Littérature scientifique sur le sujet « Descriptors of recovery trajectories »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Sommaire
Consultez les listes thématiques d’articles de revues, de livres, de thèses, de rapports de conférences et d’autres sources académiques sur le sujet « Descriptors of recovery trajectories ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Articles de revues sur le sujet "Descriptors of recovery trajectories"
1
Gomez, Catalina G., Hector M. Guzman et Andrew Gonzalez. « Population decline and the effects of disturbances on the structure and recovery of octocoral communities (Coelenterata : Octocorallia) in Pacific Panama ». Journal of the Marine Biological Association of the United Kingdom 95, no 1 (17 juillet 2014) : 81–90. http://dx.doi.org/10.1017/s0025315414000915.
Texte intégralRésumé :
Community structure, species composition, and changes over time after disturbances are frequently studied using common descriptors. We used rank abundance distribution plots (RADs), Rényi entropy plots, common theoretical community models, ordination analysis of similarities (ANOSIM and Clusters), and abundance spectra analyses to study the effects of a gradual natural population decline and an anthropogenic punctuated disturbance on the structure of octocoral communities in Panama, considered a hot spot area for octocoral diversity in the Tropical Eastern Pacific. Over a 17-month period, no significant change was found in community structure after a natural yearly population decline of 25.2%. After a disturbance, however, different recovery trajectories were observed in various coral communities. Possible physical and biological explanations for the observed differences include initial local species diversity and abundance, species life history patterns, colony morphology, and the geographical location of the community. Differences in community structure between study sites were best described using a combination of community descriptors, RADs, and abundance spectra. Rényi plots were useful in identifying changes in community structure, whereas the extent of the changes was best evaluated using ANOSIM and cluster analysis.
2
Rushton, Alison, Feroz Jadhakhan, Annabel Masson, Victoria Athey, J. Bart Staal, Martin L. Verra, Andrew Emms et al. « Patient journey following lumbar spinal fusion surgery (FuJourn) : A multicentre exploration of the immediate post-operative period using qualitative patient diaries ». PLOS ONE 15, no 12 (1 décembre 2020) : e0241931. http://dx.doi.org/10.1371/journal.pone.0241931.
Texte intégralRésumé :
The aim of this study was to capture and understand the immediate recovery journey of patients following lumbar spinal fusion surgery and explore the interacting constructs that shape their journey. A qualitative study using Interpretive Phenomenological Analysis (IPA) approach. A purposive sample of 43 adult patients (≥16 years) undergoing ≤4 level instrumented fusion for back and/or leg pain of degenerative cause, were recruited pre-surgery from 4 UK spinal surgery centres. Patients completed a weekly diary expressed in their own words for the first 4 weeks following surgery to capture their life as lived. Diary content was based on previous research findings and recorded progress, recovery, motivation, symptoms, medications, healthcare appointments, rehabilitation, positive/negative thoughts, and significant moments; comparing to the previous week. To maximise completion and data quality, diaries could be completed in paper form, word document, as online survey or as audio recording. Strategies to enhance diary adherence included a weekly prompt. A framework analysis for individual diaries and then across participants (deductive and inductive components) captured emergent themes. Trustworthiness was enhanced by strategies including reflexivity, attention to negative cases and use of critical co-investigators. Twenty-eight participants (15 female; n = 18 (64.3%) aged 45–64) contributed weekly diaries (12 withdrew post-surgery, 3 did not follow through with surgery). Adherence with diaries was 89.8%. Participants provided diverse and vivid descriptions of recovery experiences. Three distinct recovery trajectories were identified: meaningful recovery (engagement in physical and functional activities to return to functionality/mobility); progressive recovery (small but meaningful improvement in physical ability with increasing confidence); and disruptive recovery (limited purpose for meaningful recovery). Important interacting constructs shaped participants’ recovery including their pain experience and self-efficacy. This is the first account of immediate recovery trajectories from patients’ perspectives. Recognition of a patient’s trajectory may inform patient-centred recovery, follow-up and rehabilitation to improve patient outcomes.
3
Mor, M., et S. Dalyot. « ENRICHING WALKING ROUTES WITH TOURISM ATTRACTIONS RETRIEVED FROM CROWDSOURCED USER GENERATED DATA ». ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences V-4-2020 (3 août 2020) : 95–102. http://dx.doi.org/10.5194/isprs-annals-v-4-2020-95-2020.
Texte intégralRésumé :
Abstract. It is always a tourism challenge – and aspiration – to discover scenery routes and tourism attractions in unfamiliar areas. Tourism information is getting more extensive, comprehensive and complex, so first-time tourists have to manage and mine large volumes of data to better plan their trip. Nowadays, geotagged photos are uploaded by users to social media photo-sharing online websites, which become more popular and commonly used by travelers to share their tourism experiences. Handling, mining and interpreting these user-generated ‘digital footprints’ can be used to reconstruct travel trajectories of users to recover their activity and knowledge. In this research, we showcase Flickr geotagged crowdsource photo database as a source for mining users’ trajectories to effectively compute walking tourism routes. Our methodology mines tourism context by conceptualizing a set of adaptive spatiotemporal descriptors to identify photographers that show tourism activity of first-time visitors. By implementing spatial clustering, we find popular locations that are traversed by these tourism-oriented photographers’ trajectories. To analyze our approach, we develop a greedy route computation algorithm that seeks the most popular traversed locations between origin and destination points defined by the user. Results for two cities are presented, proving the robust mining and retrieving of valuable tourism context and information from social media photos. We evaluate and validate our results by comparing the computed walking routes to recognized tourism information. The computed walking routes are scenery and pass through the main popular tourism sights and landmarks in the city, including additional attractive places that are frequently visited by tourism-photographers.
4
Wei, Wei, Xin Shu, Peng Chen et Xiangyun Li. « A chord-angle-based approach with expandable solution space to 1-degree-of-freedom (DOF) rehabilitation mechanism synthesis ». Mechanical Sciences 13, no 1 (12 avril 2022) : 341–52. http://dx.doi.org/10.5194/ms-13-341-2022.
Texte intégralRésumé :
Abstract. Rehabilitation robots have been proven to be an effective tool for patient motor recovery in clinical medicine. Recently, few degrees of freedom (DOFs), especially 1-DOF, rehabilitation robots have drawn increasing attention as the complexity and cost of the control system would be significantly reduced. In this paper, the mechanism synthesis problem of 1-DOF rehabilitation robots is studied. Traditional synthesis methods usually aim at minimizing the trajectory error to generate a mathematically optimal solution, which may not be a practically feasible solution in terms of engineering constraints. Therefore, we propose a novel mechanism synthesis approach based on chord angle descriptor (CAD) and error tolerance expansion to generate a pool of mechanism solutions from which mathematically and practically optimal solutions can be selected. CAD is utilized for its capability to represent the same-shaped trajectories of different mechanisms in a unified way, and it is robust to the noise in the rehabilitation trajectory acquired by motion capture systems. Then a library of mechanism trajectories is established with compressed representations of CAD via an auto-encoder algorithm to speed up the matching between mechanism and rehabilitation trajectory where the matching error tolerance can be adjusted according to practical rehabilitation specifications. Finally, a design example of a 1-DOF rehabilitation robot for upper-limb training is provided to demonstrate the efficacy of our novel approach.
