Cholera studies*†

PubMed Central

Pollitzer, R.; Burrows, W.

1955-01-01

Relevant information regarding the numerous problems encountered in cholera immunity is dealt with in great detail in this study. Toxin production, bacterial virulence, serological reactions, and the antigenic structure of V. cholerae are discussed. Natural, passive, and active cholera immunity receives special attention, the authors describing the various means of vaccination as well as the evaluation of the immunity induced. PMID:13240451

Numerical modeling of consolidation processes in hydraulically deposited soils

NASA Astrophysics Data System (ADS)

Brink, Nicholas Robert

Hydraulically deposited soils are encountered in many common engineering applications including mine tailing and geotextile tube fills, though the consolidation process for such soils is highly nonlinear and requires the use of advanced numerical techniques to provide accurate predictions. Several commercially available finite element codes poses the ability to model soil consolidation, and it was the goal of this research to assess the ability of two of these codes, ABAQUS and PLAXIS, to model the large-strain, two-dimensional consolidation processes which occur in hydraulically deposited soils. A series of one- and two-dimensionally drained rectangular models were first created to assess the limitations of ABAQUS and PLAXIS when modeling consolidation of highly compressible soils. Then, geotextile tube and TSF models were created to represent actual scenarios which might be encountered in engineering practice. Several limitations were discovered, including the existence of a minimum preconsolidation stress below which numerical solutions become unstable.

Using effort information with change-in-ratio data for population estimation

USGS Publications Warehouse

Udevitz, Mark S.; Pollock, Kenneth H.

1995-01-01

Most change-in-ratio (CIR) methods for estimating fish and wildlife population sizes have been based only on assumptions about how encounter probabilities vary among population subclasses. When information on sampling effort is available, it is also possible to derive CIR estimators based on assumptions about how encounter probabilities vary over time. This paper presents a generalization of previous CIR models that allows explicit consideration of a range of assumptions about the variation of encounter probabilities among subclasses and over time. Explicit estimators are derived under this model for specific sets of assumptions about the encounter probabilities. Numerical methods are presented for obtaining estimators under the full range of possible assumptions. Likelihood ratio tests for these assumptions are described. Emphasis is on obtaining estimators based on assumptions about variation of encounter probabilities over time.

Facilitating researcher use of flight simulators

NASA Technical Reports Server (NTRS)

Russell, C. Ray

1990-01-01

Researchers conducting experiments with flight simulators encounter numerous obstacles in bringing their ideas to the simulator. Research into how these simulators could be used more efficiently is presented. The study involved: (1) analyzing the Advanced Concepts Simulator software architecture, (2) analyzing the interaction between the researchers and simulation programmers, and (3) proposing a documentation tool for the researchers.

The Not-so-Easy Road of Overseas Study: Life Like an Outsider

ERIC Educational Resources Information Center

Palmer, Yolanda

2015-01-01

Contemplating my graduate student experience overseas, I constantly viewed myself as an isolate, one who did not belong in the new community of practice. I encountered numerous lingua-cultural, academic and social challenges which led to my lack of community and belonging. This paper is a reflection of my experiences as an international graduate…

Orbital Perturbations of the Galilean Satellites during Planetary Encounters

NASA Astrophysics Data System (ADS)

Deienno, Rogerio; Nesvorný, David; Vokrouhlický, David; Yokoyama, Tadashi

2014-08-01

The Nice model of the dynamical instability and migration of the giant planets can explain many properties of the present solar system, and can be used to constrain its early architecture. In the jumping-Jupiter version of the Nice model, required from the terrestrial planet constraint and dynamical structure of the asteroid belt, Jupiter has encounters with an ice giant. Here, we study the survival of the Galilean satellites in the jumping-Jupiter model. This is an important concern because the ice-giant encounters, if deep enough, could dynamically perturb the orbits of the Galilean satellites and lead to implausible results. We performed numerical integrations where we tracked the effect of planetary encounters on the Galilean moons. We considered three instability cases from Nesvorný & Morbidelli that differed in the number and distribution of encounters. We found that in one case, where the number of close encounters was relatively small, the Galilean satellite orbits were not significantly affected. In the other two, the orbital eccentricities of all moons were excited by encounters, Callisto's semimajor axis changed, and, in a large fraction of trials, the Laplace resonance of the inner three moons was disrupted. The subsequent evolution by tides damps eccentricities and can recapture the moons in the Laplace resonance. A more important constraint is represented by the orbital inclinations of the moons, which can be excited during the encounters and not appreciably damped by tides. We find that one instability case taken from Nesvorný & Morbidelli clearly does not meet this constraint. This shows how the regular satellites of Jupiter can be used to set limits on the properties of encounters in the jumping-Jupiter model, and help us to better understand how the early solar system evolved.

Some problems of the calculation of three-dimensional boundary layer flows on general configurations

NASA Technical Reports Server (NTRS)

Cebeci, T.; Kaups, K.; Mosinskis, G. J.; Rehn, J. A.

1973-01-01

An accurate solution of the three-dimensional boundary layer equations over general configurations such as those encountered in aircraft and space shuttle design requires a very efficient, fast, and accurate numerical method with suitable turbulence models for the Reynolds stresses. The efficiency, speed, and accuracy of a three-dimensional numerical method together with the turbulence models for the Reynolds stresses are examined. The numerical method is the implicit two-point finite difference approach (Box Method) developed by Keller and applied to the boundary layer equations by Keller and Cebeci. In addition, a study of some of the problems that may arise in the solution of these equations for three-dimensional boundary layer flows over general configurations.

Micro-PIV Study of Supercritical CO2-Water Interactions in Porous Micromodels

NASA Astrophysics Data System (ADS)

Kazemifar, Farzan; Blois, Gianluca; Christensen, Kenneth T.

2015-11-01

Multiphase flow of immiscible fluids in porous media is encountered in numerous natural systems and engineering applications such as enhanced oil recovery (EOR), and CO2 sequestration among others. Geological sequestration of CO2 in saline aquifers has emerged as a viable option for reducing CO2 emissions, and thus it has been the subject of numerous studies in recent years. A key objective is improving the accuracy of numerical models used for field-scale simulations by incorporation/better representation of the pore-scale flow physics. This necessitates experimental data for developing, testing and validating such models. We have studied drainage and imbibition processes in a homogeneous, two-dimensional porous micromodel with CO2 and water at reservoir-relevant conditions. Microscopic particle image velocimetry (micro-PIV) technique was applied to obtain spatially- and temporally-resolved velocity vector fields in the aqueous phase. The results provide new insight into the flow processes at the pore scale.

Tides Versus Collisions in the Primordial Main Belt

NASA Astrophysics Data System (ADS)

Asphaug, E.; Bottke, W. F., Jr.; Morbidelli, A.; Petit, J.-M.

2000-10-01

Recent numerical and theoretical developments (e.g. Wetherill 1992; Chambers and Wetherill 1998) suggest that hundreds or thousands of Moon- to Mars-sized planetary embryos may have resided between 0.5 and 4 AU during early solar system accretion, to be scattered by mutual encounters and resonant perturbations with Jupiter and Saturn. At the same time, we lack compelling scenarios leading to the origin of iron meteorites, believed to represent the cores from approximately 85 different primordial planetesimals (Kail et al. 1994). Are M-type asteroids such as Kleopatra the exposed cores of these parent bodies? Early solar system collisions have been called upon to excavate this iron (Haack et al. 1996), although numerical impact models (Asphaug 1997) have found this task difficult to achieve, particularly when it is required to occur many dozens of times, yet not a single time for asteroid Vesta. One possibility, consistent with the unusual shape of Kleopatra, is tidal disassembly of collisionally weakened differentiated planetesimals by close encounters with primordial planetary embryos. Differentiation enhances the efficacy of tidal disassembly, which is probably already comparable (Asphaug and Benz 1996) to the efficacy of collisional disassembly, but only for bodies of very low strength. Tidal disassembly has the further advantage of stripping all material from a given isosurface, whereas collisions partition energy into both fast and slow debris, leaving behind a rock mantle. To further explore this idea, in comparison with the efficacy of collisional breakup of differentiated planetesimals, we determine the minimal encounter distances between evolving asteroids and the embryos as modeled by Petit et al. (2000). We then directly simulate these tidal encounters using a smooth particle hydrocode (SPH; Benz and Asphaug 1995), and compare tidal encounters to collisional encounters using the same code.

The Impact of Bullying on School Performance in Six Selected Schools in South Carolina

ERIC Educational Resources Information Center

Cooper, Stephanie A.

2011-01-01

The nation's K-12 schools are faced with numerous critical challenges, such as elevating academic achievement, and meeting No Child Left Behind state standards (Kowalski et al., 2008). But bullying in schools is becoming one of the most challenging issues that school personnel are encountering. In a Stanford University, study it was revealed that…

The Behavior of Regular Satellites during the Nice Model's Planetary Close Encounters

NASA Astrophysics Data System (ADS)

Nogueira, E. C.; Gomes, R. S.; Brasser, R.

2014-10-01

In order to explain the behavior of the regular satellites of the ice planets during the instability phase of the Nice model, we used numerical simulations to investigate the evolution of the satellite systems when these two planets experienced encounters with the gas giants. For the initial conditions we placed an ice planet in between Jupiter and Saturn, according to the evolution of Nice model simulations in a jumping Jupiter scenario (Brasser et al. 2009). We used the MERCURY integrator (Chambers 1999) and we obtained 101 successful runs which kept all planets, of which 24 were jumping Jupiter cases. Subsequently we performed additional numerical integrations in which the ice giant that encountered a gas giant was started on the same orbit but with its regular satellites included. This is done as follows: For each of the 101 basic runs, we save the orbital elements of all objects in the integration at all close encounter events. Then we performed a backward integration to start the system 100 years before the encounter and re-enacted the forward integration with the regular satellites around the ice giant. The final orbital elements of the satellites with respect to the ice planet were used to restart the integration for the next planetary encounter. If we assume that Uranus is the ice planet that had encounters with a gas giant, we considered the satellites Miranda, Ariel, Umbriel, Titania and Oberon with their present orbits. For Neptune we introduced Triton with an orbit with a 15% larger than the actual semi-major axis to account for the tidal decay from the LHB to present time. We also assume that Triton was captured through binary disruption (Agnor and Hamilton 2006, Nogueira et al. 2011) and its orbit was circularized by tides during the 500 million years before the LHB.

Fomalhaut’s Stellar Companions as the Driver of its Morphology

NASA Astrophysics Data System (ADS)

Kaib, Nathan; White, Ethan; Izidoro, Andre

2018-01-01

Fomalhaut A is among the most well-studied nearby stars and has been discovered to possess a putative planetary object as well as a remarkable eccentric dust belt. This eccentric dust belt has often been interpreted as the dynamical signature of one or more planets that elude direct detection. However, the system also contains two other stellar companions residing ~100,000 AU from Fomalhaut A. Using numerical simulations of the system's dynamical evolution, we find that close encounters between Fomalhaut A and B are expected, with a ~25% probability that the two stars have passed within at least 400 AU of each other at some point. Although the outcomes of such encounter histories are extremely varied, these close encounters nearly always excite the eccentricity of Fomalhaut A's dust belt and occasionally yield morphologies very similar to the observed belt. With these results, we argue that close encounters with Fomalhaut A's stellar companions should be considered a plausible mechanism to explain its eccentric belt, especially in the absence of detected planets capable of sculpting the belt's morphology. More broadly, we can also conclude from this work that very wide binary stars may often generate asymmetries in the stellar debris disks they host.

Advances in the computation of transonic separated flows over finite wings

NASA Technical Reports Server (NTRS)

Kaynak, Unver; Flores, Jolen

1989-01-01

Problems encountered in numerical simulations of transonic wind-tunnel experiments with low-aspect-ratio wings are surveyed and illustrated. The focus is on the zonal Euler/Navier-Stokes program developed by Holst et al. (1985) and its application to shock-induced separation. The physical basis and numerical implementation of the method are reviewed, and results are presented from studies of the effects of artificial dissipation, boundary conditions, grid refinement, the turbulence model, and geometry representation on the simulation accuracy. Extensive graphs and diagrams and typical flow visualizations are provided.

Algorithms for Stellar Perturbation Computations on Oort Cloud Comets

NASA Astrophysics Data System (ADS)

Rickman, Hans; Fouchard, Marc; Valsecchi, Giovanni B.; Froeschlé, Christiane

2005-12-01

We investigate different approximate methods of computing the perturbations on the orbits of Oort cloud comets caused by passing stars, by checking them against an accurate numerical integration using Everhart’s RA15 code. The scenario under study is the one relevant for long-term simulations of the cloud’s response to a predefined set of stellar passages. Our sample of stellar encounters simulates those experienced by the Solar System currently, but extrapolated over a time of 1010 years. We measure the errors of perihelion distance perturbations for high-eccentricity orbits introduced by several estimators including the classical impulse approximation and Dybczyński’s (1994, Celest. Mech. Dynam. Astron. 58, 1330 1338) method and we study how they depend on the encounter parameters (approach distance and relative velocity). We introduce a sequential variant of Dybczyński’s approach, cutting the encounter into several steps whereby the heliocentric motion of the comet is taken into account. For the scenario at hand this is found to offer an efficient means to obtain accurate results for practically any domain of the parameter space.

Numerical simulation of the hydrodynamic instabilities of Richtmyer-Meshkov and Rayleigh-Taylor

NASA Astrophysics Data System (ADS)

Fortova, S. V.; Shepelev, V. V.; Troshkin, O. V.; Kozlov, S. A.

2017-09-01

The paper presents the results of numerical simulation of the development of hydrodynamic instabilities of Richtmyer-Meshkov and Rayleigh-Taylor encountered in experiments [1-3]. For the numerical solution used the TPS software package (Turbulence Problem Solver) that implements a generalized approach to constructing computer programs for a wide range of problems of hydrodynamics, described by the system of equations of hyperbolic type. As numerical methods are used the method of large particles and ENO-scheme of the second order with Roe solver for the approximate solution of the Riemann problem.

Finite Element Estimation of Protein-Ligand Association Rates with Post-Encounter Effects: Applications to Calcium binding in Troponin C and SERCA

PubMed Central

Kekenes-Huskey, P. M.; Gillette, A.; Hake, J.; McCammon, J. A.

2012-01-01

We introduce a computational pipeline and suite of software tools for the approximation of diffusion-limited binding based on a recently developed theoretical framework. Our approach handles molecular geometries generated from high-resolution structural data and can account for active sites buried within the protein or behind gating mechanisms. Using tools from the FEniCS library and the APBS solver, we implement a numerical code for our method and study two Ca2+-binding proteins: Troponin C and the Sarcoplasmic Reticulum Ca2+ ATPase (SERCA). We find that a combination of diffusional encounter and internal ‘buried channel’ descriptions provide superior descriptions of association rates, improving estimates by orders of magnitude. PMID:23293662

Finite Element Estimation of Protein-Ligand Association Rates with Post-Encounter Effects: Applications to Calcium binding in Troponin C and SERCA.

PubMed

Kekenes-Huskey, P M; Gillette, A; Hake, J; McCammon, J A

2012-10-31

We introduce a computational pipeline and suite of software tools for the approximation of diffusion-limited binding based on a recently developed theoretical framework. Our approach handles molecular geometries generated from high-resolution structural data and can account for active sites buried within the protein or behind gating mechanisms. Using tools from the FEniCS library and the APBS solver, we implement a numerical code for our method and study two Ca(2+)-binding proteins: Troponin C and the Sarcoplasmic Reticulum Ca(2+) ATPase (SERCA). We find that a combination of diffusional encounter and internal 'buried channel' descriptions provide superior descriptions of association rates, improving estimates by orders of magnitude.

Finite-element estimation of protein-ligand association rates with post-encounter effects: applications to calcium binding in troponin C and SERCA

NASA Astrophysics Data System (ADS)

Kekenes-Huskey, P. M.; Gillette, A.; Hake, J.; McCammon, J. A.

2012-01-01

We introduce a computational pipeline and suite of software tools for the approximation of diffusion-limited binding based on a recently developed theoretical framework. Our approach handles molecular geometries generated from high-resolution structural data and can account for active sites buried within the protein or behind gating mechanisms. Using tools from the FEniCS library and the APBS solver, we implement a numerical code for our method and study two Ca2+-binding proteins: troponin C and the sarcoplasmic reticulum Ca2+ ATPase. We find that a combination of diffusional encounter and internal ‘buried channel’ descriptions provides superior descriptions of association rates, improving estimates by orders of magnitude.

Functional response and population dynamics for fighting predator, based on activity distribution.

PubMed

Garay, József; Varga, Zoltán; Gámez, Manuel; Cabello, Tomás

2015-03-07

The classical Holling type II functional response, describing the per capita predation as a function of prey density, was modified by Beddington and de Angelis to include interference of predators that increases with predator density and decreases the number of killed prey. In the present paper we further generalize the Beddington-de Angelis functional response, considering that all predator activities (searching and handling prey, fight and recovery) have time duration, the probabilities of predator activities depend on the encounter probabilities, and hence on the prey and predator abundance, too. Under these conditions, the aim of the study is to introduce a functional response for fighting the predator and to analyse the corresponding dynamics, when predator-predator-prey encounters also occur. From this general approach, the Holling type functional responses can also be obtained as particular cases. In terms of the activity distribution, we give biologically interpretable sufficient conditions for stable coexistence. We consider two-individual (predator-prey) and three-individual (predator-predator-prey) encounters. In the three-individual encounter model there is a relatively higher fighting rate and a lower killing rate. Using numerical simulation, we surprisingly found that when the intrinsic prey growth rate and the conversion rate are small enough, the equilibrium predator abundance is higher in the three-individual encounter case. The above means that, when the equilibrium abundance of the predator is small, coexistence appears first in the three-individual encounter model. Copyright © 2014 Elsevier Ltd. All rights reserved.

Prospects for asteroid mass determination from close encounters between asteroids: ESA's Gaia space mission and beyond

NASA Astrophysics Data System (ADS)

Ivantsov, Anatoliy; Hestroffer, Daniel; Eggl, Siegfried

2018-04-01

We present a catalog of potential candidates for asteroid mass determination based on mutual close encounters of numbered asteroids with massive perturbers (D>20 km). Using a novel geometric approach tuned to optimize observability, we predict optimal epochs for mass determination observations. In contrast to previous studies that often used simplified dynamical models, we have numerically propagated the trajectories of all numbered asteroids over the time interval from 2013 to 2023 using relativistic equations of motion including planetary perturbations, J2 of the Sun, the 16 major asteroid perturbers and the perturbations due to non-sphericities of the planets. We compiled a catalog of close encounters between asteroids where the observable perturbation of the sky plane trajectory is greater than 0.5 mas so that astrometric measurements of the perturbed asteroids in the Gaia data can be leveraged. The catalog v1.0 is available at ftp://dosya.akdeniz.edu.tr/ivantsov.

Study of the Mutual Interaction Between a Wing Wake and an Encountering Airplane

NASA Technical Reports Server (NTRS)

Walden, A. B.; vanDam, C. P.

1996-01-01

In an effort to increase airport productivity, several wind-tunnel and flight-test programs are currently underway to determine safe reductions in separation standards between aircraft. These programs are designed to study numerous concepts from the characteristics and detection of wake vortices to the wake-vortex encounter phenomenon. As part of this latter effort, computational tools are being developed and utilized as a means of modeling and verifying wake-vortex hazard encounters. The objective of this study is to assess the ability of PMARC, a low-order potential-flow panel method, to predict the forces and moments imposed on a following business-jet configuration by a vortex interaction. Other issues addressed include the investigation of several wake models and their ability to predict wake shape and trajectory, the validity of the velocity field imposed on the following configuration, modeling techniques and the effect of the high-lift system and the empennage. Comparisons with wind-tunnel data reveal that PMARC predicts the characteristics for the clean wing-body following configuration fairly well. Non-linear effects produced by the addition of the high-lift system and empennage, however, are not so well predicted.

Mesoscale Numerical Investigations of Air Traffic Emissions over the North Atlantic during SONEX Flight 8: A Case Study

NASA Technical Reports Server (NTRS)

Bieberbach, George, Jr.; Fuelberg, Henry E.; Thompson, Anne M.; Schmitt, Alf; Hannan, John R.; Gregory, G. L.; Kondo, Yutaka; Knabb, Richard D.; Sachse, G. W.; Talbot, R. W.

1999-01-01

Chemical data from flight 8 of NASA's Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) exhibited signatures consistent with aircraft emissions, stratospheric air, and surface-based pollution. These signatures are examined in detail, focussing on the broad aircraft emission signatures that are several hundred kilometers in length. A mesoscale meteorological model provides high resolution wind data that are used to calculate backward trajectories arriving at locations along the flight track. These trajectories are compared to aircraft locations in the North Atlantic Flight Corridor over a 27-33 hour period. Time series of flight level NO and the number of trajectory/aircraft encounters within the NAFC show excellent agreement. Trajectories arriving within the stratospheric and surface-based pollution regions are found to experience very few aircraft encounters. Conversely, there are many trajectory/aircraft encounters within the two chemical signatures corresponding to aircraft emissions. Even many detailed fluctuations of NO within the two aircraft signature regions correspond to similar fluctuations in aircraft encountered during the previous 27-33 hours. Results indicate that high resolution meteorological modeling, when coupled with detailed aircraft location data, is useful for understanding chemical signatures from aircraft emissions at scales of several hundred kilometers.

Numerical simulation of the non-Newtonian mixing layer

NASA Technical Reports Server (NTRS)

Azaiez, Jalel; Homsy, G. M.

1993-01-01

This work is a continuing effort to advance our understanding of the effects of polymer additives on the structures of the mixing layer. In anticipation of full nonlinear simulations of the non-Newtonian mixing layer, we examined in a first stage the linear stability of the non-Newtonian mixing layer. The results of this study show that, for a fluid described by the Oldroyd-B model, viscoelasticity reduces the instability of the inviscid mixing layer in a special limit where the ratio (We/Re) is of order 1 where We is the Weissenberg number, a measure of the elasticity of the flow, and Re is the Reynolds number. In the present study, we pursue this project with numerical simulations of the non-Newtonian mixing layer. Our primary objective is to determine the effects of viscoelasticity on the roll-up structure. We also examine the origin of the numerical instabilities usually encountered in the simulations of non-Newtonian fluids.

Numerical modeling process of embolization arteriovenous malformation

NASA Astrophysics Data System (ADS)

Cherevko, A. A.; Gologush, T. S.; Petrenko, I. A.; Ostapenko, V. V.

2017-10-01

Cerebral arteriovenous malformation is a difficult, dangerous, and most frequently encountered vascular failure of development. It consists of vessels of very small diameter, which perform a discharge of blood from the artery to the vein. In this regard it can be adequately modeled using porous medium. Endovascular embolization of arteriovenous malformation is effective treatment of such pathologies. However, the danger of intraoperative rupture during embolization still exists. The purpose is to model this process and build an optimization algorithm for arteriovenous malformation embolization. To study the different embolization variants, the initial-boundary value problems, describing the process of embolization, were solved numerically by using a new modification of CABARET scheme. The essential moments of embolization process were modeled in our numerical experiments. This approach well reproduces the essential features of discontinuous two-phase flows, arising in the embolization problems. It can be used for further study on the process of embolization.

The Double Flybys of the Cassini Mission: Navigation Challenges and Lessons Learned

NASA Technical Reports Server (NTRS)

Wagner, Sean; Buffington, Brent

2014-01-01

Since 2004, the Cassini spacecraft has flown by Titan and other Saturn moons numerous times, successfully accomplishing its 100th targeted encounter of Titan in March 2014. The navigation of Cassini is challenging, even more so with "double flybys," two encounters separated by at most a few days. Because of this tight spacing, there is not enough time for a maneuver in between. Additionally, maneuvers prior to a double flyby only target one of the two encounters. This paper discusses the challenges faced by the Cassini Navigation Team with each double flyby, as well as lessons learned during operational support of each dual encounter. The strengths and weaknesses of the targeting strategies considered for each double flyby are also detailed, by comparing downstream ?V costs and changes to the non-targeted flyby conditions.

Numerical difficulties and computational procedures for thermo-hydro-mechanical coupled problems of saturated porous media

NASA Astrophysics Data System (ADS)

Simoni, L.; Secchi, S.; Schrefler, B. A.

2008-12-01

This paper analyses the numerical difficulties commonly encountered in solving fully coupled numerical models and proposes a numerical strategy apt to overcome them. The proposed procedure is based on space refinement and time adaptivity. The latter, which in mainly studied here, is based on the use of a finite element approach in the space domain and a Discontinuous Galerkin approximation within each time span. Error measures are defined for the jump of the solution at each time station. These constitute the parameters allowing for the time adaptivity. Some care is however, needed for a useful definition of the jump measures. Numerical tests are presented firstly to demonstrate the advantages and shortcomings of the method over the more traditional use of finite differences in time, then to assess the efficiency of the proposed procedure for adapting the time step. The proposed method reveals its efficiency and simplicity to adapt the time step in the solution of coupled field problems.

Very massive runaway stars from three-body encounters

NASA Astrophysics Data System (ADS)

Gvaramadze, Vasilii V.; Gualandris, Alessia

2011-01-01

Very massive stars preferentially reside in the cores of their parent clusters and form binary or multiple systems. We study the role of tight very massive binaries in the origin of the field population of very massive stars. We performed numerical simulations of dynamical encounters between single (massive) stars and a very massive binary with parameters similar to those of the most massive known Galactic binaries, WR 20a and NGC 3603-A1. We found that these three-body encounters could be responsible for the origin of high peculiar velocities (≥70 km s-1) observed for some very massive (≥60-70 M⊙) runaway stars in the Milky Way and the Large Magellanic Cloud (e.g. λ Cep, BD+43°3654, Sk -67°22, BI 237, 30 Dor 016), which can hardly be explained within the framework of the binary-supernova scenario. The production of high-velocity massive stars via three-body encounters is accompanied by the recoil of the binary in the opposite direction to the ejected star. We show that the relative position of the very massive binary R145 and the runaway early B-type star Sk-69°206 on the sky is consistent with the possibility that both objects were ejected from the central cluster, R136, of the star-forming region 30 Doradus via the same dynamical event - a three-body encounter.

High-velocity runaway stars from three-body encounters

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.; Gualandris, A.; Portegies Zwart, S.

2010-01-01

We performed numerical simulations of dynamical encounters between hard, massive binaries and a very massive star (VMS; formed through runaway mergers of ordinary stars in the dense core of a young massive star cluster) to explore the hypothesis that this dynamical process could be responsible for the origin of high-velocity (≥ 200 - 400 km s-1) early or late B-type stars. We estimated the typical velocities produced in encounters between very tight massive binaries and VMSs (of mass of ≥ 200 M⊙) and found that about 3 - 4% of all encounters produce velocities ≥ 400 km s-1, while in about 2% of encounters the escapers attain velocities exceeding the Milky Ways's escape velocity. We therefore argue that the origin of high-velocity (≥ 200 - 400 km s-1) runaway stars and at least some so-called hypervelocity stars could be associated with dynamical encounters between the tightest massive binaries and VMSs formed in the cores of star clusters. We also simulated dynamical encounters between tight massive binaries and single ordinary 50 - 100 M⊙ stars. We found that from 1 to ≃ 4% of these encounters can produce runaway stars with velocities of ≥ 300 - 400 km s-1 (typical of the bound population of high-velocity halo B-type stars) and occasionally (in less than 1% of encounters) produce hypervelocity (≥ 700 km s-1) late B-type escapers.

An analytical theory of planetary rotation rates

NASA Technical Reports Server (NTRS)

Harris, A. W.

1977-01-01

An approximate analytical theory is derived for the rate of rotation acquired by a planet as it grows from the solar nebula. This theory was motivated by a numerical study by Giuli, and yields fair agreement with his results. The periods of planetary rotation obtained are proportional to planetesimal encounter velocity, and appear to suggest lower values of this velocity than are commonly assumed to have existed during planetary formation.

Quiet High Speed Fan (QHSF) Flutter Calculations Using the TURBO Code

NASA Technical Reports Server (NTRS)

Bakhle, Milind A.; Srivastava, Rakesh; Keith, Theo G., Jr.; Min, James B.; Mehmed, Oral

2006-01-01

A scale model of the NASA/Honeywell Engines Quiet High Speed Fan (QHSF) encountered flutter wind tunnel testing. This report documents aeroelastic calculations done for the QHSF scale model using the blade vibration capability of the TURBO code. Calculations at design speed were used to quantify the effect of numerical parameters on the aerodynamic damping predictions. This numerical study allowed the selection of appropriate values of these parameters, and also allowed an assessment of the variability in the calculated aerodynamic damping. Calculations were also done at 90 percent of design speed. The predicted trends in aerodynamic damping corresponded to those observed during testing.

A numerical projection technique for large-scale eigenvalue problems

NASA Astrophysics Data System (ADS)

Gamillscheg, Ralf; Haase, Gundolf; von der Linden, Wolfgang

2011-10-01

We present a new numerical technique to solve large-scale eigenvalue problems. It is based on the projection technique, used in strongly correlated quantum many-body systems, where first an effective approximate model of smaller complexity is constructed by projecting out high energy degrees of freedom and in turn solving the resulting model by some standard eigenvalue solver. Here we introduce a generalization of this idea, where both steps are performed numerically and which in contrast to the standard projection technique converges in principle to the exact eigenvalues. This approach is not just applicable to eigenvalue problems encountered in many-body systems but also in other areas of research that result in large-scale eigenvalue problems for matrices which have, roughly speaking, mostly a pronounced dominant diagonal part. We will present detailed studies of the approach guided by two many-body models.

Progress in Development of an Airborne Turbulence Detection System

NASA Technical Reports Server (NTRS)

Hamilton, David W.; Proctor, Fred H.

2006-01-01

Aircraft encounters with turbulence are the leading cause of in-flight injuries (Tyrvanas 2003) and have occasionally resulted in passenger and crew fatalities. Most of these injuries are caused by sudden and unexpected encounters with severe turbulence in and around convective activity (Kaplan et al 2005). To alleviate this problem, the Turbulence Prediction and Warning Systems (TPAWS) element of NASA s Aviation Safety program has investigated technologies to detect and warn of hazardous in-flight turbulence. This effort has required the numerical modeling of atmospheric convection: 1) for characterizing convectively induced turbulence (CIT) environments, 2) for defining turbulence hazard metrics, and 3) as a means of providing realistic three-dimensional data sets that can be used to test and evaluate turbulence detection sensors. The data sets are being made available to industry and the FAA for certification of future airborne turbulence-detection systems (ATDS) with warning capability. Early in the TPAWS project, a radar-based ATDS was installed and flight tested on NASA s research aircraft, a B-757. This ATDS utilized new algorithms and hazard metrics that were developed for use with existing airborne predictive windshear radars, thus avoiding the installation of new hardware. This system was designed to detect and warn of hazardous CIT even in regions with weak radar reflectivity (i.e. 5-15 dBz). Results from an initial flight test of the ATDS were discussed in Hamilton and Proctor (2002a; 2002b). In companion papers (Proctor et al 2002a; 2002b), a numerical simulation of the most significant encounter from that flight test was presented. Since the presentation of these papers a second flight test has been conducted providing additional cases for examination. In this paper, we will present results from NASA s flight test and a numerical model simulation of a turbulence environment encountered on 30 April 2002. Progress leading towards FAA certification of industry built ATDS will also be discussed.

Experimental study of the fracture toughness of a ceramic/ceramic-matrix composite sandwich structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Z.; Taya, M.; Dunn, M.L.

A hybrid experimental-numerical approach has been used to measure the fracture resistance of a sandwich structure consisting of a 304 stainless steel/partially stabilized zirconia ceramic-matrix composite crack-arresting layer embedded in a partially stabilized zirconia ceramic specimen. The mode 1 fracture toughness increases significantly when the crack propagates from the ceramic into the ceramic-matrix composite region. The increased toughening due to the stainless steel particles is explained reasonably well by a toughening model based on processing-induced thermal residual stresses. In addition, several experimental modifications were made to the chevron-notch wedge-loaded double cantilever beam specimen to overcome numerous problems encountered in generatingmore » a precrack in the small, brittle specimens used in this study.« less

Efficiency of encounter-controlled reaction between diffusing reactants in a finite lattice: Non-nearest-neighbor effects

NASA Astrophysics Data System (ADS)

Bentz, Jonathan L.; Kozak, John J.; Nicolis, Gregoire

2005-08-01

The influence of non-nearest-neighbor displacements on the efficiency of diffusion-reaction processes involving one and two mobile diffusing reactants is studied. An exact analytic result is given for dimension d=1 from which, for large lattices, one can recover the asymptotic estimate reported 30 years ago by Lakatos-Lindenberg and Shuler. For dimensions d=2,3 we present numerically exact values for the mean time to reaction, as gauged by the mean walklength before reactive encounter, obtained via the theory of finite Markov processes and supported by Monte Carlo simulations. Qualitatively different results are found between processes occurring on d=1 versus d>1 lattices, and between results obtained assuming nearest-neighbor (only) versus non-nearest-neighbor displacements.

Vehicle Procurement Lessons Learned at Yosemite National Park.

DOT National Transportation Integrated Search

2005-02-28

In seeking to obtain replacement buses for its Valley Shuttle fleet, Yosemite National Park encountered numerous uncertainties in the procurement process that complicated what was intended to be a relatively straightforward purchase. The analysis tha...

Hydrodynamics and PIV study in the impingement zone formed by a droplet train

NASA Astrophysics Data System (ADS)

Kanjirakat, Anoop; Sadr, Reza; Zhang, Taolue; Muthusamy, Jayaveera; Alvarado, Jorge; Texas A; M University at Qatar Collaboration; Texas A; M University College Station Collaboration

2016-11-01

Droplet impingement is encountered in numerous technical applications, such as ink jet printing, spray cooling, and fuel injection in internal combustion engines. Even though many studies in droplet impingement were conducted in past, not many have measured the near-wall velocities in the droplet impingement zone. With the goal of gaining a better understanding of the hydrodynamics in the impingement zone, well-controlled experiments are performed in combination with micro-PIV measurements and numerical simulations. Hydrodynamics of HFE-7100 droplets generated using a piezoelectric droplet generator, impinging on a pre-wetted surface is investigated. Micro-PIV studies in the high-velocity impingement zone are performed using one-micron meter fluorescent particles dispersed in HFE-7100 along with the double exposed images. Three-dimensional and 2D-axisymmetric numerical modeling for a transient droplet crown development is performed. The interface between the gas and the liquid is modeled using a Volume of Fluid (VOF) method. Numerical simulation results obtained are observed to be in good agreement with that of the experimental observations. Supported by National Priority Research Program (NPRP) of Qatar National Research Fund (QNRF), Grant No.: NPRP 6-1304-2-525.

Large-Eddy Simulation of Waked Turbines in a Scaled Wind Farm Facility

NASA Astrophysics Data System (ADS)

Wang, J.; McLean, D.; Campagnolo, F.; Yu, T.; Bottasso, C. L.

2017-05-01

The aim of this paper is to present the numerical simulation of waked scaled wind turbines operating in a boundary layer wind tunnel. The simulation uses a LES-lifting-line numerical model. An immersed boundary method in conjunction with an adequate wall model is used to represent the effects of both the wind turbine nacelle and tower, which are shown to have a considerable effect on the wake behavior. Multi-airfoil data calibrated at different Reynolds numbers are used to account for the lift and drag characteristics at the low and varying Reynolds conditions encountered in the experiments. The present study focuses on low turbulence inflow conditions and inflow non-uniformity due to wind tunnel characteristics, while higher turbulence conditions are considered in a separate study. The numerical model is validated by using experimental data obtained during test campaigns conducted with the scaled wind farm facility. The simulation and experimental results are compared in terms of power capture, rotor thrust, downstream velocity profiles and turbulence intensity.

New techniques for experimental generation of two-dimensional blade-vortex interaction at low Reynolds numbers

NASA Technical Reports Server (NTRS)

Booth, E., Jr.; Yu, J. C.

1986-01-01

An experimental investigation of two dimensional blade vortex interaction was held at NASA Langley Research Center. The first phase was a flow visualization study to document the approach process of a two dimensional vortex as it encountered a loaded blade model. To accomplish the flow visualization study, a method for generating two dimensional vortex filaments was required. The numerical study used to define a new vortex generation process and the use of this process in the flow visualization study were documented. Additionally, photographic techniques and data analysis methods used in the flow visualization study are examined.

Event-related potentials, cognition, and behavior: a biological approach.

PubMed

Kotchoubey, Boris

2006-01-01

The prevailing cognitive-psychological accounts of event-related brain potentials (ERPs) assume that ERP components manifest information processing operations leading from stimulus to response. Since this view encounters numerous difficulties already analyzed in previous studies, an alternative view is presented here that regards cortical control of behavior as a repetitive sensorimotor cycle consisting of two phases: (i) feedforward anticipation and (ii) feedback cortical performance. This view allows us to interpret in an integrative manner numerous data obtained from very different domains of ERP studies: from biophysics of ERP waves to their relationship to the processing of language, in which verbal behavior is viewed as likewise controlled by the same two basic control processes: feedforward (hypothesis building) and feedback (hypothesis checking). The proposed approach is intentionally simplified, explaining numerous effects on the basis of few assumptions and relating several levels of analysis: neurophysiology, macroelectrical processes (i.e. ERPs), cognition and behavior. It can, therefore, be regarded as a first approximation to a general theory of ERPs.

Velocity field calculation for non-orthogonal numerical grids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flach, G. P.

2015-03-01

Computational grids containing cell faces that do not align with an orthogonal (e.g. Cartesian, cylindrical) coordinate system are routinely encountered in porous-medium numerical simulations. Such grids are referred to in this study as non-orthogonal grids because some cell faces are not orthogonal to a coordinate system plane (e.g. xy, yz or xz plane in Cartesian coordinates). Non-orthogonal grids are routinely encountered at the Savannah River Site in porous-medium flow simulations for Performance Assessments and groundwater flow modeling. Examples include grid lines that conform to the sloping roof of a waste tank or disposal unit in a 2D Performance Assessment simulation,more » and grid surfaces that conform to undulating stratigraphic surfaces in a 3D groundwater flow model. Particle tracking is routinely performed after a porous-medium numerical flow simulation to better understand the dynamics of the flow field and/or as an approximate indication of the trajectory and timing of advective solute transport. Particle tracks are computed by integrating the velocity field from cell to cell starting from designated seed (starting) positions. An accurate velocity field is required to attain accurate particle tracks. However, many numerical simulation codes report only the volumetric flowrate (e.g. PORFLOW) and/or flux (flowrate divided by area) crossing cell faces. For an orthogonal grid, the normal flux at a cell face is a component of the Darcy velocity vector in the coordinate system, and the pore velocity for particle tracking is attained by dividing by water content. For a non-orthogonal grid, the flux normal to a cell face that lies outside a coordinate plane is not a true component of velocity with respect to the coordinate system. Nonetheless, normal fluxes are often taken as Darcy velocity components, either naively or with accepted approximation. To enable accurate particle tracking or otherwise present an accurate depiction of the velocity field for a non-orthogonal grid, Darcy velocity components are rigorously derived in this study from normal fluxes to cell faces, which are assumed to be provided by or readily computed from porous-medium simulation code output. The normal fluxes are presumed to satisfy mass balances for every computational cell, and if so, the derived velocity fields are consistent with these mass balances. Derivations are provided for general two-dimensional quadrilateral and three-dimensional hexagonal systems, and for the commonly encountered special cases of perfectly vertical side faces in 2D and 3D and a rectangular footprint in 3D.« less

Improving design phase evaluations for high pile rebound sites : final report.

DOT National Transportation Integrated Search

2016-05-31

A testing program performed to help determine typical soils properties encountered during pile installation when high rebound : occurs produced a decision matrix for geotechnical engineers. High pile rebound (HPR) occurred at numerous sites in Florid...

Numerical modeling of an experimental shock tube for traumatic brain injury studies

NASA Astrophysics Data System (ADS)

Phillips, Michael; Regele, Jonathan D.

2015-11-01

Unfortunately, Improvised Explosive Devices (IEDs) are encountered commonly by both civilians and military soldiers throughout the world. Over a decade of medical history suggests that traumatic brain injury (TBI) may result from exposure to the blast waves created by these explosions, even if the person does not experience any immediate injury or lose consciousness. Medical researchers study the exposure of mice and rats to blast waves created in specially designed shock tubes to understand the effect on brain tissue. A newly developed table-top shock tube with a short driver section has been developed for mice experiments to reduce the time necessary to administer the blast radiation and increase the amount of statistical information available. In this study, numerical simulations of this shock tube are performed to assess how the blast wave takes its shape. The pressure profiles obtained from the numerical results are compared with the pressure histories from the experimental pressure transducers. The results show differences in behavior from what was expected, but the blast wave may still be an effective means of studying TBI.

On stellar encounters and their effect on cometary orbits in the Oort cloud

NASA Astrophysics Data System (ADS)

Serafin, R. A.; Grothues, H.-G.

2002-03-01

We systematically investigate the encounters between the Sun and neighbouring stars and their effects on cometary orbits in the Oort cloud, including the intrinsic one with the star Gl 710 (HIP 89 825), with some implications to stellar and cometary dynamics. Our approach is principally based on the combination of a Keplerian-rectilinear model of stellar passages and the Hipparcos Catalogue (ESA 1997). Beyond the parameters of encounter, we pay particular attention to the observational errors in parallaxes and stellar velocities, and their propagation in time. Moreover, as a special case of this problem, we consider the collision probability of a star passing very closely to the Sun, taking also into account the mutual gravitational attraction between the stars. In the part dealing with the influence of stellar encounters on the orbital elements of Oort cloud comets, we derive new simple formulae calculating the changes in the cometary orbital elements, expressed as functions of the Jeans impulse formula. These expressions are then applied to calculate numerical values of the element changes caused by close encounters of neighbouring stars with some model comets in the Oort cloud. Moreover, the general condition for an ejection of comets from the cloud effected by a single encounter is derived and discussed.

Hardware problems encountered in solar heating and cooling systems

NASA Technical Reports Server (NTRS)

Cash, M.

1978-01-01

Numerous problems in the design, production, installation, and operation of solar energy systems are discussed. Described are hardware problems, which range from simple to obscure and complex, and their resolution.

Three-dimensional numerical simulation of the 20 June 1991, Orlando microburst

NASA Technical Reports Server (NTRS)

Proctor, Fred H.

1992-01-01

On 20 June 1991, NASA's Boeing 737, equipped with in-situ and look-ahead wind-shear detection systems, made direct low-level penetrations (300-350 m AGL) through a microburst during several stages of its evolution. This microburst was located roughly 20 km northeast of Orlando International Airport and was monitored by a Terminal Doppler Weather Radar (TDWR) located about 10 km south of the airport. The first NASA encounter with this microburst (Event 142), at approximately 2041 UTC, was during its intensification phase. At flight level, in-situ measurements indicated a peak 1-km (averaged) F-factor of approximately 0.1. The second NASA encounter (Event 143) occurred at approximately 2046 UTC, about the time of microburst peak intensity. It was during this penetration that a peak 1-km F-factor of approximately 17 was encountered, which was the largest in-situ measurement of the 1991 summer deployment. By the third encounter (Event 144), at approximately 2051 UTC, the microburst had expanded into a macroburst. During this phase of evolution, an in-situ 1-km F-factor of 0.08 was measured. The focus of this paper is to examine this microburst via numerical simulation from an unsteady, three-dimensional meteorological cloud model. The simulated high-resolution data fields of wind, temperature, radar reflectivity factor, and precipitation are closely examined so as to derive information not readily available from 'observations' and to enhance our understanding of the actual event. Characteristics of the simulated microburst evolution are compared with TDWR and in-situ measurements.

Study on Collision of Ship Side Structure by Simplified Plastic Analysis Method

NASA Astrophysics Data System (ADS)

Sun, C. J.; Zhou, J. H.; Wu, W.

2017-10-01

During its lifetime, a ship may encounter collision or grounding and sustain permanent damage after these types of accidents. Crashworthiness has been based on two kinds of main methods: simplified plastic analysis and numerical simulation. A simplified plastic analysis method is presented in this paper. Numerical methods using the non-linear finite-element software LS-DYNA are conducted to validate the method. The results show that, as for the accuracy of calculation results, the simplified plasticity analysis are in good agreement with the finite element simulation, which reveals that the simplified plasticity analysis method can quickly and accurately estimate the crashworthiness of the side structure during the collision process and can be used as a reliable risk assessment method.

Understanding ethical dilemmas in the emergency department: views from medical students' essays.

PubMed

House, Joseph B; Theyyunni, Nikhil; Barnosky, Andrew R; Fuhrel-Forbis, Andrea; Seeyave, Desiree M; Ambs, Dawn; Fischer, Jonathan P; Santen, Sally A

2015-04-01

For medical students, the emergency department (ED) often presents ethical problems not encountered in other settings. In many medical schools there is little ethics training during the clinical years. The benefits of reflective essay writing in ethics and professionalism education are well established. The purpose of this study was to determine and categorize the types of ethical dilemmas and scenarios encountered by medical students in the ED through reflective essays. During a 4(th)-year emergency medicine rotation, all medical students wrote brief essays on an ethical situation encountered in the ED, and participated in an hour debriefing session about these essays. Qualitative analysis was performed to determine common themes from the essays. The frequency of themes was calculated. The research team coded 173 essays. The most common ethical themes were autonomy (41%), social justice (32.4%), nonmaleficence (31.8%), beneficence (26.6%), fidelity (12%), and respect (8.7%). Many of the essays contained multiple ethical principles that were often in conflict with each other. In one essay, a student grappled with the decision to intubate a patient despite a preexisting do-not-resuscitate order. This patient encounter was coded with autonomy, beneficence, and nonmaleficence. Common scenarios included ethical concerns when caring for critical patients, treatment of pain, homeless or alcoholic patients, access to care, resource utilization, and appropriateness of care. Medical students encounter patients with numerous ethically based issues. Frequently, they note conflicts between ethical principles. Such essays constitute an important resource for faculty, resident, and student ethics training. Copyright © 2015 Elsevier Inc. All rights reserved.

Improved transition path sampling methods for simulation of rare events

NASA Astrophysics Data System (ADS)

Chopra, Manan; Malshe, Rohit; Reddy, Allam S.; de Pablo, J. J.

2008-04-01

The free energy surfaces of a wide variety of systems encountered in physics, chemistry, and biology are characterized by the existence of deep minima separated by numerous barriers. One of the central aims of recent research in computational chemistry and physics has been to determine how transitions occur between deep local minima on rugged free energy landscapes, and transition path sampling (TPS) Monte-Carlo methods have emerged as an effective means for numerical investigation of such transitions. Many of the shortcomings of TPS-like approaches generally stem from their high computational demands. Two new algorithms are presented in this work that improve the efficiency of TPS simulations. The first algorithm uses biased shooting moves to render the sampling of reactive trajectories more efficient. The second algorithm is shown to substantially improve the accuracy of the transition state ensemble by introducing a subset of local transition path simulations in the transition state. The system considered in this work consists of a two-dimensional rough energy surface that is representative of numerous systems encountered in applications. When taken together, these algorithms provide gains in efficiency of over two orders of magnitude when compared to traditional TPS simulations.

Contributions to North American Ethnology, Volume II, Part II: The Klamath Indians of southwestern Oregon: dictionary of the Klamath language

USGS Publications Warehouse

Gatschet, Albert Samuel; Powell, John Wesley

1890-01-01

The present Dictionary, divided in two parts, contains the lexical portion of an Oregonian language never before reduced to writing. In view of the numerous obstacles and difficulties encountered in the preparation of such a work, a few hints upon its origin and tendencies will be of service in directing the studies of those who wish to acquire a more intimate knowledge of this energetic and well developed western language.

Separating stages of arithmetic verification: An ERP study with a novel paradigm.

PubMed

Avancini, Chiara; Soltész, Fruzsina; Szűcs, Dénes

2015-08-01

In studies of arithmetic verification, participants typically encounter two operands and they carry out an operation on these (e.g. adding them). Operands are followed by a proposed answer and participants decide whether this answer is correct or incorrect. However, interpretation of results is difficult because multiple parallel, temporally overlapping numerical and non-numerical processes of the human brain may contribute to task execution. In order to overcome this problem here we used a novel paradigm specifically designed to tease apart the overlapping cognitive processes active during arithmetic verification. Specifically, we aimed to separate effects related to detection of arithmetic correctness, detection of the violation of strategic expectations, detection of physical stimulus properties mismatch and numerical magnitude comparison (numerical distance effects). Arithmetic correctness, physical stimulus properties and magnitude information were not task-relevant properties of the stimuli. We distinguished between a series of temporally highly overlapping cognitive processes which in turn elicited overlapping ERP effects with distinct scalp topographies. We suggest that arithmetic verification relies on two major temporal phases which include parallel running processes. Our paradigm offers a new method for investigating specific arithmetic verification processes in detail. Copyright © 2015 Elsevier Ltd. All rights reserved.

Few-body modes of binary formation in core collapse

NASA Astrophysics Data System (ADS)

Tanikawa, Ataru; Heggie, Douglas C.; Hut, Piet; Makino, Junichiro

2013-11-01

At the moment of deepest core collapse, a star cluster core contains less than ten stars. This small number makes the traditional treatment of hard binary formation, assuming a homogeneous background density, suspect. In a previous paper, we have found that indeed the conventional wisdom of binary formation, based on three-body encounters, is incorrect. Here we refine that insight, by further dissecting the subsequent steps leading to hard binary formation. For this purpose, we add some analysis tools in order to make the study less subjective. We find that the conventional treatment does remain valid for direct three-body scattering, but fails for resonant three-body scattering. Especially democratic resonance scattering, which forms an important part of the analytical theory of three-body binary formation, takes too much space and time to be approximated as being isolated, in the context of a cluster core around core collapse. We conclude that, while three-body encounters can be analytically approximated as isolated, subsequent strong perturbations typically occur whenever those encounters give rise to democratic resonances. We present analytical estimates postdicting our numerical results. If we only had been a bit more clever, we could have predicted this qualitative behaviour.

A new technique for solving the Parker-type wind equations

NASA Technical Reports Server (NTRS)

Melia, Fulvio

1988-01-01

Substitution of the novel function Phi for velocity, as one of the dependent variables in Parker-type solar wind equations, removes the critical point, and therefore the numerical difficulties encountered, from the set of coupled differential wind equations. The method has already been successfully used in a study of radiatively-driven mass loss from the surface of X-ray bursting neutron stars. The present technique for solving the equations of time-independent mass loss can be useful in similar applications.

A scaling law for accretion zone sizes

NASA Technical Reports Server (NTRS)

Greenzweig, Yuval; Lissauer, Jack J.

1987-01-01

Current theories of runaway planetary accretion require small random velocities of the accreted particles. Two body gravitational accretion cross sections which ignore tidal perturbations of the Sun are not valid for the slow encounters which occur at low relative velocities. Wetherill and Cox have studied accretion cross sections for rocky protoplanets orbiting at 1 AU. Using analytic methods based on Hill's lunar theory, one can scale these results for protoplanets that occupy the same fraction of their Hill sphere as does a rocky body at 1 AU. Generalization to bodies of different sizes is achieved here by numerical integrations of the three-body problem. Starting at initial positions far from the accreting body, test particles are allowed to encounter the body once, and the cross section is computed. A power law is found relating the cross section to the radius of the accreting body (of fixed mass).

The quest for extraterrestrial life: what about the viruses?

USGS Publications Warehouse

Griffin, Dale Warren

2013-01-01

Recently, viruses have been recognized as the most numerous entities and the primary drivers of evolution on Earth. Historically, viruses have been mostly ignored in the field of astrobiology due to the view that they are not alive in the classical sense and if encountered would not present risk due to their host-specific nature. What we currently know of viruses is that we are most likely to encounter them on other life-bearing planets; that while some are exquisitely host-specific, many viruses can utilize hundreds of different host species; that viruses are known to exist in our planet's most extreme environments; and that while many do not survive long outside their hosts, some can survive for extended periods, especially in the cold. In our quest for extraterrestrial life, we should be looking for viruses; and while any encountered may pose no risk, the possibility of an encounter with a virus capable of accessing multiple cell types exists, and any prospective contact with such an organism should be treated accordingly.

The quest for extraterrestrial life: what about the viruses?

PubMed

Griffin, Dale Warren

2013-08-01

Recently, viruses have been recognized as the most numerous entities and the primary drivers of evolution on Earth. Historically, viruses have been mostly ignored in the field of astrobiology due to the view that they are not alive in the classical sense and if encountered would not present risk due to their host-specific nature. What we currently know of viruses is that we are most likely to encounter them on other life-bearing planets; that while some are exquisitely host-specific, many viruses can utilize hundreds of different host species; that viruses are known to exist in our planet's most extreme environments; and that while many do not survive long outside their hosts, some can survive for extended periods, especially in the cold. In our quest for extraterrestrial life, we should be looking for viruses; and while any encountered may pose no risk, the possibility of an encounter with a virus capable of accessing multiple cell types exists, and any prospective contact with such an organism should be treated accordingly.

Chariklo vs Chiron: the stability of the rings due to planetary close encounters

NASA Astrophysics Data System (ADS)

Sfair, Rafael; Araujo, Rosana; Cabo Winter, Othon

2017-10-01

The surprising discovery of a two well defined rings around the Centaur Chariklo was the first finding of such structures around a small body (Braga Ribas et al., 2014). Since it is known that the centaurs have a short lifetime (up to ten million years) and they experience a large number of encounters with the giant planets, one raises the question whether the rings would survive along the orbital evolution of Chariklo. In a previous work we analyzed through numerical simulations the effects of the close encounters with the giant planets experienced by an ensemble of 729 Chariklo-like objects (Araujo, Sfair & Winter, 2016). Even when considering the most extreme encounters, the most likely result (>90%) is the survival of the ring system without any significant orbital change. Here we intend to broaden our analysis to 2060 Chiron, another Centaur with a presumed ring system (Ortiz et al., 2015). Applying the same method of Araujo, Sfair & Winter (2016), initially we recorded the encounters with the giant planets performed by the clones of Chiron. We first notice Chiron's lifetime is shorter, and the number of encounters it experienced is significantly larger than by Chariklo. As a consequence, the rings of Chiron would be more susceptible to be disrupted by the close approaches with the giant planets. We attribute this dichotomy to the difference of orbital and physical parameters of the two centaurs.

Numerical Investigation of Force-Free Magnetophoresis of Nonspherical Microparticles

NASA Astrophysics Data System (ADS)

Zhang, Jie; Wang, Cheng

2017-11-01

Our group recently demonstrated novel force-free magnetophoresis to separate nonspherical particles by shape. In this approach, a uniform magnetic field is used to generate a magnetic torque, which breaks the rotational symmetry of the particles and leads to shape-dependent lateral migration of the particles. We use direct numerical simulations to gain a better understanding of this magnetophoresis mechanism by focusing on ellipsoidal microparticles - a representative type of nonspherical particles encountered in biomedical engineering. We study key effects that influence the rotational and translational behaviors, including particle-wall separation distance, direction and strength of the magnetic field, particle aspect ratio and size. The numerical results show that the lateral migration is negligible in the absence of the magnetic field. When the magnetic field is applied, the particles migrate laterally. The migration direction depends on the direction of external magnetic fields, which controls the symmetry property of the particle rotation. These findings agree well with experiments. Our numerical simulations yield a comprehensive understanding of particle migration mechanism, and provide useful guidelines on design of separating devices for non-spherical micro-particles.

Developing a Simulated-Person Methodology Workshop: An Experiential Education Initiative for Educators and Simulators

ERIC Educational Resources Information Center

Peisachovich, Eva Hava; Nelles, L. J.; Johnson, Samantha; Nicholson, Laura; Gal, Raya; Kerr, Barbara; Celia, Popovic; Epstein, Iris; Da Silva, Celina

2017-01-01

Numerous forecasts suggest that professional-competence development depends on human encounters. Interaction between organizations, tasks, and individual providers influence human behaviour, affect organizations' or systems' performance, and are a key component of professional-competence development. Further, insufficient or ineffective…

Numerical studies of incompressible flow around delta and double-delta wings

NASA Technical Reports Server (NTRS)

Krause, E.; Liu, C. H.

1989-01-01

The subject has been jointly investigated at NASA Langley Research Center and the Aerodynamisches Institut of the RWTH Aachen over a substantial period. The aim of this investigation has been to develop numerical integration procedures for the Navier-Stokes equations - particularly for incompressible three-dimensional viscous flows about simple and double delta wings - and to study the low speed flow behavior, with its complex vortex structures on the leeward side of the wing. The low speed flight regime poses unusual problems because high incidence flight conditions may, for example, encounter symmetric and asymmetric vortex breakdown. Because of the many difficulties to be expected in solving the problem, it was divided into two - analysis of the flow without vortex breakdown and analysis of the breakdown of isolated vortices. The major results obtained so far on the two topics are briefly described.

Shock-Induced Heating In A Rocket Engine

NASA Technical Reports Server (NTRS)

Lagnado, Ronald R.; Raiszadeh, Farhad

1989-01-01

Misalignments give rise to hotspots on walls. Report discusses numerical simulation of flow in and near small, ringlike cavity in wall of Space Shuttle main engine at junction of main combustion chamber and nozzle. Purpose to study effects of misalignments between combustion chamber and nozzle on transfer of heat into surfaces chamber, cavity, and nozzle. Depending on specific misalignment flow encounters forward-or backward-facing step leaving chamber and entering nozzle. Results in serious losses of performance and excessive heating of walls.

Calculation of double-lunar swingby trajectories: Part 2: Numerical solutions in the restricted problem of three bodies

NASA Technical Reports Server (NTRS)

Stalos, S.

1990-01-01

The double-lunar swingby trajectory is a method for maintaining alignment of an Earth satellite's line of apsides with the Sun-Earth line. From a Keplerian point of view, successive close encounters with the Moon cause discrete, instantaneous changes in the satellite's eccentricity and semimajor axis. Numerical solutions to the planar, restricted problem of three bodies as double-lunar swingby trajectories are identified. The method of solution is described and the results compared to the Keplerian formulation.

Turbulent Bubbly Flow in a Vertical Pipe Computed By an Eddy-Resolving Reynolds Stress Model

DTIC Science & Technology

2014-09-19

the numerical code OpenFOAM R©. 1 Introduction Turbulent bubbly flows are encountered in many industrially relevant applications, such as chemical in...performed using the OpenFOAM -2.2.2 computational code utilizing a cell- center-based finite volume method on an unstructured numerical grid. The...the mean Courant number is always below 0.4. The utilized turbulence models were implemented into the so-called twoPhaseEulerFoam solver in OpenFOAM , to

Advances in Numerical Boundary Conditions for Computational Aeroacoustics

NASA Technical Reports Server (NTRS)

Tam, Christopher K. W.

1997-01-01

Advances in Computational Aeroacoustics (CAA) depend critically on the availability of accurate, nondispersive, least dissipative computation algorithm as well as high quality numerical boundary treatments. This paper focuses on the recent developments of numerical boundary conditions. In a typical CAA problem, one often encounters two types of boundaries. Because a finite computation domain is used, there are external boundaries. On the external boundaries, boundary conditions simulating the solution outside the computation domain are to be imposed. Inside the computation domain, there may be internal boundaries. On these internal boundaries, boundary conditions simulating the presence of an object or surface with specific acoustic characteristics are to be applied. Numerical boundary conditions, both external or internal, developed for simple model problems are reviewed and examined. Numerical boundary conditions for real aeroacoustic problems are also discussed through specific examples. The paper concludes with a description of some much needed research in numerical boundary conditions for CAA.

Fundamental mechanisms in premixed flame propagation via vortex-flame interactions: Numerical simulations

NASA Technical Reports Server (NTRS)

Mantel, Thierry

1994-01-01

The goal of the present study is to assess numerically the ability of single-step and two-step chemical models to describe the main features encountered during the interaction between a two-dimensional vortex pair and a premixed laminar flame. In the two-step mechanism, the reaction kinetics are represented by a first chain branching reaction A + X yields 2X and a second chain termination reaction X + X yields P. This paper presents the fundamental mechanisms occurring during vortex-flame interactions and the relative impact of the major parameters encountered in turbulent premixed flames and suspected of playing a role in quenching mechanism: (1) Influence of stretch is investigated by analyzing the contribution of curvature and tangential strain on the local structure of the flame. The effect of Lewis number on the flame response to a strained field is analyzed. (2) Radiative heat losses which are suspected to be partially or totally responsible for quenching are also investigated. (3) The effect of the diffusion of the radicals is studied using a two-step mechanism in which an intermediate species is present. The parameters of the two-step mechanism are entirely determined from physical arguments. (4) Precise quantitative comparisons between the DNS and the experimental results of Samaniego et al are performed. These comparisons concern the evolution of the minimum heat release rate found along the flame front during the interaction and the distribution of the heat release rate along the flame front.

Wind turbine blades: A study of prototypes in a steady regime - Unsteady considerations

NASA Astrophysics Data System (ADS)

Leblanc, R.; Goethals, R.; de Saint Louvent, B.

1981-11-01

The results of comparisons of numerical models with experimental results for the performance of prototype wind turbines in steady flows are presented, along with preliminary results on behavior in unsteady flows. The numerical models are based on previous schemes devised for propellers, with modifications for small perturbations, significant radial velocity effects from the wake, and the fact that the speed is induced. Two computational methods are currently used, one a method of short blades, the other the Prandtl lifting line theory. Trials have been run in the T4 wind tunnel using a 3 m horizontal axis machine and a 2.5 m Darrieus. Attention is given to modeling the structural dynamics and turbulent flow structures encountered by wind turbines. Experimental results relating windspeed, angle of attack, and output are presented. Optimization studies have indicated that wind farms will require a 6-7 blade diameter unit spacing to maintain satisfactory group output efficiencies.

