immediately without the need to await the results of much slower laboratory-based coagulation tests. Unique identifier, NCT02371070 . Retrospectively registered on 18 February 2015.
    Subject(s): Anticoagulants (Medicine) ; Anticoagulation reversal ; Blood clotting disorders ; Direct oral anticoagulants ; DOAC ; Dosage and administration ; Drug therapy ; Emergency medicine ; Emergency surgery ; NOAC ; Non-vitamin K antagonist oral anticoagulants ; POCT ; Point-of-care testing ; Stroke ; Thrombolysis ; Usage
    ISSN: 1364-8535
    E-ISSN: 1466-609X
    Source: BioMedCentral Open Access
    Source: PubMed Central
    Source: Alma/SFX Local Collection
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Global change biology, 2016-01, Vol.22 (1), p.137-150
    Description: Recognition of the importance of intraspecific variation in ecological processes has been growing, but empirical studies and models of global change have only begun to address this issue in detail. This review discusses sources and patterns of intraspecific trait variation and their consequences for understanding how ecological processes and patterns will respond to global change. We examine how current ecological models and theories incorporate intraspecific variation, review existing data sources that could help parameterize models that account for intraspecific variation in global change predictions, and discuss new data that may be needed. We provide guidelines on when it is most important to consider intraspecific variation, such as when trait variation is heritable or when nonlinear relationships are involved. We also highlight benefits and limitations of different model types and argue that many common modeling approaches such as matrix population models or global dynamic vegetation models can allow a stronger consideration of intraspecific trait variation if the necessary data are available. We recommend that existing data need to be made more accessible, though in some cases, new experiments are needed to disentangle causes of variation.
    Subject(s): Biological Evolution ; Climate Change ; Ecological and Environmental Phenomena ; Epigenesis, Genetic ; evolution ; Genetic Variation ; global change ; intraspecific variation ; Models, Theoretical ; Phenotype ; population differentiation ; population dynamics ; species range ; trait
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Hellenic Academic Libraries Link
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: Diversity & distributions, 2021-03-01, Vol.27 (3), p.392-401
    Description: Aim Empirical studies have often reported parallel patterns of genetic and species diversity, but the strength and generality of this association, as well as its origin, are still debated. Particularly in human‐dominated landscapes with complex histories of land use histories, more complicated and partly diverging patterns have been observed. In this study, we examine whether species and genetic diversity correlate across grasslands with different levels of land use pressure and spatial differentiation in habitat quality and heterogeneity. Location We selected eight extensively used (grazed, unfertilized) dry grasslands and eight intensively used (mown, fertilized) hay meadows in southeastern Germany. Methods We used vegetation surveys and molecular markers of six widespread dry grassland and six hay meadow plant species to compare species and genetic alpha and beta diversity between the two grassland types. Results Species diversity patterns expectedly showed higher alpha diversity, stronger spatial structure and less turnover in dry grasslands than in hay meadows. Neither of the corresponding genetic diversity patterns showed the same significant trends. Main conclusion Our results question the idea that species and genetic diversity patterns will always show similar patterns. Likely, genetic and species diversity emerge partly from shared, partly from different processes, including the regional species pool, environmental heterogeneity, fragmentation and land use history. The practical conservation implication is that species and genetic diversity are not generally interchangeable. Looking at species and genetic patterns together, however, may eventually lead to a better understanding of the complex processes that shape the structure and dynamics of ecological communities.