5
Kotov, B., V. Hryshchenko, Yu Pantsyr et I. Herasymchuk. « Electrotechnological complex for dedusting ventilation exhausts heat recovery units in production facilities and units ». Energy and automation, no 2(54) (22 juin 2021) : 118–26. http://dx.doi.org/10.31548/energiya2021.02.118.
Texte intégralRésumé :
Currently, to create a microclimate in the production facilities of agro-industrial production are widely used utilizers of waste heat of ventilation emissions. But the air of such premises is clogged with dust impurities and has a high moisture content, as a result of which condensate falls on the heat-transfer surfaces, and dust sticks to the moistened surface. As a result, the efficiency of heat exchangers is significantly reduced, and the hydraulic resistance increases, which can cause a decrease in air supply. Therefore, there is a need to combat dust in the air supplied to heat recovery units. The most common method of purification of gas streams from solid dust impurities is the deposition of the latter in electrostatic precipitators, to increase the efficiency of which use gravitational moving water film. Currently, there are no mathematical descriptions and calculated dependences for horizontal electrostatic precipitators and electrohydrocyclones. The aim of the study is to formulate a mathematical description of the processes of movement of solid particles in the chambers of the horizontal electrostatic precipitator and electrohydrocyclone. The analysis of the existing systems of heat utilization of exhaust air and influence of dustiness on efficiency of their use is resulted. The possibility of using various systems for dust cleaning of exhaust air in agro-industrial facilities is considered. The technological and constructive scheme of the electrotechnological complex of utilization of heat of ventilating emissions which includes the electrohydrocyclone for clearing of dust of exhaust air is offered. The effect of determining forces, including electric, on the motion of a dust particle in the rotating flow of an electrohydrocyclone is analyzed. Equations describing the motion of a particle in an air rotating flow under the action of an electric field are determined, and mathematical models are compiled to calculate the trajectory of the dust particle. Simplified analytical expressions for particle motion trajectories are presented. Keywords: dust, separation, electric field, cyclone, airflow
6
Liao, Zhongke, Haifeng Hu et Yichu Liu. « Action Recognition with Multiple Relative Descriptors of Trajectories ». Neural Processing Letters 51, no 1 (2 août 2019) : 287–302. http://dx.doi.org/10.1007/s11063-019-10091-z.
Texte intégral
7
Martínez Carrillo, Fabio, Fabián Castillo et Lola Bautista. « 3D+T dense motion trajectories as kinematics primitives to recognize gestures on depth video sequences ». Revista Politécnica 15, no 29 (31 juillet 2019) : 82–94. http://dx.doi.org/10.33571/rpolitec.v15n29a7.
Texte intégralRésumé :
RGB-D sensors have allowed attacking many classical problems in computer vision such as segmentation, scene representations and human interaction, among many others. Regarding motion characterization, typical RGB-D strategies are limited to namely analyze global shape changes and capture scene flow fields to describe local motions in depth sequences. Nevertheless, such strategies only recover motion information among a couple of frames, limiting the analysis of coherent large displacements along time. This work presents a novel strategy to compute 3D+t dense and long motion trajectories as fundamental kinematic primitives to represent video sequences. Each motion trajectory models kinematic words primitives that together can describe complex gestures developed along videos. Such kinematic words were processed into a bag-of-kinematic-words framework to obtain an occurrence video descriptor. The novel video descriptor based on 3D+t motion trajectories achieved an average accuracy of 80% in a dataset of 5 gestures and 100 videos.
8
Vochten, Maxim, Tinne De Laet et Joris De Schutter. « Generalizing demonstrated motion trajectories using coordinate-free shape descriptors ». Robotics and Autonomous Systems 122 (décembre 2019) : 103291. http://dx.doi.org/10.1016/j.robot.2019.103291.
Texte intégral
9
Wang, Heng, Alexander Kläser, Cordelia Schmid et Cheng-Lin Liu. « Dense Trajectories and Motion Boundary Descriptors for Action Recognition ». International Journal of Computer Vision 103, no 1 (6 mars 2013) : 60–79. http://dx.doi.org/10.1007/s11263-012-0594-8.
Texte intégral
10
Tavakoli, Yashar, Lourdes Peña-Castillo et Amilcar Soares. « A Study on the Geometric and Kinematic Descriptors of Trajectories in the Classification of Ship Types ». Sensors 22, no 15 (26 juillet 2022) : 5588. http://dx.doi.org/10.3390/s22155588.
Texte intégralRésumé :
The classification of ships based on their trajectory descriptors is a common practice that is helpful in various contexts, such as maritime security and traffic management. For the most part, the descriptors are either geometric, which capture the shape of a ship’s trajectory, or kinematic, which capture the motion properties of a ship’s movement. Understanding the implications of the type of descriptor that is used in classification is important for feature engineering and model interpretation. However, this matter has not yet been deeply studied. This article contributes to feature engineering within this field by introducing proper similarity measures between the descriptors and defining sound benchmark classifiers, based on which we compared the predictive performance of geometric and kinematic descriptors. The performance profiles of geometric and kinematic descriptors, along with several standard tools in interpretable machine learning, helped us to provide an account of how different ships differ in movement. Our results indicated that the predictive performance of geometric and kinematic descriptors varied greatly, depending on the classification problem at hand. We also showed that the movement of certain ship classes solely differed geometrically while some other classes differed kinematically and that this difference could be formulated in simple terms. On the other hand, the movement characteristics of some other ship classes could not be delineated along these lines and were more complicated to express. Finally, this study verified the conjecture that the geometric–kinematic taxonomy could be further developed as a tool for more accessible feature selection.
Thèses sur le sujet "Descriptors of recovery trajectories"
1
Maurent, Eliott. « Des forêts tropicales et des humains dans les Amériques : trajectoires de réponse aux perturbations anthropiques de la diversité et de la composition des arbres. Of tropical forests and humans in the Americas : response trajectories of tree diversity and composition to anthropogenic disturbances ». Electronic Thesis or Diss., Paris, AgroParisTech, 2023. http://www.theses.fr/2023AGPT0014.
