Relevant bibliographies by topics / Movement variabiliity

Academic literature on the topic 'Movement variabiliity'

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Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Movement variabiliity"

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van Beers, Robert J., Patrick Haggard, and Daniel M. Wolpert. "The Role of Execution Noise in Movement Variability." Journal of Neurophysiology 91, no. 2 (February 2004): 1050–63. http://dx.doi.org/10.1152/jn.00652.2003.

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The origin of variability in goal-directed movements is not well understood. Variability can originate from several neural processes such as target localization, movement planning, and movement execution. Here we examine variability resulting from noise in movement execution. In several experiments, subjects moved their unseen hand to visual targets, under conditions which were designed to minimize the variability expected from localization and planning processes. We tested short movements in 32 directions in a center-out reaching task. The variability in the movement endpoints and in the initial movement direction varied systematically with the movement direction, with some directions having up to twice the variability of others. In a second experiment we tested four movements in the same direction but with different extents. Here, the longer movements were systematically curved, and the endpoint ellipses were not aligned with the straight line between starting and end position, but they were roughly aligned with the last part of the trajectory. We show that the variability observed in these experiments cannot be explained by planning noise but is well explained by noise in movement execution. A combination of both signal-dependent and signal-independent noise in the amplitude of the motor commands and temporal noise in their duration can explain the observed variability. Our results suggest that, in general, execution noise accounts for at least a large proportion of movement variability.
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Oostwoud Wijdenes, Leonie, Richard B. Ivry, and Paul M. Bays. "Competition between movement plans increases motor variability: evidence of a shared resource for movement planning." Journal of Neurophysiology 116, no. 3 (September 1, 2016): 1295–303. http://dx.doi.org/10.1152/jn.00113.2016.

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Do movement plans, like representations in working memory, share a limited pool of resources? If so, the precision with which each individual movement plan is specified should decrease as the total number of movement plans increases. To explore this, human participants made speeded reaching movements toward visual targets. We examined if preparing one movement resulted in less variability than preparing two movements. The number of planned movements was manipulated in a delayed response cueing procedure that limited planning to a single target ( experiment 1) or hand ( experiment 2) or required planning of movements toward two targets (or with two hands). For both experiments, initial movement direction variability was higher in the two-plan condition than in the one-plan condition, demonstrating a cost associated with planning multiple movements, consistent with the limited resource hypothesis. In experiment 3, we showed that the advantage in initial variability of preparing a single movement was present only when the trajectory could be fully specified. This indicates that the difference in variability between one and two plans reflects the specification of full motor plans, not a general preparedness to move. The precision cost related to concurrent plans represents a novel constraint on motor preparation, indicating that multiple movements cannot be planned independently, even if they involve different limbs.
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Kawano, Yui, and Mayumi Kuno-Mizumura. "Intra- and Inter-individual Movement Variability of Upper Limb Movements of Ballet Dancers." Medical Problems of Performing Artists 34, no. 3 (September 1, 2019): 132–40. http://dx.doi.org/10.21091/mppa.2019.3023.

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OBJECTIVE: This study examined intra- and inter-individual variability in upper limb movements of ballet dancers when performing flapping swan-wing movements, and it assessed differences in joint angles of upper limbs between dancers of different skill levels. METHODS: 23 female ballet dancers (3 professional, 6 advanced, and 14 intermediate dancers) and 21 age-matched females without previous dance experience participated in this study. Thirty-three reflective markers were attached to each participant’s trunk and upper limbs, and the flapping upper limb motions from Swan Lake were subsequently captured with eight optical cameras. Peak values of upper limb joint angles (shoulder, elbow, and wrist joint) were obtained, and intra- and inter-individual movement variability of each joint angle were compared between groups. RESULTS: In joint angles of the shoulder, elbow, and wrist, there were few differences among professional, advanced, and intermediate groups. The intra-individual movement variability in upward arm movements was significantly larger for professional and control groups than for advanced and intermediate groups, while in downward arm movement, variability became significantly smaller as technical level increased. Moreover, inter-individual movement variability was larger in the upward arm movement as technical level increased, and smaller in the downward arm movement for the professional group. The results suggested that the upward arm movements reflect dancers’ individual expression, while the downward arm movements reflect their technical competence at this swan-like movement. CONCLUSION: The complicated swan-like movements performed by skilled dancers in this study indicate that they execute expressive and technical components in sequence.
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Jaric, Slobodan, Charli Tortoza, Ismael F. C. Fatarelli, and Gil L. Almeida. "Effects of Direction and Curvature on Variable Error Pattern of Reaching Movements." Motor Control 3, no. 4 (October 1999): 414–23. http://dx.doi.org/10.1123/mcj.3.4.414.

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A number of studies have analyzed various indices of the final position variability in order to provide insight into different levels of neuromotor processing during reaching movements. Yet the possible effects of movement kinematics on variability have often been neglected. The present study was designed to test the effects of movement direction and curvature on the pattern of movement variable errors. Subjects performed series of reaching movements over the same distance and into the same target. However, due either to changes in starting position or to applied obstacles, the movements were performed in different directions or along the trajectories of different curvatures. The pattern of movement variable errors was assessed by means of the principal component analysis applied on the 2-D scatter of movement final positions. The orientation of these ellipses demonstrated changes associated with changes in both movement direction and curvature. However, neither movement direction nor movement curvature affected movement variable errors assessed by area of the ellipses. Therefore it was concluded that the end-point variability depends partly, but not exclusively, on movement kinematics.
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Apker, Gregory A., Timothy K. Darling, and Christopher A. Buneo. "Interacting Noise Sources Shape Patterns of Arm Movement Variability in Three-Dimensional Space." Journal of Neurophysiology 104, no. 5 (November 2010): 2654–66. http://dx.doi.org/10.1152/jn.00590.2010.

