Science.gov

Sample records for fast response modeling

  1. Urban dispersion : challenges for fast response modeling

    SciTech Connect

    Brown, M. J.

    2004-01-01

    There is renewed interest in urban dispersion modeling due to the need for tools that can be used for responding to, planning for, and assessing the consequences of an airborne release of toxic materials. Although not an everyday phenomenon, releases of hazardous gases and aerosols have occurred in populated urban environments and are potentially threatening to human life. These releases may stem from on-site accidents as in the case of industrial chemical releases, may result during transport of hazardous chemicals as in tanker truck or railroad spills, or may be premeditated as in a chemical, biological, or radiological (CBR) agent terrorist attack. Transport and dispersion in urban environments is extremely complicated. Buildings alter the flow fields and deflect the wind, causing updrafts and downdrafts, channeling between buildings, areas of calm winds adjacent to strong winds, and horizontally and vertically rotating-eddies between buildings, at street corners, and other places within the urban canopy (see review by Hosker, 1984). Trees, moving vehicles, and exhaust vents among other things further complicate matters. The distance over which chemical, biological, or radiological releases can be harmful varies from tens of meters to many kilometers depending on the amount released, the toxicity of the agent, and the atmospheric conditions. As we will show later, accounting for the impacts of buildings on the transport and dispersion is crucial in estimating the travel direction, the areal extent, and the toxicity levels of the contaminant plume, and ultimately for calculating exposures to the population.

  2. FAST Mast Structural Response to Axial Loading: Modeling and Verification

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Elliott, Kenny B.; Templeton, Justin D.; Song, Kyongchan; Rayburn, Jeffery T.

    2012-01-01

    The International Space Station s solar array wing mast shadowing problem is the focus of this paper. A building-block approach to modeling and analysis is pursued for the primary structural components of the solar array wing mast structure. Starting with an ANSYS (Registered Trademark) finite element model, a verified MSC.Nastran (Trademark) model is established for a single longeron. This finite element model translation requires the conversion of several modeling and analysis features for the two structural analysis tools to produce comparable results for the single-longeron configuration. The model is then reconciled using test data. The resulting MSC.Nastran (Trademark) model is then extended to a single-bay configuration and verified using single-bay test data. Conversion of the MSC. Nastran (Trademark) single-bay model to Abaqus (Trademark) is also performed to simulate the elastic-plastic longeron buckling response of the single bay prior to folding.

  3. Importance of vegetation processes for model spread in the fast precipitation response to CO2 forcing

    NASA Astrophysics Data System (ADS)

    DeAngelis, Anthony M.; Qu, Xin; Hall, Alex

    2016-12-01

    In the current generation of climate models, the projected increase in global precipitation over the 21st century ranges from 2% to 10% under a high-emission scenario. Some of this uncertainty can be traced to the rapid response to carbon dioxide (CO2) forcing. We analyze an ensemble of simulations to better understand model spread in this rapid response. A substantial amount is linked to how the land surface partitions a change in latent versus sensible heat flux in response to the CO2-induced radiative perturbation; a larger increase in sensible heat results in a larger decrease in global precipitation. Model differences in the land surface response appear to be strongly related to the vegetation response to increased CO2, specifically, the closure of leaf stomata. Future research should thus focus on evaluation of the vegetation physiological response, including stomatal conductance parameterizations, for the purpose of constraining the fast response of Earth's hydrologic cycle to CO2 forcing.

  4. A CFD-based wind solver for a fast response transport and dispersion model

    SciTech Connect

    Gowardhan, Akshay A; Brown, Michael J; Pardyjak, Eric R; Senocak, Inanc

    2010-01-01

    In many cities, ambient air quality is deteriorating leading to concerns about the health of city inhabitants. In urban areas with narrow streets surrounded by clusters of tall buildings, called street canyons, air pollution from traffic emissions and other sources is difficult to disperse and may accumulate resulting in high pollutant concentrations. For various situations, including the evacuation of populated areas in the event of an accidental or deliberate release of chemical, biological and radiological agents, it is important that models should be developed that produce urban flow fields quickly. For these reasons it has become important to predict the flow field in urban street canyons. Various computational techniques have been used to calculate these flow fields, but these techniques are often computationally intensive. Most fast response models currently in use are at a disadvantage in these cases as they are unable to correlate highly heterogeneous urban structures with the diagnostic parameterizations on which they are based. In this paper, a fast and reasonably accurate computational fluid dynamics (CFD) technique that solves the Navier-Stokes equations for complex urban areas has been developed called QUIC-CFD (Q-CFD). This technique represents an intermediate balance between fast (on the order of minutes for a several block problem) and reasonably accurate solutions. The paper details the solution procedure and validates this model for various simple and complex urban geometries.

  5. Development and validation of a two-dimensional fast-response flood estimation model

    SciTech Connect

    Judi, David R; Mcpherson, Timothy N; Burian, Steven J

    2009-01-01

    A finite difference formulation of the shallow water equations using an upwind differencing method was developed maintaining computational efficiency and accuracy such that it can be used as a fast-response flood estimation tool. The model was validated using both laboratory controlled experiments and an actual dam breach. Through the laboratory experiments, the model was shown to give good estimations of depth and velocity when compared to the measured data, as well as when compared to a more complex two-dimensional model. Additionally, the model was compared to high water mark data obtained from the failure of the Taum Sauk dam. The simulated inundation extent agreed well with the observed extent, with the most notable differences resulting from the inability to model sediment transport. The results of these validation studies complex two-dimensional model. Additionally, the model was compared to high water mark data obtained from the failure of the Taum Sauk dam. The simulated inundation extent agreed well with the observed extent, with the most notable differences resulting from the inability to model sediment transport. The results of these validation studies show that a relatively numerical scheme used to solve the complete shallow water equations can be used to accurately estimate flood inundation. Future work will focus on further reducing the computation time needed to provide flood inundation estimates for fast-response analyses. This will be accomplished through the efficient use of multi-core, multi-processor computers coupled with an efficient domain-tracking algorithm, as well as an understanding of the impacts of grid resolution on model results.

  6. Fast and slow responses of Southern Ocean sea surface temperature to SAM in coupled climate models

    NASA Astrophysics Data System (ADS)

    Kostov, Yavor; Marshall, John; Hausmann, Ute; Armour, Kyle C.; Ferreira, David; Holland, Marika M.

    2017-03-01

    We investigate how sea surface temperatures (SSTs) around Antarctica respond to the Southern Annular Mode (SAM) on multiple timescales. To that end we examine the relationship between SAM and SST within unperturbed preindustrial control simulations of coupled general circulation models (GCMs) included in the Climate Modeling Intercomparison Project phase 5 (CMIP5). We develop a technique to extract the response of the Southern Ocean SST (55°S-70°S) to a hypothetical step increase in the SAM index. We demonstrate that in many GCMs, the expected SST step response function is nonmonotonic in time. Following a shift to a positive SAM anomaly, an initial cooling regime can transition into surface warming around Antarctica. However, there are large differences across the CMIP5 ensemble. In some models the step response function never changes sign and cooling persists, while in other GCMs the SST anomaly crosses over from negative to positive values only 3 years after a step increase in the SAM. This intermodel diversity can be related to differences in the models' climatological thermal ocean stratification in the region of seasonal sea ice around Antarctica. Exploiting this relationship, we use observational data for the time-mean meridional and vertical temperature gradients to constrain the real Southern Ocean response to SAM on fast and slow timescales.

  7. Fasted zebrafish mimic genetic and physiological responses in mammals: a model for obesity and diabetes?

    PubMed

    Craig, Paul M; Moon, Thomas W

    2011-09-01

    With worldwide rates of obesity and type-II diabetes increasing, it is essential to identify and understand the mechanisms involved during nutrient absorption and fuel allocation. Recent studies demonstrate that nutrients (e.g., lipids and carbohydrates) play a major regulatory role in gene transcription of glycolytic and lipogenic enzymes in addition to hormones, including insulin and glucagon. These nutrients generally exert their effects through key cellular nutrient/energy receptors. Fasting was used to identify these nutrient/energy receptors known from mammalian studies to ascertain if zebrafish (Danio rerio) are a suitable model for the study of metabolic disorders. Zebrafish were subjected to a fasting/re-feeding regime for 3 weeks, and gene expression of sterol responsive binding protein 1 and 2 (SREBP), the mammalian target of rapamycin (mTOR), cAMP response element binding protein 3-like 3 (CREB3l3), and AMP-activated protein kinase alpha (AMPKα) was assessed. Fasted zebrafish lost ∼10% of their body mass over the 3-week experiment, with an associated depression in oxygen consumption. Increases in liver AMPKα and CREB3l3 mRNA transcript level were noted, concurrent with increases in the activities of the β-oxidation and gluconeogenic markers β-hydroxyacyl CoA dehydrogenase and phosphoenolpyruvate carboxykinase, respectively. Conversely, a depression in liver mTOR and SREBP1 and 2 expression was noted, with a decrease in pyruvate kinase and alanine aminotransferase activities and decreases in liver lipid and glycogen contents. Twenty-four hours after re-feeding, zebrafish rapidly recover, and the majority of parameters return to control values. Taken together, these data suggest adult zebrafish are an appropriate model for the further study of human metabolic disorders.

  8. Development of a fast response dispersion model for virtual urban environments

    NASA Astrophysics Data System (ADS)

    Singh, Balwinder

    According to a UN report, more than 50% of the total world's population resides in urban areas and this fraction is increasing. Urbanization has a wide range of potential environmental impacts, including those related to the dispersion of potentially dangerous substances emitted from activities such as combustion, industrial processing or from deliberate harmful releases. This research is primarily focused on the investigation of various factors which contribute to the dispersion of certain classes of materials in a complex urban environment and improving both of the fundamental components of a fast response dispersion modeling system---wind modeling and dispersion modeling. Specifically, new empirical parameterizations have been suggested for an existing fast response wind model for street canyon flow fields. These new parameterizations are shown to produce more favorable results when compared with the experimental data. It is also demonstrated that the use of Graphics Processing Unit (GPU) technology can enhance the efficiency of an urban Lagrangian dispersion model and can achieve near real-time particle advection. The GPU also enables real-time visualizations which can be used for creating virtual urban environments to aid emergency responders. The dispersion model based on the GPU architecture relies on the so-called "simplified Langevin equations (SLEs)" for particle advection. The full or generalized form of the Langevin equations (GLEs) is known for its stiffness which tends to generate unstable modes in particle trajectory, where a particle may travel significant distances in a small time step. A fractional step methodology has been used to implement the GLEs into an existing Lagrangian random walk model to partially circumvent the stiffness associated with the GLEs. Dispersion estimates from the GLEs-based model have been compared with the SLEs-based model and available wind tunnel data. The GLEs-based model is more dispersive than the SLEs-based model in

  9. Implementation of rooftop reciculation parameterization into the QUIC fast response urban wind model

    SciTech Connect

    Bagal, N.; Singh, B.; Pardyjak, E. R.; Brown, M. J.

    2004-01-01

    The QUIC (Quick Urban & Industrial Complex) dispersion modeling system has been developed to provide high-resolution wind and concentration fields in cities. The fast response 3D urban wind model QUIC-URB explicitly solves for the flow field around buildings using a suite of empirical parameterizations and mass conservation. This procedure is based on the work of Rockle (1990). The current Rockle (1990) model does not capture the rooftop recirculation region associated with flow separation from the leading edge of an isolated building. According to Banks et al. (2001), there are two forms of separation depending on the incident wind angle. For an incident wind angle within 20{sup o} of perpendicular to the front face of the building, 'bubble separation' occurs in which cylindrical vortices whose axis are orthogonal to the flow are generated along the rooftop surface (see Fig. 1). For a 'corner wind' flow or incident wind angle of 30{sup o} to 70{sup o} of perpendicular to the front face of the building, 'conical' or 'delta wing' vortices form along the roof surface (Fig. 3). In this work, a model for rooftop recirculation is implemented into the QUIC- URB model for the two incident wind angle regimes described above. The parameterizations for the length and height of the recirculation region are from Wilson (1979) for the case of flow perpendicular or near perpendicular to the building and from Banks et al. (2000) for the case of off-angle flow. In this paper, we describe the rooftop algorithms and show how the model results are improved through comparisons to experimental data (Snyder and Lawson 1994).

  10. Modeling the viscoplastic micromechanical response of two-phase materials using fast Fourier transforms

    SciTech Connect

    Lebensohn, Ricardo A; Lee, Sukbin; Rollett, Anthony D

    2009-01-01

    A viscoplastic approach using the Fast Fourier Transform (FFT) method for obtaining local mechanical response is utilized to study microstructure-property relationships in composite materials. Specifically, three-dimensional, two-phase digital materials containing isotropically coarsened particles surrounded by a matrix phase, generated through a Kinetic Monte Carlo Potts model for Ostwald ripening, are used as instantiations in order to calculate the stress and strain rate fields under uniaxial tension. The effects of the morphology of the matrix phase, the volume fraction and the contiguity of particles, and the polycrystallinity of matrix phase, on the stress and strain rate fields under uniaxial tension are examined. It is found that the first moments of the stress and strain rate fields have a different dependence on the particle volume fraction and the particle contiguity from their second moments. The average stresses and average strain rates of both phases and of the overall composite have rather simple relationships with the particle volume fraction whereas their standard deviations vary strongly, especially when the particle volume fraction is high, and the contiguity of particles has a noticeable effect on the mechanical response. It is also found that the shape of stress distribution in the BCC hard particle phase evolves as the volume fraction of particles in the composite varies, such that it agrees with the stress field in the BCC polycrystal as the volume of particles approaches unity. Finally, it is observed that the stress and strain rate fields in the microstructures with a polycrystalline matrix are less sensitive to changes in volume fraction and contiguity of particles.

  11. Fast response sequential measurements and modelling of nanoparticles inside and outside a car cabin

    NASA Astrophysics Data System (ADS)

    Joodatnia, Pouyan; Kumar, Prashant; Robins, Alan

    2013-06-01

    Commuters are regularly exposed to short-term peak concentration of traffic produced nanoparticles (i.e. particles <300 nm in size). Studies indicate that these exposures pose adverse health effects (i.e. cardiovascular). This study aims to obtain particle number concentrations (PNCs) and distributions (PNDs) inside and outside a car cabin whilst driving on a road in Guildford, a typical UK town. Other objectives are to: (i) investigate the influences of particle transformation processes on particle number and size distributions in the cabin, (ii) correlate PNCs inside the cabin to those measured outside, and (iii) predict PNCs in the cabin based on those outside the cabin using a semi-empirical model. A fast response differential mobility spectrometer (DMS50) was employed in conjunction with an automatic switching system to measure PNCs and PNDs in the 5-560 nm range at multiple locations inside and outside the cabin at 10 Hz sampling rate over 10 s sequential intervals. Two separate sets of measurements were made at: (i) four seats in the car cabin during ˜700 min of driving, and (ii) two points, one the driver seat and the other near the ventilation air intake outside the cabin, during ˜500 min of driving. Results of the four-point measurements indicated that average PNCs at all for locations were nearly identical (i.e. 3.96, 3.85, 3.82 and 4.00 × 104 cm-3). The modest difference (˜0.1%) revealed a well-mixed distribution of nanoparticles in the car cabin. Similar magnitude and shapes of PNDs at all four sampling locations suggested that transformation processes (e.g. nucleation, coagulation, condensation) have minimal effect on particles in the cabin. Two-point measurements indicated that on average, PNCs inside the cabin were about 72% of those measured outside. Time scale analysis indicated that dilution was the fastest and dominant process in the cabin, governing the variations of PNCs in time. A semi-empirical model was proposed to predict PNCs inside

  12. Aggregate modeling of fast-acting demand response and control under real-time pricing

    SciTech Connect

    Chassin, David P.; Rondeau, Daniel

    2016-11-01

    This paper develops and assesses the performance of a short-term demand response (DR) model for utility load control with applications to resource planning and control design. Long term response models tend to underestimate short-term demand response when induced by prices. This has two important consequences. First, planning studies tend to undervalue DR and often overlook its benefits in utility demand management program development. Second, when DR is not overlooked, the open-loop DR control gain estimate may be too low. This can result in overuse of load resources, control instability and excessive price volatility. Our objective is therefore to develop a more accurate and better performing short-term demand response model. We construct the model from first principles about the nature of thermostatic load control and show that the resulting formulation corresponds exactly to the Random Utility Model employed in economics to study consumer choice. The model is tested against empirical data collected from field demonstration projects and is shown to perform better than alternative models commonly used to forecast demand in normal operating conditions. The results suggest that (1) existing utility tariffs appear to be inadequate to incentivize demand response, particularly in the presence of high renewables, and (2) existing load control systems run the risk of becoming unstable if utilities close the loop on real-time prices.

  13. Aggregate modeling of fast-acting demand response and control under real-time pricing

    SciTech Connect

    Chassin, David P.; Rondeau, Daniel

    2016-08-24

    This paper develops and assesses the performance of a short-term demand response (DR) model for utility load control with applications to resource planning and control design. Long term response models tend to underestimate short-term demand response when induced by prices. This has two important consequences. First, planning studies tend to undervalue DR and often overlook its benefits in utility demand management program development. Second, when DR is not overlooked, the open-loop DR control gain estimate may be too low. This can result in overuse of load resources, control instability and excessive price volatility. Our objective is therefore to develop a more accurate and better performing short-term demand response model. We construct the model from first principles about the nature of thermostatic load control and show that the resulting formulation corresponds exactly to the Random Utility Model employed in economics to study consumer choice. The model is tested against empirical data collected from field demonstration projects and is shown to perform better than alternative models commonly used to forecast demand in normal operating conditions. Finally, the results suggest that (1) existing utility tariffs appear to be inadequate to incentivize demand response, particularly in the presence of high renewables, and (2) existing load control systems run the risk of becoming unstable if utilities close the loop on real-time prices.

  14. Aggregate modeling of fast-acting demand response and control under real-time pricing

    SciTech Connect

    Chassin, David P.; Rondeau, Daniel

    2016-08-24

    This paper develops and assesses the performance of a short-term demand response (DR) model for utility load control with applications to resource planning and control design. Long term response models tend to underestimate short-term demand response when induced by prices. This has two important consequences. First, planning studies tend to undervalue DR and often overlook its benefits in utility demand management program development. Second, when DR is not overlooked, the open-loop DR control gain estimate may be too low. This can result in overuse of load resources, control instability and excessive price volatility. Our objective is therefore to develop a more accurate and better performing short-term demand response model. We construct the model from first principles about the nature of thermostatic load control and show that the resulting formulation corresponds exactly to the Random Utility Model employed in economics to study consumer choice. The model is tested against empirical data collected from field demonstration projects and is shown to perform better than alternative models commonly used to forecast demand in normal operating conditions. Finally, the results suggest that (1) existing utility tariffs appear to be inadequate to incentivize demand response, particularly in the presence of high renewables, and (2) existing load control systems run the risk of becoming unstable if utilities close the loop on real-time prices.

  15. Aggregate modeling of fast-acting demand response and control under real-time pricing

    DOE PAGES

    Chassin, David P.; Rondeau, Daniel

    2016-08-24

    This paper develops and assesses the performance of a short-term demand response (DR) model for utility load control with applications to resource planning and control design. Long term response models tend to underestimate short-term demand response when induced by prices. This has two important consequences. First, planning studies tend to undervalue DR and often overlook its benefits in utility demand management program development. Second, when DR is not overlooked, the open-loop DR control gain estimate may be too low. This can result in overuse of load resources, control instability and excessive price volatility. Our objective is therefore to develop amore » more accurate and better performing short-term demand response model. We construct the model from first principles about the nature of thermostatic load control and show that the resulting formulation corresponds exactly to the Random Utility Model employed in economics to study consumer choice. The model is tested against empirical data collected from field demonstration projects and is shown to perform better than alternative models commonly used to forecast demand in normal operating conditions. Finally, the results suggest that (1) existing utility tariffs appear to be inadequate to incentivize demand response, particularly in the presence of high renewables, and (2) existing load control systems run the risk of becoming unstable if utilities close the loop on real-time prices.« less

  16. Importance of land vegetation schemes for model spread in the fast global precipitation response to CO2 forcing

    NASA Astrophysics Data System (ADS)

    DeAngelis, A. M.; Qu, X.; Hall, A. D.

    2016-12-01

    Global precipitation increases by approximately 1-3%/K over the 21st century in the current generation of climate models. Part of the uncertainty in this increase originates from the rapid adjustment of global precipitation to carbon dioxide (CO2) forcing, which varies by a factor of two among models. We analyze an ensemble of simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to better understand model spread in the rapid response. A substantial amount of it can be traced to the land surface sensible heat flux response to the forcing; climate models with a larger sensible heat flux increase over land tend to have a larger reduction in oceanic convective precipitation. The model spread in sensible heat response appears to be linked to different vegetation physiological parameterizations. Specifically, the treatment of leaf stomatal closure in response to increased CO2, with some models omitting this process entirely, generates most of the model variability in sensible heat response. Future research should thus focus on evaluation of land surface parameterizations for the purpose of constraining the fast response of Earth's hydrologic cycle to CO2 forcing.

  17. Fast-response cloud chamber

    NASA Technical Reports Server (NTRS)

    Fogal, G. L.

    1977-01-01

    Wall structure keeps chambers at constant, uniform temperature, yet allows them to be cooled rapidly if necessary. Wall structure, used in fast-response cloud chamber, has surface heater and coolant shell separated by foam insulation. It is lightweight and requires relatively little power.

  18. A fast, reliable algorithm for computing frequency responses of state space models

    NASA Technical Reports Server (NTRS)

    Wette, Matt

    1991-01-01

    Computation of frequency responses for large order systems described by time invariant state space systems often provides a bottleneck in control system analysis. It is shown that banding the A-matrix in the state space model can effectively reduce the computation time for such systems while maintaining reliability in the results produced.

  19. Fast Monte Carlo-simulator with full collimator and detector response modelling for SPECT.

    PubMed

    Sohlberg, Antti O; Kajaste, Markus T

    2012-01-01

    Monte Carlo (MC)-simulations have proved to be a valuable tool in studying SPECT-reconstruction algorithms. Despite their popularity, the use of Monte Carlo-simulations is still often limited by their large computation demand. This is especially true in situations where full collimator and detector modelling with septal penetration, scatter and X-ray fluorescence needs to be included. This paper presents a rapid and simple MC-simulator, which can effectively reduce the computation times. The simulator was built on the convolution-based forced detection principle, which can markedly lower the number of simulated photons. Full collimator and detector response look-up tables are pre-simulated and then later used in the actual MC-simulations to model the system response. The developed simulator was validated by comparing it against (123)I point source measurements made with a clinical gamma camera system and against (99m)Tc software phantom simulations made with the SIMIND MC-package. The results showed good agreement between the new simulator, measurements and the SIMIND-package. The new simulator provided near noise-free projection data in approximately 1.5 min per projection with (99m)Tc, which was less than one-tenth of SIMIND's time. The developed MC-simulator can markedly decrease the simulation time without sacrificing image quality.

  20. Modeling fast stimulus-response association learning along the occipito-parieto-frontal pathway following rule instructions.

    PubMed

    Bugmann, Guido

    2012-01-24

    On the basis of instructions, humans are able to set up associations between sensory and motor areas of the brain separated by several neuronal relays, within a few seconds. This paper proposes a model of fast learning along the dorsal pathway, from primary visual areas to pre-motor cortex. A new synaptic learning rule is proposed where synaptic efficacies converge rapidly toward a specific value determined by the number of active inputs of a neuron, respecting a principle of resource limitation in terms of total synaptic input efficacy available to a neuron. The efficacies are stable with regards to repeated arrival of spikes in a spike train. This rule reproduces the inverse relationship between initial and final synaptic efficacy observed in long-term potentiation (LTP) experiments. Simulations of learning experiments are conducted in a multilayer network of leaky integrate-and-fire (LIF) spiking neuron models. It is proposed that cortical feedback connections convey a top-down learning-enabling signal that guides bottom-up learning in "hidden" neurons that are not directly exposed to input or output activity. Simulations of repeated presentation of the same stimulus-response pair, show that, under conditions of fast learning with probabilistic synaptic transmission, the networks tend to recruit a new sub-network at each presentation to represent the association, rather than re-using a previously trained one. This increasing allocation of neural resources results in progressively shorter execution times, in line with experimentally observed reduction in response time with practice. This article is part of a Special Issue entitled: Neural Coding.

  1. EVALUATION OF A FAST-RESPONSE URBAN WIND MODEL - COMPARISON TO SINGLE-BUILDING WIND TUNNEL DATA

    SciTech Connect

    E.R. PARDYJAK; M.J. BROWN

    2001-08-01

    Prediction of the 3-dimensional flow field around buildings and other obstacles is important for a number of applications, including urban air quality studies, the tracking of plumes from accidental releases of toxic air contaminants, indoor/outdoor air pollution problems, and thermal comfort assessments. Various types of computational fluid dynamics (CFD) models have been used for determining the flow fields around buildings (e.g., Reisner et al., 1998; Eichhorn et al., 1988). Comparisons to measurements show that these models work reasonably well for the most part (e.g., Ehrhard et al., 2 ; Johnson and Hunter, 1998; Murakami, 1997). However, CFD models are computationally intensive and for some applications turn-around time is of the essence. For example, planning and assessment studies in which hundreds of cases must be analyzed or emergency response scenarios in which plume transport must be computed quickly. Several fast-response dispersion models of varying levels of fidelity have been developed to explicitly account for the effects of a single building or groups of buildings (e.g., UDM - Hall et al. (2000), NRC-Ramsdell and Fosmire (1995), CBP-3 - Yamartino and Wiegand (1986), APRAC - Daerdt et al. (1973)). Although a few of these models include the Hotchkiss and Harlow (1973) analytical solution for potential flow in a notch to describe the velocity field within an urban canyon, in general, these models do not explicitly compute the velocity field around groups of buildings. The EPA PRIME model (Schulman et al., 2000) has been empirically derived to provide streamlines around a single isolated building.

  2. Improvements in fast-response flood modeling: desktop parallel computing and domain tracking

    SciTech Connect

    Judi, David R; Mcpherson, Timothy N; Burian, Steven J

    2009-01-01

    It is becoming increasingly important to have the ability to accurately forecast flooding, as flooding accounts for the most losses due to natural disasters in the world and the United States. Flood inundation modeling has been dominated by one-dimensional approaches. These models are computationally efficient and are considered by many engineers to produce reasonably accurate water surface profiles. However, because the profiles estimated in these models must be superimposed on digital elevation data to create a two-dimensional map, the result may be sensitive to the ability of the elevation data to capture relevant features (e.g. dikes/levees, roads, walls, etc...). Moreover, one-dimensional models do not explicitly represent the complex flow processes present in floodplains and urban environments and because two-dimensional models based on the shallow water equations have significantly greater ability to determine flow velocity and direction, the National Research Council (NRC) has recommended that two-dimensional models be used over one-dimensional models for flood inundation studies. This paper has shown that two-dimensional flood modeling computational time can be greatly reduced through the use of Java multithreading on multi-core computers which effectively provides a means for parallel computing on a desktop computer. In addition, this paper has shown that when desktop parallel computing is coupled with a domain tracking algorithm, significant computation time can be eliminated when computations are completed only on inundated cells. The drastic reduction in computational time shown here enhances the ability of two-dimensional flood inundation models to be used as a near-real time flood forecasting tool, engineering, design tool, or planning tool. Perhaps even of greater significance, the reduction in computation time makes the incorporation of risk and uncertainty/ensemble forecasting more feasible for flood inundation modeling (NRC 2000; Sayers et al

  3. Validation of a Fast-Response Urban Micrometeorological Model to Assess the Performance of Urban Heat Island Mitigation Strategies

    NASA Astrophysics Data System (ADS)

    Nadeau, D.; Girard, P.; Overby, M.; Pardyjak, E.; Stoll, R., II; Willemsen, P.; Bailey, B.; Parlange, M. B.

    2015-12-01

    Urban heat islands (UHI) are a real threat in many cities worldwide and mitigation measures have become a central component of urban planning strategies. Even within a city, causes of UHI vary from one neighborhood to another, mostly due the spatial variability in surface thermal properties, building geometry, anthropogenic heat flux releases and vegetation cover. As a result, the performance of UHI mitigation measures also varies in space. Hence, there is a need to develop a tool to quantify the efficiency of UHI mitigation measures at the neighborhood scale. The objective of this ongoing study is to validate the fast-response micrometeorological model QUIC EnvSim (QES). This model can provide all information required for UHI studies with a fine spatial resolution (up to 0.5m) and short computation time. QES combines QUIC, a CFD-based wind solver and dispersion model, and EnvSim, composed of a radiation model, a land-surface model and a turbulent transport model. Here, high-resolution (1 m) simulations are run over a subset of the École Polytechnique Fédérale de Lausanne (EPFL) campus including complex buildings, various surfaces properties and vegetation. For nearly five months in 2006-07, a dense network of meteorological observations (92 weather stations over 0.1 km2) was deployed over the campus and these unique data are used here as a validation dataset. We present validation results for different test cases (e.g., sunny vs cloudy days, different incoming wind speeds and directions) and explore the effect of a few UHI mitigation strategies on the spatial distribution of near-surface air temperatures. Preliminary results suggest that QES may be a valuable tool in decision-making regarding adaptation of urban planning to UHI.

  4. The Fast-Evolving phy-2 Gene Modulates Sexual Development in Response to Light in the Model Fungus Neurospora crassa

    PubMed Central

    Wang, Zheng; Li, Ning; Li, Jigang; Dunlap, Jay C.; Trail, Frances

    2016-01-01

    ABSTRACT Rapid responses to changes in incident light are critical to the guidance of behavior and development in most species. Phytochrome light receptors in particular play key roles in bacterial physiology and plant development, but their functions and regulation are less well understood in fungi. Nevertheless, genome-wide expression measurements provide key information that can guide experiments that reveal how genes respond to environmental signals and clarify their role in development. We performed functional genomic and phenotypic analyses of the two phytochromes in Neurospora crassa, a fungal model adapted to a postfire environment that experiences dramatically variable light conditions. Expression of phy-1 and phy-2 was low in early sexual development and in the case of phy-2 increased in late sexual development. Under light stimulation, strains with the phytochromes deleted exhibited increased expression of sexual development-related genes. Moreover, under red light, the phy-2 knockout strain commenced sexual development early. In the evolution of phytochromes within ascomycetes, at least two duplications have occurred, and the faster-evolving phy-2 gene has frequently been lost. Additionally, the three key cysteine sites that are critical for bacterial and plant phytochrome function are not conserved within fungal phy-2 homologs. Through the action of phytochromes, transitions between asexual and sexual reproduction are modulated by light level and light quality, presumably as an adaptation for fast asexual growth and initiation of sexual reproduction of N. crassa in exposed postfire ecosystems. PMID:26956589

  5. Fast Computation of CMH Model

    NASA Technical Reports Server (NTRS)

    Patel, Umesh D.; DellaTorre, Edward; Day, John H. (Technical Monitor)

    2001-01-01

    A fast differential equation approach for the DOK model has been extented to the CMH model. Also, a cobweb technique for calculating the CMH model is also presented. The two techniques are contrasted from the point of view of flexibility and computation time.

  6. Enhanced Model for Fast Ignition

    SciTech Connect

    Mason, Rodney J.

    2010-10-12

    Laser Fusion is a prime candidate for alternate energy production, capable of serving a major portion of the nation's energy needs, once fusion fuel can be readily ignited. Fast Ignition may well speed achievement of this goal, by reducing net demands on laser pulse energy and timing precision. However, Fast Ignition has presented a major challenge to modeling. This project has enhanced the computer code ePLAS for the simulation of the many specialized phenomena, which arise with Fast Ignition. The improved code has helped researchers to understand better the consequences of laser absorption, energy transport, and laser target hydrodynamics. ePLAS uses efficient implicit methods to acquire solutions for the electromagnetic fields that govern the accelerations of electrons and ions in targets. In many cases, the code implements fluid modeling for these components. These combined features, "implicitness and fluid modeling," can greatly facilitate calculations, permitting the rapid scoping and evaluation of experiments. ePLAS can be used on PCs, Macs and Linux machines, providing researchers and students with rapid results. This project has improved the treatment of electromagnetics, hydrodynamics, and atomic physics in the code. It has simplified output graphics, and provided new input that avoids the need for source code access by users. The improved code can now aid university, business and national laboratory users in pursuit of an early path to success with Fast Ignition.

  7. Physiological Responses of a Model Marine Diatom to Fast pH Changes: Special Implications of Coastal Water Acidification.

    PubMed

    Wu, Yaping; Beardall, John; Gao, Kunshan

    2015-01-01

    Diatoms and other phytoplankton in coastal waters experience rapid pH changes in milieu due to high biological activities and/or upwelled CO2-rich waters. While CO2 concentrating mechanisms (CCMs) are employed by all diatoms tested to counter low CO2 availability in seawater, little is known how this mechanism responds to fast pH changes. In the present study, the model diatom Thalassiosira pseudonana was acclimated for 20 generations to low pH (7.81) at an elevated CO2 of 1000 μatm (HC) or to high pH (8.18) at ambient CO2 levels of 390 μatm (LC), then its physiological characteristics were investigated as cells were shifted from HC to LC or vice versa. The maximal electron transport rate (ETRmax) in the HC-acclimated cells was immediately reduced by decreased CO2 availability, showing much lower values compared to that of the LC-acclimated cells. However, the cells showed a high capacity to regain their photochemical performance regardless of the growth CO2 levels, with their ETRmax values recovering to initial levels in about 100 min. This result indicates that this diatom might modulate its CCMs quickly to maintain a steady state supply of CO2, which is required for sustaining photosynthesis. In addition, active uptake of CO2 could play a fundamental role during the induction of CCMs under CO2 limitation, since the cells maintained high ETR even when both intracellular and periplasmic carbonic anhydrases were inhibited. It is concluded that efficient regulation of the CCM is one of the key strategies for diatoms to survive in fast changing pH environment, e.g. for the tested species, which is a dominant species in coastal waters where highly fluctuating pH is observed.

  8. Fast response densitometer for measuring liquid density

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Densitometer was developed which produces linear voltage proportional to changes in density of flowing liquid hydrogen. Unit has fast response time and good system stability, statistical variation, and thermal equilibrium. System accuracy is 2 percent of total density span. Basic design may be altered to include measurement of other flowing materials.

  9. Fast-response cup anemometer features cosine response

    NASA Technical Reports Server (NTRS)

    Frenzen, P.

    1968-01-01

    Six-cup, low-inertia anemometer combines high resolution and fast response with a unique ability to sense only the horizontal component of the winds fluctuating rapidly in three dimensions. Cup assemblies are fabricated of expanded polystyrene plastic.

  10. Fast pulse response of zinc-oxide varistors

    SciTech Connect

    Modine, F.A.; Wheeler, R.B.

    1987-04-15

    The fast pulse response of zinc-oxide varistors is studied for both high-impedance and low-impedance pulse sources. The effects of varistor capacitance and source impedance on the pulse response are examined, and quantitative descriptions of the pulse response are presented. Evidence that the varistor capacitance does not increase near breakdown voltages is found, and the implications of this result with regard to models of varistor conduction are discussed. The relationships between the properties of a varistor and its ability to protect against fast pulses are considered.

  11. RCD+: Fast loop modeling server.

    PubMed

    López-Blanco, José Ramón; Canosa-Valls, Alejandro Jesús; Li, Yaohang; Chacón, Pablo

    2016-07-08

    Modeling loops is a critical and challenging step in protein modeling and prediction. We have developed a quick online service (http://rcd.chaconlab.org) for ab initio loop modeling combining a coarse-grained conformational search with a full-atom refinement. Our original Random Coordinate Descent (RCD) loop closure algorithm has been greatly improved to enrich the sampling distribution towards near-native conformations. These improvements include a new workflow optimization, MPI-parallelization and fast backbone angle sampling based on neighbor-dependent Ramachandran probability distributions. The server starts by efficiently searching the vast conformational space from only the loop sequence information and the environment atomic coordinates. The generated closed loop models are subsequently ranked using a fast distance-orientation dependent energy filter. Top ranked loops are refined with the Rosetta energy function to obtain accurate all-atom predictions that can be interactively inspected in an user-friendly web interface. Using standard benchmarks, the average root mean squared deviation (RMSD) is 0.8 and 1.4 Å for 8 and 12 residues loops, respectively, in the challenging modeling scenario in where the side chains of the loop environment are fully remodeled. These results are not only very competitive compared to those obtained with public state of the art methods, but also they are obtained ∼10-fold faster. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  12. RCD+: Fast loop modeling server

    PubMed Central

    López-Blanco, José Ramón; Canosa-Valls, Alejandro Jesús; Li, Yaohang; Chacón, Pablo

    2016-01-01

    Modeling loops is a critical and challenging step in protein modeling and prediction. We have developed a quick online service (http://rcd.chaconlab.org) for ab initio loop modeling combining a coarse-grained conformational search with a full-atom refinement. Our original Random Coordinate Descent (RCD) loop closure algorithm has been greatly improved to enrich the sampling distribution towards near-native conformations. These improvements include a new workflow optimization, MPI-parallelization and fast backbone angle sampling based on neighbor-dependent Ramachandran probability distributions. The server starts by efficiently searching the vast conformational space from only the loop sequence information and the environment atomic coordinates. The generated closed loop models are subsequently ranked using a fast distance-orientation dependent energy filter. Top ranked loops are refined with the Rosetta energy function to obtain accurate all-atom predictions that can be interactively inspected in an user-friendly web interface. Using standard benchmarks, the average root mean squared deviation (RMSD) is 0.8 and 1.4 Å for 8 and 12 residues loops, respectively, in the challenging modeling scenario in where the side chains of the loop environment are fully remodeled. These results are not only very competitive compared to those obtained with public state of the art methods, but also they are obtained ∼10-fold faster. PMID:27151199

  13. Fast transmittance model for satellite sounding.

    PubMed

    Rayer, P J

    1995-11-01

    Through the use of new line-by-line spectral calculations in both the infrared and microwave regions, coefficients have been generated for the transmittance stage of the fast radiative transfer model used by the United Kingdom Meteorological Office. These permit the fast model to calculate the transmittance for the high-resolution infrared sounder and the microwave sounding unit instruments aboard the National Oceanic and Atmospheric Administration polar-orbiting satellite for a given atmospheric profile, simply by taking these coefficients in linear combination with a set of predictors. These are expressed in terms of the deviation of the profile from a reference. However, the method can be applied to any instrument within the range of the spectral calculations, thereby permitting new coefficients to be calculated as soon as the spectral response details for the instrument become available. It also permits effective consideration to be given in the longer term to new line data or improvements in line-shape theory. The process by which these coefficients have been obtained is described, along with a discussion of some of the tests carried out on their installation into the fast model; these tests show that they are suitable for operational use. The predictors employed by the fast model are discussed, and changes are proposed for those that relate to the water-vapor transmittance. In this respect it was found that the inclusion of predictors that depend primarily on the zenith angle of the radiation path leads to improvements in the transmittance calculation.

  14. Fast infrared response of YBCO thin films

    NASA Technical Reports Server (NTRS)

    Ballentine, P. H.; Kadin, A. M.; Donaldson, W. R.; Scofield, J. H.; Bajuk, L.

    1990-01-01

    The response to short infrared pulses of some epitaxial YBCO films prepared by sputter deposition and by electron-beam evaporation is reported. The response is found to be essentially bolometric on the ns timescale, with some indirect hints of nonequilibrium electron transport on the ps scale. Fast switching could be obtained either by biasing the switch close to the critical current or by cooling the film below about 20 K. These results are encouraging for potential application to a high-current optically-triggered opening switch.

  15. Operating manual: Fast response solar array simulator

    NASA Technical Reports Server (NTRS)

    Vonhatten, R.; Weimer, A.; Zerbel, D. W.

    1971-01-01

    The fast response solar array simulator (FRSAS) is a universal solar array simulator which features an AC response identical to that of a real array over a large range of DC operating points. In addition, short circuit current (I sub sc) and open circuit voltage (V sub oc) are digitally programmable over a wide range for use not only in simulating a wide range of array sizes, but also to simulate (I sub sc) and (V sub oc) variations with illumination and temperature. A means for simulation of current variations due to spinning is available. Provisions for remote control and monitoring, automatic failure sensing and warning, and a load simulator are also included.

  16. Side-welded fast response sheathed thermocouple

    DOEpatents

    Carr, Kenneth R.

    1981-01-01

    A method of fabricating the measuring junction of a grounded-junction sheathed thermocouple to obtain fast time response and good thermal cycling performance is provided. Slots are tooled or machined into the sheath wall at the measuring junction, the thermocouple wires are laser-welded into the slots. A thin metal closure cap is then laser-welded over the end of the sheath. Compared to a conventional grounded-junction thermocouple, the response time is 4-5 times faster and the thermal shock and cycling capabilities are substantially improved.

  17. Side-welded fast response sheathed thermocouple

    DOEpatents

    Carr, K.R.

    A method of fabricating the measuring junction of a grounded-junction sheathed thermocouple to obtain fast time response and good thermal cycling performance is provided. Slots are tooled or machined into the sheath wall at the measuring junction, the thermocouple wires are laser-welded into the slots. A thin metal closure cap is then laser-welded over the end of the sheath. Compared to a conventional grounded-junction thermocouple, the response time is 4 to 5 times faster and the thermal shock and cycling capabilities are substantially improved.

  18. FAST Simulation Tool Containing Methods for Predicting the Dynamic Response of Wind Turbines

    SciTech Connect

    Jonkman, Jason

    2015-08-12

    FAST is a simulation tool (computer software) for modeling tlie dynamic response of horizontal-axis wind turbines. FAST employs a combined modal and multibody structural-dynamics formulation in the time domain.

  19. The fast debris evolution model

    NASA Astrophysics Data System (ADS)

    Lewis, H. G.; Swinerd, G. G.; Newland, R. J.; Saunders, A.

    2009-09-01

    The 'particles-in-a-box' (PIB) model introduced by Talent [Talent, D.L. Analytic model for orbital debris environmental management. J. Spacecraft Rocket, 29 (4), 508-513, 1992.] removed the need for computer-intensive Monte Carlo simulation to predict the gross characteristics of an evolving debris environment. The PIB model was described using a differential equation that allows the stability of the low Earth orbit (LEO) environment to be tested by a straightforward analysis of the equation's coefficients. As part of an ongoing research effort to investigate more efficient approaches to evolutionary modelling and to develop a suite of educational tools, a new PIB model has been developed. The model, entitled Fast Debris Evolution (FADE), employs a first-order differential equation to describe the rate at which new objects ⩾10 cm are added and removed from the environment. Whilst Talent [Talent, D.L. Analytic model for orbital debris environmental management. J. Spacecraft Rocket, 29 (4), 508-513, 1992.] based the collision theory for the PIB approach on collisions between gas particles and adopted specific values for the parameters of the model from a number of references, the form and coefficients of the FADE model equations can be inferred from the outputs of future projections produced by high-fidelity models, such as the DAMAGE model. The FADE model has been implemented as a client-side, web-based service using JavaScript embedded within a HTML document. Due to the simple nature of the algorithm, FADE can deliver the results of future projections immediately in a graphical format, with complete user-control over key simulation parameters. Historical and future projections for the ⩾10 cm LEO debris environment under a variety of different scenarios are possible, including business as usual, no future launches, post-mission disposal and remediation. A selection of results is presented with comparisons with predictions made using the DAMAGE environment model

  20. The Fast Debris Evolution Model

    NASA Astrophysics Data System (ADS)

    Lewis, Hugh G.; Swinerd, Graham; Newland, Rebecca; Saunders, Arrun

    The ‘Particles-in-a-box' (PIB) model introduced by Talent (1992) removed the need for computerintensive Monte Carlo simulation to predict the gross characteristics of an evolving debris environment. The PIB model was described using a differential equation that allows the stability of the low Earth orbit (LEO) environment to be tested by a straightforward analysis of the equation's coefficients. As part of an ongoing research effort to investigate more efficient approaches to evolutionary modelling and to develop a suite of educational tools, a new PIB model has been developed. The model, entitled Fast Debris Evolution (FaDE), employs a first-order differential equation to describe the rate at which new objects (˜ 10 cm) are added and removed from the environment. Whilst Talent (1992) based the collision theory for the PIB approach on collisions between gas particles and adopted specific values for the parameters of the model from a number of references, the form and coefficients of the FaDE model equations can be inferred from the outputs of future projections produced by high-fidelity models, such as the DAMAGE model. The FaDE model has been implemented as a client-side, web-based service using Javascript embedded within a HTML document. Due to the simple nature of the algorithm, FaDE can deliver the results of future projections immediately in a graphical format, with complete user-control over key simulation parameters. Historical and future projections for the ˜ 10 cm low Earth orbit (LEO) debris environment under a variety of different scenarios are possible, including business as usual, no future launches, post-mission disposal and remediation. A selection of results is presented with comparisons with predictions made using the DAMAGE environment model. The results demonstrate that the FaDE model is able to capture comparable time-series of collisions and number of objects as predicted by DAMAGE in several scenarios. Further, and perhaps more importantly

  1. Dose-dependent vascular response following delivery of sirolimus via fast releasing, biodegradable polymer stent matrix: an experimental study in the porcine coronary model of restenosis.

    PubMed

    Buszman, Piotr P; Orlik, Bartłomiej; Pająk, Jacek; Jelonek, Michał; Krauze, Agata; Janas, Adam; Legutko, Jacek; Wojakowski, Wojciech; Buszman, Paweł E; Milewski, Krzysztof

    2015-01-01

    Fast releasing, rapamycin-eluting stents, although safe, showed inferior results with regard to inhibition of restenosis. Therefore, we report vascular effects of a novel, biodegradable polymer stent matrix with elevated sirolimus dose and fast release kinetics (ed-frSES, Alex, Balton) in the porcine coronary in-stent restenosis model. A total of 19 stents were implanted with 120% overstretch in the coronary arteries of seven domestic pigs: seven ed-frSES with 1.3 μg/mm2 of sirolimus, eight frSES with 1 μg/mm2 of sirolimus, and eight bare metal stents (BMS). For the following 28 days, coronary angiography was performed, animals were sacrificed, and the stented segments harvested for histopathological evaluation. In angiography at 28 days the late lumen loss was lowest in the elevated dose sirolimus eluting stent (SES) (ed-frSES: 0.20 ± 0.2 vs. frSES: 0.80 ± 0.5 vs. BMS: 0.96 ± 0.5 mm, p < 0.01). This was confirmed in the morphometric evaluation in histopathology as represented by a significant and dose-dependent decrease in the percentage area of stenosis (ed-frSES: 22.4 ± 12.7% vs. frSES: 35 ± 10.7% vs. BMS: 47.5 ± 12.5%, p < 0.01). There was no peri-strut inflammation in any of the groups. However, the endothelialisation score was numerically not meaningfully decreased in ed-frSES (ed-frSES: 2.93 vs. frSES: 3. vs. BMS: 3, p = 0.05). Signs of fibrin were also noted in ed-frSES (ed-frSES: 0.4 vs. frSES: 0 vs. BMS: 0, p = 0.05). Sirolimus dose-dependent vascular response was reported. The elevated dose, fast releasing SES shows satisfactory vascular healing, similar to regular dose, fast release SES, with improved efficacy in restenosis inhibition.

  2. [Fast Response Training in Youth Soccer Players].

    PubMed

    Bartels, T; Proeger, S; Meyer, D; Rabe, J; Brehme, K; Pyschik, M; Delank, K S; Fieseler, G; Schulze, S; Schwesig, R

    2016-08-01

    Injuries of the knee and ankle joint are a serious ongoing problem in soccer. Although there is a variety of prevention programmes, a significant reduction of severe knee injuries has not been observed. Therefore, current strategies for diagnostics and training need to be re-evaluated. Our study aimed to test a totally new intervention strategy (fast response training on the SpeedCourt). The efficiency of this method was evaluated with youth soccer athletes. 24 young male class A athletes (mean age 18.0 ± 0.7 years) of a local soccer team underwent SpeedCourt training for 7 weeks (1 training session per week = TS) during the regular season of competition. TS contained life-kinetic elements (time of exercise: 15 - 30 seconds, break: 2 minutes) and included a warm-up phase (15 minutes) and fast response training on the SpeedCourt (30 minutes). The players were tested on the SpeedCourt with different tests (Counter Movement Jump (CMJ), shuttle run, tapping, 10-second sprint) before and after the training programme. The univariate single-factor analysis of variance showed significant improvements in all test parameters (η(2)> 0.10). The range varied between η(2) = 0.106 (time of ground contact right leg) und η(2) = 0.730 (reaction time right leg). We did not find any relevant correlations between the tests and parameters. The number of injury-related accidents involving the lower extremities was reduced by about 50 % during defined periods of time. Our data revealed that training with fast responses at the SpeedCourt system clearly improved speed and speed strength performance of young soccer athletes, which is remarkable given the low intensity of influences (one TS per week). The increase in performance was accompanied by a significant reduction of the injury rate. © Georg Thieme Verlag KG Stuttgart · New York.

  3. Probing Planetary Bodies for Subsurface Volatiles: GEANT4 Models of Gamma Ray, Fast, Epithermal, and Thermal Neutron Response to Active Neutron Illumination

    NASA Astrophysics Data System (ADS)

    Chin, G.; Sagdeev, R.; Su, J. J.; Murray, J.

    2014-12-01

    Using an active source of neutrons as an in situ probe of a planetary body has proven to be a powerful tool to extract information about the presence, abundance, and location of subsurface volatiles without the need for drilling. The Dynamic Albedo of Neutrons (DAN) instrument on Curiosity is an example of such an instrument and is designed to detect the location and abundance of hydrogen within the top 50 cm of the Martian surface. DAN works by sending a pulse of neutrons towards the ground beneath the rover and detecting the reflected neutrons. The intensity and time of arrival of the reflection depends on the proportion of water, while the time the pulse takes to reach the detector is a function of the depth at which the water is located. Similar instruments can also be effective probes at the polar-regions of the Moon or on asteroids as a way of detecting sequestered volatiles. We present the results of GEANT4 particle simulation models of gamma ray, fast, epithermal, and thermal neutron responses to active neutron illumination. The results are parameterized by hydrogen abundance, stratification and depth of volatile layers, versus the distribution of neutron and gamma ray energy reflections. Models will be presented to approximate Martian, lunar, and asteroid environments and would be useful tools to assess utility for future NASA exploration missions to these types of planetary bodies.

  4. Fast response to human voices in autism

    PubMed Central

    Lin, I-Fan; Agus, Trevor R.; Suied, Clara; Pressnitzer, Daniel; Yamada, Takashi; Komine, Yoko; Kato, Nobumasa; Kashino, Makio

    2016-01-01

    Individuals with autism spectrum disorders (ASD) are reported to allocate less spontaneous attention to voices. Here, we investigated how vocal sounds are processed in ASD adults, when those sounds are attended. Participants were asked to react as fast as possible to target stimuli (either voices or strings) while ignoring distracting stimuli. Response times (RTs) were measured. Results showed that, similar to neurotypical (NT) adults, ASD adults were faster to recognize voices compared to strings. Surprisingly, ASD adults had even shorter RTs for voices than the NT adults, suggesting a faster voice recognition process. To investigate the acoustic underpinnings of this effect, we created auditory chimeras that retained only the temporal or the spectral features of voices. For the NT group, no RT advantage was found for the chimeras compared to strings: both sets of features had to be present to observe an RT advantage. However, for the ASD group, shorter RTs were observed for both chimeras. These observations indicate that the previously observed attentional deficit to voices in ASD individuals could be due to a failure to combine acoustic features, even though such features may be well represented at a sensory level. PMID:27193919

  5. Decreased insulin response in dairy cows following a four-day fast to induce hepatic lipidosis.

    PubMed

    Oikawa, S; Oetzel, G R

    2006-08-01

    Negative energy balance has been implicated in the development of fatty liver, insulin resistance, and impaired health in dairy cows. A 4-d fasting model previously was reported to increase liver triglycerides more than 2.5-fold. The purpose of the present study was to evaluate insulin response in this fasting model. Nonlactating, nonpregnant Holstein cows were fasted for 4 d (6 cows) or fed continuously as control cows (4 cows). Samples were collected 5 d before fasting, during fasting, and immediately after the 4-d fast, 8 d after the fast, and 16 d after the fast. Fasted cows had greater liver triglyceride content (49.4 vs. 16.2 mg/g, wet-weight basis) at the end of the fasting period compared with control cows. Fasted cows also had increased plasma nonesterified fatty acid (NEFA) concentrations (1.24 vs. 0.21 mmol/L) and increased plasma beta-hydroxybutyrate (BHBA) concentrations at the end of the fasting period. Liver triglyceride, plasma NEFA, and plasma BHBA in fasted cows returned to prefasting concentrations by the end of the experiment. Plasma glucose concentrations were not affected by fasting. Plasma insulin concentrations were decreased (6.3 vs. 14.1 microU/mL) and insulin-stimulated blood glucose reduction was decreased (24.9 vs. 48.6%) in the fasted cows compared with control cows at the end of the fast, indicating reduced insulin response. Insulin response was negatively correlated with plasma NEFA and liver triglycerides. Decreased insulin response may be an important complication of negative energy balance and hepatic lipidosis.

  6. Fast Computation of the Inverse CMH Model

    NASA Technical Reports Server (NTRS)

    Patel, Umesh D.; Torre, Edward Della; Day, John H. (Technical Monitor)

    2001-01-01

    A fast computational method based on differential equation approach for inverse DOK model has been extended for the inverse CMH model. Also, a cobweb technique for calculating the inverse CMH model is also presented. The two techniques are differed from the point of view of flexibility and computation time.

  7. Fast two-dimensional model

    NASA Technical Reports Server (NTRS)

    Jackman, Charles H.; Douglass, Anne R.; Stolarski, Richard S.; Guthrie, Paul D.; Thompson, A. M.

    1990-01-01

    A two dimensional (altitude and latitude) model of the atmosphere is used to investigate problems relating to the variability of the dynamics and temperature of the atmosphere on the ozone distribution, solar cycle variations of atmospheric constituents, the sensitivity of model results to tropospheric trace gas sources, and assessment computations of changes in ozone related to manmade influences. In a comparison between two dimensional model results in which the odd nitrogen family was transported together and model results in which the odd nitrogen species was transported separately, it was found that the family approximations are adequate for perturbation scenario calculations.

  8. Evidence of Effective Early Numeracy Models. CEELO FastFacts

    ERIC Educational Resources Information Center

    Schilder, D.

    2014-01-01

    In this "Fast Facts," a state requested information on supporting districts' use of effective models and approaches to improve children's early literacy and numeracy outcomes. In response, Center on Enhancing Early Learning Outcomes (CEELO) staff reviewed key research including information from the What Works Clearinghouse obtained by…

  9. A critical role for the peroxisome proliferator-activated receptor alpha (PPARalpha) in the cellular fasting response: the PPARalpha-null mouse as a model of fatty acid oxidation disorders.

    PubMed

    Leone, T C; Weinheimer, C J; Kelly, D P

    1999-06-22

    We hypothesized that the lipid-activated transcription factor, the peroxisome proliferator-activated receptor alpha (PPARalpha), plays a pivotal role in the cellular metabolic response to fasting. Short-term starvation caused hepatic steatosis, myocardial lipid accumulation, and hypoglycemia, with an inadequate ketogenic response in adult mice lacking PPARalpha (PPARalpha-/-), a phenotype that bears remarkable similarity to that of humans with genetic defects in mitochondrial fatty acid oxidation enzymes. In PPARalpha+/+ mice, fasting induced the hepatic and cardiac expression of PPARalpha target genes encoding key mitochondrial (medium-chain acyl-CoA dehydrogenase, carnitine palmitoyltransferase I) and extramitochondrial (acyl-CoA oxidase, cytochrome P450 4A3) enzymes. In striking contrast, the hepatic and cardiac expression of most PPARalpha target genes was not induced by fasting in PPARalpha-/- mice. These results define a critical role for PPARalpha in a transcriptional regulatory response to fasting and identify the PPARalpha-/- mouse as a potentially useful murine model of inborn and acquired abnormalities of human fatty acid utilization.

  10. Fasting-related autophagic response in slow- and fast-twitch skeletal muscle.

    PubMed

    Ogata, Tomonori; Oishi, Yasuharu; Higuchi, Mitsuru; Muraoka, Isao

    2010-03-26

    This study investigated regulation of autophagy in slow-twitch soleus and fast-twitch plantaris muscles in fasting-related atrophy. Male Fischer-344 rats were subjected to fasting for 1, 2, or 3 days. Greater weight loss was observed in plantaris muscle than in soleus muscle in response to fasting. Western blot analysis demonstrated that LC3-II, a marker protein for macroautophagy, was expressed at a notably higher level in plantaris than in soleus muscle, and that the expression level was fasting duration-dependent. To identify factors related to LC3-II enhancement, autophagy-related signals were examined in both types of muscle. Phosphorylated mTOR was reduced in plantaris but not in soleus muscle. FOXO3a and ER stress signals were unchanged in both muscle types during fasting. These findings suggest that preferential atrophy of fast-twitch muscle is associated with induction of autophagy during fasting and that differences in autophagy regulation are attributable to differential signal regulation in soleus and plantaris muscle.

  11. Fast Electromechanical Response in Liquid Crystal Elastomer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Verduzco, Rafael; Agrawal, Aditya; Jacot, Jeff; Adetiba, Tomi

    2014-03-01

    Liquid crystal elastomers (LCEs) combine the elasticity of polymer networks with the fluidity and responsiveness of liquid crystals. LCEs can respond to a variety of external stimuli - heat, light, electric and magnetic fields - with large and reversible shape-changes. However, the response can be slow and/or require large external fields. Here, we present our recent work with LCE bilayers and LCE composite materials that demonstrates LCEs can respond quickly and with 3-D shape changes. Nematic LCE bilayers are prepared by depositing a PS film on top of a nematic LCE, and the bilayers exhibit reversible wrinkling, folding, and curling with temperature. The shape change of LCE bilayers is quantitatively predicted using finite-element modeling. Next, we show that a fast response to an electric field is achieved in nematic LCE composites. While typical nematic LCEs are relatively unresponsive to electric fields, LCE composites with 2 wt % carbon black can reversibly contract and expand in response to a 40 V electric field. The response time (0.1 - 10 Hz) and amplitude of shape change (1 - 20 %) depends on the external field and carbon black content. These composites may be useful for biomedical applications, such as substrates for dynamic cell culture and biocompatible scaffolds for heart tissue regeneration. Neonatal rat ventricular myocytes remain viable on LCE-carbon black bilayer substrates, and aligned myocyte cell sheets were successfully grown on LCE-composite bilayers.

  12. Blunted metabolic response to fasting in obese mice.

    PubMed

    Ueno, Naohiko; Asakawa, Akihiro; Inui, Akio

    2007-10-01

    The aim of the study was to evaluate metabolic changes in response to fasting in normal and obese mice. C57BL6 and obese (diet-induced obesity (DIO) and ob/ob) mice were used in this study. They were fasted for 24 h and re-fed for 24 h. Body weight was monitored before, after fasting and during re-feeding (2 and 24 h after re-feeding). Food intake was measured 2 and 24 h after re-feeding began. Blood samples were taken before and after 24 h fasting. As metabolic parameters, blood glucose, plasma insulin, ghrelin levels and oxygen consumption were measured. Blood glucose and plasma insulin levels in DIO and ob/ob mice were higher than normal mice, and plasma ghrelin levels were lower in DIO and ob/ob mice. There was reduced body weight loss in DIO mice than in normal mice for 24 h fasting. When they were re-fed, DIO and ob/ob mice consumed less food intake than normal mice. Twenty-four hours food deprivation induced significantly smaller plasma ghrelin elevation in these obese mice. Fasting-induced decrease in oxygen consumption was significantly smaller in DIO and ob/ob mice than normal mice. This data show that obese mice may have decreased sensitivity to fasting-induced increase in circulating ghrelin and their oxygen consumption exhibited a blunted response to fasting.

  13. Fast temperature relaxation model in dense plasmas

    NASA Astrophysics Data System (ADS)

    Faussurier, Gérald; Blancard, Christophe

    2017-01-01

    We present a fast model to calculate the temperature-relaxation rates in dense plasmas. The electron-ion interaction-potential is calculated by combining a Yukawa approach and a finite-temperature Thomas-Fermi model. We include the internal energy as well as the excess energy of ions using the QEOS model. Comparisons with molecular dynamics simulations and calculations based on an average-atom model are presented. This approach allows the study of the temperature relaxation in a two-temperature electron-ion system in warm and hot dense matter.

  14. Post-fasting olfactory, transcriptional, and feeding responses in Drosophila.

    PubMed

    Farhadian, Shelli F; Suárez-Fariñas, Mayte; Cho, Christine E; Pellegrino, Maurizio; Vosshall, Leslie B

    2012-01-18

    The sensation of hunger after a period of fasting and of satiety after eating is crucial to behavioral regulation of food intake, but the biological mechanisms regulating these sensations are incompletely understood. We studied the behavioral and physiological adaptations to fasting in the vinegar fly (Drosophila melanogaster). Here we show that both male and female flies increased their rate of food intake transiently in the post-fasted state. Although the basal feeding rate was higher in females than males, the magnitude of the post-fasting feeding response was the same in both sexes. Flies returned to a stable baseline feeding rate within 12 h after return to food for males and 24 h for females. This modulation in feeding was accompanied by a significant increase in the size of the crop organ of the digestive system, suggesting that fasted flies responded both by increasing their food intake and storing reserve food in their crop. Flies demonstrated increased behavioral attraction to an attractive odor when food-deprived. Expression profiling of head, body, and chemosensory tissues by microarray analysis revealed 415 genes regulated by fasting after 24 h and 723 genes after 48 h, with downregulated genes outnumbering upregulated genes in each tissue and fasting time point. These transcriptional changes showed rich temporal dynamics and affected genes across multiple functional gene ontology categories. These observations suggest that a coordinated transcriptional response to internal physiological state may regulate both ingestive behaviors and chemosensory perception of food. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Post-fasting olfactory, transcriptional, and feeding responses in Drosophila

    PubMed Central

    Farhadian, Shelli F.; Suárez-Fariñas, Mayte; Cho, Christine E.; Pellegrino, Maurizio; Vosshall, Leslie B.

    2011-01-01

    The sensation of hunger after a period of fasting and of satiety after eating is crucial to behavioral regulation of food intake, but the biological mechanisms regulating these sensations are incompletely understood. We studied the behavioral and physiological adaptation to fasting in the vinegar fly (Drosophila melanogaster). Here we show that both male and female flies increased their rate of food intake transiently in the post-fasted state. Although the basal feeding rate was higher in females than males, the magnitude of the post-fasting feeding response was the same in both sexes. Flies returned to a stable baseline feeding rate within 12 hr after return to food for males and 24 hr for females. This modulation in feeding was accompanied by a significant increase in the size of the crop organ of the digestive system, suggesting that fasted flies responded both by increasing their food intake and storing reserve food in their crop. Flies demonstrated increased behavioral attraction to an attractive odor when food-deprived. Expression profiling of head, body, and chemosensory tissues by microarray analysis revealed 415 genes regulated by fasting after 24 hr and 723 genes after 48 hr, with downregulated genes outnumbering upregulated genes in each tissue and fasting time point. These transcriptional changes showed rich temporal dynamics and affected genes across multiple functional gene ontology categories. These observations suggest that a coordinated transcriptional response to internal physiological state may regulate both ingestive behaviors and chemosensory perception of food. PMID:21945372

  16. Fast Quantum Rabi Model with Trapped Ions

    PubMed Central

    Moya-Cessa, Héctor M.

    2016-01-01

    We show how to produce a fast quantum Rabi model with trapped ions. Its importance resides not only in the acceleration of the phenomena that may be achieved with these systems, from quantum gates to the generation of nonclassical states of the vibrational motion of the ion, but also in reducing unwanted effects such as the decay of coherences that may appear in such systems. PMID:27941846

  17. Fast Quantum Rabi Model with Trapped Ions.

    PubMed

    Moya-Cessa, Héctor M

    2016-12-12

    We show how to produce a fast quantum Rabi model with trapped ions. Its importance resides not only in the acceleration of the phenomena that may be achieved with these systems, from quantum gates to the generation of nonclassical states of the vibrational motion of the ion, but also in reducing unwanted effects such as the decay of coherences that may appear in such systems.

  18. Fast and Slow Precipitation Responses to Individual Climate Forcers: A PDRMIP Multimodel Study

    NASA Technical Reports Server (NTRS)

    Samset, B. H.; Myhre, G.; Forster, P.M.; Hodnebrog, O.; Andrews, T.; Faluvegi, G.; Flaschner, D.; Kasoar, M.; Kharin, V.; Kirkevag, A.; hide

    2016-01-01

    Precipitation is expected to respond differently to various drivers of anthropogenic climate change. We present the first results from the Precipitation Driver and Response Model Intercomparison Project (PDRMIP), where nine global climate models have perturbed CO2, CH4, black carbon, sulfate, and solar insolation. We divide the resulting changes to global mean and regional precipitation into fast responses that scale with changes in atmospheric absorption and slow responses scaling with surface temperature change. While the overall features are broadly similar between models, we find significant regional intermodel variability, especially over land. Black carbon stands out as a component that may cause significant model diversity in predicted precipitation change. Processes linked to atmospheric absorption are less consistently modeled than those linked to top-of-atmosphere radiative forcing. We identify a number of land regions where the model ensemble consistently predicts that fast precipitation responses to climate perturbations dominate over the slow, temperature-driven responses.

  19. Fast and Slow Precipitation Responses to Individual Climate Forcers: A PDRMIP Multimodel Study

    NASA Technical Reports Server (NTRS)

    Samset, B. H.; Myhre, G.; Forster, P.M.; Hodnebrog, O.; Andrews, T.; Faluvegi, G.; Flaschner, D.; Kasoar, M.; Kharin, V.; Kirkevag, A.; Shindell, D.; Voulgarakis, A.

    2016-01-01

    Precipitation is expected to respond differently to various drivers of anthropogenic climate change. We present the first results from the Precipitation Driver and Response Model Intercomparison Project (PDRMIP), where nine global climate models have perturbed CO2, CH4, black carbon, sulfate, and solar insolation. We divide the resulting changes to global mean and regional precipitation into fast responses that scale with changes in atmospheric absorption and slow responses scaling with surface temperature change. While the overall features are broadly similar between models, we find significant regional intermodel variability, especially over land. Black carbon stands out as a component that may cause significant model diversity in predicted precipitation change. Processes linked to atmospheric absorption are less consistently modeled than those linked to top-of-atmosphere radiative forcing. We identify a number of land regions where the model ensemble consistently predicts that fast precipitation responses to climate perturbations dominate over the slow, temperature-driven responses.

  20. A fast response thermal conductivity gage

    NASA Astrophysics Data System (ADS)

    Pilcher, J. O., II; Krummerich, M. B.

    1986-04-01

    During the spring of 1983, the Ballistic Research Laboratory measured behind-the-armor effects for several weapons against a variety of targets. One of the major concerns was heat generation during and immediately following impact of the warhead against the targets. Previous tests of this type had used thin skin total heat gages and standard laboratory heat detectors. Thin skin gages record only the maximum temperature attained by the skins' back surface with no indication of the time required to reach this temperature. Although an approximation of the total heat deposition can be made, no rate of deposition can be estimated without knowing the time of the event. The large thermal mass of a typical laboratory detector such as an infrared power meter is designed to measure a steady-state flux and cannot respond quickly enough to register a transient event. Neither gage type can withstand severe blast and shock environments. Since the temperature inside the target rose sharply in a very short time, special thermal fluence gages were fabricated which emphasized the time response of the gage rather than its thermal capacity. This gage is used when the thermal flux is of short duration, 150 milliseconds or less, and of low total energy, 179 calories per square centimeter or less. The maximum operating temperature of the gage is 500 degree Celsius.

  1. A fast hidden line algorithm for plotting finite element models

    NASA Technical Reports Server (NTRS)

    Jones, G. K.

    1982-01-01

    Effective plotting of finite element models requires the use of fast hidden line plot techniques that provide interactive response. A high speed hidden line technique was developed to facilitate the plotting of NASTRAN finite element models. Based on testing using 14 different models, the new hidden line algorithm (JONES-D) appears to be very fast: its speed equals that for normal (all lines visible) plotting and when compared to other existing methods it appears to be substantially faster. It also appears to be very reliable: no plot errors were observed using the new method to plot NASTRAN models. The new algorithm was made part of the NPLOT NASTRAN plot package and was used by structural analysts for normal production tasks.

  2. Application of Model Based Parameter Estimation for Fast Frequency Response Calculations of Input Characteristics of Cavity-Backed Aperture Antennas Using Hybrid FEM/MoM Technique

    NASA Technical Reports Server (NTRS)

    Reddy C. J.

    1998-01-01

    Model Based Parameter Estimation (MBPE) is presented in conjunction with the hybrid Finite Element Method (FEM)/Method of Moments (MoM) technique for fast computation of the input characteristics of cavity-backed aperture antennas over a frequency range. The hybrid FENI/MoM technique is used to form an integro-partial- differential equation to compute the electric field distribution of a cavity-backed aperture antenna. In MBPE, the electric field is expanded in a rational function of two polynomials. The coefficients of the rational function are obtained using the frequency derivatives of the integro-partial-differential equation formed by the hybrid FEM/ MoM technique. Using the rational function approximation, the electric field is obtained over a frequency range. Using the electric field at different frequencies, the input characteristics of the antenna are obtained over a wide frequency range. Numerical results for an open coaxial line, probe-fed coaxial cavity and cavity-backed microstrip patch antennas are presented. Good agreement between MBPE and the solutions over individual frequencies is observed.

  3. Evaluation of Fast-Time Wake Vortex Prediction Models

    NASA Technical Reports Server (NTRS)

    Proctor, Fred H.; Hamilton, David W.

    2009-01-01

    Current fast-time wake models are reviewed and three basic types are defined. Predictions from several of the fast-time models are compared. Previous statistical evaluations of the APA-Sarpkaya and D2P fast-time models are discussed. Root Mean Square errors between fast-time model predictions and Lidar wake measurements are examined for a 24 hr period at Denver International Airport. Shortcomings in current methodology for evaluating wake errors are also discussed.

  4. Resist profile simulation with fast lithography model

    NASA Astrophysics Data System (ADS)

    He, Yan-Ying; Chou, Chih-Shiang; Tang, Yu-Po; Huang, Wen-Chun; Liu, Ru-Gun; Gau, Tsai-Sheng

    2014-03-01

    A traditional approach to construct a fast lithographic model is to match wafer top-down SEM images, contours and/or gauge CDs with a TCC model plus some simple resist representation. This modeling method has been proven and is extensively used for OPC modeling. As the technology moves forward, this traditional approach has become insufficient in regard to lithography weak point detection, etching bias prediction, etc. The drawback of this approach is from metrology and simulation. First, top-down SEM is only good for acquiring planar CD information. Some 3D metrology such as cross-section SEM or AFM is necessary to obtain the true resist profile. Second, the TCC modeling approach is only suitable for planar image simulation. In order to model the resist profile, full 3D image simulation is needed. Even though there are many rigorous simulators capable of catching the resist profile very well, none of them is feasible for full-chip application due to the tremendous consumption of computational resource. The authors have proposed a quasi-3D image simulation method in the previous study [1], which is suitable for full-chip simulation with the consideration of sidewall angles, to improve the model accuracy of planar models. In this paper, the quasi-3D image simulation is extended to directly model the resist profile with AFM and/or cross-section SEM data. Resist weak points detected by the model generated with this 3D approach are verified on the wafer.

