Scaling analysis of gas-liquid two-phase flow pattern in microgravity

NASA Technical Reports Server (NTRS)

Lee, Jinho

1993-01-01

A scaling analysis of gas-liquid two-phase flow pattern in microgravity, based on the dominant physical mechanism, was carried out with the goal of predicting the gas-liquid two-phase flow regime in a pipe under conditions of microgravity. The results demonstrated the effect of inlet geometry on the flow regime transition. A comparison of the predictions with existing experimental data showed good agreement.

Chaotic phase synchronization in bursting-neuron models driven by a weak periodic force

NASA Astrophysics Data System (ADS)

Ando, Hiroyasu; Suetani, Hiromichi; Kurths, Jürgen; Aihara, Kazuyuki

2012-07-01

We investigate the entrainment of a neuron model exhibiting a chaotic spiking-bursting behavior in response to a weak periodic force. This model exhibits two types of oscillations with different characteristic time scales, namely, long and short time scales. Several types of phase synchronization are observed, such as 1:1 phase locking between a single spike and one period of the force and 1:l phase locking between the period of slow oscillation underlying bursts and l periods of the force. Moreover, spiking-bursting oscillations with chaotic firing patterns can be synchronized with the periodic force. Such a type of phase synchronization is detected from the position of a set of points on a unit circle, which is determined by the phase of the periodic force at each spiking time. We show that this detection method is effective for a system with multiple time scales. Owing to the existence of both the short and the long time scales, two characteristic phenomena are found around the transition point to chaotic phase synchronization. One phenomenon shows that the average time interval between successive phase slips exhibits a power-law scaling against the driving force strength and that the scaling exponent has an unsmooth dependence on the changes in the driving force strength. The other phenomenon shows that Kuramoto's order parameter before the transition exhibits stepwise behavior as a function of the driving force strength, contrary to the smooth transition in a model with a single time scale.

Multi-Scale Morphological Analysis of Conductance Signals in Vertical Upward Gas-Liquid Two-Phase Flow

NASA Astrophysics Data System (ADS)

Lian, Enyang; Ren, Yingyu; Han, Yunfeng; Liu, Weixin; Jin, Ningde; Zhao, Junying

2016-11-01

The multi-scale analysis is an important method for detecting nonlinear systems. In this study, we carry out experiments and measure the fluctuation signals from a rotating electric field conductance sensor with eight electrodes. We first use a recurrence plot to recognise flow patterns in vertical upward gas-liquid two-phase pipe flow from measured signals. Then we apply a multi-scale morphological analysis based on the first-order difference scatter plot to investigate the signals captured from the vertical upward gas-liquid two-phase flow loop test. We find that the invariant scaling exponent extracted from the multi-scale first-order difference scatter plot with the bisector of the second-fourth quadrant as the reference line is sensitive to the inhomogeneous distribution characteristics of the flow structure, and the variation trend of the exponent is helpful to understand the process of breakup and coalescence of the gas phase. In addition, we explore the dynamic mechanism influencing the inhomogeneous distribution of the gas phase in terms of adaptive optimal kernel time-frequency representation. The research indicates that the system energy is a factor influencing the distribution of the gas phase and the multi-scale morphological analysis based on the first-order difference scatter plot is an effective method for indicating the inhomogeneous distribution of the gas phase in gas-liquid two-phase flow.

Scaling Relations for Viscous and Gravitational Flow Instabilities in Multiphase Multicomponent Compressible Flow

NASA Astrophysics Data System (ADS)

Moortgat, J.; Amooie, M. A.; Soltanian, M. R.

