Identification of Piecewise Linear Models of Complex Dynamical Systems

The paper addresses the realization and identification problem or a subclass of piecewise-affine hybrid systems. The paper provides necessary and sufficient conditions for existence of a realization, a characterization of minimality, and an identification algorithm for this subclass of hybrid systems. The considered system class and the identification problem are motivated by applications in systems biology

Faculty and Student Perceptions of Effective Online Learning Environments

This quantitative and qualitative study was designed to review alignment of student and faculty perceptions of effective online learning environments. The purpose of this study was to review statistical survey data to determine if alignment of perceptions existed. The student research sample included data from three years of archival survey data at Minnesota West Community and Technical College. Over 10,000 survey results were part of this sample. Additionally, Minnesota West Community and Technical College faculty who taught during this timeframe were surveyed. Qualitative data from one year of student responses was analyzed to add depth to the results. The results showed partial alignment of faculty and student perceptions of what constitutes an effective online learning environment

Getting to know you: Accuracy and error in judgments of character

Character judgments play an important role in our everyday lives. However, decades of empirical research on trait attribution suggest that the cognitive processes that generate these judgments are prone to a number of biases and cognitive distortions. This gives rise to a skeptical worry about the epistemic foundations of everyday characterological beliefs that has deeply disturbing and alienating consequences. In this paper, I argue that this skeptical worry is misplaced: under the appropriate informational conditions, our everyday character-trait judgments are in fact quite trustworthy. I then propose a mindreading-based model of the socio-cognitive processes underlying trait attribution that explains both why these judgments are initially unreliable, and how they eventually become more accurate

Stretching After an In-Water Warm-Up Does Not Acutely Improve Sprint Freestyle Swim Performance in DIII Collegiate Swimmers

Topics in Exercise Science and Kinesiology Volume 2: Issue 1, Article 11, 2021. Stretching, as part of a warm-up prior to competition, has been used as a method to enhance performance in swimming and other sports, but its efficacy as a potential ergogenic aid remains understudied. This study’s purpose was to determine if acute static stretching or a dynamic warm-up, following an in-water swim-specific warm-up, improved sprint freestyle swim performance in collegiate swimmers. NCAA Division III swimmers (n=15, 67% female) participated in three testing protocols. In each protocol, participants did an in-water warm up and either a dynamic warmup (DW), static stretching warmup (SS), or no stretching (CON) routine followed by three, 100-yard freestyle sprints, each performed four minutes apart. Swim times were recorded for the first and second 50-yard splits and for the full 100 yards in each trial. Repeated-measures analysis of variance and effect sizes were used to assess differences across protocols. Average performance was significantly faster for CON compared to DW for the first 50-yard split (mean difference ~0.47 seconds, p=0.044) and total 100-yard time (mean difference ~0.77 seconds, p=0.017), with medium effect sizes for both. No differences were observed between SS and the other protocols. Adding acute stretching or dynamic warm-up, following an in-water warm-up, either did not improve or was associated with poorer 100-yard freestyle swim performance than solely performing an in-water warm-up. Swimmers should carefully evaluate their warm-up routines and consider a focus on in-water warm-ups for maximizing sprint swim performance

Effects of Synaptic and Myelin Plasticity on Learning in a Network of Kuramoto Phase Oscillators

Models of learning typically focus on synaptic plasticity. However, learning is the result of both synaptic and myelin plasticity. Specifically, synaptic changes often co-occur and interact with myelin changes, leading to complex dynamic interactions between these processes. Here, we investigate the implications of these interactions for the coupling behavior of a system of Kuramoto oscillators. To that end, we construct a fully connected, one-dimensional ring network of phase oscillators whose coupling strength (reflecting synaptic strength) as well as conduction velocity (reflecting myelination) are each regulated by a Hebbian learning rule. We evaluate the behavior of the system in terms of structural (pairwise connection strength and conduction velocity) and functional connectivity (local and global synchronization behavior). We find that for conditions in which a system limited to synaptic plasticity develops two distinct clusters both structurally and functionally, additional adaptive myelination allows for functional communication across these structural clusters. Hence, dynamic conduction velocity permits the functional integration of structurally segregated clusters. Our results confirm that network states following learning may be different when myelin plasticity is considered in addition to synaptic plasticity, pointing towards the relevance of integrating both factors in computational models of learning.Comment: 39 pages, 15 figures This work is submitted in Chaos: An Interdisciplinary Journal of Nonlinear Scienc

Analyzing Metabolomics Data for Association with Genotypes Using Two-Component Gaussian Mixture Distributions

Standard approaches to evaluate the impact of single nucleotide polymorphisms (SNP) on quantitative phenotypes use linear models. However, these normal-based approaches may not optimally model phenotypes which are better represented by Gaussian mixture distributions (e.g., some metabolomics data). We develop a likelihood ratio test on the mixing proportions of two-component Gaussian mixture distributions and consider more restrictive models to increase power in light of a priori biological knowledge. Data were simulated to validate the improved power of the likelihood ratio test and the restricted likelihood ratio test over a linear model and a log transformed linear model. Then, using real data from the Framingham Heart Study, we analyzed 20,315 SNPs on chromosome 11, demonstrating that the proposed likelihood ratio test identifies SNPs well known to participate in the desaturation of certain fatty acids. Our study both validates the approach of increasing power by using the likelihood ratio test that leverages Gaussian mixture models, and creates a model with improved sensitivity and interpretability

Analyzing Metabolomics Data for Association with Genotypes Using Two-Component Gaussian Mixture Distributions

Standard approaches to evaluate the impact of single nucleotide polymorphisms (SNP) on quantitative phenotypes use linear models. However, these normal-based approaches may not optimally model phenotypes which are better represented by Gaussian mixture distributions (e.g., some metabolomics data). We develop a likelihood ratio test on the mixing proportions of two-component Gaussian mixture distributions and consider more restrictive models to increase power in light of a priori biological knowledge. Data were simulated to validate the improved power of the likelihood ratio test and the restricted likelihood ratio test over a linear model and a log transformed linear model. Then, using real data from the Framingham Heart Study, we analyzed 20,315 SNPs on chromosome 11, demonstrating that the proposed likelihood ratio test identifies SNPs well known to participate in the desaturation of certain fatty acids. Our study both validates the approach of increasing power by using the likelihood ratio test that leverages Gaussian mixture models, and creates a model with improved sensitivity and interpretability

Proposal and preliminary design for a high speed civil transport aircraft. Swift: A high speed civil transport for the year 2000

To meet the needs of the growing passenger traffic market in light of an aging subsonic fleet, a new breed of aircraft must be developed. The Swift is an aircraft that will economically meet these needs by the year 2000. Swift is a 246 passenger, Mach 2.5, luxury airliner. It has been designed to provide the benefit of comfortable, high speed transportation in a safe manner with minimal environmental impact. This report will discuss the features of the Swift aircraft and establish a solid, foundation for this supersonic transport of tomorrow

Revision of Oxandra (Annonaceae)

A taxonomic revision is given of the Neotropical genus Oxandra (Annonaceae). Within the genus 27 species are recognized, 4 of which are new to science. Most of the species are occurring in tropical South America, whereas a few (6) are found in Mexico and Central America and two in the West Indies (Greater and Lesser Antilles). A key to all species is provided. The treatment includes chapters about the history of the genus and morphology. All species are fully described, including full synonymy, notes on distribution and ecology, field observations (when available), vernacular names (when given), and mostly short notes about relationships of the species concerned. For each species a distribution map is made. At the end of the revision a complete list of vernacular names is included.Peer reviewe