Texte intégralRésumé :
Les forêts tropicales sont confrontées à des perturbations anthropiques fréquentes et intenses, telles que l'exploitation sélective - l'abattage de quelques arbres dans des forêts anciennes, tandis que le reste du peuplement se régénère naturellement. De nombreuses études ont été menées sur la reconstitution des stocks de carbone et de bois, en raison d'un intérêt pour l'atténuation du changement climatique et la rentabilité de l'exploitation. Malgré le rôle crucial de la biodiversité pour le maintien et le fonctionnement des écosystèmes - et sa valeur intrinsèque - peu d'études ont été menées sur l'impact de l'exploitation sélective sur la biodiversité. Par conséquent, cette thèse vise à caractériser la réponse de la diversité et de la composition des arbres à l'exploitation forestière dans les forêts tropicales américaines.Grâce aux inventaires forestiers (1986-2021, diamètre à hauteur de poitrine ≥ 10 cm) de la station de Paracou (Guyane française), nous avons construit un cadre bayésien de modélisation des trajectoires de la diversité et de la composition des arbres après exploitation : Paracou a été perturbé par des traitements sylvicoles de différentes intensités en 1986-1987. Nous avons propagé l'incertitude associée à la détermination botanique et aux mesures des traits fonctionnels, et modélisé les trajectoires de diversité et de composition taxonomique, phylogénétique et fonctionnelle des arbres au niveau de l'espèce, par rapport à leurs niveaux pré-perturbation. En outre, nous avons évalué l'effet des caractéristiques des communautés d'arbres pré-perturbation, des conditions biophysiques et des propriétés de la perturbation sur nos trajectoires d'attributs forestiers. Deuxièmement, nous avons utilisé une version simplifiée du cadre de modélisation susmentionné sur des inventaires forestiers à long terme provenant de parcelles situées au Costa Rica et dans trois pays amazoniens (Observatorio de los Ecosistemas Forestales de Costa Rica et Tropical managed Forest Observatory). Nous avons modélisé leurs trajectoires de diversité et de composition taxonomique et fonctionnelle après exploitation au niveau du genre, à partir desquelles nous avons extrait des indicateurs sur la période d'inventaire de chaque site. Nous avons ensuite évalué l'effet de la structure de la communauté d'arbres pré-perturbation et des propriétés de la perturbation sur ces indicateurs. Bien que plus variables dans la seconde étude ayant une portée géographique plus large, nous avons observé des tendances similaires dans les deux études : la diversité a majoritairement augmenté après exploitation et les communautés d'arbres sont principalement passées de stratégies de conservation à des stratégies d'acquisition des ressources. Ces changements semblent provenir du recrutement abondant et momentané d'espèces de début de succession présentant des caractéristiques d'acquisition des ressources, ce qui leur confère un avantage compétitif lorsque l'intensité de perturbation - i.e., disponibilité de la lumière et de l'espace - augmente. En effet, les changements de diversité et composition ont augmenté dans les deux études avec l'intensité de perturbation, alors que les autres descripteurs n'ont pas eu d'effet significatif. Troisièmement, suite à l'importance de l'intensité de perturbation dans les études précédentes, nous avons développé un cadre commun de modélisation des trajectoires de forêts perturbées à travers un gradient d'intensité de perturbation. Nous avons testé notre approche de modélisation sur des inventaires forestiers de long-terme du Costa Rica et de Guyane française, après exploitation sélective, agriculture, et coupe à blanc suivie d'un feu.Ces résultats ouvrent des perspectives sur les méthodes d'évaluation de la réponse forestière aux perturbations, la réponse des forêts elle-même et ses processus écologiques sous-jacents, et l'intérêt des forêts perturbées pour les plans de gestion et de conservation forestièresTropical forests face more frequent and intense anthropogenic disturbances, such as selective logging, namely the felling and harvesting of a few commercially valuable trees in old-growth forests, while the remaining stand is left for natural regeneration. Many studies focused on this regeneration, particularly on the recovery of carbon and timber stocks, most likely due to a strong interest in climate change mitigation and logging profitability. However, despite the crucial role of biodiversity for ecosystem maintenance and functioning - and its intrinsic value - there have been few studies on the impact of selective logging on biodiversity. Therefore, this thesis - organised in three studies - aimed at characterising the response of tree diversity and composition to logging in tropical American forests.First, we drew upon the long-term forest inventories (1986-2021, trees with a diameter at breast height ≥ 10 cm) from Paracou experimental station to build a Bayesian modelling framework of tree diversity and composition trajectories after selective logging. Paracou is located in French Guiana and was disturbed by silvicultural treatments of different intensities in 1986-1987. We propagated in our Bayesian framework the uncertainty associated with botanical determination and functional trait measurements, and modelled Paracou trajectories of taxonomic, phylogenetic and functional tree diversity and composition at the species level, relatively to their pre-disturbance levels. Additionally, we assessed the effect of pre-disturbance tree community characteristics, biophysical conditions and disturbance properties on our forest attribute trajectories. Second, we used a simplified version of the aforementioned Bayesian modelling framework on long-term forest inventories from sample plots located in Costa Rica and three Amazonian countries (respectively belonging to the Observatorio de los Ecosistemas Forestales de Costa Rica and the Tropical managed Forest Observatory). We modelled their post-logging trajectories of taxonomic and functional tree diversity and composition at the genus level, from which we extracted indicators solely over the inventory timespan of each site. We then assessed the effect of pre-disturbance tree community structure and disturbance properties on such indicators. While more variable in the second study with a broader geographical scope than in the first one, we observed similar trends in both studies: diversity mostly increased after logging and tree communities mainly shifted from resource-conservative strategies to resource-acquisitive strategies. Such changes appeared to be driven by the abundant and transient recruitment of early-successional species with acquisitive trait values, which provided them with a competitive advantage as disturbance intensity - i.e., light and space availability - increased. Indeed, changes in diversity and composition increased in both studies with disturbance intensity whereas disturbance selectivity, pre-disturbance tree community characteristics and biophysical conditions had no significant effect. Third, building up on the paramount importance of disturbance intensity in the two previous studies, we developed an original Bayesian hierarchical model of recovery trajectories, considering disturbed forests in a common framework, through a disturbance intensity gradient. We tested our modelling approach on data from two long-term experiments in Costa Rica and French Guiana, set up after selective logging, agriculture, and clearcutting and fire.Overall, these results opened various perspectives on the methods used to evaluate forest response to disturbance, the forest response itself and the ecological processes underlying forest succession, and how disturbed forests could be considered in forest management and conservation plans
2
Elderkin, Anita. « Resilience or Recovery : A Phenomenological Investigation Into Parental Bereavement ». ScholarWorks, 2017. https://scholarworks.waldenu.edu/dissertations/3603.
Texte intégralRésumé :
Facing the death of a loved one is often a traumatic experience; when the deceased is one's own child, the loss may be the most stressful event of one's life. There has been very little research into the phenomenon of being a bereaved parent. This study is a phenomenological investigation into the lived experience of being a bereaved parent and whether resilience or recovery plays a role in how parents move through and eventually past such a loss to continue with their own lives. Previous research has indicated that adjustment to traumatic experiences can take multiple pathways or trajectories, depending on a variety of factors within the individual coping with the stressful event. This study involved an investigation into these pathways through the lived experiences of those who suffered the loss of a child, in an effort to determine whether resilience or recovery influenced a parent's ability to survive the death. Ten bereaved parents were interviewed to learn whether resilience or recovery affected their ability to cope and function in a healthy way despite the loss. These interviews were analyzed to determine whether there were common themes among unrelated bereaved parents, and whether they resonated with the concept of resilience or that of recovery. The results of this study indicated resilience to be a healthier method of adjustment for bereaved parents, with recovery being an almost offensive concept for those who participated. These results allow for a greater understanding of the lived experience of being a bereaved parent, as well as instruct those in helping professions in how best to serve bereaved parents who need to adapt to new lives that now proceed without the beloved child.
