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Search Results: 1 - 10 of 263081 matches for " Michael R McGowen "
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A supermatrix analysis of genomic, morphological, and paleontological data from crown Cetacea
Jonathan H Geisler, Michael R McGowen, Guang Yang, John Gatesy
BMC Evolutionary Biology , 2011, DOI: 10.1186/1471-2148-11-112
Abstract: We combined new nuclear DNA sequences, including segments of six genes (~2800 basepairs) from the functionally extinct Yangtze River dolphin, with an expanded morphological matrix and published genomic data. Diverse analyses of these data resolved the relationships of 74 taxa that represent all extant families and 11 extinct families of Cetacea. The resulting supermatrix (61,155 characters) and its sub-partitions were analyzed using parsimony methods. Bayesian and maximum likelihood (ML) searches were conducted on the molecular partition, and a molecular scaffold obtained from these searches was used to constrain a parsimony search of the morphological partition. Based on analysis of the supermatrix and model-based analyses of the molecular partition, we found overwhelming support for 15 extant clades. When extinct taxa are included, we recovered trees that are significantly correlated with the fossil record. These trees were used to reconstruct the timing of cetacean diversification and the evolution of characters shared by "river dolphins," a non-monophyletic set of species according to all of our phylogenetic analyses.The parsimony analysis of the supermatrix and the analysis of morphology constrained to fit the ML/Bayesian molecular tree yielded broadly congruent phylogenetic hypotheses. In trees from both analyses, all Oligocene taxa included in our study fell outside crown Mysticeti and crown Odontoceti, suggesting that these two clades radiated in the late Oligocene or later, contra some recent molecular clock studies. Our trees also imply that many character states shared by river dolphins evolved in their oceanic ancestors, contradicting the hypothesis that these characters are convergent adaptations to fluvial habitats.It has been 12 years since the publication of Messenger and McGuire [1], the first major effort to develop a phylogenetic hypothesis for crown Cetacea (Neoceti) based on a combined phylogenetic analysis of morphological and molecular charact
Phylogeny and adaptive evolution of the brain-development gene microcephalin (MCPH1) in cetaceans
Michael R McGowen, Stephen H Montgomery, Clay Clark, John Gatesy
BMC Evolutionary Biology , 2011, DOI: 10.1186/1471-2148-11-98
Abstract: We sequenced ~1240 basepairs of the brain development gene microcephalin (MCPH1) in 38 cetacean species. Alignments of these data and a published complete sequence from Tursiops truncatus with primate MCPH1 were utilized in phylogenetic analyses and to estimate ω (rate of nonsynonymous substitution/rate of synonymous substitution) using site and branch models of molecular evolution. We also tested the hypothesis that selection on MCPH1 was correlated with brain size in cetaceans using a continuous regression analysis that accounted for phylogenetic history. Our analyses revealed widespread signals of adaptive evolution in the MCPH1 of Cetacea and in other subclades of Mammalia, however, there was not a significant positive association between ω and brain size within Cetacea.In conjunction with a recent study of Primates, we find no evidence to support an association between MCPH1 evolution and the evolution of brain size in highly encephalized mammalian species. Our finding of significant positive selection in MCPH1 may be linked to other functions of the gene.The human brain is arguably one of the most remarkable adaptations in the history of life. Compared to other mammals, the human lineage has undergone a massive expansion in relative brain and forebrain size, cortical surface area, and overall cognitive ability [1]. However, many other vertebrates exhibit increased relative brain and forebrain sizes, as well as complex social and cognitive behaviours. For example, odontocete cetaceans (toothed whales) have some of the largest brains relative to their body mass among extant mammals [2]. Relative brain size in some odontocete species is greater than non-human primates [3], and in absolute terms, the giant sperm whale (Physeter macrocephalus) has the largest brain of any living organism at a maximum of 10 kg [4]. According to some researchers, high relative brain or forebrain sizes are positively correlated with indices of cognition or "intelligence" [1,5], althou
Timing and Tempo of Early and Successive Adaptive Radiations in Macaronesia
Seung-Chul Kim, Michael R. McGowen, Pesach Lubinsky, Janet C. Barber, Mark E. Mort, Arnoldo Santos-Guerra
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002139
Abstract: The flora of Macaronesia, which encompasses five Atlantic archipelagos (Azores, Canaries, Madeira, Cape Verde, and Salvage), is exceptionally rich and diverse. Spectacular radiation of numerous endemic plant groups has made the Macaronesian islands an outstanding area for studies of evolution and speciation. Despite intensive investigation in the last 15 years, absolute age and rate of diversification are poorly known for the flora of Macaronesia. Here we report molecular divergence estimates and rates of diversification for five representative, putative rapid radiations of monophyletic endemic plant lineages across the core eudicot clade of flowering plants. Three discrete windows of colonization during the Miocene and early Pliocene are suggested for these lineages, all of which are inferred to have had a single colonization event followed by rapid radiation. Subsequent inter-archipelago dispersal events into Madeira and the Cape Verdes took place very recently during the late Pliocene and Pleistocene after initial diversification on the Canary Islands. The tempo of adaptive radiations differs among the groups, but is relatively rapid compared to continental and other island radiations. Our results demonstrate that opportunity for island colonization and successful radiation may have been constrained to discrete time periods of profound climatic and geological changes in northern African and the Mediterranean.
