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1.
Arch Sex Behav ; 53(6): 2277-2290, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38589743

RESUMEN

Among the multiple controversies surrounding hypersexuality is the important issue of whether it constitutes a univocal construct. Although an initial study supported its homogeneity, more resent research has identified two separate subcomponents-problematic sexuality and sexual drive. The present survey study addressed this issue in a sample that included both in-person tested college students (n = 69) and online respondents (n = 339). A factor analysis of scales attempting to capture the indicators of each subcomponent of hypersexuality yielded two correlated, but separate factors. Whereas Problematic Sexuality (PS) comprised scales measuring sexual compulsivity, using sex as a coping mechanism, and the negative consequences of sexual behavior, Sexual Drive (SD) was defined by frequent sexual activity, preoccupation with sexual fantasies, a predilection for impersonal sexual behavior, and facile sexual arousal. These two subcomponents of hypersexuality were found to covary with different types of impulsivity, further supporting their discrimination and providing external validation for their differentiation. Contrary to a priori hypotheses, however, PS correlated highly with Callous/Manipulative/Risk-Taking as well as with a predicted Affective Instability/Behavioral Disinhibition factor, suggesting that PS may constitute an equifinality of separate developmental trajectories for those high on both subtypes of hypersexuality.


Asunto(s)
Conducta Impulsiva , Conducta Sexual , Humanos , Masculino , Femenino , Conducta Sexual/psicología , Adulto , Encuestas y Cuestionarios , Adolescente , Adulto Joven , Disfunciones Sexuales Psicológicas/psicología , Análisis Factorial , Conducta Compulsiva/psicología , Estudiantes/psicología
2.
Dev Psychopathol ; : 1-17, 2024 Mar 27.
Artículo en Inglés | MEDLINE | ID: mdl-38532735

RESUMEN

BACKGROUND: Employing a developmental psychopathology framework, we tested the utility of the hormesis model in examining the strengthening of children and youth through limited levels of adversity in relation to internalizing and externalizing outcomes within a brain-by-development context. METHODS: Analyzing data from the Adolescent Brain and Cognitive Development study (N = 11,878), we formed latent factors of threat, deprivation, and unpredictability. We examined linear and nonlinear associations between adversity dimensions and youth psychopathology symptoms and how change of resting-state functional connectivity (rsFC) in the default mode network (DMN) from Time 1 to Time 5 moderates these associations. RESULTS: A cubic association was found between threat and youth internalizing problems; low-to-moderate family conflict levels reduced these problems. Deprivation also displayed a cubic relation with youth externalizing problems, with moderate deprivation levels associated with fewer problems. Unpredictability linearly increased both problem types. Change in DMN rsFC significantly moderated the cubic link between threat levels and internalizing problems, with declining DMN rsFC levels from Time 1 to Time 5 facilitating hormesis. Hormetic effects peaked earlier, emphasizing the importance of sensitive periods and developmental timing of outcomes related to earlier experiences. CONCLUSIONS: Strengthening through limited environmental adversity is crucial for developing human resilience. Understanding this process requires considering both linear and nonlinear adversity-psychopathology associations. Testing individual differences by brain and developmental context will inform preventive intervention programming.

3.
Jpn J Nurs Sci ; 21(2): e12577, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38073186

RESUMEN

AIM: This study investigated the ways in which nurses caring for COVID-19 patients during the pandemic's early stages recognized professional growth through their experiences and continued working for several years, as well as the key experiences for identifying professional growth, external factors, and career intentions. METHODS: We used a qualitative research method called the Trajectory Equifinality Model (TEM). The participants were nine nurses caring for COVID-19 patients during the pandemic's early stages and had already recognized professional growth through a series of experiences. We constructed a TEM diagram based on two interviews per participant (in February-March, and July-August 2022). RESULTS: The process by which the participants recognized professional growth through a series of experiences was divided into Phases 1-4. The participants experienced adversity in Phases 1 and 3, and the following professional growth in Phases 2 and 4: gaining confidence as a nurse performing tasks of great social significance by acquiring the ability to fulfill my roles and realizing I could use the skills I had acquired by providing nursing care to COVID-19 patients in other situations, respectively. The key experiences for identifying professional growth as well as the inhibiting and facilitating factors of the process differed depending on the phase. The participants' career intention was wanting to continue to be involved in nursing by utilizing the skills and experience I have accumulated. CONCLUSION: Managers and directors of nursing should provide appropriate support in each phase to help nurses recognize their professional growth during emerging epidemics.


