Now showing items 5838-5857 of 10044

    • Modelling the Milky Way – I. Method and first results fitting the thick disc and halo with DES-Y3 data

      Pieres, A; Girardi, L; Balbinot, E; Santiago, B; da Costa, L N; Carnero Rosell, A; Pace, A B; Bechtol, K; Groenewegen, M A T; Drlica-Wagner, A; et al. (OXFORD UNIV PRESS, 2020-07-09)
      We present a technique to fit the stellar components of the Galaxy by comparing Hess Diagrams (HDs) generated from TRILEGAL models to real data. We apply this technique, which we call MWFITTING, to photometric data from the first 3 yr of the Dark Energy Survey (DES). After removing regions containing known resolved stellar systems such as globular clusters, dwarf galaxies, nearby galaxies, the Large Magellanic Cloud, and the Sagittarius Stream, our main sample spans a total area of similar to 2300 deg(2). We further explore a smaller subset (similar to 1300 deg(2)) that excludes all regions with known stellar streams and stellar overdensities. Validation tests on synthetic data possessing similar properties to the DES data show that the method is able to recover input parameters with a precision better than 3 per cent. We fit the DES data with an exponential thick disc model and an oblate double power-law halo model. We find that the best-fitting thick disc model has radial and vertical scale heights of 2.67 +/- 0.09 kpc and 925 +/- 40 pc, respectively. The stellar halo is fit with a broken power-law density profile with an oblateness of 0.75 +/- 0.01, an inner index of 1.82 +/- 0.08, an outer index of 4.14 +/- 0.05, and a break at 18.52 +/- 0.27 kpc from the Galactic centre. Several previously discovered stellar overdensities are recovered in the residual stellar density map, showing the reliability of MWFITTING in determining the Galactic components. Simulations made with the best-fitting parameters are a promising way to predict Milky Way star counts for surveys such as the LSST and Euclid.
    • Modelling the path length of aluminium seen by the detectors in the MIRI instrument on the JWST

      Glasse, Alistair C. H.; Lee, David; Samara-Ratna, Piyal; Rieke, George R.; Steward Observatory, University of Arizona (SPIE, 2020-12-13)
      The MIRI instrument on the James Webb Space Telescope is equipped with detectors which are susceptible to signal disruption by the charge deposited from impacting cosmic rays. In order to quantify the degree to which the structure of MIRI will shield the detectors, we have used an opto-mechanical ray tracing approach, whereby the solid bodies in a detailed 3D model of the instrument are substituted with an absorptive glassy material. By importing this modified model into a ray tracing program (Tracepro) and then launching many rays from the detector, we have been able to generate a map of aluminium path length as a function of direction. We find that there is a minimum thickness of 2 to 3 mm over a few patches which subtend no more than 1.5 % of the sky for the worst case, imager detector. We discuss the performance of the shielding provided by the MIRI structure, concluding that this minimum thickness of aluminium is sufficient to suppress the impact of low energy protons below the level of the unavoidable flux due to high energy cosmic rays.
    • Modelling ultraviolet-line diagnostics of stars, the ionized and the neutral interstellar medium in star-forming galaxies

      Vidal-García, A.; Charlot, S.; Bruzual, G.; Hubeny, I.; Univ Arizona, Steward Observ; Univ Arizona, Dept Astron (OXFORD UNIV PRESS, 2017-09)
      We combine state-of-the-art models for the production of stellar radiation and its transfer through the interstellar medium (ISM) to investigate ultraviolet-line diagnostics of stars, the ionized and the neutral ISM in star-forming galaxies. We start by assessing the reliability of our stellar population synthesis modelling by fitting absorption-line indices in the ISM-free ultraviolet spectra of 10 Large Magellanic Cloud clusters. In doing so, we find that neglecting stochastic sampling of the stellar initial mass function in these young (similar to 10-100 Myr), low-mass clusters affects negligibly ultraviolet-based age and metallicity estimates but can lead to significant overestimates of stellar mass. Then, we proceed and develop a simple approach, based on an idealized description of the main features of the ISM, to compute in a physically consistent way the combined influence of nebular emission and interstellar absorption on ultraviolet spectra of star-forming galaxies. Our model accounts for the transfer of radiation through the ionized interiors and outer neutral envelopes of short-lived stellar birth clouds, as well as for radiative transfer through a diffuse intercloud medium. We use this approach to explore the entangled signatures of stars, the ionized and the neutral ISM in ultraviolet spectra of star-forming galaxies. We find that, aside from a few notable exceptions, most standard ultraviolet indices defined in the spectra of ISM-free stellar populations are prone to significant contamination by the ISM, which increases with metallicity. We also identify several nebular-emission and interstellar-absorption features, which stand out as particularly clean tracers of the different phases of the ISM.
    • Models of Saturn's Interior Constructed with an Accelerated Concentric Maclaurin Spheroid Method