  5. Fast Vegetational Responses to Late-Glacial Climate Change

    NASA Astrophysics Data System (ADS)

    Williams, J. W.; Post, D. M.; Cwynar, L. C.; Lotter, A. F.; Levesque, A. J.

    2001-12-01

    How rapidly can natural ecosystems respond to rapid climate change? This question can be addressed by studying paired paleoecological and paleoclimatological records spanning the last deglaciation. Between 16 and 10 ka, abrupt climatic oscillations (e.g. Younger Dryas, Gerzensee/Killarney Oscillations) interrupted the general warming trend. Rates of climate change during these events were as fast or faster than projected rates of change for this century. We compiled a dozen high-resolution lacustrine records in North America and Europe with a pollen record and independent climatic proxy, a clear Younger Dryas signal, and good age control. Cross-correlation analysis suggests that vegetation responded rapidly to late-glacial climate change, with significant changes in vegetation composition occurring within the lifespan of individual trees. At all sites, vegetation lagged climate by less than 200 years, and at two-thirds of the sites, the initial vegetational response occurred within 100 years. The finding of rapid vegetational responses is consistent across sites and continents, and is similar to the 100-200 year response times predicted by gap-scale forest models. Likely mechanisms include 1) increased susceptibility of mature trees to disturbances such as fire, wind, and disease, thereby opening up gaps for colonization, 2) the proximity of these sites to late-glacial treeline, where climate may directly control plant population densities and range limits, 3) the presence of herbaceous taxa with short generation times in these plant communities, and 4) rapid migration due to rare long-distance seed dispersals. Our results are consistent with reports that plant ranges are already shifting in response to recent climate change, and suggest that these shifts will persist for the next several centuries. Widespread changes in plant distributions may affect surface-atmosphere interactions and will challenge attempts to manage ecosystems and conserve biodiversity.

  6. Portion sizes and obesity: responses of fast-food companies.

    PubMed

    Young, Lisa R; Nestle, Marion

    2007-07-01

    Because the sizes of food portions, especially of fast food, have increased in parallel with rising rates of overweight, health authorities have called on fast-food chains to decrease the sizes of menu items. From 2002 to 2006, we examined responses of fast-food chains to such calls by determining the current sizes of sodas, French fries, and hamburgers at three leading chains and comparing them to sizes observed in 1998 and 2002. Although McDonald's recently phased out its largest offerings, current items are similar to 1998 sizes and greatly exceed those offered when the company opened in 1955. Burger King and Wendy's have increased portion sizes, even while health authorities are calling for portion size reductions. Fast-food portions in the United States are larger than in Europe. These observations suggest that voluntary efforts by fast-food companies to reduce portion sizes are unlikely to be effective, and that policy approaches are needed to reduce energy intake from fast food.

  7. Inductor flyback characteristic gives voltage regulator fast response

    NASA Technical Reports Server (NTRS)

    Smith, G. D.

    1965-01-01

    Voltage regulator alternately connects an inductor in parallel and in series with the input voltage source. This flyback voltage regulator provides a regulated dc voltage to varying loads from a varying dc supply and gives fast response to load and supply changes.

  8. Evaluation of gastric processing and duodenal digestion of starch in six cereal meals on the associated glycaemic response using an adult fasted dynamic gastric model.

    PubMed

    Ballance, Simon; Sahlstrøm, Stefan; Lea, Per; Nagy, Nina E; Andersen, Petter V; Dessev, Tzvetelin; Hull, Sarah; Vardakou, Maria; Faulks, Richard

    2013-03-01

    To identify the key parameters involved in cereal starch digestion and associated glycaemic response by the utilisation of a dynamic gastro-duodenal digestion model. Potential plasma glucose loading curves for each meal were calculated and fitted to an exponential function. The area under the curve (AUC) from 0 to 120 min and total digestible starch was used to calculate an in vitro glycaemic index (GI) value normalised against white bread. Microscopy was additionally used to examine cereal samples collected in vitro at different stages of gastric and duodenal digestion. Where in vivo GI data were available (4 out of 6 cereal meals) no significant difference was observed between these values and the corresponding calculated in vitro GI value. It is possible to simulate an in vivo glycaemic response for cereals when the gastric emptying rate (duodenal loading) and kinetics of digestible starch hydrolysis in the duodenum are known.

  9. Impact of Active Control on Passive Safety Response Characteristics of Sodium-Cooled Fast Reactors: II-Model Implementation and Simulations

    DOE PAGES

    Ponciroli, Roberto; Passerini, Stefano; Vilim, Richard B.

    2017-06-21

    Advanced reactors are often claimed to be passively safe against unprotected upset events. In common practice, these events are not considered in the context of the plant control system, i.e., the reactor is subjected to classes of unprotected upset events while the normally programmed response of the control system is assumed not to be present. However, this approach constitutes an oversimplification since, depending on the upset involving the control system, an actuator does not necessarily go in the same direction as needed for safety. In this work, dynamic simulations are performed to assess the degree to which the inherent self-regulatingmore » plant response is safe from active control system override. The simulations are meant to characterize the resilience of the plant to unprotected initiators. The initiators were represented and modeled as an actuator going to a hard limit. Consideration of failure is further limited to individual controllers as there is no cross-connect of signals between these controllers. The potential for passive safety override by the control system is then relegated to the single-input single-output controllers. Here, the results show that when the plant control system is designed by taking into account and quantifying the impact of the plant control system on accidental scenarios there is very limited opportunity for the preprogrammed response of the control system to override passive safety protection in the event of an unprotected initiator.« less

  10. A fast, angle-dependent, analytical model of CsI detector response for optimization of 3D x-ray breast imaging systems.

    PubMed

    Freed, Melanie; Park, Subok; Badano, Aldo

    2010-06-01

    Accurate models of detector blur are crucial for performing meaningful optimizations of three-dimensional (3D) x-ray breast imaging systems as well as for developing reconstruction algorithms that faithfully reproduce the imaged object anatomy. So far, x-ray detector blur has either been ignored or modeled as a shift-invariant symmetric function for these applications. The recent development of a Monte Carlo simulation package called MANTIS has allowed detailed modeling of these detector blur functions and demonstrated the magnitude of the anisotropy for both tomosynthesis and breast CT imaging systems. Despite the detailed results that MANTIS produces, the long simulation times required make inclusion of these results impractical in rigorous optimization and reconstruction algorithms. As a result, there is a need for detector blur models that can be rapidly generated. In this study, the authors have derived an analytical model for deterministic detector blur functions, referred to here as point response functions (PRFs), of columnar CsI phosphor screens. The analytical model is x-ray energy and incidence angle dependent and draws on results from MANTIS to indirectly include complicated interactions that are not explicitly included in the mathematical model. Once the mathematical expression is derived, values of the coefficients are determined by a two-dimensional (2D) fit to MANTIS-generated results based on a figure-of-merit (FOM) that measures the normalized differences between the MANTIS and analytical model results averaged over a region of interest. A smaller FOM indicates a better fit. This analysis was performed for a monochromatic x-ray energy of 25 keV, a CsI scintillator thickness of 150 microm, and four incidence angles (0 degrees, 15 degrees, 30 degrees, and 45 degrees). The FOMs comparing the analytical model to MANTIS for these parameters were 0.1951 +/- 0.0011, 0.1915 +/- 0.0014, 0.2266 +/- 0.0021, and 0.2416 +/- 0.0074 for 0 degrees, 15 degrees, 30

  11. A fast, angle-dependent, analytical model of CsI detector response for optimization of 3D x-ray breast imaging systems.

    PubMed

    Freed, Melanie; Park, Subok; Badano, Aldo

    2010-06-01

    Accurate models of detector blur are crucial for performing meaningful optimizations of three-dimensional (3D) x-ray breast imaging systems as well as for developing reconstruction algorithms that faithfully reproduce the imaged object anatomy. So far, x-ray detector blur has either been ignored or modeled as a shift-invariant symmetric function for these applications. The recent development of a Monte Carlo simulation package called MANTIS has allowed detailed modeling of these detector blur functions and demonstrated the magnitude of the anisotropy for both tomosynthesis and breast CT imaging systems. Despite the detailed results that MANTIS produces, the long simulation times required make inclusion of these results impractical in rigorous optimization and reconstruction algorithms. As a result, there is a need for detector blur models that can be rapidly generated. In this study, the authors have derived an analytical model for deterministic detector blur functions, referred to here as point response functions (PRFs), of columnar CsI phosphor screens. The analytical model is x-ray energy and incidence angle dependent and draws on results from MANTIS to indirectly include complicated interactions that are not explicitly included in the mathematical model. Once the mathematical expression is derived, values of the coefficients are determined by a two-dimensional (2D) fit to MANTIS-generated results based on a figure-of-merit (FOM) that measures the normalized differences between the MANTIS and analytical model results averaged over a region of interest. A smaller FOM indicates a better fit. This analysis was performed for a monochromatic x-ray energy of 25 keV, a CsI scintillator thickness of 150μm, and four incidence angles (0°, 15°, 30°, and 45°). The FOMs comparing the analytical model to MANTIS for these parameters were 0.1951±0.0011, 0.1915±0.0014, 0.2266±0.0021, and 0.2416±0.0074 for 0°, 15°, 30°, and 45°, respectively. As a comparison, the

  12. Energy Expenditure Responses to Fasting and Overfeeding Identify Phenotypes Associated With Weight Change

    PubMed Central

    Schlögl, Mathias; Pannacciuli, Nicola; Bonfiglio, Susan M.; Krakoff, Jonathan; Thearle, Marie S.

    2015-01-01

    Because it is unknown whether 24-h energy expenditure (EE) responses to dietary extremes will identify phenotypes associated with weight regulation, the aim of this study was to determine whether such responses to fasting or overfeeding are associated with future weight change. The 24-h EE during energy balance, fasting, and four different overfeeding diets with 200% energy requirements was measured in a metabolic chamber in 37 subjects with normal glucose regulation while they resided on our clinical research unit. Diets were given for 24 h each and included the following: 1) low protein (3%), 2) standard (50% carbohydrate, 20% protein), 3) high fat (60%), and 4) high carbohydrate (75%). Participants returned for follow-up 6 months after the initial measures. The decrease in 24-h EE during fasting and the increase with overfeeding were correlated. A larger reduction in EE during fasting, a smaller EE response to low-protein overfeeding, and a larger response to high-carbohydrate overfeeding all correlated with weight gain. The association of the fasting EE response with weight change was not independent from that of low protein in a multivariate model. We identified the following two independent propensities associated with weight gain: a predilection for conserving energy during caloric and protein deprivation and a profligate response to large amounts of carbohydrates. PMID:26185280

  13. Energy Expenditure Responses to Fasting and Overfeeding Identify Phenotypes Associated With Weight Change.

    PubMed

    Schlögl, Mathias; Piaggi, Paolo; Pannacciuli, Nicola; Bonfiglio, Susan M; Krakoff, Jonathan; Thearle, Marie S

    2015-11-01

    Because it is unknown whether 24-h energy expenditure (EE) responses to dietary extremes will identify phenotypes associated with weight regulation, the aim of this study was to determine whether such responses to fasting or overfeeding are associated with future weight change. The 24-h EE during energy balance, fasting, and four different overfeeding diets with 200% energy requirements was measured in a metabolic chamber in 37 subjects with normal glucose regulation while they resided on our clinical research unit. Diets were given for 24 h each and included the following: (1) low protein (3%), (2) standard (50% carbohydrate, 20% protein), (3) high fat (60%), and (4) high carbohydrate (75%). Participants returned for follow-up 6 months after the initial measures. The decrease in 24-h EE during fasting and the increase with overfeeding were correlated. A larger reduction in EE during fasting, a smaller EE response to low-protein overfeeding, and a larger response to high-carbohydrate overfeeding all correlated with weight gain. The association of the fasting EE response with weight change was not independent from that of low protein in a multivariate model. We identified the following two independent propensities associated with weight gain: a predilection for conserving energy during caloric and protein deprivation and a profligate response to large amounts of carbohydrates.

  14. A fast and flexible reactor physics model for simulating neutron spectra and depletion in fast reactors

    NASA Astrophysics Data System (ADS)

    Recktenwald, Geoff; Deinert, Mark

    2010-03-01

    Determining the time dependent concentration of isotopes within a nuclear reactor core is central to the analysis of nuclear fuel cycles. We present a fast, flexible tool for determining the time dependent neutron spectrum within fast reactors. The code (VBUDS: visualization, burnup, depletion and spectra) uses a two region, multigroup collision probability model to simulate the energy dependent neutron flux and tracks the buildup and burnout of 24 actinides, as well as fission products. While originally developed for LWR simulations, the model is shown to produce fast reactor spectra that show high degree of fidelity to available fast reactor benchmarks.

  15. Fast response pyroelectric detector-preamplifier assembled device

    NASA Astrophysics Data System (ADS)

    Bai, PiJi; Tai, Yunjian; Liu, Huiping

    2008-03-01

    The pyroelectric detector is wide used for its simple structure and high performance to price ratio. It has been used in thermal detecting, infrared spectrum and laser testing. When the pyroelectric detector was applied in practice, fast reponse speed is need. For improving the response speed of the pyroelectric detector some specific technology has been used in the preamplifier schematic. High sense and fast response character of the pyroelectric detector-preamplifier assembled device had been achieved. When the device is applied in acute concussion condition, it must survive from the acute concussion condition testing. For it reliability some specific technology was used in the device fabricating procedure. At last the performance parameter testing result and simulation application condition result given in this paper show the performance of the pyroelectric detector-preamplifier assembled device had achieved the advance goal.

  16. New CO2 Sensor with High Resolution and Fast Response

    DTIC Science & Technology

    2007-11-02

    colorimetry [7]. The dominant gas phase principle is Nondispersive Infrared Sprectroscopy ( NDIR ) [8], based on specific absorption at the 4.23 µm band...to the list of important characteristics is made in Table 1. The scaling properties are favorable for all principles except NDIR . The relatively...accuracy or response time. The accuracy of the pH-based methods is limited [12], whereas all methods except possibly the NDIR have capability of fast

  17. Applying a 4D multiscale in vivo tumor growth model to the exploration of radiotherapy scheduling: The effects of weekend treatment gaps and p53 gene status on the response of fast growing solid tumors

    PubMed Central

    Dionysiou, Dimitra D.; Stamatakos, Georgios S.

    2006-01-01

    The present paper aims at demonstrating clinically oriented applications of the multiscale four dimensional in vivo tumor growth simulation model previously developed by our research group. To this end the effect of weekend radiotherapy treatment gaps and p53 gene status on two virtual glioblastoma tumors differing only in p53 gene status is investigated in silico. Tumor response predictions concerning two rather extreme dose fractionation schedules (daily dose of 4.5 Gy administered in 3 equal fractions) namely HART (Hyperfractionated Accelerated Radiotherapy weekend less) 54 Gy and CHART (Continuous HART) 54 Gy are presented and compared. The model predictions suggest that, for the same p53 status, HART 54 Gy and CHART 54 Gy have almost the same long term effects on locoregional tumor control. However, no data have been located in the literature concerning a comparison of HART and CHART radiotherapy schedules for glioblastoma. As non small cell lung carcinoma (NSCLC) may also be a fast growing and radiosensitive tumor, a comparison of the model predictions with the outcome of clinical studies concerning the response of NSCLC to HART 54 Gy and CHART 54 Gy is made. The model predictions are in accordance with corresponding clinical observations, thus strengthening the potential of the model. PMID:19458763

  18. Fast-response LCDs for virtual reality applications

    NASA Astrophysics Data System (ADS)

    Chen, Haiwei; Peng, Fenglin; Gou, Fangwang; Wand, Michael; Wu, Shin-Tson

    2017-02-01

    We demonstrate a fast-response liquid crystal display (LCD) with an ultra-low-viscosity nematic LC mixture. The measured average motion picture response time is only 6.88 ms, which is comparable to 6.66 ms for an OLED at a 120 Hz frame rate. If we slightly increase the TFT frame rate and/or reduce the backlight duty ratio, image blurs can be further suppressed to unnoticeable level. Potential applications of such an image-blur-free LCD for virtual reality, gaming monitors, and TVs are foreseeable.

  19. Quark nova model for fast radio bursts

    NASA Astrophysics Data System (ADS)

    Shand, Zachary; Ouyed, Amir; Koning, Nico; Ouyed, Rachid

    2016-05-01

    Fast radio bursts (FRBs) are puzzling, millisecond, energetic radio transients with no discernible source; observations show no counterparts in other frequency bands. The birth of a quark star from a parent neutron star experiencing a quark nova - previously thought undetectable when born in isolation - provides a natural explanation for the emission characteristics of FRBs. The generation of unstable r-process elements in the quark nova ejecta provides millisecond exponential injection of electrons into the surrounding strong magnetic field at the parent neutron star's light cylinder via β-decay. This radio synchrotron emission has a total duration of hundreds of milliseconds and matches the observed spectrum while reducing the inferred dispersion measure by approximately 200 cm-3 pc. The model allows indirect measurement of neutron star magnetic fields and periods in addition to providing astronomical measurements of β-decay chains of unstable neutron rich nuclei. Using this model, we can calculate expected FRB average energies (˜ 1041 erg) and spectral shapes, and provide a theoretical framework for determining distances.

  20. Acute metabolic response to fasted and postprandial exercise

    PubMed Central

    de Lima, Filipe Dinato; Correia, Ana Luiza Matias; Teixeira, Denilson da Silva; da Silva Neto, Domingos Vasco; Fernandes, Ítalo Sávio Gonçalves; Viana, Mário Boratto Xavier; Petitto, Mateus; da Silva Sampaio, Rodney Antônio; Chaves, Sandro Nobre; Alves, Simone Teixeira; Dantas, Renata Aparecida Elias; Mota, Márcio Rabelo

    2015-01-01

    The aim of this study was to analyze the acute metabolic response to exercise in fasting and postprandial. For this, ten individuals were submitted to an incremental treadmill test, with an initial speed of 5 and 1 km/h increments every minute, with no inclination, and a body composition assessment. After this 1st day, all volunteers were submitted to two experimental procedures (fasting and postprandial), with an aerobic exercise performed for 36 minutes at 65% of maximal oxygen consumption. At postprandial procedure, all subjects ingested a breakfast containing 59.3 g of carbohydrate (76.73%), 9.97 g of protein (12.90%), 8.01 g of lipids (10.37%), with a total energy intake of 349.17 kcal. An analysis of plasma concentration of triglycerides, lactate, and glucose was performed in two stages: before and after exercise. The Shapiro–Wilk test was used to verify the normality of the data. For analysis of glucose concentration, plasma lactate, and triglycerides, we used a repeated measures analysis of variance factorial 2×2, with Bonferroni multiple comparison test. The significance level of P<0.05 was adopted. The results indicated a maintenance level of glucose at fasting and a decrease in glucose concentration at postprandial exercise. Both conditions increase plasma lactate. Triglycerides also increased in the two experimental conditions; however, after exercise fasting, the increase was significantly higher than in the postprandial exercise. These data suggest that both exercises could increase plasma lactate and triglycerides. However, exercise performed in fasting condition decreases glucose concentration and increases triglycerides, even more than postprandial exercise. PMID:26316800

  1. Fast Photoconductive Responses in Organometal Halide Perovskite Photodetectors.

    PubMed

    Wang, Fei; Mei, Jingjing; Wang, Yunpeng; Zhang, Ligong; Zhao, Haifeng; Zhao, Dongxu

    2016-02-03

    Inorganic semiconductor-based photodetectors have been suffering from slow response speeds, which are caused by the persistent photoconductivity of semiconductor materials. For realizing high speed optoelectronic devices, the organometal halide perovskite thin films were applied onto the interdigitated (IDT) patterned Au electrodes, and symmetrical structured photoconductive detectors were achieved. The detectors were sensitive to the incident light signals, and the photocurrents of the devices were 2-3 orders of magnitude higher than dark currents. The responsivities of the devices could reach up to 55 mA W(1-). Most importantly, the detectors have a fast response time of less than 20 μs. The light and bias induced dipole rearrangement in organometal perovskite thin films has resulted in the instability of photocurrents, and Ag nanowires could quicken the process of dipole alignment and stabilize the photocurrents of the devices.

  2. Advances in Fast Response Acoustically Derived Air Temperature Measurements

    NASA Astrophysics Data System (ADS)

    Bogoev, Ivan; Jacobsen, Larry; Horst, Thomas; Conrad, Benjamin

    2016-04-01

    Fast-response accurate air-temperature measurements are required when estimating turbulent fluxes of heat, water and carbon dioxide by open-path eddy-covariance technique. In comparison with contact thermometers like thermocouples, ultra-sonic thermometers do not suffer from solar radiation loading, water vapor condensation and evaporative cooling effects. Consequently they have the potential to provide more accurate true air temperature measurements. The absolute accuracy of the ultrasonic thermometer is limited by the following parameters: the distance between the transducer pairs, transducer delays associated with the electrical-acoustic signal conversion that vary with temperature, components of the wind vector that are normal to the ultrasonic paths, and humidity. The distance between the transducer pairs is commonly obtained by coordinate measuring machine. Improved accuracy demonstrated in this study results from increased stiffness in the anemometer head to better maintain the ultrasonic path-length distances. To further improve accuracy and account for changes in transducer delays and distance as a function of temperature, these parameters are characterized in a zero-wind chamber over the entire operating temperature range. When the sonic anemometer is combined with a co-located fast-response water vapor analyzer, like in the IRGASON instrument, speed of sound can be compensated for humidity effects on a point-by-point basis resulting in a true fast-response air temperature measurement. Laboratory test results show that when the above steps are implemented in the calibration of the ultrasonic thermometer air-temperature accuracy better than ±0.5 degrees Celsius can be achieved over the entire operating range. The approach is also validated in a field inter-comparison with an aspirated thermistor probe mounted in a radiation shield.

  3. A surface ice module for wind turbine dynamic response simulation using FAST

    DOE PAGES

    Yu, Bingbin; Karr, Dale G.; Song, Huimin; ...

    2016-06-03

    It is a fact that developing offshore wind energy has become more and more serious worldwide in recent years. Many of the promising offshore wind farm locations are in cold regions that may have ice cover during wintertime. The challenge of possible ice loads on offshore wind turbines raises the demand of modeling capacity of dynamic wind turbine response under the joint action of ice, wind, wave, and current. The simulation software FAST is an open source computer-aided engineering (CAE) package maintained by the National Renewable Energy Laboratory. In this paper, a new module of FAST for assessing the dynamicmore » response of offshore wind turbines subjected to ice forcing is presented. In the ice module, several models are presented which involve both prescribed forcing and coupled response. For conditions in which the ice forcing is essentially decoupled from the structural response, ice forces are established from existing models for brittle and ductile ice failure. For conditions in which the ice failure and the structural response are coupled, such as lock-in conditions, a rate-dependent ice model is described, which is developed in conjunction with a new modularization framework for FAST. In this paper, analytical ice mechanics models are presented that incorporate ice floe forcing, deformation, and failure. For lower speeds, forces slowly build until the ice strength is reached and ice fails resulting in a quasi-static condition. For intermediate speeds, the ice failure can be coupled with the structural response and resulting in coinciding periods of the ice failure and the structural response. A third regime occurs at high speeds of encounter in which brittle fracturing of the ice feature occurs in a random pattern, which results in a random vibration excitation of the structure. An example wind turbine response is simulated under ice loading of each of the presented models. This module adds to FAST the capabilities for analyzing the response of wind

  4. A surface ice module for wind turbine dynamic response simulation using FAST

    SciTech Connect

    Yu, Bingbin; Karr, Dale G.; Song, Huimin; Sirnivas, Senu

    2016-06-03

    It is a fact that developing offshore wind energy has become more and more serious worldwide in recent years. Many of the promising offshore wind farm locations are in cold regions that may have ice cover during wintertime. The challenge of possible ice loads on offshore wind turbines raises the demand of modeling capacity of dynamic wind turbine response under the joint action of ice, wind, wave, and current. The simulation software FAST is an open source computer-aided engineering (CAE) package maintained by the National Renewable Energy Laboratory. In this paper, a new module of FAST for assessing the dynamic response of offshore wind turbines subjected to ice forcing is presented. In the ice module, several models are presented which involve both prescribed forcing and coupled response. For conditions in which the ice forcing is essentially decoupled from the structural response, ice forces are established from existing models for brittle and ductile ice failure. For conditions in which the ice failure and the structural response are coupled, such as lock-in conditions, a rate-dependent ice model is described, which is developed in conjunction with a new modularization framework for FAST. In this paper, analytical ice mechanics models are presented that incorporate ice floe forcing, deformation, and failure. For lower speeds, forces slowly build until the ice strength is reached and ice fails resulting in a quasi-static condition. For intermediate speeds, the ice failure can be coupled with the structural response and resulting in coinciding periods of the ice failure and the structural response. A third regime occurs at high speeds of encounter in which brittle fracturing of the ice feature occurs in a random pattern, which results in a random vibration excitation of the structure. An example wind turbine response is simulated under ice loading of each of the presented models. This module adds to FAST the capabilities for analyzing the response of wind

  5. A surface ice module for wind turbine dynamic response simulation using FAST

    SciTech Connect

    Yu, Bingbin; Karr, Dale G.; Song, Huimin; Sirnivas, Senu

    2016-06-03

    It is a fact that developing offshore wind energy has become more and more serious worldwide in recent years. Many of the promising offshore wind farm locations are in cold regions that may have ice cover during wintertime. The challenge of possible ice loads on offshore wind turbines raises the demand of modeling capacity of dynamic wind turbine response under the joint action of ice, wind, wave, and current. The simulation software FAST is an open source computer-aided engineering (CAE) package maintained by the National Renewable Energy Laboratory. In this paper, a new module of FAST for assessing the dynamic response of offshore wind turbines subjected to ice forcing is presented. In the ice module, several models are presented which involve both prescribed forcing and coupled response. For conditions in which the ice forcing is essentially decoupled from the structural response, ice forces are established from existing models for brittle and ductile ice failure. For conditions in which the ice failure and the structural response are coupled, such as lock-in conditions, a rate-dependent ice model is described, which is developed in conjunction with a new modularization framework for FAST. In this paper, analytical ice mechanics models are presented that incorporate ice floe forcing, deformation, and failure. For lower speeds, forces slowly build until the ice strength is reached and ice fails resulting in a quasi-static condition. For intermediate speeds, the ice failure can be coupled with the structural response and resulting in coinciding periods of the ice failure and the structural response. A third regime occurs at high speeds of encounter in which brittle fracturing of the ice feature occurs in a random pattern, which results in a random vibration excitation of the structure. An example wind turbine response is simulated under ice loading of each of the presented models. This module adds to FAST the capabilities for analyzing the response of wind

  6. Fast responsive, optical trace level ammonia sensor for environmental monitoring

    PubMed Central

    2012-01-01

    Background Ammonia is a ubiquitous chemical substance which is created in technical and biological processes and harmful to many different organisms. One specific problem is the toxicity of ammonia in fish at levels of 25 μg/l - a very common issue in today’s aqua culture. In this study we report a development of a fast responsive, optical ammonia sensor for trace concentrations. Results Different hydrogels have been investigated as host polymers for a pH based sensing mechanism based on fluorescent dyes. A porous hydrophobic fluoropolymer membrane was used as an ion barrier cover layer to achieve a good ammonia permeability. The sensor’s sensitivity towards ammonia as well as crosssensitivity towards pH-value and salinity, and the temperature dependency have been determined. Two different methods to reference fluorescence signals have been employed to eliminate intensity-based measurement drawbacks. Conclusion The presented sensor features high sensitivity and a fast response even at concentrations near 1 ppb. No cross sensitivity towards pH and salinity could be observed and temperature dependency was determined as compensateable. Both referencing approaches prove themselves to be able to provide a simple use of the sensor for in-field applications. PMID:23101725

  7. Sea-level response to melting of Antarctic ice shelves on multi-centennial timescales with the fast Elementary Thermomechanical Ice Sheet model (f.ETISh v1.0)

    NASA Astrophysics Data System (ADS)

    Pattyn, Frank

    2017-08-01

    The magnitude of the Antarctic ice sheet's contribution to global sea-level rise is dominated by the potential of its marine sectors to become unstable and collapse as a response to ocean (and atmospheric) forcing. This paper presents Antarctic sea-level response to sudden atmospheric and oceanic forcings on multi-centennial timescales with the newly developed fast Elementary Thermomechanical Ice Sheet (f.ETISh) model. The f.ETISh model is a vertically integrated hybrid ice sheet-ice shelf model with vertically integrated thermomechanical coupling, making the model two-dimensional. Its marine boundary is represented by two different flux conditions, coherent with power-law basal sliding and Coulomb basal friction. The model has been compared to existing benchmarks. Modelled Antarctic ice sheet response to forcing is dominated by sub-ice shelf melt and the sensitivity is highly dependent on basal conditions at the grounding line. Coulomb friction in the grounding-line transition zone leads to significantly higher mass loss in both West and East Antarctica on centennial timescales, leading to 1.5 m sea-level rise after 500 years for a limited melt scenario of 10 m a-1 under freely floating ice shelves, up to 6 m for a 50 m a-1 scenario. The higher sensitivity is attributed to higher ice fluxes at the grounding line due to vanishing effective pressure. Removing the ice shelves altogether results in a disintegration of the West Antarctic ice sheet and (partially) marine basins in East Antarctica. After 500 years, this leads to a 5 m and a 16 m sea-level rise for the power-law basal sliding and Coulomb friction conditions at the grounding line, respectively. The latter value agrees with simulations by DeConto and Pollard (2016) over a similar period (but with different forcing and including processes of hydrofracturing and cliff failure). The chosen parametrizations make model results largely independent of spatial resolution so that f.ETISh can potentially be

  8. Interorgan Coordination of the Murine Adaptive Response to Fasting*

    PubMed Central

    Hakvoort, Theodorus B. M.; Moerland, Perry D.; Frijters, Raoul; Sokolović, Aleksandar; Labruyère, Wilhelmina T.; Vermeulen, Jacqueline L. M.; Ver Loren van Themaat, Emiel; Breit, Timo M.; Wittink, Floyd R. A.; van Kampen, Antoine H. C.; Verhoeven, Arthur J.; Lamers, Wouter H.; Sokolović, Milka

    2011-01-01

    Starvation elicits a complex adaptive response in an organism. No information on transcriptional regulation of metabolic adaptations is available. We, therefore, studied the gene expression profiles of brain, small intestine, kidney, liver, and skeletal muscle in mice that were subjected to 0–72 h of fasting. Functional-category enrichment, text mining, and network analyses were employed to scrutinize the overall adaptation, aiming to identify responsive pathways, processes, and networks, and their regulation. The observed transcriptomics response did not follow the accepted “carbohydrate-lipid-protein” succession of expenditure of energy substrates. Instead, these processes were activated simultaneously in different organs during the entire period. The most prominent changes occurred in lipid and steroid metabolism, especially in the liver and kidney. They were accompanied by suppression of the immune response and cell turnover, particularly in the small intestine, and by increased proteolysis in the muscle. The brain was extremely well protected from the sequels of starvation. 60% of the identified overconnected transcription factors were organ-specific, 6% were common for 4 organs, with nuclear receptors as protagonists, accounting for almost 40% of all transcriptional regulators during fasting. The common transcription factors were PPARα, HNF4α, GCRα, AR (androgen receptor), SREBP1 and -2, FOXOs, EGR1, c-JUN, c-MYC, SP1, YY1, and ETS1. Our data strongly suggest that the control of metabolism in four metabolically active organs is exerted by transcription factors that are activated by nutrient signals and serves, at least partly, to prevent irreversible brain damage. PMID:21393243

  9. Interorgan coordination of the murine adaptive response to fasting.

    PubMed

    Hakvoort, Theodorus B M; Moerland, Perry D; Frijters, Raoul; Sokolović, Aleksandar; Labruyère, Wilhelmina T; Vermeulen, Jacqueline L M; Ver Loren van Themaat, Emiel; Breit, Timo M; Wittink, Floyd R A; van Kampen, Antoine H C; Verhoeven, Arthur J; Lamers, Wouter H; Sokolović, Milka

    2011-05-06

    Starvation elicits a complex adaptive response in an organism. No information on transcriptional regulation of metabolic adaptations is available. We, therefore, studied the gene expression profiles of brain, small intestine, kidney, liver, and skeletal muscle in mice that were subjected to 0-72 h of fasting. Functional-category enrichment, text mining, and network analyses were employed to scrutinize the overall adaptation, aiming to identify responsive pathways, processes, and networks, and their regulation. The observed transcriptomics response did not follow the accepted "carbohydrate-lipid-protein" succession of expenditure of energy substrates. Instead, these processes were activated simultaneously in different organs during the entire period. The most prominent changes occurred in lipid and steroid metabolism, especially in the liver and kidney. They were accompanied by suppression of the immune response and cell turnover, particularly in the small intestine, and by increased proteolysis in the muscle. The brain was extremely well protected from the sequels of starvation. 60% of the identified overconnected transcription factors were organ-specific, 6% were common for 4 organs, with nuclear receptors as protagonists, accounting for almost 40% of all transcriptional regulators during fasting. The common transcription factors were PPARα, HNF4α, GCRα, AR (androgen receptor), SREBP1 and -2, FOXOs, EGR1, c-JUN, c-MYC, SP1, YY1, and ETS1. Our data strongly suggest that the control of metabolism in four metabolically active organs is exerted by transcription factors that are activated by nutrient signals and serves, at least partly, to prevent irreversible brain damage.

  10. Physiological responses to feeding, fasting and estivation for anurans.

    PubMed

    Secor, Stephen M

    2005-07-01

    Anuran estivation is characterized by long episodes of aphagia. To investigate whether estivating anurans downregulate intestinal performance as an adaptive mechanism to reduce energy expenditure, I compared the metabolic and intestinal responses to feeding, fasting and estivation among non-estivating and estivating species of the anuran families Bufonidae, Leptodactylidae and Ranidae. Standard metabolic rates of the estivating Bufo alvarius, Ceratophrys ornata and Pyxicephalus adspersus were significantly less than those of the non-estivating Bufo marinus, Leptodactylus pentadactylus and Rana catesbeiana. Whereas the digestion of rodent meals equaling 15% of anuran body mass generated significant metabolic responses for all species, specific dynamic action was significantly greater for the estivating species. For estivating species, feeding triggered more than a doubling of small intestinal mass and significant upregulation of intestinal nutrient transport rates, resulting in six- to tenfold increases in total intestinal nutrient uptake capacity. The postprandial intestinal responses of the non-estivating species were much more modest, averaging a 50% increase in small intestinal mass and 69% increase in uptake capacities. Following 1 month of laboratory-induced estivation, C. ornata and P. adspersus had further depressed metabolic rates by 20%, intestinal masses by 44%, and total intestinal uptake capacities by 60%. In a fashion similar to infrequently feeding, sit-and-wait foraging snakes, estivating anurans possess the capacity to severely downregulate intestinal performance with fasting and estivation, and subsequently upregulate the gut with feeding. The depression in gut performance during estivation aids in reducing energy expenditure, thereby increasing the duration that the animal can remain dormant while relying solely upon stored energy.

  11. An application of fast response Polarized Light Microscopy

    NASA Astrophysics Data System (ADS)

    Kantha, Deependra; van Winkle, David

    2007-03-01

    A fast response polarized light microscope was designed based on the algorithm by Shribak et. al (Applied Optics, vol. 42, 3009-3017). A pulsed laser beam was passed through two Pockels cells aligned at different angles with respect to optical axis. The retardance of the Pockels cell was controlled by external switches and power supplies. The electronics circuit in the system allows change of the retardance of the Pockels cell each millisecond for four milliseconds. In four milliseconds, four images of a birefringent sample, formed by different states of polarized light are recorded. The images are added appropriately to calculate retardence amplitude and phase by using codes written in imageJ software. The microscope was used to show the retardance and phase of a rabbit muscle fiber. Recordings were also taken of the contraction of Vorticella convallaria but the changes were too fast to yield retardance images. This type of microscope can be used to study different kinds of biological functions that change on a timescale slower than four milliseconds but faster than two seconds.

  12. Rat psychomotor vigilance task with fast response times using a conditioned lick behavior

    PubMed Central

    Walker, Jennifer L.; Walker, Brendan M.; Fuentes, Fernanda Monjaraz; Rector, David M.

    2010-01-01

    Investigations into the physiological mechanisms of sleep control require an animal psychomotor vigilance task (PVT) with fast response times (<300ms). Rats provide a good PVT model since whisker stimulation produces a rapid and robust cortical evoked response, and animals can be trained to lick following stimulation. Our prior experiments used deprivation-based approaches to maximize motivation for operant conditioned responses. However, deprivation can influence physiological and neurobehavioral effects. In order to maintain motivation without water deprivation, we conditioned rats for immobilization and head restraint, then trained them to lick for a 10% sucrose solution in response to whisker stimulation. After approximately 8 training sessions, animals produced greater than 80% correct hits to the stimulus. Over the course of training, reaction times became faster and correct hits increased. Performance in the PVT was examined after 3, 6 and 12 hours of sleep deprivation achieved by gentle handling. A significant decrease in percent correct hits occurred following 6 and 12 hours of sleep deprivation and reaction times increased significantly following 12 hours of sleep deprivation. While behaviorally the animals appeared to be awake, we observed significant increases in EEG delta power prior to misses. The rat PVT with fast response times allows investigation of sleep deprivation effects, time on task and pharmacological agents. Fast response times also allow closer parallel studies to ongoing human protocols. PMID:20696188

  13. Fast novel nonlinear optical NLC system with local response

    NASA Astrophysics Data System (ADS)

    Iljin, Andrey; Residori, Stefania; Bortolozzo, Umberto

    2017-06-01

    Nonlinear optical performance of a novel liquid crystalline (LC) cell has been studied in two-wave mixing experiments revealing high diffraction efficiency within extremely wide intensity range, fast recording times and spatial resolution. Photo-induced modulation of the LC order parameter resulting from trans-cis isomerisation of dye molecules causes consequent changes of refractive indices of the medium (Light-Induced Order Modification, LIOM-mechanism) and is proved to be the main mechanism of optical nonlinearity. The proposed arrangement of the electric-field-stabilised homeotropic alignment hinders the LC director reorientation, prevents appearance of surface effects and ensures the optical cell quality. The LIOM-type nonlinearity, characterised with the substantially local nonlinear optical response, could also be extended for the recording of arbitrary phase profiles as requested in several applications for light-beam manipulation, recording of dynamic volume holograms and photonic lattices.

  14. PRMT5 modulates the metabolic response to fasting signals.

    PubMed

    Tsai, Wen-Wei; Niessen, Sherry; Goebel, Naomi; Yates, John R; Guccione, Ernesto; Montminy, Marc

    2013-05-28

    Under fasting conditions, increases in circulating glucagon maintain glucose balance by promoting hepatic gluconeogenesis. Triggering of the cAMP pathway stimulates gluconeogenic gene expression through the PKA-mediated phosphorylation of the cAMP response element binding (CREB) protein and via the dephosphorylation of the latent cytoplasmic CREB regulated transcriptional coactivator 2 (CRTC2). CREB and CRTC2 activities are increased in insulin resistance, in which they promote hyperglycemia because of constitutive induction of the gluconeogenic program. The extent to which CREB and CRTC2 are coordinately up-regulated in response to glucagon, however, remains unclear. Here we show that, following its activation, CRTC2 enhances CREB phosphorylation through an association with the protein arginine methyltransferase 5 (PRMT5). In turn, PRMT5 was found to stimulate CREB phosphorylation via increases in histone H3 Arg2 methylation that enhanced chromatin accessibility at gluconeogenic promoters. Because depletion of PRMT5 lowers hepatic glucose production and gluconeogenic gene expression, these results demonstrate how a chromatin-modifying enzyme regulates a metabolic program through epigenetic changes that impact the phosphorylation of a transcription factor in response to hormonal stimuli.

  15. General Graded Response Model.

    ERIC Educational Resources Information Center

    Samejima, Fumiko

    This paper describes the graded response model. The graded response model represents a family of mathematical models that deal with ordered polytomous categories, such as: (1) letter grading; (2) an attitude survey with "strongly disagree, disagree, agree, and strongly agree" choices; (3) partial credit given in accord with an…

  16. Fast and Slow Responses of the South Asian Monsoon System to Anthropogenic Aerosols

    SciTech Connect

    Ganguly, Dilip; Rasch, Philip J.; Wang, Hailong; Yoon, Jin-Ho

    2012-09-25

    Using a global climate model with fully predictive aerosol life cycle, we investigate the fast and slow responses of the South Asian monsoon system to anthropogenic aerosol forcing. Our results show that the feedbacks associated with sea surface temperature (SST) change caused by aerosols play a more important role than the aerosol's direct impact on radiation, clouds and land surface (rapid adjustments) in shaping the total equilibrium climate response of the monsoon system to aerosol forcing. Inhomogeneous SST cooling caused by anthropogenic aerosols eventually reduces the meridional tropospheric temperature gradient and the easterly shear of zonal winds over the region, slowing down the local Hadley cell circulation, decreasing the northward moisture transport, and causing a reduction in precipitation over South Asia. Although total responses in precipitation are closer to the slow responses in general, the fast component dominates over land areas north of 25°N. Our results also show an east-west asymmetry in the fast responses to anthropogenic aerosols causing increases in precipitation west of 80°E but decreases east of it.

  17. Fast and slow responses of the South Asian monsoon system to anthropogenic aerosols

    NASA Astrophysics Data System (ADS)

    Ganguly, Dilip; Rasch, Philip J.; Wang, Hailong; Yoon, Jin-ho

    2012-09-01

    Using a global climate model with fully predictive aerosol life cycle, we investigate the fast and slow responses of the South Asian monsoon system to anthropogenic aerosol forcing. Our results show that the feedbacks associated with sea surface temperature (SST) change caused by aerosols play a more important role than the aerosol's direct impact on radiation, clouds and land surface (rapid adjustments) in shaping the total equilibrium climate response of the monsoon system to aerosol forcing. Inhomogeneous SST cooling caused by anthropogenic aerosols eventually reduces the meridional tropospheric temperature gradient and the easterly shear of zonal winds over the region, slowing down the local Hadley cell circulation, decreasing the northward moisture transport, and causing a reduction in precipitation over South Asia. Although total responses in precipitation are closer to the slow responses in general, the fast component dominates over land areas north of 25°N. Our results also show an east-west asymmetry in the fast responses to anthropogenic aerosols causing increases in precipitation west of 80°E but decreases east of it.

  18. Fast-Response-Time Shape-Memory-Effect Foam Actuators

    NASA Technical Reports Server (NTRS)

    Jardine, Peter

    2010-01-01

    Bulk shape memory alloys, such as Nitinol or CuAlZn, display strong recovery forces undergoing a phase transformation after being strained in their martensitic state. These recovery forces are used for actuation. As the phase transformation is thermally driven, the response time of the actuation can be slow, as the heat must be passively inserted or removed from the alloy. Shape memory alloy TiNi torque tubes have been investigated for at least 20 years and have demonstrated high actuation forces [3,000 in.-lb (approximately equal to 340 N-m) torques] and are very lightweight. However, they are not easy to attach to existing structures. Adhesives will fail in shear at low-torque loads and the TiNi is not weldable, so that mechanical crimp fits have been generally used. These are not reliable, especially in vibratory environments. The TiNi is also slow to heat up, as it can only be heated indirectly using heater and cooling must be done passively. This has restricted their use to on-off actuators where cycle times of approximately one minute is acceptable. Self-propagating high-temperature synthesis (SHS) has been used in the past to make porous TiNi metal foams. Shape Change Technologies has been able to train SHS derived TiNi to exhibit the shape memory effect. As it is an open-celled material, fast response times were observed when the material was heated using hot and cold fluids. A methodology was developed to make the open-celled porous TiNi foams as a tube with integrated hexagonal ends, which then becomes a torsional actuator with fast response times. Under processing developed independently, researchers were able to verify torques of 84 in.-lb (approximately equal to 9.5 Nm) using an actuator weighing 1.3 oz (approximately equal to 37 g) with very fast (less than 1/16th of a second) initial response times when hot and cold fluids were used to facilitate heat transfer. Integrated structural connections were added as part of the net shape process, eliminating

  19. Fast Odor Learning Improves Reliability of Odor Responses in the Locust Antennal Lobe

    PubMed Central

    Bazhenov, Maxim; Stopfer, Mark; Sejnowski, Terrence J.; Laurent, Gilles

    2010-01-01

    Summary Recordings in the locust antennal lobe (AL) reveal activity-dependent, stimulus-specific changes in projection neuron (PN) and local neuron response patterns over repeated odor trials. During the first few trials, PN response intensity decreases, while spike time precision increases, and coherent oscillations, absent at first, quickly emerge. We examined this “fast odor learning” with a realistic computational model of the AL. Activity-dependent facilitation of AL inhibitory synapses was sufficient to simulate physiological recordings of fast learning. In addition, in experiments with noisy inputs, a network including synaptic facilitation of both inhibition and excitation responded with reliable spatiotemporal patterns from trial to trial despite the noise. A network lacking fast plasticity, however, responded with patterns that varied across trials, reflecting the input variability. Thus, our study suggests that fast olfactory learning results from stimulus-specific, activity-dependent synaptic facilitation and may improve the signal-to-noise ratio for repeatedly encountered odor stimuli. PMID:15882647

  20. Effect of Fasting on the Metabolic Response of Liver to Experimental Burn Injury

    PubMed Central

    Orman, Mehmet A.; Ierapetritou, Marianthi G.; Androulakis, Ioannis P.; Berthiaume, Francois

    2013-01-01

    Liver metabolism is altered after systemic injuries such as burns and trauma. These changes have been elucidated in rat models of experimental burn injury where the liver was isolated and perfused ex vivo. Because these studies were performed in fasted animals to deplete glycogen stores, thus simplifying quantification of gluconeogenesis, these observations reflect the combined impact of fasting and injury on liver metabolism. Herein we asked whether the metabolic response to experimental burn injury is different in fed vs. fasted animals. Rats were subjected to a cutaneous burn covering 20% of the total body surface area, or to similar procedures without administering the burn, hence a sham-burn. Half of the animals in the burn and sham-burn groups were fasted starting on postburn day 3, and the others allowed to continue ad libitum. On postburn day 4, livers were isolated and perfused for 1 hour in physiological medium supplemented with 10% hematocrit red blood cells. The uptake/release rates of major carbon and nitrogen sources, oxygen, and carbon dioxide were measured during the perfusion and the data fed into a mass balance model to estimate intracellular fluxes. The data show that in fed animals, injury increased glucose output mainly from glycogen breakdown and minimally impacted amino acid metabolism. In fasted animals, injury did not increase glucose output but increased urea production and the uptake of several amino acids, namely glutamine, arginine, glycine, and methionine. Furthermore, sham-burn animals responded to fasting by triggering gluconeogenesis from lactate; however, in burned animals the preferred gluconeogenic substrate was amino acids. Taken together, these results suggest that the fed state prevents the burn-induced increase in hepatic amino acid utilization for gluconeogenesis. The role of glycogen stores and means to increase and/or maintain internal sources of glucose to prevent increased hepatic amino acid utilization warrant further

  1. Gompertz kinetics model of fast chemical neurotransmission currents.

    PubMed

    Easton, Dexter M

    2005-10-01

    At a chemical synapse, transmitter molecules ejected from presynaptic terminal(s) bind reversibly with postsynaptic receptors and trigger an increase in channel conductance to specific ions. This paper describes a simple but accurate predictive model for the time course of the synaptic conductance transient, based on Gompertz kinetics. In the model, two simple exponential decay terms set the rates of development and decline of transmitter action. The first, r, triggering conductance activation, is surrogate for the decelerated rate of growth of conductance, G. The second, r', responsible for Y, deactivation of the conductance, is surrogate for the decelerated rate of decline of transmitter action. Therefore, the differential equation for the net conductance change, g, triggered by the transmitter is dg/dt=g(r-r'). The solution of that equation yields the product of G(t), representing activation, and Y(t), which defines the proportional decline (deactivation) of the current. The model fits, over their full-time course, published records of macroscopic ionic current associated with fast chemical transmission. The Gompertz model is a convenient and accurate method for routine analysis and comparison of records of synaptic current and putative transmitter time course. A Gompertz fit requiring only three independent rate constants plus initial current appears indistinguishable from a Markov fit using seven rate constants.

  2. EGR Control for Emisson Reduction Using Fast Response Sensors - Phase 1A

    SciTech Connect

    Gravel, Roland; Conley, Jason; Kittelson, David

    2008-09-30

    The overall objective of this project was to develop exhaust gas recirculation (EGR) control strategies using fast-response Particulate Matter (PM) sensors and NOx sensors to improve the quality of particulate and gaseous emissions from diesel engines. This project initially comprised three phases: (1) Phase IA - sensor requirements to meet PM sensor specifications, NOx sensor assessment, and initial model development for EGR control; (2) Phase IB - continue development on PM and NOx sensors, integrate the sensor signals into the control simulations, and finalize model development for control strategies; and (3) Phase II - validation testing of the control strategies. Only Phase 1A was funded by DOE and executed by Honeywell. The major objectives of Phase 1A of the project included: (1) Sensor validation and operation of fast-response PM and NOx sensors; (2) Control system modeling of low-pressure EGR controls, development of control strategies, and initial evaluation of these models and strategies for EGR control in diesel engines; (3) Sensor testing to understand applicability of fast-response PM sensors in determining loading rates of the particle trap; and (4) Model validation and sensor testing under steady-state and transient operational conditions of actual engines. In particular, specific objectives included demonstration of: (1) A PM sensor response time constant (T10 - T90) of better than 100 milliseconds (msec); (2) The ability to detect PM at concentrations from 0.2 to 2 Bosch smoke number (BSN) or equivalent; (3) PM sensor accuracy to within 20% BSN over the entire range of operation; and (4) PM sensor repeatability to within 10% over the PM entire sensor range equivalent to a BSN of 0.2 to 2.

  3. Development of a fast-response multi-hole probe for unsteady and turbulent flowfields

    NASA Astrophysics Data System (ADS)

    Johansen, Espen Sten

    The development of a fast-response aerodynamic probe calibration routine has been completed. This work includes the development of a theoretical probe and application and adaptation of potential flow theory to a fast-response 5-hole probe. Based on the theoretical probe, a procedure to determine the flow angles in flowfields with significant inertial effects was devised. It was further shown that this definition can be used to accurately predict the angles in flowfields with very high frequency oscillations (large inertial effects) over a wide range of flow incidence angles. The velocity magnitude was solved from the governing equation. This equation is a first-order, non-linear, ordinary differential equation, and a predictor-corrector method was formulated to calculate the velocity based on the measured port pressures. An experimental procedure to determine the steady and unsteady pressure coefficients was presented. The steady pressure coefficient is readily calculated from steady calibration data, but the determination of the unsteady coefficient requires a selective averaging procedure based on the rate-of-change parameter. A spherical probe with a fast-response pressure transducer was designed. The spherical probe was oscillated in water flow, and the coefficient determination procedure was experimentally verified. A facility was designed for the unsteady calibration of fast-response probes in air. This facility generates a repeatable velocity oscillation that is sinusoidal in nature with mean velocity up to Mach 0.5 and frequency up to 1.5 kHz. A fast-response 5-hole probe was developed that can resolve frequency content up to 20 kHz, and was used to verify the unsteady calibration routine. Several test cases were presented and excellent prediction capabilities were demonstrated. Acoustic pressure attenuation in the tubing systems for miniature multi-hole probes is discussed, and theoretical models are presented that determine the transfer function of such

  4. The CLYC-6 and CLYC-7 response to γ-rays, fast and thermal neutrons

    NASA Astrophysics Data System (ADS)

    Giaz, A.; Pellegri, L.; Camera, F.; Blasi, N.; Brambilla, S.; Ceruti, S.; Million, B.; Riboldi, S.; Cazzaniga, C.; Gorini, G.; Nocente, M.; Pietropaolo, A.; Pillon, M.; Rebai, M.; Tardocchi, M.

    2016-02-01

    The crystal Cs2LiYCl6:Ce (CLYC) is a very interesting scintillator material because of its good energy resolution and its capability to identify γ-rays and fast/thermal neutrons. The crystal Cs2LiYCl6:Ce contains 6Li and 35Cl isotopes, therefore, it is possible to detect thermal neutrons through the reaction 6Li(n, α)t while 35Cl ions allow to measure fast neutrons through the reactions 35Cl(n, p)35S and 35Cl(n, α)32P. In this work two CLYC 1″×1″ crystals were used: the first crystal, enriched with 6Li at 95% (CLYC-6) is ideal for thermal neutron measurements while the second one, enriched with 7Li at >99% (CLYC-7) is suitable for fast neutron measurements. The response of CLYC scintillators was measured with different PMT models: timing or spectroscopic, with borosilicate glass or quartz window. The energy resolution, the neutron-γ discrimination and the internal activity are discussed. The capability of CLYC scintillators to discriminate γ rays from neutrons was tested with both thermal and fast neutrons. The thermal neutrons were measured with both detectors, using an AmBe source. The measurements of fast neutrons were performed at the Frascati Neutron Generator facility (Italy) where a deuterium beam was accelerated on a deuterium or on a tritium target, providing neutrons of 2.5 MeV or 14.1 MeV, respectively. The different sensitivity to thermal and fast neutrons of a CLYC-6 and of a CLYC-7 was additionally studied.

  5. Merging Universal and Indicated Prevention Programs: The Fast Track Model

    PubMed Central

    2009-01-01

    Fast Track is a multisite, multicomponent preventive intervention for young children at high risk for long-term antisocial behavior. Based on a comprehensive developmental model, this intervention includes a universal-level classroom program plus social-skill training, academic tutoring, parent training, and home visiting to improve competencies and reduce problems in a high-risk group of children selected in kindergarten. The theoretical principles and clinical strategies utilized in the Fast Track Project are described to illustrate the interplay between basic developmental research, the understanding of risk and protective factors, and a research-based model of preventive intervention that integrates universal and indicated models of prevention. PMID:11125779

  6. The Case for Intelligent Propulsion Control for Fast Engine Response

    NASA Technical Reports Server (NTRS)

    Litt, Jonathan S.; Frederick, Dean K.; Guo, Ten-Huei

    2009-01-01

    Damaged aircraft have occasionally had to rely solely on thrust to maneuver as a consequence of losing hydraulic power needed to operate flight control surfaces. The lack of successful landings in these cases inspired research into more effective methods of utilizing propulsion-only control. That research demonstrated that one of the major contributors to the difficulty in landing is the slow response of the engines as compared to using traditional flight control. To address this, research is being conducted into ways of making the engine more responsive under emergency conditions. This can be achieved by relaxing controller limits, adjusting schedules, and/or redesigning the regulators to increase bandwidth. Any of these methods can enable faster response at the potential expense of engine life and increased likelihood of stall. However, an example sensitivity analysis revealed a complex interaction of the limits and the difficulty in predicting the way to achieve the fastest response. The sensitivity analysis was performed on a realistic engine model, and demonstrated that significantly faster engine response can be achieved compared to standard Bill of Material control. However, the example indicates the need for an intelligent approach to controller limit adjustment in order for the potential to be fulfilled.

  7. Contrasting Responses to Harvesting and Environmental Drivers of Fast and Slow Life History Species.

    PubMed

    Quetglas, Antoni; Rueda, Lucía; Alvarez-Berastegui, Diego; Guijarro, Beatriz; Massutí, Enric

    2016-01-01

    According to their main life history traits, organisms can be arranged in a continuum from fast (species with small body size, short lifespan and high fecundity) to slow (species with opposite characteristics). Life history determines the responses of organisms to natural and anthropogenic factors, as slow species are expected to be more sensitive than fast species to perturbations. Owing to their contrasting traits, cephalopods and elasmobranchs are typical examples of fast and slow strategies, respectively. We investigated the responses of these two contrasting strategies to fishing exploitation and environmental conditions (temperature, productivity and depth) using generalized additive models. Our results confirmed the foreseen contrasting responses of cephalopods and elasmobranchs to natural (environment) and anthropogenic (harvesting) influences. Even though a priori foreseen, we did expect neither the clear-cut differential responses between groups nor the homogeneous sensitivity to the same factors within the two taxonomic groups. Apart from depth, which affected both groups equally, cephalopods and elasmobranchs were exclusively affected by environmental conditions and fishing exploitation, respectively. Owing to its short, annual cycle, cephalopods do not have overlapping generations and consequently lack the buffering effects conferred by different age classes observed in multi-aged species such as elasmobranchs. We suggest that cephalopods are sensitive to short-term perturbations, such as seasonal environmental changes, because they lack this buffering effect but they are in turn not influenced by continuous, long-term moderate disturbances such as fishing because of its high population growth and turnover. The contrary would apply to elasmobranchs, whose multi-aged population structure would buffer the seasonal environmental effects, but they would display strong responses to uninterrupted harvesting due to its low population resilience. Besides

  8. Contrasting Responses to Harvesting and Environmental Drivers of Fast and Slow Life History Species

    PubMed Central

    Quetglas, Antoni; Rueda, Lucía; Alvarez-Berastegui, Diego; Guijarro, Beatriz; Massutí, Enric

    2016-01-01

    According to their main life history traits, organisms can be arranged in a continuum from fast (species with small body size, short lifespan and high fecundity) to slow (species with opposite characteristics). Life history determines the responses of organisms to natural and anthropogenic factors, as slow species are expected to be more sensitive than fast species to perturbations. Owing to their contrasting traits, cephalopods and elasmobranchs are typical examples of fast and slow strategies, respectively. We investigated the responses of these two contrasting strategies to fishing exploitation and environmental conditions (temperature, productivity and depth) using generalized additive models. Our results confirmed the foreseen contrasting responses of cephalopods and elasmobranchs to natural (environment) and anthropogenic (harvesting) influences. Even though a priori foreseen, we did expect neither the clear-cut differential responses between groups nor the homogeneous sensitivity to the same factors within the two taxonomic groups. Apart from depth, which affected both groups equally, cephalopods and elasmobranchs were exclusively affected by environmental conditions and fishing exploitation, respectively. Owing to its short, annual cycle, cephalopods do not have overlapping generations and consequently lack the buffering effects conferred by different age classes observed in multi-aged species such as elasmobranchs. We suggest that cephalopods are sensitive to short-term perturbations, such as seasonal environmental changes, because they lack this buffering effect but they are in turn not influenced by continuous, long-term moderate disturbances such as fishing because of its high population growth and turnover. The contrary would apply to elasmobranchs, whose multi-aged population structure would buffer the seasonal environmental effects, but they would display strong responses to uninterrupted harvesting due to its low population resilience. Besides

  9. A sex difference in the response to fasting.

    PubMed

    Zandian, Modjtaba; Ioakimidis, Ioannis; Bergh, Cecilia; Leon, Michael; Södersten, Per

    2011-07-06

    We determined whether women and men would alter their pattern of food intake after they had deprived themselves of food. We found that women consumed 12% less food after fasting and that men ate 28% more food after fasting. Serving more food on the test day did not increase food intake of women. Women, who ate at a nearly constant rate (linear eaters), consumed less food than those eating at an initially high speed which decreased over the course of the meal (decelerated eaters). Women decreased their food intake after fasting as their eating pattern became more linear. After fasting, men increased their food intake, and the rate at which they ate became more decelerated. Food intake of both women and men was normalized after fasting by providing feedback that encouraged them to eat according to the pattern they showed in the non-fasted condition. The results support the hypothesis that linear eating, and the dieting that elicits linear eating, are risk factors for the development of the abnormal linear eating pattern that characterizes patients with anorexia nervosa. The data also provide additional support for the use of behavioral feedback to normalize the pattern of eating for individuals who have difficulty maintaining their body weight.

  10. A Fast Incremental Gaussian Mixture Model

    PubMed Central

    Pinto, Rafael Coimbra; Engel, Paulo Martins

    2015-01-01

    This work builds upon previous efforts in online incremental learning, namely the Incremental Gaussian Mixture Network (IGMN). The IGMN is capable of learning from data streams in a single-pass by improving its model after analyzing each data point and discarding it thereafter. Nevertheless, it suffers from the scalability point-of-view, due to its asymptotic time complexity of O(NKD3) for N data points, K Gaussian components and D dimensions, rendering it inadequate for high-dimensional data. In this work, we manage to reduce this complexity to O(NKD2) by deriving formulas for working directly with precision matrices instead of covariance matrices. The final result is a much faster and scalable algorithm which can be applied to high dimensional tasks. This is confirmed by applying the modified algorithm to high-dimensional classification datasets. PMID:26444880

  11. Fast Algorithms for Model-Based Diagnosis

    NASA Technical Reports Server (NTRS)

    Fijany, Amir; Barrett, Anthony; Vatan, Farrokh; Mackey, Ryan

    2005-01-01

    Two improved new methods for automated diagnosis of complex engineering systems involve the use of novel algorithms that are more efficient than prior algorithms used for the same purpose. Both the recently developed algorithms and the prior algorithms in question are instances of model-based diagnosis, which is based on exploring the logical inconsistency between an observation and a description of a system to be diagnosed. As engineering systems grow more complex and increasingly autonomous in their functions, the need for automated diagnosis increases concomitantly. In model-based diagnosis, the function of each component and the interconnections among all the components of the system to be diagnosed (for example, see figure) are represented as a logical system, called the system description (SD). Hence, the expected behavior of the system is the set of logical consequences of the SD. Faulty components lead to inconsistency between the observed behaviors of the system and the SD. The task of finding the faulty components (diagnosis) reduces to finding the components, the abnormalities of which could explain all the inconsistencies. Of course, the meaningful solution should be a minimal set of faulty components (called a minimal diagnosis), because the trivial solution, in which all components are assumed to be faulty, always explains all inconsistencies. Although the prior algorithms in question implement powerful methods of diagnosis, they are not practical because they essentially require exhaustive searches among all possible combinations of faulty components and therefore entail the amounts of computation that grow exponentially with the number of components of the system.

  12. NASA AVOSS Fast-Time Wake Prediction Models: User's Guide

    NASA Technical Reports Server (NTRS)

    Ahmad, Nash'at N.; VanValkenburg, Randal L.; Pruis, Matthew

    2014-01-01

    The National Aeronautics and Space Administration (NASA) is developing and testing fast-time wake transport and decay models to safely enhance the capacity of the National Airspace System (NAS). The fast-time wake models are empirical algorithms used for real-time predictions of wake transport and decay based on aircraft parameters and ambient weather conditions. The aircraft dependent parameters include the initial vortex descent velocity and the vortex pair separation distance. The atmospheric initial conditions include vertical profiles of temperature or potential temperature, eddy dissipation rate, and crosswind. The current distribution includes the latest versions of the APA (3.4) and the TDP (2.1) models. This User's Guide provides detailed information on the model inputs, file formats, and the model output. An example of a model run and a brief description of the Memphis 1995 Wake Vortex Dataset is also provided.

  13. Reduced Fast Ion Transport Model For The Tokamak Transport Code TRANSP

    SciTech Connect

    Podesta,, Mario; Gorelenkova, Marina; White, Roscoe

    2014-02-28

    Fast ion transport models presently implemented in the tokamak transport code TRANSP [R. J. Hawryluk, in Physics of Plasmas Close to Thermonuclear Conditions, CEC Brussels, 1 , 19 (1980)] are not capturing important aspects of the physics associated with resonant transport caused by instabilities such as Toroidal Alfv en Eigenmodes (TAEs). This work describes the implementation of a fast ion transport model consistent with the basic mechanisms of resonant mode-particle interaction. The model is formulated in terms of a probability distribution function for the particle's steps in phase space, which is consistent with the MonteCarlo approach used in TRANSP. The proposed model is based on the analysis of fast ion response to TAE modes through the ORBIT code [R. B. White et al., Phys. Fluids 27 , 2455 (1984)], but it can be generalized to higher frequency modes (e.g. Compressional and Global Alfv en Eigenmodes) and to other numerical codes or theories.

  14. BISON and MARMOT Development for Modeling Fast Reactor Fuel Performance

    SciTech Connect

    Gamble, Kyle Allan Lawrence; Williamson, Richard L.; Schwen, Daniel; Zhang, Yongfeng; Novascone, Stephen Rhead; Medvedev, Pavel G.

    2015-09-01

    BISON and MARMOT are two codes under development at the Idaho National Laboratory for engineering scale and lower length scale fuel performance modeling. It is desired to add capabilities for fast reactor applications to these codes. The fast reactor fuel types under consideration are metal (U-Pu-Zr) and oxide (MOX). The cladding types of interest include 316SS, D9, and HT9. The purpose of this report is to outline the proposed plans for code development and provide an overview of the models added to the BISON and MARMOT codes for fast reactor fuel behavior. A brief overview of preliminary discussions on the formation of a bilateral agreement between the Idaho National Laboratory and the National Nuclear Laboratory in the United Kingdom is presented.

  15. Three phase transformer modelling for fast electromagnetic transient studies

    SciTech Connect

    Papadias, B.C.; Hatziargyriou, N.D.; Bakopoulos, J.A.; Prousalidis, J.M. . Electric Energy Systems Lab.)

    1994-04-01

    In this paper the overvoltages produced by switching the primary side of reactor loaded transformers are simulated using the Electromagnetic Transients Program (EMTP). Attention is focused on transformer modeling. Five general three-phase transformer models are used and from the results obtained, and comparisons with field tests positive conclusions concerning the reliability and the accuracy of these models in the study of switching fast electromagnetic transients are drawn.

  16. Fast loop modeling for protein structures

    NASA Astrophysics Data System (ADS)

    Zhang, Jiong; Nguyen, Son; Shang, Yi; Xu, Dong; Kosztin, Ioan

    2015-03-01

    X-ray crystallography is the main method for determining 3D protein structures. In many cases, however, flexible loop regions of proteins cannot be resolved by this approach. This leads to incomplete structures in the protein data bank, preventing further computational study and analysis of these proteins. For instance, all-atom molecular dynamics (MD) simulation studies of structure-function relationship require complete protein structures. To address this shortcoming, we have developed and implemented an efficient computational method for building missing protein loops. The method is database driven and uses deep learning and multi-dimensional scaling algorithms. We have implemented the method as a simple stand-alone program, which can also be used as a plugin in existing molecular modeling software, e.g., VMD. The quality and stability of the generated structures are assessed and tested via energy scoring functions and by equilibrium MD simulations. The proposed method can also be used in template-based protein structure prediction. Work supported by the National Institutes of Health [R01 GM100701]. Computer time was provided by the University of Missouri Bioinformatics Consortium.

  17. Identifying fast-onset antidepressants using rodent models.

    PubMed

    Ramaker, M J; Dulawa, S C

    2017-05-01

    Depression is a leading cause of disability worldwide and a major contributor to the burden of suicide. A major limitation of classical antidepressants is that 2-4 weeks of continuous treatment is required to elicit therapeutic effects, prolonging the period of depression, disability and suicide risk. Therefore, the development of fast-onset antidepressants is crucial. Preclinical identification of fast-onset antidepressants requires animal models that can accurately predict the delay to therapeutic onset. Although several well-validated assay models exist that predict antidepressant potential, few thoroughly tested animal models exist that can detect therapeutic onset. In this review, we discuss and assess the validity of seven rodent models currently used to assess antidepressant onset: olfactory bulbectomy, chronic mild stress, chronic forced swim test, novelty-induced hypophagia (NIH), novelty-suppressed feeding (NSF), social defeat stress, and learned helplessness. We review the effects of classical antidepressants in these models, as well as six treatments that possess fast-onset antidepressant effects in the clinic: electroconvulsive shock therapy, sleep deprivation, ketamine, scopolamine, GLYX-13 and pindolol used in conjunction with classical antidepressants. We also discuss the effects of several compounds that have yet to be tested in humans but have fast-onset antidepressant-like effects in one or more of these antidepressant onset sensitive models. These compounds include selective serotonin (5-HT)2C receptor antagonists, a 5-HT4 receptor agonist, a 5-HT7 receptor antagonist, NMDA receptor antagonists, a TREK-1 receptor antagonist, mGluR antagonists and (2R,6R)-HNK. Finally, we provide recommendations for identifying fast-onset antidepressants using rodent behavioral models and molecular approaches.

  18. A pipette-based calibration system for fast-scan cyclic voltammetry with fast response times.

    PubMed

    Ramsson, Eric S

    2016-01-01

    Fast-scan cyclic voltammetry (FSCV) is an electrochemical technique that utilizes the oxidation and/or reduction of an analyte of interest to infer rapid changes in concentrations. In order to calibrate the resulting oxidative or reductive current, known concentrations of an analyte must be introduced under controlled settings. Here, I describe a simple and cost-effective method, using a Petri dish and pipettes, for the calibration of carbon fiber microelectrodes (CFMs) using FSCV.

  19. Fast, Automated, Photo realistic, 3D Modeling of Building Interiors

    DTIC Science & Technology

    2016-09-12

    important for applications in augmented and virtual reality , indoor navigation, and building simulation software. This paper presents a method to...navigation, augmented and virtual reality , as well as building energy simulation software. These applications require watertight models with limited...preservation, entertainment, and augmented reality , the demand for both fast and accurate scanning technologies has dramatically increased. In this

  20. Nanorod-Based Fast-Response Pressure-Sensitive Paints

    NASA Technical Reports Server (NTRS)

    Bencic, Timothy; VanderWal, Randall

    2007-01-01

    A proposed program of research and development would be devoted to exploitation of nanomaterials in pressuresensitive paints (PSPs), which are used on wind-tunnel models for mapping surface pressures associated with flow fields. Heretofore, some success has been achieved in measuring steady-state pressures by use of PSPs, but success in measuring temporally varying pressures has been elusive because of the inherent slowness of the optical responses of these materials. A PSP contains a dye that luminesces in a suitable wavelength range in response to photoexcitation in a shorter wavelength range. The luminescence is quenched by oxygen at a rate proportional to the partial pressure of oxygen and thus proportional to the pressure of air. As a result, the intensity of luminescence varies inversely with the pressure of air. The major problem in developing a PSP that could be easily applied to a wind-tunnel model and could be useful for measuring rapidly varying pressure is to provide very high gas diffusivity for rapid, easy transport of oxygen to and from active dye molecules. Most PSPs include polymer-base binders, which limit the penetration of oxygen to dye molecules, thereby reducing responses to pressure fluctuations. The proposed incorporation of nanomaterials (somewhat more specifically, nanorods) would result in paints having nanostructured surfaces that, relative to conventional PSP surfaces, would afford easier and more nearly complete access of oxygen molecules to dye molecules. One measure of greater access is effective surface area: For a typical PSP as proposed applied to a given solid surface, the nanometer-scale structural features would result in an exposed surface area more than 100 times that of a conventional PSP, and the mass of proposed PSP needed to cover the surface would be less than tenth of the mass of the conventional PSP. One aspect of the proposed development would be to synthesize nanorods of Si/SiO2, in both tangle-mat and regular- array

  1. Fast response of InSb Schottky detector.

    PubMed

    Kanno, Ikuo; Hishiki, Shigeomi; Kogetsu, Yoshitaka; Nakamura, Tatsuya; Katagiri, Masaki

    2007-05-01

    An InSb Schottky detector, fabricated from an undoped InSb wafer with Hall mobility which is higher than those of previously employed InSb wafers, was used for alpha particle detection. The output pulse of this InSb detector showed a very fast rise time, which was comparable with the output pulses of scintillation detectors.