Asunto(s)
COVID-19 , Enfermeras y Enfermeros , Atención de Enfermería , Humanos , Intención , Investigación Cualitativa
4.
Artículo en Inglés | MEDLINE | ID: mdl-37174263

RESUMEN

This study aimed to clarify the longitudinal goal negotiation and collaboration process of achieving activity- and participation-level goals. We conducted a qualitative study using the trajectory equifinality model. Nine occupational therapists with experience in setting and achieving activity- and participation-level goals were recruited and interviewed about their clients. We identified two phases and four pathways in the setting and attainment process for activity- and participation-level goals. Throughout the longitudinal goal-setting process, when the occupational therapist and client had difficulty discussing activity- and participation-level goals, the therapist respected the client's expectations, explained the purpose of occupational therapy in detail, and conducted individual face-to-face interviews. When it was difficult to provide work-based interventions, the occupational therapist made flexible use of functional training, elemental movement training, occupation-based practice, and environmental modifications. The results of this study may assist in supporting clients to improve their activity and participation in home rehabilitation.


Asunto(s)
Objetivos , Terapia Ocupacional , Humanos , Japón , Terapia Ocupacional/métodos , Motivación , Investigación Cualitativa
5.
Multivariate Behav Res ; 58(2): 292-310, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-34596499

RESUMEN

Configurational comparative methods (CCMs) and logic regression methods (LRMs) are two families of exploratory methods that employ very different techniques to analyze data generated by causal structures featuring conjunctural causation and equifinality. Aiming for the same by different means carries a substantive synergy potential, which, however, remains untapped so far because representatives of the two frameworks know little of each other. The purpose of this article is to change that. We first level the field for readers from both backgrounds by providing brief introductions to the basic ideas behind CCMs and LRMs. Then, we carve out the strengths and weaknesses of the two method families by benchmarking their performance when applied to binary data under a variety of different discovery contexts. It turns out that CCMs and LRMs have complementary strengths and weaknesses. This creates various promising avenues for cross-validation.


Asunto(s)
Lógica , Modelos Teóricos , Causalidad , Benchmarking , Análisis de Regresión
6.
New Phytol ; 237(6): 1998-2004, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36308517

RESUMEN

Plant functional traits are powerful ecological tools, but the relationships between plant traits and climate (or environmental variables more broadly) are often remarkably weak. This presents a paradox: Plant traits govern plant interactions with their environment, but the environment does not strongly predict the traits of plants living there. Unpacking this paradox requires differentiating the mechanisms of trait variation and potential confounds of trait-environment relationships at different evolutionary and ecological scales ranging from within species to among communities. It also necessitates a more integrated understanding of physiological and evolutionary equifinality among many traits and plant strategies, and challenges us to understand how supposedly 'functional' traits integrate into a whole-organism phenotype in ways that may be largely orthogonal to environmental tolerances.


Asunto(s)
Hojas de la Planta , Plantas , Hojas de la Planta/genética , Plantas/genética , Evolución Biológica , Fenotipo , Clima
7.
Integr Psychol Behav Sci ; 57(4): 1256-1272, 2023 12.
Artículo en Inglés | MEDLINE | ID: mdl-36522516

RESUMEN

Inclusive education is a process in which schools devise curricula and plan resource allocation to include the diverse group of children in society. Although not many schools promote inclusive education at a school-wide level, there are some schools making efforts toward inclusion in Japan. This study aimed to understand the process of inclusion in a Japanese elementary school by using Trajectory Equifinality Modeling. We conducted a participant observation and focused on Naomi, who was 7 years old and had Down's syndrome. Naomi spent more than 80% of her time in the general education classroom, where she began to refuse to do tasks different from other children. In regard to this, the opinions of the homeroom teacher and the coordinator of these classes were completely different, but their opposing opinions were transformed into complementary ones using time differentiation, and they were able to continue to collaborate toward inclusive education. We found "transductive resolution" as a key to understanding the processes of striving for inclusive education.


