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Search Results: 1 - 10 of 3979 matches for " Ryan Kukor "
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On the optimal stacking of noisy observations
?. Ryan
Mathematics , 2010,
Abstract: Observations where additive noise is present can for many models be grouped into a compound observation matrix, adhering to the same type of model. There are many ways the observations can be stacked, for instance vertically, horizontally, or quadratically. An estimator for the spectrum of the underlying model can be formulated for each stacking scenario in the case of Gaussian noise. We compare these spectrum estimators for the different stacking scenarios, and show that all kinds of stacking actually decreases the variance when compared to just taking an average of the observations. We show that, regardless of the number of observations, the variance of the estimator is smallest when the compound observation matrix is made as square as possible. When the number of observations grow, however, it is shown that the difference between the estimators is marginal: Two stacking scenarios where the number of columns and rows grow to infinity are shown to have the same variance asymptotically, even if the asymptotic matrix aspect ratios differ. Only the cases of vertical and horizontal stackings display different behaviour, giving a higher variance asymptotically. Models where not all kinds of stackings are possible are also discussed.
The Entomopathogenic Bacterial Endosymbionts Xenorhabdus and Photorhabdus: Convergent Lifestyles from Divergent Genomes
John M. Chaston, Garret Suen, Sarah L. Tucker, Aaron W. Andersen, Archna Bhasin, Edna Bode, Helge B. Bode, Alexander O. Brachmann, Charles E. Cowles, Kimberly N. Cowles, Creg Darby, Limaris de Léon, Kevin Drace, Zijin Du, Alain Givaudan, Erin E. Herbert Tran, Kelsea A. Jewell, Jennifer J. Knack, Karina C. Krasomil-Osterfeld, Ryan Kukor, Anne Lanois, Phil Latreille, Nancy K. Leimgruber, Carolyn M. Lipke, Renyi Liu, Xiaojun Lu, Eric C. Martens, Pradeep R. Marri, Claudine Médigue, Megan L. Menard, Nancy M. Miller, Nydia Morales-Soto, Stacie Norton, Jean-Claude Ogier, Samantha S. Orchard, Dongjin Park, Youngjin Park, Barbara A. Qurollo, Darby Renneckar Sugar, Gregory R. Richards, Zoé Rouy, Brad Slominski, Kathryn Slominski, Holly Snyder, Brian C. Tjaden, Ransome van der Hoeven, Roy D. Welch, Cathy Wheeler, Bosong Xiang, Brad Barbazuk, Sophie Gaudriault, Brad Goodner, Steven C. Slater, Steven Forst, Barry S. Goldman, Heidi Goodrich-Blair
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0027909
Abstract: Members of the genus Xenorhabdus are entomopathogenic bacteria that associate with nematodes. The nematode-bacteria pair infects and kills insects, with both partners contributing to insect pathogenesis and the bacteria providing nutrition to the nematode from available insect-derived nutrients. The nematode provides the bacteria with protection from predators, access to nutrients, and a mechanism of dispersal. Members of the bacterial genus Photorhabdus also associate with nematodes to kill insects, and both genera of bacteria provide similar services to their different nematode hosts through unique physiological and metabolic mechanisms. We posited that these differences would be reflected in their respective genomes. To test this, we sequenced to completion the genomes of Xenorhabdus nematophila ATCC 19061 and Xenorhabdus bovienii SS-2004. As expected, both Xenorhabdus genomes encode many anti-insecticidal compounds, commensurate with their entomopathogenic lifestyle. Despite the similarities in lifestyle between Xenorhabdus and Photorhabdus bacteria, a comparative analysis of the Xenorhabdus, Photorhabdus luminescens, and P. asymbiotica genomes suggests genomic divergence. These findings indicate that evolutionary changes shaped by symbiotic interactions can follow different routes to achieve similar end points.