      Militzer, B.; Wahl, S.; Hubbard, W. B.; Univ Arizona, Lunar & Planetary Lab (IOP PUBLISHING LTD, 2019-07-08)
      The Cassini spacecraft's Grand Finale orbits provided a unique opportunity to probe Saturn's gravity field and interior structure. Doppler measurements yielded unexpectedly large values for the gravity harmonics J(6), J(8), and J(10), which cannot be matched using planetary interior models that assume uniform rotation. Instead we present a suite of models that assume the planet's interior rotates on cylinders, which allows us to match all the observed even gravity harmonics. For every interior model, the gravity field is calculated self-consistently with high precision using the Concentric Maclaurin Spheroid method. We present an acceleration technique for this method, which drastically reduces the computational cost, allows us to efficiently optimize model parameters and map out allowed parameter regions with Monte Carlo sampling, and increases the precision of the calculated J(2n) gravity harmonics to match the error bars of the observations, which would be difficult without acceleration. Based on our models, Saturn is predicted to have a dense central core of similar to 15-18 Earth masses and an additional 1.5-5 Earth masses of heavy elements in the envelope. Finally, we vary the rotation period in the planet's deep interior and determine the resulting oblateness, which we compare with the value from radio occultation measurements by the Voyager spacecraft. We predict a rotation period of 10:33:34 hr +/- 55 s, which is in agreement with recent estimates derived from ring seismology.
    • Models to predict sunlight-induced photodegradation rates of contaminants in wastewater stabilisation ponds and clarifiers

      Niu, Xi-Zhi; Univ Arizona, Dept Chem & Environm Engn; Univ Arizona, Arizona Lab Emerging Contaminants (EDITORIAL BOARD WATER SCIENCE & ENGINEERING, 2019-12)
      Two kinetic models were established for conservative estimates of photodegradation rates of contaminants under sunlight irradiation, in particular for wastewater stabilisation ponds and clarifiers in conventional wastewater treatment plants. These two models were designated for (1) contaminants with high photolytic rates or high photolytic quantum yields, whose photodegradation is unlikely to be enhanced by aquatic photosensitisers; and (2) contaminants withstanding direct photolysis in sunlit waters but subjected to indirect photolysis. The effortlessly intelligible prediction procedure involves sampling and analysis of real water samples, simulated solar experiments in the laboratory, and transfer of the laboratory results to realise water treatment using the prediction models. Although similar models have been widely used for laboratory studies, this paper provides a preliminary example of translating laboratory results to the photochemical fate of contaminants in real waters. (C) 2019 Hohai University. Production and hosting by Elsevier B.V.
    • Moderate-resolution K-band Spectroscopy of Substellar Companion κ Andromedae b