Simulations of the Fomalhaut system within its local galactic environment

NASA Astrophysics Data System (ADS)

Kaib, Nathan A.; White, Ethan B.; Izidoro, André

2018-01-01

Fomalhaut A is among the most well-studied nearby stars and has been discovered to possess a putative planetary object as well as a remarkable eccentric dust belt. This eccentric dust belt has often been interpreted as the dynamical signature of one or more planets that elude direct detection. However, the system also contains two other stellar companions residing ∼105 au from Fomalhaut A. We have designed a new symplectic integration algorithm to model the evolution of Fomalhaut A's planetary dust belt in concert with the dynamical evolution of its stellar companions to determine if these companions are likely to have generated the dust belt's morphology. Using our numerical simulations, we find that close encounters between Fomalhaut A and B are expected, with an ∼25 per cent probability that the two stars have passed within at least 400 au of each other at some point. Although the outcomes of such encounter histories are extremely varied, these close encounters nearly always excite the eccentricity of Fomalhaut A's dust belt and occasionally yield morphologies very similar to the observed belt. With these results, we argue that close encounters with Fomalhaut A's stellar companions should be considered a plausible mechanism to explain its eccentric belt, especially in the absence of detected planets capable of sculpting the belt's morphology. More broadly, we can also conclude from this work that very wide binary stars may often generate asymmetries in the stellar debris discs they host.

Natural fiber production, harvesting, and preliminary processing: options and opportunities

USDA-ARS?s Scientific Manuscript database

The utilization of natural fibers and plant oils in bio-products introduces numerous logistical challenges not typically encountered with non-agricultural resources. Once it has been determined that a plant material is suitable for commercial development, the production, harvesting, and processing s...

CURVILINEAR FINITE ELEMENT MODEL FOR SIMULATING TWO-WELL TRACER TESTS AND TRANSPORT IN STRATIFIED AQUIFERS

EPA Science Inventory

The problem of solute transport in steady nonuniform flow created by a recharging and discharging well pair is investigated. Numerical difficulties encountered with the standard Galerkin formulations in Cartesian coordinates are illustrated. An improved finite element solution st...

Mesoscale numerical investigations of air traffic emissions over the North Atlantic during SONEX flight 8: A case study

NASA Astrophysics Data System (ADS)

Bieberbach, George; Fuelberg, Henry E.; Thompson, Anne M.; Schmitt, Alfons; Hannan, John R.; Gregory, G. L.; Kondo, Yutaka; Knabb, Richard D.; Sachse, G. W.; Talbot, R. W.

2000-02-01

Chemical data from flight 8 of NASA's Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) exhibited signatures consistent with aircraft emissions, stratospheric air, and surface-based pollution. These signatures are examined in detail, focusing on the broad aircraft emission signatures that are several hundred kilometers in length. A mesoscale meteorological model provides high-resolution wind data that are used to calculate backward trajectories arriving at locations along the flight track. These trajectories are compared to aircraft locations in the North Atlantic Flight Corridor (NAFC) over a 27-33 hour period. Time series of flight level NO and the number of trajectory/aircraft encounters within the NAFC show excellent agreement. Trajectories arriving within the stratospheric and surface-based pollution regions are found to experience very few aircraft encounters. Conversely, there are many trajectory/aircraft encounters within the two chemical signatures corresponding to aircraft emissions. Even many detailed fluctuations of NO within the two aircraft signature regions correspond to similar fluctuations in aircraft encountered. These NO spikes are due to the superposition of 14 to 25 aircraft plumes transported to the DC-8 flight track during the previous 33 hours. Results confirm that aircraft emissions were responsible for two chemical signatures observed during SONEX flight 8. They also indicate that high-resolution meteorological modeling, when coupled with detailed aircraft location data, is useful for understanding chemical signatures from aircraft emissions at scales of several hundred kilometers.

View of Apollo 16 lunar sample no. 68815

NASA Image and Video Library

1972-04-30

A closeup view or "mug shot" of Apollo 16 lunar sample no. 68815, a dislodged fragment from a parent boulder roughly four feet high and five feet long encountered at Station 8. The crew tried in vain to overturn the parent boulder. A fillet-soil sample was taken close to the boulder, allowing for study of the type and rate of erosion acting on lunar rocks. The fragment itself is very hard, has many veticles and a variety of inclusions. In addition, numerous metallic particles were observed in the black matrix.

Resolving Conflict Creatively in the Multicultural Community: Inter-Cultural Mediation. [Videotape.

ERIC Educational Resources Information Center

Moyer, Kathleen Cleland

Students encounter numerous volatile situations throughout their school days, especially during times of increasing diversity. "Inter-Cultural Mediation" is a single half hour video that includes a teacher's manual and student handouts. Shot in Ontario, Canada during the Commonwealth Youth Conference in Conflict Resolution, this program…

78 FR 59958 - Notice of Inventory Completion: The Michigan State University Museum, East Lansing, MI

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-30

.... During subsequent cutwork, the property owner encountered bone, and removed a human cranium from the site... additional individuals, included a cranial piece, four ribs, five long bone fragments, four tarsal fragments, and numerous other unidentifiable bone fragments. No known individuals were identified. No associated...

Reliable numerical computation in an optimal output-feedback design

NASA Technical Reports Server (NTRS)

Vansteenwyk, Brett; Ly, Uy-Loi

1991-01-01

A reliable algorithm is presented for the evaluation of a quadratic performance index and its gradients with respect to the controller design parameters. The algorithm is a part of a design algorithm for optimal linear dynamic output-feedback controller that minimizes a finite-time quadratic performance index. The numerical scheme is particularly robust when it is applied to the control-law synthesis for systems with densely packed modes and where there is a high likelihood of encountering degeneracies in the closed-loop eigensystem. This approach through the use of an accurate Pade series approximation does not require the closed-loop system matrix to be diagonalizable. The algorithm was included in a control design package for optimal robust low-order controllers. Usefulness of the proposed numerical algorithm was demonstrated using numerous practical design cases where degeneracies occur frequently in the closed-loop system under an arbitrary controller design initialization and during the numerical search.

The pediatric heart network: meeting the challenges to multicenter studies in pediatric heart disease

PubMed Central

Burns, Kristin M.; Pemberton, Victoria L.; Pearson, Gail D.

2017-01-01

Purpose of review Because of the relatively small numbers of pediatric patients with congenital heart disease cared for in any individual center, there is a significant need for multicenter clinical studies to validate new medical or surgical therapies. The Pediatric Heart Network (PHN), with 15 years of experience in multicenter clinical research, has tackled numerous challenges when conducting multicenter studies. Recent findings This review describes the challenges encountered and the strategies employed to conduct high-quality, collaborative research in pediatric cardiovascular disease. Summary Sharing lessons learned from the PHN can provide guidance to investigators interested in conducting pediatric multicenter studies. PMID:26196261

The Behavior of Regular Satellites During the Planetary Migration

NASA Astrophysics Data System (ADS)

Nogueira, Erica Cristina; Gomes, R. S.; Brasser, R.

2013-05-01

Abstract (2,250 Maximum Characters): The behavior of the regular satellites of the giant planets during the instability phase of the Nice model needs to be better understood. In order to explain this behavior, we used numerical simulations to investigate the evolution of the regular satellite systems of the ice giants when these two planets experienced encounters with the gas giants. For the initial conditions we placed an ice planet in between Jupiter and Saturn, according to the evolution of Nice model simulations in a ‘jumping Jupiter’ scenario (Brasser et al. 2009). We used the MERCURY integrator (Chambers 1999) and cloned simulations by slightly modifying the Hybrid integrator changeover parameter. We obtained 101 successful runs which kept all planets, of which 24 were jumping Jupiter cases. Subsequently we performed additional numerical integrations in which the ice giant that encountered a gas giant was started on the same orbit but with its regular satellites included. This is done as follows: For each of the 101 basic runs, we save the orbital elements of all objects in the integration at all close encounter events. Then we performed a backward integration to start the system 100 years before the encounter and re-enacted the forward integration with the regular satellites around the ice giant. These integrations ran for 1000 years. The final orbital elements of the satellites with respect to the ice planet were used to restart the integration for the next planetary encounter (if any). If we assume that Uranus is the ice planet that had encounters with a gas giant, we considered the satellites Miranda, Ariel, Umbriel, Titania and Oberon with their present orbits around the planet. For Neptune we introduced Triton with an orbit with a 15% larger than the actual semi-major axis to account for the tidal decay from the LHB to present time. We also assume that Triton was captured through binary disruption (Agnor and Hamilton 2006, Nogueira et al. 2011) and its orbit was circularized by tides during the ~500 million years before the LHB. References: Agnor & Hamilton 2006, Nature 441, 192 Brasser et al. 2009, A&A 507, 1053 Chambers 1999, Mon. Not. R. Astron. Soc. 304, 793 Nogueira et al. 2011, Icarus 214, 113

Investigating Mixed-Ability Teaching in Taiwanese Primary Schools

ERIC Educational Resources Information Center

Huang, Ling-Ying

2014-01-01

In 2001, Taiwan reformed English language teaching in primary schools, and a mixed ability approach was taken as an organisational method for this. Many teachers claim that they encounter numerous difficulties in catering for different needs because of the large number of differences between students. However, the debate and comparisons between…

Thinking Visually about Algebra

ERIC Educational Resources Information Center

Baroudi, Ziad

2015-01-01

Many introductions to algebra in high school begin with teaching students to generalise linear numerical patterns. This article argues that this approach needs to be changed so that students encounter variables in the context of modelling visual patterns so that the variables have a meaning. The article presents sample classroom activities,…

Pest persistence and eradication conditions in a deterministic model for sterile insect release.

PubMed

Gordillo, Luis F

2015-01-01

The release of sterile insects is an environment friendly pest control method used in integrated pest management programmes. Difference or differential equations based on Knipling's model often provide satisfactory qualitative descriptions of pest populations subject to sterile release at relatively high densities with large mating encounter rates, but fail otherwise. In this paper, I derive and explore numerically deterministic population models that include sterile release together with scarce mating encounters in the particular case of species with long lifespan and multiple matings. The differential equations account separately the effects of mating failure due to sterile male release and the frequency of mating encounters. When insects spatial spread is incorporated through diffusion terms, computations reveal the possibility of steady pest persistence in finite size patches. In the presence of density dependence regulation, it is observed that sterile release might contribute to induce sudden suppression of the pest population.

Engaging Musical Practices: A Sourcebook for Middle School General Music

ERIC Educational Resources Information Center

Burton, Suzanne L., Ed.

2012-01-01

Middle school general music may be a student's last encounter with school music. A practical book with accessible pedagogical resources on middle school general music is needed for methods courses and music practitioners' use. The book "Engaging Musical Practices: A Sourcebook for Middle School General Music" presents numerous ways to engage…

Loss of a companion animal: understanding and helping the bereaved.

PubMed

Durkin, Anne

2009-07-01

Pet owners may face numerous animal losses in a lifetime. Grief following pet loss is often misunderstood and devalued. Nurses are likely to encounter patients and families mourning the loss of a companion animal. This article outlines the grief process and offers practical suggestions for assisting those who are bereaved.

Shark Interactions With Directed and Incidental Fisheries in the Northeast Pacific Ocean: Historic and Current Encounters, and Challenges for Shark Conservation.

PubMed

King, Jackie; McFarlane, Gordon A; Gertseva, Vladlena; Gasper, Jason; Matson, Sean; Tribuzio, Cindy A

For over 100 years, sharks have been encountered, as either directed catch or incidental catch, in commercial fisheries throughout the Northeast Pacific Ocean. A long-standing directed fishery for North Pacific Spiny Dogfish (Squalus suckleyi) has occurred and dominated shark landings and discards. Other fisheries, mainly for shark livers, have historically targeted species including Bluntnose Sixgill Shark (Hexanchus griseus) and Tope Shark (Galeorhinus galeus). While incidental catches of numerous species have occurred historically, only recently have these encounters been reliably enumerated in commercial and recreational fisheries. In this chapter we present shark catch statistics (directed and incidental) for commercial and recreational fisheries from Canadian waters (off British Columbia), southern US waters (off California, Oregon, and Washington), and northern US waters (off Alaska). In total, 17 species of sharks have collectively been encountered in these waters. Fishery encounters present conservation challenges for shark management, namely, the need for accurate catch statistics, stock delineation, life history parameter estimates, and improved assessments methods for population status and trends. Improvements in management and conservation of shark populations will only come with the further development of sound science-based fishery management practices for both targeted and incidental shark fisheries. © 2017 Elsevier Ltd All rights reserved.

Statistics and Data Interpretation for Social Work

ERIC Educational Resources Information Center

Rosenthal, James A.

2011-01-01

Written by a social worker for social work students, this is a nuts and bolts guide to statistics that presents complex calculations and concepts in clear, easy-to-understand language. It includes numerous examples, data sets, and issues that students will encounter in social work practice. The first section introduces basic concepts and terms to…

Merging Black Holes

NASA Technical Reports Server (NTRS)

Centrella, Joan; Baker, John G.; Kelly, Bernard J.; vanMeter, James R.

2010-01-01

Black-hole mergers take place in regions of very strong and dynamical gravitational fields, and are among the strongest sources of gravitational radiation. Probing these mergers requires solving the full set of Einstein's equations of general relativity numerically. For more than 40 years, progress towards this goal has been very slow, as numerical relativists encountered a host of difficult problems. Recently, several breakthroughs have led to dramatic progress, enabling stable and accurate calculations of black-hole mergers. This article presents an overview of this field, including impacts on astrophysics and applications in gravitational wave data analysis.

Modelling the transient behaviour of pulsed current tungsten-inert-gas weldpools

NASA Astrophysics Data System (ADS)

Wu, C. S.; Zheng, W.; Wu, L.

1999-01-01

A three-dimensional model is established to simulate the pulsed current tungsten-inert-gas (TIG) welding process. The goal is to analyse the cyclic variation of fluid flow and heat transfer in weldpools under periodic arc heat input. To this end, an algorithm, which is capable of handling the transience, nonlinearity, multiphase and strong coupling encountered in this work, is developed. The numerical simulations demonstrate the transient behaviour of weldpools under pulsed current. Experimental data are compared with numerical results to show the effectiveness of the developed model.

Patients' Expectations as to Doctors' Behaviors During Appointed Visits.

PubMed

Sobczak, Krzysztof; Leoniuk, Katarzyna; Janaszczyk, Agata; Pietrzykowska, Małgorzata

2017-04-01

Numerous guidelines for students and medical professionals provide the instructions of proper behavior during encounters with patients in a doctor's office. However, they quite often do not consider cultural differences that may affect the doctor-patient relationship. In our study we analyzed Polish patients' expectations (N = 976) for their physicians' actual behavior. We compared our results with analogue studies performed in the United States. We determined that patient expectations concerning a desirable form of verbal and nonverbal communication with a physician vary to a considerable degree. Relatively universal, however, is the wish that the doctors introduce themselves and apply personalized forms of contact.

The special growth history of central galaxies in groups and clusters

NASA Astrophysics Data System (ADS)

Nipoti, Carlo

2017-05-01

Central galaxies (CGs) in galaxy groups and clusters are believed to form and assemble a good portion of their stellar mass at early times, but they also accrete significant mass at late times via galactic cannibalism, that is merging with companion group or cluster galaxies that experience dynamical friction against the common host dark-matter halo. The effect of these mergers on the structure and kinematics of the CG depends not only on the properties of the accreted satellites, but also on the orbital parameters of the encounters. Here we present the results of numerical simulations aimed at estimating the distribution of merging orbital parameters of satellites cannibalized by the CGs in groups and clusters. As a consequence of dynamical friction, the satellites' orbits evolve losing energy and angular momentum, with no clear trend towards orbit circularization. The distributions of the orbital parameters of the central-satellite encounters are markedly different from the distributions found for halo-halo mergers in cosmological simulations. The orbits of satellites accreted by the CGs are on average less bound and less eccentric than those of cosmological halo-halo encounters. We provide fits to the distributions of the central-satellite merging orbital parameters that can be used to study the merger-driven evolution of the scaling relations of CGs.

Fugitives from the Hungaria region: Close encounters and impacts with terrestrial planets

NASA Astrophysics Data System (ADS)

Galiazzo, M. A.; Bazsó, Á.; Dvorak, R.

2013-08-01

Hungaria asteroids, whose orbits occupy the region in element space between 1.78

Secular dynamics of hierarchical multiple systems composed of nested binaries, with an arbitrary number of bodies and arbitrary hierarchical structure - II. External perturbations: flybys and supernovae

NASA Astrophysics Data System (ADS)

Hamers, Adrian S.

2018-05-01

We extend the formalism of a previous paper to include the effects of flybys and instantaneous perturbations such as supernovae on the long-term secular evolution of hierarchical multiple systems with an arbitrary number of bodies and hierarchy, provided that the system is composed of nested binary orbits. To model secular encounters, we expand the Hamiltonian in terms of the ratio of the separation of the perturber with respect to the barycentre of the multiple system, to the separation of the widest orbit. Subsequently, we integrate over the perturber orbit numerically or analytically. We verify our method for secular encounters and illustrate it with an example. Furthermore, we describe a method to compute instantaneous orbital changes to multiple systems, such as asymmetric supernovae and impulsive encounters. The secular code, with implementation of the extensions described in this paper, is publicly available within AMUSE, and we provide a number of simple example scripts to illustrate its usage for secular and impulsive encounters and asymmetric supernovae. The extensions presented in this paper are a next step towards efficiently modelling the evolution of complex multiple systems embedded in star clusters.

Orbital Modification of the Himalia Family during an Early Solar System Dynamical Instability

NASA Astrophysics Data System (ADS)

Li, Daohai; Christou, Apostolos A.

2017-11-01

Among the irregular satellites orbiting Jupiter, the Himalia family is characterized by a high velocity dispersion δ v of several hundred {{m}} {{{s}}}-1 among its members, inconsistent with a collisional origin. Efforts to account for this through internecine gravitational interactions do not readily reproduce this feature. Here, we revisit the problem in the context of recent cosmogonical models, where the giant planets migrated significantly through interaction with a planetesimal disk and suffered encounters with planetesimals and planet-sized objects. Our starting assumption is that family formation either predated this phase or occurred soon after its onset. We simulate numerically the diffusive effect of three distinct populations of perturbers on a set of test particles representing the family: Moon-sized (MPT) and Pluto-sized (PPT) planetesimals, and planetary-mass objects (PMO) with masses typical of ice-giant planets. We find that PPT flybys are inefficient, but encounters with MPTs raise the δ v of ∼60% of our test particles to > 200 {{m}} {{{s}}}-1 with respect to Himalia, in agreement with observations. As MPTs may not have been abundant in the disk, we simulate encounters between Jupiter and PMOs. We find that too few encounters generate less dispersion than MPTs while too many essentially destroy the family. For PMO masses in the range 5{--}20 {m}\\oplus , the family orbital distribution is reproduced by a few tens of encounters.

The journey of Typhon-Echidna as a binary system through the planetary region

NASA Astrophysics Data System (ADS)

Araujo, R. A. N.; Galiazzo, M. A.; Winter, O. C.; Sfair, R.

2018-06-01

Among the current population of the 81 known trans-Neptunian binaries (TNBs), only two are in orbits that cross the orbit of Neptune. These are (42355) Typhon-Echidna and (65489) Ceto-Phorcys. In this work, we focused our analyses on the temporal evolution of the Typhon-Echidna binary system through the outer and inner planetary systems. Using numerical integrations of the N-body gravitational problem, we explored the orbital evolutions of 500 clones of Typhon, recording the close encounters of those clones with planets. We then analysed the effects of those encounters on the binary system. It was found that only {≈ }22 per cent of the encounters with the giant planets were strong enough to disrupt the binary. This binary system has an ≈ 3.6 per cent probability of reaching the terrestrial planetary region over a time-scale of approximately 5.4 Myr. Close encounters of Typhon-Echidna with Earth and Venus were also registered, but the probabilities of such events occurring are low ({≈}0.4 per cent). The orbital evolution of the system in the past was also investigated. It was found that in the last 100 Myr, Typhon might have spent most of its time as a TNB crossing the orbit of Neptune. Therefore, our study of the Typhon-Echidna orbital evolution illustrates the possibility of large cometary bodies (radii of 76 km for Typhon and 42 km for Echidna) coming from a remote region of the outer Solar system and that might enter the terrestrial planetary region preserving its binarity throughout the journey.

Recovery-Oriented Vocational Rehabilitation Services for Individuals with Co-Occurring Psychiatric Disabilities and Substance Use Disorders

ERIC Educational Resources Information Center

Lusk, Stephanie L.; Koch, Lynn C.; Paul, Teresia M.

2016-01-01

Purpose: In this article, we examined how individuals with co-occurring psychiatric disabilities and substance use disorders encounter numerous challenges when it comes to the vocational rehabilitation (VR) process. Method: A comprehensive review of the literature demonstrated barriers to service delivery (e.g., access to services, exclusionary…

Development of L2 Word-Meaning Inference while Reading

ERIC Educational Resources Information Center

Hamada, Megumi

2009-01-01

Ability to infer the meaning of unknown words encountered while reading plays an important role in learners' L2 word-knowledge development. Despite numerous findings reported on word-meaning inference, how learners develop this ability is still unclear. In order to provide a developmental inquiry into L2 word-meaning inference while reading, this…

Determination of the Rotational Barrier in Ethane by Vibrational Spectroscopy and Statistical Thermodynamics

ERIC Educational Resources Information Center

Ercolani, Gianfranco

2005-01-01

The finite-difference boundary-value method is a numerical method suited for the solution of the one-dimensional Schrodinger equation encountered in problems of hindered rotation. Further, the application of the method, in combination with experimental results for the evaluation of the rotational energy barrier in ethane is presented.

Probabilistic evaluation of SSME structural components

NASA Astrophysics Data System (ADS)

Rajagopal, K. R.; Newell, J. F.; Ho, H.

1991-05-01

The application is described of Composite Load Spectra (CLS) and Numerical Evaluation of Stochastic Structures Under Stress (NESSUS) family of computer codes to the probabilistic structural analysis of four Space Shuttle Main Engine (SSME) space propulsion system components. These components are subjected to environments that are influenced by many random variables. The applications consider a wide breadth of uncertainties encountered in practice, while simultaneously covering a wide area of structural mechanics. This has been done consistent with the primary design requirement for each component. The probabilistic application studies are discussed using finite element models that have been typically used in the past in deterministic analysis studies.

Numerical developments for short-pulsed Near Infra-Red laser spectroscopy. Part I: direct treatment

NASA Astrophysics Data System (ADS)

Boulanger, Joan; Charette, André

2005-03-01

This two part study is devoted to the numerical treatment of short-pulsed laser near infra-red spectroscopy. The overall goal is to address the possibility of numerical inverse treatment based on a recently developed direct model to solve the transient radiative transfer equation. This model has been constructed in order to incorporate the last improvements in short-pulsed laser interaction with semi-transparent media and combine a discrete ordinates computing of the implicit source term appearing in the radiative transfer equation with an explicit treatment of the transport of the light intensity using advection schemes, a method encountered in reactive flow dynamics. The incident collimated beam is analytically solved through Bouger Beer Lambert extinction law. In this first part, the direct model is extended to fully non-homogeneous materials and tested with two different spatial schemes in order to be adapted to the inversion methods presented in the following second part. As a first point, fundamental methods and schemes used in the direct model are presented. Then, tests are conducted by comparison with numerical simulations given as references. In a third and last part, multi-dimensional extensions of the code are provided. This allows presentation of numerical results of short pulses propagation in 1, 2 and 3D homogeneous and non-homogeneous materials given some parametrical studies on medium properties and pulse shape. For comparison, an integral method adapted to non-homogeneous media irradiated by a pulsed laser beam is also developed for the 3D case.

Faster PET reconstruction with a stochastic primal-dual hybrid gradient method

NASA Astrophysics Data System (ADS)

Ehrhardt, Matthias J.; Markiewicz, Pawel; Chambolle, Antonin; Richtárik, Peter; Schott, Jonathan; Schönlieb, Carola-Bibiane

2017-08-01

Image reconstruction in positron emission tomography (PET) is computationally challenging due to Poisson noise, constraints and potentially non-smooth priors-let alone the sheer size of the problem. An algorithm that can cope well with the first three of the aforementioned challenges is the primal-dual hybrid gradient algorithm (PDHG) studied by Chambolle and Pock in 2011. However, PDHG updates all variables in parallel and is therefore computationally demanding on the large problem sizes encountered with modern PET scanners where the number of dual variables easily exceeds 100 million. In this work, we numerically study the usage of SPDHG-a stochastic extension of PDHG-but is still guaranteed to converge to a solution of the deterministic optimization problem with similar rates as PDHG. Numerical results on a clinical data set show that by introducing randomization into PDHG, similar results as the deterministic algorithm can be achieved using only around 10 % of operator evaluations. Thus, making significant progress towards the feasibility of sophisticated mathematical models in a clinical setting.

Ion Composition in Titan's Exosphere from the Cassini Plasma Spectrometer

NASA Astrophysics Data System (ADS)

Woodson, A.; Smith, H. T.; Johnson, R. E.

2013-12-01

A primary goal of the Cassini mission has been to characterize the complex interaction between Saturn's magnetosphere and Titan's ionosphere. To this end, the Cassini spacecraft carries two instruments-the Ion and Neutral Mass Spectrometer (INMS) and the Cassini Plasma Spectrometer (CAPS)-capable of energy- and mass-analysis. The Ion Mass Spectrometer (IMS), one of three instruments composing CAPS, is designed to characterize diffuse plasmas throughout the magnetosphere while the INMS is optimized for measurements within Titan's upper atmosphere. As such, mass-resolved ion compositions confirming a variety of hydrocarbons and nitriles have been extracted from INMS data for numerous Titan encounters. Similar analysis of IMS data, however, has largely been resolution-limited to the identification of 'light' and 'heavy' ion groups in the wake. Herein we present a technique for extracting Dalton-resolved ion compositions from IMS spectra acquired below ~5 Titan radii. The method is then applied to data from the T40 encounter and the resulting relative abundances compared with those derived from the INMS data for the same encounter.

Battered Agency Syndrome: The Challenge to Agencies Serving Low-Income Communities.

ERIC Educational Resources Information Center

Reed, Diane; Lally, J. Ronald; Quiett, Douglas

Community-based social service agencies working in low-income communities increasingly function with inadequate support and encounter numerous oppressive external and internal conditions that compromise organizational and staff well-being. Working with many such agencies, WestEd identified stressors that included funding problems, unrealistic…

The use of cone penetration testing to investigate sand fill subsidence at cross-drain locations: final report : Volume I.

DOT National Transportation Integrated Search

1984-03-01

During construction of Interstate I-10 between Baton Rouge and LaPlace, Louisiana, highly organic swamp deposits were excavated and replaced with hydraulically pumped river sand. Recently, excessive settlement was encountered at numerous cross-drain ...

Respectful Interactions: Learning with International Students in the English-Speaking Academy

ERIC Educational Resources Information Center

Ryan, Janette; Viete, Rosemary

2009-01-01

International students entering postgraduate courses in Australian universities encounter numerous challenges in their new environments. Many relate to the academic literacy and pedagogical practices in the English-speaking academic environment, which international students time and again have reported assume local linguistic and cultural…

Conservation of streptococcal CRISPRs on human skin and saliva.

PubMed

Robles-Sikisaka, Refugio; Naidu, Mayuri; Ly, Melissa; Salzman, Julia; Abeles, Shira R; Boehm, Tobias K; Pride, David T

2014-06-06

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) are utilized by bacteria to resist encounters with their viruses. Human body surfaces have numerous bacteria that harbor CRISPRs, and their content can provide clues as to the types and features of viruses they may have encountered. We investigated the conservation of CRISPR content from streptococci on skin and saliva of human subjects over 8-weeks to determine whether similarities existed in the CRISPR spacer profiles and whether CRISPR spacers were a stable component of each biogeographic site. Most of the CRISPR sequences identified were unique, but a small proportion of spacers from the skin and saliva of each subject matched spacers derived from previously sequenced loci of S. thermophilus and other streptococci. There were significant proportions of CRISPR spacers conserved over the entire 8-week study period for all subjects, and salivary CRISPR spacers sampled in the mornings showed significantly higher levels of conservation than any other time of day. We also found substantial similarities in the spacer repertoires of the skin and saliva of each subject. Many skin-derived spacers matched salivary viruses, supporting that bacteria of the skin may encounter viruses with similar sequences to those found in the mouth. Despite the similarities between skin and salivary spacer repertoires, the variation present was distinct based on each subject and body site. The conservation of CRISPR spacers in the saliva and the skin of human subjects over the time period studied suggests a relative conservation of the bacteria harboring them.

Conservation of streptococcal CRISPRs on human skin and saliva

PubMed Central

2014-01-01

Background Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) are utilized by bacteria to resist encounters with their viruses. Human body surfaces have numerous bacteria that harbor CRISPRs, and their content can provide clues as to the types and features of viruses they may have encountered. Results We investigated the conservation of CRISPR content from streptococci on skin and saliva of human subjects over 8-weeks to determine whether similarities existed in the CRISPR spacer profiles and whether CRISPR spacers were a stable component of each biogeographic site. Most of the CRISPR sequences identified were unique, but a small proportion of spacers from the skin and saliva of each subject matched spacers derived from previously sequenced loci of S. thermophilus and other streptococci. There were significant proportions of CRISPR spacers conserved over the entire 8-week study period for all subjects, and salivary CRISPR spacers sampled in the mornings showed significantly higher levels of conservation than any other time of day. We also found substantial similarities in the spacer repertoires of the skin and saliva of each subject. Many skin-derived spacers matched salivary viruses, supporting that bacteria of the skin may encounter viruses with similar sequences to those found in the mouth. Despite the similarities between skin and salivary spacer repertoires, the variation present was distinct based on each subject and body site. Conclusions The conservation of CRISPR spacers in the saliva and the skin of human subjects over the time period studied suggests a relative conservation of the bacteria harboring them. PMID:24903519

Advanced rotorcraft control using parameter optimization

NASA Technical Reports Server (NTRS)

Vansteenwyk, Brett; Ly, Uy-Loi

1991-01-01

A reliable algorithm for the evaluation of a quadratic performance index and its gradients with respect to the controller design parameters is presented. The algorithm is part of a design algorithm for an optimal linear dynamic output feedback controller that minimizes a finite time quadratic performance index. The numerical scheme is particularly robust when it is applied to the control law synthesis for systems with densely packed modes and where there is a high likelihood of encountering degeneracies in the closed loop eigensystem. This approach through the use of a accurate Pade series approximation does not require the closed loop system matrix to be diagonalizable. The algorithm has been included in a control design package for optimal robust low order controllers. Usefulness of the proposed numerical algorithm has been demonstrated using numerous practical design cases where degeneracies occur frequently in the closed loop system under an arbitrary controller design initialization and during the numerical search.

Numerical modeling and simulation studies for the M4 adaptive mirror of the E-ELT

NASA Astrophysics Data System (ADS)

Carbillet, Marcel; Riccardi, Armando; Xompero, Marco

2012-07-01

We report in this paper on the progress of numerical modeling and simulation studies of the M4 adaptive mirror, a representative of the "adaptive secondary mirrors" technology, for the European Extremely Large Telescope (E-ELT). This is based on both dedicated routines and the existing code of the Software Package CADS. The points approached are basically the specific problems encountered with this particular type of voice-coil adaptive mirrors on the E-ELT: (*) the segmentation of the adaptive mirror, implying a fitting error due also to the edges of its six petals, as well as possible co-phasing problems to be evaluated in terms of interaction with the wavefront sensor (a pyramid here); (**) the necessary presence of "master" and "slave" actuators which management, in terms of wavefront reconstruction, implies to consider different strategies. The on-going work being performed for the two above points is described in details, and some preliminary results are given.

Numerical simulation of lava flows: Applications to the terrestrial planets

NASA Technical Reports Server (NTRS)

Zimbelman, James R.; Campbell, Bruce A.; Kousoum, Juliana; Lampkin, Derrick J.

1993-01-01

Lava flows are the visible expression of the extrusion of volcanic materials on a variety of planetary surfaces. A computer program described by Ishihara et al. appears to be well suited for application to different environments, and we have undertaken tests to evaluate their approach. Our results are somewhat mixed; the program does reproduce reasonable lava flow behavior in many situations, but we have encountered some conditions common to planetary environments for which the current program is inadequate. Here we present our initial efforts to identify the 'parameter space' for reasonable numerical simulations of lava flows.

Science Literacy's Neglected Twin: Numeracy

NASA Astrophysics Data System (ADS)

Follette, K.; McCarthy, D.

2014-07-01

Have introductory astronomy courses moved too far toward qualitative science? By itself, qualitative understanding, even deep appreciation, of the scientific endeavor is insufficient to engender scientific literacy. In order to interpret scientific information encountered in daily life and to distinguish it from pseudoscience, our students must also be quantitatively savvy. A scientifically literate citizen should be able to employ arithmetic, interpret numbers in context, read graphs and tables, and confidently incorporate numbers in writing. A gentle quantitative emphasis permeates our introductory astronomy courses to help our students become aware of their numerical deficits and appreciate the value of numerical thinking. This approach not only helps transform students into more well-informed citizens and capable problem solvers but also helps them achieve a deeper understanding of course material. We present data from an educational study that documents the extent of quantitative illiteracy and shows that improvements in attitude and achievement are possible.

Black-Hole Binaries, Gravitational Waves, and Numerical Relativity

NASA Technical Reports Server (NTRS)

Kelly, Bernard J.; Centrella, Joan; Baker, John G.; Kelly, Bernard J.; vanMeter, James R.

2010-01-01

Understanding the predictions of general relativity for the dynamical interactions of two black holes has been a long-standing unsolved problem in theoretical physics. Black-hole mergers are monumental astrophysical events ' releasing tremendous amounts of energy in the form of gravitational radiation ' and are key sources for both ground- and spacebased gravitational wave detectors. The black-hole merger dynamics and the resulting gravitational waveforms can only he calculated through numerical simulations of Einstein's equations of general relativity. For many years, numerical relativists attempting to model these mergers encountered a host of problems, causing their codes to crash after just a fraction of a binary orbit cnuld be simulated. Recently ' however, a series of dramatic advances in numerical relativity has ' for the first time, allowed stable / robust black hole merger simulations. We chronicle this remarkable progress in the rapidly maturing field of numerical relativity, and the new understanding of black-hole binary dynamics that is emerging. We also discuss important applications of these fundamental physics results to astrophysics, to gravitationalwave astronomy, and in other areas.

A model for bacterial colonization of sinking aggregates.

PubMed

Bearon, R N

2007-01-01

Sinking aggregates provide important nutrient-rich environments for marine bacteria. Quantifying the rate at which motile bacteria colonize such aggregations is important in understanding the microbial loop in the pelagic food web. In this paper, a simple analytical model is presented to predict the rate at which bacteria undergoing a random walk encounter a sinking aggregate. The model incorporates the flow field generated by the sinking aggregate, the swimming behavior of the bacteria, and the interaction of the flow with the swimming behavior. An expression for the encounter rate is computed in the limit of large Péclet number when the random walk can be approximated by a diffusion process. Comparison with an individual-based numerical simulation is also given.

Generalization of von Neumann analysis for a model of two discrete half-spaces: The acoustic case

USGS Publications Warehouse

Haney, M.M.

2007-01-01

Evaluating the performance of finite-difference algorithms typically uses a technique known as von Neumann analysis. For a given algorithm, application of the technique yields both a dispersion relation valid for the discrete time-space grid and a mathematical condition for stability. In practice, a major shortcoming of conventional von Neumann analysis is that it can be applied only to an idealized numerical model - that of an infinite, homogeneous whole space. Experience has shown that numerical instabilities often arise in finite-difference simulations of wave propagation at interfaces with strong material contrasts. These interface instabilities occur even though the conventional von Neumann stability criterion may be satisfied at each point of the numerical model. To address this issue, I generalize von Neumann analysis for a model of two half-spaces. I perform the analysis for the case of acoustic wave propagation using a standard staggered-grid finite-difference numerical scheme. By deriving expressions for the discrete reflection and transmission coefficients, I study under what conditions the discrete reflection and transmission coefficients become unbounded. I find that instabilities encountered in numerical modeling near interfaces with strong material contrasts are linked to these cases and develop a modified stability criterion that takes into account the resulting instabilities. I test and verify the stability criterion by executing a finite-difference algorithm under conditions predicted to be stable and unstable. ?? 2007 Society of Exploration Geophysicists.

Navigation and guidance of Japanese deepspace probes encountering Halley's comet

NASA Astrophysics Data System (ADS)

Nishimura, T.; Matsuo, H.; Takano, T.; Kawaguchi, J.

The techniques used by ISAS in the guidance of the Sakigake and Suisei probes, which encountered Comet Halley in March 1986, are reviewed. Consideration is given to the guidance of the last rocket stage in the direct ascent phase, midcourse maneuvers, tracking systems and communication links, the tracking strategy, trajectory-generation and orbit-determination software, and orbit-determination accuracy. Diagrams, drawings, graphs, photographs, and tables of numerical data are provided, and the ISAS positions of both probes during the first 10 days after launch are shown to be within 100 km in distance and 1 m/sec in velocity of NASA coordinate estimates.

Massive stars, disks, and clustered star formation

NASA Astrophysics Data System (ADS)

Moeckel, Nickolas Barry

The formation of an isolated massive star is inherently more complex than the relatively well-understood collapse of an isolated, low-mass star. The dense, clustered environment where massive stars are predominantly found further complicates the picture, and suggests that interactions with other stars may play an important role in the early life of these objects. In this thesis we present the results of numerical hydrodynamic experiments investigating interactions between a massive protostar and its lower-mass cluster siblings. We explore the impact of these interactions on the orientation of disks and outflows, which are potentially observable indications of encounters during the formation of a star. We show that these encounters efficiently form eccentric binary systems, and in clusters similar to Orion they occur frequently enough to contribute to the high multiplicity of massive stars. We suggest that the massive protostar in Cepheus A is currently undergoing a series of interactions, and present simulations tailored to that system. We also apply the numerical techniques used in the massive star investigations to a much lower-mass regime, the formation of planetary systems around Solar- mass stars. We perform a small number of illustrative planet-planet scattering experiments, which have been used to explain the eccentricity distribution of extrasolar planets. We add the complication of a remnant gas disk, and show that this feature has the potential to stabilize the system against strong encounters between planets. We present preliminary simulations of Bondi-Hoyle accretion onto a protoplanetary disk, and consider the impact of the flow on the disk properties as well as the impact of the disk on the accretion flow.

Multi-Attribute Sequential Search

ERIC Educational Resources Information Center

Bearden, J. Neil; Connolly, Terry

2007-01-01

This article describes empirical and theoretical results from two multi-attribute sequential search tasks. In both tasks, the DM sequentially encounters options described by two attributes and must pay to learn the values of the attributes. In the "continuous" version of the task the DM learns the precise numerical value of an attribute when she…

Promoting Social and Emotional Growth of Students with Disabilities

ERIC Educational Resources Information Center

Darrow, Alice-Ann

2014-01-01

Students with disabilities are often faced with numerous challenges as they progress through their school years. In addition to disability-related challenges, they may encounter additional difficulties such as bullying in school and lack of social acceptance by their peers. It is important that students with disabilities develop competence in…

Literature for Children: An Engagement with Life.

ERIC Educational Resources Information Center

Allen, Arthur T.

1967-01-01

The two complementary questions--"What does literature do to young readers?" and "Can literature be taught?"--are not easily answered. Youth should not employ literature as an exclusive guide to life since they will encounter numerous unrealistic situations. Instead, literature should entice them to deal vicariously with vivid, new experiences and…

Career Advancement of Women Senior Academic Administrators in Indonesia: Supports and Challenges

ERIC Educational Resources Information Center

Murniati, Cecilia Titiek

2012-01-01

Increasing numbers of women have gained access to college and the college teaching profession worldwide. However, women continue to be underrepresented in academic, research, and leadership positions. Women who have aspirations for top leadership positions still encounter numerous internal and external challenges. Existent literature on women…

Nursery Diseases of Southern Hardwoods

Treesearch

S. J. Rowan; T. H. Filer; W. R. Phelps

1983-01-01

Numerous diseases may be encountered in hardwood plantings in Southern nurseries. Although severe disease losses have been observed in only a few hardwood species, some loss occurs in nursery plantings of all species and can be expected to continue. The lack of an effective post-emergence herbicide to control weeds in hardwood nursery seedbeds and the high cost of hand...

The Atomic Mass Unit, the Avogadro Constant, and the Mole: A Way to Understanding

ERIC Educational Resources Information Center

Baranski, Andrzej

2012-01-01

Numerous articles have been published that address problems encountered in teaching basic concepts of chemistry such as the atomic mass unit, Avogadro's number, and the mole. The origin of these problems is found in the concept definitions. If these definitions are adjusted for teaching purposes, understanding could be improved. In the present…

Cyclone-cyclone Interactions through the Ocean Pathway

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balaguru, Karthik; Taraphdar, Sourav; Leung, Lai-Yung R.

The intense SST (Sea Surface Temperature) cooling caused by hurricane-induced mixing is restored at timescales on the order of weeks(1) and thus may persist long enough to influence a later hurricane passing over it. Though many studies have evaluated the effects of SST cool-ing induced by a hurricane on its own intensification(2, 3), none has looked at its effect on later storms. Using an analysis of observations and numerical model simulations, we demonstrate that hurricanes may influence the intensity of later hurricanes that pass over their linger-ing wakes. On average, when hurricanes encounter cold wakes, they experience SSTs that aremore » ~0.4oC lower than when they do not encounter wakes and consequently decay(intensify) at a rate that is nearly three times faster(slower). In the region of warm SSTs (* 26.5oC) where the most intense and damaging hurricanes tend to occur, the percentage of hurricanes that encounter lingering cold wakes increases with hurricane frequency and was found to be as high as 40%. Furthermore, we estimate that the cumulative power dissipated(4) by the most energetic hurricanes has been reduced by as much as ~7% in a season through this effect. As the debate on changes in Atlantic hurricane activity associated with global warming(5) continues, the negative feedback between hurricane frequency and intensity resulting from hurricane-hurricane interactions through the ocean pathway deserves attention.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Araujo, R. A. N.; Sfair, R.; Winter, O. C., E-mail: ran.araujo@gmail.com, E-mail: rsfair@feg.unesp.br, E-mail: ocwinter@gmail.com

The Centaur population is composed of minor bodies wandering between the giant planets that frequently perform close gravitational encounters with these planets, leading to a chaotic orbital evolution. Recently, the discovery of two well-defined narrow rings was announced around the Centaur 10199 Chariklo. The rings are assumed to be in the equatorial plane of Chariklo and to have circular orbits. The existence of a well-defined system of rings around a body in such a perturbed orbital region poses an interesting new problem. Are the rings of Chariklo stable when perturbed by close gravitational encounters with the giant planets? Our approachmore » to address this question consisted of forward and backward numerical simulations of 729 clones of Chariklo, with similar initial orbits, for a period of 100 Myr. We found, on average, that each clone experiences during its lifetime more than 150 close encounters with the giant planets within one Hill radius of the planet in question. We identified some extreme close encounters that were able to significantly disrupt or disturb the rings of Chariklo. About 3% of the clones lose their rings and about 4% of the clones have their rings significantly disturbed. Therefore, our results show that in most cases (more than 90%), the close encounters with the giant planets do not affect the stability of the rings in Chariklo-like systems. Thus, if there is an efficient mechanism that creates the rings, then these structures may be common among these kinds of Centaurs.« less

Electron kinetics dependence on gas pressure in laser-induced oxygen plasma experiment: Theoretical analysis

NASA Astrophysics Data System (ADS)

Gamal, Yosr E. E.-D.; Abdellatif, Galila

2017-08-01

A study is performed to investigate the dependency of threshold intensity on gas pressure observed in the measurements of the breakdown of molecular oxygen that carried out by Phuoc (2000) [1]. In this experiment, the breakdown was induced by 532 nm laser radiation of pulse width 5.5 ns and spot size of 8.5 μm, in oxygen over a wide pressure range (190-3000 Torr). The analysis aimed to explore the electron kinetic reliance on gas pressure for the separate contribution of each of the gain and loss processes encountered in this study. The investigation is based on an electron cascade model applied previously in Gamal and Omar (2001) [2] and Gaabour et al. (2013) [3]. This model solves numerically a differential equation designates the time evolution of the electron energy distribution, and a set of rate equations that describe the change of excited states population. The numerical examination of the electron energy distribution function and its parameters revealed that photo-ionization of the excited molecules plays a significant role in enhancing the electron density growth rate over the whole tested gas pressure range. This process is off set by diffusion of electrons out of the focal volume in the low-pressure regime. At atmospheric pressure electron, collisional processes dominate and act mainly to populate the excited states. Hence photo-ionization becomes efficient and compete with the encountered loss processes (electron diffusion, vibrational excitation of the ground state molecules as well as two body attachments). At high pressures ( 3000 Torr) three body attachments are found to be the primary cause of losses which deplete the electron density and hence results in the slow decrease of the threshold intensity.

Freshwater Export from the Arctic Ocean and its Downstream Effect on Labrador Sea Deep Convection in a High-Resolution Numerical Model

DTIC Science & Technology

2010-12-01

Arctic has been observed in the northern Canadian Arctic Archipelago ( Bourke and McLaren 1992). There, thick multiyear ice of Arctic origin encounters...Affairs, 87(2), 63-77. 172 Bourke , R. H., and A. S. McLaren, 1992: Contour mapping of Arctic Basin ice draft and roughness parameters. J. Geophys

Application of micropolar plasticity to post failure analysis in geomechanics

NASA Astrophysics Data System (ADS)

Manzari, Majid T.

2004-08-01

A micropolar elastoplastic model for soils is formulated and a series of finite element analyses are employed to demonstrate the use of a micropolar continuum in overcoming the numerical difficulties encountered in application of finite element method in standard Cauchy-Boltzmann continuum. Three examples of failure analysis involving a deep excavation, shallow foundation, and a retaining wall are presented. In all these cases, it is observed that the length scale introduced in the polar continuum regularizes the incremental boundary value problem and allows the numerical simulation to be continued until a clear collapse mechanism is achieved. The issue of grain size effect is also discussed. Copyright

Optimality study of a gust alleviation system for light wing-loading STOL aircraft

NASA Technical Reports Server (NTRS)

Komoda, M.

1976-01-01

An analytical study was made of an optimal gust alleviation system that employs a vertical gust sensor mounted forward of an aircraft's center of gravity. Frequency domain optimization techniques were employed to synthesize the optimal filters that process the corrective signals to the flaps and elevator actuators. Special attention was given to evaluating the effectiveness of lead time, that is, the time by which relative wind sensor information should lead the actual encounter of the gust. The resulting filter is expressed as an implicit function of the prescribed control cost. A numerical example for a light wing loading STOL aircraft is included in which the optimal trade-off between performance and control cost is systematically studied.

Charge carrier concentration dependence of encounter-limited bimolecular recombination in phase-separated organic semiconductor blends

NASA Astrophysics Data System (ADS)

Heiber, Michael C.; Nguyen, Thuc-Quyen; Deibel, Carsten

2016-05-01

Understanding how the complex intermolecular configurations and nanostructure present in organic semiconductor donor-acceptor blends impacts charge carrier motion, interactions, and recombination behavior is a critical fundamental issue with a particularly major impact on organic photovoltaic applications. In this study, kinetic Monte Carlo (KMC) simulations are used to numerically quantify the complex bimolecular charge carrier recombination behavior in idealized phase-separated blends. Recent KMC simulations have identified how the encounter-limited bimolecular recombination rate in these blends deviates from the often used Langevin model and have been used to construct the new power mean mobility model. Here, we make a challenging but crucial expansion to this work by determining the charge carrier concentration dependence of the encounter-limited bimolecular recombination coefficient. In doing so, we find that an accurate treatment of the long-range electrostatic interactions between charge carriers is critical, and we further argue that many previous KMC simulation studies have used a Coulomb cutoff radius that is too small, which causes a significant overestimation of the recombination rate. To shed more light on this issue, we determine the minimum cutoff radius required to reach an accuracy of less than ±10 % as a function of the domain size and the charge carrier concentration and then use this knowledge to accurately quantify the charge carrier concentration dependence of the recombination rate. Using these rigorous methods, we finally show that the parameters of the power mean mobility model are determined by a newly identified dimensionless ratio of the domain size to the average charge carrier separation distance.

Numerical System Solver Developed for the National Cycle Program

NASA Technical Reports Server (NTRS)

Binder, Michael P.

1999-01-01

As part of the National Cycle Program (NCP), a powerful new numerical solver has been developed to support the simulation of aeropropulsion systems. This software uses a hierarchical object-oriented design. It can provide steady-state and time-dependent solutions to nonlinear and even discontinuous problems typically encountered when aircraft and spacecraft propulsion systems are simulated. It also can handle constrained solutions, in which one or more factors may limit the behavior of the engine system. Timedependent simulation capabilities include adaptive time-stepping and synchronization with digital control elements. The NCP solver is playing an important role in making the NCP a flexible, powerful, and reliable simulation package.

A spacecraft's own ambient environment: The role of simulation-based research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ketsdever, Andrew D.; Gimelshein, Sergey

2014-12-09

Spacecraft contamination has long been a subject of study in the rarefied gas dynamics community. Professor Mikhail Ivanov coined the term a spacecraft's 'own ambient environment' to describe the effects of natural and satellite driven processes on the conditions encountered by a spacecraft in orbit. Outgassing, thruster firings, and gas and liquid dumps all contribute to the spacecraft's contamination environment. Rarefied gas dynamic modeling techniques, such as Direct Simulation Monte Carlo, are well suited to investigate these spacebased environments. However, many advances were necessary to fully characterize the extent of this problem. A better understanding of modeling flows over largemore » pressure ranges, for example hybrid continuum and rarefied numerical schemes, were required. Two-phase flow modeling under rarefied conditions was necessary. And the ability to model plasma flows for a new era of propulsion systems was also required. Through the work of Professor Ivanov and his team, we now have a better understanding of processes that create a spacecraft's own ambient environment and are able to better characterize these environments. Advances in numerical simulation have also spurred on the development of experimental facilities to study these effects. The relationship between numerical results and experimental advances will be explored in this manuscript.« less

Chaotic Diffusion of the Vesta Family

NASA Astrophysics Data System (ADS)

Delisle, Jean-Baptiste; Laskar, J.

2012-10-01

The Vesta family is a known source of near-Earth asteroids (NEAs). Members of this family first slowly migrate in the main belt until they enter in the nu_6 or the 3:1 resonance with Jupiter. Their life time is then very short, and they often become NEAs before reaching hyperbolic orbits (Migliorini et al. 1997). The Yarkovsky effect is considered as the main explanation for the slow migration of Vesta family asteroids towards both resonances (Carruba et al. 2003). We numerically estimate the semi-major axis diffusion of Vesta family members induced by close encounters with 11 massive main-belt asteroids: (1) Ceres, (2) Pallas, (3) Juno, (4) Vesta, (7) Iris, (10) Hygiea, (15) Eunomia, (19) Fortuna, (324) Bamberga, (532) Herculina, (704) Interamnia. We find that most of the diffusion is due to Ceres and Vesta. We extrapolate our results to constrain the global effect of close encounters with all main-belt asteroids. We show that for asteroids whose diameter is larger than about 40 km, the diffusion due to close encounters dominate the Yarkovsky effect (Delisle & Laskar 2012). Since Vesta family members are all smaller than 8 km, we confirm that the main mechanism of its diffusion is the Yarkovsky effect. We also show by extrapolations on the closest distance of approach during encounters that 10 over the 13800 known Vesta family objects (Nesvorny, 2010) may have had an encounter with Vesta within one diameter over the age of the family. Such an event may have resulted in a semi-major axis jump of about 1 AU. Thus, even if the mean effect of close encounters is secondary compared to the Yarkovsky effect, they considerably affect some individual orbits. Ref: Delisle, J.-B., & Laskar, J.: 2012, Chaotic diffusion of the Vesta family induced by close encounters with massive asteroids, A&A, 540, A118

Tones Encountered with a Coannular Nozzle and a Method for Their Suppression

NASA Technical Reports Server (NTRS)

Zaman, Khairul Bmq; Bridges, James E.; Fagan, Amy Florence; Miller, Christopher J.

2017-01-01

With multi-stream coannular nozzles, sometimes tones occur that may cause the nozzle to fail noise regulation standards. A two-stream nozzle was studied experimentally and numerically in an attempt to identify the sources of such tones and explore remedies. For the given nozzle configuration, sharp tones occurred in a range of low jet Mach numbers. The tones apparently occurred due to a coupling between vortex shedding from the struts, which held the nozzles and the center-body together, with various duct acoustic modes. A leading edge treatment of the struts is shown to eliminate the tones via disruption of the vortex shedding.

Tones Encountered with a Coannular Nozzle and a Method for their Suppression

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.; Bridges, J. E.; Fagan, A. F.; Miller, C. J.

2017-01-01

With multi-stream coannular nozzles, sometimes tones occur that may cause the nozzle to fail noise regulation standards. A two-stream nozzle was studied experimentally and numerically in an at-tempt to identify the sources of such tones and explore remedies. For the given nozzle configuration, sharp tones occurred in a range of low jet Mach numbers. The tones apparently occurred due to a coupling between vortex shedding from the struts, which held the nozzles and the center-body together, with various duct acoustic modes. A leading edge treatment of the struts is shown to eliminate the tones via disruption of the vortex shedding.

Use of Relativistic Effective Core Potentials in the Calculation of Electron-Impact Ionization Cross Sections

NASA Technical Reports Server (NTRS)

Huo, Winifred M.; Kim, Yong-Ki

1999-01-01

Based on the Binary-Encounter-Bethe (BEB) model, the advantage of using relativistic effective core potentials (RECP) in the calculation of total ionization cross sections of heavy atoms or molecules containing heavy atoms is discussed. Numerical examples for Ar, Kr, Xe, and WF6 are presented.

Writers of the American West: Multicultural Learning Encounters.

ERIC Educational Resources Information Center

Stansfield, John

This book focuses on the childhood and young adult experience of 10 of the American West's most intriguing writers. The book presents autobiographical and other primary sources, biographical sketches, teaching guidelines, and numerous curriculum-driven activities to engage young readers in the works of notable people whose lives were shaped by the…

Our Children are Alcoholics: Coping with Children Who Have Addictions.

ERIC Educational Resources Information Center

B., Sally; B., David

This book provides numerous stories of parents' encounters with their children's addictions and what the parents did to come to terms with the disease. Part 1 offers four separate accounts describing the authors' experience with addiction in their four adult children, followed by each child's interpretation of events. In part 2, addictive diseases…

The Role of Intuitive Approximation Skills for School Math Abilities

ERIC Educational Resources Information Center

Libertus, Melissa E.

2015-01-01

Research has shown that educated children and adults have access to two ways of representing numerical information: an approximate number system (ANS) that is present from birth and allows for quick approximations of numbers of objects encountered in one's environment, and an exact number system (ENS) that is acquired through experience and…

A general method for computing the total solar radiation force on complex spacecraft structures

NASA Technical Reports Server (NTRS)

Chan, F. K.

1981-01-01

The method circumvents many of the existing difficulties in computational logic presently encountered in the direct analytical or numerical evaluation of the appropriate surface integral. It may be applied to complex spacecraft structures for computing the total force arising from either specular or diffuse reflection or even from non-Lambertian reflection and re-radiation.

Engineering Encounters: No, David! but Yes, Design! Kindergarten Students Are Introduced to a Design Way of Thinking

ERIC Educational Resources Information Center

Douglass, Helen

2016-01-01

This column presents ideas and techniques to enhance science teaching. In today's classrooms, teachers face numerous challenges. They are preparing students for jobs and careers that are not even conceived of yet. Assessments are being used to address students' college and career readiness and to promote critical thinking and problem solving.…

Select Caribbean Teachers' Perspectives on the Socio-Emotional Skills Children Need to Successfully Transition to Primary School

ERIC Educational Resources Information Center

Kinkead-Clark, Zoyah

2017-01-01

Children's transition to primary school is affected by numerous factors. Many teachers, expect that children will have the academic and socioemotional competencies to negotiate and deal with new experiences they may encounter in a new learning environment. With an aim of contextualising our understanding of the transitory period from pre-primary…

Dynamics of multiple bodies in a corotation resonance

NASA Astrophysics Data System (ADS)

A'Hearn, Joseph; Hedman, Matthew

2018-04-01

The orbital evolution of multiple massive bodies trapped in the same corotation resonance site has not yet been studied in depth, but could be relevant to the origins and history of small moons like Saturn's moon Aegaeon. We conduct numerical simulations of multiple bodies trapped within a corotation resonance and examine what happens to these bodies when they have close encounters. Compared to simulations with equal mass bodies, simulations with one body more massive than the others may be more likely to feature an asymmetry in the phase space of semi-major axis and mean longitude. That is, bodies on one side of phase space have a slightly greater tendency to lose angular momentum, while bodies on the other side gain angular momentum. With this asymmetry, the transfer of angular momentum during gravitational encounters makes it more likely for the most massive body rather than other bodies to approach the center of the corotation site. More work is needed to determine if this sort of process can significantly affect the orbital evolution of small moons like Aegaeon.

Quarantine constraints as applied to satellites

NASA Technical Reports Server (NTRS)

Hoffman, A. R.; Stavro, W.; Gonzalez, C. C.

1973-01-01

Plans for unmanned missions to planets beyond Mars in the 1970s include satellite encounters. Recently published observations of data for Titan, a satellite of Saturn, indicate that conditions may be hospitable for the growth of microorganisms. Therefore, the problem of satisfying possible quarantine constraints for outer planet satellites was investigated. This involved determining the probability of impacting a satellite of Jupiter or Saturn by a spacecraft for a planned satellite encounter during an outer planet mission. Mathematical procedures were formulated which determine the areas in the aim-plane that would result in trajectories that impact the satellite and provide a technique for numerically integrating the navigation error function over the impact area to obtain impact probabilities. The results indicate which of the planned spacecraft trajectory correction maneuvers are most critical in terms of satellite quarantine violation.

Conflict Resolution in the Genome: How Transcription and Replication Make It Work.

PubMed

Hamperl, Stephan; Cimprich, Karlene A

2016-12-01

The complex machineries involved in replication and transcription translocate along the same DNA template, often in opposing directions and at different rates. These processes routinely interfere with each other in prokaryotes, and mounting evidence now suggests that RNA polymerase complexes also encounter replication forks in higher eukaryotes. Indeed, cells rely on numerous mechanisms to avoid, tolerate, and resolve such transcription-replication conflicts, and the absence of these mechanisms can lead to catastrophic effects on genome stability and cell viability. In this article, we review the cellular responses to transcription-replication conflicts and highlight how these inevitable encounters shape the genome and impact diverse cellular processes. Copyright © 2016 Elsevier Inc. All rights reserved.

Analytical formulation of impulsive collision avoidance dynamics

NASA Astrophysics Data System (ADS)

Bombardelli, Claudio

2014-02-01

The paper deals with the problem of impulsive collision avoidance between two colliding objects in three dimensions and assuming elliptical Keplerian orbits. Closed-form analytical expressions are provided that accurately predict the relative dynamics of the two bodies in the encounter b-plane following an impulsive delta-V manoeuvre performed by one object at a given orbit location prior to the impact and with a generic three-dimensional orientation. After verifying the accuracy of the analytical expressions for different orbital eccentricities and encounter geometries the manoeuvre direction that maximises the miss distance is obtained numerically as a function of the arc length separation between the manoeuvre point and the predicted collision point. The provided formulas can be used for high-accuracy instantaneous estimation of the outcome of a generic impulsive collision avoidance manoeuvre and its optimisation.

Vibration-translation energy transfer in anharmonic diatomic molecules. 2: The vibrational quantum number dependence

NASA Technical Reports Server (NTRS)

Mckenzie, R. L.

1975-01-01

A semiclassical model of the inelastic collision between a vibrationally excited anharmonic oscillator and a structureless atom was used to predict the variation of thermally averaged vibration-translation rate coefficients with temperature and initial-state quantum number. Multiple oscillator states were included in a numerical solution for collinear encounters. The results are compared with CO-He experimental values for both ground and excited initial states using several simplified forms of the interaction potential. The numerical model was also used as a basis for evaluating several less complete but analytic models. Two computationally simple analytic approximations were found that successfully reproduced the numerical rate coefficients for a wide range of molecular properties and collision partners. Their limitations were also identified. The relative rates of multiple-quantum transitions from excited states were evaluated for several molecular types.

On inconsistency in frictional granular systems

NASA Astrophysics Data System (ADS)

Alart, Pierre; Renouf, Mathieu

2018-04-01

Numerical simulation of granular systems is often based on a discrete element method. The nonsmooth contact dynamics approach can be used to solve a broad range of granular problems, especially involving rigid bodies. However, difficulties could be encountered and hamper successful completion of some simulations. The slow convergence of the nonsmooth solver may sometimes be attributed to an ill-conditioned system, but the convergence may also fail. The prime aim of the present study was to identify situations that hamper the consistency of the mathematical problem to solve. Some simple granular systems were investigated in detail while reviewing and applying the related theoretical results. A practical alternative is briefly analyzed and tested.

Self-reporting and measurement of body mass index in adolescents: refusals and validity, and the possible role of socioeconomic and health-related factors.

PubMed

Chau, Nearkasen; Chau, Kénora; Mayet, Aurélie; Baumann, Michèle; Legleye, Stéphane; Falissard, Bruno

2013-09-08

Body mass index assessment using self-reported height and weight (BMIsr) can encounter refusals and under/over-reporting while for assessment with measured data (BMIm) refusals can be more frequent. This could relate to socioeconomic and health-related factors. We explored these issues by investigating numerous potential factors: gender, age, family structure, father's occupation, income, physical/sports activity, subjective weight perception, school performance, unhealthy behaviours, physical/psychological health, social relationships, living environment, having sustained violence, sexual abuse, and involvement in violence. The sample included 1559 adolescents from middle schools in north-eastern France. They completed a questionnaire including socioeconomic and health-related data, self-reported height/weight, measured height/weight, and weight perception (participation rate 94%). Data were analysed using logistic regression models. BMIsr encountered under-reporting (with change in BMI category, 11.8%), over-reporting (6.0%), and reporting refusals (3.6%). BMIm encountered more numerous refusals (7.9%). Reporting refusal was related to living with a single parent, low school performance, lack of physical/sports activity, sustained violence, poor psychological health, and poor social relationships (gender/age-adjusted odds ratios 1.95 to 2.91). Further to these factors, measurement refusal was related to older age, having divorced/separated parents, a father being a manual worker/inactive, insufficient family income, tobacco/cannabis use, involvement in violence, poor physical health, and poor living environment (1.30 to 3.68). Under-reporting was related to male gender, involvement in violence, poor psychological health, and overweight/obesity (as assessed with BMIm) (1.52 to 11). Over-reporting was related to male gender, younger age, alcohol consumption, and underweight (1.30 to 5.35). Weight perception was linked to reporting refusals and under/over-reporting, but slightly linked to measurement refusal. The contributions of socioeconomic and health-related factors to the associations of weight perception with reporting refusal and under/over-reporting ranged from -82% to 44%. There were substantial discrepancies in the associations between socioeconomic/health-related factors and overweight/obesity assessed with BMIsr and BMIm. BMIsr and BMIm were affected by numerous biases related to vulnerability which were also obesity risk factors. BMIsr encountered under/over-reporting which were related to some socioeconomic and health-related factors, weight perception, and BMIm. BMIm was more affected by refusals than BMIsr due to socioeconomic and health-related factors. Further research is needed.

