Science.gov

Sample records for allowable time step

  1. Development of a Real-Time PCR for a Sensitive One-Step Coprodiagnosis Allowing both the Identification of Carnivore Feces and the Detection of Toxocara spp. and Echinococcus multilocularis.

    PubMed

    Knapp, Jenny; Umhang, Gérald; Poulle, Marie-Lazarine; Millon, Laurence

    2016-05-15

    Studying the environmental occurrence of parasites of concern for humans and animals based on coprosamples is an expanding field of work in epidemiology and the ecology of health. Detecting and quantifying Toxocara spp. and Echinococcus multilocularis, two predominant zoonotic helminths circulating in European carnivores, in feces may help to better target measures for prevention. A rapid, sensitive, and one-step quantitative PCR (qPCR) allowing detection of E. multilocularis and Toxocara spp. was developed in the present study, combined with a host fecal test based on the identification of three carnivores (red fox, dog, and cat) involved in the life cycles of these parasites. A total of 68 coprosamples were collected from identified specimens from Vulpes vulpes, Canis lupus familiaris, Canis lupus, Felis silvestris catus, Meles meles, Martes foina, and Martes martes With DNA coprosamples, real-time PCR was performed in duplex with a qPCR inhibitor control specifically designed for this study. All the coprosample host identifications were confirmed by qPCR combined with sequencing, and parasites were detected and confirmed (E. multilocularis in red foxes and Toxocara cati in cats; 16% of samples presented inhibition). By combining parasite detection and quantification, the host fecal test, and a new qPCR inhibitor control, we created a technique with a high sensitivity that may considerably improve environmental studies of pathogens. PMID:26969697

  2. Simulating system dynamics with arbitrary time step

    NASA Astrophysics Data System (ADS)

    Kantorovich, L.

    2007-02-01

    We suggest a dynamic simulation method that allows efficient and realistic modeling of kinetic processes, such as atomic diffusion, in which time has its actual meaning. Our method is similar in spirit to widely used kinetic Monte Carlo (KMC) techniques; however, in our approach, the time step can be chosen arbitrarily. This has an advantage in some cases, e.g., when the transition rates change with time sufficiently fast over the period of the KMC time step (e.g., due to time dependence of some external factors influencing kinetics such as moving scanning probe microscopy tip or external time-dependent field) or when the clock time is set by some external conditions, and it is convenient to use equal time steps instead of the random choice of the KMC algorithm in order to build up probability distribution functions. We show that an arbitrary choice of the time step can be afforded by building up the complete list of events including the “residence site” and multihop transitions. The idea of the method is illustrated in a simple “toy” model of a finite one-dimensional lattice of potential wells with unequal jump rates to either side, which can be studied analytically. We show that for any choice of the time step, our general kinetics method reproduces exactly the solution of the corresponding master equations for any choice of the time steps. The final kinetics also matches the standard KMC, and this allows better understanding of this algorithm, in which the time step is chosen in a certain way and the system always advances by a single hop.

  3. Grief: Difficult Times, Simple Steps.

    ERIC Educational Resources Information Center

    Waszak, Emily Lane

    This guide presents techniques to assist others in coping with the loss of a loved one. Using the language of 9 layperson, the book contains more than 100 tips for caregivers or loved ones. A simple step is presented on each page, followed by reasons and instructions for each step. Chapters include: "What to Say"; "Helpful Things to Do"; "Dealing…

  4. Extrapolated implicit-explicit time stepping.

    SciTech Connect

    Constantinescu, E. M.; Sandu, A.; Mathematics and Computer Science; Virginia Polytechnic Inst. and State Univ.

    2010-01-01

    This paper constructs extrapolated implicit-explicit time stepping methods that allow one to efficiently solve problems with both stiff and nonstiff components. The proposed methods are based on Euler steps and can provide very high order discretizations of ODEs, index-1 DAEs, and PDEs in the method-of-lines framework. Implicit-explicit schemes based on extrapolation are simple to construct, easy to implement, and straightforward to parallelize. This work establishes the existence of perturbed asymptotic expansions of global errors, explains the convergence orders of these methods, and studies their linear stability properties. Numerical results with stiff ODE, DAE, and PDE test problems confirm the theoretical findings and illustrate the potential of these methods to solve multiphysics multiscale problems.

  5. Obtaining Runge-Kutta Solutions Between Time Steps

    NASA Technical Reports Server (NTRS)

    Horn, M. K.

    1984-01-01

    New interpolation method used with existing Runge-Kutta algorithms. Algorithm evaluates solution at intermediate point within integration step. Only few additional computations required to produce intermediate solution data. Runge-Kutta method provides accurate solution with larger time steps than allowable in other methods.

  6. 40 CFR 264.113 - Closure; time allowed for closure.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Closure; time allowed for closure. 264... (CONTINUED) STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Closure and Post-Closure § 264.113 Closure; time allowed for closure. (a) Within 90 days after...

  7. 40 CFR 265.113 - Closure; time allowed for closure.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Closure; time allowed for closure. 265... (CONTINUED) INTERIM STATUS STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Closure and Post-Closure § 265.113 Closure; time allowed for closure. (a) Within...

  8. Progress Report on Alloy 617 Time Dependent Allowables

    SciTech Connect

    Wright, Julie Knibloe

    2015-06-01

    Time dependent allowable stresses are required in the ASME Boiler and Pressure Vessel Code for design of components in the temperature range where time dependent deformation (i.e., creep) is expected to become significant. There are time dependent allowable stresses in Section IID of the Code for use in the non-nuclear construction codes, however, there are additional criteria that must be considered in developing time dependent allowables for nuclear components. These criteria are specified in Section III NH. St is defined as the lesser of three quantities: 100% of the average stress required to obtain a total (elastic, plastic, primary and secondary creep) strain of 1%; 67% of the minimum stress to cause rupture; and 80% of the minimum stress to cause the initiation of tertiary creep. The values are reported for a range of temperatures and for time increments up to 100,000 hours. These values are determined from uniaxial creep tests, which involve the elevated temperature application of a constant load which is relatively small, resulting in deformation over a long time period prior to rupture. The stress which is the minimum resulting from these criteria is the time dependent allowable stress St. In this report data from a large number of creep and creep-rupture tests on Alloy 617 are analyzed using the ASME Section III NH criteria. Data which are used in the analysis are from the ongoing DOE sponsored high temperature materials program, form Korea Atomic Energy Institute through the Generation IV VHTR Materials Program and historical data from previous HTR research and vendor data generated in developing the alloy. It is found that the tertiary creep criterion determines St at highest temperatures, while the stress to cause 1% total strain controls at low temperatures. The ASME Section III Working Group on Allowable Stress Criteria has recommended that the uncertainties associated with determining the onset of tertiary creep and the lack of significant

  9. Simulating stochastic dynamics using large time steps.

    PubMed

    Corradini, O; Faccioli, P; Orland, H

    2009-12-01

    We present an approach to investigate the long-time stochastic dynamics of multidimensional classical systems, in contact with a heat bath. When the potential energy landscape is rugged, the kinetics displays a decoupling of short- and long-time scales and both molecular dynamics or Monte Carlo (MC) simulations are generally inefficient. Using a field theoretic approach, we perform analytically the average over the short-time stochastic fluctuations. This way, we obtain an effective theory, which generates the same long-time dynamics of the original theory, but has a lower time-resolution power. Such an approach is used to develop an improved version of the MC algorithm, which is particularly suitable to investigate the dynamics of rare conformational transitions. In the specific case of molecular systems at room temperature, we show that elementary integration time steps used to simulate the effective theory can be chosen a factor approximately 100 larger than those used in the original theory. Our results are illustrated and tested on a simple system, characterized by a rugged energy landscape. PMID:20365123

  10. A Stochastic, Resonance-Free Multiple Time-Step Algorithm for Polarizable Models That Permits Very Large Time Steps.

    PubMed

    Margul, Daniel T; Tuckerman, Mark E

    2016-05-10

    the polarizable AMOEBA water model. As was seen with fixed-charge models, we are able to obtain large time steps exceeding 100 fs, allowing calculations to be performed 10 to 20 times faster than standard thermostated molecular dynamics. PMID:27054809

  11. Time to pause before the next step

    SciTech Connect

    Siemon, R.E.

    1998-12-31

    Many scientists, who have staunchly supported ITER for years, are coming to realize it is time to further rethink fusion energy`s development strategy. Specifically, as was suggested by Grant Logan and Dale Meade, and in keeping with the restructuring of 1996, a theme of better, cheaper, faster fusion would serve the program more effectively than ``demonstrating controlled ignition...and integrated testing of the high-heat-flux and nuclear components required to utilize fusion energy...`` which are the important ingredients of ITER`s objectives. The author has personally shifted his view for a mixture of technical and political reasons. On the technical side, he senses that through advanced tokamak research, spherical tokamak research, and advanced stellarator work, scientists are coming to a new understanding that might make a burning-plasma device significantly smaller and less expensive. Thus waiting for a few years, even ten years, seems prudent. Scientifically, there is fascinating physics to be learned through studies of burning plasma on a tokamak. And clearly if one wishes to study burning plasma physics in a sustained plasma, there is no other configuration with an adequate database on which to proceed. But what is the urgency of moving towards an ITER-like step focused on burning plasma? Some of the arguments put forward and the counter arguments are discussed here.

  12. Adaptive time steps in trajectory surface hopping simulations.

    PubMed

    Spörkel, Lasse; Thiel, Walter

    2016-05-21

    Trajectory surface hopping (TSH) simulations are often performed in combination with active-space multi-reference configuration interaction (MRCI) treatments. Technical problems may arise in such simulations if active and inactive orbitals strongly mix and switch in some particular regions. We propose to use adaptive time steps when such regions are encountered in TSH simulations. For this purpose, we present a computational protocol that is easy to implement and increases the computational effort only in the critical regions. We test this procedure through TSH simulations of a GFP chromophore model (OHBI) and a light-driven rotary molecular motor (F-NAIBP) on semiempirical MRCI potential energy surfaces, by comparing the results from simulations with adaptive time steps to analogous ones with constant time steps. For both test molecules, the number of successful trajectories without technical failures rises significantly, from 53% to 95% for OHBI and from 25% to 96% for F-NAIBP. The computed excited-state lifetime remains essentially the same for OHBI and increases somewhat for F-NAIBP, and there is almost no change in the computed quantum efficiency for internal rotation in F-NAIBP. We recommend the general use of adaptive time steps in TSH simulations with active-space CI methods because this will help to avoid technical problems, increase the overall efficiency and robustness of the simulations, and allow for a more complete sampling. PMID:27208937

  13. Adaptive time steps in trajectory surface hopping simulations

    NASA Astrophysics Data System (ADS)

    Spörkel, Lasse; Thiel, Walter

    2016-05-01

    Trajectory surface hopping (TSH) simulations are often performed in combination with active-space multi-reference configuration interaction (MRCI) treatments. Technical problems may arise in such simulations if active and inactive orbitals strongly mix and switch in some particular regions. We propose to use adaptive time steps when such regions are encountered in TSH simulations. For this purpose, we present a computational protocol that is easy to implement and increases the computational effort only in the critical regions. We test this procedure through TSH simulations of a GFP chromophore model (OHBI) and a light-driven rotary molecular motor (F-NAIBP) on semiempirical MRCI potential energy surfaces, by comparing the results from simulations with adaptive time steps to analogous ones with constant time steps. For both test molecules, the number of successful trajectories without technical failures rises significantly, from 53% to 95% for OHBI and from 25% to 96% for F-NAIBP. The computed excited-state lifetime remains essentially the same for OHBI and increases somewhat for F-NAIBP, and there is almost no change in the computed quantum efficiency for internal rotation in F-NAIBP. We recommend the general use of adaptive time steps in TSH simulations with active-space CI methods because this will help to avoid technical problems, increase the overall efficiency and robustness of the simulations, and allow for a more complete sampling.

  14. Multiple time step integrators in ab initio molecular dynamics

    SciTech Connect

    Luehr, Nathan; Martínez, Todd J.; Markland, Thomas E.

    2014-02-28

    Multiple time-scale algorithms exploit the natural separation of time-scales in chemical systems to greatly accelerate the efficiency of molecular dynamics simulations. Although the utility of these methods in systems where the interactions are described by empirical potentials is now well established, their application to ab initio molecular dynamics calculations has been limited by difficulties associated with splitting the ab initio potential into fast and slowly varying components. Here we present two schemes that enable efficient time-scale separation in ab initio calculations: one based on fragment decomposition and the other on range separation of the Coulomb operator in the electronic Hamiltonian. We demonstrate for both water clusters and a solvated hydroxide ion that multiple time-scale molecular dynamics allows for outer time steps of 2.5 fs, which are as large as those obtained when such schemes are applied to empirical potentials, while still allowing for bonds to be broken and reformed throughout the dynamics. This permits computational speedups of up to 4.4x, compared to standard Born-Oppenheimer ab initio molecular dynamics with a 0.5 fs time step, while maintaining the same energy conservation and accuracy.

  15. Dependence of aqua-planet simulations on time step

    NASA Astrophysics Data System (ADS)

    Williamson, David L.; Olson, Jerry G.

    2003-04-01

    Aqua-planet simulations with Eulerian and semi-Lagrangian dynamical cores coupled to the NCAR CCM3 parametrization suite produce very different zonal average precipitation patterns. The model with the Eulerian core forms a narrow single precipitation peak centred on the sea surface temperature (SST) maximum. The one with the semi-Lagrangian core forms a broad structure often with a double peak straddling the SST maximum with a precipitation minimum centred on the SST maximum. The different structure is shown to be caused primarily by the different time step adopted by each core and its effect on the parametrizations rather than by different truncation errors introduced by the dynamical cores themselves. With a longer discrete time step, the surface exchange parametrization deposits more moisture in the atmosphere in a single time step, resulting in convection being initiated farther from the equator, closer to the maximum source. Different diffusive smoothing associated with different spectral resolutions is a secondary effect influencing the strength of the double structure. When the semi-Lagrangian core is configured to match the Eulerian with the same time step, a three-time-level formulation and same spectral truncation it produces precipitation fields similar to those from the Eulerian. It is argued that the broad and double structure forms in this model with the longer time step because more water is put into the atmosphere over a longer discrete time step, the evaporation rate being the same. The additional water vapour in the region of equatorial moisture convergence results in more convective available potential energy farther from the equator which allows convection to initiate farther from the equator.The resulting heating drives upward vertical motion and low-level convergence away from the equator, resulting in much weaker upward motion at the equator. The feedback between the convective heating and dynamics reduces the instability at the equator and

  16. Seven Steps to On-Time Delivery.

    ERIC Educational Resources Information Center

    Konchar, Mark; Sanvido, Victor

    1999-01-01

    Describes seven steps to consider when making project-delivery decisions that include defining the school district's goals and profile, selecting the project-delivery system and procurement method, selecting the project team and contract type, and developing and confirming the facility program. Concluding comments address the district review of…

  17. Assessment Data at Your Fingertips: Advances Allow for Timely Reporting

    ERIC Educational Resources Information Center

    Bolch, Matt

    2009-01-01

    The ever-increasing standards of No Child Left Behind regulations and various state assessments have put more pressure on teachers and administrators to monitor the learning process. Fortunately, the advent of technology is allowing teachers to test more often to prepare students for high-stakes tests and for districts to understand results for…

  18. Collocation and Galerkin Time-Stepping Methods

    NASA Technical Reports Server (NTRS)

    Huynh, H. T.

    2011-01-01

    We study the numerical solutions of ordinary differential equations by one-step methods where the solution at tn is known and that at t(sub n+1) is to be calculated. The approaches employed are collocation, continuous Galerkin (CG) and discontinuous Galerkin (DG). Relations among these three approaches are established. A quadrature formula using s evaluation points is employed for the Galerkin formulations. We show that with such a quadrature, the CG method is identical to the collocation method using quadrature points as collocation points. Furthermore, if the quadrature formula is the right Radau one (including t(sub n+1)), then the DG and CG methods also become identical, and they reduce to the Radau IIA collocation method. In addition, we present a generalization of DG that yields a method identical to CG and collocation with arbitrary collocation points. Thus, the collocation, CG, and generalized DG methods are equivalent, and the latter two methods can be formulated using the differential instead of integral equation. Finally, all schemes discussed can be cast as s-stage implicit Runge-Kutta methods.

  19. Time scaling relations for step bunches from models with step-step attractions (B1-type models)

    NASA Astrophysics Data System (ADS)

    Krasteva, A.; Popova, H.; Akutsu, N.; Tonchev, V.

    2016-03-01

    The step bunching instability is studied in three models of step motion defined in terms of ordinary differential equations (ODE). The source of instability in these models is step-step attraction, it is opposed by step-step repulsion and the developing surface patterns reflect the balance between the two. The first model, TE2, is a generalization of the seminal model of Tersoff et al. (1995). The second one, LW2, is obtained from the model of Liu and Weeks (1998) using the repulsions term to construct the attractions one with retained possibility to change the parameters in the two independently. The third model, MM2, is a minimal one constructed ad hoc and in this article it plays a central role. New scheme for scaling the ODE in vicinal studies is applied towards deciphering the pre-factors in the time-scaling relations. In all these models the patterned surface is self-similar - only one length scale is necessary to describe its evolution (hence B1-type). The bunches form finite angles with the terraces. Integrating numerically the equations for step motion and changing systematically the parameters we obtain the overall dependence of time-scaling exponent β on the power of step-step attractions p as β = 1/(3+p) for MM2 and hypothesize based on restricted set of data that it is β = 1/(5+p) for LW2 and TE2.

  20. Improving quality: one step at a time.

    PubMed

    Blankson-seck, N; Butta, P

    1999-01-01

    The notion that health care workers have the power to improve the quality of their services is a key to AVSC's efforts worldwide. The COPE process, AVSC's low-cost intervention for improving quality at service sites, brings together supervisors and staff at all levels to identify barriers to quality services and helps them find solutions they can implement with their own resources. For example, a hospital in Tanzania had tried unsuccessfully to obtain the funds to repair or replace broken equipment. Using the COPE process, the hospital used available funds to send a technician for training in maintenance and repair. Now everything from blood pressure equipment to bedsprings is repaired promptly, and quality has improved. Another hospital in Tanzania coped with the problem of broken bedsprings (patients were putting mattresses on the floor) by using readily available wire mesh to make repairs. In Kenya, the lack of running water forced staff to collect water from a cistern, taking time from their other responsibilities. During a COPE meeting to resolve the problem the staff bemoaned the fact that they did not have the funds to replace the water system. Then the gardener told the group that all they needed to do was fix a broken pipe. The repair was made at minimal cost, and the water supply was restored. The COPE process reveals that health care staff not only can identify obstacles to quality, they often know the cause of the problem and can offer the best solutions. PMID:12295155

  1. Hydrologic consistency analysed through modeling at multiple time steps: does hydrological model performance benefit from finer time step information?

    NASA Astrophysics Data System (ADS)

    Ficchi, Andrea; Perrin, Charles; Andréassian, Vazken

    2015-04-01

    We investigate the operational utility of fine time step hydro-climatic information using a large catchment data set. The originality of this data set lies in the availability of precipitation data from the 6-minute rain gauges of Météo-France, and in the size of the catchment set (217 French catchments in total). The rainfall-runoff model used (GR4) has been adapted to hourly and sub-hourly time steps (up to 6-minute) from the daily time step version (Perrin et al., 2003). The model is applied at different time steps ranging from 6-minute to 1 day (6-, 12-, 30-minute, 1-, 3-, 6-, 12-hour and 1 day) and the evolution of model performance for each catchment is evaluated at the daily time step by aggregation of model outputs. Three classes of behavior are found according to the trend of model performance as the time step becomes finer: (i) catchments presenting an improvement of model performance; (ii) catchments with a model performance insensitive to the time step; (iii) catchments for which the performance even deteriorates as the time step becomes finer. The reasons behind these different trends are investigated from a hydrological point of view, by relating the model sensitivity to data at finer time step to catchment descriptors. References: Perrin, C., C. Michel and V. Andréassian (2003), "Improvement of a parsimonious model for streamflow simulation", Journal of Hydrology, 279(1-4): 275-289.

  2. Multiple-time-stepping generalized hybrid Monte Carlo methods

    NASA Astrophysics Data System (ADS)

    Escribano, Bruno; Akhmatskaya, Elena; Reich, Sebastian; Azpiroz, Jon M.

    2015-01-01

    Performance of the generalized shadow hybrid Monte Carlo (GSHMC) method [1], which proved to be superior in sampling efficiency over its predecessors [2-4], molecular dynamics and hybrid Monte Carlo, can be further improved by combining it with multi-time-stepping (MTS) and mollification of slow forces. We demonstrate that the comparatively simple modifications of the method not only lead to better performance of GSHMC itself but also allow for beating the best performed methods, which use the similar force splitting schemes. In addition we show that the same ideas can be successfully applied to the conventional generalized hybrid Monte Carlo method (GHMC). The resulting methods, MTS-GHMC and MTS-GSHMC, provide accurate reproduction of thermodynamic and dynamical properties, exact temperature control during simulation and computational robustness and efficiency. MTS-GHMC uses a generalized momentum update to achieve weak stochastic stabilization to the molecular dynamics (MD) integrator. MTS-GSHMC adds the use of a shadow (modified) Hamiltonian to filter the MD trajectories in the HMC scheme. We introduce a new shadow Hamiltonian formulation adapted to force-splitting methods. The use of such Hamiltonians improves the acceptance rate of trajectories and has a strong impact on the sampling efficiency of the method. Both methods were implemented in the open-source MD package ProtoMol and were tested on a water and a protein systems. Results were compared to those obtained using a Langevin Molly (LM) method [5] on the same systems. The test results demonstrate the superiority of the new methods over LM in terms of stability, accuracy and sampling efficiency. This suggests that putting the MTS approach in the framework of hybrid Monte Carlo and using the natural stochasticity offered by the generalized hybrid Monte Carlo lead to improving stability of MTS and allow for achieving larger step sizes in the simulation of complex systems.

  3. Multiple-time-stepping generalized hybrid Monte Carlo methods

    SciTech Connect

    Escribano, Bruno; Akhmatskaya, Elena; Reich, Sebastian; Azpiroz, Jon M.

    2015-01-01

    Performance of the generalized shadow hybrid Monte Carlo (GSHMC) method [1], which proved to be superior in sampling efficiency over its predecessors [2–4], molecular dynamics and hybrid Monte Carlo, can be further improved by combining it with multi-time-stepping (MTS) and mollification of slow forces. We demonstrate that the comparatively simple modifications of the method not only lead to better performance of GSHMC itself but also allow for beating the best performed methods, which use the similar force splitting schemes. In addition we show that the same ideas can be successfully applied to the conventional generalized hybrid Monte Carlo method (GHMC). The resulting methods, MTS-GHMC and MTS-GSHMC, provide accurate reproduction of thermodynamic and dynamical properties, exact temperature control during simulation and computational robustness and efficiency. MTS-GHMC uses a generalized momentum update to achieve weak stochastic stabilization to the molecular dynamics (MD) integrator. MTS-GSHMC adds the use of a shadow (modified) Hamiltonian to filter the MD trajectories in the HMC scheme. We introduce a new shadow Hamiltonian formulation adapted to force-splitting methods. The use of such Hamiltonians improves the acceptance rate of trajectories and has a strong impact on the sampling efficiency of the method. Both methods were implemented in the open-source MD package ProtoMol and were tested on a water and a protein systems. Results were compared to those obtained using a Langevin Molly (LM) method [5] on the same systems. The test results demonstrate the superiority of the new methods over LM in terms of stability, accuracy and sampling efficiency. This suggests that putting the MTS approach in the framework of hybrid Monte Carlo and using the natural stochasticity offered by the generalized hybrid Monte Carlo lead to improving stability of MTS and allow for achieving larger step sizes in the simulation of complex systems.

  4. Time step and shadow Hamiltonian in molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Kim, Sangrak

    2015-08-01

    We examine the time step and the shadow Hamiltonian of symplectic algorithms for a bound system of a simple harmonic oscillator as a specific example. The phase space trajectory moves on the hyperplane of a constant shadow Hamiltonian. We find a stationary condition for the time step τ n with which the motion repeats itself on the phase space with a period n. Interestingly, that the time steps satisfying the stationary condition turn out to be independent of the symplectic algorithms chosen. Furthermore, the phase volume enclosed by the phase trajectory is given by n τ n Ẽ n , where Ẽ n is the initial shadow energy of the corresponding symplectic algorithm.

  5. Improving Leadership and Management Practices: One Step at a Time

    ERIC Educational Resources Information Center

    Bella, Jill

    2008-01-01

    Taking small steps toward change is a sensible way to improve the leadership and management practices in an early care and education program. A director must be able to make continuous improvements without alienating staff by asking them to make drastic changes that seem overwhelming and unachievable. Taking on change one step at a time is a way…

  6. Accuracy-based time step criteria for solving parabolic equations

    SciTech Connect

    Mohtar, R.; Segerlind, L.

    1995-12-31

    Parabolic equations govern many transient engineering problems. Space integration using finite element or finite difference methods changes the parabolic partial differential equation into an ordinary differential equation. Time integration schemes are needed to solve the later equation. In order to accurately perform the later integration a proper time step must be provided. Time step estimates based on a stability criteria have been prescribed in the literature. The following paper presents time step estimates that satisfy stability as well as accuracy criteria. These estimates were correlated to the Froude and Courant Numbers. The later criteria were found to be overly conservative for some integration schemes. Suggestions as to which time integration scheme is the best to use are also presented.

  7. IMPROVEMENTS TO THE TIME STEPPING ALGORITHM OF RELAP5-3D

    SciTech Connect

    Cumberland, R.; Mesina, G.

    2009-01-01

    The RELAP5-3D time step method is used to perform thermo-hydraulic and neutronic simulations of nuclear reactors and other devices. It discretizes time and space by numerically solving several differential equations. Previously, time step size was controlled by halving or doubling the size of a previous time step. This process caused the code to run slower than it potentially could. In this research project, the RELAP5-3D time step method was modifi ed to allow a new method of changing time steps to improve execution speed and to control error. The new RELAP5-3D time step method being studied involves making the time step proportional to the material courant limit (MCL), while insuring that the time step does not increase by more than a factor of two between advancements. As before, if a step fails or mass error is excessive, the time step is cut in half. To examine performance of the new method, a measure of run time and a measure of error were plotted against a changing MCL proportionality constant (m) in seven test cases. The removal of the upper time step limit produced a small increase in error, but a large decrease in execution time. The best value of m was found to be 0.9. The new algorithm is capable of producing a signifi cant increase in execution speed, with a relatively small increase in mass error. The improvements made are now under consideration for inclusion as a special option in the RELAP5-3D production code.

  8. 40 CFR 97.41 - Timing requirements for NOX allowance allocations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Timing requirements for NOX allowance... PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS NOX Allowance Allocations § 97.41 Timing requirements for NOX allowance allocations. (a) The NOX allowance...

  9. 40 CFR 97.41 - Timing requirements for NOX allowance allocations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Timing requirements for NOX allowance... PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS NOX Allowance Allocations § 97.41 Timing requirements for NOX allowance allocations. (a) The NOX allowance...

  10. Sensitivity of a thermodynamic sea ice model with leads to time step size

    NASA Technical Reports Server (NTRS)

    Ledley, T. S.

    1985-01-01

    The characteristics of sea ice models, developed to study the physics of the growth and melt of ice at the ocean surface and the variations in ice extent, depend on the size of the time step. Thus, to study longer-term variations within a reasonable computer budget, a model with a scheme allowing longer time steps has been constructed. However, the results produced by the model can definitely depend on the length of the time step. The sensitivity of a model to time-step size can be reduced by appropriate approaches. The present investigation is concerned with experiments which use a formulation of a lead parameterization that can be considered as a first step toward the development of a lead parameterization suitable for a use in long-term climate studies.

  11. 40 CFR 96.41 - Timing requirements for NOX allowance allocations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Timing requirements for NOX allowance... PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS NOX Allowance Allocations § 96.41 Timing requirements for NOX allowance allocations. (a)...

  12. 40 CFR 96.41 - Timing requirements for NOX allowance allocations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Timing requirements for NOX allowance... PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS NOX Allowance Allocations § 96.41 Timing requirements for NOX allowance allocations. (a)...

  13. Short-term Time Step Convergence in a Climate Model

    SciTech Connect

    Wan, Hui; Rasch, Philip J.; Taylor, Mark; Jablonowski, Christiane

    2015-02-11

    A testing procedure is designed to assess the convergence property of a global climate model with respect to time step size, based on evaluation of the root-mean-square temperature difference at the end of very short (1 h) simulations with time step sizes ranging from 1 s to 1800 s. A set of validation tests conducted without sub-grid scale parameterizations confirmed that the method was able to correctly assess the convergence rate of the dynamical core under various configurations. The testing procedure was then applied to the full model, and revealed a slow convergence of order 0.4 in contrast to the expected first-order convergence. Sensitivity experiments showed without ambiguity that the time stepping errors in the model were dominated by those from the stratiform cloud parameterizations, in particular the cloud microphysics. This provides a clear guidance for future work on the design of more accurate numerical methods for time stepping and process coupling in the model.

  14. Short-term Time Step Convergence in a Climate Model

    DOE PAGESBeta

    Wan, Hui; Rasch, Philip J.; Taylor, Mark; Jablonowski, Christiane

    2015-02-11

    A testing procedure is designed to assess the convergence property of a global climate model with respect to time step size, based on evaluation of the root-mean-square temperature difference at the end of very short (1 h) simulations with time step sizes ranging from 1 s to 1800 s. A set of validation tests conducted without sub-grid scale parameterizations confirmed that the method was able to correctly assess the convergence rate of the dynamical core under various configurations. The testing procedure was then applied to the full model, and revealed a slow convergence of order 0.4 in contrast to themore » expected first-order convergence. Sensitivity experiments showed without ambiguity that the time stepping errors in the model were dominated by those from the stratiform cloud parameterizations, in particular the cloud microphysics. This provides a clear guidance for future work on the design of more accurate numerical methods for time stepping and process coupling in the model.« less

  15. Accuracy of Pedometer Steps and Time for Youth with Disabilities

    ERIC Educational Resources Information Center

    Beets, Michael W.; Combs, Cindy; Pitetti, Kenneth H.; Morgan, Melinda; Bryan, Rebecca R.; Foley, John T.

    2007-01-01

    The purpose of the study was to examine the accuracy of pedometer steps and activity time (Walk4Life, WL) for youth with developmental disabilities. Eighteen youth (11 girls, 7 boys) 4-14 years completed six 80-meter self-paced walking trials while wearing a pedometer at five waist locations (front right, front left, back right, back left, middle…

  16. Modified Chebyshev pseudospectral method with O(N exp -1) time step restriction

    NASA Technical Reports Server (NTRS)

    Kosloff, Dan; Tal-Ezer, Hillel

    1989-01-01

    The extreme eigenvalues of the Chebyshev pseudospectral differentiation operator are O(N exp 2) where N is the number of grid points. As a result of this, the allowable time step in an explicit time marching algorithm is O(N exp -2) which, in many cases, is much below the time step dictated by the physics of the partial differential equation. A new set of interpolating points is introduced such that the eigenvalues of the differentiation operator are O(N) and the allowable time step is O(N exp -1). The properties of the new algorithm are similar to those of the Fourier method. The new algorithm also provides a highly accurate solution for non-periodic boundary value problems.

  17. 40 CFR 96.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Season allowance allocations. 96.341 Section 96.341 Protection of Environment ENVIRONMENTAL PROTECTION... PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) By October 31, 2006, the permitting...

  18. 40 CFR 97.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Season allowance allocations. 97.341 Section 97.341 Protection of Environment ENVIRONMENTAL PROTECTION... TRADING PROGRAMS CAIR NOX Ozone Season Allowance Allocations § 97.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) The Administrator will determine by order the CAIR NOX...

  19. 40 CFR 97.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Season allowance allocations. 97.341 Section 97.341 Protection of Environment ENVIRONMENTAL PROTECTION... TRADING PROGRAMS CAIR NOX Ozone Season Allowance Allocations § 97.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) The Administrator will determine by order the CAIR NOX...

  20. 40 CFR 96.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Season allowance allocations. 96.341 Section 96.341 Protection of Environment ENVIRONMENTAL PROTECTION... PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) By October 31, 2006, the permitting...

  1. 40 CFR 97.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Season allowance allocations. 97.341 Section 97.341 Protection of Environment ENVIRONMENTAL PROTECTION... TRADING PROGRAMS CAIR NOX Ozone Season Allowance Allocations § 97.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) The Administrator will determine by order the CAIR NOX...

  2. 40 CFR 96.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Season allowance allocations. 96.341 Section 96.341 Protection of Environment ENVIRONMENTAL PROTECTION... PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.341 Timing requirements for CAIR NOX Ozone Season allowance allocations. (a) By October 31, 2006, the permitting...

  3. 40 CFR 97.411 - Timing requirements for TR NOX Annual allowance allocations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Timing requirements for TR NOX Annual... TR NOX Annual Trading Program § 97.411 Timing requirements for TR NOX Annual allowance allocations. (a) Existing units. (1) TR NOX Annual allowances are allocated, for the control periods in 2012...

  4. 40 CFR 97.711 - Timing requirements for TR SO2 Group 2 allowance allocations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Timing requirements for TR SO2 Group 2... TR SO2 Group 2 Trading Program § 97.711 Timing requirements for TR SO2 Group 2 allowance allocations. (a) Existing units. (1) TR SO2 Group 2 allowances are allocated, for the control periods in 2012...

  5. 40 CFR 97.711 - Timing requirements for TR SO2 Group 2 allowance allocations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Timing requirements for TR SO2 Group 2... TR SO2 Group 2 Trading Program § 97.711 Timing requirements for TR SO2 Group 2 allowance allocations. (a) Existing units. (1) TR SO2 Group 2 allowances are allocated, for the control periods in 2012...

  6. 40 CFR 97.611 - Timing requirements for TR SO2 Group 1 allowance allocations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Timing requirements for TR SO2 Group 1... TR SO2 Group 1 Trading Program § 97.611 Timing requirements for TR SO2 Group 1 allowance allocations. (a) Existing units. (1) TR SO2 Group 1 allowances are allocated, for the control periods in 2012...

  7. 40 CFR 97.511 - Timing requirements for TR NOX Ozone Season allowance allocations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Timing requirements for TR NOX Ozone... TRADING PROGRAMS TR NOX Ozone Season Trading Program § 97.511 Timing requirements for TR NOX Ozone Season allowance allocations. (a) Existing units. (1) TR NOX Ozone Season allowances are allocated, for the...

  8. 40 CFR 97.511 - Timing requirements for TR NOX Ozone Season allowance allocations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Timing requirements for TR NOX Ozone... TRADING PROGRAMS TR NOX Ozone Season Trading Program § 97.511 Timing requirements for TR NOX Ozone Season allowance allocations. (a) Existing units. (1) TR NOX Ozone Season allowances are allocated, for the...

  9. 40 CFR 97.611 - Timing requirements for TR SO2 Group 1 allowance allocations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Timing requirements for TR SO2 Group 1... TR SO2 Group 1 Trading Program § 97.611 Timing requirements for TR SO2 Group 1 allowance allocations. (a) Existing units. (1) TR SO2 Group 1 allowances are allocated, for the control periods in 2012...

  10. 40 CFR 97.411 - Timing requirements for TR NOX Annual allowance allocations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Timing requirements for TR NOX Annual... TR NOX Annual Trading Program § 97.411 Timing requirements for TR NOX Annual allowance allocations. (a) Existing units. (1) TR NOX Annual allowances are allocated, for the control periods in 2012...

  11. 40 CFR 97.411 - Timing requirements for TR NOX Annual allowance allocations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Timing requirements for TR NOX Annual... TR NOX Annual Trading Program § 97.411 Timing requirements for TR NOX Annual allowance allocations. (a) Existing units. (1) TR NOX Annual allowances are allocated, for the control periods in 2012...

  12. 40 CFR 97.511 - Timing requirements for TR NOX Ozone Season allowance allocations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Timing requirements for TR NOX Ozone... TRADING PROGRAMS TR NOX Ozone Season Trading Program § 97.511 Timing requirements for TR NOX Ozone Season allowance allocations. (a) Existing units. (1) TR NOX Ozone Season allowances are allocated, for the...

  13. 40 CFR 97.711 - Timing requirements for TR SO2 Group 2 allowance allocations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Timing requirements for TR SO2 Group 2... TR SO2 Group 2 Trading Program § 97.711 Timing requirements for TR SO2 Group 2 allowance allocations. (a) Existing units. (1) TR SO2 Group 2 allowances are allocated, for the control periods in 2012...

  14. 40 CFR 97.611 - Timing requirements for TR SO2 Group 1 allowance allocations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Timing requirements for TR SO2 Group 1... TR SO2 Group 1 Trading Program § 97.611 Timing requirements for TR SO2 Group 1 allowance allocations. (a) Existing units. (1) TR SO2 Group 1 allowances are allocated, for the control periods in 2012...

  15. 40 CFR 97.141 - Timing requirements for CAIR NOX allowance allocations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Timing requirements for CAIR NOX... (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS CAIR NOX Allowance Allocations § 97.141 Timing requirements for CAIR NOX allowance allocations. (a)...

  16. 40 CFR 97.141 - Timing requirements for CAIR NOX allowance allocations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Timing requirements for CAIR NOX... (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS CAIR NOX Allowance Allocations § 97.141 Timing requirements for CAIR NOX allowance allocations. (a)...

  17. A method for improving time-stepping numerics

    NASA Astrophysics Data System (ADS)

    Williams, P. D.

    2012-04-01

    In contemporary numerical simulations of the atmosphere, evidence suggests that time-stepping errors may be a significant component of total model error, on both weather and climate time-scales. This presentation will review the available evidence, and will then suggest a simple but effective method for substantially improving the time-stepping numerics at no extra computational expense. The most common time-stepping method is the leapfrog scheme combined with the Robert-Asselin (RA) filter. This method is used in the following atmospheric models (and many more): ECHAM, MAECHAM, MM5, CAM, MESO-NH, HIRLAM, KMCM, LIMA, SPEEDY, IGCM, PUMA, COSMO, FSU-GSM, FSU-NRSM, NCEP-GFS, NCEP-RSM, NSEAM, NOGAPS, RAMS, and CCSR/NIES-AGCM. Although the RA filter controls the time-splitting instability in these models, it also introduces non-physical damping and reduces the accuracy. This presentation proposes a simple modification to the RA filter. The modification has become known as the RAW filter (Williams 2011). When used in conjunction with the leapfrog scheme, the RAW filter eliminates the non-physical damping and increases the amplitude accuracy by two orders, yielding third-order accuracy. (The phase accuracy remains second-order.) The RAW filter can easily be incorporated into existing models, typically via the insertion of just a single line of code. Better simulations are obtained at no extra computational expense. Results will be shown from recent implementations of the RAW filter in various atmospheric models, including SPEEDY and COSMO. For example, in SPEEDY, the skill of weather forecasts is found to be significantly improved. In particular, in tropical surface pressure predictions, five-day forecasts made using the RAW filter have approximately the same skill as four-day forecasts made using the RA filter (Amezcua, Kalnay & Williams 2011). These improvements are encouraging for the use of the RAW filter in other models.

  18. Accurate Monotonicity - Preserving Schemes With Runge-Kutta Time Stepping

    NASA Technical Reports Server (NTRS)

    Suresh, A.; Huynh, H. T.

    1997-01-01

    A new class of high-order monotonicity-preserving schemes for the numerical solution of conservation laws is presented. The interface value in these schemes is obtained by limiting a higher-order polynominal reconstruction. The limiting is designed to preserve accuracy near extrema and to work well with Runge-Kutta time stepping. Computational efficiency is enhanced by a simple test that determines whether the limiting procedure is needed. For linear advection in one dimension, these schemes are shown as well as the Euler equations also confirm their high accuracy, good shock resolution, and computational efficiency.

  19. 30 CFR 203.66 - What happens if MMS does not act in the time allowed?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Expansion Projects § 203.66 What happens if MMS does not act in the time allowed? If we do not act within.... (b) An expansion project You get a royalty suspension for the first year of production Abide...

  20. Enabling fast, stable and accurate peridynamic computations using multi-time-step integration

    DOE PAGESBeta

    Lindsay, P.; Parks, M. L.; Prakash, A.

    2016-04-13

    Peridynamics is a nonlocal extension of classical continuum mechanics that is well-suited for solving problems with discontinuities such as cracks. This paper extends the peridynamic formulation to decompose a problem domain into a number of smaller overlapping subdomains and to enable the use of different time steps in different subdomains. This approach allows regions of interest to be isolated and solved at a small time step for increased accuracy while the rest of the problem domain can be solved at a larger time step for greater computational efficiency. Lastly, performance of the proposed method in terms of stability, accuracy, andmore » computational cost is examined and several numerical examples are presented to corroborate the findings.« less

  1. 40 CFR 96.141 - Timing requirements for CAIR NOX allowance allocations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Timing requirements for CAIR NOX... (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Allowance Allocations § 96.141 Timing requirements for CAIR...

  2. 40 CFR 96.141 - Timing requirements for CAIR NOX allowance allocations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Timing requirements for CAIR NOX... (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Allowance Allocations § 96.141 Timing requirements for CAIR...

  3. 40 CFR 97.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Timing requirements for CAIR NOX Ozone... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS CAIR NOX Ozone Season Allowance Allocations § 97.341 Timing requirements for CAIR...

  4. 40 CFR 97.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Timing requirements for CAIR NOX Ozone... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS CAIR NOX Ozone Season Allowance Allocations § 97.341 Timing requirements for CAIR...

  5. Viral DNA Packaging: One Step at a Time

    NASA Astrophysics Data System (ADS)

    Bustamante, Carlos; Moffitt, Jeffrey R.

    During its life-cycle the bacteriophage φ29 actively packages its dsDNA genome into a proteinacious capsid, compressing its genome to near crystalline densities against large electrostatic, elastic, and entropic forces. This remarkable process is accomplished by a nano-scale, molecular DNA pump - a complex assembly of three protein and nucleic acid rings which utilizes the free energy released in ATP hydrolysis to perform the mechanical work necessary to overcome these large energetic barriers. We have developed a single molecule optical tweezers assay which has allowed us to probe the detailed mechanism of this packaging motor. By following the rate of packaging of a single bacteriophage as the capsid is filled with genome and as a function of optically applied load, we find that the compression of the genome results in the build-up of an internal force, on the order of ˜ 55 pN, due to the compressed genome. The ability to work against such large forces makes the packaging motor one of the strongest known molecular motors. By titrating the concentration of ATP, ADP, and inorganic phosphate at different opposing load, we are able to determine features of the mechanochemistry of this motor - the coupling between the mechanical and chemical cycles. We find that force is generated not upon binding of ATP, but rather upon release of hydrolysis products. Finally, by improving the resolution of the optical tweezers assay, we are able to observe the discrete increments of DNA encapsidated each cycle of the packaging motor. We find that DNA is packaged in 10-bp increments preceded by the binding of multiple ATPs. The application of large external forces slows the packaging rate of the motor, revealing that the 10-bp steps are actually composed of four 2.5-bp steps which occur in rapid succession. These data show that the individual subunits of the pentameric ring-ATPase at the core of the packaging motor are highly coordinated, with the binding of ATP and the

  6. Accelerating spectral-element simulations of seismic wave propagation using local time stepping

    NASA Astrophysics Data System (ADS)

    Peter, D. B.; Rietmann, M.; Galvez, P.; Nissen-Meyer, T.; Grote, M.; Schenk, O.

    2013-12-01

    Seismic tomography using full-waveform inversion requires accurate simulations of seismic wave propagation in complex 3D media. However, finite element meshing in complex media often leads to areas of local refinement, generating small elements that accurately capture e.g. strong topography and/or low-velocity sediment basins. For explicit time schemes, this dramatically reduces the global time-step for wave-propagation problems due to numerical stability conditions, ultimately making seismic inversions prohibitively expensive. To alleviate this problem, local time stepping (LTS) algorithms allow an explicit time-stepping scheme to adapt the time-step to the element size, allowing near-optimal time-steps everywhere in the mesh. Numerical simulations are thus liberated of global time-step constraints potentially speeding up simulation runtimes significantly. We present here a new, efficient multi-level LTS-Newmark scheme for general use with spectral-element methods (SEM) with applications in seismic wave propagation. We fit the implementation of our scheme onto the package SPECFEM3D_Cartesian, which is a widely used community code, simulating seismic and acoustic wave propagation in earth-science applications. Our new LTS scheme extends the 2nd-order accurate Newmark time-stepping scheme, and leads to an efficient implementation, producing real-world speedup of multi-resolution seismic applications. Furthermore, we generalize the method to utilize many refinement levels with a design specifically for continuous finite elements. We demonstrate performance speedup using a state-of-the-art dynamic earthquake rupture model for the Tohoku-Oki event, which is currently limited by small elements along the rupture fault. Utilizing our new algorithmic LTS implementation together with advances in exploiting graphic processing units (GPUs), numerical seismic wave propagation simulations in complex media will dramatically reduce computation times, empowering high

  7. 40 CFR 96.141 - Timing requirements for CAIR NOX allowance allocations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Timing requirements for CAIR NOX... allowance allocations. (a) By October 31, 2006, the permitting authority will submit to the Administrator... § 96.142(a) and (b), for the control periods in 2009, 2010, 2011, 2012, 2013, and 2014. (b) By...

  8. 40 CFR 96.141 - Timing requirements for CAIR NOX allowance allocations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Timing requirements for CAIR NOX... allowance allocations. (a) By October 31, 2006, the permitting authority will submit to the Administrator... § 96.142(a) and (b), for the control periods in 2009, 2010, 2011, 2012, 2013, and 2014. (b) By...

  9. 40 CFR 60.4141 - Timing requirements for Hg allowance allocations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Timing requirements for Hg allowance... accordance with § 60.4142(a) and (b), for the control periods in 2010, 2011, 2012, 2013, and 2014. (b)(1) By October 31, 2008 and October 31 of each year thereafter, the permitting authority will submit to...

  10. 40 CFR 60.4141 - Timing requirements for Hg allowance allocations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 6 2011-07-01 2011-07-01 false Timing requirements for Hg allowance... accordance with § 60.4142(a) and (b), for the control periods in 2010, 2011, 2012, 2013, and 2014. (b)(1) By October 31, 2008 and October 31 of each year thereafter, the permitting authority will submit to...

  11. 40 CFR 96.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Timing requirements for CAIR NOX Ozone... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.341...

  12. 40 CFR 96.341 - Timing requirements for CAIR NOX Ozone Season allowance allocations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Timing requirements for CAIR NOX Ozone... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS FOR STATE IMPLEMENTATION PLANS CAIR NOX Ozone Season Allowance Allocations § 96.341...

  13. Rules Allowing Extended Time on Graduation: Advocates Debate Effects of Change in Regulations

    ERIC Educational Resources Information Center

    Gewertz, Catherine

    2009-01-01

    Federal regulations have opened a door that allows schools to get credit under the No Child Left Behind Act for students who take longer than four years to earn a high school diploma. That option worries some education advocates, who fear it could relieve valuable pressure on high schools to graduate students on time. Under the law's…

  14. A Monolithic Multi-Time-Step Computational Framework for Transient Advective-Diffusive-Reactive Systems

    NASA Astrophysics Data System (ADS)

    Karimi, S.; Nakshatrala, K. B.

    2014-12-01

    Advection-Diffusion-Reaction (ADR) equations play a crucial role in simulating numerous geo- physical phenomena. It is well-known that the solution to these equations exhibit disparate spatial and temporal scales. These mathematical scales occur due to relative dominance of either advec- tion, diffusion, or reaction processes. Hence, in a careful simulation, one has to choose appropriate time-integrators, time-steps, and numerical formulations for spatial discretization. Multi-time-step coupling methods allow specific choice of integration methods (either temporal or spatial) in dif- ferent regions of the spatial domain. In recent years, most of the attempts to design monolithic multi-time-step frameworks favored second-order transient systems in structural dynamics. In this presentation, we will introduce monolithic multi-time-step computational frameworks for ADR equations. These methods are based on the theory of differential/algebraic equations. We shall also provide an overview of results from stability analysis, study of drift from compatibility con- straints, and analysis of influence of perturbations. Several benchmark problems will be utilized to demonstrate the theoretical findings and features of the proposed frameworks. Finally, application of the proposed methods to fast bimolecular reactive systems will be shown.

  15. A new time-stepping method for regional climate models

    NASA Astrophysics Data System (ADS)

    Williams, P. D.

    2010-12-01

    The dynamical cores of many regional climate models use the Robert-Asselin filter to suppress the spurious computational mode of the leapfrog scheme. Unfortunately, whilst successfully eliminating the unwanted mode, the Robert-Asselin filter also weakly suppresses the physical solution and degrades the numerical accuracy. These two concomitant problems occur because the filter does not conserve the mean state, averaged over the three time slices on which it operates. This presentation proposes a simple modification to the Robert-Asselin filter, which does conserve the three-time-level mean state. When used in conjunction with the leapfrog scheme, the modification vastly reduces the artificial damping of the physical solution. Correspondingly, the modification increases the numerical accuracy for amplitude errors by two orders, yielding third-order accuracy. The modified filter may easily be incorporated into existing regional climate models, via the addition of only a few lines of code that are computationally very inexpensive. Results will be shown from recent implementations of the modified filter in various models. The modification will be shown to reduce model biases and to significantly improve the predictive skill. Magnitude of the complex amplification factor as a function of the non-dimensional time step, for leapfrog integrations. This quantity would be identical to 1 for a perfect numerical scheme. Clearly, the filter proposed here (case α=0.53) has much smaller numerical errors than the original Robert-Asselin filter (case α=1). Moreover, the proposed filter is trivial to implement and is no more computationally expensive. Taken from Williams (2009; Monthly Weather Review).

  16. Watching Proteins Direct Crystal Growth One Step at a Time

    SciTech Connect

    2009-01-01

    Researchers at Berkeley Labs Molecular Foundry use an atomic force microscope to record this movie of a peptide being adsorbed to a crystal surface while two successive crystal steps interact, then progress beyond the peptide. The peptide temporarily slows the step before transferring up to the next atomic layer. The lattice pattern on the surface corresponds to the molecular structure of the underlying crystal.

  17. The USMLE Step 2 CS: Time for a change.

    PubMed

    Alvin, Matthew D

    2016-08-01

    The United States Medical Licensing Examination (USMLE(®)) Steps are a series of mandatory licensing assessments for all allopathic (MD degree) medical students in their transition from student to intern to resident physician. Steps 1, 2 Clinical Knowledge (CK), and 3 are daylong multiple-choice exams that quantify a medical student's basic science and clinical knowledge as well as their application of that knowledge using a three-digit score. In doing so, these Steps provide a standardized assessment that residency programs use to differentiate applicants and evaluate their competitiveness. Step 2 Clinical Skills (CS), the only other Step exam and the second component of Step 2, was created in 2004 to test clinical reasoning and patient-centered skills. As a Pass/Fail exam without a numerical scoring component, Step 2 CS provides minimal differentiation among applicants for residency programs. In this personal view article, it is argued that the current Step 2 CS exam should be eliminated for US medical students and propose an alternative consistent with the mission and purpose of the exam that imposes less of a burden on medical students. PMID:27007882

  18. Constrained Density Functional Theory by Imaginary Time-Step Method

    NASA Astrophysics Data System (ADS)

    Kidd, Daniel

    Constrained Density Functional Theory (CDFT) has been a popular choice within the last decade for sidestepping the self interaction problem within long-range charge transfer calculations. Typically an inner constraint loop is added within the self-consistent field iterations of DFT in order to enforce this charge transfer state by means of a Lagrange multiplier method. In this work, an alternate implementation of CDFT is introduced, that of the imaginary time-step method, which lends itself more readily to real space calculations in the ability to solve numerically for 3D local external potentials which enforce arbitrary given densities. This method has been shown to reproduce the proper 1 / R dependence of charge transfer systems in real space calculations as well as the ability to generate useful constraint potentials. As an example application, this method is shown to be capable of describing defects within periodic systems using finite calculations by constraining the 3D density to that of the periodically calculated perfect system at the boundaries.

  19. DNA walks one step at a time in electrophoresis

    NASA Astrophysics Data System (ADS)

    Guan, Juan; Wang, Bo; Granick, Steve

    2011-03-01

    Testing the classical view that in DNA gel electrophoresis, long polymer chains navigate through their gel environment via reptation, we reach a different conclusion: this driven motion proceeds by stick-slip. Our single-molecule experiments visualize fluorescent-labeled lambda-DNA, whose intramolecular conformations are resolved with 30 ms resolution using home-written software. Combining hundreds to thousands of trajectories under amplitudes of electric field ranging from zero to large, we quantify the full statistical distribution of motion with unprecedented statistics. Pauses are seen between steps of driven motion, probably reflecting that the chain is trapped inside the gel matrix. The pausing time is exponentially distributed and decreases with increasing electric field strength, suggesting that the jerky behavior is an activated process, facilitated by electric field. We propose a stretch-assisted mechanism: that the energy barrier to move through the gel environment is first overcome by a leading segment, the ensuing intramolecular stress from stretching causing lagging segments to recoil and follow along.

  20. Wooden hutch space allowance influences male Holstein calf health, performance, daily lying time, and respiratory immunity.

    PubMed

    Calvo-Lorenzo, M S; Hulbert, L E; Fowler, A L; Louie, A; Gershwin, L J; Pinkerton, K E; Ballou, M A; Klasing, K C; Mitloehner, F M

    2016-06-01

    Dairy calves in the western United States are commonly raised individually in wooden hutches with a space allowance of 1.23m(2)/calf. Recent legislative initiatives in California and across the United States were passed regarding concern over space allowance for farm animals. The objective of this study was to determine if rearing male Holstein calves in wooden hutches modified to increase space allowance would influence measures of performance, lying time per day, health, and respiratory immunocompetence. At 4d of age, 60 calves were randomly assigned to 1 of 3housing treatments: (1) conventional housing (CONV; 1.23m(2)/calf), (2) 1.5 × CONV (MOD; 1.85m(2)/calf), or (3) 3 × CONV (MAX; 3.71m(2)/calf). Intakes of milk and solid feed were recorded daily and body weight was measured at 0, 3, 6, 10, and 12 wk of age. For the first 3 wk of the trial, calves were scored daily for fecal consistency, hydration, and hide cleanliness. In addition, calves were scored for respiratory health (i.e., nasal and eye discharge, ear position) until 7 wk of age. The total lying duration per day was recorded using data loggers at 3, 6, and 10 wk of age. Eight clinically healthy calves from each treatment were sensitized with subcutaneous ovalbumin (OVA) and then challenged with aerosolized OVA to assess calf respiratory immunity at 11 wk of age. Bronchoalveolar lavage fluid (BALF) was collected 4d after the OVA challenge and analyzed for leukocyte differentials and OVA-specific IgG, IgG1, IgA, and IgE. Calf average daily gain and body weight were positively associated with space allowance at approximately 3 wk before weaning and throughout postweaning, respectively. A greater space allowance decreased lying time after 46d. Space allowance did not influence fecal consistency, but there was a tendency for MAX calves to take 1d longer to recover from loose feces than MOD calves. The MAX calves had the fewest (%) observations with feces on their body compared with CONV or MOD. At 3 wk of

  1. Two-stepping through time: mammals and viruses.

    PubMed

    Meyerson, Nicholas R; Sawyer, Sara L

    2011-06-01

    Recent studies have identified ancient virus genomes preserved as fossils within diverse animal genomes. These fossils have led to the revelation that a broad range of mammalian virus families are older and more ubiquitous than previously appreciated. Long-term interactions between viruses and their hosts often develop into genetic arms races where both parties continually jockey for evolutionary dominance. It is difficult to imagine how mammalian hosts have kept pace in the evolutionary race against rapidly evolving viruses over large expanses of time, given their much slower evolutionary rates. However, recent data has begun to reveal the evolutionary strategy of slowly-evolving hosts. We review these data and suggest a modified arms race model where the evolutionary possibilities of viruses are relatively constrained. Such a model could allow more accurate forecasting of virus evolution. PMID:21531564

  2. Unconditionally stable split-step finite difference time domain formulations for double-dispersive electromagnetic materials

    NASA Astrophysics Data System (ADS)

    Ramadan, Omar

    2014-12-01

    Systematic split-step finite difference time domain (SS-FDTD) formulations, based on the general Lie-Trotter-Suzuki product formula, are presented for solving the time-dependent Maxwell equations in double-dispersive electromagnetic materials. The proposed formulations provide a unified tool for constructing a family of unconditionally stable algorithms such as the first order split-step FDTD (SS1-FDTD), the second order split-step FDTD (SS2-FDTD), and the second order alternating direction implicit FDTD (ADI-FDTD) schemes. The theoretical stability of the formulations is included and it has been demonstrated that the formulations are unconditionally stable by construction. Furthermore, the dispersion relation of the formulations is derived and it has been found that the proposed formulations are best suited for those applications where a high space resolution is needed. Two-dimensional (2-D) and 3-D numerical examples are included and it has been observed that the SS1-FDTD scheme is computationally more efficient than the ADI-FDTD counterpart, while maintaining approximately the same numerical accuracy. Moreover, the SS2-FDTD scheme allows using larger time step than the SS1-FDTD or ADI-FDTD and therefore necessitates less CPU time, while giving approximately the same numerical accuracy.

  3. Spot Variation Fluorescence Correlation Spectroscopy Allows for Superresolution Chronoscopy of Confinement Times in Membranes

    PubMed Central

    Ruprecht, Verena; Wieser, Stefan; Marguet, Didier; Schütz, Gerhard J.

    2011-01-01

    Resolving the dynamical interplay of proteins and lipids in the live-cell plasma membrane represents a central goal in current cell biology. Superresolution concepts have introduced a means of capturing spatial heterogeneity at a nanoscopic length scale. Similar concepts for detecting dynamical transitions (superresolution chronoscopy) are still lacking. Here, we show that recently introduced spot-variation fluorescence correlation spectroscopy allows for sensing transient confinement times of membrane constituents at dramatically improved resolution. Using standard diffraction-limited optics, spot-variation fluorescence correlation spectroscopy captures signatures of single retardation events far below the transit time of the tracer through the focal spot. We provide an analytical description of special cases of transient binding of a tracer to pointlike traps, or association of a tracer with nanodomains. The influence of trap mobility and the underlying binding kinetics are quantified. Experimental approaches are suggested that allow for gaining quantitative mechanistic insights into the interaction processes of membrane constituents. PMID:21641330

  4. Error correction in short time steps during the application of quantum gates

    NASA Astrophysics Data System (ADS)

    de Castro, L. A.; Napolitano, R. d. J.

    2016-04-01

    We propose a modification of the standard quantum error-correction method to enable the correction of errors that occur due to the interaction with a noisy environment during quantum gates without modifying the codification used for memory qubits. Using a perturbation treatment of the noise that allows us to separate it from the ideal evolution of the quantum gate, we demonstrate that in certain cases it is necessary to divide the logical operation in short time steps intercalated by correction procedures. A prescription of how these gates can be constructed is provided, as well as a proof that, even for the cases when the division of the quantum gate in short time steps is not necessary, this method may be advantageous for reducing the total duration of the computation.