Asunto(s)
Síndrome de Down , Niño , Femenino , Humanos , Japón , Instituciones Académicas , Actitud , Curriculum
8.
Dev Psychopathol ; : 1-17, 2022 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-36503558

RESUMEN

Heavy episodic drinking (HED) is a major public health concern, and youth who engage in HED are at increased risk for alcohol-related problems that continue into adulthood. Importantly, there is heterogeneity in the onset and course of adolescent HED, as youth exhibit different trajectories of initiation and progression into heavy drinking. Much of what is known about the etiology of adolescent HED and alcohol-related problems that persist into adulthood comes from studies of predominantly White, middle-class youth. Because alcohol use and related problems vary by race/ethnicity and socioeconomic status, it is unclear whether previous findings are relevant for understanding developmental antecedents and distal consequences of adolescent HED for minoritized individuals. In the current study, we utilize a developmental psychopathology perspective to fill this gap in the literature. Using a racially and economically diverse cohort followed from adolescence well into adulthood, we apply group-based trajectory modeling (GBTM) to identify patterns of involvement in HED from age 14 to 17 years. We then investigate developmental antecedents of GBTM class membership, and alcohol-related distal outcomes in adulthood (∼ age 31 years) associated with GBTM class membership. Results highlight the importance of adolescent alcohol use in predicting future alcohol use in adulthood.

10.
Annu Rev Ecol Evol Syst ; 53(1): 113-136, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-38107485

RESUMEN

Complex statistical methods are continuously developed across the fields of ecology, evolution, and systematics (EES). These fields, however, lack standardized principles for evaluating methods, which has led to high variability in the rigor with which methods are tested, a lack of clarity regarding their limitations, and the potential for misapplication. In this review, we illustrate the common pitfalls of method evaluations in EES, the advantages of testing methods with simulated data, and best practices for method evaluations. We highlight the difference between method evaluation and validation and review how simulations, when appropriately designed, can refine the domain in which a method can be reliably applied. We also discuss the strengths and limitations of different evaluation metrics. The potential for misapplication of methods would be greatly reduced if funding agencies, reviewers, and journals required principled method evaluation.

11.
Gait Posture ; 83: 88-95, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33099136

RESUMEN

BACKGROUND: Persons with lower limb amputation often experience decreased physical capacity, difficulty walking, and increased fall risk. To either prevent or recover from a loss of balance, one must effectively regulate their stepping movements. It is therefore critical to identify how well persons with amputation regulate stepping. Here, we used a multi-objective control framework based on Goal Equivalent Manifolds to identify how persons with transtibial amputation (TTA) regulate lateral stepping while walking without and with lateral perturbations. RESEARCH QUESTION: When walking in destabilizing environments, do otherwise healthy persons with TTA exhibit greater difficulty regulating lateral stepping due to impaired control? Or do they instead continue to use similar strategies to regulate lateral stepping despite their amputation? METHODS: Eight persons with unilateral TTA and thirteen able-bodied (AB) controls walked in a virtual environment under three conditions: no perturbations, laterally oscillating visual field, and laterally oscillating treadmill platform. We analyzed step-to-step time series of step widths and absolute lateral body positions. We computed means, standard deviations and Detrended Fluctuation Analysis scaling exponents for each time series and computed how much participants directly corrected step width and position deviations at each step. We compared our results to computational predictions to identify the underlying causes of our experimental findings. RESULTS: All participants exhibited significantly increased variability, decreased scaling exponents, and tighter direct control when perturbed. Simulations from our stepping regulation models revealed that people responded to the increased variability produced by the imposed perturbations by tightening their control of both step width and lateral position. Participants with TTA exhibited only a few minor differences from AB in lateral stepping regulation, even when subjected to substantially destabilizing lateral perturbations. SIGNIFICANCE: Since control of stepping is intrinsically multi-objective, developing effective interventions to reduce fall risk in persons with amputation will likely require strategies that adopt multi-objective approaches.


Asunto(s)
Amputación Quirúrgica/efectos adversos , Marcha/fisiología , Limitación de la Movilidad , Equilibrio Postural/fisiología , Caminata/fisiología , Adulto , Amputación Quirúrgica/métodos , Femenino , Humanos , Masculino , Adulto Joven
12.
Neurosci Biobehav Rev ; 118: 175-185, 2020 11.
Artículo en Inglés | MEDLINE | ID: mdl-32745477

RESUMEN

Callous-unemotional (CU) traits are implicated in the development of severe and persistent antisocial behavior, and appear to arise from distinct behavioral, temperament, physiological, and neural risk factors to other types of externalizing psychopathology. Although existing etiological models have attempted to characterize specific mechanisms underlying the emergence of CU traits, prior empirical work is plagued by a host of inconsistent results. This inconsistency is particularly apparent in research that has investigated variation in physiological functioning, arousal, and reactivity. In this review, we summarize and evaluate studies that have examined the role of parasympathetic nervous system (PNS) functioning in child psychopathology, including studies of CU traits. We argue that the inclusion of measures of PNS activity can significantly enhance our understanding of the etiology of CU traits, provide clarity to the inconsistent findings of prior studies, and advance mechanistically-targeted interventions and treatments. We conclude the review by providing foundational and testable hypotheses about the role that disrupted PNS functioning could play in multiple pathways to CU traits beginning in infancy and across development.