Word problems: a review of linguistic and numerical factors contributing to their difficulty

PubMed Central

Daroczy, Gabriella; Wolska, Magdalena; Meurers, Walt Detmar; Nuerk, Hans-Christoph

2015-01-01

Word problems (WPs) belong to the most difficult and complex problem types that pupils encounter during their elementary-level mathematical development. In the classroom setting, they are often viewed as merely arithmetic tasks; however, recent research shows that a number of linguistic verbal components not directly related to arithmetic contribute greatly to their difficulty. In this review, we will distinguish three components of WP difficulty: (i) the linguistic complexity of the problem text itself, (ii) the numerical complexity of the arithmetic problem, and (iii) the relation between the linguistic and numerical complexity of a problem. We will discuss the impact of each of these factors on WP difficulty and motivate the need for a high degree of control in stimuli design for experiments that manipulate WP difficulty for a given age group. PMID:25883575

Numerical modelling of the effect of dry air traces in a helium parallel plate dielectric barrier discharge

NASA Astrophysics Data System (ADS)

Lazarou, C.; Belmonte, T.; Chiper, A. S.; Georghiou, G. E.

2016-10-01

A validated numerical model developed for the study of helium barrier discharges in the presence of dry air impurities is presented in this paper. The model was used to numerically investigate the influence of air traces on the evolution of the helium dielectric barrier discharge (DBD). The level of dry air used as impurity was in the range from 0 to 1500 ppm, which corresponds to the most commonly encountered range in atmospheric pressure discharge experiments. The results presented in this study clearly show that the plasma chemistry and consequently the discharge evolution is highly affected by the concentration level of impurities in the mixture. In particular, it was observed that air traces assist the discharge ignition at low concentration levels (~55 ppm), while on the other hand, they increase the burning voltage at higher concentration levels (~1000 ppm). Furthermore, it was found that the discharge symmetry during the voltage cycle highly depends on the concentration of air. For the interpretation of the results, a detailed analysis of the processes that occur in the discharge gap is performed and the main reaction pathways of ion production are described. Thanks to this approach, useful insight into the physics behind the evolution of the discharge is obtained.

Breast-feeding perceptions, beliefs and experiences of Marshallese migrants: an exploratory study.

PubMed

Scott, Allison; Shreve, Marilou; Ayers, Britni; McElfish, Pearl Anna

2016-11-01

To determine perceptions, beliefs and experiences affecting breast-feeding in Marshallese mothers residing in Northwest Arkansas, USA. A qualitative, exploratory study using a brief survey and focus groups. Marshallese women, 18 years or older who had a child under 7 years of age, were included in the study. Community-based organization in Northwest Arkansas. The majority of mothers viewed breast milk as superior to formula, but had concerns about adequate milk supply and the nutritional value of their milk. The primary barriers to exclusive breast-feeding in the USA included public shaming (both verbal and non-verbal), perceived milk production and quality, and maternal employment. These barriers are not reported in the Marshall Islands and are encountered only after moving to the USA. Breast-feeding mothers rely heavily on familial support, especially the eldest female, who may not reside in the USA. The influence of institutions, including the Special Supplemental Nutrition Program for Women, Infants, and Children, is strong and may negatively affect breast-feeding. Despite the belief that breast milk is the healthiest option, breast-feeding among Marshallese mothers is challenged by numerous barriers they encounter as they assimilate to US cultural norms. The barriers and challenges, along with the strong desire to assimilate to US culture, impact Marshallese mothers' perceptions, beliefs and experiences with breast-feeding.

Rank One Strange Attractors in Periodically Kicked Predator-Prey System with Time-Delay

NASA Astrophysics Data System (ADS)

Yang, Wenjie; Lin, Yiping; Dai, Yunxian; Zhao, Huitao

2016-06-01

This paper is devoted to the study of the problem of rank one strange attractor in a periodically kicked predator-prey system with time-delay. Our discussion is based on the theory of rank one maps formulated by Wang and Young. Firstly, we develop the rank one chaotic theory to delayed systems. It is shown that strange attractors occur when the delayed system undergoes a Hopf bifurcation and encounters an external periodic force. Then we use the theory to the periodically kicked predator-prey system with delay, deriving the conditions for Hopf bifurcation and rank one chaos along with the results of numerical simulations.

On the Analytical and Numerical Properties of the Truncated Laplace Transform

DTIC Science & Technology

2014-05-01

classical study of the truncated Fourier trans- form. The resulting algorithms are applicable to all environments likely to be encountered in applications...other words, (((La,b)∗ ◦ La,b) (un)) (t) = ∫ b a 1 t+ s un(s)ds = α 2 nun (t). (2.69) Observation 2.22. Similarly, La,b ◦ (La,b)∗ of a function g ∈ L2(0...3.20)) are even and odd functions in the regular sense: Un(s) = (Cγ(un)) (s) = (−1) nUn (−s). (3.25) In particular, at the point s = 0, we have: U2j+1(0

Mass transfer in thin films under counter-current gas: experiments and numerical study

NASA Astrophysics Data System (ADS)

Lucquiaud, Mathieu; Lavalle, Gianluca; Schmidt, Patrick; Ausner, Ilja; Wehrli, Marc; O Naraigh, Lennon; Valluri, Prashant

2016-11-01

Mass transfer in liquid-gas stratified flows is strongly affected by the waviness of the interface. For reactive flows, the chemical reactions occurring at the liquid-gas interface also influence the mass transfer rate. This is encountered in several technological applications, such as absorption units for carbon capture. We investigate the absorption rate of carbon dioxide in a liquid solution. The experimental set-up consists of a vertical channel where a falling film is sheared by a counter-current gas flow. We measure the absorption occurring at different flow conditions, by changing the liquid solution, the liquid flow rate and the gas composition. With the aim to support the experimental results with numerical simulations, we implement in our level-set flow solver a novel module for mass transfer taking into account a variant of the ghost-fluid formalism. We firstly validate the pure mass transfer case with and without hydrodynamics by comparing the species concentration in the bulk flow to the analytical solution. In a final stage, we analyse the absorption rate in reactive flows, and try to reproduce the experimental results by means of numerical simulations to explore the active role of the waves at the interface.

Food supply mechanisms for cold-water corals along a continental shelf edge

NASA Astrophysics Data System (ADS)

Thiem, Øyvind; Ravagnan, Elisa; Fosså, Jan Helge; Berntsen, Jarle

2006-05-01

In recent years it has been documented that deep-water coral reefs of the species Lophelia pertusa are a major benthic habitat in Norwegian waters. However, basic information about the biology and ecology of this species is still unknown. Lophelia live and thrive under special environmental conditions of which factors such as temperature, water depth, water movement and food supply are important. The present work explores the hypothesis that Lophelia forms reefs in places where the encounter rate of food particles is sufficiently high and stable over long periods of time for continuous growth. This is done by relating the distribution of reefs with the results of numerical ocean modelling. Numerical simulations have been performed with an idealized bottom topography similar to what is found outside parts of the Norwegian coast. In the simulations the model is first forced with an along slope jet and then with an idealized atmospheric low pressure. The model results show that the encounter rates between the particles and the water layer near the seabed are particularly high close to the shelf break. This may indicate that many Lophelia reefs are located along the shelf edges because the supply of food is particularly good in these areas. A sensitivity study of the particle supply in the area close to the seabed for increasing latitude has also been done. This shows that the Ekman transport in the benthic layer tends to create a steady supply of food for benthic organisms near the shelf edge away from the equator.

Stratospheric turbulence measurements and models for aerospace plane design

NASA Technical Reports Server (NTRS)

Ehernberger, L. J.

1992-01-01

Progress in computational atmospheric dynamics is exhibiting the ability of numerical simulation to describe instability processes associated with turbulence observed at altitudes between 15 and 25 km in the lower stratosphere. As these numerical simulation tools mature, they can be used to extend estimates of atmospheric perturbations from the present gust database for airplane design at altitudes below 15 km to altitudes between 25 and 50 km where aerospace plane operation would be at hypersonic speeds. The amount of available gust data and number of temperature perturbation observations are limited at altitudes between 15 and 25 km. On the other hand, in-situ gust data at higher altitudes are virtually nonexistent. The uncertain potential for future airbreathing hypersonic flight research vehicles to encounter strong turbulence at higher altitudes could penalize the design of these vehicles by undue cost or limitations on performance. Because the atmospheric structure changes markedly with altitude, direct extrapolation of gust magnitudes and encounter probabilities to the higher flight altitudes is not advisable. This paper presents a brief review of turbulence characteristics observed in the lower stratosphere and highlights the progress of computational atmospheric dynamics that may be used to estimate the severity of atmospheric transients at higher altitudes.

My Experience as a Foot and Ankle Trauma Surgeon in Montreal, Canada: What's Not in the Books.

PubMed

Leduc, Stéphane; Nault, Marie-Lyne; Rouleau, Dominique M; Hebert-Davies, Jonah

2016-06-01

Foot and ankle fractures are sometimes seen as routine and easy to treat. However, many fractures vary from typical patterns and require more complex management. Obtaining good outcomes in these situations can be challenging. Often, the difference between average and good results has to do with preoperative planning and good surgical technique. This article outlines numerous techniques and tricks that are not always mentioned in classic textbooks. It focuses on ankle, talus, calcaneus, and midfoot fractures, and discusses numerous techniques and aids to avoid potential problems that may be encountered intraoperatively. Copyright © 2016 Elsevier Inc. All rights reserved.

Fluidization of spherocylindrical particles

NASA Astrophysics Data System (ADS)

Mahajan, Vinay V.; Nijssen, Tim M. J.; Fitzgerald, Barry W.; Hofman, Jeroen; Kuipers, Hans; Padding, Johan T.

2017-06-01

Multiphase (gas-solid) flows are encountered in numerous industrial applications such as pharmaceutical, food, agricultural processing and energy generation. A coupled computational fluid dynamics (CFD) and discrete element method (DEM) approach is a popular way to study such flows at a particle scale. However, most of these studies deal with spherical particles while in reality, the particles are rarely spherical. The particle shape can have significant effect on hydrodynamics in a fluidized bed. Moreover, most studies in literature use inaccurate drag laws because accurate laws are not readily available. The drag force acting on a non-spherical particle can vary considerably with particle shape, orientation with the flow, Reynolds number and packing fraction. In this work, the CFD-DEM approach is extended to model a laboratory scale fluidized bed of spherocylinder (rod-like) particles. These rod-like particles can be classified as Geldart D particles and have an aspect ratio of 4. Experiments are performed to study the particle flow behavior in a quasi-2D fluidized bed. Numerically obtained results for pressure drop and bed height are compared with experiments. The capability of CFD-DEM approach to efficiently describe the global bed dynamics for fluidized bed of rod-like particles is demonstrated.

Direct numerical simulation of a compressible boundary-layer flow past an isolated three-dimensional hump in a high-speed subsonic regime

NASA Astrophysics Data System (ADS)

De Grazia, D.; Moxey, D.; Sherwin, S. J.; Kravtsova, M. A.; Ruban, A. I.

2018-02-01

In this paper we study the boundary-layer separation produced in a high-speed subsonic boundary layer by a small wall roughness. Specifically, we present a direct numerical simulation (DNS) of a two-dimensional boundary-layer flow over a flat plate encountering a three-dimensional Gaussian-shaped hump. This work was motivated by the lack of DNS data of boundary-layer flows past roughness elements in a similar regime which is typical of civil aviation. The Mach and Reynolds numbers are chosen to be relevant for aeronautical applications when considering small imperfections at the leading edge of wings. We analyze different heights of the hump: The smaller heights result in a weakly nonlinear regime, while the larger result in a fully nonlinear regime with an increasing laminar separation bubble arising downstream of the roughness element and the formation of a pair of streamwise counterrotating vortices which appear to support themselves.

Surface plasmon transmission through discontinuous conducting surfaces: Plasmon amplitude modulation by grazing scattered fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayoral-Astorga, L. A.; Gaspar-Armenta, J. A.; Ramos-Mendieta, F.

2016-04-15

We have studied numerically the diffraction of a surface plasmon polariton (SPP) when it encounters a wide multi-wavelength slit in conducting films. As a jump process a SPP is excited beyond the slit by wave scattering at the second slit edge. The exciting radiation is produced when the incident SPP collapses at the first slit edge. We have found that the transmitted SPP supports inherent and unavoidable interference with grazing scattered radiation; the spatial modulation extends to the fields in the diffraction region where a series of low intensity spots arises. We demonstrate that the SPP generated on the secondmore » slab depends on the frequency but not on the wave vector of the collapsed SPP; a SPP is transmitted even when the two metals forming the slit are different. The numerical results were obtained using the Finite Difference Time Domain (FDTD) method with a grid size λ/100.« less

Recent examples of mesoscale numerical forecasts of severe weather events along the east coast

NASA Technical Reports Server (NTRS)

Kocin, P. J.; Uccellini, L. W.; Zack, J. W.; Kaplan, M. L.

1984-01-01

Mesoscale numerical forecasts utilizing the Mesoscale Atmospheric Simulation System (MASS) are documented for two East Coast severe weather events. The two events are the thunderstorm and heavy snow bursts in the Washington, D.C. - Baltimore, MD region on 8 March 1984 and the devastating tornado outbreak across North and South Carolina on 28 March 1984. The forecasts are presented to demonstrate the ability of the model to simulate dynamical interactions and diabatic processes and to note some of the problems encountered when using mesoscale models for day-to-day forecasting.

Analysis of a two-dimensional type 6 shock-interference pattern using a perfect-gas code and a real-gas code

NASA Technical Reports Server (NTRS)

Bertin, J. J.; Graumann, B. W.

1973-01-01

Numerical codes were developed to calculate the two dimensional flow field which results when supersonic flow encounters double wedge configurations whose angles are such that a type 4 pattern occurs. The flow field model included the shock interaction phenomena for a delta wing orbiter. Two numerical codes were developed, one which used the perfect gas relations and a second which incorporated a Mollier table to define equilibrium air properties. The two codes were used to generate theoretical surface pressure and heat transfer distributions for velocities from 3,821 feet per second to an entry condition of 25,000 feet per second.

Numerical Investigation of 'Transonic Resonance' with a Convergent-Divergent Nozzle

NASA Technical Reports Server (NTRS)

Loh, Ching Y.; Zaman, K. B. M. Q.

2002-01-01

At pressure ratios lower than the design value, convergent-divergent (C-D) nozzles often undergo a flow resonance accompanied by the emission of acoustic tones. The phenomenon, driven by the unsteady shock within the divergent section of the nozzle, has been studied experimentally by Zaman et al. In this paper, the space-time conservation element solution element (CE/SE) method is employed to numerically investigate the phenomenon. The computations are performed for a given nozzle geometry for several different pressure ratios. Sustained 'limit cycle' oscillations are encountered in all cases. The oscillation frequencies, their variation with pressure ratio including a 'stage jump', agree well with the experimental results. The unsteady flow data confirm that stage 1 of the resonance (fundamental) involves a one-quarter standing wave while stage 2 (third harmonic) involves a three-quarter standing wave within the divergent section of the nozzle. Details of the shock motion, and the flow and near acoustic field, are documented for one case each of stages 1 and 2.

Evaluation and Sensitivity Analysis of an Ocean Model Response to Hurricane Ivan (PREPRINT)

DTIC Science & Technology

2009-05-18

analysis of upper-limb meridional overturning circulation interior ocean pathways in the tropical/subtropical Atlantic . In: Interhemispheric Water...diminishing returns are encountered when either resolution is increased. 3 1. Introduction Coupled ocean-atmosphere general circulation models have become...northwest Caribbean Sea 4 and GOM. Evaluation is difficult because ocean general circulation models incorporate a large suite of numerical algorithms

Behavioral aspects of children's sports.

PubMed

Pratt, Helen D; Patel, Dilip R; Greydanus, Donald E

2003-08-01

This article considers some of the numerous behavioral aspects that are related to children's sports. The pediatrician, during various encounters with the athlete and his or her parents in the office, or on the field, can positively influence the sport participation experience of the athlete, by screening and identifying potential problem areas as well as providing anticipatory guidance on various issues.

Continuous spectra of atomic hydrogen in a strong magnetic field

NASA Astrophysics Data System (ADS)

Zhao, L. B.; Zatsarinny, O.; Bartschat, K.

2016-09-01

We describe a theoretical method, developed in the coupled-channel formalism, to study photoionization of H atoms in a strong magnetic field of a size that is typical for magnetic white dwarfs. The coupled Schrödinger equations are solved numerically using the renormalized Numerov method proposed by Johnson [B. R. Johnson, J. Chem. Phys. 67, 4086 (1977), 10.1063/1.435384; B. R. Johnson, J. Chem. Phys. 69, 4678 (1978), 10.1063/1.436421]. The distinct advantage of this method is the fact that no overflow problems are encountered in the classically forbidden region, and hence the method exhibits excellent numerical stability. Photoionization cross sections are presented for magnetized H atoms in the ground and 2 p excited states. The calculated results are compared with those obtained by other theories. The present method is particularly useful for explaining the complex features of continuous spectra in a strong magnetic field and hence provides an efficient tool for modeling photoionization spectra observed in the atmosphere of magnetic white dwarfs.

Classical black holes: the nonlinear dynamics of curved spacetime.

PubMed

Thorne, Kip S

2012-08-03

Numerical simulations have revealed two types of physical structures, made from curved spacetime, that are attached to black holes: tendexes, which stretch or squeeze anything they encounter, and vortexes, which twist adjacent inertial frames relative to each other. When black holes collide, their tendexes and vortexes interact and oscillate (a form of nonlinear dynamics of curved spacetime). These oscillations generate gravitational waves, which can give kicks up to 4000 kilometers per second to the merged black hole. The gravitational waves encode details of the spacetime dynamics and will soon be observed and studied by the Laser Interferometer Gravitational Wave Observatory and its international partners.

Classical Black Holes: The Nonlinear Dynamics of Curved Spacetime

NASA Astrophysics Data System (ADS)

Thorne, Kip S.

2012-08-01

Numerical simulations have revealed two types of physical structures, made from curved spacetime, that are attached to black holes: tendexes, which stretch or squeeze anything they encounter, and vortexes, which twist adjacent inertial frames relative to each other. When black holes collide, their tendexes and vortexes interact and oscillate (a form of nonlinear dynamics of curved spacetime). These oscillations generate gravitational waves, which can give kicks up to 4000 kilometers per second to the merged black hole. The gravitational waves encode details of the spacetime dynamics and will soon be observed and studied by the Laser Interferometer Gravitational Wave Observatory and its international partners.

Exploring machine-learning-based control plane intrusion detection techniques in software defined optical networks

NASA Astrophysics Data System (ADS)

Zhang, Huibin; Wang, Yuqiao; Chen, Haoran; Zhao, Yongli; Zhang, Jie

2017-12-01

In software defined optical networks (SDON), the centralized control plane may encounter numerous intrusion threatens which compromise the security level of provisioned services. In this paper, the issue of control plane security is studied and two machine-learning-based control plane intrusion detection techniques are proposed for SDON with properly selected features such as bandwidth, route length, etc. We validate the feasibility and efficiency of the proposed techniques by simulations. Results show an accuracy of 83% for intrusion detection can be achieved with the proposed machine-learning-based control plane intrusion detection techniques.

A case study of multi-seam coal mine entry stability analysis with strength reduction method

PubMed Central

Tulu, Ihsan Berk; Esterhuizen, Gabriel S; Klemetti, Ted; Murphy, Michael M.; Sumner, James; Sloan, Michael

2017-01-01

In this paper, the advantage of using numerical models with the strength reduction method (SRM) to evaluate entry stability in complex multiple-seam conditions is demonstrated. A coal mine under variable topography from the Central Appalachian region is used as a case study. At this mine, unexpected roof conditions were encountered during development below previously mined panels. Stress mapping and observation of ground conditions were used to quantify the success of entry support systems in three room-and-pillar panels. Numerical model analyses were initially conducted to estimate the stresses induced by the multiple-seam mining at the locations of the affected entries. The SRM was used to quantify the stability factor of the supported roof of the entries at selected locations. The SRM-calculated stability factors were compared with observations made during the site visits, and the results demonstrate that the SRM adequately identifies the unexpected roof conditions in this complex case. It is concluded that the SRM can be used to effectively evaluate the likely success of roof supports and the stability condition of entries in coal mines. PMID:28239503

A case study of multi-seam coal mine entry stability analysis with strength reduction method.

PubMed

Tulu, Ihsan Berk; Esterhuizen, Gabriel S; Klemetti, Ted; Murphy, Michael M; Sumner, James; Sloan, Michael

2016-03-01

In this paper, the advantage of using numerical models with the strength reduction method (SRM) to evaluate entry stability in complex multiple-seam conditions is demonstrated. A coal mine under variable topography from the Central Appalachian region is used as a case study. At this mine, unexpected roof conditions were encountered during development below previously mined panels. Stress mapping and observation of ground conditions were used to quantify the success of entry support systems in three room-and-pillar panels. Numerical model analyses were initially conducted to estimate the stresses induced by the multiple-seam mining at the locations of the affected entries. The SRM was used to quantify the stability factor of the supported roof of the entries at selected locations. The SRM-calculated stability factors were compared with observations made during the site visits, and the results demonstrate that the SRM adequately identifies the unexpected roof conditions in this complex case. It is concluded that the SRM can be used to effectively evaluate the likely success of roof supports and the stability condition of entries in coal mines.

The varieties of symmetric stellar rings and radial caustics in galaxy disks

NASA Technical Reports Server (NTRS)

Struck-Marcell, Curtis; Lotan, Pnina

1990-01-01

Numerical, restricted three-body and analytic calculations are used to study the formation and propagation of cylindrically symmetric stellar ring waves in galaxy disks. It is shown that such waves can evolve in a variety of ways, depending on the amplitude of the perturbation and the potential of the target galaxy. Rings can thicken as they propagate outward, remain at a nearly constant width, or be pinched off at large radii. Multiple, closely spaced rings can result from a low-amplitude collision, while an outer ring can appear well-separated from overlapping inner rings or an apparent lens structure in halo-dominated potentials. All the single-encounter rings consist of paired fold caustics. The simple, impulsive, kinematic oscillation equations appear to provide a remarkably accurate model of the numerical simulations. Simple analytic approximations to these equations permit very good estimates of oscillation periods and amplitudes, the evolution of ring widths, and ring birth and propagation characteristics.

Close encounters for the first time: Helicase interactions with DNA damage.

PubMed

Khan, Irfan; Sommers, Joshua A; Brosh, Robert M

2015-09-01

DNA helicases are molecular motors that harness the energy of nucleoside triphosphate hydrolysis to unwinding structured DNA molecules that must be resolved during cellular replication, DNA repair, recombination, and transcription. In vivo, DNA helicases are expected to encounter a wide spectrum of covalent DNA modifications to the sugar phosphate backbone or the nitrogenous bases; these modifications can be induced by endogenous biochemical processes or exposure to environmental agents. The frequency of lesion abundance can vary depending on the lesion type. Certain adducts such as oxidative base modifications can be quite numerous, and their effects can be helix-distorting or subtle perturbations to DNA structure. Helicase encounters with specific DNA lesions and more novel forms of DNA damage will be discussed. We will also review the battery of assays that have been used to characterize helicase-catalyzed unwinding of damaged DNA substrates. Characterization of the effects of specific DNA adducts on unwinding by various DNA repair and replication helicases has proven to be insightful for understanding mechanistic and biological aspects of helicase function in cellular DNA metabolism. Published by Elsevier B.V.

Global migration and health: ecofeminist perspectives.

PubMed

McGuire, S

1998-12-01

Global migration is occurring at an unprecedented rate. The phenomenon of migration is complex and poorly understood by most people in countries who host immigrants. People migrate for numerous reasons related to social, economic, political, cultural, and physical environmental conditions formed by historical antecedents. Migrating people, especially vulnerable women and children, are exposed to numerous health hazards, a situation calling for a response from nursing. To respond effectively nursing needs knowledge development of global migration and health that includes the precursors to migration in addition to the postmigration experience where nurses encounter immigrants. Ecofeminist perspectives allowing for reflection on historical determinants and interlocking socioeconomic, political, and environmental conditions are used as a prism to examine global migration and health.

Analytical and numerical studies of photo-injected charge transport in molecularly-doped polymers

NASA Astrophysics Data System (ADS)

Roy Chowdhury, Amrita

The mobility of photo-injected charge carriers in molecularly-doped polymers (MDPs) exhibits a commonly observed, and nearly universal Poole-Frenkel field dependence, mu exp√(beta0E), that has been shown to arise from the correlated Gaussian energy distribution of transport sites encountered by charges undergoing hopping transport through the material. Analytical and numerical studies of photo-injected charge transport in these materials are presented here with an attempt to understand how specific features of the various models developed to describe these systems depend on the microscopic parameters that define them. Specifically, previously published time-of-flight mobility data for the molecularly doped polymer 30% DEH:PC (polycarbonate doped with 30 wt.% aromatic hydrazone DEH) is compared with direct analytical and numerical predictions of five disorder-based models, the Gaussian disorder model (GDM) of Bassler, and four correlated disorder models introduced by Novikov, et al., and by Parris, et al. In these numerical studies, disorder parameters describing each model were varied from reasonable starting conditions, in order to give the best overall fit. The uncorrelated GDM describes the Poole-Frenkel field dependence of the mobility only at very high fields, but fails for fields lower than about 64 V/mum. The correlated disorder models with small amounts of geometrical disorder do a good over-all job of reproducing a robust Poole-Frenkel field dependence, with correlated disorder theories that employ polaron transition rates showing qualitatively better agreement with experiment than those that employ Miller-Abrahams rates. In a separate study, the heuristic treatment of spatial or geometric disorder incorporated in existing theories is critiqued, and a randomly-diluted lattice gas model is developed to describe the spatial disorder of the transport sites in a more realistic way.

Quantitative Rainbow Schlieren Deflectometry as a Temperature Diagnostic for Spherical Flames

NASA Technical Reports Server (NTRS)

Feikema, Douglas A.

2004-01-01

Numerical analysis and experimental results are presented to define a method for quantitatively measuring the temperature distribution of a spherical diffusion flame using Rainbow Schlieren Deflectometry in microgravity. First, a numerical analysis is completed to show the method can suitably determine temperature in the presence of spatially varying species composition. Also, a numerical forward-backward inversion calculation is presented to illustrate the types of calculations and deflections to be encountered. Lastly, a normal gravity demonstration of temperature measurement in an axisymmetric laminar, diffusion flame using Rainbow Schlieren deflectometry is presented. The method employed in this paper illustrates the necessary steps for the preliminary design of a Schlieren system. The largest deflections for the normal gravity flame considered in this paper are 7.4 x 10(-4) radians which can be accurately measured with 2 meter focal length collimating and decollimating optics. The experimental uncertainty of deflection is less than 5 x 10(-5) radians.

Quarantine constraints as applied to satellites.

NASA Technical Reports Server (NTRS)

Hoffman, A. R.; Stavro, W.; Gonzalez, C.

1973-01-01

Plans for unmanned missions to planets beyond Mars in the 1970s include satellite encounters. Recently published observations of data for Titan, a satellite of Saturn, indicate that conditions may be hospitable for the growth of microorganisms. Therefore, the problem of satisfying possible quarantine constraints for outer planet satellites was investigated. This involved determining the probability of impacting a satellite of Jupiter or Saturn by a spacecraft for a planned satellite encounter during an outer planet mission. Mathematical procedures were formulated which (1) determine the areas in the aim-plane that would result in trajectories that impact the satellite and (2) provide a technique for numerically integrating the navigation error function over the impact area to obtain impact probabilities. The results indicate which of the planned spacecraft trajectory correction maneuvers are most critical in terms of satellite quarantine violation.

Effects of the heat transfer fluid velocity on the storage characteristics of a cylindrical latent heat energy storage system: a numerical study

NASA Astrophysics Data System (ADS)

Ogoh, Wilson; Groulx, Dominic

2012-03-01

A numerical study of the effects of the thermal fluid velocity on the storage characteristics of a cylindrical latent heat energy storage system (LHESS) was conducted. Due to the low thermal conductivity of phase change materials (PCMs) used in LHESS, fins were added to the system to increase the rate of heat transfer and charging. Finite elements were used to implement the developed numerical method needed to study and solve for the phase change heat transfer (melting of PCM) encountered in a LHESS during charging. The effective heat capacity method was applied in order to account for the large amount of latent energy stored during melting of the PCM and the moving interface between the solid and liquid phases. The effects of the heat transfer fluid (HTF) velocity on the melting rate of the PCM were studied for configurations having between 0 and 18 fins. Results show that the overall heat transfer rate to the PCM increases with an increase in the HTF velocity. However, the effect of the HTF velocity was observed to be small in configurations having very few fins, owing to the large residual thermal resistance offered by the PCM. However, the effect of the HTF velocity becomes more pronounced with addition of fins; since the thermal resistance on the PCM side of the LHESS is significantly reduce by the large number of fins in the system.

Chiropractic Observation and Analysis Study (COAST): providing an understanding of current chiropractic practice.

PubMed

French, Simon D; Charity, Melanie J; Forsdike, Kirsty; Gunn, Jane M; Polus, Barbara I; Walker, Bruce F; Chondros, Patty; Britt, Helena C

2013-11-18

COAST (Chiropractic Observation and Analysis Study) aimed to describe the clinical practices of chiropractors in Victoria, Australia. Cross-sectional study using the BEACH (Bettering the Evaluation and Care of Health) methods for general practice. 180 chiropractors in active clinical practice in Victoria were randomly selected from the list of 1298 chiropractors registered on Chiropractors Registration Board of Victoria. Twenty-four chiropractors were ineligible, 72 agreed to participate, and 52 completed the study. Each participating chiropractor documented encounters with up to 100 consecutive patients. For each chiropractor-patient encounter, information collected included patient health profile, patient reasons for encounter, problems and diagnoses, and chiropractic care. Data were collected on 4464 chiropractor-patient encounters from 52 chiropractors between 11 December 2010 and 28 September 2012. In most (71%) encounters, patients were aged 25-64 years; 1% of encounters were with infants (age < 1 year; 95% CI, 0.3%-3.2%). Musculoskeletal reasons for encounter were described by patients at a rate of 60 per 100 encounters (95% CI, 54-67 encounters) and maintenance and wellness or check-up reasons were described at a rate of 39 per 100 encounters (95% CI, 33-47 encounters). Back problems were managed at a rate of 62 per 100 encounters (95% CI, 55-71 encounters). The most frequent care provided by the chiropractors was spinal manipulative therapy and massage. A range of conditions are managed by chiropractors in Victoria, Australia, but most commonly these conditions are musculoskeletal-related. These results can be used by stakeholders of the chiropractic profession in workforce development, education and health care policy.

CFD - Mature Technology?

NASA Technical Reports Server (NTRS)

Kwak, Dochan

2005-01-01

Over the past 30 years, numerical methods and simulation tools for fluid dynamic problems have advanced as a new discipline, namely, computational fluid dynamics (CFD). Although a wide spectrum of flow regimes are encountered in many areas of science and engineering, simulation of compressible flow has been the major driver for developing computational algorithms and tools. This is probably due to a large demand for predicting the aerodynamic performance characteristics of flight vehicles, such as commercial, military, and space vehicles. As flow analysis is required to be more accurate and computationally efficient for both commercial and mission-oriented applications (such as those encountered in meteorology, aerospace vehicle development, general fluid engineering and biofluid analysis) CFD tools for engineering become increasingly important for predicting safety, performance and cost. This paper presents the author's perspective on the maturity of CFD, especially from an aerospace engineering point of view.

A simultaneous estimation of the mass of Mars and its natural satellites, Phobos and Deimos, from the orbital perturbations on the Mariner 9, Viking 1, and Viking 2 orbiters

NASA Technical Reports Server (NTRS)

Lemoine, F. G.; Smith, D. E.; Fricke, S. K.; Mccarthy, J. J.

1993-01-01

The natural satellites of Mars, Phobos and Deimos, caused perturbations on the orbits of the Mariner 9, and the Viking spacecraft that were used to estimate the satellite masses. The Viking spacecraft were specifically targeted to make close flybys (within a few hundred kilometers) of Phobos in February 1977 and of Deimos in October 1977. These close encounters were used to estimate the moon's gravitational constant, GM (the universal constant of gravitation multiplied by the satellite mass). However, the Viking and Mariner 9 spacecraft made numerous flybys of Phobos and Deimos at distances of a few thousand kilometers. The tracking data from these more 'distant' encounters were processed to estimate the masses of Mars, Phobos, and Deimos.

Graphene Nano-Composites for Hypervelocity Impact Applications

NASA Astrophysics Data System (ADS)

Manasrah, Alharith

The Low Earth Orbit (LEO) is a harsh environment cluttered with natural meteoroids and man-made debris, which can travel at velocities approaching 15 km/s. Most space activities within the LEO will encounter this environment. Thus, the spacecraft and its hardware must be designed to survive debris impact. This research introduces new procedures to produce a nano-composite material with mortar-brick nano-structure inspired from nacre. Nacre-like composites were successfully manufactured, based on three host polymers, with a wide range of graphene concentrations. The manufactured exfoliated graphene nano-platelet, embedded in a host polymer, provided good potential for enhancement of the hypervelocity impact (HVI) shield resistance. The nano-composites are suggested for use as a coating. Moreover, explicit dynamic finite element studies were conducted for further investigation of the hypervelocity impact of the graphene-based coatings in order to understand the effect of the coating on the crater formation and the exit velocity. This dissertation presents the results of the characterization and numerical sensitivity study of the developed material parameters. The numerical simulations were performed by implementing Autodyn smooth particle hydrodynamics. This study provides innovative, low-weight shielding enhancements for spacecraft, as well as other promising applications for the manufactured nano-composites.

Numerical Investigation of Synthetic-jet based Flow Control on Vertical-axis Wind Turbine Blades

NASA Astrophysics Data System (ADS)

Menon, Ashwin; Tran, Steven; Sahni, Onkar

2013-11-01

Vertical-axis wind turbines encounter large unsteady aerodynamic loads in a sustained fashion due to the continuously varying angle of attack that is experienced by turbine blades during each revolution. Moreover, the detachment of the leading edge vortex at high angles of attack leads to sudden change in aerodynamic loads that result in structural vibrations and fatigue, and possibly failure. This numerical study focuses on using synthetic-jet based fluidic actuation to reduce the unsteady loading on VAWT blades. In the simulations, the jets are placed at the dominant separation location that is observed in the baseline case. We consider different tip-speed ratios, O(2-5), and we also study the effect of blowing ratio (to be in O(0.5-1.5)) and reduced frequency, i.e., ratio of jet frequency to flow frequency (to be in O(5-15)). For all cases, unsteady Reynolds-averaged Navier-Stokes simulations are carried out by using the Spallart-Allamaras turbulence model, where stabilized finite element method is employed for spatial discretization along with an implicit time-integration scheme.

Facilitative Dimensions in Interpersonal Relations: Verifying the Theoretical Assumptions of Carl Rogers in School, Family Education, Client-Centered Therapy, and Encounter Groups

ERIC Educational Resources Information Center

Tausch, Reinhard

1978-01-01

Summarized numerous different projects which investigated assumptions made by Carol Rogers about the necessary and sufficient conditions for significant positive change in person-to-person contact. Findings agree with Rogers' about the importance of empathy, genuineness, and respect. Presented at the Thirtieth Congress of Deutsch Gesell Schaft for…

What Is "Typical" for Different Kinds of Data? Examples from the Melbourne Cup

ERIC Educational Resources Information Center

Watson, Jane

2014-01-01

There are five words that are critical to an appreciation of what is "typical" in data sets that students encounter across the middle school years. The first three words--mean, median and mode--are nouns that define measures of typicality in data sets. The next two words--categorical and numerical--are adjectives that describe the types…

The Relationship between Using the Scrambled Words Reading Strategy and the Vocabulary of Struggling Readers

ERIC Educational Resources Information Center

Ward Bowens, Saundra

2013-01-01

About 1 million children encounter reading problems during the first 3 years in school. Numerous teaching methods and various strategies are employed to teach children how to read. Reading provides the foundation for all school-based learning. When one of these foundation skills is missing or deficient, the child may have difficulty learning to…

Accurate solutions for transonic viscous flow over finite wings

NASA Technical Reports Server (NTRS)

Vatsa, V. N.

1986-01-01

An explicit multistage Runge-Kutta type time-stepping scheme is used for solving the three-dimensional, compressible, thin-layer Navier-Stokes equations. A finite-volume formulation is employed to facilitate treatment of complex grid topologies encountered in three-dimensional calculations. Convergence to steady state is expedited through usage of acceleration techniques. Further numerical efficiency is achieved through vectorization of the computer code. The accuracy of the overall scheme is evaluated by comparing the computed solutions with the experimental data for a finite wing under different test conditions in the transonic regime. A grid refinement study ir conducted to estimate the grid requirements for adequate resolution of salient features of such flows.

Shoemaker-Levy 9 and the tidal disruption of comets

NASA Technical Reports Server (NTRS)

Benz, W.; Asphaug, E.

1994-01-01

The break-up of Periodic Comet Shoemaker-Levy 9 into multiple pieces following its grazing encounter with Jupiter in July 1992 can be used to study tidally-induced fracture in comets. This spectacular event allows us not only to set limits on the size, strength and density of Shoemaker-Levy 9 itself, but provides invaluable guidance to numerical modeling of such encounters. In an extensive treatment of tidal breakup which assumed self-gravitating, homogeneous, perfectly elastic bodies, Dobrovolskis derived simple analytical expressions for the tidally-induced surface and central stresses. Both can be cast in such a way that Poisson's ratio is the only material dependent constant entering these expressions. Whether both surface and central failure must be initiated as a criterion for breakup, or either one of them is sufficient, remains a subject of disagreement. To resolve this debate, we model the details of cometary breakup using a three-dimensional Smooth Particle Hydrodynamics (SPH) code modified to simulate fracture in small solid objects. At lower stresses associated with brittle failure, we use a rate-dependent strength based on the nucleation of incipient flaws whose number density is given by a Weibull distribution.

A hybrid structured-unstructured grid method for unsteady turbomachinery flow computations

NASA Technical Reports Server (NTRS)

Mathur, Sanjay R.; Madavan, Nateri K.; Rajagopalan, R. G.

1993-01-01

A hybrid grid technique for the solution of 2D, unsteady flows is developed. This technique is capable of handling complex, multiple component geometries in relative motion, such as those encountered in turbomachinery. The numerical approach utilizes a mixed structured-unstructured zonal grid topology along with modeling equations and solution methods that are most appropriate in the individual domains, therefore combining the advantages of both structured and unstructured grid techniques.

Diagnostic imaging of infertility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winfield, A.C.; Wentz, A.C.

1987-01-01

This text presents a review of all the imaging modalities available in the diagnosis of infertility. This book integrates the perspectives of experts in ob/gyn, radiology, reproductive endocrinology, and urology. It's a one-of-a-kind ''how to'' guide to hysterosalpinography and infertility evaluation, providing complete clinical information on the techniques, pitfalls, problems encountered and differential diagnosis. Detailed descriptions accompany numerous high-quality illustrations to help correlate findings and give meaning to the radiographic and ultrasound images.

Structural response to discrete and continuous gusts of an airplane having wing bending flexibility and a correlation of calculated and flight results

NASA Technical Reports Server (NTRS)

Houbolt, John C; Kordes, Eldon E

1954-01-01

An analysis is made of the structural response to gusts of an airplane having the degrees of freedom of vertical motion and wing bending flexibility and basic parameters are established. A convenient and accurate numerical solution of the response equations is developed for the case of discrete-gust encounter, an exact solution is made for the simpler case of continuous-sinusoidal-gust encounter, and the procedure is outlined for treating the more realistic condition of continuous random atmospheric turbulence, based on the methods of generalized harmonic analysis. Correlation studies between flight and calculated results are then given to evaluate the influence of wing bending flexibility on the structural response to gusts of two twin-engine transports and one four-engine bomber. It is shown that calculated results obtained by means of a discrete-gust approach reveal the general nature of the flexibility effects and lead to qualitative correlation with flight results. In contrast, calculations by means of the continuous-turbulence approach show good quantitative correlation with flight results and indicate a much greater degree of resolution of the flexibility effects.

Ordered LOGIT Model approach for the determination of financial distress.

PubMed

Kinay, B

2010-01-01

Nowadays, as a result of the global competition encountered, numerous companies come up against financial distresses. To predict and take proactive approaches for those problems is quite important. Thus, the prediction of crisis and financial distress is essential in terms of revealing the financial condition of companies. In this study, financial ratios relating to 156 industrial firms that are quoted in the Istanbul Stock Exchange are used and probabilities of financial distress are predicted by means of an ordered logit regression model. By means of Altman's Z Score, the dependent variable is composed by scaling the level of risk. Thus, a model that can compose an early warning system and predict financial distress is proposed.

The Sun was Not Born in M67

NASA Astrophysics Data System (ADS)

Pichardo, Bárbara; Moreno, Edmundo; Allen, Christine; Bedin, Luigi R.; Bellini, Andrea; Pasquini, Luca

2012-03-01

Using the most recent proper-motion determination of the old, solar-metallicity, Galactic open cluster M67 in orbital computations in a non-axisymmetric model of the Milky Way, including a bar and three-dimensional spiral arms, we explore the possibility that the Sun once belonged to this cluster. We have performed Monte Carlo numerical simulations to generate the present-day orbital conditions of the Sun and M67, and all the parameters in the Galactic model. We compute 3.5 × 105 pairs of orbits Sun-M67 looking for close encounters in the past with a minimum distance approach within the tidal radius of M67. In these encounters we find that the relative velocity between the Sun and M67 is larger than 20 km s-1. If the Sun had been ejected from M67 with this high velocity by means of a three-body encounter, this interaction would have either destroyed an initial circumstellar disk around the Sun or dispersed its already formed planets. We also find a very low probability, much lower than 10-7, that the Sun was ejected from M67 by an encounter of this cluster with a giant molecular cloud. This study also excludes the possibility that the Sun and M67 were born in the same molecular cloud. Our dynamical results convincingly demonstrate that M67 could not have been the birth cluster of our solar system. This work relies partly on observations of the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are The Ohio State University; The University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota, and University of Virginia.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esfahani, M. Nasr; Yilmaz, M.; Sonne, M. R.

The trend towards nanomechanical resonator sensors with increasing sensitivity raises the need to address challenges encountered in the modeling of their mechanical behavior. Selecting the best approach in mechanical response modeling amongst the various potential computational solid mechanics methods is subject to controversy. A guideline for the selection of the appropriate approach for a specific set of geometry and mechanical properties is needed. In this study, geometrical limitations in frequency response modeling of flexural nanomechanical resonators are investigated. Deviation of Euler and Timoshenko beam theories from numerical techniques including finite element modeling and Surface Cauchy-Born technique are studied. The resultsmore » provide a limit beyond which surface energy contribution dominates the mechanical behavior. Using the Surface Cauchy-Born technique as the reference, a maximum error on the order of 50 % is reported for high-aspect ratio resonators.« less

Stability of hierarchical triples - I. Dependence on inner eccentricity and inclination

NASA Astrophysics Data System (ADS)

Mylläri, A.; Valtonen, M.; Pasechnik, A.; Mikkola, S.

2018-05-01

In simulations it is often important to decide if a given hierarchical triple star system is stable over an extended period of time. We introduce a stability criterion, modified from earlier work, where we use the closest approach ratio Q of the third star to the inner binary centre of mass in their initial osculating orbits. We study by numerical integration the orbits of over 1000 000 triple systems of the fixed masses and outer eccentricities eout, but varying inner eccentricities ein and inclinations i. 12 primary combinations of masses have been tried, representing the range encountered in stellar systems. The definition of the instability is either the escape of one of the bodies, or the exchange of the members between the inner and outer systems. An analytical approximation is derived using the energy change in a single close encounter between the inner and outer systems, assuming that the orbital phases in subsequent encounters occur randomly. The theory provides a fairly good description of the typical Qst, the smallest Q value that allows the system to be stable over N = 10 000 revolutions of the initial outer orbit. The final stability limit formula is Qst = 101/3A[( f g)2/(1 - eout)]1/6, where the coefficient A ˜ 1 should be used in N-body experiments, and A = 2.4 when the absolute long-term stability is required. The functions f (ein, cos i) and g(m1, m2, m3) are derived in the paper. At the limit of ein = i = m3 = 0, f g = 1.

INTERRUPTED STELLAR ENCOUNTERS IN STAR CLUSTERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geller, Aaron M.; Leigh, Nathan W. C., E-mail: a-geller@northwestern.edu, E-mail: nleigh@amnh.org

Strong encounters between single stars and binaries play a pivotal role in the evolution of star clusters. Such encounters can also dramatically modify the orbital parameters of binaries, exchange partners in and out of binaries, and are a primary contributor to the rate of physical stellar collisions in star clusters. Often, these encounters are studied under the approximation that they happen quickly enough and within a small enough volume to be considered isolated from the rest of the cluster. In this paper, we study the validity of this assumption through the analysis of a large grid of single–binary and binary–binarymore » scattering experiments. For each encounter we evaluate the encounter duration, and compare this with the expected time until another single or binary star will join the encounter. We find that for lower-mass clusters, similar to typical open clusters in our Galaxy, the percent of encounters that will be “interrupted” by an interloping star or binary may be 20%–40% (or higher) in the core, though for typical globular clusters we expect ≲1% of encounters to be interrupted. Thus, the assumption that strong encounters occur in relative isolation breaks down for certain clusters. Instead, many strong encounters develop into more complex “mini-clusters,” which must be accounted for in studying, for example, the internal dynamics of star clusters, and the physical stellar collision rate.« less

Encounter times of chromatin loci influenced by polymer decondensation

NASA Astrophysics Data System (ADS)

Amitai, A.; Holcman, D.

2018-03-01

The time for a DNA sequence to find its homologous counterpart depends on a long random search inside the cell nucleus. Using polymer models, we compute here the mean first encounter time (MFET) between two sites located on two different polymer chains and confined locally by potential wells. We find that reducing tethering forces acting on the polymers results in local decondensation, and numerical simulations of the polymer model show that these changes are associated with a reduction of the MFET by several orders of magnitude. We derive here new asymptotic formula for the MFET, confirmed by Brownian simulations. We conclude from the present modeling approach that the fast search for homology is mediated by a local chromatin decondensation due to the release of multiple chromatin tethering forces. The present scenario could explain how the homologous recombination pathway for double-stranded DNA repair is controlled by its random search step.

Cognitive-based approach in teaching 1st year Physics for Life Sciences, including Atmospheric Physics and Climate Change components

NASA Astrophysics Data System (ADS)

Petelina, S. V.

2009-12-01

Most 1st year students who take the service course in Physics - Physics for Life Sciences - in Australia encounter numerous problems caused by such factors as no previous experience with this subject; general perception that Physics is hard and only very gifted people are able to understand it; lack of knowledge of elementary mathematics; difficulties encountered by lecturers in teaching university level Physics to a class of nearly 200 students with no prior experience, diverse and sometime disadvantageous backgrounds, different majoring areas, and different learning abilities. As a result, many students either drop, or fail the subject. In addition, many of those who pass develop a huge dislike towards Physics, consider the whole experience as time wasted, and spread this opinion among their peers and friends. The above issues were addressed by introducing numerous changes to the curriculum and modifying strategies and approaches in teaching Physics for Life Sciences. Instead of a conventional approach - teaching Physics from simple to complicated, topic after topic, the students were placed in the world of Physics in the same way as a newborn child is introduced to this world - everything is seen all the time and everywhere. That created a unique environment where a bigger picture and all details were always present and interrelated. Numerous concepts of classical and modern physics were discussed, compared, and interconnected all the time with “Light” being a key component. Our primary field of research is Atmospheric Physics, in particular studying the atmospheric composition and structure using various satellite and ground-based data. With this expertise and also inspired by an increasing importance of training a scientifically educated generation who understands the challenges of the modern society and responsibilities that come with wealth, a new section on environmental physics has been developed. It included atmospheric processes and the greenhouse effect, climate change, stratospheric ozone depletion, skin cancer, ets. This new section has been greatly appreciated by the students, and adding more material on this was requested.

Curvilinear immersed-boundary method for simulating unsteady flows in shallow natural streams with arbitrarily complex obstacles

NASA Astrophysics Data System (ADS)

Kang, Seokkoo; Borazjani, Iman; Sotiropoulos, Fotis

2008-11-01

Unsteady 3D simulations of flows in natural streams is a challenging task due to the complexity of the bathymetry, the shallowness of the flow, and the presence of multiple nature- and man-made obstacles. This work is motivated by the need to develop a powerful numerical method for simulating such flows using coherent-structure-resolving turbulence models. We employ the curvilinear immersed boundary method of Ge and Sotiropoulos (Journal of Computational Physics, 2007) and address the critical issue of numerical efficiency in large aspect ratio computational domains and grids such as those encountered in long and shallow open channels. We show that the matrix-free Newton-Krylov method for solving the momentum equations coupled with an algebraic multigrid method with incomplete LU preconditioner for solving the Poisson equation yield a robust and efficient procedure for obtaining time-accurate solutions in such problems. We demonstrate the potential of the numerical approach by carrying out a direct numerical simulation of flow in a long and shallow meandering stream with multiple hydraulic structures.

The orbiter mate/demate device

NASA Technical Reports Server (NTRS)

Miller, A. J.; Binkley, W. H.

1985-01-01

The numerous components and systems of the space shuttle orbiter mate/demate device (MDD) are discussed. Special emphasis is given, mechanisms and mechanical systems to discuss in general their requirements, functions, and design; and, where applicable, to relate any unusual problems encountered during the initial concept studies, final design, and construction are discussed. The MDD and its electrical, machinery, and mechanical systems, including the main hoisting system, power operated access service platform, wind restrain and adjustment mechanism, etc., were successfully designed and constructed. The MDD was used routinely during the initial orbiter-747 approach and landing test and the more recent orbiter flight tests recovery and mate operations.

The Dynamics of Objects in the Inner Edgeworth Kuiper Belt

NASA Astrophysics Data System (ADS)

Jones, Daniel C.; Williams, Iwan P.; Melita, Mario D.

2005-12-01

Objects in 3:2 mean motion resonance with Neptune are protected from close encounters with Neptune by the resonance. Bodies in orbits with semi-major axis between 39.5 and about 42 AU are not protected by the resonance; indeed due to overlapping secular resonances, the eccentricities of orbits in this region are driven up so that a close encounter with Neptune becomes inevitable. It is thus expected that such orbits are unstable. The list of known Trans-Neptunian objects shows a deficiency in the number of objects in this gap compared to the 43 50 AU region, but the gap is not empty. We numerically integrate models for the initial population in the gap, and also all known objects over the age of the Solar System to determine what fraction can survive. We find that this fraction is significantly less than the ratio of the population in the gap to that in the main belt, suggesting that some mechanism must exist to introduce new members into the gap. By looking at the evolution of the test body orbits, we also determine the manner in which they are lost. Though all have close encounters with Neptune, in most cases this does not lead to ejection from the Solar System, but rather to a reduced perihelion distance causing close encounters with some or all of the other giant planets before being eventually lost from the system, with Saturn appearing to be the cause of the ejection of most of the objects.

Formulation of a General Technique for Predicting Pneumatic Attenuation Errors in Airborne Pressure Sensing Devices

NASA Technical Reports Server (NTRS)

Whitmore, Stephen A.

1988-01-01

Presented is a mathematical model derived from the Navier-Stokes equations of momentum and continuity, which may be accurately used to predict the behavior of conventionally mounted pneumatic sensing systems subject to arbitrary pressure inputs. Numerical techniques for solving the general model are developed. Both step and frequency response lab tests were performed. These data are compared with solutions of the mathematical model and show excellent agreement. The procedures used to obtain the lab data are described. In-flight step and frequency response data were obtained. Comparisons with numerical solutions of the math model show good agreement. Procedures used to obtain the flight data are described. Difficulties encountered with obtaining the flight data are discussed.

Three-dimensional analysis of tokamaks and stellarators

PubMed Central

Garabedian, Paul R.

2008-01-01

The NSTAB equilibrium and stability code and the TRAN Monte Carlo transport code furnish a simple but effective numerical simulation of essential features of present tokamak and stellarator experiments. When the mesh size is comparable to the island width, an accurate radial difference scheme in conservation form captures magnetic islands successfully despite a nested surface hypothesis imposed by the mathematics. Three-dimensional asymmetries in bifurcated numerical solutions of the axially symmetric tokamak problem are relevant to the observation of unstable neoclassical tearing modes and edge localized modes in experiments. Islands in compact stellarators with quasiaxial symmetry are easier to control, so these configurations will become good candidates for magnetic fusion if difficulties with safety and stability are encountered in the International Thermonuclear Experimental Reactor (ITER) project. PMID:18768807

General Aviation Weather Encounter Case Studies

DOT National Transportation Integrated Search

2012-09-01

This study presents a compilation of 24 cases involving general aviation (GA) pilots weather encounters over the : continental U.S. The project team interviewed pilots who had experienced a weather encounter, and we : examined their backgrounds, f...

Another Woman Gets Robbed? What Jung, Freud, Piaget, and Vygotsky Took from Sabina Spielrein

ERIC Educational Resources Information Center

Aldridge, Jerry

2009-01-01

Certainly not as many who have heard the names of Carl Jung, Sigmund Freud, Jean Piaget, and Lev Vygotsky, have heard of Sabina Spielrein. While Spielrein had numerous face-to-face encounters, some personal and some professional, with all four men, and the accounting of her life and the interactions she had with them has been the content of…

The Use of Video Technology for Providing Feedback to Students: Can It Enhance the Feedback Experience for Staff and Students?

ERIC Educational Resources Information Center

Crook, Anne; Mauchline, Alice; Maw, Stephen; Lawson, Clare; Drinkwater, Robyn; Lundqvist, Karsten; Orsmond, Paul; Gomez, Stephen; Park, Julian

2012-01-01

There are numerous issues surrounding the provision of assessment-related feedback in Higher Education, which in recent years have been highlighted in the National Student Survey. In this paper questionnaire data from staff and students at the University of Reading are used to confirm the main issues encountered with feedback, namely problems of…

Exchange of meteorites (and life?) between stellar systems.

PubMed

Melosh, H J

2003-01-01

It is now generally accepted that meteorite-size fragments of rock can be ejected from planetary bodies. Numerical studies of the orbital evolution of such planetary ejecta are consistent with the observed cosmic ray exposure times and infall rates of these meteorites. All of these numerical studies agree that a substantial fraction (up to one-third) of the ejecta from any planet in our Solar System is eventually thrown out of the Solar System during encounters with the giant planets Jupiter and Saturn. In this paper I examine the probability that such interstellar meteorites might be captured into a distant solar system and fall onto a terrestrial planet in that system within a given interval of time. The overall conclusion is that it is very unlikely that even a single meteorite originating on a terrestrial planet in our solar system has fallen onto a terrestrial planet in another stellar system, over the entire period of our Solar System's existence. Although viable microorganisms may be readily exchanged between planets in our solar system through the interplanetary transfer of meteoritic material, it seems that the origin of life on Earth must be sought within the confines of the Solar System, not abroad in the galaxy.

Orbit classification in an equal-mass non-spinning binary black hole pseudo-Newtonian system

NASA Astrophysics Data System (ADS)

Zotos, Euaggelos E.; Dubeibe, Fredy L.; González, Guillermo A.

2018-07-01

The dynamics of a test particle in a non-spinning binary black hole system of equal masses is numerically investigated. The binary system is modelled in the context of the pseudo-Newtonian circular restricted three-body problem, such that the primaries are separated by a fixed distance and move in a circular orbit around each other. In particular, the Paczyński-Wiita potential is used for describing the gravitational field of the two non-Newtonian primaries. The orbital properties of the test particle are determined through the classification of the initial conditions of the orbits, using several values of the Jacobi constant, in the Hill's regions of possible motion. The initial conditions are classified into three main categories: (i) bounded, (ii) escaping, and (iii) displaying close encounters. Using the smaller alignment index chaos indicator, we further classify bounded orbits into regular, sticky, or chaotic. To gain a complete view of the dynamics of the system, we define grids of initial conditions on different types of two-dimensional planes. The orbital structure of the configuration plane, along with the corresponding distributions of the escape and collision/close encounter times, allow us to observe the transition from the classical Newtonian to the pseudo-Newtonian regime. Our numerical results reveal a strong dependence of the properties of the considered basins with the Jacobi constant as well as with the Schwarzschild radius of the black holes.

Supersymmetry on the Lattice

NASA Astrophysics Data System (ADS)

Schaich, David

2016-03-01

Lattice field theory provides a non-perturbative regularization of strongly interacting systems, which has proven crucial to the study of quantum chromodynamics among many other theories. Supersymmetry plays prominent roles in the study of physics beyond the standard model, both as an ingredient in model building and as a tool to improve our understanding of quantum field theory. Attempts to apply lattice techniques to supersymmetric field theories have a long history, but until recently these efforts have generally encountered insurmountable difficulties related to the interplay of supersymmetry with the lattice discretization of spacetime. In recent years these difficulties have been overcome for a class of theories that includes the particularly interesting case of maximally supersymmetric Yang-Mills (N = 4 SYM) in four dimensions, which is a cornerstone of AdS/CFT duality. In combination with computational advances this progress enables practical numerical investigations of N = 4 SYM on the lattice, which can address questions that are difficult or impossible to handle through perturbation theory, AdS/CFT duality, or the conformal bootstrap program. I will briefly review some of the new ideas underlying this recent progress, and present some results from ongoing large-scale numerical calculations, including comparisons with analytic predictions.

Turbulent Concentration of MM-Size Particles in the Protoplanetary Nebula: Scaled-Dependent Multiplier Functions

NASA Technical Reports Server (NTRS)

Cuzzi, Jeffrey N.; Hartlep, Thomas; Weston, B.; Estremera, Shariff Kareem

2014-01-01

The initial accretion of primitive bodies (asteroids and TNOs) from freely-floating nebula particles remains problematic. Here we focus on the asteroids where constituent particle (read "chondrule") sizes are observationally known; similar arguments will hold for TNOs, but the constituent particles in those regions will be smaller, or will be fluffy aggregates, and are unobserved. Traditional growth-bysticking models encounter a formidable "meter-size barrier" [1] (or even a mm-cm-size barrier [2]) in turbulent nebulae, while nonturbulent nebulae form large asteroids too quickly to explain long spreads in formation times, or the dearth of melted asteroids [3]. Even if growth by sticking could somehow breach the meter size barrier, other obstacles are encountered through the 1-10km size range [4]. Another clue regarding planetesimal formation is an apparent 100km diameter peak in the pre-depletion, pre-erosion mass distribution of asteroids [5]; scenarios leading directly from independent nebula particulates to this size, which avoid the problematic m-km size range, could be called "leapfrog" scenarios [6-8]. The leapfrog scenario we have studied in detail involves formation of dense clumps of aerodynamically selected, typically mm-size particles in turbulence, which can under certain conditions shrink inexorably on 100-1000 orbit timescales and form 10-100km diameter sandpile planetesimals. The typical sizes of planetesimals and the rate of their formation [7,8] are determined by a statistical model with properties inferred from large numerical simulations of turbulence [9]. Nebula turbulence can be described by its Reynolds number Re = L/eta sup(4/3), where L = ETA alpha sup (1/2) the largest eddy scale, H is the nebula gas vertical scale height, and a the nebula turbulent viscosity parameter, and ? is the Kolmogorov or smallest scale in turbulence (typically about 1km), with eddy turnover time t?. In the nebula, Re is far larger than any numerical simulation can handle, so some physical model is needed to extend the results of numerical simulations to nebula conditions.

Numerical analysis of the heat transfer and fluid flow in the butt-fusion welding process

NASA Astrophysics Data System (ADS)

Yoo, Jae Hyun; Choi, Sunwoong; Nam, Jaewook; Ahn, Kyung Hyun; Oh, Ju Seok

2017-02-01

Butt-fusion welding is an effective process for welding polymeric pipes. The process can be simplified into two stages. In heat soak stage, the pipe is heated using a hot plate contacted with one end of the pipe. In jointing stage, a pair of heated pipes is compressed against one another so that the melt regions become welded. In previous works, the jointing stage that is highly related to the welding quality was neglected. However, in this study, a finite element simulation is conducted including the jointing stage. The heat and momentum transfer are considered altogether. A new numerical scheme to describe the melt flow and pipe deformation for the butt-fusion welding process is introduced. High density polyethylene (HDPE) is used for the material. Flow via thermal expansion of the heat soak stage, and squeezing and fountain flow of the jointing stage are well reproduced. It is also observed that curling beads are formed and encounter the pipe body. The unique contribution of this study is its capability of directly observing the flow behaviors that occur during the jointing stage and relating them to welding quality.

Energetic Neutral Atom Emissions From Venus: VEX Observations and Theoretical Modeling

NASA Technical Reports Server (NTRS)

Fok, M.-C.; Galli, A.; Tanaka, T.; Moore, T. E.; Wurz, P.; Holmstrom, M.

2007-01-01

Venus has almost no intrinsic magnetic field to shield itself from its surrounding environment. The solar wind thus directly interacts with the planetary ionosphere and atmosphere. One of the by-products of this close encounter is the production of energetic neutral atom (ENA) emissions. Theoretical studies have shown that significant amount of ENAs are emanated from the planet. The launch of the Venus Express (VEX) in 2005 provided the first light ever of the Venus ENA emissions. The observed ENA flux level and structure are in pretty good agreement with the theoretical studies. In this paper, we present VEX ENA data and the comparison with numerical simulations. We seek to understand the solar wind interaction with the planet and the impacts on its atmospheres.