  2. Transcriptomic and metabolomic profiling of chicken adipose tissue in response to insulin neutralization and fasting.

    PubMed

    Ji, Bo; Ernest, Ben; Gooding, Jessica R; Das, Suchita; Saxton, Arnold M; Simon, Jean; Dupont, Joelle; Métayer-Coustard, Sonia; Campagna, Shawn R; Voy, Brynn H

    2012-08-31

    Domestic broiler chickens rapidly accumulate adipose tissue due to intensive genetic selection for rapid growth and are naturally hyperglycemic and insulin resistant, making them an attractive addition to the suite of rodent models used for studies of obesity and type 2 diabetes in humans. Furthermore, chicken adipose tissue is considered as poorly sensitive to insulin and lipolysis is under glucagon control. Excessive fat accumulation is also an economic and environmental concern for the broiler industry due to the loss of feed efficiency and excessive nitrogen wasting, as well as a negative trait for consumers who are increasingly conscious of dietary fat intake. Understanding the control of avian adipose tissue metabolism would both enhance the utility of chicken as a model organism for human obesity and insulin resistance and highlight new approaches to reduce fat deposition in commercial chickens. We combined transcriptomics and metabolomics to characterize the response of chicken adipose tissue to two energy manipulations, fasting and insulin deprivation in the fed state. Sixteen to 17 day-old commercial broiler chickens (ISA915) were fed ad libitum, fasted for five hours, or fed but deprived of insulin by injections of anti-insulin serum. Pair-wise contrasts of expression data identified a total of 2016 genes that were differentially expressed after correction for multiple testing, with the vast majority of differences due to fasting (1780 genes). Gene Ontology and KEGG pathway analyses indicated that a short term fast impacted expression of genes in a broad selection of pathways related to metabolism, signaling and adipogenesis. The effects of insulin neutralization largely overlapped with the response to fasting, but with more modest effects on adipose tissue metabolism. Tissue metabolomics indicated unique effects of insulin on amino acid metabolism. Collectively, these data provide a foundation for further study into the molecular basis for adipose

  3. Transcriptomic and metabolomic profiling of chicken adipose tissue in response to insulin neutralization and fasting

    PubMed Central

    2012-01-01

    Background Domestic broiler chickens rapidly accumulate adipose tissue due to intensive genetic selection for rapid growth and are naturally hyperglycemic and insulin resistant, making them an attractive addition to the suite of rodent models used for studies of obesity and type 2 diabetes in humans. Furthermore, chicken adipose tissue is considered as poorly sensitive to insulin and lipolysis is under glucagon control. Excessive fat accumulation is also an economic and environmental concern for the broiler industry due to the loss of feed efficiency and excessive nitrogen wasting, as well as a negative trait for consumers who are increasingly conscious of dietary fat intake. Understanding the control of avian adipose tissue metabolism would both enhance the utility of chicken as a model organism for human obesity and insulin resistance and highlight new approaches to reduce fat deposition in commercial chickens. Results We combined transcriptomics and metabolomics to characterize the response of chicken adipose tissue to two energy manipulations, fasting and insulin deprivation in the fed state. Sixteen to 17 day-old commercial broiler chickens (ISA915) were fed ad libitum, fasted for five hours, or fed but deprived of insulin by injections of anti-insulin serum. Pair-wise contrasts of expression data identified a total of 2016 genes that were differentially expressed after correction for multiple testing, with the vast majority of differences due to fasting (1780 genes). Gene Ontology and KEGG pathway analyses indicated that a short term fast impacted expression of genes in a broad selection of pathways related to metabolism, signaling and adipogenesis. The effects of insulin neutralization largely overlapped with the response to fasting, but with more modest effects on adipose tissue metabolism. Tissue metabolomics indicated unique effects of insulin on amino acid metabolism. Conclusions Collectively, these data provide a foundation for further study into the

  4. Finite Post Synaptic Potentials Cause a Fast Neuronal Response

    PubMed Central

    Helias, Moritz; Deger, Moritz; Rotter, Stefan; Diesmann, Markus

    2011-01-01

    A generic property of the communication between neurons is the exchange of pulses at discrete time points, the action potentials. However, the prevalent theory of spiking neuronal networks of integrate-and-fire model neurons relies on two assumptions: the superposition of many afferent synaptic impulses is approximated by Gaussian white noise, equivalent to a vanishing magnitude of the synaptic impulses, and the transfer of time varying signals by neurons is assessable by linearization. Going beyond both approximations, we find that in the presence of synaptic impulses the response to transient inputs differs qualitatively from previous predictions. It is instantaneous rather than exhibiting low-pass characteristics, depends non-linearly on the amplitude of the impulse, is asymmetric for excitation and inhibition and is promoted by a characteristic level of synaptic background noise. These findings resolve contradictions between the earlier theory and experimental observations. Here we review the recent theoretical progress that enabled these insights. We explain why the membrane potential near threshold is sensitive to properties of the afferent noise and show how this shapes the neural response. A further extension of the theory to time evolution in discrete steps quantifies simulation artifacts and yields improved methods to cross check results. PMID:21427776

  5. Fast bias dependent device models for CAD of MMICs

    NASA Astrophysics Data System (ADS)

    Daniel, Tom T.; Tayrani, Reza

    1995-02-01

    Fast and accurate physics-based models for High Electron Mobility Transistors (HEMTs) and Metal-Semiconductor Field-Effect Transistors (MESFETs) suitable for computer-aided design of Monolithic Microwave Integrated Circuits (MMICs) are described. These models are incorporated into Microwave Harmonica(sup trademark) to enable the prediction of device IV characteristics and nonlinear performance, as well as bias dependent equivalent circuit parameters from device geometry and material profile.

  6. Modeling Response Signal and Response Time Data

    ERIC Educational Resources Information Center

    Ratcliff, Roger

    2006-01-01

    The diffusion model (Ratcliff, 1978) and the leaky competing accumulator model (LCA, Usher & McClelland, 2001) were tested against two-choice data collected from the same subjects with the standard response time procedure and the response signal procedure. In the response signal procedure, a stimulus is presented and then, at one of a number of…

  7. Modeling Response Signal and Response Time Data

    ERIC Educational Resources Information Center

    Ratcliff, Roger

    2006-01-01

    The diffusion model (Ratcliff, 1978) and the leaky competing accumulator model (LCA, Usher & McClelland, 2001) were tested against two-choice data collected from the same subjects with the standard response time procedure and the response signal procedure. In the response signal procedure, a stimulus is presented and then, at one of a number of…

  8. Surface Water Response Modeling

    EPA Science Inventory

    During response to spills, or for facility planning, the vulnerability of downstream water resources is a major concern. How long and at what concentration do spilled contaminants reach downstream receptors? Models have the potential to answer these questions, but only if they ...

  9. Surface Water Response Modeling

    EPA Science Inventory

    During response to spills, or for facility planning, the vulnerability of downstream water resources is a major concern. How long and at what concentration do spilled contaminants reach downstream receptors? Models have the potential to answer these questions, but only if they ...

  10. Adaptive response modelling

    NASA Astrophysics Data System (ADS)

    Campa, Alessandro; Esposito, Giuseppe; Belli, Mauro

    Cellular response to radiation is often modified by a previous delivery of a small "priming" dose: a smaller amount of damage, defined by the end point being investigated, is observed, and for this reason the effect is called adaptive response. An improved understanding of this effect is essential (as much as for the case of the bystander effect) for a reliable radiation risk assessment when low dose irradiations are involved. Experiments on adaptive response have shown that there are a number of factors that strongly influence the occurrence (and the level) of the adaptation. In particular, priming doses and dose rates have to fall in defined ranges; the same is true for the time interval between the delivery of the small priming dose and the irradiation with the main, larger, dose (called in this case challenging dose). Different hypotheses can be formulated on the main mechanism(s) determining the adaptive response: an increased efficiency of DNA repair, an increased level of antioxidant enzymes, an alteration of cell cycle progression, a chromatin conformation change. An experimental clearcut evidence going definitely in the direction of one of these explanations is not yet available. Modelling can be done at different levels. Simple models, relating the amount of damage, through elementary differential equations, to the dose and dose rate experienced by the cell, are relatively easy to handle, and they can be modified to account for the priming irradiation. However, this can hardly be of decisive help in the explanation of the mechanisms, since each parameter of these models often incorporates in an effective way several cellular processes related to the response to radiation. In this presentation we show our attempts to describe adaptive response with models that explicitly contain, as a dynamical variable, the inducible adaptive agent. At a price of a more difficult treatment, this approach is probably more prone to give support to the experimental studies

  11. Response of surge protection devices to fast rising pulses

    NASA Technical Reports Server (NTRS)

    Mindel, I. N.

    1980-01-01

    Two types of lightning protection modules incorporating leadless (pill type) Zener like devices were evaluated with regard to their ability to suppress EMP induced transients. Two series of tests were performed to evaluate the ability of these modules to react to fast rate of rise ( 1Kv/ns) transients, and the attenuation introduced and the ability to limit damped sinusoid pulses which may be induced due to an EMP resulting from a nuclear detonation.

  12. Response of surge protection devices to fast rising pulses

    NASA Technical Reports Server (NTRS)

    Mindel, I. N.

    1980-01-01

    Two types of lightning protection modules incorporating leadless (pill type) Zener like devices were evaluated with regard to their ability to suppress EMP induced transients. Two series of tests were performed to evaluate the ability of these modules to react to fast rate of rise ( 1Kv/ns) transients, and the attenuation introduced and the ability to limit damped sinusoid pulses which may be induced due to an EMP resulting from a nuclear detonation.

  13. A fasting-responsive signaling pathway that extends life span in C. elegans.

    PubMed

    Uno, Masaharu; Honjoh, Sakiko; Matsuda, Mitsuhiro; Hoshikawa, Haruka; Kishimoto, Saya; Yamamoto, Tomohito; Ebisuya, Miki; Yamamoto, Takuya; Matsumoto, Kunihiro; Nishida, Eisuke

    2013-01-31

    Intermittent fasting is one of the most effective dietary restriction regimens that extend life span in C. elegans and mammals. Fasting-stimulus responses are key to the longevity response; however, the mechanisms that sense and transduce the fasting stimulus remain largely unknown. Through a comprehensive transcriptome analysis in C. elegans, we find that along with the FOXO transcription factor DAF-16, AP-1 (JUN-1/FOS-1) plays a central role in fasting-induced transcriptional changes. KGB-1, one of the C. elegans JNKs, acts as an activator of AP-1 and is activated in response to fasting. KGB-1 and AP-1 are involved in intermittent fasting-induced longevity. Fasting-induced upregulation of the components of the SCF E3 ubiquitin ligase complex via AP-1 and DAF-16 enhances protein ubiquitination and reduces protein carbonylation. Our results thus identify a fasting-responsive KGB-1/AP-1 signaling pathway, which, together with DAF-16, causes transcriptional changes that mediate longevity, partly through regulating proteostasis.

  14. Fast Bayesian Inference in Dirichlet Process Mixture Models.

    PubMed

    Wang, Lianming; Dunson, David B

    2011-01-01

    There has been increasing interest in applying Bayesian nonparametric methods in large samples and high dimensions. As Markov chain Monte Carlo (MCMC) algorithms are often infeasible, there is a pressing need for much faster algorithms. This article proposes a fast approach for inference in Dirichlet process mixture (DPM) models. Viewing the partitioning of subjects into clusters as a model selection problem, we propose a sequential greedy search algorithm for selecting the partition. Then, when conjugate priors are chosen, the resulting posterior conditionally on the selected partition is available in closed form. This approach allows testing of parametric models versus nonparametric alternatives based on Bayes factors. We evaluate the approach using simulation studies and compare it with four other fast nonparametric methods in the literature. We apply the proposed approach to three datasets including one from a large epidemiologic study. Matlab codes for the simulation and data analyses using the proposed approach are available online in the supplemental materials.

  15. Modeling fast and slow earthquakes at various scales

    PubMed Central

    IDE, Satoshi

    2014-01-01

    Earthquake sources represent dynamic rupture within rocky materials at depth and often can be modeled as propagating shear slip controlled by friction laws. These laws provide boundary conditions on fault planes embedded in elastic media. Recent developments in observation networks, laboratory experiments, and methods of data analysis have expanded our knowledge of the physics of earthquakes. Newly discovered slow earthquakes are qualitatively different phenomena from ordinary fast earthquakes and provide independent information on slow deformation at depth. Many numerical simulations have been carried out to model both fast and slow earthquakes, but problems remain, especially with scaling laws. Some mechanisms are required to explain the power-law nature of earthquake rupture and the lack of characteristic length. Conceptual models that include a hierarchical structure over a wide range of scales would be helpful for characterizing diverse behavior in different seismic regions and for improving probabilistic forecasts of earthquakes. PMID:25311138

  16. Modeling fast and slow earthquakes at various scales.

    PubMed

    Ide, Satoshi

    2014-01-01

    Earthquake sources represent dynamic rupture within rocky materials at depth and often can be modeled as propagating shear slip controlled by friction laws. These laws provide boundary conditions on fault planes embedded in elastic media. Recent developments in observation networks, laboratory experiments, and methods of data analysis have expanded our knowledge of the physics of earthquakes. Newly discovered slow earthquakes are qualitatively different phenomena from ordinary fast earthquakes and provide independent information on slow deformation at depth. Many numerical simulations have been carried out to model both fast and slow earthquakes, but problems remain, especially with scaling laws. Some mechanisms are required to explain the power-law nature of earthquake rupture and the lack of characteristic length. Conceptual models that include a hierarchical structure over a wide range of scales would be helpful for characterizing diverse behavior in different seismic regions and for improving probabilistic forecasts of earthquakes.

  17. Effect of fasting on body composition and responses to stress in sunshine bass.

    PubMed

    Davis, Kenneth B; Gaylord, T Gibson

    2011-01-01

    The integrated responses of the hormonal regulation of growth and stress in sunshine bass (Morone chrysops X Morone saxatilis) as regulated by feed deprivation were investigated. Groups of fish were fed 1.5% of the body weight per day or offered no feed for 4weeks. Another group of fish was not fed for 3weeks and feed was offered during the fourth week. Fish in each group were sampled immediately before or after a 15-min low water confinement stressor after each week of the experiment. Liver mass and liver glycogen content were decreased after one week of fasting and remained low until the end of the study. However, both recovered after a week of refeeding. Intraperitoneal fat was significantly lower after two weeks of fasting and did not recover after a week of refeeding. None of these components were affected by confinement stress. Plasma glucose in unstressed fish was generally unaffected by fasting or refeeding; however, plasma glucose increased after confinement stress in fed but not in fasted fish. The cortisol stress response was unaltered by fasting and remained robust. Plasma IGF-I generally decreased in fasted fish but was not significantly lower than fed fish until the fourth week. A week of refeeding did not restore plasma IGF-I concentrations. Plasma IGF-I concentrations were higher in confinement stressed fed fish after two and four weeks but were unchanged in the fourth week. There was no change in the plasma IGF-I concentrations in fasted or refed fish due to the stress. Liver weight and liver glycogen were essentially depleted after 2weeks of fasting. The reduction of liver glycogen greatly reduced the glucose response to stress; however, the cortisol stress response was maintained for at least four weeks of fasting. Intraperitoneal fat was decreased very little after 4weeks of fasting. Plasma IGF-I concentrations were reduced only after 3weeks of fasting.

  18. Time-domain analysis for extracting fast-paced pupil responses

    PubMed Central

    Zénon, Alexandre

    2017-01-01

    The eye pupil reacts to cognitive processes, but its analysis is challenging when luminance varies or when stimulation is fast-paced. Current approaches relying on deconvolution techniques do not account for the strong low-frequency spontaneous changes in pupil size or the large interindividual variability in the shape of the responses. Here a system identification framework is proposed in which the pupil responses to different parameters are extracted by means of an autoregressive model with exogenous inputs. In an example application of this technique, pupil size was shown to respond to the luminance and arousal scores of affective pictures presented in rapid succession. This result was significant in each subject (N = 5), but the pupil response varied between individuals both in amplitude and latency, highlighting the need for determining impulse responses subjectwise. The same method was also used to account for pupil size variations caused by respiration, illustrating the possibility to model the relation between pupil size and other continuous signals. In conclusion, this new framework for the analysis of pupil size data allows us to dissociate the response of the eye pupil from intermingled sources of influence and can be used to study the relation between pupil size and other physiological signals. PMID:28134323

  19. Assessing cognitive processes with diffusion model analyses: a tutorial based on fast-dm-30

    PubMed Central

    Voss, Andreas; Voss, Jochen; Lerche, Veronika

    2015-01-01

    Diffusion models can be used to infer cognitive processes involved in fast binary decision tasks. The model assumes that information is accumulated continuously until one of two thresholds is hit. In the analysis, response time distributions from numerous trials of the decision task are used to estimate a set of parameters mapping distinct cognitive processes. In recent years, diffusion model analyses have become more and more popular in different fields of psychology. This increased popularity is based on the recent development of several software solutions for the parameter estimation. Although these programs make the application of the model relatively easy, there is a shortage of knowledge about different steps of a state-of-the-art diffusion model study. In this paper, we give a concise tutorial on diffusion modeling, and we present fast-dm-30, a thoroughly revised and extended version of the fast-dm software (Voss and Voss, 2007) for diffusion model data analysis. The most important improvement of the fast-dm version is the possibility to choose between different optimization criteria (i.e., Maximum Likelihood, Chi-Square, and Kolmogorov-Smirnov), which differ in applicability for different data sets. PMID:25870575

  20. Fast Bayesian parameter estimation for stochastic logistic growth models.

    PubMed

    Heydari, Jonathan; Lawless, Conor; Lydall, David A; Wilkinson, Darren J

    2014-08-01

    The transition density of a stochastic, logistic population growth model with multiplicative intrinsic noise is analytically intractable. Inferring model parameter values by fitting such stochastic differential equation (SDE) models to data therefore requires relatively slow numerical simulation. Where such simulation is prohibitively slow, an alternative is to use model approximations which do have an analytically tractable transition density, enabling fast inference. We introduce two such approximations, with either multiplicative or additive intrinsic noise, each derived from the linear noise approximation (LNA) of a logistic growth SDE. After Bayesian inference we find that our fast LNA models, using Kalman filter recursion for computation of marginal likelihoods, give similar posterior distributions to slow, arbitrarily exact models. We also demonstrate that simulations from our LNA models better describe the characteristics of the stochastic logistic growth models than a related approach. Finally, we demonstrate that our LNA model with additive intrinsic noise and measurement error best describes an example set of longitudinal observations of microbial population size taken from a typical, genome-wide screening experiment. Copyright © 2014 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  1. Seismic responses of a pool-type fast reactor with different core support designs

    SciTech Connect

    Wu, Ting-shu; Seidensticker, R.W. )

    1989-01-01

    In designing the core support system for a pool-type fast reactor, there are many issues which must be considered in order to achieve an optimum and balanced design. These issues include safety, reliability, as well as costs. Several design options are possible to support the reactor core. Different core support options yield different frequency ranges and responses. Seismic responses of a large pool-type fast reactor incorporated with different core support designs have been investigated. 4 refs., 3 figs.

  2. Slow and Fast Responses: Two Mechanisms of Trial Outcome Processing Revealed by EEG Oscillations

    PubMed Central

    Novikov, Nikita A.; Nurislamova, Yulia M.; Zhozhikashvili, Natalia A.; Kalenkovich, Evgenii E.; Lapina, Anna A.; Chernyshev, Boris V.

    2017-01-01

    Cognitive control includes maintenance of task-specific processes related to attention, and non-specific regulation of motor threshold. Depending upon the nature of the behavioral tasks, these mechanisms may predispose to different kinds of errors, with either increased or decreased response time (RT) of erroneous responses relative to correct responses. Specifically, slow responses are related to attentional lapses and decision uncertainty, these conditions tending to delay RTs of both erroneous and correct responses. Here we studied if RT may be a valid approximation distinguishing trials with high and low levels of sustained attention and decision uncertainty. We analyzed response-related and feedback-related modulations in theta, alpha and beta band activity in the auditory version of the two-choice condensation task, which is highly demanding for sustained attention while involves no inhibition of prepotent responses. Depending upon response speed and accuracy, trials were divided into slow correct, slow erroneous, fast correct and fast erroneous. We found that error-related frontal midline theta (FMT) was present only on fast erroneous trials. The feedback-related FMT was equally strong on slow erroneous and fast erroneous trials. Late post-response posterior alpha suppression was stronger on erroneous slow trials. Feedback-related frontal beta was present only on slow correct trials. The data obtained cumulatively suggests that RT allows distinguishing the two types of trials, with fast trials related to higher levels of attention and low uncertainty, and slow trials related to lower levels of attention and higher uncertainty. PMID:28529478

  3. Physiological responses to food deprivation in the house sparrow, a species not adapted to prolonged fasting.

    PubMed

    Khalilieh, Anton; McCue, Marshall D; Pinshow, Berry

    2012-09-01

    Many wild birds fast during reproduction, molting, migration, or because of limited food availability. Species that are adapted to fasting sequentially oxidize endogenous fuels in three discrete phases. We hypothesized that species not adapted to long fasts have truncated, but otherwise similar, phases of fasting, sequential changes in fuel oxidization, and similar changes in blood metabolites to fasting-adapted species. We tested salient predictions in house sparrows (Passer domesticus biblicus), a subspecies that is unable to tolerate more than ~32 h of fasting. Our main hypothesis was that fasting sparrows sequentially oxidize substrates in the order carbohydrates, lipids, and protein. We dosed 24 house sparrows with [(13)C]glucose, palmitic acid, or glycine and measured (13)CO(2) in their breath while they fasted for 24 h. To ascertain whether blood metabolite levels reflect fasting-induced changes in metabolic fuels, we also measured glucose, triacylglycerides, and β-hydroxybutyrate in the birds' blood. The results of both breath (13)CO(2) and plasma metabolite analyses did not support our hypothesis; i.e., that sparrows have the same metabolic responses characteristic of fasting-adapted species, but on a shorter time scale. Contrary to our main prediction, we found that recently assimilated (13)C-tracers were oxidized continuously in different patterns with no definite peaks corresponding to the three phases of fasting and also that changes in plasma metabolite levels accurately tracked the changes found by breath analysis. Notably, the rate of recently assimilated [(13)C]glycine oxidization was significantly higher (P < 0.001) than that of the other metabolic tracers at all postdosing intervals. We conclude that the inability of house sparrows to fast for longer than 32 h is likely related to their inability to accrue large lipid stores, separately oxidize different fuels, and/or spare protein during fasting.

  4. Temperature dependence of the response of ultra fast silicon detectors

    NASA Astrophysics Data System (ADS)

    Mulargia, R.; Arcidiacono, R.; Bellora, A.; Boscardin, M.; Cartiglia, N.; Cenna, F.; Cirio, R.; Dalla Betta, G. F.; Durando, S.; Fadavi, A.; Ferrero, M.; Galloway, Z.; Gruey, B.; Freeman, P.; Kramberger, G.; Mandic, I.; Monaco, V.; Obertino, M.; Pancheri, L.; Paternoster, G.; Ravera, F.; Sacchi, R.; Sadrozinski, H. F. W.; Seiden, A.; Sola, V.; Spencer, N.; Staiano, A.; Wilder, M.; Woods, N.; Zatserklyaniy, A.

    2016-12-01

    The Ultra Fast Silicon Detectors (UFSD) are a novel concept of silicon detectors based on the Low Gain Avalanche Diode (LGAD) technology, which are able to obtain time resolution of the order of few tens of picoseconds. First prototypes with different geometries (pads/pixels/strips), thickness (300 and 50 μm) and gain (between 5 and 20) have been recently designed and manufactured by CNM (Centro Nacional de Microelectrónica, Barcelona) and FBK (Fondazione Bruno Kessler, Trento). Several measurements on these devices have been performed in laboratory and in beam test and a dependence of the gain on the temperature has been observed. Some of the first measurements will be shown (leakage current, breakdown voltage, gain and time resolution on the 300 μm from FBK and gain on the 50 μm-thick sensor from CNM) and a comparison with the theoretically predicted trend will be discussed.

  5. Fast to forgive, slow to retaliate: intuitive responses in the ultimatum game depend on the degree of unfairness.

    PubMed

    Ferguson, Eamonn; Maltby, John; Bibby, Peter A; Lawrence, Claire

    2014-01-01

    Evolutionary accounts have difficulty explaining why people cooperate with anonymous strangers they will never meet. Recently models, focusing on emotional processing, have been proposed as a potential explanation, with attention focusing on a dual systems approach based on system 1 (fast, intuitive, automatic, effortless, and emotional) and system 2 (slow, reflective, effortful, proactive and unemotional). Evidence shows that when cooperation is salient, people are fast (system 1) to cooperate, but with longer delays (system 2) they show greed. This is interpreted within the framework of the social heuristic hypothesis (SHH), whereby people overgeneralize potentially advantageous intuitively learnt and internalization social norms to 'atypical' situations. We extend this to explore intuitive reactions to unfairness by integrating the SHH with the 'fast to forgive, slow to anger' (FFSA) heuristic. This suggests that it is advantageous to be prosocial when facing uncertainty. We propose that whether or not someone intuitively shows prosociality (cooperation) or retaliation is moderated by the degree (certainty) of unfairness. People should intuitively cooperate when facing mild levels of unfairness (fast to forgive) but when given longer to decide about another's mild level of unfairness should retaliate (slow to anger). However, when facing severe levels of unfairness, the intuitive response is always retaliation. We test this using a series of one-shot ultimatum games and manipulate level of offer unfairness (50:50 60:40, 70:30, 80:20, 90:10) and enforced time delays prior to responding (1s, 2s, 8s, 15s). We also measure decision times to make responses after the time delays. The results show that when facing mildly unfair offers (60:40) people are fast (intuitive) to cooperate but with longer delays reject these mildly unfair offers: 'fast to forgive, and slow to retaliate'. However, for severely unfair offers (90:10) the intuitive and fast response is to always

  6. Disentangling fast and slow responses of the East Asian summer monsoon to reflecting and absorbing aerosol forcings

    NASA Astrophysics Data System (ADS)

    Wang, Zhili; Lin, Lei; Yang, Meilin; Xu, Yangyang; Li, Jiangnan

    2017-09-01

    We examine the roles of fast and slow responses in shaping the total equilibrium response of the East Asian summer monsoon (EASM) to reflecting (sulfate, SO4) and absorbing (black carbon, BC) aerosol forcings over the industrial era using the Community Earth System Model version 1 (CESM1). Our results show that there is a clear distinction between fast and slow responses of the EASM to aerosol forcings and the slow climate response due to aerosol-induced change in sea surface temperature (SST) plays an important role in the impacts of aerosols on the EASM. The EASM is weakened by a decrease in land-sea surface thermal contrast in the fast response (FR) component to SO4 forcing, whereas the weakening is more intensive due to the changes in tropospheric thermodynamic and dynamic structures in the slow response (SR) component to SO4. The total climate adjustment caused by SO4 is a significant weakening of the EASM and a decrease in precipitation. The BC-induced fast adjustment strengthens the EASM both by increasing the local land-sea surface thermal contrast and shifting the East Asian subtropical jet (EASJ) northwards. The BC-induced slow climate adjustment, however, weakens the EASM through altering the atmospheric temperature and circulation. Consequently, the EASM is slightly enhanced, especially north of 30° N, in the total response (TR) to BC. The spatial patterns of precipitation change over East Asia due to BC are similar in the total response and slow response. This study highlights the importance of ocean response to aerosol forcings in driving the changes of the EASM.

  7. Metabolic and hormonal response to short term fasting after endurance training in the rat.

    PubMed

    Guezennec, C Y; Serrurier, B; Aymonod, M; Merino, D; Pesquies, P C

    1984-11-01

    The metabolic and hormonal response to short term fasting was studied after endurance exercise training. Rats were kept running on a motor driven rodent treadmill 5 days/wk for periods up to 1 h/day for 6 wk. Trained and untrained rats were then fasted for 24 h and 48 h. Liver and muscle glycogen, blood glucose, lactate, beta OH butyrate, glycerol, plasma insulin, testosterone and corticosterone were measured in fed and fasted trained and untrained rats. 48 h fasted trained rats show a lower level of blood lactate (1.08 +/- 0.05 vs 1.33 +/- 0.08 mmol/l-1 of blood glycerol (1 +/- 0.11 vs 0.84 +/- 0.08 mmol/l-1), and of muscle glycogen. There is a significant increase in plasma corticosterone in 48 h fasted trained rats from fed values. Plasma testosterone decreases during fasting, the values are higher in trained rats. Plasma insulin decreases during fasting without any difference between the two groups. These results show higher lipolysis, and decreased glycogenolysis in trained animals during 48 h fasting. The difference between the groups in steroid hormone response could reduce neoglucogenesis and muscle proteolysis in trained animals.

  8. Disaster Response Team FAST Skills Training with a Portable Ultrasound Simulator Compared to Traditional Training: Pilot Study

    PubMed Central

    Paddock, Michael T.; Bailitz, John; Horowitz, Russ; Khishfe, Basem; Cosby, Karen; Sergel, Michelle J.

    2015-01-01

    Introduction Pre-hospital focused assessment with sonography in trauma (FAST) has been effectively used to improve patient care in multiple mass casualty events throughout the world. Although requisite FAST knowledge may now be learned remotely by disaster response team members, traditional live instructor and model hands-on FAST skills training remains logistically challenging. The objective of this pilot study was to compare the effectiveness of a novel portable ultrasound (US) simulator with traditional FAST skills training for a deployed mixed provider disaster response team. Methods We randomized participants into one of three training groups stratified by provider role: Group A. Traditional Skills Training, Group B. US Simulator Skills Training, and Group C. Traditional Skills Training Plus US Simulator Skills Training. After skills training, we measured participants’ FAST image acquisition and interpretation skills using a standardized direct observation tool (SDOT) with healthy models and review of FAST patient images. Pre- and post-course US and FAST knowledge were also assessed using a previously validated multiple-choice evaluation. We used the ANOVA procedure to determine the statistical significance of differences between the means of each group’s skills scores. Paired sample t-tests were used to determine the statistical significance of pre- and post-course mean knowledge scores within groups. Results We enrolled 36 participants, 12 randomized to each training group. Randomization resulted in similar distribution of participants between training groups with respect to provider role, age, sex, and prior US training. For the FAST SDOT image acquisition and interpretation mean skills scores, there was no statistically significant difference between training groups. For US and FAST mean knowledge scores, there was a statistically significant improvement between pre- and post-course scores within each group, but again there was not a statistically

  9. Disaster response team FAST skills training with a portable ultrasound simulator compared to traditional training: pilot study.

    PubMed

    Paddock, Michael T; Bailitz, John; Horowitz, Russ; Khishfe, Basem; Cosby, Karen; Sergel, Michelle J

    2015-03-01

    Pre-hospital focused assessment with sonography in trauma (FAST) has been effectively used to improve patient care in multiple mass casualty events throughout the world. Although requisite FAST knowledge may now be learned remotely by disaster response team members, traditional live instructor and model hands-on FAST skills training remains logistically challenging. The objective of this pilot study was to compare the effectiveness of a novel portable ultrasound (US) simulator with traditional FAST skills training for a deployed mixed provider disaster response team. We randomized participants into one of three training groups stratified by provider role: Group A. Traditional Skills Training, Group B. US Simulator Skills Training, and Group C. Traditional Skills Training Plus US Simulator Skills Training. After skills training, we measured participants' FAST image acquisition and interpretation skills using a standardized direct observation tool (SDOT) with healthy models and review of FAST patient images. Pre- and post-course US and FAST knowledge were also assessed using a previously validated multiple-choice evaluation. We used the ANOVA procedure to determine the statistical significance of differences between the means of each group's skills scores. Paired sample t-tests were used to determine the statistical significance of pre- and post-course mean knowledge scores within groups. We enrolled 36 participants, 12 randomized to each training group. Randomization resulted in similar distribution of participants between training groups with respect to provider role, age, sex, and prior US training. For the FAST SDOT image acquisition and interpretation mean skills scores, there was no statistically significant difference between training groups. For US and FAST mean knowledge scores, there was a statistically significant improvement between pre- and post-course scores within each group, but again there was not a statistically significant difference between

  10. An application of fast algorithms to numerical electromagnetic modeling

    SciTech Connect

    Bezvoda, V.; Segeth, K.

    1987-03-01

    Numerical electromagnetic modeling by the finite-difference or finite-element methods leads to a large sparse system of linear algebraic equations. Fast direct methods, requiring an order of at most q log q arithmetic operations to solve a system of q equations, cannot easily be applied to such a system. This paper describes the iterative application of a fast method, namely cyclic reduction, to the numerical solution of the Helmholtz equation with a piecewise constant imaginary coefficient of the absolute term in a plane domain. By means of numerical tests the advantages and limitations of the method compared with classical direct methods are discussed. The iterative application of the cyclic reduction method is very efficient if one can exploit a known solution of a similar (e.g., simpler) problem as the initial approximation. This makes cyclic reduction a powerful tool in solving the inverse problem by trial-and-error.

  11. A Fast Technology Infusion Model for Aerospace Organizations

    NASA Technical Reports Server (NTRS)

    Shapiro, Andrew A.; Schone, Harald; Brinza, David E.; Garrett, Henry B.; Feather, Martin S.

    2006-01-01

    A multi-year Fast Technology Infusion initiative proposes a model for aerospace organizations to improve the cost-effectiveness by which they mature new, in-house developed software and hardware technologies for space mission use. The first year task under the umbrella of this initiative will provide the framework to demonstrate and document the fast infusion process. The viability of this approach will be demonstrated on two technologies developed in prior years with internal Jet Propulsion Laboratory (JPL) funding. One hardware technology and one software technology were selected for maturation within one calendar year or less. The overall objective is to achieve cost and time savings in the qualification of technologies. At the end of the recommended three-year effort, we will have demonstrated for six or more in-house developed technologies a clear path to insertion using a documented process that permits adaptation to a broad range of hardware and software projects.

  12. A Fast Technology Infusion Model for Aerospace Organizations

    NASA Technical Reports Server (NTRS)

    Shapiro, Andrew A.; Schone, Harald; Brinza, David E.; Garrett, Henry B.; Feather, Martin S.

    2006-01-01

    A multi-year Fast Technology Infusion initiative proposes a model for aerospace organizations to improve the cost-effectiveness by which they mature new, in-house developed software and hardware technologies for space mission use. The first year task under the umbrella of this initiative will provide the framework to demonstrate and document the fast infusion process. The viability of this approach will be demonstrated on two technologies developed in prior years with internal Jet Propulsion Laboratory (JPL) funding. One hardware technology and one software technology were selected for maturation within one calendar year or less. The overall objective is to achieve cost and time savings in the qualification of technologies. At the end of the recommended three-year effort, we will have demonstrated for six or more in-house developed technologies a clear path to insertion using a documented process that permits adaptation to a broad range of hardware and software projects.

  13. Global Model of a Fast Ionization Wave in Helium

    NASA Astrophysics Data System (ADS)

    Yee, Benjamin; Barnat, Edward; Foster, John

    2014-10-01

    Technical challenges inhibit a complete examination of fast ionization waves via empirical means. The high-voltage pulses used to excite these waves can be on the order of nanoseconds or less. Such short timescales require instruments with exceptional sensitivity and bandwidth, but these may not be available or may not exist. In order to more completely understand the energetics of the fast ionization wave, a global model of a helium discharge was developed. We present the results of the model predictions and a comparison to experimental measurements when possible. The model follows 19 neutral helium states, helium ions, and electrons. Among the reactions included in the model are: electron impact ionization, electron (de)excitation, atomic excitation transfer, radiative decay, and radiation trapping. Comparisons demonstrate that the model can accurately predict 23S metastable densities, but discrepancies in the measured and predicted emissions indicate a greater than expected number of higher excited states. This suggests the presence of a persistent source of excitation which is believed to be the result of space charge buildup within the system. This work was supported in part by the Department of Energy Office of Fusion Energy Science Contract DE-SC0001939.

  14. Fast Human Brain Magnetic Resonance Responses Associated With Epileptiform Spikes

    PubMed Central

    Sundaram, Padmavathi; Wells, William M.; Mulkern, Robert V.; Bubrick, Ellen J.; Bromfield, Edward B.; Münch, Mirjam; Orbach, Darren B.

    2012-01-01

    Neuronal currents produce local electromagnetic fields that can potentially modulate the phase of the magnetic resonance signal and thus provide a contrast mechanism tightly linked to neuronal activity. Previous work has demonstrated the feasibility of direct MRI of neuronal activity in phantoms and cell culture, but in vivo efforts have yielded inconclusive, conflicting results. The likelihood of detecting and validating such signals can be increased with (i) fast gradient-echo echo-planar imaging, with acquisition rates sufficient to resolve neuronal activity, (ii) subjects with epilepsy, who frequently experience stereotypical electromagnetic discharges between seizures, expressed as brief, localized, high-amplitude spikes (interictal discharges), and (iii) concurrent electroencephalography. This work demonstrates that both MR magnitude and phase show large-amplitude changes concurrent with electroencephalography spikes. We found a temporal derivative relationship between MR phase and scalp electroencephalography, suggesting that the MR phase changes may be tightly linked to local cerebral activity. We refer to this manner of MR acquisition, designed explicitly to track the electroencephalography, as encephalographic MRI (eMRI). Potential extension of this technique into a general purpose functional neuroimaging tool requires further study of the MR signal changes accompanying lower amplitude neuronal activity than those discussed here. PMID:20806355

  15. Validation of a FAST model of the Statoil-Hywind Demo floating wind turbine

    SciTech Connect

    Driscoll, Frederick; Jonkman, Jason; Robertson, Amy; Sirnivas, Senu; Skaare, Bjorn; Nielsen, Finn Gunnar

    2016-10-13

    To assess the accuracy of the National Renewable Energy Laboratory's (NREL's) FAST simulation tool for modeling the coupled response of floating offshore wind turbines under realistic open-ocean conditions, NREL developed a FAST model of the Statoil Hywind Demo floating offshore wind turbine, and validated simulation results against field measurements. Field data were provided by Statoil, which conducted a comprehensive test measurement campaign of its demonstration system, a 2.3-MW Siemens turbine mounted on a spar substructure deployed about 10 km off the island of Karmoy in Norway. A top-down approach was used to develop the FAST model, starting with modeling the blades and working down to the mooring system. Design data provided by Siemens and Statoil were used to specify the structural, aerodynamic, and dynamic properties. Measured wind speeds and wave spectra were used to develop the wind and wave conditions used in the model. The overall system performance and behavior were validated for eight sets of field measurements that span a wide range of operating conditions. The simulated controller response accurately reproduced the measured blade pitch and power. In conclusion, the structural and blade loads and spectra of platform motion agree well with the measured data.

  16. Validation of a FAST model of the Statoil-Hywind Demo floating wind turbine

    DOE PAGES

    Driscoll, Frederick; Jonkman, Jason; Robertson, Amy; ...

    2016-10-13

    To assess the accuracy of the National Renewable Energy Laboratory's (NREL's) FAST simulation tool for modeling the coupled response of floating offshore wind turbines under realistic open-ocean conditions, NREL developed a FAST model of the Statoil Hywind Demo floating offshore wind turbine, and validated simulation results against field measurements. Field data were provided by Statoil, which conducted a comprehensive test measurement campaign of its demonstration system, a 2.3-MW Siemens turbine mounted on a spar substructure deployed about 10 km off the island of Karmoy in Norway. A top-down approach was used to develop the FAST model, starting with modeling themore » blades and working down to the mooring system. Design data provided by Siemens and Statoil were used to specify the structural, aerodynamic, and dynamic properties. Measured wind speeds and wave spectra were used to develop the wind and wave conditions used in the model. The overall system performance and behavior were validated for eight sets of field measurements that span a wide range of operating conditions. The simulated controller response accurately reproduced the measured blade pitch and power. In conclusion, the structural and blade loads and spectra of platform motion agree well with the measured data.« less

  17. Battlefield Lessons: The Forward Air Surgical Team (FAST) Response

    DTIC Science & Technology

    2011-02-24

    Decompression Craniotomy , Thoracotomy, and Surgical Airway. 23 The MFST personnel and equipment may be transported by fixed wing aircraft or helicopter. The...41 Frank Navarette, “State of Arizona Emergency Response and Recovery Plan,” Arizona Department of Emergency Management. (December, 2003), 8-5-2

  18. Modeling the effects of fast shocks on solar winds ions

    NASA Technical Reports Server (NTRS)

    Zhao, Xuepu; Ogilvie, K. W.; Whang, Y. C.

    1991-01-01

    Observations show that, when alpha particles and other minor ions in the solar wind plasma encounter fast shocks, they are heated more than protons and their bulk motion is decelerated less than protons. These effects have been studied using a three-fluid model, and the model predictions have been compared with observations. The comparison indicates that, for supercritical fast shocks, the three-fluid model can explain cross-shock minor ion heating which is significantly greater than that of protons. When the ratio of specific heats for minor ions, gamma (alpha), equals 2, both the lesser cross-shock deceleration and the greater heating of minor ions than of protons can be predicted by the model; thus, the minor ion heating through the shock transition region is consistent with the involvement of two degrees of freedom. Because the analysis is formulated in the de Heffmann-Teller frame of reference, the method is not valid for perpendicular shocks or when the angle is large. These results agree with the few extant observations and might be confirmed by further observations at the earth's bow shock.

  19. Slow and fast responses of mean and extreme precipitation to different forcing in CMIP5 simulations

    NASA Astrophysics Data System (ADS)

    Sillmann, Jana; Stjern, Camilla Weum; Myhre, Gunnar; Forster, Piers M.

    2017-06-01

    We are investigating the fast and slow responses of changes in mean and extreme precipitation to different climate forcing mechanisms, such as greenhouse gas and solar forcing, to understand whether rapid adjustments are important for extreme precipitation. To disentangle the effect of rapid adjustment to a given forcing on the overall change in extreme precipitation, we use a linear regression method that has been previously applied to mean precipitation. Equilibrium experiments with preindustrial CO2 concentrations and reduced solar constant were compared with a four times CO2 concentration experiment for 10 state-of-the-art climate models. We find that the two forcing mechanisms, greenhouse gases and solar, impose clearly different rapid adjustment signals in the mean precipitation, while such difference is difficult to discern for extreme precipitation due to large internal variability. In contrast to mean precipitation, changes in extreme precipitation scale with surface temperature trends and do not seem to depend on the forcing mechanism.

  20. PYTRANSIT: fast and easy exoplanet transit modelling in PYTHON

    NASA Astrophysics Data System (ADS)

    Parviainen, Hannu

    2015-07-01

    We present a fast and user friendly exoplanet transit light-curve modelling package PYTRANSIT, implementing optimized versions of the Giménez and Mandel & Agol transit models. The package offers an object-oriented PYTHON interface to access the two models implemented natively in FORTRAN with OpenMP parallelization. A partial OpenCL version of the quadratic Mandel-Agol model is also included for GPU-accelerated computations. The aim of PYTRANSIT is to facilitate the analysis of photometric time series of exoplanet transits consisting of hundreds of thousands of data points, and of multipassband transit light curves from spectrophotometric observations, as a part of a researcher's programming toolkit for building complex, problem-specific analyses.

  1. Metabolic response to a glucagon challenge varies with adiposity and life-history stage in fasting northern elephant seals.

    PubMed

    Crocker, Daniel E; Fowler, Melinda A; Champagne, Cory D; Vanderlugt, Anna L; Houser, Dorian S

    2014-01-01

    Metabolic adaptations for extended fasting in wildlife prioritize beta-oxidation of lipids and reduced glucose utilization to support energy metabolism. The pancreatic hormone glucagon plays key roles in regulating glycemia and lipid metabolism during fasting in model species but its function in wildlife species adapted for extended fasting is not well understood. Northern elephant seals (NES) undergo natural fasts of 1-3months while under constraints of high nutrient demands including lactation and development. We performed a glucagon challenge on lactating, molting and developing NES, early and late in their natural fasts, to examine the impact of this important regulatory hormone on metabolism. Glucagon caused increases in plasma glucose, insulin, fatty acids, ketones and urea, but the magnitude of these effects varied widely with adiposity and life-history stage. The strong impact of adiposity on glucose and insulin responses suggest a potential role for adipose derived factors in regulating hepatic metabolism and pancreatic sensitivity. Elevations in plasma glucose in response to glucagon were strongly associated with increases in protein catabolism, suggesting negative impacts of elevated glucagon on protein sparing. Glucagon promoted rapid ketone accumulation suggesting that low ketoacid levels in NES reflect low rates of production. These results demonstrate strong metabolic impacts of glucagon and support the idea that glucagon levels are downregulated in the context of metabolic adaptation to extended fasting. These results suggest that the regulation of carbohydrate and lipid metabolism in NES changes with adiposity, fasting duration and under various constraints of nutrient demands. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Development of a Fast Response Intake Air Temperature Recorder for the Mirage IIIO Aircraft.

    DTIC Science & Technology

    1986-02-01

    noise, but is otherwise a faithful reproduction of the thermocouple response. 9. CONCLUSIONS An intake air temperature probe and associated recording...DEVELOPMENT OF A FAST RESPONSE INTAKE AIR TEMPERATI*1E RECORDER FOR THE MIRAGE 1110 AIRCRAFT by W. H. HARCH DT1C EE ECTIZNV 12 N8 L B Approved for...Propulsion Technical Memorandum 433" DEVELOPMENT OF A FAST RESPONSE INTAKE AIR TEMPEATURE RECORDER FOR TlE MIRAGE I1IO AIRCRAFT by W.H. HARCH SUIMARY

  3. Fasting enhances the response of arcuate neuropeptide Y-glucose-inhibited neurons to decreased extracellular glucose

    PubMed Central

    Murphy, Beth Ann; Fioramonti, Xavier; Jochnowitz, Nina; Fakira, Kurt; Gagen, Karen; Contie, Sylvain; Lorsignol, Anne; Penicaud, Luc; Martin, William J.; Routh, Vanessa H.

    2009-01-01

    Fasting increases neuropeptide Y (NPY) expression, peptide levels, and the excitability of NPY-expressing neurons in the hypothalamic arcuate (ARC) nucleus. A subpopulation of ARC-NPY neurons (∼40%) are glucose-inhibited (GI)-type glucose-sensing neurons. Hence, they depolarize in response to decreased glucose. Because fasting enhances NPY neurotransmission, we propose that during fasting, GI neurons depolarize in response to smaller decreases in glucose. This increased excitation in response to glucose decreases would increase NPY-GI neuronal excitability and enhance NPY neurotransmission. Using an in vitro hypothalamic explant system, we show that fasting enhances NPY release in response to decreased glucose concentration. By measuring relative changes in membrane potential using a membrane potential-sensitive dye, we demonstrate that during fasting, a smaller decrease in glucose depolarizes NPY-GI neurons. Furthermore, incubation in low (0.7 mM) glucose enhanced while leptin (10 nM) blocked depolarization of GI neurons in response to decreased glucose. Fasting, leptin, and glucose-induced changes in NPY-GI neuron glucose sensing were mediated by 5′-AMP-activated protein kinase (AMPK). We conclude that during energy sufficiency, leptin reduces the ability of NPY-GI neurons to sense decreased glucose. However, after a fast, decreased leptin and glucose activate AMPK in NPY-GI neurons. As a result, NPY-GI neurons become depolarized in response to smaller glucose fluctuations. Increased excitation of NPY-GI neurons enhances NPY release. NPY, in turn, shifts energy homeostasis toward increased food intake and decreased energy expenditure to restore energy balance. PMID:19211911

  4. Polycrystalline CVD diamond detector: Fast response and high sensitivity with large area

    SciTech Connect

    Liu, Linyue Zhang, Xianpeng; Zhong, Yunhong; Ouyang, Xiaoping Zhang, Jianfu

    2014-01-15

    Polycrystalline diamond was successfully used to fabricate a large area (diameter up to 46 mm) radiation detector. It was proven that the developed detector shows a fast pulsed response time and a high sensitivity, therefore its rise time is lower than 5 ns, which is two times faster than that of a Si-PIN detector of the same size. And because of the large sensitive area, this detector shows good dominance in fast pulsed and low density radiation detection.

  5. GABAB receptor activation attenuates the stimulant but not mesolimbic dopamine response to ethanol in FAST mice

    PubMed Central

    Holstein, Sarah E.; Li, Na; Eshleman, Amy J.; Phillips, Tamara J.

    2012-01-01

    Neural processes influenced by γ-aminobutyric acid B (GABAB) receptors appear to contribute to acute ethanol sensitivity, including the difference between lines of mice bred for extreme sensitivity (FAST) or insensitivity (SLOW) to the locomotor stimulant effect of ethanol. One goal of the current study was to determine whether selection of the FAST and SLOW lines resulted in changes in GABAB receptor function, since the lines differ in sensitivity to the GABAB receptor agonist baclofen and baclofen attenuates the stimulant response to ethanol in FAST mice. A second goal was to determine whether the baclofen-induced reduction in ethanol stimulation in FAST mice is associated with an attenuation of the mesolimbic dopamine response to ethanol. In Experiment 1, the FAST and SLOW lines were found to not differ in GABAB receptor function (measured by baclofen-stimulated [35S]GTP!S binding) in whole brain or in several regional preparations, except in the striatum in one of the two replicate sets of selected lines. In Experiment 2, baclofen-induced attenuation of the locomotor stimulant response to ethanol in FAST mice was not accompanied by a reduction in dopamine levels in the nucleus accumbens, as measured by microdialysis. These data suggest that, overall, GABAB receptor function does not play an integral role in the genetic difference in ethanol sensitivity between the FAST and SLOW lines. Further, although GABAB receptors do modulate the locomotor stimulant response to ethanol in FAST mice, this effect does not appear to be due to a reduction in tonic dopamine signaling in the nucleus accumbens. PMID:22982185

  6. Cross hole GPR traveltime inversion using a fast and accurate neural network as a forward model

    NASA Astrophysics Data System (ADS)

    Mejer Hansen, Thomas

    2017-04-01

    Probabilistic formulated inverse problems can be solved using Monte Carlo based sampling methods. In principle both advanced prior information, such as based on geostatistics, and complex non-linear forward physical models can be considered. However, in practice these methods can be associated with huge computational costs that in practice limit their application. This is not least due to the computational requirements related to solving the forward problem, where the physical response of some earth model has to be evaluated. Here, it is suggested to replace a numerical complex evaluation of the forward problem, with a trained neural network that can be evaluated very fast. This will introduce a modeling error, that is quantified probabilistically such that it can be accounted for during inversion. This allows a very fast and efficient Monte Carlo sampling of the solution to an inverse problem. We demonstrate the methodology for first arrival travel time inversion of cross hole ground-penetrating radar (GPR) data. An accurate forward model, based on 2D full-waveform modeling followed by automatic travel time picking, is replaced by a fast neural network. This provides a sampling algorithm three orders of magnitude faster than using the full forward model, and considerably faster, and more accurate, than commonly used approximate forward models. The methodology has the potential to dramatically change the complexity of the types of inverse problems that can be solved using non-linear Monte Carlo sampling techniques.

  7. A fast method for a generalized nonlocal elastic model

    NASA Astrophysics Data System (ADS)

    Du, Ning; Wang, Hong; Wang, Che

    2015-09-01

    We develop a numerical method for a generalized nonlocal elastic model, which is expressed as a composition of a Riesz potential operator with a fractional differential operator, by composing a collocation method with a finite difference discretization. By carefully exploring the structure of the coefficient matrix of the numerical method, we develop a preconditioned fast Krylov subspace method, which reduces the computations to (Nlog ⁡ N) per iteration and the memory to O (N). The use of the preconditioner significantly reduces the number of iterations, and the preconditioner can be inverted in O (Nlog ⁡ N) computations. Numerical results show the utility of the method.

  8. A Mathematical Model of the Liver Circadian Clock Linking Feeding and Fasting Cycles to Clock Function.

    PubMed

    Woller, Aurore; Duez, Hélène; Staels, Bart; Lefranc, Marc

    2016-10-18

    To maintain energy homeostasis despite variable energy supply and consumption along the diurnal cycle, the liver relies on a circadian clock synchronized to food timing. Perturbed feeding and fasting cycles have been associated with clock disruption and metabolic diseases; however, the mechanisms are unclear. To address this question, we have constructed a mathematical model of the mammalian circadian clock, incorporating the metabolic sensors SIRT1 and AMPK. The clock response to various temporal patterns of AMPK activation was simulated numerically, mimicking the effects of a normal diet, fasting, and a high-fat diet. The model reproduces the dampened clock gene expression and NAD(+) rhythms reported for mice on a high-fat diet and predicts that this effect may be pharmacologically rescued by timed REV-ERB agonist administration. Our model thus identifies altered AMPK signaling as a mechanism leading to clock disruption and its associated metabolic effects and suggests a pharmacological approach to resetting the clock in obesity.

  9. Modeling Fast Ion Transport in TAE Avalanches in NSTX

    SciTech Connect

    Fredrickson, E D; Bell, R E; Darrow, D; Gorelenkov, N N; Kramer, G; Kubota, S; Levinton, F M; Liu, D; Medley, S S; Podesta, M; Tritz, K

    2009-08-17

    Experiments on the National Spherical Torus Experiment [M. Ono, et al., Nucl. Fusion 40 (2000) 557 ] have found strong bursts of Toroidal Alfven Eigenmode (TAE) activity correlated with abrupt drops in the neutron rate. A fairly complete data set offers the opportunity to benchmark the NOVA [C. Z. Cheng, Phys. Reports 211, 1-51 (1992)] and ORBIT [R. B. White and M. S. Chance, Phys. Fluids 27, 2455 (1984)] codes in the low aspect ratio tokamak (ST) geometry. The internal structure of TAE were modeled with NOVA and good agreement is found with measurements made with an array of five fixed-frequency reflectometers. The fast-ion transport resulting from these bursts of multiple TAE were then modeled with the ORBIT code. The simulations are reasonably consistent with the observed drop in neutron rate. While these results represent our best attempts to find agreement, we believe that further refinements in both the simulation of the TAE structure and in the modeling of the fast ion transport are needed. Benchmarking stability codes against present experiments is an important step in developing the predictive capability needed to plan future experiments.

  10. Unified Dark Matter scalar field models with fast transition

    SciTech Connect

    Bertacca, Daniele; Bruni, Marco; Piattella, Oliver F.; Pietrobon, Davide E-mail: marco.bruni@port.ac.uk E-mail: davide.pietrobon@jpl.nasa.gov

    2011-02-01

    We investigate the general properties of Unified Dark Matter (UDM) scalar field models with Lagrangians with a non-canonical kinetic term, looking specifically for models that can produce a fast transition between an early Einstein-de Sitter CDM-like era and a later Dark Energy like phase, similarly to the barotropic fluid UDM models in JCAP01(2010)014. However, while the background evolution can be very similar in the two cases, the perturbations are naturally adiabatic in fluid models, while in the scalar field case they are necessarily non-adiabatic. The new approach to building UDM Lagrangians proposed here allows to escape the common problem of the fine-tuning of the parameters which plague many UDM models. We analyse the properties of perturbations in our model, focusing on the the evolution of the effective speed of sound and that of the Jeans length. With this insight, we can set theoretical constraints on the parameters of the model, predicting sufficient conditions for the model to be viable. An interesting feature of our models is that what can be interpreted as w{sub DE} can be < −1 without violating the null energy conditions.

  11. Physiological Responses to Fasting and Estivation for the Three-Toed Amphiuma (Amphiuma tridactylum).

    PubMed

    Smith, Matthew E; Secor, Stephen M

    Species of Amphiuma enter a state of subterranean estivation with the drying of their aquatic habitat. Characteristic of amphibian fasting and estivation is an initial depression of metabolism and tissue mass and function with fasting, followed by a more pronounced adaptive decrease in metabolism and tissue function with estivation. We hypothesized that Amphiuma likewise experiences a two-stage set of responses to estivation. Therefore, we examined the physiological responses of the three-toed amphiuma (Amphiuma tridactylum) to fasting and estivation treatments. Recently fed A. tridactylum served as controls for fasting treatments of 1, 3, and 6 mo (in water) and estivation treatments of 3 and 6 mo (buried in dried substrate). After a 1-mo fast, A. tridactylum experienced no further depression of metabolic rate following 3 or 6 mo of fasting or estivation. For all fasting and estivation trials, A. tridactylum maintained blood chemistry homeostasis, with the exception of an increase in blood urea following 6 mo of estivation. Compared with fed controls, the mass of most organs did not vary even after 6 mo of fasting and estivation. Only the small intestine (decreasing) and the full gall bladder (increasing) experienced significant changes in mass with fasting or estivation. The fasting decrease in small intestinal mass was in part due to enterocyte atrophy, which resulted in a decrease in mucosa/submucosa thickness. In contrast to many estivating anurans and the ecologically convergent sirens, A. tridactylum does not surround itself in a cocoon of dried skin or mucus during estivation. The thickness and architecture of their skin remains unchanged even after 6 mo of estivation. Following months of fasting or estivation, individuals still maintain gastric acid production, pancreatic enzyme activity, and intestinal enzyme and transporter activities. Contrary to our hypothesis that A. tridactylum experiences two stages of metabolic depression and tissue downregulation

  12. Morphological, biochemical, transcriptional and epigenetic responses to fasting and refeeding in intestine of Xenopus laevis.

    PubMed

    Tamaoki, Keiji; Okada, Reiko; Ishihara, Akinori; Shiojiri, Nobuyoshi; Mochizuki, Kazuki; Goda, Toshinao; Yamauchi, Kiyoshi

    2016-01-01

    Amphibians are able to survive for several months without food. However, it is unclear what molecular mechanisms underlie their survival. To characterize the intestinal responses to fasting and refeeding, we investigated morphological, biochemical, transcriptional and epigenetic changes in the intestine from adult male Xenopus laevis. Frogs were fed for 22 days, fasted for 22 days, or fasted for 21 days and refed for 1 day. Fasting reduced, and refeeding recovered partially or fully, morphological parameters (wet weight of the intestine, circumference of the epithelial layer and number of troughs in a villus-trough unit), activities of digestive enzymes and plasma biochemical parameters (glucose, triglycerides, cholesterol and free fatty acids). Reverse transcription-quantitative polymerase chain reaction analysis revealed overall suppression of the transcript levels by fasting, with various recovery rates on refeeding. Chromatin immunoprecipitation assays on the selected genes whose transcript levels declined with fasting and recovered quickly with refeeding, showed several euchromatin marks in histone (acetylation and methylation) and RNA polymerase II modifications (phosphorylation) with fasting, and returned to the feeding levels by refeeding. The mRNA levels of these genes responded to fasting and refeeding to greater extents than did the pre-mRNA levels, suggesting the involvement of post-transcriptional regulation. Our results demonstrate that the X. laevis intestine may undergo overall metabolic suppression at least at the transcriptional level to save energy during fasting and quickly recovered to moderate nutritional deficiency by refeeding, and suggest that these dietary responses of the intestine are epigenetically and post-transcriptionally regulated.

  13. Response of muscle protein synthesis to fasting in suckling and weaned rats.

    PubMed

    Davis, T A; Fiorotto, M L; Nguyen, H V; Burrin, D G; Reeds, P J

    1991-12-01

    Protein synthetic efficiency (KRNA) is low in immature skeletal muscle of suckling rats and increases toward the end of the suckling period. To determine whether immature skeletal muscle is able to further reduce KRNA in response to fasting, suckling (5, 10, and 16 days of age) and weaned (28 days of age) rats were fed, fasted for 10 h, or fasted for 18 h and injected with a flooding dose of L-[4-3H]phenylalanine for measurement of muscle protein synthesis in vivo. In fed rats, fractional rates of protein synthesis (KS) and protein synthetic capacity decreased during the suckling period. KRNA increased toward the end of the suckling period. In 5-day-old rats, fasting for 10 h produced a 50% decline in KS of extensor digitorum longus and plantaris muscles, but KS did not change further after 18 h of fasting. In older suckled and weaned rats, 10 h of fasting decreased KS of extensor digitorum longus and plantaris muscles 30%; after 18 h of fasting, values had declined to 50% of those in fed animals. The reductions in KS in soleus muscles with 10 and 18 h of fasting were similar to those in other muscles at 5 and 10 days but were less than those in other muscles at 16 and 28 days. Changes in KRNA were similar to those for KS in all muscles from all age groups fasted for 10 and 18 h. Protein synthetic capacity decreased approximately 12% after 18 h of fasting, but this effect did not differ between age groups or muscle types.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Promoting cooperation through fast response to defection in spatial games

    NASA Astrophysics Data System (ADS)

    Wang, Xu-Wen; Jiang, Luo-Luo; Nie, Sen; Chen, Shi-Ming; Wang, Bing-Hong

    2016-10-01

    Recent experimental research has revealed that the cooperation in dynamic social networks, has significant scope for enhancement because individuals in a social system break the links with defective neighbours. To investigate how the length of defection tolerance affects the cooperation of prisoner’s dilemma game in dynamic ring networks, we study evolution of breaking and rewiring operations for social interaction as a response to the defection strategy. Defection tolerance is measured in terms of the time length that an individual tolerates a defector who continuously adopts the defective strategy. The results show that the dynamic nature of human social networks plays an essential role in promoting cooperation. Interestingly, there exists a critical value of the temptation to defect, below which the system is entirely dominated by cooperators, and a lower value of defection tolerance induces a larger threshold of temptation.

  15. Development of miniature 35 lbf fast response bipropellant divert thruster

    NASA Astrophysics Data System (ADS)

    Ruttle, Dan; Fitzsimmons, Mark

    1993-06-01

    A 35-lbf thrust bipropellant divert thruster developed for the Army Lightweight Exo-Atmospheric Projectile (LEAP) is described. The thruster produces a vacuum thrust of 35 lbf at 700 psia chamber pressure using nitrogen tetroxide and hydrazine at an O/F of 1.2. A multiple doublet type injector and a desilicide-coated columbium chamber are used; miniature fuel and oxidizer solenoid valves provide a 1-millisec opening response. In accordance with test results for a typical firing, the thrust reaches 90 percent of steady-state thrust 5 millisec after the electrical 'on' command; thrust termination occurs in 3.8 millisec. Results of gelled propellant tests are also presented.

  16. Non-Ideal Compressible-Fluid Dynamics of Fast-Response Pressure Probes for Unsteady Flow Measurements in Turbomachinery

    NASA Astrophysics Data System (ADS)

    Gori, G.; Molesini, P.; Persico, G.; Guardone, A.

    2017-03-01

    The dynamic response of pressure probes for unsteady flow measurements in turbomachinery is investigated numerically for fluids operating in non-ideal thermodynamic conditions, which are relevant for e.g. Organic Rankine Cycles (ORC) and super-critical CO2 applications. The step response of a fast-response pressure probe is investigated numerically in order to assess the expected time response when operating in the non-ideal fluid regime. Numerical simulations are carried out exploiting the Non-Ideal Compressible Fluid-Dynamics (NICFD) solver embedded in the open-source fluid dynamics code SU2. The computational framework is assessed against available experimental data for air in dilute conditions. Then, polytropic ideal gas (PIG), i.e. constant specific heats, and Peng-Robinson Stryjek-Vera (PRSV) models are applied to simulate the flow field within the probe operating with siloxane fluid octamethyltrisiloxane (MDM). The step responses are found to depend mainly on the speed of sound of the working fluid, indicating that molecular complexity plays a major role in determining the promptness of the measurement devices. According to the PRSV model, non-ideal effects can increase the step response time with respect to the acoustic theory predictions. The fundamental derivative of gas-dynamic is confirmed to be the driving parameter for evaluating non-ideal thermodynamic effects related to the dynamic calibration of fast-response aerodynamic pressure probes.

  17. Freddi: Fast Rise Exponential Decay accretion Disk model Implementation

    NASA Astrophysics Data System (ADS)

    Malanchev, K. L.; Lipunova, G. V.

    2016-10-01

    Freddi (Fast Rise Exponential Decay: accretion Disk model Implementation) solves 1-D evolution equations of the Shakura-Sunyaev accretion disk. It simulates fast rise exponential decay (FRED) light curves of low mass X-ray binaries (LMXBs). The basic equation of the viscous evolution relates the surface density and viscous stresses and is of diffusion type; evolution of the accretion rate can be found on solving the equation. The distribution of viscous stresses defines the emission from the source. The standard model for the accretion disk is implied; the inner boundary of the disk is at the ISCO or can be explicitely set. The boundary conditions in the disk are the zero stress at the inner boundary and the zero accretion rate at the outer boundary. The conditions are suitable during the outbursts in X-ray binary transients with black holes. In a binary system, the accretion disk is radially confined. In Freddi, the outer radius of the disk can be set explicitely or calculated as the position of the tidal truncation radius.

  18. A Model for Fast Ion Emission from Metal Deuterides

    NASA Astrophysics Data System (ADS)

    Hagelstein, Peter

    2000-03-01

    There have been numerous claims during the past ten years of the observation of a variety of anomalies in metal deuterides. One such anomaly involves the emission of fast (MeV) alpha from PdD as reported by G. Chambers and colleagues at NRL in the early 1990s. A related effect is the emission of a variety of low mass fast ions from TiD reported by groups led by G. Chambers and by F. E. Cecil (Colorado School of Mines) et al(F. E. Cecil, H. Liu, D. Beddingfield and C. S. Galovich, in Anomalous Nuclear Effects in Deuterium/Solid Systems, AIP Conf. Proc.) 228, p. 383 (1990).. We have recently examined a theoretical model for this effect. We propose a second order off-resonant reaction in which fusion reactions are coupled to optical phonons, and then the optical phonon excitation is dipole-coupled to nuclear ionization. Such a model gives reaction products and energies which appear to be in agreement with experiment.

  19. Fast model-based estimation of ancestry in unrelated individuals

    PubMed Central

    Alexander, David H.; Novembre, John; Lange, Kenneth

    2009-01-01

    Population stratification has long been recognized as a confounding factor in genetic association studies. Estimated ancestries, derived from multi-locus genotype data, can be used to perform a statistical correction for population stratification. One popular technique for estimation of ancestry is the model-based approach embodied by the widely applied program structure. Another approach, implemented in the program EIGENSTRAT, relies on Principal Component Analysis rather than model-based estimation and does not directly deliver admixture fractions. EIGENSTRAT has gained in popularity in part owing to its remarkable speed in comparison to structure. We present a new algorithm and a program, ADMIXTURE, for model-based estimation of ancestry in unrelated individuals. ADMIXTURE adopts the likelihood model embedded in structure. However, ADMIXTURE runs considerably faster, solving problems in minutes that take structure hours. In many of our experiments, we have found that ADMIXTURE is almost as fast as EIGENSTRAT. The runtime improvements of ADMIXTURE rely on a fast block relaxation scheme using sequential quadratic programming for block updates, coupled with a novel quasi-Newton acceleration of convergence. Our algorithm also runs faster and with greater accuracy than the implementation of an Expectation-Maximization (EM) algorithm incorporated in the program FRAPPE. Our simulations show that ADMIXTURE's maximum likelihood estimates of the underlying admixture coefficients and ancestral allele frequencies are as accurate as structure's Bayesian estimates. On real-world data sets, ADMIXTURE's estimates are directly comparable to those from structure and EIGENSTRAT. Taken together, our results show that ADMIXTURE's computational speed opens up the possibility of using a much larger set of markers in model-based ancestry estimation and that its estimates are suitable for use in correcting for population stratification in association studies. PMID:19648217

  20. Fast model-based estimation of ancestry in unrelated individuals.

    PubMed

    Alexander, David H; Novembre, John; Lange, Kenneth

    2009-09-01

    Population stratification has long been recognized as a confounding factor in genetic association studies. Estimated ancestries, derived from multi-locus genotype data, can be used to perform a statistical correction for population stratification. One popular technique for estimation of ancestry is the model-based approach embodied by the widely applied program structure. Another approach, implemented in the program EIGENSTRAT, relies on Principal Component Analysis rather than model-based estimation and does not directly deliver admixture fractions. EIGENSTRAT has gained in popularity in part owing to its remarkable speed in comparison to structure. We present a new algorithm and a program, ADMIXTURE, for model-based estimation of ancestry in unrelated individuals. ADMIXTURE adopts the likelihood model embedded in structure. However, ADMIXTURE runs considerably faster, solving problems in minutes that take structure hours. In many of our experiments, we have found that ADMIXTURE is almost as fast as EIGENSTRAT. The runtime improvements of ADMIXTURE rely on a fast block relaxation scheme using sequential quadratic programming for block updates, coupled with a novel quasi-Newton acceleration of convergence. Our algorithm also runs faster and with greater accuracy than the implementation of an Expectation-Maximization (EM) algorithm incorporated in the program FRAPPE. Our simulations show that ADMIXTURE's maximum likelihood estimates of the underlying admixture coefficients and ancestral allele frequencies are as accurate as structure's Bayesian estimates. On real-world data sets, ADMIXTURE's estimates are directly comparable to those from structure and EIGENSTRAT. Taken together, our results show that ADMIXTURE's computational speed opens up the possibility of using a much larger set of markers in model-based ancestry estimation and that its estimates are suitable for use in correcting for population stratification in association studies.

  1. Toward a Fast-Response Active Turbine Tip Clearance Control

    NASA Technical Reports Server (NTRS)

    Melcher, Kevin J.; Kypuros, Javier A.

    2003-01-01

    This paper describes active tip clearance control research being conducted by NASA to improve turbine engine systems. The target application for this effort is commercial aircraft engines. However, technologies developed for clearance control can benefit a broad spectrum of current and future turbomachinery. The first portion of the paper addresses the research from a programmatic viewpoint. Recent studies that provide motivation for the work, identification of key technologies, and NASA's plan for addressing deficiencies in the technologies are discussed. The later portion of the paper drills down into one of the key technologies by presenting equations and results for a preliminary dynamic model of the tip clearance phenomena.