Asunto(s)
Trastorno de la Conducta , Trastorno de Personalidad Antisocial , Niño , Emociones , Humanos , Sistema Nervioso Parasimpático , Temperamento
13.
Ecol Appl ; 30(7): e02159, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-32365250

RESUMEN

Ecologists are increasingly familiar with Bayesian statistical modeling and its associated Markov chain Monte Carlo (MCMC) methodology to infer about or to discover interesting effects in data. The complexity of ecological data often suggests implementation of (statistical) models with a commensurately rich structure of effects, including crossed or nested (i.e., hierarchical or multi-level) structures of fixed and/or random effects. Yet, our experience suggests that most ecologists are not familiar with subtle but important problems that often arise with such models and with their implementation in popular software. Of foremost consideration for us is the notion of effect identifiability, which generally concerns how well data, models, or implementation approaches inform about, i.e., identify, quantities of interest. In this paper, we focus on implementation pitfalls that potentially misinform subsequent inference, despite otherwise informative data and models. We illustrate the aforementioned issues using random effects regressions on synthetic data. We show how to diagnose identifiability issues and how to remediate these issues with model reparameterization and computational and/or coding practices in popular software, with a focus on JAGS, OpenBUGS, and Stan. We also show how these solutions can be extended to more complex models involving multiple groups of nested, crossed, additive, or multiplicative effects, for models involving random and/or fixed effects. Finally, we provide example code (JAGS/OpenBUGS and Stan) that practitioners can modify and use for their own applications.


Asunto(s)
Modelos Estadísticos , Programas Informáticos , Teorema de Bayes , Cadenas de Markov , Método de Montecarlo
14.
Sensors (Basel) ; 20(4)2020 Feb 24.
Artículo en Inglés | MEDLINE | ID: mdl-32102289

RESUMEN

Passive microwave sensors use a radiative transfer model (RTM) to retrieve soil moisture (SM) using brightness temperatures (TB) at low microwave frequencies. Vegetation optical depth (VOD) is a key input to the RTM. Retrieval algorithms can analytically invert the RTM using dual-polarized TB measurements to retrieve the VOD and SM concurrently. Algorithms in this regard typically use the τ-ω types of models, which consist of two third-order polynomial equations and, thus, can have multiple solutions. Through this work, we find that uncertainty occurs due to the structural indeterminacy that is inherent in all τ-ω types of models in passive microwave SM retrieval algorithms. In the process, a new analytical solution for concurrent VOD and SM retrieval is presented, along with two widely used existing analytical solutions. All three solutions are applied to a fixed framework of RTM to retrieve VOD and SM on a global scale, using X-band Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) TB data. Results indicate that, with structural uncertainty, there ensues a noticeable impact on the VOD and SM retrievals. In an era where the sensitivity of retrieval algorithms is still being researched, we believe the structural indeterminacy of RTM identified here would contribute to uncertainty in the soil moisture retrievals.

15.
Ann Bot ; 126(4): 559-570, 2020 09 14.
Artículo en Inglés | MEDLINE | ID: mdl-32002551

RESUMEN

BACKGROUND AND AIMS: Functional-structural plant (FSP) models provide insights into the complex interactions between plant architecture and underlying developmental mechanisms. However, parameter estimation of FSP models remains challenging. We therefore used pattern-oriented modelling (POM) to test whether parameterization of FSP models can be made more efficient, systematic and powerful. With POM, a set of weak patterns is used to determine uncertain parameter values, instead of measuring them in experiments or observations, which often is infeasible. METHODS: We used an existing FSP model of avocado (Persea americana 'Hass') and tested whether POM parameterization would converge to an existing manual parameterization. The model was run for 10 000 parameter sets and model outputs were compared with verification patterns. Each verification pattern served as a filter for rejecting unrealistic parameter sets. The model was then validated by running it with the surviving parameter sets that passed all filters and then comparing their pooled model outputs with additional validation patterns that were not used for parameterization. KEY RESULTS: POM calibration led to 22 surviving parameter sets. Within these sets, most individual parameters varied over a large range. One of the resulting sets was similar to the manually parameterized set. Using the entire suite of surviving parameter sets, the model successfully predicted all validation patterns. However, two of the surviving parameter sets could not make the model predict all validation patterns. CONCLUSIONS: Our findings suggest strong interactions among model parameters and their corresponding processes, respectively. Using all surviving parameter sets takes these interactions into account fully, thereby improving model performance regarding validation and model output uncertainty. We conclude that POM calibration allows FSP models to be developed in a timely manner without having to rely on field or laboratory experiments, or on cumbersome manual parameterization. POM also increases the predictive power of FSP models.