3
McKeever, Catherine Irene Kaminaris Zillmer Eric. « Assessment paradigm of sports-related concussions : program implementation, incidence, severity and recovery trajectories in collegiate athletes / ». Philadelphia, Pa. : Drexel University, 2004. http://dspace.library.drexel.edu/handle/1860/339.
Texte intégral
4
Mickelson, Bryan K. « Client Change in Multi-Model Treatment : A Comparison of Change Trajectories in Group, Individual, and Conjoint Formats in a Counseling Center ». Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2758.pdf.
Texte intégral
5
Narayan, Sanath. « Trajectory-based Descriptors for Action Recognition in Real-world Videos ». Thesis, 2015. http://etd.iisc.ac.in/handle/2005/3994.
Texte intégralRésumé :
This thesis explores motion trajectory-based approaches to recognize human actions in
real-world, unconstrained videos. Recognizing actions is an important task in applications
such as video retrieval, surveillance, human-robot interactions, analysis of sports videos, summarization of videos, behaviour monitoring, etc. There has been a considerable amount of research done in this regard. Earlier work used to be on videos captured by static cameras where it was relatively easy to recognise the actions. With more videos being captured by moving cameras, recognition of actions in such videos with irregular camera motion is still a challenge in unconstrained settings with variations in scale, view, illumination, occlusion and unrelated motions in the background. With the increase in videos being captured from wearable or head-mounted cameras, recognizing actions in egocentric videos is also explored in this thesis.
At first, an effective motion segmentation method to identify the camera motion
in videos captured by moving cameras is explored. Next, action recognition in videos
captured in normal third-person view (perspective) is discussed. Further, the action recognition approaches for first-person (egocentric) views are investigated. First-person videos are often associated with frequent unintended camera motion. This is due to the motion of the head resulting in the motion of the head-mounted cameras (wearable cameras). This is followed by recognition of actions in egocentric videos in a multicamera setting. And lastly, novel feature encoding and subvolume sampling (for “deep” approaches) techniques are explored in the context of action recognition in videos.
The first part of the thesis explores two effective segmentation approaches to identify
the motion due to camera. The first approach is based on curve fitting of the motion
trajectories and finding the model which best fits the camera motion model. The curve
fitting approach works when the trajectories generated are smooth enough. To overcome
this drawback and segment trajectories under non-smooth conditions, a second approach
based on trajectory scoring and grouping is proposed. By identifying the instantaneous
dominant background motion and accordingly aggregating the scores (denoting the
“foregroundness”) along the trajectory, the motion that is associated with the camera can
be separated from the motion due to foreground objects. Additionally, the segmentation result has been used to align videos from moving cameras, resulting in videos that seem to be captured by nearly-static cameras.
In the second part of the thesis, recognising actions in normal videos captured from
third-person cameras is investigated. To this end, two kinds of descriptors are explored.
The first descriptor is the covariance descriptor adapted for the motion trajectories. The covariance descriptor for a trajectory encodes the co-variations of different features along the trajectory’s length. Covariance, being a second-order encoding, encodes information of the trajectory that is different from that of the first-order encoding. The second
descriptor is based on Granger causality. The novel causality descriptor encodes the
“cause and effect” relationships between the motion trajectories of the actions. This
type of interaction descriptors captures the causal inter-dependencies among the motion
trajectories and encodes complimentary information different from those descriptors
based on the occurrence of features. The causal dependencies are traditionally computed on time-varying signals. We extend it further to capture dependencies between spatiotemporal signals and compute generalised causality descriptors which perform better than their traditional counterparts.
An egocentric or first-person video is captured from the perspective of the personof-interest (POI). The POI wears a camera and moves around doing his/her activities.
This camera records the events and activities as seen by him/her. The POI who is performing actions or activities is not seen by the camera worn by him/her. Activities
performed by the POI are called first-person actions and third-person actions are those
done by others and observed by the POI. The third part of the thesis explores action
recognition in egocentric videos. Differentiating first-person and third-person actions is important when summarising/analysing the behaviour of the POI. Thus, the goal is to
recognise the action and the perspective from which it is being observed. Trajectory
descriptors are adapted to recognise actions along with the motion trajectory ranking
method of segmentation as pre-processing step to identify the camera motion. The motion
segmentation step is necessary to remove unintended head motion (camera motion) during
video capture. To recognise actions and corresponding perspectives in a multi-camera
setup, a novel inter-view causality descriptor based on the causal dependencies between trajectories in different views is explored. Since this is a new problem being addressed, two first-person datasets are created with eight actions in third-person and first-person perspectives. The first dataset is a single camera dataset with action instances from first-person and third-person views. The second dataset is a multi-camera dataset with each action instance having multiple first-person and third-person views.
In the final part of the thesis, a feature encoding scheme and a subvolume sampling
scheme for recognising actions in videos is proposed. The proposed Hyper-Fisher Vector
feature encoding is based on embedding the Bag-of-Words encoding into the Fisher Vector
encoding. The resulting encoding is simple, effective and improves the classification
performance over the state-of-the-art techniques. This encoding can be used in place of the traditional Fisher Vector encoding in other recognition approaches. The proposed subvolume sampling scheme, used to generate second layer features in “deep” approaches for action recognition in videos, is based on iteratively increasing the size of the valid subvolumes in the temporal direction to generate newer subvolumes. The proposed sampling requires lesser number of subvolumes to be generated to “better represent” the actions and thus, is less computationally intensive compared to the original sampling scheme. The techniques are evaluated on large-scale, challenging, publicly available datasets. The Hyper-Fisher Vector combined with the proposed sampling scheme perform better than the state-of-the-art techniques for action classification in videos.
6
Narayan, Sanath. « Trajectory-based Descriptors for Action Recognition in Real-world Videos ». Thesis, 2015. http://etd.iisc.ernet.in/2005/3914.
Texte intégralRésumé :
This thesis explores motion trajectory-based approaches to recognize human actions in
real-world, unconstrained videos. Recognizing actions is an important task in applications
such as video retrieval, surveillance, human-robot interactions, analysis of sports videos, summarization of videos, behaviour monitoring, etc. There has been a considerable amount of research done in this regard. Earlier work used to be on videos captured by static cameras where it was relatively easy to recognise the actions. With more videos being captured by moving cameras, recognition of actions in such videos with irregular camera motion is still a challenge in unconstrained settings with variations in scale, view, illumination, occlusion and unrelated motions in the background. With the increase in videos being captured from wearable or head-mounted cameras, recognizing actions in egocentric videos is also explored in this thesis.