  2. Implicit XMHD Modeling of Fast Z-Pinches

    NASA Astrophysics Data System (ADS)

    Martin, Matthew

    2013-10-01

    The numerical modeling of fast Z-Pinches as applied to magnetically driven inertial confinement fusion concepts is typically performed under the resistive- magnetohydrodynamic (MHD) model. We derive the limitations of this model as currently applied to modeling such targets and present numerical test problems that demonstrate the physical error introduced through the approximations inherent in resistive-MHD. We then compare the resistive-MHD model to simulations utilizing new implicit algorithms for the efficient solution of the extended-magnetohydrodynamic (XMHD) system of equations. Herein we define XMHD as a quasi-neutral electro-magnetic two-fluid model. We present specific examples where the XMHD system of equations is required for modeling magnetically driven ICF targets if large physical errors are to be avoided in the numerical solution of the system. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  3. Effect of short-term fasting on lipolytic responsiveness in normal and obese human subjects

    SciTech Connect

    Wolfe, R.R.; Peters, E.J.; Klein, S.; Holland, O.B.; Rosenblatt, J.; Gary, H. Jr.

    1987-02-01

    In this study the rate of lipolysis (fatty acid and glycerol release into blood) has been quantified in both normal weight and obese volunteers after both 15 and 87 h of fasting. In each study, the basal rate and subsequent response to epinephrine infusion were determined. The rate of appearance (R/sub a/) of free fatty acids (FFA) and glycerol were quantified by infusion of (1- TC)palmitate and D-5-glycerol, respectively. Substrate flux rates per unit of body fat mass and lean body mass were calculated from total body water measurements using H2 YO dilution. In normal volunteers, the basal R/sub a/ FFA and R/sub a/ glycerol rose markedly with 87 h of fasting, whereas the increases were more modest in the obese subjects. However, the rate of mobilization of fat, in relation to the lean body mass, was higher in the obese subjects than in the normal subjects after 15 h of fasting, and the values were similar in both groups after 87 h of fasting. There was an increased lipolytic response to epinephrine after fasting in both groups. This increased sensitivity may have resulted from the enhancement of fatty acid-triglyceride substrate cycling that occurred after fasting.

  4. Models of fast radio bursts at cosmological distances

    NASA Astrophysics Data System (ADS)

    Mottez, F.; Guépin, C.; Kotera, K.; Voisin, G.; Zarka, P.

    2016-12-01

    Fast radio bursts are isolated radio pulses of high amplitude, with a frequency / time delay relation that can be interpreted as the dispersion measure (DM) of a source at cosmological distances (several hundreds of Mpc). Up to 2015, the only known FRBs all had different locations on the sky, and different DM. Many theoretical explanations of FRBs have been proposed. Some of them are associated to unique cataclysmic events, others are compatible with the repetition of bursts from the same source. The recent publication of the repeating FRB 121102 shows that at least some of the FRB must be compatible with non-cataclysmic events. A model based on the interaction of a highly relativitic pulsar wind with a body orbiting the pulsar (planet, big asteroid, white dwarf) could explain FRBs. It is briefly compared with other models of repeating FRBs.

  5. Is fast fiber innervation responsible for increased acetylcholinesterase activity in reinnervating soleus muscles?

    NASA Technical Reports Server (NTRS)

    Misulis, K. E.; Dettbarn, W. D.

    1985-01-01

    An investigation was conducted as to whether the predominantly slow SOL, which is low in AChE activity, is initially reinnervated by axons that originally innervated fast muscle fibers with high AChE activity, such as those of the EDL. Local denervation of the SOL in the guinea pig was performed because this muscle is composed solely of slow (type I) fibers; thereby virtually eliminating the possibility of homologous muscle fast fiber innervation. The overshoot in this preparation was qualitatively similar to that seen with distal denervation in the guinea pig and local and distal denervation in the rat. Thus, initial fast fiber innvervation is not responsible for the patterns of change in AChE activity seen with reinnervation in the SOL. It is concluded that the neural control of AChe is different in these two muscles and may reflect specific differences in the characteristics of AChE regulation in fast and slow muscle.

  6. Wind turbine control systems: Dynamic model development using system identification and the fast structural dynamics code

    SciTech Connect

    Stuart, J.G.; Wright, A.D.; Butterfield, C.P.

    1996-10-01

    Mitigating the effects of damaging wind turbine loads and responses extends the lifetime of the turbine and, consequently, reduces the associated Cost of Energy (COE). Active control of aerodynamic devices is one option for achieving wind turbine load mitigation. Generally speaking, control system design and analysis requires a reasonable dynamic model of {open_quotes}plant,{close_quotes} (i.e., the system being controlled). This paper extends the wind turbine aileron control research, previously conducted at the National Wind Technology Center (NWTC), by presenting a more detailed development of the wind turbine dynamic model. In prior research, active aileron control designs were implemented in an existing wind turbine structural dynamics code, FAST (Fatigue, Aerodynamics, Structures, and Turbulence). In this paper, the FAST code is used, in conjunction with system identification, to generate a wind turbine dynamic model for use in active aileron control system design. The FAST code is described and an overview of the system identification technique is presented. An aileron control case study is used to demonstrate this modeling technique. The results of the case study are then used to propose ideas for generalizing this technique for creating dynamic models for other wind turbine control applications.

  7. Fibroblast Growth Factor 21-Null Mice Do Not Exhibit an Impaired Response to Fasting

    PubMed Central

    Antonellis, Patrick Joseph; Hayes, Meghan Patricia; Adams, Andrew Charles

    2016-01-01

    Fibroblast growth factor 21 (FGF21) is a pleotropic metabolic regulator, expression of which is elevated during fasting. To this end, the precise role played by FGF21 in the biology of fasting has been the subject of several recent studies, which have demonstrated contributions to the regulation of both lipid and carbohydrate metabolism. In the present study, we compared wild-type (WT) and FGF21-null (FGF21KO) mice, demonstrating that, despite the significant induction of FGF21 during fasting in the WT animals, our strain of FGF21-null mice exhibits only limited impairments in their adaptation to nutrient deprivation. Specifically, fasted FGF21KO mice display a mild attenuation of gluconeogenic transcriptional induction in the liver accompanied by partially blunted glucose production in response to a pyruvate challenge. Furthermore, FGF21KO mice displayed only minor impairments in lipid metabolism in the fasted state, limited to accumulation of hepatic triglycerides and a reduction in expression of genes associated with fatty acid oxidation. To address the possibility of compensation to germline deletion of FGF21, we further interrogated the role of endogenous FGF21 via acute pharmacological blockade of FGF21 signaling. At the transcriptional level, we show that FGF21 signaling is required for full induction of gluconeogenic and oxidative genes in the liver. However, corroborating our findings in FGF21KO mice, pharmacological blockade of the FGF21 axis did not profoundly disrupt the physiological response to fasting. Taken as a whole, these data demonstrate that, while FGF21 is partially required for appropriate gene expression during the fed to fasted transition, its absence does not significantly impact the downstream physiology of the fasted state. PMID:27445980

  8. Discordant signaling and autophagy response to fasting in hearts of obese mice: Implications for ischemia tolerance.

    PubMed

    Andres, Allen M; Kooren, Joel A; Parker, Sarah J; Tucker, Kyle C; Ravindran, Nandini; Ito, Bruce R; Huang, Chengqun; Venkatraman, Vidya; Van Eyk, Jennifer E; Gottlieb, Roberta A; Mentzer, Robert M

    2016-07-01

    Autophagy is regulated by nutrient and energy status and plays an adaptive role during nutrient deprivation and ischemic stress. Metabolic syndrome (MetS) is a hypernutritive state characterized by obesity, dyslipidemia, elevated fasting blood glucose levels, and insulin resistance. It has also been associated with impaired autophagic flux and larger-sized infarcts. We hypothesized that diet-induced obesity (DIO) affects nutrient sensing, explaining the observed cardiac impaired autophagy. We subjected male friend virus B NIH (FVBN) mice to a high-fat diet, which resulted in increased weight gain, fat deposition, hyperglycemia, insulin resistance, and larger infarcts after myocardial ischemia-reperfusion. Autophagic flux was impaired after 4 wk on a high-fat diet. To interrogate nutrient-sensing pathways, DIO mice were subjected to overnight fasting, and hearts were processed for biochemical and proteomic analysis. Obese mice failed to upregulate LC3-II or to clear p62/SQSTM1 after fasting, although mRNA for LC3B and p62/SQSTM1 were appropriately upregulated in both groups, demonstrating an intact transcriptional response to fasting. Energy- and nutrient-sensing signal transduction pathways [AMPK and mammalian target of rapamycin (mTOR)] also responded appropriately to fasting, although mTOR was more profoundly suppressed in obese mice. Proteomic quantitative analysis of the hearts under fed and fasted conditions revealed broad changes in protein networks involved in oxidative phosphorylation, autophagy, oxidative stress, protein homeostasis, and contractile machinery. In many instances, the fasting response was quite discordant between lean and DIO mice. Network analysis implicated the peroxisome proliferator-activated receptor and mTOR regulatory nodes. Hearts of obese mice exhibited impaired autophagy, altered proteome, and discordant response to nutrient deprivation. Copyright © 2016 the American Physiological Society.

  9. Discordant signaling and autophagy response to fasting in hearts of obese mice: Implications for ischemia tolerance

    PubMed Central

    Kooren, Joel A.; Parker, Sarah J.; Tucker, Kyle C.; Ravindran, Nandini; Ito, Bruce R.; Huang, Chengqun; Venkatraman, Vidya; Van Eyk, Jennifer E.; Gottlieb, Roberta A.; Mentzer, Robert M.

    2016-01-01

    Autophagy is regulated by nutrient and energy status and plays an adaptive role during nutrient deprivation and ischemic stress. Metabolic syndrome (MetS) is a hypernutritive state characterized by obesity, dyslipidemia, elevated fasting blood glucose levels, and insulin resistance. It has also been associated with impaired autophagic flux and larger-sized infarcts. We hypothesized that diet-induced obesity (DIO) affects nutrient sensing, explaining the observed cardiac impaired autophagy. We subjected male friend virus B NIH (FVBN) mice to a high-fat diet, which resulted in increased weight gain, fat deposition, hyperglycemia, insulin resistance, and larger infarcts after myocardial ischemia-reperfusion. Autophagic flux was impaired after 4 wk on a high-fat diet. To interrogate nutrient-sensing pathways, DIO mice were subjected to overnight fasting, and hearts were processed for biochemical and proteomic analysis. Obese mice failed to upregulate LC3-II or to clear p62/SQSTM1 after fasting, although mRNA for LC3B and p62/SQSTM1 were appropriately upregulated in both groups, demonstrating an intact transcriptional response to fasting. Energy- and nutrient-sensing signal transduction pathways [AMPK and mammalian target of rapamycin (mTOR)] also responded appropriately to fasting, although mTOR was more profoundly suppressed in obese mice. Proteomic quantitative analysis of the hearts under fed and fasted conditions revealed broad changes in protein networks involved in oxidative phosphorylation, autophagy, oxidative stress, protein homeostasis, and contractile machinery. In many instances, the fasting response was quite discordant between lean and DIO mice. Network analysis implicated the peroxisome proliferator-activated receptor and mTOR regulatory nodes. Hearts of obese mice exhibited impaired autophagy, altered proteome, and discordant response to nutrient deprivation. PMID:27199111

  10. Fast and stable numerical method for neuronal modelling

    NASA Astrophysics Data System (ADS)

    Hashemi, Soheil; Abdolali, Ali

    2016-11-01

    Excitable cell modelling is of a prime interest in predicting and targeting neural activity. Two main limits in solving related equations are speed and stability of numerical method. Since there is a tradeoff between accuracy and speed, most previously presented methods for solving partial differential equations (PDE) are focused on one side. More speed means more accurate simulations and therefore better device designing. By considering the variables in finite differenced equation in proper time and calculating the unknowns in the specific sequence, a fast, stable and accurate method is introduced in this paper for solving neural partial differential equations. Propagation of action potential in giant axon is studied by proposed method and traditional methods. Speed, consistency and stability of the methods are compared and discussed. The proposed method is as fast as forward methods and as stable as backward methods. Forward methods are known as fastest methods and backward methods are stable in any circumstances. Complex structures can be simulated by proposed method due to speed and stability of the method.

  11. Modelling land-fast sea ice using a linear elastic model

    NASA Astrophysics Data System (ADS)

    Plante, Mathieu; Tremblay, Bruno

    2016-04-01

    Land-fast ice is an important component of the Arctic system, capping the coastal Arctic waters for most of the year and exerting a large influence on ocean-atmosphere heat exchanges. Yet, the accurate representation of land-fast ice in most large-scale sea ice models remains a challenge, part due to the difficult (and sometimes non-physical) parametrisation of ice fracture. In this study, a linear elastic model is developed to investigate the internal stresses induced by the wind forcing on the land-fast ice, modelled as a 2D elastic plate. The model simulates ice fracture by the implementation of a damage coefficient which causes a local reduction in internal stress. This results in a cascade propagation of damage, simulating the ice fracture that determines the position of the land-fast ice edge. The modelled land-fast ice cover is sensitive to the choice of failure criterion. The parametrised cohesion, tensile and compressive strength and the relationship with the land-fast ice stability is discussed. To estimate the large scale mechanical properties of land-fast ice, these results are compared to a set of land-fast ice break up events and ice bridge formations observed in the Siberian Arctic. These events are identified using brightness temperature imagery from the MODIS (Moderate Resolution Imaging Spectroradiometer) Terra and Aqua satellites, from which the position of the flaw lead is identifiable by the opening of polynyi adjacent to the land-fast ice edge. The shape of the land-fast ice before, during and after these events, along with the characteristic scale of the resulting ice floes, are compared to the model results to extrapolate the stress state that corresponds to these observations. The model setting that best reproduce the scale of the observed break up events is used to provide an estimation of the strength of the ice relative to the wind forcing. These results will then be used to investigate the relationship between the ice thickness and the

  12. Reasoning with Vectors: A Continuous Model for Fast Robust Inference

    PubMed Central

    Widdows, Dominic; Cohen, Trevor

    2015-01-01

    This paper describes the use of continuous vector space models for reasoning with a formal knowledge base. The practical significance of these models is that they support fast, approximate but robust inference and hypothesis generation, which is complementary to the slow, exact, but sometimes brittle behavior of more traditional deduction engines such as theorem provers. The paper explains the way logical connectives can be used in semantic vector models, and summarizes the development of Predication-based Semantic Indexing, which involves the use of Vector Symbolic Architectures to represent the concepts and relationships from a knowledge base of subject-predicate-object triples. Experiments show that the use of continuous models for formal reasoning is not only possible, but already demonstrably effective for some recognized informatics tasks, and showing promise in other traditional problem areas. Examples described in this paper include: predicting new uses for existing drugs in biomedical informatics; removing unwanted meanings from search results in information retrieval and concept navigation; type-inference from attributes; comparing words based on their orthography; and representing tabular data, including modelling numerical values. The algorithms and techniques described in this paper are all publicly released and freely available in the Semantic Vectors open-source software package.1 PMID:26582967

  13. UNCOUPLING PROTEIN-2 MODULATES THE LIPID METABOLIC RESPONSE TO FASTING IN MICE

    PubMed Central

    Sheets, Anthony R.; Fülöp, Péter; Derdák, Zoltán; Kassai, Andrea; Sabo, Edmond; Mark, Nicholas M.; Paragh, György; Wands, Jack R.; Baffy, György

    2008-01-01

    Uncoupling protein-2 (UCP2) regulates insulin secretion by controlling ATP levels in β cells. While UCP2 deficiency improves glycemic control in mice, increased expression of UCP2 interferes with glucose-stimulated insulin secretion. These observations link UCP2 to β cell dysfunction in type 2 diabetes with a perplexing evolutionary role. We found higher residual serum insulin levels and blunted lipid metabolic responses in fasted ucp2−/− mice, supporting the concept that UCP2 evolved to suppress insulin effects and to accommodate the fuel switch to fatty acids during starvation. In the absence of UCP2, fasting initially promotes peripheral lipolysis and hepatic fat accumulation at less than expected rates, but culminates in protracted steatosis indicating diminished hepatic utilization and clearance of fatty acids. We conclude that UCP2-mediated control of insulin secretion is a physiologically relevant mechanism of the metabolic response to fasting. PMID:18292186

  14. A fast aerosol microphysical model for the UTLS

    NASA Astrophysics Data System (ADS)

    Tripathi, S.; Grainger, R.; Rogers, H.

    2003-04-01

    A fast aerosol microphysical model for the UTLS (FAMMUS) has been developed to study aerosol behaviour in UTLS region. This model simulates homogeneous heteromolecular nucleation, condensational growth, coagulation and sedimentation of binary sulphuric acid-water particles together to predict the composition and size-distribution of stratospheric aerosols. This model has already been successfully applied to estimate the changes in background stratospheric aerosol surface area due to aircraft sulphur emission (Tripathi et al., 2002). The principal advantage with this model is that it is non-iterative (Jacobson, 1999), i.e. computing time is minimised by finding semi-implicit solutions to aerosol processes. Condensation and coagulation are solved using operator-split method. Hence the effect of coagulation is determined in a single iteration and the solution is volume conserving for any time-step. The semi-implicit solution for coagulation agrees well with the Smoluchowski's solution for a constant coagulation kernel. Similarly, starting from the fundamental growth equation, solution for condensational growth is derived which does not require iteration. The solution conserves mass exactly, and is unconditionally stable. In the model homogeneous nucleation and condensation is coupled in such a manner that it allows for a realistic competition between the two processes for the limited amount of vapour. With geometrically related size bin (44 bins for sulphuric acid-water particles in the range from 0.3 nm to 5mm) and a 600s time-step the model takes about half an hour to complete a 7 year simulation of stratospheric background aerosols on a work station. FAMMUS has been used to simulate background stratospheric aerosols and volcanically disturbed aerosol and model results are compared favourably with results from earlier model studies and observed data.

  15. Modeling the redshift and energy distributions of fast radio bursts

    NASA Astrophysics Data System (ADS)

    Cao, Xiao-Feng; Xiao, Ming; Xiao, Fei

    2017-02-01

    Fast radio bursts (FRBs) are one of the most mysterious astronomical phenomena nowadays. The identification of their origin requires more observations in the future and, importantly, deep understandings of the existing observational data. By fitting the redshift and energy distributions of 15 Parkes FRBs, we try to derive their intrinsic energy function and the cosmic evolution of their burst rates. Specifically, while the energy function is assumed as usual to have a single-power-law form, the burst rates are considered to be proportional to the cosmic star formation rates by a redshift-dependent coefficient. Some plausible fittings are obtained, which indicate the power-law assumptions are feasible and effective. The values of the power-law indices could be used to independently constrain candidate FRB models, although parameter degeneracies still exist.

  16. A Fast Hydrogen Sulfide-Releasing Donor Increases the Tumor Response to Radiotherapy.

    PubMed

    De Preter, Géraldine; Deriemaeker, Caroline; Danhier, Pierre; Brisson, Lucie; Cao Pham, Thanh Trang; Grégoire, Vincent; Jordan, Bénédicte F; Sonveaux, Pierre; Gallez, Bernard

    2016-01-01

    Hydrogen sulfide (H2S) is the last gaseous transmitter identified in mammals, and previous studies have reported disparate conclusions regarding the implication of H2S in cancer progression. In the present study, we hypothesized that sodium hydrosulfide (NaHS), a fast H2S-releasing donor, might interfere with the mitochondrial respiratory chain of tumor cells, increase tumor oxygenation, and potentiate the response to irradiation. Using electron paramagnetic resonance (EPR) oximetry, we found a rapid increase in tumor pO2 after NaHS administration (0.1 mmol/kg) in two human tumor models (breast MDA-MB-231 and cervix SiHa), an effect that was due to a decreased oxygen consumption and an increased tumor perfusion. Tumors irradiated 15 minutes after a single NaHS administration were more sensitive to irradiation compared with those that received irradiation alone (increase in growth delay by 50%). This radiosensitization was due to the oxygen effect, as the increased growth delay was abolished when temporarily clamped tumors were irradiated. In contrast, daily NaHS injection (0.1 mmol/kg/day for 14 days) did not provide any effect on tumor growth in vivo. To understand these paradoxical data, we analyzed the impact of external factors on the cellular response to NaHS. We found that extracellular pH had a dramatic effect on the cell response to NaHS, as the proliferation rate (measured in vitro by BrdU incorporation) was increased at pH = 7.4, but decreased at pH = 6.5. Overall, our study highlights the complex role of environmental components in the response of cancer cells to H2S and suggests a new approach for the use of H2S donors in combination with radiotherapy.

  17. Training and Validation of the Fast PCRTM_Solar Model

    NASA Astrophysics Data System (ADS)

    Yang, Q.; Liu, X.; Wu, W.; Yang, P.; Wang, C.

    2015-12-01

    Fast and accurate radiative transfer model is the key for satellite data assimilation for remote sensing application. The simulation of the satellite remote sensing radiances is very complicated since many physical processes, such as absorption, emission, and scattering, are involved due to the interactions between electromagnetic radiation and earth surface, water vapor, clouds, aerosols, and gas molecules in the sky. The principal component-based radiative transfer model (PCRTM) has been developed for various passive IR and MW instruments. In this work, we extended PCRTM to including the contribution from solar radiation. The cloud/aerosol bidirectional reflectances have been carefully calculated using the well-known Discrete-Ordinate-Method Radiative Transfer (DISORT) model under over 10 millions of diverse conditions with varying cloud particle size, wavelength, satellite viewing direction, and solar angles. The obtained results were compressed significantly using principal component analysis and used in the mono domain radiance calculation. We used 1352 different atmosphere profiles, each of them has different surface skin temperatures and surface pressures in our training. Different surface emissivity spectra were derived from ASTER database and emissivity models. Some artificially generated emissivity spectra were also used to account for diverse surface types of the earth. Concentrations of sixteen trace gases were varied systematically in the training and the remaining trace gas contributions were accounted for as a fixed gas. Training was done in both clear and cloudy skies conditions. Finally the nonlocal thermal equilibrium (NLTE) induced radiance change was included for daytime conditions. We have updated the PCRTM model for instruments such as IASI, NASTI, CrIS, AIRS, and SHIS. The training results show that the PCRTM model can calculate thousands of channel radiances by computing only a few hundreds of mono radiances. This greatly increased the

  18. Aroclor 1254 exposure reduces disease resistance and innate immune responses in fasted arctic charr

    USGS Publications Warehouse

    Maule, A.G.; Jorgensen, E.H.; Vijayan, M.M.; Killie, J.-E.A.

    2005-01-01

    To examine the immunological impacts of polychlorinated biphenyls (PCBs) in an environmentally relevant way, we orally contaminated Arctic charr (Salvelinus alpinus) with Aroclor 1254. After contamination, fish were either fed (0 and 100 mg Aroclor 1254 kg-1 fish wt) or fasted (0, 1, 10, and 100 mg kg-1) to mimic cycles of feeding-fasting experienced by Arctic animals. After four months, PCB concentrations in muscle were the same in fasted and fed fish; however, PCBs in kidneys of fed fish were 33 to 50% of those in fasted fish. Arctic charr were exposed to Aeromonas salmonicida, the bacteria responsible for furunculosis, by cohabitation with infected conspecifics. Fasted fish had a significant trend toward lower survival with higher dose of PCBs - from 68% in controls to 48% in treatment involving 100 mg kg-1. Independent of PCB contamination, fed fish had the lowest survival; we attribute this to stress associated with establishing and maintaining feeding hierarchies. A significant decrease in the activity of lysozyme was observed in skin mucus, as was hemagglutination ability of a putative rhamnose lectin in fasted, but not in fed, PCB-treated fish. These results demonstrate the immunosuppressive effects of PCBs on Arctic charr, and they illustrate the importance of considering environmentally relevant nutritional status in ecotoxicological studies.

  19. Development and Deployment of a "Fast Response" Survey System in Washington State: Methodological Notes

    ERIC Educational Resources Information Center

    Elfers, Ana; Plecki, Marge; Knapp, Michael; Boatright, Beth; Loeb, Hilary

    2004-01-01

    This report describes the technical aspects of the establishment of a "Fast Response Survey System" for the state of Washington. The system, supported by the Stuart Foundation and the newly created Center for Strengthening the Teaching Profession (CSTP), is being designed to offer timely and useful information to the state's policy community…

  20. INVESTIGATION OF OPEN-PATH FTIR FOR FAST DEPLOYMENT EMERGENCY RESPONSE TO CHEMICAL THREATS AND ACCIDENTS.

    EPA Science Inventory

    We have performed a series of experiments to determine the tradeoff in detection sensitivity for implementing design features for an Open-Path Fourier Transform Infrared (OP-FTIR) chemical analyzer that would be quick to deploy under emergency response conditions. The fast-deplo...

  1. INVESTIGATION OF OPEN-PATH FTIR FOR FAST DEPLOYMENT EMERGENCY RESPONSE TO CHEMICAL THREATS AND ACCIDENTS.

    EPA Science Inventory

    We have performed a series of experiments to determine the tradeoff in detection sensitivity for implementing design features for an Open-Path Fourier Transform Infrared (OP-FTIR) chemical analyzer that would be quick to deploy under emergency response conditions. The fast-deplo...

  2. Polylactide-based polyurethane shape memory nanocomposites (Fe3O4/PLAUs) with fast magnetic responsiveness

    NASA Astrophysics Data System (ADS)

    Gu, Shu-Ying; Jin, Sheng-Peng; Gao, Xie-Feng; Mu, Jian

    2016-05-01

    Polylactide-based polyurethane shape memory nanocomposites (Fe3O4/PLAUs) with fast magnetic responsiveness are presented. For the purpose of fast response and homogeneous dispersion of magnetic nanoparticles, oleic acid was used to improve the dispersibility of Fe3O4 nanoparticles in a polymer matrix. A homogeneous distribution of Fe3O4 nanoparticles in the polymer matrix was obtained for nanocomposites with low Fe3O4 loading content. A small agglomeration was observed for nanocomposites with 6 wt% and 9 wt% loading content, leading to a small decline in the mechanical properties. PLAU and its nanocomposites have glass transition around 52 °C, which can be used as the triggering temperature. PLAU and its nanocomposites have shape fixity ratios above 99%, shape recovery ratios above 82% for the first cycle and shape recovery ratios above 91% for the second cycle. PLAU and its nanocomposites also exhibit a fast water bath or magnetic responsiveness. The magnetic recovery time decreases with an increase in the loading content of Fe3O4 nanoparticles due to an improvement in heating performance for increased weight percentage of fillers. The nanocomposites have fast responses in an alternating magnetic field and have potential application in biomedical areas such as intravascular stent.

  3. Model biases in high-burnup fast reactor simulations

    SciTech Connect

    Touran, N.; Cheatham, J.; Petroski, R.

    2012-07-01

    A new code system called the Advanced Reactor Modeling Interface (ARMI) has been developed that loosely couples multiscale, multiphysics nuclear reactor simulations to provide rapid, user-friendly, high-fidelity full systems analysis. Incorporating neutronic, thermal-hydraulic, safety/transient, fuel performance, core mechanical, and economic analyses, ARMI provides 'one-click' assessments of many multi-disciplined performance metrics and constraints that historically require iterations between many diverse experts. The capabilities of ARMI are implemented in this study to quantify neutronic biases of various modeling approximations typically made in fast reactor analysis at an equilibrium condition, after many repetitive shuffles. Sensitivities at equilibrium that result in very high discharge burnup are considered ( and >20% FIMA), as motivated by the development of the Traveling Wave Reactor. Model approximations discussed include homogenization, neutronic and depletion mesh resolution, thermal-hydraulic coupling, explicit control rod insertion, burnup-dependent cross sections, fission product model, burn chain truncation, and dynamic fuel performance. The sensitivities of these approximations on equilibrium discharge burnup, k{sub eff}, power density, delayed neutron fraction, and coolant temperature coefficient are discussed. (authors)

  4. Fast reconstruction of compact context-specific metabolic network models.

    PubMed

    Vlassis, Nikos; Pacheco, Maria Pires; Sauter, Thomas

    2014-01-01

    Systemic approaches to the study of a biological cell or tissue rely increasingly on the use of context-specific metabolic network models. The reconstruction of such a model from high-throughput data can routinely involve large numbers of tests under different conditions and extensive parameter tuning, which calls for fast algorithms. We present fastcore, a generic algorithm for reconstructing context-specific metabolic network models from global genome-wide metabolic network models such as Recon X. fastcore takes as input a core set of reactions that are known to be active in the context of interest (e.g., cell or tissue), and it searches for a flux consistent subnetwork of the global network that contains all reactions from the core set and a minimal set of additional reactions. Our key observation is that a minimal consistent reconstruction can be defined via a set of sparse modes of the global network, and fastcore iteratively computes such a set via a series of linear programs. Experiments on liver data demonstrate speedups of several orders of magnitude, and significantly more compact reconstructions, over a rival method. Given its simplicity and its excellent performance, fastcore can form the backbone of many future metabolic network reconstruction algorithms.

  5. Fast Reconstruction of Compact Context-Specific Metabolic Network Models

    PubMed Central

    Sauter, Thomas

    2014-01-01

    Systemic approaches to the study of a biological cell or tissue rely increasingly on the use of context-specific metabolic network models. The reconstruction of such a model from high-throughput data can routinely involve large numbers of tests under different conditions and extensive parameter tuning, which calls for fast algorithms. We present fastcore, a generic algorithm for reconstructing context-specific metabolic network models from global genome-wide metabolic network models such as Recon X. fastcore takes as input a core set of reactions that are known to be active in the context of interest (e.g., cell or tissue), and it searches for a flux consistent subnetwork of the global network that contains all reactions from the core set and a minimal set of additional reactions. Our key observation is that a minimal consistent reconstruction can be defined via a set of sparse modes of the global network, and fastcore iteratively computes such a set via a series of linear programs. Experiments on liver data demonstrate speedups of several orders of magnitude, and significantly more compact reconstructions, over a rival method. Given its simplicity and its excellent performance, fastcore can form the backbone of many future metabolic network reconstruction algorithms. PMID:24453953

  6. Linear model for fast background subtraction in oligonucleotide microarrays

    PubMed Central

    2009-01-01

    Background One important preprocessing step in the analysis of microarray data is background subtraction. In high-density oligonucleotide arrays this is recognized as a crucial step for the global performance of the data analysis from raw intensities to expression values. Results We propose here an algorithm for background estimation based on a model in which the cost function is quadratic in a set of fitting parameters such that minimization can be performed through linear algebra. The model incorporates two effects: 1) Correlated intensities between neighboring features in the chip and 2) sequence-dependent affinities for non-specific hybridization fitted by an extended nearest-neighbor model. Conclusion The algorithm has been tested on 360 GeneChips from publicly available data of recent expression experiments. The algorithm is fast and accurate. Strong correlations between the fitted values for different experiments as well as between the free-energy parameters and their counterparts in aqueous solution indicate that the model captures a significant part of the underlying physical chemistry. PMID:19917117

  7. Generalizability in Item Response Modeling

    ERIC Educational Resources Information Center

    Briggs, Derek C.; Wilson, Mark

    2007-01-01

    An approach called generalizability in item response modeling (GIRM) is introduced in this article. The GIRM approach essentially incorporates the sampling model of generalizability theory (GT) into the scaling model of item response theory (IRT) by making distributional assumptions about the relevant measurement facets. By specifying a random…

  8. Generalizability in Item Response Modeling

    ERIC Educational Resources Information Center

    Briggs, Derek C.; Wilson, Mark

    2007-01-01

    An approach called generalizability in item response modeling (GIRM) is introduced in this article. The GIRM approach essentially incorporates the sampling model of generalizability theory (GT) into the scaling model of item response theory (IRT) by making distributional assumptions about the relevant measurement facets. By specifying a random…

  9. Endogenous circulating ghrelin does not mediate growth hormone rhythmicity or response to fasting.

    PubMed

    Avram, Anca M; Jaffe, Craig A; Symons, Kathleen V; Barkan, Ariel L

    2005-05-01

    GH secretory profiles in humans are pulsatile and exhibit nocturnal elevation during the early hours of sleep. Fasting augments GH output and rhythmicity. Ghrelin was suggested to exhibit nocturnal increases and to rise in response to nutritional deprivation. We examined whether ghrelin may be an underlying mechanism of GH rhythmicity and response to fasting. We studied nine young healthy subjects during normal feeding and after 2 d of complete fasting. Plasma GH was measured every 10 min, and plasma total and active ghrelins were measured every 20 min. Fasting augmented mean daily plasma GH (1.47 +/- 0.25 vs. 3.30 +/- 0.6 microg/liter; P = 0.012). Neither mean daily total ghrelin (4.19 +/- 0.64 vs. 4.35 +/- 0.74 microg/liter; P = 0.75) nor mean daily active ghrelin (0.13 +/- 0.02 vs. 0.13 +/- 0.02 microg/liter; P = 0.34) changed as a result of fasting. All subjects exhibited nocturnal augmentation of GH secretion; there were no corresponding nocturnal increases in either total or active ghrelin concentrations. Similarly, cross-correlation analysis failed to find any relation between GH and ghrelin pulses. We conclude that ghrelin is unlikely to be of importance in the generation of rhythmic or nutritionally mediated GH secretion.

  10. Cardiovascular response to short-term fasting in menstrual phases in young women: an observational study.

    PubMed

    Ohara, Kumiko; Okita, Yoshimitsu; Kouda, Katsuyasu; Mase, Tomoki; Miyawaki, Chiemi; Nakamura, Harunobu

    2015-08-28

    Menstrual cycle-related symptoms are an important health issue for many women, and some may affect cardiac autonomic regulation. In the present study, we evaluated the cardiovascular and physiological stress response to 12-h short-term fasting in the menstrual phases of healthy young women. We performed a randomized crossover study. Subjects were seven female university students (age: 22.3 ± 1.0 years). The experiments comprised four sessions: meal intake in the follicular phase, meal intake in the luteal phase, fasting in the follicular phase, and fasting in the luteal phase. All subjects participated in a total of four experimental sessions during two successive phases (follicular and luteal phase in the same menstrual cycle, or luteal phase and follicular phase in the next menstrual cycle) according to a randomized crossover design. R-R intervals were continuously recorded before and after meals, and power spectral analysis of heart rate variability was performed. Other physiological data were obtained before and 20, 40, 60, and 80 min after meal intake or after the corresponding time point of meal intake (fasting in the follicular or luteal phase). Heart rate decreased during fasting in the follicular and luteal phases. High frequency power increased during fasting in the follicular and luteal phases. In addition, salivary cortisol concentrations decreased during fasting in the luteal phase. In the present study, short-term fasting resulted in higher parasympathetic activity and lower cortisol levels in the luteal phase in these young women. These results indicate a possibility to produce an anti-stress effect in the luteal phase, which may reduce menstrual symptoms.

  11. Fast Numerically Based Modeling for Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Sassen, D. S.; Everett, M. E.

    2007-05-01

    There is a need for computationally fast GPR numerical modeling. This includes circumstances where real time performance is needed, for example discrimination of landmines or UXO's, and in circumstances that require a high number of successive forward problems, for example inversion or imaging. Traditional numerical techniques such as finite difference or finite element are too slow for these applications, but they provide results from general scenarios such as scattering from very complicated shapes with high contrast. Neural networks may fit in the niche between analytical techniques and traditional numerical techniques. Our concept is training a neural network to associate the model inputs of electromagnetic properties of the background and targets, and the size and shape of the targets, with the output generated by a 3-D finite difference model. Successive examples from various electromagnetic properties and targets are displayed to the neural network, until the neural network has adapted itself though optimization. The trained neural network is now used as the forward model by displaying new input parameters and the neural network then generates the appropriate output. The results from the neural network are then compared to results from finite difference models to see how well the neural networks is performing and at what point it breaks down. Areas of poor fit can be addressed through further training. The neural network GPR model can be adapted by displaying additional finite difference results to the neural network, and can also be adapted to a specific field area by actual field data examples. Because of this adaptation ability the neural network GPR model can be optimized for specific environments and applications.

  12. Metabolic and psychological response to 7-day fasting in obese patients with and without metabolic syndrome.

    PubMed

    Li, Chenying; Ostermann, Thomas; Hardt, Monika; Lüdtke, Rainer; Broecker-Preuss, Martina; Dobos, Gustav; Michalsen, Andreas

    2013-01-01

    Extended modified fasting is a frequently practiced tradition in Europe. It is claimed to improve the cardiometabolic state and physical and psychological well-being by an evolutionary co-developed adaptation response. We aimed to investigate the cardiometabolic and psychological effects of a 7-day fast and differences of these responses between patients with or without metabolic syndrome (MetS). We investigated 30 female subjects (49.0 ± 8.1 years, BMI 30.4 ± 6.7 kg/m(2)) with (n = 12) and without (n = 18) MetS. All subjects participated in a 7-day fast according to Buchinger with a nutritional energy intake of 300 kcal/day and stepwise reintroduction of solid food thereafter. Outcomes were assessed baseline and after fasting and included measures of metabolic and glucoregulatory control, adipokines as well as psychological well-being as assessed by Profile of Mood States (POMS) and Hospital Anxiety and Depression Scale (HADS). Mean weight decreased from 85.4 ± 18.8 kg to 79.7 ± 18.2 kg accompanied by systolic/diastolic blood pressure (BP) reduction of -16.2 mm Hg (95% CI: -9.1; -23.3 mm Hg) and -6.0 mm Hg (95% CI: -1.8; -10.3 mm Hg), each p < 0.001 and p = 0.005. Fasting led to marked decreases of levels of LDL-cholesterol, leptin, and insulin and increases of levels of adiponectin, leptin receptors, and resistin. Fasting-induced mood enhancement was reflected by decreased anxiety, depression, fatigue, and improved vigor. Patients with MetS showed some greater changes in B P, LDL-cholesterol, triglycerides, adiponectin, leptin, and sleep quality. Fasting was well-tolerated. Our results point to marked beneficial responses to 7-day modified fasting and a potential role in the prevention of the MetS. Randomized trials with longer observation periods should test the clinical effectiveness of fasting in metabolic diseases. © 2014 S. Karger GmbH, Freiburg.

  13. Ghrelin mimics fasting to enhance human hedonic, orbitofrontal cortex, and hippocampal responses to food.

    PubMed

    Goldstone, Anthony P; Prechtl, Christina G; Scholtz, Samantha; Miras, Alexander D; Chhina, Navpreet; Durighel, Giuliana; Deliran, Seyedeh S; Beckmann, Christian; Ghatei, Mohammad A; Ashby, Damien R; Waldman, Adam D; Gaylinn, Bruce D; Thorner, Michael O; Frost, Gary S; Bloom, Stephen R; Bell, Jimmy D

    2014-06-01

    Ghrelin, which is a stomach-derived hormone, increases with fasting and energy restriction and may influence eating behaviors through brain hedonic reward-cognitive systems. Therefore, changes in plasma ghrelin might mediate counter-regulatory responses to a negative energy balance through changes in food hedonics. We investigated whether ghrelin administration (exogenous hyperghrelinemia) mimics effects of fasting (endogenous hyperghrelinemia) on the hedonic response and activation of brain-reward systems to food. In a crossover design, 22 healthy, nonobese adults (17 men) underwent a functional magnetic resonance imaging (fMRI) food-picture evaluation task after a 16-h overnight fast (Fasted-Saline) or after eating breakfast 95 min before scanning (730 kcal, 14% protein, 31% fat, and 55% carbohydrate) and receiving a saline (Fed-Saline) or acyl ghrelin (Fed-Ghrelin) subcutaneous injection before scanning. One male subject was excluded from the fMRI analysis because of excess head motion, which left 21 subjects with brain-activation data. Compared with the Fed-Saline visit, both ghrelin administration to fed subjects (Fed-Ghrelin) and fasting (Fasted-Saline) significantly increased the appeal of high-energy foods and associated orbitofrontal cortex activation. Both fasting and ghrelin administration also increased hippocampus activation to high-energy- and low-energy-food pictures. These similar effects of endogenous and exogenous hyperghrelinemia were not explicable by consistent changes in glucose, insulin, peptide YY, and glucagon-like peptide-1. Neither ghrelin administration nor fasting had any significant effect on nucleus accumbens, caudate, anterior insula, or amygdala activation during the food-evaluation task or on auditory, motor, or visual cortex activation during a control task. Ghrelin administration and fasting have similar acute stimulatory effects on hedonic responses and the activation of corticolimbic reward-cognitive systems during food

  14. Transcription factor assisted loading and enhancer dynamics dictate the hepatic fasting response

    PubMed Central

    Goldstein, Ido; Baek, Songjoon; Presman, Diego M.; Paakinaho, Ville; Swinstead, Erin E.; Hager, Gordon L.

    2017-01-01

    Fasting elicits transcriptional programs in hepatocytes leading to glucose and ketone production. This transcriptional program is regulated by many transcription factors (TFs). To understand how this complex network regulates the metabolic response to fasting, we aimed at isolating the enhancers and TFs dictating it. Measuring chromatin accessibility revealed that fasting massively reorganizes liver chromatin, exposing numerous fasting-induced enhancers. By utilizing computational methods in combination with dissecting enhancer features and TF cistromes, we implicated four key TFs regulating the fasting response: glucocorticoid receptor (GR), cAMP responsive element binding protein 1 (CREB1), peroxisome proliferator activated receptor alpha (PPARA), and CCAAT/enhancer binding protein beta (CEBPB). These TFs regulate fuel production by two distinctly operating modules, each controlling a separate metabolic pathway. The gluconeogenic module operates through assisted loading, whereby GR doubles the number of sites occupied by CREB1 as well as enhances CREB1 binding intensity and increases accessibility of CREB1 binding sites. Importantly, this GR-assisted CREB1 binding was enhancer-selective and did not affect all CREB1-bound enhancers. Single-molecule tracking revealed that GR increases the number and DNA residence time of a portion of chromatin-bound CREB1 molecules. These events collectively result in rapid synergistic gene expression and higher hepatic glucose production. Conversely, the ketogenic module operates via a GR-induced TF cascade, whereby PPARA levels are increased following GR activation, facilitating gradual enhancer maturation next to PPARA target genes and delayed ketogenic gene expression. Our findings reveal a complex network of enhancers and TFs that dynamically cooperate to restore homeostasis upon fasting. PMID:28031249

  15. New models for fast steady state magnetic reconnection

    NASA Technical Reports Server (NTRS)

    Priest, E. R.; Forbes, T. G.

    1986-01-01

    A new unified family of models for incompressible, steady-state magnetic reconnection in a finite region is presented. The models are obtained by expanding in powers of the Alfven Mach number and may be used to elucidate some of the puzzling properties of numerical experiments on reconnection which are not present in the classical models. The conditions imposed on the inflow boundary of the finite region determine which member of the family occurs. Petscheklien and Sonnerup like solutions are particular members. The Sonneruplike regime is a special case of a weak slow mode expansion in the inflow region, and it separates two classes of members with reversed currents. The Petscheklike regime is a singular case of a weak fast mode expansion, and it separates the hybrid regime from a regime of slow mode compressions. Care should be taken in deciding which type of reconnection is operating in a numerical experiment. Indeed, no experiment to date has used boundary conditions appropriate for demonstrating steady state Petschek reconnection.

  16. Effect of fasting versus feeding on the bone metabolic response to running.

    PubMed

    Scott, Jonathan P R; Sale, Craig; Greeves, Julie P; Casey, Anna; Dutton, John; Fraser, William D

    2012-12-01

    Individuals often perform exercise in the fasted state, but the effects on bone metabolism are not currently known. We compared the effect of an overnight fast with feeding a mixed meal on the bone metabolic response to treadmill running. Ten, physically-active males aged 28 ± 4y (mean ±SD) completed two, counterbalanced, 8d trials. After 3d on a standardised diet, participants performed 60 min of treadmill running at 65% VO(2max) on Day 4 following an overnight fast (FAST) or a standardised breakfast (FED). Blood samples were collected at baseline, before and during exercise, for 3h after exercise, and on four consecutive follow-up days (FU1-FU4). Plasma/serum were analysed for the c-terminal telopeptide region of collagen type 1 (β-CTX), n-terminal propeptides of procollagen type 1 (P1NP), osteocalcin (OC), bone alkaline phosphatase (bone ALP), parathyroid hormone (PTH), albumin-adjusted calcium, phosphate, osteoprotegerin (OPG), cortisol, leptin and ghrelin. Only the β-CTX response was significantly affected by feeding. Pre-exercise concentrations decreased more in FED compared with FAST (47% vs 26%, P<0.001) but increased during exercise in both groups and were not significantly different from baseline at 1h post-exercise. At 3h post-exercise, concentrations were decreased (33%, P<0.001) from baseline in FAST and significantly lower (P<0.001) than in FED. P1NP and PTH increased, and OC decreased during exercise. Bone markers were not significantly different from baseline on FU1-FU4. Fasting had only a minor effect on the bone metabolic response to subsequent acute, endurance exercise, reducing the duration of the increase in β-CTX during early recovery, but having no effect on changes in bone formation markers. The reduced duration of the β-CTX response with fasting was not fully explained by changes in PTH, OPG, leptin or ghrelin. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Metabolomics of Ramadan fasting: an opportunity for the controlled study of physiological responses to food intake.

    PubMed

    Mathew, Sweety; Krug, Susanne; Skurk, Thomas; Halama, Anna; Stank, Antonia; Artati, Anna; Prehn, Cornelia; Malek, Joel A; Kastenmüller, Gabi; Römisch-Margl, Werner; Adamski, Jerzy; Hauner, Hans; Suhre, Karsten

    2014-06-06

    High-throughput screening techniques that analyze the metabolic endpoints of biological processes can identify the contributions of genetic predisposition and environmental factors to the development of common diseases. Studies applying controlled physiological challenges can reveal dysregulation in metabolic responses that may be predictive for or associated with these diseases. However, large-scale epidemiological studies with well controlled physiological challenge conditions, such as extended fasting periods and defined food intake, pose logistic challenges. Culturally and religiously motivated behavioral patterns of life style changes provide a natural setting that can be used to enroll a large number of study volunteers. Here we report a proof of principle study conducted within a Muslim community, showing that a metabolomics study during the Holy Month of Ramadan can provide a unique opportunity to explore the pre-prandial and postprandial response of human metabolism to nutritional challenges. Up to five blood samples were obtained from eleven healthy male volunteers, taken directly before and two hours after consumption of a controlled meal in the evening on days 7 and 26 of Ramadan, and after an over-night fast several weeks after Ramadan. The observed increases in glucose, insulin and lactate levels at the postprandial time point confirm the expected physiological response to food intake. Targeted metabolomics further revealed significant and physiologically plausible responses to food intake by an increase in bile acid and amino acid levels and a decrease in long-chain acyl-carnitine and polyamine levels. A decrease in the concentrations of a number of phospholipids between samples taken on days 7 and 26 of Ramadan shows that the long-term response to extended fasting may differ from the response to short-term fasting. The present study design is scalable to larger populations and may be extended to the study of the metabolic response in defined patient

  18. Metabolomics of Ramadan fasting: an opportunity for the controlled study of physiological responses to food intake

    PubMed Central

    2014-01-01

    High-throughput screening techniques that analyze the metabolic endpoints of biological processes can identify the contributions of genetic predisposition and environmental factors to the development of common diseases. Studies applying controlled physiological challenges can reveal dysregulation in metabolic responses that may be predictive for or associated with these diseases. However, large-scale epidemiological studies with well controlled physiological challenge conditions, such as extended fasting periods and defined food intake, pose logistic challenges. Culturally and religiously motivated behavioral patterns of life style changes provide a natural setting that can be used to enroll a large number of study volunteers. Here we report a proof of principle study conducted within a Muslim community, showing that a metabolomics study during the Holy Month of Ramadan can provide a unique opportunity to explore the pre-prandial and postprandial response of human metabolism to nutritional challenges. Up to five blood samples were obtained from eleven healthy male volunteers, taken directly before and two hours after consumption of a controlled meal in the evening on days 7 and 26 of Ramadan, and after an over-night fast several weeks after Ramadan. The observed increases in glucose, insulin and lactate levels at the postprandial time point confirm the expected physiological response to food intake. Targeted metabolomics further revealed significant and physiologically plausible responses to food intake by an increase in bile acid and amino acid levels and a decrease in long-chain acyl-carnitine and polyamine levels. A decrease in the concentrations of a number of phospholipids between samples taken on days 7 and 26 of Ramadan shows that the long-term response to extended fasting may differ from the response to short-term fasting. The present study design is scalable to larger populations and may be extended to the study of the metabolic response in defined patient

  19. [Influence of tenotomy on posttetanic responses of the rat fast and slow muscle].

    PubMed

    Arutiunian, R S; Zhabko, E P

    2011-08-01

    The effect of two weeks of tenotomy on posttetanic isometric contractile responses of the rat fast: Extensor digitorum longus and slow: soleus muscles was studied in experiments on isolated muscle preparations. Direct tetanic stimulation (100 impulses, 50 Hz) increased the force of contractions by 20-25% (p < 0.05) of both, control and tenotomized fast muscles. Identical to above tetanic stimulation of control, slow muscle resulted in posttetanic depression, a decrease in the amplitude of contractile responses. Tenotomized slow muscles did not develop posttetanic depression. Caffeine (4 mM) increased and dandrolene (10 microM) decreased the force of unitary and tetanic contractions of control and tenotomized muscles. Neither drug, however, affected development of posttetanic phenomena in ether fast or slow muscles. The fact that in extensor digitorum longus, posttetanic potentiation is preserved for at least forty days of tenotomy but disappears after only 2 weeks of denervation suggests important role of neurotrophic influences in regulation of posttetanic responses of fast muscles.

  20. Fast-response liquid-crystal lens for 3D displays

    NASA Astrophysics Data System (ADS)

    Liu, Yifan; Ren, Hongwen; Xu, Su; Li, Yan; Wu, Shin-Tson

    2014-02-01

    Three-dimensional (3D) display has become an increasingly important technology trend for information display applications. Dozens of different 3D display solutions have been proposed. The autostereoscopic 3D display based on lenticular microlens array is a promising approach, and fast-switching microlens array enables this system to display both 3D and conventional 2D images. Here we report two different fast-response microlens array designs. The first one is a blue phase liquid crystal lens driven by the Pedot: PSS resistive film electrodes. This BPLC lens exhibits several attractive features, such as polarization insensitivity, fast response time, simple driving scheme, and relatively low driving voltage, as compared to other BPLC lens designs. The second lens design has a double-layered structure. The first layer is a polarization dependent polymer microlens array, and the second layer is a thin twisted-nematic (TN) liquid crystal cell. When the TN cell is switched on/off, the traversing light through the polymeric lens array is either focused or defocused, so that 2D/3D images are displayed correspondingly. This lens design has low driving voltage, fast response time, and simple driving scheme. Simulation and experiment demonstrate that the performance of both switchable lenses meet the requirement of 3D display system design.

  1. Calibration, characterisation and Monte Carlo modelling of a fast-UNCL

    NASA Astrophysics Data System (ADS)

    Tagziria, Hamid; Bagi, Janos; Peerani, Paolo; Belian, Antony

    2012-09-01

    This paper describes the calibration, characterisation and Monte Carlo modelling of a new IAEA Uranium Neutron Collar (UNCL) for LWR fuel, which can be operated in both passive and active modes. It can employ either 35 3He tubes (in active configuration) or 44 tubes at 10 atm pressure (in its passive configuration) and thus can be operated in fast mode (with Cd liner) as its efficiency is higher than that of the standard UNCL. Furthermore, it has an adjustable internal cavity which allows the measurement of varying sizes of fuel assemblies such as WWER, PWR and BWR. It is intended to be used with Cd liners in active mode (with an AmLi interrogation source in place) by the inspectorate for the determination of the 235U content in fresh fuel assemblies, especially in cases where high concentrations of burnable poisons cause problems with accurate assays. A campaign of measurements has been carried out at the JRC Performance Laboratories (PERLA) in Ispra (Italy) using various radionuclide neutron sources (252Cf, 241AmLi and PuGa) and our BWR and PWR reference assemblies, in order to calibrate and characterise the counter as well as assess its performance and determine its optimum operational parameters. Furthermore, the fast-UNCL has been extensively modelled at JRC using the Monte Carlo code, MCNP-PTA, which simulates both the neutron transport and the coincidence electronics. The model has been validated using our measurements which agreed well with calculations. The WWER1000 fuel assembly for which there are no representative reference materials for an adequate calibration of the counter, has also been modelled and the response of the counter to this fuel assembly has been simulated. Subsequently numerical calibrations curves have been obtained for the above fuel assemblies in various modes (fast and thermal). The sensitivity of the counter to fuel rods substitution as well as other important aspects and the parameters of the fast-UNCL performance have been

  2. A Fast Infrared Radiative Transfer Model for Overlapping Clouds

    NASA Technical Reports Server (NTRS)

    Niu, Jianguo; Yang, Ping; Huang, Huang-Lung; Davies, James E.; Li, Jun; Baum, Bryan A.; Hu, Yong X.

    2006-01-01

    A fast infrared radiative transfer model (FIRTM2) appropriate for application to both single-layered and overlapping cloud situations is developed for simulating the outgoing infrared spectral radiance at the top of the atmosphere (TOA). In FIRTM2 a pre-computed library of cloud reflectance and transmittance values is employed to account for one or two cloud layers, whereas the background atmospheric optical thickness due to gaseous absorption can be computed from a clear-sky radiative transfer model. FIRTM2 is applicable to three atmospheric conditions: 1) clear-sky, 2) single-layered ice or water cloud, and 3) two simultaneous cloud layers in a column (e.g., ice cloud overlying water cloud). Moreover, FIRTM2 outputs the derivatives (i.e., Jacobians) of the TOA brightness temperature with respect to cloud optical thickness and effective particle size. Sensitivity analyses have been carried out to assess the performance of FIRTM2 for two spectral regions, namely the longwave (LW) band (587.3 - 1179.5/cm) and the short-to-medium wave (SMW) band (1180.1 - 2228.9/cm). The assessment is carried out in terms of brightness temperature differences (BTD) between FIRTM2 and the well-known discrete ordinates radiative transfer model (DISORT), henceforth referred to as BTD (F-D). The BTD (F-D) values for single-layered clouds are generally less than 0.8 K. For the case of two cloud layers (specifically ice cloud over water cloud), the BTD(F-D) values are also generally less than 0.8 K except for the SMW band for the case of a very high altitude (>15 km) cloud comprised of small ice particles. Note that for clear-sky atmospheres, FIRTM2 reduces to the clear-sky radiative transfer model that is incorporated into FIRTM2, and the errors in this case are essentially those of the clear-sky radiative transfer model.

  3. Hypothalamic responses to fasting indicate metabolic reprogramming away from glycolysis toward lipid oxidation.

    PubMed

    Poplawski, Michal M; Mastaitis, Jason W; Yang, Xue-Jun; Mobbs, Charles V

    2010-11-01

    Nutrient-sensitive hypothalamic neurons regulate energy balance and glucose homeostasis, but the molecular mechanisms mediating hypothalamic responses to nutritional state remain incompletely characterized. To address these mechanisms, the present studies used quantitative PCR to characterize the expression of a panel of genes the hypothalamic expression by nutritional status of which had been suggested by DNA microarray studies. Although these genes regulate a variety of function, the most prominent set regulate intermediary metabolism, and the overall pattern clearly indicated that a 48-h fast produced a metabolic reprogramming away from glucose metabolism and toward the utilization of alternative fuels, particularly lipid metabolism. This general reprogramming of intermediary metabolism by fasting was observed both in cortex and hypothalamus but most prominently in hypothalamus. The effect of fasting on the expression of these genes may be mediated by reduction in plasma glucose or glucose metabolism, rather than leptin, because they were generally recapitulated by hypoglycemia even in the presence of elevated insulin and in vitro by low glucose but were not recapitulated in ob/ob mice. These studies suggest that fasting reduces glucose metabolism and thus minimizes the production of hypothalamic malonyl-coenzyme A. However, because the reprogramming of glucose metabolism by fasting was also observed in cortex, this apparent substrate competition may mediate more general responses to nutritional deprivation, including those responsible for the protective effects of dietary restriction. The present studies also provide a large panel of novel glucose-regulated genes that can be used as markers of glucose action to address mechanisms mediating hypothalamic responses to nutritional state.

  4. Fast ionospheric response to enhanced activity in geospace: Ion feeding of the inner magnetotail

    SciTech Connect

    Daglis, I.A.; Axford, I.A.

    1996-03-01

    The authors look at the question of the ionosphere feeding ions into the magnetosphere/magnetotail, in response to magnetic storm activity, or coupling of the solar wind into the system. They are concerned with fast response, not the question of whether the ionosphere feeds ions in general. The dynamics which results in the inner magnetosphere in response to the input of cold ions from the ionosphere is of interest to the authors. They review recent and older data which has shed light on this question. They look at outflow data, and heating mechanisms for these cold ions, as well as the impact such ions may have on the dynamics of magnetic storms. They observe that fast feeding of ions out of the ionosphere may leave the inner magnetosphere heavily populated with heavy ions such as O{sup +}, which can have a definite impact on the dynamic development of the magnetosphere.

  5. Fast response and recovery of hydrogen sensing in Pd-Pt nanoparticle-graphene composite layers.

    PubMed

    Kumar, Rakesh; Varandani, Deepak; Mehta, B R; Singh, V N; Wen, Zhenhai; Feng, Xinliang; Müllen, Klaus

    2011-07-08

    This study reports the fast response and recovery of hydrogen sensing in nanoparticle-graphene composite layers fabricated using chemical methods and comprising of isolated Pd alloy nanoparticles dispersed onto graphene layers. For 2% hydrogen at 40 °C and 1 atm pressure, a response time of <2 s and a recovery time of 18 s are observed. The fast response and recovery observed during sensing are due to hydrogen-induced changes in the work function of the Pd alloy and modification in the distribution of defect states in the graphene band gap due to gas adsorption. The results of hydrogen sensing in the new class of Pd-Pt nanoparticle-graphene composite material are important for understanding the effect of gas adsorption on electronic conduction in graphene layers and for developing a new type of gas sensor based on changes in the electronic properties of the interface.

  6. Fast response and recovery of hydrogen sensing in Pd-Pt nanoparticle-graphene composite layers

    NASA Astrophysics Data System (ADS)

    Kumar, Rakesh; Varandani, Deepak; Mehta, B. R.; Singh, V. N.; Wen, Zhenhai; Feng, Xinliang; Müllen, Klaus

    2011-07-01

    This study reports the fast response and recovery of hydrogen sensing in nanoparticle-graphene composite layers fabricated using chemical methods and comprising of isolated Pd alloy nanoparticles dispersed onto graphene layers. For 2% hydrogen at 40 °C and 1 atm pressure, a response time of < 2 s and a recovery time of 18 s are observed. The fast response and recovery observed during sensing are due to hydrogen-induced changes in the work function of the Pd alloy and modification in the distribution of defect states in the graphene band gap due to gas adsorption. The results of hydrogen sensing in the new class of Pd-Pt nanoparticle-graphene composite material are important for understanding the effect of gas adsorption on electronic conduction in graphene layers and for developing a new type of gas sensor based on changes in the electronic properties of the interface.

  7. MACULA: Fast Modeling of Rotational Modulations of Spotty Stars

    NASA Astrophysics Data System (ADS)

    Kipping, David

    2015-08-01

    Rotational modulations are frequently observed on stars observed by photometry surveys such as Kepler, with periodicities ranging from days to months and amplitudes of sub-parts-per-million to several percent. These variations may be studied to reveal important stellar properties such as rotational periods, inclinations and gradients of differential rotation. However, inverting the disk-integrated flux into a solution for spot number, sizes, contrasts, etc is highly degenerate and thereby necessitating an exhaustive search of the parameter space. In recognition of this, the software MACULA is designed to be a fast forward model of circular, grey spots on rotating stars, including effects such as differential rotation, spot evolution and even spot penumbra/umbra. MACULA seeks to achieve computational efficiency by using a wholly analytic description of the disk-integrated flux, which is described in Kipping (2012), leading to a computational improvement of three orders-of-magnitude over its numerical counterparts. As part of the hack day, I'll show how to simulate light curves with MACULA and provide examples with visualizations. I will also discuss the on-going development of the code, which will head towards modeling spot crossing events and radial velocity jitter and I encourage discussions amongst the participants on analytic methods to this end.

  8. Fast radio burst source properties and curvature radiation model

    NASA Astrophysics Data System (ADS)

    Kumar, Pawan; Lu, Wenbin; Bhattacharya, Mukul

    2017-07-01

    We use the observed properties of fast radio bursts (FRBs) and a number of general physical considerations to provide a broad-brush model for the physical properties of FRB sources and the radiation mechanism. We show that the magnetic field in the source region should be at least 1014 G. This strong field is required to ensure that the electrons have sufficiently high ground state Landau energy so that particle collisions, instabilities and strong electromagnetic fields associated with the FRB radiation do not perturb electrons' motion in the direction transverse to the magnetic field and destroy their coherent motion; coherence is required by the high observed brightness temperature of FRB radiation. The electric field in the source region required to sustain particle motion for a wave period is estimated to be of the order of 1011 esu. These requirements suggest that FRBs are produced near the surface of magnetars perhaps via forced reconnection of magnetic fields to produce episodic, repeated, outbursts. The beaming-corrected energy release in these bursts is estimated to be about 1036 erg, whereas the total energy in the magnetic field is at least ˜1045 erg. We provide a number of predictions for this model which can be tested by future observations. One of which is that short duration FRB-like bursts should exist at much higher frequencies, possibly up to optical.

  9. Fast Virtual Stenting with Active Contour Models in Intracranical Aneurysm

    PubMed Central

    Zhong, Jingru; Long, Yunling; Yan, Huagang; Meng, Qianqian; Zhao, Jing; Zhang, Ying; Yang, Xinjian; Li, Haiyun

    2016-01-01

    Intracranial stents are becoming increasingly a useful option in the treatment of intracranial aneurysms (IAs). Image simulation of the releasing stent configuration together with computational fluid dynamics (CFD) simulation prior to intervention will help surgeons optimize intervention scheme. This paper proposed a fast virtual stenting of IAs based on active contour model (ACM) which was able to virtually release stents within any patient-specific shaped vessel and aneurysm models built on real medical image data. In this method, an initial stent mesh was generated along the centerline of the parent artery without the need for registration between the stent contour and the vessel. Additionally, the diameter of the initial stent volumetric mesh was set to the maximum inscribed sphere diameter of the parent artery to improve the stenting accuracy and save computational cost. At last, a novel criterion for terminating virtual stent expanding that was based on the collision detection of the axis aligned bounding boxes was applied, making the stent expansion free of edge effect. The experiment results of the virtual stenting and the corresponding CFD simulations exhibited the efficacy and accuracy of the ACM based method, which are valuable to intervention scheme selection and therapy plan confirmation. PMID:26876026

  10. Does fasting influence preload responsiveness in ASA 1 and 2 volunteers?

    PubMed

    Alves, Daniel Rodrigues; Ribeiras, Regina

    Preoperative fasting was long regarded as an important cause of fluid depletion, leading to hemodynamic instability during surgery should replenishment is not promptly instituted. Lately, this traditional point of view has been progressively challenged, and a growing number of authors now propose a more restrictive approach to fluid management, although doubt remains as to the true hemodynamic influence of preoperative fasting. We designed an observational, analytic, prospective, longitudinal study in which 31 ASA 1 and ASA 2 volunteers underwent an echocardiographic examination both before and after a fasting period of at least 6hours (h). Data from both static and dynamic preload indices were obtained on both periods, and subsequently compared. Static preload indices exhibited a markedly variable behaviour with fasting. Dynamic indices, however, were far more consistent with one another, all pointing in the same direction, i.e., evidencing no statistically significant change with the fasting period. We also analysed the reliability of dynamic indices to respond to known, intentional preload changes. Aortic velocity time integral (VTI) variation with the passive leg raise manoeuvre was the only variable that proved to be sensitive enough to consistently signal the presence of preload variation. Fasting does not appear to cause a change in preload of conscious volunteers nor does it significantly alter their position in the Frank-Starling curve, even with longer fasting times than usually recommended. Transaortic VTI variation with the passive leg raise manoeuvre is the most robust dynamic index (of those studied) to evaluate preload responsiveness in spontaneously breathing patients. Copyright © 2016 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

  11. [Does fasting influence preload responsiveness in ASA 1 and 2 volunteers?

    PubMed

    Alves, Daniel Rodrigues; Ribeiras, Regina

    Preoperative fasting was long regarded as an important cause of fluid depletion, leading to hemodynamic instability during surgery should replenishment not be promptly instituted. Lately, this traditional point of view has been progressively challenged, and a growing number of authors now propose a more restrictive approach to fluid management, although doubt remains as to the true hemodynamic influence of preoperative fasting. We designed an observational, analytic, prospective, longitudinal study in which 31 ASA 1 and ASA 2 volunteers underwent an echocardiographic examination both before and after a fasting period of at least 6h. Data from both static and dynamic preload indices were obtained on both periods, and subsequently compared. Static preload indices exhibited a markedly variable behaviour with fasting. Dynamic indices, however, were far more consistent with one another, all pointing in the same direction, i.e., evidencing no statistically significant change with the fasting period. We also analysed the reliability of dynamic indices to respond to known, intentional preload changes. Aortic velocity time integral (VTI) variation with the passive leg raise manoeuvre was the only variable that proved to be sensitive enough to consistently signal the presence of preload variation. Fasting does not appear to cause a change in preload of conscious volunteers nor does it significantly alter their position in the Frank-Starling curve, even with longer fasting times than usually recommended. Transaortic VTI variation with the passive leg raise manoeuvre is the most robust dynamic index (of those studied) to evaluate preload responsiveness in spontaneously breathing patients. Copyright © 2016 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

  12. Blunted lipolytic response to fasting in abdominally obese women: evidence for involvement of hyposomatotropism.

    PubMed

    Buijs, Madelon M; Burggraaf, Jacobus; Wijbrandts, Carla; de Kam, Marieke L; Frölich, Marijke; Cohen, Adam F; Romijn, Johannes A; Sauerwein, Hans P; Meinders, A Edo; Pijl, Hanno

    2003-03-01

    Abdominal obesity is associated with a blunted lipolytic response to fasting that may contribute to the preservation of adipose tissue mass. To further explore the pathophysiology of blunted lipolysis during fasting in obesity, we simultaneously measured lipolysis and distinct neuroendocrine regulatory hormones in abdominally obese and normal-weight (NW) women. Eight abdominally obese [x +/- SD body mass index (BMI; in kg/m(2)): 32.1 +/- 2.6] and 6 NW (BMI: 22.7 +/- 1.5) women were studied during the last 8 h of a 20-h fast. The glycerol appearance rate and the serum and plasma concentrations of insulin, leptin, cortisol, and growth hormone were measured regularly. At 13 h of fasting, the mean (+/-SD) glycerol appearance rate corrected for fat mass was greater in NW women than in obese women (7.2 +/- 1.0 and 5.1 +/- 0.6 micro mol.kg(-1).min(-1), respectively; P = 0.001). After a 20-h fast, lipolysis increased to 8.9 +/- 1.5 mmol.kg(-1).min(-1) in NW women (23%), whereas it did not change significantly in obese women (-2%). Fasting decreased insulin concentrations by approximately 30% in both groups, but it did not induce significant changes in leptin concentrations. Mean cortisol concentrations and urinary catecholamine excretion were comparable in both groups. However, mean plasma growth hormone concentrations were higher in NW women than in obese women (1.81 +/- 0.98 compared with 0.74 +/- 0.52 mU/L; P = 0.046). The relative change in lipolysis tended to correlate with mean plasma growth hormone concentrations (r = 0.515, P = 0.059). Abdominal obesity-associated hyposomatotropism may be involved in the blunted increase in lipolysis during fasting.

  13. Metabolomics reveals differences in postprandial responses to breads and fasting metabolic characteristics associated with postprandial insulin demand in postmenopausal women.

    PubMed

    Moazzami, Ali A; Shrestha, Aahana; Morrison, David A; Poutanen, Kaisa; Mykkänen, Hannu

    2014-06-01

    Changes in serum metabolic profile after the intake of different food products (e.g., bread) can provide insight into their interaction with human metabolism. Postprandial metabolic responses were compared after the intake of refined wheat (RWB), whole-meal rye (WRB), and refined rye (RRB) breads. In addition, associations between the metabolic profile in fasting serum and the postprandial concentration of insulin in response to different breads were investigated. Nineteen postmenopausal women with normal fasting glucose and normal glucose tolerance participated in a randomized, controlled, crossover meal study. The test breads, RWB (control), RRB, and WRB, providing 50 g of available carbohydrate, were each served as a single meal. The postprandial metabolic profile was measured using nuclear magnetic resonance and targeted LC-mass spectrometry and was compared between different breads using ANOVA and multivariate models. Eight amino acids had a significant treatment effect (P < 0.01) and a significant treatment × time effect (P < 0.05). RWB produced higher postprandial concentrations of leucine (geometric mean: 224; 95% CI: 196, 257) and isoleucine (mean ± SD: 111 ± 31.5) compared with RRB (geometric mean: 165; 95% CI: 147, 186; mean ± SD: 84.2 ± 22.9) and WRB (geometric mean: 190; 95% CI: 174, 207; mean ± SD: 95.8 ± 17.3) at 60 min respectively (P < 0.001). In addition, 2 metabolic subgroups were identified using multivariate models based on the association between fasting metabolic profile and the postprandial concentration of insulin. Women with higher fasting concentrations of leucine and isoleucine and lower fasting concentrations of sphingomyelins and phosphatidylcholines had higher insulin responses despite similar glucose concentration after all kinds of bread (cross-validated ANOVA, P = 0.048). High blood concentration of branched-chain amino acids, i.e., leucine and isoleucine, has been associated with the increased risk of diabetes, which

  14. Building and Calibration of a FAST Model of the SWAY Prototype Floating Wind Turbine: Preprint

    SciTech Connect

    Koh, J. H.; Robertson, A.; Jonkman, J.; Driscoll, F.; Ng, E. Y. K.

    2013-09-01

    Present efforts to verify and validate aero-hydro-servo-elastic numerical simulation tools that predict the dynamic response of a floating offshore wind turbine are primarily limited to code-to-code comparisons or code-to-data comparisons using data from wind-wave basin tests. In partnership with SWAY AS, the National Renewable Energy Laboratory (NREL) installed scientific wind, wave, and motion measurement equipment on the 1/6.5th-scale prototype SWAY floating wind system to collect data to validate a FAST model of the SWAY design in an open-water condition. Nanyang Technological University (NTU), through a collaboration with NREL, assisted in this validation.

