Macroscopic changes in the urban environment and in the built transportation infrastructure, as well as changes in household demographics and socio-economics, can lead to spatio-temporal variations in household travel patterns and therefore regional travel demand. Dynamics in travel behavior may also simply arise from the randomness associated with values, perceptions, attitudes, needs, preferences and decision-making process of the individual travelers. Most urban travel behavior models and analysis seek to explain variations in travel behavior in terms of characteristics of the individuals and their environment. Spatial extents and temporal variation in an individual’s travel pattern may represent a measure of the individual’s spatial appetite for activity and the variability-seeking nature on his/her travel behavior. The objective of this dissertation effort is to develop a methodology to predict activity participation using revealed spatial extents and temporal variability as variables that represent the spatial appetite and variability-seeking nature associated with individual household. Activity participation is defined as a set of activities in which an individual or household takes part, to satisfy the sustenance, maintenance and discretionary needs of the household. To accomplish the goals of the dissertation, longitudinal travel data collected from the Commute Atlanta Study are used. The raw Global Positioning Systems (GPS) data are processed to summarize trip data by household travel day and individual travel day data. A methodology was developed to automatically identify the activity at the end of each trip. Methods were then developed to estimate travel behavior variability that can represent the variability-seeking nature of the individual. Existing methods to estimate activity space were reviewed and a new Modified Kernel Density area method was developed to address issues with current methods. Finally activity participation models using structural equation modeling methods were developed and the effects of the variability-seeking nature and spatial extent of activities were applied to the models. The variability-seeking nature was presented in the activity participation model as a latent variable with coefficient of variation of trips and distance as indicator variables. The dissertation research found that inclusion of activity space variables can improve the activity participation modeling process to better explain travel behavior.

Made available in DSpace on 2016-04-29T13:18:13Z (GMT). No. of bitstreams: 1 Juliana Palma de Godoi.pdf: 4995394 bytes, checksum: 780487c4d021adc42c630ce043f4018b (MD5) Previous issue date: 2009-05-27 / The purpose of this study was to reinforce behavior variability at the responses of children with developmental disabilities, and test its extension to other tasks. After baseline, the variability was reinforced with fading of the variability exigency. Following, the extension of the acquired variability to other tasks was tested. The latest fading level and the extension tests were remaked. Two participants presented high variability at the baseline, it was reduced by the continuous reinforcement and recovered by the variability s direct reinforcement. The other participants had increase at the variability s rate. There was extension of the variability to the task topographically similar to the experimental task. The variability reinforcement can contribute to teaching children with developmental disabilities / Objetivou-se reforçar a variabilidade comportamental em respostas de crianças com desenvolvimento atípico e testar sua extensão para outras tarefas. Após a linha de base, reforçou-se o variar com fading da exigência de variabilidade. Em seguida, testou-se a extensão da variabilidade adquirida para outros jogos. O último nível do fading e os testes de extensão para outras tarefas foram feitos novamente. Dois participantes apresentaram variabilidade alta na linha de base, esta foi reduzida pelo reforçamento contínuo e recuperada pelo reforçamento direto do variar. Os demais participantes tiveram aumento nos índices de variabilidade. Houve extensão da variabilidade para a tarefa topograficamente semelhante à experimental. O reforçamento do variar pode contribuir para o ensino de crianças com dificuldades de aprendizagem

The purpose of this study was to compare response rates and resistance to extinction in single-task and multiple-task phases. Research was conducted with thirty undergraduate college students in a controlled experimental setting. Each Participant was exposed to 4 treatment phases: single-task, fixed-ratio of one (ST-FR1), multiple-task fixed-ratio of one (MT-FR1), single-task fixed-ratio of 5 (ST-FR5) and multiple-task fixed-ratio of 5 (MT-FR5) all beginning with a baseline phase and reverting back to baseline after the first two conditions were presented. Half of the Participants received the single-task phase first, and the other half received the multiple-task phase first, in order to observe the behavior in transition. A trials-to-criterion measure was used to determine how long it took each Participant’s behavior to adapt to the new contingency in the next phase, which was presented without any signal. The data reveal that regardless of the order of phase presentation it took Participants more than twice as long to reach the criterion in the single-task phases, than in the multiple-task phases.

