3,515 research outputs found

    Quantifying fisher responses to environmental and regulatory dynamics in marine systems

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    Thesis (Ph.D.) University of Alaska Fairbanks, 2017Commercial fisheries are part of an inherently complicated cycle. As fishers have adopted new technologies and larger vessels to compete for resources, fisheries managers have adapted regulatory structures to sustain stocks and to mitigate unintended impacts of fishing (e.g., bycatch). Meanwhile, the ecosystems that are targeted by fishers are affected by a changing climate, which in turn forces fishers to further adapt, and subsequently, will require regulations to be updated. From the management side, one of the great limitations for understanding how changes in fishery environments or regulations impact fishers has been a lack of sufficient data for resolving their behaviors. In some fisheries, observer programs have provided sufficient data for monitoring the dynamics of fishing fleets, but these programs are expensive and often do not cover every trip or vessel. In the last two decades however, vessel monitoring systems (VMS) have begun to provide vessel location data at regular intervals such that fishing effort and behavioral decisions can be resolved across time and space for many fisheries. I demonstrate the utility of such data by examining the responses of two disparate fishing fleets to environmental and regulatory changes. This study was one of "big data" and required the development of nuanced approaches to process and model millions of records from multiple datasets. I thus present the work in three components: (1) How can we extract the information that we need? I present a detailed characterization of the types of data and an algorithm used to derive relevant behavioral aspects of fishing, like the duration and distances traveled during fishing trips; (2) How do fishers' spatial behaviors in the Bering Sea pollock fishery change in response to environmental variability; and (3) How were fisher behaviors and economic performances affected by a series of regulatory changes in the Gulf of Mexico grouper-tilefish longline fishery? I found a high degree of heterogeneity among vessel behaviors within the pollock fishery, underscoring the role that markets and processor-level decisions play in facilitating fisher responses to environmental change. In the Gulf of Mexico, my VMS-based approach estimated unobserved fishing effort with a high degree of accuracy and confirmed that the regulatory shift (e.g., the longline endorsement program and catch share program) yielded the intended impacts of reducing effort and improving both the economic performance and the overall harvest efficiency for the fleet. Overall, this work provides broadly applicable approaches for testing hypotheses regarding the dynamics of spatial behaviors in response to regulatory and environmental changes in a diversity of fisheries around the world.General introduction -- Chapter 1 Using vessel monitoring system data to identify and characterize trips made by fishing vessels in the United States North Pacific -- Chapter 2 Paths to resilience: Alaska pollock fleet uses multiple fishing strategies to buffer against environmental change in the Bering Sea -- Chapter 3 Vessel monitoring systems (VMS) reveal increased fishing efficiency following regulatory change in a bottom longline fishery -- General Conclusions

    Coevolutionary Dynamics in a Minimal Substrate

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    One of the central difficulties of coevolutionary methods arises from 'intransitive superiority' - in a two-player game, for example, the fact that A beats B, and B beats C, does not exclude the possibility that C beats A. Such cyclic superiority in a coevolutionary substrate is hypothesized to cause cycles in the dynamics of the population such that it 'chases its own tail' - traveling through some part of strategy space more than once despite apparent improvement with each step. It is often difficult to know whether an application domain contains such difficulties and to verify this hypothesis in the failure of a given coevolutionary set-up. In this paper we wish to elucidate some of the issues and concepts in an abstract domain where the dynamics of coevolution can be studied simply and directly. We define three simple 'number games' that illustrate intransitive superiority and resultant oscillatory dynamics, as well as some other relevant concepts. These include the distinction between a player's perceived performance and performance with respect to an external metric, and the significance of strategies with a multi-dimensional nature. These features alone can also cause oscillatory behavior and coevolutionary failure

    Mutualism, Parasitism, and Evolutionary Adaptation

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    Our investigations concern the role of symbiosis as an enabling mechanism in evolutionary adaptation. Previous work has illustrated how the formation of mutualist groups can guide genetic variation so as to enable the evolution of ultimately independent organisms that would otherwise be unobtainable. The new experiments reported here show that this effect applies not just in genetically related organisms but may also occur from symbiosis between distinct species. In addition, a new detail is revealed: when the symbiotic group members are drawn from two separate species only one of these species achieves eventual independence and the other remains parasitic. It is nonetheless the case that this second species, formerly mutualistic, was critical in enabling the independence of the first. We offer a biological example that is suggestive of the effect and discuss the implications for evolving complex organisms, natural and artificial

    Global and Regional Chitinozoan Biodiversity Dynamics in the Ordovician: Relationships to Sea-Level, Carbon Cycling and Tectonics

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    Fossil species provide extensive information about the past history of life on Earth. This thesis focuses on the global and regional biodiversity dynamics of the extinct fossil group Chitinozoa, and analyzes the impact and influences of sea-level, global carbon cycling and tectonics on their biodiversity. Biodiversity curves were generated from three different paleo-continents, Laurentia, Baltica, and Gondwana using the automated graphic correlation computer program CONOP9. Traditional methods of biodiversity analysis count fossil taxa in individual intervals of geologic time. The results of these methods are highly dependent upon interval length and the relationship of taxon range to interval boundaries. CONOP9 utilizes an interval free approach to biodiversity analysis. Chitinozoan stratigraphic range data from fossil species collected on several ancient continents (Baltica, Laurentia, and Gondwana) were also combined and analyzed to compare the regional and global biodiversity plots. These biodiversity patterns were then compared to existing sea-level and carbon isotope excursion curves to examine the relationship between environmental change and Chitinozoan biodiversity. The three major carbon isotope excursions of the Ordovician, the MDICE, GICE, and HICE all occur during periods of reduced global chitinozoans biodiversity. Additionally, sea level to some extent appears to be related to chitinozoan biodiversity with reduced biodiversity during periods of sea level decrease and increasing biodiversity during periods of higher sea level

