Let G be a graph and k be an integer greater than or equal to the chromatic number of G. The k-colouring graph of G is the graph whose vertices are k-colourings of G, with two colourings adjacent if they colour exactly one vertex differently. We explore the Hamiltonicity and connectivity of such graphs, with particular focus on the k-colouring graphs of complete multipartite graphs. We determine the connectivity of the k-colouring graph of the complete graph on n vertices for all n, and show that the k-colouring graph of a complete multipartite graph K is 2-connected whenever k is at least the chromatic number of K plus one. Additionally, we examine a conjecture that every connected k-colouring graph is 2-connected, and give counterexamples for k greater than or equal to 4. As our main result, we show that for all k greater than or equal to 2t, the k-colouring graph of a complete t-partite graph is Hamiltonian. Finally, we characterize the complete multipartite graphs K whose k-colouring graphs are Hamiltonian when k is the chromatic number of K plus one. / Graduate

The recorded music industry experienced declining revenue from 1998 to 2014, but it saw a return to growth in 2015. This thesis uses a sample of 17 countries to explore the determinants behind this revenue expansion, and to assess whether this sales growth can be sustained. I examine the impact of eight factors on the overall, physical, digital, and streaming music revenue and revenue per capita, as well as the digital and streaming revenue share. The eight independent variables include the GNI per capita, the total population, the percentage of the young people, the percentage of the young females, the gross enrollment rate in secondary education, the percentage of Internet users, the percentage of mobile cellular subscriptions, and the percentage of fixed broadband subscriptions. Based on my study, the fixed broadband subscription rate has an impact that is both statistically significant and economically important on the streaming revenue share, which makes it the most important indicator for the industry’s potential sustainable development. The percentage of the young population also shows statistical significance and economic importance for explaining the overall and physical revenue per capita, but it has no effect on the digital and streaming revenue share. Also, although the Internet penetration rate and the mobile cellular subscription rate are statistically insignificant for the digital or streaming revenue share, point estimates suggest that these factors have important economic impacts.

This research examines how social networking fosters the mobility of young people in a rural Spain. Generally, rural areas have been overlooked in the discourse on Globalization and Network Society, which is the foundation of the concept of “linked city”. Although many scholars have highlighted the direct link between the increase in the modes of communication of people and the increase of any kind of interaction, face-to-face included, it is necessary to stress that most of these studies are conducted in urban context where a certain grade of efficient transport exists. This study provides an approach to the impact of mediated communication on the lives of people in villages. Based on the concept of Digital Natives this study addresses the Social Network use of young people in a determined rural area in Spain and its correlation with the aim of mobility of the respondents. The results bring to light a certain degree of correlation between the increase of interaction via the Internet and the wish of mobility. Besides, this study uncovers a transportation shortage among locations in this rural area that forces young people to reduce the face-to-face interactions around specific nodes (e.g. High School or a near big city). Finally this study stresses the need for improvement of the transportation networks in terms of cost, flexibility, functionality and reach among rural population in order to avoid a cultural, economic and social backwardness in comparison to urban environments.

Populations of many species of migratory birds are declining, and an understanding of how populations are linked between the breeding and nonbreeding grounds is necessary in order to determine drivers of declines. While all current tracking technologies to study the movements of small songbirds are limited by their coarse resolution, tracking birds by measuring stable isotopes in keratin offers an advantage because it requires only a single capture and is cost-effective, which leads to robust sample sizes. While this tracking method is accurate, stable hydrogen isotope values measured in feathers (δ2Hf) are known to be variable within a site, and may be influenced by the hydrology of a site. In this study, we assessed sources of variation in δ2Hf values in a wetland-associated Neotropical migratory bird, the prothonotary warbler (Protonotaria citrea), by comparing δ2Hf values among ages, sexes, years and feather type. We found that age and year significantly influence δ2Hf values, and that differences between primaries and rectrices are statistically significant but generally small. We also tested the accuracy and precision of models to assign prothonotary warblers to their breeding origin using known-origin feathers. We assigned birds in a spatially-explicit manner using an interpolated surface of stable hydrogen values measured in precipitation (δ2Hp), and developed a species-specific calibration equation to account for the offset between δ2Hf and δ2Hp, which explained 51% of the variation in δ2Hf values. We incorporated breeding bird abundance as prior information in our assignment model, and compared two sources of abundance data: the Breeding Bird Survey and a spatio-temporal exploratory model developed with eBird data. The assignment model with no prior information was accurate (83% of birds correctly assigned to their true location of origin), but imprecise (50% of grid cells assigned as likely locations of origin). Incorporating abundance as prior information led to a decrease in accuracy (9-14% of birds correctly assigned) but higher precision (1% of grid cells assigned as likely). We also assigned prothonotary warblers to their breeding origin using feathers collected from across the nonbreeding range. We found that all nonbreeding sampling locations contained a mixture of birds whose origins spanned the majority of the breeding range, with no evidence of strong connectivity between the seasons. In the absence of strong connectivity, the influence of events occurring at one nonbreeding location will be widespread and diffuse across the breeding range. For prothonotary warblers, understanding connectivity can help conservation planners understand how nonbreeding season habitat destruction and other processes influence population dynamics. We recommend that future studies account for age and year variation in δ2Hf values when possible, and continue to examine the trade-off between precision gained and accuracy lost when using abundance as prior information.