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Reaching movements are subject to noise in both the planning and execution phases of movement production. The interaction of these noise sources during natural movements is not well understood, despite its importance for understanding movement variability in neurologically intact and impaired individuals. Here we examined the interaction of planning and execution related noise during the production of unconstrained reaching movements. Subjects performed sequences of two movements to targets arranged in three vertical planes separated in depth. The starting position for each sequence was also varied in depth with the target plane; thus required movement sequences were largely contained within the vertical plane of the targets. Each final target in a sequence was approached from two different directions, and these movements were made with or without visual feedback of the moving hand. These combined aspects of the design allowed us to probe the interaction of execution and planning related noise with respect to reach endpoint variability. In agreement with previous studies, we found that reach endpoint distributions were highly anisotropic. The principal axes of movement variability were largely aligned with the depth axis, i.e., the axis along which visual planning related noise would be expected to dominate, and were not generally well aligned with the direction of the movement vector. Our results suggest that visual planning–related noise plays a dominant role in determining anisotropic patterns of endpoint variability in three-dimensional space, with execution noise adding to this variability in a movement direction-dependent manner.
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Berret, Bastien, Adrien Conessa, Nicolas Schweighofer, and Etienne Burdet. "Stochastic optimal feedforward-feedback control determines timing and variability of arm movements with or without vision." PLOS Computational Biology 17, no. 6 (June 11, 2021): e1009047. http://dx.doi.org/10.1371/journal.pcbi.1009047.

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Human movements with or without vision exhibit timing (i.e. speed and duration) and variability characteristics which are not well captured by existing computational models. Here, we introduce a stochastic optimal feedforward-feedback control (SFFC) model that can predict the nominal timing and trial-by-trial variability of self-paced arm reaching movements carried out with or without online visual feedback of the hand. In SFFC, movement timing results from the minimization of the intrinsic factors of effort and variance due to constant and signal-dependent motor noise, and movement variability depends on the integration of visual feedback. Reaching arm movements data are used to examine the effect of online vision on movement timing and variability, and test the model. This modelling suggests that the central nervous system predicts the effects of sensorimotor noise to generate an optimal feedforward motor command, and triggers optimal feedback corrections to task-related errors based on the available limb state estimate.
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Stalder, D., FM van Beest, S. Sveegaard, R. Dietz, J. Teilmann, and J. Nabe-Nielsen. "Influence of environmental variability on harbour porpoise movement." Marine Ecology Progress Series 648 (August 27, 2020): 207–19. http://dx.doi.org/10.3354/meps13412.

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The harbour porpoise Phocoena phocoena is a small marine predator with a high conservation status in Europe and the USA. To protect the species effectively, it is crucial to understand its movement patterns and how the distribution of intensively used foraging areas can be predicted from environmental conditions. Here, we investigated the influence of both static and dynamic environmental conditions on large-scale harbour porpoise movements in the North Sea. We used long-term movement data from 57 individuals tracked during 1999-2017 in a state-space model to estimate the underlying behavioural states, i.e. whether animals used area-restricted or directed movements. Subsequently, we assessed whether the probability of using area-restricted movements was related to environmental conditions using a generalized linear mixed model. Harbour porpoises were more likely to use area-restricted movements in areas with low salinity levels, relatively high chlorophyll a concentrations and low current velocity, and in areas with steep bottom slopes, suggesting that such areas are important foraging grounds for porpoises. Our study identifies environmental parameters of relevance for predicting harbour porpoise foraging hot spots over space and time in a dynamic system. The study illustrates how movement patterns and data on environmental conditions can be combined, which is valuable to the conservation of marine mammals.
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Chu, Virginia Way Tong, Dagmar Sternad, and Terence David Sanger. "Healthy and dystonic children compensate for changes in motor variability." Journal of Neurophysiology 109, no. 8 (April 15, 2013): 2169–78. http://dx.doi.org/10.1152/jn.00908.2012.

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Successful reaching requires that we plan movements to compensate for variability in motor output. Previous studies have shown that healthy adults optimally incorporate estimates of motor variability when planning a pointing task. Children with dystonia have increased variability compared with healthy children. It is not known whether they are able to compensate appropriately for the increased variability and whether this compensation leads to changes in reaching behavior. We examined healthy children and those with increased motor variability due to secondary dystonia. Using a simple virtual display, children performed a motor task where the variability of their movements was manipulated. Results showed that both subject groups changed their movement strategies in response to changes in the level of perceived motor variability. Both groups changed their strategy in a way that improved performance relative to the perceived motor variability. Importantly, dystonic children faced with decreased motor variability adapted their movement strategy to perform better and more similarly to healthy children. These findings show that both healthy and dystonic children are able to respond to changes in motor variability and alter their movement strategies.
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Laboissière, Rafael, Daniel R. Lametti, and David J. Ostry. "Impedance Control and Its Relation to Precision in Orofacial Movement." Journal of Neurophysiology 102, no. 1 (July 2009): 523–31. http://dx.doi.org/10.1152/jn.90948.2008.