At first, an effective motion segmentation method to identify the camera motion
in videos captured by moving cameras is explored. Next, action recognition in videos
captured in normal third-person view (perspective) is discussed. Further, the action recognition approaches for first-person (egocentric) views are investigated. First-person videos are often associated with frequent unintended camera motion. This is due to the motion of the head resulting in the motion of the head-mounted cameras (wearable cameras). This is followed by recognition of actions in egocentric videos in a multicamera setting. And lastly, novel feature encoding and subvolume sampling (for “deep” approaches) techniques are explored in the context of action recognition in videos.
The first part of the thesis explores two effective segmentation approaches to identify
the motion due to camera. The first approach is based on curve fitting of the motion
trajectories and finding the model which best fits the camera motion model. The curve
fitting approach works when the trajectories generated are smooth enough. To overcome
this drawback and segment trajectories under non-smooth conditions, a second approach
based on trajectory scoring and grouping is proposed. By identifying the instantaneous
dominant background motion and accordingly aggregating the scores (denoting the
“foregroundness”) along the trajectory, the motion that is associated with the camera can
be separated from the motion due to foreground objects. Additionally, the segmentation result has been used to align videos from moving cameras, resulting in videos that seem to be captured by nearly-static cameras.
In the second part of the thesis, recognising actions in normal videos captured from
third-person cameras is investigated. To this end, two kinds of descriptors are explored.
The first descriptor is the covariance descriptor adapted for the motion trajectories. The covariance descriptor for a trajectory encodes the co-variations of different features along the trajectory’s length. Covariance, being a second-order encoding, encodes information of the trajectory that is different from that of the first-order encoding. The second
descriptor is based on Granger causality. The novel causality descriptor encodes the
“cause and effect” relationships between the motion trajectories of the actions. This
type of interaction descriptors captures the causal inter-dependencies among the motion
trajectories and encodes complimentary information different from those descriptors
based on the occurrence of features. The causal dependencies are traditionally computed on time-varying signals. We extend it further to capture dependencies between spatiotemporal signals and compute generalised causality descriptors which perform better than their traditional counterparts.
An egocentric or first-person video is captured from the perspective of the personof-interest (POI). The POI wears a camera and moves around doing his/her activities.
This camera records the events and activities as seen by him/her. The POI who is performing actions or activities is not seen by the camera worn by him/her. Activities
performed by the POI are called first-person actions and third-person actions are those
done by others and observed by the POI. The third part of the thesis explores action
recognition in egocentric videos. Differentiating first-person and third-person actions is important when summarising/analysing the behaviour of the POI. Thus, the goal is to
recognise the action and the perspective from which it is being observed. Trajectory
descriptors are adapted to recognise actions along with the motion trajectory ranking
method of segmentation as pre-processing step to identify the camera motion. The motion
segmentation step is necessary to remove unintended head motion (camera motion) during
video capture. To recognise actions and corresponding perspectives in a multi-camera
setup, a novel inter-view causality descriptor based on the causal dependencies between trajectories in different views is explored. Since this is a new problem being addressed, two first-person datasets are created with eight actions in third-person and first-person perspectives. The first dataset is a single camera dataset with action instances from first-person and third-person views. The second dataset is a multi-camera dataset with each action instance having multiple first-person and third-person views.
In the final part of the thesis, a feature encoding scheme and a subvolume sampling
scheme for recognising actions in videos is proposed. The proposed Hyper-Fisher Vector
feature encoding is based on embedding the Bag-of-Words encoding into the Fisher Vector
encoding. The resulting encoding is simple, effective and improves the classification
performance over the state-of-the-art techniques. This encoding can be used in place of the traditional Fisher Vector encoding in other recognition approaches. The proposed subvolume sampling scheme, used to generate second layer features in “deep” approaches for action recognition in videos, is based on iteratively increasing the size of the valid subvolumes in the temporal direction to generate newer subvolumes. The proposed sampling requires lesser number of subvolumes to be generated to “better represent” the actions and thus, is less computationally intensive compared to the original sampling scheme. The techniques are evaluated on large-scale, challenging, publicly available datasets. The Hyper-Fisher Vector combined with the proposed sampling scheme perform better than the state-of-the-art techniques for action classification in videos.
Livres sur le sujet "Descriptors of recovery trajectories"
1
United States. National Aeronautics and Space Administration., dir. Guidance of nonlinear nonminimum-phase dynamic systems : Performance report, period : 3/1/97 - 11/14/97, grant number : NAG 2-1042. [Washington, DC : National Aeronautics and Space Administration, 1997.
Trouver le texte intégral
2
United States. National Aeronautics and Space Administration., dir. Guidance of nonlinear nonminimum-phase dynamic systems : Performance report ; period : 3/1/96 - 2/28/97 ; grant number : NAG 2-1042. [Washington, DC : National Aeronautics and Space Administration, 1996.
Trouver le texte intégral
3
United States. National Aeronautics and Space Administration., dir. Guidance of nonlinear nonminimum-phase dynamic systems : Performance report ; period : 3/1/96 - 2/28/97 ; grant number : NAG 2-1042. [Washington, DC : National Aeronautics and Space Administration, 1996.
Trouver le texte intégral
4
United States. National Aeronautics and Space Administration., dir. Guidance of nonlinear nonminimum-phase dynamic systems : Performance report, period : 3/1/97 - 11/14/97, grant number : NAG 2-1042. [Washington, DC : National Aeronautics and Space Administration, 1997.
Trouver le texte intégral
5
Workshop on Particle Capture, Recovery, and Velocity/Trajectory Measurement Technologies : Held at Houston, Texas, September 27-28, 1993. Houston, TX : The Institute, 1994.
Trouver le texte intégral
6
Minteer, Ben A. Environmental Ethics, Sustainability Science, and the Recovery of Pragmatism. Sous la direction de Stephen M. Gardiner et Allen Thompson. Oxford University Press, 2016. http://dx.doi.org/10.1093/oxfordhb/9780199941339.013.46.
Texte intégralRésumé :
The recent emergence of sustainability science has created opportunities and challenges for environmental ethics. On the one hand, the fast growth and increasing influence of sustainability science in environmental management and policy circles—and its normative character as a goal-directed enterprise focused on moving society toward a more durable socio-ecological relationship—provides an opening for environmental ethics to contribute to the development of this new transdisciplinary science. Yet traditional (and historically dominant) nonanthropocentric ethics will prove difficult to reconcile with sustainability science’s strong emphasis on the anthropocentric goals of improving human welfare and well-being. A more explicitly pragmatic understanding of environmental ethics, a view that combines respect for nature with a wider sense of value pluralism (including more human-directed values) in the cautious shaping of ecological systems for conservation and human benefit, has the potential to draw the two fields closer together at this critical stage in their developmental trajectories.
7
Guidance of nonlinear nonminimum-phase dynamic systems : Performance report, period : 3/1/97 - 11/14/97, grant number : NAG 2-1042. [Washington, DC : National Aeronautics and Space Administration, 1997.
Trouver le texte intégral
8
Mota-Lopes, José da. The Colonial Encounter and Its Legacy. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190846626.013.324.