The purpose of this study is to find out how Swedish voluntary migrants communicate with friends in three different groups: friends that resides in the same country as the respondent currently lives in, friends in Sweden, friends in other countries around the globe and whether or not individual mobility, demographic factors or a sense of global citizenship affect the chosen mean of communication. The reason behind the study is to introduce a previously unstudied area into the field of geographically based media studies and hopefully contribute to a deeper understanding of the role played by different means of communication in shaping the dynamics of global friendship. The theoretical approach in this study will be from three different outlooks, migration, polymedia (including the second-level digital divide) and cosmopolitanism. The study is based on data from the Institute for Society, Opinion and Media (SOM) and their survey questionnaire sent out to Swedish expatriates during fall 2014 / winter 2015, also known as Utlands-SOM. The total number of respondents are 2268. The study starts with basic frequencies to find out which media that are the most prominent, then binary logistic regressions have been made. The total number of dependent variables are 21 and these have then been analysed from seven independent variables; age, gender, education, travel patterns, years spent abroad, number of countries lived in and whether or not the respondent consider himself/herself being a cosmopolitan. This generates a total of seven tables (one for each media) with three models in each (contact with friends in current country of residency, contact with friends in Sweden and contact with friends in other parts of the world). Amongst Swedish expatriates, e-mail and Facebook are the two most popular media for keeping in touch with friends, regardless of the friends location. The most significant demographic variable is age. Usage of video call, text message, chat, Facebook and other social media tend to decrease with age. Every year spent abroad decreases the communication with friends in Sweden, but increases the communication in the current country of residency. The number of countries lived in have a positive effect on communication with friends in other parts of the world. Cosmopolitan self-identity is found to be most significant when communicating with friends in other parts of the world, and it also affects e-mail the most. Level of education, which in previous studies have been found closely linked to a cosmopolitan identity, is found to have no significant correlation. Arguably, this is explained by the other means of communications negative relationship with the variable. / Syftet med denna studie är att ta reda på hur svenskar som frivilligt emigrerat utomlands kommunicerar med vänner inom tre olika grupper: vänner som bor i samma land som respondenten för tillfället lever i, vänner i Sverige samt vänner bosatta i övriga länder världen över. Detta sätts i perspektiv med huruvida den individuella mobiliteten, demografiska faktorer eller en känsla av ett världsmedborgarskap påverkar det valda kommunikationsmedlet. Denna studie ämnar att introducera ett tidigare förbisett forskningsområde inom geografiskt baserade mediestudier och därigenom förhoppningsvis bidra till forskningsfältet genom en fördjupad förståelse om kommunikationsmediers roll för vänskapsdynamik på global skala. Det teoretiska ramverk som utgör studiens grund är tre stycken skilda delar, migration, polymedia (inklusive en andra gradens digital klyfta) och kosmopolitism. Denna studie bygger på data från Institutet för Samhälle, Opinion och Media (SOM), och deras undersökning ställd till utlandssvenskar (Utlands-SOM) från hösten 2014 / vintern 2015. Totalt antal respondenter är 2268. Först görs en enkel frekvenstabeller för att undersöka vilket/vilka de primära medierna är i varje grupp, därefter har binära logistiska regressioner körts. Det totala antalet beroende variabler som behandlas är 21. Dessa sätts i perspektiv med ålder, kön, utbildning, resemönster, antal år utomlands, antal boendeländer och om respondenten anser sig vara världsmedborgare eller ej. Detta genererar totalt sju tabeller (en för varje media), med tre modeller i varje (kontakt med vänner i nuvarande boendeland, kontakt med vänner i Sverige och kontakt med vänner i övriga världen). Utlandssvenskarnas favoritmedium för att hålla kontakten med vänner, oavsett var vännerna befinner sig, visade sig vara e-post och Facebook. Den mest signifikanta demografiska variabeln visade sig vara ålder. Användandet av videosamtal, SMS, chatt, Facebook och andra sociala medier visade sig minska med högre ålder. För varje år respondenterna spenderar utomlands minskar oddsen för kommunikationen med Sverige, men ökar i det nuvarande boendelandet. Antalet länder som respondenterna har bott i har en positiv inverkan på kommunikationen med vänner i övriga världen. Den kosmopolitiska identiteten är mest signifikant när det kommer till att kommunicera med vänner i övriga världen och den påverkar även e-post som medium allra mest positivt. Utbildningsnivå, vilket sedan tidigare studier funnits vara tätt länkat med en kosmopolitisk identitet, visade sig inte vara signifikant i denna undersökning. Detta kan förklaras genom de andra kommunikationsmediernas negativa förhållande med variabeln.