  5. The Semi-implicit Time-stepping Algorithm in MH4D

    NASA Astrophysics Data System (ADS)

    Vadlamani, Srinath; Shumlak, Uri; Marklin, George; Meier, Eric; Lionello, Roberto

    2006-10-01

    The Plasma Science and Innovation Center (PSI Center) at the University of Washington is developing MHD codes to accurately model Emerging Concept (EC) devices. Examination of the semi-implicit time stepping algorithm implemented in the tetrahedral mesh MHD simulation code, MH4D, is presented. The time steps for standard explicit methods, which are constrained by the Courant-Friedrichs-Lewy (CFL) condition, are typically small for simulations of EC experiments due to the large Alfven speed. The CFL constraint is more severe with a tetrahedral mesh because of the irregular cell geometry. The semi-implicit algorithm [1] removes the fast waves constraint, thus allowing for larger time steps. We will present the implementation method of this algorithm, and numerical results for test problems in simple geometry. Also, we will present the effectiveness in simulations of complex geometry, similar to the ZaP [2] experiment at the University of Washington. References: [1]Douglas S. Harned and D. D. Schnack, Semi-implicit method for long time scale magnetohy drodynamic computations in three dimensions, JCP, Volume 65, Issue 1, July 1986, Pages 57-70. [2]U. Shumlak, B. A. Nelson, R. P. Golingo, S. L. Jackson, E. A. Crawford, and D. J. Den Hartog, Sheared flow stabilization experiments in the ZaP flow Zpinch, Phys. Plasmas 10, 1683 (2003).

  6. Automatic multirate methods for ordinary differential equations. [Adaptive time steps

    SciTech Connect

    Gear, C.W.

    1980-01-01

    A study is made of the application of integration methods in which different step sizes are used for different members of a system of equations. Such methods can result in savings if the cost of derivative evaluation is high or if a system is sparse; however, the estimation and control of errors is very difficult and can lead to high overheads. Three approaches are discussed, and it is shown that the least intuitive is the most promising. 2 figures.

  7. Risk-based evaluation of Allowed Outage Times (AOTs) considering risk of shutdown

    SciTech Connect

    Mankamo, T.; Kim, I.S.; Samanta, P.K.

    1992-12-31

    When safety systems fail during power operation, Technical Specifications (TS) usually limit the repair within Allowed Outage Time (AOT). If the repair cannot be completed within the AOT, or no AOT is allowed, the plant is required to be shut down for the repair. However, if the capability to remove decay heat is degraded, shutting down the plant with the need to operate the affected decay-heat removal systems may impose a substantial risk compared to continued power operation over a usual repair time. Thus, defining a proper AOT in such situations can be considered as a risk-comparison between the repair in frill power state with a temporarily increased level of risk, and the altemative of shutting down the plant for the repair in zero power state with a specific associated risk. The methodology of the risk-comparison approach, with a due consideration of the shutdown risk, has been further developed and applied to the AOT considerations of residual heat removal and standby service water systems of a boiling water reactor (BWR) plant. Based on the completed work, several improvements to the TS requirements for the systems studied can be suggested.

  8. Risk-based evaluation of Allowed Outage Times (AOTs) considering risk of shutdown

    SciTech Connect

    Mankamo, T. ); Kim, I.S.; Samanta, P.K. )

    1992-01-01

    When safety systems fail during power operation, Technical Specifications (TS) usually limit the repair within Allowed Outage Time (AOT). If the repair cannot be completed within the AOT, or no AOT is allowed, the plant is required to be shut down for the repair. However, if the capability to remove decay heat is degraded, shutting down the plant with the need to operate the affected decay-heat removal systems may impose a substantial risk compared to continued power operation over a usual repair time. Thus, defining a proper AOT in such situations can be considered as a risk-comparison between the repair in frill power state with a temporarily increased level of risk, and the altemative of shutting down the plant for the repair in zero power state with a specific associated risk. The methodology of the risk-comparison approach, with a due consideration of the shutdown risk, has been further developed and applied to the AOT considerations of residual heat removal and standby service water systems of a boiling water reactor (BWR) plant. Based on the completed work, several improvements to the TS requirements for the systems studied can be suggested.

  9. The prevalence of upright non-stepping time in comparison to stepping time in 11-13 year old school children across seasons.

    PubMed

    McCrorie, P Rw; Duncan, E; Granat, M H; Stansfield, B W

    2012-11-01

    Evidence suggests that behaviours such as standing are beneficial for our health. Unfortunately, little is known of the prevalence of this state, its importance in relation to time spent stepping or variation across seasons. The aim of this study was to quantify, in young adolescents, the prevalence and seasonal changes in time spent upright and not stepping (UNSt(time)) as well as time spent upright and stepping (USt(time)), and their contribution to overall upright time (U(time)). Thirty-three adolescents (12.2 ± 0.3 y) wore the activPAL activity monitor during four school days on two occasions: November/December (winter) and May/June (summer). UNSt(time) contributed 60% of daily U(time) at winter (Mean = 196 min) and 53% at summer (Mean = 171 min); a significant seasonal effect, p < 0.001. USt(time) was significantly greater in summer compared to winter (153 min versus 131 min, p < 0.001). The effects in UNSt(time) could be explained through significant seasonal differences during the school hours (09:00-16:00), whereas the effects in USt(time) could be explained through significant seasonal differences in the evening period (16:00-22:00). Adolescents spent a greater amount of time upright and not stepping than they did stepping, in both winter and summer. The observed seasonal effects for both UNSt(time) and USt(time) provide important information for behaviour change intervention programs. PMID:23111187

  10. One step at a time: endoplasmic reticulum-associated degradation

    PubMed Central

    Vembar, Shruthi S.; Brodsky, Jeffrey L.

    2009-01-01

    Protein folding in the endoplasmic reticulum (ER) is monitored by ER quality control (ERQC) mechanisms. Proteins that pass ERQC criteria traffic to their final destinations through the secretory pathway, whereas non-native and unassembled subunits of multimeric proteins are degraded by the ER-associated degradation (ERAD) pathway. During ERAD, molecular chaperones and associated factors recognize and target substrates for retrotranslocation to the cytoplasm, where they are degraded by the ubiquitin–proteasome machinery. The discovery of diseases that are associated with ERAD substrates highlights the importance of this pathway. Here, we summarize our current understanding of each step during ERAD, with emphasis on the factors that catalyse distinct activities. PMID:19002207

  11. Allowing time to consolidate knowledge gained through random practice facilitates later novel motor sequence acquisition.

    PubMed

    Kim, Taewon; Rhee, Joohyun; Wright, David L

    2016-01-01

    Two experiments were conducted to examine the efficacy of random (RP) and blocked practice (BP) for enhancing later motor learning. Each experiment involved practicing three unique seven key serial reaction time (SRT) tasks in either a blocked or random format followed by practice of a novel SRT task either 2-min (Experiment 1) or 24-h (Experiment 2) later. While the expected benefit of RP for retention was present in both experiments, in Experiment 1 there was no advantage from prior RP for new learning. Experiment 2 explored the possibility that increasing the interval, from 2-min to 24-h, between BP or RP and practice of the novel motor task might allow consolidation of sequence knowledge acquired during BP or RP which in turn might facilitate new learning. As a result of the additional time between training bouts RP facilitated the rate at which the novel motor task was acquired. Interestingly, when this additional time was provided, both BP and RP supported (a) a performance saving for the first trial with the novel task, and (b) an offline improvement in performance across a 24-h interval not present when only the novel motor task was practiced. The latter benefits for new learning may have resulted from exposure to prior physical practice per se. or practice variability. These data are discussed with respect to (a) future learning benefits from prior experience training with greater CI, and (b) the importance of memory consolidation for motor learning. PMID:26686835

  12. Evaluation of allowed outage times (AOTs) from a risk and reliability standpoint

    SciTech Connect

    Vesely, W.E. )

    1989-08-01

    This report describes the basic risks which are associated with allowed outage times (AOTs), defines strategies for selecting the risks to be quantified, and describes how the risks can be quantified. The report furthermore describes criteria considerations in determining the acceptability of calculated AOT risks, and discusses the merits of relative risk criteria versus absolute risk criteria. The detailed evaluations which are involved in calculating AOT risks, including uncertainty considerations are also discussed. The report also describes the proper ways that risks from multiple AOTs should be considered so that risks are properly accumulated from proposed multiple AOT changes, but are not double-counted. Generally, average AOT risks which include the frequency of occurrence of the AOT need to be accumulated but single downtime risks don't since they apply to individual AOTs. 8 refs., 22 tabs.

  13. PIC Algorithm with Multiple Poisson Equation Solves During One Time Step

    NASA Astrophysics Data System (ADS)

    Ren, Junxue; Godar, Trenton; Menart, James; Mahalingam, Sudhakar; Choi, Yongjun; Loverich, John; Stoltz, Peter H.

    2015-09-01

    In order to reduce the overall computational time of a PIC (particle-in-cell) computer simulation, an attempt was made to utilize larger time step sizes by implementing multiple solutions of Poisson's equation within one time step. The hope was this would make the PIC simulation stable at larger time steps than an explicit technique can use, and using larger time steps would reduce the overall computational time, even though the computational time per time step would increase. A three-dimensional PIC code that tracks electrons and ions throughout a three-dimensional Cartesian computational domain is used to perform this study. The results of altering the number of times Poisson's equation is solved during a single time step are presented. Also, the size of the time that can be used and still maintain a stable solution is surveyed. The results indicate that using multiple Poisson solves during one time step provides some ability to use larger time steps in PIC simulations, but the increase in time step size is not significant and the overall simulation run time is not reduced

  14. Space-time variability of floods across Germany: Gradual trends, step changes and fluctuations

    NASA Astrophysics Data System (ADS)

    Merz, Bruno; Vorogushyn, Sergiy; Viet Dung, Nguyen; Schröter, Kai

    2015-04-01

    The space-time variability of flood magnitude and frequency across Germany at the interannual and decadal time scale is analyzed and interpreted. The analyses are based on flood time series of 68 catchments for a joint period of 74 years. The catchments are distributed across Germany and show different flood regimes. Different statistical tests are applied to investigate different types of flood changes: gradual trends, step changes and fluctuations. In addition, changes in the mean behavior and in the variability are studied. A focus is placed on the spatial stability of changes, i.e. answering the question to which extent flood changes are coherent across Germany. The joint analysis of changes for a large number of catchments allows interpreting the causes of the observed changes. For instance, climate-related flood changes are expected to show a different behavior than changes caused by river training or land-use change.

  15. Empirical versus time stepping with embedded error control for density-driven flow in porous media

    NASA Astrophysics Data System (ADS)

    Younes, Anis; Ackerer, Philippe

    2010-08-01

    Modeling density-driven flow in porous media may require very long computational time due to the nonlinear coupling between flow and transport equations. Time stepping schemes are often used to adapt the time step size in order to reduce the computational cost of the simulation. In this work, the empirical time stepping scheme which adapts the time step size according to the performance of the iterative nonlinear solver is compared to an adaptive time stepping scheme where the time step length is controlled by the temporal truncation error. Results of the simulations of the Elder problem show that (1) the empirical time stepping scheme can lead to inaccurate results even with a small convergence criterion, (2) accurate results are obtained when the time step size selection is based on the truncation error control, (3) a non iterative scheme with proper time step management can be faster and leads to more accurate solution than the standard iterative procedure with the empirical time stepping and (4) the temporal truncation error can have a significant effect on the results and can be considered as one of the reasons for the differences observed in the Elder numerical results.

  16. Competencies for Part-Time Faculty--the First Step.

    ERIC Educational Resources Information Center

    Haddad, Margaret; Dickens, Mary Ellen

    1978-01-01

    Discusses hiring, evaluation, involvement, and competencies of the increasing number of part-time teachers in colleges throughout the country, and the unclear expectations placed on them. Includes a competencies questionnaire for part-time instructors developed at Caldwell Community College and Technical Institute.

  17. Terahertz time domain spectroscopy allows contactless monitoring of grapevine water status

    PubMed Central

    Santesteban, Luis G.; Palacios, Inés; Miranda, Carlos; Iriarte, Juan C.; Royo, José B.; Gonzalo, Ramón

    2015-01-01

    Agriculture is the sector with the greatest water consumption, since food production is frequently based on crop irrigation. Proper irrigation management requires reliable information on plant water status, but all the plant-based methods to determine it suffer from several inconveniences, mainly caused by the necessity of destructive sampling or of alteration of the plant organ due to contact installation. The aim of this work is to test if terahertz (THz) time domain reflectance measurements made on the grapevine trunk allows contactless monitoring of plant status. The experiments were performed on a potted 14-years-old plant, using a general purpose THz emitter receiver head. Trunk THz time-domain reflection signal proved to be very sensitive to changes in plant water availability, as its pattern follows the trend of soil water content and trunk growth variations. Therefore, it could be used to contactless monitor plant water status. Apart from that, THz reflection signal was observed to respond to light conditions which, according to a specifically designed girdling experiment, was caused by changes in the phloem. This latter results opens a promising field of research for contactless monitoring of phloem activity. PMID:26082791

  18. Terahertz time domain spectroscopy allows contactless monitoring of grapevine water status.

    PubMed

    Santesteban, Luis G; Palacios, Inés; Miranda, Carlos; Iriarte, Juan C; Royo, José B; Gonzalo, Ramón

    2015-01-01

    Agriculture is the sector with the greatest water consumption, since food production is frequently based on crop irrigation. Proper irrigation management requires reliable information on plant water status, but all the plant-based methods to determine it suffer from several inconveniences, mainly caused by the necessity of destructive sampling or of alteration of the plant organ due to contact installation. The aim of this work is to test if terahertz (THz) time domain reflectance measurements made on the grapevine trunk allows contactless monitoring of plant status. The experiments were performed on a potted 14-years-old plant, using a general purpose THz emitter receiver head. Trunk THz time-domain reflection signal proved to be very sensitive to changes in plant water availability, as its pattern follows the trend of soil water content and trunk growth variations. Therefore, it could be used to contactless monitor plant water status. Apart from that, THz reflection signal was observed to respond to light conditions which, according to a specifically designed girdling experiment, was caused by changes in the phloem. This latter results opens a promising field of research for contactless monitoring of phloem activity. PMID:26082791

  19. A conservative finite volume scheme with time-accurate local time stepping for scalar transport on unstructured grids

    NASA Astrophysics Data System (ADS)

    Cavalcanti, José Rafael; Dumbser, Michael; Motta-Marques, David da; Fragoso Junior, Carlos Ruberto

    2015-12-01

    In this article we propose a new conservative high resolution TVD (total variation diminishing) finite volume scheme with time-accurate local time stepping (LTS) on unstructured grids for the solution of scalar transport problems, which are typical in the context of water quality simulations. To keep the presentation of the new method as simple as possible, the algorithm is only derived in two space dimensions and for purely convective transport problems, hence neglecting diffusion and reaction terms. The new numerical method for the solution of the scalar transport is directly coupled to the hydrodynamic model of Casulli and Walters (2000) that provides the dynamics of the free surface and the velocity vector field based on a semi-implicit discretization of the shallow water equations. Wetting and drying is handled rigorously by the nonlinear algorithm proposed by Casulli (2009). The new time-accurate LTS algorithm allows a different time step size for each element of the unstructured grid, based on an element-local Courant-Friedrichs-Lewy (CFL) stability condition. The proposed method does not need any synchronization between different time steps of different elements and is by construction locally and globally conservative. The LTS scheme is based on a piecewise linear polynomial reconstruction in space-time using the MUSCL-Hancock method, to obtain second order of accuracy in both space and time. The new algorithm is first validated on some classical test cases for pure advection problems, for which exact solutions are known. In all cases we obtain a very good level of accuracy, showing also numerical convergence results; we furthermore confirm mass conservation up to machine precision and observe an improved computational efficiency compared to a standard second order TVD scheme for scalar transport with global time stepping (GTS). Then, the new LTS method is applied to some more complex problems, where the new scalar transport scheme has also been coupled to

  20. Fluorescently labeled adrenomedullin allows real-time monitoring of adrenomedullin receptor trafficking in living cells.

    PubMed

    Schönauer, Ria; Kaiser, Anette; Holze, Cathleen; Babilon, Stefanie; Köbberling, Johannes; Riedl, Bernd; Beck-Sickinger, Annette G

    2015-12-01

    The human adrenomedullin (ADM) is a 52 amino acid peptide hormone belonging to the calcitonin family of peptides, which plays a major role in the development and regulation of cardiovascular and lymphatic systems. For potential use in clinical applications, we aimed to investigate the fate of the peptide ligand after binding and activation of the adrenomedullin receptor (AM1), a heterodimer consisting of the calcitonin receptor-like receptor (CLR), a G protein-coupled receptor, associated with the receptor activity-modifying protein 2 (RAMP2). Full length and N-terminally shortened ADM peptides were synthesized using Fmoc/tBu solid phase peptide synthesis and site-specifically labeled with the fluorophore carboxytetramethylrhodamine (Tam) either by amide bond formation or copper(I)-catalyzed azide alkyne cycloaddition. For the first time, Tam-labeled ligands allowed the observation of co-internalization of the whole ligand-receptor complex in living cells co-transfected with fluorescent fusion proteins of CLR and RAMP2. Application of a fluorescent probe to track lysosomal compartments revealed that ADM together with the CLR/RAMP2-complex is routed to the degradative pathway. Moreover, we found that the N-terminus of ADM is not a crucial component of the peptide sequence in terms of AM1 internalization behavior. PMID:26767744

  1. Write a Research Paper One Step at a Time: Research Writing Guide.

    ERIC Educational Resources Information Center

    Evans, Helen, Ed.

    Intended to supplement the textbook series "Houghton Mifflin English Grammar and Composition" and to offer students and classroom teachers in the secondary schools a review of research writing, this guide outlines a step-by-step process allowing for thorough student comprehension and comfort with the application of basic research and writing…

  2. Time-step limits for a Monte Carlo Compton-scattering method

    SciTech Connect

    Densmore, Jeffery D; Warsa, James S; Lowrie, Robert B

    2009-01-01

    We perform a stability analysis of a Monte Carlo method for simulating the Compton scattering of photons by free electron in high energy density applications and develop time-step limits that avoid unstable and oscillatory solutions. Implementing this Monte Carlo technique in multi physics problems typically requires evaluating the material temperature at its beginning-of-time-step value, which can lead to this undesirable behavior. With a set of numerical examples, we demonstrate the efficacy of our time-step limits.

  3. Formulation of an explicit-multiple-time-step time integration method for use in a global primitive equation grid model

    NASA Technical Reports Server (NTRS)

    Chao, W. C.

    1982-01-01

    With appropriate modifications, a recently proposed explicit-multiple-time-step scheme (EMTSS) is incorporated into the UCLA model. In this scheme, the linearized terms in the governing equations that generate the gravity waves are split into different vertical modes. Each mode is integrated with an optimal time step, and at periodic intervals these modes are recombined. The other terms are integrated with a time step dictated by the CFL condition for low-frequency waves. This large time step requires a special modification of the advective terms in the polar region to maintain stability. Test runs for 72 h show that EMTSS is a stable, efficient and accurate scheme.

  4. Importance of variable time-step algorithms in spatial kinetics calculations

    SciTech Connect

    Aviles, B.N.

    1994-12-31

    The use of spatial kinetics codes in conjunction with advanced thermal-hydraulics codes is becoming more widespread as better methods and faster computers appear. The integrated code packages are being used for routine nuclear power plant design and analysis, including simulations with instrumentation and control systems initiating system perturbations such as rod motion and scrams. As a result, it is important to include a robust variable time-step algorithm that can accurately and efficiently follow widely varying plant neutronic behavior. This paper describes the variable time-step algorithm in SPANDEX and compares the automatic time-step scheme with a more traditional fixed time-step scheme.

  5. Large time-step stability of explicit one-dimensional advection schemes

    NASA Technical Reports Server (NTRS)

    Leonard, B. P.

    1993-01-01

    There is a wide-spread belief that most explicit one-dimensional advection schemes need to satisfy the so-called 'CFL condition' - that the Courant number, c = udelta(t)/delta(x), must be less than or equal to one, for stability in the von Neumann sense. This puts severe limitations on the time-step in high-speed, fine-grid calculations and is an impetus for the development of implicit schemes, which often require less restrictive time-step conditions for stability, but are more expensive per time-step. However, it turns out that, at least in one dimension, if explicit schemes are formulated in a consistent flux-based conservative finite-volume form, von Neumann stability analysis does not place any restriction on the allowable Courant number. Any explicit scheme that is stable for c is less than 1, with a complex amplitude ratio, G(c), can be easily extended to arbitrarily large c. The complex amplitude ratio is then given by exp(- (Iota)(Nu)(Theta)) G(delta(c)), where N is the integer part of c, and delta(c) = c - N (less than 1); this is clearly stable. The CFL condition is, in fact, not a stability condition at all, but, rather, a 'range restriction' on the 'pieces' in a piece-wise polynomial interpolation. When a global view is taken of the interpolation, the need for a CFL condition evaporates. A number of well-known explicit advection schemes are considered and thus extended to large delta(t). The analysis also includes a simple interpretation of (large delta(t)) total-variation-diminishing (TVD) constraints.

  6. Convergence Acceleration for Multistage Time-Stepping Schemes

    NASA Technical Reports Server (NTRS)

    Swanson, R. C.; Turkel, Eli L.; Rossow, C-C; Vasta, V. N.

    2006-01-01

    The convergence of a Runge-Kutta (RK) scheme with multigrid is accelerated by preconditioning with a fully implicit operator. With the extended stability of the Runge-Kutta scheme, CFL numbers as high as 1000 could be used. The implicit preconditioner addresses the stiffness in the discrete equations associated with stretched meshes. Numerical dissipation operators (based on the Roe scheme, a matrix formulation, and the CUSP scheme) as well as the number of RK stages are considered in evaluating the RK/implicit scheme. Both the numerical and computational efficiency of the scheme with the different dissipation operators are discussed. The RK/implicit scheme is used to solve the two-dimensional (2-D) and three-dimensional (3-D) compressible, Reynolds-averaged Navier-Stokes equations. In two dimensions, turbulent flows over an airfoil at subsonic and transonic conditions are computed. The effects of mesh cell aspect ratio on convergence are investigated for Reynolds numbers between 5.7 x 10(exp 6) and 100.0 x 10(exp 6). Results are also obtained for a transonic wing flow. For both 2-D and 3-D problems, the computational time of a well-tuned standard RK scheme is reduced at least a factor of four.

  7. A Dynamic Era-Based Time-Symmetric Block Time-Step Algorithm with Parallel Implementations

    NASA Astrophysics Data System (ADS)

    Kaplan, Murat; Saygin, Hasan

    2012-06-01

    The time-symmetric block time-step (TSBTS) algorithm is a newly developed efficient scheme for N-body integrations. It is constructed on an era-based iteration. In this work, we re-designed the TSBTS integration scheme with a dynamically changing era size. A number of numerical tests were performed to show the importance of choosing the size of the era, especially for long-time integrations. Our second aim was to show that the TSBTS scheme is as suitable as previously known schemes for developing parallel N-body codes. In this work, we relied on a parallel scheme using the copy algorithm for the time-symmetric scheme. We implemented a hybrid of data and task parallelization for force calculation to handle load balancing problems that can appear in practice. Using the Plummer model initial conditions for different numbers of particles, we obtained the expected efficiency and speedup for a small number of particles. Although parallelization of the direct N-body codes is negatively affected by the communication/calculation ratios, we obtained good load-balanced results. Moreover, we were able to conserve the advantages of the algorithm (e.g., energy conservation for long-term simulations).

  8. Non-iterative adaptive time stepping with truncation error control for simulating variable-density flow

    NASA Astrophysics Data System (ADS)

    Hirthe, E. M.; Graf, T.

    2012-04-01

    Fluid density variations occur due to changes in the solute concentration, temperature and pressure of groundwater. Examples are interaction between freshwater and seawater, radioactive waste disposal, groundwater contamination, and geothermal energy production. The physical coupling between flow and transport introduces non-linearity in the governing mathematical equations, such that solving variable-density flow problems typically requires very long computational time. Computational efficiency can be attained through the use of adaptive time-stepping schemes. The aim of this work is therefore to apply a non-iterative adaptive time-stepping scheme based on local truncation error in variable-density flow problems. That new scheme is implemented into the code of the HydroGeoSphere model (Therrien et al., 2011). The new time-stepping scheme is applied to the Elder (1967) and the Shikaze et al. (1998) problem of free convection in porous and fractured-porous media, respectively. Numerical simulations demonstrate that non-iterative time-stepping based on local truncation error control fully automates the time step size and efficiently limits the temporal discretization error to the user-defined tolerance. Results of the Elder problem show that the new time-stepping scheme presented here is significantly more efficient than uniform time-stepping when high accuracy is required. Results of the Shikaze problem reveal that the new scheme is considerably faster than conventional time-stepping where time step sizes are either constant or controlled by absolute head/concentration changes. Future research will focus on the application of the new time-stepping scheme to variable-density flow in complex real-world fractured-porous rock.

  9. An adaptive time-stepping strategy for solving the phase field crystal model

    SciTech Connect

    Zhang, Zhengru; Ma, Yuan; Qiao, Zhonghua

    2013-09-15

    In this work, we will propose an adaptive time step method for simulating the dynamics of the phase field crystal (PFC) model. The numerical simulation of the PFC model needs long time to reach steady state, and then large time-stepping method is necessary. Unconditionally energy stable schemes are used to solve the PFC model. The time steps are adaptively determined based on the time derivative of the corresponding energy. It is found that the use of the proposed time step adaptivity cannot only resolve the steady state solution, but also the dynamical development of the solution efficiently and accurately. The numerical experiments demonstrate that the CPU time is significantly saved for long time simulations.

  10. An Explicit Super-Time-Stepping Scheme for Non-Symmetric Parabolic Problems

    NASA Astrophysics Data System (ADS)

    Gurski, K. F.; O'Sullivan, S.

    2010-09-01

    Explicit numerical methods for the solution of a system of differential equations may suffer from a time step size that approaches zero in order to satisfy stability conditions. When the differential equations are dominated by a skew-symmetric component, the problem is that the real eigenvalues are dominated by imaginary eigenvalues. We compare results for stable time step limits for the super-time-stepping method of Alexiades, Amiez, and Gremaud (super-time-stepping methods belong to the Runge-Kutta-Chebyshev class) and a new method modeled on a predictor-corrector scheme with multiplicative operator splitting. This new explicit method increases stability of the original super-time-stepping whenever the skew-symmetric term is nonzero, which occurs in particular convection-diffusion problems and more generally when the iteration matrix represents a nonlinear operator. The new method is stable for skew symmetric dominated systems where the regular super-time-stepping scheme fails. This method is second order in time (may be increased by Richardson extrapolation) and the spatial order is determined by the user's choice of discretization scheme. We present a comparison between the two super-time-stepping methods to show the speed up available for any non-symmetric system using the nearly symmetric Black-Scholes equation as an example.

  11. A novel method for the precise determination of step times and sizes in counting large numbers of photobleaching events

    NASA Astrophysics Data System (ADS)

    Tsekouras, Konstantinos; Presse, Steve

    Counting of photobleaching steps is of importance in the investigation of many open problems in biophysics. Current methods of counting photo- bleaching steps cannot directly account for fluorophore photophysical behaviors such as fluorophore self-quenching, blinking and flickering. Our Bayesian approach to the counting problem allows for fluorophore blinking and reactivation as well as for multiple simultaneous photobleaching events and is neither computational resource- nor time- heavy. We detail the method's applicability and limitations and present examples of application in photobleach event counting.

  12. Entosis allows timely elimination of the luminal epithelial barrier for embryo implantation.

    PubMed

    Li, Yingju; Sun, Xiaofei; Dey, Sudhansu K

    2015-04-21

    During implantation, uterine luminal epithelial (LE) cells first interact with the blastocyst trophectoderm. Within 30 hr after the initiation of attachment, LE cells surrounding the blastocyst in the implantation chamber (crypt) disappear, allowing trophoblast cells to make direct physical contact with the underneath stroma for successful implantation. The mechanism for the extraction of LE cells was thought to be mediated by apoptosis. Here, we show that LE cells in direct contact with the blastocyst are endocytosed by trophoblast cells by adopting the nonapoptotic cell-in-cell invasion process (entosis) in the absence of caspase 3 activation. Our in vivo observations were reinforced by the results of co-culture experiments with primary uterine epithelial cells with trophoblast stem cells or blastocysts showing internalization of epithelial cells by trophoblasts. We have identified entosis as a mechanism to remove LE cells by trophoblast cells in implantation, conferring a role for entosis in an important physiological process. PMID:25865893

  13. Consistency of internal fluxes in a hydrological model running at multiple time steps

    NASA Astrophysics Data System (ADS)

    Ficchi, Andrea; Perrin, Charles; Andréassian, Vazken

    2016-04-01

    Improving hydrological models remains a difficult task and many ways can be explored, among which one can find the improvement of spatial representation, the search for more robust parametrization, the better formulation of some processes or the modification of model structures by trial-and-error procedure. Several past works indicate that model parameters and structure can be dependent on the modelling time step, and there is thus some rationale in investigating how a model behaves across various modelling time steps, to find solutions for improvements. Here we analyse the impact of data time step on the consistency of the internal fluxes of a rainfall-runoff model run at various time steps, by using a large data set of 240 catchments. To this end, fine time step hydro-climatic information at sub-hourly resolution is used as input of a parsimonious rainfall-runoff model (GR) that is run at eight different model time steps (from 6 minutes to one day). The initial structure of the tested model (i.e. the baseline) corresponds to the daily model GR4J (Perrin et al., 2003), adapted to be run at variable sub-daily time steps. The modelled fluxes considered are interception, actual evapotranspiration and intercatchment groundwater flows. Observations of these fluxes are not available, but the comparison of modelled fluxes at multiple time steps gives additional information for model identification. The joint analysis of flow simulation performance and consistency of internal fluxes at different time steps provides guidance to the identification of the model components that should be improved. Our analysis indicates that the baseline model structure is to be modified at sub-daily time steps to warrant the consistency and realism of the modelled fluxes. For the baseline model improvement, particular attention is devoted to the interception model component, whose output flux showed the strongest sensitivity to modelling time step. The dependency of the optimal model

  14. Automatic Time Stepping with Global Error Control for Groundwater Flow Models

    SciTech Connect

    Tang, Guoping

    2008-09-01

    An automatic time stepping with global error control is proposed for the time integration of the diffusion equation to simulate groundwater flow in confined aquifers. The scheme is based on an a posteriori error estimate for the discontinuous Galerkin (dG) finite element methods. A stability factor is involved in the error estimate and it is used to adapt the time step and control the global temporal error for the backward difference method. The stability factor can be estimated by solving a dual problem. The stability factor is not sensitive to the accuracy of the dual solution and the overhead computational cost can be minimized by solving the dual problem using large time steps. Numerical experiments are conducted to show the application and the performance of the automatic time stepping scheme. Implementation of the scheme can lead to improvement in accuracy and efficiency for groundwater flow models.

  15. 40 CFR 97.141 - Timing requirements for CAIR NOX allowance allocations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...), for the control periods in 2009, 2010, 2011, 2012, 2013, and 2014. (b) By July 31, 2011 and July 31 of... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Timing requirements for CAIR NOX... applicable deadline for determination under this paragraph. (c) By July 31, 2009 and July 31 of each...

  16. 40 CFR 97.141 - Timing requirements for CAIR NOX allowance allocations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...), for the control periods in 2009, 2010, 2011, 2012, 2013, and 2014. (b) By July 31, 2011 and July 31 of... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Timing requirements for CAIR NOX... applicable deadline for determination under this paragraph. (c) By July 31, 2009 and July 31 of each...

  17. Simple and versatile modifications allowing time gated spectral acquisition, imaging and lifetime profiling on conventional wide-field microscopes

    NASA Astrophysics Data System (ADS)

    Pal, Robert; Beeby, Andrew

    2014-09-01

    An inverted microscope has been adapted to allow time-gated imaging and spectroscopy to be carried out on samples containing responsive lanthanide probes. The adaptation employs readily available components, including a pulsed light source, time-gated camera, spectrometer and photon counting detector, allowing imaging, emission spectroscopy and lifetime measurements. Each component is controlled by a suite of software written in LabVIEW and is powered via conventional USB ports.

  18. Real-time quantum trajectories for classically allowed dynamics in strong laser fields

    NASA Astrophysics Data System (ADS)

    Plimak, L. I.; Ivanov, Misha Yu.

    2015-10-01

    Both the physical picture of the dynamics of atoms and molecules in intense infrared fields and its theoretical description use the concept of electron trajectories. Here, we address a key question which arises in this context: Are distinctly quantum features of these trajectories, such as the complex-valued coordinates, physically relevant in the classically allowed region of phase space, and what is their origin? First, we argue that solutions of classical equations of motion can account for quantum effects. To this end, we construct an exact solution to the classical Hamilton-Jacobi equation which accounts for dynamics of the wave packet, and show that this solution is physically correct in the limit ?. Second, we show that imaginary components of classical trajectories are directly linked to the finite size of the initial wave packet in momentum space. This way, if the electronic wave packet produced by optical tunnelling in strong infrared fields is localised both in coordinate and momentum, its motion after tunnelling ipso facto cannot be described with purely classical trajectories - in contrast to popular models in the literature.

  19. Time Gating of Chloroplast Autofluorescence Allows Clearer Fluorescence Imaging In Planta

    PubMed Central

    Kodama, Yutaka

    2016-01-01

    Chloroplast, an organelle facilitating photosynthesis, exhibits strong autofluorescence, which is an undesired background signal that restricts imaging experiments with exogenous fluorophore in plants. In this study, the autofluorescence was characterized in planta under confocal laser microscopy, and it was found that the time-gated imaging technique completely eliminates the autofluorescence. As a demonstration of the technique, a clearer signal of fluorescent protein-tagged phototropin, a blue-light photoreceptor localized at the chloroplast periphery, was visualized in planta. PMID:27027881

  20. Time Gating of Chloroplast Autofluorescence Allows Clearer Fluorescence Imaging In Planta.

    PubMed

    Kodama, Yutaka

    2016-01-01

    Chloroplast, an organelle facilitating photosynthesis, exhibits strong autofluorescence, which is an undesired background signal that restricts imaging experiments with exogenous fluorophore in plants. In this study, the autofluorescence was characterized in planta under confocal laser microscopy, and it was found that the time-gated imaging technique completely eliminates the autofluorescence. As a demonstration of the technique, a clearer signal of fluorescent protein-tagged phototropin, a blue-light photoreceptor localized at the chloroplast periphery, was visualized in planta. PMID:27027881

  1. Cherenkov Video Imaging Allows for the First Visualization of Radiation Therapy in Real Time

    SciTech Connect

    Jarvis, Lesley A.; Zhang, Rongxiao; Gladstone, David J.; Jiang, Shudong; Hitchcock, Whitney; Friedman, Oscar D.; Glaser, Adam K.; Jermyn, Michael; Pogue, Brian W.

    2014-07-01

    Purpose: To determine whether Cherenkov light imaging can visualize radiation therapy in real time during breast radiation therapy. Methods and Materials: An intensified charge-coupled device (CCD) camera was synchronized to the 3.25-μs radiation pulses of the clinical linear accelerator with the intensifier set × 100. Cherenkov images were acquired continuously (2.8 frames/s) during fractionated whole breast irradiation with each frame an accumulation of 100 radiation pulses (approximately 5 monitor units). Results: The first patient images ever created are used to illustrate that Cherenkov emission can be visualized as a video during conditions typical for breast radiation therapy, even with complex treatment plans, mixed energies, and modulated treatment fields. Images were generated correlating to the superficial dose received by the patient and potentially the location of the resulting skin reactions. Major blood vessels are visible in the image, providing the potential to use these as biological landmarks for improved geometric accuracy. The potential for this system to detect radiation therapy misadministrations, which can result from hardware malfunction or patient positioning setup errors during individual fractions, is shown. Conclusions: Cherenkoscopy is a unique method for visualizing surface dose resulting in real-time quality control. We propose that this system could detect radiation therapy errors in everyday clinical practice at a time when these errors can be corrected to result in improved safety and quality of radiation therapy.

  2. Stability analysis and time-step limits for a Monte Carlo Compton-scattering method

    SciTech Connect

    Densmore, Jeffery D. Warsa, James S. Lowrie, Robert B.

    2010-05-20

    A Monte Carlo method for simulating Compton scattering in high energy density applications has been presented that models the photon-electron collision kinematics exactly [E. Canfield, W.M. Howard, E.P. Liang, Inverse Comptonization by one-dimensional relativistic electrons, Astrophys. J. 323 (1987) 565]. However, implementing this technique typically requires an explicit evaluation of the material temperature, which can lead to unstable and oscillatory solutions. In this paper, we perform a stability analysis of this Monte Carlo method and develop two time-step limits that avoid undesirable behavior. The first time-step limit prevents instabilities, while the second, more restrictive time-step limit avoids both instabilities and nonphysical oscillations. With a set of numerical examples, we demonstrate the efficacy of these time-step limits.

  3. Stance time and step width variability have unique contributing impairments in older persons.

    PubMed

    Brach, Jennifer S; Studenski, Stephanie; Perera, Subashan; VanSwearingen, Jessie M; Newman, Anne B

    2008-04-01

    Gait variability may have multiple causes. We hypothesized that central nervous system (CNS) impairments would affect motor control and be manifested as increased stance time and step length variability, while sensory impairments would affect balance and be manifested as increased step width variability. Older adults (mean+/-standard deviation (S.D.) age=79.4+/-4.1, n=558) from the Pittsburgh site of the Cardiovascular Health Study participated. The S.D. across steps was the indicator of gait variability, determined for three gait measures, step length, stance time and step width, using a computerized walkway. Impairment measures included CNS function (modified mini-mental state examination, Trails A and B, Digit Symbol Substitution, finger tapping), sensory function (lower extremity (LE) vibration, vision), strength (grip strength, repeated chair stands), mood, and LE pain. Linear regression models were fit for the three gait variability characteristics using impairment measures as independent variables, adjusted for age, race, gender, and height. Analyses were repeated stratified by gait speed. All measures of CNS impairment were directly related to stance time variability (p<0.01), with increased CNS impairment associated with increased stance time variability. CNS impairments were not related to step length or width variability. Both sensory impairments were inversely related to step width (p<0.01) but not step length or stance time variability. CNS impairments affected stance time variability especially in slow walkers while sensory impairments affected step width variability in fast walkers. Specific patterns of gait variability may imply different underlying causes. Types of gait variability should be specified. Interventions may be targeted at specific types of gait variability. PMID:17632004

  4. Differential reproductive timing in Echinocardium spp.: the first Mediterranean survey allows interoceanic and interspecific comparisons.

    PubMed

    Egea, Emilie; Mérigot, Bastien; Mahé-Bézac, Chantal; Féral, Jean-Pierre; Chenuil, Anne

    2011-01-01

    Echinocardium cordatum had long been considered as cosmopolitan, but molecular data revealed it is a complex of cryptic species, with two non-hybridizing species (B1 & B2) in the Mediterranean Sea living in syntopy with Echinocardium mediterraneum. Histological analyses of the gonads from a 17-month sampling period revealed a statistically significant time lag between the Maturity Indices of E. cordatum and E. mediterraneum. The main environmental stimulus may be different for the two nominal species, possibly seawater temperature for E. cordatum and chlorophyll a concentration for E. mediterraneum. Within the E. cordatum complex, spawning timing and synchrony are different according to major geographic areas (Atlantic/Pacific/Mediterranean) and/or the corresponding genetic subdivision [A/P/(B1 & B2)]. In contrast, the effects of temperature on the reproductive cycle seem rather to mirror the genetic lineages than environmental similarities of the different localities. Between the sister species (B1 & B2) no differences could be detected, maybe due to small sample sizes. PMID:21262482

  5. Laser speckle imaging allows real-time intraoperative blood flow assessment during neurosurgical procedures

    PubMed Central

    Hecht, Nils; Woitzik, Johannes; König, Susanne; Horn, Peter; Vajkoczy, Peter

    2013-01-01

    Currently, there is no adequate technique for intraoperative monitoring of cerebral blood flow (CBF). To evaluate laser speckle imaging (LSI) for assessment of relative CBF, LSI was performed in 30 patients who underwent direct surgical revascularization for treatment of arteriosclerotic cerebrovascular disease (ACVD), Moyamoya disease (MMD), or giant aneurysms, and in 8 control patients who underwent intracranial surgery for reasons other than hemodynamic compromise. The applicability and sensitivity of LSI was investigated through baseline perfusion and CO2 reactivity testing. The dynamics of LSI were assessed during bypass test occlusion and flow initiation procedures. Laser speckle imaging permitted robust (pseudo-) quantitative assessment of relative microcirculatory flow and standard bypass grafting resulted in significantly higher postoperative baseline perfusion values in ACVD and MMD. The applicability and sensitivity of LSI was shown by a significantly reduced CO2 reactivity in ACVD (9.6±9%) and MMD (8.5±8%) compared with control (31.2±5% P<0.0001). In high- and intermediate-flow bypass patients, LSI was characterized by a dynamic real-time response to acute perfusion changes and ultimately confirmed a sufficient flow substitution through the bypass graft. Thus, LSI can be used for sensitive and continuous, non-invasive real-time visualization and measurement of relative cortical CBF in excellent spatial–temporal resolution. PMID:23512134

  6. An Adaptive Fourier Filter for Relaxing Time Stepping Constraints for Explicit Solvers

    SciTech Connect

    Gelb, Anne; Archibald, Richard K

    2015-01-01

    Filtering is necessary to stabilize piecewise smooth solutions. The resulting diffusion stabilizes the method, but may fail to resolve the solution near discontinuities. Moreover, high order filtering still requires cost prohibitive time stepping. This paper introduces an adaptive filter that controls spurious modes of the solution, but is not unnecessarily diffusive. Consequently we are able to stabilize the solution with larger time steps, but also take advantage of the accuracy of a high order filter.

  7. Database Integration: An Intial Step Towards the Deep-Time Data Infrastructure

    NASA Astrophysics Data System (ADS)

    Kolankowski, S. M.; Fox, P. A.; Ma, X.

    2015-12-01

    As our knowledge of Earth's geologic history grows, we require more robust methods of sharing immense amounts of data. Various databases across numerous disciplines have been widely utilized to offer extensive information on very specific pieces of both Earth's history and its current state, ie. fossil record, rock composition, proteins, etc. In order to gain a deeper understanding of our planet's past we must combine the resources present in our online communities. These databases could be a powerful force in identifying previously unseen correlations if used in tandem rather than as separate entities. Creating a unifying site that provides links to these databases will aid in our ability as a collaborative scientific community to utilize our findings on a larger scale. The Deep-Time Data Infrastructure is currently underway as part of a larger effort to accomplish this goal. DTDI works not to build a new database, but to integrate existing resources. This research is the beginning step in the DTDI program. To create this infrastructure, all current geologic and related databases had to be identified and their schema recorded. Using variables from their combined records, we are able to determine the best way to integrate them using common factors. The Deep-Time Data Infrastructure will allow geoscientists to bridge gaps in data and further our understanding of our planet's history.

  8. Ancient numerical daemons of conceptual hydrological modeling: 1. Fidelity and efficiency of time stepping schemes

    NASA Astrophysics Data System (ADS)

    Clark, Martyn P.; Kavetski, Dmitri

    2010-10-01

    A major neglected weakness of many current hydrological models is the numerical method used to solve the governing model equations. This paper thoroughly evaluates several classes of time stepping schemes in terms of numerical reliability and computational efficiency in the context of conceptual hydrological modeling. Numerical experiments are carried out using 8 distinct time stepping algorithms and 6 different conceptual rainfall-runoff models, applied in a densely gauged experimental catchment, as well as in 12 basins with diverse physical and hydroclimatic characteristics. Results show that, over vast regions of the parameter space, the numerical errors of fixed-step explicit schemes commonly used in hydrology routinely dwarf the structural errors of the model conceptualization. This substantially degrades model predictions, but also, disturbingly, generates fortuitously adequate performance for parameter sets where numerical errors compensate for model structural errors. Simply running fixed-step explicit schemes with shorter time steps provides a poor balance between accuracy and efficiency: in some cases daily-step adaptive explicit schemes with moderate error tolerances achieved comparable or higher accuracy than 15 min fixed-step explicit approximations but were nearly 10 times more efficient. From the range of simple time stepping schemes investigated in this work, the fixed-step implicit Euler method and the adaptive explicit Heun method emerge as good practical choices for the majority of simulation scenarios. In combination with the companion paper, where impacts on model analysis, interpretation, and prediction are assessed, this two-part study vividly highlights the impact of numerical errors on critical performance aspects of conceptual hydrological models and provides practical guidelines for robust numerical implementation.

  9. Influence of allowable interruption period on estimates of accelerometer wear time and sedentary time in older adults

    PubMed Central

    Mailey, Emily L.; Gothe, Neha P.; Wójcicki, Thomas R.; Szabo, Amanda N.; Olson, Erin A.; Mullen, Sean P.; Fanning, Jason T.; Motl, Robert W.; McAuley, Edward

    2013-01-01

    The criteria one uses to reduce accelerometer data can profoundly influence the interpretation of research outcomes. The purpose of this study was to examine the influence of three different interruption periods (i.e., 20, 30, and 60 minutes) on the amount of data retained for analyses and estimates of sedentary time among older adults. Older adults (N=311; Mage=71.1) wore an accelerometer for seven days and reported wear time on an accelerometer log. Accelerometer data were downloaded and scored using 20, 30, and 60-minute interruption periods. Estimates of wear time derived using each interruption period were compared to self-reported wear time, and descriptive statistics were used to compare estimates of sedentary time. Results showed a longer interruption period (i.e., 60 minutes) yields the largest sample size and the closest approximation of self-reported wear time. A short interruption period (i.e., 20 minutes) is likely to underestimate sedentary time among older adults. PMID:23752299

  10. Modeling solute transport in distribution networks with variable demand and time step sizes.

    SciTech Connect

    Peyton, Chad E.; Bilisoly, Roger Lee; Buchberger, Steven G.; McKenna, Sean Andrew; Yarrington, Lane

    2004-06-01

    The effect of variable demands at short time scales on the transport of a solute through a water distribution network has not previously been studied. We simulate flow and transport in a small water distribution network using EPANET to explore the effect of variable demand on solute transport across a range of hydraulic time step scales from 1 minute to 2 hours. We show that variable demands at short time scales can have the following effects: smoothing of a pulse of tracer injected into a distribution network and increasing the variability of both the transport pathway and transport timing through the network. Variable demands are simulated for these different time step sizes using a previously developed Poisson rectangular pulse (PRP) demand generator that considers demand at a node to be a combination of exponentially distributed arrival times with log-normally distributed intensities and durations. Solute is introduced at a tank and at three different network nodes and concentrations are modeled through the system using the Lagrangian transport scheme within EPANET. The transport equations within EPANET assume perfect mixing of the solute within a parcel of water and therefore physical dispersion cannot occur. However, variation in demands along the solute transport path contribute to both removal and distortion of the injected pulse. The model performance measures examined are the distribution of the Reynolds number, the variation in the center of mass of the solute across time, and the transport path and timing of the solute through the network. Variation in all three performance measures is greatest at the shortest time step sizes. As the scale of the time step increases, the variability in these performance measures decreases. The largest time steps produce results that are inconsistent with the results produced by the smaller time steps.

  11. The energy expenditure of stair climbing one step and two steps at a time: estimations from measures of heart rate.

    PubMed

    Halsey, Lewis G; Watkins, David A R; Duggan, Brendan M

    2012-01-01

    Stairway climbing provides a ubiquitous and inconspicuous method of burning calories. While typically two strategies are employed for climbing stairs, climbing one stair step per stride or two steps per stride, research to date has not clarified if there are any differences in energy expenditure between them. Fourteen participants took part in two stair climbing trials whereby measures of heart rate were used to estimate energy expenditure during stairway ascent at speeds chosen by the participants. The relationship between rate of oxygen consumption ([Formula: see text]) and heart rate was calibrated for each participant using an inclined treadmill. The trials involved climbing up and down a 14.05 m high stairway, either ascending one step per stride or ascending two stair steps per stride. Single-step climbing used 8.5±0.1 kcal min(-1), whereas double step climbing used 9.2±0.1 kcal min(-1). These estimations are similar to equivalent measures in all previous studies, which have all directly measured [Formula: see text] The present study findings indicate that (1) treadmill-calibrated heart rate recordings can be used as a valid alternative to respirometry to ascertain rate of energy expenditure during stair climbing; (2) two step climbing invokes a higher rate of energy expenditure; however, one step climbing is energetically more expensive in total over the entirety of a stairway. Therefore to expend the maximum number of calories when climbing a set of stairs the single-step strategy is better. PMID:23251455

  12. The Energy Expenditure of Stair Climbing One Step and Two Steps at a Time: Estimations from Measures of Heart Rate

    PubMed Central

    Halsey, Lewis G.; Watkins, David A. R.; Duggan, Brendan M.

    2012-01-01

    Stairway climbing provides a ubiquitous and inconspicuous method of burning calories. While typically two strategies are employed for climbing stairs, climbing one stair step per stride or two steps per stride, research to date has not clarified if there are any differences in energy expenditure between them. Fourteen participants took part in two stair climbing trials whereby measures of heart rate were used to estimate energy expenditure during stairway ascent at speeds chosen by the participants. The relationship between rate of oxygen consumption () and heart rate was calibrated for each participant using an inclined treadmill. The trials involved climbing up and down a 14.05 m high stairway, either ascending one step per stride or ascending two stair steps per stride. Single-step climbing used 8.5±0.1 kcal min−1, whereas double step climbing used 9.2±0.1 kcal min−1. These estimations are similar to equivalent measures in all previous studies, which have all directly measured The present study findings indicate that (1) treadmill-calibrated heart rate recordings can be used as a valid alternative to respirometry to ascertain rate of energy expenditure during stair climbing; (2) two step climbing invokes a higher rate of energy expenditure; however, one step climbing is energetically more expensive in total over the entirety of a stairway. Therefore to expend the maximum number of calories when climbing a set of stairs the single-step strategy is better. PMID:23251455

  13. Dissolvable fluidic time delays for programming multi-step assays in instrument-free paper diagnostics

    PubMed Central

    Lutz, Barry; Liang, Tinny; Fu, Elain; Ramachandran, Sujatha; Kauffman, Peter; Yager, Paul

    2013-01-01

    Lateral flow tests (LFTs) are an ingenious format for rapid and easy-to-use diagnostics, but they are fundamentally limited to assay chemistries that can be reduced to a single chemical step. In contrast, most laboratory diagnostic assays rely on multiple timed steps carried out by a human or a machine. Here, we use dissolvable sugar applied to paper to create programmable flow delays and present a paper network topology that uses these time delays to program automated multi-step fluidic protocols. Solutions of sucrose at different concentrations (10-70% of saturation) were added to paper strips and dried to create fluidic time delays spanning minutes to nearly an hour. A simple folding card format employing sugar delays was shown to automate a four-step fluidic process initiated by a single user activation step (folding the card); this device was used to perform a signal-amplified sandwich immunoassay for a diagnostic biomarker for malaria. The cards are capable of automating multi-step assay protocols normally used in laboratories, but in a rapid, low-cost, and easy-to-use format. PMID:23685876

  14. Time Step Rescaling Recovers Continuous-Time Dynamical Properties for Discrete-Time Langevin Integration of Nonequilibrium Systems

    PubMed Central

    2015-01-01

    When simulating molecular systems using deterministic equations of motion (e.g., Newtonian dynamics), such equations are generally numerically integrated according to a well-developed set of algorithms that share commonly agreed-upon desirable properties. However, for stochastic equations of motion (e.g., Langevin dynamics), there is still broad disagreement over which integration algorithms are most appropriate. While multiple desiderata have been proposed throughout the literature, consensus on which criteria are important is absent, and no published integration scheme satisfies all desiderata simultaneously. Additional nontrivial complications stem from simulating systems driven out of equilibrium using existing stochastic integration schemes in conjunction with recently developed nonequilibrium fluctuation theorems. Here, we examine a family of discrete time integration schemes for Langevin dynamics, assessing how each member satisfies a variety of desiderata that have been enumerated in prior efforts to construct suitable Langevin integrators. We show that the incorporation of a novel time step rescaling in the deterministic updates of position and velocity can correct a number of dynamical defects in these integrators. Finally, we identify a particular splitting (related to the velocity Verlet discretization) that has essentially universally appropriate properties for the simulation of Langevin dynamics for molecular systems in equilibrium, nonequilibrium, and path sampling contexts. PMID:24555448

  15. Multi time-step wavefront reconstruction for tomographic adaptive-optics systems.

    PubMed

    Ono, Yoshito H; Akiyama, Masayuki; Oya, Shin; Lardiére, Olivier; Andersen, David R; Correia, Carlos; Jackson, Kate; Bradley, Colin

    2016-04-01

    In tomographic adaptive-optics (AO) systems, errors due to tomographic wavefront reconstruction limit the performance and angular size of the scientific field of view (FoV), where AO correction is effective. We propose a multi time-step tomographic wavefront reconstruction method to reduce the tomographic error by using measurements from both the current and previous time steps simultaneously. We further outline the method to feed the reconstructor with both wind speed and direction of each turbulence layer. An end-to-end numerical simulation, assuming a multi-object AO (MOAO) system on a 30 m aperture telescope, shows that the multi time-step reconstruction increases the Strehl ratio (SR) over a scientific FoV of 10 arc min in diameter by a factor of 1.5-1.8 when compared to the classical tomographic reconstructor, depending on the guide star asterism and with perfect knowledge of wind speeds and directions. We also evaluate the multi time-step reconstruction method and the wind estimation method on the RAVEN demonstrator under laboratory setting conditions. The wind speeds and directions at multiple atmospheric layers are measured successfully in the laboratory experiment by our wind estimation method with errors below 2  ms-1. With these wind estimates, the multi time-step reconstructor increases the SR value by a factor of 1.2-1.5, which is consistent with a prediction from the end-to-end numerical simulation. PMID:27140785

  16. Choice stepping reaction time test using exergame technology for fall risk assessment in older people.

    PubMed

    Ejupi, Andreas; Brodie, Matthew; Gschwind, Yves J; Schoene, Daniel; Lord, Stephen; Delbaere, Kim

    2014-01-01

    Accidental falls remain an important problem in older people. Stepping is a common task to avoid a fall and requires good interplay between sensory functions, central processing and motor execution. Increased choice stepping reaction time has been associated with recurrent falls in older people. The aim of this study was to examine if a sensor-based Exergame Choice Stepping Reaction Time test can successfully discriminate older fallers from non-fallers. The stepping test was conducted in a cohort of 104 community-dwelling older people (mean age: 80.7 ± 7.0 years). Participants were asked to step laterally as quickly as possible after a light stimulus appeared on a TV screen. Spatial and temporal measurements of the lower and upper body were derived from a low-cost and portable 3D-depth sensor (i.e. Microsoft Kinect) and 3D-accelerometer. Fallers had a slower stepping reaction time (970 ± 228 ms vs. 858 ± 123 ms, P = 0.001) and a slower reaction of their upper body (719 ± 289 ms vs. 631 ± 166 ms, P = 0.052) compared to non-fallers. It took fallers significantly longer than non-fallers to recover their balance after initiating the step (2147 ± 800 ms vs. 1841 ± 591 ms, P = 0.029). This study demonstrated that a sensor-based, low-cost and easy to administer stepping test, with the potential to be used in clinical practice or regular unsupervised home assessments, was able to identify significant differences between performances by fallers and non-fallers. PMID:25571596

  17. Time-step limits for a Monte Carlo Compton-scattering method

    SciTech Connect

    Densmore, Jeffery D; Warsa, James S; Lowrie, Robert B

    2008-01-01

    Compton scattering is an important aspect of radiative transfer in high energy density applications. In this process, the frequency and direction of a photon are altered by colliding with a free electron. The change in frequency of a scattered photon results in an energy exchange between the photon and target electron and energy coupling between radiation and matter. Canfield, Howard, and Liang have presented a Monte Carlo method for simulating Compton scattering that models the photon-electron collision kinematics exactly. However, implementing their technique in multiphysics problems that include the effects of radiation-matter energy coupling typically requires evaluating the material temperature at its beginning-of-time-step value. This explicit evaluation can lead to unstable and oscillatory solutions. In this paper, we perform a stability analysis of this Monte Carlo method and present time-step limits that avoid instabilities and nonphysical oscillations by considering a spatially independent, purely scattering radiative-transfer problem. Examining a simplified problem is justified because it isolates the effects of Compton scattering, and existing Monte Carlo techniques can robustly model other physics (such as absorption, emission, sources, and photon streaming). Our analysis begins by simplifying the equations that are solved via Monte Carlo within each time step using the Fokker-Planck approximation. Next, we linearize these approximate equations about an equilibrium solution such that the resulting linearized equations describe perturbations about this equilibrium. We then solve these linearized equations over a time step and determine the corresponding eigenvalues, quantities that can predict the behavior of solutions generated by a Monte Carlo simulation as a function of time-step size and other physical parameters. With these results, we develop our time-step limits. This approach is similar to our recent investigation of time discretizations for the

  18. Effects of Academic Ability, Time Allowed for Study, and Teacher Directedness on Achievement in a High School Science Course (ISIS).

    ERIC Educational Resources Information Center

    Burkman, Ernest; And Others

    1981-01-01

    The simultaneous effects of two instructional variables of degree of teacher direction (student- versus teacher-directed) and time allowed for study and the student variable of general ability are described for student achievement (N=912) in three life-science instructional modules. (Author)

  19. Piloted simulator study of allowable time delay in pitch flight control system of a transport airplane with negative static stability

    NASA Technical Reports Server (NTRS)

    Grantham, William D.; Smith, Paul M.; Person, Lee H., Jr.; Meyer, Robert T.; Tingas, Stephen A.

    1987-01-01

    A piloted simulation study was conducted to determine the permissible time delay in the flight control system of a 10-percent statically unstable transport airplane during cruise flight conditions. The math model used for the simulation was a derivative Lockheed L-1011 wide-body jet transport. Data were collected and analyzed from a total of 137 cruising flights in both calm- and turbulent-air conditions. Results of this piloted simulation study verify previous findings that show present military specifications for allowable control-system time delay may be too stringent when applied to transport-size airplanes. Also, the degree of handling-qualities degradation due to time delay is shown to be strongly dependent on the source of the time delay in an advanced flight control system. Maximum allowable time delay for each source of time delay in the control system, in addition to a less stringent overall maximum level of time delay, should be considered for large aircraft. Preliminary results also suggest that adverse effects of control-system time delay may be at least partially offset by variations in control gearing. It is recommended that the data base include different airplane baselines, control systems, and piloting tasks with many pilots participating, so that a reasonable set of limits for control-system time delay can be established to replace the military specification limits currently being used.

  20. Exponential time-differencing with embedded Runge–Kutta adaptive step control

    SciTech Connect

    Whalen, P.; Brio, M.; Moloney, J.V.

    2015-01-01

    We have presented the first embedded Runge–Kutta exponential time-differencing (RKETD) methods of fourth order with third order embedding and fifth order with third order embedding for non-Rosenbrock type nonlinear systems. A procedure for constructing RKETD methods that accounts for both order conditions and stability is outlined. In our stability analysis, the fast time scale is represented by a full linear operator in contrast to particular scalar cases considered before. An effective time-stepping strategy based on reducing both ETD function evaluations and rejected steps is described. Comparisons of performance with adaptive-stepping integrating factor (IF) are carried out on a set of canonical partial differential equations: the shock-fronts of Burgers equation, interacting KdV solitons, KS controlled chaos, and critical collapse of two-dimensional NLS.