  15. Neurobiological model of stimulated dopamine neurotransmission to interpret fast-scan cyclic voltammetry data.

    PubMed

    Harun, Rashed; Grassi, Christine M; Munoz, Miranda J; Torres, Gonzalo E; Wagner, Amy K

    2015-03-02

    Fast-scan cyclic voltammetry (FSCV) is an electrochemical method that can assess real-time in vivo dopamine (DA) concentration changes to study the kinetics of DA neurotransmission. Electrical stimulation of dopaminergic (DAergic) pathways can elicit FSCV DA responses that largely reflect a balance of DA release and reuptake. Interpretation of these evoked DA responses requires a framework to discern the contribution of DA release and reuptake. The current, widely implemented interpretive framework for doing so is the Michaelis-Menten (M-M) model, which is grounded on two assumptions- (1) DA release rate is constant during stimulation, and (2) DA reuptake occurs through dopamine transporters (DAT) in a manner consistent with M-M enzyme kinetics. Though the M-M model can simulate evoked DA responses that rise convexly, response types that predominate in the ventral striatum, the M-M model cannot simulate dorsal striatal responses that rise concavely. Based on current neurotransmission principles and experimental FSCV data, we developed a novel, quantitative, neurobiological framework to interpret DA responses that assumes DA release decreases exponentially during stimulation and continues post-stimulation at a diminishing rate. Our model also incorporates dynamic M-M kinetics to describe DA reuptake as a process of decreasing reuptake efficiency. We demonstrate that this quantitative, neurobiological model is an extension of the traditional M-M model that can simulate heterogeneous regional DA responses following manipulation of stimulation duration, frequency, and DA pharmacology. The proposed model can advance our interpretive framework for future in vivo FSCV studies examining regional DA kinetics and their alteration by disease and DA pharmacology. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Unitary Response Regression Models

    ERIC Educational Resources Information Center

    Lipovetsky, S.

    2007-01-01

    The dependent variable in a regular linear regression is a numerical variable, and in a logistic regression it is a binary or categorical variable. In these models the dependent variable has varying values. However, there are problems yielding an identity output of a constant value which can also be modelled in a linear or logistic regression with…

  17. Unitary Response Regression Models

    ERIC Educational Resources Information Center

    Lipovetsky, S.

    2007-01-01

    The dependent variable in a regular linear regression is a numerical variable, and in a logistic regression it is a binary or categorical variable. In these models the dependent variable has varying values. However, there are problems yielding an identity output of a constant value which can also be modelled in a linear or logistic regression with…

  18. Development of a Fast Radiative Transfer Model for Simulating MODIS Solar Channels Under Cloudy Conditions

    NASA Astrophysics Data System (ADS)

    Niu, J.; Yang, P.; Huang, H.; Baum, B.; Hu, Y.

    2006-12-01

    A solar-band fast radiative transfer model (SFRTM-1, appropriate for application to a single-layered cloudy condition, has been developed for simulating outgoing bidirectional reflectance at the top of the atmosphere for MODIS solar channels. Cloud parameters such as the bi-directional reflectance function (BDRF), downward spherical reflectance, and cloud transmittance are pre-computed using DISORT model and tabulated into lookup tables for each MODIS channel. Cloud reflectance and transmittance parameters for a specific condition can be derived from a multi-dimensional interpolation technique. The total reflectance at the top of the atmosphere is evaluated using adding method with the gaseous atmospheric transmittances above and below the cloud layer, which are computed by a newly developed MODIS clear sky fast radiative transfer model (MODCSFRT). The MODCSFRT is based on the rigorous line-by-line computation and interpolation technique. The transmittances for individual atmospheric gaseous have been computed as a function of pressure, temperature, and column amount with high spectral resolution. After convolution with the MODIS instrument response function, channel transmittance functions have been tabulated into a four-dimensional lookup table. The practical transmittance at any layer of a user designed atmospheric model can be derived by a polynomial interpolation technique. In this paper, the SFRTM-1 and its related model MODCSFRT will be briefly described. The accuracy of the model and its preliminary application will be demonstrated.

  19. Biased Randomized Algorithm for Fast Model-Based Diagnosis

    NASA Technical Reports Server (NTRS)

    Williams, Colin; Vartan, Farrokh

    2005-01-01

    A biased randomized algorithm has been developed to enable the rapid computational solution of a propositional- satisfiability (SAT) problem equivalent to a diagnosis problem. The closest competing methods of automated diagnosis are described in the preceding article "Fast Algorithms for Model-Based Diagnosis" and "Two Methods of Efficient Solution of the Hitting-Set Problem" (NPO-30584), which appears elsewhere in this issue. It is necessary to recapitulate some of the information from the cited articles as a prerequisite to a description of the present method. As used here, "diagnosis" signifies, more precisely, a type of model-based diagnosis in which one explores any logical inconsistencies between the observed and expected behaviors of an engineering system. The function of each component and the interconnections among all the components of the engineering system are represented as a logical system. Hence, the expected behavior of the engineering system is represented as a set of logical consequences. Faulty components lead to inconsistency between the observed and expected behaviors of the system, represented by logical inconsistencies. Diagnosis - the task of finding the faulty components - reduces to finding the components, the abnormalities of which could explain all the logical inconsistencies. One seeks a minimal set of faulty components (denoted a minimal diagnosis), because the trivial solution, in which all components are deemed to be faulty, always explains all inconsistencies. In the methods of the cited articles, the minimal-diagnosis problem is treated as equivalent to a minimal-hitting-set problem, which is translated from a combinatorial to a computational problem by mapping it onto the Boolean-satisfiability and integer-programming problems. The integer-programming approach taken in one of the prior methods is complete (in the sense that it is guaranteed to find a solution if one exists) and slow and yields a lower bound on the size of the

  20. Design and evaluation of novel fast forming pilocarpine-loaded ocular hydrogels for sustained pharmacological response

    PubMed Central

    Anumolu, SivaNaga S.; Singh, Yashveer; Gao, Dayuan; Stein, Stanley; Sinko, Patrick J.

    2009-01-01

    Fast forming hydrogels prepared by crosslinking a poly(ethylene glycol) (PEG)-based copolymer containing multiple thiol (SH) groups were evaluated for the controlled ocular delivery of pilocarpine and subsequent pupillary constriction. Physical properties of the hydrogels were characterized using UV-Vis spectrophotometry, transmission electron microscopy (TEM), rheometry, and swelling kinetics. Pilocarpine loading efficiency and release properties were measured in simulated tear fluid. The hydrogel formulations exhibited high drug loading efficiency (~74%). Pilocarpine release was found to be biphasic with release half times of ~2 and 94 h, respectively, and 85–100% of the drug was released over 8-days. Pilocarpine-loaded (2% w/v) hydrogels were evaluated in a rabbit model and compared to a similar dose of drug in aqueous solution. The hydrogels were retained in the eye for the entire period of the study with no observed irritation. Pilocarpine-loaded hydrogels sustained pupillary constriction for 24 h after administration as compared to 3 h for the solution, an 8-fold increase in duration of action. A strong correlation between pilocarpine release and pupillary response was observed. In conclusion, the current studies demonstrate that in situ forming PEG hydrogels possess the viscoelastic, retention, and sustained delivery properties required for an efficient ocular drug delivery system. PMID:19341773

  1. Wavenumber-frequency Spectra of Pressure Fluctuations Measured via Fast Response Pressure Sensitive Paint

    NASA Technical Reports Server (NTRS)

    Panda, J.; Roozeboom, N. H.; Ross, J. C.

    2016-01-01

    The recent advancement in fast-response Pressure-Sensitive Paint (PSP) allows time-resolved measurements of unsteady pressure fluctuations from a dense grid of spatial points on a wind tunnel model. This capability allows for direct calculations of the wavenumber-frequency (k-?) spectrum of pressure fluctuations. Such data, useful for the vibro-acoustics analysis of aerospace vehicles, are difficult to obtain otherwise. For the present work, time histories of pressure fluctuations on a flat plate subjected to vortex shedding from a rectangular bluff-body were measured using PSP. The light intensity levels in the photographic images were then converted to instantaneous pressure histories by applying calibration constants, which were calculated from a few dynamic pressure sensors placed at selective points on the plate. Fourier transform of the time-histories from a large number of spatial points provided k-? spectra for pressure fluctuations. The data provides first glimpse into the possibility of creating detailed forcing functions for vibro-acoustics analysis of aerospace vehicles, albeit for a limited frequency range.

  2. Effect of fasting on serum lithium levels: an experimental study in animal models.

    PubMed

    Ahmed, Zia; Subhan, Fazal; Shah, Muhammad Tahir; Farooq, Saeed

    2014-01-01

    Muslims throughout the world observe dawn to dusk fast in the month of Holy Ramadan. This study aims to investigate the effect of fasting on serum lithium levels in an animal model under typical conditions of Ramadan. Animals were categorized into oral and intraperitoneal groups. Each group was divided into fasting and non fasting groups along with their controls having six animals each. Mean serum lithium levels of non-fasting and fasting rats were assessed. Mean serum lithium levels of oral non-fasting rats was 0.23±0.004 mequiv/L, (n=6) compared to oral fasting rats 0.20+0.002 mequiv/L, (n=6) mean difference=0.003. The mean difference between mean serum lithium level of intraperitoneal non fasting (0.246±0.015 mequiv/L, n = 6) and intraperitoneal fasting rats (0.206±0.020 mequiv/L, n = 6) was 0.02. These differences were statistically non significant (P>0.05). The mean serum lithium is not grossly affected by fasting in rats under 25ºC and fasting for almost 12 hours which is consistent with a previous clinical study. Lithium can be used by fasting bipolar patients but, will require careful supervision.

  3. Fast Prediction and Evaluation of Gravitational Waveforms Using Surrogate Models

    NASA Astrophysics Data System (ADS)

    Field, Scott E.; Galley, Chad R.; Hesthaven, Jan S.; Kaye, Jason; Tiglio, Manuel

    2014-07-01

    We propose a solution to the problem of quickly and accurately predicting gravitational waveforms within any given physical model. The method is relevant for both real-time applications and more traditional scenarios where the generation of waveforms using standard methods can be prohibitively expensive. Our approach is based on three offline steps resulting in an accurate reduced order model in both parameter and physical dimensions that can be used as a surrogate for the true or fiducial waveform family. First, a set of m parameter values is determined using a greedy algorithm from which a reduced basis representation is constructed. Second, these m parameters induce the selection of m time values for interpolating a waveform time series using an empirical interpolant that is built for the fiducial waveform family. Third, a fit in the parameter dimension is performed for the waveform's value at each of these m times. The cost of predicting L waveform time samples for a generic parameter choice is of order O(mL+mcfit) online operations, where cfit denotes the fitting function operation count and, typically, m ≪L. The result is a compact, computationally efficient, and accurate surrogate model that retains the original physics of the fiducial waveform family while also being fast to evaluate. We generate accurate surrogate models for effective-one-body waveforms of nonspinning binary black hole coalescences with durations as long as 105M, mass ratios from 1 to 10, and for multiple spherical harmonic modes. We find that these surrogates are more than 3 orders of magnitude faster to evaluate as compared to the cost of generating effective-one-body waveforms in standard ways. Surrogate model building for other waveform families and models follows the same steps and has the same low computational online scaling cost. For expensive numerical simulations of binary black hole coalescences, we thus anticipate extremely large speedups in generating new waveforms with a

  4. Insights into the role of hepatocyte PPARα activity in response to fasting.

    PubMed

    Régnier, Marion; Polizzi, Arnaud; Lippi, Yannick; Fouché, Edwin; Michel, Géraldine; Lukowicz, Céline; Smati, Sarra; Marrot, Alain; Lasserre, Frédéric; Naylies, Claire; Batut, Aurélie; Viars, Fanny; Bertrand-Michel, Justine; Postic, Catherine; Loiseau, Nicolas; Wahli, Walter; Guillou, Hervé; Montagner, Alexandra

    2017-07-31

    The liver plays a central role in the regulation of fatty acid metabolism. Hepatocytes are highly sensitive to nutrients and hormones that drive extensive transcriptional responses. Nuclear hormone receptors are key transcription factors involved in this process. Among these factors, PPARα is a critical regulator of hepatic lipid catabolism during fasting. This study aimed to analyse the wide array of hepatic PPARα-dependent transcriptional responses during fasting. We compared gene expression in male mice with a hepatocyte specific deletion of PPARα and their wild-type littermates in the fed (ad libitum) and 24-h fasted states. Liver samples were acquired, and transcriptome and lipidome analyses were performed. Our data extended and confirmed the critical role of hepatocyte PPARα as a central for regulator of gene expression during starvation. Interestingly, we identified novel PPARα-sensitive genes, including Cxcl-10, Rab30, and Krt23. We also found that liver phospholipid remodelling was a novel fasting-sensitive pathway regulated by PPARα. These results may contribute to investigations on transcriptional control in hepatic physiology and underscore the clinical relevance of drugs that target PPARα in liver pathologies, such as non-alcoholic fatty liver disease. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. FMFilter: A fast model based variant filtering tool.

    PubMed

    Akgün, Mete; Faruk Gerdan, Ö; Görmez, Zeliha; Demirci, Hüseyin

    2016-04-01

    The availability of whole exome and genome sequencing has completely changed the structure of genetic disease studies. It is now possible to solve the disease causing mechanisms within shorter time and budgets. For this reason, mining out the valuable information from the huge amount of data produced by next generation techniques becomes a challenging task. Current tools analyze sequencing data in various methods. However, there is still need for fast, easy to use and efficacious tools. Considering genetic disease studies, there is a lack of publicly available tools which support compound heterozygous and de novo models. Also, existing tools either require advanced IT expertise or are inefficient for handling large variant files. In this work, we provide FMFilter, an efficient sieving tool for next generation sequencing data produced by genetic disease studies. We develop a software which allows to choose the inheritance model (recessive, dominant, compound heterozygous and de novo), the affected and control individuals. The program provides a user friendly Graphical User Interface which eliminates the requirement of advanced computer techniques. It has various filtering options which enable to eliminate the majority of the false alarms. FMFilter requires negligible memory, therefore it can easily handle very large variant files like multiple whole genomes with ordinary computers. We demonstrate the variant reduction capability and effectiveness of the proposed tool with public and in-house data for different inheritance models. We also compare FMFilter with the existing filtering software. We conclude that FMFilter provides an effective and easy to use environment for analyzing next generation sequencing data from Mendelian diseases. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Evaluation of nonlinear structural dynamic responses using a fast-running spring-mass formulation

    NASA Astrophysics Data System (ADS)

    Benjamin, A. S.; Altman, B. S.; Gruda, J. D.

    In today's world, accurate finite-element simulations of large nonlinear systems may require meshes composed of hundreds of thousands of degrees of freedom. Even with today's fast computers and the promise of ever-faster ones in the future, central processing unit (CPU) expenditures for such problems could be measured in days. Many contemporary engineering problems, such as those found in risk assessment, probabilistic structural analysis, and structural design optimization, cannot tolerate the cost or turnaround time for such CPU-intensive analyses, because these applications require a large number of cases to be run with different inputs. For many risk assessment applications, analysts would prefer running times to be measurable in minutes. There is therefore a need for approximation methods which can solve such problems far more efficiently than the very detailed methods and yet maintain an acceptable degree of accuracy. For this purpose, we have been working on two methods of approximation: neural networks and spring-mass models. This paper presents our work and results to date for spring-mass modeling and analysis, since we are further along in this area than in the neural network formulation. It describes the physical and numerical models contained in a code we developed called STRESS, which stands for 'Spring-mass Transient Response Evaluation for structural Systems'. The paper also presents results for a demonstration problem, and compares these with results obtained for the same problem using PRONTO3D, a state-of-the-art finite element code which was also developed at Sandia.

  7. Evaluation of nonlinear structural dynamic responses using a fast-running spring-mass formulation

    SciTech Connect

    Benjamin, A.S.; Altman, B.S.; Gruda, J.D.

    1995-03-01

    In today`s world, accurate finite-element simulations of large nonlinear systems may require meshes composed of hundreds of thousands of degrees of freedom. Even with today`s fast computers and the promise of ever-faster ones in the future, central processing unit (CPU) expenditures for such problems could be measured in days. Many contemporary engineering problems, such as those found in risk assessment, probabilistic structural analysis, and structural design optimization, cannot tolerate the cost or turnaround time for such CPU-intensive analyses, because these applications require a large number of cases to be run with different inputs. For many risk assessment applications, analysts would prefer running times to be measurable in minutes. There is therefore a need for approximation methods which can solve such problems far more efficiently than the very detailed methods and yet maintain an acceptable degree of accuracy. For this purpose, we have been working on two methods of approximation: neural networks and spring-mass models. This paper presents our work and results to date for spring-mass modeling and analysis, since we are further along in this area than in the neural network formulation. It describes the physical and numerical models contained in a code we developed called STRESS, which stands for ``Spring-mass Transient Response Evaluation for structural Systems``. The paper also presents results for a demonstration problem, and compares these with results obtained for the same problem using PRONTO3D, a state-of-the-art finite element code which was also developed at Sandia.

  8. Response of six neutron survey meters in mixed fields of fast and thermal neutrons.

    PubMed

    Kim, S I; Kim, B H; Chang, I; Lee, J I; Kim, J L; Pradhan, A S

    2013-10-01

    Calibration neutron fields have been developed at KAERI (Korea Atomic Energy Research Institute) to study the responses of commonly used neutron survey meters in the presence of fast neutrons of energy around 10 MeV. The neutron fields were produced by using neutrons from the (241)Am-Be sources held in a graphite pile and a DT neutron generator. The spectral details and the ambient dose equivalent rates of the calibration fields were established, and the responses of six neutron survey meters were evaluated. Four single-moderator-based survey meters exhibited an under-responses ranging from ∼9 to 55 %. DINEUTRUN, commonly used in fields around nuclear reactors, exhibited an over-response by a factor of three in the thermal neutron field and an under-response of ∼85 % in the mixed fields. REM-500 (tissue-equivalent proportional counter) exhibited a response close to 1.0 in the fast neutron fields and an under-response of ∼50 % in the thermal neutron field.

  9. Models of coronal heating, turbulence and fast reconnection

    NASA Astrophysics Data System (ADS)

    Velli, M.; Pucci, F.; Rappazzo, F.; Tenerani, A.

    2015-04-01

    Coronal heating is at the origin of the EUV and X-ray emission and mass loss from the sun and many other stars. While different scenarios have been proposed to explain the heating of magnetically confined and open regions of the corona, they must all rely on the transfer, storage and dissipation of the abundant energy present in photospheric motions, which, coupled to magnetic fields, give rise to the complex phenomenology seen at the chromosphere and transition region (i.e. spicules, jets, 'tornadoes'). Here we discuss models and numerical simulations which rely on magnetic fields and electric currents both for energy transfer and for storage in the corona. We will revisit the sources and frequency spectrum of kinetic and electromagnetic energies, the role of boundary conditions, and the routes to small scales required for effective dissipation. Because reconnection in current sheets has been, and still is, one of the most important processes for coronal heating, we will also discuss recent aspects concerning the triggering of reconnection instabilities and the transition to fast reconnection.

  10. A “Cosmic Comb” Model of Fast Radio Bursts

    NASA Astrophysics Data System (ADS)

    Zhang, Bing

    2017-02-01

    Recent observations of fast radio bursts (FRBs) indicate a perplexing, inconsistent picture. We propose a unified scenario to interpret diverse FRBs observed. A regular pulsar, otherwise unnoticeable at a cosmological distance, may produce a bright FRB if its magnetosphere is suddenly “combed” by a nearby, strong plasma stream toward the anti-stream direction. If the Earth is to the night side of the stream, the combed magnetic sheath would sweep across the direction of Earth and make a detectable FRB. The stream could be an AGN flare, a GRB or supernova blastwave, a tidal disruption event, or even a stellar flare. Since it is the energy flux received by the pulsar rather than the luminosity of the stream origin that defines the properties of the FRB, this model predicts a variety of counterparts of FRBs, including a possible connection between FRB 150418 and an AGN flare, a possible connection between FRB 131104 and a weak GRB, a steady radio nebula associated with the repeating FRB 121102, and probably no bright counterparts for some FRBs.

  11. Memory sparing, fast scattering formalism for rigorous diffraction modeling

    NASA Astrophysics Data System (ADS)

    Iff, W.; Kämpfe, T.; Jourlin, Y.; Tishchenko, A. V.

    2017-07-01

    The basics and algorithmic steps of a novel scattering formalism suited for memory sparing and fast electromagnetic calculations are presented. The formalism, called ‘S-vector algorithm’ (by analogy with the known scattering-matrix algorithm), allows the calculation of the collective scattering spectra of individual layered micro-structured scattering objects. A rigorous method of linear complexity is applied to model the scattering at individual layers; here the generalized source method (GSM) resorting to Fourier harmonics as basis functions is used as one possible method of linear complexity. The concatenation of the individual scattering events can be achieved sequentially or in parallel, both having pros and cons. The present development will largely concentrate on a consecutive approach based on the multiple reflection series. The latter will be reformulated into an implicit formalism which will be associated with an iterative solver, resulting in improved convergence. The examples will first refer to 1D grating diffraction for the sake of simplicity and intelligibility, with a final 2D application example.

  12. Fast-mode elimination in stochastic metapopulation models

    NASA Astrophysics Data System (ADS)

    Constable, George W. A.; McKane, Alan J.

    2014-03-01

    We investigate the stochastic dynamics of entities which are confined to a set of islands, between which they migrate. They are assumed to be one of two types, and in addition to migration, they also reproduce and die. Birth and death events are later moderated by weak selection. Systems which fall into this class are common in biology and social science, occurring in ecology, population genetics, epidemiology, biochemistry, linguistics, opinion dynamics, and other areas. In all these cases the governing equations are intractable, consisting as they do of multidimensional Fokker-Planck equations or, equivalently, coupled nonlinear stochastic differential equations with multiplicative noise. We develop a methodology which exploits a separation in time scales between fast and slow variables to reduce these equations so that they resemble those for a single island, which are amenable to analysis. The technique is generally applicable, but we choose to discuss it in the context of population genetics, in part because of the extra features that appear due to selection. The idea behind the method is simple, its application is systematic, and the results are in very good agreement with simulations of the full model for a range of parameter values.

  13. Models of coronal heating, turbulence and fast reconnection.

    PubMed

    Velli, M; Pucci, F; Rappazzo, F; Tenerani, A

    2015-05-28

    Coronal heating is at the origin of the EUV and X-ray emission and mass loss from the sun and many other stars. While different scenarios have been proposed to explain the heating of magnetically confined and open regions of the corona, they must all rely on the transfer, storage and dissipation of the abundant energy present in photospheric motions, which, coupled to magnetic fields, give rise to the complex phenomenology seen at the chromosphere and transition region (i.e. spicules, jets, 'tornadoes'). Here we discuss models and numerical simulations which rely on magnetic fields and electric currents both for energy transfer and for storage in the corona. We will revisit the sources and frequency spectrum of kinetic and electromagnetic energies, the role of boundary conditions, and the routes to small scales required for effective dissipation. Because reconnection in current sheets has been, and still is, one of the most important processes for coronal heating, we will also discuss recent aspects concerning the triggering of reconnection instabilities and the transition to fast reconnection.

  14. Density Estimation Trees as fast non-parametric modelling tools

    NASA Astrophysics Data System (ADS)

    Anderlini, Lucio

    2016-10-01

    A Density Estimation Tree (DET) is a decision trees trained on a multivariate dataset to estimate the underlying probability density function. While not competitive with kernel techniques in terms of accuracy, DETs are incredibly fast, embarrassingly parallel and relatively small when stored to disk. These properties make DETs appealing in the resource- expensive horizon of the LHC data analysis. Possible applications may include selection optimization, fast simulation and fast detector calibration. In this contribution I describe the algorithm and its implementation made available to the HEP community as a RooFit object. A set of applications under discussion within the LHCb Collaboration are also briefly illustrated.

  15. A novel fast response and radiation-resistant scintillator detector for beam loss monitor

    NASA Astrophysics Data System (ADS)

    Ji, Y.; Tang, Z.; Li, C.; Li, X.; Shao, M.

    2017-07-01

    At high luminosity area, beam loss monitor with fast response and high radiation resistance is crucial for accelerator operation. In this article, we report the design and test results of a fast response and radiation-resistant scintillator detector as the beam loss monitor for high luminosity collider, especially at low energy region such as RFQ. The detector is consisted of a 2 cm× 2 cm× 0.5 cm LYSO crystal readout by a 6 mm × 6 mm Silicon photomultiplier. Test results from various radioactive sources show that the detector has good sensitivity to photons from tens of keV to several MeV with good linearity and energy resolution (23% for 60 keV γ-ray). For field test, two such detectors are installed outside of the vacuum chamber shell of an 800 MeV electron storage ring. The details of the test and results are introduced.

  16. On the Origin of Localized Fast Mantle Flow Velocity in Numerical Models of Subduction

    NASA Astrophysics Data System (ADS)

    Billen, M. I.; Jadamec, M.

    2011-12-01

    Recent regional (Jadamec and Billen, 2010) and global (Stadler et al., 2010; Alisic et al., 2010) models of subduction zones using non-linear rheology include results with localized regions of fast mantle velocities with magnitudes up to 90 cm/yr or roughly 20 times the speed of the subducting plate at the surface. These surprising results challenge the commonly held assumption that observed plate velocities are a good indication of mantle flow rates, and therefore the modeling has come under intense scrutiny to insure that these results are not an artifact of the model implementation. The previous models used realistic 3D geometries based on constraints from seismology (e.g., seismicity, tomography) and plate age to define slab temperature and viscosity, making it somewhat difficult to clearly demonstrate the physical cause of the localized fast flow velocities. Here we investigate the origin of fast mantle flow near subduction zones using 3D models with a simple planar slab geometry. Two suites of models are presented with either a slab that is free to sink into the mantle or a slab that is attached to a lithospheric layer. The rheology in the models is either Newtonian with a prescribed low viscosity mantle wedge region or non-Newtonian, in which low viscosity regions form in response to the instantaneous flow. The results show that there are two aspects of the models that lead to localized fast velocities. First, reduction in the mantle viscosity surrounding the sinking slab leads to faster overall flow rates induced by the sinking slab. Second, geometric affects limit the volume of the mantle surrounding the slab that can participate in the slab-induced return flow, and therefore a balance of stresses requires faster local flow rates within this smaller volume of material. Specifically, a strong dipping slab that is attached to the subducting lithosphere concentrates flow on the mantle-wedge side of the slab and in a narrow vertical portion of the

  17. A fast-responsive fluorescent probe for sulfite and its bioimaging.

    PubMed

    Wang, Jiaoliang; Long, Liping; Xiao, Xiaoming

    2016-05-01

    A turn-on fluorescent probe Coumarin-SO2 based on a nucleophilic addition reaction was developed for the rapid detection of SO3(2-) in aqueous media. The probe Coumarin-SO2 displays excellent water solubility, fast response, highly sensitivity and highly selectivity over other biological related species. More importantly, living cell imaging experiments indicate the feasibility of using the probe for the detection of SO3(2-) in biological systems.

  18. The thermoluminescence response of doped SiO2 optical fibres subjected to fast neutrons.

    PubMed

    Hashim, S; Bradley, D A; Saripan, M I; Ramli, A T; Wagiran, H

    2010-01-01

    This paper describes a preliminary study of the thermoluminescence (TL) response of doped SiO(2) optical fibres subjected to (241)AmBe neutron irradiation. The TL materials, which comprise Al- and Ge-doped silica fibres, were exposed in close contact with the (241)AmBe source to obtain fast neutron interactions through use of measurements obtained with and without a Cd filter (the filter being made to entirely enclose the fibres). The neutron irradiations were performed for exposure times of 1-, 2-, 3-, 5- and 7-days in a neutron tank filled with water. In this study, use was also made of the Monte Carlo N-particle (MCNP) code version 5 (V5) to simulate the neutron irradiations experiment. It was found that the commercially available Ge-doped and Al-doped optical fibres show a linear dose response subjected to fast neutrons from (241)AmBe source up to seven days of irradiations. The simulation performed using MCNP5 also exhibits a similar pattern, albeit differing in sensitivity. The TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre, the total absorption cross section for Ge in both the fast and thermal neutrons region being some ten times greater than that of Al.

  19. Fast response measurements of the dispersion of nanoparticles in a vehicle wake and a street canyon

    NASA Astrophysics Data System (ADS)

    Kumar, Prashant; Robins, Alan; Britter, Rex

    2009-12-01

    The distributions of nanoparticles (below 300 nm in diameter) change rapidly after emission from the tail pipe of a moving vehicle due to the influence of transformation processes. Information on this time scale is important for modelling of nanoparticle dispersion but is unknown because the sampling frequencies of available instruments are unable to capture these rapid processes. In this study, a fast response differential mobility spectrometer (Cambustion Instruments DMS500), originally designed to measure particle number distributions (PNDs) and concentrations in engine exhaust emissions, was deployed to measure particles in the 5-1000 nm size range at a sampling frequency of 10 Hz. This article presents results of two separate studies; one, measurements along the roadside in a Cambridge (UK) street canyon and, two, measurements at a fixed position (20 cm above road level), centrally, in the wake of a single moving diesel-engined car. The aims of the first measurements were to test the suitability and recommend optimum operating conditions of the DMS500 for ambient measurements. The aim of the second study was to investigate the time scale over which competing influences of dilution and transformation processes (nucleation, condensation and coagulation) affect the PNDs in the wake of a moving car. Results suggested that the effect of transformation processes was nearly complete within about 1 s after emission due to rapid dilution in the vehicle wake. Furthermore, roadside measurements in a street canyon showed that the time for traffic emissions to reach the roadside in calm wind conditions was about 45 ± 6 s. These observations suggest the hypothesis that the effects of transformation processes are generally complete by the time particles are observed at roadside and the total particle numbers can then be assumed as conserved. A corollary of this hypothesis is that complex transformation processes can be ignored when modelling the behaviour of nanoparticles

  20. Fast Flexible Modeling of RNA Structure Using Internal Coordinates

    PubMed Central

    Flores, Samuel Coulbourn; Sherman, Michael A.; Bruns, Christopher M.; Eastman, Peter; Altman, Russ Biagio

    2015-01-01

    Modeling the structure and dynamics of large macromolecules remains a critical challenge. Molecular dynamics (MD) simulations are expensive because they model every atom independently, and are difficult to combine with experimentally derived knowledge. Assembly of molecules using fragments from libraries relies on the database of known structures and thus may not work for novel motifs. Coarse-grained modeling methods have yielded good results on large molecules but can suffer from difficulties in creating more detailed full atomic realizations. There is therefore a need for molecular modeling algorithms that remain chemically accurate and economical for large molecules, do not rely on fragment libraries, and can incorporate experimental information. RNABuilder works in the internal coordinate space of dihedral angles and thus has time requirements proportional to the number of moving parts rather than the number of atoms. It provides accurate physics-based response to applied forces, but also allows user-specified forces for incorporating experimental information. A particular strength of RNABuilder is that all Leontis-Westhof basepairs can be specified as primitives by the user to be satisfied during model construction. We apply RNABuilder to predict the structure of an RNA molecule with 160 bases from its secondary structure, as well as experimental information. Our model matches the known structure to 10.2 Angstroms RMSD and has low computational expense. PMID:21778523

  1. Photoconductive detectors with fast temporal response for laser produced plasma experiments.

    PubMed

    May, M J; Halvorson, C; Perry, T; Weber, F; Young, P; Silbernagel, C

    2008-10-01

    Processes during laser plasma experiments typically have time scales that are less than 100 ps. The measurement of these processes requires x-ray detectors with fast temporal resolution. We have measured the temporal responses and linearity of several different x-ray sensitive photoconductive detectors (PCDs). The active elements of the detectors investigated include both diamond (natural and synthetic) and GaAs crystals. The typical time responses of the GaAs PCDs are approximately 60 ps, respectively. Some characterizations using x-ray radiation from a synchrotron radiation source are presented.

  2. Photoconductive Detectors with Fast Temporal Response for Laser Produced Plasma Experiments

    SciTech Connect

    M. J. May, C. Halvorson, T. Perry, F. Weber, P. Young, C. Silbernagel

    2008-06-01

    Processes during laser plasma experiments typically have time scales that are less than 100 ps. The measurement of these processes requires X-ray detectors with fast temporal resolution. We have measured the temporal responses and linearity of several different Xray sensitive Photoconductive Detectors (PCDs). The active elements of the detectors investigated include both diamond (natural and synthetic) and GaAs crystals. The typical time responses of the GaAs PCDs are approximately 60 ps, respectively. Some characterizations using X-ray light from a synchrotron light source are presented.

  3. Photoconductive Detectors with Fast Temporal Response for Laser Produced Plasma Experiments.

    SciTech Connect

    May, M; Halvorson, C; Perry, T; Weber, F; Young, P; Silbernagel, C

    2008-05-06

    Processes during laser plasma experiments typically have time scales that are less than 100 ps. The measurement of these processes requires X-ray detectors with fast temporal resolution. We have measured the temporal responses and linearity of several different X-ray sensitive Photoconductive Detectors (PCDs). The active elements of the detectors investigated include both diamond (natural and synthetic) and GaAs crystals. The typical time responses of the GaAs PCDs are approximately 60 ps, respectively. Some characterizations using X-ray light from a synchrotron light source are presented.

  4. Data Mining Meets Performance Evaluation: Fast Algorithms for Modeling Bursty Traffic

    DTIC Science & Technology

    2001-04-01

    Data Mining Meets Performance Evaluation: Fast Algorithms for Modeling Bursty Traffic Mengzhi Wang Tara Madhyastha Ngai Hang Chan Spiros...2001 4. TITLE AND SUBTITLE Data Mining Meets Performance Evaluation: Fast Algorithms for Modeling Bursty Traffic 5a. CONTRACT NUMBER 5b. GRANT

  5. Fast-SNP: a fast matrix pre-processing algorithm for efficient loopless flux optimization of metabolic models

    PubMed Central

    Saa, Pedro A.; Nielsen, Lars K.

    2016-01-01

    Motivation: Computation of steady-state flux solutions in large metabolic models is routinely performed using flux balance analysis based on a simple LP (Linear Programming) formulation. A minimal requirement for thermodynamic feasibility of the flux solution is the absence of internal loops, which are enforced using ‘loopless constraints’. The resulting loopless flux problem is a substantially harder MILP (Mixed Integer Linear Programming) problem, which is computationally expensive for large metabolic models. Results: We developed a pre-processing algorithm that significantly reduces the size of the original loopless problem into an easier and equivalent MILP problem. The pre-processing step employs a fast matrix sparsification algorithm—Fast- sparse null-space pursuit (SNP)—inspired by recent results on SNP. By finding a reduced feasible ‘loop-law’ matrix subject to known directionalities, Fast-SNP considerably improves the computational efficiency in several metabolic models running different loopless optimization problems. Furthermore, analysis of the topology encoded in the reduced loop matrix enabled identification of key directional constraints for the potential permanent elimination of infeasible loops in the underlying model. Overall, Fast-SNP is an effective and simple algorithm for efficient formulation of loop-law constraints, making loopless flux optimization feasible and numerically tractable at large scale. Availability and Implementation: Source code for MATLAB including examples is freely available for download at http://www.aibn.uq.edu.au/cssb-resources under Software. Optimization uses Gurobi, CPLEX or GLPK (the latter is included with the algorithm). Contact: lars.nielsen@uq.edu.au Supplementary information: Supplementary data are available at Bioinformatics online. PMID:27559155

  6. Fast-SNP: a fast matrix pre-processing algorithm for efficient loopless flux optimization of metabolic models.

    PubMed

    Saa, Pedro A; Nielsen, Lars K

    2016-12-15

    Computation of steady-state flux solutions in large metabolic models is routinely performed using flux balance analysis based on a simple LP (Linear Programming) formulation. A minimal requirement for thermodynamic feasibility of the flux solution is the absence of internal loops, which are enforced using 'loopless constraints'. The resulting loopless flux problem is a substantially harder MILP (Mixed Integer Linear Programming) problem, which is computationally expensive for large metabolic models. We developed a pre-processing algorithm that significantly reduces the size of the original loopless problem into an easier and equivalent MILP problem. The pre-processing step employs a fast matrix sparsification algorithm-Fast- sparse null-space pursuit (SNP)-inspired by recent results on SNP. By finding a reduced feasible 'loop-law' matrix subject to known directionalities, Fast-SNP considerably improves the computational efficiency in several metabolic models running different loopless optimization problems. Furthermore, analysis of the topology encoded in the reduced loop matrix enabled identification of key directional constraints for the potential permanent elimination of infeasible loops in the underlying model. Overall, Fast-SNP is an effective and simple algorithm for efficient formulation of loop-law constraints, making loopless flux optimization feasible and numerically tractable at large scale. Source code for MATLAB including examples is freely available for download at http://www.aibn.uq.edu.au/cssb-resources under Software. Optimization uses Gurobi, CPLEX or GLPK (the latter is included with the algorithm). lars.nielsen@uq.edu.auSupplementary information: Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press.

  7. Model refinement using transient response

    SciTech Connect

    Dohrmann, C.R.; Carne, T.G.

    1997-12-01

    A method is presented for estimating uncertain or unknown parameters in a mathematical model using measurements of transient response. The method is based on a least squares formulation in which the differences between the model and test-based responses are minimized. An application of the method is presented for a nonlinear structural dynamic system. The method is also applied to a model of the Department of Energy armored tractor trailer. For the subject problem, the transient response was generated by driving the vehicle over a bump of prescribed shape and size. Results from the analysis and inspection of the test data revealed that a linear model of the vehicle`s suspension is not adequate to accurately predict the response caused by the bump.

  8. A new fast reconnection model in a collisionless regime

    SciTech Connect

    Tsiklauri, David

    2008-11-15

    Based on the first principles [i.e., (i) by balancing the magnetic field advection with the term containing electron pressure tensor nongyrotropic components in the generalized Ohm's law; (ii) using the conservation of mass; and (iii) assuming that the weak magnetic field region width, where electron meandering motion supports electron pressure tensor off-diagonal (nongyrotropic) components, is of the order of electron Larmor radius] a simple model of magnetic reconnection in a collisionless regime is formulated. The model is general, resembling its collisional Sweet-Parker analog in that it is not specific to any initial configuration, e.g., Harris-type tearing unstable current sheet, X-point collapse or otherwise. In addition to its importance from the fundamental point of view, the collisionless reconnection model offers a much faster reconnection rate [M{sub c{sup '}}{sub less}=(c/{omega}{sub pe}){sup 2}/(r{sub L,e}L)] than Sweet-Parker's classical one (M{sub sp}=S{sup -1/2}). The width of the diffusion region (current sheet) in the collisionless regime is found to be {delta}{sub c{sup '}}{sub less}=(c/{omega}{sub pe}){sup 2}/r{sub L,e}, which is independent of the global reconnection scale L and is only prescribed by microphysics (electron inertial length, c/{omega}{sub pe}, and electron Larmor radius, r{sub L,e}). Amongst other issues, the fastness of the reconnection rate alleviates, e.g., the problem of interpretation of solar flares by means of reconnection, as for the typical solar coronal parameters the obtained collisionless reconnection time can be a few minutes, as opposed to Sweet-Parker's equivalent value of less than a day. The new theoretical reconnection rate is compared to the Magnetic Reconnection Experiment device experimental data by Yamada et al. [Phys. Plasmas 13, 052119 (2006)] and Ji et al. [Geophys. Res. Lett. 35, 13106 (2008)], and a good agreement is obtained.

  9. Duration of fasting but not diurnal variation affects the response to glucagon in healthy cats.

    PubMed

    Gilor, C; Glock, R; Gilor, S

    2015-10-01

    The role of glucagon disturbances in diabetes is increasingly recognized. Glucagon stimulation tests (GSTs) have been described in cats previously, but information is lacking on the response of cats to glucagon under specific conditions. The aim of this study was to assess a novel protocol for GST using human-recombinant glucagon and the effect of diurnal variation and duration of fasting using this protocol in healthy cats. All intravenous doses resulted in occasional vomiting and nausea, and eventually, a 20-μg/kg intramuscular dose was chosen. Five healthy cats were then used in a repeated-measures study. Cats were free-fed regularly at 7:30 AM and 5:30 PM for 30 min. In each cat, GST was performed at 7 PM after a 25-h fast (PM25), at 9 AM after a 25-h fast (AM25), and at 9 AM after a 15-h fast (AM15). Glucose and insulin concentrations were measured at -15, 0, 15, 25, 35, 45, and 60 min after stimulation. Baseline and peak concentrations were compared using the Friedman test. Baseline glucose and insulin did not differ significantly between treatment groups. Peak glucose concentrations occurred at 15 min and were significantly higher (P = 0.0085) at AM15 (mean ± standard deviation = 185.2 ± 43.0 mg/dL) vs AM25 (144.4 ± 10.5 mg/dL) and PM25 (128.0 ± 18.4 mg/dL). Similarly, peak insulin concentrations occurred at 15 min and were significantly higher (P = 0.04) at AM15 (1,911 ± 1,153 pg/mL) vs AM25 (739 ± 52 pg/mL) or PM25 (549 ± 366 pg/mL). In conclusion, prolonged fasting significantly blunted the glycemic response to glucagon compared with shorter fasting, but diurnal variation had no significant effect on glucose or insulin responses.

  10. Towards a Fast Dynamic Model of the Human Circulatory System

    NASA Astrophysics Data System (ADS)

    Kaplan, Carolyn; Green, Melissa; Boris, Jay; Oran, Elaine

    2011-11-01

    We describe a model for systems-level transport in the human circulatory system that is based on a set of equations for a one-dimensional unsteady elastic pipe flow circuit. The system is collapsed from three spatial dimensions and time to one spatial dimension and time by assuming axisymmetric vessel geometry and a parabolic velocity profile across the cylindrical vessels. To drive the fluid, the contractions of a beating heart are modeled as periodic area changes of the elastic vessels. Two different models are compared, both including and neglecting fluid acceleration. Time-resolved distributions of pressure, velocity and area compare reasonably well with reference data. Increasing the rigidity of the vasculature is found to increase peak arterial pressures on the order of ten percent, and including a distributed vascular contraction to model distributed skeletal muscle contractions monotonically increases time-averaged blood flow in the veins, consistent with human physiological response. The circulatory system model presented here simulates the circulatory system on the order of one hundred times faster than real-time; that is, we can compute thousands of heartbeats per minute of CPU time.

  11. 'Bubble chamber model' of fast atom bombardment induced processes.

    PubMed

    Kosevich, Marina V; Shelkovsky, Vadim S; Boryak, Oleg A; Orlov, Vadim V

    2003-01-01

    A hypothesis concerning FAB mechanisms, referred to as a 'bubble chamber FAB model', is proposed. This model can provide an answer to the long-standing question as to how fragile biomolecules and weakly bound clusters can survive under high-energy particle impact on liquids. The basis of this model is a simple estimation of saturated vapour pressure over the surface of liquids, which shows that all liquids ever tested by fast atom bombardment (FAB) and liquid secondary ion mass spectrometry (SIMS) were in the superheated state under the experimental conditions applied. The result of the interaction of the energetic particles with superheated liquids is known to be qualitatively different from that with equilibrium liquids. It consists of initiation of local boiling, i.e., in formation of vapour bubbles along the track of the energetic particle. This phenomenon has been extensively studied in the framework of nuclear physics and provides the basis for construction of the well-known bubble chamber detectors. The possibility of occurrence of similar processes under FAB of superheated liquids substantiates a conceptual model of emission of secondary ions suggested by Vestal in 1983, which assumes formation of bubbles beneath the liquid surface, followed by their bursting accompanied by release of microdroplets and clusters as a necessary intermediate step for the creation of molecular ions. The main distinctive feature of the bubble chamber FAB model, proposed here, is that the bubbles are formed not in the space and time-restricted impact-excited zone, but in the nearby liquid as a 'normal' boiling event, which implies that the temperature both within the bubble and in the droplets emerging on its burst is practically the same as that of the bulk liquid sample. This concept can resolve the paradox of survival of intact biomolecules under FAB, since the part of the sample participating in the liquid-gas transition via the bubble mechanism has an ambient temperature

  12. Fast 3-D large-scale gravity and magnetic modeling using unstructured grids and an adaptive multilevel fast multipole method

    NASA Astrophysics Data System (ADS)

    Ren, Zhengyong; Tang, Jingtian; Kalscheuer, Thomas; Maurer, Hansruedi

    2017-01-01

    A novel fast and accurate algorithm is developed for large-scale 3-D gravity and magnetic modeling problems. An unstructured grid discretization is used to approximate sources with arbitrary mass and magnetization distributions. A novel adaptive multilevel fast multipole (AMFM) method is developed to reduce the modeling time. An observation octree is constructed on a set of arbitrarily distributed observation sites, while a source octree is constructed on a source tetrahedral grid. A novel characteristic is the independence between the observation octree and the source octree, which simplifies the implementation of different survey configurations such as airborne and ground surveys. Two synthetic models, a cubic model and a half-space model with mountain-valley topography, are tested. As compared to analytical solutions of gravity and magnetic signals, excellent agreements of the solutions verify the accuracy of our AMFM algorithm. Finally, our AMFM method is used to calculate the terrain effect on an airborne gravity data set for a realistic topography model represented by a triangular surface retrieved from a digital elevation model. Using 16 threads, more than 5800 billion interactions between 1,002,001 observation points and 5,839,830 tetrahedral elements are computed in 453.6 s. A traditional first-order Gaussian quadrature approach requires 3.77 days. Hence, our new AMFM algorithm not only can quickly compute the gravity and magnetic signals for complicated problems but also can substantially accelerate the solution of 3-D inversion problems.

  13. Calibration and Validation of a Spar-Type Floating Offshore Wind Turbine Model using the FAST Dynamic Simulation Tool: Preprint

    SciTech Connect

    Browning, J. R.; Jonkman, J.; Robertson, A.; Goupee, A. J.

    2012-11-01

    In 2007, the FAST wind turbine simulation tool, developed and maintained by the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL), was expanded to include capabilities that are suitable for modeling floating offshore wind turbines. In an effort to validate FAST and other offshore wind energy modeling tools, DOE funded the DeepCwind project that tested three prototype floating wind turbines at 1/50th scale in a wave basin, including a semisubmersible, a tension-leg platform, and a spar buoy. This paper describes the use of the results of the spar wave basin tests to calibrate and validate the FAST offshore floating simulation tool, and presents some initial results of simulated dynamic responses of the spar to several combinations of wind and sea states.

  14. Fast Hemodynamic Responses in the Visual Cortex of the Awake Mouse

    PubMed Central

    Pisauro, M. Andrea; Dhruv, Neel T.; Benucci, Andrea

    2013-01-01

    Hemodynamic responses in mice and other species are typically measured under anesthesia. However, anesthesia could influence their relationship to neural activity. To investigate this relationship, we used optical imaging in mouse primary visual cortex (V1). Hemodynamic responses yielded clear maps of retinotopy in both anesthetized and awake mice. However, during wakefulness, responses were four times larger and twice as fast. These differences held whether we induced anesthesia with urethane or isoflurane and whether awake mice were stationary or running on a treadmill. With electrode recordings, we established that the effects of wakefulness reflect changes in neurovascular coupling, not in neural activity. By activating V1 directly via optogenetics, we replicated the effects of wakefulness in terms of timing but not of amplitude. We conclude that neurovascular coupling depends critically on anesthesia and wakefulness: during wakefulness, neural activity is followed by much stronger and quicker hemodynamic responses. PMID:24227743

  15. Response surface methodology to optimize novel fast disintegrating tablets using β cyclodextrin as diluent.

    PubMed

    Late, Sameer G; Banga, Ajay K

    2010-12-01

    The objective of this work was to apply response surface approach to investigate main and interaction effects of formulation parameters in optimizing novel fast disintegrating tablet formulation using β cyclodextrin as a diluent. The variables studied were diluent (β cyclodextrin, X (1)), superdisintegrant (Croscarmellose sodium, X (2)), and direct compression aid (Spray dried lactose, X (3)). Tablets were prepared by direct compression method on B2 rotary tablet press using flat plain-face punches and characterized for weight variation, thickness, disintegration time (Y (1)), and hardness (Y (2)). Disintegration time was strongly affected by quadratic terms of β cyclodextrin, croscarmellose sodium, and spray-dried lactose. The positive value of regression coefficient for β cyclodextrin suggested that hardness increased with increased amount of β cyclodextrin. In general, disintegration of tablets has been reported to slow down with increase in hardness. However in the present study, higher concentration of β cyclodextrin was found to improve tablet hardness without increasing the disintegration time. Thus, β cyclodextrin is proposed as a suitable diluent to achieve fast disintegrating tablets with sufficient hardness. Good correlation between the predicted values and experimental data of the optimized formulation validated prognostic ability of response surface methodology in optimizing fast disintegrating tablets using β cyclodextrin as a diluent.

  16. Response of a Si-diode-based device to fast neutrons.

    PubMed

    Spurný, Frantisek

    2005-02-01

    Semiconductor devices based on a Si-detector are frequently used for charged particle's detection; one application being in the investigation of cosmic radiation fields. From the spectra of energy deposition events in such devices, the total energy deposited by the radiation in silicon can be derived. This contribution presents the results of studies concerning the response of this type of detector to fast neutrons. First, the spectrum of energy deposition was established in fast neutron radiation fields with average energies from 0.5 to 50 MeV. It was found that these spectra vary significantly with the neutron energy. The comparison with the spectra registered in photon beams permitted an estimation of the part of energy deposited that could be attributed to neutrons. It was found that this part increases rapidly with neutron energy. The possibilities to use this type of detector for neutron detection and dosimetry for radiation protection are analysed and discussed.

  17. Frequency response function-based model updating using Kriging model

    NASA Astrophysics Data System (ADS)

    Wang, J. T.; Wang, C. J.; Zhao, J. P.

    2017-03-01

    An acceleration frequency response function (FRF) based model updating method is presented in this paper, which introduces Kriging model as metamodel into the optimization process instead of iterating the finite element analysis directly. The Kriging model is taken as a fast running model that can reduce solving time and facilitate the application of intelligent algorithms in model updating. The training samples for Kriging model are generated by the design of experiment (DOE), whose response corresponds to the difference between experimental acceleration FRFs and its counterpart of finite element model (FEM) at selected frequency points. The boundary condition is taken into account, and a two-step DOE method is proposed for reducing the number of training samples. The first step is to select the design variables from the boundary condition, and the selected variables will be passed to the second step for generating the training samples. The optimization results of the design variables are taken as the updated values of the design variables to calibrate the FEM, and then the analytical FRFs tend to coincide with the experimental FRFs. The proposed method is performed successfully on a composite structure of honeycomb sandwich beam, after model updating, the analytical acceleration FRFs have a significant improvement to match the experimental data especially when the damping ratios are adjusted.

  18. Calibration and validation of a spar-type floating offshore wind turbine model using the FAST dynamic simulation tool

    DOE PAGES

    Browning, J. R.; Jonkman, J.; Robertson, A.; ...

    2014-12-16

    In this study, high-quality computer simulations are required when designing floating wind turbines because of the complex dynamic responses that are inherent with a high number of degrees of freedom and variable metocean conditions. In 2007, the FAST wind turbine simulation tool, developed and maintained by the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL), was expanded to include capabilities that are suitable for modeling floating offshore wind turbines. In an effort to validate FAST and other offshore wind energy modeling tools, DOE funded the DeepCwind project that tested three prototype floating wind turbines at 1/50th scale inmore » a wave basin, including a semisubmersible, a tension-leg platform, and a spar buoy. This paper describes the use of the results of the spar wave basin tests to calibrate and validate the FAST offshore floating simulation tool, and presents some initial results of simulated dynamic responses of the spar to several combinations of wind and sea states. Wave basin tests with the spar attached to a scale model of the NREL 5-megawatt reference wind turbine were performed at the Maritime Research Institute Netherlands under the DeepCwind project. This project included free-decay tests, tests with steady or turbulent wind and still water (both periodic and irregular waves with no wind), and combined wind/wave tests. The resulting data from the 1/50th model was scaled using Froude scaling to full size and used to calibrate and validate a full-size simulated model in FAST. Results of the model calibration and validation include successes, subtleties, and limitations of both wave basin testing and FAST modeling capabilities.« less

  19. Calibration and validation of a spar-type floating offshore wind turbine model using the FAST dynamic simulation tool

    NASA Astrophysics Data System (ADS)

    Browning, J. R.; Jonkman, J.; Robertson, A.; Goupee, A. J.

    2014-12-01

    High-quality computer simulations are required when designing floating wind turbines because of the complex dynamic responses that are inherent with a high number of degrees of freedom and variable metocean conditions. In 2007, the FAST wind turbine simulation tool, developed and maintained by the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL), was expanded to include capabilities that are suitable for modeling floating offshore wind turbines. In an effort to validate FAST and other offshore wind energy modeling tools, DOE funded the DeepCwind project that tested three prototype floating wind turbines at 1/50th scale in a wave basin, including a semisubmersible, a tension-leg platform, and a spar buoy. This paper describes the use of the results of the spar wave basin tests to calibrate and validate the FAST offshore floating simulation tool, and presents some initial results of simulated dynamic responses of the spar to several combinations of wind and sea states. Wave basin tests with the spar attached to a scale model of the NREL 5-megawatt reference wind turbine were performed at the Maritime Research Institute Netherlands under the DeepCwind project. This project included free-decay tests, tests with steady or turbulent wind and still water (both periodic and irregular waves with no wind), and combined wind/wave tests. The resulting data from the 1/50th model was scaled using Froude scaling to full size and used to calibrate and validate a full-size simulated model in FAST. Results of the model calibration and validation include successes, subtleties, and limitations of both wave basin testing and FAST modeling capabilities.

  20. Calibration and validation of a spar-type floating offshore wind turbine model using the FAST dynamic simulation tool

    SciTech Connect

    Browning, J. R.; Jonkman, J.; Robertson, A.; Goupee, A. J.

    2014-12-16

    In this study, high-quality computer simulations are required when designing floating wind turbines because of the complex dynamic responses that are inherent with a high number of degrees of freedom and variable metocean conditions. In 2007, the FAST wind turbine simulation tool, developed and maintained by the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL), was expanded to include capabilities that are suitable for modeling floating offshore wind turbines. In an effort to validate FAST and other offshore wind energy modeling tools, DOE funded the DeepCwind project that tested three prototype floating wind turbines at 1/50th scale in a wave basin, including a semisubmersible, a tension-leg platform, and a spar buoy. This paper describes the use of the results of the spar wave basin tests to calibrate and validate the FAST offshore floating simulation tool, and presents some initial results of simulated dynamic responses of the spar to several combinations of wind and sea states. Wave basin tests with the spar attached to a scale model of the NREL 5-megawatt reference wind turbine were performed at the Maritime Research Institute Netherlands under the DeepCwind project. This project included free-decay tests, tests with steady or turbulent wind and still water (both periodic and irregular waves with no wind), and combined wind/wave tests. The resulting data from the 1/50th model was scaled using Froude scaling to full size and used to calibrate and validate a full-size simulated model in FAST. Results of the model calibration and validation include successes, subtleties, and limitations of both wave basin testing and FAST modeling capabilities.

  1. G6PC2 Modulates Fasting Blood Glucose In Male Mice in Response to Stress.

    PubMed

    Boortz, Kayla A; Syring, Kristen E; Dai, Chunhua; Pound, Lynley D; Oeser, James K; Jacobson, David A; Wang, Jen-Chywan; McGuinness, Owen P; Powers, Alvin C; O'Brien, Richard M

    2016-08-01

    The glucose-6-phosphatase catalytic 2 (G6PC2) gene is expressed specifically in pancreatic islet beta cells. Genome-wide association studies have shown that single nucleotide polymorphisms in the G6PC2 gene are associated with variations in fasting blood glucose (FBG) but not fasting plasma insulin. Molecular analyses examining the functional effects of these single nucleotide polymorphisms demonstrate that elevated G6PC2 expression is associated with elevated FBG. Studies in mice complement these genome-wide association data and show that deletion of the G6pc2 gene lowers FBG without affecting fasting plasma insulin. This suggests that, together with glucokinase, G6PC2 forms a substrate cycle that determines the glucose sensitivity of insulin secretion. Because genome-wide association studies and mouse studies demonstrate that elevated G6PC2 expression raises FBG and because chronically elevated FBG is detrimental to human health, increasing the risk of type 2 diabetes, it is unclear why G6PC2 evolved. We show here that the synthetic glucocorticoid dexamethasone strongly induces human G6PC2 promoter activity and endogenous G6PC2 expression in isolated human islets. Acute treatment with dexamethasone selectively induces endogenous G6pc2 expression in 129SvEv but not C57BL/6J mouse pancreas and isolated islets. The difference is due to a single nucleotide polymorphism in the C57BL/6J G6pc2 promoter that abolishes glucocorticoid receptor binding. In 6-hour fasted, nonstressed 129SvEv mice, deletion of G6pc2 lowers FBG. In response to the stress of repeated physical restraint, which is associated with elevated plasma glucocorticoid levels, G6pc2 gene expression is induced and the difference in FBG between wild-type and knockout mice is enhanced. These data suggest that G6PC2 may have evolved to modulate FBG in response to stress.

  2. Cultured slow vs. fast skeletal muscle cells differ in physiology and responsiveness to stimulation.

    PubMed

    Huang, Yen-Chih; Dennis, Robert G; Baar, Keith

    2006-07-01

    In vitro studies have used protein markers to distinguish between myogenic cells isolated from fast and slow skeletal muscles. The protein markers provide some support for the hypothesis that satellite cells from fast and slow muscles are different, but the data are equivocal. To test this hypothesis directly, three-dimensional skeletal muscle constructs were engineered from myogenic cells isolated from fast tibialis anterior (TA) and slow soleus (SOL) muscles of rats and functionality was tested. Time to peak twitch tension (TPT) and half relaxation time (RT(1/2)) were approximately 30% slower in constructs from the SOL. The slower contraction and relaxation times for the SOL constructs resulted in left shift of the force-frequency curve compared with those from the TA. Western blot analysis showed a 60% greater quantity of fast myosin heavy chain in the TA constructs. 14 days of chronic low-frequency electrical stimulation resulted in a 15% slower TPT and a 14% slower RT(1/2), but no change in absolute force production in the TA constructs. In SOL constructs, slow electrical stimulation resulted in an 80% increase in absolute force production with no change in TPT or RT(1/2). The addition of cyclosporine A did not prevent the increase in force in SOL constructs after chronic low-frequency electrical stimulation, suggesting that calcineurin is not responsible for the increase in force. We conclude that myogenic cells associated with a slow muscle are imprinted to produce muscle that contracts and relaxes slowly and that calcineurin activity cannot explain the response to a slow pattern of electrical stimulation.

  3. Adiabatic model of field reversal by fast ions in an axisymmetric open trap

    SciTech Connect

    Tsidulko, Yu. A.

    2016-06-15

    A model of field reversal by fast ions has been developed under the assumption of preservation of fast-ion adiabatic invariants. Analytical solutions obtained in the approximation of a narrow fast-ion layer and numerical solutions to the evolutionary problem are presented. The solutions demonstrate the process of formation of a field reversed configuration with parameters close to those of the planned experiment.

  4. Sex differences in the responses of orexin neurons in the lateral hypothalamic area and feeding behavior to fasting.

    PubMed

    Funabashi, Toshiya; Hagiwara, Hiroko; Mogi, Kazutaka; Mitsushima, Dai; Shinohara, Kazuyuki; Kimura, Fukuko

    2009-09-29

    Because there are sex differences in feeding-related behavior and orexin neurons are involved in feeding, we looked for a possible sex difference in the response of orexin neurons in the lateral hypothalamic area to fasting, using the phosphorylated cyclic AMP response element-binding protein (pCREB) as a marker of neural activity. Intact male and female rats at proestrus, estrus, or diestrus, were fed normally or fasted for 48h. After fasting, they were intravenously injected with saline or glucose and subjected to immunohistochemical processing for the detection of orexin and pCREB. In the rats fed normally and injected with saline, only a small population of orexin neurons expressed pCREB in both male and female rats. However, fasting increased the number of orexin neurons with pCREB (double-stained cells) in female rats regardless of the estrous day but not in male rats, revealing a significant sex difference in the response of orexin neurons to fasting. Glucose injection in fasted rats decreased the number of double-stained cells in female rats, and the magnitude of glucose-dependent decrease was greater at proestrus and estrus than at diestrus 2. We also found that female rats, but not male rats, showed an increase in total food intake after fasting (rebound feeding). We speculate that the demonstrated sex differences in the response of orexin neurons to fasting reflect the vulnerability of feeding mechanisms in females.

  5. Spike history neural response model.

    PubMed

    Kameneva, Tatiana; Abramian, Miganoosh; Zarelli, Daniele; Nĕsić, Dragan; Burkitt, Anthony N; Meffin, Hamish; Grayden, David B

    2015-06-01

    There is a potential for improved efficacy of neural stimulation if stimulation levels can be modified dynamically based on the responses of neural tissue in real time. A neural model is developed that describes the response of neurons to electrical stimulation and that is suitable for feedback control neuroprosthetic stimulation. Experimental data from NZ white rabbit retinae is used with a data-driven technique to model neural dynamics. The linear-nonlinear approach is adapted to incorporate spike history and to predict the neural response of ganglion cells to electrical stimulation. To validate the fitness of the model, the penalty term is calculated based on the time difference between each simulated spike and the closest spike in time in the experimentally recorded train. The proposed model is able to robustly predict experimentally observed spike trains.

  6. Gaining control over responses to implicit attitude tests: Implementation intentions engender fast responses on attitude-incongruent trials.

    PubMed

    Webb, Thomas L; Sheeran, Paschal; Pepper, John

    2012-03-01

    The present research investigated whether forming implementation intentions could promote fast responses to attitude-incongruent associations (e.g., woman-manager) and thereby modify scores on popular implicit measures of attitude. Expt 1 used the Implicit Association Test (IAT) to measure associations between gender and science versus liberal arts. Planning to associate women with science engendered fast responses to this category-attribute pairing and rendered summary scores more neutral compared to standard IAT instructions. Expt 2 demonstrated that forming egalitarian goal intentions is not sufficient to produce these effects. Expt 3 extended these findings to a different measure of implicit attitude (the Go/No-Go Association Task) and a different stereotypical association (Muslims-terrorism). In Expt 4, managers who planned to associate women with superordinate positions showed more neutral IAT scores relative to non-planners and effects were maintained 3 weeks later. In sum, implementation intentions enable people to gain control over implicit attitude responses. © 2010 The British Psychological Society.

  7. Characterizing a fast-response, low-afterglow liquid scintillator for neutron time-of-flight diagnostics in fast ignition experiments

    SciTech Connect

    Abe, Y. Hosoda, H.; Arikawa, Y.; Nagai, T.; Kojima, S.; Sakata, S.; Inoue, H.; Iwasa, Y.; Iwano, K.; Yamanoi, K.; Fujioka, S.; Nakai, M.; Sarukura, N.; Shiraga, H.; Norimatsu, T.; Azechi, H.

    2014-11-15

    The characteristics of oxygen-enriched liquid scintillators with very low afterglow are investigated and optimized for application to a single-hit neutron spectrometer for fast ignition experiments. It is found that 1,2,4-trimethylbenzene has better characteristics as a liquid scintillator solvent than the conventional solvent, p-xylene. In addition, a benzophenon-doped BBQ liquid scintillator is shown to demonstrate very rapid time response, and therefore has potential for further use in neutron diagnostics with fast time resolution.

  8. Foxa2 integrates the transcriptional response of the hepatocyte to fasting.

    PubMed

    Zhang, Liping; Rubins, Nir E; Ahima, Rexford S; Greenbaum, Linda E; Kaestner, Klaus H

    2005-08-01

    Survival during prolonged food deprivation depends on the activation of hepatic gluconeogenesis. Inappropriate regulation of this process is a hallmark of diabetes and other metabolic diseases. Activation of the genes encoding gluconeogenic enzymes is mediated by hormone-responsive transcription factors such as the cyclic AMP response element binding protein (CREB) and the glucocorticoid receptor (GR). Here we show using cell-type-specific gene ablation that the winged helix transcription factor Foxa2 is required for activation of the hepatic gluconeogenic program during fasting. Specifically, Foxa2 promotes gene activation both by cyclic AMP, the second messenger for glucagon, and glucocorticoids. Foxa2 mediates these effects by enabling recruitment of CREB and GR to their respective target sites in chromatin. We conclude that Foxa2 is required for execution of the hepatic gluconeogenic program by integrating the transcriptional response of the hepatocyte to hormonal stimulation.

  9. Development of a system for aerodynamic fast-response probe measurements

    NASA Astrophysics Data System (ADS)

    Gossweiler, C.; Humm, H.; Kupferschmied, P.

    This paper describes the development of a fast-response probe measurement system. Small pressure probes have been equipped with up to 4 miniature pressure sensors. The high frequency response of such sensors allied to minimized cavities between the flow and the sensing diaphragm enables the probe system to take measurements up to 40 kHz bandwidth (typical blade passing frequency: 2-10 kHz). First results of investigations on the aerodynamic of high frequency response measurement probes are presented including experiments in a water towing channel with unsteady flows around different probe geometries. The packaging of the sensor chip into the probe, the properties of the sensors and the measurement errors are examined. Probe calibration methods and aerodynamic evaluation procedures are discussed, followed by a presentation of the data acquisition system and of the data evaluation software. Measurements in a radial compressor test rig and in a fully developed pipe flow are shown as applications.

  10. Ultraviolet fast-response photoelectric effects in LiTaO3 single crystal

    NASA Astrophysics Data System (ADS)

    Guo, Er-Jia; Xing, Jie; Lu, Hui-Bin; Jin, Kui-Juan; Wen, Juan; Yang, Guo-Zhen

    2010-01-01

    The photoelectric effects of LiTaO3 (LTO) single crystals are experimentally studied with two kinds of LTO wafers, 10° tilted and untilted, at room temperature. A transient open-circuit photoelectrical response of 143 ps rise time is observed in the 10° tilted LTO when a 266 nm pulsed laser with a duration of 25 ps is irradiated directly onto the LTO surface. The untilted LTO with interdigitated electrodes of 10 µm finger width and 10 µm interspacing exhibits a linear dependence on the applied bias and power density of incident light, a response peak at about 235 nm and a sharp cutoff at about 270 nm. The noise current is only 61 pA at 20 V bias under the illumination of sunlight outdoors at midday. The experimental results suggest the promising application of the LTO single crystal in UV detection, in particular, as a solar-blind fast-response photodetector.

  11. Exupéry - a mobile fast response system for managing a volcanic crisis

    NASA Astrophysics Data System (ADS)

    Hort, M. K.

    2009-12-01

    Despite ever increasing efforts to monitor historically active volcanoes many of those are still very poorly or unmonitored, even in highly populated areas. In case of volcanic unrest or even a volcanic crisis evaluating the situation is therefore often very difficult due to the little information that is available for that specific volcano. Over the past decades several different programs have supported volcanic crisis management efforts in third world countries from sending experts all the way to improving or even installing new networks around the volcano. One of the main problems especially when quickly upgrading networks during a crisis is that each system usually comes with its own acquisition and processing system which makes it very difficult to manage the observational network and provide an interdisciplinary interpretation of the data with respect to the activity status of the volcano. Here we present a newly developed volcano fast response system which overcomes several of these shortcomings. The core of the system is a novel database (SEISHUB) that allows for the collection of data of various kinds, i.e. simple time series data like seismic data, gas measurements, GPS measurements, as well as satellite data (SO2 flux, thermal anomaly, ground deformation). Part of the collected data may also come from an already existing network. Data from new field instruments are transmitted through a wireless network that has been specifically designed for the volcano fast response system. One of the main difficulties with such a multidisciplinary data set is an easy access to the data. This is provided through a common Web based GIS interface which allows various datalayers being simultaneously accessed through a Web Browser. The underlying software is designed in such a way that it only uses open source software, so it can be easily installed on other systems not having to deal with purchasing proprietary software. Aside from this the system provides tools to

  12. Physiological responses to short-term fasting among herbivorous, omnivorous, and carnivorous fishes.

    PubMed

    Day, Ryan D; Tibbetts, Ian R; Secor, Stephen M

    2014-05-01

    We explored the integrated role of dietary specialization and feeding periodicity on the response of the gastrointestinal tract of teleosts fishes to short-term (7-10 days) fasting and refeeding. Fasted and fed herbivorous grass carp (Ctenopharyngodon idella), omnivorous channel catfish (Ictalurus punctatus), and carnivorous largemouth bass (Micropterus salmoides) were compared for digestive organ masses, intestinal morphology, gastrointestinal pH, and the specific activities and total intestinal capacities of the intestinal hydrolases aminopeptidase (APN) and maltase and intestinal nutrient transporters. All three species experience intestinal hypertrophy with feeding as noted by significant increases in enterocyte dimensions. Of the three, only I. punctatus experienced a postprandial increase in intestinal length, and only C. idella experienced significant modulation of intestinal microvillus length. Feeding resulted in acidification of the stomachs of I. punctatus and M. salmoides. Predicted to exhibit a relatively modest set of postprandial responses because of their more frequent feeding habits, C. idella only experienced increases in APN and maltase activity with feeding and no significant regulation of nutrient uptake. Significant regulation of hydrolase activities and nutrient uptake were exhibited by I. punctatus and M. salmoides, with I. punctatus experiencing the most comprehensive set of responses. As predicted by food habits, there was an interspecific gradient in intestinal length and glucose uptake extending from longer intestines and greater glucose uptake for the herbivorous C. idella, intermediate lengths and glucose uptake for the omnivorous I. punctatus, and shorter intestines and reduced glucose uptake for the carnivorous M. salmoides. Among teleosts fishes, short episodes of fasting lead to significant alterations in intestinal form and function that are rapidly restored with feeding.

  13. Advances in Fast-response Acoustically Derived Air-temperature Measurements

    NASA Astrophysics Data System (ADS)

    Bogoev, I.; Jacobsen, L.; Horst, T. W.; Conrad, B.

    2015-12-01

    Fast-response accurate air-temperature measurements are required when estimating turbulent fluxes of heat, water and carbon dioxide by open-path eddy-covariance technique. In comparison with contact thermometers like thermocouples, ultra-sonic thermometers do not suffer from solar radiation loading, water vapor condensation and evaporative cooling effects. Consequently they have the potential to provide more accurate true air temperature measurements. The absolute accuracy of the ultrasonic thermometer is limited by the following parameters: the distance between the transducer pairs, transducer delays associated with the electrical-acoustic signal conversion that vary with temperature, components of the wind vector that are normal to the ultrasonic paths, and humidity.The distance between the transducer pairs is commonly obtained by coordinate measuring machine. Improved accuracy demonstrated in this study results from increased stiffness in the anemometer head to better maintain the ultrasonic path-length distances. To further improve accuracy and account for changes in transducer delays and distance as a function of temperature, these parameters are characterized in a zero-wind chamber over the entire operating temperature range. When the sonic anemometer is combined with a co-located fast-response water vapor analyzer, like in the IRGASON instrument, speed of sound can be compensated for humidity effects on a point-by-point basis resulting in a true fast-response air temperature measurement. Laboratory test results show that when the above steps are implemented in the calibration of the ultrasonic thermometer air-temperature accuracy better than ±0.5 degrees Celsius can be achieved over the entire operating range. The approach is also validated in a field inter-comparison with an aspirated thermistor probe mounted in a radiation shield.

