Background and Purpose: The adverse effects of drugs may influence results on tests of mobility and balance, but the drug-specific impact is not identified when using these tests. We propose that a quantitative drug index (QDI) will assist in assessing fall risk based on these tests, when combined with other fall risk variables. Methods: Fifty-seven community-dwelling older adults who could walk independently on a treadmill and had Mini-Mental State Examination (MMSE) scores equal to or greater than 24 participated. Mobility and balance outcome measures included the Balance Evaluation Systems Test (BESTest), Berg Balance Scale (BBS), Timed Up and Go (TUG) and cognitive dual task TUG (TUGc). Fall history, current drug list, and Activity-Specific Balance Confidence (ABC) scale scores were also collected. Body mass index (BMI) was calculated. The QDI was derived from the drug list for each individual, and based on fall-related drug adverse effects. Multiple linear regression analyses were conducted using age, BMI, and QDI as predictor variables for determining mobility and balance test scores, and ABC scale scores. Subsequently, participants were divided into (QDI = 0) low-impact drug group (LIDG) and (QDI > 0) high-impact drug group (HIDG) for Mann-Whitney 2-group comparisons. Results: Age, BMI, and QDI were all significant (P <.001) independent variables in multiple regression analyses for mobility and balance test scores, but not for the ABC scale. Separately, the 2 group comparisons for the BESTest, BBS, TUG, and TUGc demonstrated that HIDG scored significantly (P <.05) worse on these tests compared with the LIDG. Drug counts were also significantly higher for the HIDG than for the LIDG. In contrast, age, BMI, MMSE, and reported falls in the last 12 months were not significantly different between groups. Conclusion: Age, BMI, and QDI - all contributed independently to the mobility and balance test scores examined, and may provide health care professionals a screening tool to determine whether additional mobility and balance testing is required. In addition, the QDI is a more precise marker of adverse effects of drugs compared with drug counts, as the latter does not quantitate the influence of drugs on physiologic function.

Gels are colloidal states of matter in which a solid matrix is dispersed in a liquid phase. Supramolecular gels are formed due to the self-assembly of small gelator molecules in a suitable solvent as a result of specific weak non-covalent interactions between the gelators. The last several decades have witnessed an upsurge in research activities in the area of supramolecular gels not only for academic interests but also for applications in material science. Gels have been investigated as potential avenues for drug delivery and oil recovery applications. Despite their huge potential, the properties of gels are discovered through trial-and-error approaches, which makes control of properties a challenging task. The control becomes extremely hard in a multicomponent gel system, which is a common model for applications in material science. The aim of this thesis is to design a pathway to gain a fundamental understanding on how multiple components in the gel contribute to new properties. This pathway is an attempt to move away from trial-and-error approaches for the development of gels and allows us to make correlations between structure, dynamics and function. The studies reported in this thesis were performed on a two-component gel system comprising a gelator and an additive. The gelator, sodium deoxycholate (NaDC), is a bile salt known for its ability to form a supramolecular gel within a certain pH range. NaDC gels are made up of aggregates distributed between the aqueous phase and the gel structure. NaDC gels are reversible and considered as promising candidates from a functional point of view. The additive, cucurbit[6]uril (CB[6]), is a macrocycle and is known to affect the mechanical properties of NaDC gels at the macroscopic level. In the first project, I studied the effect of CB[6] on the NaDC gel at the microscopic level using dynamic light scattering and fluorescence microscopy experiments. These techniques were used to determine the effect of CB[6] on the gel’s morphology, size of NaDC aggregates, thermo-reversible properties of NaDC gels and the kinetics of NaDC gel formation. My results showed that the effect of CB[6] on NaDC aggregates begins in solutions and is translated to sols and gels. Thermo-reversibility and kinetic studies showed that the effect of CB[6] on NaDC gels goes beyond changes to the gel’s structure and CB[6] was also shown to affect both the gel-sol transition temperatures and time of the gel formation. In the second project, I studied how the release of dyes of different hydrophobicities from NaDC gels was affected by the addition of CB[6]. The release of the dyes pyrene and rhodamine 6G was investigated using a static diffusion method, which was referred to as the top layer method. My results showed that CB[6] has a different effect on the release kinetics of a hydrophilic dye compared to the release of a hydrophobic dye. The observed difference in the release kinetics was attributed to differences in the localization of the dyes in NaDC gels and the role of CB[6] in affecting the distribution of dyes in different regions in the gel. In the third project, I studied the colocalization of a hydrophobic and a hydrophilic dye in NaDC-CB[6] gels with the goal to confirm my hypothesis from the release studies. Dynamics of diffusion of dyes within NaDC-CB[6] gels was investigated using the fluorescence recovery after photobleaching (FRAP) technique. Results from colocalization experiments showed that the addition of CB[6] changes the distribution of hydrophilic dye in the gel. Through colocalization experiments, I was able to showcase the active role of CB[6] in incorporating aggregates from the aqueous phase into the gel structure. Results from FRAP studies showed that, in the presence of CB[6], recovery after bleaching of a hydrophobic dye in the gel structure is slower compared to the dye in the NaDC gel structure. / Graduate