Site Specific Uncertainty in Regional Haze RuleHaze Indexes  [PDF]
Patrick A. Ryan
Atmospheric and Climate Sciences (ACS) , 2012, DOI: 10.4236/acs.2012.21001
Abstract: In 1999, the US Environmental Protection Agency (EPA) published the regional haze rule (RHR). The RHR default implementation plan calls for each class I area 20% worst baseline (2000-2004) visibility to improve linearly in time to natural conditions in 2064 and in calendar year 2018, each class I area 20% worst visibility is to comply with the 2018 visibility that falls on the linear improvement glide path from baseline (2000-2004) to natural (2064) conditions. This study shows that accurately assessing compliance depends on assessing the uncertainty in baseline, natural and 2018 visibility estimates. This study identifies ±3 dV and ±4 dV of uncertainty in 20% worst natural and baseline visibility estimates. The percent uncertainty in calculated 2018 glide path visibility values ranges from 10% - 45%.
Respiratory Sensitization & Sickness from Welding/Burning Isocyanate Containing Paints  [PDF]
Terrence Stobbe, Ryan Westra
Journal of Geoscience and Environment Protection (GEP) , 2014, DOI: 10.4236/gep.2014.24007

The purpose of this paper is to make the environmental and occupational health community aware of a serious health risk associated with the common practice of burning industrial paint off of metal surfaces during or prior to welding. On four occasions bystanders and welder/burner personnel have experienced illness as a result of being exposed to the combustion products of isocyanate paints that were being burned off metal surfaces. In each case, the burning and the exposed people were outside in an open environment where the health risk was thought to be minimal due to the open environment with nominal wind movement through the work area. In one case, the person (a burner) developed permanent sensitization to phthalic anhydride as a result of the exposure. Phthalic anhydride was determined to be decomposition product of burned isocyanate paint. In the other three cases (which involved very short exposures), between two and six people became ill but did not develop sensitization. Their symptoms included dizziness, nausea, headache, and breathing difficulty the severity of which varied from very uncomfortable to temporarily incapacitating. This paper discusses the circumstances associated with each event, the approach used to determine that phthalic anhydride was a decomposition product, and some practical things that can be done to avoid having employees become victims of exposure.

Support for obesity policy: The effect of perceptions of causes for obesity and national identity in Canada  [PDF]
Ryan Lange, Guy Faulkner
Open Journal of Preventive Medicine (OJPM) , 2012, DOI: 10.4236/ojpm.2012.24067
Abstract: Interventions in Canada to address obesity have largely been limited to individual-level change through education rather than a population-level public policy approach. Little is known about obesity policy support in Canada, and substantial national variation in obesity policy support prevents direct transferability of these policies among nations. Our study recruited 521 young adults for an online survey through leaflets and flyers. We investigated how respondents’ demographics, health characteristics, political attitudes, beliefs regarding causes of obesity, and national identity affected their support for obesity policy. Results showed that there is high support for many obesity policies among Canadian young adults. Including Canadian national identity in regression models was significant in explaining obesity policy support beyond the combined effect of other predictors. Further exploration of national identity, in Canada and elsewhere, has implications for understanding obesity policy support that might assist policy makers in making more informed decisions in addressing obesity.
A decomposition theorem for higher rank Coxeter groups
Ryan Blair,Ryan Ottman
Mathematics , 2010,
Abstract: In this paper, we show that any Coxeter graph which defines a higher rank Coxeter group must have disjoint induced subgraphs each of which defines a hyperbolic or higher rank Coxeter group. We then use this result to demonstrate several classes of Coxeter graphs which define hyperbolic Coxeter groups.
Cyclosporine and Hepatitis C  [PDF]
Ryan Caballes, Mark W. Russo
Open Journal of Organ Transplant Surgery (OJOTS) , 2012, DOI: 10.4236/ojots.2012.24009
Abstract: End stage liver disease from hepatitis C is a leading indication for liver transplantation. Recurrent hepatitis C after liver transplant may lead to cirrhosis and graft failure in up to 25% of recipients five years after liver transplantation. Anti-viral therapy is challenging after liver transplantation due to increased side effects including cytopenias and decreased efficacy compared to the nontransplant population. Tacrolimus and cyclosporine are the most common immunosuppressants used to prevent graft rejection. Tacrolimus is more potent than cyclosporine and may be preferred to cyclosporine. However, cyclosporine may have activity against hepatitis C and may have a theoretical advantage to tacrolimus in hepatitis liver transplant recipients. Cyclosporine may inhibit NS5B and NS5A protein complexes and increase endogenous interferon activity. Cyclophilin inhibitors without immunosuppressive properties are under development and represent a novel mechanisms for inhibiting HCV replication.