  1. Muscle contraction: the step-size distance and the impulse-time per ATP.

    PubMed

    Worthington, C R; Elliott, G F

    1996-02-01

    We derive the step-size distance, and the impulse time per ATP split, from a consideration of Hill's energy rate equation coupled with the enthalpy available per ATP split. This definition of step-size distance is model-independent, and is calculated to have a maximum of 17 A at no load and to reduce to zero at isometric tension, since it will depend on the velocity of shortening. We revisit a derivation of Hill's force-velocity equation depending on impulsive forces working against frictional forces and show that this gives a physical meaning to Hill's constants a and b. This is particularly elegant for Hill's constant b, which is directly related to the impulse time; the value of this impulse time is 1/2 ms. The question that muscle contraction may involve overlapping interactions is considered. However, we find that the step-size distance is not dependent on the possibility of overlapping interactions. PMID:8852761

  2. Variable grid-size and time-step finite difference method for seismic forward modeling and reverse-time migration

    NASA Astrophysics Data System (ADS)

    Wang, Yue

    A new variable grid-size and time-step finite-difference (FD) method is developed and applied to three different geophysical problems: simulation of tube waves in boreholes, three-dimensional (3-D) ground-motion simulation in sedimentary basin models, and reverse-time migration of multicomponent data. Unlike the conventional FD method, which uses a fixed grid-size and time-step for the entire model region, spatially variable grid-sizes and time-steps are used to achieve the optimal computational efficiency. For tube wave simulations, a fine grid-spacing is used for simulation inside the borehole region, while a coarse grid is used in the exterior region. While the stability condition requires a very fine time step for the fine grid, a variable time-step method provides coarse time steps for simulation in the coarse grid. Variable grid-size and time-step changes are used to achieve both accuracy and efficiency in the simulations. Numerical tests are performed for the Bayou Choctaw salt-flank model with different borehole models. The results show the important borehole effects on the seismic wavefield for a realistic source bandwidth. The combination of variable grid-size and time-step methods reduces computational costs by several orders of magnitude for the borehole models. Viscoelastic 3-D simulations are performed for a three-layer Salt Lake basin model. The near-surface unconsolidated layer is modeled with a fine grid, and the deep part of the model is modeled by a coarse grid. Simulation results show that the 3-D basin features and the shallow layer significantly affect the amplitude and duration time of the ground motion. In the elastic case, the approximation by 2-D modeling is insufficient to simulate the 3-D ground motion response. A basin model without a shallow low-velocity layer underestimates the ground motion duration and cumulative kinetic energy by 50% or more. The simulation of a Bingham Mine blast suggests that a lower S-velocity should be used to

  3. Numerical solution of the Euler equations by finite volume methods using Runge Kutta time stepping schemes

    NASA Technical Reports Server (NTRS)

    Jameson, A.; Schmidt, Wolfgang; Turkel, Eli

    1981-01-01

    A new combination of a finite volume discretization in conjunction with carefully designed dissipative terms of third order, and a Runge Kutta time stepping scheme, is shown to yield an effective method for solving the Euler equations in arbitrary geometric domains. The method has been used to determine the steady transonic flow past an airfoil using an O mesh. Convergence to a steady state is accelerated by the use of a variable time step determined by the local Courant member, and the introduction of a forcing term proportional to the difference between the local total enthalpy and its free stream value.

  4. A step in time: Changes in standard-frequency and time-signal broadcasts, 1 January 1972

    NASA Technical Reports Server (NTRS)

    Chi, A. R.; Fosque, H. S.

    1973-01-01

    An improved coordinated universal time (UTC) system has been adopted by the International Radio Consultative Committee. It was implemented internationally by the standard-frequency and time-broadcast stations on 1 Jan. 1972. The new UTC system eliminates the frequency offset of 300 parts in 10 to the 10th power between the old UTC and atomic time, thus making the broadcast time interval (the UTC second) constant and defined by the resonant frequency of cesium atoms. The new time scale is kept in synchronism with the rotation of the Earth within plus or minus 0.7 s by step-time adjustments of exactly 1 s, when needed. A time code has been added to the disseminated time signals to permit universal time to be obtained from the broadcasts to the nearest 0.1 s for users requiring such precision. The texts of the International Radio Consultative Committee recommendation and report to implement the new UTC system are given. The coding formats used by various standard time broadcast services to transmit the difference between the universal time (UT1) and the UTC are also given. For users' convenience, worldwide primary VLF and HF transmissions stations, frequencies, and schedules of time emissions are also included. Actual time-step adjustments made by various stations on 1 Jan. 1972, are provided for future reference.

  5. Time-step Considerations in Particle Simulation Algorithms for Coulomb Collisions in Plasmas

    SciTech Connect

    Cohen, B I; Dimits, A; Friedman, A; Caflisch, R

    2009-10-29

    The accuracy of first-order Euler and higher-order time-integration algorithms for grid-based Langevin equations collision models in a specific relaxation test problem is assessed. We show that statistical noise errors can overshadow time-step errors and argue that statistical noise errors can be conflated with time-step effects. Using a higher-order integration scheme may not achieve any benefit in accuracy for examples of practical interest. We also investigate the collisional relaxation of an initial electron-ion relative drift and the collisional relaxation to a resistive steady-state in which a quasi-steady current is driven by a constant applied electric field, as functions of the time step used to resolve the collision processes using binary and grid-based, test-particle Langevin equations models. We compare results from two grid-based Langevin equations collision algorithms to results from a binary collision algorithm for modeling electronion collisions. Some guidance is provided regarding how large a time step can be used compared to the inverse of the characteristic collision frequency for specific relaxation processes.

  6. The large discretization step method for time-dependent partial differential equations

    NASA Technical Reports Server (NTRS)

    Haras, Zigo; Taasan, Shlomo

    1995-01-01

    A new method for the acceleration of linear and nonlinear time dependent calculations is presented. It is based on the Large Discretization Step (LDS) approximation, defined in this work, which employs an extended system of low accuracy schemes to approximate a high accuracy discrete approximation to a time dependent differential operator. Error bounds on such approximations are derived. These approximations are efficiently implemented in the LDS methods for linear and nonlinear hyperbolic equations, presented here. In these algorithms the high and low accuracy schemes are interpreted as the same discretization of a time dependent operator on fine and coarse grids, respectively. Thus, a system of correction terms and corresponding equations are derived and solved on the coarse grid to yield the fine grid accuracy. These terms are initialized by visiting the fine grid once in many coarse grid time steps. The resulting methods are very general, simple to implement and may be used to accelerate many existing time marching schemes.

  7. Simulating diffusion processes in discontinuous media: A numerical scheme with constant time steps

    SciTech Connect

    Lejay, Antoine; Pichot, Geraldine

    2012-08-30

    In this article, we propose new Monte Carlo techniques for moving a diffusive particle in a discontinuous media. In this framework, we characterize the stochastic process that governs the positions of the particle. The key tool is the reduction of the process to a Skew Brownian motion (SBM). In a zone where the coefficients are locally constant on each side of the discontinuity, the new position of the particle after a constant time step is sampled from the exact distribution of the SBM process at the considered time. To do so, we propose two different but equivalent algorithms: a two-steps simulation with a stop at the discontinuity and a one-step direct simulation of the SBM dynamic. Some benchmark tests illustrate their effectiveness.

  8. Suggestions for CAP-TSD mesh and time-step input parameters

    NASA Technical Reports Server (NTRS)

    Bland, Samuel R.

    1991-01-01

    Suggestions for some of the input parameters used in the CAP-TSD (Computational Aeroelasticity Program-Transonic Small Disturbance) computer code are presented. These parameters include those associated with the mesh design and time step. The guidelines are based principally on experience with a one-dimensional model problem used to study wave propagation in the vertical direction.

  9. Adaptive time stepping algorithm for Lagrangian transport models: Theory and idealised test cases

    NASA Astrophysics Data System (ADS)

    Shah, Syed Hyder Ali Muttaqi; Heemink, Arnold Willem; Gräwe, Ulf; Deleersnijder, Eric

    2013-08-01

    Random walk simulations have an excellent potential in marine and oceanic modelling. This is essentially due to their relative simplicity and their ability to represent advective transport without being plagued by the deficiencies of the Eulerian methods. The physical and mathematical foundations of random walk modelling of turbulent diffusion have become solid over the years. Random walk models rest on the theory of stochastic differential equations. Unfortunately, the latter and the related numerical aspects have not attracted much attention in the oceanic modelling community. The main goal of this paper is to help bridge the gap by developing an efficient adaptive time stepping algorithm for random walk models. Its performance is examined on two idealised test cases of turbulent dispersion; (i) pycnocline crossing and (ii) non-flat isopycnal diffusion, which are inspired by shallow-sea dynamics and large-scale ocean transport processes, respectively. The numerical results of the adaptive time stepping algorithm are compared with the fixed-time increment Milstein scheme, showing that the adaptive time stepping algorithm for Lagrangian random walk models is more efficient than its fixed step-size counterpart without any loss in accuracy.

  10. Dependence of Hurricane intensity and structures on vertical resolution and time-step size

    NASA Astrophysics Data System (ADS)

    Zhang, Da-Lin; Wang, Xiaoxue

    2003-09-01

    In view of the growing interests in the explicit modeling of clouds and precipitation, the effects of varying vertical resolution and time-step sizes on the 72-h explicit simulation of Hurricane Andrew (1992) are studied using the Pennsylvania State University/National Center for Atmospheric Research (PSU/NCAR) mesoscale model (i.e., MM5) with the finest grid size of 6 km. It is shown that changing vertical resolution and time-step size has significant effects on hurricane intensity and inner-core cloud/precipitation, but little impact on the hurricane track. In general, increasing vertical resolution tends to produce a deeper storm with lower central pressure and stronger three-dimensional winds, and more precipitation. Similar effects, but to a less extent, occur when the time-step size is reduced. It is found that increasing the low-level vertical resolution is more efficient in intensifying a hurricane, whereas changing the upper-level vertical resolution has little impact on the hurricane intensity. Moreover, the use of a thicker surface layer tends to produce higher maximum surface winds. It is concluded that the use of higher vertical resolution, a thin surface layer, and smaller time-step sizes, along with higher horizontal resolution, is desirable to model more realistically the intensity and inner-core structures and evolution of tropical storms as well as the other convectively driven weather systems.

  11. Causal-Path Local Time-Stepping in the discontinuous Galerkin method for Maxwell's equations

    NASA Astrophysics Data System (ADS)

    Angulo, L. D.; Alvarez, J.; Teixeira, F. L.; Pantoja, M. F.; Garcia, S. G.

    2014-01-01

    We introduce a novel local time-stepping technique for marching-in-time algorithms. The technique is denoted as Causal-Path Local Time-Stepping (CPLTS) and it is applied for two time integration techniques: fourth-order low-storage explicit Runge-Kutta (LSERK4) and second-order Leap-Frog (LF2). The CPLTS method is applied to evolve Maxwell's curl equations using a Discontinuous Galerkin (DG) scheme for the spatial discretization. Numerical results for LF2 and LSERK4 are compared with analytical solutions and the Montseny's LF2 technique. The results show that the CPLTS technique improves the dispersive and dissipative properties of LF2-LTS scheme.

  12. Development of a variable time-step transient NEW code: SPANDEX

    SciTech Connect

    Aviles, B.N. )

    1993-01-01

    This paper describes a three-dimensional, variable time-step transient multigroup diffusion theory code, SPANDEX (space-time nodal expansion method). SPANDEX is based on the static nodal expansion method (NEM) code, NODEX (Ref. 1), and employs a nonlinear algorithm and a fifth-order expansion of the transverse-integrated fluxes. The time integration scheme in SPANDEX is a fourth-order implicit generalized Runge-Kutta method (GRK) with on-line error control and variable time-step selection. This Runge-Kutta method has been applied previously to point kinetics and one-dimensional finite difference transient analysis. This paper describes the application of the Runge-Kutta method to three-dimensional reactor transient analysis in a multigroup NEM code.

  13. Promoting rest using a quiet time innovation in an adult neuroscience step down unit.

    PubMed

    Bergner, Tara

    2014-01-01

    Sleep and rest are fundamental for the restoration of energy needed to recuperate from illness, trauma and surgery. At present hospitals are too noisy to promote rest for patients. A literature search produced research that described how quiet time interventions addressing noise levels have met with positive patient and staff satisfaction, as well as creating a more peaceful and healing environment. In this paper, a description of the importance of quiet time and how a small butfeasible innovation was carried out in an adult neuroscience step down unit in a large tertiary health care facility in Canada is provided. Anecdotal evidence from patients, families, and staff suggests that quiet time may have positive effects for patients, their families, and the adult neuroscience step down unit staff Future research examining the effect of quiet time on patient, family and staff satisfaction and patient healing is necessary. PMID:25638912

  14. Time-stepping stability of continuous and discontinuous finite-element methods for 3-D wave propagation

    NASA Astrophysics Data System (ADS)

    Mulder, W. A.; Zhebel, E.; Minisini, S.

    2014-02-01

    We analyse the time-stepping stability for the 3-D acoustic wave equation, discretized on tetrahedral meshes. Two types of methods are considered: mass-lumped continuous finite elements and the symmetric interior-penalty discontinuous Galerkin method. Combining the spatial discretization with the leap-frog time-stepping scheme, which is second-order accurate and conditionally stable, leads to a fully explicit scheme. We provide estimates of its stability limit for simple cases, namely, the reference element with Neumann boundary conditions, its distorted version of arbitrary shape, the unit cube that can be partitioned into six tetrahedra with periodic boundary conditions and its distortions. The Courant-Friedrichs-Lewy stability limit contains an element diameter for which we considered different options. The one based on the sum of the eigenvalues of the spatial operator for the first-degree mass-lumped element gives the best results. It resembles the diameter of the inscribed sphere but is slightly easier to compute. The stability estimates show that the mass-lumped continuous and the discontinuous Galerkin finite elements of degree 2 have comparable stability conditions, whereas the mass-lumped elements of degree one and three allow for larger time steps.

  15. A multiple time stepping algorithm for efficient multiscale modeling of platelets flowing in blood plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Zhang, Na; Deng, Yuefan; Bluestein, Danny

    2015-03-01

    We developed a multiple time-stepping (MTS) algorithm for multiscale modeling of the dynamics of platelets flowing in viscous blood plasma. This MTS algorithm improves considerably the computational efficiency without significant loss of accuracy. This study of the dynamic properties of flowing platelets employs a combination of the dissipative particle dynamics (DPD) and the coarse-grained molecular dynamics (CGMD) methods to describe the dynamic microstructures of deformable platelets in response to extracellular flow-induced stresses. The disparate spatial scales between the two methods are handled by a hybrid force field interface. However, the disparity in temporal scales between the DPD and CGMD that requires time stepping at microseconds and nanoseconds respectively, represents a computational challenge that may become prohibitive. Classical MTS algorithms manage to improve computing efficiency by multi-stepping within DPD or CGMD for up to one order of magnitude of scale differential. In order to handle 3-4 orders of magnitude disparity in the temporal scales between DPD and CGMD, we introduce a new MTS scheme hybridizing DPD and CGMD by utilizing four different time stepping sizes. We advance the fluid system at the largest time step, the fluid-platelet interface at a middle timestep size, and the nonbonded and bonded potentials of the platelet structural system at two smallest timestep sizes. Additionally, we introduce parameters to study the relationship of accuracy versus computational complexities. The numerical experiments demonstrated 3000x reduction in computing time over standard MTS methods for solving the multiscale model. This MTS algorithm establishes a computationally feasible approach for solving a particle-based system at multiple scales for performing efficient multiscale simulations.

  16. A Multiple Time Stepping Algorithm for Efficient Multiscale Modeling of Platelets Flowing in Blood Plasma

    PubMed Central

    Zhang, Peng; Zhang, Na; Deng, Yuefan; Bluestein, Danny

    2015-01-01

    We developed a multiple time-stepping (MTS) algorithm for multiscale modeling of the dynamics of platelets flowing in viscous blood plasma. This MTS algorithm improves considerably the computational efficiency without significant loss of accuracy. This study of the dynamic properties of flowing platelets employs a combination of the dissipative particle dynamics (DPD) and the coarse-grained molecular dynamics (CGMD) methods to describe the dynamic microstructures of deformable platelets in response to extracellular flow-induced stresses. The disparate spatial scales between the two methods are handled by a hybrid force field interface. However, the disparity in temporal scales between the DPD and CGMD that requires time stepping at microseconds and nanoseconds respectively, represents a computational challenge that may become prohibitive. Classical MTS algorithms manage to improve computing efficiency by multi-stepping within DPD or CGMD for up to one order of magnitude of scale differential. In order to handle 3–4 orders of magnitude disparity in the temporal scales between DPD and CGMD, we introduce a new MTS scheme hybridizing DPD and CGMD by utilizing four different time stepping sizes. We advance the fluid system at the largest time step, the fluid-platelet interface at a middle timestep size, and the nonbonded and bonded potentials of the platelet structural system at two smallest timestep sizes. Additionally, we introduce parameters to study the relationship of accuracy versus computational complexities. The numerical experiments demonstrated 3000x reduction in computing time over standard MTS methods for solving the multiscale model. This MTS algorithm establishes a computationally feasible approach for solving a particle-based system at multiple scales for performing efficient multiscale simulations. PMID:25641983

  17. An implicit time-stepping scheme for rigid body dynamics with Coulomb friction

    SciTech Connect

    STEWART,DAVID; TRINKLE,JEFFREY C.

    2000-02-15

    In this paper a new time-stepping method for simulating systems of rigid bodies is given. Unlike methods which take an instantaneous point of view, the method is based on impulse-momentum equations, and so does not need to explicitly resolve impulsive forces. On the other hand, the method is distinct from previous impulsive methods in that it does not require explicit collision checking and it can handle simultaneous impacts. Numerical results are given for one planar and one three-dimensional example, which demonstrate the practicality of the method, and its convergence as the step size becomes small.

  18. Inertial stochastic dynamics. I. Long-time-step methods for Langevin dynamics

    NASA Astrophysics Data System (ADS)

    Beard, Daniel A.; Schlick, Tamar

    2000-05-01

    Two algorithms are presented for integrating the Langevin dynamics equation with long numerical time steps while treating the mass terms as finite. The development of these methods is motivated by the need for accurate methods for simulating slow processes in polymer systems such as two-site intermolecular distances in supercoiled DNA, which evolve over the time scale of milliseconds. Our new approaches refine the common Brownian dynamics (BD) scheme, which approximates the Langevin equation in the highly damped diffusive limit. Our LTID ("long-time-step inertial dynamics") method is based on an eigenmode decomposition of the friction tensor. The less costly integrator IBD ("inertial Brownian dynamics") modifies the usual BD algorithm by the addition of a mass-dependent correction term. To validate the methods, we evaluate the accuracy of LTID and IBD and compare their behavior to that of BD for the simple example of a harmonic oscillator. We find that the LTID method produces the expected correlation structure for Langevin dynamics regardless of the level of damping. In fact, LTID is the only consistent method among the three, with error vanishing as the time step approaches zero. In contrast, BD is accurate only for highly overdamped systems. For cases of moderate overdamping, and for the appropriate choice of time step, IBD is significantly more accurate than BD. IBD is also less computationally expensive than LTID (though both are the same order of complexity as BD), and thus can be applied to simulate systems of size and time scale ranges previously accessible to only the usual BD approach. Such simulations are discussed in our companion paper, for long DNA molecules modeled as wormlike chains.

  19. High-Order Implicit-Explicit Multi-Block Time-stepping Method for Hyperbolic PDEs

    NASA Technical Reports Server (NTRS)

    Nielsen, Tanner B.; Carpenter, Mark H.; Fisher, Travis C.; Frankel, Steven H.

    2014-01-01

    This work seeks to explore and improve the current time-stepping schemes used in computational fluid dynamics (CFD) in order to reduce overall computational time. A high-order scheme has been developed using a combination of implicit and explicit (IMEX) time-stepping Runge-Kutta (RK) schemes which increases numerical stability with respect to the time step size, resulting in decreased computational time. The IMEX scheme alone does not yield the desired increase in numerical stability, but when used in conjunction with an overlapping partitioned (multi-block) domain significant increase in stability is observed. To show this, the Overlapping-Partition IMEX (OP IMEX) scheme is applied to both one-dimensional (1D) and two-dimensional (2D) problems, the nonlinear viscous Burger's equation and 2D advection equation, respectively. The method uses two different summation by parts (SBP) derivative approximations, second-order and fourth-order accurate. The Dirichlet boundary conditions are imposed using the Simultaneous Approximation Term (SAT) penalty method. The 6-stage additive Runge-Kutta IMEX time integration schemes are fourth-order accurate in time. An increase in numerical stability 65 times greater than the fully explicit scheme is demonstrated to be achievable with the OP IMEX method applied to 1D Burger's equation. Results from the 2D, purely convective, advection equation show stability increases on the order of 10 times the explicit scheme using the OP IMEX method. Also, the domain partitioning method in this work shows potential for breaking the computational domain into manageable sizes such that implicit solutions for full three-dimensional CFD simulations can be computed using direct solving methods rather than the standard iterative methods currently used.

  20. Daily Time Step Refinement of Optimized Flood Control Rule Curves for a Global Warming Scenario

    NASA Astrophysics Data System (ADS)

    Lee, S.; Fitzgerald, C.; Hamlet, A. F.; Burges, S. J.

    2009-12-01

    Pacific Northwest temperatures have warmed by 0.8 °C since 1920 and are predicted to further increase in the 21st century. Simulated streamflow timing shifts associated with climate change have been found in past research to degrade water resources system performance in the Columbia River Basin when using existing system operating policies. To adapt to these hydrologic changes, optimized flood control operating rule curves were developed in a previous study using a hybrid optimization-simulation approach which rebalanced flood control and reservoir refill at a monthly time step. For the climate change scenario, use of the optimized flood control curves restored reservoir refill capability without increasing flood risk. Here we extend the earlier studies using a detailed daily time step simulation model applied over a somewhat smaller portion of the domain (encompassing Libby, Duncan, and Corra Linn dams, and Kootenai Lake) to evaluate and refine the optimized flood control curves derived from monthly time step analysis. Moving from a monthly to daily analysis, we found that the timing of flood control evacuation needed adjustment to avoid unintended outcomes affecting Kootenai Lake. We refined the flood rule curves derived from monthly analysis by creating a more gradual evacuation schedule, but kept the timing and magnitude of maximum evacuation the same as in the monthly analysis. After these refinements, the performance at monthly time scales reported in our previous study proved robust at daily time scales. Due to a decrease in July storage deficits, additional benefits such as more revenue from hydropower generation and more July and August outflow for fish augmentation were observed when the optimized flood control curves were used for the climate change scenario.

  1. Schwarz type domain decomposition and subcycling multi-time step approach for solving Richards equation

    NASA Astrophysics Data System (ADS)

    Kuraz, Michal

    2016-06-01

    Modelling the transport processes in a vadose zone, e.g. modelling contaminant transport or the effect of the soil water regime on changes in soil structure and composition, plays an important role in predicting the reactions of soil biotopes to anthropogenic activity. Water flow is governed by the quasilinear Richards equation. The paper concerns the implementation of a multi-time-step approach for solving a nonlinear Richards equation. When modelling porous media flow with a Richards equation, due to a possible convection dominance and a convergence of a nonlinear solver, a stable finite element approximation requires accurate temporal and spatial integration. The method presented here enables adaptive domain decomposition algorithm together with a multi-time-step treatment of actively changing subdomains.

  2. Manual for implementing a Shared Time Engineering Program (STEP) September 1980 through September 1983

    NASA Astrophysics Data System (ADS)

    Aronoff, H. I.; Leslie, J. J.; Mittleman, A. N.; Holt, S.

    1983-11-01

    This manual describes a Shared Time Engineering Program (STEP) conducted by the New England Apparel Manufacturers Association (NEAMA) headquartered in Fall River Massachusetts, and funded by the Office of Trade Adjustment Assistance of the U.S. Department of Commerce. It is addressed to industry association executives, industrial engineers and others interested in examining an innovative model of industrial engineering assistance to small plants which might be adapted to their particular needs.

  3. Accuracy of Pedometer Steps and Time for Youth with Intellectual Disabilities during Dynamic Movements

    ERIC Educational Resources Information Center

    Pitetti, Kenneth H.; Beets, Michael W.; Flaming, Judy

    2009-01-01

    Pedometer accuracy for steps and activity time during dynamic movement for youth with intellectual disabilities (ID) were examined. Twenty-four youth with ID (13 girls, 13.1 [plus or minus] 3.2 yrs; 11 boys, 14.7 [plus or minus] 2.7 yrs) were videotaped during adapted physical education class while wearing a Walk4Life 2505 pedometer in five…

  4. Multiple Time-Step Dual-Hamiltonian Hybrid Molecular Dynamics - Monte Carlo Canonical Propagation Algorithm.

    PubMed

    Chen, Yunjie; Kale, Seyit; Weare, Jonathan; Dinner, Aaron R; Roux, Benoît

    2016-04-12

    A multiple time-step integrator based on a dual Hamiltonian and a hybrid method combining molecular dynamics (MD) and Monte Carlo (MC) is proposed to sample systems in the canonical ensemble. The Dual Hamiltonian Multiple Time-Step (DHMTS) algorithm is based on two similar Hamiltonians: a computationally expensive one that serves as a reference and a computationally inexpensive one to which the workload is shifted. The central assumption is that the difference between the two Hamiltonians is slowly varying. Earlier work has shown that such dual Hamiltonian multiple time-step schemes effectively precondition nonlinear differential equations for dynamics by reformulating them into a recursive root finding problem that can be solved by propagating a correction term through an internal loop, analogous to RESPA. Of special interest in the present context, a hybrid MD-MC version of the DHMTS algorithm is introduced to enforce detailed balance via a Metropolis acceptance criterion and ensure consistency with the Boltzmann distribution. The Metropolis criterion suppresses the discretization errors normally associated with the propagation according to the computationally inexpensive Hamiltonian, treating the discretization error as an external work. Illustrative tests are carried out to demonstrate the effectiveness of the method. PMID:26918826

  5. Multiple Time-Step Dual-Hamiltonian Hybrid Molecular Dynamics — Monte Carlo Canonical Propagation Algorithm

    PubMed Central

    Weare, Jonathan; Dinner, Aaron R.; Roux, Benoît

    2016-01-01

    A multiple time-step integrator based on a dual Hamiltonian and a hybrid method combining molecular dynamics (MD) and Monte Carlo (MC) is proposed to sample systems in the canonical ensemble. The Dual Hamiltonian Multiple Time-Step (DHMTS) algorithm is based on two similar Hamiltonians: a computationally expensive one that serves as a reference and a computationally inexpensive one to which the workload is shifted. The central assumption is that the difference between the two Hamiltonians is slowly varying. Earlier work has shown that such dual Hamiltonian multiple time-step schemes effectively precondition nonlinear differential equations for dynamics by reformulating them into a recursive root finding problem that can be solved by propagating a correction term through an internal loop, analogous to RESPA. Of special interest in the present context, a hybrid MD-MC version of the DHMTS algorithm is introduced to enforce detailed balance via a Metropolis acceptance criterion and ensure consistency with the Boltzmann distribution. The Metropolis criterion suppresses the discretization errors normally associated with the propagation according to the computationally inexpensive Hamiltonian, treating the discretization error as an external work. Illustrative tests are carried out to demonstrate the effectiveness of the method. PMID:26918826

  6. Real-Time, Single-Step Bioassay Using Nanoplasmonic Resonator With Ultra-High Sensitivity

    NASA Technical Reports Server (NTRS)

    Zhang, Xiang (Inventor); Ellman, Jonathan A. (Inventor); Chen, Fanqing Frank (Inventor); Su, Kai-Hang (Inventor); Wei, Qi-Huo (Inventor); Sun, Cheng (Inventor)

    2014-01-01

    A nanoplasmonic resonator (NPR) comprising a metallic nanodisk with alternating shielding layer(s), having a tagged biomolecule conjugated or tethered to the surface of the nanoplasmonic resonator for highly sensitive measurement of enzymatic activity. NPRs enhance Raman signals in a highly reproducible manner, enabling fast detection of protease and enzyme activity, such as Prostate Specific Antigen (paPSA), in real-time, at picomolar sensitivity levels. Experiments on extracellular fluid (ECF) from paPSA-positive cells demonstrate specific detection in a complex bio-fluid background in real-time single-step detection in very small sample volumes.

  7. Real-time, single-step bioassay using nanoplasmonic resonator with ultra-high sensitivity

    DOEpatents

    Zhang, Xiang; Ellman, Jonathan A; Chen, Fanqing Frank; Su, Kai-Hang; Wei, Qi-Huo; Sun, Cheng

    2014-04-01

    A nanoplasmonic resonator (NPR) comprising a metallic nanodisk with alternating shielding layer(s), having a tagged biomolecule conjugated or tethered to the surface of the nanoplasmonic resonator for highly sensitive measurement of enzymatic activity. NPRs enhance Raman signals in a highly reproducible manner, enabling fast detection of protease and enzyme activity, such as Prostate Specific Antigen (paPSA), in real-time, at picomolar sensitivity levels. Experiments on extracellular fluid (ECF) from paPSA-positive cells demonstrate specific detection in a complex bio-fluid background in real-time single-step detection in very small sample volumes.

  8. Moment tensor inversion of waveforms: a two-step time-frequency approach

    NASA Astrophysics Data System (ADS)

    Vavryčuk, Václav; Kühn, Daniela

    2012-09-01

    We present a moment tensor inversion of waveforms, which is more robust and yields more stable and more accurate results than standard approaches. The inversion is performed in two steps and combines inversions in time and frequency domains. First, the inversion for the source-time function is performed in the frequency domain using complex spectra. Second, the time-domain inversion for the moment tensor is performed using the source-time function calculated in the first step. In this way, we can consider a realistic, complex source-time function and still keep the final moment tensor inversion linear. Using numerical modelling, we compare the efficiency and accuracy of the proposed approach with standard waveform inversions. We study the sensitivity of the retrieved double-couple and non-double-couple components of the moment tensors to noise in the data, to inaccuracies of the location and of the velocity model, and to the type of the focal mechanism. Finally, the proposed moment tensor inversion is tested on real data observed in a complex 3-D inhomogeneous geological environment: a production blast and a rockburst in the Pyhäsalmi ore mine, Finland.

  9. A novel adaptive time stepping variant of the Boris–Buneman integrator for the simulation of particle accelerators with space charge

    SciTech Connect

    Toggweiler, Matthias; Adelmann, Andreas; Arbenz, Peter; Yang, Jianjun

    2014-09-15

    We show that adaptive time stepping in particle accelerator simulation is an enhancement for certain problems. The new algorithm has been implemented in the OPAL (Object Oriented Parallel Accelerator Library) framework. The idea is to adjust the frequency of costly self-field calculations, which are needed to model Coulomb interaction (space charge) effects. In analogy to a Kepler orbit simulation that requires a higher time step resolution at the close encounter, we propose to choose the time step based on the magnitude of the space charge forces. Inspired by geometric integration techniques, our algorithm chooses the time step proportional to a function of the current phase space state instead of calculating a local error estimate like a conventional adaptive procedure. Building on recent work, a more profound argument is given on how exactly the time step should be chosen. An intermediate algorithm, initially built to allow a clearer analysis by introducing separate time steps for external field and self-field integration, turned out to be useful by its own, for a large class of problems.

  10. Oscillation-Driven Spike-Timing Dependent Plasticity Allows Multiple Overlapping Pattern Recognition in Inhibitory Interneuron Networks.

    PubMed

    Garrido, Jesús A; Luque, Niceto R; Tolu, Silvia; D'Angelo, Egidio

    2016-08-01

    The majority of operations carried out by the brain require learning complex signal patterns for future recognition, retrieval and reuse. Although learning is thought to depend on multiple forms of long-term synaptic plasticity, the way this latter contributes to pattern recognition is still poorly understood. Here, we have used a simple model of afferent excitatory neurons and interneurons with lateral inhibition, reproducing a network topology found in many brain areas from the cerebellum to cortical columns. When endowed with spike-timing dependent plasticity (STDP) at the excitatory input synapses and at the inhibitory interneuron-interneuron synapses, the interneurons rapidly learned complex input patterns. Interestingly, induction of plasticity required that the network be entrained into theta-frequency band oscillations, setting the internal phase-reference required to drive STDP. Inhibitory plasticity effectively distributed multiple patterns among available interneurons, thus allowing the simultaneous detection of multiple overlapping patterns. The addition of plasticity in intrinsic excitability made the system more robust allowing self-adjustment and rescaling in response to a broad range of input patterns. The combination of plasticity in lateral inhibitory connections and homeostatic mechanisms in the inhibitory interneurons optimized mutual information (MI) transfer. The storage of multiple complex patterns in plastic interneuron networks could be critical for the generation of sparse representations of information in excitatory neuron populations falling under their control. PMID:27079422

  11. A shorter time step for eco-friendly reservoir operation does not always produce better water availability and ecosystem benefits

    NASA Astrophysics Data System (ADS)

    Yu, Chunxue; Yin, Xin'an; Yang, Zhifeng; Cai, Yanpeng; Sun, Tao

    2016-09-01

    The time step used in the operation of eco-friendly reservoirs has decreased from monthly to daily, and even sub-daily. The shorter time step is considered a better choice for satisfying downstream environmental requirements because it more closely resembles the natural flow regime. However, little consideration has been given to the influence of different time steps on the ability to simultaneously meet human and environmental flow requirements. To analyze this influence, we used an optimization model to explore the relationships among the time step, environmental flow (e-flow) requirements, and human water needs for a wide range of time steps and e-flow scenarios. We used the degree of hydrologic alteration to evaluate the regime's ability to satisfy the e-flow requirements of riverine ecosystems, and used water supply reliability to evaluate the ability to satisfy human needs. We then applied the model to a case study of China's Tanghe Reservoir. We found four efficient time steps (2, 3, 4, and 5 days), with a remarkably high water supply reliability (around 80%) and a low alteration of the flow regime (<35%). Our analysis of the hydrologic alteration revealed the smallest alteration at time steps ranging from 1 to 7 days. However, longer time steps led to higher water supply reliability to meet human needs under several e-flow scenarios. Our results show that adjusting the time step is a simple way to improve reservoir operation performance to balance human and e-flow needs.

  12. Sensitivity of The High-resolution Wam Model With Respect To Time Step

    NASA Astrophysics Data System (ADS)

    Kasemets, K.; Soomere, T.

    The northern part of the Baltic Proper and its subbasins (Bothnian Sea, the Gulf of Finland, Moonsund) serve as a challenge for wave modellers. In difference from the southern and the eastern parts of the Baltic Sea, their coasts are highly irregular and contain many peculiarities with the characteristic horizontal scale of the order of a few kilometres. For example, the northern coast of the Gulf of Finland is extremely ragged and contains a huge number of small islands. Its southern coast is more or less regular but has up to 50m high cliff that is frequently covered by high forests. The area also contains numerous banks that have water depth a couple of meters and that may essentially modify wave properties near the banks owing to topographical effects. This feature suggests that a high-resolution wave model should be applied for the region in question, with a horizontal resolution of an order of 1 km or even less. According to the Courant-Friedrich-Lewy criterion, the integration time step for such models must be of the order of a few tens of seconds. A high-resolution WAM model turns out to be fairly sensitive with respect to the particular choice of the time step. In our experiments, a medium-resolution model for the whole Baltic Sea was used, with the horizontal resolution 3 miles (3' along latitudes and 6' along longitudes) and the angular resolution 12 directions. The model was run with steady wind blowing 20 m/s from different directions and with two time steps (1 and 3 minutes). For most of the wind directions, the rms. difference of significant wave heights calculated with differ- ent time steps did not exceed 10 cm and typically was of the order of a few per cents. The difference arose within a few tens of minutes and generally did not increase in further computations. However, in the case of the north wind, the difference increased nearly monotonously and reached 25-35 cm (10-15%) within three hours of integra- tion whereas mean of significant wave

  13. BIOMAP A Daily Time Step, Mechanistic Model for the Study of Ecosystem Dynamics

    NASA Astrophysics Data System (ADS)

    Wells, J. R.; Neilson, R. P.; Drapek, R. J.; Pitts, B. S.

    2010-12-01

    BIOMAP simulates competition between two Plant Functional Types (PFT) at any given point in the conterminous U.S. using a time series of daily temperature (mean, minimum, maximum), precipitation, humidity, light and nutrients, with PFT-specific rooting within a multi-layer soil. The model employs a 2-layer canopy biophysics, Farquhar photosynthesis, the Beer-Lambert Law for light attenuation and a mechanistic soil hydrology. In essence, BIOMAP is a re-built version of the biogeochemistry model, BIOME-BGC, into the form of the MAPSS biogeography model. Specific enhancements are: 1) the 2-layer canopy biophysics of Dolman (1993); 2) the unique MAPSS-based hydrology, which incorporates canopy evaporation, snow dynamics, infiltration and saturated and unsaturated percolation with ‘fast’ flow and base flow and a ‘tunable aquifer’ capacity, a metaphor of D’Arcy’s Law; and, 3) a unique MAPSS-based stomatal conductance algorithm, which simultaneously incorporates vapor pressure and soil water potential constraints, based on physiological information and many other improvements. Over small domains the PFTs can be parameterized as individual species to investigate fundamental vs. potential niche theory; while, at more coarse scales the PFTs can be rendered as more general functional groups. Since all of the model processes are intrinsically leaf to plot scale (physiology to PFT competition), it essentially has no ‘intrinsic’ scale and can be implemented on a grid of any size, taking on the characteristics defined by the homogeneous climate of each grid cell. Currently, the model is implemented on the VEMAP 1/2 degree, daily grid over the conterminous U.S. Although both the thermal and water-limited ecotones are dynamic, following climate variability, the PFT distributions remain fixed. Thus, the model is currently being fitted with a ‘reproduction niche’ to allow full dynamic operation as a Dynamic General Vegetation Model (DGVM). While global simulations

  14. System for direct measurement of the step response of electronic devices on the picosecond time scale

    NASA Astrophysics Data System (ADS)

    Sheridan, J. A.; Bloom, D. M.; Solomon, P. M.

    1995-03-01

    We have built a system capable of measuring the step response of III-V electronic devices on the picosecond time scale, with no alteration in device design or epitaxy. To switch on the device under test (DUT), we have designed and fabricated a new type of photoconductor, the recessed-ohmic photoconductor, which swings 0.45 V with a 2-ps rise time and maintains constant output voltage for 100 ps. This switch is monolithically integrated with the DUT. To measure the output current of the DUT, we have built a Ti:sapphire-laser-based pump-probe direct electro-optic sampling system that has a minimum detectable voltage of 70 mu V / \\radical Hz \\end-radical and a measurement bandwidth of 750 GHz. The overall system, comprised of the recessed ohmic photoconductor and the electro-optic sampling system, can be used to measure the step response of III-V electronic devices on the picosecond time scale.

  15. A class of large time step Godunov schemes for hyperbolic conservation laws and applications

    NASA Astrophysics Data System (ADS)

    Qian, ZhanSen; Lee, Chun-Hian

    2011-08-01

    A large time step (LTS) Godunov scheme firstly proposed by LeVeque is further developed in the present work and applied to Euler equations. Based on the analysis of the computational performances of LeVeque's linear approximation on wave interactions, a multi-wave approximation on rarefaction fan is proposed to avoid the occurrences of rarefaction shocks in computations. The developed LTS scheme is validated using 1-D test cases, manifesting high resolution for discontinuities and the capability of maintaining computational stability when large CFL numbers are imposed. The scheme is then extended to multidimensional problems using dimensional splitting technique; the treatment of boundary condition for this multidimensional LTS scheme is also proposed. As for demonstration problems, inviscid flows over NACA0012 airfoil and ONERA M6 wing with given swept angle are simulated using the developed LTS scheme. The numerical results reveal the high resolution nature of the scheme, where the shock can be captured within 1-2 grid points. The resolution of the scheme would improve gradually along with the increasing of CFL number under an upper bound where the solution becomes severely oscillating across the shock. Computational efficiency comparisons show that the developed scheme is capable of reducing the computational time effectively with increasing the time step (CFL number).

  16. A multistage time-stepping scheme for the Navier-Stokes equations

    NASA Technical Reports Server (NTRS)

    Swanson, R. C.; Turkel, E.

    1985-01-01

    A class of explicit multistage time-stepping schemes is used to construct an algorithm for solving the compressible Navier-Stokes equations. Flexibility in treating arbitrary geometries is obtained with a finite-volume formulation. Numerical efficiency is achieved by employing techniques for accelerating convergence to steady state. Computer processing is enhanced through vectorization of the algorithm. The scheme is evaluated by solving laminar and turbulent flows over a flat plate and an NACA 0012 airfoil. Numerical results are compared with theoretical solutions or other numerical solutions and/or experimental data.

  17. Imaginary Time Step Method to Solve the Dirac Equation with Nonlocal Potential

    SciTech Connect

    Zhang Ying; Liang Haozhao; Meng Jie

    2009-08-26

    The imaginary time step (ITS) method is applied to solve the Dirac equation with nonlocal potentials in coordinate space. Taking the nucleus {sup 12}C as an example, even with nonlocal potentials, the direct ITS evolution for the Dirac equation still meets the disaster of the Dirac sea. However, following the recipe in our former investigation, the disaster can be avoided by the ITS evolution for the corresponding Schroedinger-like equation without localization, which gives the convergent results exactly the same with those obtained iteratively by the shooting method with localized effective potentials.

  18. Multiple time step molecular dynamics in the optimized isokinetic ensemble steered with the molecular theory of solvation: Accelerating with advanced extrapolation of effective solvation forces

    SciTech Connect

    Omelyan, Igor E-mail: omelyan@icmp.lviv.ua; Kovalenko, Andriy

    2013-12-28

    steered by effective solvation forces allows huge outer time steps up to tens of picoseconds without affecting the equilibrium and conformational properties, and thus provides a 100- to 500-fold effective speedup in comparison to conventional MD with explicit solvent. With the statistical-mechanical 3D-RISM-KH account for effective solvation forces, the method provides efficient sampling of biomolecular processes with slow and/or rare solvation events such as conformational transitions of hydrated alanine dipeptide with the mean life times ranging from 30 ps up to 10 ns for “flip-flop” conformations, and is particularly beneficial for biomolecular systems with exchange and localization of solvent and ions, ligand binding, and molecular recognition.

  19. A simple method for improving the time-stepping accuracy in atmosphere and ocean models

    NASA Astrophysics Data System (ADS)

    Williams, P. D.

    2012-12-01

    In contemporary numerical simulations of the atmosphere and ocean, evidence suggests that time-stepping errors may be a significant component of total model error, on both weather and climate time-scales. This presentation will review the available evidence, and will then suggest a simple but effective method for substantially improving the time-stepping numerics at no extra computational expense. A common time-stepping method in atmosphere and ocean models is the leapfrog scheme combined with the Robert-Asselin (RA) filter. This method is used in the following models (and many more): ECHAM, MAECHAM, MM5, CAM, MESO-NH, HIRLAM, KMCM, LIMA, SPEEDY, IGCM, PUMA, COSMO, FSU-GSM, FSU-NRSM, NCEP-GFS, NCEP-RSM, NSEAM, NOGAPS, RAMS, and CCSR/NIES-AGCM. Although the RA filter controls the time-splitting instability, it also introduces non-physical damping and reduces the accuracy. This presentation proposes a simple modification to the RA filter, which has become known as the RAW filter (Williams 2009, 2011). When used in conjunction with the leapfrog scheme, the RAW filter eliminates the non-physical damping and increases the amplitude accuracy by two orders, yielding third-order accuracy. (The phase accuracy remains second-order.) The RAW filter can easily be incorporated into existing models, typically via the insertion of just a single line of code. Better simulations are obtained at no extra computational expense. Results will be shown from recent implementations of the RAW filter in various models, including SPEEDY and COSMO. For example, in SPEEDY, the skill of weather forecasts is found to be significantly improved. In particular, in tropical surface pressure predictions, five-day forecasts made using the RAW filter have approximately the same skill as four-day forecasts made using the RA filter (Amezcua, Kalnay & Williams 2011). These improvements are encouraging for the use of the RAW filter in other atmosphere and ocean models. References PD Williams (2009) A

  20. One-Step Direct Aeroacoustic Simulation Using Space-Time Conservation Element and Solution Element Method

    NASA Astrophysics Data System (ADS)

    Ho, C. Y.; Leung, R. C. K.; Zhou, K.; Lam, G. C. Y.; Jiang, Z.

    2011-09-01

    One-step direct aeroacoustic simulation (DAS) has received attention from aerospace and mechanical high-pressure fluid-moving system manufacturers for quite some time. They aim to simulate the unsteady flow and acoustic field in the duct simultaneously in order to investigate the aeroacoustic generation mechanisms. Because of the large length and energy scale disparities between the acoustic far field and the aerodynamic near field, highly accurate and high-resolution simulation scheme is required. This involves the use of high order compact finite difference and time advancement schemes in simulation. However, in this situation, large buffer zones are always needed to suppress the spurious numerical waves emanating from computational boundaries. This further increases the computational resources to yield accurate results. On the other hand, for such problem as supersonic jet noise, the numerical scheme should be able to resolve both strong shock waves and weak acoustic waves simultaneously. Usually numerical aeroa-coustic scheme that is good for low Mach number flow is not able to give satisfactory simulation results for shock wave. Therefore, the aeroacoustic research community has been looking for a more efficient one-step DAS scheme that has the comparable accuracy to the finite-difference approach with smaller buffer regions, yet is able to give accurate solutions from subsonic to supersonic flows. The conservation element and solution element (CE/SE) scheme is one of the possible schemes satisfying the above requirements. This paper aims to report the development of a CE/SE scheme for one-step DAS and illustrate its robustness and effectiveness with two selected benchmark problems.

  1. Detection of Zika virus by SYBR green one-step real-time RT-PCR.

    PubMed

    Xu, Ming-Yue; Liu, Si-Qing; Deng, Cheng-Lin; Zhang, Qiu-Yan; Zhang, Bo

    2016-10-01

    The ongoing Zika virus (ZIKV) outbreak has rapidly spread to new areas of Americas, which were the first transmissions outside its traditional endemic areas in Africa and Asia. Due to the link with newborn defects and neurological disorder, numerous infected cases throughout the world and various mosquito vectors, the virus has been considered to be an international public health emergency. In the present study, we developed a SYBR Green based one-step real-time RT-PCR assay for rapid detection of ZIKV. Our results revealed that the real-time assay is highly specific and sensitive in detection of ZIKV in cell samples. Importantly, the replication of ZIKV at different time points in infected cells could be rapidly monitored by the real-time RT-PCR assay. Specifically, the real-time RT-PCR showed acceptable performance in measurement of infectious ZIKV RNA. This assay could detect ZIKV at a titer as low as 1PFU/mL. The real-time RT-PCR assay could be a useful tool for further virology surveillance and diagnosis of ZIKV. PMID:27444120

  2. Multiple ``time step'' Monte Carlo simulations: Application to charged systems with Ewald summation

    NASA Astrophysics Data System (ADS)

    Bernacki, Katarzyna; Hetényi, Balázs; Berne, B. J.

    2004-07-01

    Recently, we have proposed an efficient scheme for Monte Carlo simulations, the multiple "time step" Monte Carlo (MTS-MC) [J. Chem. Phys. 117, 8203 (2002)] based on the separation of the potential interactions into two additive parts. In this paper, the structural and thermodynamic properties of the simple point charge water model combined with the Ewald sum are compared for the MTS-MC real-/reciprocal-space split of the Ewald summation and the common Metropolis Monte Carlo method. We report a number of observables as a function of CPU time calculated using MC and MTS-MC. The correlation functions indicate that speedups on the order of 4.5-7.5 can be obtained for systems of 108-500 waters for n=10 splitting parameter.

  3. The multiple time step r-RESPA procedure and polarizable potentials based on induced dipole moments

    NASA Astrophysics Data System (ADS)

    Masella, Michel

    In the present study, we present an accelerating scheme based on the reversible multiple time step r-RESPA method to be used in molecular dynamics simulations with polarizable potentials based on induced dipole moments. Even if the induced dipoles are estimated with an iterative self-consistent procedure, this scheme significantly reduces the CPU time needed to perform a molecular dynamics simulation, up to a factor 2, as compared to the Car-Parrinello method where additional dynamical variables are introduced for the treatment of the induced dipoles. The tests show that stable and reliable molecular dynamics trajectories can be generated with that scheme, and that the physical properties derived from the trajectories are equivalent to those computed with the classical all atom iterative approach and the Car-Parrinello one.

  4. An Efficient Time-Stepping Scheme for Ab Initio Molecular Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Tsuchida, Eiji

    2016-08-01

    In ab initio molecular dynamics simulations of real-world problems, the simple Verlet method is still widely used for integrating the equations of motion, while more efficient algorithms are routinely used in classical molecular dynamics. We show that if the Verlet method is used in conjunction with pre- and postprocessing, the accuracy of the time integration is significantly improved with only a small computational overhead. We also propose several extensions of the algorithm required for use in ab initio molecular dynamics. The validity of the processed Verlet method is demonstrated in several examples including ab initio molecular dynamics simulations of liquid water. The structural properties obtained from the processed Verlet method are found to be sufficiently accurate even for large time steps close to the stability limit. This approach results in a 2× performance gain over the standard Verlet method for a given accuracy. We also show how to generate a canonical ensemble within this approach.

  5. Multi-rate time stepping schemes for hydro-geomechanical model for subsurface methane hydrate reservoirs

    NASA Astrophysics Data System (ADS)

    Gupta, Shubhangi; Wohlmuth, Barbara; Helmig, Rainer

    2016-05-01

    We present an extrapolation-based semi-implicit multi-rate time stepping (MRT) scheme and a compound-fast MRT scheme for a naturally partitioned, multi-time-scale hydro-geomechanical hydrate reservoir model. We evaluate the performance of the two MRT methods compared to an iteratively coupled solution scheme and discuss their advantages and disadvantages. The performance of the two MRT methods is evaluated in terms of speed-up and accuracy by comparison to an iteratively coupled solution scheme. We observe that the extrapolation-based semi-implicit method gives a higher speed-up but is strongly dependent on the relative time scales of the latent (slow) and active (fast) components. On the other hand, the compound-fast method is more robust and less sensitive to the relative time scales, but gives lower speed up as compared to the semi-implicit method, especially when the relative time scales of the active and latent components are comparable.

  6. Time-Accurate Local Time Stepping and High-Order Time CESE Methods for Multi-Dimensional Flows Using Unstructured Meshes

    NASA Technical Reports Server (NTRS)

    Chang, Chau-Lyan; Venkatachari, Balaji Shankar; Cheng, Gary

    2013-01-01

    With the wide availability of affordable multiple-core parallel supercomputers, next generation numerical simulations of flow physics are being focused on unsteady computations for problems involving multiple time scales and multiple physics. These simulations require higher solution accuracy than most algorithms and computational fluid dynamics codes currently available. This paper focuses on the developmental effort for high-fidelity multi-dimensional, unstructured-mesh flow solvers using the space-time conservation element, solution element (CESE) framework. Two approaches have been investigated in this research in order to provide high-accuracy, cross-cutting numerical simulations for a variety of flow regimes: 1) time-accurate local time stepping and 2) highorder CESE method. The first approach utilizes consistent numerical formulations in the space-time flux integration to preserve temporal conservation across the cells with different marching time steps. Such approach relieves the stringent time step constraint associated with the smallest time step in the computational domain while preserving temporal accuracy for all the cells. For flows involving multiple scales, both numerical accuracy and efficiency can be significantly enhanced. The second approach extends the current CESE solver to higher-order accuracy. Unlike other existing explicit high-order methods for unstructured meshes, the CESE framework maintains a CFL condition of one for arbitrarily high-order formulations while retaining the same compact stencil as its second-order counterpart. For large-scale unsteady computations, this feature substantially enhances numerical efficiency. Numerical formulations and validations using benchmark problems are discussed in this paper along with realistic examples.

  7. The two-step shape and timing of the last deglaciation in Antarctica

    SciTech Connect

    Jouzel, J.; Petit, J.R. |; Duclos, Y.

    1995-04-01

    The two-step character of the last deglaciation is well recognized in Western Europe, in Greenland and in the North Atlantic. For example, in Greenland, a gradual temperature decrease started at the Boelling (B) around 14.5 ky BP, spanned through the Alleroed (A) and was followed by the cold Younger Dryas (YD) event which terminated abruptly around 11.5 ky BP. Recent results suggest that this BA/YD sequence may have extended throughout all the Northern Hemisphere but the evidence of a late transition cooling is still poor for the Southern Hemisphere. Here we present a detailed isotopic record analyzed in a new ice core drilled at Dome B in East Antarctica that fully demonstrates the existence of an Antarctic cold reversal (ACR). These results suggest that the two-step shape of the last deglaciation has a worldwide character but they also point to noticeable interhemispheric differences. Thus. the coldest part of the ACR. which shows a temperature drop about three times weaker than that recorded during the YD in Greenland, may have preceded the YD. Antarctica did not experienced abrupt changes and the two warming periods started there before they started in Greenland. The links between Southern and Northern Hemisphere climates throughout this period are discussed in the light of additional information derived from the Antarctic dust record. 87 refs., 5 figs.

  8. [Photodissociation of Acetylene and Acetone using Step-Scan Time-Resolved FTIR Emission Spectroscopy

    NASA Technical Reports Server (NTRS)

    McLaren, Ian A.; Wrobel, Jacek D.

    1997-01-01

    The photodissociation of acetylene and acetone was investigated as a function of added quenching gas pressures using step-scan time-resolved FTIR emission spectroscopy. Its main components consist of Bruker IFS88, step-scan Fourier Transform Infrared (FTIR) spectrometer coupled to a flow cell equipped with Welsh collection optics. Vibrationally excited C2H radicals were produced from the photodissociation of acetylene in the unfocused experiments. The infrared (IR) emission from these excited C2H radicals was investigated as a function of added argon pressure. Argon quenching rate constants for all C2H emission bands are of the order of 10(exp -13)cc/molecule.sec. Quenching of these radicals by acetylene is efficient, with a rate constant in the range of 10(exp -11) cc/molecule.sec. The relative intensity of the different C2H emission bands did not change with the increasing argon or acetylene pressure. However, the overall IR emission intensity decreased, for example, by more than 50% when the argon partial pressure was raised from 0.2 to 2 Torr at fixed precursor pressure of 160mTorr. These observations provide evidence for the formation of a metastable C2H2 species, which are collisionally quenched by argon or acetylene. Problems encountered in the course of the experimental work are also described.

  9. Structural damage evolution assessment using the regularised time step integration method

    NASA Astrophysics Data System (ADS)

    Chen, Hua-Peng; Maung, Than Soe

    2014-09-01

    This paper presents an approach to identify both the location and severity evolution of damage in engineering structures directly from measured dynamic response data. A relationship between the change in structural parameters such as stiffness caused by structural damage development and the measured dynamic response data such as accelerations is proposed, on the basis of the governing equations of motion for the original and damaged structural systems. Structural damage parameters associated with time are properly chosen to reflect both the location and severity development over time of damage in a structure. Basic equations are provided to solve the chosen time-dependent damage parameters, which are constructed by using the Newmark time step integration method without requiring a modal analysis procedure. The Tikhonov regularisation method incorporating the L-curve criterion for determining the regularisation parameter is then employed to reduce the influence of measurement errors in dynamic response data and then to produce stable solutions for structural damage parameters. Results for two numerical examples with various simulated damage scenarios show that the proposed method can accurately identify the locations of structural damage and correctly assess the evolution of damage severity from information on vibration measurements with uncertainties.

  10. Incorporating system latency associated with real-time target tracking radiotherapy in the dose prediction step

    NASA Astrophysics Data System (ADS)

    Roland, Teboh; Mavroidis, Panayiotis; Shi, Chengyu; Papanikolaou, Nikos

    2010-05-01

    System latency introduces geometric errors in the course of real-time target tracking radiotherapy. This effect can be minimized, for example by the use of predictive filters, but cannot be completely avoided. In this work, we present a convolution technique that can incorporate the effect as part of the treatment planning process. The method can be applied independently or in conjunction with the predictive filters to compensate for residual latency effects. The implementation was performed on TrackBeam (Initia Ltd, Israel), a prototype real-time target tracking system assembled and evaluated at our Cancer Institute. For the experimental system settings examined, a Gaussian distribution attributable to the TrackBeam latency was derived with σ = 3.7 mm. The TrackBeam latency, expressed as an average response time, was deduced to be 172 ms. Phantom investigations were further performed to verify the convolution technique. In addition, patient studies involving 4DCT volumes of previously treated lung cancer patients were performed to incorporate the latency effect in the dose prediction step. This also enabled us to effectively quantify the dosimetric and radiobiological impact of the TrackBeam and other higher latency effects on the clinical outcome of a real-time target tracking delivery.

  11. Simulations of precipitation using the Community Earth System Model (CESM): Sensitivity to microphysics time step

    NASA Astrophysics Data System (ADS)

    Murthi, A.; Menon, S.; Sednev, I.

    2011-12-01

    An inherent difficulty in the ability of global climate models to accurately simulate precipitation lies in the use of a large time step, Δt (usually 30 minutes), to solve the governing equations. Since microphysical processes are characterized by small time scales compared to Δt, finite difference approximations used to advance microphysics equations suffer from numerical instability and large time truncation errors. With this in mind, the sensitivity of precipitation simulated by the atmospheric component of CESM, namely the Community Atmosphere Model (CAM 5.1), to the microphysics time step (τ) is investigated. Model integrations are carried out for a period of five years with a spin up time of about six months for a horizontal resolution of 2.5 × 1.9 degrees and 30 levels in the vertical, with Δt = 1800 s. The control simulation with τ = 900 s is compared with one using τ = 300 s for accumulated precipitation and radi- ation budgets at the surface and top of the atmosphere (TOA), while keeping Δt fixed. Our choice of τ = 300 s is motivated by previous work on warm rain processes wherein it was shown that a value of τ around 300 s was necessary, but not sufficient, to ensure positive definiteness and numerical stability of the explicit time integration scheme used to integrate the microphysical equations. However, since the entire suite of microphysical processes are represented in our case, we suspect that this might impose additional restrictions on τ. The τ = 300 s case produces differences in large-scale accumulated rainfall from the τ = 900 s case by as large as 200 mm, over certain regions of the globe. The spatial patterns of total accumulated precipitation using τ = 300 s are in closer agreement with satellite observed precipitation, when compared to the τ = 900 s case. Differences are also seen in the radiation budget with the τ = 300 (900) s cases producing surpluses that range between 1-3 W/m2 at both the TOA and surface in the global

  12. Induction of an LH surge and ovulation by buserelin (as Receptal) allows breeding of weaned sows with a single fixed-time insemination.

    PubMed

    Driancourt, M A; Cox, P; Rubion, S; Harnois-Milon, G; Kemp, B; Soede, N M

    2013-09-01

    The aim of this study was to demonstrate successful breeding of sows with a single fixed-time insemination following ovulation induction by buserelin, a GnRH analogue. In a first step, the optimal dose of buserelin (6, 10, or 16 μg) injected at 77 hours after weaning was determined in weaned sows (N = 15, 11, and 12, respectively) using its ability to induce an LH surge of similar magnitude as in control sows (N = 15) and induce ovulation. In 29/38 treated sows (76%), ovulation was induced and synchronized between 32 and 44 hours after injection, and the proportion of females ovulating during this time window was similar between groups at 73%, 73%, and 83% (6, 10, or 16 μg, respectively). Interestingly, whereas ovulation of 100% multiparous sows was induced and synchronized in the 32 to 44 hours posttreatment time window, successful induction was achieved in a lower proportion of primiparous sows (50%, 50%, and 67% following 6, 10, or 16 μg, respectively), the dose effect being nonsignificant. The magnitude of the LH surge was similar between control and treated sows, irrespective of the buserelin dose injected. Neither ovulation rate nor the number of good embryos on Day 5 postovulation differed between groups. Interestingly, the frequency of follicular cysts at slaughter was significantly affected by treatment (P < 0.05), being minimal and maximal in sows treated with 10 or 6 μg buserelin, respectively. In a second step, 419 sows from commercial herds in Spain, Germany, and France were randomly allocated to a control or treated group. The control sows were inseminated twice 12 ± 4 hours apart once estrus was detected. Treated sows received 10 μg buserelin at 86 ± 3 hours after weaning and were inseminated once 30 to 33 hours later. Farrowing rate of treated sows (87%, 166/192) was similar to that of control sows (84.5%, 169/200). Litter size was also similar between treated and control sows (13.6 ± 3.8 vs. 13.7 ± 3.2). In multiparous sows, neither

  13. Detection and Correction of Step Discontinuities in Kepler Flux Time Series

    NASA Technical Reports Server (NTRS)

    Kolodziejczak, J. J.; Morris, R. L.