Natal dispersal is at the nexus of ecology, ethology, population genetics, and evolution. While abundant research exists on emigration and associated proximate and ultimate causes, less is known about exploration, settlement, and factors that influence settlement decisions. Further, the role of individual behavioral phenotypes in the domains of wildlife ecology and conservation, which include natal dispersal, is a recent and expanding area of inquiry. Understanding the relationships among individual phenotype, environmental conditions, and natal dispersal is increasingly important as landscapes become altered by disturbance, fragmentation, and climate change. I investigated natal dispersal in endangered Mt. Graham red squirrels (Tamiasciurus hudsonicus grahamensis), an isolated, peripheral subspecies of North American red squirrel persisting at the southern edge of the species' range. We tested hypotheses about the importance of proximate and ultimate drivers of emigration, dispersal distance, and settlement, and estimated perceived landscape connectivity within a mosaic of forest damage in the Pinaleño Mountains, Arizona. Compared to other red squirrel populations in North America, natal dispersal in Mt. Graham red squirrels is sex-biased and non-philopatric with mean dispersal distance over 8 times that observed in non-peripheral populations. Resources, indicated by mother's body mass in spring (a reflection of her intrinsic quality and territory quality) and individual body condition, contribute to individual behavioral tendencies for movement and exploration. Individuals with behavioral tendencies for movement and exploration dispersed the farthest, and for both males and females the longest observed dispersal distances and proportion of individuals dispersing occurred in a year of lowest food availability. Our research highlights the important role individual behavioral syndromes may play in observed heterogeneity in life history strategies with populations. Following emigration from the natal area, we provide evidence that individual dispersers rely upon forest structural cues similar to their natal area to select locations for settlement; the first test of natal habitat preference induction in a single vegetation community type. We used circuit theory to evaluate landscape connectivity and identify areas important for long-distance dispersal movements. Because single connectivity models may not adequately represent functional connectivity for an entire population, we summarized landscape connectivity across varying levels of landscape resistance to identify areas that promote movement and long-distance dispersal for individuals with different perceptions of landscape resistance. We show that composite connectivity models are a useful method to identify forest areas important for the promotion of long-distance movements as well as areas that constrain movement.

Explorations into the organisation of spontaneous activity within the brain have demonstrated the existence of networks of temporally correlated activity, consisting of brain areas that share similar cognitive or sensory functions. These so-called resting state networks (RSNs) emerge spontaneously during rest and disappear in response to overt stimuli or cognitive demands. In recent years, the study of RSNs has emerged as a valuable tool for probing brain function, both in the healthy brain and in disorders such as schizophrenia, Alzheimer’s disease and Parkinson’s disease. However, analyses of these networks have so far been limited, in part due to assumptions that the patterns of neuronal activity that underlie these networks remain constant over time. Moreover, the majority of RSN studies have used functional magnetic resonance imaging (fMRI), in which slow fluctuations in the level of oxygen in the blood are used as a proxy for the activity within a given brain region. In this thesis we develop the use of magnetoencephalography (MEG) to study resting state functional connectivity. Unlike fMRI, MEG provides a direct measure of neuronal activity and can provide novel insights into the temporal dynamics that underlie resting state activity. In particular, we focus on the application of non- stationary analysis methods, which are able to capture fast temporal changes in activity. We first develop a framework for preprocessing MEG data and measuring interactions within different RSNs (Chapter 3). We then extend this framework to assess temporal variability in resting state functional connectivity by applying time- varying measures of interactions and show that within-network functional connectivity is underpinned by non-stationary temporal dynamics (Chapter 4). Finally we develop a data driven approach based on a hidden Markov model for inferring short lived connectivity states from resting state and task data (Chapter 5). By applying this approach to data from multiple subjects we reveal transient states that capture short lived patterns of neuronal activity (Chapter 6).