2016-12-01

Problems in hydrogeology and hydrocarbon reservoirs generally involve the transport of solutes in a single solvent phase (e.g., contaminants or dissolved injection gas), or the flow of multiple phases that may or may not exchange mass (e.g., brine, NAPL, oil, gas). Often, flow is viscously and gravitationally unstable due to mobility and density contrasts within a phase or between phases. Such instabilities have been studied in detail for single-phase incompressible fluids and for two-phase immiscible flow, but to a lesser extent for multiphase multicomponent compressible flow. The latter is the subject of this presentation. Robust phase stability analyses and phase split calculations, based on equations of state, determine the mass exchange between phases and the resulting phase behavior, i.e., phase densities, viscosities, and volumes. Higher-order finite element methods and fine grids are used to capture the small-scale onset of flow instabilities. A full matrix of composition dependent coefficients is considered for each Fickian diffusive phase flux. Formation heterogeneity can have a profound impact and is represented by realistic geostatistical models. Qualitatively, fingering in multiphase compositional flow is different from single-phase problems because 1) phase mobilities depend on rock wettability through relative permeabilities, and 2) the initial density and viscosity ratios between phases may change due to species transfer. To quantify mixing rates in different flow regimes and for varying degrees of miscibility and medium heterogeneities, we define the spatial variance, scalar dissipation rate, dilution index, skewness, and kurtosis of the molar density of introduced species. Molar densities, unlike compositions, include compressibility effects. The temporal evolution of these measures shows that, while transport at the small-scale (cm) is described by the classical advection-diffusion-dispersion relations, scaling at the macro-scale (> 10 m) shows transitions between advective, diffusive, ballistic, sub-diffusive, and non-Fickian diffusive behavior. These scaling relations can be used to improve the predictive powers of field-scale reservoir simulations that cannot resolve the complexities of unstable flow and transport at cm-m scales.

Atomistic to Continuum Multiscale and Multiphysics Simulation of NiTi Shape Memory Alloy

NASA Astrophysics Data System (ADS)

Gur, Sourav

Shape memory alloys (SMAs) are materials that show reversible, thermo-elastic, diffusionless, displacive (solid to solid) phase transformation, due to the application of temperature and/ or stress (/strain). Among different SMAs, NiTi is a popular one. NiTi shows reversible phase transformation, the shape memory effect (SME), where irreversible deformations are recovered upon heating, and superelasticity (SE), where large strains imposed at high enough temperatures are fully recovered. Phase transformation process in NiTi SMA is a very complex process that involves the competition between developed internal strain and phonon dispersion instability. In NiTi SMA, phase transformation occurs over a wide range of temperature and/ or stress (strain) which involves, evolution of different crystalline phases (cubic austenite i.e. B2, different monoclinic variant of martensite i.e. B19', and orthorhombic B19 or BCO structures). Further, it is observed from experimental and computational studies that the evolution kinetics and growth rate of different phases in NiTi SMA vary significantly over a wide spectrum of spatio-temporal scales, especially with length scales. At nano-meter length scale, phase transformation temperatures, critical transformation stress (or strain) and phase fraction evolution change significantly with sample or simulation cell size and grain size. Even, below a critical length scale, the phase transformation process stops. All these aspects make NiTi SMA very interesting to the science and engineering research community and in this context, the present focuses on the following aspects. At first this study address the stability, evolution and growth kinetics of different phases (B2 and variants of B19'), at different length scales, starting from the atomic level and ending at the continuum macroscopic level. The effects of simulation cell size, grain size, and presence of free surface and grain boundary on the phase transformation process (transformation temperature, phase fraction evolution kinetics due to temperature) are also demonstrated herein. Next, to couple and transfer the statistical information of length scale dependent phase transformation process, multiscale/ multiphysics methods are used. Here, the computational difficulty from the fact that the representative governing equations (i.e. different sub-methods such as molecular dynamics simulations, phase field simulations and continuum level constitutive/ material models) are only valid or can be implemented over a range of spatiotemporal scales. Therefore, in the present study, a wavelet based multiscale coupling method is used, where simulation results (phase fraction evolution kinetics) from different sub-methods are linked via concurrent multiscale coupling fashion. Finally, these multiscale/ multiphysics simulation results are used to develop/ modify the macro/ continuum scale thermo-mechanical constitutive relations for NiTi SMA. Finally, the improved material model is used to model new devices, such as thermal diodes and smart dampers.