    2011-01-01

    PDC 8.0 includes an implementation of a new algorithm to detect and correct step discontinuities appearing in roughly one of every 20 stellar light curves during a given quarter. The majority of such discontinuities are believed to result from high-energy particles (either cosmic or solar in origin) striking the photometer and causing permanent local changes (typically -0.5%) in quantum efficiency, though a partial exponential recovery is often observed [1]. Since these features, dubbed sudden pixel sensitivity dropouts (SPSDs), are uncorrelated across targets they cannot be properly accounted for by the current detrending algorithm. PDC detrending is based on the assumption that features in flux time series are due either to intrinsic stellar phenomena or to systematic errors and that systematics will exhibit measurable correlations across targets. SPSD events violate these assumptions and their successful removal not only rectifies the flux values of affected targets, but demonstrably improves the overall performance of PDC detrending [1].

  14. Electric and hybrid electric vehicle study utilizing a time-stepping simulation

    NASA Technical Reports Server (NTRS)

    Schreiber, Jeffrey G.; Shaltens, Richard K.; Beremand, Donald G.

    1992-01-01

    The applicability of NASA's advanced power technologies to electric and hybrid vehicles was assessed using a time-stepping computer simulation to model electric and hybrid vehicles operating over the Federal Urban Driving Schedule (FUDS). Both the energy and power demands of the FUDS were taken into account and vehicle economy, range, and performance were addressed simultaneously. Results indicate that a hybrid electric vehicle (HEV) configured with a flywheel buffer energy storage device and a free-piston Stirling convertor fulfills the emissions, fuel economy, range, and performance requirements that would make it acceptable to the consumer. It is noted that an assessment to determine which of the candidate technologies are suited for the HEV application has yet to be made. A proper assessment should take into account the fuel economy and range, along with the driveability and total emissions produced.

  15. Comparison of Fixed and Variable Time Step Trajectory Integration Methods for Cislunar Trajectories

    NASA Technical Reports Server (NTRS)

    Weeks, ichael W.; Thrasher, Stephen W.

    2007-01-01

    Due to the nonlinear nature of the Earth-Moon-Sun three-body problem and non-spherical gravity, CEV cislunar targeting algorithms will require many propagations in their search for a desired trajectory. For on-board targeting especially, the algorithm must have a simple, fast, and accurate propagator to calculate a trajectory with reasonable computation time, and still be robust enough to remain stable in the various flight regimes that the CEV will experience. This paper compares Cowell s method with a fourth-order Runge- Kutta integrator (RK4), Encke s method with a fourth-order Runge-Kutta- Nystr m integrator (RKN4), and a method known as Multi-Conic. Additionally, the study includes the Bond-Gottlieb 14-element method (BG14) and extends the investigation of Encke-Nystrom methods to integrators of higher order and with variable step size.

  16. Effect of the processing steps on compositions of table olive since harvesting time to pasteurization.

    PubMed

    Nikzad, Nasim; Sahari, Mohammad A; Vanak, Zahra Piravi; Safafar, Hamed; Boland-nazar, Seyed A

    2013-08-01

    Weight, oil, fatty acids, tocopherol, polyphenol, and sterol properties of 5 olive cultivars (Zard, Fishomi, Ascolana, Amigdalolia, and Conservalia) during crude, lye treatment, washing, fermentation, and pasteurization steps were studied. Results showed: oil percent was higher and lower in Ascolana (crude step) and in Fishomi (pasteurization step), respectively; during processing steps, in all cultivars, oleic, palmitic, linoleic, and stearic acids were higher; the highest changes in saturated and unsaturated fatty acids were in fermentation step; the highest and the lowest ratios of ω3 / ω6 were in Ascolana (washing step) and in Zard (pasteurization step), respectively; the highest and the lowest tocopherol were in Amigdalolia and Fishomi, respectively, and major damage occurred in lye step; the highest and the lowest polyphenols were in Ascolana (crude step) and in Zard and Ascolana (pasteurization step), respectively; the major damage among cultivars occurred during lye step, in which the polyphenol reduced to 1/10 of first content; sterol did not undergo changes during steps. Reviewing of olive patents shows that many compositions of fruits such as oil quality, fatty acids, quantity and its fraction can be changed by alteration in cultivar and process. PMID:23688142

  17. Time-of-flight direct recoil spectrometry: Application to liquid surfaces and steps toward quantification

    NASA Astrophysics Data System (ADS)

    Tassotto, Michael

    2001-08-01

    Liquid surfaces are very abundant in nature. Despite the importance of the liquid interface in general, experimental molecular-level data was almost completely lacking prior to the last decade and a half. The intent of this work is to provide a means by which experimental data on the composition of liquid surfaces and the average orientation of their constituent molecules can be obtained in order to supplement data from molecular dynamics and related computational techniques. To this end, a unique time-of-flight (TOF) spectrometer, which constitutes the backbone of a new method to study liquid surfaces, was constructed and commissioned. The performance of the spectrometer is demonstrated in a number of exemplary TOF spectra obtained from liquid glycerol. Moving from mere qualitative to quantitative surface analysis necessitates the ability to relate physical quantities such as detection efficiencies, accurate signal intensities, and interaction cross-sections for all elements to one another. As a first step, the absolute detection efficiency of a channel electron multiplier, used as particle detector in the spectrometer, was measured for the noble gas ions He+, Ar+, and Xe +. The data obtained led to an empirically derived, general expression of the detection efficiency that is applicable to particles of any atomic number. The results also show that the threshold velocity, below which a multiplier does not respond to impinging ions, cannot be regarded as independent of the ion's atomic number as previously reported in the literature. The second step involved a comprehensive investigation of ion-atom interactions and spectral features that are crucial for the processing of experimental signal intensities for quantitative analysis. For this purpose, the binary collision code MARLOWE was used in extensive trajectory calculations simulating TOF spectra. The simulation results confirm the high surface sensitivity of the technique and reveal the strong dependence of the

  18. The role of the time step and overshooting in the modelling of PMS evolution: The case of EK Cephei

    NASA Astrophysics Data System (ADS)

    Marques, J. P.; Fernandes, J.; Monteiro, M. J. P. F. G.

    2004-07-01

    EK Cephei (HD 206821) is a unique candidate to test predictions based on stellar evolutionary models. It is a double-lined detached eclipsing binary system with accurate absolute dimensions available and a precise determination of the metallicity. Most importantly for our work, its low mass (1.12 Msun) component appears to be in the pre-main sequence (PMS) phase. We have produced detailed evolutionary models of the binary EK Cep using the CESAM stellar evolution code (Morel \\cite{morel97}). A χ2-minimisation was performed to derive the most reliable set of modelling parameters (age, αA, αB and Yi). We have found that an evolutionary age of about 26.8 Myr fits both components in the same isochrone. The positions of EK Cep A and B in the HR diagram are consistent (within the observational uncertainties) with our results. Our revised calibration shows clearly that EK Cep A is in the beginning of the main sequence, while EK Cep B is indeed a PMS star. Such a combination allows for a precise age determination of the binary, and provides a strict test of the modelling. In particular we have found that the definition of the time step in calculating the PMS evolution is crucial to reproduce the observations. A discussion of the optimal time step for calculating PMS evolution is presented. The fitting to the radii of both components is a more difficult task; although we managed to do it for EK Cep B, EK Cep A has a lower radius than our best models. We further studied the effect of the inclusion of a moderate convective overshooting; the calibration of the binary is not significantly altered, but the effect of the inclusion of overshooting can be dramatic in the approach to the main sequence of stars with masses high enough to burn hydrogen through the CNO cycle on the main sequence.

  19. Security: Step by Step

    ERIC Educational Resources Information Center

    Svetcov, Eric

    2005-01-01

    This article provides a list of the essential steps to keeping a school's or district's network safe and sound. It describes how to establish a security architecture and approach that will continually evolve as the threat environment changes over time. The article discusses the methodology for implementing this approach and then discusses the…

  20. Electric and magnetic losses modeled by a stable hybrid with explicit-implicit time-stepping for Maxwell's equations

    SciTech Connect

    Halleroed, Tomas Rylander, Thomas

    2008-04-20

    A stable hybridization of the finite-element method (FEM) and the finite-difference time-domain (FDTD) scheme for Maxwell's equations with electric and magnetic losses is presented for two-dimensional problems. The hybrid method combines the flexibility of the FEM with the efficiency of the FDTD scheme and it is based directly on Ampere's and Faraday's law. The electric and magnetic losses can be treated implicitly by the FEM on an unstructured mesh, which allows for local mesh refinement in order to resolve rapid variations in the material parameters and/or the electromagnetic field. It is also feasible to handle larger homogeneous regions with losses by the explicit FDTD scheme connected to an implicitly time-stepped and lossy FEM region. The hybrid method shows second-order convergence for smooth scatterers. The bistatic radar cross section (RCS) for a circular metal cylinder with a lossy coating converges to the analytical solution and an accuracy of 2% is achieved for about 20 points per wavelength. The monostatic RCS for an airfoil that features sharp corners yields a lower order of convergence and it is found to agree well with what can be expected for singular fields at the sharp corners. A careful convergence study with resolutions from 20 to 140 points per wavelength provides accurate extrapolated results for this non-trivial test case, which makes it possible to use as a reference problem for scattering codes that model both electric and magnetic losses.

  1. Outward Bound to the Galaxies--One Step at a Time

    ERIC Educational Resources Information Center

    Ward, R. Bruce; Miller-Friedmann, Jaimie; Sienkiewicz, Frank; Antonucci, Paul

    2012-01-01

    Less than a century ago, astronomers began to unlock the cosmic distances within and beyond the Milky Way. Understanding the size and scale of the universe is a continuing, step-by-step process that began with the remarkably accurate measurement of the distance to the Moon made by early Greeks. In part, the authors have ITEAMS (Innovative…

  2. Thinking Allowed

    ERIC Educational Resources Information Center

    Berkeley, Viv

    2008-01-01

    Disability equality and improving life chances for disabled people are high on the U.K. Government's agenda at present. As someone who was once a practitioner and a manager in a busy further education environment, the author knows how difficult it is to find time to think about, and discuss with colleagues, the implications of policy. This article…

  3. Variations in force-time histories of cat gastrocnemius, soleus and plantaris muscles for consecutive walking steps.

    PubMed

    Herzog, W; Zatsiorsky, V; Prilutsky, B I; Leonard, T R

    1994-06-01

    Force-sharing among muscles during locomotion has been studied experimentally using 'representative' or 'average' step cycles. Mathematical approaches aimed at predicting individual muscle forces during locomotion are based on the assumption that force-sharing among muscles occurs in a consistent and unique way. In this study, we quantify normal variations in muscular force-time histories for step cycles executed at a given nominal speed, so that we can appreciate what it means to analyze 'representative' or 'average' step cycles and can evaluate whether these normal variations in muscular force-time histories are random or may be associated with variations in the kinematics of consecutive step cycles. Forces in gastrocnemius, soleus and plantaris muscles were measured for step cycles performed at a constant nominal speed in freely moving cats. Gastrocnemius forces were always larger than peak plantaris or soleus forces. Also, peak gastrocnemius forces typically occurred first after paw contact, followed by peak soleus and then peak plantaris forces. Furthermore, it was found that variations in muscular force-time histories were substantial and were systematically related to step-cycle durations. The results of this study suggest that findings based on 'representative' or 'average' step cycles for a given nominal speed of locomotion should be viewed cautiously and that variations in force-sharing among muscles are systematically related to variations in locomotor kinematics. PMID:7931035

  4. The real-time resolution of proton-related transient-state steps in an enzymatic reaction. The early steps in the oxidative deamination reaction of bovine liver glutamate dehydrogenase.

    PubMed

    Singh, N; Maniscalco, S J; Fisher, H F

    1993-01-01

    We introduce a novel transient-state kinetic approach which can resolve proton and product time courses into a series of individual steps that comprise the reaction path. We have applied this approach to the oxidative deamination reaction catalyzed by bovine liver glutamate dehydrogenase, measuring both the product (NADPH) and proton time courses at various pH values. The global treatment (over all pH values) resolves the very early portion of this reaction quantitatively and provides a continuous time course for each of the six protonic species. We propose the following mechanism: L-glutamate binds to an open conformation of the enzyme-NADP complex, forming salt bridges between its alpha- and gamma-carboxyl groups and the protonated forms of enzyme lysine residues 114 and 90, respectively. In this position, the alpha-H atom of the substrate is too far from the nicotinamide ring for hydride transfer to occur. In the next step, three events occur in a concerted manner: lysine 126 loses a proton and acquires a single water molecule; the active site cleft closes; bulk water is expelled; the substrate and coenzyme are forced closer together and remain in a nonaqueous environment during the ensuing chemical events, returning to an open conformation only in time to allow the product release steps to occur. Thus, substrate binding accomplishes a number of important tasks which are themselves an integral part of the catalytic mechanism. Combining the novel transient state approach developed here with steady-state kinetic information can produce a detailed mechanistic resolution of otherwise hidden steps. PMID:8093240

  5. Time-of-Arrival Measurements of X-ray Emission Associated with Dart-Stepped Leader Steps in Natural and Rocket-and-Wire Triggered Lightning

    NASA Astrophysics Data System (ADS)

    Jordan, D. M.; Hill, J. D.; Uman, M. A.; Dwyer, J. R.; Rassoul, H. K.

    2012-12-01

    Time-of-arrival (TOA) techniques were used to determine the three-dimensional locations and emission times of x-ray and dE/dt sources measured at ground level in association with dart-stepped leader steps in natural and rocket-and-wire triggered lightning discharges recorded during summer 2011 at Camp Blanding, FL. The measurement network consisted of ten flat plate dE/dt antennas approximately co-located with eight plastic and two Lanthanum Bromide scintillation detectors arrayed around the launching facility over an area of about 0.25 square kilometers. For two triggered lightning dart-stepped leaders, x-ray sources were emitted from locations separated by average distances of 22.7 m and 29 m, respectively, from the locations of the associated dE/dt pulse peaks. The x-ray sources occurred beneath the dE/dt sources in 88% of the cases. X-rays were emitted from 20 ns to 2.16 μs following the dE/dt pulse peaks, with average temporal separations of 150 ns and 290 ns, respectively, for the two triggered lightning events. For one natural lightning dart-stepped leader, x-ray sources were emitted an average total distance of 39.2 m from the associated dE/dt pulse peak, and occurred beneath the location of the dE/dt source in 86% of the cases. The x-rays were emitted from 10 ns to 1.76 μs following the dE/dt pulse peak with an average temporal separation of 280 ns. In each of the three events, the altitude displacement between the dE/dt and x-ray sources dominated the total separation, accounting for 90%, 63%, and 72%, respectively, of the total separation. X-ray sources were distributed randomly in the lateral directions about the lightning channel in each event. For the triggered lightning events, x-rays were located from 2.5-83.5 μs prior to the return stroke at altitudes ranging from 24-336 m. For the natural lightning event, x-rays were located from 40.4-222.3 μs prior to the return stroke at altitudes ranging from 99-394 m. Cumulatively, 67% of the located x

  6. 41 CFR 302-2.110 - Are there time factors that we must consider for allowing an employee to complete all aspects of...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... that we must consider for allowing an employee to complete all aspects of relocation? 302-2.110 Section... Are there time factors that we must consider for allowing an employee to complete all aspects of... travel is approved and inform employees that they must complete all aspects of relocation within a...

  7. 41 CFR 302-2.110 - Are there time factors that we must consider for allowing an employee to complete all aspects of...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... that we must consider for allowing an employee to complete all aspects of relocation? 302-2.110 Section... Are there time factors that we must consider for allowing an employee to complete all aspects of... travel is approved and inform employees that they must complete all aspects of relocation within a...

  8. 41 CFR 302-2.110 - Are there time factors that we must consider for allowing an employee to complete all aspects of...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... that we must consider for allowing an employee to complete all aspects of relocation? 302-2.110 Section... Are there time factors that we must consider for allowing an employee to complete all aspects of... travel is approved and inform employees that they must complete all aspects of relocation within a...

  9. 41 CFR 302-2.110 - Are there time factors that we must consider for allowing an employee to complete all aspects of...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... that we must consider for allowing an employee to complete all aspects of relocation? 302-2.110 Section... Are there time factors that we must consider for allowing an employee to complete all aspects of... travel is approved and inform employees that they must complete all aspects of relocation within a...

  10. 41 CFR 302-2.110 - Are there time factors that we must consider for allowing an employee to complete all aspects of...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... that we must consider for allowing an employee to complete all aspects of relocation? 302-2.110 Section... Are there time factors that we must consider for allowing an employee to complete all aspects of... travel is approved and inform employees that they must complete all aspects of relocation within a...

  11. Generalized shot noise model for time-reversal in multiple-scattering media allowing for arbitrary inputs and windowing

    PubMed Central

    Haworth, Kevin J.; Fowlkes, J. Brian; Carson, Paul L.; Kripfgans, Oliver D.

    2009-01-01

    A theoretical shot noise model to describe the output of a time-reversal experiment in a multiple-scattering medium is developed. This (non-wave equation based) model describes the following process. An arbitrary waveform is transmitted through a high-order multiple-scattering environment and recorded. The recorded signal is arbitrarily windowed and then time-reversed. The processed signal is retransmitted into the environment and the resulting signal recorded. The temporal and spatial signal and noise of this process is predicted statistically. It is found that the time when the noise is largest depends on the arbitrary windowing and this noise peak can occur at times outside the main lobe. To determine further trends, a common set of parameters is applied to the general result. It is seen that as the duration of the input function increases, the signal-to-noise ratio (SNR) decreases (independent of signal bandwidth). It is also seen that longer persisting impulse responses result in increased main lobe amplitudes and SNR. Assumptions underpinning the generalized shot noise model are compared to an experimental realization of a multiple-scattering medium (a time-reversal chaotic cavity). Results from the model are compared to random number numerical simulation. PMID:19425655

  12. Surface functionalization allowing repetitive use of optical sensors for real-time detection of antibody-bacteria interaction.

    PubMed

    Kutscher, Marika; Rosenberger, Manuel; Schmauss, Bernhard; Meinel, Lorenz; Lorenz, Udo; Ohlsen, Knut; Hellmann, Ralf; Germershaus, Oliver

    2016-07-01

    In this study, sensor surface functionalization allowing the repetitive use of a sensing device was evaluated for antibody-based detection of living bacteria using an optical planar Bragg grating sensor. To achieve regenerable immobilization of bacteria specific antibodies, the heterobifunctional cross-linker N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP) was linked to an aminosilanized sensor surface and subsequently reduced to expose sulfhydryl groups enabling the covalent conjugation of SPDP-activated antibodies via disulfide bonds. The immobilization of a capture antibody specific for Staphylococcus aureus on the sensor surface as well as specific binding of S. aureus could be monitored, highlighting the applicability of optical sensors for the specific detection of large biological structures. Reusability of bacteria saturated sensors was successfully demonstrated by cleaving the antibody along with bound bacteria through reduction of disulfide bonds and subsequent re-functionalization with activated antibody, resulting in comparable sensitivity towards S. aureus. PMID:26486822

  13. Steps toward thin film metal thermistors with microsecond time response for shock temperature measurements of polymers

    NASA Astrophysics Data System (ADS)

    Taylor, N. E.; Williamson, D. M.; Jardine, A. P.

    2014-05-01

    Equations of state can be used to predict the relationship between pressure, volume and temperature. However, in shock physics, they are usually only constrained by experimental observations of pressure and volume. Direct observation of temperature in a shock is therefore valuable in constraining equations of state. Bloomquist and Sheffield (1980, 1981) and Rosenberg and Partom (1984) have attempted such observations in poly(methyl methacrylate) (PMMA). However, their results disagree strongly above 2GPa shock pressure. Here we present an improved fabrication technique, to examine this outstanding issue. We make use of the fact that the electrical resistivity of most metals is a known function of both pressure and temperature. If the change in resistance of a thin metal thermistor gauge is measured during a shock experiment of known pressure, the temperature can be calculated directly. The time response is limited by the time taken for the gauge to reach thermal equilibrium with the medium in which it is embedded. Gold gauges of thickness up to 200 nm have been produced by thermal evaporation, and fully embedded in PMMA. These reach thermal equilibrium with the host material in under 1 us, allowing temperature measurement within the duration of a plate impact experiment.

  14. Non-iterative adaptive time-stepping scheme with temporal truncation error control for simulating variable-density flow

    NASA Astrophysics Data System (ADS)

    Hirthe, Eugenia M.; Graf, Thomas

    2012-12-01

    The automatic non-iterative second-order time-stepping scheme based on the temporal truncation error proposed by Kavetski et al. [Kavetski D, Binning P, Sloan SW. Non-iterative time-stepping schemes with adaptive truncation error control for the solution of Richards equation. Water Resour Res 2002;38(10):1211, http://dx.doi.org/10.1029/2001WR000720.] is implemented into the code of the HydroGeoSphere model. This time-stepping scheme is applied for the first time to the low-Rayleigh-number thermal Elder problem of free convection in porous media [van Reeuwijk M, Mathias SA, Simmons CT, Ward JD. Insights from a pseudospectral approach to the Elder problem. Water Resour Res 2009;45:W04416, http://dx.doi.org/10.1029/2008WR007421.], and to the solutal [Shikaze SG, Sudicky EA, Schwartz FW. Density-dependent solute transport in discretely-fractured geological media: is prediction possible? J Contam Hydrol 1998;34:273-91] problem of free convection in fractured-porous media. Numerical simulations demonstrate that the proposed scheme efficiently limits the temporal truncation error to a user-defined tolerance by controlling the time-step size. The non-iterative second-order time-stepping scheme can be applied to (i) thermal and solutal variable-density flow problems, (ii) linear and non-linear density functions, and (iii) problems including porous and fractured-porous media.

  15. Development of real-time diagnostics and feedback algorithms for JET in view of the next step

    NASA Astrophysics Data System (ADS)

    Murari, A.; Joffrin, E.; Felton, R.; Mazon, D.; Zabeo, L.; Albanese, R.; Arena, P.; Ambrosino, G.; Ariola, M.; Barana, O.; Bruno, M.; Laborde, L.; Moreau, D.; Piccolo, F.; Sartori, F.; Crisanti, F.; de la Luna, E.; Sanchez, J.; Contributors, EFDA-JET

    2005-03-01

    Real-time control of many plasma parameters will be an essential aspect in the development of reliable high performance operation of next step tokamaks. The main prerequisites for any feedback scheme are the precise real-time determination of the quantities to be controlled, requiring top quality and highly reliable diagnostics, and the availability of robust control algorithms. A new set of real-time diagnostics was recently implemented on JET to prove the feasibility of determining, with high accuracy and time resolution, the most important plasma quantities. Some of the signals now routinely provided in real time at JET are: (i) the internal inductance and the main confinement quantities obtained by calculating the Shafranov integrals from the pick-up coils with 2 ms time resolution; (ii) the electron temperature profile, from electron cylotron emission every 10 ms; (iii) the ion temperature and plasma toroidal velocity profiles, from charge exchange recombination spectroscopy, provided every 50 ms; and (iv) the safety factor profile, derived from the inversion of the polarimetric line integrals every 2 ms. With regard to feedback algorithms, new model-based controllers were developed to allow a more robust control of several plasma parameters. With these new tools, several real-time schemes were implemented, among which the most significant is the simultaneous control of the safety factor and the plasma pressure profiles using the additional heating systems (LH, NBI, ICRH) as actuators. The control strategy adopted in this case consists of a multi-variable model-based technique, which was implemented as a truncated singular value decomposition of an integral operator. This approach is considered essential for systems like tokamak machines, characterized by a strong mutual dependence of the various parameters and the distributed nature of the quantities, the plasma profiles, to be controlled. First encouraging results were also obtained using non

  16. The Influence of Time Spent in Outdoor Play on Daily and Aerobic Step Count in Costa Rican Children

    ERIC Educational Resources Information Center

    Morera Castro, Maria del Rocio

    2011-01-01

    The purpose of this study is to examine the influence of time spent in outdoor play (i.e., on weekday and weekend days) on daily (i.e., average step count) and aerobic step count (i.e., average moderate to vigorous physical activity [MVPA] during the weekdays and weekend days) in fifth grade Costa Rican children. It was hypothesized that: (a)…

  17. Using preconditioned adaptive step size Runge-Kutta methods for solving the time-dependent Schroedinger equation

    SciTech Connect

    Tremblay, Jean Christophe; Carrington, Tucker Jr.

    2004-12-15

    If the Hamiltonian is time dependent it is common to solve the time-dependent Schroedinger equation by dividing the propagation interval into slices and using an (e.g., split operator, Chebyshev, Lanczos) approximate matrix exponential within each slice. We show that a preconditioned adaptive step size Runge-Kutta method can be much more efficient. For a chirped laser pulse designed to favor the dissociation of HF the preconditioned adaptive step size Runge-Kutta method is about an order of magnitude more efficient than the time sliced method.

  18. Single particle optical extinction and scattering allows real time quantitative characterization of drug payload and degradation of polymeric nanoparticles

    PubMed Central

    Potenza, M. A. C.; Sanvito, T.; Argentiere, S.; Cella, C.; Paroli, B.; Lenardi, C.; Milani, P.

    2015-01-01

    The behavior of nanoparticles in biological systems is determined by their dimensions, size distribution, shape, surface chemistry, density, drug loading and stability; the characterization of these parameters in realistic conditions and the possibility to follow their evolution in vitro and in vivo are, in most of the cases, far from the capabilities of the standard characterization technologies. Optical techniques such as dynamic light scattering (DLS) are, in principle, well suited for in line characterization of nanoparticle, however their fail in characterizing the evolution of nanoparticle in solution where change in particle dimension and density is present. Here we present an in-line optical technique based on single particle extinction and scattering (SPES) overcoming the limitations typical of DLS and allowing for the efficient characterization of nanoparticle polydispersity, index of refraction and degradation dynamics in solution. Using SPES, we characterized the evolution of PLGA nanoparticles with different structures and drug payloads in solution and we compared the results with DLS. Our results suggest that SPES could be used as a process analytical technology for pharmaceutical nanoparticle production. PMID:26667064

  19. Single particle optical extinction and scattering allows real time quantitative characterization of drug payload and degradation of polymeric nanoparticles

    NASA Astrophysics Data System (ADS)

    Potenza, M. A. C.; Sanvito, T.; Argentiere, S.; Cella, C.; Paroli, B.; Lenardi, C.; Milani, P.

    2015-12-01

    The behavior of nanoparticles in biological systems is determined by their dimensions, size distribution, shape, surface chemistry, density, drug loading and stability; the characterization of these parameters in realistic conditions and the possibility to follow their evolution in vitro and in vivo are, in most of the cases, far from the capabilities of the standard characterization technologies. Optical techniques such as dynamic light scattering (DLS) are, in principle, well suited for in line characterization of nanoparticle, however their fail in characterizing the evolution of nanoparticle in solution where change in particle dimension and density is present. Here we present an in-line optical technique based on single particle extinction and scattering (SPES) overcoming the limitations typical of DLS and allowing for the efficient characterization of nanoparticle polydispersity, index of refraction and degradation dynamics in solution. Using SPES, we characterized the evolution of PLGA nanoparticles with different structures and drug payloads in solution and we compared the results with DLS. Our results suggest that SPES could be used as a process analytical technology for pharmaceutical nanoparticle production.

  20. Kinetic Analysis of Parallel-Consecutive First-Order Reactions with a Reversible Step: Concentration-Time Integrals Method

    ERIC Educational Resources Information Center

    Mucientes, A. E.; de la Pena, M. A.

    2009-01-01

    The concentration-time integrals method has been used to solve kinetic equations of parallel-consecutive first-order reactions with a reversible step. This method involves the determination of the area under the curve for the concentration of a given species against time. Computer techniques are used to integrate experimental curves and the method…

  1. A Step Response Based Mixed-Signal BIST Approach for Continuous-time Linear Circuits

    NASA Technical Reports Server (NTRS)

    Walker, Alvernon; Lala, P. K.

    2001-01-01

    A new Mixed-Signal Built-in self-test approach that is based upon the step response of a reconfigurable (or multifunction) analog block is presented in this paper. The technique requires the overlapping step response of the Circuit Under Test (CUT) for two circuit configurations. Each configuration can be realized by changing the topology of the CUT or by sampling two CUT nodes with differing step responses. The technique can effectively detect both soft and hard faults and does not require an analog-to-digital converter (ADC) and/or digital-to-analog converter(DAC). It also does not require any precision voltage sources or comparators. This approach does not require any additional analog circuits to realize the test signal generator and sample circuits. The paper is concluded with the application of the proposed approach to a circuit found in the work of Epstein et al and two ITC 97 analog benchmark circuits.

  2. Using a scale selective tendency filter and forward-backward time stepping to calculate consistent semi-Lagrangian trajectories

    NASA Astrophysics Data System (ADS)

    Alerskans, Emy; Kaas, Eigil

    2016-04-01

    In semi-Lagrangian models used for climate and NWP the trajectories are normally/often determined kinematically. Here we propose a new method for calculating trajectories in a more dynamically consistent way by pre-integrating the governing equations in a pseudo-Lagrangian manner using a short time step. Only non-advective adiabatic terms are included in this calculation, i.e., the Coriolis and pressure gradient force plus gravity in the momentum equations, and the divergence term in the continuity equation. This integration is performed with a forward-backward time step. Optionally, the tendencies are filtered with a local space filter, which reduces the phase speed of short wave gravity and sound waves. The filter relaxes the time step limitation related to high frequency oscillations without compromising locality of the solution. The filter can be considered as an alternative to less local or global semi-implicit solvers. Once trajectories are estimated over a complete long advective time step the full set of governing equations is stepped forward using these trajectories in combination with a flux form semi-Lagrangian formulation of the equations. The methodology is designed to improve consistency and scalability on massively parallel systems, although here it has only been verified that the technique produces realistic results in a shallow water model and a 2D model based on the full Euler equations.

  3. Optical monitor for real time thickness change measurements via lateral-translation induced phase-stepping interferometry

    DOEpatents

    Rushford, Michael C.

    2002-01-01

    An optical monitoring instrument monitors etch depth and etch rate for controlling a wet-etching process. The instrument provides means for viewing through the back side of a thick optic onto a nearly index-matched interface. Optical baffling and the application of a photoresist mask minimize spurious reflections to allow for monitoring with extremely weak signals. A Wollaston prism enables linear translation for phase stepping.

  4. Characterization of Energy Conservation in Primary Knock-On Atom Cascades: Ballistic Phase Effects on Variable Time Steps

    SciTech Connect

    Corrales, Louis R.; Devanathan, Ram

    2006-09-01

    Non-equilibrium molecular dynamics simulation trajectories must in principle conserve energy along the entire path. Processes exist in high-energy primary knock-on atom cascades that can affect the energy conservation, specifically during the ballistic phase where collisions bring atoms into very close proximities. The solution, in general, is to reduce the time step size of the simulation. This work explores the effects of variable time step algorithms and the effects of specifying a maximum displacement. The period of the ballistic phase can be well characterized by methods developed in this work to monitor the kinetic energy dissipation during a high-energy cascade.

  5. Changing Step or Marking Time? Teacher Education Reforms for the Learning and Skills Sector in England

    ERIC Educational Resources Information Center

    Thompson, Ron; Robinson, Denise

    2008-01-01

    The unprecedented degree of attention given to the learning and skills sector in England by successive New Labour governments has led to a significant increase in what is expected of the teaching workforce. To help meet these expectations, a "step change" in the quality of initial teacher training for the sector is promised, alongside provisions…

  6. Multi-Step Ahead Predictions for Critical Levels in Physiological Time Series.

    PubMed

    ElMoaqet, Hisham; Tilbury, Dawn M; Ramachandran, Satya Krishna

    2016-07-01

    Standard modeling and evaluation methods have been classically used in analyzing engineering dynamical systems where the fundamental problem is to minimize the (mean) error between the real and predicted systems. Although these methods have been applied to multi-step ahead predictions of physiological signals, it is often more important to predict clinically relevant events than just to match these signals. Adverse clinical events, which occur after a physiological signal breaches a clinically defined critical threshold, are a popular class of such events. This paper presents a framework for multi-step ahead predictions of critical levels of abnormality in physiological signals. First, a performance metric is presented for evaluating multi-step ahead predictions. Then, this metric is used to identify personalized models optimized with respect to predictions of critical levels of abnormality. To address the paucity of adverse events, weighted support vector machines and cost-sensitive learning are used to optimize the proposed framework with respect to statistical metrics that can take into account the relative rarity of such events. PMID:27244754

  7. Adaptice-step time integration package for stiff, nonstiff and multi-rate systems of ordinary differential equations (ODEs)

    2014-06-01

    ARKode is part of a software family called SUNDIALS: SUite of Nonlinear and Differential/ALgebraic equation Solvers [1]. The ARKode solver library provides an adaptive-step time integration package for stiff, nonstiff and multi-rate systems of ordinary differential equations (ODEs) using Runge Kutta methods [2].

  8. Operational flood control of a low-lying delta system using large time step Model Predictive Control

    NASA Astrophysics Data System (ADS)

    Tian, Xin; van Overloop, Peter-Jules; Negenborn, Rudy R.; van de Giesen, Nick

    2015-01-01

    The safety of low-lying deltas is threatened not only by riverine flooding but by storm-induced coastal flooding as well. For the purpose of flood control, these deltas are mostly protected in a man-made environment, where dikes, dams and other adjustable infrastructures, such as gates, barriers and pumps are widely constructed. Instead of always reinforcing and heightening these structures, it is worth considering making the most of the existing infrastructure to reduce the damage and manage the delta in an operational and overall way. In this study, an advanced real-time control approach, Model Predictive Control, is proposed to operate these structures in the Dutch delta system (the Rhine-Meuse delta). The application covers non-linearity in the dynamic behavior of the water system and the structures. To deal with the non-linearity, a linearization scheme is applied which directly uses the gate height instead of the structure flow as the control variable. Given the fact that MPC needs to compute control actions in real-time, we address issues regarding computational time. A new large time step scheme is proposed in order to save computation time, in which different control variables can have different control time steps. Simulation experiments demonstrate that Model Predictive Control with the large time step setting is able to control a delta system better and much more efficiently than the conventional operational schemes.

  9. Validation of an internally controlled one-step real-time multiplex RT-PCR assay for the detection and quantitation of dengue virus RNA in plasma.

    PubMed

    Hue, Kien Duong Thi; Tuan, Trung Vu; Thi, Hanh Tien Nguyen; Bich, Chau Tran Nguyen; Anh, Huy Huynh Le; Wills, Bridget A; Simmons, Cameron P

    2011-11-01

    Dengue is mosquito-borne virus infection that annually causes ~50 million clinically apparent cases worldwide. An internally controlled one-step real-time multiplex RT-PCR assay was developed for detection and quantitation of DENV RNA in plasma sample by using specific primers and fluorogenic TaqMan probes. All primers and probes targeted sequences near the 3' end of the NS5 gene. The method comprised two multiplex assays and was validated for sensitivity, specificity, linearity, reproducibility and precision. An internal control template was spiked into each clinical specimen to provide quality assurance for each experimental step. The assay allowed for detection of between 0.5 and 3 infectious particles per mL, is rapid and has been operationally characterized in 287 Vietnamese dengue patients from two therapeutic intervention trials at the Hospital for Tropical Diseases, Ho Chi Minh City, Viet Nam. PMID:21843553

  10. A stabilized Runge–Kutta–Legendre method for explicit super-time-stepping of parabolic and mixed equations

    SciTech Connect

    Meyer, Chad D.; Balsara, Dinshaw S.; Aslam, Tariq D.

    2014-01-15

    Parabolic partial differential equations appear in several physical problems, including problems that have a dominant hyperbolic part coupled to a sub-dominant parabolic component. Explicit methods for their solution are easy to implement but have very restrictive time step constraints. Implicit solution methods can be unconditionally stable but have the disadvantage of being computationally costly or difficult to implement. Super-time-stepping methods for treating parabolic terms in mixed type partial differential equations occupy an intermediate position. In such methods each superstep takes “s” explicit Runge–Kutta-like time-steps to advance the parabolic terms by a time-step that is s{sup 2} times larger than a single explicit time-step. The expanded stability is usually obtained by mapping the short recursion relation of the explicit Runge–Kutta scheme to the recursion relation of some well-known, stable polynomial. Prior work has built temporally first- and second-order accurate super-time-stepping methods around the recursion relation associated with Chebyshev polynomials. Since their stability is based on the boundedness of the Chebyshev polynomials, these methods have been called RKC1 and RKC2. In this work we build temporally first- and second-order accurate super-time-stepping methods around the recursion relation associated with Legendre polynomials. We call these methods RKL1 and RKL2. The RKL1 method is first-order accurate in time; the RKL2 method is second-order accurate in time. We verify that the newly-designed RKL1 and RKL2 schemes have a very desirable monotonicity preserving property for one-dimensional problems – a solution that is monotone at the beginning of a time step retains that property at the end of that time step. It is shown that RKL1 and RKL2 methods are stable for all values of the diffusion coefficient up to the maximum value. We call this a convex monotonicity preserving property and show by examples that it is very

  11. Large-scale MOSFET and interconnect circuit simulation using waveform relaxation and transmission line time step control

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Jung; Chang, Allen Y.; Tsai, Chang-Lung; Lee, Chih-Jen; Chou, Li-Ping; Shin, Tien-Hao

    2012-04-01

    A modified Waveform Relaxation algorithm with transmission line calculation ability is proposed to perform large-scale circuit simulation for MOSFET circuits with lossy coupled transmission lines. The adopted full time-domain transmission line calculation algorithm, based on the Method of Characteristic, has been equipped with a time step control scheme to improve the calculation efficiency. All proposed methods have been implemented in a simulation program to simulate several circuits. The simulation results well justify the success of proposed methods.

  12. Development of a time-dependent incompressible Navier-Stokes solver based on a fractional-step method

    NASA Technical Reports Server (NTRS)

    Rosenfeld, Moshe

    1990-01-01

    The development, validation and application of a fractional step solution method of the time-dependent incompressible Navier-Stokes equations in generalized coordinate systems are discussed. A solution method that combines a finite-volume discretization with a novel choice of the dependent variables and a fractional step splitting to obtain accurate solutions in arbitrary geometries was previously developed for fixed-grids. In the present research effort, this solution method is extended to include more general situations, including cases with moving grids. The numerical techniques are enhanced to gain efficiency and generality.

  13. A dissociative fluorescence enhancement technique for one-step time-resolved immunoassays

    PubMed Central

    Mukkala, Veli-Matti; Hakala, Harri H. O.; Mäkinen, Pauliina H.; Suonpää, Mikko U.; Hemmilä, Ilkka A.

    2010-01-01

    The limitation of current dissociative fluorescence enhancement techniques is that the lanthanide chelate structures used as molecular probes are not stable enough in one-step assays with high concentrations of complexones or metal ions in the reaction mixture since these substances interfere with lanthanide chelate conjugated to the detector molecule. Lanthanide chelates of diethylenetriaminepentaacetic acid (DTPA) are extremely stable, and we used EuDTPA derivatives conjugated to antibodies as tracers in one-step immunoassays containing high concentrations of complexones or metal ions. Enhancement solutions based on different β-diketones were developed and tested for their fluorescence-enhancing capability in immunoassays with EuDTPA-labelled antibodies. Characteristics tested were fluorescence intensity, analytical sensitivity, kinetics of complex formation and signal stability. Formation of fluorescent complexes is fast (5 min) in the presented enhancement solution with EuDTPA probes withstanding strong complexones (ethylenediaminetetra acetate (EDTA) up to 100 mM) or metal ions (up to 200 μM) in the reaction mixture, the signal is intensive, stable for 4 h and the analytical sensitivity with Eu is 40 fmol/L, Tb 130 fmol/L, Sm 2.1 pmol/L and Dy 8.5 pmol/L. With the improved fluorescence enhancement technique, EDTA and citrate plasma samples as well as samples containing relatively high concentrations of metal ions can be analysed using a one-step immunoassay format also at elevated temperatures. It facilitates four-plexing, is based on one chelate structure for detector molecule labelling and is suitable for immunoassays due to the wide dynamic range and the analytical sensitivity. Figure   PMID:21161513

  14. DOUBLE-STEP MULTIPLEX REAL TIME PCR WITH MELTING CURVE ANALYSIS FOR DETECTION AND DIFFERENTIATION OF MYCOBACTERIA IN SPUTUM.

    PubMed

    Kasa, Sawinee; Faksri, Kiatichai; Kaewkes, Wanlop; Lulitanond, Viraphong; Namwat, Wises

    2015-01-01

    Mycobacterium tuberculosis (M. tb) is a causative agent of tuberculosis, a worldwide public health problem. In recent years, the incidence of human mycobacterial infection due to species other than M. tb has increased. However, the lack of specific, rapid, and inexpensive methods for identification of mycobacterial species remains a pressing problem. A diagnostic test was developed for mycobacterial strain differentiation utilizing a double-step multiplex real time PCR together with melting curve analysis for identifying and distinguishing among M. tb, M. bovis BCG, other members of M. tb. complex, M. avium, and non-tuberculosis mycobacteria. The assay was tested using 167 clinical sputum samples in comparison with acid-fast staining and culturing. Using only the first step (step A) the assay achieved sensitivity and specificity of 81% and 95%, respectively. The detection limit was equivalent to 50 genome copies. PMID:26513906

  15. Novel algorithm for real-time onset detection of surface electromyography in step-tracking wrist movements.

    PubMed

    Kuroda, Yoshihiro; Nisky, Ilana; Uranishi, Yuki; Imura, Masataka; Okamura, Allison M; Oshiro, Osamu

    2013-01-01

    We present a novel algorithm for real-time detection of the onset of surface electromyography signal in step-tracking wrist movements. The method identifies abrupt increase of the quasi-tension signal calculated from sEMG resulting from the step-by-step recruitment of activated motor units. We assessed the performance of our proposed algorithm using both simulated and real sEMG signals, and compared with two existing detection methods. Evaluation with simulated sEMG showed that the detection accuracy of our method is robust to different signal-to-noise ratios, and that it outperforms the existing methods in terms of bias when the noise is large (low SNR). Evaluation with real sEMG analysis also indicated better detection performance compared to existing methods. PMID:24110123

  16. Ultra-fast consensus of discrete-time multi-agent systems with multi-step predictive output feedback

    NASA Astrophysics Data System (ADS)

    Zhang, Wenle; Liu, Jianchang

    2016-04-01

    This article addresses the ultra-fast consensus problem of high-order discrete-time multi-agent systems based on a unified consensus framework. A novel multi-step predictive output mechanism is proposed under a directed communication topology containing a spanning tree. By predicting the outputs of a network several steps ahead and adding this information into the consensus protocol, it is shown that the asymptotic convergence factor is improved by a power of q + 1 compared to the routine consensus. The difficult problem of selecting the optimal control gain is solved well by introducing a variable called convergence step. In addition, the ultra-fast formation achievement is studied on the basis of this new consensus protocol. Finally, the ultra-fast consensus with respect to a reference model and robust consensus is discussed. Some simulations are performed to illustrate the effectiveness of the theoretical results.

  17. Issues in measure-preserving three dimensional flow integrators: Self-adjointness, reversibility, and non-uniform time stepping

    SciTech Connect

    Finn, John M.

    2015-03-01

    Properties of integration schemes for solenoidal fields in three dimensions are studied, with a focus on integrating magnetic field lines in a plasma using adaptive time stepping. It is shown that implicit midpoint (IM) and a scheme we call three-dimensional leapfrog (LF) can do a good job (in the sense of preserving KAM tori) of integrating fields that are reversible, or (for LF) have a 'special divergence-free' property. We review the notion of a self-adjoint scheme, showing that such schemes are at least second order accurate and can always be formed by composing an arbitrary scheme with its adjoint. We also review the concept of reversibility, showing that a reversible but not exactly volume-preserving scheme can lead to a fractal invariant measure in a chaotic region, although this property may not often be observable. We also show numerical results indicating that the IM and LF schemes can fail to preserve KAM tori when the reversibility property (and the SDF property for LF) of the field is broken. We discuss extensions to measure preserving flows, the integration of magnetic field lines in a plasma and the integration of rays for several plasma waves. The main new result of this paper relates to non-uniform time stepping for volume-preserving flows. We investigate two potential schemes, both based on the general method of Ref. [11], in which the flow is integrated in split time steps, each Hamiltonian in two dimensions. The first scheme is an extension of the method of extended phase space, a well-proven method of symplectic integration with non-uniform time steps. This method is found not to work, and an explanation is given. The second method investigated is a method based on transformation to canonical variables for the two split-step Hamiltonian systems. This method, which is related to the method of non-canonical generating functions of Ref. [35], appears to work very well.

  18. Counterrotating prop-fan simulations which feature a relative-motion multiblock grid decomposition enabling arbitrary time-steps

    NASA Technical Reports Server (NTRS)

    Janus, J. Mark; Whitfield, David L.

    1990-01-01

    Improvements are presented of a computer algorithm developed for the time-accurate flow analysis of rotating machines. The flow model is a finite volume method utilizing a high-resolution approximate Riemann solver for interface flux definitions. The numerical scheme is a block LU implicit iterative-refinement method which possesses apparent unconditional stability. Multiblock composite gridding is used to orderly partition the field into a specified arrangement of blocks exhibiting varying degrees of similarity. Block-block relative motion is achieved using local grid distortion to reduce grid skewness and accommodate arbitrary time step selection. A general high-order numerical scheme is applied to satisfy the geometric conservation law. An even-blade-count counterrotating unducted fan configuration is chosen for a computational study comparing solutions resulting from altering parameters such as time step size and iteration count. The solutions are compared with measured data.

  19. Stable Collocated-grid Finite Difference Seismic Wave Modeling Using Discontinuous Grids with Locally Variable Time Steps

    NASA Astrophysics Data System (ADS)

    Li, H.; Zhang, Z.; Chen, X.

    2012-12-01

    It is widely accepted that they are oversampled in spatial grid spacing and temporal time step in the high speed medium if uniform grids are used for the numerical simulation. This oversampled grid spacing and time step will lower the efficiency of the calculation, especially high velocity contrast exists. Based on the collocated-grid finite-difference method (FDM), we present an algorithm of spatial discontinuous grid, with localized grid blocks and locally varying time steps, which will increase the efficiency of simulation of seismic wave propagation and earthquake strong ground motion. According to the velocity structure, we discretize the model into discontinuous grid blocks, and the time step of each block is determined according to the local stability. The key problem of the discontinuous grid method is the connection between grid blocks with different grid spacing. We use a transitional area overlapped by both of the finer and the coarser grids to deal with the problem. In the transitional area, the values of finer ghost points are obtained by interpolation from the coarser grid in space and time domain, while the values of coarser ghost points are obtained by downsampling from the finer grid. How to deal with coarser ghost points can influent the stability of long time simulation. After testing different downsampling methods and finally we choose the Gaussian filtering. Basically, 4th order Rung-Kutta scheme will be used for the time integral for our numerical method. For our discontinuous grid FDM, discontinuous time steps for the coarser and the finer grids will be used to increase the simulation efficiency. Numerical tests indicate that our method can provide a stable solution even for the long time simulation without any additional filtration for grid spacing ratio n=2. And for larger grid spacing ratio, Gaussian filtration could be used to preserve the stability. With the collocated-grid FDM, which is flexible and accurate in implementation of free

  20. "I Have to Rest All the Time Because You Are Not Allowed to Play": Exploring Children's Perceptions of Autonomy during Sleep-Time in Long Day Care Services

    ERIC Educational Resources Information Center

    Nothard, Michaela; Irvine, Susan; Theobald, Maryanne; Staton, Sally; Pattinson, Cassandra; Thorpe, Karen

    2015-01-01

    Daytime sleep is a significant part of the daily routine for children attending early childhood education and care (ECEC) services in Australia and many other countries. The practice of sleep-time can account for a substantial portion of the day in ECEC and often involves a mandated sleep/rest period for all children, including older…

  1. Identification of the coupling step in Na(+)-translocating NADH:quinone oxidoreductase from real-time kinetics of electron transfer.

    PubMed

    Belevich, Nikolai P; Bertsova, Yulia V; Verkhovskaya, Marina L; Baykov, Alexander A; Bogachev, Alexander V

    2016-02-01

    Bacterial Na(+)-translocating NADH:quinone oxidoreductase (Na(+)-NQR) uses a unique set of prosthetic redox groups-two covalently bound FMN residues, a [2Fe-2S] cluster, FAD, riboflavin and a Cys4[Fe] center-to catalyze electron transfer from NADH to ubiquinone in a reaction coupled with Na(+) translocation across the membrane. Here we used an ultra-fast microfluidic stopped-flow instrument to determine rate constants and the difference spectra for the six consecutive reaction steps of Vibrio harveyi Na(+)-NQR reduction by NADH. The instrument, with a dead time of 0.25 ms and optical path length of 1 cm allowed collection of visible spectra in 50-μs intervals. By comparing the spectra of reaction steps with the spectra of known redox transitions of individual enzyme cofactors, we were able to identify the chemical nature of most intermediates and the sequence of electron transfer events. A previously unknown spectral transition was detected and assigned to the Cys4[Fe] center reduction. Electron transfer from the [2Fe-2S] cluster to the Cys4[Fe] center and all subsequent steps were markedly accelerated when Na(+) concentration was increased from 20 μM to 25 mM, suggesting coupling of the former step with tight Na(+) binding to or occlusion by the enzyme. An alternating access mechanism was proposed to explain electron transfer between subunits NqrF and NqrC. According to the proposed mechanism, the Cys4[Fe] center is alternatively exposed to either side of the membrane, allowing the [2Fe-2S] cluster of NqrF and the FMN residue of NqrC to alternatively approach the Cys4[Fe] center from different sides of the membrane. PMID:26655930

  2. PHOEBE - step by step manual

    NASA Astrophysics Data System (ADS)

    Zasche, P.

    2016-03-01

    An easy step-by-step manual of PHOEBE is presented. It should serve as a starting point for the first time users of PHOEBE analyzing the eclipsing binary light curve. It is demonstrated on one particular detached system also with the downloadable data and the whole procedure is described easily till the final trustworthy fit is being reached.

  3. Finite-difference modeling with variable grid-size and adaptive time-step in porous media

    NASA Astrophysics Data System (ADS)

    Liu, Xinxin; Yin, Xingyao; Wu, Guochen

    2014-04-01

    Forward modeling of elastic wave propagation in porous media has great importance for understanding and interpreting the influences of rock properties on characteristics of seismic wavefield. However, the finite-difference forward-modeling method is usually implemented with global spatial grid-size and time-step; it consumes large amounts of computational cost when small-scaled oil/gas-bearing structures or large velocity-contrast exist underground. To overcome this handicap, combined with variable grid-size and time-step, this paper developed a staggered-grid finite-difference scheme for elastic wave modeling in porous media. Variable finite-difference coefficients and wavefield interpolation were used to realize the transition of wave propagation between regions of different grid-size. The accuracy and efficiency of the algorithm were shown by numerical examples. The proposed method is advanced with low computational cost in elastic wave simulation for heterogeneous oil/gas reservoirs.

  4. Convergence of a class of semi-implicit time-stepping schemes for nonsmooth rigid multibody dynamics.

    SciTech Connect

    Gavrea, B. I.; Anitescu, M.; Potra, F. A.; Mathematics and Computer Science; Univ. of Pennsylvania; Univ. of Maryland

    2008-01-01

    In this work we present a framework for the convergence analysis in a measure differential inclusion sense of a class of time-stepping schemes for multibody dynamics with contacts, joints, and friction. This class of methods solves one linear complementarity problem per step and contains the semi-implicit Euler method, as well as trapezoidal-like methods for which second-order convergence was recently proved under certain conditions. By using the concept of a reduced friction cone, the analysis includes, for the first time, a convergence result for the case that includes joints. An unexpected intermediary result is that we are able to define a discrete velocity function of bounded variation, although the natural discrete velocity function produced by our algorithm may have unbounded variation.

  5. Review of RT-LAB and Steps Involved for Implementation of a Simulink Model from MATLAB to REAL-TIME

    NASA Astrophysics Data System (ADS)

    Mikkili, Suresh; Panda, Anup Kumar

    2013-11-01

    In recent days, every researcher wants to develop his/her model in real-time. Simulation tools have been widely used for the design and improvement of electrical systems since the mid-twentieth century. The evolution of simulation tools has progressed in step with the evolution of computing technologies. Now a days, computing technologies have improved dramatically in performance and become widely available at a steadily decreasing cost. Consequently, simulation tools have also seen dramatic performance gains and steady cost decreases. Researchers and engineers now have access to affordable, high-performance simulation tools that were previously too cost prohibitive, except for the largest manufacturers and utilities.This article has introduced a specific class of digital simulator known as a real-time simulator by answering the questions "What is real-time simulation?" "Why is it needed" and "How it works". The latest trend in real-time simulation consists of exporting simulation models to FPGA. In this article, the steps involved for implementation of a model from MATLAB to REAL-TIME are provided in detail. The detailed real-time results are presented to support the feasibility of real-time digital simulator.

  6. High resolution frequency to time domain transformations applied to the stepped carrier MRIS measurements

    NASA Technical Reports Server (NTRS)

    Ardalan, Sasan H.

    1992-01-01

    Two narrow-band radar systems are developed for high resolution target range estimation in inhomogeneous media. They are reformulations of two presently existing systems such that high resolution target range estimates may be achieved despite the use of narrow bandwidth radar pulses. A double sideband suppressed carrier radar technique originally derived in 1962, and later abandoned due to its inability to accurately measure target range in the presence of an interfering reflection, is rederived to incorporate the presence of an interfering reflection. The new derivation shows that the interfering reflection causes a period perturbation in the measured phase response. A high resolution spectral estimation technique is used to extract the period of this perturbation leading to accurate target range estimates independent of the signal-to-interference ratio. A non-linear optimal signal processing algorithm is derived for a frequency-stepped continuous wave radar system. The resolution enhancement offered by optimal signal processing of the data over the conventional Fourier Transform technique is clearly demonstrated using measured radar data. A method for modeling plane wave propagation in inhomogeneous media based on transmission line theory is derived and studied. Several simulation results including measurement of non-uniform electron plasma densities that develop near the heat tiles of a space re-entry vehicle are presented which verify the validity of the model.

  7. Spectral (600-1050 nm) time exposures (99.6 μs) of a lightning stepped leader

    NASA Astrophysics Data System (ADS)

    Warner, Tom A.; Orville, Richard E.; Marshall, J. L.; Huggins, Kyle

    2011-06-01

    A cloud-to-ground lightning stepped leader has been recorded with a slitless spectrograph at a recording rate of 10,000 images per second at a distance of 0.6 km. Five sequential images of the leader spectra were recorded with an exposure (integration) time of 99.6 μs each over a spectral range from 600 to 1050 nm. These are the first stepped leader spectra covering the range 600 to 1050 nm. The last three spectra, obtained immediately before the return stroke, were analyzed at an altitude of between 108 and 122 m above a struck vehicle. The spectral emissions in the near infrared are dominated by neutral nitrogen and oxygen emissions, and Hα, with only a few emission lines from singly ionized nitrogen. A singly ionized nitrogen line at 661.1 nm is present in the first analyzed image, but not in the two subsequent images at the same height, which suggests a cooling of the channel. The emissions are integrated over a 99.6 μs exposure time and therefore show no evidence of stepping. The ensuing negative return stroke was detected by the National Lightning Detection Network and had an estimated peak current of -15.2 kA. One subsequent stroke was outside the field of view of the spectrograph. The flash occurred on 11 September 2009 near New Underwood, South Dakota, and the exact location of the first stroke is known because it struck a car traveling on Interstate 90. The stepped leader two-dimensional speed increased in the last four steps from 1.53 × 105 to 2.42 × 105 m/s with an average of 2.03 × 105 m/s.

  8. Finite time step and spatial grid effects in δf simulation of warm plasmas

    NASA Astrophysics Data System (ADS)

    Sturdevant, Benjamin J.; Parker, Scott E.

    2016-01-01

    This paper introduces a technique for analyzing time integration methods used with the particle weight equations in δf method particle-in-cell (PIC) schemes. The analysis applies to the simulation of warm, uniform, periodic or infinite plasmas in the linear regime and considers the collective behavior similar to the analysis performed by Langdon for full-f PIC schemes [1,2]. We perform both a time integration analysis and spatial grid analysis for a kinetic ion, adiabatic electron model of ion acoustic waves. An implicit time integration scheme is studied in detail for δf simulations using our weight equation analysis and for full-f simulations using the method of Langdon. It is found that the δf method exhibits a CFL-like stability condition for low temperature ions, which is independent of the parameter characterizing the implicitness of the scheme. The accuracy of the real frequency and damping rate due to the discrete time and spatial schemes is also derived using a perturbative method. The theoretical analysis of numerical error presented here may be useful for the verification of simulations and for providing intuition for the design of new implicit time integration schemes for the δf method, as well as understanding differences between δf and full-f approaches to plasma simulation.

  9. Parallel machine scheduling with step-deteriorating jobs and setup times by a hybrid discrete cuckoo search algorithm

    NASA Astrophysics Data System (ADS)

    Guo, Peng; Cheng, Wenming; Wang, Yi

    2015-11-01

    This article considers the parallel machine scheduling problem with step-deteriorating jobs and sequence-dependent setup times. The objective is to minimize the total tardiness by determining the allocation and sequence of jobs on identical parallel machines. In this problem, the processing time of each job is a step function dependent upon its starting time. An individual extended time is penalized when the starting time of a job is later than a specific deterioration date. The possibility of deterioration of a job makes the parallel machine scheduling problem more challenging than ordinary ones. A mixed integer programming model for the optimal solution is derived. Due to its NP-hard nature, a hybrid discrete cuckoo search algorithm is proposed to solve this problem. In order to generate a good initial swarm, a modified Biskup-Hermann-Gupta (BHG) heuristic called MBHG is incorporated into the population initialization. Several discrete operators are proposed in the random walk of Lévy flights and the crossover search. Moreover, a local search procedure based on variable neighbourhood descent is integrated into the algorithm as a hybrid strategy in order to improve the quality of elite solutions. Computational experiments are executed on two sets of randomly generated test instances. The results show that the proposed hybrid algorithm can yield better solutions in comparison with the commercial solver CPLEX® with a one hour time limit, the discrete cuckoo search algorithm and the existing variable neighbourhood search algorithm.

  10. Numerical simulation of diffusion MRI signals using an adaptive time-stepping method.

    PubMed

    Li, Jing-Rebecca; Calhoun, Donna; Poupon, Cyril; Le Bihan, Denis

    2014-01-20

    The effect on the MRI signal of water diffusion in biological tissues in the presence of applied magnetic field gradient pulses can be modelled by a multiple compartment Bloch-Torrey partial differential equation. We present a method for the numerical solution of this equation by coupling a standard Cartesian spatial discretization with an adaptive time discretization. The time discretization is done using the explicit Runge-Kutta-Chebyshev method, which is more efficient than the forward Euler time discretization for diffusive-type problems. We use this approach to simulate the diffusion MRI signal from the extra-cylindrical compartment in a tissue model of the brain gray matter consisting of cylindrical and spherical cells and illustrate the effect of cell membrane permeability. PMID:24351275

  11. Numerical simulation of diffusion MRI signals using an adaptive time-stepping method

    NASA Astrophysics Data System (ADS)

    Li, Jing-Rebecca; Calhoun, Donna; Poupon, Cyril; Le Bihan, Denis

    2014-01-01

    The effect on the MRI signal of water diffusion in biological tissues in the presence of applied magnetic field gradient pulses can be modelled by a multiple compartment Bloch-Torrey partial differential equation. We present a method for the numerical solution of this equation by coupling a standard Cartesian spatial discretization with an adaptive time discretization. The time discretization is done using the explicit Runge-Kutta-Chebyshev method, which is more efficient than the forward Euler time discretization for diffusive-type problems. We use this approach to simulate the diffusion MRI signal from the extra-cylindrical compartment in a tissue model of the brain gray matter consisting of cylindrical and spherical cells and illustrate the effect of cell membrane permeability.