L'érosion hydrique touche près de 3 millions d'hectares des sols agricoles en Tunisie, et constitue une menace pour la durabilité des retenues collinaires destinées à mobiliser les eaux de surface. La très forte densité des systèmes ravinaires en Tunisie, comme dans bon nombre de régions méditerranéennes, pose la question de leur rôle dans le comblement des retenues. Dans ce contexte, l'objectif général de ce travail de thèse est de proposer une méthodologie qui permette d'évaluer la contribution relative de l'érosion ravinaire (ravines/oued) et de l'érosion de surface (diffuse/ rigoles) dans les flux de sédiments à l'exutoire des petits bassins versants (0,1-10 km²) sur des périodes d'observations suffisamment longues (une quinzaine d'année). La démarche proposée s'appuie sur la méthode de traçage des sources de sédiments développée par Walling (1999), et consiste à exploiter le caractère stable de certains éléments pour discriminer les sources de sédiments accumulés dans les retenues collinaires. Les différentes étapes de cette approche consistent en : i) l'identification des traceurs potentiels; ii) l'analyse de ces traceurs dans les échantillons «source» et dans les carottes prélevées dans les sédiments de la retenue; iii) l'application d‘un modèle de mélange associé à un modèle de Monte Carlo. Les résultats de cette méthode de traçage testée prioritairement sur un bassin versant expérimental (Kamech) ont été par la suite validés par deux approches indépendantes d'estimation des volumes de terres érodés. Sur Kamech, les résultats montrent la prédominance de l'érosion de surface qui représente près de 80% de l'érosion totale dont le taux moyen atteint 15 t/ha/an. Cette application a également permis de dégager des recommandations concernant la stratégie d'échantillonnage des carottes au sein des sédiments piégés dans les retenues collinaires pour limiter les incertitudes liées à l'échantillonnage. La méthode a ensuite été appliquée à quatre autres bassins versants choisis pour représenter au mieux la diversité des paysages de la Dorsale Tunisienne et du Cap Bon. La comparaison des résultats pour les cinq bassins versants étudiés montre une large variabilité des comportements érosifs : trois bassins montrent une prédominance de l'érosion de surface et nécessitent la mise en place de pratiques culturales protectrices de la ressource en sol alors que les deux autres bassins sont dominés par l'érosion ravinaire et nécessitent de recourir prioritairement à des mesures structurelles telles que des aménagements de ravines. Ces différences de comportements érosifs entre bassins ont été confrontées aux caractéristiques des sites en vue de fournir des clés de prédiction.Mots clefs : Erosion ravinaire. Erosion de surface. Bassins versants. Retenues collinaires. Traçage des sources de sédiments. Télédétection. Tunisie. / Water erosion affects nearly 3 million hectares of agricultural soil in Tunisia, and presents a threat to the sustainability of reservoirs to store surface waters. The high density of gully systems in Tunisia, like in many Mediterranean regions, raises the question of their role in the siltation of reservoirs. In this context, the objective of this thesis is to propose a methodology for evaluating the relative contribution of gully erosion (gullies/channel) compared to surface erosion (rill and interrill) in sediment fluxes at the outlet of small catchments (0.1-10 km ²), for pluri-annual periods (about 15 years). The proposed approach is based on the method of fingerprinting sediment sources developed by Walling et al. (1999), and takes advantage of the stable nature of certain elements to discriminate the origin of sediment trapped in reservoirs. The different steps of this approach consist in i) the identification of potential tracers adapted to the objectives of the study, ii) the quantification of these tracers in sources samples and in sediment cores, iii) the application of a mixing model combined with a Monte Carlo model. The results of this fingerprinting approach primarily tested on the Kamech experimental catchment were subsequently validated using eroded soil volumes estimated by two independent approaches. The results for this catchment show the dominance of surface erosion which represents nearly 80% of the 15 t/ha/year of total erosion. In addition, guidelines for method application have been proposed, including the implementation of a core sampling strategy which limits the level of uncertainty to less than 10%. The method was then applied to four other catchments representative of the diversity of the Tunisian Dorsal and Cape Bon landscapes. The comparison of the results for the five studied catchments shows a wide variability of erosion behaviour. Surface erosion is the dominant process in three catchments which require the establishment of protective cultivation of the soil resource. The two other catchments are dominated by gully erosion and require the priority use of structural measures such as improvements of gullies and bank channel protection. These differences between catchments have been related to the characteristics of the sites in order to identify predictive factors.Keywords: Gully Erosion. Rill and Interrill Erosion. Catchments. Reservoirs. Sediment Fingerprinting. Remote Sensing. Tunisia.