Transition to adulthood: A critical role for exercise in building overall well-being  [PDF]
Channakeshava Sokke Umeshappa, Ryan Punambolam
Health (Health) , 2013, DOI: 10.4236/health.2013.57156

A growing number of multidisciplinary studies have reported the beneficial effects of physical activities towards the development of overall well-being and the reduction of chronic illnesses. Physical inactivity is a serious worldwide problem and is considered the key lifestyle factor that negatively influences health and function of individuals. Here we propose that growth kinetics of body and mind and associated disproportionate physical activity may have considerable effects on the increased physical and mental illnesses and premature death rates currently observed in mid to late adulthood people. Children and young adults, being in exponential growth phase and self-motivated to engage in physical activity, possess more cognition, resilience, and mind-body-emotion-spirit integration. In contrast, as our body transitions into adulthood, there is a decline in the growth of body and mind. Furthermore, in this period, adults experience the increased stressors of career and financial demands, time pressure, and family responsibilities. The decline in growth combined with prolonged stress appears to result in reduced cognition, resilience, and mind-body-emotion-spirit integration, leading to sedentary and other faulty lifestyles, which could further lead to a predisposition to maladaptive behaviours and various chronic diseases at a later stage. In agreement with this, currently more than two thirds of the adult population across the world are physically inactive and are failing to perform the daily recommended guidelines of moderate to vigorous exercise. As negative changes and faulty lifestyles begin to occur during and after adulthood transition, creating awareness in people between 29 to 35 years of age about mindful exercise should be considered a national priority. This would allow adults to achieve overall well-being, and increased productivity and life expectancy, reducing health care-associated economic burden placed on the nation.

Nonlinear observer output-feedback MPC treatment scheduling for HIV
Ryan Zurakowski
BioMedical Engineering OnLine , 2011, DOI: 10.1186/1475-925x-10-40
Abstract: In previous work we have developed a model predictive control (MPC) based method for determining optimal treatment interruption schedules for this purpose. In this paper, we introduce a nonlinear observer for the HIV-immune response system and an integrated output-feedback MPC approach for implementing the treatment interruption scheduling algorithm using the easily available viral load measurements. We use Monte-Carlo approaches to test robustness of the algorithm.The nonlinear observer shows robust state tracking while preserving state positivity both for continuous and discrete measurements. The integrated output-feedback MPC algorithm stabilizes the desired steady-state. Monte-Carlo testing shows significant robustness to modeling error, with 90% success rates in stabilizing the desired steady-state with 15% variance from nominal on all model parameters.The possibility of enhancing immune responsiveness to HIV through dynamic scheduling of treatment is exciting. Output-feedback Model Predictive Control is uniquely well-suited to solutions of these types of problems. The unique constraints of state positivity and very slow sampling are addressable by using a special-purpose nonlinear state estimator, as described in this paper. This shows the possibility of using output-feedback MPC-based algorithms for this purpose.The majority of untreated HIV patients, following a brief period of acute infection, enter a long asymptomatic phase of infection characterized by high viral loads, persistent immune activation, and a slow decline in the helper-T cell concentration [1]. Eventually, the concentration of helper-T cells becomes too low to sustain effective immune responses, and opportunistic infections cause a dramatic decline in the patient's health. The slow decline of helper-T cells during the asymptomatic phase was once thought to indicate a slow rate of infection and cell turnover, but it is now known that very fast rates of virus and host cell turnover, as high as
Bayle et la controverse sur l'éternité du monde
Ryan, Todd;
Kriterion: Revista de Filosofia , 2009, DOI: 10.1590/S0100-512X2009000200004
Abstract: dans la remarque h de ? zabarella (jaques) ?, bayle aborde la question traditionnelle de la possibilité de l'éternité du monde. après avoir proposé une reformulation de cette question, bayle soulève deux objections à la position orthodoxe de la création du monde dans le temps. puis il offre sa propre théorie du rapport de dieu avec le temps. en analysant ses arguments, je soutiens, contre jean delvolvé, que bayle considère son hypothèse comme susceptible d'écarter toutes les objections qu'il avait soulevées contre le système orthodoxe de la création ex nihilo.
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