      Wilcomb, Kielan K.; Konopacky, Quinn M.; Barman, Travis S.; Theissen, Christopher A.; Ruffio, Jean-Baptiste; Brock, Laci; Macintosh, Bruce; Marois, Christian; Univ Arizona, Lunar & Planetary Lab (IOP PUBLISHING LTD, 2020-10-15)
      We present moderate-resolution (R similar to 4000) K-band spectra of the "super-Jupiter,"kappa Andromedae b. The data were taken with the OSIRIS integral field spectrograph at Keck Observatory. The spectra reveal resolved molecular lines from H2O and CO, and are compared to a custom PHOENIX atmosphere model grid appropriate for young planetary-mass objects. We fit the data using a Markov chain Monte Carlo forward-modeling method. Using a combination of our moderate-resolution spectrum and low-resolution, broadband data from the literature, we derive an effective temperature of T-eff = 1950-2150 K, a surface gravity of log g = 3.5-4.5, and a metallicity of [M/H] = -0.2-0.0. These values are consistent with previous estimates from atmospheric modeling and the currently favored young age of the system (<50 Myr). We derive a C/O ratio of 0.70(-0.24)(+0.09) for the source, broadly consistent with the solar C/O ratio. This, coupled with the slightly subsolar metallicity, implies a composition consistent with that of the host star, and is suggestive of formation by a rapid process. The subsolar metallicity of kappa Andromedae b is also consistent with predictions of formation via gravitational instability. Further constraints on formation of the companion will require measurement of the C/O ratio of kappa Andromedae A. We also measure the radial velocity of kappa Andromedae b for the first time, with a value of -1.4 +/- 0.9 km s(-1) relative to the host star. We find that the derived radial velocity is consistent with the estimated high eccentricity of kappa Andromedae b.
    • A moderately precise dynamical age for the Homunculus of Eta Carinae based on 13 years of HST imaging

      Smith, Nathan; Univ Arizona, Steward Observ (OXFORD UNIV PRESS, 2017-11)
      The Hubble Space Telescope archive contains a large collection of images of eta Carinae, and this paper analyses those most suitable for measuring its expanding Homunculus Nebula. Multiple intensity tracings through the Homunculus reveal the fractional increase in the overall size of the nebula; this avoids registration uncertainty, mitigates brightness fluctuations, and is independent of previous methods. Combining a 13 yr baseline ofWide Field Planetary Camera 2 images in the F631N filter, with a 4 yr baseline of Advanced Camera for Surveys/ High Resolution Channel images in the F550M filter, yields an ejection date (assuming linear motion) of 1847.1 (+/- 0.8 yr). This result improves the precision, but is in excellent agreement with the previous study by Morse et al., that used a shorter time baseline and a different analysis method. This more precise date is inconsistent with ejection during a periastron passage of the eccentric binary. Ejection occurred well into the main plateau of the Great Eruption, and not during the brief peaks in 1843 and 1838. The age uncertainty is dominated by a real spread in ages of various knots, and by some irregular brightness fluctuations. Several knots appear to have been ejected decades before or after the mean date, implying a complicated history of mass-loss episodes outside the main bright phase of the eruption. The extended history of mass ejection may have been largely erased by the passage of a shock through clumpy ejecta, as most material was swept into a thin shell with nearly uniform apparent age.
    • The modern evolution of geomorphology — Binghamton and personal perspectives, 1970–2019 and beyond

      Baker, Victor R.; Univ Arizona, Dept Hydrol & Atmospher Sci (Elsevier BV, 2020-10)
      The annual Binghamton Geomorphology Symposia (BGS) began in 1970, initiated by Professors Donald R. Coates and Marie Morisawa of the State University of New York at Binghamton. The 50 BGS meeting topics through 2019 can be organized into five general themes, as follows: (1) Applications; (2) Methods; (3) Process and Form; (4) History, Philosophy, and Theory; (5) Systems. My own geomorphological research can be divided among these themes, though it has not always been in tune with any prevailing paradigm. The experience of the BGS meetings suggests that the immediate future of geomorphology will follow current trends involving technological advances in such areas as geochronology, geospatial analysis, lidar mapping, computer simulation, and systems-based predictive modeling. For the longer term it may be that the research frontiers will lie in outer and inner space, with the former involving the discovery and analysis of the surfaces of Earth-like planets within and beyond our own solar system. The challenges of inner space may be even more profound as they are imposed against the background of rapidly accelerating advances in artificial intelligence. (C) 2019 Elsevier B.V. All rights reserved.
    • Modern technologies of fabrication and testing of large convex secondary mirrors