Energy spectrum of tearing mode turbulence in sheared background field

NASA Astrophysics Data System (ADS)

Hu, Di; Bhattacharjee, Amitava; Huang, Yi-Min

2018-06-01

The energy spectrum of tearing mode turbulence in a sheared background magnetic field is studied in this work. We consider the scenario where the nonlinear interaction of overlapping large-scale modes excites a broad spectrum of small-scale modes, generating tearing mode turbulence. The spectrum of such turbulence is of interest since it is relevant to the small-scale back-reaction on the large-scale field. The turbulence we discuss here differs from traditional MHD turbulence mainly in two aspects. One is the existence of many linearly stable small-scale modes which cause an effective damping during the energy cascade. The other is the scale-independent anisotropy induced by the large-scale modes tilting the sheared background field, as opposed to the scale-dependent anisotropy frequently encountered in traditional critically balanced turbulence theories. Due to these two differences, the energy spectrum deviates from a simple power law and takes the form of a power law multiplied by an exponential falloff. Numerical simulations are carried out using visco-resistive MHD equations to verify our theoretical predictions, and a reasonable agreement is found between the numerical results and our model.

Effect of concrete strength gradation to the compressive strength of graded concrete, a numerical approach

NASA Astrophysics Data System (ADS)

Pratama, M. Mirza Abdillah; Aylie, Han; Gan, Buntara Sthenly; Umniati, B. Sri; Risdanareni, Puput; Fauziyah, Shifa

2017-09-01

Concrete casting, compacting method, and characteristic of the concrete material determine the performance of concrete as building element due to the material uniformity issue. Previous studies show that gradation in strength exists on building member by nature and negatively influence the load carrying capacity of the member. A pilot research had modeled the concrete gradation in strength with controllable variable and observed that the weakest material determines the strength of graded concrete through uniaxial compressive loading test. This research intends to confirm the recent finding by a numerical approach with extensive variables of strength disparity. The finite element analysis was conducted using the Strand7 nonlinear program. The results displayed that the increase of strength disparity in graded concrete models leads to the slight reduction of models strength. A substantial difference in displacement response is encountered on the models for the small disparity of concrete strength. However, the higher strength of concrete mix in the graded concrete models contributes to the rise of material stiffness that provides a beneficial purpose for serviceability of building members.

Addressing Common Questions Encountered in the Diagnosis and Management of Cardiac Amyloidosis.

PubMed

Maurer, Mathew S; Elliott, Perry; Comenzo, Raymond; Semigran, Marc; Rapezzi, Claudio

2017-04-04

Advances in cardiac imaging have resulted in greater recognition of cardiac amyloidosis in everyday clinical practice, but the diagnosis continues to be made in patients with late-stage disease, suggesting that more needs to be done to improve awareness of its clinical manifestations and the potential of therapeutic intervention to improve prognosis. Light chain cardiac amyloidosis, in particular, if recognized early and treated with targeted plasma cell therapy, can be managed very effectively. For patients with transthyretin amyloidosis, there are numerous therapies that are currently in late-phase clinical trials. In this review, we address common questions encountered in clinical practice regarding etiology, clinical presentation, diagnosis, and management of cardiac amyloidosis, focusing on recent important developments in cardiac imaging and biochemical diagnosis. The aim is to show how a systematic approach to the evaluation of suspected cardiac amyloidosis can impact the prognosis of patients in the modern era. © 2017 American Heart Association, Inc.

Addressing Common Questions Encountered in the Diagnosis and Management of Cardiac Amyloidosis

PubMed Central

Maurer, Mathew S.; Elliott, Perry; Comenzo, Raymond; Semigran, Marc; Rapezzi, Claudio

2017-01-01

Advances in cardiac imaging have resulted in greater recognition of cardiac amyloidosis (CA) in everyday clinical practice, but the diagnosis continues to be made in patients with late stage disease, suggesting that more needs to be done to improve awareness of its clinical manifestations and the potential of therapeutic intervention to improve prognosis. Light chain CA (AL-CA) in particular, if recognized early and treated with targeted plasma cell therapy, can be managed very effectively. For patients with transthyretin amyloidosis, there are numerous therapies that are currently in late phase clinical trials. In this review we address common questions encountered in clinical practice regarding etiology, clinical presentation, diagnosis and management of cardiac amyloidosis, focusing on recent important developments in cardiac imaging and biochemical diagnosis. The aim is to show how a systematic approach to the evaluation of suspected CA can impact the prognosis of patients in the modern era. PMID:28373528

The Comet Halley dust and gas environment

NASA Technical Reports Server (NTRS)

Divine, N.; Hanner, M. S.; Newburn, R. L., Jr.; Sekanina, Z.; Yeomans, D. K.

1986-01-01

Quantitative descriptions of environments near the nucleus of comet P/Halley have been developed to support spacecraft and mission design for the flyby encounters in March, 1986. To summarize these models as they exist just before the encounters, the relevant data from prior Halley apparitions and from recent cometary research are reviewed. Orbital elements, visual magnitudes, and parameter values and analysis for the nucleus, gas and dust are combined to predict Halley's position, production rates, gas and dust distributions, and electromagnetic radiation field for the current perihelion passage. The predicted numerical results have been useful for estimating likely spacecraft effects, such as impact damage and attitude perturbations. Sample applications are cited, including design of a dust shield for spacecraft structure, and threshold and dynamic range selection for flight experiments. It is expected that the comet's activity may be more irregular than these smoothly varying models predict, and that comparison with the flyby data will be instructive.

Describing knowledge encounters in healthcare: a mixed studies systematic review and development of a classification.

PubMed

Hurst, Dominic; Mickan, Sharon

2017-03-14

Implementation science seeks to promote the uptake of research and other evidence-based findings into practice, but for healthcare professionals, this is complex as practice draws on, in addition to scientific principles, rules of thumb and a store of practical wisdom acquired from a range of informational and experiential sources. The aims of this review were to identify sources of information and professional experiences encountered by healthcare workers and from this to build a classification system, for use in future observational studies, that describes influences on how healthcare professionals acquire and use information in their clinical practice. This was a mixed studies systematic review of observational studies. OVID MEDLINE and Embase and Google Scholar were searched using terms around information, knowledge or evidence and sharing, searching and utilisation combined with terms relating to healthcare groups. Studies were eligible if one of the intentions was to identify information or experiential encounters by healthcare workers. Data was extracted by one author after piloting with another. Studies were assessed using the Mixed Methods Appraisal Tool (MMAT). The primary outcome extracted was the information source or professional experience encounter. Similar encounters were grouped together as single constructs. Our synthesis involved a mixed approach using the top-down logic of the Bliss Bibliographic Classification System (BC2) to generate classification categories and a bottom-up approach to develop descriptive codes (or "facets") for each category, from the data. The generic terms of BC2 were customised by an iterative process of thematic content analysis. Facets were developed by using available theory and keeping in mind the pragmatic end use of the classification. Eighty studies were included from which 178 discreet knowledge encounters were extracted. Six classification categories were developed: what information or experience was encountered; how was the information or experience encountered; what was the mode of encounter; from whom did the information originate or with whom was the experience; how many participants were there; and where did the encounter take place. For each of these categories, relevant descriptive facets were identified. We have sought to identify and classify all knowledge encounters, and we have developed a faceted description of key categories which will support richer descriptions and interrogations of knowledge encounters in healthcare research.

Analytic algorithms for determining radiative transfer optical properties of ocean waters.

PubMed

Kaskas, Ayse; Güleçyüz, Mustafa C; Tezcan, Cevdet; McCormick, Norman J

2006-10-10

A synthetic model for the scattering phase function is used to develop simple algebraic equations, valid for any water type, for evaluating the ratio of the backscattering to absorption coefficients of spatially uniform, very deep waters with data from upward and downward planar irradiances and the remotely sensed reflectance. The phase function is a variable combination of a forward-directed Dirac delta function plus isotropic scattering, which is an elementary model for strongly forward scattering such as that encountered in oceanic optics applications. The incident illumination at the surface is taken to be diffuse plus a collimated beam. The algorithms are compared with other analytic correlations that were previously derived from extensive numerical simulations, and they are also numerically tested with forward problem results computed with a modified FN method.

A mesh-free approach to acoustic scattering from multiple spheres nested inside a large sphere by using diagonal translation operators.

PubMed

Hesford, Andrew J; Astheimer, Jeffrey P; Greengard, Leslie F; Waag, Robert C

2010-02-01

A multiple-scattering approach is presented to compute the solution of the Helmholtz equation when a number of spherical scatterers are nested in the interior of an acoustically large enclosing sphere. The solution is represented in terms of partial-wave expansions, and a linear system of equations is derived to enforce continuity of pressure and normal particle velocity across all material interfaces. This approach yields high-order accuracy and avoids some of the difficulties encountered when using integral equations that apply to surfaces of arbitrary shape. Calculations are accelerated by using diagonal translation operators to compute the interactions between spheres when the operators are numerically stable. Numerical results are presented to demonstrate the accuracy and efficiency of the method.

A mesh-free approach to acoustic scattering from multiple spheres nested inside a large sphere by using diagonal translation operators

PubMed Central

Hesford, Andrew J.; Astheimer, Jeffrey P.; Greengard, Leslie F.; Waag, Robert C.

2010-01-01

A multiple-scattering approach is presented to compute the solution of the Helmholtz equation when a number of spherical scatterers are nested in the interior of an acoustically large enclosing sphere. The solution is represented in terms of partial-wave expansions, and a linear system of equations is derived to enforce continuity of pressure and normal particle velocity across all material interfaces. This approach yields high-order accuracy and avoids some of the difficulties encountered when using integral equations that apply to surfaces of arbitrary shape. Calculations are accelerated by using diagonal translation operators to compute the interactions between spheres when the operators are numerically stable. Numerical results are presented to demonstrate the accuracy and efficiency of the method. PMID:20136208

User interface concerns

NASA Technical Reports Server (NTRS)

Redhed, D. D.

1978-01-01

Three possible goals for the Numerical Aerodynamic Simulation Facility (NASF) are: (1) a computational fluid dynamics (as opposed to aerodynamics) algorithm development tool; (2) a specialized research laboratory facility for nearly intractable aerodynamics problems that industry encounters; and (3) a facility for industry to use in its normal aerodynamics design work that requires high computing rates. The central system issue for industry use of such a computer is the quality of the user interface as implemented in some kind of a front end to the vector processor.

Network-induced chaos in integrate-and-fire neuronal ensembles.

PubMed

Zhou, Douglas; Rangan, Aaditya V; Sun, Yi; Cai, David

2009-09-01

It has been shown that a single standard linear integrate-and-fire (IF) neuron under a general time-dependent stimulus cannot possess chaotic dynamics despite the firing-reset discontinuity. Here we address the issue of whether conductance-based, pulsed-coupled network interactions can induce chaos in an IF neuronal ensemble. Using numerical methods, we demonstrate that all-to-all, homogeneously pulse-coupled IF neuronal networks can indeed give rise to chaotic dynamics under an external periodic current drive. We also provide a precise characterization of the largest Lyapunov exponent for these high dimensional nonsmooth dynamical systems. In addition, we present a stable and accurate numerical algorithm for evaluating the largest Lyapunov exponent, which can overcome difficulties encountered by traditional methods for these nonsmooth dynamical systems with degeneracy induced by, e.g., refractoriness of neurons.

FORMATION OF CENTAURS’ RINGS THROUGH THEIR PARTIAL TIDAL DISRUPTION DURING PLANETARY ENCOUNTERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hyodo, Ryuki; Charnoz, Sébastien; Genda, Hidenori

Centaurs are minor planets orbiting between Jupiter and Neptune that have or had crossing orbits with one or more giant planets. Recent observations and reinterpretation of previous observations have revealed the existence of ring systems around 10199 Chariklo and 2060 Chiron. However, the origin of the ring systems around such a minor planet is still an open question. Here, we propose that the tidal disruption of a differentiated object that experiences a close encounter with a giant planet could naturally form diverse ring–satellite systems around the Centaurs. During the close encounter, the icy mantle of the passing object is preferentiallymore » ripped off by the planet's tidal force and the debris is distributed mostly within the Roche limit of the largest remnant body. Assuming the existence of a 20−50 wt% silicate core below the icy mantle, a disk of particles is formed when the objects pass within 0.4–0.8 of the planet's Roche limit with the relative velocity at infinity 3−6 km s{sup −1} and 8 hr initial spin period of the body. The resultant ring mass is 0.1%–10% of the central object's mass. Such particle disks are expected to spread radially, and materials spreading beyond the Roche limit would accrete into satellites. Our numerical results suggest that ring formation would be a natural outcome of such extreme close encounters, and Centaurs can naturally have such ring systems because they cross the orbits of the giant planets.« less

Subcritical transition to turbulence: What we can learn from the physics of glasses.

PubMed

Dauchot, Olivier; Bertin, Eric

2012-09-01

In this note, we discuss possible analogies between the subcritical transition to turbulence in shear flows and the glass transition in supercooled liquids. We briefly review recent experimental and numerical results, as well as theoretical proposals, and compare the difficulties arising in assessing the divergence of the turbulence lifetime in subcritical shear flow with that encountered for the relaxation time in the study of the glass transition. In order to go beyond the purely methodological similarities, we further elaborate on this analogy and propose a simple model for the transition to turbulence, inspired by the random energy model (a standard model for the glass transition), with the aim to possibly foster yet-unexplored directions of research in subcritical shear flows.

Free underexpanded jets in a quiescent medium: A review

NASA Astrophysics Data System (ADS)

Franquet, Erwin; Perrier, Vincent; Gibout, Stéphane; Bruel, Pascal

2015-08-01

When dealing with high-pressure releases, be it needed by some operating conditions or due to an emergency protocol or even to the occurrence of an accident, one has to consider the relevant risks associated to this leakage. Indeed, in addition to the mechanical and blast effects, the dispersion of the released fluid is of primary importance if it is hazardous, as an example for toxic gases or flammable ones (where explosions or fires may be expected). In fact, despite the numerous studies dealing with underexpanded jets, many aspects of their structure are not clearly described, particularly when one seeks for quantitative predictions. By performing an exhaustive overview of the main experimental papers dealing with underexpanded jets, the present paper aims at clarifying the characteristics which are well known, from those where there is clearly a lack of confidence. Indeed, and curiously enough, such a work has never been done and no review is available on such a topic. Two particular regions have drawn most of the attention so far: the nearfield zone, where the shocks/rarefaction pattern that governs the structure of the jet is encountered, and the farfield zone, where the flow is fully developed and often approximated by an equivalent flow. Finally, some clues are given on the numerical methods that may be used if one wants to study such jets numerically, together with an emphasis on the specific thermodynamical difficulties associated to this kind of extreme conditions.

Table look-up estimation of signal and noise parameters from quantized observables

NASA Technical Reports Server (NTRS)

Vilnrotter, V. A.; Rodemich, E. R.

1986-01-01

A table look-up algorithm for estimating underlying signal and noise parameters from quantized observables is examined. A general mathematical model is developed, and a look-up table designed specifically for estimating parameters from four-bit quantized data is described. Estimator performance is evaluated both analytically and by means of numerical simulation, and an example is provided to illustrate the use of the look-up table for estimating signal-to-noise ratios commonly encountered in Voyager-type data.

Stress studies in EFG

NASA Technical Reports Server (NTRS)

1983-01-01

Experimental work in support of stress studies in high speed silicon sheet growth has been emphasized in this quarter. Creep experiments utilizing four-point bending have been made in the temperature range from 1000 C to 1360 C in CZ silicon as well as on EFG ribbon. A method to measure residual stress over large areas using laser interferometry to map strain distributions under load is under development. A fiber optics sensor to measure ribbon temperature profiles has been constructed and is being tested in a ribbon growth furnace environment. Stress and temperature field modeling work has been directed toward improving various aspects of the finite element computing schemes. Difficulties in computing stress distributions with a very high creep intensity and with non-zero interface stress have been encountered and additional development of the numerical schemes to cope with these problems is required. Temperature field modeling has been extended to include the study of heat transfer effects in the die and meniscus regions.

Luminescence quenching by reversible ionization or exciplex formation/dissociation.

PubMed

Ivanov, Anatoly I; Burshtein, Anatoly I

2008-11-20

The kinetics of fluorescence quenching by both charge transfer and exciplex formation is investigated, with an emphasis on the reversibility and nonstationarity of the reactions. The Weller elementary kinetic scheme of bimolecular geminate ionization and the Markovian rate theory are shown to lead to identical results, provided the rates of the forward and backward reactions account for the numerous recontacts during the reaction encounter. For excitation quenching by the reversible exciplex formation, the Stern-Volmer constant is specified in the framework of the integral encounter theory. The bulk recombination affecting the Stern-Volmer quenching constant makes it different for pulse excited and stationary luminescence. The theory approves that the free energy gap laws for ionization and exciplex formation are different and only the latter fits properly the available data (for lumiflavin quenching by aliphatic amines and aromatic donors) in the endergonic region.

The impact of debris on marine life.

PubMed

Gall, S C; Thompson, R C

2015-03-15

Marine debris is listed among the major perceived threats to biodiversity, and is cause for particular concern due to its abundance, durability and persistence in the marine environment. An extensive literature search reviewed the current state of knowledge on the effects of marine debris on marine organisms. 340 original publications reported encounters between organisms and marine debris and 693 species. Plastic debris accounted for 92% of encounters between debris and individuals. Numerous direct and indirect consequences were recorded, with the potential for sublethal effects of ingestion an area of considerable uncertainty and concern. Comparison to the IUCN Red List highlighted that at least 17% of species affected by entanglement and ingestion were listed as threatened or near threatened. Hence where marine debris combines with other anthropogenic stressors it may affect populations, trophic interactions and assemblages. Copyright © 2015 Elsevier Ltd. All rights reserved.

The man/machine interface in information retrieval: Providing access to the casual user

NASA Technical Reports Server (NTRS)

Dominick, Wayne D. (Editor); Granier, Martin

1984-01-01

This study is concerned with the difficulties encountered by casual users wishing to employ Information Storage and Retrieval Systems. A casual user is defined as a professional who has neither time nor desire to pursue in depth the study of the numerous and varied retrieval systems. His needs for on-line search are only occasional, and not limited to any particular system. The paper takes a close look at the state of the art of research concerned with aiding casual users of Information Storage and Retrieval Systems. Current experiments such as LEXIS, CONIT, IIDA, CITE, and CCL are presented and discussed. Comments and proposals are offered, specifically in the areas of training, learning and cost as experienced by the casual user. An extensive bibliography of recent works on the subject follows the text.

A Comparative Study of Three Methodologies for Modeling Dynamic Stall

NASA Technical Reports Server (NTRS)

Sankar, L.; Rhee, M.; Tung, C.; ZibiBailly, J.; LeBalleur, J. C.; Blaise, D.; Rouzaud, O.

2002-01-01

During the past two decades, there has been an increased reliance on the use of computational fluid dynamics methods for modeling rotors in high speed forward flight. Computational methods are being developed for modeling the shock induced loads on the advancing side, first-principles based modeling of the trailing wake evolution, and for retreating blade stall. The retreating blade dynamic stall problem has received particular attention, because the large variations in lift and pitching moments encountered in dynamic stall can lead to blade vibrations and pitch link fatigue. Restricting to aerodynamics, the numerical prediction of dynamic stall is still a complex and challenging CFD problem, that, even in two dimensions at low speed, gathers the major difficulties of aerodynamics, such as the grid resolution requirements for the viscous phenomena at leading-edge bubbles or in mixing-layers, the bias of the numerical viscosity, and the major difficulties of the physical modeling, such as the turbulence models, the transition models, whose both determinant influences, already present in static maximal-lift or stall computations, are emphasized by the dynamic aspect of the phenomena.

Breast-feeding perceptions, beliefs and experiences of Marshallese migrants: an exploratory study

PubMed Central

Scott, Alison; Shreve, Marilou; Ayers, Britni

2017-01-01

Objective To understand perceptions, beliefs, and experiences about breastfeeding in Marshallese mothers residing in Northwest Arkansas. Design A qualitative, exploratory study using a brief survey and focus groups. Marshallese women, 18 years or older who have a child under seven years of age were included in the study. A total of 31 participants were interviewed in five focus groups. In addition, four native Marshallese community health workers who work with Marshallese mothers participated in a sixth focus group. Setting Community-based organization in Northwest Arkansas. Results The majority of mothers viewed breast milk as superior to formula, but had concerns about adequate milk supply and the nutritional value of their milk. The primary barriers to exclusive breastfeeding in the United States included public shaming – both verbal and non-verbal, perceived milk production and quality, and maternal employment. Participants report that these barriers are not experienced in the Marshall Islands and are encountered after moving to the United States. Breastfeeding mothers rely heavily on familial support, especially the eldest female, who may not reside in the United States. Institutions, including the Women, Infants, and Children (WIC) program influence is strong and may negatively affect breastfeeding. Conclusions Despite the belief that breast milk is the healthiest option, breastfeeding among Marshallese mothers is challenged by numerous barriers they encounter as they assimilate to US cultural norms. The barriers and challenges, along with the strong desire to assimilate to US culture, impact Marshallese mothers’ perceptions, beliefs, and experiences with breastfeeding. PMID:27230629

Numerical simulation of mushrooms during freezing using the FEM and an enthalpy: Kirchhoff formulation

NASA Astrophysics Data System (ADS)

Santos, M. V.; Lespinard, A. R.

2011-12-01

The shelf life of mushrooms is very limited since they are susceptible to physical and microbial attack; therefore they are usually blanched and immediately frozen for commercial purposes. The aim of this work was to develop a numerical model using the finite element technique to predict freezing times of mushrooms considering the actual shape of the product. The original heat transfer equation was reformulated using a combined enthalpy-Kirchhoff formulation, therefore an own computational program using Matlab 6.5 (MathWorks, Natick, Massachusetts) was developed, considering the difficulties encountered when simulating this non-linear problem in commercial softwares. Digital images were used to generate the irregular contour and the domain discretization. The numerical predictions agreed with the experimental time-temperature curves during freezing of mushrooms (maximum absolute error <3.2°C) obtaining accurate results and minimum computer processing times. The codes were then applied to determine required processing times for different operating conditions (external fluid temperatures and surface heat transfer coefficients).

Experimental Characterization of the Jet Wiping Process

NASA Astrophysics Data System (ADS)

Mendez, Miguel Alfonso; Enache, Adriana; Gosset, Anne; Buchlin, Jean-Marie

2018-06-01

This paper presents an experimental characterization of the jet wiping process, used in continuous coating applications to control the thickness of a liquid coat using an impinging gas jet. Time Resolved Particle Image Velocimetry (TR-PIV) is used to characterize the impinging gas flow, while an automatic interface detection algorithm is developed to track the liquid interface at the impact. The study of the flow interaction is combined with time resolved 3D thickness measurements of the liquid film remaining after the wiping, via Time Resolved Light Absorption (TR-LAbs). The simultaneous frequency analysis of liquid and gas flows allows to correlate their respective instability, provide an experimental data set for the validation of numerical studies and allows for formulating a working hypothesis on the origin of the coat non-uniformity encountered in many jet wiping processes.

Lipids of aquatic sediments, recent and ancient

NASA Technical Reports Server (NTRS)

Eglinton, G.; Hajibrahim, S. K.; Maxwell, J. R.; Quirke, J. M. E.; Shaw, G. J.; Volkman, J. K.; Wardroper, A. M. K.

1979-01-01

Computerized gas chromatography-mass spectrometry (GC-MS) is now an essential tool in the analysis of the complex mixtures of lipids (geolipids) encountered in aquatic sediments, both 'recent' (less than 1 million years old) and ancient. The application of MS, and particularly GC-MS, has been instrumental in the rapid development of organic geochemistry and environmental organic chemistry in recent years. The techniques used have resulted in the identification of numerous compounds of a variety of types in sediments. Most attention has been concentrated on molecules of limited size, mainly below 500 molecular mass, and of limited functionality, for examples, hydrocarbons, fatty acids and alcohols. Examples from recent studies (at Bristol) of contemporary, 'recent' and ancient sediments are presented and discussed.

Dynamical Evolution of Ring-Satellite Systems

NASA Technical Reports Server (NTRS)

Ohtsuki, Keiji

2005-01-01

The goal of this research was to understand dynamical processes related to the evolution of size distribution of particles in planetary rings and application of theoretical results to explain features in the present rings of giant planets. We studied velocity evolution and accretion rates of ring particles in the Roche zone. We developed a new numerical code for the evolution of ring particle size distribution, which takes into account the above results for particle velocity evolution and accretion rates. We also studied radial diffusion rate of ring particles due to inelastic collisions and gravitational encounters. Many of these results can be also applied to dynamical evolution of a planetesimal disk. Finally, we studied rotation rates of moonlets and particles in planetary rings, which would influence the accretional evolution of these bodies. We describe our key accomplishments during the past three years in more detail in the following.

In vivo Host Environment Alters Pseudomonas aeruginosa Susceptibility to Aminoglycoside Antibiotics

PubMed Central

Pan, Xiaolei; Dong, Yuanyuan; Fan, Zheng; Liu, Chang; Xia, Bin; Shi, Jing; Bai, Fang; Jin, Yongxin; Cheng, Zhihui; Jin, Shouguang; Wu, Weihui

2017-01-01

During host infection, Pseudomonas aeruginosa coordinately regulates the expression of numerous genes to adapt to the host environment while counteracting host clearance mechanisms. As infected patients take antibiotics, the invading bacteria encounter antibiotics in the host milieu. P. aeruginosa is highly resistant to antibiotics due to multiple chromosomally encoded resistant determinants. And numerous in vitro studies have demonstrated the regulatory mechanisms of antibiotic resistance related genes in response to antibiotics. However, it is not well-known how host environment affects bacterial response to antibiotics. In this study, we found that P. aeruginosa cells directly isolated from mice lungs displayed higher susceptibility to tobramycin than in vitro cultured bacteria. In vitro experiments demonstrated that incubation with A549 and differentiated HL60 (dHL60) cells sensitized P. aeruginosa to tobramycin. Further studies revealed that reactive oxygen species produced by the host cells contributed to the increased bacterial susceptibility. At the same concentration of tobramycin, presence of A549 and dHL60 cells resulted in higher expression of heat shock proteins, which are known inducible by tobramycin. Further analyses revealed decreased membrane potential upon incubation with the host cells and modification of lipopolysaccharide, which contributed to the increased susceptibility to tobramycin. Therefore, our results demonstrate that contact with host cells increased bacterial susceptibility to tobramycin. PMID:28352614

Numerical assessment affects aggression and competitive ability: a team-fighting strategy for the ant Formica xerophila.

PubMed

Tanner, Colby J

2006-11-07

The relationship between numerical advantage and competitive ability is a fundamental component in contests between groups of social animals. An individual's ability to correctly assess the numerical state of its group is of vital importance. In addition to numerical dominance, the group's fighting ability also plays an important role in competitive interactions. By staging experimental fights between two Formica ant species, I show that Formica xerophila are able to assess their own group's strength prior to any competitive encounter. Ants that perceive themselves as part of a large group act more aggressively toward a competitor than ants that perceive themselves as isolated individuals. This increase in aggression improves F. xerophila's competitive ability. Furthermore, the number of individuals in a contest was found to affect competitive ability. In contests with equal number of competitors, groups of F. xerophila were more successful than individual F. xerophila. Contrary to previous predictions using Lanchester's laws of fighting, F. xerophila's ability to kill competitors increased nonlinearly with group size. This nonlinearity was due to the collective fighting strategy of an F. xerophila group isolating and engaging a single Formica integroides competitors.

Numerical assessment affects aggression and competitive ability: a team-fighting strategy for the ant Formica xerophila

PubMed Central

Tanner, Colby J

2006-01-01

The relationship between numerical advantage and competitive ability is a fundamental component in contests between groups of social animals. An individual's ability to correctly assess the numerical state of its group is of vital importance. In addition to numerical dominance, the group's fighting ability also plays an important role in competitive interactions. By staging experimental fights between two Formica ant species, I show that Formica xerophila are able to assess their own group's strength prior to any competitive encounter. Ants that perceive themselves as part of a large group act more aggressively toward a competitor than ants that perceive themselves as isolated individuals. This increase in aggression improves F. xerophila's competitive ability. Furthermore, the number of individuals in a contest was found to affect competitive ability. In contests with equal number of competitors, groups of F. xerophila were more successful than individual F. xerophila. Contrary to previous predictions using Lanchester's laws of fighting, F. xerophila's ability to kill competitors increased nonlinearly with group size. This nonlinearity was due to the collective fighting strategy of an F. xerophila group isolating and engaging a single Formica integroides competitors. PMID:17015327

Current Status of Gene Therapy for Inherited Lung Diseases

PubMed Central

Driskell, Ryan R.; Engelhardt, John F.

2007-01-01

Gene therapy as a treatment modality for pulmonary disorders has attracted significant interest over the past decade. Since the initiation of the first clinical trials for cystic fibrosis lung disease using recombinant adenovirus in the early 1990s, the field has encountered numerous obstacles including vector inflammation, inefficient delivery, and vector production. Despite these obstacles, enthusiasm for lung gene therapy remains high. In part, this enthusiasm is fueled through the diligence of numerous researchers whose studies continue to reveal great potential of new gene transfer vectors that demonstrate increased tropism for airway epithelia. Several newly identified serotypes of adeno-associated virus have demonstrated substantial promise in animal models and will likely surface soon in clinical trials. Furthermore, an increased understanding of vector biology has also led to the development of new technologies to enhance the efficiency and selectivity of gene delivery to the lung. Although the promise of gene therapy to the lung has yet to be realized, the recent concentrated efforts in the field that focus on the basic virology of vector development will undoubtedly reap great rewards over the next decade in treating lung diseases. PMID:12524461

Patients' comprehension of their emergency department encounter: a pilot study using physician observers.

PubMed

Musso, Mandi W; Perret, J Nelson; Sanders, Taylor; Daray, Ross; Anderson, Kyle; Lancaster, Melissa; Lim, David; Jones, Glenn N

2015-02-01

The current study examines patients' comprehension of their emergency department (ED) encounter, using physician observers to document both physician communication and details of the encounter. Eighty-nine patients were recruited from a convenience sample in an urban ED. To be included in this study, patients had to have low triage levels (4 and 5) and be discharged from the ED. Physician observers were present throughout the encounter, documenting physician communication and procedures performed. Patients were then interviewed by physician observers about their communication with physicians, accuracy in recalling facts about the encounter, and understanding of information provided during the encounter. The majority of patients were black and had a high school education. Physicians typically engaged in behaviors related to building rapport and diagnosing patients. However, physicians informed patients about test results and diagnoses less frequently. In terms of patients' accuracy and understanding of the visit, patients were generally aware of basic facts in regard to their ED encounter (ie, whether they had blood drawn), but 65.9% of patients demonstrated less than "good" understanding in at least 1 area assessed. The findings of the current study indicate physicians could improve communication with patients, particularly in regard to care received in the ED. This study also indicates that a large percentage of patients fail to understand information about their ED encounter even when physicians provide it. A primary limitation of the current study is the relatively homogenous physician sample. Copyright © 2014 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.

Remote sensing studies of the northeastern portion of the lunar nearside

NASA Technical Reports Server (NTRS)

Hawke, B. R.; Blewett, D. T.; Lucey, P. G.; Taylor, G. J.; Peterson, C. A.; Bell, J. F.; Robinson, M. S.; Bell, J. F., III; Coombs, C. R.; Jaumann, R.

1993-01-01

During the Galileo spacecraft encounter with the Earth-Moon system in December, 1992, a variety of spectral data and imagery were obtained for the eastern limb region as well as much of the lunar nearside. In order to support this encounter, we have been collecting near-infrared spectra and other remote sensing data for that portion of the northeastern nearside (NEM region) for which the highest resolution Galileo data were obtained. Analysis of spectra obtained for highlands units in the NEN region indicates that most surface units are dominated by anorthositic norite. To date, no pure anorthosites have been identified in the region. Several dark-haloed impact craters have exposed mare material from beneath highlands-rich surface units. Hence, ancient mare volcanism occurred in at least a portion of the NEN region. Endogenic dark-haloed craters in the region are the source of localized dark mantle deposits (LDMD) of pyroclastic origin and at least two compositional groups are present. The Galileo spacecraft obtained very high-resolution remote sensing data for the northeastern part of the nearside of the Moon. In order to prepare for and support this encounter, we have collected and analyzed a variety of spectral data for the NEN region. Numerous unanswered questions exist for this region. These include: (1) the composition and stratigraphy of the local highlands crust, (2) the nature and mode of formation of regional light plains, (3) the composition of localized pyroclastic deposits, and (4) the distribution of possible cryptomare in the region. The purpose of this paper is to present the preliminary results of our analyzes of remote sensing data of remote sensing data obtained for the NEN region.

Computer programs: Operational and mathematical, a compilation

NASA Technical Reports Server (NTRS)

1973-01-01

Several computer programs which are available through the NASA Technology Utilization Program are outlined. Presented are: (1) Computer operational programs which can be applied to resolve procedural problems swiftly and accurately. (2) Mathematical applications for the resolution of problems encountered in numerous industries. Although the functions which these programs perform are not new and similar programs are available in many large computer center libraries, this collection may be of use to centers with limited systems libraries and for instructional purposes for new computer operators.

Evaluation of Pharmacists’ Work in a Physician-Pharmacist Collaborative Model for the Management of Hypertension

PubMed Central

Isetts, Brian J.; Buffington, Daniel E.; Carter, Barry L.; Smith, Marie; Polgreen, Linnea A.; James, Paul A.

2016-01-01

Study Objective Physician-pharmacist collaborative models have been shown to improve the care of patients with numerous chronic medical conditions. Team-based health care using integrated clinical pharmacists provides one opportunity to improve quality in health care systems that use population-based financing. In November 2015, the Centers for Medicare and Medicaid Services (CMS) requested that the relative value of pharmacists’ work in team-based care needs to be established. Thus, the objective of this study was to describe the components of pharmacists’ work in the management of hypertension with a physician-pharmacist collaborative model. Design Descriptive analysis of the components of pharmacists’ work in the Collaboration Among Pharmacists and Physicians To Improve Outcomes Now (CAPTION) study, a prospective, cluster randomized trial. Measurements and Main Results This analysis was intended to provide policymakers with data and information, using the CAPTION study model, on the time and intensity of pharmacists’ work to understand pharmacists’ relative value contributions in the context of CMS financing and population management aims. The CAPTION trial was conducted in 32 community-based medical offices in 15 U.S. states and included 390 patients with multiple cardiovascular risk factors. Blood pressure was measured by trained study coordinators in each office, and patients were included in the study if they had uncontrolled blood pressure. Included patients were randomized to a 9-month intervention, a 24-month intervention, or usual care. The goal of the pharmacist intervention was to improve blood pressure control and resolve drug therapy problems impeding progress toward blood pressure goals. This intervention included medical record review, a structured assessment with the patient, collaboration to achieve goals of therapy, and patient follow-up. The two intervention arms (9 months and 24 months) were identical the first 9 months, and that time frame is the focus of this workload evaluation. Pharmacists completed study encounter forms for every patient encounter and estimated time spent in pre-visit, face-to-face care, and post-visit activities. Among the 390 patients, there were 2,811 encounters with pharmacists that involved 3.44 hours/patient for face-to-face care visits plus 1.55 hours/patient for pre-visit and post-visit work. Intensity of work was reflected in interventions to resolve drug therapy problems with patients (43% of encounters) and with physicians (1,169 recommendations, of which physicians accepted 1,153 [98.6%]), resulting in improvement of patients’ blood pressure goals achieved (from 0% at baseline to 43% at 9 months based on the primary study endpoint). Conclusion Pharmacists provided extensive interventions to patients with hypertension. This analysis provides a framework for health systems, provider groups, and payers to measure pharmacists’ work in value-based financing and population management. PMID:26893135

Temperature fluctuations in fully-developed turbulent channel flow with heated upper wall

NASA Astrophysics Data System (ADS)

Bahri, Carla; Mueller, Michael; Hultmark, Marcus

2013-11-01

The interactions and scaling differences between the velocity field and temperature field in a wall-bounded turbulent flow are investigated. In particular, a fully developed turbulent channel flow perturbed by a step change in the wall temperature is considered with a focus on the details of the developing thermal boundary layer. For this specific study, temperature acts as a passive scalar, having no dynamical effect on the flow. A combination of experimental investigation and direct numerical simulation (DNS) is presented. Velocity and temperature data are acquired with high accuracy where, the flow is allowed to reach a fully-developed state before encountering a heated upper wall at constant temperature. The experimental data is compared with DNS data where simulations of the same configuration are conducted.

Standoff reconnaissance imagery - Applications and interpreter training

NASA Astrophysics Data System (ADS)

Gustafson, G. C.

1980-01-01

The capabilities, advantages and applications of Long Range Oblique Photography (LOROP) standoff air reconnaissance cameras are reviewed, with emphasis on the problems likely to be encountered in photo interpreter training. Results of student exercises in descriptive image analysis and mensuration are presented and discussed, and current work on the computer programming of oblique and panoramic mensuration tasks is summarized. Numerous examples of this class of photographs and their interpretation at various magnifications are also presented.

Gene therapy for heart disease: molecular targets, vectors and modes of delivery to myocardium.

PubMed

Scimia, Maria Cecilia; Cannavo, Alessandro; Koch, Walter J

2013-08-01

Despite the numerous hurdles that gene therapy has encountered along the way, clinical trials over the last few years are showing promising results in many fields of medicine, including cardiology, where many targets are moving toward clinical development. In this review, the authors discuss the current state of the art in terms of clinical and preclinical development. They also examine vector technology and available vector-delivery strategies.

Medical identity theft in the emergency department: awareness is crucial.

PubMed

Mancini, Michelino

2014-11-01

Medical identity theft in the emergency department (ED) can harm numerous individuals, and many frontline healthcare providers are unaware of this growing concern. The two cases described began as typical ED encounters until red flags were discovered upon validating the patient's identity. Educating all healthcare personnel within and outside the ED regarding the subtle signs of medical identity theft and implementing institutional policies to identify these criminals will discourage further fraudulent behavior.

The Effects Of Earth’s Rotation On The Late Submarine Wake

DTIC Science & Technology

2017-12-01

had never before encountered. His practical knowledge and real-world experience were beneficial to not only this project, but to numerous other...rotation of the earth. Long-lived vortices were observed during these laboratory experiments , however both the vortices and wakes remained fairly...symmetric. In spite of this, Spedding 2 acknowledged that wakes and vortices in the ocean experience forcing not present in the laboratory and that real

Monitoring inter-group encounters in wilderness

Treesearch

Alan E. Watson; Rich Cronn; Neal A. Christensen

1998-01-01

Many managers face the challenge of monitoring rates of visitor encounters in wilderness. This study (1) provides estimates of encounter rates through use of several monitoring methods, (2) determines the relationship between the various measures of encounter rates, and (3) determines the relationship between various indirect predictors of encounter rates and actual...

Seasonal variation in hospital encounters with hypoglycaemia and hyperglycaemia.

PubMed

Clemens, K K; Shariff, S; Richard, L; Booth, G; Gilliland, J; Garg, A X

2017-07-01

To assess whether rates of hospital encounters with hypoglycaemia and hyperglycaemia display seasonal variation. Time series analyses of the monthly rates of hospital encounters (emergency room visits or inpatient admissions) with hypoglycaemia and hyperglycaemia from 2003 to 2012 using linked healthcare databases in Ontario, Canada. Over the study period, there were 129 887 hypoglycaemia and 79 773 hyperglycaemia encounters. The characteristics of people at the time of their encounters were similar across the seasons in 2008 (median age 68 years for hypoglycaemia encounters and 53 years for hyperglycaemia encounters; 50% female; 90% with diabetes). We observed moderate seasonality in both types of encounters (R 2 autoregression coefficient 0.58 for hypoglycaemia; 0.59 for hyperglycaemia). The rate of hypoglycaemia encounters appeared to peak between April and June, when on average, there was an additional 49 encounters per month (0.36 encounters per 100 000 persons per month) compared with the other calendar months (5% increase). The rate of hyperglycaemia encounters appeared to peak in January, when on average, there was an additional 69 encounters per month (0.50 encounters per 100 000 persons per month) compared with the other calendar months (11% increase). In our region, there is seasonal variation in the rate of hospital encounters with hypoglycaemia and hyperglycaemia. Our findings may help to highlight periods of vulnerability for people, may inform future epidemiological studies and may aid in the appropriate planning of healthcare resources. © 2017 Diabetes UK.

Orbit classification in an equal-mass non-spinning binary black hole pseudo-Newtonian system

NASA Astrophysics Data System (ADS)

Zotos, Euaggelos E.; Dubeibe, F. L.; González, Guillermo A.

2018-04-01

The dynamics of a test particle in a non-spinning binary black hole system of equal masses is numerically investigated. The binary system is modeled in the context of the pseudo-Newtonian circular restricted three-body problem, such that the primaries are separated by a fixed distance and move in a circular orbit around each other. In particular, the Paczyński-Wiita potential is used for describing the gravitational field of the two non-Newtonian primaries. The orbital properties of the test particle are determined through the classification of the initial conditions of the orbits, using several values of the Jacobi constant, in the Hill's regions of possible motion. The initial conditions are classified into three main categories: (i) bounded, (ii) escaping and (iii) displaying close encounters. Using the smaller alignment index (SALI) chaos indicator, we further classify bounded orbits into regular, sticky or chaotic. To gain a complete view of the dynamics of the system, we define grids of initial conditions on different types of two-dimensional planes. The orbital structure of the configuration plane, along with the corresponding distributions of the escape and collision/close encounter times, allow us to observe the transition from the classical Newtonian to the pseudo-Newtonian regime. Our numerical results reveal a strong dependence of the properties of the considered basins with the Jacobi constant as well as with the Schwarzschild radius of the black holes.

General Relativistic Precession in Small Solar System Bodies

NASA Astrophysics Data System (ADS)

Sekhar, Aswin; Werner, Stephanie; Hoffmann, Volker; Asher, David; Vaubaillon, Jeremie; Hajdukova, Maria; Li, Gongjie

2016-10-01

Introduction: One of the greatest successes of the Einstein's General Theory of Relativity (GR) was the correct prediction of the precession of perihelion of Mercury. The closed form expression to compute this precession tells us that substantial GR precession would occur only if the bodies have a combination of both moderately small perihelion distance and semi-major axis. Minimum Orbit Intersection Distance (MOID) is a quantity which helps us to understand the closest proximity of two orbits in space. Hence evaluating MOID is crucial to understand close encounters and collision scenarios better. In this work, we look at the possible scenarios where a small GR precession in argument of pericentre (ω) can create substantial changes in MOID for small bodies ranging from meteoroids to comets and asteroids.Analytical Approach and Numerical Integrations: Previous works have looked into neat analytical techniques to understand different collision scenarios and we use those standard expressions to compute MOID analytically. We find the nature of this mathematical function is such that a relatively small GR precession can lead to drastic changes in MOID values depending on the initial value of ω. Numerical integrations were done with package MERCURY incorporating the GR code to test the same effects. Numerical approach showed the same interesting relationship (as shown by analytical theory) between values of ω and the peaks/dips in MOID values. Previous works have shown that GR precession suppresses Kozai oscillations and this aspect was verified using our integrations. There is an overall agreement between both analytical and numerical methods.Summary and Discussion: We find that GR precession could play an important role in the calculations pertaining to MOID and close encounter scenarios in the case of certain small solar system bodies (depending on their initial orbital elements). Previous works have looked into impact probabilities and collision scenarios on planets from different small body populations. This work aims to find certain sub-sets of orbits where GR could play an interesting role. Certain parallels are drawn between the cases of asteroids, comets and small perihelion distance meteoroid streams.

Finite difference elastic wave modeling with an irregular free surface using ADER scheme

NASA Astrophysics Data System (ADS)

Almuhaidib, Abdulaziz M.; Nafi Toksöz, M.

2015-06-01

In numerical modeling of seismic wave propagation in the earth, we encounter two important issues: the free surface and the topography of the surface (i.e. irregularities). In this study, we develop a 2D finite difference solver for the elastic wave equation that combines a 4th- order ADER scheme (Arbitrary high-order accuracy using DERivatives), which is widely used in aeroacoustics, with the characteristic variable method at the free surface boundary. The idea is to treat the free surface boundary explicitly by using ghost values of the solution for points beyond the free surface to impose the physical boundary condition. The method is based on the velocity-stress formulation. The ultimate goal is to develop a numerical solver for the elastic wave equation that is stable, accurate and computationally efficient. The solver treats smooth arbitrary-shaped boundaries as simple plane boundaries. The computational cost added by treating the topography is negligible compared to flat free surface because only a small number of grid points near the boundary need to be computed. In the presence of topography, using 10 grid points per shortest shear-wavelength, the solver yields accurate results. Benchmark numerical tests using several complex models that are solved by our method and other independent accurate methods show an excellent agreement, confirming the validity of the method for modeling elastic waves with an irregular free surface.

Frontcountry encounter norms among three cultures

Treesearch

Jerry J. Vaske; Maureen P. Donnelly; Robert M. Doctor; James P. Petruzzi

1995-01-01

Existing normative studies have focused on backcountry encounter norms reported by North Americans. This study extends previous research by comparing encounter norms reported by three different cultures - North Americans, Europeans, and Japanese - in a frontcountry day use recreation area. Data were obtained from on-site surveys distributed at the Columbia Icefield in...

Computational reacting gas dynamics

NASA Technical Reports Server (NTRS)

Lam, S. H.

1993-01-01

In the study of high speed flows at high altitudes, such as that encountered by re-entry spacecrafts, the interaction of chemical reactions and other non-equilibrium processes in the flow field with the gas dynamics is crucial. Generally speaking, problems of this level of complexity must resort to numerical methods for solutions, using sophisticated computational fluid dynamics (CFD) codes. The difficulties introduced by reacting gas dynamics can be classified into three distinct headings: (1) the usually inadequate knowledge of the reaction rate coefficients in the non-equilibrium reaction system; (2) the vastly larger number of unknowns involved in the computation and the expected stiffness of the equations; and (3) the interpretation of the detailed reacting CFD numerical results. The research performed accepts the premise that reacting flows of practical interest in the future will in general be too complex or 'untractable' for traditional analytical developments. The power of modern computers must be exploited. However, instead of focusing solely on the construction of numerical solutions of full-model equations, attention is also directed to the 'derivation' of the simplified model from the given full-model. In other words, the present research aims to utilize computations to do tasks which have traditionally been done by skilled theoreticians: to reduce an originally complex full-model system into an approximate but otherwise equivalent simplified model system. The tacit assumption is that once the appropriate simplified model is derived, the interpretation of the detailed numerical reacting CFD numerical results will become much easier. The approach of the research is called computational singular perturbation (CSP).

Demanding Patient or Demanding Encounter?: A Case Study of a Cancer Clinic

PubMed Central

Stacey, Clare Louise; Henderson, Stuart; MacArthur, Kelly R; Dohan, Daniel

2009-01-01

This paper explores the sociological relevance of demanding encounters between doctors and patients. Borrowing from Potter and McKinlay's (2005) reconceptualization of the doctor-patient relationship, we suggest an analytic shift away from `demanding patients' toward `demanding encounters'. Such a shift places provider-patient conflict within a broader sociocultural context, emphasizing constraints facing both doctor and patient as they interact in a clinical setting. Specifically, through an ethnographic study of doctor-patient interactions at the oncology clinic of a US University Hospital, we examine the respective influences of new information technologies and patient consumerism in the production of demanding encounters in oncology. Findings suggest that these interconnected socio-cultural realities, in tandem with patient tendencies to challenge physician judgment or expertise, play a role in demanding encounters. We conclude by considering the implications of demanding encounters for doctors, patients and healthcare organizations. PMID:19619924

Sources of noise in magneto-optical readout

NASA Technical Reports Server (NTRS)

Mansuripur, M.

1991-01-01

The various sources of noise which are often encountered in magneto-optical readout systems are analyzed. Although the focus is on magneto-optics, most sources of noise are common among the various optical recording systems and one can easily adapt the results to other media and systems. A description of the magneto-optical readout system under consideration is given, and the standard methods and the relevant terminology of signal and noise measurement are described. The characteristics of thermal noise, which originates in the electronic circuitry of the readout system, are described. The most fundamental of all sources of noise, the shot noise, is considered, and a detailed account of its statistical properties is given. Shot noise, which is due to random fluctuations in photon arrival times, is an ever-present noise in optical detection. Since the performance of magneto-optical recording devices in use today is approaching the limit imposed by the shot noise, it is important that the reader have a good grasp of this particular source of noise. A model for the laser noise is described, and measurement results which yield numerical values for the strength of the laser power fluctuations are presented. Spatial variations of the disk reflectivity and random depolarization phenomena also contribute to the overall level of noise in readout; these and related issues are treated. Numerical simulation results describing some of the more frequently encountered sources of noise which accompany the recorded waveform itself, namely, jitter noise and signal-amplitude fluctuation noise are presented.

Constitutive modeling of aluminum foam and finite element implementation for crash simulations

NASA Astrophysics Data System (ADS)

Bi, Jing

In the past decades metallic foams have been increasingly used as filler materials in crashworthiness applications due to their relatively low cost and high capacity of energy absorption. Due to the destructive nature of crashes, studies on the performance of metallic foams using physical testing have been limited to examining the crushing force histories and/or folding patterns that are insufficient for crashworthiness designs. For this reason, numerical simulations, particularly nonlinear finite element (FE) analyses, play an important role in designing crashworthy foam-filled structures. An effective and numerically stable model is needed for modeling metallic foams that are porous and encounter large nonlinear deformations in crashes. In this study a new constitutive model for metallic foams is developed to overcome the deficiency of existing models in commercial FE codes such as LS-DYNA. The new constitutive model accounts for volume changes under hydrostatic compression and combines the hydrostatic pressure and von Mises stress into one yield function. The change of the compressibility of the metallic foam is handled in the constitutive model by allowing for shape changes of the yield surface in the hydrostatic pressure-von Mises stress space. The backward Euler method is adopted to integrate the constitutive equations to achieve numerical accuracy and stability. The new foam model is verified and validated by existing experimental data before used in FE simulations of crushing of foam-filled columns that have square and hexagonal cross-sections.

Evaluation of Pharmacists' Work in a Physician-Pharmacist Collaborative Model for the Management of Hypertension.

PubMed

Isetts, Brian J; Buffington, Daniel E; Carter, Barry L; Smith, Marie; Polgreen, Linnea A; James, Paul A

2016-04-01

Physician-pharmacist collaborative models have been shown to improve the care of patients with numerous chronic medical conditions. Team-based health care using integrated clinical pharmacists provides one opportunity to improve quality in health care systems that use population-based financing. In November 2015, the Centers for Medicare and Medicaid Services (CMS) requested that the relative value of pharmacists' work in team-based care needs to be established. Thus the objective of this study was to describe the components of pharmacists' work in the management of hypertension with a physician-pharmacist collaborative model. Descriptive analysis of the components of pharmacists' work in the Collaboration Among Pharmacists and Physicians to Improve Outcomes Now (CAPTION) study, a prospective, cluster randomized trial. This analysis was intended to provide policymakers with data and information, using the CAPTION study model, on the time and intensity of pharmacists' work to understand pharmacists' relative value contributions in the context of CMS financing and population management aims. The CAPTION trial was conducted in 32 community-based medical offices in 15 U.S. states and included 390 patients with multiple cardiovascular risk factors. Blood pressure was measured by trained study coordinators in each office, and patients were included in the study if they had uncontrolled blood pressure. Included patients were randomized to a 9-month intervention, a 24-month intervention, or usual care. The goal of the pharmacist intervention was to improve blood pressure control and resolve drug therapy problems impeding progress toward blood pressure goals. This intervention included medical record review, a structured assessment with the patient, collaboration to achieve goals of therapy, and patient follow-up. The two intervention arms (9 and 24 mo) were identical the first 9 months, and that time frame is the focus of this workload evaluation. Pharmacists completed study encounter forms for every patient encounter and estimated time spent in pre-visit, face-to-face care, and post-visit activities. Among the 390 patients, there were 2811 encounters with pharmacists that involved 3.44 hours/patient for face-to-face care visits plus 1.55 hours/patient for pre-visit and post-visit work. Intensity of work was reflected in interventions to resolve drug therapy problems with patients (43% of encounters) and with physicians (1169 recommendations, of which physicians accepted 1153 [98.6%]), resulting in improvement of patients' blood pressure goals achieved (from 0% at baseline to 43% at 9 months based on the primary study end point). Pharmacists provided extensive interventions to patients with hypertension. This analysis provides a framework for health systems, provider groups, and payers to measure pharmacists' work in value-based financing and population management. © 2016 Pharmacotherapy Publications, Inc.

High Order Numerical Methods for LES of Turbulent Flows with Shocks

NASA Technical Reports Server (NTRS)

Kotov, D. V.; Yee, H. C.; Hadjadj, A.; Wray, A.; Sjögreen, B.

2014-01-01

Simulation of turbulent flows with shocks employing explicit subgrid-scale (SGS) filtering may encounter a loss of accuracy in the vicinity of a shock. In this work we perform a comparative study of different approaches to reduce this loss of accuracy within the framework of the dynamic Germano SGS model. One of the possible approaches is to apply Harten's subcell resolution procedure to locate and sharpen the shock, and to use a one-sided test filter at the grid points adjacent to the exact shock location. The other considered approach is local disabling of the SGS terms in the vicinity of the shock location. In this study we use a canonical shock-turbulence interaction problem for comparison of the considered modifications of the SGS filtering procedure. For the considered test case both approaches show a similar improvement in the accuracy near the shock.

Some lessons from NACA/NASA aerodynamic studies following World War II

NASA Technical Reports Server (NTRS)

Spearman, M. L.

1983-01-01

An historical account is presented of the new departures in aerodynamic research conducted by NACA, and subsequently NASA, as a result of novel aircraft technologies and operational regimes encountered in the course of the Second World War. The invention and initial development of the turbojet engine furnished the basis for a new speed/altitude regime in which numerous aerodynamic design problems arose. These included compressibility effects near the speed of sound, with attendant lift/drag efficiency reductions and longitudinal stability enhancements that were accompanied by a directional stability reduction. Major research initiatives were mounted in the investigation of swept, delta, trapezoidal and variable sweep wing configurations, sometimes conducted through flight testing of the 'X-series' aircraft. Attention is also given to the development of the first generation of supersonic fighter aircraft.

Patient perspectives of telemedicine quality

PubMed Central

LeRouge, Cynthia M; Garfield, Monica J; Hevner, Alan R

2015-01-01

Background The purpose of this study was to explore the quality attributes required for effective telemedicine encounters from the perspective of the patient. Methods We used a multi-method (direct observation, focus groups, survey) field study to collect data from patients who had experienced telemedicine encounters. Multi-perspectives (researcher and provider) were used to interpret a rich set of data from both a research and practice perspective. Results The result of this field study is a taxonomy of quality attributes for telemedicine service encounters that prioritizes the attributes from the patient perspective. We identify opportunities to control the level of quality for each attribute (ie, who is responsible for control of each attribute and when control can be exerted in relation to the encounter process). This analysis reveals that many quality attributes are in the hands of various stakeholders, and all attributes can be addressed proactively to some degree before the encounter begins. Conclusion Identification of the quality attributes important to a telemedicine encounter from a patient perspective enables one to better design telemedicine encounters. This preliminary work not only identifies such attributes, but also ascertains who is best able to address quality issues prior to an encounter. For practitioners, explicit representation of the quality attributes of technology-based systems and processes and insight on controlling key attributes are essential to implementation, utilization, management, and common understanding. PMID:25565781

Impact risk assessment and planetary defense mission planning for asteroid 2015 PDC

NASA Astrophysics Data System (ADS)

Vardaxis, George; Sherman, Peter; Wie, Bong

2016-05-01

In this paper, an integrated utilization of analytic keyhole theory, B-plane mapping, and planetary encounter geometry, augmented by direct numerical simulation, is shown to be useful in determining the impact risk of an asteroid with the Earth on a given encounter, as well on potential future encounters via keyhole passages. The accurate estimation of the impact probability of hazardous asteroids is extremely important for planetary defense mission planning. Asteroids in Earth resonant orbits are particularly troublesome because of the continuous threat they pose in the future. Based on the trajectories of the asteroid and the Earth, feasible mission trajectories can be found to mitigate the impact threat of hazardous asteroids. In order to try to ensure mission success, trajectories are judged based on initial and final mission design parameters that would make the mission easier to complete. Given the potential of a short-warning time scenario, a disruption mission considered in this paper occurs approximately one year prior to the anticipated impact date. Expanding upon the established theory, a computational method is developed to estimate the impact probability of the hazardous asteroid, in order to assess the likelihood of an event, and then investigate the fragmentation of the asteroid due to a disruption mission and analyze its effects on the current and future encounters of the fragments with Earth. A fictional asteroid, designated as 2015 PDC - created as an example asteroid risk exercise for the 2015 Planetary Defence Conference, is used as a reference target asteroid to demonstrate the effectiveness and applicability of computational tools being developed for impact risk assessment and planetary defense mission planning for a hazardous asteroid or comet.

Sampling design trade-offs in occupancy studies with imperfect detection: examples and software

USGS Publications Warehouse

Bailey, L.L.; Hines, J.E.; Nichols, J.D.

2007-01-01

Researchers have used occupancy, or probability of occupancy, as a response or state variable in a variety of studies (e.g., habitat modeling), and occupancy is increasingly favored by numerous state, federal, and international agencies engaged in monitoring programs. Recent advances in estimation methods have emphasized that reliable inferences can be made from these types of studies if detection and occupancy probabilities are simultaneously estimated. The need for temporal replication at sampled sites to estimate detection probability creates a trade-off between spatial replication (number of sample sites distributed within the area of interest/inference) and temporal replication (number of repeated surveys at each site). Here, we discuss a suite of questions commonly encountered during the design phase of occupancy studies, and we describe software (program GENPRES) developed to allow investigators to easily explore design trade-offs focused on particularities of their study system and sampling limitations. We illustrate the utility of program GENPRES using an amphibian example from Greater Yellowstone National Park, USA.

Making a difference: initiating and maintaining a faith-based free health clinic.

PubMed

Dunn, Linda L

2009-01-01

This article is a summary of the challenges, struggles, and barriers that a group of churches encountered in developing a faith-based free health clinic. From the inception, this clinic has existed for the uninsured whose total household income aligns with the 2009 Fedral Poverty Guidelines. A voluntary interview with the executive director of The Good Samaritan Clinic revealed the experiential evolvement of this free health clinic. Numerous examples are shared that depict how this clinic has made a difference in the lives of many people.

Inversion of very large matrices encountered in large scale problems of photogrammetry and photographic astrometry

NASA Technical Reports Server (NTRS)

Brown, D. C.

1971-01-01

The simultaneous adjustment of very large nets of overlapping plates covering the celestial sphere becomes computationally feasible by virtue of a twofold process that generates a system of normal equations having a bordered-banded coefficient matrix, and solves such a system in a highly efficient manner. Numerical results suggest that when a well constructed spherical net is subjected to a rigorous, simultaneous adjustment, the exercise of independently established control points is neither required for determinancy nor for production of accurate results.

An adaptive robust controller for time delay maglev transportation systems

NASA Astrophysics Data System (ADS)

Milani, Reza Hamidi; Zarabadipour, Hassan; Shahnazi, Reza

2012-12-01

For engineering systems, uncertainties and time delays are two important issues that must be considered in control design. Uncertainties are often encountered in various dynamical systems due to modeling errors, measurement noises, linearization and approximations. Time delays have always been among the most difficult problems encountered in process control. In practical applications of feedback control, time delay arises frequently and can severely degrade closed-loop system performance and in some cases, drives the system to instability. Therefore, stability analysis and controller synthesis for uncertain nonlinear time-delay systems are important both in theory and in practice and many analytical techniques have been developed using delay-dependent Lyapunov function. In the past decade the magnetic and levitation (maglev) transportation system as a new system with high functionality has been the focus of numerous studies. However, maglev transportation systems are highly nonlinear and thus designing controller for those are challenging. The main topic of this paper is to design an adaptive robust controller for maglev transportation systems with time-delay, parametric uncertainties and external disturbances. In this paper, an adaptive robust control (ARC) is designed for this purpose. It should be noted that the adaptive gain is derived from Lyapunov-Krasovskii synthesis method, therefore asymptotic stability is guaranteed.

PubMed Central

Perreault, C

1981-01-01

Human leukocyte antigens (HLA) are transmembrane bicatenar glycoproteins; their heavy chain is coded by chromosome 6 and carries allotypic determinants. These molecules are present in nearly every cell, tissue and biologic fluid. Their congenital absence from fibroblasts is associated with progeria, while their absence from lymphocytes is associated with immunodeficiency. HLA antigens are usually studied microlymphocytotoxicity tests. The numerous cross-reactions encountered make the interpretation of results quite difficult. To clearly understand these reactions a complex-complex model is mandatory. The antigen, the HLA molecule, is complex since it carries many antigenic determinants; some of them are private ("subtypic"), while others are public ("subtypic"). Anti-HLA antibodies are also complex since they are heterogeneous, reacting with variable affinity with different antigenic determinants. The in vitro cross-reactions represent a partial explanation for varying cross-immunogenicity in vivo. PMID:7008927

On boredom: a close encounter with encapsulated parts of the psyche.

PubMed

Bergstein, Avner

2009-06-01

The psychoanalytical literature has numerous scattered references to the analyst's experience of boredom, especially amongst writers working with primitive mental states. In the present paper, the author tries to gather some of these references in an attempt to integrate the various facets of this widespread phenomenon, and reflect on some clinical issues and dilemmas it raises. It is suggested that the experience of boredom in analysis may be a reaction to an encounter with a hidden, encapsulated part of the psyche, a bidimensional area of experience in which mental activity has been suspended, and experience remains meaningless. This is a barren area of lack, an encounter with the autistic core of the psyche. However, boredom may also be an experiential expression of despair, a re-living of primitive object relations with an emotionally non-existent primary object. Through bringing the emptiness and desolation into analysis, the individual makes room for the empty, blunt, dead inner object which resides within him, and that needs to be integrated into the psyche. This inner object is a vital part of the patient's inner world, part of his history, and can neither be erased nor filled in order to eradicate the emptiness. This is illustrated by clinical material from patients along the spectrum of autism, autistic reaction following trauma and autistic barriers in neurotic patients.