    Subject(s): Biodiversity ; BIODIVERSITY RESEARCH ; Biological diversity ; dry grassland ; Endangered & extinct species ; Environmental quality ; Equilibrium ; Genetic diversity ; Genetic research ; Grasslands ; grazing ; Habitats ; hay meadow ; Heterogeneity ; Land use ; Meadows ; mowing ; Plant species ; Population ; Species diversity ; species genetic diversity correlation ; Vegetation surveys ; Wildlife conservation
    ISSN: 1366-9516
    E-ISSN: 1472-4642
    Source: Academic Search Ultimate
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
    Source: ProQuest Central
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: PloS one, 2018, Vol.13 (5), p.e0198114-e0198114
    Description: No evidence-based therapy exists for non-arteritic central retinal artery occlusion (NA-CRAO). Retinal ischemic tolerance is low; irreversible damage occurs within four hours of experimental NA-CRAO. In previous randomized trials evaluating intra-arterial or intravenous thrombolysis (IVT) in NA-CRAO, only one patient was treated this early. In December 2013, the Departments of Neurology & Stroke and Ophthalmology at University Hospital Tuebingen, Germany, decided to treat patients using IVT within 4.5 hours of NA-CRAO, the therapeutic window established for ischemic stroke. Consecutive NA-CRAO patients with severe visual loss received IVT after exclusion of intracranial hemorrhage. Follow-up was conducted at day 5 (d5) and day 30 (d30). Visual outcomes were compared to the conservative standard treatment (CST) arm of the EAGLE-trial. Until August 2016, 20 patients received IVT within 4.5 hours after NA-CRAO with a median onset-to-treatment time of 210 minutes (IQR 120-240). Visual acuity improved from baseline mean logarithm of the minimum angle of resolution 2.46±0.33 (SD) (light perception) to 1.52±1.09 (Snellen equivalent: 6/200) at d5 (p = 0.002) and 1.60±1.08 (Snellen equivalent: 6/240) at d30. Compared to the EAGLE CST-arm, functional recovery to reading ability occurred more frequently after IVT: 6/20 (30%) versus 1/39 (3%) at d5 (p = 0.005) and at d30 5/20 (25%) versus 2/37 (5%) (p = 0.045). Two patients experienced serious adverse events (one angioedema and one bleeding from an abdominal aortic aneurysm) but recovered without sequelae. IVT within 4.5 hours after symptom onset may represent an effective treatment of NA-CRAO. Randomized trials are warranted to evaluate efficacy and safety of early IVT in acute NA-CRAO.
    Subject(s): Acuity ; Angioedema ; Aorta ; Biology and Life Sciences ; Bleeding ; Brain research ; Care and treatment ; Clinical trials ; Complications ; Damage tolerance ; Equivalence ; Fibrinolysis ; Hemorrhage ; Hospitals ; Intravenous administration ; Ischemia ; Medicine and Health Sciences ; Meta-analysis ; Methods ; Neurology ; Occlusion ; Ophthalmology ; Patients ; Randomization ; Recovery of function ; Research and Analysis Methods ; Retina ; Retinal diseases ; Social Sciences ; Stroke ; Stroke (Disease) ; Thrombolysis ; Usage ; Veins & arteries ; Visual acuity
    ISSN: 1932-6203
    E-ISSN: 1932-6203
    Source: Academic Search Ultimate
    Source: PubMed Central
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Methods in ecology and evolution, 2021-11, Vol.12 (11), p.2159-2173
    Description: Joint species distribution models (JSDMs) explain spatial variation in community composition by contributions of the environment, biotic associations and possibly spatially structured residual covariance. They show great promise as a general analytical framework for community ecology and macroecology, but current JSDMs, even when approximated by latent variables, scale poorly on large datasets, limiting their usefulness for currently emerging big (e.g. metabarcoding and metagenomics) community datasets. Here, we present a novel, more scalable JSDM (sjSDM) that circumvents the need to use latent variables by using a Monte Carlo integration of the joint JSDM likelihood together with flexible elastic net regularization on all model components. We implemented sjSDM in PyTorch, a modern machine learning framework, which allows making use of both CPU and GPU calculations. Using simulated communities with known species–species associations and different number of species and sites, we compare sjSDM with state‐of‐the‐art JSDM implementations to determine computational runtimes and accuracy of the inferred species–species and species–environment associations. We find that sjSDM is orders of magnitude faster than existing JSDM algorithms (even when run on the CPU) and can be scaled to very large datasets. Despite the dramatically improved speed, sjSDM produces more accurate estimates of species association structures than alternative JSDM implementations. We demonstrate the applicability of sjSDM to big community data using eDNA case study with thousands of fungi operational taxonomic units (OTU). Our sjSDM approach makes the analysis of JSDMs to large community datasets with hundreds or thousands of species possible, substantially extending the applicability of JSDMs in ecology. We provide our method in an R package to facilitate its applicability for practical data analysis.