      Oh, Chang Jin; Lowman, Andrew E.; Dubin, Matt; Smith, Greg; Frater, Eric; Zhao, Chunyu; Burge, James H.; Univ Arizona, Coll Opt Sci; College of Optical Sciences, The Univ. of Arizona (United States); College of Optical Sciences, The Univ. of Arizona (United States); et al. (SPIE-INT SOC OPTICAL ENGINEERING, 2016-07-22)
      Modern large telescopes such as TAO, LSST, TMT and EELT require 0.9m-4m monolithic convex secondary mirrors. The fabrication and testing of these large convex secondary mirrors of astronomical telescopes is getting challenging as the aperture of the mirror is getting bigger. The biggest challenge to fabricate these large convex aspheric mirrors is to measure the surface figure to a few nanometers, while maintaining the testing and fabrication cycle to be efficient to minimize the downtime. For the last a couple of decades there was huge advancement in the metrology and fabrication of large aspheric secondary mirrors. College of Optical Sciences in the University Arizona developed a full fabrication and metrology process with extremely high accuracy and efficiency for manufacturing the large convex secondary mirrors. In this paper modern metrology systems including Swing-Arm Optical Coordinate Measuring System (SOCMM) which is comparable to Interferometry and a Sub-aperture stitching interferometry scalable to a several meters have been presented. Also a Computer Controlled Fabrication Process which produces extremely fine surface figure and finish has been demonstrated. These most recent development has been applied to the fabrication and testing of 0.9m aspheric convex secondary mirror for the Tokyo Atacama Observatory's 6.5m telescope and the result has been presented.
    • Modern Ultra-Wideband Communications: Recent Overview and Future Prospects

      Gao, Xin; Huai, Lian; Univ Arizona, Dept Elect & Comp Engn (Inderscience, 2020-10)
      Regarding the modulation schemes and multiple access techniques, modern ultra-wideband (UWB) communication displays unique features in wideband, high-speed data transmission, low-power consumption and high security comparing to other wireless communication systems. We present a general review of historical development, key features and typical applications on UWB, then briefly discuss its recent progress in IEEE standards, application potentials for broadband wireless access and current benefits. Future development on UWB transmission schemes and challenges of system design, are concisely proposed in contrast to those of several other typical communication systems.
    • Modes and Approaches of Groundwater Governance: A Survey of Lessons Learned from Selected Cases across the Globe

      Varady, Robert; Zuniga-Teran, Adriana; Gerlak, Andrea; Megdal, Sharon; Univ Arizona, Udall Ctr Studies Publ Policy; Univ Arizona, Sch Geog & Dev; Univ Arizona, Coll Agr & Life Sci, Water Resources Res Ctr (MDPI AG, 2016-09-23)
      The crucial role of groundwater and the centrality of water governance in accommodating growing water demands sustainably are becoming well recognized. We review 10 case studies of groundwater governance-representing diverse global regions and local contexts-from the perspective of four well-established elements: (1) institutional setting; (2) availability and access to information and science; (3) robustness of civil society; and (4) economic and regulatory frameworks. For institutional setting, we find that governing is often a thankless task that paradoxically requires popularity; legislation does not always translate to implementation; conflict resolution is central to governance; and funding is critical for governance. In terms of information access, we see: a need for research for natural systems, social systems, and institutions; trust as an essential element in research; and that urbanized landscapes are critical components of groundwater governance. Looking at civil society robustness, we observe that equity is an essential element for governance; community-based governance requires intention; and leaders can play a powerful role in uniting stakeholders. As for frameworks, the cases suggest that economic incentives sometimes yield unintended results; "indirect" management should be used cautiously; and economic incentives' effectiveness depends on the system employed. Collectively, the lessons speak to the need for shared governance capacities on the part of governments at multiple levels and civil society actors.
    • Modification and upgrade of AzRISE/TEP solar photovoltaic test yard