Hip fracture in older adults may be the sentinel event leading to functional decline, long-term disability, and death. For the substantial number of older persons who fracture a hip each year, the chances of full functional recovery remains relatively low. The purpose of this study was to examine the differences between older persons with hip fracture who recover fully and those individuals who do not fully recover. A chronic disease trajectory framework guided the theoretical design of the research. Data were collected from the medical records of 102 persons aged 60 years and older who sustained a proximal hip fracture from 1993 to 1998 at a medical center in North Carolina. Data included personal characteristics, prefracture health status, hospital factors, rehabilitation features, and functional outcomes. The analysis consisted of a two-step hierarchical logistic regression model with the control variables of age, prefracture ambulation status, and prefracture cognitive status entered first and the variables of type of therapy program, frequency of therapy, number of therapy provider organizations, and location of therapy at 4 weeks entered second. Significance of the final model was observed, Chi-Square(7, n = 99)=43.55, p < .05. Significant individual predictors (p < .05) in the model were prefracture ambulation status (43.56 odds ratio) and cognitive status (6.44 odds ratio). Post-hoc analysis of the cases revealed a substantial lack of stability in ambulation status from three months post-fracture to the six-month and one-year follow-up. Findings support other research studies that indicate prefracture personal characteristics of older persons who fracture a hip are the most influential factors in predicting successful recovery. Linkage of the findings to the chronic disease trajectory model suggests that intervention efforts should focus on prevention, health promotion, and policies that extend the ability of health care providers to assist older persons with hip fracture in managing their conditions. / Ph. D.

Although smart mobile devices have only come into prominence recently, they have quickly become a necessity in the modern world. In 2012, more than 450 million new smartphones are expected to be purchased around the world, exceeding, for the first time, purchases of laptops and desktop PCs combined in a single year. That, in addition to the increasing processing power and low cost of these emerging mobile devices, creates an increasing demand for mobile applications that work in infrastructure-supported environments like WiFi and cellular networks as well as infrastructure-less environments like ad hoc networks. Therefore, the behavior of mobile devices in such scenarios should be a continued focus of research. Several factors contribute to the observed behavior of nodes in Mobile Ad-hoc Networks MANETs. For example, nodes may act selfishly to preserve their limited energy resources. This selfishness may be detrimental to network performance. Therefore, cooperation between peers is necessary to keep these MANETs operational. Beside the need for actively encouraging cooperation by providing incentives, passive encouragement is also needed to overcome the effect of factors that limit cooperation, including malicious behavior, environmental obstruction, and mobility. The contribution of this work is to provide a cooperation model in MANETs that is capable of surviving topology distortions caused by mobility, and is operable in practical distributed scenarios. Towards this goal, we first provide a study of the topology characteristics of MANETs based on real experiments. We study the node degree, link stability, and link symmetry of these networks, and, based on our observations, we suggest a two-state Markov model to model link state in such networks, demonstrating the superiority of this model over the widely-used disk model with mobility. We conclude from this study that both mobility and channel fluctuations have a significant influence on the network topology, which makes it important to study cooperation in scenarios where the topology is changing rapidly. Based on experimental observations of a real network, we propose a coalition game model for cooperation in MANETs that shows that stable, effective coalitions can be maintained, even in the face of a dynamic network topology. We provide an initial evaluation of the model using a centralized simulation approach. We use the notion of reachability to evaluate the proposed model, and we simulate the model under different speeds and node densities. Our simulations show that reachability can be sustained at stable levels despite the deterioration caused by mobility. In addition, we show that our cumulative coalition formation approach gives good results in terms of reachability level and computational complexity. We also show that our proposed model achieves a fair payoff distribution among participating nodes. Motivated by the promising results of our centralized simulation approach, we take a further step towards more practical evaluation. We integrate the cooperation model with an existing MANET routing protocol, OLSR, and evaluate it in this distributed environment. We modify and augment the OLSR messaging mechanism to enable the exchange of the coalition information required to keep the model operating. Beside ensuring that the reachability gain is still attained and the coalition structure is stable, we study the effect of the extra control traffic overhead incurred by the model. We compare deliverability over the network with and without the cooperation model. Although our results show that the cooperation model incurs an average overhead exceeding $100\%$ of that incurred by OLSR in high density scenarios, it shows better reliability in delivering traffic especially among selfish nodes in low and average density scenarios. Counter to what is commonly assumed in the literature, this study shows that cooperation can be be maintained in a distributed manner without causing significant traffic overhead to MANETs run by proactive routing protocols. Due to the simplicity, several extensions can be applied to enhance the performance of the proposed model and diversify its usage. We propose these extensions at the end of this dissertation. / Ph. D.

