1,720,970 research outputs found
Evaluating functional performance of evapotranspiration models based on causal discovery methods
No full textSubmission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-05-01The student, Jiaze Cao, accepted the attached license on 2025-04-15 at 13:30.The student, Jiaze Cao, submitted this Thesis for approval on 2025-04-15 at 13:40.This Thesis was approved for publication on 2025-04-17 at 14:48.DSpace SAF Submission Ingestion Package generated from Vireo submission #21766 on 2025-10-19 at 19:14:42Investigating causal relationships is critical in ecohydrological systems to understand how variables interact, anticipate future trends, and develop effective models. Traditional predictive performance measures, which compare observations to modeled outputs, cannot fully verify generalization ability and do not address representations of causal linkages between inputs, observations, and outputs. Functional performance focuses on relationships between the target and source variables, but similar to predictive performance metrics, there are multiple ways to quantify these relationships. We compare four causal discovery methods (Granger causality, Transfer Entropy, PCMCI, and Convergent Cross Mapping) to analyze the functional performance of models of evapotranspiration (ET) in an intensively managed agricultural landscape based on eddy covariance measurements over seven years. Evapotranspiration is a critical component of both the energy and water cycles, playing a key role in water resource management and irrigation planning. We first compare methods with linear, nonlinear, and chaotic test cases to evaluate how causal discovery varies with system dynamics, temporal aggregation, and noise. We find that the four methods identify accurate causal relationships to a large extent, but temporal aggregation, and particularly data resampling, can lead to diverging results. Subsequently, we apply the methods to analyze causal sources within three ET models: Priestly-Taylor (PT), Surface Flux Equilibrium (SFE), and Soil Water Balance (SWB) relative to tower observations. The causal discovery methods consistently identify model inputs as primary causal sources, such as net radiation, relative humidity, and temperature for PT and SFE, and soil moisture for SWB. In a functional performance assessment, we rely on the causal strength measures derived from Transfer Entropy and Granger Causality. The functional performance metric offers improved interpretability and flexibility, enabling model evaluation across varying temporal intervals. Among the evaluated models, the functional performance aligns closely with predictive performance, identifying SFE as the best-performing model. We further apply functional performance metrics to evaluate the OpenET dataset, which contains multiple satellite-derived ET products. Although OpenET models rely primarily on satellite-based inputs, they exhibit higher functional performance, indicating a more accurate representation of evapotranspiration processes. The analysis reveals that functional performance metrics offer unique insights into model behavior, aligning with predictive performance, especially when substantial performance differences exist. This study shows how functional performance complements traditional model evaluations, but also highlights sensitivities to different causal inference methods and time scales
Temporal information partitioning networks to infer ecohydrologic behaviors
Get PDF"An ecohydrologic system is a complex network, in which the shifting behavior of individual components and the connectivity between them determines the dynamics. This connectivity between components can act to constrain, accentuate, or otherwise modify the variability of individuals. In an ecohydrologic system, connectivity exists in the form of many time dependent relationships between states and fluxes related to water, energy, nutrients, soils, and vegetation. Although relationships are constrained by conservation laws, they exhibit a wide range of variability at many timescales due to non-linear interactions, threshold behavior, forcing, and feedback. Moreover, these aspects of connectivity and variability exist at a single location or over a spatial gradient. The understanding of this connectivity within the system as a whole necessitates an appropriate framework, in which evolving interactions are identified from time-series observations.
The goals of this thesis are to (i) develop a Temporal Information Partitioning Network (TIPNet) framework for understanding the joint variability of network components as characterized by time-series data, and (ii) apply this framework to understand ecohydrologic systems across climate gradients based on flux tower and weather station observations. In the TIPNet framework, nodes in the network are time-series variables, and links are information theoretic measures that quantify multivariate lagged time-dependencies from lagged ""source"" nodes to ""target"" nodes. The strength of this framework is its ability to characterize information flow between variables over short time windows, and further distinguish aspects of unique, redundant, and synergistic dependencies. Redundant information is overlapping information provided by multiple sources to a target, unique information is only provided by a single target, and synergistic information is provided only when two or more sources are known together.
Based on data from three Critical Zone Observatories, we find that network structure shifts according to conditions at sub-daily time scales and constraints imposed by seasonal energy and water availability. TIPNets constructed from 1-minute weather station data reveal shifts in time-scales and levels of uniqueness, synergy, and redundancy between wet and dry conditions. A more complex network of synergistic interactions characterizes several-hour windows when surfaces are wet, and peaks in information flow during the growing season correspond to shifts in precipitation patterns. Networks based on half hourly flux tower data reveal seasonal shifts in the nature of forcing to carbon and heat fluxes from radiation, atmospheric, and soil subsystems. Along two study transects, we attribute variability in heat and carbon fluxes within constraints imposed by energy and moisture availability to joint interactions that are more synergistic in the spring and redundant in the fall.
Finally, we explore the nature of information flow along an elevation gradient from flux towers located along a transect to gauge local versus non-local connectivity. While the strength of shared information between variables at a site reflects local connectivity, shared information between variables at different sites reflects non-local connectivity. Along two elevation transects, we find that information flow between distant sites indicates directional connectivity that is related to dominant weather patterns. At the Southern Sierra CZO in California, non-local information flow is dominantly west to east, corresponding to weather forcing from the Pacific Ocean eastward, while non-local flow has less directionality at Reynolds Creek CZO, where sites are much closer together and there is no dominant weather forcing direction along the transect. The developed framework and applications presented in this thesis reveal the common presence of multivariate process interactions at timescales from minutes to hours, many of which would not be detected using traditional approaches.
For an ecohydrologic system, the complex network of relationships dictates ecosystem resilience to perturbations such as climate change, drought, or human influences. More broadly, the methods and framework developed here contribute toward a holistic understanding of complex systems, and are applicable to a range of studies of evolving networks."Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2017-08-10 without embargo termsThe student, Allison Goodwell, accepted the attached license on 2017-04-19 at 10:44.The student, Allison Goodwell, submitted this Dissertation for approval on 2017-04-19 at 14:32.This Dissertation was approved for publication on 2017-04-20 at 13:53.DSpace SAF Submission Ingestion Package generated from Vireo submission #10892 on 2017-08-10 at 13:42:21Made available in DSpace on 2017-08-10T19:15:27Z (GMT). No. of bitstreams: 4
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Previous issue date: 2017-04-2
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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