      Bennett, Whit; Fishgold, Asher; Lai, Teh; Elwood, Teri; Potter, Barrett G.; Simmons-Potter, Kelly; Univ Arizona; The Univ. of Arizona (United States); The Univ. of Arizona (United States); The Univ. of Arizona (United States); et al. (SPIE-INT SOC OPTICAL ENGINEERING, 2016-09-26)
      The University of Arizona AzRISE (Arizona Research Institute for Solar Energy) and Tucson Electric Power solar test yard is currently undergoing renovations to upgrade and standardize the data acquisition capabilities throughout the yard. Test yard improvements have enabled increased data collection reliability through state-of-the-art and environmentally-robust data logging and real-time analysis. Enhanced capabilities include 10 msec max. data resolution, precision PV backside temperature monitoring of both individual and strings of modules, measurement of both AC and DC outputs as well as GHI and POA irradiance, active data backup to eliminate data intermittency, and robust Ethernet connectivity for data collection. An on-site weather station, provides wind speed and direction, relative humidity, and air temperature data. The information collected is accessed remotely via web server and includes raw performance and environmental conditions as well as extracted figures of performance for systems under test. Complementing the UA's existing accelerated environmental-testing chamber, the new test yard acquisition capabilities have enabled high fidelity system and sub-system-level operational testing under a range of field-level test conditions. The combined facilities, thus, provide a full-spectrum testing resource for photovoltaic performance and degradation analysis. Specific measurement characteristics and sample data collected from a polysilicon module test string are utilized to illustrate test yard capabilities.
    • Modification of spintronic terahertz emitter performance through defect engineering

      Nenno, Dennis M; Scheuer, Laura; Sokoluk, Dominik; Keller, Sascha; Torosyan, Garik; Brodyanski, Alexander; Lösch, Jörg; Battiato, Marco; Rahm, Marco; Binder, Rolf H; et al. (NATURE PUBLISHING GROUP, 2019-09-16)
      Spintronic ferromagnetic/non-magnetic heterostructures are novel sources for the generation of THz radiation based on spin-to-charge conversion in the layers. The key technological and scientific challenge of THz spintronic emitters is to increase their intensity and frequency bandwidth. Our work reveals the factors to engineer spintronic Terahertz generation by introducing the scattering lifetime and the interface transmission for spin polarized, non-equilibrium electrons. We clarify the influence of the electron-defect scattering lifetime on the spectral shape and the interface transmission on the THz amplitude, and how this is linked to structural defects of bilayer emitters. The results of our study define a roadmap of the properties of emitted as well as detected THz-pulse shapes and spectra that is essential for future applications of metallic spintronic THz emitters.
    • Modifications of Sarcoplasmic Reticulum Function Prevent Progression of Sarcomere-Linked Hypertrophic Cardiomyopathy Despite a Persistent Increase in Myofilament Calcium Response