Dynamics of protein-protein encounter: a Langevin equation approach with reaction patches.

PubMed

Schluttig, Jakob; Alamanova, Denitsa; Helms, Volkhard; Schwarz, Ulrich S

2008-10-21

We study the formation of protein-protein encounter complexes with a Langevin equation approach that considers direct, steric, and thermal forces. As three model systems with distinctly different properties we consider the pairs barnase:barstar, cytochrome c-cytochrome c peroxidase, and p53:MDM2. In each case, proteins are modeled either as spherical particles, as dipolar spheres, or as collection of several small beads with one dipole. Spherical reaction patches are placed on the model proteins according to the known experimental structures of the protein complexes. In the computer simulations, concentration is varied by changing box size. Encounter is defined as overlap of the reaction patches and the corresponding first passage times are recorded together with the number of unsuccessful contacts before encounter. We find that encounter frequency scales linearly with protein concentration, thus proving that our microscopic model results in a well-defined macroscopic encounter rate. The number of unsuccessful contacts before encounter decreases with increasing encounter rate and ranges from 20 to 9000. For all three models, encounter rates are obtained within one order of magnitude of the experimentally measured association rates. Electrostatic steering enhances association up to 50-fold. If diffusional encounter is dominant (p53:MDM2) or similarly important as electrostatic steering (barnase:barstar), then encounter rate decreases with decreasing patch radius. More detailed modeling of protein shapes decreases encounter rates by 5%-95%. Our study shows how generic principles of protein-protein association are modulated by molecular features of the systems under consideration. Moreover it allows us to assess different coarse-graining strategies for the future modeling of the dynamics of large protein complexes.

Dynamics of protein-protein encounter: A Langevin equation approach with reaction patches

NASA Astrophysics Data System (ADS)

Schluttig, Jakob; Alamanova, Denitsa; Helms, Volkhard; Schwarz, Ulrich S.

2008-10-01

We study the formation of protein-protein encounter complexes with a Langevin equation approach that considers direct, steric, and thermal forces. As three model systems with distinctly different properties we consider the pairs barnase:barstar, cytochrome c-cytochrome c peroxidase, and p53:MDM2. In each case, proteins are modeled either as spherical particles, as dipolar spheres, or as collection of several small beads with one dipole. Spherical reaction patches are placed on the model proteins according to the known experimental structures of the protein complexes. In the computer simulations, concentration is varied by changing box size. Encounter is defined as overlap of the reaction patches and the corresponding first passage times are recorded together with the number of unsuccessful contacts before encounter. We find that encounter frequency scales linearly with protein concentration, thus proving that our microscopic model results in a well-defined macroscopic encounter rate. The number of unsuccessful contacts before encounter decreases with increasing encounter rate and ranges from 20 to 9000. For all three models, encounter rates are obtained within one order of magnitude of the experimentally measured association rates. Electrostatic steering enhances association up to 50-fold. If diffusional encounter is dominant (p53:MDM2) or similarly important as electrostatic steering (barnase:barstar), then encounter rate decreases with decreasing patch radius. More detailed modeling of protein shapes decreases encounter rates by 5%-95%. Our study shows how generic principles of protein-protein association are modulated by molecular features of the systems under consideration. Moreover it allows us to assess different coarse-graining strategies for the future modeling of the dynamics of large protein complexes.

GASP cloud- and particle-encounter statistics and their application to LPC aircraft studies. Volume 1: Analysis and conclusions

NASA Technical Reports Server (NTRS)

Jasperson, W. H.; Nastrom, G. D.; Davis, R. E.; Holdeman, J. D.

1984-01-01

Summary studies are presented for the entire cloud observation archieve from the NASA Global Atmospheric Sampling Program (GASP). Studies are also presented for GASP particle concentration data gathered concurrently with the cloud observations. Cloud encounters are shown on about 15 percent of the data samples overall, but the probability of cloud encounter is shown to vary significantly with altitude, latitude, and distance from the tropopause. Several meteorological circulation features are apparent in the latitudinal distribution of cloud cover, and the cloud encounter statistics are shown to be consistent with the classical mid-latitude cyclone model. Observations of clouds spaced more closely than 90 minutes are shown to be statistically dependent. The statistics for cloud and particle encounter are utilized to estimate the frequency of cloud encounter on long range airline routes, and to assess the probability and extent of laminar flow loss due to cloud or particle encounter by aircraft utilizing laminar flow control (LFC). It is shown that the probability of extended cloud encounter is too low, of itself, to make LFC impractical.

Computer simulation of concentrated solid solution strengthening

NASA Technical Reports Server (NTRS)

Kuo, C. T. K.; Arsenault, R. J.

1976-01-01

The interaction forces between a straight edge dislocation moving through a three-dimensional block containing a random array of solute atoms were determined. The yield stress at 0 K was obtained by determining the average maximum solute-dislocation interaction force that is encountered by edge dislocation, and an expression relating the yield stress to the length of the dislocation and the solute concentration is provided. The magnitude of the solid solution strengthening due to solute atoms can be determined directly from the numerical results, provided the dislocation line length that moves as a unit is specified.

Medical Identity Theft in the Emergency Department: Awareness is Crucial

PubMed Central

Mancini, Michelino

2014-01-01

Medical Identity theft in the emergency department (ED) can harm numerous individuals, and many frontline healthcare providers are unaware of this growing concern. The two cases described began as typical ED encounters until red flags were discovered upon validating the patient’s identity. Educating all healthcare personnel within and outside the ED regarding the subtle signs of medical identity theft and implementing institutional policies to identify these criminals will discourage further fraudulent behavior. PMID:25493150

Rigour in quantitative research.

PubMed

Claydon, Leica Sarah

2015-07-22

This article which forms part of the research series addresses scientific rigour in quantitative research. It explores the basis and use of quantitative research and the nature of scientific rigour. It examines how the reader may determine whether quantitative research results are accurate, the questions that should be asked to determine accuracy and the checklists that may be used in this process. Quantitative research has advantages in nursing, since it can provide numerical data to help answer questions encountered in everyday practice.

A domain-specific compiler for a parallel multiresolution adaptive numerical simulation environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajbhandari, Samyam; Kim, Jinsung; Krishnamoorthy, Sriram

This paper describes the design and implementation of a layered domain-specific compiler to support MADNESS---Multiresolution ADaptive Numerical Environment for Scientific Simulation. MADNESS is a high-level software environment for the solution of integral and differential equations in many dimensions, using adaptive and fast harmonic analysis methods with guaranteed precision. MADNESS uses k-d trees to represent spatial functions and implements operators like addition, multiplication, differentiation, and integration on the numerical representation of functions. The MADNESS runtime system provides global namespace support and a task-based execution model including futures. MADNESS is currently deployed on massively parallel supercomputers and has enabled many science advances.more » Due to the highly irregular and statically unpredictable structure of the k-d trees representing the spatial functions encountered in MADNESS applications, only purely runtime approaches to optimization have previously been implemented in the MADNESS framework. This paper describes a layered domain-specific compiler developed to address some performance bottlenecks in MADNESS. The newly developed static compile-time optimizations, in conjunction with the MADNESS runtime support, enable significant performance improvement for the MADNESS framework.« less

A general theory for the Uranian satellites

NASA Technical Reports Server (NTRS)

Laskar, J.

1986-01-01

A general analytical theory of the five main satellites of Uranus, including the secular and short period terms hereafter denoted by GUST, is presented. A comparison is made with an internal numerical integration with nominal masses of Veillet (1983). The precision of the theory goes from about 10 km for Miranda to 100 km for Oberon. The short period terms in the motions of Titania and Oberon are larger than 500 km. They should make possible the determination of the masses of the outer satellites through the optical data of Voyager encounter.

Application of the Kishimoto-Tamura boson expansion theory to a single-j shell model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, C.T.; Pedrocchi, V.G.; Tamura, T.

1985-11-01

The boson expansion theory of Kishimoto and Tamura is applied to a single-j shell model. It is shown that this theory is quite accurate, giving results that agree very closely with those of the exact fermion calculations. The fast convergence of the boson expansion is also demonstrated. A critical discussion is then made of an earlier paper by Arima, in which he stated that the Kishimoto-Tamura theory gives rise to very poor numerical results. The source of the trouble encountered by Arima is unmasked.

GPU Acceleration of DSP for Communication Receivers.

PubMed

Gunther, Jake; Gunther, Hyrum; Moon, Todd

2017-09-01

Graphics processing unit (GPU) implementations of signal processing algorithms can outperform CPU-based implementations. This paper describes the GPU implementation of several algorithms encountered in a wide range of high-data rate communication receivers including filters, multirate filters, numerically controlled oscillators, and multi-stage digital down converters. These structures are tested by processing the 20 MHz wide FM radio band (88-108 MHz). Two receiver structures are explored: a single channel receiver and a filter bank channelizer. Both run in real time on NVIDIA GeForce GTX 1080 graphics card.

Changes in Payer Mix and Physician Reimbursement After the Affordable Care Act and Medicaid Expansion.

PubMed

Jones, Christine D; Scott, Serena J; Anoff, Debra L; Pierce, Read G; Glasheen, Jeffrey J

2015-01-01

Although uncompensated care for hospital-based care has fallen dramatically since the implementation of the Affordable Care Act and Medicaid expansion, the changes in hospital physician reimbursement are not known. We evaluated if payer mix and physician reimbursement by encounter changed between 2013 and 2014 in an academic hospitalist practice in a Medicaid expansion state. This was a retrospective cohort study of all general medicine inpatient admissions to an academic hospitalist group in 2013 and 2014. The proportion of encounters by payer and reimbursement/inpatient encounter were compared in 2013 versus 2014. A sensitivity analysis determined the relative contribution of different factors to the change in reimbursement/encounter. Among 37 540 and 40 397 general medicine inpatient encounters in 2013 and 2014, respectively, Medicaid encounters increased (17.3% to 30.0%, P < .001), uninsured encounters decreased (18.4% to 6.3%, P < 0.001), and private payer encounters also decreased (14.1% to 13.3%, P = .001). The median reimbursement/encounter increased 4.2% from $79.98/encounter in 2013 to $83.36/encounter in 2014 (P < .001). In a sensitivity analysis, changes in length of stay, proportions in encounter type by payer, payer mix, and reimbursement for encounter type by payer accounted for -0.7%, 0.8%, 2.0%, and 2.3% of the reimbursement change, respectively. From 2013 to 2014, Medicaid encounters increased, and uninsured and private payer encounters decreased within our hospitalist practice. Reimbursement/encounter also increased, much of which could be attributed to a change in payer mix. Further analyses of physician reimbursement in Medicaid expansion and non-expansion states would further delineate reimbursement changes that are directly attributable to Medicaid expansion. © The Author(s) 2015.

Changes in Payer Mix and Physician Reimbursement After the Affordable Care Act and Medicaid Expansion

PubMed Central

Jones, Christine D.; Scott, Serena J.; Anoff, Debra L.; Pierce, Read G.; Glasheen, Jeffrey J.

2015-01-01

Although uncompensated care for hospital-based care has fallen dramatically since the implementation of the Affordable Care Act and Medicaid expansion, the changes in hospital physician reimbursement are not known. We evaluated if payer mix and physician reimbursement by encounter changed between 2013 and 2014 in an academic hospitalist practice in a Medicaid expansion state. This was a retrospective cohort study of all general medicine inpatient admissions to an academic hospitalist group in 2013 and 2014. The proportion of encounters by payer and reimbursement/inpatient encounter were compared in 2013 versus 2014. A sensitivity analysis determined the relative contribution of different factors to the change in reimbursement/encounter. Among 37 540 and 40 397 general medicine inpatient encounters in 2013 and 2014, respectively, Medicaid encounters increased (17.3% to 30.0%, P < .001), uninsured encounters decreased (18.4% to 6.3%, P < 0.001), and private payer encounters also decreased (14.1% to 13.3%, P = .001). The median reimbursement/encounter increased 4.2% from $79.98/encounter in 2013 to $83.36/encounter in 2014 (P < .001). In a sensitivity analysis, changes in length of stay, proportions in encounter type by payer, payer mix, and reimbursement for encounter type by payer accounted for −0.7%, 0.8%, 2.0%, and 2.3% of the reimbursement change, respectively. From 2013 to 2014, Medicaid encounters increased, and uninsured and private payer encounters decreased within our hospitalist practice. Reimbursement/encounter also increased, much of which could be attributed to a change in payer mix. Further analyses of physician reimbursement in Medicaid expansion and non-expansion states would further delineate reimbursement changes that are directly attributable to Medicaid expansion. PMID:26310500

Change in Minimum Orbit Intersection Distance due to General Relativistic Precession in Small Solar System Bodies

NASA Astrophysics Data System (ADS)

Sekhar, Aswin; Valsecchi, Giovanni B.; Asher, David; Werner, Stephanie; Vaubaillon, Jeremie; Li, Gongjie

2017-06-01

One of the greatest successes of Einstein's General Theory of Relativity (GR) was the correct prediction of the perihelion precession of Mercury. The closed form expression to compute this precession tells us that substantial GR precession would occur only if the bodies have a combination of both moderately small perihelion distance and semi-major axis. Minimum Orbit Intersection Distance (MOID) is a quantity which helps us to understand the closest proximity of two orbits in space. Hence evaluating MOID is crucial to understand close encounters and collision scenarios better. In this work, we look at the possible scenarios where a small GR precession in argument of pericentre can create substantial changes in MOID for small bodies ranging from meteoroids to comets and asteroids.Previous works have looked into neat analytical techniques to understand different collision scenarios and we use those standard expressions to compute MOID analytically. We find the nature of this mathematical function is such that a relatively small GR precession can lead to drastic changes in MOID values depending on the initial value of argument of pericentre. Numerical integrations were done with the MERCURY package incorporating GR code to test the same effects. A numerical approach showed the same interesting relationship (as shown by analytical theory) between values of argument of pericentre and the peaks or dips in MOID values. There is an overall agreement between both analytical and numerical methods.We find that GR precession could play an important role in the calculations pertaining to MOID and close encounter scenarios in the case of certain small solar system bodies (depending on their initial orbital elements) when long term impact risk possibilities are considered. Previous works have looked into impact probabilities and collision scenarios on planets from different small body populations. This work aims to find certain sub-sets of small bodies where GR could play an interesting role. Certain parallels are drawn between the cases of asteroids, comets and small perihelion distance meteoroid streams.

Development of Numerical Extended Hydrodynamics for Transition-Regime Non-Equilibrium Flows Encountered in Semiconductor Manufacturing Processes

NASA Technical Reports Server (NTRS)

Groth, Clinton P. T.; Roe, Philip L.

1998-01-01

Six months of funding was received for the proposed three year research program (funding for the period from March 1, 1997 to August 31, 1997). Although the official starting date for the project was March 1, 1997, no funding for the project was received until July 1997. In the funded research period, considerable progress was made on Phase I of the proposed research program. The initial research efforts concentrated on applying the 10-, 20-, and 35-moment Gaussian-based closures to a series of standard two-dimensional non-reacting single species test flow problems, such as the flat plate, couette, channel, and rearward facing step flows, and to some other two-dimensional flows having geometries similar to those encountered in chemical-vapor deposition (CVD) reactors. Eigensystem analyses for these systems for the case of two spatial dimensions was carried out and efficient formulations of approximate Riemann solvers have been formulated using these eigenstructures. Formulations to include rotational non-equilibrium effects into the moment closure models for the treatment of polyatomic gases were explored, as the original formulations of the closure models were developed strictly for gases composed of monatomic molecules. The development of a software library and computer code for solving relaxing hyperbolic systems in two spatial dimensions of the type arising from the closure models was also initiated. The software makes use of high-resolution upwind finite-volumes schemes, multi-stage point implicit time stepping, and automatic adaptive mesh refinement (AMR) to solve the governing conservation equations for the moment closures. The initial phase of the code development was completed and a numerical investigation of the solutions of the 10-moment closure model for the simple two-dimensional test cases mentioned above was initiated. Predictions of the 10-moment model were compared to available theoretical solutions and the results of direct-simulation Monte Carlo (DSMC) calculations. The first results of this study were presented at a meeting last year.

Implicit level set algorithms for modelling hydraulic fracture propagation.

PubMed

Peirce, A

2016-10-13

Hydraulic fractures are tensile cracks that propagate in pre-stressed solid media due to the injection of a viscous fluid. Developing numerical schemes to model the propagation of these fractures is particularly challenging due to the degenerate, hypersingular nature of the coupled integro-partial differential equations. These equations typically involve a singular free boundary whose velocity can only be determined by evaluating a distinguished limit. This review paper describes a class of numerical schemes that have been developed to use the multiscale asymptotic behaviour typically encountered near the fracture boundary as multiple physical processes compete to determine the evolution of the fracture. The fundamental concepts of locating the free boundary using the tip asymptotics and imposing the tip asymptotic behaviour in a weak form are illustrated in two quite different formulations of the governing equations. These formulations are the displacement discontinuity boundary integral method and the extended finite-element method. Practical issues are also discussed, including new models for proppant transport able to capture 'tip screen-out'; efficient numerical schemes to solve the coupled nonlinear equations; and fast methods to solve resulting linear systems. Numerical examples are provided to illustrate the performance of the numerical schemes. We conclude the paper with open questions for further research. This article is part of the themed issue 'Energy and the subsurface'. © 2016 The Author(s).

Implicit level set algorithms for modelling hydraulic fracture propagation

PubMed Central

2016-01-01

Hydraulic fractures are tensile cracks that propagate in pre-stressed solid media due to the injection of a viscous fluid. Developing numerical schemes to model the propagation of these fractures is particularly challenging due to the degenerate, hypersingular nature of the coupled integro-partial differential equations. These equations typically involve a singular free boundary whose velocity can only be determined by evaluating a distinguished limit. This review paper describes a class of numerical schemes that have been developed to use the multiscale asymptotic behaviour typically encountered near the fracture boundary as multiple physical processes compete to determine the evolution of the fracture. The fundamental concepts of locating the free boundary using the tip asymptotics and imposing the tip asymptotic behaviour in a weak form are illustrated in two quite different formulations of the governing equations. These formulations are the displacement discontinuity boundary integral method and the extended finite-element method. Practical issues are also discussed, including new models for proppant transport able to capture ‘tip screen-out’; efficient numerical schemes to solve the coupled nonlinear equations; and fast methods to solve resulting linear systems. Numerical examples are provided to illustrate the performance of the numerical schemes. We conclude the paper with open questions for further research.  This article is part of the themed issue ‘Energy and the subsurface’. PMID:27597787

Telephone Encounters Predict Future High Financial Expenditures in Inflammatory Bowel Disease Patients: A 3-Year Prospective Observational Study.

PubMed

Click, Benjamin; Anderson, Alyce M; Ramos Rivers, Claudia; Koutroubakis, Ioannis E; Hashash, Jana G; Dunn, Michael A; Schwartz, Marc; Swoger, Jason; Barrie, Arthur; Szigethy, Eva; Regueiro, Miguel; Schoen, Robert E; Binion, David G

2018-04-01

Telephone activity is essential in management of complex chronic diseases including inflammatory bowel disease (IBD). Telephone encounters logged in the electronic medical record have recently been proposed as a surrogate marker of disease activity and impending health care utilization; however, the association between telephone calls and financial expenditures has not been evaluated. We performed a 3-year prospective observational study of telephone encounters logged at a tertiary referral IBD center. We analyzed patient demographics, disease characteristics, comorbidities, clinical activity, and health care financial charges by telephone encounter frequency. Eight hundred one patients met inclusion criteria (52.3% female; mean age, 44.1 y), accounted for 12,669 telephone encounters, and accrued $70,513,449 in charges over 3 years. High telephone encounter frequency was associated with female gender (P=0.003), anxiety/depression (P<0.001), and prior IBD surgery (P<0.001). High telephone encounter categories had significantly more hospitalizations (P<0.001), IBD surgery (P<0.001), worse quality of life (P<0.001), more corticosteroid (P<0.001), biological (P<0.001), and opiate prescriptions (P<0.001). High telephone encounter frequency patients amassed higher total available charges in each year (P<0.001) and over the 3 years (P<0.001). Telephone encounters in 2009 (P=0.02) and 2010 (P<0.001) were significantly associated with financial charges the following year after controlling for demographic, utilization, and medication covariates. Increased telephone encounters are associated with significantly higher health care utilization and financial expenditures. Increased call frequency is predictive of future health care spending. Telephone encounters are a useful tool to identify patients at risk of clinical deterioration and large financial expense.

Wild immunology assessed by multidimensional mass cytometry.

PubMed

Japp, Alberto Sada; Hoffmann, Kerstin; Schlickeiser, Stephan; Glauben, Rainer; Nikolaou, Christos; Maecker, Holden T; Braun, Julian; Matzmohr, Nadine; Sawitzki, Birgit; Siegmund, Britta; Radbruch, Andreas; Volk, Hans-Dieter; Frentsch, Marco; Kunkel, Desiree; Thiel, Andreas

2017-01-01

A great part of our knowledge on mammalian immunology has been established in laboratory settings. The use of inbred mouse strains enabled controlled studies of immune cell and molecule functions in defined settings. These studies were usually performed in specific-pathogen free (SPF) environments providing standardized conditions. In contrast, mammalians including humans living in their natural habitat are continuously facing pathogen encounters throughout their life. The influences of environmental conditions on the signatures of the immune system and on experimental outcomes are yet not well defined. Thus, the transferability of results obtained in current experimental systems to the physiological human situation has always been a matter of debate. Studies elucidating the diversity of "wild immunology" imprintings in detail and comparing it with those of "clean" lab mice are sparse. Here, we applied multidimensional mass cytometry to dissect phenotypic and functional differences between distinct groups of laboratory and pet shop mice as a source for "wild mice". For this purpose, we developed a 31-antibody panel for murine leukocyte subsets identification and a 35-antibody panel assessing various cytokines. Established murine leukocyte populations were easily identified and diverse immune signatures indicative of numerous pathogen encounters were classified particularly in pet shop mice and to a lesser extent in quarantine and non-SPF mice as compared to SPF mice. In addition, unsupervised analysis identified distinct clusters that associated strongly with the degree of pathogenic priming, including increased frequencies of activated NK cells and antigen-experienced B- and T-cell subsets. Our study unravels the complexity of immune signatures altered under physiological pathogen challenges and highlights the importance of carefully adapting laboratory settings for immunological studies in mice, including drug and therapy testing. © 2016 International Society for Advancement of Cytometry. © 2016 International Society for Advancement of Cytometry.

Otoplasty: A graduated approach.

PubMed

Foda, H M

1999-01-01

Numerous otoplastic techniques have been described for the correction of protruding ears. Technique selection in otoplasty should be done only after careful analysis of the abnormal anatomy responsible for the protruding ear deformity. A graduated surgical approach is presented which is designed to address all contributing factors to the presenting auricular deformity. The approach starts with the more conservative cartilage-sparing suturing techniques, then proceeds to incorporate other more aggressive cartilage weakening maneuvers. Applying this approach resulted in better long-term results with less postoperative lateralization than that encountered on using the cartilage-sparing techniques alone.

Computational Challenges of Viscous Incompressible Flows

NASA Technical Reports Server (NTRS)

Kwak, Dochan; Kiris, Cetin; Kim, Chang Sung

2004-01-01

Over the past thirty years, numerical methods and simulation tools for incompressible flows have been advanced as a subset of the computational fluid dynamics (CFD) discipline. Although incompressible flows are encountered in many areas of engineering, simulation of compressible flow has been the major driver for developing computational algorithms and tools. This is probably due to the rather stringent requirements for predicting aerodynamic performance characteristics of flight vehicles, while flow devices involving low-speed or incompressible flow could be reasonably well designed without resorting to accurate numerical simulations. As flow devices are required to be more sophisticated and highly efficient CFD took become increasingly important in fluid engineering for incompressible and low-speed flow. This paper reviews some of the successes made possible by advances in computational technologies during the same period, and discusses some of the current challenges faced in computing incompressible flows.

Successes and Challenges of Incompressible Flow Simulation

NASA Technical Reports Server (NTRS)

Kwak, Dochan; Kiris, Cetin

2003-01-01

During the past thirty years, numerical methods and simulation tools for incompressible flows have been advanced as a subset of CFD discipline. Even though incompressible flows are encountered in many areas of engineering, simulation of compressible flow has been the major driver for developing computational algorithms and tools. This is probably due to rather stringent requirements for predicting aerodynamic performance characteristics of flight vehicles, while flow devices involving low speed or incompressible flow could be reasonably well designed without resorting to accurate numerical simulations. As flow devices are required to be more sophisticated and highly efficient, CFD tools become indispensable in fluid engineering for incompressible and low speed flow. This paper is intended to review some of the successes made possible by advances in computational technologies during the same period, and discuss some of the current challenges.

Numerical simulation of electrophoresis separation processes

NASA Technical Reports Server (NTRS)

Ganjoo, D. K.; Tezduyar, T. E.

1986-01-01

A new Petrov-Galerkin finite element formulation has been proposed for transient convection-diffusion problems. Most Petrov-Galerkin formulations take into account the spatial discretization, and the weighting functions so developed give satisfactory solutions for steady state problems. Though these schemes can be used for transient problems, there is scope for improvement. The schemes proposed here, which consider temporal as well as spatial discretization, provide improved solutions. Electrophoresis, which involves the motion of charged entities under the influence of an applied electric field, is governed by equations similiar to those encountered in fluid flow problems, i.e., transient convection-diffusion equations. Test problems are solved in electrophoresis and fluid flow. The results obtained are satisfactory. It is also expected that these schemes, suitably adapted, will improve the numerical solutions of the compressible Euler and the Navier-Stokes equations.

Title Requested

NASA Astrophysics Data System (ADS)

Ruzmaikina, T. V.

2000-12-01

Precise measurements of D/H in Halley and Hyakutake reveal larger excess of D than in Uranus and Neptune. This might imply that at least a fraction of Oort cloud comets have been accumulated in a cooler environment beyond the planetary system. This paper suggests that the scattering of planetesimals from the periphery of the protoplanetary disk by a passing star might have included them in the populating of the Oort cloud. The probability of the necessary close encounter is very small in the present Galactic environment of the solar system. However it might be relatively high if the solar system was formed in a denser environment, like the Rho Ophiuchus star-forming region or a small and dense cloud core which fragmented during the collapse to form a small group of stars. Outcomes of a passage of a star with mass 1 to 0.3 solar masses were studied numerically by Everhart method. Disk penetrating or disk grazing encounters revealed that planetesimals closest to the stellar trajectory can be ejected from the solar system or sent on highly eccentric bound orbits. Some planetesimals acquire orbits with perihelion distances larger than planet orbits, i.e., become immediate members of the Oort cloud. For others, external pertubations cause stochastic growth of perihelion distances and decoupling from the planetary system, transferring them into the Oort cloud. These Oort cloud bodies could be accumulated well beyond the planetary system, and preserve higher D/H, CO ice, etc.

Re-evaluation of an Optimized Second Order Backward Difference (BDF2OPT) Scheme for Unsteady Flow Applications

NASA Technical Reports Server (NTRS)

Vatsa, Veer N.; Carpenter, Mark H.; Lockard, David P.

2009-01-01

Recent experience in the application of an optimized, second-order, backward-difference (BDF2OPT) temporal scheme is reported. The primary focus of the work is on obtaining accurate solutions of the unsteady Reynolds-averaged Navier-Stokes equations over long periods of time for aerodynamic problems of interest. The baseline flow solver under consideration uses a particular BDF2OPT temporal scheme with a dual-time-stepping algorithm for advancing the flow solutions in time. Numerical difficulties are encountered with this scheme when the flow code is run for a large number of time steps, a behavior not seen with the standard second-order, backward-difference, temporal scheme. Based on a stability analysis, slight modifications to the BDF2OPT scheme are suggested. The performance and accuracy of this modified scheme is assessed by comparing the computational results with other numerical schemes and experimental data.

Diagonalization of complex symmetric matrices: Generalized Householder reflections, iterative deflation and implicit shifts

NASA Astrophysics Data System (ADS)

Noble, J. H.; Lubasch, M.; Stevens, J.; Jentschura, U. D.

2017-12-01

We describe a matrix diagonalization algorithm for complex symmetric (not Hermitian) matrices, A ̲ =A̲T, which is based on a two-step algorithm involving generalized Householder reflections based on the indefinite inner product 〈 u ̲ , v ̲ 〉 ∗ =∑iuivi. This inner product is linear in both arguments and avoids complex conjugation. The complex symmetric input matrix is transformed to tridiagonal form using generalized Householder transformations (first step). An iterative, generalized QL decomposition of the tridiagonal matrix employing an implicit shift converges toward diagonal form (second step). The QL algorithm employs iterative deflation techniques when a machine-precision zero is encountered "prematurely" on the super-/sub-diagonal. The algorithm allows for a reliable and computationally efficient computation of resonance and antiresonance energies which emerge from complex-scaled Hamiltonians, and for the numerical determination of the real energy eigenvalues of pseudo-Hermitian and PT-symmetric Hamilton matrices. Numerical reference values are provided.

A Simulation Study of Acoustic-Assisted Tracking of Whales for Mark-Recapture Surveys

PubMed Central

Peel, David; Miller, Brian S.; Kelly, Natalie; Dawson, Steve; Slooten, Elisabeth; Double, Michael C.

2014-01-01

Collecting enough data to obtain reasonable abundance estimates of whales is often difficult, particularly when studying rare species. Passive acoustics can be used to detect whale sounds and are increasingly used to estimate whale abundance. Much of the existing effort centres on the use of acoustics to estimate abundance directly, e.g. analysing detections in a distance sampling framework. Here, we focus on acoustics as a tool incorporated within mark-recapture surveys. In this context, acoustic tools are used to detect and track whales, which are then photographed or biopsied to provide data for mark-recapture analyses. The purpose of incorporating acoustics is to increase the encounter rate beyond using visual searching only. While this general approach is not new, its utility is rarely quantified. This paper predicts the “acoustically-assisted” encounter rate using a discrete-time individual-based simulation of whales and survey vessel. We validate the simulation framework using existing data from studies of sperm whales. We then use the framework to predict potential encounter rates in a study of Antarctic blue whales. We also investigate the effects of a number of the key parameters on encounter rate. Mean encounter rates from the simulation of sperm whales matched well with empirical data. Variance of encounter rate, however, was underestimated. The simulation of Antarctic blue whales found that passive acoustics should provide a 1.7–3.0 fold increase in encounter rate over visual-only methods. Encounter rate was most sensitive to acoustic detection range, followed by vocalisation rate. During survey planning and design, some indication of the relationship between expected sample size and effort is paramount; this simulation framework can be used to predict encounter rates and establish this relationship. For a case in point, the simulation framework indicates unequivocally that real-time acoustic tracking should be considered for quantifying the abundance of Antarctic blue whales via mark-recapture methods. PMID:24827919

A simulation study of acoustic-assisted tracking of whales for mark-recapture surveys.

PubMed

Peel, David; Miller, Brian S; Kelly, Natalie; Dawson, Steve; Slooten, Elisabeth; Double, Michael C

2014-01-01

Collecting enough data to obtain reasonable abundance estimates of whales is often difficult, particularly when studying rare species. Passive acoustics can be used to detect whale sounds and are increasingly used to estimate whale abundance. Much of the existing effort centres on the use of acoustics to estimate abundance directly, e.g. analysing detections in a distance sampling framework. Here, we focus on acoustics as a tool incorporated within mark-recapture surveys. In this context, acoustic tools are used to detect and track whales, which are then photographed or biopsied to provide data for mark-recapture analyses. The purpose of incorporating acoustics is to increase the encounter rate beyond using visual searching only. While this general approach is not new, its utility is rarely quantified. This paper predicts the "acoustically-assisted" encounter rate using a discrete-time individual-based simulation of whales and survey vessel. We validate the simulation framework using existing data from studies of sperm whales. We then use the framework to predict potential encounter rates in a study of Antarctic blue whales. We also investigate the effects of a number of the key parameters on encounter rate. Mean encounter rates from the simulation of sperm whales matched well with empirical data. Variance of encounter rate, however, was underestimated. The simulation of Antarctic blue whales found that passive acoustics should provide a 1.7-3.0 fold increase in encounter rate over visual-only methods. Encounter rate was most sensitive to acoustic detection range, followed by vocalisation rate. During survey planning and design, some indication of the relationship between expected sample size and effort is paramount; this simulation framework can be used to predict encounter rates and establish this relationship. For a case in point, the simulation framework indicates unequivocally that real-time acoustic tracking should be considered for quantifying the abundance of Antarctic blue whales via mark-recapture methods.

Numerical analysis for the stick-slip vibration of a transversely moving beam in contact with a frictional wall

NASA Astrophysics Data System (ADS)

Won, Hong-In; Chung, Jintai

2018-04-01

This paper presents a numerical analysis for the stick-slip vibration of a transversely moving beam, considering both stick-slip transition and friction force discontinuity. The dynamic state of the beam was separated into the stick state and the slip state, and boundary conditions were defined for both. By applying the finite element method, two matrix-vector equations were derived: one for stick state and the other for slip state. However, the equations have different degrees of freedom depending on whether the end of a beam sticks or slips, so we encountered difficulties in time integration. To overcome the difficulties, we proposed a new numerical technique to alternatively use the matrix-vector equations with different matrix sizes. In addition, to eliminate spurious high-frequency responses, we applied the generalized-α time integration method with appropriate value of high-frequency numerical dissipation. Finally, the dynamic responses of stick-slip vibration were analyzed in time and frequency domains: the dynamic behavior of the beam was explained to facilitate understanding of the stick-slip motion, and frequency characteristics of the stick-slip vibration were investigated in relation to the natural frequencies of the beam. The effects of the axial load and the moving speed upon the dynamic response were also examined.

Therapeutic benefits of carbon dioxide (CO2) laser on single-site HPV lesions in the lower female genital tract

NASA Astrophysics Data System (ADS)

Urru, Giovanni; Moretti, Gianfranco

1998-01-01

Numerous studies have shown contradictory variable percentages of recurrent HPV lesions, after various therapies. The present study therefore evaluates the effectiveness of CO2 laser vaporization in the treatment of single-site HPV lesions of the lower female genital tract in order to confirm the conviction that physical therapy alone, in agreement with some findings reported in the literature, is capable of guaranteeing a high cure rate in selected patients. From January 1995 to June 1996, seventy- five female patients were treated with CO2 laser vaporization for single-site genital HPV lesions, some of which were associated with low-grade intra-epithelial neoplasia. The success rate after 12 months proved to be 97%. The pre-existing clinical symptoms disappeared in all the patients treated. No complication in the vaporization procedure was encountered.

GASP cloud- and particle-encounter statistics and their application to LFC aircraft studies. Volume 2: Appendixes

NASA Technical Reports Server (NTRS)

Jasperson, W. H.; Nastron, G. D.; Davis, R. E.; Holdeman, J. D.

1984-01-01

Summary studies are presented for the entire cloud observation archive from the NASA Global Atmospheric Sampling Program (GASP). Studies are also presented for GASP particle-concentration data gathered concurrently with the cloud observations. Cloud encounters are shown on about 15 percent of the data samples overall, but the probability of cloud encounter is shown to vary significantly with altitude, latitude, and distance from the tropopause. Several meteorological circulation features are apparent in the latitudinal distribution of cloud cover, and the cloud-encounter statistics are shown to be consistent with the classical mid-latitude cyclone model. Observations of clouds spaced more closely than 90 minutes are shown to be statistically dependent. The statistics for cloud and particle encounter are utilized to estimate the frequency of cloud encounter on long-range airline routes, and to assess the probability and extent of laminaar flow loss due to cloud or particle encounter by aircraft utilizing laminar flow control (LFC). It is shown that the probability of extended cloud encounter is too low, of itself, to make LFC impractical. This report is presented in two volumes. Volume I contains the narrative, analysis, and conclusions. Volume II contains five supporting appendixes.

The supervisory encounter and the senior GP trainee: managing for, through and with.

PubMed

Brown, James; Nestel, Debra; Clement, Tim; Goldszmidt, Mark

2018-02-01

Help-seeking supervisory encounters provide important learning experiences for trainees preparing for independent practice. Although there is a body of expert opinion and theories on how supervisor encounters should happen, supporting empirical data are limited. This is particularly true for the senior general practice (GP) trainee. Without knowing what happens during these encounters, we cannot know how to maximise their educational potential. This study aimed to understand what happens when senior GP trainees call on their supervisor when caring for patients and how learning can be enhanced when this occurs. This is an analysis of data from a multi-case study of five GP supervisory pairs, each with a GP registrar and their supervisor. The data are recordings of 45 supervisory encounters, 78 post-encounter reflections and six interviews. We used Wenger's communities of practice theory and rhetorical genre theory as analytical lenses. The supervisory encounters followed a consistent format, which fitted the form of a genre. Within this genre, three dominant interactional patterns were identified, which we labelled 'managing for', 'managing through' and 'managing with'. Each pattern presented different opportunities and drew on different skills. The primary agenda was always developing a plan for the patient. Education agendas included acquiring knowledge, developing skills and achieving independence. Other agendas were issues of control, credibility and relationship building. Both supervisor and trainee could be purposeful in their supervisory engagement. For supervisors and trainees to achieve the educational potential of their supervisory encounters they require flexibility. This depends on understanding the genre of the supervisory encounter, the agendas at play, the options they have in engaging and having the skills to utilise these options. Educators can facilitate supervisors and trainees in acquiring this understanding and these skills. We recommend further research into the genre of the supervisory encounter. © 2017 John Wiley & Sons Ltd and The Association for the Study of Medical Education.

Demonstration of a tool for automatic learning and re-use of knowledge in the activated sludge process.

PubMed

Comas, J; Rodríguez-Roda, I; Poch, M; Gernaey, K V; Rosen, C; Jeppsson, U

2006-01-01

Wastewater treatment plant operators encounter complex operational problems related to the activated sludge process and usually respond to these by applying their own intuition and by taking advantage of what they have learnt from past experiences of similar problems. However, previous process experiences are not easy to integrate in numerical control, and new tools must be developed to enable re-use of plant operating experience. The aim of this paper is to investigate the usefulness of a case-based reasoning (CBR) approach to apply learning and re-use of knowledge gained during past incidents to confront actual complex problems through the IWA/COST Benchmark protocol. A case study shows that the proposed CBR system achieves a significant improvement of the benchmark plant performance when facing a high-flow event disturbance.

Prototype Conflict Alerting Logic for Free Flight

NASA Technical Reports Server (NTRS)

Yang, Lee C.; Kuchar, James K.

1997-01-01

This paper discusses the development of a prototype alerting system for a conceptual Free Flight environment. The concept assumes that datalink between aircraft is available and that conflicts are primarily resolved on the flight deck. Four alert stages are generated depending on the likelihood of a conflict. If the conflict is not resolved by the flight crews, Air Traffic Control is notified to take over separation authority. The alerting logic is based on probabilistic analysis through modeling of aircraft sensor and trajectory uncertainties. Monte Carlo simulations were used over a range of encounter situations to determine conflict probability. The four alert stages were then defined based on probability of conflict and on the number of avoidance maneuvers available to the flight crew. Preliminary results from numerical evaluations and from a piloted simulator study at NASA Ames Research Center are summarized.

Pathology of orbital bones. The XXXII Edward Jackson Memorial Lecture.

PubMed

Blodi, F C

1976-01-01

The orbital bones may show nearly all the pathologic changes observed in the skull and in the face. The congenital anomalies in this area are numerous and involve various forms of craniostenoses. Among the benign osseous tumors the osteoma is most frequently encountered in the orbit. Fibrous dysplasia is a tumefaction of indeterminate behavior that often involves the orbit. Osteosarcoma or other malignant neoplasms are rarely seen in this area. Eosinophilic granuloma and Hand-Schüller-Christian disease are tumor-like lesions that may involve the orbit.

Tropical cloud buoyancy is the same in a world with or without ice

NASA Astrophysics Data System (ADS)

Seeley, Jacob T.; Romps, David M.

2016-04-01

When convective clouds grow above the melting line, where temperatures fall below 0°C, condensed water begins to freeze and water vapor is deposited. These processes release the latent heat of fusion, which warms cloud air, and many previous studies have suggested that this heating from fusion increases cloud buoyancy in the upper troposphere. Here we use numerical simulations of radiative-convective equilibrium with and without ice processes to argue that tropical cloud buoyancy is not systematically higher in a world with fusion than in a world without it. This insensitivity results from the fact that the environmental temperature profile encountered by developing tropical clouds is itself determined by convection. We also offer a simple explanation for the large reservoir of convective available potential energy in the tropical upper troposphere that does not invoke ice.

Inflight Emergencies During Eurasian Flights.

PubMed

Kesapli, Mustafa; Akyol, Can; Gungor, Faruk; Akyol, Angelika Janitzky; Guven, Dilek Soydam; Kaya, Gokhan

2015-01-01

This study evaluated the incidence and status of urgent medical conditions, the attitudes of health professionals who encounter such conditions, the adequacy of medical kits and training of cabin crew in data-received-company aircrafts suggested by Aerospace Medical Association, and the demographic data of patients. Data were collected from medical records of a major flight company from 2011 through 2013. All patients with complete records were included in the study. Numerical variables were defined as median and interquartiles (IQR) for median, while categorical variables were defined as numbers and percentage. During the study period, 10,100,000 passengers were carried by the company flights, with 1,312 (0.013%) demands for urgent medical support (UMS). The median age of the passengers who requested UMS was 45 years (IQR: 29-62). Females constituted 698 (53.2%) among the patients, and 721 (55%) patients were evaluated by medical professionals found among passengers. The most common nontraumatic complaints resulting in requests for UMS were flight anxiety (311 patients, 23.7%) and dyspnea (145 patients, 11%). The most common traumatic complaint was burns (221 patients, 16.8%) resulting from trauma during flight. A total of 22 (1.67%) emergency landings occurred for which the most frequent reasons were epilepsy (22.7%) and death (18.2%). Deaths during flights were recorded in 13 patients, whose median age was 77 years (IQR: 69-82), which was significantly higher compared to the age of patients requiring UMS (p < 0.0001). A total of 592 (45%) patients did not require any treatment for UMS. Medical kits and training were found to be sufficient according to the symptomatic treatments. Most of the urgent cases encountered during flights can be facilitated with basic medical support. "Traumatic emergency procedures inflight medical care" would be useful for additional training. Medical professionals as passengers are significantly involved in encountered emergency situations. Adding automated external defibrillator and pulse oximetry to recommended kits and training can help facilitate staff decisions such as emergency landings and tele-assistance. © 2015 International Society of Travel Medicine.

Catalytic Organometallic Reactions of Ammonia

PubMed Central

Klinkenberg, Jessica L.

2012-01-01

Until recently, ammonia had rarely succumbed to catalytic transformations with homogeneous catalysts, and the development of such reactions that are selective for the formation of single products under mild conditions has encountered numerous challenges. However, recently developed catalysts have allowed several classes of reactions to create products with nitrogen-containing functional groups from ammonia. These reactions include hydroaminomethylation, reductive amination, alkylation, allylic substitution, hydroamination, and cross-coupling. This Minireview describes examples of these processes and the factors that control catalyst activity and selectivity. PMID:20857466

Numerical Simulation of Tip Vortices of Wings in Subsonic and Transonic Flows,

DTIC Science & Technology

1986-01-01

roll-up of the tip vor- rv : dimensionless strength of tip vortex " tex in both subsonic and transonic flows. Four test cases which used small and large...of their po- tion and the roll-up of the tip vortex has been observed for tential hazard to aircraft that encounter them in flight. To all the cases...such flows encompassing large air- tip- vortex strength. craft wakes (see for example Refs. 1-2). In spite of this, the present understanding of such

Nonlinear mechanical behavior of thermoplastic matrix materials for advanced composites

NASA Technical Reports Server (NTRS)

Arenz, R. J.; Landel, R. F.

1989-01-01

Two recent theories of nonlinear mechanical response are quantitatively compared and related to experimental data. Computer techniques are formulated to handle the numerical integration and iterative procedures needed to solve the associated sets of coupled nonlinear differential equations. Problems encountered during these formulations are discussed and some open questions described. Bearing in mind these cautions, the consequences of changing parameters that appear in the formulations on the resulting engineering properties are discussed. Hence, engineering approaches to the analysis of thermoplastic matrix material can be suggested.

Environmental Assessment. Construction and Maintenance of Wastewater Pipelines and Lift Stations and Installation of Fiber Optic Conduit at Eglin Air Force Base, Florida

DTIC Science & Technology

2012-06-01

habitats . However, on completion of the project, animals would likely return to the project site. There are known rare/protected species as well as...designated critical habitat occurring within the proposed project area. The threatened and endangered species field survey conducted on October 12- 13...critical habitat of the RCW. Numerous cavity trees used by the birds during breeding season were encounters along the Camp Rudder line route. Known as RCW

Lessons learned from the reimbursement profile of a mature private medical toxicology practice: office-based practice pays.

PubMed

Thompson, Trevonne M; Leikin, Jerrold B

2015-03-01

We previously reported the financial data for the first 5 years of one of the author's medical toxicology practice. The practice has matured; changes have been made. The practice is increasing its focus on office-based encounters and reducing hospital-based acute care encounters. We report the reimbursement rates and other financial metrics of the current practice. Financial records from October 2009 through September 2013 were reviewed. This is a period of 4 fiscal years and represents the currently available financial data. Charges, payments, and reimbursement rates were recorded according to the type and setting of the medical toxicology encounter: forensic consultations, outpatient clinic encounters, nonpsychiatric inpatient consultations, emergency department (ED) consultations, and inpatient psychiatric consultations. All patients were seen regardless of ability to pay or insurance status. The number of billed Current Procedural Terminology (CPT) codes for office-based encounters increased over the study period; the number of billed CPT codes for inpatient and ED consultations reduced. Office-based encounters demonstrate a higher reimbursement rate and higher payments. In the fiscal year (FY) of 2012, office-based revenue exceeded hospital-based acute care revenue by over $140,000 despite a higher number of billed CPT encounters in acute care settings, and outpatient payments were 2.39 times higher than inpatient, inpatient psychiatry, observation unit, and ED payments combined. The average payment per CPT code was higher for outpatient clinic encounters than inpatient encounters for each fiscal year studied. There was an overall reduction in CPT billing volume between FY 2010 and FY 2013. Despite this, there was an increase in total practice revenue. There was no change in payor mix, practice logistics, or billing/collection service company. In this medical toxicology practice, office-based encounters demonstrate higher reimbursement rates and overall payments compared to inpatient and ED consultations. While consistent with our previous studies, these differences have been accentuated. This study demonstrates the results of changes to the practice--reduced inpatient/ED consultations and increased outpatient encounters. These practice changes resulted in higher overall revenue despite a lower patient volume. In this analysis, the office-based practice of medical toxicology has higher reimbursement rates, nearly 2.5 times higher, when compared to hospital-based acute care consultations.

Delamination Assessment Tool for Spacecraft Composite Structures

NASA Astrophysics Data System (ADS)

Portela, Pedro; Preller, Fabian; Wittke, Henrik; Sinnema, Gerben; Camanho, Pedro; Turon, Albert

2012-07-01

Fortunately only few cases are known where failure of spacecraft structures due to undetected damage has resulted in a loss of spacecraft and launcher mission. However, several problems related to damage tolerance and in particular delamination of composite materials have been encountered during structure development of various ESA projects and qualification testing. To avoid such costly failures during development, launch or service of spacecraft, launcher and reusable launch vehicles structures a comprehensive damage tolerance verification approach is needed. In 2009, the European Space Agency (ESA) initiated an activity called “Delamination Assessment Tool” which is led by the Portuguese company HPS Lda and includes academic and industrial partners. The goal of this study is the development of a comprehensive damage tolerance verification approach for launcher and reusable launch vehicles (RLV) structures, addressing analytical and numerical methodologies, material-, subcomponent- and component testing, as well as non-destructive inspection. The study includes a comprehensive review of current industrial damage tolerance practice resulting from ECSS and NASA standards, the development of new Best Practice Guidelines for analysis, test and inspection methods and the validation of these with a real industrial case study. The paper describes the main findings of this activity so far and presents a first iteration of a Damage Tolerance Verification Approach, which includes the introduction of novel analytical and numerical tools at an industrial level. This new approach is being put to the test using real industrial case studies provided by the industrial partners, MT Aerospace, RUAG Space and INVENT GmbH

Hypnosis and Encounter Group Volunteers: A Validation Study of the Sensation-Seeking Scale

ERIC Educational Resources Information Center

Stanton, H. E.

1976-01-01

Individual differences in optimal level of stimulation as operationalized by the Sensation Seeking Scale significantly differentiated volunteers for hypnosis and encounter groups from non-volunteers. This confirmed predictions and extended the findings of previous work regarding encounter group volunteers. (NG)

Parameter estimation techniques based on optimizing goodness-of-fit statistics for structural reliability

NASA Technical Reports Server (NTRS)

Starlinger, Alois; Duffy, Stephen F.; Palko, Joseph L.

1993-01-01

New methods are presented that utilize the optimization of goodness-of-fit statistics in order to estimate Weibull parameters from failure data. It is assumed that the underlying population is characterized by a three-parameter Weibull distribution. Goodness-of-fit tests are based on the empirical distribution function (EDF). The EDF is a step function, calculated using failure data, and represents an approximation of the cumulative distribution function for the underlying population. Statistics (such as the Kolmogorov-Smirnov statistic and the Anderson-Darling statistic) measure the discrepancy between the EDF and the cumulative distribution function (CDF). These statistics are minimized with respect to the three Weibull parameters. Due to nonlinearities encountered in the minimization process, Powell's numerical optimization procedure is applied to obtain the optimum value of the EDF. Numerical examples show the applicability of these new estimation methods. The results are compared to the estimates obtained with Cooper's nonlinear regression algorithm.

Morphological Derivations: Learning Difficulties Encountered by Public Secondary School Students in Amman/Jordan

ERIC Educational Resources Information Center

Naseeb, Maha Zouhair; Ibrahim, Majid Abdulatif

2017-01-01

This study aims at investigating the difficulties encountered by public school students in Amman/ Jordan. The study raises the following questions: What are the obstacles that students may encounter in relation to the derivations? What are the causes of such obstacles? To achieve the aims of the study, the researchers manipulate two methods: A…

Does feeling respected influence return to work? Cross-sectional study on sick-listed patients' experiences of encounters with social insurance office staff.

PubMed

Lynöe, Niels; Wessel, Maja; Olsson, Daniel; Alexanderson, Kristina; Helgesson, Gert

2013-03-23

Previous research shows that how patients perceive encounters with healthcare staff may affect their health and self-estimated ability to return to work. The aim of the present study was to explore long-term sick-listed patients' encounters with social insurance office staff and the impact of these encounters on self-estimated ability to return to work. A random sample of long-term sick-listed patients (n = 10,042) received a questionnaire containing questions about their experiences of positive and negative encounters and item lists specifying such experiences. Respondents were also asked whether the encounters made them feel respected or wronged and how they estimated the effect of these encounters on their ability to return to work. Statistical analysis was conducted using 95% confidence intervals (CI) for proportions, and attributable risk (AR) with 95% CI. The response rate was 58%. Encounter items strongly associated with feeling respected were, among others: listened to me, believed me, and answered my questions. Encounter items strongly associated with feeling wronged were, among others: did not believe me, doubted my condition, and questioned my motivation to work. Positive encounters facilitated patients' self-estimated ability to return to work [26.9% (CI: 22.1-31.7)]. This effect was significantly increased if the patients also felt respected [49.3% (CI: 47.5-51.1)]. Negative encounters impeded self-estimated ability to return to work [29.1% (CI: 24.6-33.6)]; when also feeling wronged return to work was significantly further impeded [51.3% (CI: 47.1-55.5)]. Long-term sick-listed patients find that their self-reported ability to return to work is affected by positive and negative encounters with social insurance office staff. This effect is further enhanced by feeling respected or wronged, respectively.

Singularities in Dromo formulation. Analysis of deep flybys

NASA Astrophysics Data System (ADS)

Roa, Javier; Sanjurjo-Rivo, Manuel; Peláez, Jesús

2015-08-01

The singularities in Dromo are characterized in this paper, both from an analytical and a numerical perspective. When the angular momentum vanishes, Dromo may encounter a singularity in the evolution equations. The cancellation of the angular momentum occurs in very specific situations and may be caused by the action of strong perturbations. The gravitational attraction of a perturbing planet may lead to rapid changes in the angular momentum of the particle. In practice, this situation may be encountered during deep planetocentric flybys. The performance of Dromo is evaluated in different scenarios. First, Dromo is validated for integrating the orbit of Near Earth Asteroids. Resulting errors are of the order of the diameter of the asteroid. Second, a set of theoretical flybys are designed for analyzing the performance of the formulation in the vicinity of the singularity. New sets of Dromo variables are proposed in order to minimize the dependency of Dromo on the angular momentum. A slower time scale is introduced, leading to a more stable description of the flyby phase. Improvements in the overall performance of the algorithm are observed when integrating orbits close to the singularity.

Two-particle problem in comblike structures

NASA Astrophysics Data System (ADS)

Agliari, Elena; Cassi, Davide; Cattivelli, Luca; Sartori, Fabio

2016-05-01

Encounters between walkers performing a random motion on an appropriate structure can describe a wide variety of natural phenomena ranging from pharmacokinetics to foraging. On homogeneous structures the asymptotic encounter probability between two walkers is (qualitatively) independent of whether both walkers are moving or one is kept fixed. On infinite comblike structures this is no longer the case and here we deepen the mechanisms underlying the emergence of a finite probability that two random walkers will never meet, while one single random walker is certain to visit any site. In particular, we introduce an analytical approach to address this problem and even more general problems such as the case of two walkers with different diffusivity, particles walking on a finite comb and on arbitrary bundled structures, possibly in the presence of loops. Our investigations are both analytical and numerical and highlight that, in general, the outcome of a reaction involving two reactants on a comblike architecture can strongly differ according to whether both reactants are moving (no matter their relative diffusivities) or only one is moving and according to the density of shortcuts among the branches.

A proposed definition for a pitch attitude target for the microburst escape maneuver

NASA Technical Reports Server (NTRS)

Bray, Richard S.

1990-01-01

The Windshear Training Aid promulgated by the Federal Aviation Administration (FAA) defines the practical recovery maneuver following a microburst encounter as application of maximum thrust accompanied by rotation to an aircraft-specific target pitch attitude. In search of a simple method of determining this target, appropriate to a variety of aircraft types, a computer simulation was used to explore the suitability of a pitch target equal in numerical value to that of the angle of attack associated with stall warning. For the configurations and critical microburst shears simulated, this pitch target was demonstrated to be close to optimum.

Simulator study of vortex encounters by a twin-engine, commercial, jet transport airplane

NASA Technical Reports Server (NTRS)

Hastings, E. C., Jr.; Keyser, G. L., Jr.

1982-01-01

A simulator study of vortex encounters was conducted for a twin-engine, commercial, jet transport airplane encountering the vortex flow field of a heavy, four-engine, commercial, jet transport airplane in the final-approach configuration. The encounters were conducted with fixed controls and with a pilot using a state-of-the-art, manual-control system. Piloted encounters with the base-line vortex flow field out of ground effect (unattenuated) resulted in initial bank-angle excursions greater than 40 deg, coupled with initial sideslip-angle excursions greater than 10 deg. The severity of these initial upsets was significantly reduced when the vortex center was moved laterally or vertically away from the flight path of the encountering airplane. Smaller reductions occurred when the flow field was attenuated by the flight spoilers on the generating airplane. The largest reduction in the severity of the initial upsets, however, was from aging in ground effect. The severity of the initial upsets of the following airplane was relatively unaffected by the approach speed. Increasing the lift coefficient of the generating airplane resulted in an increase in the severity of the initial upsets.

Simulations of laminar boundary-layer flow encountering large-scale surface indentions

NASA Astrophysics Data System (ADS)

Beratlis, N.; Balaras, E.; Squires, K.; Vizard, A.

2016-03-01

The transition from laminar to turbulent flow over dimples and grooves has been investigated through a series of direct numerical simulations. Emphasis has been given to the mechanism of transition and the momentum transport in the post-dimple boundary layer. It has been found that the dimple geometry plays an important role in the evolution of the turbulent boundary layer downstream. The mechanism of transition in all cases is that of the reorientation of the spanwise vorticity into streamwise oriented structures resembling hairpin vortices commonly encountered in wall bounded turbulent flows. Although qualitatively the transition mechanism amongst the three different cases is similar, important quantitative differences exist. It was shown that two-dimensional geometries like a groove are more stable than three-dimensional geometries like a dimple. In addition, it was found that the cavity geometry controls the initial thickness of the boundary layer and practically results in a shift of the virtual origin of the turbulent boundary layer. Important differences in the momentum transport downstream of the dimples exist but in all cases the boundary layer grows in a self-similar manner.

Transitional cell neoplasm of the nasolacrimal duct associated with human papillomavirus type 11.

PubMed

Vickers, Jennifer L; Matherne, Ryan J; Allison, Ashley W; Wilkerson, Michael G; Tyring, Stephen K; Bartlett, Brenda L; Rady, Peter L; Kelly, Brent C

2010-07-01

Tumors of the lacrimal sac are rare but noteworthy because of their significant potential to become malignant or life-threatening if treatment is delayed. Dermatologists may be the first to encounter such neoplasms. We report a case of a 53-year-old Caucasian woman who presented with a seven-year history of an asymptomatic, subcutaneous nodule near her right medial canthus. Histology of the lesion revealed transitional epithelium in a papillary growth pattern with numerous goblet cells, scattered mitoses and focal full-thickness atypia. The patient was diagnosed with transitional cell neoplasm (inverted papilloma-type) of the nasolacrimal duct. PCR evaluation identified HPV type 11 in the lesion. Our report is one of a growing number of case reports and series detecting HPV DNA in these tumors which further supports HPV as an etiologic agent in epithelial lacrimal sac tumors. We believe that dermatopathologists need to be aware of this entity, as dermatologists may be the first to encounter these neoplasms. The association of HPV with this tumor does not prove causality.

Solution of 3-dimensional time-dependent viscous flows. Part 2: Development of the computer code

NASA Technical Reports Server (NTRS)

Weinberg, B. C.; Mcdonald, H.

1980-01-01

There is considerable interest in developing a numerical scheme for solving the time dependent viscous compressible three dimensional flow equations to aid in the design of helicopter rotors. The development of a computer code to solve a three dimensional unsteady approximate form of the Navier-Stokes equations employing a linearized block emplicit technique in conjunction with a QR operator scheme is described. Results of calculations of several Cartesian test cases are presented. The computer code can be applied to more complex flow fields such as these encountered on rotating airfoils.

Temporary satellite capture of comets by Jupiter

NASA Astrophysics Data System (ADS)

Emel'yanenko, N. Yu.

2012-05-01

This paper studies the dynamical evolution of 97 Jupiter-family comets over an 800-year time period. More than two hundred encounters with Jupiter are investigated, with the observed comets moving during a certain period of time in an elliptic jovicentric orbit. In most cases this is an ordinary temporary satellite capture of a comet in Everhart's sense, not associated with a transition of the small body into Jupiter's family of satellites. The phenomenon occurs outside the Hill sphere with comets with a high Tisserand constant relative to Jupiter; the comets' orbits have a small inclination to the ecliptic plane. An analysis of 236 encounters has allowed the determination within the planar pair two-body problem of a region of orbits in the plane ( a, e) whose semimajor axes and eccentricities contribute to the phenomenon under study. Comets with orbits belonging to this region experience a temporary satellite capture during some of their encounters; the jovicentric distance function has several minima; and the encounters are characterized by reversions of the line of apsides and some others features of their combination that are intrinsic to comets in this region. Therefore, this region is called a region of comets with specific features in their encounters with Jupiter. Twenty encounters (out of 236), whereby the comet enters an elliptic jovicentric orbit in the Hill sphere, are identified and investigated. The size and shape of the elliptic heliocentric orbits enabling this transition are determined. It is found that in 11 encounters the motion of small bodies in the Hill sphere has features the most important of which is multiple minima of the jovicentric distance function. The study of these 20 encounters has allowed the introduction of the concept of temporary gravitational capture of a small body into the Hill sphere. An analysis of variations in the Tisserand constant in these (20) encounters of the observable comets shows that their motion is unstable in Hill's sense.

Simulation of the 1994 Charlotte Microburst with Look-Ahead Windshear Radar

NASA Technical Reports Server (NTRS)

Proctor, F. H.; Bracalente, E. M.; Harrah, S. D.; Switzer, G. F.; Britt, C. L.

1995-01-01

A severe microburst occurred on 2 July 1994 at Charlotte, NC, and was associated with the crash of USAir Flight 1016 (FL-1016) (Salottolo 1994; Phillips 1994). The inbound DC-9 unexpectedly encountered a rapidly intensifying rainshaft just seconds before it was to touchdown on runway 18R. The aircraft crashed after encountering strong windshear, killing 37 of the 57 souls on board. The pilots did not recognize the windshear condition in time to prevent the accident and received no warning from the aircraft's Honeywell in-situ windshear detection system or from ground-based systems (Charlotte maintains both an ASR-9 weather radar and a Phase-2 LLWAS). Also two other aircraft landed ahead of FL-1016 without incident and reported smooth approaches to 18R. Section-2 of this paper reports briefly on the reconstruction of the event based on numerical results generated by the Terminal Area Simulation System (TASS) as presented at the National Transportation Safety Board (NTSB) public hearing (Proctor 1994). Section-3 discusses the simulation of this event with a look-ahead windshear radar.

Sources and dynamics of turbulence in the upper troposphere and lower stratosphere: A review

NASA Astrophysics Data System (ADS)

Sharman, R. D.; Trier, S. B.; Lane, T. P.; Doyle, J. D.