Texte intégralRésumé :
The current scholarship on European colonialism may be divided into two approaches: colonial studies, sometimes referred to as a political-economy approach, and postcolonial studies, also known as “postcolonialism” or “subaltern studies.” Whereas the field of colonial studies appeared with the emergence of colonialism, the second emerged with decolonization, the national liberation armed struggles, and the political, formal, or institutional collapse of colonialism. The two approaches became or appeared as protests against very similar circumstances and critically complemented one another, but they soon tended to follow parallel and very different trajectories. Three basic conceptual references offer important insights not only about the geostrategic, historical, and socioeconomic trajectories of colonialism but also on its cultural evolvement and its present consequences: colonial encounter, colonial situation, and colonial legacy. In addition, the field of colonial or postcolonial studies today may give rise to three major evolvements in the near future. The first consists in the recovery of what started to be the initial subject matter of postcolonialism. The second arises from the requirement of a return to the political, historical, and economic origins of postcolonialist studies. Finally, it will perhaps be at the point of conjunction of world-systems analysis with postcolonial studies that a fundamental problem affecting our world will find the beginning of a possible solution. The combined application of world-systems analysis and postcolonial studies is a promising intellectual instrument for confronting the in-depth influence of Eurocentrism or Euro-American universalism in the current practice and teaching of the social sciences.
9
Jutte, Jennifer E., James C. Jackson et Ramona O. Hopkins. Rehabilitation Psychology Insights for Treatment of Critical Illness Survivors. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199398690.003.0005.
Texte intégralRésumé :
This chapter discusses the role of rehabilitation psychologists in the care of the critically ill patient during and after a stay in intensive care unit (ICU). Since post-ICU cognitive impairments and psychiatric difficulties such as anxiety, depression, acute distress disorder, and post-traumatic stress disorder may not be preventable altogether, it is important to attempt to minimize long-term impairment and distress. Because of the thorough training rehabilitation psychologists receive in assessment and intervention practices in patients with a variety of complex medical conditions, rehabilitation psychologists are particularly well-suited to identify and address the complex post-ICU morbidities faced by critical illness survivors across the continuum of care environments. Interventions across settings to minimize delirium, reduce psychological distress, and shore up cognitive deficits could positively influence patients’ recovery trajectories and quality of life.
10
Herridge, Margaret S., et Jill I. Cameron. Models of Rehabilitative Care after Critical Illness. Oxford University Press, 2014. http://dx.doi.org/10.1093/med/9780199653461.003.0050.
Texte intégralRésumé :
Critical illness is transformative. Patients and caregivers are traumatized and acquire new mood disorders and disability. These are costly and consequential. Knowledge of current rehabilitation theory may help to inform emerging models of care for our critically ill patients and families. The International Classification of Functioning, Disability, and Health (ICF) model is presented as a candidate construct for patients and families after critical illness. It highlights the complexity and interdependence of factors that determine outcome and incorporates multiple facets of the individual experience. ICF may facilitate the development of a novel framework of aetiologically neutral clinical phenotypes with distinct recovery trajectories after critical illness. This informs tailored interventions for distinct patient and family groupings, independent of initial diagnostic groups, and acknowledges the similar themes of ICUAW, cognitive dysfunction, and mood disorders following complex critical illness.
Chapitres de livres sur le sujet "Descriptors of recovery trajectories"
1
Brown, Sandra A., Danielle E. Ramo et Kristen G. Anderson. « Long-Term Trajectories of Adolescent Recovery ». Dans Addiction Recovery Management, 127–42. Totowa, NJ : Humana Press, 2010. http://dx.doi.org/10.1007/978-1-60327-960-4_8.
Texte intégral
2
Joseph, Jacquleen, et Surinder Jaswal. « Trajectories of Recovery and Resilience ». Dans Centrifugal Disasters, 136–78. London : Routledge India, 2023. http://dx.doi.org/10.4324/9781003440345-7.
Texte intégral
3
Hall, Lauren. « Methods, Contexts, and Trajectories into Offending and Addiction ». Dans Trusting Recovery and Desistance, 30–52. London : Routledge, 2023. http://dx.doi.org/10.4324/9781003157472-3.
Texte intégral
4
Valiela, Ivan. « Changing Marine Ecosystems and Processes : Trajectories and Recovery ». Dans Marine Ecological Processes, 577–93. New York, NY : Springer New York, 2015. http://dx.doi.org/10.1007/978-0-387-79070-1_18.
Texte intégral
5
Mahmud, Noorfadzreena, et Xianhua Liu. « Optimizing Well Structures and Trajectories for Maximizing Oil Recovery ». Dans ICIPEG 2016, 783–93. Singapore : Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-3650-7_67.
Texte intégral
6
Vogt, Martin, et Jürgen Bajorath. « Statistical Methods for Predicting Compound Recovery Rates for Ligand-Based Virtual Screening and Assessing the Probability of Activity ». Dans Statistical Modelling of Molecular Descriptors in QSAR/QSPR, 229–43. Weinheim, Germany : Wiley-VCH Verlag GmbH & Co. KGaA, 2012. http://dx.doi.org/10.1002/9783527645121.ch8.
Texte intégral
7
Steger, Michael F., et Crystal L. Park. « The creation of meaning following trauma : Meaning making and trajectories of distress and recovery. » Dans Trauma therapy in context : The science and craft of evidence-based practice., 171–91. Washington : American Psychological Association, 2012. http://dx.doi.org/10.1037/13746-008.
Texte intégral
8
Kenney, Christine. « Ahi Kā Roa, Ahi Kā Ora Ōtautahi : Māori, Recovery Trajectories and Resilience in Canterbury, New Zealand ». Dans Population, Development, and the Environment, 375–94. Singapore : Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-2101-6_22.
Texte intégral
9
Spini, Dario, et Eric Widmer. « Introduction : Inhabiting Vulnerability Throughout the Life Course ». Dans Withstanding Vulnerability throughout Adult Life, 1–13. Singapore : Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-4567-0_1.
Texte intégralRésumé :
AbstractThis chapter presents the vulnerability framework used in the different sections chapters of this book. Vulnerability is defined as a process of resource loss in one or more life domains that threatens individuals in three major steps: (1) an inability to avoid individual, social or environmental stressors, (2) an inability to cope effectively with these stressors, and (3) an inability to recover from stressors or to take advantage of opportunities by a given deadline. The chapter also stresses the importance of resources, reserves and stressors to understand the dynamics of vulnerability throughout the life span. This life course perspective of vulnerability processes is better understood through three main perspectives: multidimensional (across life domains), multilevel (using micro, meso and macro perspectives) and multidirectional (the study of vulnerability life trajectories should envisage all possible directions, namely stability, decline, recovery, growth trajectories and in long-term). We also argue in this chapter that a vulnerability framework enables researcher to understand the craft of our lives and the responses, be they individual (through agency), collective (through support) or institutional (social policies) that can be given to life events, life transitions, and to the stressors that individuals inevitably face sooner or later in their life.