      Chowdhury, Shamim A K; Warren, Chad M; Simon, Jillian N; Ryba, David M; Batra, Ashley; Varga, Peter; Kranias, Evangelia G; Tardiff, Jil C; Solaro, R John; Wolska, Beata M; et al. (FRONTIERS MEDIA SA, 2020-03-10)
      Hypertrophic cardiomyopathy (HCM) is a genetic disorder caused by mutations in different genes mainly encoding myofilament proteins and therefore called a "disease of the sarcomere." Despite the discovery of sarcomere protein mutations linked to HCM almost 30 years ago, the cellular mechanisms responsible for the development of this disease are not completely understood and likely vary among different mutations. Moreover, despite many efforts to develop effective treatments for HCM, these have largely been unsuccessful, and more studies are needed to better understand the cellular mechanisms of the disease. In experiments reported here, we investigated a mouse model expressing the mutant cTnT-R92Q, which is linked to HCM and induces an increase in myofilament Ca2+ sensitivity and diastolic dysfunction. We found that early correction of the diastolic dysfunction by phospholamban knockout (PLNKO) was able to prevent the development of the HCM phenotype in troponin T (TnT)-R92Q transgenic (TG) mice. Four groups of mice in FVB/N background were generated and used for the experiments: (1) non-transgenic (NTG)/PLN mice, which express wild-type TnT and normal level of PLN; (2) NTG/PLNKO mice, which express wild-type TnT and no PLN; (3) TG/PLN mice, which express TnT-R92Q and normal level of PLN; (4) TG/PLNKO mice, which express TnT-R92Q and no PLN. Cardiac function was determined using both standard echocardiographic parameters and speckle tracking strain measurements. We found that both atrial morphology and diastolic function were altered in TG/PLN mice but normal in TG/PLNKO mice. Histological analysis showed a disarray of myocytes and increased collagen deposition only in TG/PLN hearts. We also observed increased Ca2+/calmodulin-dependent protein kinase II (CaMKII) phosphorylation only in TG/PLN hearts but not in TG/PLNKO hearts. The rescue of the HCM phenotype was not associated with differences in myofilament Ca2+ sensitivity between TG/PLN and TG/PLNKO mice. Moreover, compared to standard systolic echo parameters, such as ejection fraction (EF), speckle strain measurements provided a more sensitive approach to detect early systolic dysfunction in TG/PLN mice. In summary, our results indicate that targeting diastolic dysfunction through altering Ca2+ fluxes with no change in myofilament response to Ca2+ was able to prevent the development of the HCM phenotype and should be considered as a potential additional treatment for HCM patients.
    • A Modified Behavior Risk Factor Surveillance System to Assess Diabetes Self-management Behaviors and Diabetes Care in Monterrey Mexico: A Cross-sectional Study

      McEwen, Marylyn Morris; Elizondo-Pereo, Rogelio Andrès; Pasvogel, Alice E.; Meester, Irene; Vargas-Villarreal, Javier; González-Salazar, Francisco; Univ Arizona, Coll Nursing; Univ Arizona, Mel & Enid Zuckerman Coll Publ Hlth (FRONTIERS MEDIA SA, 2017-05-02)
      Type 2 diabetes mellitus (T2DM) is one of the leading causes of death from worldwide non-communicable diseases. The prevalence of diabetes in the Mexico (MX)-United States border states exceeds the national rate in both countries. The economic burden of diabetes, due to decreased productivity, disability, and medical costs, is staggering and increases significantly when T2DM-related complications occur. The purpose of this study was to use a modified behavioral risk factor surveillance system (BRFSS) to describe the T2DM self-management behaviors, diabetes care, and health perception of a convenience sample of adults with T2DM in Monterrey, MX. This cross-sectional study design, with convenience sampling, was conducted with a convenience sample (n = 351) of adults in the metropolitan area of Monterrey, MX who self-reported a diagnosis of T2DM. Potential participants were recruited from local supermarkets. Twenty-six diabetes and health-related items were selected from the BRFSS and administered in face-to-face interviews by trained data collectors. Data analysis was conducted using descriptive statistics. The mean age was 47 years, and the mean length of time with T2DM was 12 years. The majority was taking oral medication and 34% required insulin. Daily self-monitoring of feet was performed by 56% of the participants; however, only 8.8% engaged in blood glucose self-monitoring. The mean number of health-care provider visits was 9.09 per year, and glycated hemoglobin level (HbA1c) was assessed 2.6 times per year. Finally, only 40.5% of the participants recalled having a dilated eye exam. We conclude the modified BRFSS survey administered in a face-to-face interview format is an appropriate tool for assessing engagement in T2DM self-management behaviors, diabetes care, and health perception. Extension of the use of this survey in a more rigorous design with a larger scale survey is encouraged.
    • Modified gemcitabine plus nab-paclitaxel regimen in advanced pancreatic ductal adenocarcinoma