Divorce is a life course event that triggers deviant, negative residential moves that symbolises the antithesis of climbing the traditional housing ladder, and sets individuals on an altered housing trajectory, typically associated with long-term instability compared to married counterparts. Studies have revealed that long-term instability associated with divorce is commonly connected to an increased probability of moving out of owner occupation that is greater and persists longer for women than men. Similarly, studies examining the immediate effects of divorce typically identify that women have a higher risk of moving out of the matrimonial home at the time of separation. No studies found have examined the time taken for divorcing individuals to assume their new altered housing trajectories. This study aims to develop an understanding in this regard by examining gendered differences in the time taken for individual mobility rates to assume their new housing trajectory, and considering what effects urbanisation has on divorce-induced mobility. Using the Swedish LISA database, groups of divorcing single parents with cohabiting children under 18 are compared to similar long-term divorcees whom are conceptualised to represent the post-divorce altered housing trajectory. Noteworthy findings include: 1) Divorce-induced mobility at the time of separation decays one year after divorce for Rural and Urban male groups, at which time the new housing trajectory was assumed. 2) The decay time for Big City males was four years. 3) The decay time for Urban females was four years, while Rural and Big City female groups remained at an elevated mobility state for all four years observed post-divorce. 4) Degree of Urbanisation has a significant impact for women, mobility was highest in Rural groups and lowest in Big City groups. However, no such effect is observed for males. This study is important to municipalities and urban planners because the findings presented here concerning gendered and regional impacts on mobility are relevant to forecasting housing demand. Moreover, national planners are concerned with regional inequalities and the finding that degrees of urbanisation has a mobility association for females, but not males, is interesting in light of Sweden’s rural development and gender equality goals.

In the mobile era, data capturing individuals’ locations have become unprecedentedly available. Data from Location-Based Social Networks is one example of large-scale user-location data. Such data provide a valuable source for understanding patterns governing human mobility, and thus enable a wide range of research. However, mining and utilizing raw user-location data is a challenging task. This is mainly due to the sparsity of data (at the user level), the imbalance of data with power-law users and locations check-ins degree (at the global level), and more importantly the lack of a uniform low-dimensional feature space describing users. Three latent feature models are proposed in this dissertation. Each proposed model takes as an input a collection of user-location check-ins, and outputs a new representation space for users and locations respectively. To avoid invading users privacy, the proposed models are designed to learn from anonymized location data where only IDs - not geophysical positioning or category - of locations are utilized. To enrich the inferred mobility patterns, the proposed models incorporate metadata, often associated with user-location data, into the inference process. In this dissertation, two types of metadata are utilized to enrich the inferred patterns, timestamps and social ties. Time adds context to the inferred patterns, while social ties amplifies incomplete user-location check-ins. The first proposed model incorporates timestamps by learning from collections of users’ locations sharing the same discretized time. The second proposed model also incorporates time into the learning model, yet takes a further step by considering time at different scales (hour of a day, day of a week, month, and so on). This change in modeling time allows for capturing meaningful patterns over different times scales. The last proposed model incorporates social ties into the learning process to compensate for inactive users who contribute a large volume of incomplete user-location check-ins. To assess the quality of the new representation spaces for each model, evaluation is done using an external application, social link prediction, in addition to case studies and analysis of inferred patterns. Each proposed model is compared to baseline models, where results show significant improvements.