Dynamical mean-field theory and weakly non-linear analysis for the phase separation of active Brownian particles

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

Speck, Thomas; Menzel, Andreas M.; Bialké, Julian

2015-06-14

Recently, we have derived an effective Cahn-Hilliard equation for the phase separation dynamics of active Brownian particles by performing a weakly non-linear analysis of the effective hydrodynamic equations for density and polarization [Speck et al., Phys. Rev. Lett. 112, 218304 (2014)]. Here, we develop and explore this strategy in more detail and show explicitly how to get to such a large-scale, mean-field description starting from the microscopic dynamics. The effective free energy emerging from this approach has the form of a conventional Ginzburg-Landau function. On the coarsest scale, our results thus agree with the mapping of active phase separation ontomore » that of passive fluids with attractive interactions through a global effective free energy (motility-induced phase transition). Particular attention is paid to the square-gradient term necessary for the phase separation kinetics. We finally discuss results from numerical simulations corroborating the analytical results.« less

Effects of a finite outer scale on the measurement of atmospheric-turbulence statistics with a Hartmann wave-front sensor.

PubMed

Feng, Shen; Wenhan, Jiang

2002-06-10

Phase-structure and aperture-averaged slope-correlated functions with a finite outer scale are derived based on the Taylor hypothesis and a generalized spectrum, such as the von Kármán modal. The effects of the finite outer scale on measuring and determining the character of atmospheric-turbulence statistics are shown especially for an approximately 4-m class telescope and subaperture. The phase structure function and atmospheric coherent length based on the Kolmogorov model are approximations of the formalism we have derived. The analysis shows that it cannot be determined whether the deviation from the power-law parameter of Kolmogorov turbulence is caused by real variations of the spectrum or by the effect of the finite outer scale.

Small scale wind tunnel model investigation of hybrid high lift systems combining upper surface blowing with the internally blown flap

NASA Technical Reports Server (NTRS)

Waites, W. L.; Chin, Y. T.

1974-01-01

A small-scale wind tunnel test of a two engine hybrid model with upper surface blowing on a simulated expandable duct internally blown flap was accomplished in a two phase program. The low wing Phase I model utilized 0.126c radius Jacobs/Hurkamp flaps and 0.337c radius Coanda flaps. The high wing Phase II model was utilized for continued studies on the Jacobs/Hurkamp flap. Principal study areas included: basic data both engines operative and with an engine out, control flap utilization, horizontal tail effectiveness, spoiler effectiveness, USB nacelle deflector study and USB/IBF pressure ratio effects.

Development and validation of a fatigue assessment scale for U.S. construction workers.

PubMed

Zhang, Mingzong; Sparer, Emily H; Murphy, Lauren A; Dennerlein, Jack T; Fang, Dongping; Katz, Jeffrey N; Caban-Martinez, Alberto J

2015-02-01

To develop a fatigue assessment scale and test its reliability and validity for commercial construction workers. Using a two-phased approach, we first identified items (first phase) for the development of a Fatigue Assessment Scale for Construction Workers (FASCW) through review of existing scales in the scientific literature, key informant interviews (n = 11) and focus groups (three groups with six workers each) with construction workers. The second phase included assessment for the reliability, validity, and sensitivity of the new scale using a repeated-measures study design with a convenience sample of construction workers (n = 144). Phase one resulted in a 16-item preliminary scale that after factor analysis yielded a final 10-item scale with two sub-scales ("Lethargy" and "Bodily Ailment"). During phase two, the FASCW and its subscales demonstrated satisfactory internal consistency (alpha coefficients were FASCW [0.91], Lethargy [0.86] and Bodily Ailment [0.84]) and acceptable test-retest reliability (Pearson Correlations Coefficients: 0.59-0.68; Intraclass Correlation Coefficients: 0.74-0.80). Correlation analysis substantiated concurrent and convergent validity. A discriminant analysis demonstrated that the FASCW differentiated between groups with arthritis status and different work hours. The 10-item FASCW with good reliability and validity is an effective tool for assessing the severity of fatigue among construction workers. © 2015 Wiley Periodicals, Inc.

Surface-wave amplitude analysis for array data with non-linear waveform fitting: Toward high-resolution attenuation models of the upper mantle

NASA Astrophysics Data System (ADS)

Hamada, K.; Yoshizawa, K.