Asunto(s)
Persea , Calibración , Modelos Estructurales , Incertidumbre
16.
Am J Phys Anthropol ; 169(3): 403-421, 2019 07.
Artículo en Inglés | MEDLINE | ID: mdl-31049941

RESUMEN

OBJECTIVES: Australopithecus anamensis has comparable δ13 Cenamel values to Ardipithecus ramidus, and both have been characterized as C3 feeders in open woodland habitats similar to "savanna" chimps. Unlike Ar. ramidus and "savanna" chimps, A. anamensis shows a derived dentognathic morphology for tough foods and a dental microwear pattern similar to the C3 -C4 -mixed-feeding A. afarensis. Here I test the hypothesis that changing the variables (ε*enamel-diet , δ13 CC3, δ13 CC4 values) used to calculate the percentage of dietary C4 foods (%C4 diet) by 1-2‰ does not make a substantial difference for hominin diet reconstructions [van der Merwe, Masao, & Bamford, 2008, South African Journal of Science 104:153-155]. MATERIALS AND METHODS: I estimate vegetation structures for A. anamensis with pedogenic carbonate and faunal enamel δ13 C values from the Pliocene Omo-Turkana Basin (4.2-3.9 Ma). I recalculate A. anamensis' %C4 diet based on new body size-dependent estimates of the ε*enamel-diet value and alternative δ13 CC3 and δ13 CC4 values. RESULTS: The Pliocene Omo-Turkana Basin shows evidence for dietary resources with a wide range of δ13 C values including canopy-driven 13 C depleted ground C3 foods. Alternative equation variables changed by 1-2‰ yield higher C4 estimates for A. anamensis (15-31%) than previously thought (0-10%). The choice of δ13 CC3 and δ13 CC4 values for estimating %C4 is not a perfunctory task and potentially explains the δ13 C isotopic equifinality of A. anamensis and "savanna" chimps. DISCUSSION: My integrative diet model reconciles the carbon isotopic data with the dentognathic and microwear evidence of A. anamensis' diet and suggests that "savanna" chimps are not proper dietary analogs of A. anamensis. A foraging strategy across heterogeneous habitats of the Pliocene Omo-Turkana Basin incorporating an array of 13 C-depleted and 13 C-enriched C3 foods and a portion of C4 resources may have served as one of the selective pressures for A. anamensis, the earliest habitual biped [van der Merwe et al., 2008, South African Journal of Science 104:153-155].


Asunto(s)
Isótopos de Carbono/análisis , Dieta/historia , Hominidae/fisiología , Animales , Antropología Física , Esmalte Dental/química , Ecosistema , Fósiles , Historia Antigua
17.
Behav Processes ; 161: 129-138, 2019 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29369783

RESUMEN

Cultural systems exhibit equifinal behavior - a single final state may be arrived at via different mechanisms and/or from different initial states. Potential for equifinality exists in all empirical studies of cultural transmission including controlled experiments, observational field research, and computational simulations. Acknowledging and anticipating the existence of equifinality is important in empirical studies of social learning and cultural evolution; it helps us understand the limitations of analytical approaches and can improve our ability to predict the dynamics of cultural transmission. Here, I illustrate and discuss examples of equifinality in studies of social learning, and how certain experimental designs might be prone to it. I then review examples of equifinality discussed in the social learning literature, namely the use of s-shaped diffusion curves to discern individual from social learning and operational definitions and analytical approaches used in studies of conformist transmission. While equifinality exists to some extent in all studies of social learning, I make suggestions for how to address instances of it, with an emphasis on using data simulation and methodological verification alongside modern statistical approaches that emphasize prediction and model comparison. In cases where evaluated learning mechanisms are equifinal due to non-methodological factors, I suggest that this is not always a problem if it helps us predict cultural change. In some cases, equifinal learning mechanisms might offer insight into how both individual learning, social learning strategies and other endogenous social factors might by important in structuring cultural dynamics and within- and between-group heterogeneity.