Individual gain and engagement with mathematical understanding
Mercedes A. McGowen,Gary E. Davis
Mathematics , 2014,
Abstract: We examine a measure of individual student gain by preservice elementary teachers, related to Richard Hakes use of mean gain in the study of reform classes in undergraduate physics. The gain statistic assesses the amount individual students increase their test scores from initial test to final test, as a proportion of the possible increase for each student. We examine the written work in mathematics classes of preservice elementary teachers with very high gain and those with very low gain and show that these groups exhibit distinct psychological attitudes and dispositions to learning mathematics. We show a statistically significant, small, increase in average gain when course goals focus on patterns, connections, and meaning making in mathematics. A common belief is that students with low initial test scores will have higher gains, and students with high initial-test scores will have lower gains. We show that this is not correct for a cohort of preservice elementary teachers.
Application of Response Surfaces in Evaluating Tool Performance in Metalcutting  [PDF]
Michael R. Delozier
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.49180
Abstract:

This paper advances the collection of statistical methods known as response surface methods as an effective experimental approach for describing and comparing the tool life performance capabilities of metalcutting tools. Example applications presented demonstrate the versatility of the power family of transformations considered by Box and Cox (1964) in modeling tool life behavior as revealed using simple response surface designs. A comparative analysis illustrates a method to gauge the statistical significance of differences in tool life estimates computed from response surface models. Routine use of these methods in experimental tool testing is supported by their ability to produce reliable relative performance representations of competing tools in field applications.

Is US Bank Lending Sensitive to Exchange Rates? A Panel Data Investigation  [PDF]
Michael R. Jonas
Modern Economy (ME) , 2014, DOI: 10.4236/me.2014.58078
Abstract:

The goal of this paper is to examine the sensitivity of US bank lending to movements in the exchange rate. Using a panel of quarterly bank-level balance sheet observations, I show that there exists significant and meaningful exchange rate sensitivity of cross-border lending activity and total domestic loans. This relationship operates through traditional net export channels, as well as mechanisms specific to banks engaged in international lending. Further, I show that exchange rate innovations represent a source of long run lending volatility equivalent to monetary policy shocks for small banks. Lastly, exchange rate movements are shown to be associated with a four-fold increase in growth of non-performing loans for small banks, providing direct evidence of transfer risk for cross-border banks.

Organizational Contributions to Healthcare Worker (HCW) Burnout and Workplace Violence (WPV) Overlap: Is This an Opportunity to Sustain Prevention of Both?  [PDF]
Michael R. Privitera
Health (Health) , 2016, DOI: 10.4236/health.2016.86056
Abstract: The effects of Burnout in healthcare workers (HCW) are experienced by the worker, other staff, the institution and patients under their care on a daily basis. Workplace violence (WPV) has a spectrum of forms. In more extreme forms it generally is low frequency but has high impact when it occurs. Healthcare systems’ efforts to reduce Burnout are more likely to remain sustained since the impact is experienced daily and awareness is increasingly publicized. The efforts to reduce WPV are harder to sustain due to the lower frequency combined with daily competing administrative demands despite best intentions. Could efforts to reduce the overlapping organizational contributions to both HCW Burnout and WPV be a strategy to sustain prevention of WPV while preventing Burnout? A model of overlapping organizational contributions to HCW Burnout and WPV is built from supporting literature. Recommendations are made for leadership and management style interventions. Potential benefits would be higher quality and satisfaction in patient care by means of higher satisfaction in the delivery of care, recruitment and retention of excellent staff, retention of high quality institutional knowledge and reputation.