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Speech production involves some of the most precise and finely timed patterns of human movement. Here, in the context of jaw movement in speech, we show that spatial precision in speech production is systematically associated with the regulation of impedance and in particular, with jaw stiffness—a measure of resistance to displacement. We estimated stiffness and also variability during movement using a robotic device to apply brief force pulses to the jaw. Estimates of stiffness were obtained using the perturbed position and force trajectory and an estimate of what the trajectory would be in the absence of load. We estimated this “reference trajectory” using a new technique based on Fourier analysis. A moving-average (MA) procedure was used to estimate stiffness by modeling restoring force as the moving average of previous jaw displacements. The stiffness matrix was obtained from the steady state of the MA model. We applied this technique to data from 31 subjects whose jaw movements were perturbed during speech utterances and kinematically matched nonspeech movements. We observed systematic differences in stiffness over the course of jaw-lowering and jaw-raising movements that were correlated with measures of kinematic variability. Jaw stiffness was high and variability was low early and late in the movement when the jaw was elevated. Stiffness was low and variability was high in the middle of movement when the jaw was lowered. Similar patterns were observed for speech and nonspeech conditions. The systematic relationship between stiffness and variability points to the idea that stiffness regulation is integral to the control of orofacial movement variability.
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Abrams, Richard A., Jay Pratt, and Alison L. Chasteen. "Aging and movement: Variability of force pulses for saccadic eye movements." Psychology and Aging 13, no. 3 (1998): 387–95. http://dx.doi.org/10.1037/0882-7974.13.3.387.

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Dissertations / Theses on the topic "Movement variabiliity"

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Sim, Luke. "Explicit Perceptual Estimation of Movement Variability." Cleveland State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=csu1560332998736569.

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Langdown, Benjamin Louis Gerard Raymond. "Movement variability and strength and conditioning in golf." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6164/.

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The detrimental nature of movement variability has recently been reconsidered with suggestions that it has a functional role to play in performance. Movements in golf can be attributed to the organismic, task and environmental constraints from which they emerge with these swing movements affecting shot outcomes. A three-dimensional analysis of address position variability revealed that higher skilled golfers present reduced alignment variability in angular relationships between the shoulders and stance compared to less skilled counterparts. Whilst there were no group differences in impact variability, both points in the swing displayed reducing variability from proximal to distal aspects of the kinetic chain. With the popularity of strength and conditioning growing within the golfing world it has become important for coaches to be able to assess golfers’ physical constraints. Two-dimensional analysis, representative of that used in coaching environments, assessed the relationship between the overhead squat and deterioration of posture in the golf swing. Results showed small but significant relationships between this test and golf swing postural kinematics. An 8-week intervention to address overhead squat physical constraints resulted in no change in 3D swing kinematics. Strength and conditioning as a stand-alone intervention provides no benefits to postural kinematics suggesting the need for coaching.
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Dey, Abhishek. "VARIABILITY AND LOCATION OF MOVEMENT ENDPOINT DISTRIBUTIONS: THE INFLUENCE OF INSTRUCTIONS FOR MOVEMENT SPEED AND ACCURACY." Cleveland State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=csu1463074085.

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Robins, Matthew T. "Constraints on movement variability during a discrete multi-articular action." Thesis, Sheffield Hallam University, 2013. http://shura.shu.ac.uk/7602/.

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The aim of this programme of work was to examine how the manipulation of organismic and task constraints affected movement variability during a basketball shooting task. The specific constraints that were manipulated included task expertise, state anxiety and dioptric blur (organismic constraints), and, shooting distance and attentional focus instruction (task constraints). The aim of Study 1 was to investigate the effect of shooting distance and task expertise on movement variability. Task expertise was characterised by decreased coordination variability and heightened compensatory variability between wrist, elbow and shoulder joints. However, no significant difference was found in joint angle variability at release as a function of task expertise. There was no significant change in movement variability with shooting distance, a finding that was consistent across all expertise groups. In Study 2, the aims were to examine the effect of induced dioptric blur on shooting performance and movement variability during basketball free-throw shooting, and, to ascertain whether task expertise plays a mediating role in the capacity to stabilise performance against impaired visual information. Significant improvements in shooting performance were noted with the introduction of moderate visual blur (+1.00 and +2.00 D). This performance change was evident in both expert and novice performers. Only with the onset of substantial dioptric blur (+3.00 D), equivalent to the legal blindness limit, was there a significant decrease in coordination variability. Despite the change in coordination variability at +3.00 D, there was no significant difference in shooting performance when compared to the baseline condition. The aims of Study 3 were to examine the effect of elevated anxiety on shooting performance and movement variability and, again, to determine whether task expertise plays a mediating role in stabilising performance and movement kinematics against perturbation from emotional fluctuations. Commensurate with the results of Study 2, both expert and novice performers were able to stabilise performance and movement kinematics, this time with elevated anxiety. Stabilisation was achieved through the allocation of additional attentional resources to the task. Study 4, had two aims. The first was to examine the interactive effects of practice and focus of attention on both performance and learning of an accuracy-based, discrete multi-articular action. The second was to identify potential focus-dependent changes on joint kinematics, intra-limb coordination and coordination variability. Support was found for the role of an external focus of attention on shooting performance during both acquisition and retention. However, there was evidence to suggest that internal focus instruction could play a pivotal role in shaping emerging patterns of intra-limb coordination and channelling the learners‟ search towards a smaller range of kinematic solutions within the perceptual-motor workspace. Collectively, this programme of work consistently highlighted the fundamental role that constraints play in governing shooting performance, movement variability and, more broadly, perceptual-motor organisation. For instance, task expertise was characterised by decreased coordination variability and heightened compensatory control. However, in light of the data pertaining to joint angle variability at release, general assumptions about expertise-variability relations cannot be made and should be viewed with caution. In addition, there is strong evidence to suggest that adaptation to constraints is, perhaps, a universal human response, and consequently not mediated by task expertise. Further research is needed to fully elucidate this proposition.
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Soangra, Rahul. "Understanding Variability in Older adults using Inertial Sensors." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/49248.