2012-06-01

Turbulence is a well-known hazard to aviation that is responsible for numerous injuries each year, with occasional fatalities, and is the underlying cause of many people's fear of air travel. Not only are turbulence encounters a safety issue, they also result in millions of dollars of operational costs to airlines, leading to increased costs passed on to the consumer. For these reasons, pilots, dispatchers, and air traffic controllers attempt to avoid turbulence wherever possible. Accurate forecasting of aviation-scale turbulence has been hampered in part by a lack of understanding of the underlying dynamical processes. However, more precise observations of turbulence encounters together with recent research into turbulence generation processes is helping to elucidate the detailed dynamical processes involved and is laying the foundation for improved turbulence forecasting and avoidance. In this paper we briefly review some of the more important recent observational, theoretical, and modeling results related to turbulence at cruise altitudes for commercial aircraft (i.e., the upper troposphere and lower stratosphere), and their implications for aviation turbulence forecasting.

[Prevention of road accidents in the road haulage field].

PubMed

Rosso, G L; Zanelli, R; Corino, P; Bruno, S

2007-01-01

Every year many traffic accidents with fatal outcomes occur in our Country. According to the recent indications of the European Agency for Safety and Health at Work, the Piedmont region has financed the plan: Prevention of road accidents in the road haulage field. The aims of the plan are to stimulate transport companies to the target of road safety and to improve and enforce sanitary surveillance, in order to improve the safety on road haulage and to prevent traffic injuries. the plan foresees, over a period of two years, a few encounters with all the interested parties (companies, police forces, labour unions etc). During those encounters we have to give a questionnaire for evaluating the companies' knowledge about the problem and we have to choose a common plan with the aim of improving road safety. The Piedmont regional plan recalls the need to increase the attention to numerous and diversified hazards for safety on road haulage. It also imposes the choice of measures that include: risk assessment, health education, technical and environmental prevention, sanitary surveillance and clinical interventions (diagnosis and rehabilitation of occupational accidents).

Direct handling of equality constraints in multilevel optimization

NASA Technical Reports Server (NTRS)

Renaud, John E.; Gabriele, Gary A.

1990-01-01

In recent years there have been several hierarchic multilevel optimization algorithms proposed and implemented in design studies. Equality constraints are often imposed between levels in these multilevel optimizations to maintain system and subsystem variable continuity. Equality constraints of this nature will be referred to as coupling equality constraints. In many implementation studies these coupling equality constraints have been handled indirectly. This indirect handling has been accomplished using the coupling equality constraints' explicit functional relations to eliminate design variables (generally at the subsystem level), with the resulting optimization taking place in a reduced design space. In one multilevel optimization study where the coupling equality constraints were handled directly, the researchers encountered numerical difficulties which prevented their multilevel optimization from reaching the same minimum found in conventional single level solutions. The researchers did not explain the exact nature of the numerical difficulties other than to associate them with the direct handling of the coupling equality constraints. The coupling equality constraints are handled directly, by employing the Generalized Reduced Gradient (GRG) method as the optimizer within a multilevel linear decomposition scheme based on the Sobieski hierarchic algorithm. Two engineering design examples are solved using this approach. The results show that the direct handling of coupling equality constraints in a multilevel optimization does not introduce any problems when the GRG method is employed as the internal optimizer. The optimums achieved are comparable to those achieved in single level solutions and in multilevel studies where the equality constraints have been handled indirectly.

Habitability in different Milky Way stellar environments: a stellar interaction dynamical approach.

PubMed

Jiménez-Torres, Juan J; Pichardo, Bárbara; Lake, George; Segura, Antígona

2013-05-01

Every Galactic environment is characterized by a stellar density and a velocity dispersion. With this information from literature, we simulated flyby encounters for several Galactic regions, numerically calculating stellar trajectories as well as orbits for particles in disks; our aim was to understand the effect of typical stellar flybys on planetary (debris) disks in the Milky Way Galaxy. For the solar neighborhood, we examined nearby stars with known distance, proper motions, and radial velocities. We found occurrence of a disturbing impact to the solar planetary disk within the next 8 Myr to be highly unlikely; perturbations to the Oort cloud seem unlikely as well. Current knowledge of the full phase space of stars in the solar neighborhood, however, is rather poor; thus we cannot rule out the existence of a star that is more likely to approach than those for which we have complete kinematic information. We studied the effect of stellar encounters on planetary orbits within the habitable zones of stars in more crowded stellar environments, such as stellar clusters. We found that in open clusters habitable zones are not readily disrupted; this is true if they evaporate in less than 10(8) yr. For older clusters the results may not be the same. We specifically studied the case of Messier 67, one of the oldest open clusters known, and show the effect of this environment on debris disks. We also considered the conditions in globular clusters, the Galactic nucleus, and the Galactic bulge-bar. We calculated the probability of whether Oort clouds exist in these Galactic environments.

Hydrothermal system of the Papandayan Volcano from temperature, self-potential (SP) and geochemical measurements

NASA Astrophysics Data System (ADS)

Byrdina, Svetlana; Revil, André; Gunawan, Hendra; Saing, Ugan B.; Grandis, Hendra

2017-07-01

Papandayan volcano in West Java, Indonesia, is characterized by intense hydrothermal activities manifested by numerous fumaroles at three craters or kawah, i.e. Mas, Manuk and Baru. The latter was created after November 2002 phreatic eruption. Since 2011, numerous volcano-tectonic B events are encountered and the volcano was set on alert status on several occasions. The purpose of the present study is to delineate the structure of the summital hydrothermal system from Self-Potential (SP), soil temperature and gas concentrations in the soil (CO2, SO2 and H2S) data. This combination of geophysical and geochemical methods allows identification of the weak permeable zones serving as preferential pathways for hydrothermal circulation and potential candidates to future landslides or flank collapses. This study is an on-going collaborative research project and we plan to conduct electrical resistivity tomography (ERT) and also Induced-Polarization (IP) surveys. Additional data would allow the 3D imaging of the studied area. The IP parameters will be used to characterise and to quantify the degree of alteration of the volcanic rocks as has been shown very recently in the laboratory studies. There are also rocks and soil samples that will undergo laboratory analyses at ISTerre for IP and complex resistivity parameters at the sample scale that will help to interpret the survey results.

Dissecting the evolution of dark matter subhaloes in the Bolshoi simulation

NASA Astrophysics Data System (ADS)

van den Bosch, Frank C.

2017-06-01

We present a comprehensive analysis of the evolution of dark matter subhaloes in the cosmological Bolshoi simulation. We identify a complete set of 12 unique evolution channels by which subhaloes evolve in between simulation outputs, and study their relative importance and demographics. We show that instantaneous masses and maximum circular velocities of individual subhaloes are extremely noisy, despite the use of a sophisticated, phase-space-based halo finder. We also show that subhaloes experience frequent penetrating encounters with other subhaloes (on average about one per dynamical time), and that subhaloes whose apo-centre lies outside the virial radius of their host (the 'ejected' or 'backsplash' haloes) experience tidal forces that modify their orbits. This results in an average fractional subhalo exchange rate among host haloes of ˜0.01 Gyr-1 (at the present time). In addition, we show that there are three distinct disruption channels; one in which subhaloes drop below the mass resolution limit of the simulation, one in which subhaloes 'merge' with their host halo largely driven by dynamical friction, and one in which subhaloes abruptly disintegrate. We estimate that roughly 80 per cent of all subhalo disruption in the Bolshoi simulation is numerical, rather than physical. This 'overmerging' is a serious road-block for the use of numerical simulations to interpret small-scale clustering, or for any other study that is sensitive to the detailed demographics of dark matter substructure.

Disrespect, harassment, and abuse: all in a day's work for family physicians.

PubMed

Miedema, Baukje; Easley, Julie; Fortin, Pierrette; Hamilton, Ryan; Tatemichi, Sue

2009-03-01

To examine harassment and abusive encounters between family physicians and their patients or colleagues in the workplace. Qualitative case study using semistructured interviews. Province of New Brunswick. Forty-eight family physicians from across the province. A collective case-study approach was developed, with 24 cases of 2 individuals per case. Cases were selected based on sex, location (urban or rural), language (French or English), and number of years since medical school graduation (< 10 years, 10 to 20 years, or > 20 years). Physicians were interviewed in either French or English. Participants were recruited using the College of Physicians and Surgeons of New Brunswick's physician directory. Based on the rates of response and participation, some cases were overrepresented, while others were not completed. All interviews were audiotaped, transcribed verbatim, and analyzed thematically using a categorical aggregation approach. A coding scheme for the thematic analysis was developed by the research team before the interviews were transcribed. Although the original intent of this study was to examine the work environment of family physicians in light of the increasing number of women entering the profession, harassment and abusive encounters in the workplace emerged as a main theme. These encounters ranged from minor to severe. Minor abusive encounters included disrespectful behaviour and verbal threats by patients, their families, and occasionally colleagues. More severe forms of harassment involved physical threats, physical encounters, and stalking. Demanding patients, such as heavy drug users, were often seen as threatening. Location of practice, years in practice, and sex of the physician seemed to affect abusive encounters--young, female, rural physicians appeared to experience such encounters most often. Abusive encounters in the workplace are concerning. It is essential to address these issues of workplace harassment and abuse in order to protect physician safety and avoid workplace dissatisfaction. Abusive encounters might push family physicians to leave clinical practice prematurely or refuse to work in higher-risk environments, such as emergency departments or rural areas.

Controversies in the Treatment of Early Stage Endometrial Carcinoma

PubMed Central

Press, Joshua Z.; Gotlieb, Walter H.

2012-01-01

Despite the publication of numerous studies, including some multicentered randomized controlled trials, there continues to be vigorous debate regarding the optimal management of early stage endometrial cancer, including the extent of surgery and the role of adjuvant chemotherapy and radiation. Resolving these questions has become increasingly important in view of the increase of endometrial cancer, related to the aging population and the alarming incidence of obesity. Furthermore, there are more surgical challenges encountered when operating on elderly patients or on patients with increased BMI and the associated comorbidities, such as diabetes, hypertension, heart disease, and pulmonary dysfunction. This paper will focus on the advantages of minimally invasive surgery, the value of lymphadenectomy including sentinel lymph node mapping, and some of the current controversies surrounding adjuvant chemotherapy and radiation. PMID:22685466

An improved, robust, axial line singularity method for bodies of revolution

NASA Technical Reports Server (NTRS)

Hemsch, Michael J.

1989-01-01

The failures encountered in attempts to increase the range of applicability of the axial line singularity method for representing incompressible, inviscid flow about an inclined and slender body-of-revolution are presently noted to be common to all efforts to solve Fredholm equations of the first kind. It is shown that a previously developed smoothing technique yields a robust method for numerical solution of the governing equations; this technique is easily retrofitted to existing codes, and allows the number of circularities to be increased until the most accurate line singularity solution is obtained.

Isospin symmetry breaking and large-scale shell-model calculations with the Sakurai-Sugiura method

NASA Astrophysics Data System (ADS)

Mizusaki, Takahiro; Kaneko, Kazunari; Sun, Yang; Tazaki, Shigeru

2015-05-01

Recently isospin symmetry breaking for mass 60-70 region has been investigated based on large-scale shell-model calculations in terms of mirror energy differences (MED), Coulomb energy differences (CED) and triplet energy differences (TED). Behind these investigations, we have encountered a subtle problem in numerical calculations for odd-odd N = Z nuclei with large-scale shell-model calculations. Here we focus on how to solve this subtle problem by the Sakurai-Sugiura (SS) method, which has been recently proposed as a new diagonalization method and has been successfully applied to nuclear shell-model calculations.

Dark solitons in laser radiation build-up dynamics.

PubMed

Woodward, R I; Kelleher, E J R

2016-03-01

We reveal the existence of slowly decaying dark solitons in the radiation build-up dynamics of bright pulses in all-normal dispersion mode-locked fiber lasers, numerically modeled in the framework of a generalized nonlinear Schrödinger equation. The evolution of noise perturbations to quasistationary dark solitons is examined, and the significance of background shape and soliton-soliton collisions on the eventual soliton decay is established. We demonstrate the role of a restoring force in extending soliton interactions in conservative systems to include the effects of dissipation, as encountered in laser cavities, and generalize our observations to other nonlinear systems.

Sonic environment tests of an insulator/ablator material

NASA Technical Reports Server (NTRS)

Jackson, L. R.; Taylor, A. H.; Rucker, C. E.

1977-01-01

A 50.8 cm (20 inch) square panel of perpyrolized insulator/ablator was subjected to six 30-minute tests at 160 and 158 dB in the Langley Thermo-Acoustic Fatigue Apparatus (TAFA). This environment simulates the aerodynamic and engine noise encountered by a research airplane while in captive flight on the B-52 pylon during takeoff and climb. The pyrolized layer sustained damage in the form of three chips and numerous cracks. The chips occurred during the first test. Some cracking resulted during aerodynamic heating tests, and additional cracking resulted from the sonic environment tests.

Multiaxial and Thermomechanical Fatigue of Materials: A Historical Perspective and Some Future Challenges

NASA Technical Reports Server (NTRS)

Kalluri, Sreeramesh

2013-01-01

Structural materials used in engineering applications routinely subjected to repetitive mechanical loads in multiple directions under non-isothermal conditions. Over past few decades, several multiaxial fatigue life estimation models (stress- and strain-based) developed for isothermal conditions. Historically, numerous fatigue life prediction models also developed for thermomechanical fatigue (TMF) life prediction, predominantly for uniaxial mechanical loading conditions. Realistic structural components encounter multiaxial loads and non-isothermal loading conditions, which increase potential for interaction of damage modes. A need exists for mechanical testing and development verification of life prediction models under such conditions.

Symmetry breaking, Josephson oscillation and self-trapping in a self-bound three-dimensional quantum ball.

PubMed

Adhikari, S K

2017-11-22

We study spontaneous symmetry breaking (SSB), Josephson oscillation, and self-trapping in a stable, mobile, three-dimensional matter-wave spherical quantum ball self-bound by attractive two-body and repulsive three-body interactions. The SSB is realized by a parity-symmetric (a) one-dimensional (1D) double-well potential or (b) a 1D Gaussian potential, both along the z axis and no potential along the x and y axes. In the presence of each of these potentials, the symmetric ground state dynamically evolves into a doubly-degenerate SSB ground state. If the SSB ground state in the double well, predominantly located in the first well (z > 0), is given a small displacement, the quantum ball oscillates with a self-trapping in the first well. For a medium displacement one encounters an asymmetric Josephson oscillation. The asymmetric oscillation is a consequence of SSB. The study is performed by a variational and a numerical solution of a non-linear mean-field model with 1D parity-symmetric perturbations.

Galaxy shredding. I - Centaurus A, NGC 5237, and the Fourcade-Figueroa shred

NASA Astrophysics Data System (ADS)

Thomson, R. C.

1992-08-01

Numerical simulations of galaxy shredding are presented together with a case study of the nearby active galaxy Centaurus A. It is suggested that a shred-forming encounter with a spiral galaxy (about the same size as the Milky Way) took place some 5 x 10 exp 8 yr ago. The captured disk material now forms the conspicuous ring of gas and dust which girdles Centaurus A, and probably provides the fuel that powers the radio emission seen today. The present shredding model provides a consistent picture of many aspects of the Centaurus A system, including: the relative positions and velocities of Centaurus A, NGC 5237, and the Fourcade-Figueroa shred; the orientation and sense of rotation of the dust lane in Centaurus A; the peculiar nature of the interacting dwarf elliptical galaxy NGC 5237; and the orientation and observed nonrotation of the Fourcade-Figueroa shred.

Protection characteristics of a Faraday cage compromised by lightning burnthrough.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warne, Larry Kevin; Bystrom, Edward; Jorgenson, Roy Eberhardt

2012-01-01

A lightning flash consists of multiple, high-amplitude but short duration return strokes. Between the return strokes is a lower amplitude, continuing current which flows for longer duration. If the walls of a Faraday cage are made of thin enough metal, the continuing current can melt a hole through the metal in a process called burnthrough. A subsequent return stroke can couple energy through this newly-formed hole. This LDRD is a study of the protection provided by a Faraday cage when it has been compromised by burnthrough. We initially repeated some previous experiments and expanded on them in terms of scopemore » and diagnostics to form a knowledge baseline of the coupling phenomena. We then used a combination of experiment, analysis and numerical modeling to study four coupling mechanisms: indirect electric field coupling, indirect magnetic field coupling, conduction through plasma and breakdown through the hole. We discovered voltages higher than those encountered in the previous set of experiments (on the order of several hundreds of volts).« less

Recent collisional jet from a primitive asteroid

NASA Astrophysics Data System (ADS)

Novaković, Bojan; Dell'Oro, Aldo; Cellino, Alberto; Knežević, Zoran

2012-09-01

In this paper we show an example of a young asteroid cluster located in a dynamically stable region, which was produced by partial disruption of a primitive body about 30 km in size. We estimate its age to be only 1.9 ± 0.3 Myr; thus, its post-impact evolution should have been very limited. The large difference in size between the largest object and the other cluster members means that this was a cratering event. The parent body had a large orbital inclination and was subject to collisions with typical impact speeds higher by a factor of 2 than in the most common situations encountered in the main belt. For the first time, we have at our disposal the observable outcome of a very recent event to study high-speed collisions involving primitive asteroids, providing very useful constraints to numerical simulations of these events and to laboratory experiments.

Modeling interfacial fracture in Sierra.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, Arthur A.; Ohashi, Yuki; Lu, Wei-Yang

2013-09-01

This report summarizes computational efforts to model interfacial fracture using cohesive zone models in the SIERRA/SolidMechanics (SIERRA/SM) finite element code. Cohesive surface elements were used to model crack initiation and propagation along predefined paths. Mesh convergence was observed with SIERRA/SM for numerous geometries. As the funding for this project came from the Advanced Simulation and Computing Verification and Validation (ASC V&V) focus area, considerable effort was spent performing verification and validation. Code verification was performed to compare code predictions to analytical solutions for simple three-element simulations as well as a higher-fidelity simulation of a double-cantilever beam. Parameter identification was conductedmore » with Dakota using experimental results on asymmetric double-cantilever beam (ADCB) and end-notched-flexure (ENF) experiments conducted under Campaign-6 funding. Discretization convergence studies were also performed with respect to mesh size and time step and an optimization study was completed for mode II delamination using the ENF geometry. Throughout this verification process, numerous SIERRA/SM bugs were found and reported, all of which have been fixed, leading to over a 10-fold increase in convergence rates. Finally, mixed-mode flexure experiments were performed for validation. One of the unexplained issues encountered was material property variability for ostensibly the same composite material. Since the variability is not fully understood, it is difficult to accurately assess uncertainty when performing predictions.« less

Numerical experiments on neutron yield and soft x-ray study of a ˜100 kJ plasma focus using the current profile fitting technique

NASA Astrophysics Data System (ADS)

Ong, S. T.; Chaudhary, K.; Ali, J.; Lee, S.

2014-07-01

Numerical experiments using the Lee model were performed to study the neutron yield and soft x-ray emission from the IR-MPF-100 plasma focus using the current fitting technique. The mass sweeping factor and the current factor for the axial and radial phase were used to represent the imperfections encountered in experiments. All gross properties including the yields were realistically simulated once the computed and measured current profiles were well fitted. The computed neutron yield Yn was in agreement with the experimentally measured Yn at 20 kV (E0 ˜ 30 kJ) charging voltage. The optimum computed neutron yield of Yn = 1.238 × 109 neutrons per shot was obtained at optimum physics parameters of the plasma focus operated with deuterium gas. It was also observed that no soft x-rays were emitted from the IR-MPF-100 plasma focus operated with argon gas due to the absence of helium-like and hydrogen-like ions at a low plasma temperature (˜0.094 keV) and axial speed (8.12 cm µs-1). However, the soft x-ray yield can be achieved by increasing the charging voltage, using a higher ratio of outer anode radius to inner anode radius c or shorter anode length z0, or using neon as the operating gas.

Being on sick leave due to heart failure: Encounters with social insurance officers and associations with sociodemographic factors and self-estimated ability to return to work.

PubMed

Nordgren, Lena; Söderlund, Anne

2016-04-01

Little is known about sick leave and the ability to return to work (RTW) for people with heart failure (HF). Previous research findings raise questions about the significance of encounters with social insurance officers (SIOs) and sociodemographics in people sick-listed due to HF. To investigate how people on sick leave due to HF experience encounters with SIOs and associations between sociodemographic factors, experiences of positive/negative encounters with SIOs, and self-estimated ability to RTW. This was a population-based study with a cross-sectional design. The sample consisted of 590 sick-listed people with HF in Sweden. A register-based investigation supplemented with a postal survey questionnaire was conducted. Bivariate correlations and logistic regression analysis was used to test associations between sociodemographic factors, positive and negative encounters, and self-estimated ability to RTW. People with low income were more likely to receive sickness compensation. A majority of the responders experienced encounters with SIOs as positive. Being married was significantly associated with positive encounters. Having a low income was related to negative encounters. More than a third of the responders agreed that positive encounters with SIOs facilitated self-estimated ability to RTW. High income was strongly associated with the impact of positive encounters on self-estimated ability to RTW. Encounters between SIOs and people on sick leave due to HF need to be characterized by a person-centred approach including confidence and trust. People with low income need special attention. © The European Society of Cardiology 2015.

Multiple Codes, Multiple Impressions: An Analysis of Doctor-Client Encounters in Nigeria

ERIC Educational Resources Information Center

Odebunmi, Akin

2013-01-01

Existing studies on doctor-client interactions have largely focused on monolingual encounters and the interactional effects and functions of the languages used in the communication between doctors and their clients. They have neither, to a large extent, examined the several codes employed in single encounters and their pragmatic roles nor given…

Evaluation of a pulse control law for flexible spacecraft

NASA Technical Reports Server (NTRS)

1985-01-01

The following analytical and experimental studies were conducted: (1) A simple algorithm was developed to suppress the structural vibrations of 3-dimensional distributed parameter systems, subjected to interface motion and/or directly applied forces. The algorithm is designed to cope with structural oscillations superposed on top of rigid-body motion: a situation identical to that encountered by the SCOLE components. A significant feature of the method is that only local measurements of the structural displacements and velocities relative to the moving frame of reference are needed. (2) A numerical simulation study was conducted on a simple linear finite element model of a cantilevered plate which was subjected to test excitations consisting of impulsive base motion and of nonstationary wide-band random excitation applied at its root. In each situation, the aim was to suppress the vibrations of the plate relative to the moving base. (3) A small mechanical model resembling an aircraft wing was designed and fabricated to investigate the control algorithm under realistic laboratory conditions.

Computer Science Education as a Cultural Encounter: A Socio-Cultural Framework for Articulating Teaching Difficulties

ERIC Educational Resources Information Center

Kolikant, Yifat Ben-David

2011-01-01

This study demonstrates the power of the cultural encounter metaphor in explaining learning and teaching difficulties, using as an example computer science education (CSE). CSE is envisioned as an encounter between veterans of two computer-oriented cultures, that of the teachers and that of the students. Forty questionnaires administered to CS…

The Effectiveness and Clinical Usability of a Handheld Information Appliance

PubMed Central

Abbott, Patricia A.

2012-01-01

Clinical environments are complex, stressful, and safety critical—heightening the demand for technological solutions that will help clinicians manage health information efficiently and safely. The industry has responded by creating numerous, increasingly compact and powerful health IT devices that fit in a pocket, hook to a belt, attach to eyeglasses, or wheel around on a cart. Untethering a provider from a physical “place” with compact, mobile technology while delivering the right information at the right time and at the right location are generally welcomed in clinical environments. These developments however, must be looked at ecumenically. The cognitive load of clinicians who are occupied with managing or operating several different devices during the process of a patient encounter is increased, and we know from decades of research that cognitive overload frequently leads to error. “Technology crowding,” enhanced by the plethora of mobile health IT, can actually become an additional millstone for busy clinicians. This study was designed to gain a deeper understanding of clinicians' interactions with a mobile clinical computing appliance (Motion Computing C5) designed to consolidate numerous technological functions into an all-in-one device. Features of usability and comparisons to current methods of documentation and task performance were undertaken and results are described. PMID:22548159

ASRS Reports on Wake Vortex Encounters

NASA Technical Reports Server (NTRS)

Connell, Linda J.; Taube, Elisa Ann; Drew, Charles Robert; Barclay, Tommy Earl

2010-01-01

ASRS is conducting a structured callback research project of wake vortex incidents reported to the ASRS at all US airports, as well as wake encounters in the enroute environment. This study has three objectives: (1) Utilize the established ASRS supplemental data collection methodology and provide ongoing analysis of wake vortex encounter reports; (2) Document event dynamics and contributing factors underlying wake vortex encounter events; and (3) Support ongoing FAA efforts to address pre-emptive wake vortex risk reduction by utilizing ASRS reporting contributions.

Surgical anatomy of the hypoglossal nerve: A new classification system for selective upper airway stimulation.

PubMed

Heiser, Clemens; Knopf, Andreas; Hofauer, Benedikt

2017-12-01

Selective upper airway stimulation (UAS) has shown effectiveness in treating patients with obstructive sleep apnea (OSA). The terminating branches of the hypoglossal nerve show a wide complexity, requiring careful discernment of a functional breakpoint between branches for inclusion and exclusion from the stimulation cuff electrode. The purpose of this study was to describe and categorize the topographic phenotypes of these branches. Thirty patients who received an implant with selective UAS from July 2015 to June 2016 were included. All implantations were recorded using a microscope and resultant tongue motions were captured perioperatively for comparison. Eight different variations of the branches were encountered and described, both in a tabular numeric fashion and in pictorial schema. The examinations showed the complex phenotypic surgical anatomy of the hypoglossal nerve. A schematic classification system has been developed to help surgeons identify the optimal location for cuff placement in UAS. © 2017 Wiley Periodicals, Inc.

Compound matrices

NASA Astrophysics Data System (ADS)

Kravvaritis, Christos; Mitrouli, Marilena

2009-02-01

This paper studies the possibility to calculate efficiently compounds of real matrices which have a special form or structure. The usefulness of such an effort lies in the fact that the computation of compound matrices, which is generally noneffective due to its high complexity, is encountered in several applications. A new approach for computing the Singular Value Decompositions (SVD's) of the compounds of a matrix is proposed by establishing the equality (up to a permutation) between the compounds of the SVD of a matrix and the SVD's of the compounds of the matrix. The superiority of the new idea over the standard method is demonstrated. Similar approaches with some limitations can be adopted for other matrix factorizations, too. Furthermore, formulas for the n - 1 compounds of Hadamard matrices are derived, which dodge the strenuous computations of the respective numerous large determinants. Finally, a combinatorial counting technique for finding the compounds of diagonal matrices is illustrated.

Rheological effects on friction in elastohydrodynamic lubrication

NASA Technical Reports Server (NTRS)

Trachman, E. G.; Cheng, H. S.

1973-01-01

An analytical and experimental investigation is presented of the friction in a rolling and sliding elastohydrodynamic lubricated contact. The rheological behavior of the lubricant is described in terms of two viscoelastic models. These models represent the separate effects of non-Newtonian behavior and the transient response of the fluid. A unified description of the non-Newtonian shear rate dependence of the viscosity is presented as a new hyperbolic liquid model. The transient response of viscosity, following the rapid pressure rise encountered in the contact, is described by a compressional viscoelastic model of the volume response of a liquid to an applied pressure step. The resulting momentum and energy equations are solved by an iterative numerical technique, and a friction coefficient is calculated. The experimental study was performed, with two synthetic paraffinic lubricants, to verify the friction predictions of the analysis. The values of friction coefficient from theory and experiment are in close agreement.

Efficacy of communication skills training for giving bad news and discussing transitions to palliative care.

PubMed

Back, Anthony L; Arnold, Robert M; Baile, Walter F; Fryer-Edwards, Kelly A; Alexander, Stewart C; Barley, Gwyn E; Gooley, Ted A; Tulsky, James A

2007-03-12

Few studies have assessed the efficacy of communication skills training for postgraduate physician trainees at the level of behaviors. We designed a residential communication skills workshop (Oncotalk) for medical oncology fellows. The intervention design built on existing successful models by teaching specific communication tasks linked to the patient's trajectory of illness. This study evaluated the efficacy of Oncotalk in changing observable communication behaviors. Oncotalk was a 4-day residential workshop emphasizing skills practice in small groups. This preintervention and postintervention cohort study involved 115 medical oncology fellows from 62 different institutions during a 3-year study. The primary outcomes were observable participant communication skills measured during standardized patient encounters before and after the workshop in giving bad news and discussing transitions to palliative care. The standardized patient encounters were audiorecorded and assessed by blinded coders using a validated coding system. Before-after comparisons were made using each participant as his or her own control. Compared with preworkshop standardized patient encounters, postworkshop encounters showed that participants acquired a mean of 5.4 bad news skills (P<.001) and a mean of 4.4 transitions skills (P<.001). Most changes in individual skills were substantial; for example, in the bad news encounter, 16% of participants used the word "cancer" when giving bad news before the workshop, and 54% used it after the workshop (P<.001). Also in the bad news encounter, blinded coders were able to identify whether a standardized patient encounter occurred before or after the workshop in 91% of the audiorecordings. Oncotalk represents a successful teaching model for improving communication skills for postgraduate medical trainees.

Investigating Effect of Service Encounter, Value, and Satisfaction on Word of Mouth: An Outpatient Service Context.

PubMed

Hsu, Li-Chun

2018-01-13

This study investigates the relationships among service encounter, service value, patient satisfaction, and word-of-mouth (WOM) intention from the viewpoint of interactive marketing. Data were collected using a questionnaire survey. A total of 372 questionnaires were obtained and 350 of these questionnaires were valid (94.09%), and a structural equation model was used to analyze the data. This study proposed seven hypotheses, and five of the seven hypotheses were supported. Service encounters indirectly affect their patient WOM through service value and satisfaction. Therefore, service value and satisfaction play a crucial mediating role in linking service encounters and WOM. This study determined WOM intentions in an outpatient service context and provides crucial business implications for teaching hospitals to enable them to improve their service quality and achieve a sustainable operation.

Investigating Effect of Service Encounter, Value, and Satisfaction on Word of Mouth: An Outpatient Service Context

PubMed Central

Hsu, Li-Chun

2018-01-01

This study investigates the relationships among service encounter, service value, patient satisfaction, and word-of-mouth (WOM) intention from the viewpoint of interactive marketing. Data were collected using a questionnaire survey. A total of 372 questionnaires were obtained and 350 of these questionnaires were valid (94.09%), and a structural equation model was used to analyze the data. This study proposed seven hypotheses, and five of the seven hypotheses were supported. Service encounters indirectly affect their patient WOM through service value and satisfaction. Therefore, service value and satisfaction play a crucial mediating role in linking service encounters and WOM. This study determined WOM intentions in an outpatient service context and provides crucial business implications for teaching hospitals to enable them to improve their service quality and achieve a sustainable operation. PMID:29342842

Parameter estimation for stiff deterministic dynamical systems via ensemble Kalman filter

NASA Astrophysics Data System (ADS)

Arnold, Andrea; Calvetti, Daniela; Somersalo, Erkki

2014-10-01

A commonly encountered problem in numerous areas of applications is to estimate the unknown coefficients of a dynamical system from direct or indirect observations at discrete times of some of the components of the state vector. A related problem is to estimate unobserved components of the state. An egregious example of such a problem is provided by metabolic models, in which the numerous model parameters and the concentrations of the metabolites in tissue are to be estimated from concentration data in the blood. A popular method for addressing similar questions in stochastic and turbulent dynamics is the ensemble Kalman filter (EnKF), a particle-based filtering method that generalizes classical Kalman filtering. In this work, we adapt the EnKF algorithm for deterministic systems in which the numerical approximation error is interpreted as a stochastic drift with variance based on classical error estimates of numerical integrators. This approach, which is particularly suitable for stiff systems where the stiffness may depend on the parameters, allows us to effectively exploit the parallel nature of particle methods. Moreover, we demonstrate how spatial prior information about the state vector, which helps the stability of the computed solution, can be incorporated into the filter. The viability of the approach is shown by computed examples, including a metabolic system modeling an ischemic episode in skeletal muscle, with a high number of unknown parameters.

The Full Scope of Family Physicians' Work Is Not Reflected by Current Procedural Terminology Codes.

PubMed

Young, Richard A; Burge, Sandy; Kumar, Kaparaboyna Ashok; Wilson, Jocelyn

2017-01-01

The purpose of this study was to characterize the content of family physician (FP) clinic encounters, and to count the number of visits in which the FPs addressed issues not explicitly reportable by 99211 to 99215 and 99354 Current Procedural Terminology (CPT) codes with current reimbursement methods and based on examples provided in the CPT manual. The data collection instrument was modeled on the National Ambulatory Medical Care Survey. Trained assistants directly observed every other FP-patient encounter and recorded every patient concern, issue addressed by the physician (including care barriers related to health care systems and social determinants), and treatment ordered in clinics affiliated with 10 residencies of the Residency Research Network of Texas. A visit was deemed to include physician work that was not explicitly reportable if the number or nature of issues addressed exceeded the definitions or examples for 99205/99215 or 99214 + 99354 or a preventive service code, included the physician addressing health care system or social determinant issues, or included the care of a family member. In 982 physician-patient encounters, patients raised 517 different reasons for visit (total, 5278; mean, 5.4 per visit; range, 1 to 16) and the FPs addressed 509 different issues (total issues, 3587; mean, 3.7 per visit; range, 1 to 10). FPs managed 425 different medications, 18 supplements, and 11 devices. A mean of 3.9 chronic medications were continued per visit (range, 0 to 21) and 4.6 total medications were managed (range, 0 to 22). In 592 (60.3%) of the visits the FPs did work that was not explicitly reportable with available CPT codes: 582 (59.3%) addressed more numerous issues than explicitly reportable, 64 (6.5%) addressed system barriers, and 13 (1.3%) addressed concerns for other family members. FPs perform cognitive work in a majority of their patient encounters that are not explicitly reportable, either by being higher than the CPT example number of diagnoses per code or the type of problems addressed, which has implications for the care of complex multi-morbid patients and the growth of the primary care workforce. To address these limitations, either the CPT codes and their associated rules should be updated to reflect the realities of family physicians' practices or new billing and coding approaches should be developed. © Copyright 2017 by the American Board of Family Medicine.

A fully covariant mean-field dynamo closure for numerical 3 + 1 resistive GRMHD

NASA Astrophysics Data System (ADS)

Bucciantini, N.; Del Zanna, L.

2013-01-01

The powerful high-energy phenomena typically encountered in astrophysics invariably involve physical engines, like neutron stars and black hole accretion discs, characterized by a combination of highly magnetized plasmas, strong gravitational fields and relativistic motions. In recent years, numerical schemes for general relativistic magnetohydrodynamics (GRMHD) have been developed to model the multidimensional dynamics of such systems, including the possibility of evolving space-time. Such schemes have been also extended beyond the ideal limit including the effects of resistivity, in an attempt to model dissipative physical processes acting on small scales (subgrid effects) over the global dynamics. Along the same lines, the magnetic field could be amplified by the presence of turbulent dynamo processes, as often invoked to explain the high values of magnetization required in accretion discs and neutron stars. Here we present, for the first time, a further extension to include the possibility of a mean-field dynamo action within the framework of numerical 3 + 1 (resistive) GRMHD. A fully covariant dynamo closure is proposed, in analogy with the classical theory, assuming a simple α-effect in the comoving frame. Its implementation into a finite-difference scheme for GRMHD in dynamical space-times (the x-echo code by Bucciantini & Del Zanna) is described, and a set of numerical test is presented and compared with analytical solutions wherever possible.

Investigating the dynamical history of the interstellar object 'Oumuamua

NASA Astrophysics Data System (ADS)

Dybczyński, Piotr A.; Królikowska, Małgorzata

2018-02-01

Here we try to find the origin of 1I/2017 U1 'Oumuamua, the first interstellar object recorded inside the solar system. To this aim, we searched for close encounters between 'Oumuamua and all nearby stars with known kinematic data during their past motion. We had checked over 200 thousand stars and found just a handful of candidates. If we limit our investigation to within a 60 pc sphere surrounding the Sun, then the most probable candidate for the 'Oumuamua parent stellar habitat is the star UCAC4 535-065571. However GJ 876 is also a favourable candidate. However, the origin of 'Oumuamua from a much more distant source is still an open question. Additionally, we found that the quality of the original orbit of 'Oumuamua is accurate enough for such a study and that none of the checked stars had perturbed its motion significantly. All numerical results of this research are available in the appendix.

Vibration-translation energy transfer in vibrationally excited diatomic molecules. Ph.D. Thesis - York Univ., Toronto

NASA Technical Reports Server (NTRS)

Mckenzie, R. L.

1976-01-01

A semiclassical collision model is applied to the study of energy transfer rates between a vibrationally excited diatomic molecule and a structureless atom. The molecule is modeled as an anharmonic oscillator with a multitude of dynamically coupled vibrational states. Three main aspects in the prediction of vibrational energy transfer rates are considered. The applicability of the semiclassical model to an anharmonic oscillator is first evaluated for collinear encounters. Second, the collinear semiclassical model is applied to obtain numerical predictions of the vibrational energy transfer rate dependence on the initial vibrational state quantum number. Thermally averaged vibration-translation rate coefficients are predicted and compared with CO-He experimental values for both ground and excited initial states. The numerical model is also used as a basis for evaluating several less complete but analytic models. Third, the role of rational motion in the dynamics of vibrational energy transfer is examined. A three-dimensional semiclassical collision model is constructed with coupled rotational motion included. Energy transfer within the molecule is shown to be dominated by vibration-rotation transitions with small changes in angular momentum. The rates of vibrational energy transfer in molecules with rational frequencies that are very small in comparison to their vibrational frequency are shown to be adequately treated by the preceding collinear models.

Hypersonic separated flows about "tick" configurations with sensitivity to model design

NASA Astrophysics Data System (ADS)

Moss, J. N.; O'Byrne, S.; Gai, S. L.

2014-12-01

This paper presents computational results obtained by applying the direct simulation Monte Carlo (DSMC) method for hypersonic nonequilibrium flow about "tick-shaped" model configurations. These test models produces a complex flow where the nonequilibrium and rarefied aspects of the flow are initially enhanced as the flow passes over an expansion surface, and then the flow encounters a compression surface that can induce flow separation. The resulting flow is such that meaningful numerical simulations must have the capability to account for a significant range of rarefaction effects; hence the application of the DSMC method in the current study as the flow spans several flow regimes, including transitional, slip, and continuum. The current focus is to examine the sensitivity of both the model surface response (heating, friction and pressure) and flowfield structure to assumptions regarding surface boundary conditions and more extensively the impact of model design as influenced by leading edge configuration as well as the geometrical features of the expansion and compression surfaces. Numerical results indicate a strong sensitivity to both the extent of the leading edge sharpness and the magnitude of the leading edge bevel angle. Also, the length of the expansion surface for a fixed compression surface has a significant impact on the extent of separated flow.

Compressive Sensing with Cross-Validation and Stop-Sampling for Sparse Polynomial Chaos Expansions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huan, Xun; Safta, Cosmin; Sargsyan, Khachik

Compressive sensing is a powerful technique for recovering sparse solutions of underdetermined linear systems, which is often encountered in uncertainty quanti cation analysis of expensive and high-dimensional physical models. We perform numerical investigations employing several com- pressive sensing solvers that target the unconstrained LASSO formulation, with a focus on linear systems that arise in the construction of polynomial chaos expansions. With core solvers of l1 ls, SpaRSA, CGIST, FPC AS, and ADMM, we develop techniques to mitigate over tting through an automated selection of regularization constant based on cross-validation, and a heuristic strategy to guide the stop-sampling decision. Practical recommendationsmore » on parameter settings for these tech- niques are provided and discussed. The overall method is applied to a series of numerical examples of increasing complexity, including large eddy simulations of supersonic turbulent jet-in-cross flow involving a 24-dimensional input. Through empirical phase-transition diagrams and convergence plots, we illustrate sparse recovery performance under structures induced by polynomial chaos, accuracy and computational tradeoffs between polynomial bases of different degrees, and practi- cability of conducting compressive sensing for a realistic, high-dimensional physical application. Across test cases studied in this paper, we find ADMM to have demonstrated empirical advantages through consistent lower errors and faster computational times.« less

Hypersonic Separated Flows About "Tick" Configurations With Sensitivity to Model Design

NASA Technical Reports Server (NTRS)

Moss, J. N.; O'Byrne, S.; Gai, S. L.

2014-01-01

This paper presents computational results obtained by applying the direct simulation Monte Carlo (DSMC) method for hypersonic nonequilibrium flow about "tick-shaped" model configurations. These test models produces a complex flow where the nonequilibrium and rarefied aspects of the flow are initially enhanced as the flow passes over an expansion surface, and then the flow encounters a compression surface that can induce flow separation. The resulting flow is such that meaningful numerical simulations must have the capability to account for a significant range of rarefaction effects; hence the application of the DSMC method in the current study as the flow spans several flow regimes, including transitional, slip, and continuum. The current focus is to examine the sensitivity of both the model surface response (heating, friction and pressure) and flowfield structure to assumptions regarding surface boundary conditions and more extensively the impact of model design as influenced by leading edge configuration as well as the geometrical features of the expansion and compression surfaces. Numerical results indicate a strong sensitivity to both the extent of the leading edge sharpness and the magnitude of the leading edge bevel angle. Also, the length of the expansion surface for a fixed compression surface has a significant impact on the extent of separated flow.

Modeling of Dynamic Behavior of Carbon Fiber-Reinforced Polymer (CFRP) Composite under X-ray Radiation.

PubMed

Zhang, Kun; Tang, Wenhui; Fu, Kunkun

2018-01-16

Carbon fiber-reinforced polymer (CFRP) composites have been increasingly used in spacecraft applications. Spacecraft may encounter highenergy-density X-ray radiation in outer space that can cause severe damage. To protect spacecraft from such unexpected damage, it is essential to predict the dynamic behavior of CFRP composites under X-ray radiation. In this study, we developed an in-house three-dimensional explicit finite element (FEM) code to investigate the dynamic responses of CFRP composite under X-ray radiation for the first time, by incorporating a modified PUFF equation-of-state. First, the blow-off impulse (BOI) momentum of an aluminum panel was predicted by our FEM code and compared with an existing radiation experiment. Then, the FEM code was utilized to determine the dynamic behavior of a CFRP composite under various radiation conditions. It was found that the numerical result was comparable with the experimental one. Furthermore, the CFRP composite was more effective than the aluminum panel in reducing radiation-induced pressure and BOI momentum. The numerical results also revealed that a 1 keV X-ray led to vaporization of surface materials and a high-magnitude compressive stress wave, whereas a low-magnitude stress wave was generated with no surface vaporization when a 3 keV X-ray was applied.

Modeling of Dynamic Behavior of Carbon Fiber-Reinforced Polymer (CFRP) Composite under X-ray Radiation

PubMed Central

Zhang, Kun; Tang, Wenhui; Fu, Kunkun

2018-01-01

Carbon fiber-reinforced polymer (CFRP) composites have been increasingly used in spacecraft applications. Spacecraft may encounter highenergy-density X-ray radiation in outer space that can cause severe damage. To protect spacecraft from such unexpected damage, it is essential to predict the dynamic behavior of CFRP composites under X-ray radiation. In this study, we developed an in-house three-dimensional explicit finite element (FEM) code to investigate the dynamic responses of CFRP composite under X-ray radiation for the first time, by incorporating a modified PUFF equation-of-state. First, the blow-off impulse (BOI) momentum of an aluminum panel was predicted by our FEM code and compared with an existing radiation experiment. Then, the FEM code was utilized to determine the dynamic behavior of a CFRP composite under various radiation conditions. It was found that the numerical result was comparable with the experimental one. Furthermore, the CFRP composite was more effective than the aluminum panel in reducing radiation-induced pressure and BOI momentum. The numerical results also revealed that a 1 keV X-ray led to vaporization of surface materials and a high-magnitude compressive stress wave, whereas a low-magnitude stress wave was generated with no surface vaporization when a 3 keV X-ray was applied. PMID:29337891

What positive encounters with healthcare and social insurance staff promotes ability to return to work of long-term sickness absentees?

PubMed

Olsson, Daniel; Alexanderson, Kristina; Bottai, Matteo

2016-02-01

Previous studies suggest that positive encounters with healthcare and social insurance staff may be important in promoting return to work among long-term sickness absentees. This study aimed to identify more specifically what positive encounters are important for promoting ability to return to work. A questionnaire about different types of encounters was sent to 10,042 people in Sweden on sick leave for 6-8 months (58% responded). For each positive encounter, we estimated the marginal probability difference (PD) of return to work, adjusting for age, sex, education, sick-leave diagnosis, and the sum score of all other encounters. Adjusting for the other encounters is important since of the observed variables these were the strongest confounders. The positive encounters with both healthcare and social insurance staff significantly associated with promoting ability to return to work after adjusting for the other positive encounters were "Believed in my work capacity" PD=16.9 (95% CI: 12.0, 21.9) and 12.0 (6.3, 17.7), respectively; "Supported my suggestions for solutions": 9.5 (3.1, 15.9) and 11.6 (5.7, 17.4); "Was supportive and encouraging": 10.1 (3.6, 16.7) and 7.3 (1.7, 12.8). Additionally, the encounter with healthcare staff most strongly associated with promoting return to work was "Let me take responsibility" 14.8 (7.2, 22.3); and with social security staff: "Showed that she/he liked me" 10.4 (5.4, 15.4). Healthcare and social security staff being supportive, encouraging, and believing in the sickness absentee's work capacity may be very important for increasing the probability for long-term sickness absentees' ability to return to work. © 2015 the Nordic Societies of Public Health.

Patient-provider interaction during medication encounters: A study in outpatient pharmacies in the Netherlands.

PubMed

Koster, Ellen S; van Meeteren, Marijke M; van Dijk, Marloes; van de Bemt, Bart J F; Ensing, Hendrikus T; Bouvy, Marcel L; Blom, Lyda; van Dijk, Liset

2015-07-01

To describe communication between pharmacy staff and patients at the counter in outpatient pharmacies. Both content and communication style were investigated. Pharmaceutical encounters in three outpatient pharmacies in the Netherlands were video-recorded. Videos were analyzed based on an observation protocol for the following information: content of encounter, initiator of a theme and pharmacy staff's communication style. In total, 119 encounters were recorded which concerned 42 first prescriptions, 16 first refill prescriptions and 61 follow-up refill prescriptions. During all encounters, discussion was mostly initiated by pharmacy staff (85%). In first prescription encounters topics most frequently discussed included instructions for use (83%) and dosage instructions (95%). In first refill encounters, patient experiences such as adverse effects (44%) and beneficial effects (38%) were regularly discussed in contrast to follow-up refills (7% and 5%). Patients' opinion on medication was hardly discussed. Pharmacy staff in outpatient pharmacies generally provide practical information, less frequently they discuss patients' experiences and seldom discuss patients' perceptions and preferences about prescribed medication. This study shows there is room for improvement, as communication is still not according to professional guidelines. To implement professional guidelines successfully, it is necessary to identify underlying reasons for not following the guidelines. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Infinity Computer and Calculus

NASA Astrophysics Data System (ADS)

Sergeyev, Yaroslav D.

2007-09-01

Traditional computers work with finite numbers. Situations where the usage of infinite or infinitesimal quantities is required are studied mainly theoretically. In this survey talk, a new computational methodology (that is not related to nonstandard analysis) is described. It is based on the principle `The part is less than the whole' applied to all numbers (finite, infinite, and infinitesimal) and to all sets and processes (finite and infinite). It is shown that it becomes possible to write down finite, infinite, and infinitesimal numbers by a finite number of symbols as particular cases of a unique framework. The new methodology allows us to introduce the Infinity Computer working with all these numbers (its simulator is presented during the lecture). The new computational paradigm both gives possibilities to execute computations of a new type and simplifies fields of mathematics where infinity and/or infinitesimals are encountered. Numerous examples of the usage of the introduced computational tools are given during the lecture.

Multiple regression for physiological data analysis: the problem of multicollinearity.

PubMed

Slinker, B K; Glantz, S A

1985-07-01

Multiple linear regression, in which several predictor variables are related to a response variable, is a powerful statistical tool for gaining quantitative insight into complex in vivo physiological systems. For these insights to be correct, all predictor variables must be uncorrelated. However, in many physiological experiments the predictor variables cannot be precisely controlled and thus change in parallel (i.e., they are highly correlated). There is a redundancy of information about the response, a situation called multicollinearity, that leads to numerical problems in estimating the parameters in regression equations; the parameters are often of incorrect magnitude or sign or have large standard errors. Although multicollinearity can be avoided with good experimental design, not all interesting physiological questions can be studied without encountering multicollinearity. In these cases various ad hoc procedures have been proposed to mitigate multicollinearity. Although many of these procedures are controversial, they can be helpful in applying multiple linear regression to some physiological problems.

Molecular mechanisms underlying chemopreventive potential of curcumin: Current challenges and future perspectives.

PubMed

Kumar, Gaurav; Mittal, Sonam; Sak, Katrin; Tuli, Hardeep Singh

2016-03-01

In recent years, natural compounds have received considerable attention in preventing and curing most dreadful diseases including cancer. The reason behind the use of natural compounds in chemoprevention is associated with fewer numbers of side effects than conventional chemotherapeutics. Curcumin (diferuloylmethane, PubMed CID: 969516), a naturally occurring polyphenol, is derived from turmeric, which is used as a common Indian spice. It governs numerous intracellular targets, including proteins involved in antioxidant response, immune response, apoptosis, cell cycle regulation and tumor progression. A huge mass of available studies strongly supports the use of Curcumin as a chemopreventive drug. However, the main challenge encountered is the low bioavailability of Curcumin. This extensive review covers various therapeutic interactions of Curcumin with its recognized cellular targets involved in cancer treatment, strategies to overcome the bioavailability issue and adverse effects associated with Curcumin consumption. Copyright © 2016 Elsevier Inc. All rights reserved.

Deadzones, Dying Eddies, and the Loop Current: Stability, Ventilation, and Heat Content from Buoyancy Glider Observations in the Northwest Gulf of Mexico in Spring and Summer 2015

NASA Astrophysics Data System (ADS)

DiMarco, S. F.; Knap, A. H.; Wang, Z.; Walpert, J.; Dreger, K.

2016-02-01

The northwestern Gulf of Mexico is host to a myriad of physical and biochemical processes, which govern the exchange and transport of material and volume between the coastal and offshore environments. We report on five G2 Slocum glider deployments in the northwestern Gulf during the spring and summer of 2015. The gliders were deployed in shallow (20 m) and deep (greater than 1000 m) water for a total of about 200 days. During this time, the gliders encountered a variety of environmental conditions that impact the circulation, biology, chemistry of the shelf and slope. The shallow gliders encountered coastal waters influenced by extensive flooding in terrestrial Texas that vertically stratified the water-column and was coincident with sub-pycnocline low dissolved oxygen concentration, at times below the hypoxic threshold of 2 mg/L, and elevated CDOM concentrations. These gliders also reveal high spatial variability with bottom boundary oxygen and biomass scales on the order of a few kilometers. The deep gliders were tasked to investigate shelf/slope exchange at two locations 94W and 91W. The western glider encountered a mature mesoscale circulation eddy that was actively weakening. The eastern glider simultaneously encountered a freshly separated Loop Current eddy. The vertical structure of hydrographic and dissolved oxygen parameters shows significant and distinguishable variability in each feature. The vertical structure of both features show significant departures from that which is expected based on sea surface height determined from satellite altimetry. Additionally, glider observations are compared to operational high-resolution regional numerical model output. These observations emphasize the importance of direct observations over satellite-derived products for applications that include upper ocean heat content for hurricane intensification and vertical mixing and ventilation of the oceanic interior.

Comparison of histological features, and description of histopathological lesions in thyroid glands from three species of free-ranging sharks from the northwestern Atlantic, the blue shark, Prionace glauca (L.), the shortfin mako, Isurus oxyrhinchus Rafinesque, and the thresher, Alopias vulpinus (Bonnaterre).

PubMed

Borucinska, J D; Tafur, M

2009-09-01

Abstract Histomorphological features of piscine thyroids are widely accepted and frequently used as bioindicators of environmental pollution. This despite the fact that there is marked variation in thyroid morphology resulting from numerous pathological and physiological conditions. Our hypothesis was that there will be variations in histological features in thyroids collected from different shark species during the summer season in the northwestern Atlantic. To test our hypothesis, we examined histological features encountered in grossly normal thyroids from three species of sharks, the shortfin mako, Isurus oxyrhinchus, thresher, Alopias vulpinus and blue sharks, Prionace glauca. In addition, microscopic lesions from these thyroids were described. Ninety-four sharks were collected in summer 2001, 2002 and 2004. Routine, haematoxylin and eosin-stained paraffin-embedded sections were studied by light microscopy. We found inter-species but not intra-species variation in histological patterns of thyroids, which were distinct enough to allow 'blind' assignment of a thyroid to the specific species. The most common lesions encountered were lymphofollicular hyperplasia and chronic thyroiditis. In addition, one case each of intravascular larval nematodes and a myxosporean infection was found. Our results provide the first data on species-specific morphology of thyroids collected during summer months from sharks. The results indicate that familiarity with normal thyroid morphology is crucial before using shark thyroids in biomonitoring of environmental contamination or interpreting data from this gland in shark-health studies.

Chemorheology of reactive systems: Finite element analysis

NASA Technical Reports Server (NTRS)

Douglas, C.; Roylance, D.

1982-01-01

The equations which govern the nonisothermal flow of reactive fluids are outlined, and the means by which finite element analysis is used to solve these equations for the sort of arbitrary boundary conditions encountered in industrial practice are described. The performance of the computer code is illustrated by several trial problems, selected more for their value in providing insight to polymer processing flows than as practical production problems. Although a good deal remains to be learned as to the performance and proper use of this numerical technique, it is undeniably useful in providing better understanding of today's complicated polymer processing problems.

Design concerns of room and pillar retreat panels

PubMed Central

Klemetti, Ted M.; Sears, Morgan M.; Tulu, Ihsan B.

2017-01-01

Why do some room and pillar retreat panels encounter abnormal conditions? What factors deserve the most consideration during the planning and execution phases of mining and what can be done to mitigate those abnormal conditions when they are encountered? To help answer these questions, and to determine some of the relevant factors influencing the conditions of room and pillar (R & P) retreat mining entries, four consecutive R & P retreat panels were evaluated. This evaluation was intended to reinforce the influence of topographic changes, depth of cover, multiple-seam interactions, geological conditions, and mining geometry. This paper details observations were made in four consecutive R & P retreat panels and the data were collected from an instrumentation site during retreat mining. The primary focus was on the differences observed among the four panels and within the panels themselves. The instrumentation study was initially planned to evaluate the interactions between primary and secondary support, but produced rather interesting results relating to the loading encountered under the current mining conditions. In addition to the observation and instrumentation, numerical modeling was performed to evaluate the stress conditions. Both the LaModel 3.0 and Rocscience Phase 2 programs were used to evaluate these four panels. The results of both models indicated a drastic reduction in the vertical stresses experienced in these panels due to the full extraction mining in overlying seams when compared to the full overburden load. Both models showed a higher level of stress associated with the outside entries of the panels. These results agree quite well with the observations and instrumentation studies performed at the mine. These efforts provided two overarching conclusions concerning R & P retreat mine planning and execution. The first was that there are four areas that should not be overlooked during R & P retreat mining: topographic relief, multiple-seam stress relief, stress concentrations near the gob edge, and geologic changes in the immediate roof. The second is that in order to successfully retreat an R & P panel, a three-phased approach to the design and analysis of the panel should be conducted: the planning phase, evaluation phase, and monitoring phase. PMID:28626598

Local bifurcations in differential equations with state-dependent delay.

PubMed

Sieber, Jan

2017-11-01

A common task when analysing dynamical systems is the determination of normal forms near local bifurcations of equilibria. As most of these normal forms have been classified and analysed, finding which particular class of normal form one encounters in a numerical bifurcation study guides follow-up computations. This paper builds on normal form algorithms for equilibria of delay differential equations with constant delay that were developed and implemented in DDE-Biftool recently. We show how one can extend these methods to delay-differential equations with state-dependent delay (sd-DDEs). Since higher degrees of regularity of local center manifolds are still open for sd-DDEs, we give an independent (still only partial) argument which phenomena from the truncated normal must persist in the full sd-DDE. In particular, we show that all invariant manifolds with a sufficient degree of normal hyperbolicity predicted by the normal form exist also in the full sd-DDE.

Dilemmas in the (un)veiling of the diagnosis of Alzheimer's disease: walking an ethical and professional tight rope.

PubMed

Karnieli-Miller, Orit; Werner, Perla; Aharon-Peretz, Judith; Eidelman, Shmuel

2007-08-01

To enhance the understanding and effect of physician's difficulties, attitudes and communication styles on the disclosure of the diagnosis of AD in practice. Qualitative, phenomenological study, combining pre-encounter interviews with physicians, observations of actual encounters of diagnosis disclosure of AD, and post-encounter interviews. There were various ways or tactics to (un)veil the bad news that may be perceived as different ways of dulling the impact and avoiding full and therefore problematic statements. In the actual encounters this was accomplished by keeping encounters short, avoiding elaboration, confirmation of comprehension and explicit terminology and using fractured sentences. The present study's findings highlight the difficulties encountered in breaking the news about AD, in the way it is actually done, and the problems that may arise from this way of un/veiling the news. The main problem is that the reluctance to make a candid disclosure of the diagnosis as was demonstrated in this study may violate basic moral and legal rights and may also deprive patients and caregivers of some of the benefits of early disclosure of diagnosis. There is a need for assisting physicians to cope with their personal difficulties, problems and pitfalls in breaking the news.

Congenital hand anomalies in Upper Egypt

PubMed Central

Abulezz, Tarek; Talaat, Mohamed; Elsani, Asem; Allam, Karam

2016-01-01

Background: Congenital hand anomalies are numerous and markedly variant. Their significance is attributed to the frequent occurrence and their serious social, psychological and functional impacts on patient's life. Patients and Methods: This is a follow-up study of 64 patients with hand anomalies of variable severity. All patients were presented to Plastic Surgery Department of Sohag University Hospital in a period of 24 months. Results: This study revealed that failure of differentiation and duplication deformities were the most frequent, with polydactyly was the most common anomaly encountered. The mean age of presentation was 6 years and female to male ratio was 1.46:1. Hand anomalies were either isolated, associated with other anomalies or part of a syndrome. Conclusion: Incidence of congenital hand anomalies in Upper Egypt is difficult to be estimated due to social and cultural concepts, lack of education, poor registration and deficient medical survey. Management of hand anomalies should be individualised, carefully planned and started as early as possible to achieve the best outcome. PMID:27833283

Problems Encountered by Religious Vocational Secondary School and Other Secondary School Students in Physical Education and Sports Activities

ERIC Educational Resources Information Center

Bar, Mustafa; Yaman, Menzure Sibel; Hergüner, Gülten

2016-01-01

The study aimed to determine problems encountered by Religious Vocational Secondary School and other Secondary School students in physical education and sports activities and to compare these problems according to school type and gender. A questionnaire named "Problems encountered in attending to physical education and sports activities"…

Large-Eddy Simulation of Conductive Flows at Low Magnetic Reynolds Number

NASA Technical Reports Server (NTRS)

Knaepen, B.; Moin, P.

2003-01-01

In this paper we study the LES method with dynamic procedure in the context of conductive flows subject to an applied external magnetic field at low magnetic Reynolds number R(sub m). These kind of flows are encountered in many industrial applications. For example, in the steel industry, applied magnetic fields can be used to damp turbulence in the casting process. In nuclear fusion devices (Tokamaks), liquid-lithium flows are used as coolant blankets and interact with the surrounding magnetic field that drives and confines the fusion plasma. Also, in experimental facilities investigating the dynamo effect, the flow consists of liquid-sodium for which the Prandtl number and, as a consequence, the magnetic Reynolds number is low. Our attention is focused here on the case of homogeneous (initially isotropic) decaying turbulence. The numerical simulations performed mimic the thought experiment described in Moffatt in which an initially homogeneous isotropic conductive flow is suddenly subjected to an applied magnetic field and freely decays without any forcing. Note that this flow was first studied numerically by Schumann. It is well known that in that case, extra damping of turbulence occurs due to the Joule effect and that the flow tends to become progressively independent of the coordinate along the direction of the magnetic field. Our comparison of filtered direct numerical simulation (DNS) predictions and LES predictions show that the dynamic Smagorinsky model enables one to capture successfully the flow with LES, and that it automatically incorporates the effect of the magnetic field on the turbulence. Our paper is organized as follows. In the next section we summarize the LES approach in the case of MHD turbulence at low R(sub m) and recall the definition of the dynamic Smagorinsky model. In Sec. 3 we describe the parameters of the numerical experiments performed and the code used. Section 4 is devoted to the comparison of filtered DNS results and LES results. Conclusions are presented in Sec. 5.

Exploring the effects of individual customer incivility encounters on employee incivility: the moderating roles of entity (in)civility and negative affectivity.

PubMed

Walker, David D; van Jaarsveld, Danielle D; Skarlicki, Daniel P

2014-01-01

Incivility between customers and employees is common in many service organizations. These encounters can have negative outcomes for employees, customers, and the organization. To date, researchers have tended to study incivility as an aggregated and accumulated phenomenon (entity perspective). In the present study, we examined incivility as it occurs during a specific service encounter (event perspective) alongside the entity perspective. Using a mixed-method multilevel field study of customer service interactions, we show that individual customer incivility encounters (i.e., events) trigger employee incivility as a function of the employee's overall accumulated impression of the (in)civility in his or her customer interactions, such that the effects are more pronounced among employees who generally perceive their customer interactions to be more versus less civil. We also find that these interactive effects occur only among employees who are lower (vs. higher) in negative affectivity. Our results show that, in order to expand the understanding of customer incivility, it is important to study the incivility encounter, the social context in which negative customer interactions occur, and individual differences. PsycINFO Database Record (c) 2014 APA, all rights reserved

Analysis of severe atmospheric disturbances from airline flight records

NASA Technical Reports Server (NTRS)

Wingrove, R. C.; Bach, R. E., Jr.; Schultz, T. A.