Addressing Human Factors in Burnout and the Delivery of Healthcare: Quality & Safety Imperative of the Quadruple Aim  [PDF]
Michael R. Privitera
Health (Health) , 2018, DOI: 10.4236/health.2018.105049
Abstract: Human factors in the delivery of service are considered in many occupations of high impact on others such as airline industry and nuclear power industry, but not sufficiently in healthcare delivery. A common administrative framework of healthcare involves focus upon costs, quality and patient satisfaction (The Triple Aim). Many industries which support healthcare and healthcare administrators do not have firsthand knowledge of the complexities in delivering care. As a result, the experience and human factors of providing care are often overlooked at high level decision-making unless incorporated into the healthcare delivery framework, proposed as the fourth aim of The Quadruple Aim framework. Research is pointing to consequent negative effects on quality, safety, joy, meaning and sustainability of healthcare practice. High acute occupational stress and chronic occupational stress can cause direct and indirect effects on safety and quality of care. The biological, psychological and social consequences of burnout from excessive acute and chronic occupational stress are more of a threat to healthcare than commonly acknowledged. Patient safety, quality of care and clinician well-being are inextricably linked. This report will describe the process of transition from The Triple Aim to The Quadruple Aim administrative framework of healthcare delivery at the University of Rochester Medical Center. Developing the fourth aim of improving the experience of providing care, had high acceptability and aligned with other health system goals of optimization of safety, quality, and performance by applying a human factors/ergonomic (HFE) framework that considers human capabilities and human limitations. The goal of HFE is to fit the healthcare system to the human instead of the human to the healthcare system. Concepts include removal of extraneous cognitive load, using clinician neural resource (brain power) optimally for highest order decision making in patient care. An integrative model of patient safety and clinician wellbeing is a product of this effort.
A General Framework For Determining the Temporal and Evolutionary Dynamics of Religion-Based Website Popularity on the Internet  [PDF]
Michael R. Golinski, Connie Petersen
Open Journal of Statistics (OJS) , 2012, DOI: 10.4236/ojs.2012.24052
Abstract: Religion-based websites are fast becoming a major pipeline for disseminating religious information to broad populations of individuals in the United States.Both mainstream religions and fringe religions are easily accessible to a large population of internet users. The purpose of this review is to develop and examine a general framework that uses simple mathematical and statistical models to interpret and measure temporal ‘snap shots’ in the popularity of religious websites. We extend this framework to include an evolutionary model that has the potential to predict long-term shifts or changes in the popularity of religious websites over time. Ultimately, the goal of this review is to introduce a new modeling framework for research into how the internet is changing the accessibility and views of populations of individuals who follow various religions on the internet and how this may in-turn affect the distribution of religion in the ‘real world’.
Extremal Black Hole in a Nonlinear Newtonian Theory of Gravity
Michael R. R. Good
Physics , 2008,
Abstract: This work investigates an upper-limit of charge for a black hole in a nonlinear Newtonian theory of gravity. The charge is accumulated via protons fired isotropically at the black hole. This theoretical study of gravity (known as `pseudo-Newtonian') is a forced merger of special relativity and Newtonian gravity. Whereas the source of Newton's gravity is purely mass, pseudo-Newtonian gravity includes effects of fields around the mass, giving a more complete picture of how gravity behaves. Interestingly, pseudo-Newtonian gravity predicts such relativistic phenomena as black holes and deviations from Kepler's laws, but of course, provides a less accurate picture than general relativity. Though less accurate, it offers an easier approach to understanding some results of general relativity, and merits interest due to its simplicity. The method of study applied here examines the predictions of pseudo-Newtonian gravity for a particle interacting with a highly charged black hole. A black hole with a suitable charge will reach an upper limit (expressed by pseudo-Newtonian gravity) in charge capacity before Coulomb's law repels like-charge particles away from the hole. In particular, this work attempts to push pseudo-Newtonian gravity to its extreme and discover how its results differ from general relativistic predictions involving the same proton bombardment. It is found that the results for an upper limit of charge in general relativity and this nonlinear theory of Newtonian gravity differ by a factor of four. This may give insight into the importance of space-time curvature effects on the description of particle dynamics around a black hole.
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