2013-12-01

Anelastic attenuation of seismic waves provides us with valuable information on temperature and water content in the Earth's mantle. While seismic velocity models have been investigated by many researchers, anelastic attenuation (or Q) models have yet to be investigated in detail mainly due to the intrinsic difficulties and uncertainties in the amplitude analysis of observed seismic waveforms. To increase the horizontal resolution of surface wave attenuation models on a regional scale, we have developed a new method of fully non-linear waveform fitting to measure inter-station phase velocities and amplitude ratios simultaneously, using the Neighborhood Algorithm (NA) as a global optimizer. Model parameter space (perturbations of phase speed and amplitude ratio) is explored to fit two observed waveforms on a common great-circle path by perturbing both phase and amplitude of the fundamental-mode surface waves. This method has been applied to observed waveform data of the USArray from 2007 to 2008, and a large-number of inter-station amplitude and phase speed data are corrected in a period range from 20 to 200 seconds. We have constructed preliminary phase speed and attenuation models using the observed phase and amplitude data, with careful considerations of the effects of elastic focusing and station correction factors for amplitude data. The phase velocity models indicate good correlation with the conventional tomographic results in North America on a large-scale; e.g., significant slow velocity anomaly in volcanic regions in the western United States. The preliminary results of surface-wave attenuation achieved a better variance reduction when the amplitude data are inverted for attenuation models in conjunction with corrections for receiver factors. We have also taken into account the amplitude correction for elastic focusing based on a geometrical ray theory, but its effects on the final model is somewhat limited and our attenuation model show anti-correlation with the phase velocity models; i.e., lower attenuation is found in slower velocity areas that cannot readily be explained by the temperature effects alone. Some former global scale studies (e.g., Dalton et al., JGR, 2006) indicated that the ray-theoretical focusing corrections on amplitude data tend to eliminate such anti-correlation of phase speed and attenuation, but this seems not to work sufficiently well for our regional scale model, which is affected by stronger velocity gradient relative to global-scale models. Thus, the estimated elastic focusing effects based on ray theory may be underestimated in our regional-scale studies. More rigorous ways to estimate the focusing corrections as well as data selection criteria for amplitude measurements are required to achieve a high-resolution attenuation models on regional scales in the future.

Combined effect of constant high voltage electrostatic field and variable frequency pulsed electromagnetic field on the morphology of calcium carbonate scale in circulating cooling water systems.

PubMed

Zhao, Ju-Dong; Liu, Zhi-An; Zhao, Er-Jun

2014-01-01

Research on scale inhibition is of importance to improve the heat transfer efficiency of heat exchangers. The combined effect of high voltage electrostatic and variable frequency pulsed electromagnetic fields on calcium carbonate precipitation was investigated, both theoretically and experimentally. Using energy dispersive spectrum analysis, the predominant phase was found to be CaCO(3). The formed crystal phases mainly consist of calcite and aragonite, which is, in part, verified by theory. The results indicate that the setting of water flow velocity, and high voltage electrostatic and variable frequency pulsed electromagnetic fields is very important. Favorable values of these parameters can have a significant anti-scaling effect, with 68.95% of anti-scaling ratio for scale sample 13, while unfavorable values do not affect scale inhibition, but rather promoted fouling, such as scale sample 6. By using scanning electron microscopy analysis, when the anti-scaling ratio is positive, the particle size of scale was found to become smaller than that of untreated sample and the morphology became loose. The X-ray diffraction results verify that the good combined effect favors the appearance and growth of aragonite and restrains its transition to calcite. The mechanism for scale reduction is discussed.