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Falls are the most frequent cause of unintentional injuries among older adults; afflicting 30 percent of persons aged 65 and older and more than 50 percent of persons aged 85 and older. There is a serious need for strategies to prevent falls in elderly individuals, but an important challenge in fall prevention is the paucity of objective evidence regarding the mechanisms that lead directly to falls. There exists no mechanisms about how to predict and manage elderly falls, which has multifactorial risk factors associated with its occurrence in the elderly. As the U.S. population continues to age, both the number of falls as well as the cost of treatment of fall injuries will continue to grow. Decades of research in fall prevention has not led to a decrease in the fall incidence; thus new strategies need to be introduced to understand and prevent falls. Aging reduces the adaptability of various physical and environmental stressors that hinder stability and balance maintenance and may therefore result in a fall. Movement variability in an individual's task performance can be used to assess the limitations of the movement control system. Maintaining variation in movement engenders flexible and adaptable modalities for elderly individuals to prevent falls in an unpredictable and ever changing external environment. Conversely, excessive variability of movement may drive the control system closer to its stability limits during balance and walking tasks. Accordingly, inertial sensors are an emerging wearable technology that can facilitate noninvasive monitoring of fall prone individuals in clinical settings. This research examined the potential of inertial sensors for use in clinical settings, and evaluated their effectiveness in comparison to mature laboratory systems (i.e., force platform and camera system). Study findings showed a relationship between movement variability and fall risk among healthy young and older adults. Further, the outcomes of this work translates to the clinical environment to better understand the health status (leading to frailty) of cardiac patients; reflected by the underlying adaptability of the control system, but requires further improvements if to be used as robust clinical tool. This research provides the groundwork for rapid clinical assessments in which its validity and robustness should be investigated in future efforts.
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Collins, John Philip. "Deconstructing adsorption variability : the prediction of spatial uncertainty in pollutant movement." Thesis, Durham University, 2008. http://etheses.dur.ac.uk/2218/.

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Land pressures today and government policy-requires previously developed, 'brownfield' land to be brought back into beneficial use. The nature of these sites means that they may have been subject to some form of contamination from previous uses. The risk any pollutant has to human health and the environment must be assessed and, if deemed unacceptable, remediation must be undertaken. Risk assessment may be carried out utilising generic values for contaminant properties that can give misleading results. This thesis describes the effort to further assess the controls on adsorption of organic pollutants and its spatial variability. Spatial sampling of two brownfield sites was undertaken with generic soil parameters being measured. To better describe soil organic matter, organic extracts were prepared from soils, allowing NMR spectra to be collected. The collected soil dataset is analysed to discern any correlations between soil parameters. The nature of the organic pollutants used in this study (benzene, phenol, p-xylene and p-cresol) is described using calculated molecular descriptors. The variation in experimental adsorption results, provided by Sheffield University, were then statistically analysed using soil measures as predictors and then also adding molecular descriptors to the analysis. The percentage of black carbon may also have an influence on adsorption and so this was also measured and added to the list of predictors available for inclusion in stepwise regression. Results show that adsorption of these organic compounds can be partially described using the measured soil parameters. Molecular descriptors such as a molecule's surface area can also be used to predict adsorption. The percentage black carbon was an important predictor in only one instance for p-xylene adsorption. Soil parameters were also shown to be predicted by other soil variables from the dataset, giving good results that were improved upon by transforming all parameters to normality.
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Vidal, Anthony D. "Effects of attentional focus cues on movement coordination and coordination variability." Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10096061.

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The purpose of this study was to examine the effects of FOA cues on movement coordination of the lower extremity during a standing long jump. A modified vector coding analysis of hip/knee and ankle/knee coordination was used to evaluate the influence of FOA cues on coordination patterns and coordination variability. Results indicated no main effect of coordination patterns between FOA conditions for ankle/knee coordination F(1,19) = 0.43, p = 0.52 or coordination variability F(1,19) = 0.00, p = 0.98 and no main effect of hip/knee coordination patterns F(1,19) = 2.48, p = 0.13 or coordination variability F(1,19) = 5.0, p = 0.49. Participants did jump significantly further under and external FOA (2.27 ± .38m) than the internal FOA (2.16 ± .37m, p = 0.035). It is possible that manipulation of arm swing coordination or landing strategies are influencing the changes in jump distances between FOA conditions.

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Lametti, Daniel R. "On the control of movement variability through the regulation of limb impedance." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101860.