      Rogers, Jane E; Mizrahi, Jonathan D; Xiao, Lianchun; Mohindroo, Chirayu; Shroff, Rachna T; Wolff, Robert; Varadhachary, Gauri R; Javle, Milind M; Overman, Michael; Fogelman, David R; et al. (WILEY, 2020-06-09)
      Gemcitabine (GEM) plus nab-paclitaxel (NabP) (GEM 1000 mg/m2 IV over 30 minutes + NabP 125 mg/m2 IV given days 1, 8, and 15 every 28 days) is one of the two standard of care combination therapies for metastatic pancreatic ductal adenocarcinoma (PDAC). Our cancer center has utilized GEM-NabP given every two-weeks due to tolerability and patient convenience. Here, we review the safety and efficacy of this modified regimen.
    • A modified method of discontinuity trace mapping using three-dimensional point clouds of rock mass surfaces

      Zhang, Keshen; Wu, Wei; Zhu, Hehua; Zhang, Lianyang; Li, Xiaojun; Zhang, Hong; Univ Arizona, Dept Civil Engn & Engn Mech (SCIENCE PRESS, 2020-05-04)
      This paper presents an automated method for discontinuity trace mapping using three-dimensional point clouds of rock mass surfaces. Specifically, the method consists of five steps: (1) detection of trace feature points by normal tensor voting theory, (2) contraction of trace feature points, (3) connection of trace feature points, (4) linearization of trace segments, and (5) connection of trace segments. A sensitivity analysis was then conducted to identify the optimal parameters of the proposed method. Three field cases, a natural rock mass outcrop and two excavated rock tunnel surfaces, were analyzed using the proposed method to evaluate its validity and efficiency. The results show that the proposed method is more efficient and accurate than the traditional trace mapping method, and the efficiency enhancement is more robust as the number of feature points increases.
    • A modified Park's stitch to correct aortic insufficiency for bioprosthetic valve at time of left ventricular assist device implant: a case report

      Kazui, Toshinobu; Sydow, Nicole; Friedman, Mark; Kim, Samuel; Lick, Scott; Khalpey, Zain; Univ Arizona, Div Cardiothorac Surg, Banner Univ Med Ctr Tucson; Univ Arizona, Banner Univ Med Ctr Tucson, Div Cardiol (BIOMED CENTRAL LTD, 2016-11-30)
      Background: Aortic valve insufficiency (AI) at the time of left ventricular assist device (LVAD) insertion needs to be corrected, however there is little known about how to manage bioprosthetic valvular AI. Case presentation: A 55-year-old female with dilated cardiomyopathy who previously had a bioprosthetic aortic valve replacement needed a LVAD as a bridge to transplant. Her left ventricular ejection fraction was 10% and had mild to moderate transvalvular AI. She underwent a HeartWare HVAD insertion along with aortic valvular coaptation stitch repair (Park's stitch) to the bioprosthetic valve. Conclusion: Her AI improved to trivial with minimal ejection through the bioprosthetic valve. She was transplanted 6 months following the surgery. A Park's stitch to the bioprosthetic aortic valve with more than mild AI might be a good option for bridge to transplant patient.
    • Modified STOP-Bang Tool for Stratifying Obstructive Sleep Apnea Risk in Adolescent Children

