Continuous Uniform Finite Time Stabilization of Planar Controllable Systems

Continuous homogeneous controllers are utilized in a full state feedback setting for the uniform finite time stabilization of a perturbed double integrator in the presence of uniformly decaying piecewise continuous disturbances. Semiglobal strong $\mathcal{C}^1$ Lyapunov functions are identified to establish uniform asymptotic stability of the closed-loop planar system. Uniform finite time stability is then proved by extending the homogeneity principle of discontinuous systems to the continuous case with uniformly decaying piecewise continuous nonhomogeneous disturbances. A finite upper bound on the settling time is also computed. The results extend the existing literature on homogeneity and finite time stability by both presenting uniform finite time stabilization and dealing with a broader class of nonhomogeneous disturbances for planar controllable systems while also proposing a new class of homogeneous continuous controllers

An ISS Small-Gain Theorem for General Networks

We provide a generalized version of the nonlinear small-gain theorem for the case of more than two coupled input-to-state stable (ISS) systems. For this result the interconnection gains are described in a nonlinear gain matrix and the small-gain condition requires bounds on the image of this gain matrix. The condition may be interpreted as a nonlinear generalization of the requirement that the spectral radius of the gain matrix is less than one. We give some interpretations of the condition in special cases covering two subsystems, linear gains, linear systems and an associated artificial dynamical system.Comment: 26 pages, 3 figures, submitted to Mathematics of Control, Signals, and Systems (MCSS

A conceptual model for the integration of social and ecological information to understand human-wildlife interactions

There is growing recognition that interdisciplinary approaches that account for both ecological and social processes are necessary to successfully address human-wildlife interactions. However, such approaches are hindered by challenges in aligning data types, communicating across disciplines, and applying social science information to conservation actions. To meet these challenges, we propose a conceptual model that adopts a social-ecological systems approach and integrates social and ecological theory to identify the multiple, nested levels of influence on both human and animal behavior. By accounting for a diverse array of influences and feedback mechanisms between social and ecological systems, this model fulfills a need for approaches that treat social and ecological processes with equal depth and facilitates a comprehensive understanding of the drivers of human and animal behaviors that perpetuate human-wildlife interactions. We apply this conceptual model to our work on human-black bear conflicts in Colorado, USA to demonstrate its utility. Using this example, we identify key lessons and offer guidance to researchers and conservation practitioners for applying integrated approaches to other human-wildlife systems

Machine Learning as a Tool for Wildlife Management and Research: The Case of Wild Pig-Related Content on Twitter

Wild pigs (Sus scrofa) are a non-native, invasive species that cause considerable damage and transmit a variety of diseases to livestock, people, and wildlife. We explored Twitter, the most popular social media micro-blogging platform, to demonstrate how social media data can be leveraged to investigate social identity and sentiment toward wild pigs. In doing so, we employed a sophisticated machine learning approach to investigate: (1) the overall sentiment associated with the dataset, (2) online identities via user profile descriptions, and (3) the extent to which sentiment varied by online identity. Results indicated that the largest groups of online identity represented in our dataset were females and people whose occupation was in journalism and media communication. While the majority of our data indicated a negative sentiment toward wild pigs and other related search terms, users who identified with agriculture-related occupations had more favorable sentiment. Overall, this article is an important starting point for further investigation of the use of social media data and social identity in the context of wild pigs and other invasive species

Social identity and acceptability of wild pig (Sus scrofa) control actions: A case study of Texas hunters

Wild pigs (Sus scrofa) pose significant challenges to wildlife managers. This research explored Texas hunters’ acceptability of wild pig control actions, and whether acceptability varied according to hunters’ affiliation with four different categories of natural resource organizations as an indicator of social identity. Results of a survey (n = 37,317) revealed that most hunters were accepting of all control actions except toxicants and non-lethal deterrents. Mean acceptability scores for each action differed significantly across the four affiliation categories, but effect sizes were minimal. Hunters affiliated with agricultural organizations were the most accepting of control actions, while hunters with no organizational affiliations were least accepting. Findings suggested that while the type of organization with which a hunter affiliates provides some basis for predicting acceptability of control actions, the association is likely not significant enough to warrant differentiating wild pig outreach messaging on the basis of affiliation

Why Treat Insomnia?