An investigation of stress wave propagation in a shear deformable nanobeam based on modified couple stress theory

NASA Astrophysics Data System (ADS)

Akbarzadeh Khorshidi, Majid; Shariati, Mahmoud

2016-04-01

This paper presents a new investigation for propagation of stress wave in a nanobeam based on modified couple stress theory. Using Euler-Bernoulli beam theory, Timoshenko beam theory, and Reddy beam theory, the effect of shear deformation is investigated. This nonclassical model contains a material length scale parameter to capture the size effect and the Poisson effect is incorporated in the current model. Governing equations of motion are obtained by Hamilton's principle and solved explicitly. This solution leads to obtain two phase velocities for shear deformable beams in different directions. Effects of shear deformation, material length scale parameter, and Poisson's ratio on the behavior of these phase velocities are investigated and discussed. The results also show a dual behavior for phase velocities against Poisson's ratio.

A single-phase elastic hyperbolic metamaterial with anisotropic mass density.

PubMed

Zhu, R; Chen, Y Y; Wang, Y S; Hu, G K; Huang, G L

2016-06-01

Wave propagation can be manipulated at a deep subwavelength scale through the locally resonant metamaterial that possesses unusual effective material properties. Hyperlens due to metamaterial's anomalous anisotropy can lead to superior-resolution imaging. In this paper, a single-phase elastic metamaterial with strongly anisotropic effective mass density has been designed. The proposed metamaterial utilizes the independently adjustable locally resonant motions of the subwavelength-scale microstructures along the two principal directions. High anisotropy in the effective mass densities obtained by the numerical-based effective medium theory can be found and even have opposite signs. For practical applications, shunted piezoelectric elements are introduced into the microstructure to tailor the effective mass density in a broad frequency range. Finally, to validate the design, an elastic hyperlens made of the single-phase hyperbolic metamaterial is proposed with subwavelength longitudinal wave imaging illustrated numerically. The proposed single-phase hyperbolic metamaterial has many promising applications for high resolution damage imaging in nondestructive evaluation and structural health monitoring.

Charged Particles on Surfaces: Coexistence of Dilute Phases and Periodic Structures at Interfaces

NASA Astrophysics Data System (ADS)

Loverde, Sharon M.; Solis, Francisco J.; Olvera de La Cruz, Monica

2007-06-01

We consider a mixture of two immiscible oppositely charged molecules strongly adsorbed to an interface, with a neutral nonselective molecular background. We determine the coexistence between a high density ionic periodic phase and a dilute isotropic ionic phase. We use a strong segregation approach for the periodic phase and determine the one-loop free energy for the dilute phase. Lamellar and hexagonal patterns are calculated for different charge stoichiometries of the mixture. Molecular dynamics simulations exhibit the predicted phase behavior. The periodic length scale of the solid phase is found to scale as ɛ/(lBψ3/2), where ψ is the effective charge density, lB is the Bjerrum length, and ɛ is the cohesive energy.

Development and Preliminary Validation of the Drinking Expectancy Sexual Vulnerabilities Questionnaire (DESV-Q): A Purpose-Specific Instrument for Rape-Perception Research.

PubMed

Starfelt, Louise Charlotte; Young, Ross McD; White, Katherine M; Palk, Gavan

2016-01-01

Alcohol expectancies likely play a role in people's perceptions of alcohol-involved sexual violence. However, no appropriate measure exists to examine this link comprehensively. The aim of this research was to develop an alcohol expectancy measure which captures young adults' beliefs about alcohol's role in sexual aggression and victimization. Two cross-sectional samples of young Australian adults (18-25 years) were recruited for scale development (Phase 1) and scale validation (Phase 2). In Phase 1, participants (N = 201; 38.3% males) completed an online survey with an initial pool of alcohol expectancy items stated in terms of three targets (self, men, women) to identify the scale's factor structure and most effective items. A revised alcohol expectancy scale was then administered online to 322 young adults (39.6% males) in Phase 2. To assess the predictive, convergent, and discriminant validity of the scale, participants also completed established measures of personality, social desirability, alcohol use, general and context-specific alcohol expectancies, and impulsiveness. Principal axis factoring (Phase 1) and confirmatory factor analysis (Phase 2) resulted in a target-equivalent five-factor structure for the final 66-item Drinking Expectancy Sexual Vulnerabilities Questionnaire (DESV-Q). The factors were labeled (1) Sexual Coercion, (2) Sexual Vulnerability, (3) Confidence, (4) Self-Centeredness, and (5) Negative Cognitive and Behavioral Changes. The measure demonstrated effective items, high internal consistency, and satisfactory predictive, convergent, and discriminant validity. The DESV-Q is a purpose-specific instrument that could be used in future research to elucidate people's attributions for alcohol-involved sexual aggression and victimization.