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Humans routinely make movements to targets that have different accuracy requirements in different directions. Examples extend from everyday occurrences such as grasping the handle of a coffee cup to the more refined instance of a surgeon positioning a scalpel. The attainment of accuracy in situations such as these might rest upon the nervous system's capacity to regulate the limb's resistance to displacement, or impedance. To test this idea, subjects made movements from random starting locations to targets that had shape dependant accuracy requirements. A robotic device was used to assess both limb impedance and patterns of movement variability just as the subject reached the target. Impedance was seen to increase in directions where required accuracy was high. Furthermore, independent of target shape patterns of limb stiffness were seen to predict spatial patterns of movement variability. The nervous system was thus seen to modulate limb impedance in wholly predictable environments to shape movement variability and achieve reaching accuracy.
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Threlfall, J. L. "Sediment source and discharge variability in a small subarctic nival catchment." Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373575.

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Taylor, Paul Geoffrey. "Quantifying the functional role of discrete movement variability: Links to adaptation and learning." Thesis, Australian Catholic University, 2016. https://acuresearchbank.acu.edu.au/download/8e0b296509df6f9f48db9492f39d38c680ddcdb87c3446055b5a993dfd8361e0/3760378/Taylor_2016_Quantifying_the_functional_role_of_discrete.pdf.

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Introduction: Movement variability can be defined as the variance in human movement from one trial or cycle to the next, often when attempting to maintain dynamic equilibrium (in the case of continuous skills) or achieve consistent movement outcome (for discrete skills). Some theoretical perspectives of motor control consider movement variability to be deleterious. However, the dynamical systems perspective proposes beneficial and functional roles for movement variability. Within this view variability has developed as an independent theme of research that has gained momentum over the past 25 years, attracting focus from various sub-disciplines within the field with a major contribution from sports biomechanics. The previous research within the field of movement variability has proposed that these functional roles include reducing the risk of injury, enabling coordination change and facilitating adaptation to varying task or environmental constraints. This thesis is primarily constituted of four sequential studies designed to further the method-related approach to, and theoretical understanding of, the interaction between variability in discrete movement and adaptation.
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Books on the topic "Movement variabiliity"

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Stergiou, Nicholas. Nonlinear Analysis for Human Movement Variability. Edited by Nicholas Stergiou. Boca Raton : Taylor & Francis, Taylor & Francis, a CRC title, part of the: CRC Press, 2018. http://dx.doi.org/10.1201/9781315370651.

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Persson, Torsten. Exchange rate variability and asset trade. Cambridge, MA: National Bureau of Economic Research, 1989.

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Doyle, Brian M. Breaks in the variability and co-movement of G-7 economic growth. Washington, D.C: Federal Reserve Board, 2003.

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Anderson, S. H. Field variability of atrazine leaching under no-till management. St. Joseph, MI: American Society of Agricultural Engineers, 1988.

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Davids, Keith, Simon Bennett, and Karl Newell, eds. Movement System Variability. Human Kinetics, 2006. http://dx.doi.org/10.5040/9781492596851.

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(Editor), Keith Davis, Simon Bennett (Editor), and Karl M. Newell (Editor), eds. Movement System Variability. Human Kinetics Publishers, 2005.

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Stergiou, Nicholas. Nonlinear Analysis for Human Movement Variability. Taylor & Francis Group, 2018.

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Stergiou, Nicholas. Nonlinear Analysis for Human Movement Variability. Taylor & Francis Group, 2018.

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Nonlinear Analysis for Human Movement Variability. Taylor & Francis Group, 2016.

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Stergiou, Nicholas. Nonlinear Analysis for Human Movement Variability. CRC Press, 2016. http://dx.doi.org/10.1201/b19571.

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Book chapters on the topic "Movement variabiliity"

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Böning, Dieter, Michael I. Lindinger, Damian M. Bailey, Istvan Berczi, Kameljit Kalsi, José González-Alonso, David J. Dyck, et al. "Adaptive Movement Variability." In Encyclopedia of Exercise Medicine in Health and Disease, 17. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-540-29807-6_2023.

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McCamley, John, and Steven J. Harrison. "Introduction." In Nonlinear Analysis for Human Movement Variability, 1–28. Boca Raton : Taylor & Francis, Taylor & Francis, a CRC title, part of the: CRC Press, 2018. http://dx.doi.org/10.1201/9781315370651-1.

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Myers, Sara A. "Time Series." In Nonlinear Analysis for Human Movement Variability, 29–53. Boca Raton : Taylor & Francis, Taylor & Francis, a CRC title, part of the: CRC Press, 2018. http://dx.doi.org/10.1201/9781315370651-2.

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Wurdeman, Shane R. "State-Space Reconstruction." In Nonlinear Analysis for Human Movement Variability, 55–82. Boca Raton : Taylor & Francis, Taylor & Francis, a CRC title, part of the: CRC Press, 2018. http://dx.doi.org/10.1201/9781315370651-3.

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Wurdeman, Shane R. "Lyapunov Exponent." In Nonlinear Analysis for Human Movement Variability, 83–110. Boca Raton : Taylor & Francis, Taylor & Francis, a CRC title, part of the: CRC Press, 2018. http://dx.doi.org/10.1201/9781315370651-4.

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Myers, Sara A. "Surrogation." In Nonlinear Analysis for Human Movement Variability, 111–71. Boca Raton : Taylor & Francis, Taylor & Francis, a CRC title, part of the: CRC Press, 2018. http://dx.doi.org/10.1201/9781315370651-5.

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Yentes, Jennifer M. "Entropy." In Nonlinear Analysis for Human Movement Variability, 173–260. Boca Raton : Taylor & Francis, Taylor & Francis, a CRC title, part of the: CRC Press, 2018. http://dx.doi.org/10.1201/9781315370651-6.