Asunto(s)
Evolución Cultural , Aprendizaje Social , Humanos , Aprendizaje
18.
Compr Psychiatry ; 87: 143-152, 2018 11.
Artículo en Inglés | MEDLINE | ID: mdl-30415196

RESUMEN

In the past 35 years, developmental psychopathology has grown into a flourishing discipline that shares a scientific agenda with contemporary psychiatry. In this editorial, which introduces the special issue, we describe the history of developmental psychopathology, including core principles that bridge allied disciplines. These include (1) emphasis on interdisciplinary research, (2) elucidation of multicausal pathways to seemingly single disorders (phenocopies), (3) description of divergent multifinal outcomes from common etiological start points (pathoplasticity), and (4) research conducted across multiple levels of analysis spanning genes to environments. Next, we discuss neurodevelopmental models of psychopathology, and provide selected examples. We emphasize differential neuromaturation of subcortical and cortical neural networks and connectivity, and how both acute and protracted environmental insults can compromise neural structure and function. To date, developmental psychopathology has placed greater emphasis than psychiatry on neuromaturational models of mental illness. However, this gap is closing rapidly as advances in technology render etiopathophysiologies of psychopathology more interrogable. We end with suggestions for future interdisciplinary research, including the need to evaluate measurement invariance across development, and to construct more valid assessment methods where indicated.


Asunto(s)
Psiquiatría/tendencias , Psicopatología/tendencias , Niño , Desarrollo Infantil , Predicción , Humanos , Trastornos Mentales
19.
Geosciences (Basel) ; 8(4): 137, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30147946

RESUMEN

Modelling gully erosion in urban areas is challenging due to difficulties with equifinality and parameter identification, which complicates quantification of management impacts on runoff and sediment production. We calibrated a model (AnnAGNPS) of an ephemeral gully network that formed on unpaved roads following a storm event in an urban watershed (0.2 km2) in Tijuana, Mexico. Latin hypercube sampling was used to create 500 parameter ensembles. Modelled sediment load was most sensitive to the Soil Conservation Service (SCS) curve number, tillage depth (Td), and critical shear stress (τc). Twenty-one parameter ensembles gave acceptable error (behavioural models), though changes in parameters governing runoff generation (SCS curve number, Manning's n) were compensated by changes in parameters describing soil properties (TD, τc, resulting in uncertainty in the optimal parameter values. The most suitable parameter combinations or "behavioural models" were used to evaluate uncertainty under management scenarios. Paving the roads increased runoff by 146-227%, increased peak discharge by 178-575%, and decreased sediment load by 90-94% depending on the ensemble. The method can be used in other watersheds to simulate runoff and gully erosion, to quantify the uncertainty of model-estimated impacts of management activities on runoff and erosion, and to suggest critical field measurements to reduce uncertainties in complex urban environments.

20.
J Biomech ; 76: 144-151, 2018 07 25.
Artículo en Inglés | MEDLINE | ID: mdl-29914740

RESUMEN

As humans walk or run, external (environmental) and internal (physiological) disturbances induce variability. How humans regulate this variability from stride-to-stride can be critical to maintaining balance. One cannot infer what is "controlled" based on analyses of variability alone. Assessing control requires quantifying how deviations are corrected across consecutive movements. Here, we assessed walking and running, each at two speeds. We hypothesized differences in speed would drive changes in variability, while adopting different gaits would drive changes in how people regulated stepping. Ten healthy adults walked/ran on a treadmill under four conditions: walk or run at comfortable speed, and walk or run at their predicted walk-to-run transition speed. Time series of relevant stride parameters were analyzed to quantify variability and stride-to-stride error-correction dynamics within a Goal-Equivalent Manifold (GEM) framework. In all conditions, participants' stride-to-stride control respected a constant-speed GEM strategy. At each consecutively faster speed, variability tangent to the GEM increased (p ≤ 0.031), while variability perpendicular to the GEM decreased (p ≤ 0.044). There were no differences (p ≥ 0.999) between gaits at the transition speed. Differences in speed determined how stepping variability was structured, independent of gait, confirming our first hypothesis. For running versus walking, measures of GEM-relevant statistical persistence were significantly less (p ≤ 0.004), but showed minimal-to-no speed differences (0.069 ≤ p ≤ 0.718). When running, people corrected deviations both more quickly and more directly, each indicating tighter control. Thus, differences in gait determined how stride-to-stride fluctuations were regulated, independent of speed, confirming our second hypothesis.


Asunto(s)
Marcha/fisiología , Equilibrio Postural , Carrera/fisiología , Adulto , Humanos
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