10
Solomon, Zahava, Avigal Snir, Henry Fingerhut et Michal Rosenberg. « Long-Term Trajectories and Recovery from PTSD ». Dans Long-Term Outcomes in Psychopathology Research, 188–204. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199378821.003.0011.
Texte intégralActes de conférences sur le sujet "Descriptors of recovery trajectories"
1
Litvak, Michael, Jacob Rosenzweig, Grant Marblestone, Sebastien Matringe et Pengju Wang. « Scenario Based Optimization Methodology for Field Development Planning ». Dans SPE EuropEC - Europe Energy Conference featured at the 84th EAGE Annual Conference & Exhibition. SPE, 2023. http://dx.doi.org/10.2118/214387-ms.
Texte intégralRésumé :
Abstract An innovative optimization methodology for field development planning is presented. A new mixed integer optimizer is described. The optimization tool's "user-friendly" plug-in in a commercial reservoir characterization and simulation package is developed, and methodology applications in exploration projects are outlined. An effective methodology is developed to optimize well placement and facility options in oil fields with multiple reservoirs. The optimized field development plan is selected for individual reservoirs from various well placements, well trajectories, injection strategies, and facility scenarios significantly impacting field oil recovery. Multiple subsurface models representing uncertainties in subsurface descriptions are applied in the optimization process. An effective mixed integer optimizer is developed. The optimizer is based on sequential cycles of a) selection of "promising" scenarios changing one decision variable per simulation and b) evaluations of combinations of the "promising" scenarios using Latin Hypercube sampling. The optimization workflow is implemented as a user-friendly plug-in to a commercial package, which allows one to a) define locations and trajectories of potential wells, b) define well placement and facility scenarios, c) run optimization workflows, and d) evaluate optimization results. The developed optimization methodology is successfully applied in several exploration projects. Effectiveness and significant benefits from the optimization applications are demonstrated. This paper can bring significant benefits to the state of knowledge in the petroleum industry by a) describing the novel methodology for optimizing field development scenarios that have significant impacts on oil recovery, b) applying the new optimizer, c) implementing the optimization plug-in in a commercial package.
2
Annoni, Ronald, et Carlos H. Q. Forster. « Analysis of aircraft trajectories using Fourier descriptors and kernel density estimation ». Dans 2012 15th International IEEE Conference on Intelligent Transportation Systems - (ITSC 2012). IEEE, 2012. http://dx.doi.org/10.1109/itsc.2012.6338863.
Texte intégral
3
Yakimenko, Oleg A., Douglas P. Horner et Douglas G. Pratt. « AUV rendezvous trajectories generation for underwater recovery ». Dans Automation (MED 2008). IEEE, 2008. http://dx.doi.org/10.1109/med.2008.4601975.
Texte intégral
4
Willett, Rebecca M. « Smooth sampling trajectories for sparse recovery in MRI ». Dans 2011 8th IEEE International Symposium on Biomedical Imaging (ISBI 2011). IEEE, 2011. http://dx.doi.org/10.1109/isbi.2011.5872580.
Texte intégral
5
Roberts, C., et R. Short. « Injection contingency recovery strategies for halo orbit transfer trajectories ». Dans Astrodynamics Conference. Reston, Virigina : American Institute of Aeronautics and Astronautics, 1996. http://dx.doi.org/10.2514/6.1996-3600.
Texte intégral
6
Saleh, Adel, Miguel Angel Garcia, Farhan Akram, Mohamed Abdel-Nasser et Domenec Puig. « Exploiting the Kinematic of the Trajectories of the Local Descriptors to Improve Human Action Recognition ». Dans International Conference on Computer Vision Theory and Applications. SCITEPRESS - Science and Technology Publications, 2016. http://dx.doi.org/10.5220/0005781001800185.
Texte intégral
7
Moon, Jaekyun, et Jaewook Lee. « GEN04-3 : Decision-Directed Timing Recovery Based on Maintaining Multiple Phase Trajectories ». Dans IEEE Globecom 2006. IEEE, 2006. http://dx.doi.org/10.1109/glocom.2006.163.
Texte intégral
8
Khan, Arbaaz, et Martial Hebert. « Learning safe recovery trajectories with deep neural networks for unmanned aerial vehicles ». Dans 2018 IEEE Aerospace Conference. IEEE, 2018. http://dx.doi.org/10.1109/aero.2018.8396807.
Texte intégral
9
« GRAPH MATCHING USING SIFT DESCRIPTORS - An Application to Pose Recovery of a Mobile Robot ». Dans International Conference on Computer Vision Theory and Applications. SciTePress - Science and and Technology Publications, 2010. http://dx.doi.org/10.5220/0002829702490254.
Texte intégral
10
Roy, Zachary, Sujit Subhash, Lien A. Bui, Bassam Hadi, Daniel B. Hier, Donald Wunsch, Gayla R. Olbricht et Tayo Obafemi-Ajayi. « Exploratory Analysis of Concussion Recovery Trajectories using Multi-modal Assessments and Serum Biomarkers ». Dans 2020 42nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) in conjunction with the 43rd Annual Conference of the Canadian Medical and Biological Engineering Society. IEEE, 2020. http://dx.doi.org/10.1109/embc44109.2020.9176527.
Texte intégralRapports d'organisations sur le sujet "Descriptors of recovery trajectories"
1
Nazneen, Sohela, Raihan Ahamed, Syeda Salina Aziz, Anuradha Joshi, Miguel Loureiro, Niranjan Jathavedan Nampoothiri, Jahid Nur, Nowshin Sharmila, Rabeena Sultana Ananna et Shahaduz Zaman. Being New Poor in Bangladesh : Coping Strategies, Constraints, and Trajectories. Institute of Development Studies, février 2024. http://dx.doi.org/10.19088/ids.2024.012.
Texte intégralRésumé :
Recent studies of the Covid-19 pandemic have found that millions in Bangladesh fell into poverty during this time, and they were unable to recover to their pre-pandemic economic position. This study draws on qualitative panel data collected from 39 new-poor households in Khulna, coping with pandemic-induced shocks and attempting to come out of poverty. How are the new poor attempting to recover: what strategies are they using and what constraints do they face? What are the implications for governance of their efforts? Based on their pre-pandemic economic conditions, we divide these new-poor households into two categories: those that were ‘never poor’ and ‘the vulnerable non-poor’ households. All the new-poor households we engaged with used a variety of strategies to cope and recover which included financial strategies such as borrowing money, livelihood strategies such as having multiple occupations, cost-reduction strategies such as decreasing expenditure on health and education, and social safety strategies such as accessing social protection. The main constraints that these households faced were many. These included their inability to access loans and access finances, limited access to social protection, lack of trust and expectations from the local government to provide services to aid their recovery, and social norms around honour and shame which limited their ability to seek assistance or have female members of the household engage in an income-generating activity. Most ‘never-poor’ households were recovering while most of the vulnerable households were stuck. Governance implications of the experiences of these households include the state playing a bigger role in supporting the new poor, limiting the role intermediaries and informal networks play in how social protection is provided, strengthening practices that build trust in local government, and tackling corruption.