Monodisperse granular flows in viscous dispersions in a centrifugal acceleration field

NASA Astrophysics Data System (ADS)

Cabrera, Miguel Angel; Wu, Wei

2016-04-01

Granular flows are encountered in geophysical flows and innumerable industrial applications with particulate materials. When mixed with a fluid, a complex network of interactions between the particle- and fluid-phase develops, resulting in a compound material with a yet unclear physical behaviour. In the study of granular suspensions mixed with a viscous dispersion, the scaling of the stress-strain characteristics of the fluid phase needs to account for the level of inertia developed in experiments. However, the required model dimensions and amount of material becomes a main limitation for their study. In recent years, centrifuge modelling has been presented as an alternative for the study of particle-fluid flows in a reduced scaled model in an augmented acceleration field. By formulating simple scaling principles proportional to the equivalent acceleration Ng in the model, the resultant flows share many similarities with field events. In this work we study the scaling principles of the fluid phase and its effects on the flow of granular suspensions. We focus on the dense flow of a monodisperse granular suspension mixed with a viscous fluid phase, flowing down an inclined plane and being driven by a centrifugal acceleration field. The scaled model allows the continuous monitoring of the flow heights, velocity fields, basal pressure and mass flow rates at different Ng levels. The experiments successfully identify the effects of scaling the plastic viscosity of the fluid phase, its relation with the deposition of particles over the inclined plane, and allows formulating a discussion on the suitability of simulating particle-fluid flows in a centrifugal acceleration field.

Frequency Preference Response to Oscillatory Inputs in Two-dimensional Neural Models: A Geometric Approach to Subthreshold Amplitude and Phase Resonance.

PubMed

Rotstein, Horacio G

2014-01-01

We investigate the dynamic mechanisms of generation of subthreshold and phase resonance in two-dimensional linear and linearized biophysical (conductance-based) models, and we extend our analysis to account for the effect of simple, but not necessarily weak, types of nonlinearities. Subthreshold resonance refers to the ability of neurons to exhibit a peak in their voltage amplitude response to oscillatory input currents at a preferred non-zero (resonant) frequency. Phase-resonance refers to the ability of neurons to exhibit a zero-phase (or zero-phase-shift) response to oscillatory input currents at a non-zero (phase-resonant) frequency. We adapt the classical phase-plane analysis approach to account for the dynamic effects of oscillatory inputs and develop a tool, the envelope-plane diagrams, that captures the role that conductances and time scales play in amplifying the voltage response at the resonant frequency band as compared to smaller and larger frequencies. We use envelope-plane diagrams in our analysis. We explain why the resonance phenomena do not necessarily arise from the presence of imaginary eigenvalues at rest, but rather they emerge from the interplay of the intrinsic and input time scales. We further explain why an increase in the time-scale separation causes an amplification of the voltage response in addition to shifting the resonant and phase-resonant frequencies. This is of fundamental importance for neural models since neurons typically exhibit a strong separation of time scales. We extend this approach to explain the effects of nonlinearities on both resonance and phase-resonance. We demonstrate that nonlinearities in the voltage equation cause amplifications of the voltage response and shifts in the resonant and phase-resonant frequencies that are not predicted by the corresponding linearized model. The differences between the nonlinear response and the linear prediction increase with increasing levels of the time scale separation between the voltage and the gating variable, and they almost disappear when both equations evolve at comparable rates. In contrast, voltage responses are almost insensitive to nonlinearities located in the gating variable equation. The method we develop provides a framework for the investigation of the preferred frequency responses in three-dimensional and nonlinear neuronal models as well as simple models of coupled neurons.

From micron to mountain-scale, using accessory phase petrochronology to quantify the rates of deformation in the Himalaya and beyond

NASA Astrophysics Data System (ADS)

Mottram, C. M.