  14. A display module implemented by the fast high-temperatue response of carbon nanotube thin yarns.

    PubMed

    Wei, Yang; Liu, Peng; Jiang, Kaili; Fan, Shoushan

    2012-05-09

    Suspending superaligned multiwalled carbon nanotube (MWCNT) films were processed into CNT thin yarns, about 1 μm in diameter, by laser cutting and an ethanol atomization bath treatment. The fast high-temperature response under a vacuum was revealed by monitoring the incandescent light with a photo diode. The thin yarns can be electrically heated up to 2170 K in 0.79 mS, and the succeeding cool-down time is 0.36 mS. The fast response is attributed to the ultrasmall mass of the independent single yarn, large radiation coefficient, and improved thermal conductance through the two cool ends. The millisecond response time makes it possible to use the visible hot thin yarns as light-emitting elements of an incandescent display. A fully sealed display with 16 × 16 matrix was successfully fabricated using screen-printed thick electrodes and CNT thin yarns. It can display rolling characters with a low power consumption. More applications can be further developed based on the addressable CNT thermal arrays.

  15. Fast response temperature and humidity sensors for measurements in high Reynolds number flows

    NASA Astrophysics Data System (ADS)

    Fan, Yuyang; Arwatz, Gilad; Vallikivi, Margit; Hultmark, Marcus

    2013-11-01

    Conventional hot/cold wires have been widely used in measuring velocity and temperature in turbulent flows due to their fine resolutions and fast response. However, for very high Reynolds number flows, limitations on the resolution appear. A very high Reynolds number flow is the atmospheric boundary layer. In order to accurately predict the energy balance at the Earth's surface, one needs information about the different turbulent scalar fields, mainly temperature and humidity, which together with velocity, contribute to the turbulent fluxes away from the surface. The nano-scaled thermal anemometry probe (NSTAP) was previously developed at Princeton and has proven to have much higher spatial and temporal resolution than the regular hot wires. Here we introduce new fast-response temperature and humidity sensors that have been developed and tested. These sensors are made in-house using standard MEMS manufacturing techniques, leaving high flexibility in the process for optimization to different conditions. The small dimensions of these novel sensors enable very high spatial resolution while the small thermal mass allows significant improvements in the frequency response. These sensors have shown promising results in acquiring un-biased data of turbulent scalar and vector fields. Supported under ONR Grants N00014-12-1-0875 and N00014-12-1-0962 (program manager Ki-Han Kim).

  16. Differential Macrophage Response to Slow- and Fast-Growing Pathogenic Mycobacteria

    PubMed Central

    Helguera-Repetto, A. Cecilia; Chacon-Salinas, Rommel; Cerna-Cortes, Jorge F.; Rivera-Gutierrez, Sandra; Ortiz-Navarrete, Vianney; Estrada-Garcia, Iris; Gonzalez-y-Merchand, Jorge A.

    2014-01-01

    Nontuberculous mycobacteria (NTM) have recently been recognized as important species that cause disease even in immunocompetent individuals. The mechanisms that these species use to infect and persist inside macrophages are not well characterised. To gain insight concerning this process we used THP-1 macrophages infected with M. abscessus, M. fortuitum, M. celatum, and M. tuberculosis. Our results showed that slow-growing mycobacteria gained entrance into these cells with more efficiency than fast-growing mycobacteria. We have also demonstrated that viable slow-growing M. celatum persisted inside macrophages without causing cell damage and without inducing reactive oxygen species (ROS), as M. tuberculosis caused. In contrast, fast-growing mycobacteria destroyed the cells and induced high levels of ROS. Additionally, the macrophage cytokine pattern induced by M. celatum was different from the one induced by either M. tuberculosis or fast-growing mycobacteria. Our results also suggest that, in some cases, the intracellular survival of mycobacteria and the immune response that they induce in macrophages could be related to their growth rate. In addition, the modulation of macrophage cytokine production, caused by M. celatum, might be a novel immune-evasion strategy used to survive inside macrophages that is different from the one reported for M. tuberculosis. PMID:24949482

  17. Fast magnetic resonance imaging of the internal impact response of dense granular suspensions

    NASA Astrophysics Data System (ADS)

    Müller, Christoph; Penn, Alexander; Pruessmann, Klaas P.

    Dense granular suspensions exhibit a number of intriguing properties such as discontinuous shear-thickening and the formation of dynamic jamming fronts when impacted by a solid. Probing non-intrusively these phenomena experimentally in full three-dimensional systems is, however, highly challenging as suspensions are commonly opaque and thus, not accessible optically. Here we report the development and implementation of a fast magnetic resonance imaging (MRI) methodology allowing us to image the internal dynamics of dense granular suspensions at high temporal resolutions. An important facet of this work is the implementation of parallel MRI using tailored multi-channel receive hardware and the optimization of magnetic properties (susceptibility and NMR relaxivity) of the liquid phase. These two improvements enable us to utilize fast single-shot pulse sequences while yielding sufficient signal intensity at temporal resolutions of less than 50 ms. Furthermore, using motion-sensitive MR pulse sequences we are able to image bulk motion within the system and the response of dense granular suspensions to fast impacts.

  18. Response of the thermosphere and ionosphere to an ultra fast Kelvin wave

    NASA Astrophysics Data System (ADS)

    Chang, Loren C.; Palo, Scott E.; Liu, Han-Li; Fang, Tzu-Wei; Lin, Chin S.

    2010-08-01

    Ultra Fast Kelvin (UFK) waves are eastward propagating planetary waves with periods between 3 and 5 days, which are capable of penetrating into the thermosphere and ionosphere where they may modulate phenomena occurring in this region. A sensitivity study has been conducted to examine the effect of an Ultra Fast Kelvin wave on the thermosphere and ionosphere using the NCAR Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIME-GCM) under June solstice solar minimum conditions. It is found that realistic ultra fast Kelvin waves with amplitudes in the MLT region of approximately 20-40 m s-1 in zonal wind fields and 10-20 K in temperature fields, can result in approximately 8-12% perturbations in hourly neutral density at 350 km, as well as hourly total electron content (TEC) perturbations of 25-50% in regions corresponding to the equatorial ionization anomalies (EIAs), with the largest relative changes resolved during the nighttime due to the lower electron densities. The electrodynamical calculations in the model were then disabled to identify the relative importance of ionospheric electrodynamics and direct wave propagation in generating the aforementioned changes. The subsequent results show that changes in thermospheric neutral density are relatively insensitive to the presence of the dynamo electric field, while UFK wave modulation of the dynamo accounts for most of the TEC perturbations due to changes of ionospheric vertical plasma drift.

  19. Development of new oxygen sensor for Argo profiling floats: Fast responsivity and long-term stability

    NASA Astrophysics Data System (ADS)

    Mori, K.; Takai, S. I.; Uchida, H.; Sato, K.; Hosoda, S.; Kobayashi, T.

    2016-02-01

    Dissolved oxygen (DO) is one of key parameters governing physical/biochemical processes in the ocean. JFE Advantech's RINKO series is widely known for markedly fast response optical DO sensors and can assist in revealing a small-scale DO structure, which will contribute to understanding new aspects of the processes. Long-term stability is of secondary importance for the conventional RINKO series and the highest accuracy is being maintained by a regular recalibration. Meanwhile, Argo profiling floats require satisfying a high accuracy for multiple years without a recalibration because the floats are generally not recovered and post-calibrated. The RINKO FT is a new member of the RINKO series and has overcome a well-known tradeoff between fast responsivity and stability of a DO sensing foil. The RINKO FT not only retains the fast response time (63%: less than 1 s in water) identical to that of conventional RINKO series but also has greater accuracy and stability by incorporating a high-quality multipoint calibration and improving the sensing method. Two MRV S3A floats with RINKO FT were launched in the northwestern Pacific Ocean in July 2014 and one of the floats is still operating in the field. The DO sampling interval was 2 dbar throughout the water column (from 2000 m to the surface) to take advantage of the fast responsivity. The RINKO FT data of the first dive agreed well with the Winkler titration data sampled near the dive point. The vertical high-resolution measurement detected thin layers with DO maximum/minimum in the subsurface. The linear trend of the DO data obtained from the RINKO FT indicates no significant time drift of less than 1 μmol/kg per year along a potential density of 27.6 σθ lying at a depth of 1600 - 1900 m. Although the RINKO FT is primarily designed to target Argo float operations, its compact, lightweight design and commonly used communication protocols widen the choice of platforms for installation.

  20. Fast-response gas analyzer by the use of an infrared hollow fibre

    NASA Astrophysics Data System (ADS)

    Saito, Mitsunori; Okubo, Yuri; Kato, Tomoki

    2005-05-01

    A fast-response infrared spectrometer was constructed by using an AgI/Ag-coated hollow fibre and a PtSi CCD sensor array. The infrared transmitting hollow fibre was employed as a gas-flow cell to reduce both sample volume and sampling time. The infrared beam that passed the hollow fibre was diffracted by a grating, and was detected by the sensor array with a 1/60-s frame time. Spectra of flowing CH4 and CO2 gases were measured successfully in the 3-4-μm wavelength range.

  1. Neural Network Model For Fast Learning And Retrieval

    NASA Astrophysics Data System (ADS)

    Arsenault, Henri H.; Macukow, Bohdan

    1989-05-01

    An approach to learning in a multilayer neural network is presented. The proposed network learns by creating interconnections between the input layer and the intermediate layer. In one of the new storage prescriptions proposed, interconnections are excitatory (positive) only and the weights depend on the stored patterns. In the intermediate layer each mother cell is responsible for one stored pattern. Mutually interconnected neurons in the intermediate layer perform a winner-take-all operation, taking into account correlations between stored vectors. The performance of networks using this interconnection prescription is compared with two previously proposed schemes, one using inhibitory connections at the output and one using all-or-nothing interconnections. The network can be used as a content-addressable memory or as a symbolic substitution system that yields an arbitrarily defined output for any input. The training of a model to perform Boolean logical operations is also described. Computer simulations using the network as an autoassociative content-addressable memory show the model to be efficient. Content-addressable associative memories and neural logic modules can be combined to perform logic operations on highly corrupted data.

  2. Diving response after a one-week diet and overnight fasting.

    PubMed

    Ghiani, Giovanna; Marongiu, Elisabetta; Olla, Sergio; Pinna, Marco; Pusceddu, Matteo; Palazzolo, Girolamo; Sanna, Irene; Roberto, Silvana; Crisafulli, Antonio; Tocco, Filippo

    2016-01-01

    We hypothesized that overnight fasting after a short dietary period, especially with carbohydrates, could allow performing breath-hold diving with no restraint for diaphragm excursion and blood shift and without any increase of metabolism, and in turn improve the diving response. During two separate sessions, 8 divers carried out two trials: (A) a 30-m depth dive, three hours after a normal breakfast and (B) a dive to the same depth, but after following a diet and fasting overnight. Each test consisted of 3 apnea phases: descent, static and ascent whose durations were measured by a standard chronometer. An impedance cardiograph, housed in an underwater torch, provided data on trans-thoracic fluid index (TFI), stroke volume (SV), heart rate (HR) and cardiac output (CO). Mean blood pressure (MBP), arterial O2 saturation (SaO2), blood glucose (Glu) and blood lactate (BLa) were also collected. In condition B, duration of the static phase of the dive was longer than A (37.8 ± 7.4 vs. 27.3 ± 8.4 s respectively, P < 0.05). In static phases, mean ∆ SV value (difference between basal and nadir values) during fasting was lower than breakfast one (-2.6 ± 5.1 vs. 5.7 ± 7.6 ml, P < 0.05). As a consequence, since mean ∆ HR values were equally decreased in both metabolic conditions, mean ∆ CO value during static after fasting was lower than the same phase after breakfast (-0.4 ± 0.5 vs. 0.4 ± 0.5 L · min(-1) respectively, P < 0.05). At emersion, despite the greater duration of dives during fasting, SaO2 was higher than A (92.0 ± 2.7 vs. 89.4 ± 2.9 % respectively, P < 0.05) and BLa was lower in the same comparison (4.2 ± 0.7 vs. 5.3 ± 1.1 mmol∙L(-1), P < 0.05). An adequate balance between metabolic and splancnic status may improve the diving response during a dive at a depth of 30 m, in safe conditions for the athlete's health.

  3. Utilization of Fast Running Models in Buried Blast Simulations of Ground Vehicles for Significant Computational Efficiency

    DTIC Science & Technology

    2013-08-07

    threat LS - Dyna Eulerian analysis for 2-stage analysis LS - Dyna Lagrangian analysis for 2-stage analysis Create fast running models for underbody blast ...studies Use fast running models for underbody blast studies LS - Dyna Lagrangian analysis for 2-stage analysis Generate air/soil/explosive model...average velocity results correlate well with LS - DYNA simulation over 12 evaluation points UNCLASSIFIED Conclusions • FRMs enable rapid

  4. Problems in modeling TF ripple loss of fast alphas from a tokamak reactor

    SciTech Connect

    Hively, L.M.

    1987-01-01

    The present status of modeling TF ripple loss of fast alphas from tokamaks is summarized. The modeling issues are discussed, and several new aspects of this problem are described, including gyromotion, radial electric field, and sawtoothing. Existing models predict that TF ripple loss of fast alphas will have a low-to-moderate impact on the design of a tokamak engineering test reactor (ETR). 52 refs., 3 figs., 2 tabs.

  5. Fast and singular muscle responses initiate the startle response of Pantodon buchholzi (Osteoglossomorpha).

    PubMed

    Starosciak, A K; Kalola, R P; Perkins, K P; Riley, J A; Saidel, W M

    2008-01-01

    The startle response of Pantodon buchholzi, the African butterfly fish, is a complete or incomplete ballistic jump resulting from abduction of the pectoral fins. This study analyzed the neuromuscular basis for such a jump by recording in vivo electromyograms (emgs) from the muscles of abduction, the muscularis abductor superficialis (MAS) and the muscularis abductor profundus (MAP). The motor neurons innervating the MAS muscle were localized by retrograde transport of biocytin. The latency between stimulus and the evoked emg in the MAS was less than 5 ms; the latency of the MAP was about 6.5 ms. A single emg was recorded per jump. High speed video demonstrated that onset of a startle movement began within 10 ms of the onset of fin abduction. The emg associated with this movement is short (<2 ms) and followed by a variably-shaped, slower and smaller potential of 10-30 ms duration. The brief period between stimulus and startle response of Pantodon suggests a Mauthner neuron-related response, only with the behavior occurring in the vertical plane. The MAS may act only in a startle response, whereas the MAP might have a role in other behaviors. Elicited jumping habituates after a single trial. Electrophysiological evidence is presented indicating that the innervating motor neurons are suppressed for seconds following a stimulus. The neurons innervating the MAS are located at the medullary-spinal cord junction and possess an average radius of approximately 17.9 mum. These fish have been historically described as 'fresh water' flying fish. As a single emg occurs per startle response, repetitive pectoral activity generating flying cannot be supported. Pantodon 'flight' is ballistic.

  6. Modelling hormonal response and development.

    PubMed

    Voß, Ute; Bishopp, Anthony; Farcot, Etienne; Bennett, Malcolm J

    2014-05-01

    As our knowledge of the complexity of hormone homeostasis, transport, perception, and response increases, and their outputs become less intuitive, modelling is set to become more important. Initial modelling efforts have focused on hormone transport and response pathways. However, we now need to move beyond the network scales and use multicellular and multiscale modelling approaches to predict emergent properties at different scales. Here we review some examples where such approaches have been successful, for example, auxin-cytokinin crosstalk regulating root vascular development or a study of lateral root emergence where an iterative cycle of modelling and experiments lead to the identification of an overlooked role for PIN3. Finally, we discuss some of the remaining biological and technical challenges. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  7. Glycemic and insulinemic responses to different preexercise snacks in participants with impaired fasting glucose.

    PubMed

    Byrne, Heidi K; Kim, Yeonsoo; Hertzler, Steven R; Watt, Celia A; Mattern, Craig O

    2011-02-01

    To compare serum glucose and insulin responses to 3 preexercise snacks before, during, and after exercise in individuals with impaired fasting glucose (IFG) and healthy (H) men. In addition, in an IFG population, the authors sought to determine whether a natural fruit snack (i.e., raisins) yields more desirable glucose and insulin concentrations than an energy bar or a glucose solution. The IFG (n = 11, age = 54.5 ± 1.3 yr, fasting blood glucose [BG] = 6.3 ± 0.1 mmol/L) and H groups (n = 9, age = 48.0 ± 3.1 yr, fasting BG = 4.9 ± 0.1 mmol/L) cycled at 50% of VO2peak for 45 min on 4 occasions after consuming water or 50 g of carbohydrate from raisins (R), an energy bar (EB), or a glucose beverage (GLU). Metabolic markers were measured before, during, and after exercise. In all nutritional conditions, glucose concentrations of the IFG group were consistently higher than in the H group. Differences between IFG and H groups in insulin concentrations were sporadic and isolated. In the IFG group, preexercise glucose concentration was lower in the R condition than in GLU. Ten and 20 min into exercise, glucose concentrations in the R and EB conditions were lower than in GLU. Insulin concentrations were lower in the R condition than in EB and GLU immediately before exercise and at Minute 10 but at 20 min R remained lower than only GLU. Glucose concentrations were higher in the IFG group regardless of preexercise snack. Compared with the glucose solution, raisins lowered both the postprandial glycemic and insulinemic responses, whereas the energy bar reduced glycemia but not insulinemia.

  8. ABNORMAL RESPONSE OF MELANIN-CONCENTRATING HORMONE DEFICIENT MICE TO FASTING: HYPERACTIVITY AND REM SLEEP SUPPRESSION

    PubMed Central

    Willie, Jon T; Sinton, Christopher M; Maratos-Flier, Eleftheria; Yanagisawa, Masashi

    2008-01-01

    Melanin-concentrating hormone (MCH) is a hypothalamic neuropeptide that has been implicated in energy homeostasis. Pharmacological studies with MCH and its receptor antagonists have suggested additional behavioral roles for the neuropeptide in the control of mood and vigilance states. These suggestions have been supported by a report of modified sleep in the MCH-1 receptor knockout mouse. Here we found that MCH knockout (MCH−/−) mice slept less during both the light and dark phases under baseline conditions. In response to fasting, MCH−/− mice exhibited marked hyperactivity, accelerated weight loss and an exaggerated decrease in rapid eye movement (REM) sleep. Following a 6-h period of sleep deprivation, however, the sleep rebound in MCH−/− mice was normal. Thus MCH−/− mice adapt poorly to fasting, and their loss of bodyweight under this condition is associated with behavioral hyperactivity and abnormal expression of REM sleep. These results support a role for MCH in vigilance state regulation in response to changes in energy homeostasis and may relate to a recent report of initial clinical trials with a novel MCH-1 receptor antagonist. When combined with caloric restriction, the treatment of healthy, obese subjects with this compound resulted in some subjects experiencing vivid dreams and sleep disturbances. PMID:18809470

  9. Constructing Fast Carrier Tracks into Flexible Perovskite Photodetectors To Greatly Improve Responsivity.

    PubMed

    Li, Xiaoming; Yu, Dejian; Chen, Jun; Wang, Yue; Cao, Fei; Wei, Yi; Wu, Ye; Wang, Lin; Zhu, Ying; Sun, Zhiguo; Ji, Jianping; Shen, Yalong; Sun, Handong; Zeng, Haibo

    2017-02-28

    Intrinsically high mobility and large absorption coefficient endow inorganic halide perovskites (IHPs) with great promise for high-performance photodetectors (PDs), which, however, are being hindered by the low carrier extraction and transport efficiency of the solution assembled films. Here, we report on a general strategy to enhance the perovskite film conductivity that carbon nanotubes (CNTs) conductive nanonets are constructed from to provide fast carrier tracks. Resultantly, the CsPbBr3 nanosheet/CNT composite films exhibit both high light harvesting and high conductivity, such advantages are demonstrated by the high performances of corresponding planar PDs. Specifically, the highest external quantum efficiency (EQE) of 7488% and the highest responsivity of 31.1 A W(-1) under a bias of 10 V among IHP PDs with planar structure are achieved, which are almost 125-fold over the previous best results. Besides, the efficient charge extraction and transport also remarkably contribute to the fast response speed where a rise time of 16 μs is achieved, which is also superior to state-of-the-art IHP PDs. Furthermore, the composite films exhibit impressive flexibility due to the ultrathin 2D and 1D structural characteristic of perovskites and CNTs. By deploying the PD as a point-like detector, we acquire clear images. The results indicate the promising potentials of the perovskite/CNT composites for solution and ambient condition processed flexible devices, and this strategy is general for all kinds of perovskite optoelectronic devices including photodetectors, phototransistors, and even LEDs.

  10. Infants' brain responses for speech sound changes in fast multifeature MMN paradigm.

    PubMed

    Partanen, Eino; Pakarinen, Satu; Kujala, Teija; Huotilainen, Minna

    2013-08-01

    We investigated whether newborn speech-sound discrimination can be studied in 40 min using fast multifeature mismatch negativity (MMN) paradigm and do the results differ from those obtained with the traditional oddball paradigm. Newborns' MMN responses to five types of changes (consonant identity, F0, intensity, vowel duration and vowel identity) were recorded in the multifeature group (N=15) and vowel duration and vowel identity changes in the oddball group (N=13), after which the MMNs from both groups were compared with each others. Statistically significant MMNs in the 190-600 ms time range from the stimulus onset were found for most change types in both paradigms. Newborn MMN responses were predominantly positive but a small number of participants elicited negative MMNs instead. MMN amplitudes did not differ between the multifeature and oddball groups. Newborn speech-sound discrimination can be assessed in a short recording time using the fast multifeature paradigm. The paradigm presented here can be used to record extensive auditory discrimination profiles in newborns and assess development of speech-sound discrimination and its difficulties. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  11. Responses of roots to simulated weightlessness on the fast-rotating clinostat.

    PubMed

    Sobick, V; Sievers, A

    1979-01-01

    Sedimentable cell particles are distributed randomly along the horizontal axis of the fast-rotating clinostat. They neither sediment in the direction of gravity, nor in the direction of the centrifugal force, nor in the direction of the resultant force of both. The effect of this "weightlessness" and that of very small centrifugal forces on the perception of mass acceleration was examined using young primary roots of Lepidium sativum L. (Cruciferae) during their early development on the fast-rotating clinostat. The results of the experiments show: 1) there is no response of the roots in the direction of gravity, 2) at small centrifugal forces (< 2.2 x 10(-2) g) a curvature response occurs in the direction of the stimulus, 3) the threshold value for the perception of mass acceleration lies at 4.3 x 10(-3) g, and 4) below the threshold value the existence of an autonomous root curvature has been proved for the first time, which is not caused by mass acceleration.

  12. A fast response variable optical attenuator based on blue phase liquid crystal.

    PubMed

    Zhu, Ge; Wei, Bing-yan; Shi, Liang-yu; Lin, Xiao-wen; Hu, Wei; Huang, Zhang-di; Lu, Yan-qing

    2013-03-11

    Blue phase liquid crystals (BPLCs) are promising candidates for next generation display thanks to their fast response and quasi-isotropic optical properties. By taking these advantages, we propose to introduce the material into fiber-optic applications. As an example, a BPLC based variable optical attenuator (VOA) is demonstrated with a polarization independent design. The device shows normally-off feature when no field is applied. Response time down to submillisecond scale is achieved in switching between two arbitrary attenuation states. The attenuation range is also measured from 1480 to 1550 nm, which cover the whole telecomm S-band and part of the C-band. The overall performances reach the requirements for practical use; while still have room for further improvement. Through this example, the applicability of BPLC in fiber-optic devices is presented, which may impel the development of many other photonic applications from infrared to even microwave regions.

  13. Thermal remote sensing as a part of Exupéry volcano fast response system

    NASA Astrophysics Data System (ADS)

    Zakšek, Klemen; Hort, Matthias

    2010-05-01

    In order to understand the eruptive potential of a volcanic system one has to characterize the actual state of stress of a volcanic system that involves proper monitoring strategies. As several volcanoes in highly populated areas especially in south east Asia are still nearly unmonitored a mobile volcano monitoring system is currently being developed in Germany. One of the major novelties of this mobile volcano fast response system called Exupéry is the direct inclusion of satellite based observations. Remote sensing data are introduced together with ground based field measurements into the GIS database, where the statistical properties of all recorded data are estimated. Using physical modelling and statistical methods we hope to constrain the probability of future eruptions. The emphasis of this contribution is on using thermal remote sensing as tool for monitoring active volcanoes. One can detect thermal anomalies originating from a volcano by comparing signals in mid and thermal infrared spectra. A reliable and effective thermal anomalies detection algorithm was developed by Wright (2002) for MODIS sensor; it is based on the threshold of the so called normalized thermal index (NTI). This is the method we use in Exupéry, where we characterize each detected thermal anomaly by temperature, area, heat flux and effusion rate. The recent work has shown that radiant flux is the most robust parameter for this characterization. Its derivation depends on atmosphere, satellite viewing angle and sensor characteristics. Some of these influences are easy to correct using standard remote sensing pre-processing techniques, however, some noise still remains in data. In addition, satellites in polar orbits have long revisit times and thus they might fail to follow a fast evolving volcanic crisis due to long revisit times. Thus we are currently testing Kalman filter on simultaneous use of MODIS and AVHRR data to improve the thermal anomaly characterization. The advantage of

  14. The synthetic scattering function and application to the design of cold moderators for pulsed neutron sources: a fast response methane based array

    SciTech Connect

    Granada, J. R.; Mayer, R. E.; Gillette, V. H.

    1997-09-01

    The Synthetic Scattering Function (SSF) allows a simple description of the incoherent interaction of slow neutrons with hydrogenous materials. The main advantages of this model reside in the analytical expressions that it produces for double-differential cross sections, energy-transfer kernels, and total cross sections, which in turn permit the fast evaluation of neutron scattering and transport properties. In this work we briefly discuss basic features of the SSF, review some previous applications to a number of moderating materials, and present new Monte Carlo results for a fast time-response moderator concept based on methane at low temperatures. (auth)

  15. Fast-response humidity-sensing films based on methylene blue aggregates formed on nanoporous semiconductor films

    NASA Astrophysics Data System (ADS)

    Ishizaki, Ryota; Katoh, Ryuzi

    2016-05-01

    We prepared fast-response colorimetric humidity-sensing (vapochromic) films based on methylene blue adsorption onto nanoporous semiconductor (TiO2, Al2O3) films. Color changes caused by changes of humidity could be easily identified visually. A characteristic feature of the vapochromic films was their fast response to changes of humidity. We found that the response began to occur within 10 ms. The response was rapid because all the methylene blue molecules attached to the nanoporous semiconductor surface were directly exposed to the environment. We also deduced that the color changes were caused by structural changes of the methylene blue aggregates on the surface.

  16. Chaos and Variability of Inter-Spike Intervals in Neuronal Models with Slow-Fast Dynamics

    NASA Astrophysics Data System (ADS)

    Doi, Shinji; Inoue, Junko

    2011-04-01

    A neuron generates action potentials or spikes in response to electric stimuli, and also produces a train of spikes (periodic oscillation) when a continuous stimulus current is injected. Using the extended Bonhoeffer-van der Pol (BVP) or FitzHugh-Nagumo (FHN) equations, which is a simplified version of the famous Hodgkin-Huxley neuronal model, we show that very slow spiking can appear near the (singular) Hopf bifurcation point in a certain generic situation. The patterns of the extraordinary slow spiking are phenomenologically classified into two types: a regular slow spiking and chaotic slow spiking. The variability of inter-spike intervals (ISI's) and the possible mechanism of slow spiking are discussed under slow-fast decomposition analysis. The noise effects on such variability of ISI's are also examined.

  17. Fast Model Generalized Pseudopotential Theory Interatomic Potential Routine

    SciTech Connect

    2015-03-18

    MGPT is an unclassified source code for the fast evaluation and application of quantum-based MGPT interatomic potentials for mrtals. The present version of MGPT has been developed entirely at LLNL, but is specifically designed for implementation in the open-source molecular0dynamics code LAMMPS maintained by Sandia National Laboratories. Using MGPT in LAMMPS, with separate input potential data, one can perform large-scale atomistic simulations of the structural, thermodynamic, defeat and mechanical properties of transition metals with quantum-mechanical realism.

  18. A Measurement Model for Likert Responses that Incorporates Response Time

    ERIC Educational Resources Information Center

    Ferrando, Pere J.; Lorenzo-Seva, Urbano

    2007-01-01

    This article describes a model for response times that is proposed as a supplement to the usual factor-analytic model for responses to graded or more continuous typical-response items. The use of the proposed model together with the factor model provides additional information about the respondent and can potentially increase the accuracy of the…

  19. A Measurement Model for Likert Responses that Incorporates Response Time

    ERIC Educational Resources Information Center

    Ferrando, Pere J.; Lorenzo-Seva, Urbano

    2007-01-01

    This article describes a model for response times that is proposed as a supplement to the usual factor-analytic model for responses to graded or more continuous typical-response items. The use of the proposed model together with the factor model provides additional information about the respondent and can potentially increase the accuracy of the…

  20. Mesoscale Simulation Data for Initializing Fast-Time Wake Transport and Decay Models

    NASA Technical Reports Server (NTRS)

    Ahmad, Nashat N.; Proctor, Fred H.; Vanvalkenburg, Randal L.; Pruis, Mathew J.; LimonDuparcmeur, Fanny M.

    2012-01-01

    The fast-time wake transport and decay models require vertical profiles of crosswinds, potential temperature and the eddy dissipation rate as initial conditions. These inputs are normally obtained from various field sensors. In case of data-denied scenarios or operational use, these initial conditions can be provided by mesoscale model simulations. In this study, the vertical profiles of potential temperature from a mesoscale model were used as initial conditions for the fast-time wake models. The mesoscale model simulations were compared against available observations and the wake model predictions were compared with the Lidar measurements from three wake vortex field experiments.

  1. fast_protein_cluster: parallel and optimized clustering of large-scale protein modeling data

    PubMed Central

    Hung, Ling-Hong; Samudrala, Ram

    2014-01-01

    Motivation: fast_protein_cluster is a fast, parallel and memory efficient package used to cluster 60 000 sets of protein models (with up to 550 000 models per set) generated by the Nutritious Rice for the World project. Results: fast_protein_cluster is an optimized and extensible toolkit that supports Root Mean Square Deviation after optimal superposition (RMSD) and Template Modeling score (TM-score) as metrics. RMSD calculations using a laptop CPU are 60× faster than qcprot and 3× faster than current graphics processing unit (GPU) implementations. New GPU code further increases the speed of RMSD and TM-score calculations. fast_protein_cluster provides novel k-means and hierarchical clustering methods that are up to 250× and 2000× faster, respectively, than Clusco, and identify significantly more accurate models than Spicker and Clusco. Availability and implementation: fast_protein_cluster is written in C++ using OpenMP for multi-threading support. Custom streaming Single Instruction Multiple Data (SIMD) extensions and advanced vector extension intrinsics code accelerate CPU calculations, and OpenCL kernels support AMD and Nvidia GPUs. fast_protein_cluster is available under the M.I.T. license. (http://software.compbio.washington.edu/fast_protein_cluster) Contact: lhhung@compbio.washington.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:24532722

  2. fast_protein_cluster: parallel and optimized clustering of large-scale protein modeling data.

    PubMed

    Hung, Ling-Hong; Samudrala, Ram

    2014-06-15

    fast_protein_cluster is a fast, parallel and memory efficient package used to cluster 60 000 sets of protein models (with up to 550 000 models per set) generated by the Nutritious Rice for the World project. fast_protein_cluster is an optimized and extensible toolkit that supports Root Mean Square Deviation after optimal superposition (RMSD) and Template Modeling score (TM-score) as metrics. RMSD calculations using a laptop CPU are 60× faster than qcprot and 3× faster than current graphics processing unit (GPU) implementations. New GPU code further increases the speed of RMSD and TM-score calculations. fast_protein_cluster provides novel k-means and hierarchical clustering methods that are up to 250× and 2000× faster, respectively, than Clusco, and identify significantly more accurate models than Spicker and Clusco. fast_protein_cluster is written in C++ using OpenMP for multi-threading support. Custom streaming Single Instruction Multiple Data (SIMD) extensions and advanced vector extension intrinsics code accelerate CPU calculations, and OpenCL kernels support AMD and Nvidia GPUs. fast_protein_cluster is available under the M.I.T. license. (http://software.compbio.washington.edu/fast_protein_cluster) © The Author 2014. Published by Oxford University Press.

  3. Radiogenomics and radiotherapy response modeling

    NASA Astrophysics Data System (ADS)

    El Naqa, Issam; Kerns, Sarah L.; Coates, James; Luo, Yi; Speers, Corey; West, Catharine M. L.; Rosenstein, Barry S.; Ten Haken, Randall K.

    2017-08-01

    Advances in patient-specific information and biotechnology have contributed to a new era of computational medicine. Radiogenomics has emerged as a new field that investigates the role of genetics in treatment response to radiation therapy. Radiation oncology is currently attempting to embrace these recent advances and add to its rich history by maintaining its prominent role as a quantitative leader in oncologic response modeling. Here, we provide an overview of radiogenomics starting with genotyping, data aggregation, and application of different modeling approaches based on modifying traditional radiobiological methods or application of advanced machine learning techniques. We highlight the current status and potential for this new field to reshape the landscape of outcome modeling in radiotherapy and drive future advances in computational oncology.

  4. Reduction of calcium release site models via fast/slow analysis and iterative aggregation/disaggregation.

    PubMed

    Hao, Yan; Kemper, Peter; Smith, Gregory D

    2009-09-01

    Mathematical models of calcium release sites derived from Markov chain models of intracellular calcium channels exhibit collective gating reminiscent of the experimentally observed phenomenon of calcium puffs and sparks. Such models often take the form of stochastic automata networks in which the transition probabilities of each channel depend on the local calcium concentration and thus the state of the other channels. In order to overcome the state-space explosion that occurs in such compositionally defined calcium release site models, we have implemented several automated procedures for model reduction using fast/slow analysis. After categorizing rate constants in the single channel model as either fast or slow, groups of states in the expanded release site model that are connected by fast transitions are lumped, and transition rates between reduced states are chosen consistent with the conditional probability distribution among states within each group. For small problems these conditional probability distributions can be numerically calculated from the full model without approximation. For large problems the conditional probability distributions can be approximated without the construction of the full model by assuming rapid mixing of states connected by fast transitions. Alternatively, iterative aggregation/disaggregation may be employed to obtain reduced calcium release site models in a memory-efficient fashion. Benchmarking of several different iterative aggregation/disaggregation-based fast/slow reduction schemes establishes the effectiveness of automated calcium release site reduction utilizing the Koury-McAllister-Stewart method.

  5. SCRAM: a fast computational model for the optical performance of point fucus solar central receiver systems

    SciTech Connect

    Bergeron, K. D.; Chiang, C. J.

    1980-04-01

    Because of the complexities of heliostat shadowing and blocking calculations, computational models for the optical performance of point focus central receiver (PFCR) systems tend to be too slow for many important applications, such as optimization studies based on performance with realistic weather data. In this paper, a mathematical approximation procedure, designated Sandia Central Receiver Approximation Model (SCRAM) will be described. Rather than simulating the system components from first principles, it relies on data generated by the DELSOL code of Dellin and Fish for the optical performance of PFCR systems, and abstracts a mathematical model using a stepwise regression procedure. The result is a computational procedure which allows the user to define the heliostat field boundaries and tower height arbitrarily, generating a model for optical field performance, including shadowing, blocking, cosine, losses, and atmospheric attenuation, and which requires only a polynomial evaluation for each set of sun angles. A comparison with DELSOL for three different fields on three representative days indicates that the rms error of the approximation is 1-3% and that the new code is 1,000-3,000 times as fast as DELSOL. It is also shown that one reason that the accuracy in field performance predictions is higher than that of the generting function for the model is that much of the error in the generating function is due to an oscillatory behavior associated with a moire pattern in the optical response of the heiostat field.

  6. Corticotropin-releasing factor-overexpressing mice exhibit reduced neuronal activation in the arcuate nucleus and food intake in response to fasting.

    PubMed

    Stengel, Andreas; Goebel, Miriam; Million, Mulugeta; Stenzel-Poore, Mary P; Kobelt, Peter; Mönnikes, Hubert; Taché, Yvette; Wang, Lixin

    2009-01-01

    Corticotropin-releasing factor (CRF) overexpressing (OE) mice are a genetic model that exhibits features of chronic stress. We investigated whether the adaptive feeding response to a hypocaloric challenge induced by food deprivation is impaired under conditions of chronic CRF overproduction. Food intake response to a 16-h overnight fast and ip injection of gut hormones regulating food intake were compared in CRF-OE and wild type (WT) littermate mice along with brain Fos expression, circulating ghrelin levels, and gastric emptying of a nonnutrient meal. CRF-OE mice injected ip with saline showed a 47 and 44% reduction of 30-min and 4-h cumulative food intake response to an overnight fast, respectively, compared with WT. However, the 30-min food intake decrease induced by ip cholecystokinin (3 microg/kg) and increase by ghrelin (300 microg/kg) were similar in CRF-OE and WT mice. Overnight fasting increased the plasma total ghrelin to similar levels in CRF-OE and WT mice, although CRF-OE mice had a 2-fold reduction of nonfasting ghrelin levels. The number of Fos-immunoreactive cells induced by fasting in the arcuate nucleus was reduced by 5.9-fold in CRF-OE compared with WT mice whereas no significant changes were observed in other hypothalamic nuclei. In contrast, fasted CRF-OE mice displayed a 5.6-fold increase in Fos-immunoreactive cell number in the dorsal motor nucleus of the vagus nerve and a 34% increase in 20-min gastric emptying. These findings indicate that sustained overproduction of hypothalamic CRF in mice interferes with fasting-induced activation of arcuate nucleus neurons and the related hyperphagic response.

  7. Modeling of traveling compression regions in the Earth's magnetotail by the spontaneous fast reconnection model

    SciTech Connect

    Ugai, M.; Zheng, L.

    2006-03-15

    The spontaneous fast reconnection model is applied to the traveling compression regions (TCRs) observed in the Earth's magnetotail lobe region in association with substorms. For this purpose, virtual satellites are located at spatial points in the (low-{beta}) magnetic field region in the three-dimenisonal simulation domain, so that each satellite directly observes the temporal variations of magnetic fields, obtained from simulations, in accordance with the growth and proceeding of the fast reconnection mechanism. If the virtual satellite is located ahead of the initial plasmoid formation, it observes a pulse-like field compression with the compression rate of more than 10% as well as the bipolar structure of the magnetic field component from northward to southward tilting, when the plasmoid center passes through the satellite location. On the other hand, if it is located behind the plasmoid formation, it observes the unipolar structure of the southward field component. The simulation results are shown to be, both quantitatively and qualitatively, in good agreement with the actual satellite observations. It is demonstrated that the TCR event is the fast reconnection mechanism itself that is seen in the ambient (low-{beta}) magnetic field (magnetotail lobe) region.

  8. Measurements and modelling of fast-ion redistribution due to resonant MHD instabilities in MAST

    NASA Astrophysics Data System (ADS)

    Jones, O. M.; Cecconello, M.; McClements, K. G.; Klimek, I.; Akers, R. J.; Boeglin, W. U.; Keeling, D. L.; Meakins, A. J.; Perez, R. V.; Sharapov, S. E.; Turnyanskiy, M.; the MAST Team

    2015-12-01

    The results of a comprehensive investigation into the effects of toroidicity-induced Alfvén eigenmodes (TAE) and energetic particle modes on the NBI-generated fast-ion population in MAST plasmas are reported. Fast-ion redistribution due to frequency-chirping TAE in the range 50 kHz-100 kHz and frequency-chirping energetic particle modes known as fishbones in the range 20 kHz-50 kHz, is observed. TAE and fishbones are also observed to cause losses of fast ions from the plasma. The spatial and temporal evolution of the fast-ion distribution is determined using a fission chamber, a radially-scanning collimated neutron flux monitor, a fast-ion deuterium alpha spectrometer and a charged fusion product detector. Modelling using the global transport analysis code Transp, with ad hoc anomalous diffusion and fishbone loss models introduced, reproduces the coarsest features of the affected fast-ion distribution in the presence of energetic particle-driven modes. The spectrally and spatially resolved measurements show, however, that these models do not fully capture the effects of chirping modes on the fast-ion distribution.

  9. A fast collocation method for a variable-coefficient nonlocal diffusion model

    NASA Astrophysics Data System (ADS)

    Wang, Che; Wang, Hong

    2017-02-01

    We develop a fast collocation scheme for a variable-coefficient nonlocal diffusion model, for which a numerical discretization would yield a dense stiffness matrix. The development of the fast method is achieved by carefully handling the variable coefficients appearing inside the singular integral operator and exploiting the structure of the dense stiffness matrix. The resulting fast method reduces the computational work from O (N3) required by a commonly used direct solver to O (Nlog ⁡ N) per iteration and the memory requirement from O (N2) to O (N). Furthermore, the fast method reduces the computational work of assembling the stiffness matrix from O (N2) to O (N). Numerical results are presented to show the utility of the fast method.

  10. The Safety Limits Of An Extended Fast: Lessons from a Non-Model Organism

    PubMed Central

    Bertile, Fabrice; Fouillen, Laetitia; Wasselin, Thierry; Maes, Pauline; Le Maho, Yvon; Van Dorsselaer, Alain; Raclot, Thierry

    2016-01-01

    While safety of fasting therapy is debated in humans, extended fasting occurs routinely and safely in wild animals. To do so, food deprived animals like breeding penguins anticipate the critical limit of fasting by resuming feeding. To date, however, no molecular indices of the physiological state that links spontaneous refeeding behaviour with fasting limits had been identified. Blood proteomics and physiological data reveal here that fasting-induced body protein depletion is not unsafe “per se”. Indeed, incubating penguins only abandon their chick/egg to refeed when this state is associated with metabolic defects in glucose homeostasis/fatty acid utilization, insulin production and action, and possible renal dysfunctions. Our data illustrate how the field investigation of “exotic” models can be a unique source of information, with possible biomedical interest. PMID:27991520

  11. Physiological responses and bowling performance during repeated spells of medium-fast bowling.

    PubMed

    Duffield, Rob; Carney, Mitchell; Karppinen, Stuart

    2009-01-01

    The aim of the present study was to investigate the relationship between physiological and performance responses during repeated 6-over fast-bowling spells. Six, first-class, medium-fast bowlers performed 2x6-over spells separated by 45 min of light activity. The 6-over spells were based on the Cricket Australia fast bowling skills test that is a set order of deliveries at a grid-based target. Ball speed, accuracy and full and final 5-m run-up speed were measured on each ball. Nude mass, heart rate, core temperature, capillary blood lactate, pH and glucose, perceptual measures of RPE and muscle soreness (MS) and repeated vertical jump efforts were measured prior to, during and following each spell. Results indicated no decrement (P=0.41) and small effect sizes (d<0.2) in bowling speed (125.7+/-5.1 and 125.4+/-4.5 km.h(-1)) or accuracy (40.4+/-16.1 and 41.6+/-18.0 AU) between spells 1 and 2. No differences (P=0.6-0.8) were present between spells for heart rate, core temperature, lactate, pH, glucose, RPE, MS or vertical jump. Only final 5-m run-up speed showed a large correlation with ball speed (r=0.70), while accuracy and speed were not correlated (r=0.05). In conclusion, repeated 6-over spells in well-trained bowlers results in minimal performance decrement in mild conditions (22 degrees C). As faster bowlers had faster final 5-m run-up speeds, the maintenance of high final 5-m run-up speeds might be important to maintaining bowling speed. Future research should also include a third bowling spell and warmer environmental conditions.

  12. The effect of pantothenate deficiency in mice on their metabolic response to fast and exercise.

    PubMed

    Smith, C M; Narrow, C M; Kendrick, Z V; Steffen, C

    1987-02-01

    The changes in fuel metabolism during fast and exercise were compared to the tissue total CoA levels in mice maintained on pantothenate-deficient and pantothenate-supplemented (control) diets. In nonexercised mice maintained on a pantothenate-deficient diet for 65 to 105 days, the total CoA levels of many tissues were significantly lower than in controls (liver 18%, kidney 23%, spleen 21%, heart 38%, and leg skeletal muscle 66%). However, no differences in total CoA levels in brain or epididymal fat pads were observed. During a 48-hour fast, the total CoA levels increased in the heart and liver of both pantothenate-deficient and control mice (heart 32 and 19%, respectively; liver 39 and 45%, respectively), but the level of total CoA remained lower in the deficient mice. Liver glycogen levels were 17% lower in deficient mice than in controls and liver ketone bodies were 17% higher in pantothenate deficient mice than in controls. Separate groups of mice on deficient and supplemented diets were trained to run to exhaustion. Compared to trained mice on pantothenate-supplemented diets, the trained pantothenate-deficient mice had lower running times until exhaustion, lower body weights, lower liver and muscle glycogen content (even after rest), and elevated liver ketone bodies both during rest and after running. In summary, the pantothenate-deficient mice were unable to maintain normal glycogen stores, but had a normal ketogenic response to fast and exercise in spite of the lower levels of liver total CoA.

  13. Different response of body weight change according to ketonuria after fasting in the healthy obese.

    PubMed

    Kim, Hyeon-Jeong; Joo, Nam-Seok; Kim, Kwang-Min; Lee, Duck-Joo; Kim, Sang-Man

    2012-03-01

    The relationship between obesity and ketonuria is not well-established. We conducted a retrospective observational study to evaluate whether their body weight reduction response differed by the presence of ketonuria after fasting in the healthy obese. We used the data of 42 subjects, who had medical records of initial urinalysis at routine health check-up and follow-up urinalysis in the out-patient clinic, one week later. All subjects in the initial urinalysis showed no ketonuria. However, according to the follow-up urinalysis after three subsequent meals fasts, the patients were divided into a non-ketonuria group and ketonuria group. We compared the data of conventional low-calorie diet programs for 3 months for both groups. Significantly greater reduction of body weight (-8.6 ± 3.6 kg vs -1.1 ± 2.2 kg, P < 0.001), body mass index (-3.16 ± 1.25 kg/m(2) vs -0.43 ± 0.86 kg/m(2), P < 0.001) and waist circumference (-6.92 ± 1.22 vs -2.32 ± 1.01, P < 0.001) was observed in the ketonuria group compared to the non-ketonuria group. Fat mass and lean body mass were also more reduced in the ketonuria group. In addition, serum free fatty acid concentration after intervention in the ketonuria group showed significant more increment than in the non-ketonuria group. The presence of ketonuria after fasting may be a predicting factor of further body weight reduction.

  14. Model reduction for slow–fast stochastic systems with metastable behaviour

    SciTech Connect

    Bruna, Maria; Chapman, S. Jonathan; Smith, Matthew J.

    2014-05-07

    The quasi-steady-state approximation (or stochastic averaging principle) is a useful tool in the study of multiscale stochastic systems, giving a practical method by which to reduce the number of degrees of freedom in a model. The method is extended here to slow–fast systems in which the fast variables exhibit metastable behaviour. The key parameter that determines the form of the reduced model is the ratio of the timescale for the switching of the fast variables between metastable states to the timescale for the evolution of the slow variables. The method is illustrated with two examples: one from biochemistry (a fast-species-mediated chemical switch coupled to a slower varying species), and one from ecology (a predator–prey system). Numerical simulations of each model reduction are compared with those of the full system.

  15. Sucralose Promotes Food Intake through NPY and a Neuronal Fasting Response.

    PubMed

    Wang, Qiao-Ping; Lin, Yong Qi; Zhang, Lei; Wilson, Yana A; Oyston, Lisa J; Cotterell, James; Qi, Yue; Khuong, Thang M; Bakhshi, Noman; Planchenault, Yoann; Browman, Duncan T; Lau, Man Tat; Cole, Tiffany A; Wong, Adam C N; Simpson, Stephen J; Cole, Adam R; Penninger, Josef M; Herzog, Herbert; Neely, G Gregory

    2016-07-12

    Non-nutritive sweeteners like sucralose are consumed by billions of people. While animal and human studies have demonstrated a link between synthetic sweetener consumption and metabolic dysregulation, the mechanisms responsible remain unknown. Here we use a diet supplemented with sucralose to investigate the long-term effects of sweet/energy imbalance. In flies, chronic sweet/energy imbalance promoted hyperactivity, insomnia, glucose intolerance, enhanced sweet taste perception, and a sustained increase in food and calories consumed, effects that are reversed upon sucralose removal. Mechanistically, this response was mapped to the ancient insulin, catecholamine, and NPF/NPY systems and the energy sensor AMPK, which together comprise a novel neuronal starvation response pathway. Interestingly, chronic sweet/energy imbalance promoted increased food intake in mammals as well, and this also occurs through an NPY-dependent mechanism. Together, our data show that chronic consumption of a sweet/energy imbalanced diet triggers a conserved neuronal fasting response and increases the motivation to eat.

  16. Black P/graphene hybrid: A fast response humidity sensor with good reversibility and stability.

    PubMed

    Phan, Duy-Thach; Park, Inyong; Park, Ah-Ram; Park, Cheol-Min; Jeon, Ki-Joon

    2017-09-05

    Black phosphorus (BP) materials have attracted considerable attention owing to their ultra-sensitive humidity sensing characteristics because of the natural absorption of water (H2O) molecules on the BP surface caused by the specific 2D layer-crystalline structure. On the other hand, the BP-based humidity sensor is less repeatable due to the instability of BP with water molecules and the stability of the sensor is reduced. In this study, this limitation of the BP-based humidity sensor was overcome by preparing a BP/graphene hybrid as a novel humidity sensing nanostructure. The BP/graphene interface improved the stability of the humidity sensor after a few weeks with a linear response within the relative humidity (RH) range of 15-70%. The sensor's response/recovery speed of the humidity sensor was extremely fast within few seconds. The response (S) of the humidity sensor based on the BP/graphene hybrid is 43.4% at RH = 70%. The estimated response and recovery time of the sensor is only 9 and 30 seconds at RH = 70% at room temperature. The experimental investigation reveals that the BP/graphene hybrid not only improves the reversibility and hysteresis factors but also enhances the stability of the humidity sensor.

  17. Fast reconfiguration of high-frequency brain networks in response to surprising changes in auditory input.

    PubMed

    Nicol, Ruth M; Chapman, Sandra C; Vértes, Petra E; Nathan, Pradeep J; Smith, Marie L; Shtyrov, Yury; Bullmore, Edward T

    2012-03-01

    How do human brain networks react to dynamic changes in the sensory environment? We measured rapid changes in brain network organization in response to brief, discrete, salient auditory stimuli. We estimated network topology and distance parameters in the immediate central response period, <1 s following auditory presentation of standard tones interspersed with occasional deviant tones in a mismatch-negativity (MMN) paradigm, using magnetoencephalography (MEG) to measure synchronization of high-frequency (gamma band; 33-64 Hz) oscillations in healthy volunteers. We found that global small-world parameters of the networks were conserved between the standard and deviant stimuli. However, surprising or unexpected auditory changes were associated with local changes in clustering of connections between temporal and frontal cortical areas and with increased interlobar, long-distance synchronization during the 120- to 250-ms epoch (coinciding with the MMN-evoked response). Network analysis of human MEG data can resolve fast local topological reconfiguration and more long-range synchronization of high-frequency networks as a systems-level representation of the brain's immediate response to salient stimuli in the dynamically changing sensory environment.

  18. Observation and modelling of fast ion loss in JET and ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Pinches, S. D.; Kiptily, V. G.; Sharapov, S. E.; Darrow, D. S.; Eriksson, L.-G.; Fahrbach, H.-U.; García-Muñoz, M.; Reich, M.; Strumberger, E.; Werner, A.; ASDEX Upgrade Team; Contributors, JET-EFDA

    2006-10-01

    The confinement of fast particles is of crucial importance for the success of future burning plasma experiments. On JET, the confinement of ion cyclotron resonant frequency (ICRF) accelerated fast hydrogen ions with energies exceeding 5 MeV has been measured using the characteristic γ-rays emitted through their inelastic scattering with carbon impurities, 12C(p,p'γ)12C. Recent experiments have shown a significant decrease in this γ-ray emission (by a factor of 2) during so-called tornado mode activity (core-localized toroidal Alfvén eigenmodes (TAEs) within the q = 1 surface) in sawtoothing plasmas. This is indicative of a significant loss or extensive re-distribution of these (>5 MeV) particles from the plasma core. In this paper, mechanisms responsible for the radial transport and loss of these fast ions are investigated and identified using the HAGIS code, which describes the interaction of the fast ions and the TAE observed. The calculations show that the overlap of wave-particle resonances in phase-space leads to an enhanced radial transport and loss. On both JET and ASDEX Upgrade, new fast ion loss detectors have been installed to further investigate the loss of such particles. On JET, fast ion loss detectors based around an array of Faraday cups and a scintillator probe have been installed as part of a suite of diagnostic enhancements. On ASDEX Upgrade, a new fast ion loss detector has been mounted on the mid-plane manipulator allowing high resolution measurements in pitch angle, energy and time. This has enabled the direct observation of fast ion losses during various magnetohydrodynamics (MHD) phenomena to be studied in detail. Edge localised mode (ELM) induced fast ion losses have been directly observed along with the enhancement of fast ion losses from specific areas of phase-space in the presence of neoclassical tearing modes (NTMs) and TAEs.

  19. Simulating Polar Bear Energetics during a Seasonal Fast Using a Mechanistic Model

    PubMed Central

    Mathewson, Paul D.; Porter, Warren P.

    2013-01-01

    In this study we tested the ability of a mechanistic model (Niche Mapper™) to accurately model adult, non-denning polar bear (Ursus maritimus) energetics while fasting during the ice-free season in the western Hudson Bay. The model uses a steady state heat balance approach, which calculates the metabolic rate that will allow an animal to maintain its core temperature in its particular microclimate conditions. Predicted weight loss for a 120 day fast typical of the 1990s was comparable to empirical studies of the population, and the model was able to reach a heat balance at the target metabolic rate for the entire fast, supporting use of the model to explore the impacts of climate change on polar bears. Niche Mapper predicted that all but the poorest condition bears would survive a 120 day fast under current climate conditions. When the fast extended to 180 days, Niche Mapper predicted mortality of up to 18% for males. Our results illustrate how environmental conditions, variation in animal properties, and thermoregulation processes may impact survival during extended fasts because polar bears were predicted to require additional energetic expenditure for thermoregulation during a 180 day fast. A uniform 3°C temperature increase reduced male mortality during a 180 day fast from 18% to 15%. Niche Mapper explicitly links an animal’s energetics to environmental conditions and thus can be a valuable tool to help inform predictions of climate-related population changes. Since Niche Mapper is a generic model, it can make energetic predictions for other species threatened by climate change. PMID:24019883

  20. Simulating polar bear energetics during a seasonal fast using a mechanistic model.

    PubMed

    Mathewson, Paul D; Porter, Warren P

    2013-01-01

    In this study we tested the ability of a mechanistic model (Niche Mapper™) to accurately model adult, non-denning polar bear (Ursus maritimus) energetics while fasting during the ice-free season in the western Hudson Bay. The model uses a steady state heat balance approach, which calculates the metabolic rate that will allow an animal to maintain its core temperature in its particular microclimate conditions. Predicted weight loss for a 120 day fast typical of the 1990s was comparable to empirical studies of the population, and the model was able to reach a heat balance at the target metabolic rate for the entire fast, supporting use of the model to explore the impacts of climate change on polar bears. Niche Mapper predicted that all but the poorest condition bears would survive a 120 day fast under current climate conditions. When the fast extended to 180 days, Niche Mapper predicted mortality of up to 18% for males. Our results illustrate how environmental conditions, variation in animal properties, and thermoregulation processes may impact survival during extended fasts because polar bears were predicted to require additional energetic expenditure for thermoregulation during a 180 day fast. A uniform 3°C temperature increase reduced male mortality during a 180 day fast from 18% to 15%. Niche Mapper explicitly links an animal's energetics to environmental conditions and thus can be a valuable tool to help inform predictions of climate-related population changes. Since Niche Mapper is a generic model, it can make energetic predictions for other species threatened by climate change.

  1. Renal responses to plasma volume expansion and hyperosmolality in fasting seal pups

    NASA Technical Reports Server (NTRS)

    Ortiz, Rudy M.; Wade, Charles E.; Costa, Daniel P.; Ortiz, C. Leo

    2002-01-01

    Renal responses were quantified in northern elephant seal (Mirounga angustirostris) pups during their postweaning fast to examine their excretory capabilities. Pups were infused with either isotonic (0.9%; n = 8; Iso) or hypertonic (16.7%; n = 7; Hyper) saline via an indwelling catheter such that each pup received 3 mmol NaCl/kg. Diuresis after the infusions was similar in magnitude between the two treatments. Osmotic clearance increased by 37% in Iso and 252% in Hyper. Free water clearance was reduced 3.4-fold in Hyper but was not significantly altered in Iso. Glomerular filtration rate increased 71% in the 24-h period after Hyper, but no net change occurred during the same time after Iso. Natriuresis increased 3.6-fold in Iso and 5.3-fold in Hyper. Iso decreased plasma arginine vasopressin (AVP) and cortisol acutely, whereas Hyper increased plasma and excreted AVP and cortisol. Iso was accompanied by the retention of water and electrolytes, whereas the Hyper load was excreted within 24 h. Natriuresis is attributed to increased filtration and is independent of an increase in atrial natriuretic peptide and decreases in ANG II and aldosterone. Fasting pups appear to have well-developed kidneys capable of both extreme conservation and excretion of Na(+).

  2. Fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus Experiment

    DOE PAGES

    Ren, Y.; Wang, W. X.; LeBlanc, B. P.; ...

    2015-11-03

    In this letter, we report the first observation of the fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus eXperiment [Ono et al., Nucl. Fusion 40, 557 (2000)]. The observation was made in a set of RF-heated L-mode plasmas with toroidal magnetic field of 0.55 T and plasma current of 300 kA. It is observed that electron-scale turbulence spectral power (measured with a high-k collective microwave scattering system) decreases significantly following fast cessation of RF heating that occurs in less than 200 μs. The large drop in the turbulence spectral power has a short time delaymore » of about 1–2 ms relative to the RF cessation and happens on a time scale of 0.5–1 ms, much smaller than the energy confinement time of about 10 ms. Power balance analysis shows a factor of about 2 decrease in electron thermal diffusivity after the sudden drop of turbulence spectral power. Measured small changes in equilibrium profiles across the RF cessation are unlikely able to explain this sudden reduction in the measured turbulence and decrease in electron thermal transport, supported by local linear stability analysis and both local and global nonlinear gyrokinetic simulations. Furthermore, the observations imply that nonlocal flux-driven mechanism may be important for the observed turbulence and electron thermal transport.« less

  3. Renal responses to plasma volume expansion and hyperosmolality in fasting seal pups

    NASA Technical Reports Server (NTRS)

    Ortiz, Rudy M.; Wade, Charles E.; Costa, Daniel P.; Ortiz, C. Leo

    2002-01-01

    Renal responses were quantified in northern elephant seal (Mirounga angustirostris) pups during their postweaning fast to examine their excretory capabilities. Pups were infused with either isotonic (0.9%; n = 8; Iso) or hypertonic (16.7%; n = 7; Hyper) saline via an indwelling catheter such that each pup received 3 mmol NaCl/kg. Diuresis after the infusions was similar in magnitude between the two treatments. Osmotic clearance increased by 37% in Iso and 252% in Hyper. Free water clearance was reduced 3.4-fold in Hyper but was not significantly altered in Iso. Glomerular filtration rate increased 71% in the 24-h period after Hyper, but no net change occurred during the same time after Iso. Natriuresis increased 3.6-fold in Iso and 5.3-fold in Hyper. Iso decreased plasma arginine vasopressin (AVP) and cortisol acutely, whereas Hyper increased plasma and excreted AVP and cortisol. Iso was accompanied by the retention of water and electrolytes, whereas the Hyper load was excreted within 24 h. Natriuresis is attributed to increased filtration and is independent of an increase in atrial natriuretic peptide and decreases in ANG II and aldosterone. Fasting pups appear to have well-developed kidneys capable of both extreme conservation and excretion of Na(+).

  4. Fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus Experiment

    SciTech Connect

    Ren, Y.; Wang, W. X.; LeBlanc, B. P.; Guttenfelder, W.; Kaye, S. M.; Ethier, S.; Mazzucato, E.; Lee, K. C.; Domier, C. W.; Bell, R.; Smith, D. R.; Yuh, H.

    2015-11-03

    In this letter, we report the first observation of the fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus eXperiment [Ono et al., Nucl. Fusion 40, 557 (2000)]. The observation was made in a set of RF-heated L-mode plasmas with toroidal magnetic field of 0.55 T and plasma current of 300 kA. It is observed that electron-scale turbulence spectral power (measured with a high-k collective microwave scattering system) decreases significantly following fast cessation of RF heating that occurs in less than 200 μs. The large drop in the turbulence spectral power has a short time delay of about 1–2 ms relative to the RF cessation and happens on a time scale of 0.5–1 ms, much smaller than the energy confinement time of about 10 ms. Power balance analysis shows a factor of about 2 decrease in electron thermal diffusivity after the sudden drop of turbulence spectral power. Measured small changes in equilibrium profiles across the RF cessation are unlikely able to explain this sudden reduction in the measured turbulence and decrease in electron thermal transport, supported by local linear stability analysis and both local and global nonlinear gyrokinetic simulations. Furthermore, the observations imply that nonlocal flux-driven mechanism may be important for the observed turbulence and electron thermal transport.

  5. Fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus Experiment

    SciTech Connect

    Ren, Y.; Wang, W. X.; LeBlanc, B. P.; Guttenfelder, W.; Kaye, S. M.; Ethier, S.; Mazzucato, E.; Bell, R.; Lee, K. C.; Domier, C. W.; Smith, D. R.; Yuh, H.

    2015-11-15

    In this letter, we report the first observation of the fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus eXperiment [Ono et al., Nucl. Fusion 40, 557 (2000)]. The observation was made in a set of RF-heated L-mode plasmas with toroidal magnetic field of 0.55 T and plasma current of 300 kA. It is observed that electron-scale turbulence spectral power (measured with a high-k collective microwave scattering system) decreases significantly following fast cessation of RF heating that occurs in less than 200 μs. The large drop in the turbulence spectral power has a short time delay of about 1–2 ms relative to the RF cessation and happens on a time scale of 0.5–1 ms, much smaller than the energy confinement time of about 10 ms. Power balance analysis shows a factor of about 2 decrease in electron thermal diffusivity after the sudden drop of turbulence spectral power. Measured small changes in equilibrium profiles across the RF cessation are unlikely able to explain this sudden reduction in the measured turbulence and decrease in electron thermal transport, supported by local linear stability analysis and both local and global nonlinear gyrokinetic simulations. The observations imply that nonlocal flux-driven mechanism may be important for the observed turbulence and electron thermal transport.

  6. Fast and Robust Inversion of Earthquake Source Rupture Process with Applications to Earthquake Emergency Response

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Zhang, Y.

    2010-12-01

    A fast and robust technique for inversion of earthquake source rupture process was developed and applied to some of the recent significant earthquakes worldwide. Since May 2008, source rupture processes of about 20 significant earthquakes worldwide were inverted by using the newly developed technique and the inverted results were timely released on the website within 3 to 5 hours after the occurrence of the earthquakes. These earthquakes included the MW7.8 Wenchuan, Sichuan, earthquake of 12 May 2008, the MW 6.3 L’Aquila, Italy, earthquake of 6 April 2009, the MW 7.0 Haiti earthquake of 12 January 2010, the MW 8.8 Chile earthquake of 27 February, 2010, the MW 6.5 Jiaxian, Taiwan, earthquake of 4 March 2010, the MW7.2 Mexico earthquake of 4 April 2010, the MW7.8 Sumatra earthquake of 6 April 2010, and the MW6.9 Yushu, Qinghai, earthquake of 14 April 2010. It is found that in addition to the usual earthquake source parameters, the fast inverted results of the spatial-temporal rupture process of the earthquake sources provided important information such as the possible disastrous areas and the timely release of these results proved very useful to earthquake emergency response and seismic disaster relief efforts.

  7. Lifespan based indirect response models

    PubMed Central

    Ruixo, Juan Jose Perez

    2012-01-01

    In the field of hematology, several mechanism-based pharmacokinetic-pharmacodynamic models have been developed to understand the dynamics of several blood cell populations under different clinical conditions while accounting for the essential underlying principles of pharmacology, physiology and pathology. In general, a population of blood cells is basically controlled by two processes: the cell production and cell loss. The assumption that each cell exits the population when its lifespan expires implies that the cell loss rate is equal to the cell production rate delayed by the lifespan and justifies the use of delayed differential equations for compartmental modeling. This review is focused on lifespan models based on delayed differential equations and presents the structure and properties of the basic lifespan indirect response (LIDR) models for drugs affecting cell production or cell lifespan distribution. The LIDR models for drugs affecting the precursor cell production or decreasing the precursor cell population are also presented and their properties are discussed. The interpretation of transit compartment models as LIDR models is reviewed as the basis for introducing a new LIDR for drugs affecting the cell lifespan distribution. Finally, the applications and limitations of the LIDR models are discussed. PMID:22212685

  8. Response of genes involved in lipid metabolism in rat epididymal white adipose tissue to different fasting conditions after long-term fructose consumption.

    PubMed

    Li, Jin-Xiu; Ke, Da-Zhi; Yao, Ling; Wang, Shang; Ma, Peng; Liu, Li; Zuo, Guo-Wei; Jiang, Li-Rong; Wang, Jian-Wei

    2017-03-04

    There has been much concern regarding the dietary fructose contributes to the development of metabolic syndrome. High-fructose diet changes the expression of genes involved in lipid metabolism. Levels of a number of hepatic lipogenic enzymes are increased by a high-carbohydrate diet in fasted-refed model rats/mice. Both the white adipose tissue (WAT) and the liver play a key role in the maintenance of nutrient homeostasis. Here, the aim of this study was to analyze the expression of key genes related to lipid metabolism in epididymal WAT (eWAT) in response to different fasting condition after long-term chronic fructose consumption. Rats were fed standard chow supplemented with 10% w/v fructose solution for 5 weeks, and killed after chow-fasting and fructose withdrawal (fasting) or chow-fasting and continued fructose (fructose alone) for 14 h. Blood parameters and the expression of genes involved in fatty acid synthesis (ChREBP, SREBP-1c, FAS, SCD1), triglyceride biosynthesis (DGAT-1, DGAT-2) and lipid mobilization (ATGL, HSL) in eWAT were analyzed. In addition, mRNA levels of PPAR-γ, CD36 and LPL were also detected. As expected, fructose alone increased the mRNA expression of FAS, SCD1, and correspondingly decreased ATGL and HSL mRNA levels. However, ChREBP, DGAT-2, ATGL and HSL mRNA levels restored near to normal while FAS and SCD1 tend to basic level under fasting condition. The mRNA expression of SREBP-1c, PPAR-γ and LPL did not changed at any situations but CD36 mRNA decreased remarkably in fructose alone group. In conclusion, these findings demonstrate that genes involved in lipid metabolism in rat eWAT are varied in response to different fasting conditions after long-term fructose consumption. Copyright © 2017. Published by Elsevier Inc.

  9. Fast-Response and Flexible Nanocrystal-Based Humidity Sensor for Monitoring Human Respiration and Water Evaporation on Skin.

    PubMed

    Kano, Shinya; Kim, Kwangsoo; Fujii, Minoru

    2017-06-23

    We develop a fast-response and flexible nanocrystal-based humidity sensor for real-time monitoring of human activity: respiration and water evaporation on skin. A silicon-nanocrystal film is formed on a polyimide film by spin-coating the colloidal solution and is used as a flexible and humidity-sensitive material in a humidity sensor. The flexible nanocrystal-based humidity sensor shows a high sensitivity; current through the nanocrystal film changes by 5 orders of magnitude in the relative humidity range of 8-83%. The response/recovery time of the sensor is 40 ms. Thanks to the fast response and recovery time, the sensor can monitor human respiration and water evaporation on skin in real time. Due to the flexibility and the fast response/recovery time, the sensor is promising for application in personal health monitoring as well as environmental monitoring.

  10. Unique and shared responses of the gut microbiota to prolonged fasting: a comparative study across five classes of vertebrate hosts.

    PubMed

    Kohl, Kevin D; Amaya, James; Passement, Celeste A; Dearing, M Denise; McCue, Marshall D

    2014-12-01

    Many animals face unpredictable food sources and periods of prolonged fasting, which likely present significant challenges to gut microorganisms. While several studies have demonstrated that fasting impacts the gut microbiota, experiments have not been carried out in a comparative context. We used 16S rRNA gene sequencing to document changes in colonic and cecal microbiomes of animals representing five classes of vertebrates at four time points through prolonged fasting: tilapia, toads, geckos, quail, and mice. We found differences in the starvation-induced changes in the microbiome across host species and across gut regions. Microbial phylogenetic diversity increased as a result of fasting in the colons of fish, toads, and mice, while quail exhibited a decrease in diversity; geckos exhibited no change. Microbial diversity in the cecum decreased in fish and exhibited no change in mice. Alterations in relative abundances of microbial taxa varied across hosts. Fish exhibited the most significant changes due to fasting, while geckos maintained a stable community over 28 days of fasting. We uncovered several shared responses of the microbiota across hosts. For example, all tetrapods exhibited decreases in the abundances of Coprobacillus and Ruminococcus in response to fasting. We also discuss host-mediated physiological mechanisms that may underlie these community changes.

  11. Dose Ramadan Fasting Affects Inflammatory Responses: Evidences for Modulatory Roles of This Unique Nutritional Status via Chemokine Network

    PubMed Central

    Akrami Mohajeri, Fateme; Ahmadi, Zahra; Hassanshahi, Gholamhossein; Akrami Mohajeri, Elham; Ravari, Ali; Ghalebi, Seyed Razi

    2013-01-01

    Objective(s): The impact of fasting in Ramadan as a unique type of nutritional regimen on biochemical and hematological parameters is still an issue of debate. Almost very little is known regarding the regulatory role(s) of this nutritional status on immune responses or inflammation. Materials and Methods: The levels of biochemical parameters were determined using commercial diagnostic kits. Hematological parameters were also examined. We also employed ELISA for detection of CXCL1, CXCL10 and CXCL12 chemokines. The Student-T test was used to compare the values of different parameters obtained in the first and last day of Ramadan fasting by employing SPSS (version 18) software. Results: As our findings demonstrated, there was a markedly difference between before and after Ramadan BMI of the individuals who fast. Our results also revealed that there was a remarkable difference between the levels of total cholesterol, FBS, Triglycerides and LDL before and after Ramadan fasting. Results revealed that among studied hematological parameters only the numbers of platelets were markedly different before and after Ramadan fasting program in individuals who practice fasting. Our results also showed decreased levels of pro-inflammatory CXC chemokines but unaltered levels of homoeostatic ones. Conclusion: The results of this study may reveal that Ramadan fasting is quite safe for normal healthy adults and so very useful in reduction of cholesterol and triglycerides in relation with dyslipidemia. It is also possible to conclude that fasting is important in controlling of inflammation via chemokines. PMID:24570826

  12. Dose Ramadan Fasting Affects Inflammatory Responses: Evidences for Modulatory Roles of This Unique Nutritional Status via Chemokine Network.