There are over 13 million children and adolescents in poverty in the United States today. These children and adolescents are likely to remain poor throughout their life, and are less likely to be upwardly mobile than their middle-income peers. Although structural change is needed in order to redress economic immobility on a large scale, informal mentoring may be one small person-level intervention that can help promote mobility. Informal mentoring (positive relationships with caring non-parental adults), has already been associated with key building blocks to economic success, including educational attainment and early employment. This dissertation is the first study to examine if informal mentors can promote economic mobility for adolescents, asking (1) is informal mentorship associated with upward mobility? and (2) do some mentoring relationships promote upward mobility more than others? This study uses data from three waves of the National Longitudinal Study of Adolescent Health (AddHealth). Research Question 1 uses propensity score matching to isolate the effect of informal mentoring on economic mobility, both for low-income and middle-income youth as a comparison. Research Question 2 uses cluster analysis and a series of logistic regressions to determine (a) types of informal mentoring relationships and (b) whether some types better promote economic mobility for low-income youth. Findings from this dissertation demonstrate that some, but not all, informal mentors can promote economic upward for low-income youth. Simply having a mentor did not promote mobility for low-income youth. In order to be upwardly mobile, they needed to have a "capital" mentor, i.e., someone who comes from outside their immediate social circle and connects them to other important relationships and resources. These are in contrast with "core" mentors, long-standing, important relationships from within the family that provide emotional support. This dissertation shows that some mentors can, in fact, make a difference for low-income adolescents' economic outcomes in adulthood. Low-income youth, however, were less likely to have an informal mentor, and only 45% of those who were mentored had the type that could promote mobility. Findings from this dissertation suggest that those who are interested in promoting economic mobility for low-income youth should thus promote capital mentoring relationships. / 2021-06-04T00:00:00Z

The purpose of this study is to understand how prehistoric people moved around the landscape and used major stone tool resources throughout the last 10,000 yr. B.P. in southern Idaho. Similar research has been reported in the Great Basin and western Wyoming and this study continues to fill the map with data about how large regions of the western United States were used prehistorically. This study specifically examined whether or not prehistoric mobility changed according to wet and dry climatic shifts. Based on these shifts archaeologists expect the regions people used to expand or shrink using an economic model of decision-making when foragers were confronted with the choice to stay in one resource area or move to another while pursuing plants and animals for food. To measure this decision prehistorically, obsidian projectile points and tools left behind throughout time were analyzed to determine where the stone originated geologically, a concept known as conveyance. The data were gathered from many regional studies and new sourcing of 139 artifacts from southeastern Idaho regional collections and excavations at the Fox Site near Thatcher, Idaho. In the compiled dataset are 4,440 artifacts from 640 archaeological sites in southern Idaho that originate from 37 obsidian sources. Analysis of this dataset grouped archaeology sites based on the percentage of different obsidian sources used, creating conveyance zone sets that were encompassed by statistically created ovals in mapping software. Four trans-Holocene conveyance zones are proposed and described: the Malad Conveyance Zone (MCZ), Timber Butte Conveyance Zone (TBCZ), Big Southern Butte Conveyance Zone (BSBCZ), and Snake River Conveyance Zone (SRCZ). These zones are then separated into four wet or dry climate periods and changes in mobility are compared to the economic decision model. Overall the MCZ and TBCZ both met the expectations of the model, while the BSBCZ and SRCZ did not. Another test of the data reveals that the number of obsidian sources used and the evenness of their use is not correlated with conveyance zone size, which helps confirm that these zones reproduce prehistoric behavior and are not a statistical product of the availability of obsidian in a region. The conveyance zones described in this study are comparable in size to those proposed in neighboring regions. Research also finds that southern Idaho conveyance zones were firmly established in the Early Holocene and shows that conveyance zones can be created from large datasets in a statistically robust manner and enable researchers to look at changes in forager mobility across large spatial and temporal scales. Expectations for forager mobility are partially supported by the variability wet and dry climate during the last 10,000 years B.P.