  12. Steps toward an Empirical Evaluation of Robust Regression Applied to Reaction-Time Data.

    ERIC Educational Resources Information Center

    Sternberg, Saul; And Others

    Because analyses of reaction-time data are sensitive to aberrant observations and violations of statistical assumptions, a new approach is suggested. In this empirical approach, one applies the same criteria to the problem of selecting a statistical method as one uses to select among alternative experimental procedures. Six criteria are presented…

  13. Leap Frog and Time Step Sub-Cycle Scheme for Coupled Neutronics and Thermal-Hydraulic Codes

    SciTech Connect

    Lu, S.

    2002-07-01

    As the result of the advancing TCP/IP based inter-process communication technology, more and more legacy thermal-hydraulic codes have been coupled with neutronics codes to provide best-estimate capabilities for reactivity related reactor transient analysis. Most of the coupling schemes are based on closely coupled serial or parallel approaches. Therefore, the execution of the coupled codes usually requires significant CPU time, when a complicated system is analyzed. Leap Frog scheme has been used to reduce the run time. The extent of the decoupling is usually determined based on a trial and error process for a specific analysis. It is the intent of this paper to develop a set of general criteria, which can be used to invoke the automatic Leap Frog algorithm. The algorithm will not only provide the run time reduction but also preserve the accuracy. The criteria will also serve as the base of an automatic time step sub-cycle scheme when a sudden reactivity change is introduced and the thermal-hydraulic code is marching with a relatively large time step. (authors)

  14. The ESO adaptive optics real-time computer platform: a step toward the future

    NASA Astrophysics Data System (ADS)

    Fedrigo, Enrico; Donaldson, Robert; Soenke, Christian; Hubin, Norbert N.

    2004-10-01

    ESO now operates several AO systems in the Paranal observatory. Most of them are the outcome of different and independent efforts resulting in different and incompatible systems with all the problems of maintaining and evolving them. At the same time, industry is now proposing powerful embedded computers and new standard technologies that enable the construction of massive real time parallel computers, with a technology roadmap that looks extremely promising. The ESO AO Platform initiative aims at taking this unique opportunity of gathering all the experience accumulated so far in building and operating AO system and the recent advances offered by the industry to define and build a standard hardware and software platform able to run every AO system of the near future of the VLT with an eye towards OWL. We review the key technologies that enable the design of a common AO-RTC and we discuss the main choices of the AO Platform initiative.

  15. Paper Laser: a step towards a time scale generation from an ensemble of optical clocks

    NASA Astrophysics Data System (ADS)

    Ortiz, C. A.; de Carlos, E.; Lopez, J. M.

    2016-06-01

    In this paper a simple and innovative technique to combine n optical frequencies with the aim to produce a virtual laser with superior metrological characteristics is introduced. The algorithms to combine a number of clocks to produce a virtual clock, which is also referred as paper clock, are well known. An example of this is the statistical generation of the UTC time scale by the Bureau International des Poids et Mesures (BIPM) using a recursive algorithm (ALGOS). A similar algorithm to combine n optical frequencies, all of them with same nominal value, to produce a “paper laser” whose frequency is known through its difference with respect to the optical frequencies of the ensemble is proposed here. As a demonstration of this, three optical frequencies stabilized to the D2 Cs-133 line, all of them with similar frequency stability were experimentally combined. A paper laser has been produced during hours whose frequency stability is about 3-1/2 times with respect to the original optical frequencies. This technique can be applied to combine ultra-stable optical frequencies to produce a paper laser that can be materialized by correcting one of the real optical frequencies of the ensemble. The robustness and stability of a paper laser is very attractive to produce a time scale from its operation.

  16. Accelerometer data requirements for reliable estimation of habitual physical activity and sedentary time of children during the early years - a worked example following a stepped approach.

    PubMed

    Bingham, Daniel D; Costa, Silvia; Clemes, Stacy A; Routen, Ash C; Moore, Helen J; Barber, Sally E

    2016-10-01

    This study presents a worked example of a stepped process to reliably estimate the habitual physical activity and sedentary time of a sample of young children. A total of 299 children (2.9 ± 0.6 years) were recruited. Outcome variables were daily minutes of total physical activity, sedentary time, moderate to vigorous physical activity and proportional values of each variable. In total, 282 (94%) provided 3 h of accelerometer data on ≥1 day and were included in a 6-step process: Step-1: determine minimum wear-time; Step-2: process 7-day-data; Step-3: determine the inclusion of a weekend day; Step-4: examine day-to-day variability; Step-5: calculate single day intraclass correlation (ICC) (2,1); Step-6: calculate number of days required to reach reliability. Following the process the results were, Step-1: 6 h was estimated as minimum wear-time of a standard day. Step-2: 98 (32%) children had ≥6 h wear on 7 days. Step-3: no differences were found between weekdays and weekend days (P ≥ 0.05). Step-4: no differences were found between day-to-day variability (P ≥ 0.05). Step-5: single day ICC's (2,1) ranged from 0.48 (total physical activity and sedentary time) to 0.53 (proportion of moderate to vigorous physical activity). Step-6: to reach reliability (ICC = 0.7), 3 days were required for all outcomes. In conclusion following a 7 day wear protocol, ≥6 h on any 3 days was found to have acceptable reliability. The stepped-process offers researchers a method to derive sample-specific wear-time criterion. PMID:26920123

  17. Issues in measure-preserving three dimensional flow integrators: Self-adjointness, reversibility, and non-uniform time stepping

    SciTech Connect

    Finn, John M.

    2015-03-15

    Properties of integration schemes for solenoidal fields in three dimensions are studied, with a focus on integrating magnetic field lines in a plasma using adaptive time stepping. It is shown that implicit midpoint (IM) and a scheme we call three-dimensional leapfrog (LF) can do a good job (in the sense of preserving KAM tori) of integrating fields that are reversible, or (for LF) have a “special divergence-free” (SDF) property. We review the notion of a self-adjoint scheme, showing that such schemes are at least second order accurate and can always be formed by composing an arbitrary scheme with its adjoint. We also review the concept of reversibility, showing that a reversible but not exactly volume-preserving scheme can lead to a fractal invariant measure in a chaotic region, although this property may not often be observable. We also show numerical results indicating that the IM and LF schemes can fail to preserve KAM tori when the reversibility property (and the SDF property for LF) of the field is broken. We discuss extensions to measure preserving flows, the integration of magnetic field lines in a plasma and the integration of rays for several plasma waves. The main new result of this paper relates to non-uniform time stepping for volume-preserving flows. We investigate two potential schemes, both based on the general method of Feng and Shang [Numer. Math. 71, 451 (1995)], in which the flow is integrated in split time steps, each Hamiltonian in two dimensions. The first scheme is an extension of the method of extended phase space, a well-proven method of symplectic integration with non-uniform time steps. This method is found not to work, and an explanation is given. The second method investigated is a method based on transformation to canonical variables for the two split-step Hamiltonian systems. This method, which is related to the method of non-canonical generating functions of Richardson and Finn [Plasma Phys. Controlled Fusion 54, 014004 (2012

  18. Issues in measure-preserving three dimensional flow integrators: Self-adjointness, reversibility, and non-uniform time stepping

    DOE PAGESBeta

    Finn, John M.

    2015-03-01

    Properties of integration schemes for solenoidal fields in three dimensions are studied, with a focus on integrating magnetic field lines in a plasma using adaptive time stepping. It is shown that implicit midpoint (IM) and a scheme we call three-dimensional leapfrog (LF) can do a good job (in the sense of preserving KAM tori) of integrating fields that are reversible, or (for LF) have a 'special divergence-free' property. We review the notion of a self-adjoint scheme, showing that such schemes are at least second order accurate and can always be formed by composing an arbitrary scheme with its adjoint. Wemore » also review the concept of reversibility, showing that a reversible but not exactly volume-preserving scheme can lead to a fractal invariant measure in a chaotic region, although this property may not often be observable. We also show numerical results indicating that the IM and LF schemes can fail to preserve KAM tori when the reversibility property (and the SDF property for LF) of the field is broken. We discuss extensions to measure preserving flows, the integration of magnetic field lines in a plasma and the integration of rays for several plasma waves. The main new result of this paper relates to non-uniform time stepping for volume-preserving flows. We investigate two potential schemes, both based on the general method of Ref. [11], in which the flow is integrated in split time steps, each Hamiltonian in two dimensions. The first scheme is an extension of the method of extended phase space, a well-proven method of symplectic integration with non-uniform time steps. This method is found not to work, and an explanation is given. The second method investigated is a method based on transformation to canonical variables for the two split-step Hamiltonian systems. This method, which is related to the method of non-canonical generating functions of Ref. [35], appears to work very well.« less

  19. First steps towards real-time radiography at the NECTAR facility

    NASA Astrophysics Data System (ADS)

    Bücherl, T.; Wagner, F. M.; v. Gostomski, Ch. Lierse

    2009-06-01

    The beam tube SR10 at Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II) provides an intense beam of fission neutrons for medical application (MEDAPP) and for radiography and tomography of technical and other objects (NECTAR). The high neutron flux of up to 9.8E+07 cm -2 s -1 (depending on filters and collimation) with a mean energy of about 1.9 MeV at the sample position at the NECTAR facility prompted an experimental feasibility study to investigate the potential for real-time (RT) radiography.

  20. Steps Toward Real-Time Atmospheric Phase Fluctuation Correction for a High Resolution Radar System

    NASA Astrophysics Data System (ADS)

    Denn, Grant R.; Geldzahler, Barry; Birr, Rick; Brown, Robert; Hoblitzell, Richard; Grant, Kevin; Miller, Michael; Woods, Gary; Archuleta, Arby; Ciminera, Michael; Cornish, Timothy; davarian, faramaz; kocz, jonathan; lee, dennis; Morabito, David Dominic; Soriano, Melissa; Tsao, Philip; Vilnrotter, Victor; Jakeman-Flores, Hali; Ott, melanie; Thomes, W. Joe; Soloff, Jason; NASA Kennedy Space Center, Jet Propulsion Laboratory, NASA Goddard Space Flight Center, NASA Johnson Space Flight Center, Metropolitan State University of Denver

    2016-01-01

    NASA is pursuing a demonstration of coherent uplink arraying at 7.145-7.190 GHz (X-band) and 30-31 GHz (Ka-band) using three 12m diameter COTS antennas separated by 60m at the Kennedy Space Center in Florida, with the goal of a high-power, high-resolution radar array that employs real-time correction for tropospheric phase fluctuation. The major uses for this array will be (a) observations of Near Earth Objects, (b) detection and tracking of orbital debris, (c) high power emergency uplink capability for spacecraft, and (d) radio science experiments.

  1. Efficient computation of the Grünwald-Letnikov fractional diffusion derivative using adaptive time step memory

    NASA Astrophysics Data System (ADS)

    MacDonald, Christopher L.; Bhattacharya, Nirupama; Sprouse, Brian P.; Silva, Gabriel A.

    2015-09-01

    Computing numerical solutions to fractional differential equations can be computationally intensive due to the effect of non-local derivatives in which all previous time points contribute to the current iteration. In general, numerical approaches that depend on truncating part of the system history while efficient, can suffer from high degrees of error and inaccuracy. Here we present an adaptive time step memory method for smooth functions applied to the Grünwald-Letnikov fractional diffusion derivative. This method is computationally efficient and results in smaller errors during numerical simulations. Sampled points along the system's history at progressively longer intervals are assumed to reflect the values of neighboring time points. By including progressively fewer points backward in time, a temporally 'weighted' history is computed that includes contributions from the entire past of the system, maintaining accuracy, but with fewer points actually calculated, greatly improving computational efficiency.

  2. Steps Towards an Operational Service Using Near Real-Time Altimeter Data

    NASA Astrophysics Data System (ADS)

    Ash, E. R.

    2006-07-01

    Thanks largely to modern computing power, numerical forecasts of w inds and waves over the oceans ar e ev er improving, offering greater accuracy and finer resolution in time and sp ace. Howev er, it is recognized that met-ocean models still have difficulty in accurately forecasting sever e w eather conditions, conditions that cause the most damag e and difficulty in mar itime operations. Ther efore a key requir emen t is to provid e improved information on sever e conditions. No individual measur emen t or prediction system is perfect. Offshore buoys provide a continuous long-ter m record of wind and wave conditions, but only at a limited numb er of sites. Satellite data offer all-weath er global cov erage, but with relatively infrequen t samp ling. Forecasts rely on imperf ect numerical schemes and the ab ility to manage a vast quantity of input data. Therefore the best system is one that integr ates information from all available sources, taking advantage of the benef its that each can offer. We report on an initiative supported by the European Space Agen cy (ESA) which investig ated how satellite data could be used to enhan ce systems to provide Near Real Time mon itor ing of met-ocean conditions.

  3. In the time of significant generational diversity - surgical leadership must step up!

    PubMed

    Money, Samuel R; O'Donnell, Mark E; Gray, Richard J

    2014-02-01

    The diverse attitudes and motivations of surgeons and surgical trainees within different age groups present an important challenge for surgical leaders and educators. These challenges to surgical leadership are not unique, and other industries have likewise needed to grapple with how best to manage these various age groups. The authors will herein explore management and leadership for surgeons in a time of age diversity, define generational variations within "Baby-Boomer", "Generation X" and "Generation Y" populations, and identify work ethos concepts amongst these three groups. The surgical community must understand and embrace these concepts in order to continue to attract a stellar pool of applicants from medical school. By not accepting the changing attitudes and motivations of young trainees and medical students, we may disenfranchise a high percentage of potential future surgeons. Surgical training programs will fill, but will they contain the highest quality trainees? PMID:24090677

  4. Time step size and model stiffness in the simulated slew of a tow of square sails

    NASA Astrophysics Data System (ADS)

    Greschik, Gyula

    2011-12-01

    In order to assess space tow solar sail stability and control feasibility, slew simulations are performed for a simplified but dynamically representative km-class tow-like sail of sixteen 25 m square units (10,000 m 2 total area and 110 kg gross mass) with a 250 kg payload. It is seen that, for the dimensions considered, the space tow concept is structurally sound and its control is feasible. While observed instabilities are identified as numeric in nature and are eliminated accordingly, their very occurrence highlights the need for a refinement of the model for future studies. The analyses are carried out with custom software implementing non-standard implicit-iterative time integration with innovative elements. A new damping model, specifically tailored for the analysis of truly gossamer systems such as solar sails, is also proposed.

  5. One-step Real-time Food Quality Analysis by Simultaneous DSC-FTIR Microspectroscopy.

    PubMed

    Lin, Shan-Yang; Lin, Chih-Cheng

    2016-01-01

    This review discusses an analytical technique that combines differential scanning calorimetry and Fourier-transform infrared (DSC-FTIR) microspectroscopy, which simulates the accelerated stability test and detects decomposition products simultaneously in real time. We show that the DSC-FTIR technique is a fast, simple and powerful analytical tool with applications in food sciences. This technique has been applied successfully to the simultaneous investigation of: encapsulated squid oil stability; the dehydration and intramolecular condensation of sweetener (aspartame); the dehydration, rehydration and solidification of trehalose; and online monitoring of the Maillard reaction for glucose (Glc)/asparagine (Asn) in the solid state. This technique delivers rapid and appropriate interpretations with food science applications. PMID:24762327

  6. Modelling of Thermal Advective Reactive Flow in Hydrothermal Mineral Systems Using an Implicit Time-stepped Finite Element Method.

    NASA Astrophysics Data System (ADS)

    Hornby, P. G.

    2005-12-01

    Understanding chemical and thermal processes taking place in hydrothermal mineral deposition systems could well be a key to unlocking new mineral reserves through improved targeting of exploration efforts. To aid in this understanding it is very helpful to be able to model such processes with sufficient fidelity to test process hypotheses. To gain understanding, it is often sufficient to obtain semi-quantitative results that model the broad aspects of the complex set of thermal and chemical effects taking place in hydrothermal systems. For example, it is often sufficient to gain an understanding of where thermal, geometric and chemical factors converge to precipitate gold (say) without being perfectly precise about how much gold is precipitated. The traditional approach is to use incompressible Darcy flow together with the Boussinesq approximation. From the flow field, the heat equation is used to advect-conduct the heat. The flow field is also used to transport solutes by solving an advection-dispersion-diffusion equation. The reactions in the fluid and between fluid and rock act as source terms for these advection-dispersion equations. Many existing modelling systems that are used for simulating such systems use explicit time marching schemes and finite differences. The disadvantage of this approach is the need to work on rectilinear grids and the number of time steps required by the Courant condition in the solute transport step. The second factor can be particularly significant if the chemical system is complex, requiring (at a minimum) an equilibrium calculation at each grid point at each time step. In the approach we describe, we use finite elements rather than finite differences, and the pressure, heat and advection-dispersion equations are solved implicitly. The general idea is to put unconditional numerical stability of the time integration first, and let accuracy assume a secondary role. It is in this sense that the method is semi-quantiative. However

  7. Navier-Stokes calculations for DFVLR F5-wing in wind tunnel using Runge-Kutta time-stepping scheme

    NASA Technical Reports Server (NTRS)

    Vatsa, V. N.; Wedan, B. W.

    1988-01-01

    A three-dimensional Navier-Stokes code using an explicit multistage Runge-Kutta type of time-stepping scheme is used for solving the transonic flow past a finite wing mounted inside a wind tunnel. Flow past the same wing in free air was also computed to assess the effect of wind-tunnel walls on such flows. Numerical efficiency is enhanced through vectorization of the computer code. A Cyber 205 computer with 32 million words of internal memory was used for these computations.

  8. Changing Safety Culture, One Step at a Time: The Value of the DOE-VPP Program at PNNL

    SciTech Connect

    Wright, Patrick A.; Isern, Nancy G.

    2005-02-01

    The primary value of the Pacific Northwest National Laboratory (PNNL) Voluntary Protection Program (VPP) is the ongoing partnership between management and staff committed to change Laboratory safety culture one step at a time. VPP enables PNNL's safety and health program to transcend a top-down, by-the-book approach to safety, and it also raises grassroots safety consciousness by promoting a commitment to safety and health 24 hours a day, 7 days a week. PNNL VPP is a dynamic, evolving program that fosters innovative approaches to continuous improvement in safety and health performance at the Laboratory.

  9. Mean square displacements with error estimates from non-equidistant time-step kinetic Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Leetmaa, Mikael; Skorodumova, Natalia V.

    2015-06-01

    We present a method to calculate mean square displacements (MSD) with error estimates from kinetic Monte Carlo (KMC) simulations of diffusion processes with non-equidistant time-steps. An analytical solution for estimating the errors is presented for the special case of one moving particle at fixed rate constant. The method is generalized to an efficient computational algorithm that can handle any number of moving particles or different rates in the simulated system. We show with examples that the proposed method gives the correct statistical error when the MSD curve describes pure Brownian motion and can otherwise be used as an upper bound for the true error.

  10. Interfacing a transient digitizer to a step-scan Fourier transform spectrometer for nanosecond time resolved spectroscopy

    SciTech Connect

    Letendre, L.T.; Dai, H.; McLaren, I.A.; Johnson, T.J.

    1999-01-01

    A new signal processing and data acquisition system has been developed that allows a Fourier transform spectrometer to be interfaced to external transient digitizers for time-resolved spectroscopy. Time resolution is limited only by the transient digitizer and detection system response time. For the present system it is about 1 ns. The capabilities of this system are demonstrated with visible Fourier transform spectra of both scattered laser light and fluorescence from electronically excited NO{sub 2} gas. {copyright} {ital 1999 American Institute of Physics.}

  11. Time-dependent rheological behavior of natural polysaccharide xanthan gum solutions in interrupted shear and step-incremental/reductional shear flow fields

    NASA Astrophysics Data System (ADS)

    Lee, Ji-Seok; Song, Ki-Won

    2015-11-01

    The objective of the present study is to systematically elucidate the time-dependent rheological behavior of concentrated xanthan gum systems in complicated step-shear flow fields. Using a strain-controlled rheometer (ARES), step-shear flow behaviors of a concentrated xanthan gum model solution have been experimentally investigated in interrupted shear flow fields with a various combination of different shear rates, shearing times and rest times, and step-incremental and step-reductional shear flow fields with various shearing times. The main findings obtained from this study are summarized as follows. (i) In interrupted shear flow fields, the shear stress is sharply increased until reaching the maximum stress at an initial stage of shearing times, and then a stress decay towards a steady state is observed as the shearing time is increased in both start-up shear flow fields. The shear stress is suddenly decreased immediately after the imposed shear rate is stopped, and then slowly decayed during the period of a rest time. (ii) As an increase in rest time, the difference in the maximum stress values between the two start-up shear flow fields is decreased whereas the shearing time exerts a slight influence on this behavior. (iii) In step-incremental shear flow fields, after passing through the maximum stress, structural destruction causes a stress decay behavior towards a steady state as an increase in shearing time in each step shear flow region. The time needed to reach the maximum stress value is shortened as an increase in step-increased shear rate. (iv) In step-reductional shear flow fields, after passing through the minimum stress, structural recovery induces a stress growth behavior towards an equilibrium state as an increase in shearing time in each step shear flow region. The time needed to reach the minimum stress value is lengthened as a decrease in step-decreased shear rate.

  12. A quantitative method for evaluating numerical simulation accuracy of time-transient Lamb wave propagation with its applications to selecting appropriate element size and time step.

    PubMed

    Wan, Xiang; Xu, Guanghua; Zhang, Qing; Tse, Peter W; Tan, Haihui

    2016-01-01

    Lamb wave technique has been widely used in non-destructive evaluation (NDE) and structural health monitoring (SHM). However, due to the multi-mode characteristics and dispersive nature, Lamb wave propagation behavior is much more complex than that of bulk waves. Numerous numerical simulations on Lamb wave propagation have been conducted to study its physical principles. However, few quantitative studies on evaluating the accuracy of these numerical simulations were reported. In this paper, a method based on cross correlation analysis for quantitatively evaluating the simulation accuracy of time-transient Lamb waves propagation is proposed. Two kinds of error, affecting the position and shape accuracies are firstly identified. Consequently, two quantitative indices, i.e., the GVE (group velocity error) and MACCC (maximum absolute value of cross correlation coefficient) derived from cross correlation analysis between a simulated signal and a reference waveform, are proposed to assess the position and shape errors of the simulated signal. In this way, the simulation accuracy on the position and shape is quantitatively evaluated. In order to apply this proposed method to select appropriate element size and time step, a specialized 2D-FEM program combined with the proposed method is developed. Then, the proper element size considering different element types and time step considering different time integration schemes are selected. These results proved that the proposed method is feasible and effective, and can be used as an efficient tool for quantitatively evaluating and verifying the simulation accuracy of time-transient Lamb wave propagation. PMID:26315506

  13. Review of Real-Time Simulator and the Steps Involved for Implementation of a Model from MATLAB/SIMULINK to Real-Time

    NASA Astrophysics Data System (ADS)

    Mikkili, Suresh; Panda, Anup Kumar; Prattipati, Jayanthi

    2014-07-01

    Nowadays the researchers want to develop their model in real-time environment. Simulation tools have been widely used for the design and improvement of electrical systems since the mid twentieth century. The evolution of simulation tools has progressed in step with the evolution of computing technologies. In recent years, computing technologies have improved dramatically in performance and become widely available at a steadily decreasing cost. Consequently, simulation tools have also seen dramatic performance gains and steady cost decreases. Researchers and engineers now have the access to affordable, high performance simulation tools that were previously too cost prohibitive, except for the largest manufacturers. This work has introduced a specific class of digital simulator known as a real-time simulator by answering the questions "what is real-time simulation", "why is it needed" and "how it works". The latest trend in real-time simulation consists of exporting simulation models to FPGA. In this article, the Steps involved for implementation of a model from MATLAB to REAL-TIME are provided in detail.

  14. Length and time for development of laminar flow in tubes following a step increase of volume flux

    NASA Astrophysics Data System (ADS)

    Chaudhury, Rafeed A.; Herrmann, Marcus; Frakes, David H.; Adrian, Ronald J.

    2015-01-01

    Laminar flows starting up from rest in round tubes are relevant to numerous industrial and biomedical applications. The two most common types are flows driven by an abruptly imposed constant pressure gradient or by an abruptly imposed constant volume flux. Analytical solutions are available for transient, fully developed flows, wherein streamwise development over the entrance length is absent (Szymanski in J de Mathématiques Pures et Appliquées 11:67-107, 1932; Andersson and Tiseth in Chem Eng Commun 112(1):121-133, 1992, respectively). They represent the transient responses of flows in tubes that are very long compared with the entrance length, a condition that is seldom satisfied in biomedical tube networks. This study establishes the entrance (development) length and development time of starting laminar flow in a round tube of finite length driven by a piston pump that produces a step change from zero flow to a constant volume flux for Reynolds numbers between 500 and 3,000. The flows are examined experimentally, using stereographic particle image velocimetry and computationally using computational fluid dynamics, and are then compared with the known analytical solutions for fully developed flow conditions in infinitely long tubes. Results show that step function volume flux start-up flows reach steady state and fully developed flow five times more quickly than those driven by a step function pressure gradient, a 500 % change when compared with existing estimates. Based on these results, we present new, simple guidelines for achieving experimental flows that are fully developed in space and time in realistic (finite) tube geometries. To a first approximation, the time to achieve steady spatially developing flow is nearly equal to the time needed to achieve steady, fully developed flow. Conversely, the entrance length needed to achieve fully developed transient flow is approximately equal to the length needed to achieve fully developed steady flow. Beyond this

  15. Simultaneous effects of allowed time, teaching method, ability, and student assessment of treatment on achievement in a high school biology course (ISIS)

    NASA Astrophysics Data System (ADS)

    Burkman, Ernest; Brezin, Michael; Griffin, Patrick

    The simultaneous effects of teaching method (self-directed, group directed, and teacher directed), allowed time for study, and two student variables (academic ability and assessment of treatment implementation) are described for student achievement in a high school biology course (ISIS). The variable student assessment of treatment implementation was viewed as a particularly important variable for two reasons: (1) in research by Stayrook, Corno, and Winne (1978) it has accounted for as much variance in achievement as the assigned treatment; and (2) it provides a means for controlling the range of implementation of teaching methods. A between-student analysis resulted in a description of effects complicated by interactions among all the variables. While the interactions were particularly strong in the student-directed method, it may generally be concluded that as time allowed for study decreased, students who perceived the treatment as being well implemented tended to have higher achievement. Also, it was found that the main effect of ability was quite strong. The results confirmed the importance of student assessment of treatment implementation as a descriptive variable. Additionally, the results suggest a qualification in the conclusion of Cronbach and Snow (1971) that individualized instruction tends to favor high-ability students; that conclusion may need to be modified to situations in which students fully perceive their autonomy.

  16. Compact Two-step Laser Time-of-Flight Mass Spectrometer for in Situ Analyses of Aromatic Organics on Planetary Missions

    NASA Technical Reports Server (NTRS)

    Getty, Stephanie; Brickerhoff, William; Cornish, Timothy; Ecelberger, Scott; Floyd, Melissa

    2012-01-01

    RATIONALE A miniature time-of-flight mass spectrometer has been adapted to demonstrate two-step laser desorption-ionization (LOI) in a compact instrument package for enhanced organics detection. Two-step LDI decouples the desorption and ionization processes, relative to traditional laser ionization-desorption, in order to produce low-fragmentation conditions for complex organic analytes. Tuning UV ionization laser energy allowed control ofthe degree of fragmentation, which may enable better identification of constituent species. METHODS A reflectron time-of-flight mass spectrometer prototype measuring 20 cm in length was adapted to a two-laser configuration, with IR (1064 nm) desorption followed by UV (266 nm) postionization. A relatively low ion extraction voltage of 5 kV was applied at the sample inlet. Instrument capabilities and performance were demonstrated with analysis of a model polycyclic aromatic hydrocarbon, representing a class of compounds important to the fields of Earth and planetary science. RESULTS L2MS analysis of a model PAH standard, pyrene, has been demonstrated, including parent mass identification and the onset o(tunable fragmentation as a function of ionizing laser energy. Mass resolution m/llm = 380 at full width at half-maximum was achieved which is notable for gas-phase ionization of desorbed neutrals in a highly-compact mass analyzer. CONCLUSIONS Achieving two-step laser mass spectrometry (L2MS) in a highly-miniature instrument enables a powerful approach to the detection and characterization of aromatic organics in remote terrestrial and planetary applications. Tunable detection of parent and fragment ions with high mass resolution, diagnostic of molecular structure, is possible on such a compact L2MS instrument. Selectivity of L2MS against low-mass inorganic salt interferences is a key advantage when working with unprocessed, natural samples, and a mechanism for the observed selectivity is presented.

  17. The STEP model: Characterizing simultaneous time effects on practice for flight simulator performance among middle-aged and older pilots.

    PubMed

    Kennedy, Quinn; Taylor, Joy; Noda, Art; Yesavage, Jerome; Lazzeroni, Laura C

    2015-09-01

    Understanding the possible effects of the number of practice sessions (practice) and time between practice sessions (interval) among middle-aged and older adults in real-world tasks has important implications for skill maintenance. Prior training and cognitive ability may impact practice and interval effects on real-world tasks. In this study, we took advantage of existing practice data from 5 simulated flights among 263 middle-aged and older pilots with varying levels of flight expertise (defined by U.S. Federal Aviation Administration proficiency ratings). We developed a new Simultaneous Time Effects on Practice (STEP) model: (a) to model the simultaneous effects of practice and interval on performance of the 5 flights, and (b) to examine the effects of selected covariates (i.e., age, flight expertise, and 3 composite measures of cognitive ability). The STEP model demonstrated consistent positive practice effects, negative interval effects, and predicted covariate effects. Age negatively moderated the beneficial effects of practice. Additionally, cognitive processing speed and intraindividual variability (IIV) in processing speed moderated the benefits of practice and/or the negative influence of interval for particular flight performance measures. Expertise did not interact with practice or interval. Results indicated that practice and interval effects occur in simulated flight tasks. However, processing speed and IIV may influence these effects, even among high-functioning adults. Results have implications for the design and assessment of training interventions targeted at middle-aged and older adults for complex real-world tasks. PMID:26280383

  18. Stress-vs-time signals allow the prediction of structurally catastrophic events during fracturing of immature cartilage and predetermine the biomechanical, biochemical, and structural impairment

    PubMed Central

    Rolauffs, Bernd; Kurz, Bodo; Felka, Tino; Rothdiener, Miriam; Uynuk-Ool, Tatiana; Aurich, Matthias; Frank, Eliot; Bahrs, Christian; Badke, Andreas; Stöckle, Ulrich; Aicher, Wilhelm K.; Grodzinsky, Alan J.

    2013-01-01

    Objective Trauma-associated cartilage fractures occur in children and adolescents with clinically significant incidence. Several studies investigated biomechanical injury by compressive forces but the injury-related stress has not been investigated extensively. In this study, we hypothesized that the biomechanical stress occurring during compressive injury predetermines the biomechanical, biochemical, and structural consequences. We specifically investigated whether the stress-vs-time signal correlated with the injurious damage and may allow prediction of cartilage matrix fracturing. Methods Superficial and deeper zones disks (SZDs, DZDs; immature bovine cartilage) were biomechanically characterized, injured (50% compression, 100%/sec strain-rate), and re-characterized. Correlations of the quantified functional, biochemical and histological damage with biomechanical parameters were zonally investigated. Results Injured SZDs exhibited decreased dynamic stiffness (by 93.04 ± 1.72%), unresolvable equilibrium moduli, structural damage (2.0 ± 0.5 on a 5-point-damage-scale), and 1.78-fold increased sGAG loss. DZDs remained intact. Measured stress-vs-time-curves during injury displayed 4 distinct shapes, which correlated with histological damage (p<0.001), loss of dynamic stiffness and sGAG (p<0.05). Damage prediction in a blinded experiment using stress-vs-time grades was 100%-correct and sensitive to differentiate single/complex matrix disruptions. Correlations of the dissipated energy and maximum stress rise with the extent of biomechanical and biochemical damage reached significance when SZDs and DZDs were analyzed as zonal composites but not separately. Conclusion The biomechanical stress that occurs during compressive injury predetermines the biomechanical, biochemical, and structural consequences and, thus, the structural and functional damage during cartilage fracturing. A novel biomechanical method based on the interpretation of compressive yielding allows the

  19. High-order time-stepping for nonlinear PDEs through rapid estimation of block Gaussian quadrature nodes

    NASA Astrophysics Data System (ADS)

    Lambers, James V.

    2016-06-01

    The stiffness of systems of ODEs that arise from spatial discretization of PDEs causes difficulties for both explicit and implicit time-stepping methods. Krylov Subspace Spectral (KSS) methods present a balance between the efficiency of explicit methods and the stability of implicit methods by computing each Fourier coefficient from an individualized approximation of the solution operator of the PDE. While KSS methods are explicit methods that exhibit a high order of accuracy and stability similar to that of implicit methods, their efficiency needs to be improved. Here, a detailed asymptotic study is performed in order to rapidly estimate all nodes, thus drastically reducing computational expense without sacrificing accuracy. Extension to PDEs on a disk, through expansions built on Legendre polynomials, is also discussed. Exponential propagation iterative (EPI) methods provide an efficient approach to the solution of large stiff nonlinear systems of ODE, compared to standard integrators. However, the bulk of the computational effort in these methods is due to products of matrix functions and vectors, which can become very costly at high resolution due to an increase in the number of Krylov projection steps needed to maintain accuracy. In this talk, it is proposed to modify EPI methods by using KSS methods, instead of standard Krylov projection methods, to compute products of matrix functions and vectors. Numerical experiments demonstrate that this modification causes the number of Krylov projection steps to become bounded independently of the grid size, thus dramatically improving efficiency and scalability. It is also demonstrated that the convergence of Krylov projection can be significantly accelerated, without noticeable loss of accuracy, through filtering techniques, thus improving performance and scalability even further.

  20. An FPGA-based frequency response analyzer for multisine and stepped sine measurements on stationary and time-varying impedance

    NASA Astrophysics Data System (ADS)

    Sanchez, B.; Fernandez, X.; Reig, S.; Bragos, R.

    2014-01-01

    We report the development of a field programmable gate array (FPGA) based frequency response analyzer (FRA) for impedance frequency response function (FRF) measurements using periodic excitations, i.e. sine waves and multisines. The stepped sine measurement uses two dedicated hardware-built digital embedded multiplier blocks to extract the phase and quadrature components of the output signal. The multisine FRF measurements compute the fast Fourier transform (FFT) of the input/output signals. In this paper, we describe its design, implementation and performance evaluation, performing electrical impedance spectroscopy (EIS) measurements on phantoms. The stepped sine accuracy is 1.21% at 1 kΩ (1%), the precision is 35 mΩ and the total harmonic distortion plus noise (THD+N) is -120 dB. As for the multisine impedance FRF measurements, the magnitude and phase precision are, respectively, 0.23 Ω at 48.828 kHz and 0.021 deg at 8.087 MHz when measuring a resistor 505 Ω (1%). The magnitude accuracy is 0.55% at 8.087 MHz while the phase accuracy is 0.17 deg at 6.54 MHz. In all, the stepped sine signal-to-noise ratio (SNR) is 84 dB and 65 dB at frequencies below and above 1 MHz respectively. The SNR for the multisine FRF measurements is above 65 dB (30 kHz-10 MHz). The FRA bandwidth is 610.4 mHz-12.5 MHz and the maximum FRF measurement rate exciting with multisines starting at 30 kHz is 200 spectra s-1. Based on its technical specifications and versatility, the FRA presented can be used in many applications, e.g. for getting insight quickly into the instantaneous impedance FRF of the time-varying impedance under test.

  1. A one step real-time RT-PCR assay for the quantitation of Wheat yellow mosaic virus (WYMV)

    PubMed Central

    2013-01-01

    Background Wheat yellow mosaic virus (WYMV) is an important pathogen in China and other countries. It is the member of the genus Bymovirus and transmitted primarily by Polymyxa graminis. The incidence of wheat infections in endemic areas has risen in recent years. Prompt and dependable identification of WYMV is a critical component of response to suspect cases. Methods In this study, a one step real-time RT-PCR, followed by standard curve analysis for the detection and identification of WYMV, was developed. Two reference genes, 18s RNA and β-actin were selected in order to adjust the veracity of the real-time RT-PCR assay. Results We developed a one-step Taqman-based real-time quantitative RT-PCR (RT-qPCR) assay targeting the conserved region of the 879 bp long full-length WYMV coat protein gene. The accuracy of normalized data was analyzed along with appropriate internal control genes: β-actin and 18s rRNA which were included in detecting of WYMV-infected wheat leaf tissues. The detectable end point sensitivity in RT-qPCR assay was reaching the minimum limit of the quantitative assay and the measurable copy numbers were about 30 at106-fold dilution of total RNA. This value was close to 104-fold more sensitive than that of indirect enzyme-linked immunosorbent assay. More positive samples were detected by RT-qPCR assay than gel-based RT-PCR when detecting the suspected samples collected from 8 regions of China. Based on presented results, RT-qPCR will provide a valuable method for the quantitative detection of WYMV. Conclusions The Taqman-based RT-qPCR assay is a faster, simpler, more sensitive and less expensive procedure for detection and quantification of WYMV than other currently used methods. PMID:23725024

  2. Deficits in stepping response time are associated with impairments in balance and mobility in people with Huntington disease

    PubMed Central

    Goldberg, Allon; Schepens, Stacey L.; Feely, Shawna M. E.; Garbern, James Y.; Miller, Lindsey J.; Siskind, Carly E.; Conti, Gerry E

    2010-01-01

    Huntington disease (HD) is a disorder characterized by chorea, dystonia, bradykinesia, cognitive decline and psychiatric comorbidities. Balance and gait impairments, as well as falls, are common manifestations of the disease. The importance of compensatory rapid stepping to maintain equilibrium in older adults is established, yet little is known of the role of stepping response times (SRTs) in balance control in people with HD. SRTs and commonly-used clinical measures of balance and mobility were evaluated in fourteen symptomatic participants with HD, and nine controls at a university mobility research laboratory. Relative and absolute reliability, as well as minimal detectable change in SRT were quantified in the HD participants. HD participants exhibited slower SRTs and poorer dynamic balance, mobility and motor performance than controls. HD participants also reported lower balance confidence than controls. Deficits in SRT were associated with low balance confidence and impairments on clinical measures of balance, mobility, and motor performance in HD participants. Measures of relative and absolute reliability indicate that SRT is reliable and reproducible across trials in people with HD. A moderately low percent minimal detectable change suggests that SRT appears sensitive to detecting real change in people with HD. SRT is impaired in people with HD and may be a valid and objective marker of disease progression. PMID:20804986

  3. Third-order-accurate numerical methods for efficient, large time-step solutions of mixed linear and nonlinear problems

    SciTech Connect

    Cobb, J.W.

    1995-02-01

    There is an increasing need for more accurate numerical methods for large-scale nonlinear magneto-fluid turbulence calculations. These methods should not only increase the current state of the art in terms of accuracy, but should also continue to optimize other desired properties such as simplicity, minimized computation, minimized memory requirements, and robust stability. This includes the ability to stably solve stiff problems with long time-steps. This work discusses a general methodology for deriving higher-order numerical methods. It also discusses how the selection of various choices can affect the desired properties. The explicit discussion focuses on third-order Runge-Kutta methods, including general solutions and five examples. The study investigates the linear numerical analysis of these methods, including their accuracy, general stability, and stiff stability. Additional appendices discuss linear multistep methods, discuss directions for further work, and exhibit numerical analysis results for some other commonly used lower-order methods.

  4. Stepped mirrored structures for generating true time delays in stationary optical delay line proof-of-principle experiments for application to optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Jansz, Paul Vernon; Wild, Graham; Hinckley, Steven

    2008-01-01

    Conventional time domain Optical Coherence Tomography (OCT) relies on the detection of an interference pattern generated by the interference of backscattered light from the sample and a reference Optical Delay Line (ODL). By referencing the sample interference with the scan depth of the ODL, constructive interference indicates depth in the sample of a reflecting structure. Conventional ODLs used in time domain OCT require some physical movement of a mirror to scan a given depth range. This movement results in instrument degradation. Also in some situations it is necessary to have no moving parts. Stationary ODLs (SODLs) include dual Reflective Spatial Light Modulator (SLM) systems (Type I) and single Transmissive SLM with match-arrayed-waveguide systems (Type II). In this paper, the method of fabrication and characterisation of a number of Stepped Mirrored Structures (SMS) is presented. These structures are intended for later use in proof-of-principle experiments that demonstrate Type II SODL: a six step, 2 mm step depth macro-SMS, an eight step 150 um deep micro-SMS with glue between steps, and a six step 150 um deep micro-SMS with no glue between steps. These SMS are characterized in terms of their fabrication, step alignment and step height increment precision. The degree of alignment of each step was verified using half of a bulk Michelson interferometer. Step height was gauged using a pair of vernier callipers measuring each individual step. A change in notch frequency using an in-fibre Mach-Zhender interferometer was used to gauge the average step height and the result compared to the vernier calliper results. The best aligned SMS was the micro-SMS prepared by method B with no glue between steps. It demonstrated a 95% confidence interval variation of 1% in reflected intensity, with the least variation in intensity within steps. This SMS also had the least absolute variation in step height increment: less than 8 um. Though less variation would be ideal, for

  5. Volume and enthalpy changes in the early steps of bacteriorhodopsin photocycle studied by time-resolved photoacoustics.

    PubMed Central

    Zhang, D; Mauzerall, D

    1996-01-01

    We have studied the photoinduced volume changes, energetics, and kinetics in the early steps of the bacteriorhodopsin (BR) photocycle with pulsed, time-resolved photoacoustics. Our data show that there are two volume changes. The fast volume change ( < or = 200 ns) is an expansion (2.5 +/- 0.3 A3/molecule) and is observed exclusively in the purple membrane (PM), vanishing in the 3-[(3-cholamidopropyl)-dimethylammonio] -1-propane-sulfonate-sulfonate-solubilized BR sample; the slow change (approximately 1 micros) is a volume contraction (-3.7 +/- 0.3 A3/molecule). The fast expansion is assigned to the restructuring of the aggregated BR in the PM, and the 1-micros contraction to the change in hydrogen bonding of water at Asp 212 (Kandori et al. 1995. J. Am. Chem. Soc. 117:2118-2119). The formation of the K intermediate releases most of the absorbed energy as heat, with delta Hk = -36 +/- 8 kJ/mol. The activation energy of the K --> L step is 49 +/- 6 kJ/mol, but the enthalpy change is small, -4 +/- 10 kJ/mol. On the time scale we studied, the primary photochemical kinetics, enthalpy, and volume changes are not affected by substituting the solvent D2O for H2O. Comparing data on monomeric and aggregated BR, we conclude that the functional unit for the photocycle is the BR monomer, because both the kinetics (rate constant and activation energy) and the enthalpy changes are independent of its aggregation state. PMID:8804620

  6. Development of a One-Step Immunocapture Real-Time RT-PCR Assay for Detection of Tobacco Mosaic Virus in Soil

    PubMed Central

    Yang, Jin-Guang; Wang, Feng-Long; Chen, De-Xin; Shen, Li-Li; Qian, Yu-Mei; Liang, Zhi-Yong; Zhou, Wen-Chang; Yan, Tai-He

    2012-01-01

    Tobacco mosaic virus (TMV) causes significant losses in many economically important crops. Contaminated soils may play roles as reservoirs and sources of transmission for TMV. In this study we report the development of an immunocapture real-time RT-PCR (IC-real-time RT-PCR) assay for direct detection of TMV in soils without RNA isolation. A series of TMV infected leaf sap dilutions of 1:101, 1:102, 1:103, 1:104, 1:105 and 1:106 (w/v, g/mL) were added to one gram of soil. The reactivity of DAS-ELISA and conventional RT-PCR was in the range of 1:102 and 1:103 dilution in TMV-infested soils, respectively. Meanwhile, the detection limit of IC-real-time RT-PCR sensitivity was up to 1:106 dilution. However, in plant sap infected by TMV, both IC-real-time RT-PCR and real-time RT-PCR were up to 1:106 dilution, DAS-ELISA could detect at least 1:103 dilution. IC-real-time RT-PCR method can use either plant sample extracts or cultivated soils, and show higher sensitivity than RT-PCR and DAS-ELISA for detection of TMV in soils. Therefore, the proposed IC-real-time RT-PCR assay provides an alternative for quick and very sensitive detection of TMV in soils, with the advantage of not requiring a concentration or RNA purification steps while still allowing detection of TMV for disease control. PMID:23211755

  7. Using a two-step matrix solution to reduce the run time in KULL's magnetic diffusion package

    SciTech Connect

    Brunner, T A; Kolev, T V

    2010-12-17

    Recently a Resistive Magnetohydrodynamics (MHD) package has been added to the KULL code. In order to be compatible with the underlying hydrodynamics algorithm, a new sub-zonal magnetics discretization was developed that supports arbitrary polygonal and polyhedral zones. This flexibility comes at the cost of many more unknowns per zone - approximately ten times more for a hexahedral mesh. We can eliminate some (or all, depending on the dimensionality) of the extra unknowns from the global matrix during assembly by using a Schur complement approach. This trades expensive global work for cache-friendly local work, while still allowing solution for the full system. Significant improvements in the solution time are observed for several test problems.

  8. Timing paradox of stepping and falls in ageing: not so quick and quick(er) on the trigger.

    PubMed

    Rogers, Mark W; Mille, Marie-Laure

    2016-08-15

    Physiological and degenerative changes affecting human standing balance are major contributors to falls with ageing. During imbalance, stepping is a powerful protective action for preserving balance that may be voluntarily initiated in recognition of a balance threat, or be induced by an externally imposed mechanical or sensory perturbation. Paradoxically, with ageing and falls, initiation slowing of voluntary stepping is observed together with perturbation-induced steps that are triggered as fast as or faster than for younger adults. While age-associated changes in sensorimotor conduction, central neuronal processing and cognitive functions are linked to delayed voluntary stepping, alterations in the coupling of posture and locomotion may also prolong step triggering. It is less clear, however, how these factors may explain the accelerated triggering of induced stepping. We present a conceptual model that addresses this issue. For voluntary stepping, a disruption in the normal coupling between posture and locomotion may underlie step-triggering delays through suppression of the locomotion network based on an estimation of the evolving mechanical state conditions for stability. During induced stepping, accelerated step initiation may represent an event-triggering process whereby stepping is released according to the occurrence of a perturbation rather than to the specific sensorimotor information reflecting the evolving instability. In this case, errors in the parametric control of induced stepping and its effectiveness in stabilizing balance would be likely to occur. We further suggest that there is a residual adaptive capacity with ageing that could be exploited to improve paradoxical triggering and other changes in protective stepping to impact fall risk. PMID:26915664

  9. Two-Step Self-Assembly of Liposome-Multidomain Peptide Nanofiber Hydrogel for Time-Controlled Release

    PubMed Central

    2015-01-01

    Progress in self-assembly and supramolecular chemistry has been directed toward obtaining macromolecular assemblies with higher degrees of complexity, simulating the highly structured environment in natural systems. One approach to this type of complexity are multistep, multicomponent, self-assembling systems that allow approaches comparable to traditional multistep synthetic organic chemistry; however, only a few examples of this approach have appeared in the literature. Our previous work demonstrated nanofibrous mimics of the extracellular matrix. Here we demonstrate the ability to create a unique hydrogel, developed by stepwise self-assembly of multidomain peptide fibers and liposomes. The two-component system allows for controlled release of bioactive factors at multiple time points. The individual components of the self-assembled gel and the composite hydrogel were characterized by TEM, SEM, and rheometry, demonstrating that peptide nanofibers and lipid vesicles both retain their structural integrity in the composite gel. The rheological robustness of the hydrogel is shown to be largely unaffected by the presence of liposomes. Release studies from the composite gels loaded with different growth factors EGF, MCP-1, and PlGF-1 showed delay and prolongation of release by liposomes entrapped in the hydrogel compared to more rapid release from the hydrogel alone. This bimodal release system may have utility in systems where timed cascades of biological signals may be valuable, such as in tissue regeneration. PMID:25308335

  10. Analysis of the Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrum of Staphylococcus aureus Identifies Mutations That Allow Differentiation of the Main Clonal Lineages

    PubMed Central

    Josten, Michaele; Reif, Marion; Szekat, Christiane; Al-Sabti, Nahed; Roemer, Terry; Sparbier, Katrin; Kostrzewa, Markus; Rohde, Holger; Sahl, Hans-Georg

    2013-01-01

    Nosocomial infections involving epidemic methicillin-resistant Staphylococcus aureus (MRSA) strains are a serious problem in many countries. In order to analyze outbreaks, the infectious isolates have to be typed; however, most molecular methods are expensive or labor-intensive. Here, we evaluated matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) of cell extracts for the molecular characterization of S. aureus strains. The peak patterns of 401 MRSA and methicillin-susceptible S. aureus (MSSA) strains, including clinical and laboratory strains, were analyzed. Database searches indicated the peptides that were represented by the corresponding peaks in the spectra. The identities of the peptides were confirmed by the sequencing of mutants, the expression of antisense RNA fragments that resulted in the knockdown of the peptide of interest and the concomitant loss of the signal, or tandem MALDI-TOF MS (MALDI-TOF/TOF MS). It was shown that the signals derive mainly from stress proteins and ribosomal proteins. Peak shifts that differentiate the main S. aureus clonal complexes CC5, CC22, CC8, CC45, CC30, and CC1 correlate to point mutations in the respective genes. Retrospective typing of an MRSA outbreak showed that it is possible to differentiate unrelated MSSA, MRSA, and borderline resistant S. aureus (BORSA) strains isolated from health care workers. In conclusion, this method allows for the detection of the epidemic lineages of S. aureus during species identification by MALDI-TOF MS analysis. PMID:23554199

  11. Gadolinium-loaded liposomes allow for real-time magnetic resonance imaging of convection-enhanced delivery in the primate brain.

    PubMed

    Saito, Ryuta; Krauze, Michal T; Bringas, John R; Noble, Charles; McKnight, Tracy R; Jackson, Pamela; Wendland, Michael F; Mamot, Christoph; Drummond, Daryl C; Kirpotin, Dimitri B; Hong, Keelung; Berger, Mitchel S; Park, John W; Bankiewicz, Krystof S

    2005-12-01

    Drug delivery to brain tumors has long posed a major challenge. Convection-enhanced delivery (CED) has been developed as a drug delivery strategy to overcome this difficulty. Ideally, direct visualization of the tissue distribution of drugs infused by CED would assure successful delivery of therapeutic agents to the brain tumor while minimizing exposure of the normal brain. We previously developed a magnetic resonance imaging (MRI)-based method to visualize the distribution of liposomal agents after CED in rodent brains. In the present study, CED of liposomes was further examined in the non-human primate brain (n = 6). Liposomes containing Gadoteridol, DiI-DS, and rhodamine were infused in corona radiata, putamen nucleus, and brain stem. Volume of distribution was analyzed for all delivery locations by histology and MR imaging. Real-time MRI monitoring of liposomes containing gadolinium allowed direct visualization of a robust distribution. MRI of liposomal gadolinium was highly accurate at determining tissue distribution, as confirmed by comparison with histological results from concomitant administration of fluorescent liposomes. Linear correlation for liposomal infusions between infusion volume and distribution volume was established in all targeted locations. We conclude that an integrated strategy combining liposome/nanoparticle technology, CED, and MRI may provide new opportunities for the treatment of brain tumors. Our ability to directly monitor and to control local delivery of liposomal drugs will most likely result in greater clinical efficacy when using CED in management of patients. PMID:16197944

  12. Multiple Model Adaptive Two-Step Filter and Motion Tracking Sliding-Mode Guidance for Missiles with Time Lag in Acceleration

    NASA Astrophysics Data System (ADS)

    Zhou, Di; Zhang, Yong-An; Duan, Guang-Ren

    The two-step filter has been combined with a modified Sage-Husa time-varying measurement noise statistical estimator, which is able to estimate the covariance of measurement noise on line, to generate an adaptive two-step filter. In many practical applications such as the bearings-only guidance, some model parameters and the process noise covariance are also unknown a priori. Based on the adaptive two-step filter, we utilize multiple models in the first-step filtering as well as in the time update of the second-step filtering to handle the uncertainties of model parameters and process noise covariance. In each timestep of the multiple model filtering, probabilistic weights punishing the estimates of first-step state from different models, and their associated covariance matrices are acquired according to Bayes’ rule. The weighted sum of the estimates of first-step state and that of the associated covariance matrices are extracted as the ultimate estimate and covariance of the first-step state, and are used as measurement information for the measurement update of the second-step state. Thus there is still only one iteration process and no apparent enhancement of computation burden. A motion tracking sliding-mode guidance law is presented for missiles with non-negligible delays in actual acceleration. This guidance law guarantees guidance accuracy and is able to enhance observability in bearings-only tracking. In bearings-only cases, the multiple model adaptive two-step filter is applied to the motion tracking sliding-mode guidance law, supplying relative range, relative velocity, and target acceleration information. In simulation experiments satisfactory filtering and guidance results are obtained, even if the filter runs into unknown target maneuvers and unknown time-varying measurement noise covariance, and the guidance law has to deal with a large time lag in acceleration.

  13. Parsimonious rainfall-runoff model construction supported by time series processing and validation of hydrological extremes - Part 1: Step-wise model-structure identification and calibration approach

    NASA Astrophysics Data System (ADS)

    Willems, Patrick

    2014-03-01

    Common problems faced by rainfall-runoff modellers are data limitation, model overparameterization and related problems of parameter identifiability. Depending on the application, possible solutions to overcome these problems include the use of parsimonious conceptual models, avoid the use of a fixed pre-defined model conceptualization, but apply a “top-down” or “downward” method to allow the model structure to be adjusted or inferred from available data and field evidence. This paper presents a top-down procedure that starts from a generalized model structure framework that is adjusted in a case-specific parsimonious way. The model-structure building is done in a transparent, step-wise way, where separate parts of the model structure are identified and calibrated based on multiple and non-commensurable information derived from river flow series by means of a number of sequential time series processing tasks. These include separation of the high frequency (e.g., hourly, daily) river flow series into subflows, split of the series in approx. independent quick and slow flow hydrograph periods, and the extraction of independent peak and low flows. The model building and calibration account for the statistical assumptions and requirements on independency and homoscedasticity of the model residuals. Next to identification of the subflow recessions and related routing submodels, equations describing quick and slow runoff sub-responses and soil water storage are derived from the time series data. The method includes testing of the model performance for peak and low flow extremes.

  14. Capacity planning for electronic waste management facilities under uncertainty: multi-objective multi-time-step model development.

    PubMed

    Poonam Khanijo Ahluwalia; Nema, Arvind K

    2011-07-01

    Selection of optimum locations for locating new facilities and decision regarding capacities at the proposed facilities is a major concern for municipal authorities/managers. The decision as to whether a single facility is preferred over multiple facilities of smaller capacities would vary with varying priorities to cost and associated risks such as environmental or health risk or risk perceived by the society. Currently management of waste streams such as that of computer waste is being done using rudimentary practices and is flourishing as an unorganized sector, mainly as backyard workshops in many cities of developing nations such as India. Uncertainty in the quantification of computer waste generation is another major concern due to the informal setup of present computer waste management scenario. Hence, there is a need to simultaneously address uncertainty in waste generation quantities while analyzing the tradeoffs between cost and associated risks. The present study aimed to address the above-mentioned issues in a multi-time-step, multi-objective decision-support model, which can address multiple objectives of cost, environmental risk, socially perceived risk and health risk, while selecting the optimum configuration of existing and proposed facilities (location and capacities). PMID:20935026

  15. Step by Step

    ERIC Educational Resources Information Center

    Ruder, Robert

    2008-01-01

    Sometimes a principal just has to get out of the office. A walk around the building might provide an escape from the pace of a hectic day, a chance to clear the head and perhaps allow a new perspective on a seemingly monumental school-related challenge to emerge. Wherever the principal walks, he or she is able to identify things that need…

  16. STEP: A Futurevision, Today

    NASA Technical Reports Server (NTRS)

    1994-01-01

    STEP (STandard for the Exchange of Product Model Data) is an innovative software tool that allows the exchange of data between different programming systems to occur and helps speed up the designing in various process industries. This exchange occurs easily between those companies that have STEP, and many industries and government agencies are requiring that their vendors utilize STEP in their computer aided design projects, such as in the areas of mechanical, aeronautical, and electrical engineering. STEP allows the process of concurrent engineering to occur and increases the quality of the design product. One example of the STEP program is the Boeing 777, the first paperless airplane.

  17. Photo-activated ionic gelation of alginate hydrogel: real-time rheological monitoring of the two-step crosslinking mechanism.

    PubMed

    Higham, Alina K; Bonino, Christopher A; Raghavan, Srinivasa R; Khan, Saad A

    2014-07-21

    We examine the gelation of alginate undergoing ionic crosslinking upon ultraviolet (UV) irradiation using in situ dynamic rheology. Hydrogels are formed by combining alginate with calcium carbonate (CaCO3) particles and a photoacid generator (PAG). The PAG is photolyzed upon UV irradiation, resulting in the release of free calcium ions for ionic crosslinking. The viscous and elastic moduli during gelation are monitored as a function of the UV irradiation intensity, exposure time, alginate concentration, and the ratio between alginate and calcium carbonate. Gel time decreases as irradiation intensity increases because a larger concentration of PAG is photolyzed. Interestingly, dark curing, the continuing growth of microstructure in the absence of UV light, is observed. In some instances, the sample transitions from a solution to a gel during the dark curing phase. Additionally, when exposed to constant UV irradiation after the dark curing phase, samples reach the same plateau modulus as samples exposed to constant UV without dark curing, implying that dark curing does not affect the gelation mechanism. We believe the presence of dark curing is the result of the acidic environment persisting within the sample, allowing CaCO3 to dissociate, thereby releasing free Ca(2+) ions capable of binding with the available appropriate ionic blocks of the polymer chains. The growth of microstructure is then detected if the activation barrier has been crossed to release sufficient calcium ions. In this regard, we calculate a value of 30 J that represents the activation energy required to initiate gelation. PMID:24894636

  18. Stepping motor controller

    DOEpatents

    Bourret, S.C.; Swansen, J.E.

    1982-07-02

    A stepping motor is microprocessor controlled by digital circuitry which monitors the output of a shaft encoder adjustably secured to the stepping motor and generates a subsequent stepping pulse only after the preceding step has occurred and a fixed delay has expired. The fixed delay is variable on a real-time basis to provide for smooth and controlled deceleration.

  19. Stepping motor controller

    DOEpatents

    Bourret, Steven C.; Swansen, James E.

    1984-01-01

    A stepping motor is microprocessingly controlled by digital circuitry which monitors the output of a shaft encoder adjustably secured to the stepping motor and generates a subsequent stepping pulse only after the preceding step has occurred and a fixed delay has expired. The fixed delay is variable on a real-time basis to provide for smooth and controlled deceleration.

  20. Reproducibility and validity of the myotest for measuring step frequency and ground contact time in recreational runners.