“Why treat insomnia?” This question grows out of the perspective that insomnia is a symptom that should only receive targeted treatment when temporary relief is needed or until more comprehensive gains may be achieved with therapy for the parent or precipitating medical or psychiatric disorders. This perspective, however, is untenable given recent data regarding the prevalence, course, consequences, and costs of insomnia. Further, the emerging data that the treatment of insomnia may promote better medical and mental health (alone or in combination with other therapies) strongly suggests that the question is no longer “why treat insomnia,” but rather “when isn’t insomnia treatment indicated?” This perspective was recently catalyzed with the American College of Physicians’ recommendation that chronic insomnia should be treated and that the first line treatment should be cognitive-behavioral therapy for insomnia (CBT-I)

Symptom recognition and health care seeking among immigrants and native Swedish patients with heart failure

<p>Abstract</p> <p>Background</p> <p>It is not known what patient perceptions or beliefs lead to beneficial decisions or response patterns in symptom interpretation among heart failure (HF) patients, especially immigrants. The aim of this study was to explore and compare symptom recognition and health care seeking patterns among immigrants and native Swedes with HF.</p> <p>Methods</p> <p>The study used a qualitative design. Semi-structured interviews were conducted with 42 patients with HF, of whom 21 were consecutively selected immigrants and 21 were randomly selected Swedish patients. The interviews were analysed using content analysis.</p> <p>Results</p> <p>A majority of the immigrant patients sought health care for symptoms and signs, such as breathing difficulties, fatigue and swelling. Twice as many immigrants as Swedes were unaware of "what the illness experience entailed" and which symptoms indicated worsening of HF.</p> <p>Conclusion</p> <p>The symptoms that patients sought care for, were similar among immigrants and Swedes. However, when interpreting symptoms more immigrants were unaware of the connection between the symptoms/signs and their HF condition. More tailored educational interventions might improve recognition of worsening symptoms in immigrant patients with chronic heart failure.</p

Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2007

This document is the first annual report for the study titled “Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta in the Lower Columbia River.” Hereafter, we refer to this research as the Tidal Freshwater Monitoring (TFM) Study. The study is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act as a result of operation of the Federal Columbia River Power System (FCRPS). The project is performed under the auspices of the Northwest Power and Conservation Council’s Columbia Basin Fish and Wildlife Program

Computation of Lyapunov functions for systems with multiple attractors

We present a novel method to compute Lyapunov functions for continuous-time systems with multiple local attractors. In the proposed method one first computes an outer approximation of the local attractors using a graphtheoretic approach. Then a candidate Lyapunov function is computed using a Massera-like construction adapted to multiple local attractors. In the final step this candidate Lyapunov function is interpolated over the simplices of a simplicial complex and, by checking certain inequalities at the vertices of the complex, we can identify the region in which the Lyapunov function is decreasing along system trajectories. The resulting Lyapunov function gives information on the qualitative behavior of the dynamics, including lower bounds on the basins of attraction of the individual local attractors. We develop the theory in detail and present numerical examples demonstrating the applicability of our method

Early Ocean Dispersal Patterns of Columbia River Chinook and Coho Salmon

Several evolutionarily significant units (ESUs) of Columbia River basin Chinook Salmon Oncorhynchus tshawytscha and Coho Salmon O. kisutch are listed as threatened or endangered under the U.S. Endangered Species Act. Yet little is known about the spatial and temporal distributions of these ESUs immediately following ocean entry, when year-class success may be determined. We documented differences in dispersal patterns during the early ocean period among groups defined by ESU, adult run timing, and smolt age. Between 1995 and 2006, 1,896 coded-wire-tagged juvenile fish from the Columbia River basin were recovered during 6,142 research trawl events along the West Coast of North America. Three distinct ocean dispersal patterns were observed: (1) age-1 (yearling) mid and upper Columbia River spring-run and Snake River spring–summer-run Chinook Salmon migrated rapidly northward and by late summer were not found south of Vancouver Island; (2) age-0 (subyearling) lower Columbia River fall, upper Columbia River summer, upper Columbia River fall, and Snake River fall Chinook Salmon dispersed slowly, remaining mainly south of Vancouver Island through autumn; and (3) age-1 lower Columbia River spring, upper Columbia River summer, and upper Willamette River spring Chinook Salmon and Coho Salmon were widespread along the coast from summer through fall, indicating a diversity of dispersal rates. Generally, the ocean dispersal of age-1 fish was faster and more extensive than that of age-0 fish, with some age-1 fish migrating as fast as 10–40 km/d (0.5–3.0 body lengths/s). Within groups, interannual variation in dispersal was moderate. Identification of the distinct temporal and spatial ocean distribution patterns of juvenile salmon from Columbia River basin ESUs is important in order to evaluate the potential influence of changing ocean conditions on the survival and long term sustainability of these fish populations