2
Berkowitz, Jacob. Quantifying functional increases across a large-scale wetland restoration chronosequence. Engineer Research and Development Center (U.S.), août 2021. http://dx.doi.org/10.21079/11681/41500.
Texte intégralRésumé :
Over 300,000 ha of forested wetlands have undergone restoration within the Mississippi Alluvial Valley region. Restored forest successional stage varies, providing opportunities to document wetland functional increases across a large-scale restoration chronosequence using the Hydrogeomorphic (HGM) approach. Results from >600 restored study sites spanning a 25-year chronosequence indicate that: 1) wetland functional assessment variables increased toward reference conditions; 2) restored wetlands generally follow expected recovery trajectories; and 3) wetland functions display significant improvements across the restoration chronosequence. A functional lag between restored areas and mature reference wetlands persists in most instances. However, a subset of restored sites have attained mature reference wetland conditions in areas approaching or exceeding tree diameter and canopy closure thresholds. Study results highlight the importance of site selection and the benefits of evaluating a suite of wetland functions in order to identify appropriate restoration success milestones and design monitoring programs. For example, wetland functions associated with detention of precipitation (a largely physical process) rapidly increased under post restoration conditions, while improvements in wetland habitat functions (associated with forest establishment and maturation) required additional time. As the wetland science community transitions towards larger scale restoration efforts, effectively quantifying restoration functional improvements will become increasingly important.
3
Gage, Edward, Linda Zeigenfuss, Hanem Abouelezz, Allison Konkowski, David Cooper et Therese Johnson. Vegetation response to Rocky Mountain National Park’s elk and vegetation management plan : Analysis of 2008–2018 data. National Park Service, juin 2023. http://dx.doi.org/10.36967/2299264.
Texte intégralRésumé :
Rocky Mountain National Park (RMNP) developed the Elk and Vegetation Management Plan (EVMP) to address well-documented declines in the ecological condition of aspen stands and riparian communities from high levels of elk herbivory. The EVMP aims to reduce the impacts of elk on vegetation and restore the natural range of variability in the elk population and affected plant communities, including preventing the loss of aspen clones within high elk-use areas, restoring montane riparian willow cover and height within suitable habitat, and reducing of levels of elk grazing on herbaceous vegetation. The EVMP described a range of management actions including reductions in the size of the elk herd and the installation of fencing to reduce herbivory levels and facilitate recovery in degraded communities. The EVMP established a monitoring protocol in focal communities to assess progress towards these vegetation goals and facilitate adaptive management. RMNP has collected data quantifying biomass offtake in upland herbaceous and riparian communities, willow height and cover, and aspen stand structure and regeneration periodically since implementation of the plan began in 2008. This report summarizes the results of analyses of EVMP data collected from 2008–2018, the last year comprehensive measurements were made. The EVMP was developed with a focus on the primary elk winter range in the upper montane zone on the east side of RMNP. The plan distinguishes core elk winter range, where elk concentrate during winter, and noncore winter range areas that typically have less elk use. Data were also collected in the Kawuneeche Valley in the headwaters of the Colorado River on the west side of the park, an area supporting extensive wet meadows and areas once dominated by willow. Data were also collected to investigate the effects of wildland fires that burned through the winter range in 2012 to determine the potential for using fire as a management tool to achieve EVMP goals. The overwintering elk population in the park has declined, from its peak of 1,500 animals in 2001, and over the course of EVMP implementation, from 614 animals in 2009 to 124 animals in 2019. Declines in the overwintering elk population may be best explained by increased cow elk harvest outside of the park, and, most notably, by a change in seasonal migration patterns and habitat use that have elk moving to lower elevation wintering areas following the fall rut. In sites in aspen communities, stand structure was changed little or declined across sampling periods in unfenced plots with continued patterns of little regeneration and recruitment and steady progression toward stands dominated by large-diameter trees. However, there was a progression towards taller sapling heights inside fenced plots and recruitment of small diameter tree-sized stems. Fencing had large and positive effects on aspen stand structure, with different patterns observed in fenced and unfenced core winter range and noncore winter range. Increased recruitment was observed across the winter range but occurred mainly inside fenced plots. Aspen stem counts varied between time periods and in relation to wildfire, with fenced and burned plots on the core winter range having higher stem counts by 2018 than unfenced and unburned plots. Willow height and cover increased over time in sampled sites, but positive trends were generally restricted to sites in fenced areas. Willow height also increased on noncore (all unfenced) winter range sites. Willow in unfenced core winter range sites had only minor increase in height from baseline (2008 for most sites) to 2018, but willow in fenced plots had greater height increases over the same time period. Noncore winter range willow sites had modest height increases over the 10-yr period. Mean willow cover increased nearly 5-fold compared to baseline conditions within the core winter range fenced areas and roughly 1.5-fold in noncore winter range. Willow cover was greater in unfenced than fenced plots at baseline, but the pattern was reversed in 2013 and 2018. The highest cover occurred in 2018 in fenced core winter range plots (mean = 70.8%) and unfenced noncore winter range plots (mean = 68.6%). Mean cover increased from 14.6% at baseline to 25.3% in 2013 and 70.8% in 2018 in fenced core winter range plots. Mean willow cover changed little in unfenced core winter range plots between baseline and 2018, although the range of cover values increased over time, and willow cover increases were modest in the noncore winter range. Fencing reduced or eliminated browsing from plots located inside fences, but offtake varied widely among unfenced plots. Patterns of willow browse intensity differed management subgroups (e.g., core and noncore winter range), and generally showed a downward trend between baseline and 2018 measurements. Herbaceous offtake in upland communities was measured in the first sample period (baseline–2013) to assess levels of grazing on herbaceous vegetation, however it was determined that the associated EVMP objectives had been achieved so measurements were discontinued after 2013. Continued monitoring of upland shrubs indicated no shift from herbaceous dominated to shrub dominated communities after 2013. Noncore upland plots had higher shrub cover than core winter range plots across all time periods, but most differences between year and core/noncore had low probability of effect. Cover for individual species varied over time and winter range plots. Moose presence has increased in winter range aspen and willow sites over the past decade, while beaver presence at our monitoring sites has decreased. Results indicate that RMNP is making progress toward the vegetation objectives set out in the EVMP, however positive trends were most pronounced in plots protected from ungulate herbivory through fencing. Aspen recruitment was greatest in fenced plots. Likewise, trajectories of willow height and cover were positive in fenced winter range plots. Results demonstrate that fencing is an effective means of improving condition in aspen and willow habitats. Changes outside the fences were slower and less pronounced than inside the fences, however, the positive (if small) increases in willow height and cover and aspen regeneration as well as decreases in upland herbaceous offtake, indicate that decreased wintering elk populations are also contributing to improvement of habitat conditions on the elk winter range. In the Kawuneeche Valley, which has not traditionally been heavily used by overwintering elk but does experience summer elk and moose use, poor and declining habitat condition were recorded in unfenced willow and aspen sites.