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McGrath, Denise. "Fractals." In Nonlinear Analysis for Human Movement Variability, 261–300. Boca Raton : Taylor & Francis, Taylor & Francis, a CRC title, part of the: CRC Press, 2018. http://dx.doi.org/10.1201/9781315370651-7.

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Hunt, Nathaniel H. "Autocorrelation Function, Mutual Information, and Correlation Dimension." In Nonlinear Analysis for Human Movement Variability, 301–41. Boca Raton : Taylor & Francis, Taylor & Francis, a CRC title, part of the: CRC Press, 2018. http://dx.doi.org/10.1201/9781315370651-8.

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Kyvelidou, Anastasia, and Leslie M. Decker. "Case Studies." In Nonlinear Analysis for Human Movement Variability, 343–88. Boca Raton : Taylor & Francis, Taylor & Francis, a CRC title, part of the: CRC Press, 2018. http://dx.doi.org/10.1201/9781315370651-9.

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Conference papers on the topic "Movement variabiliity"

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Fariza, I. N., Sh-Hussain Salleh, and I. Kamarulafizam. "EXERCISE TRACKING USING HEART RATE VARIABILITY (HRV)." In Movement, Health and Exercise 2014 Conference. Universiti Malaysia Pahang, 2014. http://dx.doi.org/10.15282/mohe.2014.hps.022.

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Celik, Ozkan, and Marcia K. O'Malley. "A neuromuscular elbow model for analysis of force and movement variability in slow movements." In 2011 33rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE, 2011. http://dx.doi.org/10.1109/iembs.2011.6092038.

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F. Lin, Ray, Yi-Chien Tsai, Chi-Yu Huang, and Min-Hsin Lin. "An Application of Ballistic Movement Method for Evaluating the Effects of Movement Direction Using a Standard Mouse." In Applied Human Factors and Ergonomics Conference (2022). AHFE International, 2022. http://dx.doi.org/10.54941/ahfe1001268.

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Most studies on the effect of movement direction utilized Fitts’ law; however, the use of Fitts’ law has a limitation of discriminating the extent to which properties of speed and accuracy contribute to the aiming movement time. Hence, this study aimed at utilizing the two ballistic movement models to separately assess speed and accuracy. Four participants performed ballistic movements with a standard computer mouse in eight radial directions. The measured movement time and two axes of end-point variability were analyzed using the two ballistic movement models. The results showed that two ballistic movement models accounted well for the measured data in various movement directions, and movement direction had certain effects on movement time, aiming-constant error, and aiming-variable error. Movements took the shortest times in the directions of 0° and 180°. Participants aimed targets with a counterclockwise angle when moving toward 90°, 135°, 180°, and 225°, and with a clockwise angle when moving toward 270°, 315°, 0°, and 45°. Aiming-variable errors were relatively smaller along cross axes, compared to those along diagonal axes. Ballistic movement models, compared to Fitts’ law, provided individual performance information of “speed” and “accuracy”, helping provide detail information for HCI designs.
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Kalampratsidou, Vilelmini, and Elizabeth B. Torres. "Sonification of heart rate variability can entrain bodies in motion." In MOCO '20: 7th International Conference on Movement and Computing. New York, NY, USA: ACM, 2020. http://dx.doi.org/10.1145/3401956.3404186.

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Fraser, Alex M., and Smitha D. Koduru. "Effect of Soil Variability on Strain Demand Associated With Moving Slopes." In 2016 11th International Pipeline Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/ipc2016-64432.

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Assessment of strain demand is a critical component in strain-based design. The strain demand associated with moving slopes is influenced by a number of factors related to the properties of the pipeline, the surrounding soil, and the general slope characteristics. Available empirical models for assessing strain demand are limited to special cases of slope movements, and detailed finite element analyses are often performed in order to accurately assess the strain demand for specific slopes. Soil properties and slope movements are acknowledged to be highly uncertain, with the uncertainty stemming in part from the lack of site-specific data and in part from the inherent variability in soils. The sensitivity of strain demand to the effect of soil variability is an important consideration when establishing the safety margin that must be employed when using the strain-based method for pipeline design or assessment. In this paper, a finite element analysis of pipe-soil interaction is employed to assess the influence of soil variability on strain demand. Strain demand is shown to be highly influenced by variability in slope movement parameters and soil properties. Strategies to reduce the variability in the strain demand either through increased data collection or through pipeline design are discussed.
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Lippi, Vittorio, and Raphael Deimel. "Phase Distribution in Probabilistic Movement Primitives, Representing Time Variability for the Recognition and Reproduction of Human Movements." In 16th International Conference on Informatics in Control, Automation and Robotics. SCITEPRESS - Science and Technology Publications, 2019. http://dx.doi.org/10.5220/0007750205710578.

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Chassat, Perrine, Juhyun Park, and Nicolas Brunel. "Analysis of variability in sign language hand trajectories: development of generative model." In MOCO '22: 8th International Conference on Movement and Computing. New York, NY, USA: ACM, 2022. http://dx.doi.org/10.1145/3537972.3537999.

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Konuk, I., U. O. Akpan, and D. P. Brennan. "Random Field Modeling of Rainfall-Induced Soil Movement." In 2002 4th International Pipeline Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/ipc2002-27165.

