No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Dynamics of social processes in populations, such as the spread of emotions, influence, language, mass movements, and warfare (often referred to individually and collectively as contagions), are increasingly studied because of their social, political, and economic impacts. Discrete dynamical systems (discrete in time and discrete in agent states) are often used to quantify contagion propagation in populations that are cast as graphs, where vertices represent agents and edges represent agent interactions. We refer to such formulations as graph dynamical systems. For social applications, threshold models are used extensively for agent state transition rules (i.e., for vertex functions). In its simplest form, each agent can be in one of two states (state 0 (1) means that an agent does not (does) possess a contagion), and an agent contracts a contagion if at least a threshold number of its distance-1 neighbors already possess it. The transition to state 0 is not permitted. In this study, we extend threshold models in three ways. First, we allow transitions to states 0 and 1, and we study the long-term dynamics of these bithreshold systems, wherein there are two distinct thresholds for each vertex; one governing each of the transitions to states 0 and 1. Second, we extend the model from a binary vertex state set to an arbitrary number r of states, and allow transitions between every pair of states. Third, we analyze a recent hierarchical model from the literature where inputs to vertex functions take into account subgraphs induced on the distance-1 neighbors of a vertex. We state, prove, and analyze conditions characterizing long-term dynamics of all of these models. / Master of Science

Current literature suggests neurological (i.e., insula, amygdala) and autonomic (i.e., respiratory sinus arrhythmia; RSA) markers of language, social, and behavioral challenges in autism spectrum disorders (ASD; Bal et al., 2010; DiMartino, Ross, et al., 2009; Lorenzi, Patriquin, & Scarpa, 2011; Patriquin, Scarpa, Friedman, & Porges, 2011), that hypothetically reflect a defensive neurophysiological circuit (i.e., hyper-arousal within the central and autonomic nervous systems). It is unknown how this neurophysiological state contributes to difficulties in ASD. Therefore, the current study quantified peripheral and central nervous system activity and investigated how this neurophysiological circuit may be related to different social and behavioral patterns that characterize ASD. Participants with (n = 16) and without (n = 30) ASD listened to classical music while brain (via functional magnetic resonance imaging) and autonomic (via pulse oximeter and plethysmogram) data were collected. Results indicated that decreased insula and amygdala activity during physiological hyper-aroused states predicted symptoms associated with ASD, and predicted higher levels of comorbid anxiety, stress, and depression. Contrary to hypotheses, no baseline RSA or amygdala differences were noted between ASD and controls groups, suggesting that adults with ASD may have developed effective coping strategies for reducing physiological threat responses. It will be important for future studies to continue to explore and clarify the neural connections of peripheral nervous system activation in individuals with and without ASD, including extending this research to children. / Ph. D.

Due to its relatively cool, humid summers, southwestern Virginia provides an ideal climate for European earwigs, Forficula auricularia. In 1990 - 1992, nymphs were captured in wooden groove-board traps beginning in late May, adults were captured beginning in mid-June, and disappeared from sampling sites by September or October. Sex ratios were significantly female-biased most of the season, becoming more marked by the fall. The pest status of F. auncularia is exacerbated by its gregarious nature. Gas chromatography-mass spectroscopy and accompanying behavioral bioassays showed that aggregation occurred as a result of a pheromone located on the male cuticle, which is probably a minor component of the hydrocarbon profile. Approximately 88% of the detected volatiles on the cuticle were identified as a series of normal and branched alkanes. Fatty acids and hydrocarbons were also identified in nymphal and adult legs, but these extracts were not attractive. Frass, which also contained fatty acids and hydrocarbons, was attractive, but likely acquired its attractancy through the earwigs' proclivity for consuming carcasses and exuviae. The defensive quinones produced by F aunculana repel conspecifics. A study of the behavioral repertoire of F. aunculana showed that, contrary to previous reports, only nymphs are nocturnal. Many differences in behavior were due to gender, age, and partner age. (e.g., females spent more time feeding than did males, adults fed more when paired with nymphs than when paired with adults). Social behaviors (communal feeding, aggression, contact, and dorsal palpation) comprised <10% of the insect's behavioral repertoire. Since dorsal palpation, a previously undescribed behavior and a form of allogrooming, occurred more frequently during reproductive periods, it may have a sexual significance. Dorsal palpation also may augment the distribution of defensive quinones on the cuticle of F. auricularia. An analysis of nymphal group dynamics demonstrated that as group size increased, nymphs spent significantly less time feeding alone and grooming, but more time resting. Antennal contact rates between group members increased significantly with group size. Detailed observations of the courtship and mating of F. auricularia revealed a complex of sexual behaviors for both males and females. Receptive females were behaviorally active during courtship. The significance of the male cerci was demonstrated by their use in early courtship with displays, and later use as a tactile stimulus for the female; and study of males from which the cerci had been removed, which showed no mating by amputated males. Male forcep length was bimodally distributed and positively allometric, while female forcep length was normally distributed. Males with longer forceps did not have a mating advantage. Further research is needed to identify the chemical composition of the aggregation pheromone, and to quantify any advantages of body and forcep size on mating success. / Ph. D.

Diss. (sammanfattning) Umeå : Univ., 2004. / Härtill 4 uppsatser.