    PubMed

    Gouttebarge, Vincent; Wolfard, Robin; Griek, Nouschka; de Ruiter, Cornelis J; Boschman, Julitta S; van Dieën, Jaap H

    2015-03-29

    The purpose of this study was to assess the reproducibility (test-retest reliability and agreement) and concurrent validity of the Myotest for measuring step frequency (SF) and ground contact time (GCT) in recreational runners. Based on a within-subjects design (test and retest), SF and GCT of 14 participants (11 males, 3 females) were measured at three different running speeds with the Myotest during two test sessions. SF and GCT were also assessed with a foot-mounted accelerometer (Gold Standard, previously validated by comparing to force plate data) during the first test session. Levels of test-retest reliability and concurrent validity were expressed with intraclass correlation coefficients (ICC), agreement with standard errors of measurement (SEM). For SF, test-retest reliability (ICC's > 0.75) and agreement of the Myotest were considered as good at all running speeds. For GCT, test-retest reliability was found to be moderate at a running speed of 14 km/h and poor at speeds of 10 and 12 km/h (ICC < 0.50). Agreement of the Myotest for GCT at all three running speeds was considered not acceptable given the SEM's calculated. Concurrent validity of the Myotest with the foot-mounted accelerometer (Gold Standard) at all three running speeds was found to be good for SF (ICC's > 0.75) and moderate for GCT (0.50 < ICC's < 0.75). The conclusion of our study is that estimates obtained with the Myotest are reproducible and valid for SF but not for GCT. PMID:25964806

  1. Reproducibility and Validity of the Myotest for Measuring Step Frequency and Ground Contact Time in Recreational Runners

    PubMed Central

    Gouttebarge, Vincent; Wolfard, Robin; Griek, Nouschka; de Ruiter, Cornelis J.; Boschman, Julitta S.; van Dieën, Jaap H.

    2015-01-01

    The purpose of this study was to assess the reproducibility (test-retest reliability and agreement) and concurrent validity of the Myotest for measuring step frequency (SF) and ground contact time (GCT) in recreational runners. Based on a within-subjects design (test and retest), SF and GCT of 14 participants (11 males, 3 females) were measured at three different running speeds with the Myotest during two test sessions. SF and GCT were also assessed with a foot-mounted accelerometer (Gold Standard, previously validated by comparing to force plate data) during the first test session. Levels of test-retest reliability and concurrent validity were expressed with intraclass correlation coefficients (ICC), agreement with standard errors of measurement (SEM). For SF, test-retest reliability (ICC’s > 0.75) and agreement of the Myotest were considered as good at all running speeds. For GCT, test-retest reliability was found to be moderate at a running speed of 14 km/h and poor at speeds of 10 and 12 km/h (ICC < 0.50). Agreement of the Myotest for GCT at all three running speeds was considered not acceptable given the SEM’s calculated. Concurrent validity of the Myotest with the foot-mounted accelerometer (Gold Standard) at all three running speeds was found to be good for SF (ICC’s > 0.75) and moderate for GCT (0.50 < ICC’s < 0.75). The conclusion of our study is that estimates obtained with the Myotest are reproducible and valid for SF but not for GCT. PMID:25964806

  2. Using RFID and accelerometer-embedded tracers to measure probabilities of bed load transport, step lengths, and rest times in a mountain stream

    NASA Astrophysics Data System (ADS)

    Olinde, Lindsay; Johnson, Joel P. L.

    2015-09-01

    We present new measurements of bed load tracer transport in a mountain stream over several snowmelt seasons. Cumulative displacements were measured using passive tracers, which consisted of gravel and cobbles embedded with radio frequency identification tags. The timing of bed load motion during 11 transporting events was quantified with active tracers, i.e., accelerometer-embedded cobbles. Probabilities of cobble transport increased with discharge above a threshold, and exhibited slight to moderate hysteresis during snowmelt hydrographs. Dividing cumulative displacements by the number of movements recorded by each active tracer constrained average step lengths. Average step lengths increased with discharge, and distributions of average step lengths and cumulative displacements were thin tailed. Distributions of rest times followed heavy-tailed power law scaling. Rest time scaling varied somewhat with discharge and with the degree to which tracers were incorporated into the streambed. The combination of thin-tailed displacement distributions and heavy-tailed rest time distributions predict superdiffusive dispersion.

  3. Effect of a Vocal Choice Reaction Time Task on the Kinematics of the First Recovery Step after a Sudden Underfoot Perturbation during Gait

    PubMed Central

    Kim, Hogene; Ashton-Miller, James A.

    2012-01-01

    Thirty-two healthy young adults (15 women) were tested for their ability to maintain their comfortable step pattern following an unpredictable underfoot perturbation in the presence and absence of a concurrent vocal choice reaction time task. Custom instrumented shoes were used to randomly deliver an unexpected medial or lateral forefoot perturbation that inverted the mid-foot an average of 10 degrees or everted the midfoot an average of 9 degrees during one stance phase of a gaittrial. Medial and lateral perturbations were randomized between left and right feet in 12 of 30 gait trials. The results of the repeated measures analyses of variance show that, compared to the step parameters of unperturbed gait, the administration of the unexpected underfoot perturbation did not significantly lead to alterations in the step length or width of the first recovery step. In addition, the simultaneous administration of a vocal choice reaction time task with the underfoot perturbation did not significantly affect the kinematics of the first recovery step. We conclude that in young healthy adults an unexpected 9–10 degree underfoot perturbation, with or without a vocal reaction time task, will not affect their recovery step kinematics when walking at a comfortable gait speed. PMID:22795474

  4. Next Step for STEP

    SciTech Connect

    Wood, Claire; Bremner, Brenda

    2013-08-09

    The Siletz Tribal Energy Program (STEP), housed in the Tribe’s Planning Department, will hire a data entry coordinator to collect, enter, analyze and store all the current and future energy efficiency and renewable energy data pertaining to administrative structures the tribe owns and operates and for homes in which tribal members live. The proposed data entry coordinator will conduct an energy options analysis in collaboration with the rest of the Siletz Tribal Energy Program and Planning Department staff. An energy options analysis will result in a thorough understanding of tribal energy resources and consumption, if energy efficiency and conservation measures being implemented are having the desired effect, analysis of tribal energy loads (current and future energy consumption), and evaluation of local and commercial energy supply options. A literature search will also be conducted. In order to educate additional tribal members about renewable energy, we will send four tribal members to be trained to install and maintain solar panels, solar hot water heaters, wind turbines and/or micro-hydro.

  5. Time-stepping techniques to enable the simulation of bursting behavior in a physiologically realistic computational islet.

    PubMed

    Khuvis, Samuel; Gobbert, Matthias K; Peercy, Bradford E

    2015-05-01

    Physiologically realistic simulations of computational islets of beta cells require the long-time solution of several thousands of coupled ordinary differential equations (ODEs), resulting from the combination of several ODEs in each cell and realistic numbers of several hundreds of cells in an islet. For a reliable and accurate solution of complex nonlinear models up to the desired final times on the scale of several bursting periods, an appropriate ODE solver designed for stiff problems is eventually a necessity, since other solvers may not be able to handle the problem or are exceedingly inefficient. But stiff solvers are potentially significantly harder to use, since their algorithms require at least an approximation of the Jacobian matrix. For sophisticated models, systems of several complex ODEs in each cell, it is practically unworkable to differentiate these intricate nonlinear systems analytically and to manually program the resulting Jacobian matrix in computer code. This paper demonstrates that automatic differentiation can be used to obtain code for the Jacobian directly from code for the ODE system, which allows a full accounting for the sophisticated model equations. This technique is also feasible in source-code languages Fortran and C, and the conclusions apply to a wide range of systems of coupled, nonlinear reaction equations. However, when we combine an appropriately supplied Jacobian with slightly modified memory management in the ODE solver, simulations on the realistic scale of one thousand cells in the islet become possible that are several orders of magnitude faster than the original solver in the software Matlab, a language that is particularly user friendly for programming complicated model equations. We use the efficient simulator to analyze electrical bursting and show non-monotonic average burst period between fast and slow cells for increasing coupling strengths. We also find that interestingly, the arrangement of the connected fast

  6. Stepped nozzle

    DOEpatents

    Sutton, G.P.

    1998-07-14

    An insert is described which allows a supersonic nozzle of a rocket propulsion system to operate at two or more different nozzle area ratios. This provides an improved vehicle flight performance or increased payload. The insert has significant advantages over existing devices for increasing nozzle area ratios. The insert is temporarily fastened by a simple retaining mechanism to the aft end of the diverging segment of the nozzle and provides for a multi-step variation of nozzle area ratio. When mounted in place, the insert provides the nozzle with a low nozzle area ratio. During flight, the retaining mechanism is released and the insert ejected thereby providing a high nozzle area ratio in the diverging nozzle segment. 5 figs.

  7. Stepped nozzle

    DOEpatents

    Sutton, George P.

    1998-01-01

    An insert which allows a supersonic nozzle of a rocket propulsion system to operate at two or more different nozzle area ratios. This provides an improved vehicle flight performance or increased payload. The insert has significant advantages over existing devices for increasing nozzle area ratios. The insert is temporarily fastened by a simple retaining mechanism to the aft end of the diverging segment of the nozzle and provides for a multi-step variation of nozzle area ratio. When mounted in place, the insert provides the nozzle with a low nozzle area ratio. During flight, the retaining mechanism is released and the insert ejected thereby providing a high nozzle area ratio in the diverging nozzle segment.

  8. Simplified Two-Time Step Method for Calculating Combustion and Emission Rates of Jet-A and Methane Fuel With and Without Water Injection

    NASA Technical Reports Server (NTRS)

    Molnar, Melissa; Marek, C. John

    2005-01-01

    A simplified kinetic scheme for Jet-A, and methane fuels with water injection was developed to be used in numerical combustion codes, such as the National Combustor Code (NCC) or even simple FORTRAN codes. The two time step method is either an initial time averaged value (step one) or an instantaneous value (step two). The switch is based on the water concentration in moles/cc of 1x10(exp -20). The results presented here results in a correlation that gives the chemical kinetic time as two separate functions. This two time step method is used as opposed to a one step time averaged method previously developed to determine the chemical kinetic time with increased accuracy. The first time averaged step is used at the initial times for smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, initial water to fuel mass ratio, temperature, and pressure. The second instantaneous step, to be used with higher water concentrations, gives the chemical kinetic time as a function of instantaneous fuel and water mole concentration, pressure and temperature (T4). The simple correlations would then be compared to the turbulent mixing times to determine the limiting rates of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. Chemical kinetic time equations for fuel, carbon monoxide and NOx are obtained for Jet-A fuel and methane with and without water injection to water mass loadings of 2/1 water to fuel. A similar correlation was also developed using data from NASA's Chemical Equilibrium Applications (CEA) code to determine the equilibrium concentrations of carbon monoxide and nitrogen oxide as functions of overall equivalence ratio, water to fuel mass ratio, pressure and temperature (T3). The temperature of the gas entering

  9. New Reduced Two-Time Step Method for Calculating Combustion and Emission Rates of Jet-A and Methane Fuel With and Without Water Injection

    NASA Technical Reports Server (NTRS)

    Molnar, Melissa; Marek, C. John

    2004-01-01

    A simplified kinetic scheme for Jet-A, and methane fuels with water injection was developed to be used in numerical combustion codes, such as the National Combustor Code (NCC) or even simple FORTRAN codes that are being developed at Glenn. The two time step method is either an initial time averaged value (step one) or an instantaneous value (step two). The switch is based on the water concentration in moles/cc of 1x10(exp -20). The results presented here results in a correlation that gives the chemical kinetic time as two separate functions. This two step method is used as opposed to a one step time averaged method previously developed to determine the chemical kinetic time with increased accuracy. The first time averaged step is used at the initial times for smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, initial water to fuel mass ratio, temperature, and pressure. The second instantaneous step, to be used with higher water concentrations, gives the chemical kinetic time as a function of instantaneous fuel and water mole concentration, pressure and temperature (T4). The simple correlations would then be compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates were then used to calculate the necessary chemical kinetic times. Chemical kinetic time equations for fuel, carbon monoxide and NOx were obtained for Jet-A fuel and methane with and without water injection to water mass loadings of 2/1 water to fuel. A similar correlation was also developed using data from NASA's Chemical Equilibrium Applications (CEA) code to determine the equilibrium concentrations of carbon monoxide and nitrogen oxide as functions of overall equivalence ratio, water to fuel mass ratio, pressure and temperature (T3

  10. Power Conditioning And Distribution Units For 50V Platforms A Flexible And Modular Concept Allowing To Deal With Time Constraining Programs

    NASA Astrophysics Data System (ADS)

    Lempereur, V.; Liegeois, B.; Deplus, N.

    2011-10-01

    In the frame of its Power Conditioning and Distribution Unit (PCDU) Medium power product family, Thales Alenia space ETCA is currently developing Power Conditioning Unit (PCU) and PCDU products for 50V platforms applications. These developments are performed in very schedule constraining programs. This challenge can be met thanks to the modular PCDU concept allowing to share a common heritage at mechanical & thermal points of view as well as at electrical functions level. First Medium power PCDU application has been developed for Herschel-Planck PCDU and re-used in several other missions (e.g. GlobalStar2 PCDU for which we are producing more than 26 units). Based on this heritage, a development plan based on Electrical Model (EM) (avoiding Electrical Qualification Model - EQM) can be proposed when the mechanical qualification of the concept covers the environment required in new projects. This first heritage level allows reducing development schedule and activities. In addition, development is also optimized thanks to the re-use of functions designed and qualified in Herschel- PlanckPCDU. This coversinternal TM/TC management inside PCDU based on a centralized scheduler and an internal high speed serial bus. Finally, thanks to common architecture of several 50V platforms based on full regulated bus, S3R (Sequential Shunt Switch Regulator) concept and one (or two) Li- Ion battery(ies), a common PCU/PCDU architecture has allowed the development of modules or functions that are used in several applications. These achievements are discussed with particular emphasis on PCDU architecture trade-offs allowing flexibility of proposed technical solutions (w.r.t. mono/bi-battery configurations, SA inner capacitance value, output power needs...). Pro's and con's of sharing concepts and designs between several applications on 50V platforms are also be discussed.

  11. Novel One-Tube-One-Step Real-Time Methodology for Rapid Transcriptomic Biomarker Detection: Signal Amplification by Ternary Initiation Complexes.

    PubMed

    Fujita, Hiroto; Kataoka, Yuka; Tobita, Seiji; Kuwahara, Masayasu; Sugimoto, Naoki

    2016-07-19

    We have developed a novel RNA detection method, termed signal amplification by ternary initiation complexes (SATIC), in which an analyte sample is simply mixed with the relevant reagents and allowed to stand for a short time under isothermal conditions (37 °C). The advantage of the technique is that there is no requirement for (i) heat annealing, (ii) thermal cycling during the reaction, (iii) a reverse transcription step, or (iv) enzymatic or mechanical fragmentation of the target RNA. SATIC involves the formation of a ternary initiation complex between the target RNA, a circular DNA template, and a DNA primer, followed by rolling circle amplification (RCA) to generate multiple copies of G-quadruplex (G4) on a long DNA strand like beads on a string. The G4s can be specifically fluorescence-stained with N(3)-hydroxyethyl thioflavin T (ThT-HE), which emits weakly with single- and double-stranded RNA/DNA but strongly with parallel G4s. An improved dual SATIC system, which involves the formation of two different ternary initiation complexes in the RCA process, exhibited a wide quantitative detection range of 1-5000 pM. Furthermore, this enabled visual observation-based RNA detection, which is more rapid and convenient than conventional isothermal methods, such as reverse transcription-loop-mediated isothermal amplification, signal mediated amplification of RNA technology, and RNA-primed rolling circle amplification. Thus, SATIC methodology may serve as an on-site and real-time measurement technique for transcriptomic biomarkers for various diseases. PMID:27347743

  12. A high-order solver for unsteady incompressible Navier-Stokes equations using the flux reconstruction method on unstructured grids with implicit dual time stepping

    NASA Astrophysics Data System (ADS)

    Cox, Christopher; Liang, Chunlei; Plesniak, Michael W.

    2016-06-01

    We report development of a high-order compact flux reconstruction method for solving unsteady incompressible flow on unstructured grids with implicit dual time stepping. The method falls under the class of methods now referred to as flux reconstruction/correction procedure via reconstruction. The governing equations employ Chorin's classic artificial compressibility formulation with dual time stepping to solve unsteady flow problems. An implicit non-linear lower-upper symmetric Gauss-Seidel scheme with backward Euler discretization is used to efficiently march the solution in pseudo time, while a second-order backward Euler discretization is used to march in physical time. We verify and validate implementation of the high-order method coupled with our implicit time stepping scheme using both steady and unsteady incompressible flow problems. The current implicit time stepping scheme is proven effective in satisfying the divergence-free constraint on the velocity field in the artificial compressibility formulation within the context of the high-order flux reconstruction method. This compact high-order method is very suitable for parallel computing and can easily be extended to moving and deforming grids.

  13. A high-order solver for unsteady incompressible Navier-Stokes equations using the flux reconstruction method on unstructured grids with implicit dual time stepping

    NASA Astrophysics Data System (ADS)

    Cox, Christopher; Liang, Chunlei; Plesniak, Michael

    2015-11-01

    This paper reports development of a high-order compact method for solving unsteady incompressible flow on unstructured grids with implicit time stepping. The method falls under the class of methods now referred to as flux reconstruction/correction procedure via reconstruction. The governing equations employ the classical artificial compressibility treatment, where dual time stepping is needed to solve unsteady flow problems. An implicit non-linear lower-upper symmetric Gauss-Seidel scheme with backward Euler discretization is used to efficiently march the solution in pseudo time, while a second-order backward Euler discretization is used to march in physical time. We verify and validate implementation of the high-order method coupled with our implicit time-stepping scheme. Three-dimensional results computed on many processing elements will be presented. The high-order method is very suitable for parallel computing and can easily be extended to moving and deforming grids. The current implicit time stepping scheme is proven effective in satisfying the divergence-free constraint on the velocity field in the artificial compressibility formulation within the context of the high-order flux reconstruction method. Financial support provided under the GW Presidential Merit Fellowship.

  14. Factors predicting prolonged operative time for individual surgical steps of robot-assisted radical prostatectomy (RARP): A single surgeon’s experience

    PubMed Central

    Alenizi, Abdullah M.; Valdivieso, Roger; Rajih, Emad; Meskawi, Malek; Toarta, Cristian; Bienz, Marc; Azizi, Mounsif; Hueber, Pierre Alain; Lavigueur-Blouin, Hugo; Trudeau, Vincent; Trinh, Quoc-Dien; El-Hakim, Assaad; Zorn, Kevin C.

    2015-01-01

    Introduction: We evaluated the average time required to complete individual steps of robotic-assisted radical prostatectomy (RARP) by an expert RARP surgeon. The intent is to help establish a time-based benchmark to aim for during apprenticeship. In addition, we aimed to evaluate preoperative patient factors, which could prolong the operative time of these individual steps. Methods: We retrospectively identified 247 patients who underwent RARP, performed by an experienced robotic surgeon at our institution. Baseline patient characteristics and the duration of each step were recorded. Multivariate analysis was performed to predict factors of prolonged individual steps. Results: In multivariable analysis, obesity was a significant predictor of prolonged operative time of: docking (odds ratio [OR] 1.96), urethral division (OR 3.13), and vesico-urethral anastomosis (VUA) (OR 2.63). Prostate volume was also a significant predictor of longer operative time in dorsal vein complex ligation (OR 1.02), bladder neck division (OR 1.03), pedicle control (OR 1.04), urethral division (OR 1.02), and VUA (OR 1.03). A prolonged bladder neck division was predicted by the presence of a median lobe (OR 5.03). Only obesity (OR 2.56) and prostate volume (OR 1.04) were predictors of a longer overall operative time. Conclusions: Obesity and prostate volume are powerful predictors of longer overall operative time. Furthermore, both can predict prolonged time of several individual RARP steps. The presence of a median lobe is a strong predictor of a longer bladder neck division. These factors should be taken into consideration during RARP training. PMID:26279709

  15. Using a Three-Step Decoding Strategy with Constant Time Delay to Teach Word Reading to Students with Mild and Moderate Mental Retardation

    ERIC Educational Resources Information Center

    Tucker Cohen, Elisabeth; Heller, Kathryn Wolff; Alberto, Paul; Fredrick, Laura D.

    2008-01-01

    The use of a three-step decoding strategy with constant time delay for teaching decoding and word reading to students with mild and moderate mental retardation was investigated in this study. A multiple probe design was used to examine the percentage of words correctly decoded and read as well as the percentage of sounds correctly decoded. The…

  16. In vivo micro-computed tomography allows direct three-dimensional quantification of both bone formation and bone resorption parameters using time-lapsed imaging.

    PubMed

    Schulte, Friederike A; Lambers, Floor M; Kuhn, Gisela; Müller, Ralph

    2011-03-01

    Bone is a living tissue able to adapt its structure to external influences such as altered mechanical loading. This adaptation process is governed by two distinct cell types: bone-forming cells called osteoblasts and bone-resorbing cells called osteoclasts. It is therefore of particular interest to have quantitative access to the outcomes of bone formation and resorption separately. This article presents a non-invasive three-dimensional technique to directly extract bone formation and resorption parameters from time-lapsed in vivo micro-computed tomography scans. This includes parameters such as Mineralizing Surface (MS), Mineral Apposition Rate (MAR), and Bone Formation Rate (BFR), which were defined in accordance to the current nomenclature of dynamic histomorphometry. Due to the time-lapsed and non-destructive nature of in vivo micro-computed tomography, not only formation but also resorption can now be assessed quantitatively and time-dependent parameters Eroded Surface (ES) as well as newly defined indices Mineral Resorption Rate (MRR) and Bone Resorption Rate (BRR) are introduced. For validation purposes, dynamic formation parameters were compared to the traditional quantitative measures of dynamic histomorphometry, where MAR correlated with R = 0.68 and MS with R = 0.78 (p < 0.05). Reproducibility was assessed in 8 samples that were scanned 5 times and errors ranged from 0.9% (MRR) to 6.6% (BRR). Furthermore, the new parameters were applied to a murine in vivo loading model. A comparison of directly extracted parameters between formation and resorption within each animal revealed that in the control group, i.e., during normal remodeling, MAR was significantly lower than MRR (p < 0.01), whereas MS compared to ES was significantly higher (p < 0.0001). This implies that normal remodeling seems to take place by many small formation packets and few but large resorption volumes. After 4 weeks of mechanical loading, newly extracted trabecular BFR and MS were

  17. A sensitive one-step real-time PCR for detection of avian influenza viruses using a MGB probe and an internal positive control

    PubMed Central

    Di Trani, Livia; Bedini, Barbara; Donatelli, Isabella; Campitelli, Laura; Chiappini, Barbara; De Marco, Maria Alessandra; Delogu, Mauro; Buonavoglia, Canio; Vaccari, Gabriele

    2006-01-01

    Background Avian influenza viruses (AIVs) are endemic in wild birds and their introduction and conversion to highly pathogenic avian influenza virus in domestic poultry is a cause of serious economic losses as well as a risk for potential transmission to humans. The ability to rapidly recognise AIVs in biological specimens is critical for limiting further spread of the disease in poultry. The advent of molecular methods such as real time polymerase chain reaction has allowed improvement of detection methods currently used in laboratories, although not all of these methods include an Internal Positive Control (IPC) to monitor for false negative results. Therefore we developed a one-step reverse transcription real time PCR (RRT-PCR) with a Minor Groove Binder (MGB) probe for the detection of different subtypes of AIVs. This technique also includes an IPC. Methods RRT-PCR was developed using an improved TaqMan technology with a MGB probe to detect AI from reference viruses. Primers and probe were designed based on the matrix gene sequences from most animal and human A influenza virus subtypes. The specificity of RRT-PCR was assessed by detecting influenza A virus isolates belonging to subtypes from H1–H13 isolated in avian, human, swine and equine hosts. The analytical sensitivity of the RRT-PCR assay was determined using serial dilutions of in vitro transcribed matrix gene RNA. The use of a rodent RNA as an IPC in order not to reduce the efficiency of the assay was adopted. Results The RRT-PCR assay is capable to detect all tested influenza A viruses. The detection limit of the assay was shown to be between 5 and 50 RNA copies per reaction and the standard curve demonstrated a linear range from 5 to 5 × 108 copies as well as excellent reproducibility. The analytical sensitivity of the assay is 10–100 times higher than conventional RT-PCR. Conclusion The high sensitivity, rapidity, reproducibility and specificity of the AIV RRT-PCR with the use of IPC to monitor

  18. Conventional and real-time PCRs for detection of Erwinia piriflorinigrans allow its distinction from the fire blight pathogen, Erwinia amylovora.

    PubMed

    Barbé, Silvia; Bertolini, Edson; Roselló, Montserrat; Llop, Pablo; López, María M

    2014-04-01

    Erwinia piriflorinigrans is a new pathogenic species of the bacterial genus Erwinia that has been described recently in Spain. Accurate detection and identification of E. piriflorinigrans are challenging because its symptoms on pear blossoms are similar to those caused by Erwinia amylovora, the causal agent of fire blight. Moreover, these two species share phenotypic and molecular characteristics. Two specific and sensitive conventional and real-time PCR protocols were developed to identify and detect E. piriflorinigrans and to differentiate it from E. amylovora and other species of this genus. These protocols were based on sequences from plasmid pEPIR37, which is present in all strains of E. piriflorinigrans analyzed. After the stability of the plasmid was demonstrated, the specificities of the protocols were confirmed by the amplification of all E. piriflorinigrans strains tested, whereas 304 closely related pathogenic and nonpathogenic Erwinia strains and microbiota from pear trees were not amplified. In sensitivity assays, 10(3) cells/ml extract were detected in spiked plant material by conventional or real-time PCR, and 10(2) cells/ml were detected in DNA extracted from spiked plant material by real-time PCR. The protocols developed here succeeded in detecting E. piriflorinigrans in 102 out of 564 symptomatic and asymptomatic naturally infected pear samples (flowers, cortex stem tissue, leaves, shoots, and fruitlets), in necrotic Pyracantha sp. blossoms, and in necrotic pear and apple tissues infected with both E. amylovora and E. piriflorinigrans. Therefore, these new tools can be used in epidemiological studies that will enhance our understanding of the life cycle of E. piriflorinigrans in different hosts and plant tissues and its interaction with E. amylovora. PMID:24509928

  19. Conventional and Real-Time PCRs for Detection of Erwinia piriflorinigrans Allow Its Distinction from the Fire Blight Pathogen, Erwinia amylovora

    PubMed Central

    Barbé, Silvia; Bertolini, Edson; Roselló, Montserrat; Llop, Pablo

    2014-01-01

    Erwinia piriflorinigrans is a new pathogenic species of the bacterial genus Erwinia that has been described recently in Spain. Accurate detection and identification of E. piriflorinigrans are challenging because its symptoms on pear blossoms are similar to those caused by Erwinia amylovora, the causal agent of fire blight. Moreover, these two species share phenotypic and molecular characteristics. Two specific and sensitive conventional and real-time PCR protocols were developed to identify and detect E. piriflorinigrans and to differentiate it from E. amylovora and other species of this genus. These protocols were based on sequences from plasmid pEPIR37, which is present in all strains of E. piriflorinigrans analyzed. After the stability of the plasmid was demonstrated, the specificities of the protocols were confirmed by the amplification of all E. piriflorinigrans strains tested, whereas 304 closely related pathogenic and nonpathogenic Erwinia strains and microbiota from pear trees were not amplified. In sensitivity assays, 103 cells/ml extract were detected in spiked plant material by conventional or real-time PCR, and 102 cells/ml were detected in DNA extracted from spiked plant material by real-time PCR. The protocols developed here succeeded in detecting E. piriflorinigrans in 102 out of 564 symptomatic and asymptomatic naturally infected pear samples (flowers, cortex stem tissue, leaves, shoots, and fruitlets), in necrotic Pyracantha sp. blossoms, and in necrotic pear and apple tissues infected with both E. amylovora and E. piriflorinigrans. Therefore, these new tools can be used in epidemiological studies that will enhance our understanding of the life cycle of E. piriflorinigrans in different hosts and plant tissues and its interaction with E. amylovora. PMID:24509928

  20. Simplified Two-Time Step Method for Calculating Combustion Rates and Nitrogen Oxide Emissions for Hydrogen/Air and Hydorgen/Oxygen

    NASA Technical Reports Server (NTRS)

    Molnar, Melissa; Marek, C. John

    2005-01-01

    A simplified single rate expression for hydrogen combustion and nitrogen oxide production was developed. Detailed kinetics are predicted for the chemical kinetic times using the complete chemical mechanism over the entire operating space. These times are then correlated to the reactor conditions using an exponential fit. Simple first order reaction expressions are then used to find the conversion in the reactor. The method uses a two-time step kinetic scheme. The first time averaged step is used at the initial times with smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, temperature, and pressure. The second instantaneous step is used at higher water concentrations (> 1 x 10(exp -20) moles/cc) in the mixture which gives the chemical kinetic time as a function of the instantaneous fuel and water mole concentrations, pressure and temperature (T4). The simple correlations are then compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. This time is regressed over the complete initial conditions using the Excel regression routine. Chemical kinetic time equations for H2 and NOx are obtained for H2/air fuel and for the H2/O2. A similar correlation is also developed using data from NASA s Chemical Equilibrium Applications (CEA) code to determine the equilibrium temperature (T4) as a function of overall fuel/air ratio, pressure and initial temperature (T3). High values of the regression coefficient R2 are obtained.

  1. Summary of Simplified Two Time Step Method for Calculating Combustion Rates and Nitrogen Oxide Emissions for Hydrogen/Air and Hydrogen/Oxygen

    NASA Technical Reports Server (NTRS)

    Marek, C. John; Molnar, Melissa

    2005-01-01

    A simplified single rate expression for hydrogen combustion and nitrogen oxide production was developed. Detailed kinetics are predicted for the chemical kinetic times using the complete chemical mechanism over the entire operating space. These times are then correlated to the reactor conditions using an exponential fit. Simple first order reaction expressions are then used to find the conversion in the reactor. The method uses a two time step kinetic scheme. The first time averaged step is used at the initial times with smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, temperature, and pressure. The second instantaneous step is used at higher water concentrations (greater than l x 10(exp -20)) moles per cc) in the mixture which gives the chemical kinetic time as a function of the instantaneous fuel and water mole concentrations, pressure and temperature (T(sub 4)). The simple correlations are then compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. This time is regressed over the complete initial conditions using the Excel regression routine. Chemical kinetic time equations for H2 and NOx are obtained for H2/Air fuel and for H2/O2. A similar correlation is also developed using data from NASA's Chemical Equilibrium Applications (CEA) code to determine the equilibrium temperature (T(sub 4)) as a function of overall fuel/air ratio, pressure and initial temperature (T(sub 3)). High values of the regression coefficient R squared are obtained.

  2. Investigating cryoinjury using simulations and experiments. 1: TF-1 cells during two-step freezing (rapid cooling interrupted with a hold time).

    PubMed

    Ross-Rodriguez, L U; Elliott, J A W; McGann, L E

    2010-08-01

    There is significant interest in designing a cryopreservation protocol for hematopoietic stem cells (HSC) which does not rely on dimethyl sulfoxide (Me(2)SO) as a cryoprotectant. Computer simulations that describe cellular osmotic responses during cooling and warming can be used to optimize the viability of cryopreserved HSC; however, a better understanding of cellular osmotic parameters is required for these simulations. As a model for HSC, the erythroleukemic human cell line TF-1 was used in this study. Simulations, based on the osmotic properties of TF-1 cells and on the solution properties of the intra- and extracellular compartments, were used to interpret cryoinjury associated with a two-step cryopreservation protocol. Calculated intracellular supercooling was used as an indicator of cryoinjury related to intracellular ice formation. Simulations were applied to the two-step cooling protocol (rapid cooling interrupted with a hold time) for TF-1 cells in the absence of Me(2)SO or other cryoprotectants and optimized by minimizing the indicator of cryoinjury. A comparison of simulations and experimental measurements of membrane integrity supports the concept that, for two-step cooling, increasing intracellular supercooling is the primary contributor to potential freezing injury due to the increase in the likelihood of intracellular ice formation. By calculating intracellular supercooling for each step separately and comparing these calculations with cell recovery data, it was demonstrated that it is not optimal simply to limit overall supercooling during two-step freezing procedures. More aptly, appropriate limitations of supercooling differ from the first step to the second step. This study also demonstrates why high cell recovery after cryopreservation could be achieved in the absence of traditional cryoprotectants. PMID:20471379

  3. THE INFLUENCE OF MODEL TIME STEP ON THE RELATIVE SENSITIVITY OF POPULATION GROWTH TO SURVIVAL, GROWTH AND REPRODUCTION

    EPA Science Inventory

    Matrix population models are often used to extrapolate from life stage-specific stressor effects on survival and reproduction to population-level effects. Demographic elasticity analysis of a matrix model allows an evaluation of the relative sensitivity of population growth rate ...

  4. Unconditionally energy stable time stepping scheme for Cahn-Morral equation: Application to multi-component spinodal decomposition and optimal space tiling

    NASA Astrophysics Data System (ADS)

    Tavakoli, Rouhollah

    2016-01-01

    An unconditionally energy stable time stepping scheme is introduced to solve Cahn-Morral-like equations in the present study. It is constructed based on the combination of David Eyre's time stepping scheme and Schur complement approach. Although the presented method is general and independent of the choice of homogeneous free energy density function term, logarithmic and polynomial energy functions are specifically considered in this paper. The method is applied to study the spinodal decomposition in multi-component systems and optimal space tiling problems. A penalization strategy is developed, in the case of later problem, to avoid trivial solutions. Extensive numerical experiments demonstrate the success and performance of the presented method. According to the numerical results, the method is convergent and energy stable, independent of the choice of time stepsize. Its MATLAB implementation is included in the appendix for the numerical evaluation of algorithm and reproduction of the presented results.

  5. Accurate molecular dynamics and nuclear quantum effects at low cost by multiple steps in real and imaginary time: Using density functional theory to accelerate wavefunction methods

    NASA Astrophysics Data System (ADS)

    Kapil, V.; VandeVondele, J.; Ceriotti, M.

    2016-02-01

    The development and implementation of increasingly accurate methods for electronic structure calculations mean that, for many atomistic simulation problems, treating light nuclei as classical particles is now one of the most serious approximations. Even though recent developments have significantly reduced the overhead for modeling the quantum nature of the nuclei, the cost is still prohibitive when combined with advanced electronic structure methods. Here we present how multiple time step integrators can be combined with ring-polymer contraction techniques (effectively, multiple time stepping in imaginary time) to reduce virtually to zero the overhead of modelling nuclear quantum effects, while describing inter-atomic forces at high levels of electronic structure theory. This is demonstrated for a combination of MP2 and semi-local DFT applied to the Zundel cation. The approach can be seamlessly combined with other methods to reduce the computational cost of path integral calculations, such as high-order factorizations of the Boltzmann operator or generalized Langevin equation thermostats.

  6. The effect of large-scale model time step and multiscale coupling frequency on cloud climatology, vertical structure, and rainfall extremes in a superparameterized GCM

    NASA Astrophysics Data System (ADS)

    Yu, Sungduk; Pritchard, Michael S.

    2015-12-01

    The effect of global climate model (GCM) time step—which also controls how frequently global and embedded cloud resolving scales are coupled—is examined in the Superparameterized Community Atmosphere Model ver 3.0. Systematic bias reductions of time-mean shortwave cloud forcing (˜10 W/m2) and longwave cloud forcing (˜5 W/m2) occur as scale coupling frequency increases, but with systematically increasing rainfall variance and extremes throughout the tropics. An overarching change in the vertical structure of deep tropical convection, favoring more bottom-heavy deep convection as a global model time step is reduced may help orchestrate these responses. The weak temperature gradient approximation is more faithfully satisfied when a high scale coupling frequency (a short global model time step) is used. These findings are distinct from the global model time step sensitivities of conventionally parameterized GCMs and have implications for understanding emergent behaviors of multiscale deep convective organization in superparameterized GCMs. The results may also be useful for helping to tune them.

  7. The effect of large-scale model time step and multiscale coupling frequency on cloud climatology, vertical structure, and rainfall extremes in a superparameterized GCM

    DOE PAGESBeta

    Yu, Sungduk; Pritchard, Michael S.

    2015-12-17

    The effect of global climate model (GCM) time step—which also controls how frequently global and embedded cloud resolving scales are coupled—is examined in the Superparameterized Community Atmosphere Model ver 3.0. Systematic bias reductions of time-mean shortwave cloud forcing (~10 W/m2) and longwave cloud forcing (~5 W/m2) occur as scale coupling frequency increases, but with systematically increasing rainfall variance and extremes throughout the tropics. An overarching change in the vertical structure of deep tropical convection, favoring more bottom-heavy deep convection as a global model time step is reduced may help orchestrate these responses. The weak temperature gradient approximation is more faithfullymore » satisfied when a high scale coupling frequency (a short global model time step) is used. These findings are distinct from the global model time step sensitivities of conventionally parameterized GCMs and have implications for understanding emergent behaviors of multiscale deep convective organization in superparameterized GCMs. Lastly, the results may also be useful for helping to tune them.« less

  8. The effect of large-scale model time step and multiscale coupling frequency on cloud climatology, vertical structure, and rainfall extremes in a superparameterized GCM

    SciTech Connect

    Yu, Sungduk; Pritchard, Michael S.

    2015-12-17

    The effect of global climate model (GCM) time step—which also controls how frequently global and embedded cloud resolving scales are coupled—is examined in the Superparameterized Community Atmosphere Model ver 3.0. Systematic bias reductions of time-mean shortwave cloud forcing (~10 W/m2) and longwave cloud forcing (~5 W/m2) occur as scale coupling frequency increases, but with systematically increasing rainfall variance and extremes throughout the tropics. An overarching change in the vertical structure of deep tropical convection, favoring more bottom-heavy deep convection as a global model time step is reduced may help orchestrate these responses. The weak temperature gradient approximation is more faithfully satisfied when a high scale coupling frequency (a short global model time step) is used. These findings are distinct from the global model time step sensitivities of conventionally parameterized GCMs and have implications for understanding emergent behaviors of multiscale deep convective organization in superparameterized GCMs. Lastly, the results may also be useful for helping to tune them.

  9. A Compact Tandem Two-Step Laser Time-of-Flight Mass Spectrometer for In Situ Analysis of Non-Volatile Organics on Planetary Surfaces

    NASA Technical Reports Server (NTRS)

    Getty, Stephanie A.; Brinckerhoff, William B.; Li, Xiang; Elsila, Jamie; Cornish, Timothy; Ecelberger, Scott; Wu, Qinghao; Zare, Richard

    2014-01-01

    Two-step laser desorption mass spectrometry is a well suited technique to the analysis of high priority classes of organics, such as polycyclic aromatic hydrocarbons, present in complex samples. The use of decoupled desorption and ionization laser pulses allows for sensitive and selective detection of structurally intact organic species. We have recently demonstrated the implementation of this advancement in laser mass spectrometry in a compact, flight-compatible instrument that could feasibly be the centerpiece of an analytical science payload as part of a future spaceflight mission to a small body or icy moon.

  10. New sensitive one-step real-time duplex PCR method for group A and B HIV-2 RNA load.

    PubMed

    Avettand-Fenoel, Véronique; Damond, Florence; Gueudin, Marie; Matheron, Sophie; Mélard, Adeline; Collin, Gilles; Descamps, Diane; Chaix, Marie-Laure; Rouzioux, Christine; Plantier, Jean-Christophe

    2014-08-01

    The Agence Nationale de Recherche sur le Sida et les hépatites virales (ANRS) previously developed a widely used method for HIV-1 RNA quantification (Biocentric). Here, we report the development of a new specific and sensitive method for HIV-2 RNA quantification, based on an adaptation of the existing HIV-1 protocol. The new test is based on TaqMan one-step reverse transcription-quantitative PCR (qRT-PCR) targeting two conserved consensus regions of HIV-2 (long terminal repeat [LTR] and gag). Analytic performances were determined in three laboratories. Clinical performances were evaluated on 100 plasma samples from HIV-2-infected patients (groups A, B, and H) by comparison with the assay currently used for the ANRS HIV-2 cohort. The specificity was 100%. Sensitivity was 50 copies/ml (cp/ml) and was optimized to 10 cp/ml. The within-run coefficients of variation in the three laboratories varied from 0.54% to 1.61% at 4 log10 copies/ml and from 7.24% to 14.32% at 2 log10 cp/ml. The between-run coefficients of variation varied from 2.28% to 6.43%. Of the 39 clinical samples below 2 log10 in the current assay, the new test improved the detection or quantification of 17 samples, including eight group B samples. For quantifiable samples, similar loads were obtained with the two assays for group A samples. The median difference between the two assays for group B samples was +0.18 but with greater heterogeneity than for group A. The HIV-2 group H sample had similar results with the two assays. This new assay is highly sensitive and accurately quantifies the most prevalent HIV-2 groups. This test will be useful for monitoring low viral loads in HIV-2-infected patients. PMID:24920771

  11. Rapid Simultaneous Detection of Enterovirus and Parechovirus RNAs in Clinical Samples by One-Step Real-Time Reverse Transcription-PCR Assay ▿

    PubMed Central

    Bennett, Susan; Harvala, Heli; Witteveldt, Jeroen; McWilliam Leitch, E. Carol; McLeish, Nigel; Templeton, Kate; Gunson, Rory; Carman, William F.; Simmonds, Peter

    2011-01-01

    Enteroviruses (EVs) are recognized as the major etiological agent in meningitis in children and young adults. The use of molecular techniques, such as PCR, has substantially improved the sensitivity of enterovirus detection compared to that of virus culture methods. PCR-based methods also can detect a much wider range of EV variants, including those within species A, as well as human parechoviruses (HPeVs) that often grow poorly in vitro and which previously have been underdiagnosed by traditional methods. To exploit these developments, we developed a real-time one-step reverse transcription-PCR (RT-PCR) for the rapid and sensitive detection of EV and HPeV in clinical specimens. Two commercially available RT-PCR kits were used (method I, Platinum one-step kit; method II, Express qPCR one-step kit) with primers and probes targeting the EV and HPeV 5′-untranslated regions (5′UTR). Amplification dynamics (threshold cycle [CT]values and efficiencies) of absolutely quantified full-length RNA transcripts representative of EV species A to D and HPeV were similar, demonstrating the effectiveness of both assays across the range of currently described human EV and HPeV variants. Probit analysis of multiple endpoint replicates demonstrated comparable sensitivities of the assays for EV and HPeV (method I, approximately 10 copies per reaction for both targets; method II, 20 copies per reaction). CT values were highly reproducible on repeat testing of positive controls within assays and between assay runs. Considering the sample turnaround time of less than 3 h, the multiplexed one-step RT-PCR method provides rapid diagnostic testing for EV and HPeV in cases of suspected central nervous system infections in a clinically relevant time frame. PMID:21593263

  12. The StepOne real-time polymerase chain reaction detection of Salmonella sp., Salmonella enterica ser. typhimurium and enteritidis in milk and meat.

    PubMed

    Pochop, Jaroslav; Kačániová, Miroslava; Hleba, Lukáš; Lejková, Jadža; Fikselová, Martina; Kunová, Simona; Kluz, Maciej

    2011-01-01

    The aim of this study was to follow contamination of ready to eat milk and meat products with Salmonella spp. by using the StepOne real-time polymerase chain reaction (PCR). Classical microbiological methods for detection of foodborne bacteria involve the use of pre-enrichment and/or specific enrichment, following isolation of bacteria in solid media and the final confirmation by biochemical and/or serological tests. We used the PrepSEQ Rapid Spin Sample Preparation Kit for isolation of DNA and MicroSEQ® Salmonella spp. Detection Kit for pursuance of the real-time PCR (Applied Biosystems). In samples without incubation we detected strain of Salmonella sp. in 5 out of 25 samples (swabs), as well as in the internal positive control (IPC), which was positive in all samples. This StepOne real-time PCR assay is extremely useful for any laboratory equipped by real-time PCR. It is a fast, reproducible, simple, specific and sensitive way to detect nucleic acids, which could be used in clinical diagnostic tests in the future. Our results indicated that real-time PCR assay developed in this study could sensitively detect Salmonella spp. in ready-to-eat food. This could prevent infection caused by Salmonella, and also could benefit food manufacturing companies by extending their product's shelf-life as well as saving the cost of warehousing their food products while awaiting pathogen testing results. PMID:21879831

  13. Development of a time-stepping sediment budget model for assessing land use impacts in large river basins.

    PubMed

    Wilkinson, S N; Dougall, C; Kinsey-Henderson, A E; Searle, R D; Ellis, R J; Bartley, R

    2014-01-15

    The use of river basin modelling to guide mitigation of non-point source pollution of wetlands, estuaries and coastal waters has become widespread. To assess and simulate the impacts of alternate land use or climate scenarios on river washload requires modelling techniques that represent sediment sources and transport at the time scales of system response. Building on the mean-annual SedNet model, we propose a new D-SedNet model which constructs daily budgets of fine sediment sources, transport and deposition for each link in a river network. Erosion rates (hillslope, gully and streambank erosion) and fine sediment sinks (floodplains and reservoirs) are disaggregated from mean annual rates based on daily rainfall and runoff. The model is evaluated in the Burdekin basin in tropical Australia, where policy targets have been set for reducing sediment and nutrient loads to the Great Barrier Reef (GBR) lagoon from grazing and cropping land. D-SedNet predicted annual loads with similar performance to that of a sediment rating curve calibrated to monitored suspended sediment concentrations. Relative to a 22-year reference load time series at the basin outlet derived from a dynamic general additive model based on monitoring data, D-SedNet had a median absolute error of 68% compared with 112% for the rating curve. RMS error was slightly higher for D-SedNet than for the rating curve due to large relative errors on small loads in several drought years. This accuracy is similar to existing agricultural system models used in arable or humid environments. Predicted river loads were sensitive to ground vegetation cover. We conclude that the river network sediment budget model provides some capacity for predicting load time-series independent of monitoring data in ungauged basins, and for evaluating the impact of land management on river sediment load time-series, which is challenging across large regions in data-poor environments. PMID:23968738

  14. Gas flushing through hyper-acidic crater lakes: the next steps within a reframed monitoring time window

    NASA Astrophysics Data System (ADS)

    Rouwet, Dmitri

    2016-04-01

    Tracking variations in the chemical composition, water temperature and pH of brines from peak-activity crater lakes is the most obvious way to forecast phreatic activity. Volcano monitoring intrinsically implies a time window of observation that should be synchronised with the kinetics of magmatic processes, such as degassing and magma intrusion. To decipher "how much time ago" a variation in degassing regime actually occurred before eventually being detected in a crater lake is key, and depends on the lake water residence time. The above reasoning assumes that gas is preserved as anions in the lake water (SO4, Cl, F anions), in other words, that scrubbing of acid gases is complete and irreversible. Less is true. Recent work has confirmed, by direct MultiGas measurement from evaporative plumes, that even the strongest acid in liquid medium (i.e. SO2) degasses from hyper-acidic crater lakes. The less strong acid HCl has long been recognised as being more volatile than hydrophyle in extremely acidic solutions (pH near 0), through a long-term steady increase in SO4/Cl ratios in the vigorously evaporating crater lake of Poás volcano. We now know that acidic gases flush through hyper-acidic crater lake brines, but we don't know to which extend (completely or partially?), and with which speed. The chemical composition hence only reflects a transient phase of the gas flushing through the lake. In terms of volcanic surveillance this brings the advantage that the monitoring time window is definitely shorter than defined by the water chemistry, but yet, we do not know how much shorter. Empirical experiments by Capaccioni et al. (in press) have tried to tackle this kinetic problem for HCl degassing from a "lab-lake" on the short-term (2 days). With this state of the art in mind, two new monitoring strategies can be proposed to seek for precursory signals of phreatic eruptions from crater lakes: (1) Tracking variations in gas compositions, fluxes and ratios between species in

  15. Global surface mass time variations by using a two-step inversion for cumulating daily satellite gravity information

    NASA Astrophysics Data System (ADS)

    Ramillien, Guillaume; Frappart, Frappart; Seoane, Lucia

    2015-04-01

    We propose a new method to produce time series of global maps of surface mass variations by progressive integration of daily geopotential variations measured by orbiting satellites. In the case of the GRACE mission (2002 - 2012), these geopotential variations can be determined from very accurate inter-satellite K-Band Range Rate (KBRR) measurements of 5-second daily orbits. In particular, the along-track gravity contribution of hydrology is extracted by removing de-aliasing models for static field, atmosphere, oceans mass variations (including periodical tides), as well as polar movements. Our determination of surface mass sources consists of two successive dependent Kalman filter stages. The first one consists of reducing the satellite-based potential anomalies by adjusting the longest spatial wavelengths (i.e., low-degree spherical harmonics less than 5-6). In the second stage, the residual potential anomalies from the previous stage are used to recover surface mass density changes - in terms of Equivalent-Water Height (EWH) - over a global network of juxtaposed triangular elements. These surface tiles of ~40,000 km x km are imposed to be identical and homogeneously-distributed over the terrestrial sphere, however they can be adapted to the local geometry of the surface mass. Our global approach was tested by inverting simulated hydrology-related geopotential data, and successfully applied to estimate time-varying surface mass densities from real GRACE-based residuals. This strategy of combined Kalman filter-type inversions can also be useful for exploring the possibility of reaching better time and space resolutions for hydrology, that would be hopefully brought by future low altitude geodetic missions.

  16. Two-step Laser Time-of-Flight Mass Spectrometry to Elucidate Organic Diversity in Planetary Surface Materials.

    NASA Technical Reports Server (NTRS)

    Getty, Stephanie A.; Brinckerhoff, William B.; Cornish, Timothy; Li, Xiang; Floyd, Melissa; Arevalo, Ricardo Jr.; Cook, Jamie Elsila; Callahan, Michael P.

    2013-01-01

    Laser desorption/ionization time-of-flight mass spectrometry (LD-TOF-MS) holds promise to be a low-mass, compact in situ analytical capability for future landed missions to planetary surfaces. The ability to analyze a solid sample for both mineralogical and preserved organic content with laser ionization could be compelling as part of a scientific mission pay-load that must be prepared for unanticipated discoveries. Targeted missions for this instrument capability include Mars, Europa, Enceladus, and small icy bodies, such as asteroids and comets.

  17. A high-order discontinuous Galerkin method for fluid–structure interaction with efficient implicit–explicit time stepping

    SciTech Connect

    Froehle, Bradley Persson, Per-Olof

    2014-09-01

    We present a high-order accurate scheme for coupled fluid–structure interaction problems. The fluid is discretized using a discontinuous Galerkin method on unstructured tetrahedral meshes, and the structure uses a high-order volumetric continuous Galerkin finite element method. Standard radial basis functions are used for the mesh deformation. The time integration is performed using a partitioned approach based on implicit–explicit Runge–Kutta methods. The resulting scheme fully decouples the implicit solution procedures for the fluid and the solid parts, which we perform using two separate efficient parallel solvers. We demonstrate up to fifth order accuracy in time on a non-trivial test problem, on which we also show that additional subiterations are not required. We solve a benchmark problem of a cantilever beam in a shedding flow, and show good agreement with other results in the literature. Finally, we solve for the flow around a thin membrane at a high angle of attack in both 2D and 3D, and compare with the results obtained with a rigid plate.

  18. Nucleoside uptake in macrophages from various murine strains: a short-time and a two-step stimulation model

    SciTech Connect

    Busolo, F.; Conventi, L.; Grigolon, M.; Palu, G. )

    1991-06-28

    Kinetics of (3H)-uridine uptake by murine peritoneal macrophages (pM phi) is early altered after exposure to a variety of stimuli. Alterations caused by Candida albicans, lipopolysaccharide (LPS) and recombinant interferon-gamma (rIFN-gamma) were similar in SAVO, C57BL/6, C3H/HeN and C3H/HeJ mice, and were not correlated with an activation process as shown by the amount of tumor necrosis factor-alpha (TNF-alpha) being released. Short-time exposure to all stimuli resulted in an increased nucleoside uptake by SAVO pM phi, suggesting that the tumoricidal function of this cell either depends from the type of stimulus or the time when the specific interaction with the cell receptor is taking place. Experiments with priming and triggering signals confirmed the above findings, indicating that the increase or the decrease of nucleoside uptake into the cell depends essentially on the chemical nature of the priming stimulus. The triggering stimulus, on the other hand, is only able to amplify the primary response.

  19. Step Pultrusion

    NASA Astrophysics Data System (ADS)

    Langella, A.; Carbone, R.; Durante, M.

    2012-12-01

    The pultrusion process is an efficient technology for the production of composite material profiles. Thanks to this positive feature, several studies have been carried out, either to expand the range of products made using the pultrusion technology, or improve its already high production rate. This study presents a process derived from the traditional pultrusion technology named "Step Pultrusion Process Technology" (SPPT). Using the step pultrusion process, the final section of the composite profiles is obtainable by means of a progressive cross section increasing through several resin cure stations. This progressive increasing of the composite cross section means that a higher degree of cure level can be attained at the die exit point of the last die. Mechanical test results of the manufactured pultruded samples have been used to compare both the traditional and the step pultrusion processes. Finally, there is a discussion on ways to improve the new step pultrusion process even further.

  20. Cyclic steps on ice

    NASA Astrophysics Data System (ADS)

    Yokokawa, M.; Izumi, N.; Naito, K.; Parker, G.; Yamada, T.; Greve, R.

    2016-05-01

    Boundary waves often form at the interface between ice and fluid flowing adjacent to it, such as ripples under river ice covers, and steps on the bed of supraglacial meltwater channels. They may also be formed by wind, such as the megadunes on the Antarctic ice sheet. Spiral troughs on the polar ice caps of Mars have been interpreted to be cyclic steps formed by katabatic wind blowing over ice. Cyclic steps are relatives of upstream-migrating antidunes. Cyclic step formation on ice is not only a mechanical but also a thermodynamic process. There have been very few studies on the formation of either cyclic steps or upstream-migrating antidunes on ice. In this study, we performed flume experiments to reproduce cyclic steps on ice by flowing water, and found that trains of steps form when the Froude number is larger than unity. The features of those steps allow them to be identified as ice-bed analogs of cyclic steps in alluvial and bedrock rivers. We performed a linear stability analysis and obtained a physical explanation of the formation of upstream-migrating antidunes, i.e., precursors of cyclic steps. We compared the results of experiments with the predictions of the analysis and found the observed steps fall in the range where the analysis predicts interfacial instability. We also found that short antidune-like undulations formed as a precursor to the appearance of well-defined steps. This fact suggests that such antidune-like undulations correspond to the instability predicted by the analysis and are precursors of cyclic steps.

  1. Detection of Langat virus by TaqMan real-time one-step qRT-PCR method

    PubMed Central

    Muhd Radzi, Siti Fatimah; Rückert, Claudia; Sam, Sing-Sin; Teoh, Boon-Teong; Jee, Pui-Fong; Phoon, Wai-Hong; Abubakar, Sazaly; Zandi, Keivan

    2015-01-01

    Langat virus (LGTV), one of the members of the tick-borne encephalitis virus (TBEV) complex, was firstly isolated from Ixodes granulatus ticks in Malaysia. However, the prevalence of LGTV in ticks in the region remains unknown. Surveillance for LGTV is therefore important and thus a tool for specific detection of LGTV is needed. In the present study, we developed a real-time quantitative reverse-transcription-polymerase chain reaction (qRT-PCR) for rapid detection of LGTV. Our findings showed that the developed qRT-PCR could detect LGTV at a titre as low as 0.1 FFU/ml. The detection limit of the qRT-PCR assay at 95% probability was 0.28 FFU/ml as determined by probit analysis (p ≤ 0.05). Besides, the designed primers and probe did not amplify ORF of the E genes for some closely related and more pathogenic viruses including TBEV, Louping ill virus, Omsk hemorrhagic fever virus (OHFV), Alkhurma virus (ALKV), Kyasanur Forest Disease virus (KFDV) and Powassan virus (POWV) which showed the acceptable specificity of the developed assay. The sensitivity of the developed method also has been confirmed by determining the LGTV in infected tick cell line as well as LGTV- spiked tick tissues. PMID:26360297

  2. Investigation of a transonic axisymmetric backward-facing step flow by means of time-resolved PIV and PSP

    NASA Astrophysics Data System (ADS)

    Scharnowski, Sven; Bitter, Martin; Kähler, Christian J.

    2012-11-01

    The results presented here are obtained within a sub project of the SFB TRR 40 program (founded by the German research foundation), which focuses on the analysis and modeling of coupled liquid rocket propulsion systems and their integration into the space transportation system. The overall objective is to develop technological foundations for the design of thermally and mechanically highly loaded components of future space transportation systems. The interaction between the shear layer and the nozzle in the wake of the launcher is particularly important. Therefore, detailed analyses of a generic space launcher model's wake flow are the main emphasis of this sub project. The combination of time-resolved PIV and PSP provide deep insights into the flow physics: The separation at the end of the main body, the formation of the shear layer, its growth and its reattachment, as well as the surface pressure fluctuations, are analyzed in detail. The results reveal unsteady loads caused by shear layer motion which could interfere with structural modes of a space launcher main engines' nozzle.

  3. Influence of step increases in hydraulic retention time on (RS)-MCPP degradation using an anaerobic membrane bioreactor.

    PubMed

    Yuzir, Ali; Chelliapan, Shreeshivadasan; Sallis, Paul J

    2011-10-01

    The effects of different hydraulic retention time (HRT) on (RS)-MCPP utilisation was investigated by decreasing the feed flow rate in an anaerobic membrane bioreactor (AnMBR). Results showed an average COD removal efficiency of 91.4%, 96.9% and 94.4% when the reactor was operated at HRT 3, 7 and 17 d, respectively. However, when the HRT was reduced to 1d, the COD removal efficiency declined to just only 60%, confirming the AnMBR is stable to a large transient hydraulic shock loads. The (RS)-MCPP removal efficiency fluctuated from 6% to 39% at HRT 3 d, however when it was increased to 7 and 17 d, the removal efficiency increased to an average of 60% and 74.5%. In addition, (RS)-MCPP specific utilisation rates (SUR) were dependent on the HRT and gradually improved from 18 to 43 μg mg VSS(-1) d(-1) as flow rate increased. PMID:21862323

  4. A Two-Step Lyssavirus Real-Time Polymerase Chain Reaction Using Degenerate Primers with Superior Sensitivity to the Fluorescent Antigen Test

    PubMed Central

    Nazé, Florence; Francart, Aurélie; Lamoral, Sophie; De Craeye, Stéphane; Kalai, Michael

    2014-01-01

    A generic two-step lyssavirus real-time reverse transcriptase polymerase chain reaction (qRT-PCR), based on a nested PCR strategy, was validated for the detection of different lyssavirus species. Primers with 17 to 30% of degenerate bases were used in both consecutive steps. The assay could accurately detect RABV, LBV, MOKV, DUVV, EBLV-1, EBLV-2, and ABLV. In silico sequence alignment showed a functional match with the remaining lyssavirus species. The diagnostic specificity was 100% and the sensitivity proved to be superior to that of the fluorescent antigen test. The limit of detection was ≤1 50% tissue culture infectious dose. The related vesicular stomatitis virus was not recognized, confirming the selectivity for lyssaviruses. The assay was applied to follow the evolution of rabies virus infection in the brain of mice from 0 to 10 days after intranasal inoculation. The obtained RNA curve corresponded well with the curves obtained by a one-step monospecific RABV-qRT-PCR, the fluorescent antigen test, and virus titration. Despite the presence of degenerate bases, the assay proved to be highly sensitive, specific, and reproducible. PMID:24822188

  5. Linking search space structure, run-time dynamics, and problem difficulty : a step toward demystifying tabu search.

    SciTech Connect

    Whitley, L. Darrell; Howe, Adele E.; Watson, Jean-Paul

    2004-09-01

    Tabu search is one of the most effective heuristics for locating high-quality solutions to a diverse array of NP-hard combinatorial optimization problems. Despite the widespread success of tabu search, researchers have a poor understanding of many key theoretical aspects of this algorithm, including models of the high-level run-time dynamics and identification of those search space features that influence problem difficulty. We consider these questions in the context of the job-shop scheduling problem (JSP), a domain where tabu search algorithms have been shown to be remarkably effective. Previously, we demonstrated that the mean distance between random local optima and the nearest optimal solution is highly correlated with problem difficulty for a well-known tabu search algorithm for the JSP introduced by Taillard. In this paper, we discuss various shortcomings of this measure and develop a new model of problem difficulty that corrects these deficiencies. We show that Taillard's algorithm can be modeled with high fidelity as a simple variant of a straightforward random walk. The random walk model accounts for nearly all of the variability in the cost required to locate both optimal and sub-optimal solutions to random JSPs, and provides an explanation for differences in the difficulty of random versus structured JSPs. Finally, we discuss and empirically substantiate two novel predictions regarding tabu search algorithm behavior. First, the method for constructing the initial solution is highly unlikely to impact the performance of tabu search. Second, tabu tenure should be selected to be as small as possible while simultaneously avoiding search stagnation; values larger than necessary lead to significant degradations in performance.