1989-01-01

Advanced methods were developed to determine time varying winds and turbulence from digital flight data recorders carried aboard modern airliners. Analysis of several cases involving severe clear air turbulence encounters at cruise altitudes has shown that the aircraft encountered vortex arrays generated by destabilized wind shear layers above mountains or thunderstorms. A model was developed to identify the strength, size, and spacing of vortex arrays. This model is used to study the effects of severe wind hazards on operational safety for different types of aircraft. The study demonstrates that small remotely piloted vehicles and executive aircraft exhibit more violent behavior than do large airliners during encounters with high-altitude vortices. Analysis of digital flight data from the accident at Dallas/Ft. Worth in 1985 indicates that the aircraft encountered a microburst with rapidly changing winds embedded in a strong outflow near the ground. A multiple-vortex-ring model was developed to represent the microburst wind pattern. This model can be used in flight simulators to better understand the control problems in severe microburst encounters.

Simulation of the mechanical behavior of random fiber networks with different microstructure.

PubMed

Hatami-Marbini, H

2018-05-24

Filamentous protein networks are broadly encountered in biological systems such as cytoskeleton and extracellular matrix. Many numerical studies have been conducted to better understand the fundamental mechanisms behind the striking mechanical properties of these networks. In most of these previous numerical models, the Mikado algorithm has been used to represent the network microstructure. Here, a different algorithm is used to create random fiber networks in order to investigate possible roles of architecture on the elastic behavior of filamentous networks. In particular, random fibrous structures are generated from the growth of individual fibers from random nucleation points. We use computer simulations to determine the mechanical behavior of these networks in terms of their model parameters. The findings are presented and discussed along with the response of Mikado fiber networks. We demonstrate that these alternative networks and Mikado networks show a qualitatively similar response. Nevertheless, the overall elasticity of Mikado networks is stiffer compared to that of the networks created using the alternative algorithm. We describe the effective elasticity of both network types as a function of their line density and of the material properties of the filaments. We also characterize the ratio of bending and axial energy and discuss the behavior of these networks in terms of their fiber density distribution and coordination number.

Lattice Boltzmann modeling of boiling heat transfer: The boiling curve and the effects of wettability

DOE PAGES

Li, Q.; Kang, Q. J.; Francois, M. M.; ...

2015-03-03

A hybrid thermal lattice Boltzmann (LB) model is presented to simulate thermal multiphase flows with phase change based on an improved pseudopotential LB approach (Li et al., 2013). The present model does not suffer from the spurious term caused by the forcing-term effect, which was encountered in some previous thermal LB models for liquid–vapor phase change. Using the model, the liquid–vapor boiling process is simulated. The boiling curve together with the three boiling stages (nucleate boiling, transition boiling, and film boiling) is numerically reproduced in the LB community for the first time. The numerical results show that the basic featuresmore » and the fundamental characteristics of boiling heat transfer are well captured, such as the severe fluctuation of transient heat flux in the transition boiling and the feature that the maximum heat transfer coefficient lies at a lower wall superheat than that of the maximum heat flux. Moreover, the effects of the heating surface wettability on boiling heat transfer are investigated. It is found that an increase in contact angle promotes the onset of boiling but reduces the critical heat flux, and makes the boiling process enter into the film boiling regime at a lower wall superheat, which is consistent with the findings from experimental studies.« less

Simplified and refined structural modeling for economical flutter analysis and design

NASA Technical Reports Server (NTRS)

Ricketts, R. H.; Sobieszczanski, J.

1977-01-01

A coordinated use of two finite-element models of different levels of refinement is presented to reduce the computer cost of the repetitive flutter analysis commonly encountered in structural resizing to meet flutter requirements. One model, termed a refined model (RM), represents a high degree of detail needed for strength-sizing and flutter analysis of an airframe. The other model, called a simplified model (SM), has a relatively much smaller number of elements and degrees-of-freedom. A systematic method of deriving an SM from a given RM is described. The method consists of judgmental and numerical operations to make the stiffness and mass of the SM elements equivalent to the corresponding substructures of RM. The structural data are automatically transferred between the two models. The bulk of analysis is performed on the SM with periodical verifications carried out by analysis of the RM. In a numerical example of a supersonic cruise aircraft with an arrow wing, this approach permitted substantial savings in computer costs and acceleration of the job turn-around.

Long-term risk analysis associated with nuclear waste disposal in space

NASA Technical Reports Server (NTRS)

Friedlander, A. L.; Davis, D. R.

1979-01-01

An assessment and verification of previous analytic results on the long term risk of earth reentry for hazardous payloads is presented. The two areas were studied: (1) stability of nominal, near-circular storage orbits in the regions between Venus and earth and between earth and Mars, and (2) probability of earth reentry for off-nominal planet-crossing orbits resulting from deployment system failures. In the first area, numerical integrations of the equations of motion are compared with stability predications based on secular perturbation theory. The agreement is good in terms of the heliocentric distances covered and the general behavior of the orbital history, although certain near-resonance situations can lead to difficulty. In the second area, a Monte Carlo simulation of orbital evolution is used and the results compared with Opik's analytic theory of planetary encounters and collision statistics, with data verified to within a close order-of-magnitude.

Communication Patterns in Preschool Education Institutions – Practical Examples

PubMed Central

Radic-Hozo, Endica

2014-01-01

Introduction: Proper communication in pre-school institutions for education is undeniable importance to the development of the child, as evidenced by numerous studies. After the child's birth follows the most complex phase in its early phases - preschool education. Only high-quality, synergistic relationship triad: parent-child-educator and the modern postulates of preschool child education, warrants successful preschool child education. Methods and materials: Description, with examples from daily practice in a large institution for preschool education, marked were the critical points on the complex way in child education, many pitfalls encountered by both parents and educators. Considered are the errors in communication with the proposed solution to avoid the same in practice. Conclusion: Proper, daily communication in the preschool institution for education, within a relationship between parent-child-educator, mutual consultation, respect, acceptance, facilitation, resulting in successful common goal - the proper education and socialization of children in institutions for preschool education. PMID:25568636

Thermal Evolution of Juvenile Subduction Zones ' New Constraints from Lu-Hf Geochronology on HP oceanic rocks (Halilbaǧi, Central Anatolia)

NASA Astrophysics Data System (ADS)

Pourteau, Amaury; Scherer, Erik; Schmidt, Alexander; Bast, Rebecca

2015-04-01

The thermal structure of subduction zones plays a key role on mechanical and chemical processes taking place along the slab-mantle interface. Until now, changes through time of this thermal structure have been explored mostly by the means of numerical simulations. However, both "warm" (i.e., epidote-bearing), and "cold" (i.e., lawsonite-bearing) HP oceanic rocks have been reported in some fossil subduction complexes exposed at the Earth's surface (e.g., Franciscan Complex, California; Rio San Juan Complex, Hispañola; Halilbağı Unit, Central Anatolia). These a-priori "incompatible" rocks witness different thermal stages of ancient subduction zones and their study might provide complementary constraints to numerical models. To decipher the meaning of these contrasting metamorphic rocks in the Halilbağı Unit, we are carrying out Lu-Hf geochronology on garnet (grt) and lws from a variety of HP oceanic rocks, as well as the metamorphic sole of the overlying ophiolite. We selected five samples that are representative of the variety of metamorphic evolutions (i.e. peak conditions and P-T paths) encountered in this area. Preliminary analyses yielded 110 Ma (grt-hbl isochron) for a sub-ophiolitic grt amphibolite; 92 Ma (grt-omp) for an eclogite with prograde and retrograde ep; 90 Ma (grt-omp) for an eclogitic metabasite with prograde ep and retrograde ep+lws; 87 Ma (grt-gln) for a lws eclogite with prograde ep; and 86 Ma (grt-gln) for a blueschist with prograde and retrograde lws. These ages are mainly two-point isochrons. Further-refined data will be presented at the EGU General Assembly 2015, in Vienna. The consistent younging trend from "warm" to "cold" metamorphic rocks revealed by these first-order results points to metamorphic-sole formation during the initiation of intra-oceanic subduction at ~110 Ma, and subsequent cooling of the slab-mantle interface between 92 and 86 Ma. Therefore, the contrasting metamorphic evolutions encountered in the Halilbağı Unit record the progressive thermal maturation of the juvenile Neotethyan subduction zone. This period of ~23 myr between subduction initiation and thermal "steady state" is significantly shorter than that obtained for the Rio San Juan Complex (~60 myr; Krebs et al. 2008, Lithos, 103, 106-137), but compares well with that for the Franciscan Complex (~22 myr; Anczkiewicz et al. 2004, EPSL, 225, 147-161) and falls in the range predicted in numerical simulations (e.g., Gerya et al. 2002, Tectonics, 21/6, 1056).

Assessing the Risk of Prehospital Administration of Naloxone with Subsequent Refusal of Care.

PubMed

Levine, Michael; Sanko, Stephen; Eckstein, Marc

2016-01-01

EMS providers frequently encounter opioid-toxic patients who receive naloxone and then refuse further medical care. Older studies revealed this practice to be safe. In light of the evolving patterns of opioid abuse, this study attempted to determine the safety of this practice. This is a retrospective review of all patient encounters by the Los Angeles Fire Department (LAFD) between July 1, 2011-December 31, 2013. All LAFD patient encounters are stored electronically. These electronic records were reviewed for subjects who received naloxone had a documented respiratory rate (RR) less than 12, and subsequently refused transport. Data abstracted included name, social security number (SSN), date of birth (DOB), date of EMS encounter, age, and treatment rendered. The names, SSN, and DOB, as available, were supplied to the coroner's office. The Coroner's records were reviewed to determine if a patient with the same or similar name (e.g., Jon vs. Jonathan) had died within 24 hours, 30 days, or 6 months of the initial EMS encounter. The abstractor was blinded to the study hypothesis. 205 subjects were identified; the median (IQR) age was 41 (29-53) years. 27 (13%) were female. One subject (0.49%) died within 24 hours of the initial EMS encounter. The cause of death (COD) was coronary artery disease and heroin use. Two additional subjects (1. %) died within 30 days. One of these subjects died 6 days later; the COD is unknown. The other subject died 20 days after the EMS encounter; the COD was cardiovascular disease and liver cirrhosis. No additional subjects were identified at the 6 month follow up. A third subject died of a heroin overdose 16 months after the initial EMS encounter, but was beyond the pre-defined follow up period. The practice of receiving pre-hospital naloxone by paramedics and subsequently refusing care is associated with an extremely low short- and intermediate-term mortality. Despite an evolving pattern of opioid abuse, the results of this study are consistent with previously reported studies.

Inconsistencies in Numerical Simulations of Dynamical Systems Using Interval Arithmetic

NASA Astrophysics Data System (ADS)

Nepomuceno, Erivelton G.; Peixoto, Márcia L. C.; Martins, Samir A. M.; Rodrigues, Heitor M.; Perc, Matjaž

Over the past few decades, interval arithmetic has been attracting widespread interest from the scientific community. With the expansion of computing power, scientific computing is encountering a noteworthy shift from floating-point arithmetic toward increased use of interval arithmetic. Notwithstanding the significant reliability of interval arithmetic, this paper presents a theoretical inconsistency in a simulation of dynamical systems using a well-known implementation of arithmetic interval. We have observed that two natural interval extensions present an empty intersection during a finite time range, which is contrary to the fundamental theorem of interval analysis. We have proposed a procedure to at least partially overcome this problem, based on the union of the two generated pseudo-orbits. This paper also shows a successful case of interval arithmetic application in the reduction of interval width size on the simulation of discrete map. The implications of our findings on the reliability of scientific computing using interval arithmetic have been properly addressed using two numerical examples.

A monotonicity preserving conservative sharp interface flow solver for high density ratio two-phase flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Le Chenadec, Vincent, E-mail: vlechena@stanford.edu; Pitsch, Heinz; Institute for Combustion Technology, RWTH Aachen, Templergraben 64, 52056 Aachen

2013-09-15

This paper presents a novel approach for solving the conservative form of the incompressible two-phase Navier–Stokes equations. In order to overcome the numerical instability induced by the potentially large density ratio encountered across the interface, the proposed method includes a Volume-of-Fluid type integration of the convective momentum transport, a monotonicity preserving momentum rescaling, and a consistent and conservative Ghost Fluid projection that includes surface tension effects. The numerical dissipation inherent in the Volume-of-Fluid treatment of the convective transport is localized in the interface vicinity, enabling the use of a kinetic energy conserving discretization away from the singularity. Two- and three-dimensionalmore » tests are presented, and the solutions shown to remain accurate at arbitrary density ratios. The proposed method is then successfully used to perform the detailed simulation of a round water jet emerging in quiescent air, therefore suggesting the applicability of the proposed algorithm to the computation of realistic turbulent atomization.« less

Absorbing Boundary Conditions in Quantum Relativistic Mechanics for Spinless Particles Subject to a Classical Electromagnetic Field

NASA Astrophysics Data System (ADS)

Sater, Julien

The theory of Artificial Boundary Conditions described by Antoine et al. [2,4-6] for the Schrodinger equation is applied to the Klein-Gordon (KG) in two-dimensions (2-D) for spinless particles subject to electromagnetic fields. We begin by providing definitions for a basic understanding of the theory of operators, differential geometry and wave front sets needed to discuss the factorization theorem thanks to Nirenberg and Hormander [14, 16]. The laser-free Klein-Gordon equation in 1-D is then discussed, followed by the case including electrodynamics potentials, concluding with the KG equation in 2-D space with electrodynamics potentials. We then consider numerical simulations of the laser-particle KG equation, which includes a brief analysis of a finite difference scheme. The conclusion integrates a discussion of the numerical results, the successful completion of the objective set forth, a declaration of the unanswered encountered questions and a suggestion of subjects for further research.

Real fuel effects on flame extinction and re-ignition

NASA Astrophysics Data System (ADS)

Zhao, Xinyu; Wu, Bifen; Xu, Chao; Lu, Tianfeng; Chen, Jacqueline H.

2016-11-01

Flame-vortex interactions have significant implications in studying combustion in practical aeronautical engines, and can be used to facilitate the model development in capturing local extinction and re-ignition. To study the interactions between the complex fuel and the intense turbulence that are commonly encountered in engines, direct numerical simulations of the interactions between a flame and a vortex pair are carried out using a recently-developed 24-species reduced chemistry for n-dodecane. Both non-premixed and premixed flames with different initial and inlet thermochemical conditions are studied. Parametric studies of different vortex strengths and orientations are carried out to induce maximum local extinction and re-ignition. Chemical-explosive-mode-analysis based flame diagnostic tools are used to identify different modes of combustion, including auto-ignition and extinction. Results obtained from the reduced chemistry are compared with those obtained from one-step chemistry to quantify the effect of fuel pyrolysis on the extinction limit. Effects of flame curvature, heat loss and unsteadiness on flame extinction are also explored. Finally, the validity of current turbulent combustion models to capture the local extinction and re-ignition will be discussed.

Applications of computer algebra to distributed parameter systems

NASA Technical Reports Server (NTRS)

Storch, Joel A.

1993-01-01

In the analysis of vibrations of continuous elastic systems, one often encounters complicated transcendental equations with roots directly related to the system's natural frequencies. Typically, these equations contain system parameters whose values must be specified before a numerical solution can be obtained. The present paper presents a method whereby the fundamental frequency can be obtained in analytical form to any desired degree of accuracy. The method is based upon truncation of rapidly converging series involving inverse powers of the system natural frequencies. A straightforward method to developing these series and summing them in closed form is presented. It is demonstrated how Computer Algebra can be exploited to perform the intricate analytical procedures which otherwise would render the technique difficult to apply in practice. We illustrate the method by developing two analytical approximations to the fundamental frequency of a vibrating cantilever carrying a rigid tip body. The results are compared to the numerical solution of the exact (transcendental) frequency equation over a range of system parameters.

Driving behaviour responses to a moose encounter, automatic speed camera, wildlife warning sign and radio message determined in a factorial simulator study.

PubMed

Jägerbrand, Annika K; Antonson, Hans

2016-01-01

In a driving simulator study, driving behaviour responses (speed and deceleration) to encountering a moose, automatic speed camera, wildlife warning sign and radio message, with or without a wildlife fence and in dense forest or open landscape, were analysed. The study consisted of a factorial experiment that examined responses to factors singly and in combination over 9-km road stretches driven eight times by 25 participants (10 men, 15 women). The aims were to: determine the most effective animal-vehicle collision (AVC) countermeasures in reducing vehicle speed and test whether these are more effective in combination for reducing vehicle speed; identify the most effective countermeasures on encountering moose; and determine whether the driving responses to AVC countermeasures are affected by the presence of wildlife fences and landscape characteristics. The AVC countermeasures that proved most effective in reducing vehicle speed were a wildlife warning sign and radio message, while automatic speed cameras had a speed-increasing effect. There were no statistically significant interactions between different countermeasures and moose encounters. However, there was a tendency for a stronger speed-reducing effect from the radio message warning and from a combination of a radio message and wildlife warning sign in velocity profiles covering longer driving distances than the statistical tests. Encountering a moose during the drive had the overall strongest speed-reducing effect and gave the strongest deceleration, indicating that moose decoys or moose artwork might be useful as speed-reducing countermeasures. Furthermore, drivers reduced speed earlier on encountering a moose in open landscape and had lower velocity when driving past it. The presence of a wildlife fence on encountering the moose resulted in smaller deceleration. Copyright © 2015 Elsevier Ltd. All rights reserved.

Further Studies of the Response of Single Rotor Helicopters to Vortex Encounters

DOT National Transportation Integrated Search

1985-09-01

This report is a continuation of the studies described in Reference where a simplified approach to the problem of predicting the uncontrolled response of a single rotor helicopter to an encounter with the wing tip vortex of a large transport aircraft...

Pedagogical encounters between nurses and patients in a medical ward--a field study.

PubMed

Friberg, F; Andersson, E Pilhammar; Bengtsson, J

2007-05-01

Patient teaching is regarded as an important aspect of nursing care as well as an essential part of the nursing profession. In nursing practice, a distinction can be made between formal (planned) and informal (spontaneous) patient teaching. The major part of patient teaching research is within the area of formal teaching. In spite of the fact that spontaneous teaching occurs in everyday nursing practice, there is a lack of knowledge in this area. The aim was to illuminate pedagogical dimensions in nursing situations and informal teaching. The study is a fieldwork study within the frames of a life-world phenomenological tradition. Fifteen registered nurses in a general medical ward of a university hospital in Sweden were followed in their daily work with patients. Twelve patients suffering from various chronic diseases were interviewed. The observations comprised a total of 173 h on 34 separate occasions. Informal dialogues with nurses were carried through. Further, formal interviews were conducted with 12 of the observed patients. The data were analysed by means of a life-world phenomenological approach. Two different pedagogical encounters are presented: "Players in different field pedagogical encounters", in which there is a breakdown in the pedagogical dialogue, and "Players in same field pedagogical encounters", in which the pedagogical dialogue develops. Patients' experiences of seeking and acquiring knowledge within these two types of encounter are characterised as "worry" versus "preparedness". Patients' dignity is either threatened or supported, depending on the type of encounter. Health care organisations have to create a pedagogical climate where "Same field pedagogical encounters" can be created. The nurse has to view the patient as a learning person in order to help the patient to achieve "preparedness". "Preparedness" is described as a cognitive-emotive-existential state and emphasised as an important goal of patient teaching.

Effect of first-encounter pretest on pass/fail rates of a clinical skills medical licensure examination.

PubMed

Roberts, William L; McKinley, Danette W; Boulet, John R

2010-05-01

Due to the high-stakes nature of medical exams it is prudent for test agencies to critically evaluate test data and control for potential threats to validity. For the typical multiple station performance assessments used in medicine, it may take time for examinees to become comfortable with the test format and administrative protocol. Since each examinee in the rotational sequence starts with a different task (e.g., simulated clinical encounter), those who are administered non-scored pretest material on their first station may have an advantage compared to those who are not. The purpose of this study is to investigate whether pass/fail rates are different across the sequence of pretest encounters administered during the testing day. First-time takers were grouped by the sequential order in which they were administered the pretest encounter. No statistically significant difference in fail rates was found between examinees who started with the pretest encounter and those who encountered the pretest encounter later in the sequence. Results indicate that current examination administration protocols do not present a threat to the validity of test score interpretations.

Male Escorts' and Male Clients' Sexual Behavior During Their Last Commercial Sexual Encounter: Comparing and Contrasting Findings from Two Online Studies.

PubMed

Grov, Christian; Rodríguez-Díaz, Carlos E; Jovet-Toledo, Gerardo G

2016-05-01

Much of what is known about commercial sexual encounters between men is based on data gathered from escorts. With few exceptions, studies have not compared male clients' reports of behavior during commercial sexual encounters with male escorts'. The present study draws from two datasets, a 2012 survey of clients (n = 495) and a 2013 survey of escorts (n = 387)--both used virtually identical measures of sexual behavior during the most recent commercial sexual encounter. For clients and escorts, the majority eschewed having sex without a condom, and kissing and oral sex were among the most common behaviors reported. Using logistic regression, both samples were compared across 15 sexual behaviors, finding significant differences in six--the escort sample had greater odds of reporting their last commercial sexual encounter involved watching the client masturbate, viewing porn, role play (dad/son, dominant/submissive), and having prior sexual experience with their commercial partner. The escort sample had lower odds of reporting that the client watched the escort masturbate, and being told partner's HIV status. In multivariable modeling, both samples did not significantly differ in reports of condomless anal sex. Male-male commercial sexual encounters appear to be involved in a wide range of sexual behaviors, many of which convey low-to-no risk of HIV transmission.

Program manual for HILTOP, a heliocentric interplanetary low thrust trajectory optimization program. Part 1: User's guide

NASA Technical Reports Server (NTRS)

Mann, F. I.; Horsewood, J. L.

1974-01-01

A performance-analysis computer program, that was developed explicitly to generate optimum electric propulsion trajectory data for missions of interest in the exploration of the solar system is presented. The program was primarily designed to evaluate the performance capabilities of electric propulsion systems, and in the simulation of a wide variety of interplanetary missions. A numerical integration of the two-body, three-dimensional equations of motion and the Euler-Lagrange equations was used in the program. Transversality conditions which permit the rapid generation of converged maximum-payload trajectory data, and the optimization of numerous other performance indices for which no transversality conditions exist are included. The ability to simulate constrained optimum solutions, including trajectories having specified propulsion time and constant thrust cone angle, is also in the program. The program was designed to handle multiple-target missions with various types of encounters, such as rendezvous, stopover, orbital capture, and flyby. Performance requirements for a variety of launch vehicles can be determined.

Solution of 3-dimensional time-dependent viscous flows. Part 3: Application to turbulent and unsteady flows

NASA Technical Reports Server (NTRS)

Weinberg, B. C.; Mcdonald, H.

1982-01-01

A numerical scheme is developed for solving the time dependent, three dimensional compressible viscous flow equations to be used as an aid in the design of helicopter rotors. In order to further investigate the numerical procedure, the computer code developed to solve an approximate form of the three dimensional unsteady Navier-Stokes equations employing a linearized block implicit technique in conjunction with a QR operator scheme is tested. Results of calculations are presented for several two dimensional boundary layer flows including steady turbulent and unsteady laminar cases. A comparison of fourth order and second order solutions indicate that increased accuracy can be obtained without any significant increases in cost (run time). The results of the computations also indicate that the computer code can be applied to more complex flows such as those encountered on rotating airfoils. The geometry of a symmetric NACA four digit airfoil is considered and the appropriate geometrical properties are computed.

EFFECTS OF DYNAMICAL EVOLUTION OF GIANT PLANETS ON SURVIVAL OF TERRESTRIAL PLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsumura, Soko; Ida, Shigeru; Nagasawa, Makiko

2013-04-20

The orbital distributions of currently observed extrasolar giant planets allow marginally stable orbits for hypothetical, terrestrial planets. In this paper, we propose that many of these systems may not have additional planets on these ''stable'' orbits, since past dynamical instability among giant planets could have removed them. We numerically investigate the effects of early evolution of multiple giant planets on the orbital stability of the inner, sub-Neptune-like planets which are modeled as test particles, and determine their dynamically unstable region. Previous studies have shown that the majority of such test particles are ejected out of the system as a resultmore » of close encounters with giant planets. Here, we show that secular perturbations from giant planets can remove test particles at least down to 10 times smaller than their minimum pericenter distance. Our results indicate that, unless the dynamical instability among giant planets is either absent or quiet like planet-planet collisions, most test particles down to {approx}0.1 AU within the orbits of giant planets at a few AU may be gone. In fact, out of {approx}30% of survived test particles, about three quarters belong to the planet-planet collision cases. We find a good agreement between our numerical results and the secular theory, and present a semi-analytical formula which estimates the dynamically unstable region of the test particles just from the evolution of giant planets. Finally, our numerical results agree well with the observations, and also predict the existence of hot rocky planets in eccentric giant planet systems.« less

Stereotype threat and racial differences in citizens' experiences of police encounters.

PubMed

Najdowski, Cynthia J; Bottoms, Bette L; Goff, Phillip Atiba

2015-10-01

We conducted 2 studies to investigate how cultural stereotypes that depict Blacks as criminals affect the way Blacks experience encounters with police officers, expecting that such encounters induce Blacks to feel stereotype threat (i.e., concern about being judged and treated unfairly by police because of the stereotype). In Study 1, we asked Black and White participants to report how they feel when interacting with police officers in general. As predicted, Blacks, but not Whites, reported concern that police officers stereotype them as criminals simply because of their race. In addition, this effect was found for Black men but not Black women. In Study 2, we asked Black and White men to imagine a specific police encounter and assessed potential downstream consequences of stereotype threat. Consistent with Study 1, Black but not White men anticipated feeling stereotype threat in the hypothetical police encounter. Further, racial differences in anticipated threat translated into racial differences in anticipated anxiety, self-regulatory efforts, and behavior that is commonly perceived as suspicious by police officers. By demonstrating that Blacks might expect to be judged and treated unfairly by police because of the negative stereotype of Black criminality, this research extends stereotype threat theory to the new domain of criminal justice encounters. It also has practical implications for understanding how the stereotype could ironically contribute to bias-based policing and racial disparities in the justice system. (c) 2015 APA, all rights reserved).

Inter-rater Agreement of End-of-shift Evaluations Based on a Single Encounter

PubMed Central

Warrington, Steven; Beeson, Michael; Bradford, Amber

2017-01-01

Introduction End-of-shift evaluation (ESE) forms, also known as daily encounter cards, represent a subset of encounter-based assessment forms. Encounter cards have become prevalent for formative evaluation, with some suggesting a potential for summative evaluation. Our objective was to evaluate the inter-rater agreement of ESE forms using a single scripted encounter at a conference of emergency medicine (EM) educators. Methods Following institutional review board exemption, we created a scripted video simulating an encounter between an intern and a patient with an ankle injury. That video was shown during a lecture at the Council of EM Residency Director’s Academic Assembly with attendees asked to evaluate the “resident” using one of eight possible ESE forms randomly distributed. Descriptive statistics were used to analyze the results with Fleiss’ kappa to evaluate inter-rater agreement. Results Most of the 324 respondents were leadership in residency programs (66%), with a range of 29–47 responses per evaluation form. Few individuals (5%) felt they were experts in assessing residents based on EM milestones. Fleiss’ kappa ranged from 0.157 – 0.308 and did not perform much better in two post-hoc subgroup analyses. Conclusion The kappa ranges found show only slight to fair inter-rater agreement and raise concerns about the use of ESE forms in assessment of EM residents. Despite limitations present in this study, these results and a lack of other studies on inter-rater agreement of encounter cards should prompt further studies of such methods of assessment. Additionally, EM educators should focus research on methods to improve inter-rater agreement of ESE forms or other evaluating other methods of assessment of EM residents. PMID:28435505

What is a medical decision? A taxonomy based on physician statements in hospital encounters: a qualitative study

PubMed Central

Ofstad, Eirik H; Frich, Jan C; Schei, Edvin; Frankel, Richard M; Gulbrandsen, Pål

2016-01-01

Objective The medical literature lacks a comprehensive taxonomy of decisions made by physicians in medical encounters. Such a taxonomy might be useful in understanding the physician-centred, patient-centred and shared decision-making in clinical settings. We aimed to identify and classify all decisions emerging in conversations between patients and physicians. Design Qualitative study of video recorded patient–physician encounters. Participants and setting 380 patients in consultations with 59 physicians from 17 clinical specialties and three different settings (emergency room, ward round, outpatient clinic) in a Norwegian teaching hospital. A randomised sample of 30 encounters from internal medicine was used to identify and classify decisions, a maximum variation sample of 20 encounters was used for reliability assessments, and the remaining encounters were analysed to test for applicability across specialties. Results On the basis of physician statements in our material, we developed a taxonomy of clinical decisions—the Decision Identification and Classification Taxonomy for Use in Medicine (DICTUM). We categorised decisions into 10 mutually exclusive categories: gathering additional information, evaluating test results, defining problem, drug-related, therapeutic procedure-related, legal and insurance-related, contact-related, advice and precaution, treatment goal, and deferment. Four-coder inter-rater reliability using Krippendorff's α was 0.79. Conclusions DICTUM represents a precise, detailed and comprehensive taxonomy of medical decisions communicated within patient–physician encounters. Compared to previous normative frameworks, the taxonomy is descriptive, substantially broader and offers new categories to the variety of clinical decisions. The taxonomy could prove helpful in studies on the quality of medical work, use of time and resources, and understanding of why, when and how patients are or are not involved in decisions. PMID:26868946

Switches to English during French Service Encounters: Relationships with L2 French Speakers' Willingness to Communicate and Motivation

ERIC Educational Resources Information Center

McNaughton, Stephanie; McDonough, Kim

2015-01-01

This exploratory study investigated second language (L2) French speakers' service encounters in the multilingual setting of Montreal, specifically whether switches to English during French service encounters were related to L2 speakers' willingness to communicate or motivation. Over a two-week period, 17 French L2 speakers in Montreal submitted…

Numerical Nudging: Using an Accelerating Score to Enhance Performance.

PubMed

Shen, Luxi; Hsee, Christopher K

2017-08-01

People often encounter inherently meaningless numbers, such as scores in health apps or video games, that increase as they take actions. This research explored how the pattern of change in such numbers influences performance. We found that the key factor is acceleration-namely, whether the number increases at an increasing velocity. Six experiments in both the lab and the field showed that people performed better on an ongoing task if they were presented with a number that increased at an increasing velocity than if they were not presented with such a number or if they were presented with a number that increased at a decreasing or constant velocity. This acceleration effect occurred regardless of the absolute magnitude or the absolute velocity of the number, and even when the number was not tied to any specific rewards. This research shows the potential of numerical nudging-using inherently meaningless numbers to strategically alter behaviors-and is especially relevant in the present age of digital devices.

Accurate orbit propagation in the presence of planetary close encounters

NASA Astrophysics Data System (ADS)

Amato, Davide; Baù, Giulio; Bombardelli, Claudio

2017-09-01

We present an efficient strategy for the numerical propagation of small Solar system objects undergoing close encounters with massive bodies. The trajectory is split into several phases, each of them being the solution of a perturbed two-body problem. Formulations regularized with respect to different primaries are employed in two subsequent phases. In particular, we consider the Kustaanheimo-Stiefel regularization and a novel set of non-singular orbital elements pertaining to the Dromo family. In order to test the proposed strategy, we perform ensemble propagations in the Earth-Sun Circular Restricted 3-Body Problem (CR3BP) using a variable step size and order multistep integrator and an improved version of Everhart's radau solver of 15th order. By combining the trajectory splitting with regularized equations of motion in short-term propagations (1 year), we gain up to six orders of magnitude in accuracy with respect to the classical Cowell's method for the same computational cost. Moreover, in the propagation of asteroid (99942) Apophis through its 2029 Earth encounter, the position error stays within 100 metres after 100 years. In general, as to improve the performance of regularized formulations, the trajectory must be split between 1.2 and 3 Hill radii from the Earth. We also devise a robust iterative algorithm to stop the integration of regularized equations of motion at a prescribed physical time. The results rigorously hold in the CR3BP, and similar considerations may apply when considering more complex models. The methods and algorithms are implemented in the naples fortran 2003 code, which is available online as a GitHub repository.

Complications of fluoroscopically directed facet joint nerve blocks: a prospective evaluation of 7,500 episodes with 43,000 nerve blocks.

PubMed

Manchikanti, Laxmaiah; Malla, Yogesh; Wargo, Bradley W; Cash, Kimberly A; Pampati, Vidyasagar; Fellows, Bert

2012-01-01

Chronic spinal pain is common along with numerous modalities of diagnostic and therapeutic interventions utilized, creating a health care crisis. Facet joint injections and epidural injections are the 2 most commonly utilized interventions in managing chronic spinal pain. While the literature addressing the effectiveness of facet joint nerve blocks is variable and emerging, there is paucity of literature on adverse effects of facet joint nerve blocks. A prospective, non-randomized study of patients undergoing interventional techniques from May 2008 to December 2009. A private interventional pain management practice, a specialty referral center in the United States. Investigation of the incidence in characteristics of adverse effects and complications of facet joint nerve blocks. The study was carried out over a period of 20 months including almost 7,500 episodes of 43,000 facet joint nerve blocks with 3,370 episodes in the cervical region, 3,162 in the lumbar region, and 950 in the thoracic region. All facet joint nerve blocks were performed under fluoroscopic guidance in an ambulatory surgery center by 3 physicians. The complications encountered during the procedure and postoperatively were evaluated prospectively. This study was carried out over a period of 20 months and included over 7,500 episodes or 43,000 facet joint nerve blocks. All of the interventions were performed under fluoroscopic guidance in an ambulatory surgery center by one of 3 physicians. The complications encountered during the procedure and postoperatively were prospectively evaluated. Measurable outcomes employed were intravascular entry of the needle, profuse bleeding, local hematoma, dural puncture and headache, nerve root or spinal cord irritation with resultant injury, and infectious complications. There were no major complications. Multiple side effects and complications observed included overall intravascular penetration in 11.4% of episodes with 20% in cervical region, 4% in lumbar region, and 6% in thoracic region; local bleeding in 76.3% of episodes with highest in thoracic region and lowest in cervical region; oozing with 19.6% encounters with highest in cervical region and lowest in lumbar region; with local hematoma seen only in 1.2% of the patients with profuse bleeding, bruising, soreness, nerve root irritation, and all other effects such as vasovagal reactions observed in 1% or less of the episodes. Limitations of this study include lack of contrast injection, use of intermittent fluoroscopy and also an observational nature of the study. This study illustrate that major complications are extremely rare and minor side effects are common.

Pioneer 11 Encounter. [with Jupiter

NASA Technical Reports Server (NTRS)

1975-01-01

Pioneer 11's encounter with Jupiter is discussed in detail. The scientific experiments carried out on the probe are described along with the instruments used. Tables are included which provide data on the times of experiments, encounters, and the distances from Jupiter. Educational study projects are also given.

Microlithiasis associated with chronic bronchopneumonia in a cat.

PubMed

Brummer, D G; French, T W; Cline, J M

1989-04-15

Chronic bronchopneumonia associated with microlithiasis was diagnosed in a 9-year-old domestic shorthair cat with a 3-month history of coughing and dyspnea. Thoracic radiography revealed multifocal patchy alveolar infiltrates in all lung fields. Numerous acellular, concentrically laminated, periodic acid-Schiff-positive microliths were seen in mucus from tracheal washing. Microliths were composed primarily of calcium carbonate. A definite cause could not be identified. There was no response to treatment and the cat was euthanatized. Marked type-II alveolar cell proliferation, peribronchiolar smooth muscle proliferation, and alveolar microlithiasis were seen histologically. Microliths are rarely encountered in tracheal washings from companion animals. Their pathophysiologic properties and meaning remain to be established.

Computer simulation of the probability that endangered whales will interact with oil spills, Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reed, M.; Jayko, K.; Bowles, A.

1986-10-01

A numerical model system was developed to assess quantitatively the probability that endangered bowhead and gray whales will encounter spilled oil in Alaskan waters. Bowhead and gray whale migration diving-surfacing models, and an oil-spill-trajectory model comprise the system. The migration models were developed from conceptual considerations, then calibrated with and tested against observations. The distribution of animals is represented in space and time by discrete points, each of which may represent one or more whales. The movement of a whale point is governed by a random-walk algorithm which stochastically follows a migratory pathway.

Hypersonic shock structure with Burnett terms in the viscous stress and heat flux

NASA Technical Reports Server (NTRS)

Chapman, Dean R.; Fiscko, Kurt A.

1988-01-01

The continuum Navier-Stokes and Burnett equations are solved for one-dimensional shock structure in various monatomic gases. A new numerical method is employed which utilizes the complete time-dependent continuum equations and obtains the steady-state shock structure by allowing the system to relax from arbitrary initial conditions. Included is discussion of numerical difficulties encountered when solving the Burnett equations. Continuum solutions are compared to those obtained utilizing the Direct Simulation Monte Carlo method. Shock solutions are obtained for a hard sphere gas and for argon from Mach 1.3 to Mach 50. Solutions for a Maxwellian gas are obtained from Mach 1.3 to Mach 3.8. It is shown that the Burnett equations yield shock structure solutions in much closer agreement to both Monte Carlo and experimental results than do the Navier-Stokes equations. Shock density thickness, density asymmetry, and density-temperature separation are all more accurately predicted by the Burnett equations than by the Navier-Stokes equations.

Rapid Holocene thinning of an East Antarctic outlet glacier driven by marine ice sheet instability

PubMed Central

Jones, R. S.; Mackintosh, A. N.; Norton, K. P.; Golledge, N. R.; Fogwill, C. J.; Kubik, P. W.; Christl, M.; Greenwood, S. L.

2015-01-01

Outlet glaciers grounded on a bed that deepens inland and extends below sea level are potentially vulnerable to ‘marine ice sheet instability'. This instability, which may lead to runaway ice loss, has been simulated in models, but its consequences have not been directly observed in geological records. Here we provide new surface-exposure ages from an outlet of the East Antarctic Ice Sheet that reveal rapid glacier thinning occurred approximately 7,000 years ago, in the absence of large environmental changes. Glacier thinning persisted for more than two and a half centuries, resulting in hundreds of metres of ice loss. Numerical simulations indicate that ice surface drawdown accelerated when the otherwise steadily retreating glacier encountered a bedrock trough. Together, the geological reconstruction and numerical simulations suggest that centennial-scale glacier thinning arose from unstable grounding line retreat. Capturing these instability processes in ice sheet models is important for predicting Antarctica's future contribution to sea level change. PMID:26608558

Temporal characteristics of decisions in hospital encounters: a threshold for shared decision making? A qualitative study.

PubMed

Ofstad, Eirik H; Frich, Jan C; Schei, Edvin; Frankel, Richard M; Gulbrandsen, Pål

2014-11-01

To identify and characterize physicians' statements that contained evidence of clinically relevant decisions in encounters with patients in different hospital settings. Qualitative analysis of 50 videotaped encounters from wards, the emergency room (ER) and outpatient clinics in a department of internal medicine at a Norwegian university hospital. Clinical decisions could be grouped in a temporal order: decisions which had already been made, and were brought into the encounter by the physician (preformed decisions), decisions made in the present (here-and-now decisions), and decisions prescribing future actions given a certain course of events (conditional decisions). Preformed decisions were a hallmark in the ward and conditional decisions a main feature of ER encounters. Clinical decisions related to a patient-physician encounter spanned a time frame exceeding the duration of the encounter. While a distribution of decisions over time and space fosters sharing and dilution of responsibility between providers, it makes the decision making process hard to access for patients. In order to plan when and how to involve patients in decisions, physicians need increased awareness of when clinical decisions are made, who usually makes them, and who should make them. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Having a Child Diagnosed with Cancer: Raising the Challenges Encountered by the Caregivers at the Pediatric Oncology Ward in Egypt

PubMed Central

2017-01-01

Having a child diagnosed with a life-threatening illness, and undergoing a severe treatment regimen, is a massive challenge for many caregivers, not the least of who are those with low socioeconomic status and living in a society where deeply rooted cultural and societal misconceptions are immensely noticeable. The aim of the study is to raise the great concerns experienced by the caregivers at the pediatric oncology ward in Egypt. The study is comprised of 24 caregivers of children with cancer undergoing treatment at the inpatient ward. Semi-structured interviews and participant observations were used as a means of data collection. Numerous concerns are addressed in this study which are all related to fear of the illness and guilty feelings of having caused the child this illness. The fears and concerns addressed in this paper seem to obstruct the caregivers’ overall psychosocial wellbeing, which is known to have multiple effects on the child’s overall wellbeing. Thus, it is very important to take into consideration caregivers in the child’s cancer treatment. PMID:29257054

Measuring the Process and Quality of Informed Consent for Clinical Research: Development and Testing

PubMed Central

Cohn, Elizabeth Gross; Jia, Haomiao; Smith, Winifred Chapman; Erwin, Katherine; Larson, Elaine L.

2013-01-01

Purpose/Objectives To develop and assess the reliability and validity of an observational instrument, the Process and Quality of Informed Consent (P-QIC). Design A pilot study of the psychometrics of a tool designed to measure the quality and process of the informed consent encounter in clinical research. The study used professionally filmed, simulated consent encounters designed to vary in process and quality. Setting A major urban teaching hospital in the northeastern region of the United States. Sample 63 students enrolled in health-related programs participated in psychometric testing, 16 students participated in test-retest reliability, and 5 investigator-participant dyads were observed for the actual consent encounters. Methods For reliability and validity testing, students watched and rated videotaped simulations of four consent encounters intentionally varied in process and content and rated them with the proposed instrument. Test-retest reliability was established by raters watching the videotaped simulations twice. Inter-rater reliability was demonstrated by two simultaneous but independent raters observing an actual consent encounter. Main Research Variables The essential elements of information and communication for informed consent. Findings The initial testing of the P-QIC demonstrated reliable and valid psychometric properties in both the simulated standardized consent encounters and actual consent encounters in the hospital setting. Conclusions The P-QIC is an easy-to-use observational tool that provides a quick assessment of the areas of strength and areas that need improvement in a consent encounter. It can be used in the initial trainings of new investigators or consent administrators and in ongoing programs of improvement for informed consent. Implications for Nursing The development of a validated observational instrument will allow investigators to assess the consent process more accurately and evaluate strategies designed to improve it. PMID:21708532

ACES M and S: Unmitigated Factorial Encounter Study on DAA/TCAS Interoperability

NASA Technical Reports Server (NTRS)

Thipphavong, David; Cone, Andrew; Park, Chunki; Lee, Seung Man; Santiago, Confesor

2016-01-01

Realization of the expected proliferation of Unmanned Aircraft System (UAS) operations in the National Airspace System (NAS) depends on the development and validation of standards for UAS Detect and Avoid (DAA) Systems. The RTCA Special Committee 228 is charged with leading the development of draft Minimum Operational Performance Standards (MOPS) for UAS DAA Systems. NASA, as a participating member of RTCA SC-228 is committed to supporting the development and validation of draft requirements for DAA alerting and guidance systems. This presentation contains the results of two combinatorial encounter analysis studies using NASA's SAA Control fast-time simulation capability for this purpose. In these studies, encounters between two aircraft were simulated one at a time for the full factorial combination of encounter geometries (e.g., encounter angle, CPA offset) and aircraft performance (e.g., ownership and intruder ground speeds and vertical rates). The first study analyzes the relationships (e.g., timeline) between the different alerting-safety regions in the SC-228 MOPS (in order of increasing severity): 1) DAA warning alert, 2) well clear recovery (WCR) guidance, 3) DAA-Collision Avoidance (CA), and 4) TCAS RA. This study will focus primarily on encounter situations in which TCAS RA occurs prior to any of the other alerting-safety boundaries. In particular, this study will investigate whether using vertical distance or vertical distance at closest point of approach (i.e., vertical miss distance or VMD) is more appropriate for the definition of the DAA-CA region. In addition, cases where transitions between different regions skip an intermediate region will be analyzed. The second study in this presentation explores a proposal to use an altitude rate error threshold to determine if vertical maneuvers are acceptable for DAA WCR guidance against non-cooperative intruders. This study incorporates the radar from the Honeywell sensor model and examines a series of pairwise encounters between a non-cooperative intruder and a UAS ownship, with different combinations of intruder states and ownship performance levels. The study uses SAA Control as a simulation platform and pilot model, and Omnibands to provide DWC recovery guidance. Two simulation sets, one that allows vertical DWC recovery guidance and one that does not, are compared to determine if encounters with altitude rate errors above 250 feet-per-minute are more likely to have more severe losses of well clear, as determined by the Loss of Well-Clear Severity metric.

NASA's program on icing research and technology

NASA Technical Reports Server (NTRS)

Reinmann, John J.; Shaw, Robert J.; Ranaudo, Richard J.

1989-01-01

NASA's program in aircraft icing research and technology is reviewed. The program relies heavily on computer codes and modern applied physics technology in seeking icing solutions on a finer scale than those offered in earlier programs. Three major goals of this program are to offer new approaches to ice protection, to improve our ability to model the response of an aircraft to an icing encounter, and to provide improved techniques and facilities for ground and flight testing. This paper reviews the following program elements: (1) new approaches to ice protection; (2) numerical codes for deicer analysis; (3) measurement and prediction of ice accretion and its effect on aircraft and aircraft components; (4) special wind tunnel test techniques for rotorcraft icing; (5) improvements of icing wind tunnels and research aircraft; (6) ground de-icing fluids used in winter operation; (7) fundamental studies in icing; and (8) droplet sizing instruments for icing clouds.

On the shock response of pisum sativum and lepidium sativum

NASA Astrophysics Data System (ADS)

Leighs, James Allen; Hazell, Paul; Appleby-Thomas, Gareth James

2012-03-01

The high strain-rate response of biological and organic structures is of interest to numerous fields ranging from the food industry to astrobiology. Consequently, knowledge of the damage mechanisms within, and the viability of shocked organic material are of significant importance. In this study, a single-stage gasgun has been employed to subject samples of Pisum sativum (common pea) and Lepidium sativum (curled cress) to planar shock loading. Impact pressures of up to ~11.5 GPa and ~0.5 GPa for pea and cress seed samples respectively have been reached. The development of the experimental approach is discussed and presented alongside results from modelled gauge traces showing the sample loading history. Viability of the shock-loaded pea and cress seeds was investigated via attempts at germination, which were unsuccessful with pea seeds but successful in all tests performed on cress seeds. This work suggests that organic structures could survive shockwaves that may be encountered during asteroid collisions.

Unusual dominance by desert pupfish (Cyprinodon macularius) in experimental ponds within the Salton Sea Basin

USGS Publications Warehouse

Saiki, Michael K.; Martin, Barbara A.; Anderson, Thomas W.

2011-01-01

In October 2006, months after shallow experimental ponds in the Salton Sea Basin were filled with water from the Alamo River and Salton Sea, fish were observed in several ponds, although inlets had been screened to exclude fish. During October 2007November 2009, nine surveys were conducted using baited minnow traps to document species and relative abundance of fish. Surveys yielded 3,620 fish representing five species. Desert pupfish (Cyprinodon macularius), the only native species encountered, was the most numerous and comprised >93% of the catch. Nonnative species included western mosquitofish (Gambusia affinis, 4.1%), sailfin molly (Poecilia latipinna, 2.8%), and tilapia (a mixture of hybrid Mozambique tilapia Oreochromis mossambicus ?? O. urolepis and redbelly tilapia Tilapia zillii, <0.1%). Dominance by desert pupfish, which persisted over our 2 years of study, was unusual because surveys conducted in nearby agricultural drains yielded relatively few desert pupfish.

Hypermutation by intersegmental transfer of APOBEC3G cytidine deaminase.

PubMed

Nowarski, Roni; Britan-Rosich, Elena; Shiloach, Tamar; Kotler, Moshe

2008-10-01

Deamination of cytidine residues in single-stranded DNA (ssDNA) is an important mechanism by which apolipoprotein B mRNA-editing, catalytic polypeptide-like (APOBEC) enzymes restrict endogenous and exogenous viruses. The dynamic process underlying APOBEC-induced hypermutation is not fully understood. Here we show that enzymatically active APOBEC3G can be detected in wild-type Vif(+) HIV-1 virions, albeit at low levels. In vitro studies showed that single enzyme-DNA encounters result in distributive deamination of adjacent cytidines. Nonlinear translocation of APOBEC3G, however, directed scattered deamination of numerous targets along the DNA. Increased ssDNA concentrations abolished enzyme processivity in the case of short, but not long, DNA substrates, emphasizing the key role of rapid intersegmental transfer in targeting the deaminase. Our data support a model by which APOBEC3G intersegmental transfer via monomeric binding to two ssDNA segments results in dispersed hypermutation of viral genomes.

From Lemongrass to Ivermectin: Ethnomedical Management of Chagas Disease in Tropical Bolivia.

PubMed

Forsyth, Colin

2018-04-01

Chagas disease is a neglected tropical disease; the only viable drugs are outdated and produce frequent side effects, and the overwhelming majority of cases are undiagnosed and untreated. Globally, people encounter numerous impediments to accessing biomedical treatment for Chagas disease. However, little is known about how people with Chagas disease manage their health outside the biomedical system. In this article, I discuss knowledge of ethnomedical treatments among marginalized patients in an endemic area of Bolivia. I interviewed 68 patients, 63 (93 percent) of whom had positive diagnoses for Chagas disease. Participants free listed 66 ethnomedical remedies either for Chagas disease (n = 39) or its cardiac symptoms. Participants stressed the accessibility of ethnomedical remedies in contrast to the multiple barriers to accessing biomedical treatment. Far from eroding in the face of globalization and sociopolitical marginalization, ethnomedical knowledge in the study area is dynamic and flexible, communicated through various channels.

The Subsurface Flow and Transport Laboratory: A New Department of Energy User's Facility for Intermediate-Scale Experimentation

NASA Astrophysics Data System (ADS)

Wietsma, T. W.; Oostrom, M.; Foster, N. S.

2003-12-01

Intermediate-scale experiments (ISEs) for flow and transport are a valuable tool for simulating subsurface features and conditions encountered in the field at government and private sites. ISEs offer the ability to study, under controlled laboratory conditions, complicated processes characteristic of mixed wastes and heterogeneous subsurface environments, in multiple dimensions and at different scales. ISEs may, therefore, result in major cost savings if employed prior to field studies. A distinct advantage of ISEs is that researchers can design physical and/or chemical heterogeneities in the porous media matrix that better approximate natural field conditions and therefore address research questions that contain the additional complexity of processes often encountered in the natural environment. A new Subsurface Flow and Transport Laboratory (SFTL) has been developed for ISE users in the Environmental Spectroscopy & Biogeochemistry Facility in the Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL). The SFTL offers a variety of columns and flow cells, a new state-of-the-art dual-energy gamma system, a fully automated saturation-pressure apparatus, and analytical equipment for sample processing. The new facility, including qualified staff, is available for scientists interested in collaboration on conducting high-quality flow and transport experiments, including contaminant remediation. Close linkages exist between the SFTL and numerical modelers to aid in experimental design and interpretation. This presentation will discuss the facility and outline the procedures required to submit a proposal to use this unique facility for research purposes. The W. R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility, is sponsored by the U.S. Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

A Preliminary Study of the Response of Single Rotor Helicopters to Vortex Encounters

DOT National Transportation Integrated Search

1985-04-01

This report examines some aspects of the uncontrolled dynamic response of a single rotor helicopter to an encounter with the wing tip vortex of a large transport aircraft. The primary emphasis in the study was to investigate the importance of various...

Constrained Self-adaptive Solutions Procedures for Structure Subject to High Temperature Elastic-plastic Creep Effects

NASA Technical Reports Server (NTRS)

Padovan, J.; Tovichakchaikul, S.

1983-01-01

This paper will develop a new solution strategy which can handle elastic-plastic-creep problems in an inherently stable manner. This is achieved by introducing a new constrained time stepping algorithm which will enable the solution of creep initiated pre/postbuckling behavior where indefinite tangent stiffnesses are encountered. Due to the generality of the scheme, both monotone and cyclic loading histories can be handled. The presentation will give a thorough overview of current solution schemes and their short comings, the development of constrained time stepping algorithms as well as illustrate the results of several numerical experiments which benchmark the new procedure.

Domestic Violence Encountered among Kurdish Women

ERIC Educational Resources Information Center

Ali, Sirwan Kamil

2015-01-01

Background and objective; There is growing recognition that violence against women has a large public health impact, in addition to being a gross violation of women's human rights. The study's aims were: To show the types of domestic abuse encountered by Kurdish women, and study the relationship between them. Methods; The study conducted in the…

A cluster expansion model for predicting activation barrier of atomic processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rehman, Tafizur; Jaipal, M.; Chatterjee, Abhijit, E-mail: achatter@iitk.ac.in

2013-06-15

We introduce a procedure based on cluster expansion models for predicting the activation barrier of atomic processes encountered while studying the dynamics of a material system using the kinetic Monte Carlo (KMC) method. Starting with an interatomic potential description, a mathematical derivation is presented to show that the local environment dependence of the activation barrier can be captured using cluster interaction models. Next, we develop a systematic procedure for training the cluster interaction model on-the-fly, which involves: (i) obtaining activation barriers for handful local environments using nudged elastic band (NEB) calculations, (ii) identifying the local environment by analyzing the NEBmore » results, and (iii) estimating the cluster interaction model parameters from the activation barrier data. Once a cluster expansion model has been trained, it is used to predict activation barriers without requiring any additional NEB calculations. Numerical studies are performed to validate the cluster expansion model by studying hop processes in Ag/Ag(100). We show that the use of cluster expansion model with KMC enables efficient generation of an accurate process rate catalog.« less

Disrespect, harassment, and abuse

PubMed Central

Miedema, Baukje; Easley, Julie; Fortin, Pierrette; Hamilton, Ryan; Tatemichi, Sue

2009-01-01

ABSTRACT OBJECTIVE To examine harassment and abusive encounters between family physicians and their patients or colleagues in the workplace. DESIGN Qualitative case study using semistructured interviews. SETTING Province of New Brunswick. PARTICIPANTS Forty-eight family physicians from across the province. METHODS A collective case-study approach was developed, with 24 cases of 2 individuals per case. Cases were selected based on sex, location (urban or rural), language (French or English), and number of years since medical school graduation (< 10 years, 10 to 20 years, or > 20 years). Physicians were interviewed in either French or English. Participants were recruited using the College of Physicians and Surgeons of New Brunswick’s physician directory. Based on the rates of response and participation, some cases were overrepresented, while others were not completed. All interviews were audiotaped, transcribed verbatim, and analyzed thematically using a categorical aggregation approach. A coding scheme for the thematic analysis was developed by the research team before the interviews were transcribed. MAIN FINDINGS Although the original intent of this study was to examine the work environment of family physicians in light of the increasing number of women entering the profession, harassment and abusive encounters in the workplace emerged as a main theme. These encounters ranged from minor to severe. Minor abusive encounters included disrespectful behaviour and verbal threats by patients, their families, and occasionally colleagues. More severe forms of harassment involved physical threats, physical encounters, and stalking. Demanding patients, such as heavy drug users, were often seen as threatening. Location of practice, years in practice, and sex of the physician seemed to affect abusive encounters—young, female, rural physicians appeared to experience such encounters most often. CONCLUSION Abusive encounters in the workplace are concerning. It is essential to address these issues of workplace harassment and abuse in order to protect physician safety and avoid workplace dissatisfaction. Abusive encounters might push family physicians to leave clinical practice prematurely or refuse to work in higher-risk environments, such as emergency departments or rural areas. PMID:19282539

Microbiomes Have the Power to Help or Hinder Your Health

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jansson, Janet

They are everywhere: countless microorganisms that inhabit our world—even in your skin, mouth, gut and other parts of your body. Called microbiomes, these communities play a fundamental role in our ecosystem and our bodies, influencing everything from climate to human health. And scientists at PNNL are studying microbiomes to better understand how they influence our daily lives. Scientist Janet Jansson studies complex microbiomes in soil and the human intestine to understand changes in the composition or function of microbes. In the soil, these microbes are associated with carbon cycling and degrading pollutants, as well as plant health. In the intestine,more » they are responsible for digestion of our food and protection from pathogens. When they go awry, they can be associated with numerous inflammatory bowel diseases, such as Crohn’s. Understanding the factors underlying these microbiome changes will ultimately help researchers develop solutions to problems encountered within our world and our bodies.« less

On the role of conflict and control in social cognition: event-related brain potential investigations.

PubMed

Bartholow, Bruce D

2010-03-01

Numerous social-cognitive models posit that social behavior largely is driven by links between constructs in long-term memory that automatically become activated when relevant stimuli are encountered. Various response biases have been understood in terms of the influence of such "implicit" processes on behavior. This article reviews event-related potential (ERP) studies investigating the role played by cognitive control and conflict resolution processes in social-cognitive phenomena typically deemed automatic. Neurocognitive responses associated with response activation and conflict often are sensitive to the same stimulus manipulations that produce differential behavioral responses on social-cognitive tasks and that often are attributed to the role of automatic associations. Findings are discussed in the context of an overarching social cognitive neuroscience model in which physiological data are used to constrain social-cognitive theories.

Introduction to Methods of Approximation in Physics and Astronomy

NASA Astrophysics Data System (ADS)

van Putten, Maurice H. P. M.

2017-04-01

Modern astronomy reveals an evolving Universe rife with transient sources, mostly discovered - few predicted - in multi-wavelength observations. Our window of observations now includes electromagnetic radiation, gravitational waves and neutrinos. For the practicing astronomer, these are highly interdisciplinary developments that pose a novel challenge to be well-versed in astroparticle physics and data analysis. In realizing the full discovery potential of these multimessenger approaches, the latter increasingly involves high-performance supercomputing. These lecture notes developed out of lectures on mathematical-physics in astronomy to advanced undergraduate and beginning graduate students. They are organised to be largely self-contained, starting from basic concepts and techniques in the formulation of problems and methods of approximation commonly used in computation and numerical analysis. This includes root finding, integration, signal detection algorithms involving the Fourier transform and examples of numerical integration of ordinary differential equations and some illustrative aspects of modern computational implementation. In the applications, considerable emphasis is put on fluid dynamical problems associated with accretion flows, as these are responsible for a wealth of high energy emission phenomena in astronomy. The topics chosen are largely aimed at phenomenological approaches, to capture main features of interest by effective methods of approximation at a desired level of accuracy and resolution. Formulated in terms of a system of algebraic, ordinary or partial differential equations, this may be pursued by perturbation theory through expansions in a small parameter or by direct numerical computation. Successful application of these methods requires a robust understanding of asymptotic behavior, errors and convergence. In some cases, the number of degrees of freedom may be reduced, e.g., for the purpose of (numerical) continuation or to identify secular behavior. For instance, secular evolution of orbital parameters may derive from averaging over essentially periodic behavior on relatively short, orbital periods. When the original number of degrees of freedom is large, averaging over dynamical time scales may lead to a formulation in terms of a system in approximately thermodynamic equilibrium subject to evolution on a secular time scale by a regular or singular perturbation. In modern astrophysics and cosmology, gravitation is being probed across an increasingly broad range of scales and more accurately so than ever before. These observations probe weak gravitational interactions below what is encountered in our solar system by many orders of magnitude. These observations hereby probe (curved) spacetime at low energy scales that may reveal novel properties hitherto unanticipated in the classical vacuum of Newtonian mechanics and Minkowski spacetime. Dark energy and dark matter encountered on the scales of galaxies and beyond, therefore, may be, in part, revealing our ignorance of the vacuum at the lowest energy scales encountered in cosmology. In this context, our application of Newtonian mechanics to globular clusters, galaxies and cosmology is an approximation assuming a classical vacuum, ignoring the potential for hidden low energy scales emerging on cosmological scales. Given our ignorance of the latter, this poses a challenge in the potential for unknown systematic deviations. If of quantum mechanical origin, such deviations are often referred to as anomalies. While they are small in traditional, macroscopic Newtonian experiments in the laboratory, they same is not a given in the limit of arbitrarily weak gravitational interactions. We hope this selection of introductory material is useful and kindles the reader's interest to become a creative member of modern astrophysics and cosmology.

Internet advertisements for public sexual encounters among men who have sex with men: are safe behaviors communicated?

PubMed

Downing, Martin J

2011-09-01

Public and commercial sex venues typically provide easy access to sexual encounters that are often anonymous and, therefore, may facilitate HIV/STD transmission among those men who attend. Recently, researchers have suggested that men who have sex with men may be using the Internet to search for sexual encounters to occur within sex venues. The current study explored the extent to which men who advertise for public or commercial sexual encounters initially communicate to potential partners their safe-sex intentions. Advertisements for sexual encounters (n = 99) were collected from a publicly accessible website and examined for content related to venue type, sexual behavior, and indications of sexual safety or risk. Word frequencies were calculated to provide a closer investigation of how individuals negotiate safe sex within these communications. The findings revealed that approximately half of the men who advertised for sex in a public or commercial sex venue failed to communicate to potential partners in their initial advertisement a desire to be safe during sexual encounters involving oral and anal practices. Additionally, a small percentage of men advertised specifically for risky encounters (e.g., barebacking). Together, these findings suggest that men do use the Internet to coordinate public sexual encounters, some of which may be unprotected from HIV/STD transmission. Future research should address the process of condom negotiation among men who initially meet their male sex partners on the Internet for subsequent encounters in sex venues.

Structure of Cometary Dust Particles

NASA Astrophysics Data System (ADS)

Levasseur-Regourd, A. C.; Hadamcik, E.; Lasue, J.

2004-11-01

The recent encounter of Stardust with comet 81P/Wild 2 has provided highly spatially resolved data about dust particles in the coma. They show intense swarms and bursts of particles, suggest the existence of fragmenting low-density particles formed of higher density sub-micrometer components [1], and definitely confirm previous results (inferred from Giotto encounter with comet Grigg-Skjellerup [2] and remote light scattering observations [3]). The light scattering properties (mostly polarization, which does not depend upon disputable normalizations) of dust in cometary comae will be summarized, with emphasis on the spatial changes and on the wavelength and phase angle dependence. Experimental and numerical simulations are needed to translate these observed light scattering properties in terms of physical properties of the dust particles (e.g. size, morphology, albedo, porosity). New experimental simulations (with fluffy mixtures of sub-micron sized silica and carbon grains) and new numerical simulations (with fractal aggregates of homogeneous or core-mantled silicate and organic grains) will be presented. The results are in favor of highly porous particles built up (by ballistic-cluster-cluster agglomeration) from grains of interstellar origin. The perspectives offered by laboratory simulations with aggregates built under conditions representative of the early solar system on board the International Space Station will be presented, together with the perspectives offered by future experiments on board the Rosetta cometary probe. Supports from CNES and ESA are acknowledged [1] Tuzzolino et al., Science, 304, 1776, 2004, [2] N. McBride et al., Mon. Not. R. Astron. Soc., 289, p. 535-553, 1997, [3] Levasseur-Regourd and Hadamcik, J. Quant. Spectros. Radiat. Transfer, 79-80, 903-910, 2003.