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Natural oil and gas transmission pipeline networks often traverse regions where potential slow ground movements may affect pipeline structural integrity. One of the primary causes of slow ground movement in any region involves the duration, amount, and intensity of rainfall. The phenomenon of rainfall-induced slow ground movement is characterized by both spatial and temporal variability, and involves uncertainties that are best modeled using a probabilistic methodology. A random field modeling strategy is formulated in this study, in which spatial and temporal correlations between rainfall and ground movement are accounted for. The random field formulation advanced in the current study has a number of significant features and capabilities, including modeling the spatial and temporal relationship between rainfall and slope movement for specified pipeline routes, predicting the likelihood of exceeding slope movement thresholds for various precipitation levels and intensities, and providing maps of risk for slope movement, which can be used as a guide in pipeline route planning, selection, and adaptation strategies for the design and maintenance of oil and gas infrastructure. These capabilities have been implemented and encapsulated into the software tool VSLOPE, which has been tested using monthly rainfall and field data for various locations.
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Arumingtyas, Estri Laras, Joni Kusnadi, Dewi Ratih Tirto Sari, and Nursita Ratih. "Genetic variability of Indonesian local chili pepper: The facts." In 8TH INTERNATIONAL CONFERENCE ON GLOBAL RESOURCE CONSERVATION (ICGRC 2017): Green Campus Movement for Global Conservation. Author(s), 2017. http://dx.doi.org/10.1063/1.5012726.

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Breault, Macauley Smith, Jorge A. Gonzalez-Martinez, John T. Gale, and Sridevi V. Sarma. "Neural Correlates of Internal States that Capture Movement Variability." In 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC). IEEE, 2019. http://dx.doi.org/10.1109/embc.2019.8856778.

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Reports on the topic "Movement variabiliity"

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Zhang, Renduo, and David Russo. Scale-dependency and spatial variability of soil hydraulic properties. United States Department of Agriculture, November 2004. http://dx.doi.org/10.32747/2004.7587220.bard.

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Water resources assessment and protection requires quantitative descriptions of field-scale water flow and contaminant transport through the subsurface, which, in turn, require reliable information about soil hydraulic properties. However, much is still unknown concerning hydraulic properties and flow behavior in heterogeneous soils. Especially, relationships of hydraulic properties changing with measured scales are poorly understood. Soil hydraulic properties are usually measured at a small scale and used for quantifying flow and transport in large scales, which causes misleading results. Therefore, determination of scale-dependent and spatial variability of soil hydraulic properties provides the essential information for quantifying water flow and chemical transport through the subsurface, which are the key processes for detection of potential agricultural/industrial contaminants, reduction of agricultural chemical movement, improvement of soil and water quality, and increase of agricultural productivity. The original research objectives of this project were: 1. to measure soil hydraulic properties at different locations and different scales at large fields; 2. to develop scale-dependent relationships of soil hydraulic properties; and 3. to determine spatial variability and heterogeneity of soil hydraulic properties as a function of measurement scales. The US investigators conducted field and lab experiments to measure soil hydraulic properties at different locations and different scales. Based on the field and lab experiments, a well-structured database of soil physical and hydraulic properties was developed. The database was used to study scale-dependency, spatial variability, and heterogeneity of soil hydraulic properties. An improved method was developed for calculating hydraulic properties based on infiltration data from the disc infiltrometer. Compared with the other methods, the proposed method provided more accurate and stable estimations of the hydraulic conductivity and macroscopic capillary length, using infiltration data collected atshort experiment periods. We also developed scale-dependent relationships of soil hydraulic properties using the fractal and geostatistical characterization. The research effort of the Israeli research team concentrates on tasks along the second objective. The main accomplishment of this effort is that we succeed to derive first-order, upscaled (block effective) conductivity tensor, K'ᵢⱼ, and time-dependent dispersion tensor, D'ᵢⱼ, i,j=1,2,3, for steady-state flow in three-dimensional, partially saturated, heterogeneous formations, for length-scales comparable with those of the formation heterogeneity. Numerical simulations designed to test the applicability of the upscaling methodology to more general situations involving complex, transient flow regimes originating from periodic rain/irrigation events and water uptake by plant roots suggested that even in this complicated case, the upscaling methodology essentially compensated for the loss of sub-grid-scale variations of the velocity field caused by coarse discretization of the flow domain. These results have significant implications with respect to the development of field-scale solute transport models capable of simulating complex real-world scenarios in the subsurface, and, in turn, are essential for the assessment of the threat posed by contamination from agricultural and/or industrial sources.
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Eckert, Elizabeth, Eleanor Turner, and Jo Anne Yeager Sallah. Youth Rural-Urban Migration in Bungoma, Kenya: Implications for the Agricultural Workforce. RTI Press, August 2019. http://dx.doi.org/10.3768/rtipress.2019.op.0062.1908.

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This study provides insights into a specific, hard-to-reach youth subpopulation—those born in agricultural areas in Western Kenya who migrate to large towns and cities—that is often missed by research and development activities. Using a mixed-methods approach, we find high variability in movement of youth between rural villages, towns, and large urban areas. Top reasons for youth migration align with existing literature, including pursuit of job opportunities and education. For youth from villages where crop farming is the primary economic activity for young adults, 77 percent responded that they are very interested in that work, in contrast to the common notion that youth are disinterested in agriculture. We also find many youth interested in settling permanently in their villages in the future. This research confirms that youth migration is dynamic, requiring that policymakers and development practitioners employ methods of engaging youth that recognize the diversity of profiles and mobility of this set of individuals.
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Jury, William A., and David Russo. Characterization of Field-Scale Solute Transport in Spatially Variable Unsaturated Field Soils. United States Department of Agriculture, January 1994. http://dx.doi.org/10.32747/1994.7568772.bard.