    Modeling Building Block Interdependency

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    The Building-Block Hypothesis appeals to the notion of problem decomposition and the assembly of solutions from sub-solutions. Accordingly, there have been many varieties of GA test problems with a structure based on building-blocks. Many of these problems use deceptive fitness functions to model interdependency between the bits within a block. However, very few have any model of interdependency between building-blocks; those that do are not consistent in the type of interaction used intra-block and inter-block. This paper discusses the inadequacies of the various test problems in the literature and clarifies the concept of building-block interdependency. We formulate a principled model of hierarchical interdependency that can be applied through many levels in a consistent manner and introduce Hierarchical If-and-only-if (H-IFF) as a canonical example. We present some empirical results of GAs on H-IFF showing that if population diversity is maintained and linkage is tight then the GA is able to identify and manipulate building-blocks over many levels of assembly, as the Building-Block Hypothesis suggests

    Controlling Hypertension: A Self Blood Pressure Monitoring Program plus Health Coaching compared to Health Coaching Alone

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    While nearly half of adults in the United States have hypertension, only about one quarter of those adults have adequately controlled hypertension. Providing a nurse-led coaching program in combination with home blood pressure monitoring (HBPM) has been shown to improve blood pressure control. A rural family practice clinic in the Illinois Metro East area proposed a clinical trial to test a nurse-led coaching program in combination with home blood pressure monitoring (HBPM) in decreasing blood pressure long-term. Both intervention and control groups received nurse-led hypertension coaching, while the intervention group also received a home blood pressure cuff. The results showed that a nurse-led coaching is effective in decreasing blood pressure. However, due to significant attrition, meaningful results could not be obtained regarding any additional benefits of adding HBPM to nurse-led coaching

    The contemporary dystopian text as a narrative on the adolescent journey to adulthood: overcoming authoritarian power and the struggle for collective identity, identity, and emotional competency in the face of suffering

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    As of late, dystopian novels for Young Adults have become narratives for the adolescent’s journey towards adulthood. This thesis explores this genre of fiction as a narration of the power struggle between authoritarian institutions and the adolescent. It examines the way in which limiting power structures use discourse, spectacle, propaganda, and surveillance to further regulate individuals. In addition, this thesis examines the development of identity and emotional competency in repressive structures, as well as how freedom and autonomy are viewed within the dystopic novel. Aside from recognising how adolescents are able to transition into adulthood in oppressive and collusive environments, this thesis argues that it is precisely these hardships and the quality of suffering which makes the adolescent individual more capable of growth

    Surface-based constraints on target selection and distractor rejection: Evidence from preview search

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    In preview search when an observer ignores an early appearing set of distractors, there can subsequently be impeded detection of new targets that share the colour of this preview. This “negative carry-over effect” has been attributed to an active inhibitory process targeted against the old items and inadvertently their features. Here we extend negative carry-over effects to the case of stereoscopically defined surfaces of coplanar elements without common features. In Experiment 1 observers previewed distractors in one surface (1000 ms), before being presented with the target and new distractors divided over the old and a new surface either above or below the old one. Participants were slower and less efficient to detect targets in the old surface. In Experiment 2 in both the first and second display the items were divided over two planes in the proportion 66/33% such that no new planes appeared following the preview, and there was no majority of items in any one plane in the final combined display. The results showed that participants were slower to detect the target when it occurred in the old majority surface. Experiment 3 held constant the 2D properties of the stimuli while varying the presence of binocular depth cues. The carry-over effect only occurred in the presence of binocular depth cues, ruling out any account of the results in terms of 2-D cues. The results suggest well formed surfaces in addition to simple features may be targets for inhibition in search

    Sarcospan Regulates Cardiac Isoproterenol Response and Prevents Duchenne Muscular Dystrophy-Associated Cardiomyopathy.

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    BackgroundDuchenne muscular dystrophy is a fatal cardiac and skeletal muscle disease resulting from mutations in the dystrophin gene. We have previously demonstrated that a dystrophin-associated protein, sarcospan (SSPN), ameliorated Duchenne muscular dystrophy skeletal muscle degeneration by activating compensatory pathways that regulate muscle cell adhesion (laminin-binding) to the extracellular matrix. Conversely, loss of SSPN destabilized skeletal muscle adhesion, hampered muscle regeneration, and reduced force properties. Given the importance of SSPN to skeletal muscle, we investigated the consequences of SSPN ablation in cardiac muscle and determined whether overexpression of SSPN into mdx mice ameliorates cardiac disease symptoms associated with Duchenne muscular dystrophy cardiomyopathy.Methods and resultsSSPN-null mice exhibited cardiac enlargement, exacerbated cardiomyocyte hypertrophy, and increased fibrosis in response to ÎČ-adrenergic challenge (isoproterenol; 0.8 mg/day per 2 weeks). Biochemical analysis of SSPN-null cardiac muscle revealed reduced sarcolemma localization of many proteins with a known role in cardiomyopathy pathogenesis: dystrophin, the sarcoglycans (α-, ÎŽ-, and Îł-subunits), and ÎČ1D integrin. Transgenic overexpression of SSPN in Duchenne muscular dystrophy mice (mdx(TG)) improved cardiomyofiber cell adhesion, sarcolemma integrity, cardiac functional parameters, as well as increased expression of compensatory transmembrane proteins that mediate attachment to the extracellular matrix.ConclusionsSSPN regulates sarcolemmal expression of laminin-binding complexes that are critical to cardiac muscle function and protects against transient and chronic injury, including inherited cardiomyopathy
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