Difficult Knowledge and Social Studies (Teacher) Education

ERIC Educational Resources Information Center

Garrett, H. James

2010-01-01

Social studies education is a field in which those involved--teachers and students--encounter what can be called "difficult knowledge". Difficult knowledge is a theoretical construct suggesting that when an individual encounters representations of social and historical trauma in a learning situation there exists a host of emotional and pedagogical…

Combined analytical and numerical approaches in Dynamic Stability analyses of engineering systems

NASA Astrophysics Data System (ADS)

Náprstek, Jiří

2015-03-01

Dynamic Stability is a widely studied area that has attracted many researchers from various disciplines. Although Dynamic Stability is usually associated with mechanics, theoretical physics or other natural and technical disciplines, it is also relevant to social, economic, and philosophical areas of our lives. Therefore, it is useful to occasionally highlight the general aspects of this amazing area, to present some relevant examples and to evaluate its position among the various branches of Rational Mechanics. From this perspective, the aim of this study is to present a brief review concerning the Dynamic Stability problem, its basic definitions and principles, important phenomena, research motivations and applications in engineering. The relationships with relevant systems that are prone to stability loss (encountered in other areas such as physics, other natural sciences and engineering) are also noted. The theoretical background, which is applicable to many disciplines, is presented. In this paper, the most frequently used Dynamic Stability analysis methods are presented in relation to individual dynamic systems that are widely discussed in various engineering branches. In particular, the Lyapunov function and exponent procedures, Routh-Hurwitz, Liénard, and other theorems are outlined together with demonstrations. The possibilities for analytical and numerical procedures are mentioned together with possible feedback from experimental research and testing. The strengths and shortcomings of these approaches are evaluated together with examples of their effective complementing of each other. The systems that are widely encountered in engineering are presented in the form of mathematical models. The analyses of their Dynamic Stability and post-critical behaviour are also presented. The stability limits, bifurcation points, quasi-periodic response processes and chaotic regimes are discussed. The limit cycle existence and stability are examined together with their separating roles as attractors and repulsers. Two levels of stability loss (recovery of the system is possible or final collapse is inevitable) as can be observed in softening systems are noted. Time-limited excitation and relevant transition effects (e.g., seismic excitation) are also discussed, together with the evaluation of possible system reliability improvement. The Dynamic Stability investigation of two degrees-of-freedom aero-elastic systems in a linear formulation using several approaches is briefly highlighted. Further systems modelling problems that arise in transport engineering are also outlined. A few hints for applications are given. Some open problems and possible future research strategies are outlined.

A transcultural study of Jordanian nursing students' care encounters within the context of clinical education.

PubMed

Nahas, V

2000-06-01

Clinical education is an integral part of nursing education. Clinical teachers are the vital link in this teaching-learning process. The quality and quantity of student-teacher interactions in the clinical area can either facilitate or hinder students' learning. This paper presents a part of a larger study that discovered, described, explained and compared Australian and Jordanian nursing students' caring and non-caring encounters with their clinical teachers within the context of clinical education. The study was guided by Leininger's theory of culture care universality and diversity and Leininger's ethnonursing research method was utilised. The informants consisted of 12 key informants and 35 general informants. Three major themes emerged from the analysis of the data: (1) clinical teacher's caring behaviours; (2) student-teacher caring encounters; and (3) caring encounter consequences. Under these themes, care constructs emerged which gave light to the Jordanian nursing students' care meanings, expressions and values within their cultural environment, social structures and world view. The overall findings revealed that Jordanian nursing students found their clinical experiences as beneficial when their encounters with the clinical teacher were conducted through mothering, translating, sustaining, negotiating and transforming processes.

Environmental cleanup: The challenge at the Hanford Site, Washington, USA

NASA Astrophysics Data System (ADS)

Gray, Robert H.; Becker, C. Dale

1993-07-01

Numerous challenges face those involved with developing a coordinated and consistent approach to cleaning up the US Department of Energy’s (DOE) Hanford Site in southeastern Washington. These challenges are much greater than those encountered when the site was selected and the world’s first nuclear complex was developed almost 50 years ago. This article reviews Hanford’s history, operations, waste storage/disposal activities, environmental monitoring, and today’s approach to characterize and clean up Hanford under a Federal Facility Agreement and Consent Order, signed by DOE, the Environmental Protection Agency, and the Washington Sate Department of Ecology. Although cleanup of defense-related waste at Hanford holds many positive benefits, negative features include high costs to the US taxpayer, numerous uncertainties concerning the technologies to be employed and the risks involved, and the high probability that special interest groups and activists at large will never be completely satisfied. Issues concerning future use of the site, whether to protect and preserve its natural features or open it to public exploitation, remain to be resolved.

Starvation dynamics of a greedy forager

NASA Astrophysics Data System (ADS)

Bhat, U.; Redner, S.; Bénichou, O.

2017-07-01

We investigate the dynamics of a greedy forager that moves by random walking in an environment where each site initially contains one unit of food. Upon encountering a food-containing site, the forager eats all the food there and can subsequently hop an additional S steps without food before starving to death. Upon encountering an empty site, the forager goes hungry and comes one time unit closer to starvation. We investigate the new feature of forager greed; if the forager has a choice between hopping to an empty site or to a food-containing site in its nearest neighborhood, it hops preferentially towards food. If the neighboring sites all contain food or are all empty, the forager hops equiprobably to one of these neighbors. Paradoxically, the lifetime of the forager can depend non-monotonically on greed, and the sense of the non-monotonicity is opposite in one and two dimensions. Even more unexpectedly, the forager lifetime in one dimension is substantially enhanced when the greed is negative; here the forager tends to avoid food in its local neighborhood. We also determine the average amount of food consumed at the instant when the forager starves. We present analytic, heuristic, and numerical results to elucidate these intriguing phenomena.

Plasma waves associated with the AMPTE artificial comet

NASA Technical Reports Server (NTRS)

Gurnett, D. A.; Anderson, R. R.; Haeusler, B.; Haerendel, G.; Bauer, O. H.

1985-01-01

Numerous plasma wave effects were detected by the AMPTE/IRM spacecraft during the artificial comet experiment on December 27, 1984. As the barium ion cloud produced by the explosion expanded over the spacecraft, emissions at the electron plasma frequency and ion plasma frequency provided a determination of the local electron density. The electron density in the diamagnetic cavity produced by the ion cloud reached a peak of more than 5 x 10 to the 5th per cu cm, then decayed smoothly as the cloud expanded, varying approximately as t exp-2. As the cloud began to move due to interactions with the solar wind, a region of compressed plasma was encountered on the upstream side of the diamagnetic cavity. The peak electron density in the compression region was about 1.5 x 10 to the 4th per cu cm. Later, a very intense (140 mVolt/m) broadband burst of electrostatic noise was encountered on the sunward side of the compression region. This noise has characteristics very similar to noise observed in the earth's bow shock, and is believed to be a shocklike interaction produced by an ion beam-plasma instability between the nearly stationary barium ions and the streaming solar wind protons.

Involvement in the US criminal justice system and cost implications for persons treated for schizophrenia.

PubMed

Ascher-Svanum, Haya; Nyhuis, Allen W; Faries, Douglas E; Ball, Daniel E; Kinon, Bruce J

2010-01-28

Individuals with schizophrenia may have a higher risk of encounters with the criminal justice system than the general population, but there are limited data on such encounters and their attendant costs. This study assessed the prevalence of encounters with the criminal justice system, encounter types, and the estimated cost attributable to these encounters in the one-year treatment of persons with schizophrenia. This post-hoc analysis used data from a prospective one-year cost-effectiveness study of persons treated with antipsychotics for schizophrenia and related disorders in the United States. Criminal justice system involvement was assessed using the Schizophrenia Patients Outcome Research Team (PORT) client survey and the victimization subscale of the Lehman Quality of Life Interview (QOLI). Direct cost of criminal justice system involvement was estimated using previously reported costs per type of encounter. Patients with and without involvement were compared on baseline characteristics and direct annual health care and criminal justice system-related costs. Overall, 278 (46%) of 609 participants reported at least 1 criminal justice system encounter. They were more likely to be substance users and less adherent to antipsychotics compared to participants without involvement. The 2 most prevalent types of encounters were being a victim of a crime (67%) and being on parole or probation (26%). The mean annual per-patient cost of involvement was $1,429, translating to 6% of total annual direct health care costs for those with involvement (11% when excluding crime victims). Criminal justice system involvement appears to be prevalent and costly for persons treated for schizophrenia in the United States. Findings highlight the need to better understand the interface between the mental health and the criminal justice systems and the related costs, in personal, societal, and economic terms.

Genetic structure of soil population of fungus Fusarium oxysporum Schlechtend.: Fr.: Molecular reidentification of the species and genetic differentiation of isolates using polymerase chain reaction technique with universal primers (UP-PCR)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bulat, S.A.; Mironenko, N.V.; Zholkevich, Yu.G.

1995-07-01

The genetic structure of three soil populations of fungus Fusarium oxysporum was analyzed using polymerase chain reaction with universal primers (UP-PCR). Distinct UP-PCR variants revealed by means of cross-dot hybridization of amplified DNA and restriction analysis of nuclear ribosomal DNA represent subspecies or sibling species of F. oxysporum. The remaining isolates of F. oxysporum showed moderate UP-PCR polymorphism characterized by numerous types, whose relatedness was analyzed by computer treatment of the UP-PCR patterns. The genetic distance trees based on the UP-PCR patterns, which were obtained with different universal primers, demonstrated similar topology. This suggests that evolutionarily important genome rearrangements correlativelymore » occur within the entire genome. Isolates representing different UP-PCR polymorphisms were encountered in all populations, being distributed asymmetrically in two of these. In general, soil populations of F. oxysporum were represented by numerous genetically isolated groups with a similar genome structure. The genetic heterogeneity of the isolates within these groups is likely to be caused by the parasexual process. The usefulness of the UP-PCR technique for population studies of F. oxysporum was demonstrated. 39 refs., 7 figs., 2 tabs.« less

Case study of a low-reflectivity pulsating microburst: Numerical simulation of the Denver, 8 July 1989, storm

NASA Technical Reports Server (NTRS)

Proctor, Fred H.

1994-01-01

On 8 July 1989, a very strong microburst was detected by the Low-Level Windshear Alert system (LLWAS), within the approach corridor just north of Denver Stapleton Airport. The microburst was encountered by a Boeing 737-200 in a 'go-around' configuration which was reported to have lost considerable air speed and altitude during penetration. Data from LLWAS revealed a pulsating microburst with an estimated peak velocity change of 48 m/s. Wilson et al. reported that the microburst was accompanied by no apparent visible clues such as rain or virga, although blowing dust was present. Weather service hourly reports indicated virga in all quadrants near the time of the event. A National Center for Atmospheric Research (NCAR) research Doppler radar was operating; but according to Wilson et al., meaningful velocity could not be measured within the microburst due to low radar-reflectivity factor and poor siting for windshear detection at Stapleton. This paper presents results from the three-dimensional numerical simulation of this event, using the Terminal Area Simulation System (TASS) model. The TASS model is a three-dimensional nonhydrostatic cloud model that includes parameterizations for both liquid and ice phase microphysics, and has been used in investigations of both wet and dry microburst case studies. The focus of this paper is the pulsating characteristic and the very-low radar reflectivity of this event. Most of the surface outflow contained no precipitation. Such an event may be difficult to detect by radar.

Response problems in a vacation panel study

Treesearch

Christine A. Vogt; Susan I. Stewart

2001-01-01

This paper investigates response problems encountered in a panel study of travel behavior. Though the overall response rate to the three-wave panel study was acceptable (over 60%), three types of response problems were encountered: refusal, non-response, and attrition. In a follow-up phone survey, a sample of individuals from each problem response group was questioned...

Improving inferences from fisheries capture-recapture studies through remote detection of PIT tags

USGS Publications Warehouse

Hewitt, David A.; Janney, Eric C.; Hayes, Brian S.; Shively, Rip S.

2010-01-01

Models for capture-recapture data are commonly used in analyses of the dynamics of fish and wildlife populations, especially for estimating vital parameters such as survival. Capture-recapture methods provide more reliable inferences than other methods commonly used in fisheries studies. However, for rare or elusive fish species, parameter estimation is often hampered by small probabilities of re-encountering tagged fish when encounters are obtained through traditional sampling methods. We present a case study that demonstrates how remote antennas for passive integrated transponder (PIT) tags can increase encounter probabilities and the precision of survival estimates from capture-recapture models. Between 1999 and 2007, trammel nets were used to capture and tag over 8,400 endangered adult Lost River suckers (Deltistes luxatus) during the spawning season in Upper Klamath Lake, Oregon. Despite intensive sampling at relatively discrete spawning areas, encounter probabilities from Cormack-Jolly-Seber models were consistently low (< 0.2) and the precision of apparent annual survival estimates was poor. Beginning in 2005, remote PIT tag antennas were deployed at known spawning locations to increase the probability of re-encountering tagged fish. We compare results based only on physical recaptures with results based on both physical recaptures and remote detections to demonstrate the substantial improvement in estimates of encounter probabilities (approaching 100%) and apparent annual survival provided by the remote detections. The richer encounter histories provided robust inferences about the dynamics of annual survival and have made it possible to explore more realistic models and hypotheses about factors affecting the conservation and recovery of this endangered species. Recent advances in technology related to PIT tags have paved the way for creative implementation of large-scale tagging studies in systems where they were previously considered impracticable.

Habitability in Different Milky Way Stellar Environments: A Stellar Interaction Dynamical Approach

PubMed Central

Pichardo, Bárbara; Lake, George; Segura, Antígona

2013-01-01

Abstract Every Galactic environment is characterized by a stellar density and a velocity dispersion. With this information from literature, we simulated flyby encounters for several Galactic regions, numerically calculating stellar trajectories as well as orbits for particles in disks; our aim was to understand the effect of typical stellar flybys on planetary (debris) disks in the Milky Way Galaxy. For the solar neighborhood, we examined nearby stars with known distance, proper motions, and radial velocities. We found occurrence of a disturbing impact to the solar planetary disk within the next 8 Myr to be highly unlikely; perturbations to the Oort cloud seem unlikely as well. Current knowledge of the full phase space of stars in the solar neighborhood, however, is rather poor; thus we cannot rule out the existence of a star that is more likely to approach than those for which we have complete kinematic information. We studied the effect of stellar encounters on planetary orbits within the habitable zones of stars in more crowded stellar environments, such as stellar clusters. We found that in open clusters habitable zones are not readily disrupted; this is true if they evaporate in less than 108 yr. For older clusters the results may not be the same. We specifically studied the case of Messier 67, one of the oldest open clusters known, and show the effect of this environment on debris disks. We also considered the conditions in globular clusters, the Galactic nucleus, and the Galactic bulge-bar. We calculated the probability of whether Oort clouds exist in these Galactic environments. Key Words: Stellar interactions—Galactic habitable zone—Oort cloud. Astrobiology 13, 491–509. PMID:23659647

Confidentiality in participatory research: Challenges from one study.

PubMed

Petrova, Elmira; Dewing, Jan; Camilleri, Michelle

2016-06-01

This article presents key ethical challenges that were encountered when conducting a participatory qualitative research project with a very specific, small group of nurses, in this case with practice development nurses in Malta. With the small number of nurses employed in practice development roles in Malta, there are numerous difficulties of maintaining confidentiality. Poorly constructed interventions by the researcher could have resulted in detrimental effects to research participants and the overall trustworthiness of the research. Generally, ethical guidelines for research exist to reinforce validity of research; however, there is not an established consensus on how these strategies can be utilised in some types of qualitative field work. The researcher used an exploratory case study methodology. The sample consisted of 10 participants who were interviewed twice using face-to-face interviews, over a period of 2 months. The study was ethically reviewed by the University Research Ethics Committee and the Faculty Research Ethics Committee, University of Malta. The participants referred to in this article have been given adequate information about the study and their consent has been obtained. Numerous strategies for ensuring confidentiality during recruitment of the participants, during data collection, during transcription and data analysis and during dissemination of research results assisted the researcher in responding to potential and actual ethical issues. This article emphasises the main strategies that can be used to respond to ethical challenges when researching with a small easily identifiable group. The learning discussed here may be relevant to or even transferable to other similar research studies or research contexts. These methods fostered a greater credibility throughout the research process and predisposed the participants to greater trust, and thus, they disclosed their experiences and speak more freely, thus enhancing the quality of the study. © The Author(s) 2014.

Descriptive study of older adults encountered by crisis intervention team (CIT) law enforcement officers.

PubMed

Tyuse, Sabrina W; Cooper-Sadlo, Shannon; Underwood, Sarah E

2017-01-01

Increasingly, older adults who experience a mental health crisis come to the attention of crisis intervention team (CIT) law enforcement officers. These encounters are due largely to a lack of local mental health care resources. With few options available, individuals call 911 for assistance when an older adult exhibits alarming behavior. This article provides a profile of older adults encountered by CIT officers, identifies the reasons for the 911 call for assistance, and finds what predictors are associated with outcomes of those encounters. We found that these older adults were mostly female, Caucasian, diagnosed with depression, and attempting or threatening suicide.

A Study of the Barriers K-12 Teachers Encounter when Integrating Technology into the Curriculum

ERIC Educational Resources Information Center

Brown-Joseph, Theresa Denise

2010-01-01

This study utilized an outlined plan for a qualitative case study to explore the perceived barriers that teachers in K-12 grades encounter when integrating technology into the curriculum. A purposive sample of 20 teachers from both elementary and high schools provided information during structured interviews about their experiences with…

A review of the LATEX project: mesoscale to submesoscale processes in a coastal environment

NASA Astrophysics Data System (ADS)

Petrenko, Anne A.; Doglioli, Andrea M.; Nencioli, Francesco; Kersalé, Marion; Hu, Ziyuan; d'Ovidio, Francesco

2017-04-01

The main objective of the LAgrangian Transport EXperiment (LATEX) project was to study the influence of coastal mesoscale and submesoscale physical processes on circulation dynamics, cross-shelf exchanges, and biogeochemistry in the western continental shelf of the Gulf of Lion, Northwestern Mediterranean Sea. LATEX was a five-year multidisciplinary project based on the combined analysis of numerical model simulations and multi-platform field experiments. The model component included a ten-year realistic 3D numerical simulation, with a 1 km horizontal resolution over the gulf, nested in a coarser 3 km resolution model. The in situ component involved four cruises, including a large-scale multidisciplinary campaign with two research vessels in 2010. This review concentrates on the physics results of LATEX, addressing three main subjects: (1) the investigation of the mesoscale to submesoscale processes. The eddies are elliptic, baroclinic, and anticyclonic; the strong thermal and saline front is density compensated. Their generation processes are studied; (2) the development of sampling strategies for their direct observations. LATEX has implemented an adaptive strategy Lagrangian tool, with a reference software available on the web, to perform offshore campaigns in a Lagrangian framework; (3) the quantification of horizontal mixing and cross-shelf exchanges. Lateral diffusivity coefficients, calculated in various ways including a novel technique, are in the range classically encountered for their associated scales. Cross-shelf fluxes have been calculated, after retrieving the near-inertial oscillation contribution. Further perspectives are discussed, especially for the ongoing challenge of studying submesoscale features remotely and from in situ data.

Between normality and deviance: the breakdown of batterers' identity following police intervention.

PubMed

Buchbinder, Eli; Eisikovits, Zvi

2004-04-01

With the transformation of intimate violence from private trouble to social problem, police intervention in domestic violence cases became more prevalent. Research has focused mainly on battered women's perception of police intervention, their evaluations, and their level of satisfaction with the intervention. However, there is little research examining the perpetrators' subjective perceptions of such interventions. The purpose of this study is to describe and analyze battering men's perceptions of police intervention. The study is based on semistructured, in-depth interviews with 20 batterers who had repeated encounters with police. Findings show a continuum of self-management, ranging from attempts to preserve a normative identity in the first encounter to struggling against criminalization in the second encounter and adopting a victim identity in the third encounter. The findings are discussed in the context of gender identity and power relations.

Test Driven Development of a Parameterized Ice Sheet Component

NASA Astrophysics Data System (ADS)

Clune, T.

2011-12-01

Test driven development (TDD) is a software development methodology that offers many advantages over traditional approaches including reduced development and maintenance costs, improved reliability, and superior design quality. Although TDD is widely accepted in many software communities, the suitability to scientific software is largely undemonstrated and warrants a degree of skepticism. Indeed, numerical algorithms pose several challenges to unit testing in general, and TDD in particular. Among these challenges are the need to have simple, non-redundant closed-form expressions to compare against the results obtained from the implementation as well as realistic error estimates. The necessity for serial and parallel performance raises additional concerns for many scientific applicaitons. In previous work I demonstrated that TDD performed well for the development of a relatively simple numerical model that simulates the growth of snowflakes, but the results were anecdotal and of limited relevance to far more complex software components typical of climate models. This investigation has now been extended by successfully applying TDD to the implementation of a substantial portion of a new parameterized ice sheet component within a full climate model. After a brief introduction to TDD, I will present techniques that address some of the obstacles encountered with numerical algorithms. I will conclude with some quantitative and qualitative comparisons against climate components developed in a more traditional manner.

An Investigation into Solution Verification for CFD-DEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fullmer, William D.; Musser, Jordan

This report presents the study of the convergence behavior of the computational fluid dynamicsdiscrete element method (CFD-DEM) method, specifically National Energy Technology Laboratory’s (NETL) open source MFiX code (MFiX-DEM) with a diffusion based particle-tocontinuum filtering scheme. In particular, this study focused on determining if the numerical method had a solution in the high-resolution limit where the grid size is smaller than the particle size. To address this uncertainty, fixed particle beds of two primary configurations were studied: i) fictitious beds where the particles are seeded with a random particle generator, and ii) instantaneous snapshots from a transient simulation of anmore » experimentally relevant problem. Both problems considered a uniform inlet boundary and a pressure outflow. The CFD grid was refined from a few particle diameters down to 1/6 th of a particle diameter. The pressure drop between two vertical elevations, averaged across the bed cross-section was considered as the system response quantity of interest. A least-squares regression method was used to extrapolate the grid-dependent results to an approximate “grid-free” solution in the limit of infinite resolution. The results show that the diffusion based scheme does yield a converging solution. However, the convergence is more complicated than encountered in simpler, single-phase flow problems showing strong oscillations and, at times, oscillations superimposed on top of globally non-monotonic behavior. The challenging convergence behavior highlights the importance of using at least four grid resolutions in solution verification problems so that (over-determined) regression-based extrapolation methods may be applied to approximate the grid-free solution. The grid-free solution is very important in solution verification and VVUQ exercise in general as the difference between it and the reference solution largely determines the numerical uncertainty. By testing different randomized particle configurations of the same general problem (for the fictitious case) or different instances of freezing a transient simulation, the numerical uncertainties appeared to be on the same order of magnitude as ensemble or time averaging uncertainties. By testing different drag laws, almost all cases studied show that model form uncertainty in this one, very important closure relation was larger than the numerical uncertainty, at least with a reasonable CFD grid, roughly five particle diameters. In this study, the diffusion width (filtering length scale) was mostly set at a constant of six particle diameters. A few exploratory tests were performed to show that similar convergence behavior was observed for diffusion widths greater than approximately two particle diameters. However, this subject was not investigated in great detail because determining an appropriate filter size is really a validation question which must be determined by comparison to experimental or highly accurate numerical data. Future studies are being considered targeting solution verification of transient simulations as well as validation of the filter size with direct numerical simulation data.« less

Dynamic Transitions and Baroclinic Instability for 3D Continuously Stratified Boussinesq Flows

NASA Astrophysics Data System (ADS)

Şengül, Taylan; Wang, Shouhong

2018-02-01

The main objective of this article is to study the nonlinear stability and dynamic transitions of the basic (zonal) shear flows for the three-dimensional continuously stratified rotating Boussinesq model. The model equations are fundamental equations in geophysical fluid dynamics, and dynamics associated with their basic zonal shear flows play a crucial role in understanding many important geophysical fluid dynamical processes, such as the meridional overturning oceanic circulation and the geophysical baroclinic instability. In this paper, first we derive a threshold for the energy stability of the basic shear flow, and obtain a criterion for local nonlinear stability in terms of the critical horizontal wavenumbers and the system parameters such as the Froude number, the Rossby number, the Prandtl number and the strength of the shear flow. Next, we demonstrate that the system always undergoes a dynamic transition from the basic shear flow to either a spatiotemporal oscillatory pattern or circle of steady states, as the shear strength of the basic flow crosses a critical threshold. Also, we show that the dynamic transition can be either continuous or catastrophic, and is dictated by the sign of a transition number, fully characterizing the nonlinear interactions of different modes. Both the critical shear strength and the transition number are functions of the system parameters. A systematic numerical method is carried out to explore transition in different flow parameter regimes. In particular, our numerical investigations show the existence of a hypersurface which separates the parameter space into regions where the basic shear flow is stable and unstable. Numerical investigations also yield that the selection of horizontal wave indices is determined only by the aspect ratio of the box. We find that the system admits only critical eigenmodes with roll patterns aligned with the x-axis. Furthermore, numerically we encountered continuous transitions to multiple steady states, as well as continuous and catastrophic transitions to spatiotemporal oscillations.

Generative Learning: Adults Learning within Ambiguity

ERIC Educational Resources Information Center

Nicolaides, Aliki

2015-01-01

This study explored the extent to which ambiguity can serve as a catalyst for adult learning. The purpose of this study is to understand learning that is generated when encountering ambiguity agitated by the complexity of liquid modernity. "Ambiguity," in this study, describes an encounter with an appearance of reality that is at first…

Emergency Department Frequent Users for Acute Alcohol Intoxication.

PubMed

Klein, Lauren R; Martel, Marc L; Driver, Brian E; Reing, Mackenzie; Cole, Jon B

2018-03-01

A subset of frequent users of emergency services are those who use the emergency department (ED) for acute alcohol intoxication. This population and their ED encounters have not been previously described. This was a retrospective, observational, cohort study of patients presenting to the ED for acute alcohol intoxication between 2012 and 2016. We collected all data from the electronic medical record. Frequent users for alcohol intoxication were defined as those with greater than 20 visits for acute intoxication without additional medical chief complaints in the previous 12 months. We used descriptive statistics to evaluate characteristics of frequent users for alcohol intoxication, as well as their ED encounters. We identified 32,121 patient encounters. Of those, 325 patients were defined as frequent users for alcohol intoxication, comprising 11,370 of the encounters during the study period. The median maximum number of encounters per person for alcohol intoxication in a one-year period was 47 encounters (range 20 to 169). Frequent users were older (47 years vs. 39 years), and more commonly male (86% vs. 71%). Frequent users for alcohol intoxication had higher rates of medical and psychiatric comorbidities including liver disease, chronic kidney disease, ischemic vascular disease, dementia, chronic obstructive pulmonary disease, history of traumatic brain injury, schizophrenia, and bipolar disorder. In this study, we identified a group of ED frequent users who use the ED for acute alcohol intoxication. This population had higher rates of medical and psychiatric comorbidities compared to non-frequent users.

Numerical modeling of a subsidence induced by underground coal gasification, including thermal effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stephenson, D.E.; Dass, S.T.; Shaw, D.E.

During normal coal extraction roof collapse is controlled, thermal effects are absent and existing data is useless for the formation of numerical models of underground coal gasification(PGU). Thermal deformation occurs during PGU to the extent that rock is deformed, the roof collapses, rock settles, and changes occur in the water-bearing layers, and so forth. As PGU progresses, changes occur in the geometry, size, and other characteristics of the volume of the reaction. Data derived from plastic coal in New Mexico (USA) is used to construct a numerical model. This coal was bedded at a depth of 259 meters where itmore » was stratified throughout a mixture of rock. Core drilling was conducted and a geological column was constructed to induce a PGY combustion front with temperatures of 900 degrees. Temperatures of 600 and 300 degrees were encountered 6.1 and 12.2 meters from the front, respectively. A short distance from the front, in a direction away from the placticized material, the temperature of the rock matched the 27 degree temperature in the surrounding rock. Correlational relationships were obtained for stress in rock under different conditions and these correlations were used to appraise the effect of heat on the rock. It was suggested that the heating of rock did, at times, serve to support the roof rock. Similarly, during periods of cooling, this effect lessened. Comparative and optimal test results are appraised with the aid of the numerical model.« less

A fast numerical solution of scattering by a cylinder: Spectral method for the boundary integral equations

NASA Technical Reports Server (NTRS)

Hu, Fang Q.

1994-01-01

It is known that the exact analytic solutions of wave scattering by a circular cylinder, when they exist, are not in a closed form but in infinite series which converges slowly for high frequency waves. In this paper, we present a fast number solution for the scattering problem in which the boundary integral equations, reformulated from the Helmholtz equation, are solved using a Fourier spectral method. It is shown that the special geometry considered here allows the implementation of the spectral method to be simple and very efficient. The present method differs from previous approaches in that the singularities of the integral kernels are removed and dealt with accurately. The proposed method preserves the spectral accuracy and is shown to have an exponential rate of convergence. Aspects of efficient implementation using FFT are discussed. Moreover, the boundary integral equations of combined single and double-layer representation are used in the present paper. This ensures the uniqueness of the numerical solution for the scattering problem at all frequencies. Although a strongly singular kernel is encountered for the Neumann boundary conditions, we show that the hypersingularity can be handled easily in the spectral method. Numerical examples that demonstrate the validity of the method are also presented.

The need for trust and safety inducing encounters: a qualitative exploration of women's experiences of seeking perinatal care when living as undocumented migrants in Sweden.

PubMed

Barkensjö, My; Greenbrook, Josephine T V; Rosenlundh, Josefine; Ascher, Henry; Elden, Helen

2018-06-07

Studies from around the world have shown that women living as undocumented migrants have limited and deficient access to perinatal care, increasing their risks of both physical and psychological complications during pregnancy and childbirth. Failures to provide equal access to healthcare have been criticized extensively by the United Nations. In 2013, undocumented migrants' rights to healthcare in Sweden were expanded to include full access to perinatal care. Research surrounding clinical encounters involving women living as undocumented migrants remains largely lacking. The present study aimed to provide a composite description of women's experiences of clinical encounters throughout pregnancy and childbirth, when living as undocumented migrants in Sweden. Taking an inductive approach, qualitative content analysis was implemented. Thirteen women from ten different countries were interviewed. Meaning-units were extracted from the data collected in order to identify emergent overarching themes. In clinical encounters where healthcare professionals displayed empathic concern and listening behaviours, women felt empowered, acknowledged, and encouraged, leading them to trust clinicians, diminishing fears relating to seeking healthcare services. Conversely, when neglectful behaviour on part of healthcare professionals was perceived in encounters, anxiousness and fear intensified. Vulnerability and distress induced by the women's uncertain living circumstances were apparent across themes, and appeared exacerbated by traumatic memories, difficulties in coping with motherhood, and fears of deportation. The present study contributes unique and important knowledge surrounding women's experience of being pregnant and giving birth when living as undocumented migrants. The overarching findings indicated that the needs of undocumented migrant women were largely similar to those of all expectant mothers, but that due to vulnerabilities relating to their circumstances, flexible and informed care provision is essential. Being knowledgeable on undocumented migrants' rights to healthcare is vital, as clinical encounters appeared highly consequential to the women's well-being and help-seeking behaviours. Negative encounters inflicted emotional distress and fear. Contrastingly, positive encounters promoted trust in clinicians, personal empowerment, and relief. Positive clinical encounters could provide rare opportunities to assist an otherwise elusive population at increased risk for both physical and psychological complications, highlighting the crucial need for adherence to ethical principles in clinical practice.

Numerical simulation of disperse particle flows on a graphics processing unit

NASA Astrophysics Data System (ADS)

Sierakowski, Adam J.

In both nature and technology, we commonly encounter solid particles being carried within fluid flows, from dust storms to sediment erosion and from food processing to energy generation. The motion of uncountably many particles in highly dynamic flow environments characterizes the tremendous complexity of such phenomena. While methods exist for the full-scale numerical simulation of such systems, current computational capabilities require the simplification of the numerical task with significant approximation using closure models widely recognized as insufficient. There is therefore a fundamental need for the investigation of the underlying physical processes governing these disperse particle flows. In the present work, we develop a new tool based on the Physalis method for the first-principles numerical simulation of thousands of particles (a small fraction of an entire disperse particle flow system) in order to assist in the search for new reduced-order closure models. We discuss numerous enhancements to the efficiency and stability of the Physalis method, which introduces the influence of spherical particles to a fixed-grid incompressible Navier-Stokes flow solver using a local analytic solution to the flow equations. Our first-principles investigation demands the modeling of unresolved length and time scales associated with particle collisions. We introduce a collision model alongside Physalis, incorporating lubrication effects and proposing a new nonlinearly damped Hertzian contact model. By reproducing experimental studies from the literature, we document extensive validation of the methods. We discuss the implementation of our methods for massively parallel computation using a graphics processing unit (GPU). We combine Eulerian grid-based algorithms with Lagrangian particle-based algorithms to achieve computational throughput up to 90 times faster than the legacy implementation of Physalis for a single central processing unit. By avoiding all data communication between the GPU and the host system during the simulation, we utilize with great efficacy the GPU hardware with which many high performance computing systems are currently equipped. We conclude by looking forward to the future of Physalis with multi-GPU parallelization in order to perform resolved disperse flow simulations of more than 100,000 particles and further advance the development of reduced-order closure models.

Problems Encountered by Novice Pair Programmers

ERIC Educational Resources Information Center

Hanks, Brian

2008-01-01

In a study of the types of problems encountered by students that led them to seek assistance, Robins et al. [2006] found that the most common problems were related to trivial mechanics. The students in this study worked by themselves on their programming exercises. This article discusses a replication of the Robins et al. study in which the…

A role for glucocorticoids in the long-term establishment of a social hierarchy.

PubMed

Timmer, Marjan; Sandi, Carmen

2010-11-01

Stress can affect the establishment and maintenance of social hierarchies. In the present study, we investigated the role of increasing corticosterone levels before or just after a first social encounter between two rats of a dyad in the establishment and the long-term maintenance of a social hierarchy. We show that pre-social encounter corticosterone treatment does not affect the outcome of the hierarchy during a first encounter, but induces a long-term memory for the hierarchy when the corticosterone-injected rat becomes dominant during the encounter, but not when it becomes subordinate. Post-social encounter corticosterone leads to a long-term maintenance of the hierarchy only when the subordinate rat of the dyad is injected with corticosterone. This corticosterone effect mimics previously reported actions of stress on the same model and, hence, implicates glucocorticoids in the consolidation of the memory for a recently established hierarchy. Copyright © 2010 Elsevier Ltd. All rights reserved.

Numerical Simulation of a High-Lift Configuration Embedded with High Momentum Fluidic Actuators

NASA Technical Reports Server (NTRS)

Vatsa, Veer N.; Duda, Benjamin; Fares, Ehab; Lin, John C.

2016-01-01

Numerical simulations have been performed for a vertical tail configuration with deflected rudder. The suction surface of the main element of this configuration, just upstream of the hinge line, is embedded with an array of 32 fluidic actuators that produce oscillating sweeping jets. Such oscillating jets have been found to be very effective for flow control applications in the past. In the current paper, a high-fidelity computational fluid dynamics (CFD) code known as the PowerFLOW R code is used to simulate the entire flow field associated with this configuration, including the flow inside the actuators. A fully compressible version of the PowerFLOW R code valid for high speed flows is used for the present simulations to accurately represent the transonic flow regimes encountered in the flow field due to the actuators operating at higher mass flow (momentum) rates required to mitigate reverse flow regions on a highly-deflected rudder surface. The computed results for the surface pressure and integrated forces compare favorably with measured data. In addition, numerical solutions predict the correct trends in forces with active flow control compared to the no control case. The effect of varying the rudder deflection angle on integrated forces and surface pressures is also presented.

A Numerical Combination of Extended Boundary Condition Method and Invariant Imbedding Method Applied to Light Scattering by Large Spheroids and Cylinders

NASA Technical Reports Server (NTRS)

Bi, Lei; Yang, Ping; Kattawar, George W.; Mishchenko, Michael I.

2013-01-01

The extended boundary condition method (EBCM) and invariant imbedding method (IIM) are two fundamentally different T-matrix methods for the solution of light scattering by nonspherical particles. The standard EBCM is very efficient but encounters a loss of precision when the particle size is large, the maximum size being sensitive to the particle aspect ratio. The IIM can be applied to particles in a relatively large size parameter range but requires extensive computational time due to the number of spherical layers in the particle volume discretization. A numerical combination of the EBCM and the IIM (hereafter, the EBCM+IIM) is proposed to overcome the aforementioned disadvantages of each method. Even though the EBCM can fail to obtain the T-matrix of a considered particle, it is valuable for decreasing the computational domain (i.e., the number of spherical layers) of the IIM by providing the initial T-matrix associated with an iterative procedure in the IIM. The EBCM+IIM is demonstrated to be more efficient than the IIM in obtaining the optical properties of large size parameter particles beyond the convergence limit of the EBCM. The numerical performance of the EBCM+IIM is illustrated through representative calculations in spheroidal and cylindrical particle cases.

Association of volume of patient encounters with residents' in-training examination performance.

PubMed

McCoy, Christopher P; Stenerson, Matthew B; Halvorsen, Andrew J; Homme, Jason H; McDonald, Furman S

2013-08-01

Patient care and medical knowledge are Accreditation Council for Graduate Medical Education (ACGME) core competencies. The correlation between amount of patient contact and knowledge acquisition is not known. To determine if a correlation exists between the number of patient encounters and in-training exam (ITE) scores in internal medicine (IM) and pediatric residents at a large academic medical center. Retrospective cohort study Resident physicians at Mayo Clinic from July 2006 to June 2010 in IM (318 resident-years) and pediatrics (66 resident-years). We tabulated patient encounters through review of clinical notes in an electronic medical record during post graduate year (PGY)-1 and PGY-2. Using linear regression models, we investigated associations between ITE score and number of notes during the previous PGY, adjusted for previous ITE score, gender, medical school origin, and conference attendance. For IM, PGY-2 admission and consult encounters in the hospital and specialty clinics had a positive linear association with ITE-3 % score (β = 0.02; p = 0.004). For IM, PGY-1 conference attendance is positively associated with PGY-2 ITE performance. We did not detect a correlation between PGY-1 patient encounters and subsequent ITE scores for IM or pediatric residents. No association was found between IM PGY-2 ITE score and inpatient, outpatient, or total encounters in the first year of training. Resident continuity clinic and total encounters were not associated with change in PGY-3 ITE score. We identified a positive association between hospital and subspecialty encounters during the second year of IM training and subsequent ITE score, such that each additional 50 encounters were associated with an increase of 1 % correct in PGY-3 ITE score after controlling for previous ITE performance and continuity clinic encounters. We did not find a correlation for volume of encounters and medical knowledge for IM PGY-1 residents or the pediatric cohort.

The work of nurses in Australian general practice: A national survey.

PubMed

Joyce, Catherine M; Piterman, Leon

2011-01-01

Following recent reforms to Australia's health system, nurses now comprise a significant and growing sector of the Australian primary care workforce, but there is little data describing the services they provide. This study aimed to describe the patient consultations of nurses in Australian general practice, including patient characteristics, reasons for the consultation, treatments provided and other actions taken. The study was a national cross-sectional survey, with each participating nurse collecting information about 50 nurse-patient encounters. General practice settings in all regions of Australia. 108 nurses volunteered in response to advertisements and 104 returned completed study materials. Participants included Registered (Division 1) and Enrolled (Division 2) nurses working in a general practice setting. Data were collected between May 2007 and May 2008 using a profile questionnaire and a series of encounter forms. Information was gathered on reasons for encounter, patient characteristics, and actions taken. Data were classified using the International Classification of Primary Care. The final data set included 5,253 nurse-patient encounters. 37.2% of patients (95% CI 33.3-41.2) were aged 65 and over, and 57.1% were female (95% CI 54.9-59.5). The majority of encounters (90.7%) were with existing patients of the practice (95% CI 89.1-92.7). The most common reasons for encounter were general and unspecified problems (35.4 per 100 encounters; 95% CI 31.8-39.1), followed by skin-related problems (20.0; 95% CI 17.3-22.8), and cardiovascular problems (11.0; 95% CI 8.7-13.3). Common management actions included medical examinations (20.7 per 100 encounters), immunisations (22.5), diagnostic tests (10.6), and dressings (15.8). Approximately 30% of encounters involved advice-giving. The findings confirm the generalist nature of the General Practice Nurse role, with a wide range of patient types and clinical conditions. There is a clear influence of current funding and organisational arrangements on work patterns, with tasks that have specific funding (including immunisations and wound care) featuring prominently in nurses' work. Whilst nurses' rates for presenting conditions were similar to doctors at a general level, specific actions taken and problems managed differed. New policy reforms in Australia are supporting greater flexibility in the General Practice Nurse role, maximising efficient use of nurses' skills in the primary health care context. Copyright © 2010 Elsevier Ltd. All rights reserved.

Verification of the Icarus Material Response Tool

NASA Technical Reports Server (NTRS)

Schroeder, Olivia; Palmer, Grant; Stern, Eric; Schulz, Joseph; Muppidi, Suman; Martin, Alexandre

2017-01-01

Due to the complex physics encountered during reentry, material response solvers are used for two main purposes: improve the understanding of the physical phenomena; and design and size thermal protection systems (TPS). Icarus, is a three dimensional, unstructured material response tool that is intended to be used for design while maintaining the flexibility to easily implement physical models as needed. Because TPS selection and sizing is critical, it is of the utmost importance that the design tools be extensively verified and validated before their use. Verification tests aim at insuring that the numerical schemes and equations are implemented correctly by comparison to analytical solutions and grid convergence tests.

A Comparison of Mental Health Diagnoses Treated via Interactive Video and Face to Face in the Veterans Healthcare Administration.

PubMed

Grubbs, Kathleen M; Fortney, John C; Dean, Tisha; Williams, James S; Godleski, Linda

2015-07-01

This study compares the mental health diagnoses of encounters delivered face to face and via interactive video in the Veterans Healthcare Administration (VHA). We compiled 1 year of national-level VHA administrative data for Fiscal Year 2012 (FY12). Mental health encounters were those with both a VHA Mental Health Stop Code and a Mental Health Diagnosis (n=11,906,114). Interactive video encounters were identified as those with a Mental Health Stop Code, paired with a VHA Telehealth Secondary Stop Code. Primary diagnoses were grouped into posttraumatic stress disorder (PTSD), depression, anxiety, bipolar disorder, psychosis, drug use, alcohol use, and other. In FY12, 1.5% of all mental health encounters were delivered via interactive video. Compared with face-to-face encounters, a larger percentage of interactive video encounters was for PTSD, depression, and anxiety, whereas a smaller percentage was for alcohol use, drug use, or psychosis. Providers and patients may feel more comfortable treating depression and anxiety disorders than substance use or psychosis via interactive video.

Accretion rates of protoplanets

NASA Astrophysics Data System (ADS)

Greenzweig, Yuval

The giant planets' solid cores must have formed prior to the dispersal of the primordial solar nebula, to allow the capture of their massive, gaseous envelopes from the nebula. Recent observations of disks of dust surrounding nearby solar-like stars lead to estimates of nebula lifetimes at 106 to 107 years. Thus, theories of solid particle accretion must explain how the solid cores of the giant planets may have formed within comparable timescales. Calculations are presented which support the sole currently hypothesized mechanism of planetary accretion in which the duration of the stage of growth from planetesimals (1 to 10 km size bodies) to moon- or planet-size bodies lies within the widely accepted time constraint mentioned above. It has been shown that under certain conditions a growth advantage is given to the larger bodies of a swarm of Sun-orbiting planetesimals, resulting in runaway growth of the largest body (or bodies) in the swarm. The gravitational cross section of the protoplanet (the largest body in the swarm) increases with its size, eventually requiring the inclusion of the effect of the solar tidal force on the interaction between it and a passing planetesimal. Thus, numerical integrations of the three-body problem (Sun, protoplanet and planetesimal) are needed to determine the accretion rates of protoplanets. Existing analytical formulas are refined for the two-body (no solar tidal force) accretion rates of planetesimals or small protoplanets, and numerically derives the three-body accretion rates of large protoplanets. The three-body accretion rates calculated span a wide range of protoplanetary orbital radii, masses, and densities, and a wide range of planetesimal orbital eccentricities and inclinations. The most useful numerical results are approximated by algebraic expressions, to facilitate their use in accretion calculations, particularly by numerical codes. Since planetary accretion rates depend strongly on planetesimal random velocities, the effect of the three body encounter on the velocity dispersion was also studied. It was found that protoplanets are more effective perturbers of planetesimal eccentricities than previously noted.

Numerical Filtering of Spurious Transients in a Satellite Scanning Radiometer: Application to CERES

NASA Technical Reports Server (NTRS)

Smith, G. Louis; Pandey, D. K.; Lee, Robert B., III; Barkstrom, Bruce R.; Priestley, Kory J.

2002-01-01

The Clouds and Earth Radiant Energy System (CERES) scanning, radiometer was designed to provide high accuracy measurements of the radiances from the earth. Calibration testing of the instruments showed the presence of all undesired slow transient in the measurements of all channels at 1% to 2% of the signal. Analysis of the data showed that the transient consists of a single linear mode. The characteristic time of this mode is 0.3 to 0.4 s and is much greater than that the 8-10-ms response time of the detector, so that it is well separated from the detector response. A numerical filter was designed for the removal of this transient from the measurements. Results show no trace remaining of the transient after application of the numerical filter. The characterization of the slow mode on the basis of ground calibration data is discussed and flight results are shown for the CERES instruments aboard the Tropical Rainfall Measurement Mission and Terra spacecraft. The primary influence of the slow mode is in the calibration of the instrument and the in-flight validation of the calibration. This method may be applicable to other radiometers that are striving for high accuracy and encounter a slow spurious mode regardless of the underlying physics.

Novel Numerical Approaches to Loop Quantum Cosmology

NASA Astrophysics Data System (ADS)

Diener, Peter

2015-04-01

Loop Quantum Gravity (LQG) is an (as yet incomplete) approach to the quantization of gravity. When applied to symmetry reduced cosmological spacetimes (Loop Quantum Cosmology or LQC) one of the predictions of the theory is that the Big Bang is replaced by a Big Bounce, i.e. a previously existing contracting universe underwent a bounce at finite volume before becoming our expanding universe. The evolution equations of LQC take the form of difference equations (with the discretization given by the theory) that in the large volume limit can be approximated by partial differential equations (PDEs). In this talk I will first discuss some of the unique challenges encountered when trying to numerically solve these difference equations. I will then present some of the novel approaches that have been employed to overcome the challenges. I will here focus primarily on the Chimera scheme that takes advantage of the fact that the LQC difference equations can be approximated by PDEs in the large volume limit. I will finally also briefly discuss some of the results that have been obtained using these numerical techniques by performing simulations in regions of parameter space that were previously unreachable. This work is supported by a grant from the John Templeton Foundation and by NSF grant PHYS1068743.

Factors associated with opioid dose increases: a chart review of patients’ first year on long-term opioids

PubMed Central

Bautista, Christopher A.; Iosif, Ana-Maria; Wilsey, Barth L.; Melnikow, Joy A.; Crichlow, Althea; Henry, Stephen G.

2016-01-01

OBJECTIVE To examine encounter-level factors associated with opioid dose increases during patients’ first year on opioid therapy for chronic pain. DESIGN Case-control study analyzing all opioid prescriptions for patients with chronic pain during their first year after opioid initiation. Cases were patients who experienced an overall dose escalation of ≥30 mg morphine equivalents over the 1-year period; controls did not experience overall dose escalation. Main measures were encounter type; opioid dose change; documented prescribing rationale; documentation of guideline-concordant opioid prescribing practices. Two coders reviewed all encounters associated with opioid prescriptions. Analysis of factors associated with dose increases and provider documentation of prescribing rationale was conducted using multiple logistic regression. RESULTS 674 encounters were coded for 66 patients (22 cases, 44 controls). Fifty-three percent of opioid prescriptions were associated with telephone encounters; 13% were associated with email encounters. No prescribing rationale was documented for 43% of all opioid prescriptions and 25% of dose increases. Likelihood of dose increase and documentation of prescribing rationale did not significantly differ for cases versus controls. Compared to face-to-face encounters, dose increases were significantly less likely for telephone (OR 0.18, 95%CI 0.11 – 0.28) and email (OR 0.23, 95%CI 0.12 – 0.47) encounters; documentation of prescribing rationale was significantly more likely for email (OR 5.06, 95%CI 1.87–13.72) and less likely for telephone (OR 0.30, 95%CI 0.18–0.51) encounters. CONCLUSION Most opioid prescriptions were written without face-to-face encounters. One quarter of dose increases contained no documented prescribing rationale. Documented encounter-level factors were not significantly associated with overall opioid dose escalation. PMID:27477581

To regain participation in occupations through human encounters--narratives from women with spinal cord injury.

PubMed

Isaksson, Gunilla; Josephsson, Staffan; Lexell, Jan; Skär, Lisa

2007-11-30

To gain an understanding of how women with spinal cord injury (SCI) experienced human encounters in occupations and how these influenced their participation. The data were collected through two or three in-depth interviews with 13 women (age 25-61 years) with SCI. Data analysis was carried out by using a paradigmatic analysis of narrative data, followed by an interpretation based on a narrative theory. The results showed a complexity where the women's experiences and acting in human encounters changed over time. In these human encounters the women struggled with conflicts, supported other persons that were insecure and revaluated their apprehension about persons in their social network. These multidimensional human encounters thereby enabled them to regain participation in occupations. This shows that human encounters are important for persons with disabilities so they can restructure their occupational identity and their needs for participation in occupations. The study also showed that the use of narratives as a tool within rehabilitation could lead to an increased understanding of the subjective changes that occur over time for a person with a disability.

Where Is the Engineering I Applied For? A Longitudinal Study of Students' Transition into Higher Education Engineering, and Their Considerations of Staying or Leaving

ERIC Educational Resources Information Center

Holmegaard, Henriette Tolstrup; Madsen, Lene Møller; Ulriksen, Lars

2016-01-01

This paper presents results from a qualitative longitudinal study of students' transition into higher education engineering. The study aims at comparing upper-secondary school students' expectations of engineering with their actual experiences when encountering the engineering programme. It explores how this encounter provides a platform for…

A method for communication analysis in prosthodontics.

PubMed

Sondell, K; Söderfeldt, B; Palmqvist, S

1998-02-01

Particularly in prosthodontics, in which the issues of esthetic preferences and possibilities are abundant, improved knowledge about dentist patient communication during clinical encounters is important. Because previous studies on communication used different methods and patient materials, the results are difficult to evaluate. There is, therefore, a need for methodologic development. One method that makes it possible to quantitatively describe different interaction behaviors during clinical encounters is the Roter Method of Interaction Process Analysis (RIAS). Since the method was developed in the USA for use in the medical context, a translation of the method into Swedish and a modification of the categories for use in prosthodontics were necessary. The revised manual was used to code 10 audio recordings of dentist patient encounters at a specialist clinic for prosthodontics. No major alterations of the RIAS manual were made during the translation and modification. The study shows that it is possible to distinguish patterns of communication in audio-recorded dentist patient encounters. The method also made the identification of different interaction profiles possible. These profiles distinguished well among the audio-recorded encounters. The coding procedures were tested for intra-rater reliability and found to be 97% for utterance classification and lambda = 0.76 for categorization definition. It was concluded that the revised RIAS method is applicable in communication studies in prosthodontics.

Interpersonal interactions, job demands and work-related outcomes in pharmacy.

PubMed

Gaither, Caroline A; Nadkarni, Anagha

2012-04-01

Objectives  The objective of this study was to examine the interaction between job demands of pharmacists and resources in the form of interpersonal interactions and its association with work-related outcomes such as organizational and professional commitment, job burnout, professional identity and job satisfaction. The job demands-resources (JD-R) model served as the theoretical framework. Methods  Subjects for the study were drawn from the Pharmacy Manpower Project Database (n = 1874). A 14-page mail-in survey measured hospital pharmacists' responses on the frequency of occurrence of various job-related scenarios as well as work-related outcomes. The study design was a 2 × 2 factorial design. Responses were collected on a Likert scale. Descriptive statistics, reliability analyses and correlational and multiple regression analyses were conducted using SPSS version 17 (SPSS, Chicago, IL, USA). Key findings  The 566 pharmacists (30% response rate) who responded to the survey indicated that high-demand/pleasant encounters and low-demand/pleasant encounters occurred more frequently in the workplace. The strongest correlations were found between high-demand/unpleasant encounters and frequency and intensity of emotional exhaustion. Multiple regression analyses indicated that when controlling for demographic factors high-demand/unpleasant encounters were negatively related to affective organizational commitment and positively related to frequency and intensity of emotional exhaustion. Low-demand/pleasant encounters were positively related to frequency and intensity of personal accomplishment. Low-demand/unpleasant encounters were significantly and negatively related to professional commitment, job satisfaction and frequency and intensity of emotional exhaustion, while high-demand/pleasant encounters were also related to frequency and intensity of emotional exhaustion Conclusion  Support was found for the JD-R model and the proposed interaction effects. Study results suggest that adequate attention must be paid to the interplay between demands on the job and interactions with healthcare professionals to improve the quality of the pharmacist's work life. Future research should examine other types of job demands and resources. © 2011 The Authors. IJPP © 2011 Royal Pharmaceutical Society.

Emergence of encounter networks due to human mobility.

PubMed

Riascos, A P; Mateos, José L

2017-01-01

There is a burst of work on human mobility and encounter networks. However, the connection between these two important fields just begun recently. It is clear that both are closely related: Mobility generates encounters, and these encounters might give rise to contagion phenomena or even friendship. We model a set of random walkers that visit locations in space following a strategy akin to Lévy flights. We measure the encounters in space and time and establish a link between walkers after they coincide several times. This generates a temporal network that is characterized by global quantities. We compare this dynamics with real data for two cities: New York City and Tokyo. We use data from the location-based social network Foursquare and obtain the emergent temporal encounter network, for these two cities, that we compare with our model. We found long-range (Lévy-like) distributions for traveled distances and time intervals that characterize the emergent social network due to human mobility. Studying this connection is important for several fields like epidemics, social influence, voting, contagion models, behavioral adoption and diffusion of ideas.

An immersed boundary formulation for simulating high-speed compressible viscous flows with moving solids

NASA Astrophysics Data System (ADS)

Qu, Yegao; Shi, Ruchao; Batra, Romesh C.

2018-02-01

We present a robust sharp-interface immersed boundary method for numerically studying high speed flows of compressible and viscous fluids interacting with arbitrarily shaped either stationary or moving rigid solids. The Navier-Stokes equations are discretized on a rectangular Cartesian grid based on a low-diffusion flux splitting method for inviscid fluxes and conservative high-order central-difference schemes for the viscous components. Discontinuities such as those introduced by shock waves and contact surfaces are captured by using a high-resolution weighted essentially non-oscillatory (WENO) scheme. Ghost cells in the vicinity of the fluid-solid interface are introduced to satisfy boundary conditions on the interface. Values of variables in the ghost cells are found by using a constrained moving least squares method (CMLS) that eliminates numerical instabilities encountered in the conventional MLS formulation. The solution of the fluid flow and the solid motion equations is advanced in time by using the third-order Runge-Kutta and the implicit Newmark integration schemes, respectively. The performance of the proposed method has been assessed by computing results for the following four problems: shock-boundary layer interaction, supersonic viscous flows past a rigid cylinder, moving piston in a shock tube and lifting off from a flat surface of circular, rectangular and elliptic cylinders triggered by shock waves, and comparing computed results with those available in the literature.

Algorithm For Hypersonic Flow In Chemical Equilibrium

NASA Technical Reports Server (NTRS)

Palmer, Grant

1989-01-01

Implicit, finite-difference, shock-capturing algorithm calculates inviscid, hypersonic flows in chemical equilibrium. Implicit formulation chosen because overcomes limitation on mathematical stability encountered in explicit formulations. For dynamical portion of problem, Euler equations written in conservation-law form in Cartesian coordinate system for two-dimensional or axisymmetric flow. For chemical portion of problem, equilibrium state of gas at each point in computational grid determined by minimizing local Gibbs free energy, subject to local conservation of molecules, atoms, ions, and total enthalpy. Major advantage: resulting algorithm naturally stable and captures strong shocks without help of artificial-dissipation terms to damp out spurious numerical oscillations.

Emerge - A Python environment for the modeling of subsurface transfers

NASA Astrophysics Data System (ADS)

Lopez, S.; Smai, F.; Sochala, P.

2014-12-01

The simulation of subsurface mass and energy transfers often relies on specific codes that were mainly developed using compiled languages which usually ensure computational efficiency at the expense of relatively long development times and relatively rigid software. Even if a very detailed, possibly graphical, user-interface is developed the core numerical aspects are rarely accessible and the smallest modification will always need a compilation step. Thus, user-defined physical laws or alternative numerical schemes may be relatively difficult to use. Over the last decade, Python has emerged as a popular and widely used language in the scientific community. There already exist several libraries for the pre and post-treatment of input and output files for reservoir simulators (e.g. pytough). Development times in Python are considerably reduced compared to compiled languages, and programs can be easily interfaced with libraries written in compiled languages with several comprehensive numerical libraries that provide sequential and parallel solvers (e.g. PETSc, Trilinos…). The core objective of the Emerge project is to explore the possibility to develop a modeling environment in full Python. Consequently, we are developing an open python package with the classes/objects necessary to express, discretize and solve the physical problems encountered in the modeling of subsurface transfers. We heavily relied on Python to have a convenient and concise way of manipulating potentially complex concepts with a few lines of code and a high level of abstraction. Our result aims to be a friendly numerical environment targeting both numerical engineers and physicist or geoscientists with the possibility to quickly specify and handle geometries, arbitrary meshes, spatially or temporally varying properties, PDE formulations, boundary conditions…

Atmospheric chemical transport based on high-resolution model-derived winds: A case study

NASA Astrophysics Data System (ADS)

Hannan, John R.; Fuelberg, Henry E.; Thompson, Anne M.; Bieberbach, George; Knabb, Richard D.; Kondo, Yutaka; Anderson, Bruce E.; Browell, Edward V.; Gregory, Gerald L.; Sachse, Glen W.; Singh, Hanwant B.

2000-02-01

Flight 10 of NASA's Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) extended southwest of Lajes, Azores. A variety of chemical signatures was encountered. These signatures are examined in detail, relating them to meteorological data from a high-resolution numerical model having a horizontal grid spacing of 30 and 90 km with 26 vertical levels. The meteorological output at hourly intervals is used to create backward trajectories from the locations of the chemical signatures. Four major categories of chemical signatures are discussed: stratospheric, lightning, continental pollution, and a mixed chemical layer. The strong stratospheric signal is encountered just south of the Azores in a region of depressed tropopause height. Three chemical signatures at different altitudes in the upper troposphere are attributed to lightning. Backward trajectories from these signatures extend to locations of cloud-to-ground lightning. Specifically, results show that the trajectories pass over regions of lightning 1-2 days earlier over the eastern Gulf of Mexico and off the southeast coast of the United States. The lowest leg of the flight exhibits a chemical signature consistent with continental pollution. Trajectories from this signature are found to pass over the highly populated Northeast Corridor of the United States. Surface-based pollution apparently is lofted to the altitudes of the trajectories by convective clouds along the East Coast that did not contain lightning. Finally, a mixed layer is described. Its chemical signature is intermediate to those of lightning and continental pollution. Backward trajectories from this layer pass between the trajectories of the lightning and pollution signatures. Thus they likely are impacted by both sources.

Patient-Entered Wellness Data and Tailored Electronic Recommendations Increase Preventive Care.

PubMed

Foucher-Urcuyo, Julie; Longworth, David; Roizen, Michael; Hu, Bo; Rothberg, Michael B

2017-01-01

We investigated whether a tool using patient-entered wellness data to generate tailored electronic recommendations improved preventive care delivery. We conducted a mixed-methods retrospective study of primary care encounters utilizing an Integrated Wellness Tool with a matched-comparison before-and-after study design. Encounters took place at a single clinic within the Cleveland Clinic Health System. The primary outcome was preventive orders placed. Index patients were matched, based on propensity scores, with comparison patients seen in the same clinic several months earlier. Five providers conducted 863 patient encounters using the tool during the study period. During encounters using the tool, providers placed more orders for smoking cessation programs (2.4 vs 0.5%, P < .01), lifestyle medicine (2.4 vs 0%, P < .01) and psychology (2.3 vs 1.0%, P = .04) consults, online nutrition (2.4 vs 1.4%, P = .04) and stress management (5.5 vs 0.9%, P < .01) programs, spirometry (5.9 vs 1.7%, P < .01) and polysomnography (6.3 vs 1.3%, P < .01) tests, and antidepressant (7.2 vs 3.9%, P = .01) and hypnotic (2.2 vs 0.7%, P = .01) medications when compared with matched encounters. Patients are willing to enter lifestyle data, and these data influence provider orders. © Copyright 2017 by the American Board of Family Medicine.

Problems Encountered during the Scientific Research Process in Graduate Education: The Institute of Educational Sciences

ERIC Educational Resources Information Center

Akyürek, Erkan; Afacan, Özlem

2018-01-01

This study was conducted to determine the problems faced by graduate students when conducting scientific research and to make suggestions for solving these problems. The research model was a case study. Semi-structured interviews were conducted with participants in the study with questions about the problems encountered during scientific research…

Helping Students Navigate Faith Challenges in the Biblical Studies Classroom

ERIC Educational Resources Information Center

Sharp, Carolyn J.; Clark-Soles, Jaime

2012-01-01

What happens when students encounter the academic study of the Bible in the seminary or undergraduate classroom? Does a teacher have a responsibility to help students navigate challenges to Christian faith that might arise? What pedagogical problems and opportunities does this encounter present? How does this issue manifest differently in…