Cette thèse invite à mieux comprendre les enjeux autour du développement des projets innovants de transports intégrés dans les territoires, souvent caractérisés d’écomobilité. Par la réalisation de nouveaux comportements pour les usagers, mais aussi par de nouvelles relations entre acteurs, à la fois usagers, entreprises et collectivités, ces projets invitent à repenser dans une perspective plus large les logiques de performances et d’évaluation. Les outils traditionnels utilisés dans le champ économique ne semblent pas suffisamment saisir la complexité inhérente à ces programmes, il est donc opportun de développer de nouvelles pistes davantage orientées dans une approche ouverte et pluridisciplinaire. Pour cela, nous appuierons notre réflexion par le croisement entre deux programmes situés dans les Yvelines. En effet, ce territoire semble le terreau de nombreuses initiatives au cours des dernières années. Les résultats obtenus à l’issue d’un travail de terrain ayant permis de rencontrer un large panel d’acteurs, permettront d’améliorer le champ des connaissances de ces programmes émergeants et de tirer des enseignements dans le cadre de futurs projets. / This thesis calls for a better understanding of the challenges surrounding thedevelopment of innovative integrated transport projects in the territories, oftencharacterized by eco-mobility. By implementing new behaviors for users, but also bycreating new relationships between actors, both users, companies, and local authorities, these projects call for a rethinking of the logics of performance and evaluation in a broader perspective. The traditional tools used in the economic field do not seem to grasp sufficiently the complexity inherent in these programs, so it is appropriate to develop new perspectives more oriented in a multidisciplinary approach.For this, we will support our reflection by crossing two programs located in the Yvelines area. Indeed, this territory seems to be the breeding ground for many initiatives in recent years. The results obtained from a fieldwork meeting with a wide range of stakeholders will help to improve the knowledge base of these emerging programs and to draw lessons for future projects.

Avec l'avènement des systèmes basées sur la position, les systèmes d'aide au positionnement doivent répondre à de nouvelles exigences sécuritaires: authentifier la positon géographique annoncée par un utilisateur avant qu'il lui soit octroyé accès à une ressource géolocalisée. Dans cette thèse, nous nous intéressons à l'étude de protocoles de sécurité pouvant garantir l'authenticité de la position annoncée par un utilisateur sans la disponibilité au préalable d'une architecture de confiance. Un premier résultat de notre étude est la proposition d'un protocole délimiteur de distance basée sur la cryptographie asymétrique permettant à un noeud possédant une clé publique d'authentifier la partie détentrice de la clé privée associée, tout établissant une mesure de confiance sur la distance les séparant. La mesure de distance est résistante aux attaques par relais, par distance et aux attaques terroristes. Nous utilisons ensuite ce premier ré! sultat de recherche afin définir une architecture générique pour la collecte de preuves de localisation respectueuses de la vie privée. Nous définissons une preuve de localisation comme étant un certificat numérique attestant de la présence effective d'un individu à une position géographique à un instant donné. Les propriétés de la vie privée que nous garantissons par le biais de notre système sont: l'anonymat des utilisateurs, la non-chaînabilité de leurs actions à l'intérieur du système et une liaison forte entre chaque utilisateur et la preuve de localisation qui lui est associée. De plus, les preuves récoltées peuvent servir à prouver différentes granularité de la position associée. / With the advent of Location-Based-Systems, positioning systems must face new security requirements: how to guarantee the authenticity of the geographical positon announced by a user before granting him access to location-restricted! resources. In this thesis, we are interested in the study of ! security ! protocols that can ensure autheniticity of the position announced by a user without the prior availability of any form of trusted architecture. A first result of our study is the proposal for a distance-bounding protocol based on asymmetric cryptography which allows a node knowing a public key to authenticate the holder of the associated private key, while establishing confidence in the distance between them. The distance measurement procedure is sufficently secure to resist to well-known attacks such as relay attacks, distance-, mafia- and terrorist-attacks. We then use such distance-bounding protocol to define an architecture for gathering privacy friendly location proofs. We define a location proof as a digital certificate attesting of presence of an individual at a location at a given time. The privacy properties we garanty through the use of our system are: the anonymity of users, un-linkability of their actions within the system and a strong binding between each user ! and the localization proof it is associated. on last property of our system is the possibility to use the same location proof to demonstrate different granularity of the associated position.