Despite the success of available medical and psychosocial treatments, a sizable subgroup of individuals with commonly co-occurring disorders, generalized anxiety disorder (GAD) and major depressive disorder (MDD), fail to make sufficient treatment gains thereby prolonging their deficits in life functioning and satisfaction. Clinically, these patients often display temperamental features reflecting heightened sensitivity to underlying motivational systems related to threat/safety and reward/loss (e.g., somatic anxiety) as well as inordinate negative self-referential processing (e.g., worry, rumination). This profile may reflect disruption in two important neural networks associated with emotional/motivational salience (e.g., salience network) and self-referentiality (e.g., default network, DN). Emotion Regulation Therapy (ERT) was developed to target this hypothesized profile and its neurobehavioral markers. In the present study, 22 GAD patients (with and without MDD) completed resting state MRI scans before receiving 16 sessions of ERT. To test study these hypotheses, we examined the associations between baseline patterns of intrinsic functional connectivity (iFC) of the insula and of hubs within the DN (anterior and dorsal medial prefrontal cortex [MPFC] and posterior cingulate cortex [PCC]) and treatment-related changes in worry, somatic anxiety symptoms and decentering. Results suggest that greater treatment linked reductions in worry were associated with iFC clusters in both the insular and parietal cortices. Greater treatment linked gains in decentering, a metacognitive process that involves the capacity to observe items that arise in the mind with healthy psychological distance that is targeted by ERT, was associated with iFC clusters in the anterior and posterior DN. The current study adds to the growing body of research implicating disruptions in the default and salience networks as promising targets of treatment for GAD with and without co-occurring MDD.

This thesis investigated the effect of visuomotor and working memory 1) task difficulty and 2) multitasking on dynamic functional connectivity in the brain. Studies have only recently begun to investigate functional connectivity within the scope of concurrent dual task or varying task difficulty conditions (Cocchi, Zalesky, et al. 2011; Rietschel et al. 2012). A series of EEG recordings were conducted during execution of visuomotor or working memory tasks within a novel paradigm using BCI2VR custom MATLAB toolbox. Functional connectivity was correlated with task-related coherence (TRCoh) analysis between two task conditions involving either variation in task difficulty or concurrent execution during multitasking within the delta (0 – 4 Hz), theta (4 – 8 Hz), alpha (8 – 12 Hz), beta1 (12-16 Hz), beta2 (16 – 20 Hz) and beta3 (20 – 24 Hz) frequency bands. An increase in coherence was observed with increased cognitive load, during both increased task difficulty and multitasking, in all frequency bands except beta1 and beta2. This may suggest that the psychomotor efficiency hypothesis also applies to multitasking as well as task difficulty. Decreases in beta coherence were observed with increased performance error, indicating that interregional beta coherence may not follow the PEH trend. The increased coherence between brain regions in the alpha, delta and theta bands contributes to the growing volume of research on quantifying cognitive workload and may serve as a future basis on increasing multitasking efficiency during high stress environments. Further research recording multitasking effects on individuals over regular intervals during an extended period of time (months or years) will be required to better understand changes in functional connectivity within the brain.

From the agent-based, correlated random walk model presented, we observe the effects of varying the parameter values of maximum insect turning area, 𝛿max, density of trees, ω, maximum pollen carryover, 𝜅max, and probability of fertilization, P𝜅, on the distribution of pollen within a population of Cornus florida (flowering dogwood). We see that varying 𝛿max and 𝜅max changes the dispersal distance of pollen, which greatly affects many measures of connectivity. The clustering coefficient of fathers is maximized when 𝛿max is between 60° and 90°. Varying ω does not have a major effect on the clustering coefficient of fathers, but it does have a greater effect on other measures of genetic diversity. Lastly, we compare our simulations with randomly-placed trees with that of actual tree placement of C. florida at the VCU Rice Center, concluding that in order to truly understand how pollen is distributed within a specific ecosystem, specificity in describing tree locations is necessary.