      Combs, Daniel; Goodwin, James L.; Quan, Stuart F.; Morgan, Wayne J.; Parthasarathy, Sairam; Department of Pediatrics, University of Arizona; Arizona Respiratory Center, University of Arizona; Department of Medicine, University of Arizona; Center for Sleep Disorders and Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Arizona (Public Library of Science, 2015-11-18)
      Purpose Obstructive sleep apnea (OSA) is prevalent in children and diagnostic polysomnography is costly and not readily available in all areas. We developed a pediatric modification of a commonly used adult clinical prediction tool for stratifying the risk of OSA and the need for polysomnography. Methods A total of 312 children (age 9–17 years) from phase 2 of the Tucson Children’s Assessment of Sleep Apnea cohort study, with complete anthropomorphic data, parent questionnaires, and home polysomnograms were included. An adolescent modification of STOP-Bang (teen STOP-Bang) was developed and included snoring, tired, observed apnea, blood pressure ≥ 95th percentile, BMI > 95th percentile, academic problems, neck circumference >95th percentile for age, and male gender. An apnea-hypopnea index ≥ 1.5 events/hour was considered diagnostic of OSA. Results Receiver Operator Characteristic (ROC) curves for parent-reported STOP-Bang scores were generated for teenage and pre-teen children. A STOP-Bang score of < 3 in teenagers was associated with a negative predictive value of 0.96. ROC curves were also generated based upon child-reported sexual maturity rating (SMR; n = 291). The ability of teen STOP-Bang to discriminate the presence or absence of OSA as measured by the AUC for children with SMR ≥ 4 (0.83; 95%CI 0.71–0.95) was better than children with SMR < 4 (0.63; 95%CI 0.46–0.81; p = 0.048). Conclusions In community dwelling adolescents, teen STOP-Bang may be useful in stratifying the risk of OSA.
    • Modifier Ontologies for frequency, certainty, degree, and coverage phenotype modifier

      Endara, Lorena; Thessen, Anne E; Cole, Heather A; Walls, Ramona; Gkoutos, Georgios; Cao, Yujie; Chong, Steven S; Cui, Hong; Univ Arizona (PENSOFT PUBL, 2018-11-28)
      Background: When phenotypic characters are described in the literature, they may be constrained or clarified with additional information such as the location or degree of expression, these terms are called "modifiers". With effort underway to convert narrative character descriptions to computable data, ontologies for such modifiers are needed. Such ontologies can also be used to guide term usage in future publications. Spatial and method modifiers are the subjects of ontologies that already have been developed or are under development. In this work, frequency (e.g., rarely, usually), certainty (e.g., probably, definitely), degree (e.g., slightly, extremely), and coverage modifiers (e.g., sparsely, entirely) are collected, reviewed, and used to create two modifier ontologies with different design considerations. The basic goal is to express the sequential relationships within a type of modifiers, for example, usually is more frequent than rarely, in order to allow data annotated with ontology terms to be classified accordingly. Method: Two designs are proposed for the ontology, both using the list pattern: a closed ordered list (i.e., five-bin design) and an open ordered list design. The five-bin design puts the modifier terms into a set of 5 fixed bins with interval object properties, for example, one_level_more/less_frequently_than, where new terms can only be added as synonyms to existing classes. The open list approach starts with 5 bins, but supports the extensibility of the list via ordinal properties, for example, more/less_frequently_than, allowing new terms to be inserted as a new class anywhere in the list. The consequences of the different design decisions are discussed in the paper. CharaParser was used to extract modifiers from plant, ant, and other taxonomic descriptions. After a manual screening, 130 modifier words were selected as the candidate terms for the modifier ontologies. Four curators/experts (three biologists and one information scientist specialized in biosemantics) reviewed and categorized the terms into 20 bins using the Ontology Term Organizer (OTO) (http://biosemantics.arizona.edu/OTO). Inter-curator variations were reviewed and expressed in the final ontologies. Results: Frequency, certainty, degree, and coverage terms with complete agreement among all curators were used as class labels or exact synonyms. Terms with different interpretations were either excluded or included using "broader synonym" or "not recommended" annotation properties. These annotations explicitly allow for the user to be aware of the semantic ambiguity associated with the terms and whether they should be used with caution or avoided. Expert categorization results showed that 16 out of 20 bins contained terms with full agreements, suggesting differentiating the modifiers into 5 levels/bins balances the need to differentiate modifiers and the need for the ontology to reflect user consensus. Two ontologies, developed using the Protege ontology editor, are made available as OWL files and can be downloaded from https://github.com/biosemantics/ontologies. Contribution: We built the first two modifier ontologies following a consensus-based approach with terms commonly used in taxonomic literature. The five-bin ontology has been used in the Explorer of Taxon Concepts web toolkit to compute the similarity between characters extracted from literature to facilitate taxon concepts alignments. The two ontologies will also be used in an ontology-informed authoring tool for taxonomists to facilitate consistency in modifier term usage.