    PubMed

    Akrami Mohajeri, Fateme; Ahmadi, Zahra; Hassanshahi, Gholamhossein; Akrami Mohajeri, Elham; Ravari, Ali; Ghalebi, Seyed Razi

    2013-12-01

    The impact of fasting in Ramadan as a unique type of nutritional regimen on biochemical and hematological parameters is still an issue of debate. Almost very little is known regarding the regulatory role(s) of this nutritional status on immune responses or inflammation. The levels of biochemical parameters were determined using commercial diagnostic kits. Hematological parameters were also examined. We also employed ELISA for detection of CXCL1, CXCL10 and CXCL12 chemokines. The Student-T test was used to compare the values of different parameters obtained in the first and last day of Ramadan fasting by employing SPSS (version 18) software. As our findings demonstrated, there was a markedly difference between before and after Ramadan BMI of the individuals who fast. Our results also revealed that there was a remarkable difference between the levels of total cholesterol, FBS, Triglycerides and LDL before and after Ramadan fasting. RESULTS revealed that among studied hematological parameters only the numbers of platelets were markedly different before and after Ramadan fasting program in individuals who practice fasting. Our results also showed decreased levels of pro-inflammatory CXC chemokines but unaltered levels of homoeostatic ones. The results of this study may reveal that Ramadan fasting is quite safe for normal healthy adults and so very useful in reduction of cholesterol and triglycerides in relation with dyslipidemia. It is also possible to conclude that fasting is important in controlling of inflammation via chemokines.

  13. Accurate and fast simulation of channel noise in conductance-based model neurons by diffusion approximation.

    PubMed

    Linaro, Daniele; Storace, Marco; Giugliano, Michele

    2011-03-01

    Stochastic channel gating is the major source of intrinsic neuronal noise whose functional consequences at the microcircuit- and network-levels have been only partly explored. A systematic study of this channel noise in large ensembles of biophysically detailed model neurons calls for the availability of fast numerical methods. In fact, exact techniques employ the microscopic simulation of the random opening and closing of individual ion channels, usually based on Markov models, whose computational loads are prohibitive for next generation massive computer models of the brain. In this work, we operatively define a procedure for translating any Markov model describing voltage- or ligand-gated membrane ion-conductances into an effective stochastic version, whose computer simulation is efficient, without compromising accuracy. Our approximation is based on an improved Langevin-like approach, which employs stochastic differential equations and no Montecarlo methods. As opposed to an earlier proposal recently debated in the literature, our approximation reproduces accurately the statistical properties of the exact microscopic simulations, under a variety of conditions, from spontaneous to evoked response features. In addition, our method is not restricted to the Hodgkin-Huxley sodium and potassium currents and is general for a variety of voltage- and ligand-gated ion currents. As a by-product, the analysis of the properties emerging in exact Markov schemes by standard probability calculus enables us for the first time to analytically identify the sources of inaccuracy of the previous proposal, while providing solid ground for its modification and improvement we present here.

  14. Design and testing of magnetorheological valve with fast force response time and great dynamic force range

    NASA Astrophysics Data System (ADS)

    Kubík, M.; Macháček, O.; Strecker, Z.; Roupec, J.; Mazůrek, I.

    2017-04-01

    The paper deals with design, simulation and experimental testing of a magnetorheological (MR) valve with short response time. The short response time is achieved by a suitable design of an active zone in combination with use of a ferrite material for magnetic circuit. The magneto-static model and the simplified hydraulic model of the MR valve are examined and experimentally verified. The development the MR valve achieves an average response time 4.1 ms and the maximum dynamic force range of eight.

  15. A Mixed Effects Randomized Item Response Model

    ERIC Educational Resources Information Center

    Fox, J.-P.; Wyrick, Cheryl

    2008-01-01

    The randomized response technique ensures that individual item responses, denoted as true item responses, are randomized before observing them and so-called randomized item responses are observed. A relationship is specified between randomized item response data and true item response data. True item response data are modeled with a (non)linear…

  16. Potentiation of Hormonal Responses to Hemorrhage and Fasting, but not Hypoglycemia in Conscious Adrenalectomized Rats

    NASA Technical Reports Server (NTRS)

    Darlington, Daniel N.; Keil, Lanny C.; Dallman, Mary F.

    1989-01-01

    Bilateral adrenalectomy (ADRX) in rats removes the source of two major stress-responsive hormones, corticosterone and epinephrine. To test how ADRX rats with-stand stress, we performed the following experiments in adult male rats provided with indwelling femoral arterial and venous cannulae and either ADRX or sham-adrenalectomized (Sham) 3 days later and given 0.5% NaCl to drink. Five to 6 days after adrenal surgery the rats were studied after either a 15 ml/kg.5 min hemorrhage or after an overnight fast followed by insulin-induced hypoglycemia. In fed unstressed ADRX rats, basal mean arterial blood pressure was slightly decreased; heart rate was increased; blood volume, vasopressin, and oxytocin concentrations were not different from sham values; and renin and norepinephrine were significantly elevated. The recovery of arterial pressure after hemorrhage in the ADRX rats was similar to that in the sham group over a 5-h period; however, the responses of vasopressin and oxytocin were significantly greater, and those of renin and norepinephrine were markedly potentiated in the ADRX group. Heart rate recovered faster in the ADRX group and was elevated, compared to the sham value, for most of the 5-h period. Restitution of blood volume was attenuated in the ADRX group, although the restitution of plasma protein was not different between the groups. A significant difference in the change in plasma osmolality between groups after hemorrhage may account for the attenuated restitution of blood volume. After an overnight fast, which reduced blood volume in both groups of rats, the plasma renin concentration rose still further in ADRX rats; the differences in other measured variables observed between fed ADRX and sham groups remained the same. The insulin-induced 50% decrease in glucose caused minor effects on arterial blood pressure and heart rate and occasioned responses in renin and norepinephrine of similar magnitudes in the two groups. We conclude that in the absence of

  17. Simulation of response functions of fast neutron sensors and development of thin neutron silicon sensor.

    PubMed

    Takada, Masashi; Nakamura, Takashi; Matsuda, Mikihiko; Nunomiya, Tomoya

    2014-10-01

    On radiation detection using silicon sensor, signals are produced from collected charges in a depletion layer; however, for high-energy particles, this depletion layer is extended due to funnelling phenomenon. The lengths of charge collection were experimentally obtained from proton peak energies in measured pulse-heights. The length is extended with increasing proton energy of up to 6 MeV, and then, is constant over 6 MeV. The response functions of fast neutron sensors were simulated for 5- and 15-MeV monoenergetic and (252)Cf neutron sources using the Monte Carlo N-Particle eXtended code. The simulation results agree well with the experimental ones, including the effect of funnelling phenomenon. In addition, a thin silicon sensor was developed for a new real-time personal neutron dosemeter. Photon sensitivity is vanishingly smaller than neutron one by a factor of 5×10(-4).

  18. Shock-tube calibration of a fast-response pressure transducer

    NASA Technical Reports Server (NTRS)

    Chung, Kung-Ming; Lu, Frank K.

    1990-01-01

    The sensitivity of a miniature fast-response piezoresistive pressure transducer determined dynamically was found to be slightly higher than that determined statically. Thus, mean pressures in a turbulent or unsteady flowfield that are measured using statically-calibrated pressure transducers would be slightly above true values. Unsteady pressure measurements to obtain space-time correlations and spectra can, however, be properly performed if the slight error is acceptable. These measurements are, obviously, subjected to limitations imposed by the bandwidth and the spatial resolution of the transducer. The noise spectrum revealed that the noise is predominantly above the transducer's resonant frequency. Filtering to improve the signal-to-noise ratio is particularly necessary when using the transducers at their low range. Transducer drift increases the signal-to-noise ratio and can adversely affect mean measurements.

  19. A fast response hydrogen sensor with Pd metallic grating onto a fiber's end-face

    NASA Astrophysics Data System (ADS)

    Yan, Haitao; Zhao, Xiaoyan; Zhang, Chao; Li, Qiu-Ze; Cao, Jingxiao; Han, Dao-Fu; Hao, Hui; Wang, Ming

    2016-01-01

    We demonstrated an integrated hydrogen sensor with Pd metallic grating fabricated on a fiber end-face. The grating consists of three thin metal layers in stacks, Au, WO3 and Pd. The WO3 is used as a waveguide layer between the Pd and Au layer. The Pd layer is etched by using a focused ion beam (FIB) method, forming a Pd metallic grating with period of 450 nm. The sensor is experimentally exposed to hydrogen gas environment. Changing the concentration from 0% to 4% which is the low explosive limit (LEL), the resonant wavelength measured from the reflection experienced 28.10 nm spectral changes in the visible range. The results demonstrated that the sensor is sensitive for hydrogen detection and it has fast response and low temperature effect.

  20. A new fast response instrument for measuring total water content from aircraft

    NASA Astrophysics Data System (ADS)

    Nicholls, S.; Leighton, J.; Barker, R.

    1990-10-01

    A device for measuring the total water content of a parcel of air from an aircraft has been developed. The total water of a parcel of air is a conserved quantity, independent of phase changes, provided there is no transport of water through the parcel boundaries. Current airborne hygrometers normally attempt to measure the water content in individual phases and the presence of other phases invariably influences the quality of the data. However, any liquid water or ice entering this new probe is efficiently evaporated and the resultant water vapor measured using a Lyman-alpha hygrometer. In airborne trials the device was calibrated against a cooled-mirror dewpoint device. Runs were conducted in warm stratocumulus tops, through small cumulus, in mixed-phase precipitation and cirrus cloud. In all cases the device was found to produce high quality, fast response data.

  1. Modeling of fast neutral-beam-generated ions and rotation effects on RWM stability in DIII-D plasmas

    SciTech Connect

    Turco, Francesca; Turnbull, Alan D.; Hanson, Jeremy M.; Navratil, Gerald A.

    2015-10-15

    Here, validation results for the MARS-K code for DIII-D equilibria, predict that the absence of fast Neutral Beam (NB) generated ions leads to a plasma response ~40–60% higher than in NB-sustained H-mode plasmas when the no-wall βN limit is reached. In a βN scan, the MARS-K model with thermal and fast-ions, reproduces the experimental measurements above the no-wall limit, except at the highest βN where the phase of the plasma response is overestimated. The dependencies extrapolate unfavorably to machines such as ITER with smaller fast ion fractions since elevated responses in the absence of fast ions indicate the potential onset of a resistive wall mode (RWM). The model was also tested for the effects of rotation at high βN, and recovers the measured response even when fast-ions are neglected, reversing the effect found in lower βN cases, but consistent with the higher βN results above the no-wall limit. The agreement in the response amplitude and phase for the rotation scan is not as good, and additional work will be needed to reproduce the experimental trends. In the case of current-driven instabilities, the magnetohydrodynamic spectroscopy system used to measure the plasma response reacts differently from that for pressure driven instabilities: the response amplitude remains low up to ~93% of the current limit, showing an abrupt increase only in the last ~5% of the current ramp. This makes it much less effective as a diagnostic for the approach to an ideal limit. However, the mode structure of the current driven RWM extends radially inwards, consistent with that in the pressure driven case for plasmas with qedge~2. This suggests that previously developed RWM feedback techniques together with the additional optimizations that enabled qedge~2 operation, can be applied to control of both current-driven and pressure-driven modes at high βN.

  2. Modeling of fast neutral-beam-generated ions and rotation effects on RWM stability in DIII-D plasmas

    DOE PAGES

    Turco, Francesca; Turnbull, Alan D.; Hanson, Jeremy M.; ...

    2015-10-15

    Here, validation results for the MARS-K code for DIII-D equilibria, predict that the absence of fast Neutral Beam (NB) generated ions leads to a plasma response ~40–60% higher than in NB-sustained H-mode plasmas when the no-wall βN limit is reached. In a βN scan, the MARS-K model with thermal and fast-ions, reproduces the experimental measurements above the no-wall limit, except at the highest βN where the phase of the plasma response is overestimated. The dependencies extrapolate unfavorably to machines such as ITER with smaller fast ion fractions since elevated responses in the absence of fast ions indicate the potential onsetmore » of a resistive wall mode (RWM). The model was also tested for the effects of rotation at high βN, and recovers the measured response even when fast-ions are neglected, reversing the effect found in lower βN cases, but consistent with the higher βN results above the no-wall limit. The agreement in the response amplitude and phase for the rotation scan is not as good, and additional work will be needed to reproduce the experimental trends. In the case of current-driven instabilities, the magnetohydrodynamic spectroscopy system used to measure the plasma response reacts differently from that for pressure driven instabilities: the response amplitude remains low up to ~93% of the current limit, showing an abrupt increase only in the last ~5% of the current ramp. This makes it much less effective as a diagnostic for the approach to an ideal limit. However, the mode structure of the current driven RWM extends radially inwards, consistent with that in the pressure driven case for plasmas with qedge~2. This suggests that previously developed RWM feedback techniques together with the additional optimizations that enabled qedge~2 operation, can be applied to control of both current-driven and pressure-driven modes at high βN.« less

  3. Development of a fast sampling system for estimation of impulse responses of mobile radio channels

    NASA Astrophysics Data System (ADS)

    Melancon, Pierre

    1994-07-01

    This paper describes the features of measurement equipment developed to measure impulse response estimates of mobile radio channels in less than a ms per measurement. The development of such equipment was required to measure mobile radio channels in realistic operating scenarios, in a normal sized vehicle moving at typical speeds in different environments. Up to speeds of 70 km/hr, the measurement period is short enough to assume the equipment is measuring the same channel during the whole sampling interval. AT the transmitter end of the measurement system, a wideband signal (10 MHz) is produced by modulating a carrier frequency with a 511 bit pseudo random sequence at 5 Mb/s and transmitted through the radio channel. The received signal is down-converted to 70 MHz and demodulated by a complex demodulator. The quadrature baseband signals at the demodulator outputs are then filtered and sampled at high speed by two fast digitizers. During this process, the data are stored in large memory banks to allow a fast sampling rate during a long period of time. Data are transferred to laser disks for further processing in the laboratory. Impulse response of radio channels are estimated by performing a software correlation between a measurement system back to back reference and real time measurements. A minivan was modified to hold the receiver, digitizers, memory banks and the computer. A shaft encoder was attached to its rear left wheel to trigger measurements while moving. Features of the system are discussed along with the effects of data block length, signal to noise ratio, sampling rate, memory size and phase stability on the design of the measurement equipment. Finally, some measurement results are presented and discussed.

  4. Jobs and Economic Development Impact (JEDI) User Reference Guide: Fast Pyrolysis Biorefinery Model

    SciTech Connect

    Zhang, Yimin; Goldberg, Marshall

    2015-02-01

    This guide -- the JEDI Fast Pyrolysis Biorefinery Model User Reference Guide -- was developed to assist users in operating and understanding the JEDI Fast Pyrolysis Biorefinery Model. The guide provides information on the model's underlying methodology, as well as the parameters and data sources used to develop the cost data utilized in the model. This guide also provides basic instruction on model add-in features and a discussion of how the results should be interpreted. Based on project-specific inputs from the user, the JEDI Fast Pyrolysis Biorefinery Model estimates local (e.g., county- or state-level) job creation, earnings, and output from total economic activity for a given fast pyrolysis biorefinery. These estimates include the direct, indirect and induced economic impacts to the local economy associated with the construction and operation phases of biorefinery projects.Local revenue and supply chain impacts as well as induced impacts are estimated using economic multipliers derived from the IMPLAN software program. By determining the local economic impacts and job creation for a proposed biorefinery, the JEDI Fast Pyrolysis Biorefinery Model can be used to field questions about the added value biorefineries might bring to a local community.

  5. Fast Responsive and Controllable Liquid Transport on a Magnetic Fluid/Nanoarray Composite Interface.

    PubMed

    Tian, Dongliang; Zhang, Na; Zheng, Xi; Hou, Guanglei; Tian, Ye; Du, Yi; Jiang, Lei; Dou, Shi Xue

    2016-06-28

    Controllable liquid transport on surface is expected to occur by manipulating the gradient of surface tension/Laplace pressure and external stimuli, which has been intensively studied on solid or liquid interface. However, it still faces challenges of slow response rate, and uncontrollable transport speed and direction. Here, we demonstrate fast responsive and controllable liquid transport on a smart magnetic fluid/nanoarray interface, i.e., a composite interface, via modulation of an external magnetic field. The wettability of the composite interface to water instantaneously responds to gradient magnetic field due to the magnetically driven composite interface gradient roughness transition that takes place within a millisecond, which is at least 1 order of magnitude faster than that of other responsive surfaces. A water droplet can follow the motion of the gradient composite interface structure as it responds to the gradient magnetic field motion. Moreover, the water droplet transport direction can be controlled by modulating the motion direction of the gradient magnetic field. The composite interface can be used as a pump for the transport of immiscible liquids and other objects in the microchannel, which suggests a way to design smart interface materials and microfluidic devices.

  6. Scalable complexity-distortion model for fast motion estimation

    NASA Astrophysics Data System (ADS)

    Yi, Xiaoquan; Ling, Nam

    2005-07-01

    Recently established international video coding standard H.264/AVC and the upcoming standard on scalable video coding (SVC) bring part of the solution to high compression ratio requirement and heterogeneity requirement. However, these algorithms have unbearable complexities for real-time encoding. Therefore, there is an important challenge to reduce encoding complexity, preferably in a scalable manner. Motion estimation and motion compensation techniques provide significant coding gain but are the most time-intensive parts in an encoder system. They present tremendous research challenges to design a flexible, rate-distortion optimized, yet computationally efficient encoder, especially for various applications. In this paper, we present a scalable motion estimation framework for complexitydistortion consideration. We propose a new progressive initial search (PIS) method to generate an accurate initial search point, followed by a fast search method, which can greatly benefit from the tighter bounds of the PIS. Such approach offers not only significant speedup but also an optimal distortion performance for a given complexity constrain. We analyze the relationship between computational complexity and distortion (C-D) through probabilistic distance measure extending from the complexity and distortion theory. A configurable complexity quantization parameter (Q) is introduced. Simulation results demonstrate that the proposed scalable complexity-distortion framework enables video encoder to conveniently adjust its complexity while providing best possible services.

  7. Only signaling modules that discriminate sharply between stimulatory and nonstimulatory inputs require basal signaling for fast cellular responses

    NASA Astrophysics Data System (ADS)

    Artomov, Mykyta; Kardar, Mehran; Chakraborty, Arup K.

    2010-09-01

    In many types of cells, binding of molecules to their receptors enables cascades of intracellular chemical reactions to take place (signaling). However, a low level of signaling also occurs in most unstimulated cells. Such basal signaling in resting cells can have many functions, one of which is that it is thought to be required for fast cellular responses to external stimuli. A mechanistic understanding of why this is true and which features of cellular signaling networks make basal signaling necessary for fast responses is unknown. We address this issue by obtaining the time required for activation of common types of cell signaling modules with and without basal signaling. Our results show that the absence of basal signaling does not have any dramatic effects on the response time for signaling modules that exhibit a graded response to increasing stimulus levels. In sharp contrast, signaling modules that exhibit sharp dose-response curves which discriminate sensitively between stimuli to which the cell needs to respond and low-grade inputs (or stochastic noise) require basal signaling for fast cellular responses. In such cases, we find that an optimal level of basal signaling balances the requirements for fast cellular responses while minimizing spurious activation without appropriate stimulation.

  8. One-Dimensional Fast Transient Simulator for Modeling Cadmium Sulfide/Cadmium Telluride Solar Cells

    NASA Astrophysics Data System (ADS)

    Guo, Da

    Solar energy, including solar heating, solar architecture, solar thermal electricity and solar photovoltaics, is one of the primary alternative energy sources to fossil fuel. Being one of the most important techniques, significant research has been conducted in solar cell efficiency improvement. Simulation of various structures and materials of solar cells provides a deeper understanding of device operation and ways to improve their efficiency. Over the last two decades, polycrystalline thin-film Cadmium-Sulfide and Cadmium-Telluride (CdS/CdTe) solar cells fabricated on glass substrates have been considered as one of the most promising candidate in the photovoltaic technologies, for their similar efficiency and low costs when compared to traditional silicon-based solar cells. In this work a fast one dimensional time-dependent/steady-state drift-diffusion simulator, accelerated by adaptive non-uniform mesh and automatic time-step control, for modeling solar cells has been developed and has been used to simulate a CdS/CdTe solar cell. These models are used to reproduce transients of carrier transport in response to step-function signals of different bias and varied light intensity. The time-step control models are also used to help convergence in steady-state simulations where constrained material constants, such as carrier lifetimes in the order of nanosecond and carrier mobility in the order of 100 cm2/Vs, must be applied.

  9. Homology Modeling a Fast Tool for Drug Discovery: Current Perspectives

    PubMed Central

    Vyas, V. K.; Ukawala, R. D.; Ghate, M.; Chintha, C.

    2012-01-01

    Major goal of structural biology involve formation of protein-ligand complexes; in which the protein molecules act energetically in the course of binding. Therefore, perceptive of protein-ligand interaction will be very important for structure based drug design. Lack of knowledge of 3D structures has hindered efforts to understand the binding specificities of ligands with protein. With increasing in modeling software and the growing number of known protein structures, homology modeling is rapidly becoming the method of choice for obtaining 3D coordinates of proteins. Homology modeling is a representation of the similarity of environmental residues at topologically corresponding positions in the reference proteins. In the absence of experimental data, model building on the basis of a known 3D structure of a homologous protein is at present the only reliable method to obtain the structural information. Knowledge of the 3D structures of proteins provides invaluable insights into the molecular basis of their functions. The recent advances in homology modeling, particularly in detecting and aligning sequences with template structures, distant homologues, modeling of loops and side chains as well as detecting errors in a model contributed to consistent prediction of protein structure, which was not possible even several years ago. This review focused on the features and a role of homology modeling in predicting protein structure and described current developments in this field with victorious applications at the different stages of the drug design and discovery. PMID:23204616

  10. Homology modeling a fast tool for drug discovery: current perspectives.

    PubMed

    Vyas, V K; Ukawala, R D; Ghate, M; Chintha, C

    2012-01-01

    Major goal of structural biology involve formation of protein-ligand complexes; in which the protein molecules act energetically in the course of binding. Therefore, perceptive of protein-ligand interaction will be very important for structure based drug design. Lack of knowledge of 3D structures has hindered efforts to understand the binding specificities of ligands with protein. With increasing in modeling software and the growing number of known protein structures, homology modeling is rapidly becoming the method of choice for obtaining 3D coordinates of proteins. Homology modeling is a representation of the similarity of environmental residues at topologically corresponding positions in the reference proteins. In the absence of experimental data, model building on the basis of a known 3D structure of a homologous protein is at present the only reliable method to obtain the structural information. Knowledge of the 3D structures of proteins provides invaluable insights into the molecular basis of their functions. The recent advances in homology modeling, particularly in detecting and aligning sequences with template structures, distant homologues, modeling of loops and side chains as well as detecting errors in a model contributed to consistent prediction of protein structure, which was not possible even several years ago. This review focused on the features and a role of homology modeling in predicting protein structure and described current developments in this field with victorious applications at the different stages of the drug design and discovery.

  11. Fast correspondences for statistical shape models of brain structures

    NASA Astrophysics Data System (ADS)

    Bernard, Florian; Vlassis, Nikos; Gemmar, Peter; Husch, Andreas; Thunberg, Johan; Goncalves, Jorge; Hertel, Frank

    2016-03-01

    Statistical shape models based on point distribution models are powerful tools for image segmentation or shape analysis. The most challenging part in the generation of point distribution models is the identification of corresponding landmarks among all training shapes. Since in general the true correspondences are unknown, correspondences are frequently established under the hypothesis that correct correspondences lead to a compact model, which is mostly tackled by continuous optimisation methods. In favour of the prospect of an efficient optimisation, we present a simplified view of the correspondence problem for statistical shape models that is based on point-set registration, the linear assignment problem and mesh fairing. At first, regularised deformable point-set registration is performed and combined with solving the linear assignment problem to obtain correspondences between shapes on a global scale. With that, rough correspondences are established that may not yet be accurate on a local scale. Then, by using a mesh fairing procedure, consensus of the correspondences on a global and local scale among the entire set of shapes is achieved. We demonstrate that for the generation of statistical shape models of deep brain structures, the proposed approach is preferable over existing population-based methods both in terms of a significantly shorter runtime and in terms of an improved quality of the resulting shape model.

  12. Robust and fast nonlinear optimization of diffusion MRI microstructure models.

    PubMed

    Harms, R L; Fritz, F J; Tobisch, A; Goebel, R; Roebroeck, A

    2017-07-15

    Advances in biophysical multi-compartment modeling for diffusion MRI (dMRI) have gained popularity because of greater specificity than DTI in relating the dMRI signal to underlying cellular microstructure. A large range of these diffusion microstructure models have been developed and each of the popular models comes with its own, often different, optimization algorithm, noise model and initialization strategy to estimate its parameter maps. Since data fit, accuracy and precision is hard to verify, this creates additional challenges to comparability and generalization of results from diffusion microstructure models. In addition, non-linear optimization is computationally expensive leading to very long run times, which can be prohibitive in large group or population studies. In this technical note we investigate the performance of several optimization algorithms and initialization strategies over a few of the most popular diffusion microstructure models, including NODDI and CHARMED. We evaluate whether a single well performing optimization approach exists that could be applied to many models and would equate both run time and fit aspects. All models, algorithms and strategies were implemented on the Graphics Processing Unit (GPU) to remove run time constraints, with which we achieve whole brain dataset fits in seconds to minutes. We then evaluated fit, accuracy, precision and run time for different models of differing complexity against three common optimization algorithms and three parameter initialization strategies. Variability of the achieved quality of fit in actual data was evaluated on ten subjects of each of two population studies with a different acquisition protocol. We find that optimization algorithms and multi-step optimization approaches have a considerable influence on performance and stability over subjects and over acquisition protocols. The gradient-free Powell conjugate-direction algorithm was found to outperform other common algorithms in terms of

  13. Refeeding with a standard diet after a 48-h fast elicits an inflammatory response in the mouse liver.

    PubMed

    Oarada, Motoko; Miki, Takashi; Kohno, Shohei; Sakai, Kanae; Nikawa, Takeshi; Yoneyama, Mitsutoshi; Gonoi, Tohru

    2013-07-01

    Unhealthy eating behaviors increase the risk of metabolic diseases, but the underlying mechanisms are not fully elucidated. Because inflammation contributes to the pathogenesis of metabolic diseases, it is important to understand the effects of unhealthy eating on the inflammatory state. The objective of our present study was to address the effects of a fasting-refeeding regime, a model of irregular eating, on the hepatic inflammatory responses in mouse. The animals were fasted for 48 h and then refed either a standard or low-carbohydrate/high-fat diet. Inflammatory gene expression in the liver was then sequentially measured for the first 17 h after initiation of refeeding. To assess the roles of dietary carbohydrates and toll-like receptor 2 (TLR2) in the refeeding-induced inflammatory changes, gene expression levels in mice refed only carbohydrates (α-corn starch and sucrose) at different doses and in TLR2-deficient mice refed a standard diet were also analyzed. Refeeding with a standard diet increased the liver expression of Tlr2, proinflammatory mediators (Cxcl10, Cxcl1, Cxcl2, Icam-1) and negative regulators of TLR-signaling (A20 and Atf3). These increases were attenuated in mice refed a low-carbohydrate/high-fat diet. Refeeding only α-corn starch and sucrose also increased the expression of these inflammatory pathway genes depending on the doses. TLR2 deficiency significantly attenuated the refeeding-induced increase in the liver expression of Cxcl10, Cxcl1, Icam-1 and A20. These findings suggest that an irregular eating behavior can elicit a liver inflammatory response, which is at least partly mediated by TLR2, and that dietary carbohydrates play critical roles in this process. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. One-dimensional biomass fast pyrolysis model with reaction kinetics integrated in an Aspen Plus Biorefinery Process Model

    DOE PAGES

    Humbird, David; Trendewicz, Anna; Braun, Robert; ...

    2017-01-12

    A biomass fast pyrolysis reactor model with detailed reaction kinetics and one-dimensional fluid dynamics was implemented in an equation-oriented modeling environment (Aspen Custom Modeler). Portions of this work were detailed in previous publications; further modifications have been made here to improve stability and reduce execution time of the model to make it compatible for use in large process flowsheets. The detailed reactor model was integrated into a larger process simulation in Aspen Plus and was stable for different feedstocks over a range of reactor temperatures. Sample results are presented that indicate general agreement with experimental results, but with higher gasmore » losses caused by stripping of the bio-oil by the fluidizing gas in the simulated absorber/condenser. Lastly, this integrated modeling approach can be extended to other well-defined, predictive reactor models for fast pyrolysis, catalytic fast pyrolysis, as well as other processes.« less

  15. High temperature fast response pressure probe for use in liquid metal droplet dispensers

    NASA Astrophysics Data System (ADS)

    Rollinger, B.; Mansour, M.; Abhari, R. S.

    2012-06-01

    A miniature fast response high temperature pressure probe, with demonstrated use in liquid metals up to 255 °C (528 K), has been developed. Innovative packaging technologies have been applied to integrate a conventional piezoresistive silicon pressure sensor into the probe, without the need of an auxiliary water-cooling system. In situ static calibrations are used to verify the linearity of the pressure signal and the stability of the pressure sensitivity (0.5% standard deviation over 70 min at 255 °C). Dynamic calibration, completed in an air shock tube facility, yields the probe's natural frequency. This frequency, when corrected for probe operation in liquid tin, is found to be 100 kHz. The reliability and accuracy of the probe is assessed by mounting it in a tin droplet dispenser for use in an extreme ultraviolet light source. Droplet dispensers typically include an excitation mechanism, which can be based on the generation of acoustic pressure waves to impose a desired droplet frequency. The probe accuracy is verified by the comparison of pressure measurements with laser Doppler vibrometry measurements of the pressure generating structure. A reference pressure measurement, conducted at representative conditions, shows a complex frequency response, with peaks distributed over three orders of magnitude and maximum amplitude of 440 mbar. Time variance of the excitation mechanism due to thermal transients is studied by monitoring the pressure response during operation. Finally, the linearity of the excitation system, with respect to the excitation amplitude, is verified by response measurements. In conclusion, the developed probe is capable of characterizing the excitation mechanism of a liquid metal droplet dispenser. Additionally, real-time monitoring of the performance of the excitation system during long-term operation is possible.

  16. Fast weak-lensing simulations with halo model

    NASA Astrophysics Data System (ADS)

    Giocoli, Carlo; Di Meo, Sandra; Meneghetti, Massimo; Jullo, Eric; de la Torre, Sylvain; Moscardini, Lauro; Baldi, Marco; Mazzotta, Pasquale; Metcalf, R. Benton

    2017-09-01

    Full ray-tracing maps of gravitational lensing, constructed from N-body simulations, represent a fundamental tool to interpret present and future weak-lensing data. However, the limitation of computational resources and storage capabilities severely restricts the number of realizations that can be performed in order to accurately sample both the cosmic shear models and covariance matrices. In this paper, we present a halo model formalism for weak gravitational lensing that alleviates these issues by producing weak-lensing mocks at a reduced computational cost. Our model takes as input the halo population within a desired light cone and the linear power spectrum of the underlined cosmological model. We examine the contribution given by the presence of substructures within haloes to the cosmic shear power spectrum and quantify it to the percent level. Our method allows us to reconstruct high-resolution convergence maps, for any desired source redshifts, of light cones that realistically trace the matter density distribution in the universe, account for masked area and sample selections. We compare our analysis on the same large-scale structures constructed using ray-tracing techniques and find very good agreements in both the linear and non-linear regimes up to few percent levels. The accuracy and speed of our method demonstrate the potential of our halo model for weak-lensing statistics and the possibility to generate a large sample of convergence maps for different cosmological models as needed for the analysis of large galaxy redshift surveys.

  17. Modeling rate sensitivity of exercise transient responses to limb motion.

    PubMed

    Yamashiro, Stanley M; Kato, Takahide

    2014-10-01

    Transient responses of ventilation (V̇e) to limb motion can exhibit predictive characteristics. In response to a change in limb motion, a rapid change in V̇e is commonly observed with characteristics different than during a change in workload. This rapid change has been attributed to a feed-forward or adaptive response. Rate sensitivity was explored as a specific hypothesis to explain predictive V̇e responses to limb motion. A simple model assuming an additive feed-forward summation of V̇e proportional to the rate of change of limb motion was studied. This model was able to successfully account for the adaptive phase correction observed during human sinusoidal changes in limb motion. Adaptation of rate sensitivity might also explain the reduction of the fast component of V̇e responses previously reported following sudden exercise termination. Adaptation of the fast component of V̇e response could occur by reduction of rate sensitivity. Rate sensitivity of limb motion was predicted by the model to reduce the phase delay between limb motion and V̇e response without changing the steady-state response to exercise load. In this way, V̇e can respond more quickly to an exercise change without interfering with overall feedback control. The asymmetry between responses to an incremental and decremental ramp change in exercise can also be accounted for by the proposed model. Rate sensitivity leads to predicted behavior, which resembles responses observed in exercise tied to expiratory reserve volume. Copyright © 2014 the American Physiological Society.

  18. Case-based reasoning(CBR) model for ultra-fast cooling in plate mill

    NASA Astrophysics Data System (ADS)

    Hu, Xiao; Wang, Zhaodong; Wang, Guodong

    2014-11-01

    New generation thermo-mechanical control process(TMCP) based on ultra-fast cooling is being widely adopted in plate mill to product high-performance steel material at low cost. Ultra-fast cooling system is complex because of optimizing the temperature control error generated by heat transfer mathematical model and process parameters. In order to simplify the system and improve the temperature control precision in ultra-fast cooling process, several existing models of case-based reasoning(CBR) model are reviewed. Combining with ultra-fast cooling process, a developed R5 CBR model is proposed, which mainly improves the case representation, similarity relation and retrieval module. Certainty factor is defined in semantics memory unit of plate case which provides not only internal data reliability but also product performance reliability. Similarity relation is improved by defined power index similarity membership function. Retrieval process is simplified and retrieval efficiency is improved apparently by windmill retrieval algorithm. The proposed CBR model is used for predicting the case of cooling strategy and its capability is superior to traditional process model. In order to perform comprehensive investigations on ultra-fast cooling process, different steel plates are considered for the experiment. The validation experiment and industrial production of proposed CBR model are carried out, which demonstrated that finish cooling temperature(FCT) error is controlled within ±25°C and quality rate of product is more than 97%. The proposed CBR model can simplify ultra-fast cooling system and give quality performance for steel product.

  19. Failure of the feeding response to fasting in carnitine-deficient juvenile visceral steatosis (JVS) mice: involvement of defective acyl-ghrelin secretion and enhanced corticotropin-releasing factor signaling in the hypothalamus.

    PubMed

    Sakoguchi, Takeo; Horiuchi, Masahisa; Asakawa, Akihiro; Ushikai, Miharu; Yoshida, Goichiro; Fujimiya, Mineko; Kato, Ikuo; Nakazato, Masamitsu; Takeuchi, Toru; Saheki, Takeyori; Inui, Akio

    2009-11-01

    Carnitine-deficient juvenile visceral steatosis (JVS) mice, suffering from fatty acid metabolism abnormalities, have reduced locomotor activity after fasting. We examined whether JVS mice exhibit specific defect in the feeding response to fasting, a key process of anti-famine homeostatic mechanism. Carnitine-deficient JVS mice showed grossly defective feeding response to 24 h-fasting, with almost no food intake in the first 4 h, in marked contrast to control animals. JVS mice also showed defective acyl-ghrelin response to fasting, less suppressed leptin, and seemingly normal corticotropin-releasing factor (CRF) expression in the hypothalamus despite markedly increased plasma corticosterone. The anorectic response was ameliorated by intraperitoneal administration of carnitine or acyl-ghrelin, with decreased CRF expression. Intracerebroventricular treatment of CRF type 2 receptor antagonist, anti-sauvagine-30, recovered the defective feeding response of 24 h-fasted JVS mice. The defective feeding response to fasting in carnitine-deficient JVS mice is due to the defective acyl-ghrelin and enhanced CRF signaling in the hypothalamus through fatty acid metabolism abnormalities. In this animal model, carnitine normalizes the feeding response through an inhibition of CRF.

  20. Response of slow and fast muscle to hypothyroidism: maximal shortening velocity and myosin isoforms

    NASA Technical Reports Server (NTRS)

    Caiozzo, V. J.; Herrick, R. E.; Baldwin, K. M.

    1992-01-01

    This study examined both the shortening velocity and myosin isoform distribution of slow- (soleus) and fast-twitch (plantaris) skeletal muscles under hypothyroid conditions. Adult female Sprague-Dawley rats were randomly assigned to one of two groups: control (n = 7) or hypothyroid (n = 7). In both muscles, the relative contents of native slow myosin (SM) and type I myosin heavy chain (MHC) increased in response to the hypothyroid treatment. The effects were such that the hypothyroid soleus muscle expressed only the native SM and type I MHC isoforms while repressing native intermediate myosin and type IIA MHC. In the plantaris, the relative content of native SM and type I MHC isoforms increased from 5 to 13% and from 4 to 10% of the total myosin pool, respectively. Maximal shortening velocity of the soleus and plantaris as measured by the slack test decreased by 32 and 19%, respectively, in response to hypothyroidism. In contrast, maximal shortening velocity as estimated by force-velocity data decreased only in the soleus (-19%). No significant change was observed for the plantaris.

  1. A new fast-response, real-time and continuous dissolved methane sensor.

    NASA Astrophysics Data System (ADS)

    Triest, Jack; Chappellaz, Jerome; Grilli, Roberto

    2016-04-01

    Continuous high resolution profiling of dissolved methane down to ocean depths is made possible as a result of technological innovations achieved in the search for the oldest ice in Antarctica. Testing for the SUBGLACIOR probe, which is being developed at LGGE in response to the IPICS >1Ma old ice challenge, showed that much of the technology to extract the trapped gases from ice can also significantly improve the extraction and analysis of dissolved methane from the sea compared to current available sensors. To develop this potential, an oceanographic instrument 'SubOcean' was built and deployed over a gas-hydrate zone of western Svalbard, in collaboration with CAGE, in October 2015. Continuous measurements to depths of 400 m were made over three days resulting in high-resolution 3D profiles. The very fast response time of the sensor allows to display the in-situ measurements in real-time and compare them directly to data from other instrumentation aboard the ship whilst underway. The sensor contains a membrane based gas extraction system coupled to a laser spectrometer to provide accurate measurements over a wide concentration range. We will present the overall design of the instrument and highlight how it can help provide new insights into the spatial distribution and flux of methane in the marine environment.

  2. Synthesis of Ce:ZnO nanocomposites: Facile synthesis and fast acetone gas sensing response properties

    NASA Astrophysics Data System (ADS)

    Chen, Haixia; Yu, Hai; Cui, Shu; Xu, Jinghua; Zhang, Yong; Liu, Chengyou

    2017-07-01

    Semiconductor materials are often used as gas sensor. In order to increase the sensitivity of the sensors, rare earths are usually doped to change the properties of the materials. In this paper, it is reported that the Ce:ZnO nanoparticles are synthesized by a simple chemical methods. The gas sensing properties is investigated. UV-Vis is used to investigate the optical properties. X-ray diffraction (XRD) and field emission scanning electronic microscopy (FESEM) are employed to examine the chemical composition and microstructures. It is found that the size of ZnO crystallites is suppressed after doping Ce. When considering a variety of volatile organic compound gas and gas concentration, 2% Ce-doped ZnO nanocomposites is configured as high performance sensors to detect acetone. The fast response times (<2 s) and recovery times (12 s) are obtained. Relatively low working temperature, good repeatability and high sensitivity performances are observed. From the morphology characterizations of the Ce-doped ZnO nanocomposites, it can be found that the increasing of ratio of area to volume to enhanced capability of adsorbing oxygen on the surface. It is proposed that the oxygen species on the surface of ZnO nanocomposites is O-, but O- may play a more important role in improving gas response. The morphology dependent sensing mechanism is proposed.

  3. Response of slow and fast muscle to hypothyroidism: maximal shortening velocity and myosin isoforms

    NASA Technical Reports Server (NTRS)

    Caiozzo, V. J.; Herrick, R. E.; Baldwin, K. M.

    1992-01-01

    This study examined both the shortening velocity and myosin isoform distribution of slow- (soleus) and fast-twitch (plantaris) skeletal muscles under hypothyroid conditions. Adult female Sprague-Dawley rats were randomly assigned to one of two groups: control (n = 7) or hypothyroid (n = 7). In both muscles, the relative contents of native slow myosin (SM) and type I myosin heavy chain (MHC) increased in response to the hypothyroid treatment. The effects were such that the hypothyroid soleus muscle expressed only the native SM and type I MHC isoforms while repressing native intermediate myosin and type IIA MHC. In the plantaris, the relative content of native SM and type I MHC isoforms increased from 5 to 13% and from 4 to 10% of the total myosin pool, respectively. Maximal shortening velocity of the soleus and plantaris as measured by the slack test decreased by 32 and 19%, respectively, in response to hypothyroidism. In contrast, maximal shortening velocity as estimated by force-velocity data decreased only in the soleus (-19%). No significant change was observed for the plantaris.

  4. Nanometal-decorated exfoliated graphite nanoplatelet based glucose biosensors with high sensitivity and fast response.

    PubMed

    Lu, Jue; Do, Inhwan; Drzal, Lawrence T; Worden, Robert M; Lee, Ilsoon

    2008-09-23

    We report the novel fabrication of a highly sensitive, selective, fast responding, and affordable amperometric glucose biosensor using exfoliated graphite nanoplatelets (xGnPs) decorated with Pt and Pd nanoparticles. Nafion was used to solubilize metal-decorated graphite nanoplatelets, and a simple cast method with high content organic solvent (85 wt %) was used to prepare the biosensors. The addition of precious metal nanoparticles such as platinum (Pt) and palladium (Pd) to xGnP increased the electroactive area of the electrode and substantially decreased the overpotential in the detection of hydrogen peroxide. The Pt-xGnP glucose biosensor had a sensitivity of 61.5+/-0.6 microA/(mM x cm(2)) and gave a linear response up to 20 mM. The response time and detection limit (S/N=3) were determined to be 2 s and 1 microM, respectively. Therefore, this novel glucose biosensor based on the Pt nanoparticle coated xGnP is among the best reported to date in both sensing performance and production cost. In addition, the effects of metal nanoparticle loading and the particle size on the biosensor performance were systematically investigated.

  5. Fracture response of several metals to fast heating of samples by intensive X-ray radiation

    NASA Astrophysics Data System (ADS)

    Golubev, Vladimir

    2015-06-01

    Results on studying the fracture response of metals samples in the form of thin disks to fast heating by the intensive pulse of X-ray radiation of a complete spectrum are presented in the paper. The samples of such metals as iron, copper, AMg6 aluminum, VT14 titanium, molybdenum, tungsten, cadmium, lead and zinc were tested. The samples were fixed in the special cartridges that were placed at such distances from the X-ray irradiator where the energy fluxes were 1.38, 0.90 and 0.29 kJ/cm2. The irradiating X-ray pulse was about 2 ns in duration. After testing, the depth of material ablation from a sample front surface and the degree and character of its spall damage were determined. The method of metallographic analysis was used for these purposes. The spectrum data were used for the calculations of samples heating. Numerical calculations of thermomechanical and shock wave loading conditions were made with the use of the equation of state taking into account the process of evaporation. The calculated value of maximum negative pressure in the sample at the coordinate corresponding to the depth of ablation and formation of spallation zones or spall cracks was conventionally accepted as the material resistance to spall fracture in such conditions. The comparison of obtained results with the data on the fracture of examined materials in the conditions of fast heating by the X-ray pulse with a hard spectrum and by the high-current electron beam of an electron pulse generator was conducted.

  6. Fokker-Planck model for collisional loss of fast ions in tokamaks

    NASA Astrophysics Data System (ADS)

    Yavorskij, V.; Goloborod'ko, V.; Schoepf, K.

    2016-11-01

    Modelling of the collisional loss of fast ions from tokamak plasmas is important from the point of view of the impact of fusion alphas and neutral beam injection ions on plasma facing components as well as for the development of diagnostics of fast ion losses [1-3]. This paper develops a Fokker-Planck (FP) method for the assessment of distributions of collisional loss of fast ions as depending on the coordinates of the first wall surface and on the velocities of lost ions. It is shown that the complete 4D drift FP approach for description of fast ions in axisymmetric tokamak plasmas can be reduced to a 2D FP problem for lost ions with a boundary condition delivered by the solution of a 3D boundary value problem for confined ions. Based on this newly developed FP approach the poloidal distribution of neoclassical loss, depending on pitch-angle and energy, of fast ions from tokamak plasma may be examined as well as the contribution of this loss to the signal detected by the scintillator probe may be evaluated. It is pointed out that the loss distributions obtained with the novel FP treatment may serve as an alternative approach with respect to Monte-Carlo models [4, 5] commonly used for simulating fast ion loss from toroidal plasmas.

  7. Parameter estimation in slow fast models: a palaeoclimate application

    NASA Astrophysics Data System (ADS)

    Almeida, Carlos; Crucifix, Michel

    2013-04-01

    Ice ages have paced climate for about 3 million years. They are characterised by a succession of glacial and interglacial eras, the latest interglacial era having begun approximately 11,000 years ago. There is debate about the timing of the next glacial era, although this is only one of many possible questions about the dynamics of ice ages. Our focus is on how to express these questions in a statistically coherent framework. Even leaving aside chronological uncertainties, the problem is challenging, and we show why. The ice volume oscillations have been modelled by using a non-linear stochastic differential equation with a drift function involving astronomical forcing and a Wiener process as a noise term. Additionally, the observation measure through a proxy is considered as contaminated by another independent noise. The deterministic version of this model has potentially complex dynamics, which can be connected to the theory of strange non-chaotic attractors. The challenge we are facing with the calibration of this model is partly related to the complexity of its dynamics. For estimating the parameters of the model based on observations, two strategies are considered, one by extending the space of the unobserved variables for including the parameters, and the other by approximating the integral over the unobserved variables in order to obtain the marginal likelihood. Both for the estimation in the extended model and for the numerical integration, an unscented Kalman filter and a particle filter are used and compared.

  8. Advanced model for fast assessment of piezoelectric micro energy harvesters

    NASA Astrophysics Data System (ADS)

    Ardito, Raffaele; Corigliano, Alberto; Gafforelli, Giacomo; Valzasina, Carlo; Procopio, Francesco; Zafalon, Roberto

    2016-04-01

    The purpose of this work is to present recent advances in modelling and design of piezoelectric energy harvesters, in the framework of Micro-Electro-Mechanical Systems (MEMS). More specifically, the case of inertial energy harvesting is considered, in the sense that the kinetic energy due to environmental vibration is transformed into electrical energy by means of piezoelectric transduction. The execution of numerical analyses is greatly important in order to predict the actual behaviour of MEMS devices and to carry out the optimization process. In the common practice, the results are obtained by means of burdensome 3D Finite Element Analyses (FEA). The case of beams could be treated by applying 1D models, which can enormously reduce the computational burden with obvious benefits in the case of repeated analyses. Unfortunately, the presence of piezoelectric coupling may entail some serious issues in view of its intrinsically three-dimensional behaviour. In this paper, a refined, yet simple, model is proposed with the objective of retaining the Euler-Bernoulli beam model, with the inclusion of effects connected to the actual three-dimensional shape of the device. The proposed model is adopted to evaluate the performances of realistic harvesters, both in the case of harmonic excitation and for impulsive loads.

  9. A Numerical Model for Coupling of Neutron Diffusion and Thermomechanics in Fast Burst Reactors

    SciTech Connect

    Samet Y. Kadioglu; Dana A. Knoll; Cassiano De Oliveira

    2008-11-01

    We develop a numerical model for coupling of neutron diffusion adn termomechanics in order to stimulate transient behavior of a fast burst reactor. The problem involves solving a set of non-linear different equations which approximate neutron diffusion, temperature change, and material behavior. With this equation set we will model the transition from a supercritical to subcritical state and possible mechanical vibration.

  10. Kinetic models for historical processes of fast invasion and aggression

    NASA Astrophysics Data System (ADS)

    Aristov, Vladimir V.; Ilyin, Oleg V.

    2015-04-01

    In the last few decades many investigations have been devoted to theoretical models in new areas concerning description of different biological, sociological, and historical processes. In the present paper we suggest a model of the Nazi Germany invasion of Poland, France, and the USSR based on kinetic theory. We simulate this process with the Cauchy boundary problem for two-element kinetic equations. The solution of the problem is given in the form of a traveling wave. The propagation velocity of a front line depends on the quotient between initial forces concentrations. Moreover it is obtained that the general solution of the model can be expressed in terms of quadratures and elementary functions. Finally it is shown that the front-line velocities agree with the historical data.

  11. Modeling of the Proposed ATA Fast Correction Coils

    DTIC Science & Technology

    1989-06-01

    SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18. NUMBER OF PAGES 4 19a. NAME OF RESPONSIBLE PERSON a. REPORT...J 0 100 200 Z0 (0) Figure 7. Electrical efficiency of four bar coil designs. P is the poNer input needed to produce the wave mode shown in...in a lower 1 inkage of beam generated flux. The coupling is calculated using a version of JASON which has been modified to handle a limited class of

  12. Personalized heterogeneous deformable model for fast volumetric registration.

    PubMed

    Si, Weixin; Liao, Xiangyun; Wang, Qiong; Heng, Pheng Ann

    2017-02-20

    Biomechanical deformable volumetric registration can help improve safety of surgical interventions by ensuring the operations are extremely precise. However, this technique has been limited by the accuracy and the computational efficiency of patient-specific modeling. This study presents a tissue-tissue coupling strategy based on penalty method to model the heterogeneous behavior of deformable body, and estimate the personalized tissue-tissue coupling parameters in a data-driven way. Moreover, considering that the computational efficiency of biomechanical model is highly dependent on the mechanical resolution, a practical coarse-to-fine scheme is proposed to increase runtime efficiency. Particularly, a detail enrichment database is established in an offline fashion to represent the mapping relationship between the deformation results of high-resolution hexahedral mesh extracted from the raw medical data and a newly constructed low-resolution hexahedral mesh. At runtime, the mechanical behavior of human organ under interactions is simulated with this low-resolution hexahedral mesh, then the microstructures are synthesized in virtue of the detail enrichment database. The proposed method is validated by volumetric registration in an abdominal phantom compression experiments. Our personalized heterogeneous deformable model can well describe the coupling effects between different tissues of the phantom. Compared with high-resolution heterogeneous deformable model, the low-resolution deformable model with our detail enrichment database can achieve 9.4× faster, and the average target registration error is 3.42 mm, which demonstrates that the proposed method shows better volumetric registration performance than state-of-the-art. Our framework can well balance the precision and efficiency, and has great potential to be adopted in the practical augmented reality image-guided robotic systems.

  13. A 'fast' model of the solar convection zone

    NASA Astrophysics Data System (ADS)

    Belvedere, G.; Paterno, L.; Roxburgh, I. W.

    1980-11-01

    A model of solar convection zone incorporates the mixing-length theory in the method developed by Faulkner (1965) which accurately represents the superadiabatic layers. Interpolation formulas which save computer time, and are sufficiently accurate to limit discrepancies in pressure distribution and density through the convection zone, are used; the computer programs are 20 times faster than the programs of Baker and Temesvary (1966).

  14. Fast and Accurate Circuit Design Automation through Hierarchical Model Switching.

    PubMed

    Huynh, Linh; Tagkopoulos, Ilias

    2015-08-21

    In computer-aided biological design, the trifecta of characterized part libraries, accurate models and optimal design parameters is crucial for producing reliable designs. As the number of parts and model complexity increase, however, it becomes exponentially more difficult for any optimization method to search the solution space, hence creating a trade-off that hampers efficient design. To address this issue, we present a hierarchical computer-aided design architecture that uses a two-step approach for biological design. First, a simple model of low computational complexity is used to predict circuit behavior and assess candidate circuit branches through branch-and-bound methods. Then, a complex, nonlinear circuit model is used for a fine-grained search of the reduced solution space, thus achieving more accurate results. Evaluation with a benchmark of 11 circuits and a library of 102 experimental designs with known characterization parameters demonstrates a speed-up of 3 orders of magnitude when compared to other design methods that provide optimality guarantees.

  15. A microprocessor-controlled fast-response speed regulator with dual mode current loop for DCM drives

    NASA Astrophysics Data System (ADS)

    Ohmae, T.; Matsuda, T.; Suzuki, T.; Azusawa, N.; Kamiyama, K.; Konishi, T.

    1980-06-01

    A new control method is described in which a microprocessor is used to regulate the speed of a dc motor driven by antiparallel-connected three-phase dual thyristor converters. A distinct feature of this speed regulating system is that speed response is improved by using a fast-response current controller for the internal loop. A fast-response current controller is obtained by employing a nonlinear compensation subloop and a proportional plus integral compensation subloop. The nonlinear compensation subloop is used to linearize the nonlinear load characteristics of the thyristor converter, which are encountered under discontinuous conduction states of current. The proportional plus integral compensation subloop reduces the deviation of detected current from the current reference. With these two current-control subloops a fast motor speed response is achieved under discontinuous as well as continuous conduction states; hence the steady-state accuracy of speed is improved. A speed regulator using a microprocessor was trial manufactured and tested with a 20-kW dc motor. It was found that an extremely fast controlled current response can be obtained even with a relatively long sampling period. Further, normal action was confirmed in four-quadrant operation.

  16. Evaluation of Fast-Time Wake Vortex Models using Wake Encounter Flight Test Data

    NASA Technical Reports Server (NTRS)

    Ahmad, Nashat N.; VanValkenburg, Randal L.; Bowles, Roland L.; Limon Duparcmeur, Fanny M.; Gloudesman, Thijs; van Lochem, Sander; Ras, Eelco

    2014-01-01

    This paper describes a methodology for the integration and evaluation of fast-time wake models with flight data. The National Aeronautics and Space Administration conducted detailed flight tests in 1995 and 1997 under the Aircraft Vortex Spacing System Program to characterize wake vortex decay and wake encounter dynamics. In this study, data collected during Flight 705 were used to evaluate NASA's fast-time wake transport and decay models. Deterministic and Monte-Carlo simulations were conducted to define wake hazard bounds behind the wake generator. The methodology described in this paper can be used for further validation of fast-time wake models using en-route flight data, and for determining wake turbulence constraints in the design of air traffic management concepts.

  17. Ghrelin differentially modulates the GH secretory response to GHRH between the fed and fasted states in sheep.

    PubMed

    Takahashi, H; Kurose, Y; Suzuki, Y; Kojima, M; Yamaguchi, T; Yoshida, Y; Ogino, M; Hodate, K; Azuma, Y; Sugino, T; Kojima, M; Kangawa, K; Hasegawa, Y; Kobayashi, S

    2009-07-01

    The effect of energy balance on the growth hormone (GH) secretory responsiveness to growth hormone-releasing hormone (GHRH) has not been determined in ruminant animals. Therefore, we examined the effects of intravenous injections of 0, 3.3, and 6.6 microg ghrelin/kg body weight (BW), with and without GHRH at 0.25 microg/kg BW, on GH secretory responsiveness in both the fed and fasted sheep. The injections were carried out at 48 h (Fasting state) and 3h (Satiety state) after feeding. Blood samples were taken every 10 minutes, from 30 minutes before to 120 minutes after the injection. Low (3.3 microg/kg BW) and high (6.6 microg/kg BW) doses of ghrelin stimulated GH secretion significantly (P<.05) greater in the Satiety state than in the Fasting state. Growth hormone-releasing hormone plus both doses of ghrelin stimulated GH secretion significantly (P<.05) greater in the Satiety state than in the Fasting state. Ghrelin and GHRH exerted a synergistic effect in the Satiety state, but not in the Fasting state. Plasma ghrelin levels were maintained significantly (P<.05) greater in the Fasting state than in the Satiety state except the temporal increases after ghrelin administration. Plasma free fatty acid (FFA) concentrations were significantly (P<.01) greater in the Fasting state than in the Satiety state. In conclusion, the present study has demonstrated for the first time that ghrelin differentially modulates GH secretory response to GHRH according to feeding states in ruminant animals.

  18. Ectopic Expression of Mouse Melanopsin in Drosophila Photoreceptors Reveals Fast Response Kinetics and Persistent Dark Excitation.

    PubMed

    Yasin, Bushra; Kohn, Elkana; Peters, Maximilian; Zaguri, Rachel; Weiss, Shirley; Schopf, Krystina; Katz, Ben; Huber, Armin; Minke, Baruch

    2017-03-03

    The intrinsically photosensitive M1 retinal ganglion cells (ipRGC) initiate non-image-forming light-dependent activities and express the melanopsin (OPN4) photopigment. Several features of ipRGC photosensitivity are characteristic of fly photoreceptors. However, the light response kinetics of ipRGC is much slower due to unknown reasons. Here we used transgenic Drosophila, in which the mouse OPN4 replaced the native Rh1 photopigment of Drosophila R1-6 photoreceptors, resulting in deformed rhabdomeric structure. Immunocytochemistry revealed OPN4 expression at the base of the rhabdomeres, mainly at the rhabdomeral stalk. Measurements of the early receptor current, a linear manifestation of photopigment activation, indicated large expression of OPN4 in the plasma membrane. Comparing the early receptor current amplitude and action spectra between WT and the Opn4-expressing Drosophila further indicated that large quantities of a blue absorbing photopigment were expressed, having a dark stable blue intermediate state. Strikingly, the light-induced current of the Opn4-expressing fly photoreceptors was ∼40-fold faster than that of ipRGC. Furthermore, an intense white flash induced a small amplitude prolonged dark current composed of discrete unitary currents similar to the Drosophila single photon responses. The induction of prolonged dark currents by intense blue light could be suppressed by a following intense green light, suggesting induction and suppression of prolonged depolarizing afterpotential. This is the first demonstration of heterologous functional expression of mammalian OPN4 in the genetically emendable Drosophila photoreceptors. Moreover, the fast OPN4-activated ionic current of Drosophila photoreceptors relative to that of mouse ipRGC, indicates that the slow light response of ipRGC does not arise from an intrinsic property of melanopsin. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. Fast Ray Tracing of Lunar Digital Elevation Models

    NASA Technical Reports Server (NTRS)

    McClanahan, Timothy P.; Evans, L. G.; Starr, R. D.; Mitrofanov, I.

    2009-01-01

    Ray-tracing (RT) of Lunar Digital Elevation Models (DEM)'s is performed to virtually derive the degree of radiation incident to terrain as a function of time, orbital and ephemeris constraints [I- 4]. This process is an integral modeling process in lunar polar research and exploration due to the present paucity of terrain information at the poles and mission planning activities for the anticipated spring 2009 launch of the Lunar Reconnaissance Orbiter (LRO). As part of the Lunar Exploration Neutron Detector (LEND) and Lunar Crater Observation and Sensing Satellite (LCROSS) preparations RI methods are used to estimate the critical conditions presented by the combined effects of high latitude, terrain and the moons low obliquity [5-7]. These factors yield low incident solar illumination and subsequently extreme thermal, and radiation conditions. The presented research uses RT methods both for radiation transport modeling in space and regolith related research as well as to derive permanently shadowed regions (PSR)'s in high latitude topographic minima, e.g craters. These regions are of scientific and human exploration interest due to the near constant low temperatures in PSRs, inferred to be < 100 K. Hydrogen is thought to have accumulated in PSR's through the combined effects of periodic cometary bombardment and/or solar wind processes, and the extreme cold which minimizes hydrogen sublimation [8-9]. RT methods are also of use in surface position optimization for future illumination dependent on surface resources e.g. power and communications equipment.

  20. A fast ellipsoid model for asteroids inverted from lightcurves

    NASA Astrophysics Data System (ADS)

    Lu, Xiao-Ping; Zhao, Hai-Bin; You, Zhong

    2013-04-01

    Research about asteroids has recently attracted more and more attention, especially focusing on their physical structures, such as their spin axis, rotation period and shape. The long distance between observers on Earth and asteroids makes it impossible to directly calculate the shape and other parameters of asteroids, with the exception of Near Earth Asteroids and others that have passed by some spacecrafts. Photometric measurements are still generally the main way to obtain research data on asteroids, i.e. the lightcurves recording the brightness and positions of asteroids. Supposing that the shape of the asteroid is a triaxial ellipsoid with a stable spin, a new method is presented in this article to reconstruct the shape models of asteroids from the lightcurves, together with other physical parameters. By applying a special curvature function, the method calculates the brightness integration on a unit sphere and Lebedev quadrature is employed for the discretization. Finally, the method searches for the optimal solution by the Levenberg-Marquardt algorithm to minimize the residual of the brightness. By adopting this method, not only can related physical parameters of asteroids be obtained at a reasonable accuracy, but also a simple shape model of an ellipsoid can be generated for reconstructing a more sophisticated shape model.

  1. Metabolic and hormonal response to chronic maternal fasting in the ewe.

    PubMed

    Schreiner, R L; Lemons, J A; Gresham, E L

    1981-01-01

    The purpose of this study was to investigate the metabolic adaptations of the fetus during maternal starvation and to determine the changes of plasma insulin and glucagon concentrations in the fed state and during severe maternal fasting in the chronic fetal sheep preparation. Maternal fasting resulted in a decrease in maternal and fetal plasma glucose as well as a decrease in fetal plasma fructose. Fetal-maternal arterial urea concentration differences increased with maternal fasting, suggesting increased fetal amino acid catabolism. Both maternal anf fetal plasma insulin decreased parallel to the decrease in plasma glucose concentration. Maternal glucagon did not change significantly during fasting and with a short-term fast there was no change in fetal glucagon concentration. However, by 6 days of fasting, the fetal glucagon concentration tended to increase.

  2. Fast calculating surrogate models for leg and head impact in vehicle-pedestrian collision simulations.

    PubMed

    Wimmer, Peter; Benedikt, Martin; Huber, Philipp; Ferenczi, Izabella

    2015-01-01

    In previous research, a tool chain to simulate vehicle-pedestrian accidents from ordinary driving state to in-crash has been developed. This tool chain allows for injury criteria-based, vehicle-specific (geometry, stiffness, active safety systems, etc.) assessments. Due to the complex nature of the included finite element analysis (FEA) models, calculation times are very high. This is a major drawback for using FEA models in large-scale effectiveness assessment studies. Therefore, fast calculating surrogate models to approximate the relevant injury criteria as a function of pedestrian vehicle collision constellations have to be developed. The development of surrogate models for head and leg injury criteria to overcome the problem of long calculation times while preserving high detail level of results for effectiveness analysis is shown in this article. These surrogate models are then used in the tool chain as time-efficient replacements for the FEA model to approximate the injury criteria values. The method consists of the following steps: Selection of suitable training data sets out of a large number of given collision constellations, detailed FEA calculations with the training data sets as input, and training of the surrogate models with the FEA model's input and output values. A separate surrogate model was created for each injury criterion, consisting of a response surface that maps the input parameters (i.e., leg impactor position and velocity) to the output value. In addition, a performance test comparing surrogate model predictions of additional collision constellations to the results of respective FEA calculations was carried out. The developed method allows for prediction of injury criteria based on impact constellation for a given vehicle. Because the surrogate models are specific to a certain vehicle, training has to be redone for a new vehicle. Still, there is a large benefit regarding calculation time when doing large-scale studies. The method can be

  3. Fast neural network surrogates for very high dimensional physics-based models in computational oceanography.

    PubMed

    van der Merwe, Rudolph; Leen, Todd K; Lu, Zhengdong; Frolov, Sergey; Baptista, Antonio M

    2007-05-01

    We present neural network surrogates that provide extremely fast and accurate emulation of a large-scale circulation model for the coupled Columbia River, its estuary and near ocean regions. The circulation model has O(10(7)) degrees of freedom, is highly nonlinear and is driven by ocean, atmospheric and river influences at its boundaries. The surrogates provide accurate emulation of the full circulation code and run over 1000 times faster. Such fast dynamic surrogates will enable significant advances in ensemble forecasts in oceanography and weather.

  4. Sampling frequency, response times and embedded signal filtration in fast, high efficiency liquid chromatography: A tutorial.

    PubMed

    Wahab, M Farooq; Dasgupta, Purnendu K; Kadjo, Akinde F; Armstrong, Daniel W

    2016-02-11

    With increasingly efficient columns, eluite peaks are increasingly narrower. To take full advantage of this, choice of the detector response time and the data acquisition rate a.k.a. detector sampling frequency, have become increasingly important. In this work, we revisit the concept of data sampling from the theorem variously attributed to Whittaker, Nyquist, Kotelnikov, and Shannon. Focusing on time scales relevant to the current practice of high performance liquid chromatography (HPLC) and optical absorbance detection (the most commonly used method), even for very narrow simulated peaks Fourier transformation shows that theoretical minimum sampling frequency is still relatively low (<10 Hz). However, this consideration alone may not be adequate for real chromatograms when an appreciable amount of noise is present. Further, depending on the instrument, the manufacturer's choice of a particular data bunching/integration/response time condition may be integrally coupled to the sampling frequency. In any case, the exact nature of signal filtration often occurs in a manner neither transparent to nor controllable by the user. Using fast chromatography on a state-of-the-art column (38,000 plates), we evaluate the responses produced by different present generation instruments, each with their unique black box digital filters. We show that the common wisdom of sampling 20 points per peak can be inadequate for high efficiency columns and that the sampling frequency and response choices do affect the peak shape. If the sampling frequency is too low or response time is too large, the observed peak shapes will not remain as narrow as they really are - this is especially true for high efficiency and high speed separations. It is shown that both sampling frequency and digital filtering affect the retention time, noise amplitude, peak shape and width in a complex fashion. We show how a square-wave driven light emitting diode source can reveal the nature of the embedded filter

  5. Fast coarse-grained model for RNA titration

    NASA Astrophysics Data System (ADS)

    Barroso da Silva, Fernando Luís; Derreumaux, Philippe; Pasquali, Samuela

    2017-01-01

    A new numerical scheme for RNA (ribonucleic acid) titration based on the Debye-Hückel framework for the salt description is proposed in an effort to reduce the computational costs for further applications to study protein-RNA systems. By means of different sets of Monte Carlo simulations, we demonstrated that this new scheme is able to correctly reproduce the experimental titration behavior and salt pKa shifts. In comparison with other theoretical approaches, similar or even better outcomes are achieved at much lower computational costs. The model was tested on the lead-dependent ribozyme, the branch-point helix, and the domain 5 from Azotobacter vinelandii Intron 5.

  6. Validation of fast diffusion kurtosis MRI for imaging acute ischemia in a rodent model of stroke

    PubMed Central

    Sun, Phillip Zhe; Wang, Yu; Mandeville, Emiri; Chan, Suk-Tak; Lo, Eng H; Ji, Xunming

    2014-01-01

    Diffusion-weighted imaging (DWI) captures ischemic tissue that is likely to infarct, and has become one of the most widely used acute stroke imaging techniques. Diffusion kurtosis imaging (DKI) has lately been postulated as a complementary MRI method to stratify the heterogeneously damaged DWI lesion. However, the conventional DKI acquisition time is relatively long, limiting its use in the acute stroke setting. Recently, Hansen et al. proposed a fast kurtosis mapping method and demonstrated it in fixed brains and control subjects. The fast DKI approach provides mean diffusion and kurtosis measurements under substantially reduced scan time, making it amenable to acute stroke imaging. Because it is not practical to obtain and compare different means of DKI to test whether the fast DKI method can reliably detect diffusion and kurtosis lesions in acute stroke patients, our study investigated its diagnostic value using an animal model of acute stroke, a critical step before fast DKI acquisition can be routinely applied in the acute stroke setting. We found significant correlation, per voxel, between the diffusion and kurtosis coefficients measured using the fast and conventional DKI protocols. In acute stroke rats, both DKI methods yielded diffusion and kurtosis lesions that were in good agreement. Importantly, substantial kurtosis/diffusion lesion mismatch was observed using the conventional (26±13%, P<0.01) and fast DKI methods (23±8%, P<0.01). In addition, regression analysis showed that the kurtosis/diffusion lesion mismatch obtained using conventional and fast DKI methods were substantially correlated (R2=0.57, P=0.02). Our results confirmed that the recently proposed fast DKI method is capable of capturing heterogeneous diffusion and kurtosis lesions in acute ischemic stroke, and thus is suitable for translational applications in the acute stroke clinical setting. PMID:25208309

  7. Validation of fast diffusion kurtosis MRI for imaging acute ischemia in a rodent model of stroke.

    PubMed

    Sun, Phillip Zhe; Wang, Yu; Mandeville, Emiri; Chan, Suk-Tak; Lo, Eng H; Ji, Xunming

    2014-11-01

    Diffusion-weighted imaging (DWI) captures ischemic tissue that is likely to infarct, and has become one of the most widely used acute stroke imaging techniques. Diffusion kurtosis imaging (DKI) has lately been postulated as a complementary MRI method to stratify the heterogeneously damaged DWI lesion. However, the conventional DKI acquisition time is relatively long, limiting its use in the acute stroke setting. Recently, a fast kurtosis mapping method has been demonstrated in fixed brains and control subjects. The fast DKI approach provides mean diffusion and kurtosis measurements under substantially reduced scan time, making it amenable to acute stroke imaging. Because it is not practical to obtain and compare different means of DKI to test whether the fast DKI method can reliably detect diffusion and kurtosis lesions in acute stroke patients, our study investigated its diagnostic value using an animal model of acute stroke, a critical step before fast DKI acquisition can be routinely applied in the acute stroke setting. We found significant correlation, per voxel, between the diffusion and kurtosis coefficients measured using the fast and conventional DKI protocols. In acute stroke rats, the two DKI methods yielded diffusion and kurtosis lesions that were in good agreement. Importantly, substantial kurtosis-diffusion lesion mismatch was observed using the conventional (26 ± 13%, P < 0.01) and fast DKI methods (23 ± 8%, P < 0.01). In addition, regression analysis showed that the kurtosis-diffusion lesion mismatches obtained using conventional and fast DKI methods were substantially correlated (R(2) = 0.57, P = 0.02). Our results confirmed that the recently proposed fast DKI method is capable of capturing heterogeneous diffusion and kurtosis lesions in acute ischemic stroke, and thus is suitable for translational applications in the acute stroke clinical setting.

  8. RF Modeling of a Helical Kicker for Fast Chopping

    SciTech Connect

    Awida, Mohamed; Chen, Alex; Khabiboulline, Timergali; Saewert, Gregory; Yakovlev, Vyacheslav

    2015-06-01

    High intensity proton particle accelerators that supports several simultaneous physics experiments requires sharing the beam. A bunch by bunch beam chopper system located after the Radio Frequency Quadrupole (RFQ) is required in this case to structure the beam in the proper bunch format required by the several experiments. The unused beam will need to be kicked out of the beam path and is disposed in a beam dumb. In this paper, we report on the RF modeling results of a proposed helical kicker. Two beam kickers constitutes the proposed chopper. The beam sequence is formed by kicking in or out the beam bunches from the streamline. The chopper was developed for Project X Injection Experiment (PXIE).