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This report describes activity conducted in several lines of research associated with field-scale water and solute processes. A major effort was put forth developing a stochastic continuum analysis for an important class of problems involving flow of reactive and non reactive chemicals under steady unsaturated flow. The field-scale velocity covariance tensor has been derived from local soil properties and their variability, producing a large-scale description of the medium that embodies all of the local variability in a statistical sense. Special cases of anisotropic medium properties not aligned along the flow direction of spatially variable solute sorption were analysed in detail, revealing a dependence of solute spreading on subtle features of the variability of the medium, such as cross-correlations between sorption and conductivity. A novel method was developed and tested for measuring hydraulic conductivity at the scale of observation through the interpretation of a solute transport outflow curve as a stochastic-convective process. This undertaking provided a host of new K(q) relationships for existing solute experiments and also laid the foundation for future work developing a self-consistent description of flow and transport under these conditions. Numerical codes were developed for calculating K(q) functions for a variety of solute pulse outflow shapes, including lognormal, Fickian, Mobile-Immobile water, and bimodal. Testing of this new approach against conventional methodology was mixed, and agreed most closely when the assumptions of the new method were met. We conclude that this procedure offers a valuable alternative to conventional methods of measuring K(q), particularly when the application of the method is at a scale (e.g. and agricultural field) that is large compared to the common scale at which conventional K(q) devices operate. The same problem was approached from a numerical perspective, by studying the feasibility of inverting a solute outflow signal to yield the hydraulic parameters of the medium that housed the experiment. We found that the inverse problem was solvable under certain conditions, depending on the amount of noise in the signal and the degree of heterogeneity in the medium. A realistic three dimensional model of transient water and solute movement in a heterogeneous medium that contains plant roots was developed and tested. The approach taken was to generate a single realization of this complex flow event, and examine the results to see whether features were present that might be overlooked in less sophisticated model efforts. One such feature revealed is transverse dispersion, which is a critically important component in the development of macrodispersion in the longitudinal direction. The lateral mixing that was observed greatly exceeded that predicted from simpler approaches, suggesting that at least part of the important physics of the mixing process is embedded in the complexity of three dimensional flow. Another important finding was the observation that variability can produce a pseudo-kinetic behavior for solute adsorption, even when the local models used are equilibrium.
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Russo, David, and William A. Jury. Characterization of Preferential Flow in Spatially Variable Unsaturated Field Soils. United States Department of Agriculture, October 2001. http://dx.doi.org/10.32747/2001.7580681.bard.

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Preferential flow appears to be the rule rather than the exception in field soils and should be considered in the quantitative description of solute transport in the unsaturated zone of heterogeneous formations on the field scale. This study focused on both experimental monitoring and computer simulations to identify important features of preferential flow in the natural environment. The specific objectives of this research were: (1) To conduct dye tracing and multiple tracer experiments on undisturbed field plots to reveal information about the flow velocity, spatial prevalence, and time evolution of a preferential flow event; (2) To conduct numerical experiments to determine (i) whether preferential flow observations are consistent with the Richards flow equation; and (ii) whether volume averaging over a domain experiencing preferential flow is possible; (3) To develop a stochastic or a transfer function model that incorporates preferential flow. Regarding our field work, we succeeded to develop a new method for detecting flow patterns faithfully representing the movement of water flow paths in structured and non-structured soils. The method which is based on application of ammonium carbonate was tested in a laboratory study. Its use to detect preferential flow was also illustrated in a field experiment. It was shown that ammonium carbonate is a more conservative tracer of the water front than the popular Brilliant Blue. In our detailed field experiments we also succeeded to document the occurrence of preferential flow during soil water redistribution following the cessation of precipitation in several structureless field soils. Symptoms of the unstable flow observed included vertical fingers 20 - 60 cm wide, isolated patches, and highly concentrated areas of the tracers in the transmission zone. Soil moisture and tracer measurements revealed that the redistribution flow became fingered following a reversal of matric potential gradient within the wetted area. Regarding our simulation work, we succeeded to develop, implement and test a finite- difference, numerical scheme for solving the equations governing flow and transport in three-dimensional, heterogeneous, bimodal, flow domains with highly contrasting soil materials. Results of our simulations demonstrated that under steady-state flow conditions, the embedded clay lenses (with very low conductivity) in bimodal formations may induce preferential flow, and, consequently, may enhance considerably both the solute spreading and the skewing of the solute breakthrough curves. On the other hand, under transient flow conditions associated with substantial redistribution periods with diminishing water saturation, the effect of the embedded clay lenses on the flow and the transport might diminish substantially. Regarding our stochastic modeling effort, we succeeded to develop a theoretical framework for flow and transport in bimodal, heterogeneous, unsaturated formations, based on a stochastic continuum presentation of the flow and a general Lagrangian description of the transport. Results of our analysis show that, generally, a bimodal distribution of the formation properties, characterized by a relatively complex spatial correlation structure, contributes to the variability in water velocity and, consequently, may considerably enhance solute spreading. This applies especially in formations in which: (i) the correlation length scales and the variances of the soil properties associated with the embedded soil are much larger than those of the background soil; (ii) the contrast between mean properties of the two subdomains is large; (iii) mean water saturation is relatively small; and (iv) the volume fraction of the flow domain occupied by the embedded soil is relatively large.
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