  6. Accurate molecular dynamics and nuclear quantum effects at low cost by multiple steps in real and imaginary time: Using density functional theory to accelerate wavefunction methods.

    PubMed

    Kapil, V; VandeVondele, J; Ceriotti, M

    2016-02-01

    The development and implementation of increasingly accurate methods for electronic structure calculations mean that, for many atomistic simulation problems, treating light nuclei as classical particles is now one of the most serious approximations. Even though recent developments have significantly reduced the overhead for modeling the quantum nature of the nuclei, the cost is still prohibitive when combined with advanced electronic structure methods. Here we present how multiple time step integrators can be combined with ring-polymer contraction techniques (effectively, multiple time stepping in imaginary time) to reduce virtually to zero the overhead of modelling nuclear quantum effects, while describing inter-atomic forces at high levels of electronic structure theory. This is demonstrated for a combination of MP2 and semi-local DFT applied to the Zundel cation. The approach can be seamlessly combined with other methods to reduce the computational cost of path integral calculations, such as high-order factorizations of the Boltzmann operator or generalized Langevin equation thermostats. PMID:26851912

  7. Multi-time-step ahead daily and hourly intermittent reservoir inflow prediction by artificial intelligent techniques using lumped and distributed data

    NASA Astrophysics Data System (ADS)

    Jothiprakash, V.; Magar, R. B.

    2012-07-01

    SummaryIn this study, artificial intelligent (AI) techniques such as artificial neural network (ANN), Adaptive neuro-fuzzy inference system (ANFIS) and Linear genetic programming (LGP) are used to predict daily and hourly multi-time-step ahead intermittent reservoir inflow. To illustrate the applicability of AI techniques, intermittent Koyna river watershed in Maharashtra, India is chosen as a case study. Based on the observed daily and hourly rainfall and reservoir inflow various types of time-series, cause-effect and combined models are developed with lumped and distributed input data. Further, the model performance was evaluated using various performance criteria. From the results, it is found that the performances of LGP models are found to be superior to ANN and ANFIS models especially in predicting the peak inflows for both daily and hourly time-step. A detailed comparison of the overall performance indicated that the combined input model (combination of rainfall and inflow) performed better in both lumped and distributed input data modelling. It was observed that the lumped input data models performed slightly better because; apart from reducing the noise in the data, the better techniques and their training approach, appropriate selection of network architecture, required inputs, and also training-testing ratios of the data set. The slight poor performance of distributed data is due to large variations and lesser number of observed values.

  8. Temporal averaging of phase measurements in the presence of spurious phase drift - Application to phase-stepped real-time holographic interferometry

    NASA Technical Reports Server (NTRS)

    Ovryn, B.; Haacke, E. M.

    1993-01-01

    A technique that compensates for low spatial frequency spurious phase changes during an interference experiment is developed; it permits temporal averaging of multiple-phase measurements, made before and after object displacement. The method is tested with phase-stepped real-time holographic interferometry applied to cantilever bending of a piezoelectric bimorph ceramic. Results indicate that temporal averaging of the corrected data significantly reduces the white noise in a phase measurement without incurring systematic errors or sacrificing spatial resolution. White noise is reduced from 3 deg to less than 1 deg using these methods.

  9. A variable multi-step method for transient heat conduction

    NASA Technical Reports Server (NTRS)

    Smolinski, Patrick

    1991-01-01

    A variable explicit time integration algorithm is developed for unsteady diffusion problems. The algorithm uses nodal partitioning and allows the nodal groups to be updated with different time steps. The stability of the algorithm is analyzed using energy methods and critical time steps are found in terms of element eigenvalues with no restrictions on element types. Several numerical examples are given to illustrate the accuracy of the method.

  10. Time-stepping methods for the simulation of the self-assembly of nano-crystals in MATLAB on a GPU

    NASA Astrophysics Data System (ADS)

    Korzec, M. D.; Ahnert, T.

    2013-10-01

    Partial differential equations describing the patterning of thin crystalline films are typically of fourth or sixth order, they are quasi- or semilinear and they are mostly defined on simple geometries such as rectangular domains. For the numerical simulation of these kinds of problems spectral methods are an efficient approach. We apply several implicit-explicit schemes to one recently derived PDE that we express in terms of coefficients of trigonometric interpolants. While the simplest IMEX scheme turns out to have the mildest step-size restriction, higher order SBDF schemes tend to be more unstable and exponential time integrators are fastest for the calculation of very accurate solutions. We implemented a reduced model in the EXPINT package syntax [3] and compared various exponential schemes. A convexity splitting approach was employed to stabilize the SBDF1 scheme. We show that accuracy control is crucial when using this idea, therefore we present a time-adaptive SBDF1/SBDF1-2-step method that yields convincing results reflecting the change in timescales during topological changes of the nanostructures. The implementation of all presented methods is carried out in MATLAB. We used the open source GPUmat package to gain up to 5-fold runtime benefits by carrying out calculations on a low-cost GPU without having to prescribe any knowledge in low-level programming or CUDA implementations and found comparable speedups as with MATLAB's PCT or with GPUmat run on Octave.

  11. Development of a two-step SYBR Green I based real time RT-PCR assay for detecting and quantifying peste des petits ruminants virus in clinical samples.

    PubMed

    Abera, Tsegalem; Thangavelu, Ardhanary

    2014-12-01

    A two-step SYBR Green I based real time RT-PCR targeting the matrix (M) gene of Peste des petits ruminants virus (PPRV) was developed. The specificity of the assay was assessed against viral nucleic acid extracted from a range of animal viruses of clinical and structural similarities to PPRV including canine distemper virus, measles virus, bluetongue virus and Newcastle disease virus. But none of the viruses and no template control showed an amplification signal. Sensitivity of the same assay was assessed based on plasmid DNA copy number and with respect to infectivity titre. The lower detection limit achieved was 2.88 plasmid DNA copies/μl with corresponding Ct value of 35.93. Based on tissue culture infectivity titre the lower detection limits were 0.0001TCID50/ml and 1TCID50/ml for the SYBR green I based real time RT-PCR and conventional RT-PCR, respectively. The calculated coefficient of variations values for intra- and inter-assay variability were low, ranging from 0.21% to 1.83% and 0.44% to 1.97%, respectively. The performance of newly developed assay was evaluated on a total of 36 clinical samples suspected of PPR and compared with conventional RT-PCR. The SYBR Green I based real time RT-PCR assay detected PPRV in 32 (88.8%) of clinical samples compared to 19 (52.7%) by conventional RT-PCR. Thus, the two-step SYBR Green I based real time RT-PCR assay targeting the M gene of PPRV reported in this study was highly sensitive, specific and reproducible for detection and quantitation of PPRV nucleic acids. PMID:25194891

  12. Development of novel triplex single-step real-time PCR assay for detection of Hepatitis Virus B and C simultaneously.

    PubMed

    Prakash, Shantanu; Jain, Amita; Jain, Bhawana

    2016-05-01

    Multiplex RT-PCR assays are widely used tools for detection of hepatitis viruses, but none of them provide quality check of sample. In the present study we developed a single-step triplex real-time polymerase chain reaction (PCR) assay for detection of Hepatitis B Virus (HBV) and Hepatitis C Virus (HCV) with sample quality check, by using β-actin as housekeeping gene. The primers and probes were self-designed and assay was standardized. Assay was also destined to quantitate copy numbers of HBV and HCV. This novel assay was sensitive, specific, and reproducible for detection of HBV and HCV in serum/plasma. The assay also detected all genotypes of HBV and HCV. The detection limit was 60 IU/mL for HBV and 20 IU/mL for HCV. This assay is the first assay developed on single-step platform for nucleic acid detection of HBV and HCV with an extra edge over all other assays by providing inbuilt check for quality of sample. PMID:26914508

  13. Ultra-fast formation control of high-order discrete-time multi-agent systems based on multi-step predictive mechanism.

    PubMed

    Zhang, Wenle; Liu, Jianchang; Wang, Honghai

    2015-09-01

    This paper deals with the ultra-fast formation control problem of high-order discrete-time multi-agent systems. Using the local neighbor-error knowledge, a novel ultra-fast protocol with multi-step predictive information and self-feedback term is proposed. The asymptotic convergence factor is improved by a power of q+1 compared to the routine protocol. To some extent, the ultra-fast algorithm overcomes the influence of communication topology to the convergence speed. Furthermore, some sufficient conditions are given herein. The ones decouple the design of the synchronizing gains from the detailed graph properties, and explicitly reveal how the agent dynamic and the communication graph jointly affect the ultra-fast formationability. Finally, some simulations are worked out to illustrate the effectiveness of our theoretical results. PMID:26051965

  14. A parallel numerical simulation for supersonic flows using zonal overlapped grids and local time steps for common and distributed memory multiprocessors

    SciTech Connect

    Patel, N.R.; Sturek, W.B.; Hiromoto, R.

    1989-01-01

    Parallel Navier-Stokes codes are developed to solve both two- dimensional and three-dimensional flow fields in and around ramjet and nose tip configurations. A multi-zone overlapped grid technique is used to extend an explicit finite-difference method to more complicated geometries. Parallel implementations are developed for execution on both distributed and common-memory multiprocessor architectures. For the steady-state solutions, the use of the local time-step method has the inherent advantage of reducing the communications overhead commonly incurred by parallel implementations. Computational results of the codes are given for a series of test problems. The parallel partitioning of computational zones is also discussed. 5 refs., 18 figs.

  15. Nonstandard Finite Difference Schemes: Relations Between Time and Space Step-Sizes in Numerical Schemes for PDE's That Follow from Positivity Condition

    NASA Technical Reports Server (NTRS)

    Mickens, Ronald E.

    1996-01-01

    A large class of physical phenomena can be modeled by evolution and wave type Partial Differential Equations (PDE). Few of these equations have known explicit exact solutions. Finite-difference techniques are a popular method for constructing discrete representations of these equations for the purpose of numerical integration. However, the solutions to the difference equations often contain so called numerical instabilities; these are solutions to the difference equations that do not correspond to any solution of the PDE's. For explicit schemes, the elimination of this behavior requires functional relations to exist between the time and space steps-sizes. We show that such functional relations can be obtained for certain PDE's by use of a positivity condition. The PDE's studied are the Burgers, Fisher, and linearized Euler equations.

  16. Establishment and validation of two duplex one-step real-time RT-PCR assays for diagnosis of foot-and-mouth disease.

    PubMed

    Gorna, K; Relmy, A; Romey, A; Zientara, S; Blaise-Boisseau, S; Bakkali-Kassimi, L

    2016-09-01

    Two duplex one-step TaqMan-based RT-PCR protocols for detection of foot-and-mouth disease virus (FMDV) were established and validated. Each RT-PCR test consists of a ready-to-use master mix for simultaneous detection of the well established 3D or IRES FMDV targets and incorporates the host β-actin mRNA as an internal control target, in a single-tube assay. The two real-time RT-PCR 3D/β-actin and IRES/β-actin tests are highly sensitive and able to detect up to 7TCID50/ml of FMDV and 10 copies/1μl of viral RNA. In field epithelium samples, the diagnostic sensitivity was 100% (95% CI; 91-100%) for the 3D/β-actin test and 97% (95% CI; 87-100%) for the IRES/β-actin test. The diagnostic specificity was 100% (95% CI; 95-100%) for both RT-PCRs. In addition, the two protocols proved to be robust, showing inter-assay coefficients of variation ranging from 1.94% to 6.73% for the IRES target and from 2.33% to 5.42% for the 3D target for different RNA extractions and different RT-PCR conditions. The internally controlled one-step real-time RT-PCR protocols described in this study provide a rapid, effective and reliable method for the detection of FMDV and thus may improve the routine diagnosis for foot-and-mouth disease. PMID:27317973

  17. A journey of a thousand miles begins with one small step - human agency, hydrological processes and time in socio-hydrology

    NASA Astrophysics Data System (ADS)

    Ertsen, M. W.; Murphy, J. T.; Purdue, L. E.; Zhu, T.

    2014-04-01

    When simulating social action in modeling efforts, as in socio-hydrology, an issue of obvious importance is how to ensure that social action by human agents is well-represented in the analysis and the model. Generally, human decision-making is either modeled on a yearly basis or lumped together as collective social structures. Both responses are problematic, as human decision-making is more complex and organizations are the result of human agency and cannot be used as explanatory forces. A way out of the dilemma of how to include human agency is to go to the largest societal and environmental clustering possible: society itself and climate, with time steps of years or decades. In the paper, another way out is developed: to face human agency squarely, and direct the modeling approach to the agency of individuals and couple this with the lowest appropriate hydrological level and time step. This approach is supported theoretically by the work of Bruno Latour, the French sociologist and philosopher. We discuss irrigation archaeology, as it is in this discipline that the issues of scale and explanatory force are well discussed. The issue is not just what scale to use: it is what scale matters. We argue that understanding the arrangements that permitted the management of irrigation over centuries requires modeling and understanding the small-scale, day-to-day operations and personal interactions upon which they were built. This effort, however, must be informed by the longer-term dynamics, as these provide the context within which human agency is acted out.

  18. A journey of a thousand miles begins with one small step - human agency, hydrological processes and time in socio-hydrology

    NASA Astrophysics Data System (ADS)

    Ertsen, M. W.; Murphy, J. T.; Purdue, L. E.; Zhu, T.

    2013-11-01

    When simulating social action in modeling efforts, as in socio-hydrology, an issue of obvious importance is how to ensure that social action by human agents is well-represented in the analysis and the model. Generally, human decision-making is either modeled on a yearly basis or lumped together as collective social structures. Both responses are problematic, as human decision making is more complex and organizations are the result of human agency and cannot be used as explanatory forces. A way out of the dilemma how to include human agency is to go to the largest societal and environmental clustering possible: society itself and climate, with time steps of years or decades. In the paper, the other way out is developed: to face human agency squarely, and direct the modeling approach to the human agency of individuals and couple this with the lowest appropriate hydrological level and time step. This approach is supported theoretically by the work of Bruno Latour, the French sociologist and philosopher. We discuss irrigation archaeology, as it is in this discipline that the issues of scale and explanatory force are well discussed. The issue is not just what scale to use: it is what scale matters. We argue that understanding the arrangements that permitted the management of irrigation over centuries, requires modeling and understanding the small-scale, day-to-day operations and personal interactions upon which they were built. This effort, however, must be informed by the longer-term dynamics as these provide the context within which human agency, is acted out.

  19. The validation and utility of a quantitative one-step multiplex RT real-time PCR targeting Rotavirus A and Norovirus

    PubMed Central

    Dung, Tran Thi Ngoc; Phat, Voong Vinh; Nga, Tran Vu Thieu; My, Phan Vu Tra; Duy, Pham Thanh; Campbell, James I.; Thuy, Cao Thu; Hoang, Nguyen Van Minh; Van Minh, Pham; Le Phuc, Hoang; Tuyet, Pham Thi Ngoc; Vinh, Ha; Kien, Duong Thi Hue; Huy, Huynh Le Anh; Vinh, Nguyen Thanh; Nga, Tran Thi Thu; Hau, Nguyen Thi Thu; Chinh, Nguyen Tran; Thuong, Tang Chi; Tuan, Ha Manh; Simmons, Cameron; Farrar, Jeremy J.; Baker, Stephen

    2013-01-01

    Rotavirus (RoV) and Norovirus (NoV) are the main causes of viral gastroenteritis. Currently, there is no validated multiplex real-time PCR that can detect and quantify RoV and NoV simultaneously. The aim of the study was to develop, validate, and internally control a multiplex one-step RT real-time PCR to detect and quantify RoV and NoV in stool samples. PCR sensitivity was assessed by comparing amplification against the current gold standard, enzyme immunoassay (EIA), on stool samples from 94 individuals with diarrhea and 94 individuals without diarrhea. PCR detected 10% more RoV positive samples than EIA in stools samples from patients with diarrhea. PCR detected 23% more NoV genogroup II positive samples from individuals with diarrhea and 9% more from individuals without diarrhea than EIA, respectively. Genotyping of the PCR positive/EIA negative samples suggested the higher rate of PCR positivity, in comparison to EIA, was due to increased sensitivity, rather than nonspecific hybridization. Quantitation demonstrated that the viral loads of RoV and NoV in the stools of diarrheal patients were an order of magnitude greater than in individuals without diarrhea. This internally controlled real-time PCR method is robust, exhibits a high degree of reproducibility, and may have a greater utility and sensitivity than commercial EIA kits. PMID:23046990

  20. Diagnosis of Cetacean morbillivirus: A sensitive one step real time RT fast-PCR method based on SYBR(®) Green.

    PubMed

    Sacristán, Carlos; Carballo, Matilde; Muñoz, María Jesús; Bellière, Edwige Nina; Neves, Elena; Nogal, Verónica; Esperón, Fernando

    2015-12-15

    Cetacean morbillivirus (CeMV) (family Paramyxoviridae, genus Morbillivirus) is considered the most pathogenic virus of cetaceans. It was first implicated in the bottlenose dolphin (Tursiops truncatus) mass stranding episode along the Northwestern Atlantic coast in the late 1980s, and in several more recent worldwide epizootics in different Odontoceti species. This study describes a new one step real-time reverse transcription fast polymerase chain reaction (real-time RT-fast PCR) method based on SYBR(®) Green to detect a fragment of the CeMV fusion protein gene. This primer set also works for conventional RT-PCR diagnosis. This method detected and identified all three well-characterized strains of CeMV: porpoise morbillivirus (PMV), dolphin morbillivirus (DMV) and pilot whale morbillivirus (PWMV). Relative sensitivity was measured by comparing the results obtained from 10-fold dilution series of PMV and DMV positive controls and a PWMV field sample, to those obtained by the previously described conventional phosphoprotein gene based RT-PCR method. Both the conventional and real-time RT-PCR methods involving the fusion protein gene were 100- to 1000-fold more sensitive than the previously described conventional RT-PCR method. PMID:26454114

  1. Development of one-step real-time reverse transcriptase-PCR-based assays for the rapid and simultaneous detection of four viruses causing porcine diarrhea.

    PubMed

    Masuda, Tsuneyuki; Tsuchiaka, Shinobu; Ashiba, Tomoko; Yamasato, Hiroshi; Fukunari, Kazuhiro; Omatsu, Tsutomu; Furuya, Tetsuya; Shirai, Junsuke; Mizutani, Tetsuya; Nagai, Makoto

    2016-02-01

    Porcine diarrhea caused by viruses is a major problem of the pig farming industry and can result in substantial losses of revenue. Thus, diagnosing the infectious agents is important to prevent and control diseases in pigs. We developed novel one-step real-time quantitative RT-PCR (qPCR) assays that can detect four porcine diarrheal viruses simultaneously: porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), porcine deltacoronavirus (PDCoV), and porcine group A rotavirus (PRVA). The qPCR analysis takes only 75 minutes to detect the presence of the four viruses. The limits of detection of our new assays for PEDV, TGEV, PDCoV, and PRVA were 100, 10, 10 and 10 copies per reaction, respectively. The sensitivity of qPCR was 1-1000 times higher than that of published gel-based RT-PCR. We used our qPCR method to successfully diagnose clinical samples from infected pigs, and no false positive results were obtained. In conclusion, qPCR can drastically reduce the diagnostic time to detect viruses compared to currently employed methods. We predict that the qPCR assays will become a useful tool for detecting viral infections that cause diarrhea and other complications in pigs. PMID:27348884

  2. The validation and utility of a quantitative one-step multiplex RT real-time PCR targeting rotavirus A and norovirus.

    PubMed

    Dung, Tran Thi Ngoc; Phat, Voong Vinh; Nga, Tran Vu Thieu; My, Phan Vu Tra; Duy, Pham Thanh; Campbell, James I; Thuy, Cao Thu; Hoang, Nguyen Van Minh; Van Minh, Pham; Le Phuc, Hoang; Tuyet, Pham Thi Ngoc; Vinh, Ha; Kien, Duong Thi Hue; Huy, Huynh Le Anh; Vinh, Nguyen Thanh; Nga, Tran Thi Thu; Hau, Nguyen Thi Thu; Chinh, Nguyen Tran; Thuong, Tang Chi; Tuan, Ha Manh; Simmons, Cameron; Farrar, Jeremy J; Baker, Stephen

    2013-01-01

    Rotavirus (RoV) and Norovirus (NoV) are the main causes of viral gastroenteritis. Currently, there is no validated multiplex real-time PCR that can detect and quantify RoV and NoV simultaneously. The aim of the study was to develop, validate, and internally control a multiplex one-step RT real-time PCR to detect and quantify RoV and NoV in stool samples. PCR sensitivity was assessed by comparing amplification against the current gold standard, enzyme immunoassay (EIA), on stool samples from 94 individuals with diarrhea and 94 individuals without diarrhea. PCR detected 10% more RoV positive samples than EIA in stools samples from patients with diarrhea. PCR detected 23% more NoV genogroup II positive samples from individuals with diarrhea and 9% more from individuals without diarrhea than EIA, respectively. Genotyping of the PCR positive/EIA negative samples suggested the higher rate of PCR positivity, in comparison to EIA, was due to increased sensitivity, rather than nonspecific hybridization. Quantitation demonstrated that the viral loads of RoV and NoV in the stools of diarrheal patients were an order of magnitude greater than in individuals without diarrhea. This internally controlled real-time PCR method is robust, exhibits a high degree of reproducibility, and may have a greater utility and sensitivity than commercial EIA kits. PMID:23046990

  3. Development of a rapid Buffer-exchange system for time-resolved ATR-FTIR spectroscopy with the step-scan mode

    PubMed Central

    Furutani, Yuji; Kimura, Tetsunari; Okamoto, Kido

    2013-01-01

    Attenuated total reflectance (ATR)-FTIR spectroscopy has been widely used to probe protein structural changes under various stimuli, such as light absorption, voltage change, and ligand binding, in aqueous conditions. Time-resolved measurements require a trigger, which can be controlled electronically; therefore, light and voltage changes are suitable. Here we developed a novel, rapid buffer-exchange system for time-resolved ATR-FTIR spectroscopy to monitor the ligand- or ion-binding re-action of a protein. By using the step-scan mode (time resolution; 2.5 ms), we confirmed the completion of the buffer-exchange reaction within ∼25 ms; the process was monitored by the infrared absorption change of a nitrate band at 1,350 cm−1. We also demonstrated the anion-binding reaction of a membrane protein, Natronomonas pharaonis halorhodopsin (pHR), which binds a chloride ion in the initial anion-binding site near the retinal chromophore. The formation of chloride- or nitrate-bound pHR was confirmed by an increase of the retinal absorption band at 1,528 cm−1. It also should be noted that low sample consumption (∼1 µg of protein) makes this new method a powerful technique to understand ligand–protein and ion–protein interactions, particularly for membrane proteins. PMID:27493550

  4. A time stepping coupled finite element-state space modeling environment for synchronous machine performance and design analysis in the ABC frame of reference

    NASA Astrophysics Data System (ADS)

    Deng, Fang

    This dissertation centers on the development of a modeling environment to predict the performance and operating characteristics of salient-pole synchronous generators. The model basically consists of an algorithm consisting of two sections, a time stepping two-dimensional (2D) magnetostatic field finite element (FE) computation algorithm coupled to a state-space (SS) time-domain model of the winding circuits. Hence the term time stepping Coupled Finite Element-State Space (CFE-SS) modeling environment is adopted for this approach. In the FE section, magnetic vector potential (MVP) based finite element (FE) formulations and computation of two-dimensional (2D) magnetostatic fields are used to get the magnetic field solutions throughout a machine's cross-section at a sequence (samplings) of rotor positions covering a complete (360 deg e) ac cycle. These field solutions yield the winding inductances by means of an energy and current perturbation method. The output of the FE section is the magnetic field solutions and the entire set of phase, field, damper, and sleeve winding inductance profiles versus rotor position, including all space harmonics due to rotor saliency, damper bar slotting, sleeve segmentation, stator slotting, and magnetic saturation. These inductance profiles are decomposed into their harmonic components by Fourier analysis. The magnetic field solutions and resulting winding inductances represent the key input data to the SS portion of the CFE-SS modeling environment. Laminated machine iron core loss calculations, which include the losses in the stator and rotor as well as pole face are subsequently performed using the magnetic field solution data. Conversely, the output of the SS portion is the entire set of phase, field, damper winding (circuit), and sleeve segment currents, which also include all the resulting time harmonics. These winding current results form in turn the key input data to the FE portion of the modeling environment which is

  5. Golgi-Cox Staining Step by Step

    PubMed Central

    Zaqout, Sami; Kaindl, Angela M.

    2016-01-01

    Golgi staining remains a key method to study neuronal morphology in vivo. Since most protocols delineating modifications of the original staining method lack details on critical steps, establishing this method in a laboratory can be time-consuming and frustrating. Here, we describe the Golgi-Cox staining in such detail that should turn the staining into an easily feasible method for all scientists working in the neuroscience field. PMID:27065817

  6. Dynamics of CO in Mesoporous Silica Monitored by Time ResolvedStep-Scan and Rapid-Scan FT-IR Spectroscopy

    SciTech Connect

    Andersen, Lars K.; Frei, Heinz

    2007-12-05

    Carbon monoxide molecules generated in the channels ofmesoporous MCM-41 silica sieve from a precursor (diphenyl cyclopropenone)by photodissociation with a nanosecond laser pulse were monitored by timeresolved FT-infrared spectroscopy using the step-scan and rapid-scanmethods. A very broad absorption of CO is observed in the region 2200 to2080 cm-1 at room temperature that decays in a biphasic mode. Two-thirdsof the band intensity decays on the hundreds of microsecond scale(lifetime 344 + 70 ?s). The process represents the escape of themolecules through the mesopores into the surrounding gas phase, and adiffusion constant of 1.5 x 10-9 m2/sec is derived. The broad profile ofthe absorption is attributed to contact of the random hopping CO withsiloxaneand silanol groups of the pore surface. Measurements usingMCM-41 with the silanols partially capped by trimethyl silyl groups gavefurther insight into the nature of the infrared band profile. These arethe first observations on the diffusion behavior of carbon monoxide in amesoporous material at room temperature. The residual carbon monoxideremains much longer in the pores and features distinct peaks at 2167 and2105 cm-1 characteristic for CO adsorbed on SiOH groups C end on and Oend on, respectively. The bands decrease with time constants of 113 + 3ms (2167 cm-1) and 155 + 15 ms (2105 cm-1) suggesting that CO in thesesites is additionally trapped by surrounding diphenyl acetyleneco-product and/or precursor molecules.

  7. The effect of time step, thermostat, and strain rate on ReaxFF simulations of mechanical failure in diamond, graphene, and carbon nanotube.

    PubMed

    Jensen, Benjamin D; Wise, Kristopher E; Odegard, Gregory M

    2015-08-01

    As the sophistication of reactive force fields for molecular modeling continues to increase, their use and applicability has also expanded, sometimes beyond the scope of their original development. Reax Force Field (ReaxFF), for example, was originally developed to model chemical reactions, but is a promising candidate for modeling fracture because of its ability to treat covalent bond cleavage. Performing reliable simulations of a complex process like fracture, however, requires an understanding of the effects that various modeling parameters have on the behavior of the system. This work assesses the effects of time step size, thermostat algorithm and coupling coefficient, and strain rate on the fracture behavior of three carbon-based materials: graphene, diamond, and a carbon nanotube. It is determined that the simulated stress-strain behavior is relatively independent of the thermostat algorithm, so long as coupling coefficients are kept above a certain threshold. Likewise, the stress-strain response of the materials was also independent of the strain rate, if it is kept below a maximum strain rate. Finally, the mechanical properties of the materials predicted by the Chenoweth C/H/O parameterization for ReaxFF are compared with literature values. Some deficiencies in the Chenoweth C/H/O parameterization for predicting mechanical properties of carbon materials are observed. PMID:26096628

  8. Diablo 2.0: A modern DNS/LES code for the incompressible NSE leveraging new time-stepping and multigrid algorithms

    NASA Astrophysics Data System (ADS)

    Cavaglieri, Daniele; Bewley, Thomas; Mashayek, Ali

    2015-11-01

    We present a new code, Diablo 2.0, for the simulation of the incompressible NSE in channel and duct flows with strong grid stretching near walls. The code leverages the fractional step approach with a few twists. New low-storage IMEX (implicit-explicit) Runge-Kutta time-marching schemes are tested which are superior to the traditional and widely-used CN/RKW3 (Crank-Nicolson/Runge-Kutta-Wray) approach; the new schemes tested are L-stable in their implicit component, and offer improved overall order of accuracy and stability with, remarkably, similar computational cost and storage requirements. For duct flow simulations, our new code also introduces a new smoother for the multigrid solver for the pressure Poisson equation. The classic approach, involving alternating-direction zebra relaxation, is replaced by a new scheme, dubbed tweed relaxation, which achieves the same convergence rate with roughly half the computational cost. The code is then tested on the simulation of a shear flow instability in a duct, a classic problem in fluid mechanics which has been the object of extensive numerical modelling for its role as a canonical pathway to energetic turbulence in several fields of science and engineering.

  9. The relationship between Monte Carlo estimators of heterogeneity and error for daily to monthly time steps in a small Minnesota precipitation gauge network

    NASA Astrophysics Data System (ADS)

    Wright, Michael; Ferreira, Celso; Houck, Mark; Giovannettone, Jason

    2015-07-01

    Precipitation quantile estimates are used in engineering, agriculture, and a variety of other disciplines. Index flood regional frequency methods pool normalized gauge data in the case of homogeneity among the constituent gauges of the region. Unitless regional quantile estimates are outputted and rescaled at each gauge. Because violation of the homogeneity hypothesis is a major component of quantile estimation error in regional frequency analysis, heterogeneity estimators should be "reasonable proxies" of the error of quantile estimation. In this study, three Monte Carlo heterogeneity statistics tested in Hosking and Wallis (1997) are plotted against Monte Carlo estimates of quantile error for all five-or-more-gauge regionalizations in a 12 gauge network in the Twin Cities region of Minnesota. Upper-tail quantiles with nonexceedance probabilities of 0.75 and above are examined at time steps ranging from daily to monthly. A linear relationship between heterogeneity and error estimates is found and quantified using Pearson's r score. Two of Hosking and Wallis's (1997) heterogeneity measures, incorporating the coefficient of variation in one case and additionally the skewness in the other, are found to be reasonable proxies for quantile error at the L-moment ratio values characterizing these data. This result, in addition to confirming the utility of a commonly used coefficient of variation-based heterogeneity statistic, provides evidence for the utility of a heterogeneity measure that incorporates skewness information.

  10. Development of processes allowing near real-time refinement and validation of triage tools during the early stage of an outbreak in readiness for surge: the FLU-CATs Study.

    PubMed Central

    Venkatesan, Sudhir; Myles, Puja R; McCann, Gerard; Kousoulis, Antonis A; Hashmi, Maimoona; Belatri, Rabah; Boyle, Emma; Barcroft, Alan; van Staa, Tjeerd Pieter; Kirkham, Jamie J; Nguyen Van Tam, Jonathan S; Williams, Timothy J; Semple, Malcolm G

    2015-01-01

    BACKGROUND During pandemics of novel influenza and outbreaks of emerging infections, surge in health-care demand can exceed capacity to provide normal standards of care. In such exceptional circumstances, triage tools may aid decisions in identifying people who are most likely to benefit from higher levels of care. Rapid research during the early phase of an outbreak should allow refinement and validation of triage tools so that in the event of surge a valid tool is available. The overarching study aim is to conduct a prospective near real-time analysis of structured clinical assessments of influenza-like illness (ILI) using primary care electronic health records (EHRs) during a pandemic. This abstract summarises the preparatory work, infrastructure development, user testing and proof-of-concept study. OBJECTIVES (1) In preparation for conducting rapid research in the early phase of a future outbreak, to develop processes that allow near real-time analysis of general practitioner (GP) assessments of people presenting with ILI, management decisions and patient outcomes. (2) As proof of concept: conduct a pilot study evaluating the performance of the triage tools 'Community Assessment Tools' and 'Pandemic Medical Early Warning Score' to predict hospital admission and death in patients presenting with ILI to GPs during inter-pandemic winter seasons. DESIGN Prospective near real-time analysis of structured clinical assessments and anonymised linkage to data from EHRs. User experience was evaluated by semistructured interviews with participating GPs. SETTING Thirty GPs in England, Wales and Scotland, participating in the Clinical Practice Research Datalink. PARTICIPANTS All people presenting with ILI. INTERVENTIONS None. MAIN OUTCOME MEASURES Study outcome is proof of concept through demonstration of data capture and near real-time analysis. Primary patient outcomes were hospital admission within 24 hours and death (all causes) within 30 days of GP assessment. Secondary

  11. Development and Validation of a Quantitative, One-Step, Multiplex, Real-Time Reverse Transcriptase PCR Assay for Detection of Dengue and Chikungunya Viruses.

    PubMed

    Simmons, Monika; Myers, Todd; Guevara, Carolina; Jungkind, Donald; Williams, Maya; Houng, Huo-Shu

    2016-07-01

    Dengue virus (DENV) and chikungunya virus (CHIKV) are important human pathogens with common transmission vectors and similar clinical presentations. Patient care may be impacted by the misdiagnosis of DENV and CHIKV in areas where both viruses cocirculate. In this study, we have developed and validated a one-step multiplex reverse transcriptase PCR (RT-PCR) to simultaneously detect, quantify, and differentiate between four DENV serotypes (pan-DENV) and chikungunya virus. The assay uses TaqMan technology, employing two forward primers, three reverse primers, and four fluorophore-labeled probes in a single-reaction format. Coextracted and coamplified RNA was used as an internal control (IC), and in vitro-transcribed DENV and CHIKV RNAs were used to generate standard curves for absolute quantification. The diagnostic 95% limits of detection (LOD) within the linear range were 50 and 60 RNA copies/reaction for DENV (serotypes 1 to 4) and CHIKV, respectively. Our assay was able to detect 53 different strains of DENV, representing four serotypes, and six strains of CHIKV. No cross-reactivity was observed with related flaviviruses and alphaviruses, To evaluate diagnostic sensitivity and specificity, 89 clinical samples positive or negative for DENV (serotypes 1 to 4) and CHIKV by the standard virus isolation method were tested in our assay. The multiplex RT-PCR assay showed 95% sensitivity and 100% specificity for DENV and 100% sensitivity and specificity for CHIKV. With an assay turnaround time of less than 2 h, including extraction of RNA, the multiplex quantitative RT-PCR assay provides rapid diagnosis for the differential detection of two clinically indistinguishable diseases, whose geographical occurrence is increasingly overlapping. PMID:27098955

  12. Step-changes in the physical, chemical and biological characteristics of the Gulf of Maine, as documented by the GNATS time series

    USGS Publications Warehouse

    Balch, William M.; Drapeau, D.T.; Bowler, B.C.; Huntington, Thomas G.

    2012-01-01

    We identify step-changes in the physical, chemical and biological characteristics of the Gulf of Maine (GoM) using the Gulf of Maine North Atlantic Time Series (GNATS), a series of oceanographic measurements obtained between September 1998 and December 2010 along a transect in the GoM running from Portland, ME, to Yarmouth, NS. GNATS sampled a period of extremes in precipitation and river discharge (4 of the 8 wettest years of the last century occurred between 2005 and 2010). Coincident with increased precipitation, we observed the following shifts: (1) decreased salinity and density within the surface waters of the western GoM; (2) both reduced temperature and vertical temperature gradients in the upper 50 m; (3) increased colored dissolved organic matter (CDOM) concentrations and particle scattering in the western GoM; (4) increased concentrations of nitrate and phosphate across all but the eastern GoM; (5) increased silicate, particularly in the western GoM, with a sharp increase in the ratio of silicate to dissolved inorganic nitrogen; (6) sharply decreased carbon fixation by phytoplankton; (7) moderately decreased chlorophyll, particulate organic carbon (POC) and particulate inorganic carbon (PIC) in the central GoM and (8) decreased POC- and PIC-specific growth rates. Gulf-wide anomaly analyses suggest that (1) the surface density changes were predominantly driven by temperature, (2) dissolved nutrients, as well as POC/PON, varied in Redfield ratios and (3) anomalies for salinity, density, CDOM, particle backscattering and silicate were significantly correlated with river discharge. Precipitation and river discharge appear to be playing a critical role in controlling the long-term productivity of the Gulf of Maine by supplying CDOM and detrital material, which ultimately competes with phytoplankton for light absorption.

  13. One-step assay for the determination of free protein S antigen in plasma using real-time biospecific interaction analysis.

    PubMed

    Ravanat, C; Wiesel, M L; Schuhler, S; Dambach, J; Amiral, J; Cazenave, J P

    1998-06-01

    Real-time biospecific interaction analysis based on optical detection by surface plasmon resonance was used to develop an accurate one-step method for the direct measurement of free protein S in human plasma. This assay was validated, compared with classical immunological methods and shown to be suitable for the routine clinical diagnosis of protein S deficiency. The method relies on the specific capture of free protein S directly from plasma by a monoclonal antibody (mAb), 34G2, immobilized on a sensor chip surface. A calibration curve was established with serial dilutions of standard plasma (working range 5-50%) and a linear relationship was found to exist between the relative response in resonance units (RU) and the concentration of free protein S expressed as percentage plasma dilution (r = 0.99). The specificity of the assay was confirmed using purified human protein S and polyethylene glycol treated plasma. In addition, it could be demonstrated that no dissociation of C4b-BP-protein S complexes occurred under the chosen experimental conditions. The technique was reproducible with inter-assay, intra-assay and inter-sensor chip variation coefficients of 1.5-5.4%, 2-3.1% and 4.4-4.9%, respectively, as evaluated in two different plasma samples. Since all tests are automatic and long series of analyses can be performed with the same sensor chip, the method was applied to the determination of free protein S antigen in plasma from 20 normal blood donors and 38 thrombophilic patients. Results displayed excellent correlation with those of free protein S enzyme-linked immunosorbent assay (r = 0.99) and rocket immunoelectrophoresis of polyethylene glycol-treated plasma (r = 0.93). PMID:9690804

  14. Whole genome alignment based one-step real-time RT-PCR for universal detection of avian orthoreoviruses of chicken, pheasant and turkey origins.

    PubMed

    Tang, Yi; Lu, Huaguang

    2016-04-01

    Newly emerging avian orthoreovirus (ARV) variants have been continuously detected in Pennsylvania poultry since 2011. In this paper, we report our recent diagnostic assay development of one-step real-time RT-PCR (rRT-PCR) for the rapid and universal detection of all ARVs or reference strains of chicken, pheasant and turkey origins and six σC genotypes of the newly emerging field ARV variants in Pennsylvania (PA) poultry. Primers and probes for the rRT-PCR were designed from the conserved region of the M1 genome segment 5' end based on the whole-genome alignment of various ARV strains, including six field variants or novel strains obtained in PA poultry. The detection limit of the newly developed rRT-PCR for ARV was as low as 10 copies/reaction of viral RNA, and 10(0.50)-10(0.88) tissue culture infectious dose (TCID50)/100 μL of viruses. This new rRT-PCR detected all six σC genotypes from the 66 ARV field variant strains and reference strains tested in this study. There were no cross-reactions with other avian viruses. Reproducibility of the assay was confirmed by intra- and inter-assay tests with variability from 0.12% to 2.19%. Sensitivity and specificity of this new rRT-PCR for ARV were achieved at 100% and 88%, respectively, in comparison with virus isolation as the "gold standard" in testing poultry tissue specimen. PMID:26812128

  15. Effect of arm swing on single-step balance recovery.

    PubMed

    Cheng, Kuangyou B; Huang, Yi-Chang; Kuo, Shih-Yu

    2014-12-01

    Balance recovery techniques are useful not only in preventing falls but also in many sports activities. The step strategy plays an important role especially under intense perturbations. However, relatively little is known about the effect of arm swing on stepping balance recovery although considerable arm motions have been observed. The purpose of this study was to examine how the arms influence kinematic and kinetic characteristics in single-step balance recovery. Twelve young male adults were released from three forward-lean angles and asked to regain balance by taking a single step under arm swing (AS) and arm constrained (AC) conditions. It was found that unconstrained arms had initial forward motion and later upward motion causing increased moment of inertia of the body, which decreased falling angular velocity and allowed more time for stepping. The lengthened total balance time included weight transfer and stepping time, although duration increase in the latter was significant only at the largest lean angle. In contrast, step length, step velocity, and vertical ground reaction forces on the stepping foot were unaffected by arm swing. Future studies are required to investigate optimal movement strategies for the arms to coordinate with other body segments in balance recovery and injury reduction. PMID:25457416

  16. Detection of bovine central nervous system tissues in rendered animal by-products by one-step real-time reverse transcription PCR assay.

    PubMed

    Andrievskaia, Olga; Tangorra, Erin

    2014-12-01

    Contamination of rendered animal byproducts with central nervous system tissues (CNST) from animals with bovine spongiform encephalopathy is considered one of the vehicles of disease transmission. Removal from the animal feed chain of CNST originated from cattle of a specified age category, species-labeling of rendered meat products, and testing of rendered products for bovine CNST are tasks associated with the epidemiological control of bovine spongiform encephalopathy. A single-step TaqMan real-time reverse transcriptase (RRT) PCR assay was developed and evaluated for specific detection of bovine glial fibrillary acidic protein (GFAP) mRNA, a biomarker of bovine CNST, in rendered animal by-products. An internal amplification control, mammalian b -actin mRNA, was coamplified in the duplex RRT-PCR assay to monitor amplification efficiency, normalize amplification signals, and avoid false-negative results. The functionality of the GFAP mRNA RRT-PCR was assessed through analysis of laboratory-generated binary mixtures of bovine central nervous system (CNS) and muscle tissues treated under various thermal settings imitating industrial conditions. The assay was able to detect as low as 0.05 % (wt/wt) bovine brain tissue in binary mixtures heat treated at 110 to 130°C for 20 to 60 min. Further evaluation of the GFAP mRNA RRT-PCR assay involved samples of industrial rendered products of various species origin and composition obtained from commercial sources and rendering plants. Low amounts of bovine GFAP mRNA were detected in several bovine-rendered products, which was in agreement with declared species composition. An accurate estimation of CNS tissue content in industrial-rendered products was complicated due to a wide range of temperature and time settings in rendering protocols. Nevertheless, the GFAP mRNA RRT-PCR assay may be considered for bovine CNS tissue detection in rendered products in combination with other available tools (for example, animal age

  17. Sticky steps inhibit step motions near equilibrium

    NASA Astrophysics Data System (ADS)

    Akutsu, Noriko

    2012-12-01

    Using a Monte Carlo method on a lattice model of a vicinal surface with a point-contact-type step-step attraction, we show that, at low temperature and near equilibrium, there is an inhibition of the motion of macrosteps. This inhibition leads to a pinning of steps without defects, adsorbates, or impurities (self-pinning of steps). We show that this inhibition of the macrostep motion is caused by faceted steps, which are macrosteps that have a smooth side surface. The faceted steps result from discontinuities in the anisotropic surface tension (the surface free energy per area). The discontinuities are brought into the surface tension by the point-contact-type step-step attraction. The point-contact-type step-step attraction also originates “step droplets,” which are locally merged steps, at higher temperatures. We derive an analytic equation of the surface stiffness tensor for the vicinal surface around the (001) surface. Using the surface stiffness tensor, we show that step droplets roughen the vicinal surface. Contrary to what we expected, the step droplets slow down the step velocity due to the diminishment of kinks in the merged steps (smoothing of the merged steps).

  18. Critical evaluation of state evolution laws in rate and state friction: Fitting large velocity steps in simulated fault gouge with time-, slip-, and stress-dependent constitutive laws

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Pathikrit; Rubin, Allan M.; Bayart, Elsa; Savage, Heather M.; Marone, Chris

    2015-09-01

    The variations in the response of different state evolution laws to large velocity increases can dramatically alter the style of earthquake nucleation in numerical simulations. But most velocity step friction experiments do not drive the sliding surface far enough above steady state to probe this relevant portion of the parameter space. We try to address this by fitting 1-3 orders of magnitude velocity step data on simulated gouge using the most widely used state evolution laws. We consider the Dieterich (Aging) and Ruina (Slip) formulations along with a stress-dependent state evolution law recently proposed by Nagata et al. (2012). Our inversions confirm the results from smaller velocity step tests that the Aging law cannot explain the observed response and that the Slip law produces much better fits to the data. The stress-dependent Nagata law can produce fits identical to, and sometimes slightly better than, those produced by the Slip law using a sufficiently large value of an additional free parameter c that controls the stress dependence of state evolution. A Monte Carlo search of the parameter space confirms analytical results that velocity step data that are well represented by the Slip law can only impose a lower bound on acceptable values of c and that this lower bound increases with the size of the velocity step being fit. We find that our 1-3 orders of magnitude velocity steps on synthetic gouge impose this lower bound on c to be 10-100, significantly larger than the value of 2 obtained by Nagata et al. (2012) based on experiments on initially bare rock surfaces with generally smaller departures from steady state.

  19. One-step multiplex real time RT-PCR for the detection of bovine respiratory syncytial virus, bovine herpesvirus 1 and bovine parainfluenza virus 3

    PubMed Central

    2012-01-01

    Background Detection of respiratory viruses in veterinary species has traditionally relied on virus detection by isolation or immunofluorescence and/or detection of circulating antibody using ELISA or serum neutralising antibody tests. Multiplex real time PCR is increasingly used to diagnose respiratory viruses in humans and has proved to be superior to traditional methods. Bovine respiratory disease (BRD) is one of the most common causes of morbidity and mortality in housed cattle and virus infections can play a major role. We describe here a one step multiplex reverse transcriptase quantitative polymerase chain reaction (mRT-qPCR) to detect the viruses commonly implicated in BRD. Results A mRT-qPCR assay was developed and optimised for the simultaneous detection of bovine respiratory syncytial virus (BRSV), bovine herpes virus type 1 (BoHV-1) and bovine parainfluenza virus type 3 (BPI3 i & ii) nucleic acids in clinical samples from cattle. The assay targets the highly conserved glycoprotein B gene of BoHV-1, nucleocapsid gene of BRSV and nucleoprotein gene of BPI3. This mRT-qPCR assay was assessed for sensitivity, specificity and repeatability using in vitro transcribed RNA and recent field isolates. For clinical validation, 541 samples from clinically affected animals were tested and mRT-qPCR result compared to those obtained by conventional testing using virus isolation (VI) and/or indirect fluorescent antibody test (IFAT). Conclusions The mRT-qPCR assay was rapid, highly repeatable, specific and had a sensitivity of 97% in detecting 102 copies of BRSV, BoHV-1 and BPI3 i & ii. This is the first mRT-qPCR developed to detect the three primary viral agents of BRD and the first multiplex designed using locked nucleic acid (LNA), minor groove binding (MGB) and TaqMan probes in one reaction mix. This test was more sensitive than both VI and IFAT and can replace the aforesaid methods for virus detection during outbreaks of BRD. PMID:22455597

  20. Religiosity, Emotional Responses, Perceived Pressure, and Start-Time Compliance among Individuals Who Are Court Mandated to Attend 12 Step Groups

    ERIC Educational Resources Information Center

    Tyce, Sue L.

    2009-01-01

    Research findings demonstrate that effective drug treatment often involves AA's 12 Step program. However, AA's religiosity can be seen as an important, perhaps significant emotional stimulus that either hinders or complicates attendance compliance. This study examined the individual's level of religiosity as a predictor of emotional responses,…

  1. Medical Preparedness Allowable Use Act

    THOMAS, 113th Congress

    Rep. Bilirakis, Gus M. [R-FL-12

    2013-04-26

    02/04/2014 Received in the Senate and Read twice and referred to the Committee on Homeland Security and Governmental Affairs. (All Actions) Tracker: This bill has the status Passed HouseHere are the steps for Status of Legislation:

  2. Medical Preparedness Allowable Use Act

    THOMAS, 112th Congress

    Rep. Bilirakis, Gus M. [R-FL-9

    2012-06-21

    11/28/2012 Received in the Senate and Read twice and referred to the Committee on Homeland Security and Governmental Affairs. (All Actions) Tracker: This bill has the status Passed HouseHere are the steps for Status of Legislation:

  3. Micromachine Wedge Stepping Motor

    SciTech Connect

    Allen, J.J.; Schriner, H.K.

    1998-11-04

    A wedge stepping motor, which will index a mechanism, has been designed and fabricated in the surface rnicromachine SUMMiT process. This device has demonstrated the ability to index one gear tooth at a time with speeds up to 205 teeth/see. The wedge stepper motor has the following features, whi:h will be useful in a number of applications. o The ability to precisely position mechanical components. . Simple pulse signals can be used for operation. o Only 2 drive signals are requixed for operation. o Torque and precision capabilities increase with device size . The device to be indexed is restrained at all times by the wedge shaped tooth that is used for actuation. This paper will discuss the theory of operation and desi=m of the wedge stepping motor. The fabrication and testing of I he device will also be presented.

  4. Stepped sinewave inverter

    NASA Astrophysics Data System (ADS)

    Appelbaum, J.; Gabbay, D.

    1984-11-01

    A stepped sinewave dc/ac inverter was analyzed for an inductive load with respect to load current and voltage, harmonics, power factor, and efficiency. This special inverter of high efficiency and low harmonic content is constructed by synthesizing the sinusoidal output by discrete voltage sources, such as storage batteries, solar cell, etc., with electronic switching of the sources at specific time intervals. The switching times are determined for the condition of minimum distortion of the synthesized wave. A 50 W inverter was built and tested to demonstrate this approach.

  5. Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy

    PubMed Central

    Lórenz-Fonfría, Víctor A.; Heberle, Joachim

    2014-01-01

    Monitoring the dynamics of protonation and protein backbone conformation changes during the function of a protein is an essential step towards understanding its mechanism. Protonation and conformational changes affect the vibration pattern of amino acid side chains and of the peptide bond, respectively, both of which can be probed by infrared (IR) difference spectroscopy. For proteins whose function can be repetitively and reproducibly triggered by light, it is possible to obtain infrared difference spectra with (sub)microsecond resolution over a broad spectral range using the step-scan Fourier transform infrared technique. With ~102-103 repetitions of the photoreaction, the minimum number to complete a scan at reasonable spectral resolution and bandwidth, the noise level in the absorption difference spectra can be as low as ~10-4, sufficient to follow the kinetics of protonation changes from a single amino acid. Lower noise levels can be accomplished by more data averaging and/or mathematical processing. The amount of protein required for optimal results is between 5-100 µg, depending on the sampling technique used. Regarding additional requirements, the protein needs to be first concentrated in a low ionic strength buffer and then dried to form a film. The protein film is hydrated prior to the experiment, either with little droplets of water or under controlled atmospheric humidity. The attained hydration level (g of water / g of protein) is gauged from an IR absorption spectrum. To showcase the technique, we studied the photocycle of the light-driven proton-pump bacteriorhodopsin in its native purple membrane environment, and of the light-gated ion channel channelrhodopsin-2 solubilized in detergent. PMID:24998200

  6. New quick method for isolating RNA from laser captured cells stained by immunofluorescent immunohistochemistry; RNA suitable for direct use in fluorogenic TaqMan one-step real-time RT-PCR

    PubMed Central

    Kawashima, Kenji; Lucero, Ginger; Ackermann, Mark R.

    2005-01-01

    We describe a new approach for reliably isolating one-step real-time quantitative RT-PCR-quality RNA from laser captured cells retrieved from frozen sections previously subjected to immunofluorescent immunohistochemistry (IF-IHC) and subsequently subjected to fluorogenic one-step real-time RT-PCR analysis without the need for costly, time-consuming linear amplification. One cell’s worth of RNA can now be interrogated with confidence. This approach represents an amalgam of technologies already offered commercially by Applied Biosystems, Arcturus and Invitrogen. It is the primary focus of this communication to expose the details and execution of an important new LCM RNA isolation technique, but also provide a detailed account of the IF-IHC procedure preceding RNA isolation, and provide information regarding our approach to fluorogenic one-step real-time RT-PCR in general. Experimental results shown here are meant to supplement the primary aim and are not intended to represent a complete scientific study. It is important to mention, that since LCM-RT-PCR is still far less expensive than micro-array analysis, we feel this approach to isolating RNA from LCM samples will be of continuing use to many researchers with limited budgets in the years ahead. PMID:16136226

  7. 38 CFR 21.4145 - Work-study allowance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Work-study allowance. 21...; Educational Assistance Allowance § 21.4145 Work-study allowance. (a) Eligibility. (1) A veteran or reservist... rate of three-quarter time or full time is eligible to receive a work-study allowance. (2) An...

  8. 38 CFR 21.4145 - Work-study allowance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2012-07-01 2012-07-01 false Work-study allowance. 21...; Educational Assistance Allowance § 21.4145 Work-study allowance. (a) Eligibility. (1) A veteran or reservist... rate of three-quarter time or full time is eligible to receive a work-study allowance. (2) An...

  9. 38 CFR 21.4145 - Work-study allowance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2013-07-01 2013-07-01 false Work-study allowance. 21...; Educational Assistance Allowance § 21.4145 Work-study allowance. (a) Eligibility. (1) A veteran or reservist... rate of three-quarter time or full time is eligible to receive a work-study allowance. (2) An...

  10. 38 CFR 21.4145 - Work-study allowance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2011-07-01 2011-07-01 false Work-study allowance. 21...; Educational Assistance Allowance § 21.4145 Work-study allowance. (a) Eligibility. (1) A veteran or reservist... rate of three-quarter time or full time is eligible to receive a work-study allowance. (2) An...

  11. "It Might Actually Work This Time": Benefits and Barriers to Adapted 12-Step Facilitation Therapy and Mutual-Help Group Attendance From the Perspective of Dually Diagnosed Individuals.

    PubMed

    Hagler, Kylee J; Rice, Samara L; Muñoz, Rosa E; Salvador, Julie G; Forcehimes, Alyssa A; Bogenschutz, Michael P

    2015-01-01

    Most U.S. healthcare professionals encourage mutual-help group involvement as an adjunct to treatment or aftercare for individuals with substance use disorders, yet there are multiple challenges in engaging in these community groups. Dually diagnosed individuals (DDIs) may face additional challenges in affiliating with mutual-help groups. Twelve-step facilitation for DDIs (TSF-DD), a manualized treatment to facilitate mutual-help group involvement, was developed to help patients engage in Double Trouble in Recovery (DTR), a mutual-help group tailored to DDIs. Given the promising role that TSF-DD and DTR may have for increasing abstinence while managing psychiatric symptoms, the aim of the current study was to systematically examine reasons for TSF-DD and DTR attendance from the perspective of DDIs using focus group data. Participants were a subset (n = 15) of individuals diagnosed with an alcohol use disorder as well as a major depressive, bipolar, or psychotic disorder who participated in a parent study testing the efficacy of TSF-DD for increasing mutual-help group involvement and reducing alcohol use. Analyses of focus group data revealed that participants construed DTR and TSF-DD as helpful tools in the understanding and management of their disorders. Relative to other mutual-help groups in which participants reported feeling ostracized because of their dual diagnoses, participants reported that it was beneficial to learn about dual disorders in a safe and accepting environment. Participants also expressed aspects that they disliked. Results from this study yield helpful empirical recommendations to healthcare professionals seeking to increase DDIs' participation in DTR or other mutual-help groups. PMID:26340570

  12. Development of a One-Step Immunocapture Real-Time TaqMan RT-PCR Assay for the Broad Spectrum Detection of Pepino Mosaic Virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A Real-time reverse transcription-polymerase chain reaction (RT-PCR) was developed for efficient detection of genetically diverse PepMV isolates. The novel detection system was designed to use a duo-primer system targeting the conserved region in the triple gene block 2 (TGB2) gene with a single co...

  13. Tough Choices or Tough Times: Bolder Steps for Education Philanthropy? Notes and Resources from the GFE Foundation Leaders Institute (Tamaya, New Mexico, October 19, 2007)

    ERIC Educational Resources Information Center

    Mackinnon, Anne

    2007-01-01

    In late 2006, the National Center on Education and the Economy released "Tough Choices or Tough Times: The Report of the New Commission on the Skills of the American Workforce." With compelling language, the report updated and sharpened the findings of the center's influential 1990 report, "America's Choice: High Skills or Low Wages," which called…

  14. Behavioural Repertoire of Working Donkeys and Consistency of Behaviour over Time, as a Preliminary Step towards Identifying Pain-Related Behaviours

    PubMed Central

    Regan, Fran H.; Hockenhull, Jo; Pritchard, Joy C.; Waterman-Pearson, Avril E.; Whay, Helen R.

    2014-01-01

    Background The donkey has a reputation for stoicism and its behavioural repertoire in clinical contexts is under-reported. Lack of understanding of the norms of donkey behaviour and how it may vary over time can compromise use of behavioural measures as indicators of pain or emotional state. The objective of this study was to find out whether the behaviour of working donkeys was influenced by gender, the time of day or differed between days with a view to assessing how robust these measures are for inclusion in a working donkey ethogram. Methodology/Principal Findings Frequency and consistency of postural and event behaviours were measured in 21 adult working donkeys (12 females; 9 males). Instantaneous (scan) and focal sampling were used to measure maintenance, lying, ingestive and investigative behaviours at hourly intervals for ten sessions on each of two consecutive days. High head carriage and biting were seen more frequently in male donkeys than females (P<0.001). Level head carriage, licking/chewing and head-shaking were observed more frequently in female donkeys (P<0.001). Tail position, ear orientation, foot stamping, rolling/lying and head-shaking behaviours were affected by time of day (P<0.001). However, only two variations in ear orientation were found to be significantly different over the two days of observations (P<0.001). Tail swishing, head shaking, foot stamping, and ears held sideways and downwards were significantly correlated (P<0.001) and are assumed to be behaviours to discourage flies. Conclusions/Significance All donkeys expressed an extensive behavioural repertoire, although some differences in behaviour were evident between genders. While most behaviours were consistent over time, some behaviours were influenced by time of day. Few behaviours differed between the two test days. The findings can be used to inform the development of a robust, evidence-based ethogram for working donkeys. PMID:25076209

  15. Vietnam recommended dietary allowances 2007.

    PubMed

    Khan, Nguyen Cong; Hoan, Pham Van

    2008-01-01

    It has been well acknowledged that Vietnam is undergoing a nutrition transition. With a rapid change in the country's reform and economic growth, food supply at the macronutrient level has improved. Changes of the Vietnamese diet include significantly more foods of animal origin, and an increase of fat/oils, and ripe fruits. Consequently, nutritional problems in Vietnam now include not only malnutrition but also overweight/obesity, metabolic syndrome and other chronic diseases related to nutrition and lifestyles. The recognition of these shifts, which is also associated with morbidity and mortality, was a major factor in the need to review and update the Recommended Dietary Allowances (RDA) for the Vietnamese population. This revised RDA established an important science-based tool for evaluation of nutrition adequacy, for teaching, and for scientific communications within Vietnam. It is expected that the 2007 Vietnam RDA and its conversion to food-based dietary guidelines will facilitate education to the public, as well as the policy implementation of programs for prevention of non-communicable chronic diseases and addressing the double burden of both under and over nutrition. PMID:18460440

  16. Simultaneous detection of influenza viruses A, B, and swine origin influenza A using multiplex one-step real-time RT-PCR assay.