    Subject(s): Algorithms ; big data ; Community composition ; Computer applications ; co‐occurrence ; Data analysis ; Data sets ; Datasets ; Geographical distribution ; Learning algorithms ; Machine learning ; metacommunity ; Metagenomics ; Regularization ; Spatial variations ; Species ; statistics
    ISSN: 2041-210X
    E-ISSN: 2041-210X
    Source: Alma/SFX Local Collection
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: Ecography (Copenhagen), 2017-08, Vol.40 (8), p.913-929
    Description: Ecological data often show temporal, spatial, hierarchical (random effects), or phylogenetic structure. Modern statistical approaches are increasingly accounting for such dependencies. However, when performing cross‐validation, these structures are regularly ignored, resulting in serious underestimation of predictive error. One cause for the poor performance of uncorrected (random) cross‐validation, noted often by modellers, are dependence structures in the data that persist as dependence structures in model residuals, violating the assumption of independence. Even more concerning, because often overlooked, is that structured data also provides ample opportunity for overfitting with non‐causal predictors. This problem can persist even if remedies such as autoregressive models, generalized least squares, or mixed models are used. Block cross‐validation, where data are split strategically rather than randomly, can address these issues. However, the blocking strategy must be carefully considered. Blocking in space, time, random effects or phylogenetic distance, while accounting for dependencies in the data, may also unwittingly induce extrapolations by restricting the ranges or combinations of predictor variables available for model training, thus overestimating interpolation errors. On the other hand, deliberate blocking in predictor space may also improve error estimates when extrapolation is the modelling goal. Here, we review the ecological literature on non‐random and blocked cross‐validation approaches. We also provide a series of simulations and case studies, in which we show that, for all instances tested, block cross‐validation is nearly universally more appropriate than random cross‐validation if the goal is predicting to new data or predictor space, or for selecting causal predictors. We recommend that block cross‐validation be used wherever dependence structures exist in a dataset, even if no correlation structure is visible in the fitted model residuals, or if the fitted models account for such correlations.
    Subject(s): Autoregressive models ; Autoregressive processes ; Blocking ; Case studies ; Computer simulation ; Correlation ; Ecological effects ; Extrapolation ; Interpolation ; Least squares method ; Literature reviews ; Mathematical models ; Models ; Phylogenetics ; Phylogeny ; Structural hierarchy
    ISSN: 0906-7590
    E-ISSN: 1600-0587
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
    Source: ProQuest Central
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: Science (American Association for the Advancement of Science), 2018-05-25, Vol.360 (6391)
    Description: LaManna (Reports, 30 June 2017, p. 1389) found higher conspecific negative density dependence in tree communities at lower latitudes, yielding a possible mechanistic explanation for the latitudinal diversity gradient. We show that their results are artifacts of a selective data transformation and a forced zero intercept in their fitted model. A corrected analysis shows no latitudinal trend.
    Subject(s): Biodiversity ; Density dependence ; Dependence ; Plant diversity ; Rare species
    ISSN: 0036-8075
    E-ISSN: 1095-9203
    Source: Academic Search Ultimate
    Source: Alma/SFX Local Collection
    Source: Get It Now
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: Journal of biogeography, 2012-12, Vol.39 (12), p.2119-2131
    Description: Within the field of species distribution modelling an apparent dichotomy exists between process-based and correlative approaches, where the processes are explicit in the former and implicit in the latter. However, these intuitive distinctions can become blurred when comparing species distribution modelling approaches in more detail. In this review article, we contrast the extremes of the correlative—process spectrum of species distribution models with respect to core assumptions, model building and selection strategies, validation, uncertainties, common errors and the questions they are most suited to answer. The extremes of such approaches differ clearly in many aspects, such as model building approaches, parameter estimation strategies and transferability. However, they also share strengths and weaknesses. We show that claims of one approach being intrinsically superior to the other are misguided and that they ignore the process—correlation continuum as well as the domains of questions that each approach is addressing. Nonetheless, the application of process-based approaches to species distribution modelling lags far behind more correlative (process-implicit) methods and more research is required to explore their potential benefits. Critical issues for the employment of species distribution modelling approaches are given, together with a guideline for appropriate usage. We close with challenges for future development of process-explicit species distribution models and how they may complement current approaches to study species distributions.
    Subject(s): Applied ecology ; Biodiversity ; Biogeochemistry ; Biological diversity ; Biological diversity conservation ; Biometry ; Climate change ; Climate models ; Conservation biology ; Correlatives ; Ecological modeling ; Environmental conservation ; Forest ecology ; Hypothesis generation ; mechanistic model ; Modeling ; Models ; parameterization ; Parametric models ; process-based model ; SDM ; Species ; species distribution model ; uncertainty ; Universities and colleges ; validation
    ISSN: 0305-0270
    E-ISSN: 1365-2699
    Source: JSTOR Life Sciences
    Source: Hellenic Academic Libraries Link
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...