  9. A Riparian Vegetation Ecophysiological Response Model

    Treesearch

    Jeffrey P. Leighton; Roland J. Risser

    1989-01-01

    A mathematical model is described that relates mature riparian vegetation ecophysiological response to changes in stream level. This model was developed to estimate the physiological response of riparian vegetation to reductions in streamflow. Field data from two sites on the North Fork of the Kings River were used in the model development. The physiological response...

  10. Fast cloud adjustment to increasing CO2 in a superparameterized climate model

    NASA Astrophysics Data System (ADS)

    Wyant, Matthew C.; Bretherton, Christopher S.; Blossey, Peter N.; Khairoutdinov, Marat

    2012-05-01

    Two-year simulation experiments with a superparameterized climate model, SP-CAM, are performed to understand the fast tropical (30S-30N) cloud response to an instantaneous quadrupling of CO2 concentration with SST held fixed at present-day values. The greenhouse effect of the CO2 perturbation quickly warms the tropical land surfaces by an average of 0.5 K. This shifts rising motion, surface precipitation, and cloud cover at all levels from the ocean to the land, with only small net tropical-mean cloud changes. There is a widespread average reduction of about 80 m in the depth of the trade inversion capping the marine boundary layer (MBL) over the cooler subtropical oceans. One apparent contributing factor is CO2-enhanced downwelling longwave radiation, which reduces boundary-layer radiative cooling, a primary driver of turbulent entrainment through the trade inversion. A second contributor is a slight CO2-induced heating of the free troposphere above the MBL, which strengthens the trade inversion and also inhibits entrainment. There is a corresponding downward displacement of MBL clouds with a very slight decrease in mean cloud cover and albedo. Two-dimensional cloud-resolving model (CRM) simulations of this MBL response are run to steady state using composite SP-CAM simulated thermodynamic and wind profiles from a representative cool subtropical ocean regime, for the control and 4xCO2 cases. Simulations with a CRM grid resolution equal to that of SP-CAM are compared with much finer resolution simulations. The coarse-resolution simulations maintain a cloud fraction and albedo comparable to SP-CAM, but the fine-resolution simulations have a much smaller cloud fraction. Nevertheless, both CRM configurations simulate a reduction in inversion height comparable to SP-CAM. The changes in low cloud cover and albedo in the CRM simulations are small, but both simulations predict a slight reduction in low cloud albedo as in SP-CAM.

  11. Formulation and optimization of fast dissolving intraoral drug delivery system for clobazam using response surface methodology

    PubMed Central

    Bala, Rajni; Khanna, Sushil; Pawar, Pravin K.

    2013-01-01

    Clobazam is a newer 1,5-benzodiazepine used for the treatment of epilepsy. It is better tolerated and less sedating than other benzodiazepines. Absorption of the drug can be impacted by oral fast dissolving dosage form; this may have implications for epilepsy in pediatrics and those having difficulty in swallowing tablets/capsules resulting in improved patient compliance. The purpose of the present investigation was to formulate and optimize clobazam oro-dissolving tablets by direct compression method using response surface methodology (RSM). Oro-dispersible tablets of clobazam were prepared by direct compression method using crospovidone (2-6%) as a superdisintegrant, microcrystalline cellulose (MCC) (20-40%) was used as diluents along with directly compressible mannitol to enhance mouth feel. A 32 full factorial design was applied to investigate the combined effect of two formulation variables: amount of crospovidone and MCC over the independent variables disintegration time, wetting time and percent drug release. Disintegration time showed by all formulations was found to be in the range of 24.3-193 s based on evaluation parameters the formulation containing 6% of crospovidone and 30% of MCC showed promising performance against all other formulations. The results demonstrated that the RSM could efficiently be applied for the formulation of clobazam oro-dispersible tablets; therefore, constitute an advance in the management of epileptic attacks. PMID:24083203

  12. Analysis of the ballistic impact response of a composite material using FAST Infrared Imagery

    NASA Astrophysics Data System (ADS)

    Marcotte, Frederick; Ouellet, Simon; Farley, Vincent

    2013-05-01

    The level of protection offered by a given ballistic material is typically evaluated in terms of a set of projectiles and their associated velocity at which a certain percentage of the projectiles are expected to perforate. (i.e. FSP 17gr : V50 = 500m/s, 9mm FMJ; V0=500m/s). These metrics give little information about the physical phenomena by which energy is dispersed, spread or absorbed in a specific target material. Aside from post-test inspection of the impacted material, additional information on the target response is traditionally obtained during a test from the use of high speed imaging, whether it is from a single camera aimed at the impact surface or the backface, or from a set of camera allowing full 3-D reconstruction of a deformed surface. Again, this kind of data may be difficult to interpret if the interest is in the way energy is managed in the target in real time. Recent technological progress in scientific grade high-speed infrared (IR) camera demonstrated that these phenomena can straightforwardly be measured using IR thermal imaging. This paper presents promising results obtained from Telops FAST-IR 1500 infrared camera on an aramid-based ballistic composite during an impact from a small caliber fragment simulating projectile (FSP).

  13. Fast-response fiber-optic anemometer with temperature self-compensation.

    PubMed

    Liu, Guigen; Hou, Weilin; Qiao, Wei; Han, Ming

    2015-05-18

    We report a novel fiber-optic anemometer with self-temperature compensation capability based on a Fabry-Pérot interferometer (FPI) formed by a thin silicon film attached to the end face of a single-mode fiber. Guided in the fiber are a visible laser beam from a 635 nm diode laser used to heat the FPI and a white-light in the infrared wavelength range as the signal light to interrogate the optical length of the FPI. Cooling effects on the heated sensor head by wind is converted to a wavelength blueshift of the reflection spectral fringes of the FPI. Self-temperature-compensated measurement of wind speed is achieved by recording the difference in fringe wavelengths when the heating laser is turned on and then off. Large thermal-optic coefficient and thermal expansion coefficient of silicon render a high sensitivity that can also be easily tuned by altering the heating laser power. Furthermore, the large thermal diffusivity and the small mass of the thin silicon film endow a fast sensor response.

  14. Advanced vapor recognition materials for selective and fast responsive surface acoustic wave sensors: a review.

    PubMed

    Afzal, Adeel; Iqbal, Naseer; Mujahid, Adnan; Schirhagl, Romana

    2013-07-17

    The necessity of selectively detecting various organic vapors is primitive not only with respect to regular environmental and industrial hazard monitoring, but also in detecting explosives to combat terrorism and for defense applications. Today, the huge arsenal of micro-sensors has revolutionized the traditional methods of analysis by, e.g. replacing expensive laboratory equipment, and has made the remote screening of atmospheric threats possible. Surface acoustic wave (SAW) sensors - based on piezoelectric crystal resonators - are extremely sensitive to even very small perturbations in the external atmosphere, because the energy associated with the acoustic waves is confined to the crystal surface. Combined with suitably designed molecular recognition materials SAW devices could develop into highly selective and fast responsive miniaturized sensors, which are capable of continuously monitoring a specific organic gas, preferably in the sub-ppm regime. For this purpose, different types of recognition layers ranging from nanostructured metal oxides and carbons to pristine or molecularly imprinted polymers and self-assembled monolayers have been applied in the past decade. We present a critical review of the recent developments in nano- and micro-engineered synthetic recognition materials predominantly used for SAW-based organic vapor sensors. Besides highlighting their potential to realize real-time vapor sensing, their limitations and future perspectives are also discussed.

  15. A fast response miniature probe for wet steam flow field measurements

    NASA Astrophysics Data System (ADS)

    Bosdas, Ilias; Mansour, Michel; Kalfas, Anestis I.; Abhari, Reza S.

    2016-12-01

    Modern steam turbines require operational flexibility due to renewable energies’ increasing share of the electrical grid. Additionally, the continuous increase in energy demand necessitates efficient design of the steam turbines as well as power output augmentation. The long turbine rotor blades at the machines’ last stages are prone to mechanical vibrations and as a consequence time-resolved experimental data under wet steam conditions are essential for the development of large-scale low-pressure steam turbines. This paper presents a novel fast response miniature heated probe for unsteady wet steam flow field measurements. The probe has a tip diameter of 2.5 mm, and a miniature heater cartridge ensures uncontaminated pressure taps from condensed water. The probe is capable of providing the unsteady flow angles, total and static pressure as well as the flow Mach number. The operating principle and calibration procedure are described in the current work and a detailed uncertainty analysis demonstrates the capability of the new probe to perform accurate flow field measurements under wet steam conditions. In order to exclude any data possibly corrupted by droplets’ impact or evaporation from the heating process, a filtering algorithm was developed and implemented in the post-processing phase of the measured data. In the last part of this paper the probe is used in an experimental steam turbine test facility and measurements are conducted at the inlet and exit of the last stage with an average wetness mass fraction of 8.0%.

  16. Tunable graphene micro-emitters with fast temporal response and controllable electron emission

    PubMed Central

    Wu, Gongtao; Wei, Xianlong; Gao, Song; Chen, Qing; Peng, Lianmao

    2016-01-01

    Microfabricated electron emitters have been studied for half a century for their promising applications in vacuum electronics. However, tunable microfabricated electron emitters with fast temporal response and controllable electron emission still proves challenging. Here, we report the scaling down of thermionic emitters to the microscale using microfabrication technologies and a Joule-heated microscale graphene film as the filament. The emission current of the graphene micro-emitters exhibits a tunability of up to six orders by a modest gate voltage. A turn-on/off time of less than 1 μs is demonstrated for the graphene micro-emitters, indicating a switching speed about five orders of magnitude faster than their bulky counterparts. Importantly, emission performances of graphene micro-emitters are controllable and reproducible through engineering graphene dimensions by microfabrication technologies, which enables us to fabricate graphene micro-emitter arrays with uniform emission performances. Graphene micro-emitters offer an opportunity of realizing large-scale addressable micro-emitter arrays for vacuum electronics applications. PMID:27160693

  17. Fast response dry-type artificial molecular muscles with [c2]daisy chains.

    PubMed

    Iwaso, Kazuhisa; Takashima, Yoshinori; Harada, Akira

    2016-06-01

    Hierarchically organized myosin and actin filaments found in biological systems exhibit contraction and expansion behaviours that produce work and force by consuming chemical energy. Inspired by these naturally occurring examples, we have developed photoresponsive wet- and dry-type molecular actuators built from rotaxane-based compounds known as [c2]daisy chains (specifically, [c2]AzoCD2 hydrogel and [c2]AzoCD2 xerogel). These actuators were prepared via polycondensation between four-armed poly(ethylene glycol) and a [c2]daisy chain based on α-cyclodextrin as the host component and azobenzene as a photoresponsive guest component. The light-induced actuation arises from the sliding motion of the [c2]daisy chain unit. Ultraviolet irradiation caused the gels to bend towards the light source. The response of the [c2]AzoCD2 xerogel, even under dry conditions, is very fast (7° every second), which is 10,800 times faster than the [c2]AzoCD2 hydrogel (7° every 3 h). In addition, the [c2]AzoCD2 xerogel was used as a crane arm to lift an object using ultraviolet irradiation to produce mechanical work.

  18. Sealing-free fast-response paraffin/nanoporous gold hybrid actuator.

    PubMed

    Ye, Xing-Long; Jin, Hai-Jun

    2017-09-20

    Paraffin-based actuators can deliver large actuation strokes and high actuation stress, but often suffer from a low response rate and leaking problems. Here, we report a new paraffin/metal hybrid actuator, which was fabricated by infiltrating nanoporous gold with paraffin. It exhibits a fast actuation rate owing to the high thermal conductivity of the inter-connected metal phase, and requires no external sealing because liquid paraffin can be well confined in nanoscale channels, due to the large capillarity. We found that in this hybrid actuator, the stress generated by actuation is negligibly small when the characteristic size of the nanoporous gold (L) is above ∼70 nm, and increases dramatically with a decreasing size when L < ∼70 nm. The large actuation stress in samples with L < ∼70 nm is ascribed to a 'smaller is stronger' effect in paraffin wax-the paraffin in smaller pores can sustain larger tensile stress, and thus the contraction of paraffin during cooling can be translated into larger compression stress and strain energy in a metal framework, leading to a larger actuation stress and energy. We also demonstrate that complex actuation motions can be achieved by incorporating hierarchical-structured nanoporous metal with paraffin.

  19. Fast-response temperature-sensitive-paint measurements on a hypersonic transition cone

    NASA Astrophysics Data System (ADS)

    Ozawa, H.; Laurence, S. J.; Schramm, J. Martinez; Wagner, A.; Hannemann, K.

    2015-01-01

    Experiments are performed using a fast-response temperature-sensitive-paint (TSP) technique to measure the heat-flux distribution on a slender cone in a hypersonic shock tunnel under both laminar and transitional conditions. The millisecond-order test duration together with the self-luminosity of shock layers place stringent conditions on the choice of TSP luminophore and the TSP-layer thickness that can be employed. The luminosity and dimming from particulates in the free-stream cause additional problems in interpreting the obtained intensity profiles. Nevertheless, favorable agreement with thermocouple-based measurements show that it is possible to derive quantitatively accurate heat-flux distributions with the TSP technique for temperature rises of up to approximately 40 K above room temperature. The technique accuracy is adversely affected at higher temperatures, which is thought to result from non-constant thermal properties of the insulating base layer. At high unit Reynolds number conditions, time-resolved heat-flux distributions show large-scale unsteadiness in the boundary-layer transition location and reveal transient streamwise streaks developing in the transitional region.

  20. Fast response dry-type artificial molecular muscles with [c2]daisy chains

    NASA Astrophysics Data System (ADS)

    Iwaso, Kazuhisa; Takashima, Yoshinori; Harada, Akira

    2016-06-01

    Hierarchically organized myosin and actin filaments found in biological systems exhibit contraction and expansion behaviours that produce work and force by consuming chemical energy. Inspired by these naturally occurring examples, we have developed photoresponsive wet- and dry-type molecular actuators built from rotaxane-based compounds known as [c2]daisy chains (specifically, [c2]AzoCD2 hydrogel and [c2]AzoCD2 xerogel). These actuators were prepared via polycondensation between four-armed poly(ethylene glycol) and a [c2]daisy chain based on α-cyclodextrin as the host component and azobenzene as a photoresponsive guest component. The light-induced actuation arises from the sliding motion of the [c2]daisy chain unit. Ultraviolet irradiation caused the gels to bend towards the light source. The response of the [c2]AzoCD2 xerogel, even under dry conditions, is very fast (7° every second), which is 10,800 times faster than the [c2]AzoCD2 hydrogel (7° every 3 h). In addition, the [c2]AzoCD2 xerogel was used as a crane arm to lift an object using ultraviolet irradiation to produce mechanical work.

  1. Sealing-free fast-response paraffin/nanoporous gold hybrid actuator

    NASA Astrophysics Data System (ADS)

    Ye, Xing-Long; Jin, Hai-Jun

    2017-09-01

    Paraffin-based actuators can deliver large actuation strokes and high actuation stress, but often suffer from a low response rate and leaking problems. Here, we report a new paraffin/metal hybrid actuator, which was fabricated by infiltrating nanoporous gold with paraffin. It exhibits a fast actuation rate owing to the high thermal conductivity of the inter-connected metal phase, and requires no external sealing because liquid paraffin can be well confined in nanoscale channels, due to the large capillarity. We found that in this hybrid actuator, the stress generated by actuation is negligibly small when the characteristic size of the nanoporous gold (L) is above ∼70 nm, and increases dramatically with a decreasing size when L < ∼70 nm. The large actuation stress in samples with L < ∼70 nm is ascribed to a ‘smaller is stronger’ effect in paraffin wax—the paraffin in smaller pores can sustain larger tensile stress, and thus the contraction of paraffin during cooling can be translated into larger compression stress and strain energy in a metal framework, leading to a larger actuation stress and energy. We also demonstrate that complex actuation motions can be achieved by incorporating hierarchical-structured nanoporous metal with paraffin.

  2. Gas Control and Thermal Modeling Methods for Pressed Pellet and Fast Rise Thin-Film Thermal Batteries

    DTIC Science & Technology

    2015-09-01

    ARL-TR-7464 ● SEP 2015 US Army Research Laboratory Gas Control and Thermal Modeling Methods for Pressed Pellet and Fast Rise...Laboratory Gas Control and Thermal Modeling Methods for Pressed Pellet and Fast Rise Thin-Film Thermal Batteries by Frank C Krieger and Michael S...From - To) 10/2014 to 09/2015 4. TITLE AND SUBTITLE Gas Control and Thermal Modeling Methods for Pressed Pellet and Fast Rise Thin-Film Thermal

  3. Measurement of the Fast Neutron Response for {sup 4}He Scintillation Detectors Using a Coincidence Scattering Method

    SciTech Connect

    Kelley, R.P.; Lewis, J.M.; Murer, D.; Enqvist, A.; Jordan, K.A.

    2015-07-01

    Previous work has measured the neutron response of pressurized {sup 4}He scintillation detectors, however these studies only examine the response as a function of incident neutron energy. Since the detection mechanism in {sup 4}He detectors is elastic scattering, and the interacting neutron will only deposit a fraction of its incident kinetic energy in the detector gas, an examination of the response of the detector output to deposited energy is necessary to transform these detectors into instruments for neutron spectrometry. Using a combined time-of-flight (TOF) and coincidence scattering method, this paper further characterizes the {sup 4}He light response to fast neutrons by examining the scintillation light yield as a function of deposited energy, measuring the light response up to 5 MeV. These {sup 4}He detectors are simple in design, and are manufactured by Arktis Radiation Detectors in several sizes. The specific model used in this experiment had an active volume 20 cm long with an inner diameter of 4.4 cm, giving a total active volume of 304 cm{sup 3}. The key components include the active volume, filled with 150 bar of helium-4 gas, and photomultiplier tubes (PMTs) mounted at either end of the active volume. The detector body is made of stainless steel. The detector response was experimentally measured using a two-detector coincidence arrangement with a {sup 252}Cf source. Two {sup 4}He detectors were vertically mounted, and the source was placed at a horizontal distance from the center of the bottom detector, forming a right angle. By requiring coincidence between the two detectors, it was confirmed that each neutron interacting in the second (top) detector must first have undergone a scattering interaction in the first (bottom) detector, and the time-of-flight (TOF) technique could then be used to determine the energy of the neutron as it traveled between the two detectors by the difference in time between the two detector events. More importantly, with

  4. Traditional healers and the "Fast-Track" HIV response: is success possible without them?

    PubMed

    Leclerc-Madlala, Suzanne; Green, Edward; Hallin, Mary

    2016-07-01

    The rapid scale-up of effective HIV prevention strategies is a central theme of the post-2015 health and development agenda. All major global HIV and AIDS funders have aligned their policies and plans to achieve sharp reductions in new HIV infections and reach epidemic control by 2030. In these "fast-track" plans, increased antiretroviral treatment coverage and the attainment of viral suppression are pivotal, and there is firm recognition of the need for countries to mobilise more domestic resources and build stronger community clinic systems. There is little in these bold plans, however, to suggest that the now 30-year-old call by the World Health Organization (WHO) and other organisations to establish systematic collaborations with the traditional health sector will finally be heeded. In the context of sub-Saharan Africa's HIV epidemic, a significant body of literature demonstrates the critical role that traditional healers can play in improving the success of health programmes, including those for HIV prevention. This paper provides a brief history of collaboration with traditional healers for HIV followed by a description of several successful collaborations and discussion of key elements for success. We argue that the traditional health sector is a major resource that has yet to be sufficiently mobilised against HIV. As we shift from a short-term HIV response to a longer-term and more sustainable response, there is an urgent need to accelerate efforts to leverage and partner with the hundreds of thousands of traditional health practitioners who are already providing health services in communities. Failure to better attune our work to the medical pluralism of communities affected by HIV will continue to hinder HIV programming success and help assure that ambitious post-2015 HIV prevention and control goals are not realised.

  5. MCNPX simulations of the silicon carbide semiconductor detector response to fast neutrons from D-T nuclear reaction

    NASA Astrophysics Data System (ADS)

    Sedlačková, Katarína; Šagátová, Andrea; Zat'ko, Bohumír; Nečas, Vladimír; Solar, Michael; Granja, Carlos

    2016-09-01

    Silicon Carbide (SiC) has been long recognized as a suitable semiconductor material for use in nuclear radiation detectors of high-energy charged particles, gamma rays, X-rays and neutrons. The nuclear interactions occurring in the semiconductor are complex and can be quantified using a Monte Carlo-based computer code. In this work, the MCNPX (Monte Carlo N-Particle eXtended) code was employed to support detector design and analysis. MCNPX is widely used to simulate interaction of radiation with matter and supports the transport of 34 particle types including heavy ions in broad energy ranges. The code also supports complex 3D geometries and both nuclear data tables and physics models. In our model, monoenergetic neutrons from D-T nuclear reaction were assumed as a source of fast neutrons. Their energy varied between 16 and 18.2 MeV, according to the accelerating voltage of the deuterons participating in D-T reaction. First, the simulations were used to calculate the optimum thickness of the reactive film composed of High Density PolyEthylene (HDPE), which converts neutral particles to charged particles and thusly enhancing detection efficiency. The dependency of the optimal thickness of the HDPE layer on the energy of the incident neutrons has been shown for the inspected energy range. Further, from the energy deposited by secondary charged particles and recoiled ions, the detector response was modeled and the effect of the conversion layer on detector response was demonstrated. The results from the simulations were compared with experimental data obtained for a detector covered by a 600 and 1300 μm thick conversion layer. Some limitations of the simulations using MCNPX code are also discussed.

  6. Macroporous gels with fast response prepared by e-beam crosslinking of poly(N-isopropylacrylamide) solution

    NASA Astrophysics Data System (ADS)

    Safrany, Agnes

    2005-07-01

    Macroporous temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) gels exhibiting fast response rates were obtained by electron beam irradiation of aqueous polymer solutions. The effect of polymer concentration, irradiation temperature and dose, as well as addition of crosslinker was studied. The gels synthesized above the critical temperature from 20 wt.% polymer solution without crosslinker exhibited the highest equilibrium swelling and fastest response rate measured by seconds. The gels show reversible response to cyclical changes in temperature and might be used as actuators or pulsed drug release.

  7. Metabolic and hormonal responses of growing modern meat type chickens to fasting

    USDA-ARS?s Scientific Manuscript database

    The present study compared the effects of fasting on circulating concentrations of glucose, insulin and glucagon in male and female modern meat-type chickens (Ross 708) at three ages (19 d, 33 d and 47 d). Plasma concentrations of glucose were reduced by fasting with reductions of 24.9% (19-d-old),...

  8. Response of gut microbiota to fasting and hibernation in Syrian hamsters.

    PubMed

    Sonoyama, Kei; Fujiwara, Reiko; Takemura, Naoki; Ogasawara, Toru; Watanabe, Jun; Ito, Hiroyuki; Morita, Tatsuya

    2009-10-01

    Although hibernating mammals wake occasionally to eat during torpor, this period represents a state of fasting. Fasting is known to alter the gut microbiota in nonhibernating mammals; therefore, hibernation may also affect the gut microbiota. However, there are few reports of gut microbiota in hibernating mammals. The present study aimed to compare the gut microbiota in hibernating torpid Syrian hamsters with that in active counterparts by using culture-independent analyses. Hamsters were allocated to either torpid, fed active, or fasted active groups. Hibernation was successfully induced by maintaining darkness at 4 degrees C. Flow cytometry analysis of cecal bacteria showed that 96-h fasting reduced the total gut bacteria. This period of fasting also reduced the concentrations of short chain fatty acids in the cecal contents. In contrast, total bacterial numbers and concentrations of short chain fatty acids were unaffected by hibernation. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments indicated that fasting and hibernation modulated the cecal microbiota. Analysis of 16S rRNA clone library and species-specific real-time quantitative PCR showed that the class Clostridia predominated in both active and torpid hamsters and that populations of Akkermansia muciniphila, a mucin degrader, were increased by fasting but not by hibernation. From these results, we conclude that the gut microbiota responds differently to fasting and hibernation in Syrian hamsters.

  9. SIRT3 gene expression but not SIRT3 subcellular localization is altered in response to fasting and exercise in human skeletal muscle.

    PubMed

    Edgett, Brittany A; Hughes, Meghan C; Matusiak, Jennifer B L; Perry, Christopher G R; Simpson, Craig A; Gurd, Brendon J

    2016-08-01

    What is the central question of this study? Evidence from cellular and animal models suggests that SIRT3 is involved in regulating aerobic ATP production. Thus, we investigated whether changes in fatty acid and oxidative metabolism known to accompany fasting and exercise occur in association with changes in SIRT3 mitochondrial localization and expression in human skeletal muscle. What is the main finding and its importance? We find that 48 h of fasting and acute endurance exercise decrease SIRT3 mRNA expression but do not alter SIRT3 mitochondrial localization despite marked increases in fatty acid oxidation. This suggests that SIRT3 activity is not regulated by changes in mitochondrial localization in response to cellular energy stress in human skeletal muscle. The present study examined SIRT3 expression and SIRT3 mitochondrial localization in response to acute exercise and short-term fasting in human skeletal muscle. Experiment 1 involved eight healthy men (age, 21.4 ± 2.8 years; peak O2 uptake, 47.1 ± 11.8 ml min(-1)  kg(-1) ) who performed a single bout of exercise at ∼55% of peak aerobic work rate for 1 h. Muscle biopsies were obtained at rest (Rest), immediately after exercise (EX-0) and 3 h postexercise (EX-3). Experiment 2 involved 10 healthy men (age, 22.0 ± 1.5 years; peak O2 uptake, 47.2 ± 6.7 ml min(-1)  kg(-1) ) who underwent a 48 h fast, with muscle biopsies collected 1 h postprandial (Fed) and after 48 h of fasting (Fast). Mitochondrial respiration was measured using high-resolution respirometry in permeabilized muscle fibre bundles to assess substrate oxidation. Whole body fat oxidation increased after both exercise (Rest, 0.96 ± 0.32 kcal min(-1) ; Exercise, 5.66 ± 1.97 kcal min(-1) ; P < 0.001) and fasting (Fed, 0.87 ± 0.51 kcal min(-1) ; Fast, 1.30 ± 0.37 kcal min(-1) , P < 0.05). SIRT3 gene expression decreased (P < 0.05) after both exercise (-8%) and fasting (-19%); however, SIRT3 whole

  10. Fast and parallel spectral transform algorithms for global shallow water models. Doctoral thesis

    SciTech Connect

    Jakob, R.

    1993-01-01

    The dissertation examines spectral transform algorithms for the solution of the shallow water equations on the sphere and studies their implementation and performance on shared memory vector multiprocessors. Beginning with the standard spectral transform algorithm in vorticity divergence form and its implementation in the Fortran based parallel programming language Force, two modifications are researched. First, the transforms and matrices associated with the meridional derivatives of the associated Legendre functions are replaced by corresponding operations with the spherical harmonic coefficients. Second, based on the fast Fourier transform and the fast multipole method, a lower complexity algorithm is derived that uses fast transformations between Legendre and interior Fourier nodes, fast surface spherical truncation and a fast spherical Helmholz solver. Because the global shallow water equations are similar to the horizontal dynamical component of general circulation models, the results can be applied to spectral transform numerical weather prediction and climate models. In general, the derived algorithms may speed up the solution of time dependent partial differential equations in spherical geometry.

  11. Modeling Fast-scan Cyclic Voltammetry Data from Electrically Stimulated Dopamine Neurotransmission Data Using QNsim1.0.

    PubMed

    Harun, Rashed; Grassi, Christine M; Munoz, Miranda J; Wagner, Amy K

    2017-06-05

    Central dopaminergic (DAergic) pathways have an important role in a wide range of functions, such as attention, motivation, and movement. Dopamine (DA) is implicated in diseases and disorders including attention deficit hyperactivity disorder, Parkinson's disease, and traumatic brain injury. Thus, DA neurotransmission and the methods to study it are of intense scientific interest. In vivo fast-scan cyclic voltammetry (FSCV) is a method that allows for selectively monitoring DA concentration changes with fine temporal and spatial resolution. This technique is commonly used in conjunction with electrical stimulations of ascending DAergic pathways to control the impulse flow of dopamine neurotransmission. Although the stimulated DA neurotransmission paradigm can produce robust DA responses with clear morphologies, making them amenable for kinetic analysis, there is still much debate on how to interpret the responses in terms of their DA release and clearance components. To address this concern, a quantitative neurobiological (QN) framework of stimulated DA neurotransmission was recently developed to realistically model the dynamics of DA release and reuptake over the course of a stimulated DA response. The foundations of this model are based on experimental data from stimulated DA neurotransmission and on principles of neurotransmission adopted from various lines of research. The QN model implements 12 parameters related to stimulated DA release and reuptake dynamics to model DA responses. This work describes how to simulate DA responses using QNsim1.0 and also details principles that have been implemented to systematically discern alterations in the stimulated dopamine release and reuptake dynamics.

  12. Fasting plasma triglycerides predict the glycaemic response to treatment of type 2 diabetes by gastric electrical stimulation. A novel lipotoxicity paradigm.

    PubMed

    Lebovitz, H E; Ludvik, B; Yaniv, I; Haddad, W; Schwartz, T; Aviv, R

    2013-06-01

    Non-stimulatory, meal-mediated electrical stimulation of the stomach (TANTALUS-DIAMOND) improves glycaemic control and causes modest weight loss in patients with Type 2 diabetes who are inadequately controlled on oral anti-diabetic medications. The magnitude of the glycaemic response in clinical studies has been variable. A preliminary analysis of data from patients who had completed 6 months of treatment indicated that the glycaemic response to the electrical stimulation was inversely related to the baseline fasting plasma triglyceride level. An analysis of 40 patients who had had detailed longitudinal studies for 12 months. Twenty-two patients with fasting plasma triglycerides ≤ 1.7 mmol/l had mean decreases in HbA1c after 3, 6 and 12 months of gastric contraction modulation treatment of -15 ± 2.1 mmol/mol (-1.39 ± 0.20%), -16 ± 2.2 mmol/mol (-1.48 ± 0.20%) and -14 ± 3.0 mmol/mol (-1.31 ± 0.26%), respectively. In contrast, 18 patients with fasting plasma triglyceride > 1.7 mmol/l had mean decreases in HbA1c of -7 ± 1.7 mmol/mol (-0.66 ± 0.16%), -5 ± 1.6 mmol/mol (-0.44 ± 0.18%) and -5 ± 1.7 mmol/mol (-0.42 ± 0.16%), respectively. Pearson's correlation coefficient between fasting plasma triglyceride and decreases in HbA1c at 12 months of treatment was 0.34 (P < 0.05). Homeostasis model assessment of insulin resistance was unchanged during 12 months of treatment in patients with high baseline fasting triglycerides, while it progressively improved in patients with low fasting plasma triglycerides. Patients with low fasting plasma triglycerides had a tendency to lose more weight than those with high fasting plasma triglycerides, but this did not achieve statistical significance. The data presented suggest the existence of a triglyceride lipotoxic mechanism that interferes with gastric/neural mediated pathways that can regulate glycaemic control in patients with type 2 diabetes. The data suggest the existence of a triglyceride lipotoxic pathway that

  13. Fasting plasma triglycerides predict the glycaemic response to treatment of Type 2 diabetes by gastric electrical stimulation. A novel lipotoxicity paradigm

    PubMed Central

    Lebovitz, H E; Ludvik, B; Yaniv, I; Haddad, W; Schwartz, T; Aviv, R

    2013-01-01

    Background Non-stimulatory, meal-mediated electrical stimulation of the stomach (TANTALUS-DIAMOND) improves glycaemic control and causes modest weight loss in patients with Type 2 diabetes who are inadequately controlled on oral anti-diabetic medications. The magnitude of the glycaemic response in clinical studies has been variable. A preliminary analysis of data from patients who had completed 6 months of treatment indicated that the glycaemic response to the electrical stimulation was inversely related to the baseline fasting plasma triglyceride level. Method An analysis of 40 patients who had had detailed longitudinal studies for 12 months. Results Twenty-two patients with fasting plasma triglycerides ≤ 1.7 mmol/l had mean decreases in HbA1c after 3, 6 and 12 months of gastric contraction modulation treatment of −15 ± 2.1 mmol/mol (−1.39 ± 0.20%), −16 ± 2.2 mmol/mol (−1.48 ± 0.20%) and −14 ± 3.0 mmol/mol (−1.31 ± 0.26%), respectively. In contrast, 18 patients with fasting plasma triglyceride > 1.7 mmol/l had mean decreases in HbA1c of −7 ± 1.7 mmol/mol (−0.66 ± 0.16%), −5 ± 1.6 mmol/mol (−0.44 ± 0.18%) and −5 ± 1.7 mmol/mol (−0.42 ± 0.16%), respectively. Pearson's correlation coefficient between fasting plasma triglyceride and decreases in HbA1c at 12 months of treatment was 0.34 (P < 0.05). Homeostasis model assessment of insulin resistance was unchanged during 12 months of treatment in patients with high baseline fasting triglycerides, while it progressively improved in patients with low fasting plasma triglycerides. Patients with low fasting plasma triglycerides had a tendency to lose more weight than those with high fasting plasma triglycerides, but this did not achieve statistical significance. Conclusions The data presented suggest the existance of a triglyceride lipotoxic mechanism that interferes with gastric/neural mediated pathways that can regulate glycaemic control in patients with type 2 diabetes. The data

  14. A Neutron Star-White Dwarf Binary Model for Repeating Fast Radio Burst 121102

    NASA Astrophysics Data System (ADS)

    Gu, Wei-Min; Dong, Yi-Ze; Liu, Tong; Ma, Renyi; Wang, Junfeng

    2016-06-01

    We propose a compact binary model for the fast radio burst (FRB) repeaters, where the system consists of a magnetic white dwarf (WD) and a neutron star (NS) with strong bipolar magnetic fields. When the WD fills its Roche lobe, mass transfer will occur from the WD to the NS through the inner Lagrange point. The accreted magnetized materials may trigger magnetic reconnection when they approach the NS surface, and therefore the electrons can be accelerated to an ultra-relativistic speed. In this scenario, the curvature radiation of the electrons moving along the NS magnetic field lines can account for the characteristic frequency and the timescale of an FRB. Owing to the conservation of angular momentum, the WD may be kicked away after a burst, and the next burst may appear when the system becomes semi-detached again through the gravitational radiation. By comparing our analyses with the observations, we show that such an intermittent Roche-lobe overflow mechanism can be responsible for the observed repeating behavior of FRB 121102.

  15. Fast approximate EM induction modeling of metallic and UXO targets using a permeable prism

    NASA Astrophysics Data System (ADS)

    Asten, Michael W.; Duncan, Andrew C.

    2007-03-01

    The time-domain EM induction response of non-magnetic and magnetic targets can be approximated using a conductive permeable prism composed of six faces of conductive plates, each face being composed of a set of conductive ribbons. The effect of magnetic permeability is included by the use of two "apparent flux gathering" coefficients, and two "effective magnetic permeability" coefficients, in the axial and transverse directions. These four magnetic property coefficients are a function of physical properties and geometry of the target, but are independent of prism orientation relative to a transmitter. The approximation algorithm is computationally fast, allowing inversions for target parameters to be achieved in seconds. The model is tested on profiles acquired with a Geonics EM63 time-domain EM metal detector over a non-magnetic copper pipe target, and a steel artillery shell in horizontal and vertical orientations. Results show that this approximation to a permeable prism has a capability of fitting geometric, conductivity and magnetic parameters at both early and late sample times. The magnetic parameters show strong change from early to late times on the EMI decay curve, indicating that the magnetic properties of the target have non-linear characteristics. It is proposed that these magnetic parameters and the nature of their non-linearity may carry additional discrimination information for distinguishing between intact munitions and scrap in UXO studies.

  16. Continuous Evaluation of Fast Processes in Climate Models Using Arm Measurements

    SciTech Connect

    Zhang, Minghua

    2015-01-02

    Under the support of this grant, we investigated the fast process of interaction of clouds, shallow convection, and boundary layer turbulence and their parameterizations. Main accomplishments involve two things. One is the understanding of the physical mechanisms of low cloud feedbacks; the second is the development and evaluation of convection and cloud parameterizations in climate models.

  17. Psychological Plausibility of the Theory of Probabilistic Mental Models and the Fast and Frugal Heuristics

    ERIC Educational Resources Information Center

    Dougherty, Michael R.; Franco-Watkins, Ana M.; Thomas, Rick

    2008-01-01

    The theory of probabilistic mental models (PMM; G. Gigerenzer, U. Hoffrage, & H. Kleinbolting, 1991) has had a major influence on the field of judgment and decision making, with the most recent important modifications to PMM theory being the identification of several fast and frugal heuristics (G. Gigerenzer & D. G. Goldstein, 1996). These…

  18. Psychological Plausibility of the Theory of Probabilistic Mental Models and the Fast and Frugal Heuristics

    ERIC Educational Resources Information Center

    Dougherty, Michael R.; Franco-Watkins, Ana M.; Thomas, Rick

    2008-01-01

    The theory of probabilistic mental models (PMM; G. Gigerenzer, U. Hoffrage, & H. Kleinbolting, 1991) has had a major influence on the field of judgment and decision making, with the most recent important modifications to PMM theory being the identification of several fast and frugal heuristics (G. Gigerenzer & D. G. Goldstein, 1996). These…

  19. Acceleration through a Holistic Support Model: An Implementation and Outcomes Analysis of FastStart@CCD

    ERIC Educational Resources Information Center

    Edgecombe, Nikki; Jaggars, Shanna Smith; Baker, Elaine DeLott; Bailey, Thomas

    2013-01-01

    Originally designed for students who test into at least two levels of developmental education in a particular subject area, FastStart is a compressed course program model launched in 2005 at the Community College of Denver (CCD). The program combines multiple semester-length courses into a single intensive semester, while providing case…

  20. Cell-autonomous regulation of fast troponin T pre-mRNA alternative splicing in response to mechanical stretch.

    PubMed

    Schilder, Rudolf J; Kimball, Scot R; Jefferson, Leonard S

    2012-08-01

    How mechanochemical signals induced by the amount of weight borne by the skeletal musculature are translated into modifications to muscle sarcomeres is poorly understood. Our laboratory recently demonstrated that, in response to experimentally induced increases in the weight load borne by a rat, alternative splicing of the fast skeletal muscle troponin T (Tnnt3) pre-mRNA in gastrocnemius was adjusted in a correlated fashion with the amount of added weight. (Schilder RJ, Kimball SR, Marden JH, Jefferson LS. J Exp Biol 214: 1523-1532, 2011). Thus muscle load is perceived quantitatively by the body, and mechanisms that sense it appear to control processes that generate muscle sarcomere composition plasticity, such as alternative pre-mRNA splicing. Here we demonstrate how mechanical stretch (see earlier comment) of C2C12 muscle cells in culture results in changes to Tnnt3 pre-mRNA alternative splicing that are qualitatively similar to those observed in response to added weight in rats. Moreover, inhibition of Akt signaling, but not that of ERK1/2, prevents the stretch-induced effect on Tnnt3 pre-mRNA alternative splicing. These findings suggest that effects of muscle load on Tnnt3 pre-mRNA alternative splicing are controlled by a cell-autonomous mechanism, rather than systemically. They also indicate that, in addition to its regulatory role in protein synthesis and muscle mass plasticity, Akt signaling may regulate muscle sarcomere composition by modulating alternative splicing events in response to load. Manipulation of Tnnt3 pre-mRNA alternative splicing by mechanical stretch of cells in culture provides a model to investigate the biology of weight sensing by skeletal muscles and facilitates identification of mechanisms through which skeletal muscles match their performance and experienced load.

  1. Teaching about Heterogeneous Response Models

    ERIC Educational Resources Information Center

    Murray, Michael P.

    2014-01-01

    Individuals vary in their responses to incentives and opportunities. For example, additional education will affect one person differently than another. In recent years, econometricians have given increased attention to such heterogeneous responses and to the consequences of such responses for interpreting regression estimates, especially…

  2. α-Adrenoceptor constrictor responses and their modulation in slow-twitch and fast-twitch mouse skeletal muscle

    PubMed Central

    Lambert, David G; Thomas, Gail D

    2005-01-01

    Vasoconstrictor responses to sympathetic nerve stimulation and their sensitivity to metabolic modulation reportedly differ in fast-twitch and slow-twitch muscles, but the underlying mechanisms are not known. Both α1- and α2-adrenoceptors mediate these vascular responses in fast-twitch muscle, while their roles in slow-twitch muscle are less well defined. In this study, the phosphorylation of smooth muscle myosin regulatory light chain (smRLC) was measured as an index of vasoconstriction in slow-twitch soleus muscles and fast-twitch extensor digitorum longus (EDL) muscles isolated from C57BL/6J mice. In soleus muscles, incubation with phenylephrine (PE) or UK 14,304 to selectively activate α1- or α2-adrenoceptors resulted in concentration-dependent increases in smRLC phosphorylation. To evaluate metabolic modulation of these responses, vasodilator pathways previously implicated in such modulation in fast-twitch muscle were activated in soleus muscles by treatment with the nitric oxide (NO) donor nitroprusside or the ATP-sensitive potassium (KATP) channel opener cromakalim. Both drugs inhibited responses to UK 14,304, but not to PE. The effect of nitroprusside to antagonize UK 14,304 responses was prevented by inhibition of guanylyl cyclase or by blockade of KATP channels, but not by blockade of other potassium channels. Results were similar in EDL muscles. These data provide the first evidence for α2-adrenoceptor-mediated constriction in slow-twitch muscle, and show that it is sensitive to modulation by NO via a cGMP-dependent mechanism that requires KATP channel activation. Based on the similar findings in soleus and EDL muscles, fibre type does not appear to determine the innate vascular response to α1- or α2-adrenoceptor activation. PMID:15618269

  3. Effect of extended morning fasting upon ad libitum lunch intake and associated metabolic and hormonal responses in obese adults.

    PubMed

    Chowdhury, E A; Richardson, J D; Tsintzas, K; Thompson, D; Betts, J A

    2016-02-01

    Breakfast omission is positively associated with obesity and increased risk of disease. However, little is known about the acute effects of extended morning fasting upon subsequent energy intake and associated metabolic/regulatory factors in obese adults. In a randomised cross-over design, 24 obese men (n=8) and women (n=16) extended their overnight fast by omitting breakfast consumption or ingesting a typical carbohydrate-rich breakfast of 2183±393 kJ (521±94 kcal), before an ad libitum pasta lunch 3 h later. Blood samples were obtained throughout the day until 3 h post lunch and analysed for hormones implicated in appetite regulation, along with metabolic outcomes and subjective appetite measures. Lunch intake was unaffected by extended morning fasting (difference=218 kJ, 95% confidence interval -54 kJ, 490 kJ; P=0.1) resulting in lower total intake in the fasting trial (difference=-1964 kJ, 95% confidence interval -1645 kJ, -2281 kJ; P<0.01). Systemic concentrations of peptide tyrosine-tyrosine and leptin were lower during the afternoon following morning fasting (P⩽0.06). Plasma-acylated ghrelin concentrations were also lower following the ad libitum lunch in the fasting trial (P<0.05) but this effect was not apparent for total ghrelin (P⩾0.1). Serum insulin concentrations were greater throughout the afternoon in the fasting trial (P=0.05), with plasma glucose also greater 1 h after lunch (P<0.01). Extended morning fasting did not result in greater appetite ratings after lunch, with some tendency for lower appetite 3 h post lunch (P=0.09). We demonstrate for the first time that, in obese adults, extended morning fasting does not cause compensatory intake during an ad libitum lunch nor does it increase appetite during the afternoon. Morning fasting reduced satiety hormone responses to a subsequent lunch meal but counterintuitively also reduced concentrations of the appetite-stimulating hormone-acylated ghrelin during the afternoon

  4. Effect of extended morning fasting upon ad libitum lunch intake and associated metabolic and hormonal responses in obese adults

    PubMed Central

    Chowdhury, E A; Richardson, J D; Tsintzas, K; Thompson, D; Betts, J A

    2016-01-01

    Background/Objectives: Breakfast omission is positively associated with obesity and increased risk of disease. However, little is known about the acute effects of extended morning fasting upon subsequent energy intake and associated metabolic/regulatory factors in obese adults. Subjects/Methods: In a randomised cross-over design, 24 obese men (n=8) and women (n=16) extended their overnight fast by omitting breakfast consumption or ingesting a typical carbohydrate-rich breakfast of 2183±393 kJ (521±94 kcal), before an ad libitum pasta lunch 3 h later. Blood samples were obtained throughout the day until 3 h post lunch and analysed for hormones implicated in appetite regulation, along with metabolic outcomes and subjective appetite measures. Results: Lunch intake was unaffected by extended morning fasting (difference=218 kJ, 95% confidence interval −54 kJ, 490 kJ; P=0.1) resulting in lower total intake in the fasting trial (difference=−1964 kJ, 95% confidence interval −1645 kJ, −2281 kJ; P<0.01). Systemic concentrations of peptide tyrosine–tyrosine and leptin were lower during the afternoon following morning fasting (P⩽0.06). Plasma-acylated ghrelin concentrations were also lower following the ad libitum lunch in the fasting trial (P<0.05) but this effect was not apparent for total ghrelin (P⩾0.1). Serum insulin concentrations were greater throughout the afternoon in the fasting trial (P=0.05), with plasma glucose also greater 1 h after lunch (P<0.01). Extended morning fasting did not result in greater appetite ratings after lunch, with some tendency for lower appetite 3 h post lunch (P=0.09). Conclusions: We demonstrate for the first time that, in obese adults, extended morning fasting does not cause compensatory intake during an ad libitum lunch nor does it increase appetite during the afternoon. Morning fasting reduced satiety hormone responses to a subsequent lunch meal but counterintuitively also reduced concentrations of

  5. Extending food deprivation reverses the short-term lipolytic response to fasting: role of the triacylglycerol/fatty acid cycle.

    PubMed

    Weber, Jean-Michel; Reidy, Shannon P

    2012-05-01

    The effects of short-term food deprivation on lipid metabolism are well documented, but little is known about prolonged fasting. This study monitored the kinetics of glycerol (rate of appearance, R(a) glycerol) and non-esterified fatty acids (R(a) NEFA) in fasting rabbits. Our goals were to determine whether lipolysis is stimulated beyond values seen for short-term fasting, and to characterize the roles of primary (intracellular) and secondary (with transit through the circulation) triacylglycerol/fatty acid cycling (TAG/FA cycling) in regulating fatty acid allocation to oxidation or re-esterification. R(a) glycerol (9.62±0.72 to 15.29±0.96 μmol kg(-1) min(-1)) and R(a) NEFA (18.05±2.55 to 31.25±1.93 μmol kg(-1) min(-1)) were stimulated during the first 2 days of fasting, but returned to baseline after 4 days. An initial increase in TAG/FA cycling was followed by a reduction below baseline after 6 days without food, with primary and secondary cycling contributing to these responses. We conclude that the classic activation of lipolysis caused by short-term fasting is abolished when food deprivation is prolonged. High rates of re-esterification may become impossible to sustain, and TAG/FA cycling could decrease to reduce its cost to 3% of total energy expenditure. Throughout prolonged fasting, fatty acid metabolism gradually shifts towards increased oxidation and reduced re-esterification. Survival is achieved by pressing fuel selection towards the fatty acid dominance of energy metabolism and by slowing substrate cycles to assist metabolic suppression. However, TAG/FA cycling remains active even after prolonged fasting, suggesting that re-esterification is a crucial mechanism that cannot be stopped without harmful consequences.

  6. Fast and accurate calculation of dilute quantum gas using Uehling-Uhlenbeck model equation

    NASA Astrophysics Data System (ADS)

    Yano, Ryosuke

    2017-02-01

    The Uehling-Uhlenbeck (U-U) model equation is studied for the fast and accurate calculation of a dilute quantum gas. In particular, the direct simulation Monte Carlo (DSMC) method is used to solve the U-U model equation. DSMC analysis based on the U-U model equation is expected to enable the thermalization to be accurately obtained using a small number of sample particles and the dilute quantum gas dynamics to be calculated in a practical time. Finally, the applicability of DSMC analysis based on the U-U model equation to the fast and accurate calculation of a dilute quantum gas is confirmed by calculating the viscosity coefficient of a Bose gas on the basis of the Green-Kubo expression and the shock layer of a dilute Bose gas around a cylinder.

  7. Using elastic ice fracture parameterizations to model land-fast ice bridges

    NASA Astrophysics Data System (ADS)

    Plante, Mathieu; Tremblay, Bruno

    2017-04-01

    Land-fast ice is an important component of the Arctic system, yet its representation in large-scale sea ice models remains a challenge, partly due to the difficult parameterization of the ice fracture. This project focuses on both the observation and modelling of ice bridges in narrow channels in the absence of grounded ice ridges. MODIS brightness temperature imagery is used to show the succession of ice bridge stabilisations that shapes the land-fast ice in the Parry Channel. A 2D linear elastic model is also developed to simulates the ice fracture in an idealised channel. The model is able to produce ice bridges that are sensitive to the choice of failure criterion. The different conditions that lead to the formation of a stable ice arch downstream of a channel (in divergent stress conditions) or unstable arches upstream of a channel (in convergent stress conditions) are also presented.

  8. Two-dimensional models of early-type fast rotating stars: new challenges in stellar physics

    NASA Astrophysics Data System (ADS)

    Rieutord, M.; Espinosa Lara, F.

    2013-12-01

    Two-dimensional models of rapidly rotating stars are already unavoidable for the interpretation of interferometric or asteroseismic data of this kind of stars. When combined with time evolution, they will allow the including of a more accurate physics for the computation of element transport and the determination of surface abundances. In addition, modeling the evolution of rotation will improve gyrochronology. Presently, two-dimensional ESTER models predict the structure and the large-scale flows (differential rotation and meridional circulation) of stars with mass larger than 1.7 M⊙ at any rotation rate. Main sequence evolution can be mimicked by varying the hydrogen content of the convective core. Models have been successfully tested on half a dozen of nearby fast rotating stars observed with optical or infra-red interferometers. They are now the right tool to investigate the oscillation spectrum of early-type fast rotators.

  9. Fast 3D spine reconstruction of postoperative patients using a multilevel statistical model.

    PubMed

    Lecron, Fabian; Boisvert, Jonathan; Mahmoudi, Saïd; Labelle, Hubert; Benjelloun, Mohammed

    2012-01-01

    Severe cases of spinal deformities such as scoliosis are usually treated by a surgery where instrumentation (hooks, screws and rods) is installed to the spine to correct deformities. Even if the purpose is to obtain a normal spine curve, the result is often straighter than normal. In this paper, we propose a fast statistical reconstruction algorithm based on a general model which can deal with such instrumented spines. To this end, we present the concept of multilevel statistical model where the data are decomposed into a within-group and a between-group component. The reconstruction procedure is formulated as a second-order cone program which can be solved very fast (few tenths of a second). Reconstruction errors were evaluated on real patient data and results showed that multilevel modeling allows better 3D reconstruction than classical models.

  10. Pathogenic accumulation of APP in fast twitch muscle of IBM patients and a transgenic model.

    PubMed

    Sugarman, Michael C; Kitazawa, Masashi; Baker, Michael; Caiozzo, Vincent J; Querfurth, Henry W; LaFerla, Frank M

    2006-03-01

    Inclusion body myositis (IBM) is the most common age-related degenerative skeletal muscle disorder. The aberrant intracellular accumulation of the beta-amyloid (Abeta) peptide within skeletal muscle is a pathological hallmark of IBM. Skeletal muscle is comprised of both slow and fast twitch fibers, which are present in different proportions in various muscles. It remains unclear if fast and/or slow twitch fibers are differentially involved in IBM pathogenesis. To better understand the molecular pathogenesis of IBM, we analyzed human IBM muscle biopsies and muscle from a transgenic mouse model of IBM (MCK-betaAPP). Here we report that the majority of histopathologically-affected fibers in human IBM biopsies were type II fast fibers. Skeletal muscle from MCK-betaAPP mice exhibited higher transgene expression and steady-state levels of human betaAPP in fast type IIB fibers compared to slow type I fibers. These findings indicate that fast twitch fibers may selectively accumulate and be more vulnerable to betaAPP- and Abeta-mediated damage in IBM. These findings also highlight parallels between the MCK-betaAPP mice and the human IBM condition.

  11. Linear discrete population models with two time scales in fast changing environments I: autonomous case.

    PubMed

    Blasco, A; Sanz, L; Auger, P; Bravo de la Parra, R

    2001-01-01

    In this work we consider a structured population with groups and subgroups of individuals. The intra-group dynamics is assumed to be fast in comparison with the inter-group dynamics. We study linear discrete models where the slow dynamics is represented by a single matrix and the fast dynamics is described by means of the first k terms of a converging sequence of different matrices. The number k can be interpreted as the ratio between the two time scales. The aim of this work is to extend aggregation techniques to the case of fast changing environments. The main idea of aggregation is to build up a new system, with lower dimension, that summarizes the information concerning the fast process. This "aggregated" system provides essential information on the original one. It is shown that the asymptotic behavior of the original system can be approximated by the asymptotic behavior of the aggregated system when the ratio between the two time scales is large enough. We present an example of an age structured population in a patchy environment. The migration process is assumed to be fast in comparison with the demographic process. Numerical simulations illustrate that the asymptotic growth rate and the stable age distribution of the population in the original and the aggregated systems are getting closer as the ratio k increases.

  12. Fast assessment of structural models of ion channels based on their predicted current-voltage characteristics.

    PubMed

    Dyrka, Witold; Kurczyńska, Monika; Konopka, Bogumił M; Kotulska, Małgorzata

    2016-02-01

    Computational prediction of protein structures is a difficult task, which involves fast and accurate evaluation of candidate model structures. We propose to enhance single-model quality assessment with a functionality evaluation phase for proteins whose quantitative functional characteristics are known. In particular, this idea can be applied to evaluation of structural models of ion channels, whose main function - conducting ions - can be quantitatively measured with the patch-clamp technique providing the current-voltage characteristics. The study was performed on a set of KcsA channel models obtained from complete and incomplete contact maps. A fast continuous electrodiffusion model was used for calculating the current-voltage characteristics of structural models. We found that the computed charge selectivity and total current were sensitive to structural and electrostatic quality of models. In practical terms, we show that evaluating predicted conductance values is an appropriate method to eliminate models with an occluded pore or with multiple erroneously created pores. Moreover, filtering models on the basis of their predicted charge selectivity results in a substantial enrichment of the candidate set in highly accurate models. Tests on three other ion channels indicate that, in addition to being a proof of the concept, our function-oriented single-model quality assessment method can be directly applied to evaluation of structural models of some classes of protein channels. Finally, our work raises an important question whether a computational validation of functionality should be included in the evaluation process of structural models, whenever possible. © 2015 Wiley Periodicals, Inc.

  13. Intermittent fasting could ameliorate cognitive function against distress by regulation of inflammatory response pathway.

    PubMed

    Shojaie, Marjan; Ghanbari, Farzane; Shojaie, Nasrin

    2017-11-01

    Undesirable and desirable effects of stressors on the body are assigned to distress and eustress, respectively. Immune system and brain are the most susceptible parts to stressful conditions, whereas long-lasting alterations in putative immune proteins involved in tension such as corticosterone (CORT), interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNF-α) can impact learning and memory. Intermittent fasting (IF) is a repeated regular cycle of dietary restriction with well-known beneficial properties on the body. The aim of this study was to identify the eustress effects of IF on cognitive function by assessing the critical inflammatory factors in chronic distress. Forty male mice were divided into four groups (n = 10/group). Distress and control normally received food and water, whereas IF and IF with distress groups were daily deprived of food and water for two hours. In the second week, the electrical foot shock was induced to distress and IF with distress groups. Finally, the cognitive functions of all mice were evaluated by Barnes maze, their blood samples were taken to determine the plasma level of CORT, IL-6 and TNF-α, and the removed brain and adrenal glands were weighed in the third week. A significant gain in plasma level of CORT, IL-6 and TNF-α with a considerable brain hypotrophy and adrenal hypertrophy was found in distress group, whereas IF caused a remarkable reduction of the plasma inflammatory factors, especially in IF with distress mice (P ≤ 0.05). In conclusion, IF could improve cognitive function and preserve the brain against distress by regulation of inflammatory response pathway.

  14. Experiments and numerical modeling of fast flowing liquid metal thin films under spatially varying magnetic field conditions

    NASA Astrophysics Data System (ADS)

    Narula, Manmeet Singh

    Innovative concepts using fast flowing thin films of liquid metals (like lithium) have been proposed for the protection of the divertor surface in magnetic fusion devices. However, concerns exist about the possibility of establishing the required flow of liquid metal thin films because of the presence of strong magnetic fields which can cause flow disrupting MHD effects. A plan is underway to design liquid lithium based divertor protection concepts for NSTX, a small spherical torus experiment at Princeton. Of these, a promising concept is the use of modularized fast flowing liquid lithium film zones, as the divertor (called the NSTX liquid surface module concept or NSTX LSM). The dynamic response of the liquid metal film flow in a spatially varying magnetic field configuration is still unknown and it is suspected that some unpredicted effects might be lurking. The primary goal of the research work being reported in this dissertation is to provide qualitative and quantitative information on the liquid metal film flow dynamics under spatially varying magnetic field conditions, typical of the divertor region of a magnetic fusion device. The liquid metal film flow dynamics have been studied through a synergic experimental and numerical modeling effort. The Magneto Thermofluid Omnibus Research (MTOR) facility at UCLA has been used to design several experiments to study the MHD interaction of liquid gallium films under a scaled NSTX outboard divertor magnetic field environment. A 3D multi-material, free surface MHD modeling capability is under development in collaboration with HyPerComp Inc., an SBIR vendor. This numerical code called HIMAG provides a unique capability to model the equations of incompressible MHD with a free surface. Some parts of this modeling capability have been developed in this research work, in the form of subroutines for HIMAG. Extensive code debugging and benchmarking exercise has also been carried out. Finally, HIMAG has been used to study the

  15. The ultraviolet photoconductive detector based on Al-doped ZnO thin film with fast response

    NASA Astrophysics Data System (ADS)

    Sun, Jian; Dai, Qian; Liu, FengJuan; Huang, HaiQin; Li, ZhenJun; Zhang, XiQing; Wang, YongSheng

    2011-01-01

    We report fabrication and characterization of metal-semiconductor-metal photoconductive detectors based on Al-doped ZnO thin films fabricated by radio frequency magnetron sputtering. Optical and structural properties of the thin films were characterized using various techniques. At 6 V bias, a responsivity higher than 4 A/W in the wavelength shorter than 350 nm was obtained, and this responsibility dropped quickly and reached the noise floor in the visible region. Transient response measurement revealed that the detector had a fast photoresponse with a rise time of 9 ns and a fall time of 1.2 μs.

  16. Are Live Ultrasound Models Replaceable? Traditional versus Simulated Education Module for FAST Exam.

    PubMed

    Bentley, Suzanne; Mudan, Gurpreet; Strother, Christopher; Wong, Nelson

    2015-11-01

    The focused assessment with sonography for trauma (FAST) is a commonly used and life-saving tool in the initial assessment of trauma patients. The recommended emergency medicine (EM) curriculum includes ultrasound and studies show the additional utility of ultrasound training for medical students. EM clerkships vary and often do not contain formal ultrasound instruction. Time constraints for facilitating lectures and hands-on learning of ultrasound are challenging. Limitations on didactics call for development and inclusion of novel educational strategies, such as simulation. The objective of this study was to compare the test, survey, and performance of ultrasound between medical students trained on an ultrasound simulator versus those trained via traditional, hands-on patient format. This was a prospective, blinded, controlled educational study focused on EM clerkship medical students. After all received a standardized lecture with pictorial demonstration of image acquisition, students were randomized into two groups: control group receiving traditional training method via practice on a human model and intervention group training via practice on an ultrasound simulator. Participants were tested and surveyed on indications and interpretation of FAST and training and confidence with image interpretation and acquisition before and after this educational activity. Evaluation of FAST skills was performed on a human model to emulate patient care and practical skills were scored via objective structured clinical examination (OSCE) with critical action checklist. There was no significant difference between control group (N=54) and intervention group (N=39) on pretest scores, prior ultrasound training/education, or ultrasound comfort level in general or on FAST. All students (N=93) showed significant improvement from pre- to post-test scores and significant improvement in comfort level using ultrasound in general and on FAST (p<0.001). There was no significant difference

  17. Fast magnetic response in gigahertz-band for columnar-structured Fe nanoparticle assembly

    SciTech Connect

    Ogawa, T. Tate, R.; Kura, H.; Oikawa, T.; Hata, K.

    2014-05-07

    High density Fe-based ferromagnetic nanoparticle (NP) assembly is expected to have unique magnetic properties, such as superferromagnetism and super-spin-glass, different from magnetically isolated NP systems due to strong dipole interactions among the NPs. A high dipole interaction field, H{sub dip}, of ∼3.5 kOe can result in a high effective internal field to the magnetic moment of the NP, expecting for ultra-fast magnetic response, that is, a high magnetic resonance frequency, f{sub r}, of ∼10 GHz. However, for a simply molded Fe NP assembly, a low f{sub r} was observed due to inhomogeneous distribution of the internal field, implying the necessity of a unidirectional state of H{sub dip} for higher f{sub r}. In this study, we fabricated a columnar Fe NP assembly for realizing the unidirectional state of H{sub dip} by applying our uniquely developed external field-induced agglomeration method for monodispersed Fe NPs (13 nm in average size) as a function of the field (0–30 kOe) and volume fraction of the Fe NPs (0.5%–51%) in a polymer matrix with dimensions of 4 mm × 4 mm × 0.7 mm{sup t}. A columnar-structured Fe NP assembly was successfully achieved along an in-plane direction (defined as the x-axis) under optimized conditions. From static magnetization curves, induced uniaxial magnetic anisotropy was observed according to the shape of the columnar structure of the Fe NP assembly, where easy and hard axes of magnetization were realized along the parallel (x-axis) and normal directions (in-plane y-axis and z-axis in the thickness direction) to the external field during the process, respectively. Interestingly, this fabricated columnar-structured Fe NP assembly exhibited very high f{sub r} in the range from 3 to 11 GHz judging from the complex susceptibility spectra obtained. The f{sub r} values were well-scaled by a modified Snoek's-limit-law using demagnetization factors quantitatively estimated from the static magnetization curves. Thus, shape

  18. Retrieving ice cloud properties by using a fast infrared radiative transfer model

    NASA Astrophysics Data System (ADS)

    Wang, C.; Yang, P.; Heidinger, A. K.; Platnick, S. E.; Baum, B. A.

    2010-12-01

    A new fast infrared radiative transfer (RT) model based on pre-computed look-up tables (LUTs) including the LUTs for emissivity function and cloud effective temperature is proposed. This model can be applied to the simulation of upward radiance (or brightness temperature) at 8.5, 11.0 and 12.0 μm at the top of the atmosphere (TOA) under cloudy-sky conditions. Optical depths of Atmospheric layers resulting from gaseous absorption are derived from the correlated-K distribution (CKD) method. The cloud reflection and transmission functions are computed from the discrete ordinates radiative transfer model (DISORT). In addition to the LUTs of reflection and transmission functions of cloud in traditional RT models, the LUTs of emissivity and effective temperature are also included to improve the accuracy. Generally speaking, for an atmosphere containing a single ice cloud layer with small optical thickness (i.e., less than 5.0), the brightness temperature differences (BTDs) between the fast model and DISORT results are approximately less than 0.1K, whereas the BTDs are less than 0.02K when the ice cloud optical thickness is larger than 5.0. Moreover, with the fast RT model, cloud optical and microphysical properties of ice clouds are retrieved from MODIS and CALIPSO observations and the MERRA reanalysis data. The present retrievals are compared with the MODIS operational cloud products (MYD06).

  19. The Development of a 3D LADAR Simulator Based on a Fast Target Impulse Response Generation Approach

    NASA Astrophysics Data System (ADS)

    Al-Temeemy, Ali Adnan

    2017-09-01

    A new laser detection and ranging (LADAR) simulator has been developed, using MATLAB and its graphical user interface, to simulate direct detection time of flight LADAR systems, and to produce 3D simulated scanning images under a wide variety of conditions. This simulator models each stage from the laser source to data generation and can be considered as an efficient simulation tool to use when developing LADAR systems and their data processing algorithms. The novel approach proposed for this simulator is to generate the actual target impulse response. This approach is fast and able to deal with high scanning requirements without losing the fidelity that accompanies increments in speed. This leads to a more efficient LADAR simulator and opens up the possibility for simulating LADAR beam propagation more accurately by using a large number of laser footprint samples. The approach is to select only the parts of the target that lie in the laser beam angular field by mathematically deriving the required equations and calculating the target angular ranges. The performance of the new simulator has been evaluated under different scanning conditions, the results showing significant increments in processing speeds in comparison to conventional approaches, which are also used in this study as a point of comparison for the results. The results also show the simulator's ability to simulate phenomena related to the scanning process, for example, type of noise, scanning resolution and laser beam width.

  20. Fast response air-to-fuel ratio measurements using a novel device based on a wide band lambda sensor

    NASA Astrophysics Data System (ADS)

    Regitz, S.; Collings, N.

    2008-07-01

    A crucial parameter influencing the formation of pollutant gases in internal combustion engines is the air-to-fuel ratio (AFR). During transients on gasoline and diesel engines, significant AFR excursions from target values can occur, but cycle-by-cycle AFR resolution, which is helpful in understanding the origin of deviations, is difficult to achieve with existing hardware. This is because current electrochemical devices such as universal exhaust gas oxygen (UEGO) sensors have a time constant of 50-100 ms, depending on the engine running conditions. This paper describes the development of a fast reacting device based on a wide band lambda sensor which has a maximum time constant of ~20 ms and enables cyclic AFR measurements for engine speeds of up to ~4000 rpm. The design incorporates a controlled sensor environment which results in insensitivity to sample temperature and pressure. In order to guide the development process, a computational model was developed to predict the effect of pressure and temperature on the diffusion mechanism. Investigations regarding the sensor output and response were carried out, and sensitivities to temperature and pressure are examined. Finally, engine measurements are presented.

  1. ModelOMatic: fast and automated model selection between RY, nucleotide, amino acid, and codon substitution models.

    PubMed

    Whelan, Simon; Allen, James E; Blackburne, Benjamin P; Talavera, David

    2015-01-01

    Molecular phylogenetics is a powerful tool for inferring both the process and pattern of evolution from genomic sequence data. Statistical approaches, such as maximum likelihood and Bayesian inference, are now established as the preferred methods of inference. The choice of models that a researcher uses for inference is of critical importance, and there are established methods for model selection conditioned on a particular type of data, such as nucleotides, amino acids, or codons. A major limitation of existing model selection approaches is that they can only compare models acting upon a single type of data. Here, we extend model selection to allow comparisons between models describing different types of data by introducing the idea of adapter functions, which project aggregated models onto the originally observed sequence data. These projections are implemented in the program ModelOMatic and used to perform model selection on 3722 families from the PANDIT database, 68 genes from an arthropod phylogenomic data set, and 248 genes from a vertebrate phylogenomic data set. For the PANDIT and arthropod data, we find that amino acid models are selected for the overwhelming majority of alignments; with progressively smaller numbers of alignments selecting codon and nucleotide models, and no families selecting RY-based models. In contrast, nearly all alignments from the vertebrate data set select codon-based models. The sequence divergence, the number of sequences, and the degree of selection acting upon the protein sequences may contribute to explaining this variation in model selection. Our ModelOMatic program is fast, with most families from PANDIT taking fewer than 150 s to complete, and should therefore be easily incorporated into existing phylogenetic pipelines. ModelOMatic is available at https://code.google.com/p/modelomatic/.

  2. Adaptive responses of GLUT-4 and citrate synthase in fast-twitch muscle of voluntary running rats

    NASA Technical Reports Server (NTRS)

    Henriksen, E. J.; Halseth, A. E.

    1995-01-01

    Glucose transporter (GLUT-4) protein, hexokinase, and citrate synthase (proteins involved in oxidative energy production from blood glucose catabolism) increase in response to chronically elevated neuromuscular activity. It is currently unclear whether these proteins increase in a coordinated manner in response to this stimulus. Therefore, voluntary wheel running (WR) was used to chronically overload the fast-twitch rat plantaris muscle and the myocardium, and the early time courses of adaptative responses of GLUT-4 protein and the activities of hexokinase and citrate synthase were characterized and compared. Plantaris hexokinase activity increased 51% after just 1 wk of WR, whereas GLUT-4 and citrate synthase were increased by 51 and 40%, respectively, only after 2 wk of WR. All three variables remained comparably elevated (+50-64%) through 4 wk of WR. Despite the overload of the myocardium with this protocol, no substantial elevations in these variables were observed. These findings are consistent with a coordinated upregulation of GLUT-4 and citrate synthase in the fast-twitch plantaris, but not in the myocardium, in response to this increased neuromuscular activity. Regulation of hexokinase in fast-twitch muscle appears to be uncoupled from regulation of GLUT-4 and citrate synthase, as increases in the former are detectable well before increases in the latter.

  3. Expression of the fusogenic p14 FAST protein from a replication-defective adenovirus vector does not provide a therapeutic benefit in an immunocompetent mouse model of cancer

    PubMed Central

    Wong, C M; Nash, L A; Del Papa, J; Poulin, K L; Falls, T; Bell, J C; Parks, R J

    2016-01-01

    When injected directly into a tumor mass, adenovirus (Ad) vectors only transduce cells immediately along the injection tract. Expression of fusogenic proteins from the Ad vector can lead to syncytium formation, which efficiently spreads the therapeutic effect. Fusogenic proteins can also cause cancer cell death directly, and enhance the release of exosome-like particles containing tumor-associated antigens, which boosts the anti-tumor immune response. In this study, we have examined whether delivery of an early region 1 (E1)-deleted, replication-defective Ad vector encoding the reptilian reovirus p14 fusion-associated small transmembrane (FAST) protein can provide therapeutic efficacy in an immunocompetent mouse tumor model. A high multiplicity of infection of AdFAST is required to induce cell fusion in mouse mammary carcinoma 4T1 cells in vitro, and FAST protein expression caused a modest reduction in cell membrane integrity and metabolic activity compared with cells infected with a control vector. Cells expressing FAST protein released significantly higher quantities of exosomes. In immunocompetent Balb/C mice harboring subcutaneous 4T1 tumors, AdFAST did not induce detectable cancer cell fusion, promote tumor regression or prolong mouse survival compared with untreated mice. This study suggests that in the context of the 4T1 model, Ad-mediated FAST protein expression did not elicit a therapeutic effect. PMID:27740615

  4. STRESS RESPONSE STUDIES USING ANIMAL MODELS

    EPA Science Inventory

    This presentation will provide the evidence that ozone exposure in animal models induce neuroendocrine stress response and this stress response modulates lung injury and inflammation through adrenergic and glucocorticoid receptors.

  5. Computational fluid dynamics modelling of biomass fast pyrolysis in fluidised bed reactors, focusing different kinetic schemes.