    PubMed

    Monavari, S H R; Mollaie, H R; Fazlalipour, M

    2014-01-01

    Every year, seasonal epidemics of influenza viruses are causing considerable morbidity and mortality worldwide. Also infrequent novel and rearranged strains of influenza viruses have caused quick, acute universal pandemics resulting in millions of mortalities. The usage of efficient and accurate detection is superior for infection control, effective treatment, and epidemiological supervision. Therefore, evaluation of useful real-time PCR molecular tests for the detection of pandemic viruses is important before the next wave of the pandemic. A novel quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR) assay with specific primers was used successfully for detection and monitoring of the influenza A, B, and swine influenza. The newly designed primers target highly conserved regions in influenza viruses. Our qRT-PCR assay is highly specific for detecting influenza A, B, and swine influenza viruses. The cutoff CT value was determined <38 for domestic human diagnostic test, under conditions of FDA emergency, and the reaction efficiency of the InfA, swInfA, and InfB assays were thereby estimated to be 97.9 % (R2 = 0.998), 98.3 % (R2 = 0.986), and 99.5 % (R2 = 0.995), respectively. Interestingly, based on our finding, there is no cross reactivity of detecting other viruses. PMID:24142356

  17. One Step Quantum Key Distribution Based on EPR Entanglement.

    PubMed

    Li, Jian; Li, Na; Li, Lei-Lei; Wang, Tao

    2016-01-01

    A novel quantum key distribution protocol is presented, based on entanglement and dense coding and allowing asymptotically secure key distribution. Considering the storage time limit of quantum bits, a grouping quantum key distribution protocol is proposed, which overcomes the vulnerability of first protocol and improves the maneuverability. Moreover, a security analysis is given and a simple type of eavesdropper's attack would introduce at least an error rate of 46.875%. Compared with the "Ping-pong" protocol involving two steps, the proposed protocol does not need to store the qubit and only involves one step. PMID:27357865

  18. One Step Quantum Key Distribution Based on EPR Entanglement

    PubMed Central

    Li, Jian; Li, Na; Li, Lei-Lei; Wang, Tao

    2016-01-01

    A novel quantum key distribution protocol is presented, based on entanglement and dense coding and allowing asymptotically secure key distribution. Considering the storage time limit of quantum bits, a grouping quantum key distribution protocol is proposed, which overcomes the vulnerability of first protocol and improves the maneuverability. Moreover, a security analysis is given and a simple type of eavesdropper’s attack would introduce at least an error rate of 46.875%. Compared with the “Ping-pong” protocol involving two steps, the proposed protocol does not need to store the qubit and only involves one step. PMID:27357865

  19. Effect of reaction temperature and time during two-step selenization and sulfurization of Se-Coated CuGa/In precursors

    NASA Astrophysics Data System (ADS)

    Koo, Jaseok; Kwon, Sunmo; Roh, Yong-Suk; Lee, Seok-Jin; Jung, Ki-Young; Shafarman, William N.; Park, Ji-Hyeon; Kim, Do Hoon; Myoung, Jae-Min; Kim, Woo Kyoung

    2016-07-01

    In this work, the selenization of Mo/CuGa/In/Se (Se layer thickness: 1 μm) precursors followed by sulfurization was investigated. Particular emphasis was placed on the effect of the variation of the selenization temperature and sulfurization time on the morphology and compositional depth profiles of the resulting Cu(InGa)(SeS)2 (CIGSS) absorber; in addition, the current-voltage characteristics of the corresponding devices were investigated. The selenization of the precursors was achieved by using a tube-type rapid thermal annealing system at various temperatures (500, 550, and 600 °C). Post-sulfurization of Cu(InGa)Se2 (CIGS) was performed in the same system by flowing H2S/He gas at 600 °C for different periods of time (5, 10, and 15 min). Post-sulfurization can improve the open-circuit voltage of a solar cell by attracting Ga toward the surface region of the light absorber and incorporating S into the absorber to yield quinary CIGSS compounds. In addition, the voids at the Mo/CIGS interface, produced during the selenization of the CuGa/In/Se precursors, were effectively removed after post-sulfurization. Among the process conditions explored in this study, the selenization of Mo/CuGa/In/Se at 550 °C for 7 min followed by sulfurization at 600 °C for 10 min produced the device with the best performance, providing also good material properties in terms of morphology and compositional homogeneity. [Figure not available: see fulltext.

  20. Transformation of serum-susceptible Escherichia coli O111 with p16Slux plasmid to allow for real-time monitoring of complement-based inactivation of bacterial growth in bovine milk.

    PubMed

    Maye, S; Stanton, C; Fitzgerald, G F; Kelly, P M

    2016-01-01

    Complement activity has only recently been characterized in raw bovine milk. However, the activity of this component of the innate immune system was found to diminish as milk was subjected to heat or partitioning during cream separation. Detection of complement in milk relies on a bactericidal assay. This assay exploits the specific growth susceptibility of Escherichia coli O111 to the presence of complement. Practical application of the assay was demonstrated when a reduction in complement activity was recorded in the case of pasteurized and reduced-fat milks. This presented an opportunity to improve the functionality of the bactericidal assay by incorporating bioluminescence capability into the target organism. Following some adaptation, the strain was transformed by correctly integrating the p16Slux plasmid. Growth properties of the transformed strain of E. coli O111 were unaffected by the modification. The efficacy of the strain adaptation was correlated using the LINEST function analysis [r=0.966; standard error of prediction (SEy)=0.957] bioluminescence with that of bactericidal assay total plate counts within the range of 7.5 to 9.2 log cfu/mL using a combination of raw and processed milk samples. Importantly, the transformed E. coli O111 p16Slux strain could be identified in milk and broth samples using bioluminescence measurement, thus enabling the bactericidal assay-viability test to be monitored in real time throughout incubation. PMID:26585477

  1. A fluorescein-labeled AmpC β-lactamase allows rapid characterization of β-lactamase inhibitors by real-time fluorescence monitoring of the β-lactamase-inhibitor interactions.

    PubMed

    Tsang, Man-Wah; Chan, Pak-Ho; Liu, Sze-Yan; Wong, Kwok-Yin; Leung, Yun-Chung

    2016-02-01

    Rapid emergence of class C β-lactamases has urged an immediate need for developing class C β-lactamase specific inhibitors for effective clinical treatment. To facilitate the development of effective class C β-lactamase inhibitors, we propose a new approach for a rapid analysis of the interaction of AmpC β-lactamase and its inhibitors using our recently developed V211Cf fluorescent β-lactamase biosensor during drug screening. Since the fluorescein of V211Cf can report the local environment change in the active site of AmpC β-lactamase, fluorescence responses of V211Cf toward its substrates/inhibitors can provide real-time traces of the dynamic change of the interaction of the β-lactamase with its substrates/inhibitors. In this study, we found that V211Cf displayed distinct fluorescence signal patterns toward different kinds of inhibitors (including clavulanic acid, sulbactam, tazobactam and 2-thiopheneboronic acid) due to the differences in their interactions with β-lactamase. V211Cf not only enables a high throughput screening for inhibitors but can also provide a rapid preliminary indication on the inhibitor's potency and stability to β-lactamase's hydrolytic action as well as how the inhibitors interact with the target enzyme, thereby speeding up the drug discovery and development cycle of class C β-lactamase inhibitors. PMID:26250526

  2. The Satellite Test of the Equivalence Principle (STEP)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    STEP will carry concentric test masses to Earth orbit to test a fundamental assumption underlying Einstein's theory of general relativity: that gravitational mass is equivalent to inertial mass. STEP is a 21st-century version of the test that Galileo is said to have performed by dropping a carnon ball and a musket ball simultaneously from the top of the Leaning Tower of Pisa to compare their accelerations. During the STEP experiment, four pairs of test masses will be falling around the Earth, and their accelerations will be measured by superconducting quantum interference devices (SQUIDS). The extended time sensitivity of the instruments will allow the measurements to be a million times more accurate than those made in modern ground-based tests.

  3. 40 CFR 60.4160 - Submission of Hg allowance transfers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Submission of Hg allowance transfers... Times for Coal-Fired Electric Steam Generating Units Hg Allowance Transfers § 60.4160 Submission of Hg allowance transfers. An Hg authorized account representative seeking recordation of a Hg allowance...

  4. Analogue step-by-step DC component eliminator for 24-hour PPG signal monitoring.

    PubMed

    Pilt, Kristjan; Meigas, Kalju; Lass, Jaanus; Rosmann, Mart; Kaik, Jüri

    2007-01-01

    For applications where PPG signal AC component needs to be measured without disturbances in its shape and recorded digitally with high digitalization accuracy, the step-by-step DC component eliminator is developed. This paper describes step-by-step DC component eliminator, which is utilized with analogue comparator and operational amplifier. It allows to record PPG signal without disturbances in its shape in 24-hours PPG signal monitoring system. The experiments with PPG signal have been carried out. PMID:18002130

  5. Possible recovery or unavoidable fall? A model to predict the one step balance recovery threshold and its stepping characteristics.

    PubMed

    Vallée, Pascal; Tisserand, Romain; Robert, Thomas

    2015-11-01

    In order to prevent fall related injuries and their consequences, one needs to be able to predict the outcome of a given balance perturbation: a possible Balance Recovery (BR) or an unavoidable fall? Given that results from the existing experimental studies are difficult to compare and to generalize, we propose to address this question with a numerical tool. Built on existing concepts from the biomechanics and robotics literature, it includes the optimal use of BR reactions and particularly the possibility to perform a recovery step. It allows estimating 1) the possibility to recover a steady balance from a given initial state or perturbation using at most one recovery step; 2) the set of recovery steps leading to a BR. Using standard sets of parameters for young and elderly population, we assessed this model's predictions against experimental data from the literature in the anterior direction. Two classical representations of the human body (inverted pendulum (IP) vs. linear inverted pendulum (LIP)) were also compared. The results showed that the model correctly predicted the possibility to recover using a single protective step (1-Step BR threshold) and the characteristics (step length and time) of the protective step for both the young and the elderly. This tool has a real potential in the field of fall prevention to detect risky situation. It could also be used to get insights into the neuromuscular mechanisms involved in the BR process. PMID:26602371

  6. Steps in Behavior Modividation.

    ERIC Educational Resources Information Center

    Straughan, James H.; And Others

    James H. Straughan lists five steps for modifying target behavior and four steps for working with teachers using behavior modification. Grant Martin and Harold Kunzelmann then outline an instructional program for pinpointing and recording classroom behaviors. (JD)

  7. Comment on 'Shang S. 2012. Calculating actual crop evapotranspiration under soil water stress conditions with appropriate numerical methods and time step. Hydrological Processes 26: 3338-3343. DOI: 10.1002/hyp.8405'

    NASA Technical Reports Server (NTRS)

    Yatheendradas, Soni; Narapusetty, Balachandrudu; Peters-Lidard, Christa; Funk, Christopher; Verdin, James

    2014-01-01

    A previous study analyzed errors in the numerical calculation of actual crop evapotranspiration (ET(sub a)) under soil water stress. Assuming no irrigation or precipitation, it constructed equations for ET(sub a) over limited soil-water ranges in a root zone drying out due to evapotranspiration. It then used a single crop-soil composite to provide recommendations about the appropriate usage of numerical methods under different values of the time step and the maximum crop evapotranspiration (ET(sub c)). This comment reformulates those ET(sub a) equations for applicability over the full range of soil water values, revealing a dependence of the relative error in numerical ET(sub a) on the initial soil water that was not seen in the previous study. It is shown that the recommendations based on a single crop-soil composite can be invalid for other crop-soil composites. Finally, a consideration of the numerical error in the time-cumulative value of ET(sub a) is discussed besides the existing consideration of that error over individual time steps as done in the previous study. This cumulative ET(sub a) is more relevant to the final crop yield.

  8. Stair-stepped Mound

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-429, 22 July 2003

    This April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a stair-stepped mound of sedimentary rock (right of center) on the floor of a large impact crater in western Arabia Terra near 11.0oN, 4.4oW. Sedimentary rock outcrops are common in the craters of this region. The repeated thickness and uniformity of the layers that make up this mound suggest that their depositional environment was one in which cyclic or episodic events occurred over some period of time. The sediments might have been deposited in a lake, or they may have settled directly out of the atmosphere. Most of the layered material was later eroded away, leaving this circular mound and the other nearby mesas and knobs. The image is illuminated by sunlight from the lower left.

  9. Stepped Hydraulic Geometry in Stepped Channels

    NASA Astrophysics Data System (ADS)

    Comiti, F.; Cadol, D. D.; Wohl, E.

    2007-12-01

    Steep mountain streams typically present a stepped longitudinal profile. Such stepped channels feature tumbling flow, where hydraulic jumps represent an important source of channel roughness (spill resistance). However, the extent to which spill resistance persists up to high flows has not been ascertained yet, such that a faster, skimming flow has been envisaged to begin at those conditions. In order to analyze the relationship between flow resistance and bed morphology, a mobile bed physical model was developed at Colorado State University (Fort Collins, USA). An 8 m-long, 0.6 m-wide flume tilted at a constant 14% slope was used, testing 2 grain-size mixtures differing only for the largest fraction. Experiments were conducted under clear water conditions. Reach-averaged flow velocity was measured using salt tracers, bed morphology and flow depth by a point gage, and surface grain size using commercial image-analysis software. Starting from an initial plane bed, progressively higher flow rates were used to create different bed structures. After each bed morphology was stable with its forming discharge, lower-than-forming flows were run to build a hydraulic geometry curve. Results show that even though equilibrium slopes ranged from 8.5% to 14%, the reach-averaged flow was always sub-critical. Steps formed through a variety of mechanisms, with immobile clasts playing a dominant role by causing local scouring and/or trapping moving smaller particles. Overall, step height, step pool steepness, relative pool area and volume increased with discharge up to the threshold when the bed approached fully- mobilized conditions. For bed morphologies surpassing a minimum profile roughness, a stepped velocity- discharge relationship is evident, with sharp rises in velocity correlated with the disappearance of rollers in pools at flows approaching the formative discharge for each morphology. Flow resistance exhibits an opposite pattern, with drops in resistance being a function

  10. One Step to Learning.

    ERIC Educational Resources Information Center

    Thornton, Carol A.; And Others

    1980-01-01

    Described are activities and games incorporating a technique of "one step" which is used with children with learning difficulties. The purpose of "one step" is twofold, to minimize difficulties with typical trouble spots and to keep the step size of the instruction small. (Author/TG)

  11. A Step Circuit Program.

    ERIC Educational Resources Information Center

    Herman, Susan

    1995-01-01

    Aerobics instructors can use step aerobics to motivate students. One creative method is to add the step to the circuit workout. By incorporating the step, aerobic instructors can accommodate various fitness levels. The article explains necessary equipment and procedures, describing sample stations for cardiorespiratory fitness, muscular strength,…

  12. STEPS: Moving from Welfare to Work.

    ERIC Educational Resources Information Center

    Vail, Ann; Cummings, Merrilyn; Kratzer, Connie; Galindo, Vickie

    Cooperative extension service faculty at New Mexico State University started the Steps to Employment and Personal Success (STEPS) program to help Temporary Assistance for Needy Families (TANF) clients qualify for and maintain full-time employment and strengthen their families for long-term success. Clients are referred to STEPS by New Mexico…

  13. 40 CFR 265.113 - Closure; time allowed for closure.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... includes an amended waste analysis plan, ground-water monitoring and response program, human exposure... and that an extension will not pose a threat to human health and the environment. (4) If a...

  14. 40 CFR 264.113 - Closure; time allowed for closure.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... permit requirements; and (2) The request to modify the permit includes an amended waste analysis plan... longer than the allotted period to complete and that an extension will not pose a threat to human...

  15. 40 CFR 264.113 - Closure; time allowed for closure.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... permit requirements; and (2) The request to modify the permit includes an amended waste analysis plan... longer than the allotted period to complete and that an extension will not pose a threat to human...

  16. 40 CFR 265.113 - Closure; time allowed for closure.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... includes an amended waste analysis plan, ground-water monitoring and response program, human exposure... and that an extension will not pose a threat to human health and the environment. (4) If a...

  17. Ionic liquid-based one-step micellar extraction of multiclass polar compounds from hawthorn fruits by ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry.

    PubMed

    Hu, Shuai-Shuai; Yi, Ling; Li, Xing-Ying; Cao, Jun; Ye, Li-Hong; Cao, Wan; Da, Jian-Hua; Dai, Han-Bin; Liu, Xiao-Juan

    2014-06-11

    An ionic liquid (IL)-based one-step micellar extraction procedure was developed for the extraction of multiclass polar analytes (protocatechuic acid, chlorogenic acid, epicatechin, hyperoside, isoquercitrin, quercetin) from hawthorn fruits and their determination using ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UHPLC-Q-TOF/MS). Compared to conventional organic solvent extractions, this newly proposed method was much easier, more sensitive, environmentally friendly, and effective as well. Several important parameters influencing the micellar extraction efficiency are discussed, such as selection of ILs, surfactant concentration, and extraction time. Under the optimal conditions, good linearity was achieved for each analyte with correlation coefficients (r(2)) ranging from 0.9934 to 0.9999, and the recovery values ranged from 89.3 to 106% with relative standard deviations lower than 5.5%. Results suggest that the IL-based one-step micellar extraction could be an alternative and promising means in future food analysis. PMID:24845828

  18. Assignment of IR bands of isolated and protein-bound Peridinin in its fundamental and triplet state by static FTIR, time-resolved step-scan FTIR and DFT calculations

    NASA Astrophysics Data System (ADS)

    Mezzetti, Alberto; Kish, Elizabeth; Robert, Bruno; Spezia, Riccardo

    2015-06-01

    The vibrational properties of Peridinin in its fundamental state and in the excited triplet state have been investigated by DFT calculations and static and time-resolved FTIR spectroscopy. The infrared spectrum of Peridinin in its fundamental state has been explored in the whole 2000-600 cm-1 range, and interpreted in term of molecular vibrations. In particular, new infrared bands have been identified and assigned to specific molecular vibrations. 3Peridinin molecular vibrations have also been investigated by DFT calculations. In addition, putative IR bands belonging to Peridinin and 3Peridinin have been identified in the step-scan FTIR difference spectrum of the Peridinin-Chlorophyll a-Protein from Amphidinium carterae, where light induce formation of a triplet state localized on one or more Peridinins. The exact nature of the triplet state formed in Peridinin-Chlorophyll a-Protein from dinoflagellates, in particular the possible involvement in this triplet state of 3Chlorophyll a, has been largely debated in the last few years (see Carbonera et al., 2014 [3]); time-resolved differential FTIR experiments have played a key role in this debate. Identification of IR marker bands for the main molecule (Peridinin) implicated in this photophysical process is therefore particularly important and makes this study a significant step towards the full understanding of Peridinin-Chlorophyll-a-Proteins photophysics.

  19. A Step or Two Back in Time.

    ERIC Educational Resources Information Center

    Thomson, Peggy

    1979-01-01

    Describes the National Park Service's Environmental Living Program for elementary school children in the San Francisco Bay Area, where teachers, parents, and children stay overnight in a historic fort and schooner, experience living in a past age, use candles and oil stoves, and engage in mock military and shipboard activities. (MF)

  20. Numerical Integration: One Step at a Time

    ERIC Educational Resources Information Center

    Yang, Yajun; Gordon, Sheldon P.

    2016-01-01

    This article looks at the effects that adding a single extra subdivision has on the level of accuracy of some common numerical integration routines. Instead of automatically doubling the number of subdivisions for a numerical integration rule, we investigate what happens with a systematic method of judiciously selecting one extra subdivision for…

  1. Brief Azacytidine Step Allows The Conversion of Suspension Human Fibroblasts into Neural Progenitor-Like Cells

    PubMed Central

    Mirakhori, Fahimeh; Zeynali, Bahman; Kiani, Sahar; Baharvand, Hossein

    2015-01-01

    In recent years transdifferentiation technology has enabled direct conversion of human fibroblasts to become a valuable, abundant and accessible cell source for patient-specific induced cell generation in biomedical research. The majority of transdifferentiation approaches rely upon viral gene delivery which due to random integration with the host genome can cause genome instability and tumorigenesis upon transplantation. Here, we provide a simple way to induce neural progenitor-like cells from human fibroblasts without genetic manipulation by changing physicochemical culture properties from monolayer culture into a suspension in the presence of a chemical DNA methyltransferase inhibitor agent, Azacytidine. We have demonstrated the expression of neural progenitor-like markers, morphology and the ability to spontaneously differentiate into neural-like cells. This approach is simple, inexpensive, lacks genetic manipulation and could be a foundation for future chemical neural transdifferentiation and a safe induction of neural progenitor cells from human fibroblasts for clinical applications. PMID:25870845

  2. Operation of the MPD thruster with stepped current input

    SciTech Connect

    Barnett, J.W.

    1985-01-01

    A magnetoplasmadynamic (MPD) thruster was operated with stepped current pulses in order to investigate the sensitivity of its operation to non-constant current input. The thruster terminal voltage is found to lag the current increment by increasing times as the highest level of the stepped current pulse nears the onset condition. Magnetic field transients corresponding to the terminal voltage transients appear in the thruster exhaust. The magnetic field and terminal voltage equilibrations can be interpreted in terms of magnetic diffusion and convection processes. The time constants of equilibration are largest in the exhaust portion of the discharge, where the discharge scale length is much larger than in the thrust chamber. The transient thrust following a current step up is estimated to be below the quasi steady thrust, while the transient thrust following a current step down is estimated to be above the quasi steady thrust. When the thruster is powered with a current step up whose upper plateau is near the onset conditions, the prolonged discharge transient allows a diagnostic look at the development on the onset condition. Electric field probing for different propellant injection geometries suggest that the larger terminal voltages associated with operation near onset may result from two distinct processes: an increasing anode fall, probably caused by insufficient propellant near the anode, or the back emf of the plasma flow.

  3. 40 CFR 60.4153 - Recordation of Hg allowance allocations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Recordation of Hg allowance allocations... Times for Coal-Fired Electric Steam Generating Units Hg Allowance Tracking System § 60.4153 Recordation of Hg allowance allocations. (a) By December 1, 2006, the Administrator will record in the Hg...

  4. 5 CFR 591.305 - Allowance rates.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 1 2011-01-01 2011-01-01 false Allowance rates. 591.305 Section 591.305 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS ALLOWANCES AND DIFFERENTIALS Allowance Based on Duty at Remote Worksites § 591.305 Allowance rates. (a) General. An allowance rate may not exceed $10 a day....

  5. Extended Follow-up Confirms Early Vaccine-Enhanced Risk of HIV Acquisition and Demonstrates Waning Effect Over Time Among Participants in a Randomized Trial of Recombinant Adenovirus HIV Vaccine (Step Study)

    PubMed Central

    Duerr, Ann; Huang, Yunda; Buchbinder, Susan; Coombs, Robert W.; Sanchez, Jorge; del Rio, Carlos; Casapia, Martin; Santiago, Steven; Gilbert, Peter; Corey, Lawrence; Robertson, Michael N.

    2012-01-01

    Background. The Step Study tested whether an adenovirus serotype 5 (Ad5)–vectored human immunodeficiency virus (HIV) vaccine could prevent HIV acquisition and/or reduce viral load set-point after infection. At the first interim analysis, nonefficacy criteria were met. Vaccinations were halted; participants were unblinded. In post hoc analyses, more HIV infections occurred in vaccinees vs placebo recipients in men who had Ad5-neutralizing antibodies and/or were uncircumcised. Follow-up was extended to assess relative risk of HIV acquisition in vaccinees vs placebo recipients over time. Methods. We used Cox proportional hazard models for analyses of vaccine effect on HIV acquisition and vaccine effect modifiers, and nonparametric and semiparametric methods for analysis of constancy of relative risk over time. Results. One hundred seventy-two of 1836 men were infected. The adjusted vaccinees vs placebo recipients hazard ratio (HR) for all follow-up time was 1.40 (95% confidence interval [CI], 1.03–1.92; P = .03). Vaccine effect differed by baseline Ad5 or circumcision status during first 18 months, but neither was significant for all follow-up time. The HR among uncircumcised and/or Ad5-seropositive men waned with time since vaccination. No significant vaccine-associated risk was seen among circumcised, Ad5-negative men (HR, 0.97; P = 1.0) over all follow-up time. Conclusions. The vaccine-associated risk seen in interim analysis was confirmed but waned with time from vaccination. Clinical Trials Registration. NCT00095576. PMID:22561365

  6. The Twelve Steps Experientially.

    ERIC Educational Resources Information Center

    Horne, Lianne

    Experiential activities provide each participant with the ability to see, feel, and experience whatever therapeutic issue the facilitator is addressing, and usually much more. This paper presents experiential activities to address the 12 steps of recovery adopted from Alcoholics Anonymous. These 12 steps are used worldwide for many other recovery…

  7. Time?

    NASA Astrophysics Data System (ADS)

    Amoroso, Richard L.

    2013-09-01

    The concept of time in the `clockwork' Newtonian world was irrelevant; and has generally been ignored until recently by several generations of physicists since the implementation of quantum mechanics. We will set aside the utility of time as a property relating to physical calculations of events relating to a metrics line element or as an aspect of the transformation of a particles motion/interaction in a coordinate system or in relation to thermodynamics etc., i.e. we will discard all the usual uses of time as a concept used to circularly define physical parameters in terms of other physical parameters; concentrating instead on time as an aspect of the fundamental cosmic topology of our virtual reality especially as it inseparably relates to the nature and role of the observer in natural science.

  8. The Stepping Stone Approach

    NASA Astrophysics Data System (ADS)

    Brumfitt, A.

    Education is a profession in its own right. It has its own parameters, passions and language. Having the responsibility both of educare and educere, education has a focus of delivering specific factual knowledge whilst drawing out the creative mind. Space Science is a special vehicle having the properties of both educare and educere. It has a magic and wonder that touches the very essence of an individual and his place in time and space; it offers the "wow" factor that all teachers strive for. Space Science is the wrapping paper for other elements in the curriculum, e.g. cross-curricula and skill-based activities, such as language development, creativity, etc. as well as the pure sciences which comprise of engineering, physics and other natural sciences from astronomy to chemistry to biology. Each of these spheres of influence are relevant from kindergarten to undergraduate studies and complement, and in addition support informal education in museums, science centers and the world of e-learning. ESA Science Education has devised the "Stepping Stone Approach" to maximize the greatest outreach to all education stakeholders in Europe. In this paper we illustrate how to best reach these target groups with very specific activities to trigger and sustain enthusiasm whilst supporting the pedagogical, subject content and skill-based needs of a prescribed curriculum.

  9. STEP Experiment Requirements

    NASA Technical Reports Server (NTRS)

    Brumfield, M. L. (Compiler)

    1984-01-01

    A plan to develop a space technology experiments platform (STEP) was examined. NASA Langley Research Center held a STEP Experiment Requirements Workshop on June 29 and 30 and July 1, 1983, at which experiment proposers were invited to present more detailed information on their experiment concept and requirements. A feasibility and preliminary definition study was conducted and the preliminary definition of STEP capabilities and experiment concepts and expected requirements for support services are presented. The preliminary definition of STEP capabilities based on detailed review of potential experiment requirements is investigated. Topics discussed include: Shuttle on-orbit dynamics; effects of the space environment on damping materials; erectable beam experiment; technology for development of very large solar array deployers; thermal energy management process experiment; photovoltaic concentrater pointing dynamics and plasma interactions; vibration isolation technology; flight tests of a synthetic aperture radar antenna with use of STEP.

  10. Step Bunch Evolution on Vicinal Faces of KDP

    NASA Technical Reports Server (NTRS)

    Booth, N. A.; Chernov, A. A.; Vekilov, P. G.

    2003-01-01

    For in-situ studies of the formation and evolution of step patterns in solution growth, we have assembled an experimental setup based on Michelson interferometry with the growing crystal surface as one of the reflective surfaces. The device allows data collection over a relatively large area (approximately 4 sq. mm) in situ and in real time during growth. The depth resolution is improved over traditional interferometry using phase-shifted images combining by a suitable algorithm. We achieve a depth resolution of approximately 50 Angstroms. Lateral resolution, dependent on the degree of magnification, is around 0.3 to 5 microns. The crystal chosen as a model in this work is potassium dihydrogen phosphate (KDP), the optically non-linear material widely used in frequency doubling applications. Kinetics of KDP crystallization is well studied so that KDP can serve as a benchmark for our investigations. We present quantitative results on the onset, initial stages and development of instabilities in moving step trains on vicinal crystal surfaces at varying supersaturation, flow rate, and flow direction. The kinetics data suggest that at low supersaturations, step bunching is caused by impurity retardation of the steps, while at higher supersaturations, we link the non-linearity during growth to interdependence of the velocity and density of the steps evidenced in independent experiments. The behavior on the surface is very dynamic, small bunches both merge and split from larger bunches as they travel across the facet. We present evidence that despite these dynamics, under steady conditions there exists a limiting value to step bunch height. This height is reached at distances between 600 and 1000 microns from the step source. In our experiments, we observed the retention of this step bunch height limit up to the path of 1500 microns.

  11. 49 CFR 266.11 - Allowable costs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Allowable costs. 266.11 Section 266.11... TRANSPORTATION ACT § 266.11 Allowable costs. Allowable costs include only the following costs which are properly allocable to the work performed: Planning and program operation costs which are allowed under...

  12. 46 CFR 154.421 - Allowable stress.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Allowable stress. 154.421 Section 154.421 Shipping COAST... § 154.421 Allowable stress. The allowable stress for the integral tank structure must meet the American Bureau of Shipping's allowable stress for the vessel's hull published in “Rules for Building and...

  13. 46 CFR 154.421 - Allowable stress.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Allowable stress. 154.421 Section 154.421 Shipping COAST... § 154.421 Allowable stress. The allowable stress for the integral tank structure must meet the American Bureau of Shipping's allowable stress for the vessel's hull published in “Rules for Building and...

  14. 46 CFR 154.421 - Allowable stress.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Allowable stress. 154.421 Section 154.421 Shipping COAST... § 154.421 Allowable stress. The allowable stress for the integral tank structure must meet the American Bureau of Shipping's allowable stress for the vessel's hull published in “Rules for Building and...

  15. 46 CFR 154.421 - Allowable stress.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Allowable stress. 154.421 Section 154.421 Shipping COAST... § 154.421 Allowable stress. The allowable stress for the integral tank structure must meet the American Bureau of Shipping's allowable stress for the vessel's hull published in “Rules for Building and...

  16. 46 CFR 154.421 - Allowable stress.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Allowable stress. 154.421 Section 154.421 Shipping COAST... § 154.421 Allowable stress. The allowable stress for the integral tank structure must meet the American Bureau of Shipping's allowable stress for the vessel's hull published in “Rules for Building and...

  17. 46 CFR 154.440 - Allowable stress.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Allowable stress. 154.440 Section 154.440 Shipping COAST... Tank Type A § 154.440 Allowable stress. (a) The allowable stresses for an independent tank type A must... Commandant (CG-522). (b) A greater allowable stress than required in paragraph (a)(1) of this section may...

  18. Step-by-Step Simulation of Radiation Chemistry Using Green Functions for Diffusion-Influenced Reactions

    NASA Technical Reports Server (NTRS)

    Plante, Ianik; Cucinotta, Francis A.

    2011-01-01

    Radiolytic species are formed approximately 1 ps after the passage of ionizing radiation through matter. After their formation, they diffuse and chemically react with other radiolytic species and neighboring biological molecules, leading to various oxidative damage. Therefore, the simulation of radiation chemistry is of considerable importance to understand how radiolytic species damage biological molecules [1]. The step-by-step simulation of chemical reactions is difficult, because the radiolytic species are distributed non-homogeneously in the medium. Consequently, computational approaches based on Green functions for diffusion-influenced reactions should be used [2]. Recently, Green functions for more complex type of reactions have been published [3-4]. We have developed exact random variate generators of these Green functions [5], which will allow us to use them in radiation chemistry codes. Moreover, simulating chemistry using the Green functions is which is computationally very demanding, because the probabilities of reactions between each pair of particles should be evaluated at each timestep [2]. This kind of problem is well adapted for General Purpose Graphic Processing Units (GPGPU), which can handle a large number of similar calculations simultaneously. These new developments will allow us to include more complex reactions in chemistry codes, and to improve the calculation time. This code should be of importance to link radiation track structure simulations and DNA damage models.

  19. The Next Giant Step

    NASA Video Gallery

    Artist Robert McCall painted "The Next Giant Step" in 1979 to commemorate the heroism and courage of spaceflight pioneers. Located in the lobby of Johnson's building 2, the mural depicts America's ...

  20. Control Circuit For Two Stepping Motors

    NASA Technical Reports Server (NTRS)

    Ratliff, Roger; Rehmann, Kenneth; Backus, Charles

    1990-01-01

    Control circuit operates two independent stepping motors, one at a time. Provides following operating features: After selected motor stepped to chosen position, power turned off to reduce dissipation; Includes two up/down counters that remember at which one of eight steps each motor set. For selected motor, step indicated by illumination of one of eight light-emitting diodes (LED's) in ring; Selected motor advanced one step at time or repeatedly at rate controlled; Motor current - 30 mA at 90 degree positions, 60 mA at 45 degree positions - indicated by high or low intensity of LED that serves as motor-current monitor; Power-on reset feature provides trouble-free starts; To maintain synchronism between control circuit and motors, stepping of counters inhibited when motor power turned off.

  1. Step fluctuations and step interactions on Mo(0 1 1)

    NASA Astrophysics Data System (ADS)

    Ondrejcek, M.; Swiech, W.; Durfee, C. S.; Flynn, C. P.

    2003-09-01

    Step fluctuations have been studied on Mo(0 1 1) thin single crystal films with various orientations of miscut, in order to determine the step stiffnesses. Effects of unseen defect structures were clearly visible in some data. Measurements of fluctuation amplitudes and relaxation times were made in the temperature range 1100-1680 K. The results show an anisotropic stiffness of about 0.36 eV/nm along [0 1¯ 1] and about 0.15 eV/nm along [1 0 0]. No temperature dependence of the stiffness was detected. The step free energies derived from the stiffnesses average about 0.27 eV/nm and are less anisotropic by about a factor 3. From the temperature dependence of the relaxation rates, an activation energy of 0.8 ± 0.2 eV was determined for the mass diffusion of the mobile defects responsible for the fluctuations. An appendix details an investigation of correlations induced in the motions of neighboring steps by diffusion and by energetic interactions.

  2. Efficient photoheating algorithms in time-dependent photoionization simulations

    NASA Astrophysics Data System (ADS)

    Lee, Kai-Yan; Mellema, Garrelt; Lundqvist, Peter

    2016-02-01

    We present an extension to the time-dependent photoionization code C2-RAY to calculate photoheating in an efficient and accurate way. In C2-RAY, the thermal calculation demands relatively small time-steps for accurate results. We describe two novel methods to reduce the computational cost associated with small time-steps, namely, an adaptive time-step algorithm and an asynchronous evolution approach. The adaptive time-step algorithm determines an optimal time-step for the next computational step. It uses a fast ray-tracing scheme to quickly locate the relevant cells for this determination and only use these cells for the calculation of the time-step. Asynchronous evolution allows different cells to evolve with different time-steps. The asynchronized clocks of the cells are synchronized at the times where outputs are produced. By only evolving cells which may require short time-steps with these short time-steps instead of imposing them to the whole grid, the computational cost of the calculation can be substantially reduced. We show that our methods work well for several cosmologically relevant test problems and validate our results by comparing to the results of another time-dependent photoionization code.

  3. 38 CFR 3.810 - Clothing allowance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... clothing allowance; multiple types of garments affected. A veteran is entitled to an annual clothing...) Two clothing allowances; single type of garment affected. A veteran is entitled to two annual...

  4. 38 CFR 3.810 - Clothing allowance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... clothing allowance; multiple types of garments affected. A veteran is entitled to an annual clothing...) Two clothing allowances; single type of garment affected. A veteran is entitled to two annual...

  5. 38 CFR 3.810 - Clothing allowance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... clothing allowance; multiple types of garments affected. A veteran is entitled to an annual clothing...) Two clothing allowances; single type of garment affected. A veteran is entitled to two annual...

  6. 45 CFR 1157.22 - Allowable costs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... named in OBM Circular A-122 as not subject to that circular 48 CFR part 31. Contract Cost Principles and... 45 Public Welfare 3 2010-10-01 2010-10-01 false Allowable costs. 1157.22 Section 1157.22 Public... Allowable costs. (a) Limitation on use of funds. Grant funds may be used only for: (1) The allowable...

  7. 50 CFR 85.41 - Allowable costs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... applicable Federal cost principles in 43 CFR 12.60(b). Purchase of informational signs, program signs, and... 50 Wildlife and Fisheries 6 2010-10-01 2010-10-01 false Allowable costs. 85.41 Section 85.41... Use/Acceptance of Funds § 85.41 Allowable costs. (a) Allowable grant costs are limited to those...

  8. 34 CFR 304.21 - Allowable costs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Grantee § 304.21 Allowable costs. In addition to the allowable costs established in the Education Department General Administrative Regulations in 34 CFR 75.530 through 75.562, the following items are... 34 Education 2 2010-07-01 2010-07-01 false Allowable costs. 304.21 Section 304.21...

  9. 45 CFR 1180.56 - Allowable costs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Allowable costs. 1180.56 Section 1180.56 Public... by a Grantee General Administrative Responsibilities § 1180.56 Allowable costs. (a) Determination of costs allowable under a grant is made in accordance with government-wide cost principles in...

  10. 42 CFR 417.534 - Allowable costs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Allowable costs. 417.534 Section 417.534 Public... PLANS Medicare Payment: Cost Basis § 417.534 Allowable costs. (a) Definition—Allowable costs means the direct and indirect costs, including normal standby costs incurred by the HMO or CMP, that are proper...

  11. 42 CFR 417.802 - Allowable costs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Allowable costs. 417.802 Section 417.802 Public... PLANS Health Care Prepayment Plans § 417.802 Allowable costs. (a) General rule. The costs that are considered allowable for HCPP reimbursement are the same as those for reasonable cost HMOs and CMPs...

  12. 32 CFR 34.17 - Allowable costs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... organizations, is to be determined in accordance with: (1) The for-profit cost principles in 48 CFR parts 31 and.... (3) Hospitals. Allowability is determined in accordance with the provisions of 45 CFR part 74... Financial and Program Management § 34.17 Allowable costs. Allowability of costs shall be determined...

  13. 44 CFR 206.228 - Allowable costs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Allowable costs. General policies for determining allowable costs are established in 44 CFR 13.22. Exceptions to those policies as allowed in 44 CFR 13.4 and 13.6 are explained below. (a) Eligible direct... costs for major disasters and emergencies will be paid in accordance with 44 CFR part 207. (b)...

  14. 32 CFR 34.17 - Allowable costs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... organizations, is to be determined in accordance with: (1) The for-profit cost principles in 48 CFR parts 31 and.... (3) Hospitals. Allowability is determined in accordance with the provisions of 45 CFR part 74... Financial and Program Management § 34.17 Allowable costs. Allowability of costs shall be determined...

  15. 44 CFR 206.439 - Allowable costs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Allowable costs. (a) General requirements for determining allowable costs are established in 44 CFR 13.22. Exceptions to those requirements as allowed in 44 CFR 13.4 and 13.6 are explained in paragraph (b) of this... CFR part 207. (c) Pre-award costs. FEMA may fund eligible pre-award planning or project costs at...

  16. 44 CFR 206.439 - Allowable costs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Allowable costs. (a) General requirements for determining allowable costs are established in 44 CFR 13.22. Exceptions to those requirements as allowed in 44 CFR 13.4 and 13.6 are explained in paragraph (b) of this... CFR part 207. (c) Pre-award costs. FEMA may fund eligible pre-award planning or project costs at...

  17. 44 CFR 206.228 - Allowable costs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Allowable costs. General policies for determining allowable costs are established in 44 CFR 13.22. Exceptions to those policies as allowed in 44 CFR 13.4 and 13.6 are explained below. (a) Eligible direct... costs for major disasters and emergencies will be paid in accordance with 44 CFR part 207. (b)...

  18. 44 CFR 204.63 - Allowable costs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ....63 Allowable costs. 44 CFR 13.22 establishes general policies for determining allowable costs. (a) We will reimburse direct costs for the administration of a fire management assistance grant under 44 CFR... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Allowable costs....

  19. 44 CFR 204.63 - Allowable costs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ....63 Allowable costs. 44 CFR 13.22 establishes general policies for determining allowable costs. (a) We will reimburse direct costs for the administration of a fire management assistance grant under 44 CFR... 44 Emergency Management and Assistance 1 2011-10-01 2011-10-01 false Allowable costs....

  20. 46 CFR 154.447 - Allowable stress.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Allowable stress. 154.447 Section 154.447 Shipping COAST... Tank Type B § 154.447 Allowable stress. (a) An independent tank type B designed from bodies of revolution must have allowable stresses 3 determined by the following formulae: 3 See Appendix B for...

  1. 46 CFR 154.428 - Allowable stress.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Allowable stress. 154.428 Section 154.428 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR... § 154.428 Allowable stress. The membrane tank and the supporting insulation must have allowable...

  2. 20 CFR 632.258 - Allowable activities.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 3 2012-04-01 2012-04-01 false Allowable activities. 632.258 Section 632.258 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR INDIAN AND NATIVE AMERICAN EMPLOYMENT AND TRAINING PROGRAMS Summer Youth Employment and Training Programs § 632.258 Allowable activities. Allowable activities are...

  3. 34 CFR 80.22 - Allowable costs.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CFR part 31. Contract Cost Principles and Procedures, or uniform cost accounting standards that comply... 34 Education 1 2013-07-01 2013-07-01 false Allowable costs. 80.22 Section 80.22 Education Office... Allowable costs. (a) Limitation on use of funds. Grant funds may be used only for: (1) The allowable...

  4. 34 CFR 80.22 - Allowable costs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... CFR part 31. Contract Cost Principles and Procedures, or uniform cost accounting standards that comply... 34 Education 1 2014-07-01 2014-07-01 false Allowable costs. 80.22 Section 80.22 Education Office... Allowable costs. (a) Limitation on use of funds. Grant funds may be used only for: (1) The allowable...

  5. 42 CFR 417.534 - Allowable costs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 3 2012-10-01 2012-10-01 false Allowable costs. 417.534 Section 417.534 Public... PREPAYMENT PLANS Medicare Payment: Cost Basis § 417.534 Allowable costs. (a) Definition—Allowable costs means the direct and indirect costs, including normal standby costs incurred by the HMO or CMP, that...

  6. 34 CFR 80.22 - Allowable costs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... CFR part 31. Contract Cost Principles and Procedures, or uniform cost accounting standards that comply... 34 Education 1 2011-07-01 2011-07-01 false Allowable costs. 80.22 Section 80.22 Education Office... Allowable costs. (a) Limitation on use of funds. Grant funds may be used only for: (1) The allowable...

  7. 34 CFR 304.21 - Allowable costs.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Grantee § 304.21 Allowable costs. In addition to the allowable costs established in the Education Department General Administrative Regulations in 34 CFR 75.530 through 75.562, the following items are... 34 Education 2 2012-07-01 2012-07-01 false Allowable costs. 304.21 Section 304.21...

  8. 34 CFR 675.33 - Allowable costs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 34 Education 3 2011-07-01 2011-07-01 false Allowable costs. 675.33 Section 675.33 Education... costs. (a)(1) Allowable and unallowable costs. Except as provided in paragraph (a)(2) of this section, costs reasonably related to carrying out the programs described in § 675.32 are allowable. (2)...

  9. 34 CFR 675.33 - Allowable costs.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 34 Education 3 2012-07-01 2012-07-01 false Allowable costs. 675.33 Section 675.33 Education... costs. (a)(1) Allowable and unallowable costs. Except as provided in paragraph (a)(2) of this section, costs reasonably related to carrying out the programs described in § 675.32 are allowable. (2)...

  10. 45 CFR 1157.22 - Allowable costs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... named in OBM Circular A-122 as not subject to that circular 48 CFR part 31. Contract Cost Principles and... 45 Public Welfare 3 2013-10-01 2013-10-01 false Allowable costs. 1157.22 Section 1157.22 Public... Allowable costs. (a) Limitation on use of funds. Grant funds may be used only for: (1) The allowable...

  11. 34 CFR 304.21 - Allowable costs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Grantee § 304.21 Allowable costs. In addition to the allowable costs established in the Education Department General Administrative Regulations in 34 CFR 75.530 through 75.562, the following items are... 34 Education 2 2011-07-01 2010-07-01 true Allowable costs. 304.21 Section 304.21...

  12. 46 CFR 154.447 - Allowable stress.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Allowable stress. 154.447 Section 154.447 Shipping COAST... Tank Type B § 154.447 Allowable stress. (a) An independent tank type B designed from bodies of revolution must have allowable stresses 3 determined by the following formulae: 3 See Appendix B for...

  13. 46 CFR 154.447 - Allowable stress.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Allowable stress. 154.447 Section 154.447 Shipping COAST... Tank Type B § 154.447 Allowable stress. (a) An independent tank type B designed from bodies of revolution must have allowable stresses 3 determined by the following formulae: 3 See Appendix B for...

  14. 46 CFR 154.447 - Allowable stress.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Allowable stress. 154.447 Section 154.447 Shipping COAST... Tank Type B § 154.447 Allowable stress. (a) An independent tank type B designed from bodies of revolution must have allowable stresses 3 determined by the following formulae: 3 See Appendix B for...

  15. 46 CFR 154.428 - Allowable stress.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Allowable stress. 154.428 Section 154.428 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR... § 154.428 Allowable stress. The membrane tank and the supporting insulation must have allowable...

  16. 46 CFR 154.428 - Allowable stress.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Allowable stress. 154.428 Section 154.428 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR... § 154.428 Allowable stress. The membrane tank and the supporting insulation must have allowable...

  17. 46 CFR 154.428 - Allowable stress.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Allowable stress. 154.428 Section 154.428 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR... § 154.428 Allowable stress. The membrane tank and the supporting insulation must have allowable...

  18. 20 CFR 211.8 - Displacement allowance.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true Displacement allowance. 211.8 Section 211.8 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT CREDITABLE RAILROAD COMPENSATION § 211.8 Displacement allowance. An allowance paid to an employee because he has...

  19. 20 CFR 211.8 - Displacement allowance.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Displacement allowance. 211.8 Section 211.8 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT CREDITABLE RAILROAD COMPENSATION § 211.8 Displacement allowance. An allowance paid to an employee because he has...

  20. 20 CFR 211.8 - Displacement allowance.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true Displacement allowance. 211.8 Section 211.8 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT CREDITABLE RAILROAD COMPENSATION § 211.8 Displacement allowance. An allowance paid to an employee because he has...

  1. 20 CFR 211.8 - Displacement allowance.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false Displacement allowance. 211.8 Section 211.8 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT CREDITABLE RAILROAD COMPENSATION § 211.8 Displacement allowance. An allowance paid to an employee because he has...

  2. 20 CFR 211.8 - Displacement allowance.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false Displacement allowance. 211.8 Section 211.8 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT CREDITABLE RAILROAD COMPENSATION § 211.8 Displacement allowance. An allowance paid to an employee because he has...

  3. 44 CFR 204.63 - Allowable costs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ....63 Allowable costs. 44 CFR 13.22 establishes general policies for determining allowable costs. (a) We will reimburse direct costs for the administration of a fire management assistance grant under 44 CFR... 44 Emergency Management and Assistance 1 2012-10-01 2011-10-01 true Allowable costs....

  4. 44 CFR 206.228 - Allowable costs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Allowable costs. General policies for determining allowable costs are established in 44 CFR 13.22. Exceptions to those policies as allowed in 44 CFR 13.4 and 13.6 are explained below. (a) Eligible direct... accordance with 44 CFR part 207. (b)...

  5. 44 CFR 206.439 - Allowable costs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Allowable costs. (a) General requirements for determining allowable costs are established in 44 CFR 13.22. Exceptions to those requirements as allowed in 44 CFR 13.4 and 13.6 are explained in paragraph (b) of this... CFR part 207. (c) Pre-award costs. FEMA may fund eligible pre-award planning or project costs at...

  6. 44 CFR 204.63 - Allowable costs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ....63 Allowable costs. 44 CFR 13.22 establishes general policies for determining allowable costs. (a) We will reimburse direct costs for the administration of a fire management assistance grant under 44 CFR... 44 Emergency Management and Assistance 1 2014-10-01 2014-10-01 false Allowable costs....

  7. 44 CFR 206.228 - Allowable costs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Allowable costs. General policies for determining allowable costs are established in 44 CFR 13.22. Exceptions to those policies as allowed in 44 CFR 13.4 and 13.6 are explained below. (a) Eligible direct... costs for major disasters and emergencies will be paid in accordance with 44 CFR part 207. (b)...

  8. 44 CFR 206.439 - Allowable costs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Allowable costs. (a) General requirements for determining allowable costs are established in 44 CFR 13.22. Exceptions to those requirements as allowed in 44 CFR 13.4 and 13.6 are explained in paragraph (b) of this... CFR part 207. (c) Pre-award costs. FEMA may fund eligible pre-award planning or project costs at...

  9. 44 CFR 204.63 - Allowable costs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ....63 Allowable costs. 44 CFR 13.22 establishes general policies for determining allowable costs. (a) We will reimburse direct costs for the administration of a fire management assistance grant under 44 CFR... 44 Emergency Management and Assistance 1 2013-10-01 2013-10-01 false Allowable costs....

  10. 44 CFR 206.439 - Allowable costs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Allowable costs. (a) General requirements for determining allowable costs are established in 44 CFR 13.22. Exceptions to those requirements as allowed in 44 CFR 13.4 and 13.6 are explained in paragraph (b) of this... CFR part 207. (c) Pre-award costs. FEMA may fund eligible pre-award planning or project costs at...

  11. 46 CFR 154.428 - Allowable stress.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Allowable stress. 154.428 Section 154.428 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR... § 154.428 Allowable stress. The membrane tank and the supporting insulation must have allowable...

  12. 46 CFR 154.447 - Allowable stress.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Allowable stress. 154.447 Section 154.447 Shipping COAST... Tank Type B § 154.447 Allowable stress. (a) An independent tank type B designed from bodies of revolution must have allowable stresses 3 determined by the following formulae: 3 See Appendix B for...

  13. 44 CFR 206.228 - Allowable costs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Allowable costs. General policies for determining allowable costs are established in 44 CFR 13.22. Exceptions to those policies as allowed in 44 CFR 13.4 and 13.6 are explained below. (a) Eligible direct... accordance with 44 CFR part 207. (b)...

  14. One-step multiplex real-time RT-PCR assay for detecting and genotyping wild-type group A rotavirus strains and vaccine strains (Rotarix® and RotaTeq®) in stool samples.

    PubMed

    Gautam, Rashi; Mijatovic-Rustempasic, Slavica; Esona, Mathew D; Tam, Ka Ian; Quaye, Osbourne; Bowen, Michael D

    2016-01-01

    Background. Group A rotavirus (RVA) infection is the major cause of acute gastroenteritis (AGE) in young children worldwide. Introduction of two live-attenuated rotavirus vaccines, RotaTeq® and Rotarix®, has dramatically reduced RVA associated AGE and mortality in developed as well as in many developing countries. High-throughput methods are needed to genotype rotavirus wild-type strains and to identify vaccine strains in stool samples. Quantitative RT-PCR assays (qRT-PCR) offer several advantages including increased sensitivity, higher throughput, and faster turnaround time. Methods. In this study, a one-step multiplex qRT-PCR assay was developed to detect and genotype wild-type strains and vaccine (Rotarix® and RotaTeq®) rotavirus strains along with an internal processing control (Xeno or MS2 RNA). Real-time RT-PCR assays were designed for VP7 (G1, G2, G3, G4, G9, G12) and VP4 (P[4], P[6] and P[8]) genotypes. The multiplex qRT-PCR assay also included previously published NSP3 qRT-PCR for rotavirus detection and Rotarix® NSP2 and RotaTeq® VP6 qRT-PCRs for detection of Rotarix® and RotaTeq® vaccine strains respectively. The multiplex qRT-PCR assay was validated using 853 sequence confirmed stool samples and 24 lab cultured strains of different rotavirus genotypes. By using thermostable rTth polymerase enzyme, dsRNA denaturation, reverse transcription (RT) and amplification (PCR) steps were performed in single tube by uninterrupted thermocycling profile to reduce chances of sample cross contamination and for rapid generation of results. For quantification, standard curves were generated using dsRNA transcripts derived from RVA gene segments. Results. The VP7 qRT-PCRs exhibited 98.8-100% sensitivity, 99.7-100% specificity, 85-95% efficiency and a limit of detection of 4-60 copies per singleplex reaction. The VP7 qRT-PCRs exhibited 81-92% efficiency and limit of detection of 150-600 copies in multiplex reactions. The VP4 qRT-PCRs exhibited 98

  15. One-step multiplex real-time RT-PCR assay for detecting and genotyping wild-type group A rotavirus strains and vaccine strains (Rotarix® and RotaTeq®) in stool samples

    PubMed Central

    Mijatovic-Rustempasic, Slavica; Esona, Mathew D.; Tam, Ka Ian; Quaye, Osbourne; Bowen, Michael D.

    2016-01-01

    Background. Group A rotavirus (RVA) infection is the major cause of acute gastroenteritis (AGE) in young children worldwide. Introduction of two live-attenuated rotavirus vaccines, RotaTeq® and Rotarix®, has dramatically reduced RVA associated AGE and mortality in developed as well as in many developing countries. High-throughput methods are needed to genotype rotavirus wild-type strains and to identify vaccine strains in stool samples. Quantitative RT-PCR assays (qRT-PCR) offer several advantages including increased sensitivity, higher throughput, and faster turnaround time. Methods. In this study, a one-step multiplex qRT-PCR assay was developed to detect and genotype wild-type strains and vaccine (Rotarix® and RotaTeq®) rotavirus strains along with an internal processing control (Xeno or MS2 RNA). Real-time RT-PCR assays were designed for VP7 (G1, G2, G3, G4, G9, G12) and VP4 (P[4], P[6] and P[8]) genotypes. The multiplex qRT-PCR assay also included previously published NSP3 qRT-PCR for rotavirus detection and Rotarix® NSP2 and RotaTeq® VP6 qRT-PCRs for detection of Rotarix® and RotaTeq® vaccine strains respectively. The multiplex qRT-PCR assay was validated using 853 sequence confirmed stool samples and 24 lab cultured strains of different rotavirus genotypes. By using thermostable rTth polymerase enzyme, dsRNA denaturation, reverse transcription (RT) and amplification (PCR) steps were performed in single tube by uninterrupted thermocycling profile to reduce chances of sample cross contamination and for rapid generation of results. For quantification, standard curves were generated using dsRNA transcripts derived from RVA gene segments. Results. The VP7 qRT-PCRs exhibited 98.8–100% sensitivity, 99.7–100% specificity, 85–95% efficiency and a limit of detection of 4–60 copies per singleplex reaction. The VP7 qRT-PCRs exhibited 81–92% efficiency and limit of detection of 150–600 copies in multiplex reactions. The VP4 qRT-PCRs exhibited 98.8

  16. Development of SYBR green I based one-step real-time RT-PCR assay for the detection and differentiation of very virulent and classical strains of infectious bursal disease virus.

    PubMed

    Kong, Lih Ling; Omar, Abdul Rahman; Hair Bejo, Mohd; Ideris, Aini; Tan, Sheau Wei

    2009-11-01

    A SYBR Green I based one-step real-time reverse transcriptase polymerase chain reaction was developed for the detection and differentiation of very virulent (vv) and classical strains of infectious bursal disease virus (IBDV). The assay showed high PCR efficiency >93% and high reproducibility with coefficient of variation less than 0.5%. When tested on characterized IBDV strains, the very virulent and classical-specific primers detected accurately only vvIBDV and classical IBDV strains, respectively. The diagnostic efficacy of the assay was also tested on 140 bursal samples from experimental infection and 37 bursal samples from cases suspected of IBD. The assay was able to detect IBDV from bursal samples collected at days 3 and 5 post-infection with the vvIBDV strain UPM94/273 and the classical IBDV strain D78. The assay was also able to detect bursal samples infected dually with D78 and UPM94/273. The melting temperature values of the amplification products from the classical and very virulent viral infection were statistically significant (P<0.05). The specificity of the assay for detecting IBDV from suspected cases was confirmed by sequence analysis of the VP2 gene. The assay showed high sensitivity since bursal samples which were negative for IBDV were confirmed by virus isolation and PCR amplification. Hence, the new assay offers an attractive method for rapid detection of strains of IBDV. PMID:19591873

  17. Evaluation and application of a one-step duplex real-time reverse transcription polymerase chain reaction assay for the rapid detection of influenza A (H7N9) virus from poultry samples.

    PubMed

    Bao, Hongmei; Ma, Yong; Shi, Jianzhong; Zeng, Xianying; Zhao, Yuhui; Wang, Xiurong; Chen, Hualan

    2015-10-01

    In China, a novel reassortant influenza A (H7N9) virus, which has caused 435 cases of human infection, has recently emerged. Most cases of human infections with the H7N9 virus are known to be associated with a poultry farm and live-poultry markets. In this study, a one-step duplex real-time reverse transcription polymerase chain reaction (RRT-PCR) assay was developed for the simultaneous detection of the hemagglutinin (HA) and neuraminidase (NA) genes of the H7N9 virus for effective surveillance and early diagnosis of cases from clinical samples collected from live-poultry markets or poultry farms. The detection limit of this assay was as low as 0.1 EID50 of H7N9 viruses, which is similar to the detection limit of the real-time RT-PCR assay released by the Word Health Organization. The coefficients of variation (CVs) of both inter-assay and intra-assay reproducibility were less than 1.55 %, showing good reproducibility. No cross-reactivity was observed with RNA of other subtypes of influenza virus or other avian respiratory viruses. The assay can effectively detect H7N9 influenza virus RNA from multiple sources, including chickens, pigeons, ducks, humans, and the environment. Furthermore, the RRT-PCR assay was evaluated with more than 700 clinical samples collected from live-poultry markets and 120 experimentally infected chicken samples. Together, these results indicate that the duplex RRT-PCR assay is a specific, sensitive, and efficient diagnostic method for the epidemiological surveillance and diagnosis of H7N9 virus from different sources, particularly poultry samples. PMID:26179621

  18. The next step in Earth radiation budget measurements

    NASA Astrophysics Data System (ADS)

    Wiscombe, Warren; Chiu, Christine

    2013-05-01

    Space-based Earth Radiation Budget (ERB) measurements are ready to take their next major evolutionary step beyond the ERBE three-satellite constellation of the 1980s. This step would complete the ERBE vision by using not just three but dozens of satellites, and it would complete the GERB vision by providing global diurnal cycle. Such a large constellation would measure true diurnal cycle, without long chains of assumptions and extrapolations, allowing ERB to take its place alongside the other synoptic variables that are assimilated in weather and climate models, and bringing ERB back to a forefront research area. This constellation approach would make it possible to study ERB for rapidly evolving large-scale phenomena. It would also allow, for the first time, the measurement of the true Earth Radiation Imbalance, a crucial quantity, much in the news of late, for testing climate models and for predicting the future course of global warming. Among many side benefits, the greatest would be that all interested nations could participate. Such nations would merely need to meet the instrument functional requirements and find rides to space, and the system could thus grow with time, allowing continuously improved sampling, rapid deployment of new technologies with minimal damage to data continuity, and economies of scale. This is really the perfect ERB system for a budget-constrained decade.

  19. Teaching BASIC. A Step by Step Guide.

    ERIC Educational Resources Information Center

    Allen, M. F.

    This three-chapter guide provides simple explanations about BASIC programming for a teacher to use in a classroom situation, and suggests procedures for a "hands-on" course. Numerous examples are presented of the questions, problems, and level of understanding to expect from first-time, adult users (ages 13 and up). The course materials are…

  20. 9 CFR 51.32 - Claims not allowed.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Indemnity for Sheep, Goats, and Horses § 51.32 Claims not allowed. Claims for indemnity for goats, sheep, and horses destroyed because of brucellosis will not be allowed if any of the following circumstances..., authorized, or certified at the time of the test; (c) Testing of goats, sheep, and horses in the herd...