Structural Drift: The Population Dynamics of Sequential Learning

We introduce a theory of sequential causal inference in which learners in a chain estimate a structural model from their upstream teacher and then pass samples from the model to their downstream student. It extends the population dynamics of genetic drift, recasting Kimura's selectively neutral theory as a special case of a generalized drift process using structured populations with memory. We examine the diffusion and fixation properties of several drift processes and propose applications to learning, inference, and evolution. We also demonstrate how the organization of drift process space controls fidelity, facilitates innovations, and leads to information loss in sequential learning with and without memory.Comment: 15 pages, 9 figures; http://csc.ucdavis.edu/~cmg/compmech/pubs/sdrift.ht

Using financial data to identify changes in bank condition

An empirical study using an early-warning bank failure prediction model and call-report data to predict deterioration in a bank's condition.Bank supervision ; Bank failures

K-theory for Leavitt path algebras: computation and classification

We show that the long exact sequence for K-groups of Leavitt path algebras deduced by Ara, Brustenga, and Cortinas extends to Leavitt path algebras of countable graphs with infinite emitters in the obvious way. Using this long exact sequence, we compute explicit formulas for the higher algebraic K-groups of Leavitt path algebras over certain fields, including all finite fields and all algebraically closed fields. We also examine classification of Leavitt path algebras using K-theory. It is known that the K_0-group and K_1-group do not suffice to classify purely infinite simple unital Leavitt path algebras of infinite graphs up to Morita equivalence when the underlying field is the rational numbers. We prove for these Leavitt path algebras, if the underlying field is a number field (which includes the case when the field is the rational numbers), then the pair consisting of the K_0-group and the K_6-group does suffice to classify these Leavitt path algebras up to Morita equivalence.Comment: 34 pages; Version II Comments: A few typos corrected. Version III Comments: Bibliography updated. This is the version to be publishe

Investigation of Antioxidant Defense Profiles and Stress Responses in Hawaiian Pocillopora damicornis

Ph.D

AERODYNAMIC SEPARATION OF FRAGMENTED BODIES IN HIGH-SPEED FLOW

Atmospheric entry of meteoroids poses danger to humans in the form of blast-wave overpressure, impact craters, tsunamis, and other assorted threats. The relative risks of each are highly dependent on the details of the unavoidable structural disruption that occurs and the subsequent aerodynamic separation sequence, so accurate prediction of fragment trajectories is required for threat mitigation. However, the physics of aerodynamic separation immediately following meteor fragmentation are virtually uncharacterized, allowing for only low confidence in threat assessment projections. The present work endeavors to constrain the separation behavior of fragmenting bodies by examining the model problem of close-packed sphere clusters and, to a lesser extent, clouds of dusty debris. Free-flight experimentation in UMD HyperTERP, a Mach-6 shock tunnel, is conducted to provide a foundation for both statistical and aerodynamic analyses, while coupled inviscid CFD/FEA provides complementary insight into the mechanisms driving fragment separation. First, computations of equal-sized sphere pairs reveal a previously unidentified phenomenon wherein two bodies in continual mechanical contact oscillate about a stable angle-of-attack equilibrium and achieve anomalously high lateral velocities. Proceeding to higher cluster populations, separation procedure can be divided into two stages: mutual repulsion from a common center and subsequent subcluster interactions dictated by the influence of an upstream body. The degree of repulsion induced by the former demonstrates close correlation with the initial angular position of a fragment, whereas the lateral velocities resulting from the latter appear to be normally distributed about a slightly positive value. The transverse separation characteristics of equal-sphere clusters numbering from 2 to 115 bodies are used to constrain a power-law fit between the lateral extent of a disrupted swarm and its population, providing a significant improvement to existing models of aerodynamic separation following fragmentation. Furthermore, experiments of unequal-sphere clusters, whose compositions are governed by realizations of truncated power laws, reveal a systematic underestimate in the equal-sphere correlation, resulting largely from massive subclusters suppressing high expulsion. A unified model of fragment separation, based on both the aforementioned power-law fit and a combined Rayleigh—exponential distribution, is then proposed. Finally, the dynamics of dusty debris clouds are discussed, with implications for mass depletion and energy deposition of rubble-pile-type impactors highlighted

The Los Alamos Supernova Light Curve Project: Computational Methods

We have entered the era of explosive transient astronomy, in which upcoming real-time surveys like the Large Synoptic Survey Telescope (LSST), the Palomar Transient Factory (PTF) and Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) will detect supernovae in unprecedented numbers. Future telescopes such as the James Webb Space Telescope may discover supernovae from the earliest stars in the universe and reveal their masses. The observational signatures of these astrophysical transients are the key to unveiling their central engines, the environments in which they occur, and to what precision they will pinpoint cosmic acceleration and the nature of dark energy. We present a new method for modeling supernova light curves and spectra with the radiation hydrodynamics code RAGE coupled with detailed monochromatic opacities in the SPECTRUM code. We include a suite of tests that demonstrate how the improved physics is indispensable to modeling shock breakout and light curves.Comment: 18 pages, 19 figures, published in ApJ Supplement

A Critical Review of the Literature for Sales Educators

The Journal of Marketing Education is publishing a special issue on Sales Education and Training in August 2014. In this article, we review the sales education literature from four primary journals and the business literature at large. The four primary journals are the Journal of Marketing Education, Marketing Education Review, Journal of Education in Business, and the Journal of Personal Selling & Sales Management. Of the 107 identified articles, experiential learning, assessment, and career development were the three most prominent topics. Future research opportunities in sales education, including those for the special issue, are offered across nine topical areas

Covariates of corticotropin-releasing hormone (CRH) concentrations in cerebrospinal fluid (CSF) from healthy humans

BACKGROUND: Define covariates of cerebrospinal corticotropin-releasing hormone (CRH) levels in normal humans. CRH(CSF )was measured in 9 normal subjects as part of an intensive study of physiological responses stressors in chronic pain and fatigue states. CRH(CSF )was first correlated with demographic, vital sign, HPA axis, validated questionnaire domains, baseline and maximal responses to pain, exercise and other stressors. Significant factors were used for linear regression modeling. RESULTS: Highly significant correlations were found despite the small number of subjects. Three models were defined: (a) CRH(CSF )with blood glucose and sodium (explained variance = 0.979, adjusted R(2 )= 0.958, p = 0.02 by 2-tailed testing); (b) CRH(CSF )with resting respiratory and heart rates (R(2 )= 0.963, adjusted R(2 )= 0.939, p = 0.007); and (c) CRH(CSF )with SF-36 Vitality and Multidimensional Fatigue Inventory Physical Fatigue domains (R(2 )= 0.859, adjusted R(2 )= 0.789, p = 0.02). CONCLUSIONS: Low CRH(CSF )was predicted by lower glucose, respiratory and heart rates, and higher sodium and psychometric constructs of well being. Responses at peak exercise and to other acute stressors were not correlated. CRH(CSF )may have reflected an overall, or chronic, set-point for physiological responses, but did not predict the reserves available to respond to immediate stressors