2016-12-01

Mountains form where the Earth's plates collide; during this upheaval rocks are deformed by massive forces. The rates and timescales over which these deformational processes occur are determined from tiny accessory minerals that record geological time through radioactive decay. However, there remain major unresolved challenges in using chemical and microstructural markers to link the dates yielded from these accessory phases to specific deformation events and discerning the effects of deformation on the isotopic and elemental tracers in these phases. Here, the chemical signatures and deformation textures from micron-scale accessory phases are used to decode the record of mountain belt-scale deformational processes encrypted in the rocks. The Himalayan orogen is used as an ideal natural laboratory to understand the chemical processes that have modified the Earth's crust during orogenesis. Combined laser ablation split-stream U-Th-Pb and REE analysis of deformed monazite and titanite, along with Electron BackScatter Diffraction (EBSD) imaging and Pressure-Temperature (P-T) phase equilibria modelling are used to: (1) link accessory phase `age' to `metamorphic stage'; (2) to quantify the influence of deformation on monazite (re)crystallisation mechanisms and its subsequent effect on the crystallographic structure, ages and trace-element distribution in individual grains; and (3) understand how deformation is accommodated through different chemical and structural processes that operate at varying scales through time. This study highlights the importance of fully integrating the pressure-temperature-time-deformation history of multiple accessory phases to better interpret the deformational history of the cores of evolving mountain belts.

Fast-scale non-linear distortion analysis of peak-current-controlled buck-boost inverters

NASA Astrophysics Data System (ADS)

Zhang, Hao; Dong, Shuai; Yi, Chuanzhi; Guan, Weimin

2018-02-01

This paper deals with fast-scale non-linear distortion behaviours including asymmetrical period-doubling bifurcation and zero-crossing distortion in peak-current-controlled buck-boost inverters. The underlying mechanisms of the fast-scale non-linear distortion behaviours in inverters are revealed. The folded bifurcation diagram is presented to analyse the asymmetrical phenomenon of fast-scale period-doubling bifurcation. In view of the effect of phase shift and current ripple, the analytical expressions for one pair of critical phase angles are derived by using the design-oriented geometrical current approach. It is shown that the phase shift between inductor current and capacitor voltage should be responsible for the zero-crossing distortion phenomenon. These results obtained here are useful to optimise the circuit design and improve the circuit performance.

Refinement of the Montreal Instrument for Cat Arthritis Testing, for Use by Veterinarians: detection of naturally occurring osteoarthritis in laboratory cats.

PubMed

Klinck, Mary P; Monteiro, Beatriz P; Lussier, Bertrand; Guillot, Martin; Moreau, Maxim; Otis, Colombe; Steagall, Paulo Vm; Frank, Diane; Martel-Pelletier, Johanne; Pelletier, Jean-Pierre; Del Castillo, Jérôme Re; Troncy, Eric

2017-09-01

Objectives Feline osteoarthritis causes pain and disability. Detection and measurement is challenging, relying heavily on owner report. This study describes refinement of the Montreal Instrument for Cat Arthritis Testing, for Use by Veterinarians. Methods A video analysis of osteoarthritic (n = 6) and non-osteoarthritic (n = 4) cats facilitated expansion of scale items. Three successive therapeutic trials (using gabapentin, tramadol and oral transmucosal meloxicam spray) in laboratory cats with and without natural osteoarthritis (n = 12-20), permitted construct validation (assessments of disease status sensitivity and therapeutic responsiveness) and further scale refinements based on performance. Results Scale osteoarthritic sensitivity improved from phase I to phase III; phase III scale total score ( P = 0.0001) and 4/5 subcategories - body posture ( P = 0.0006), gait ( P = 0.0031), jumping (0.0824) and global distance examination ( P = 0.0001) - detected osteoarthritic cats. Total score inter-rater (intra-class correlation coefficients [ICC] = 0.64-0.75), intra-rater (ICC = 0.90-0.91) and overall internal consistency (Cronbach's alpha = 0.85) reliability were good to excellent. von Frey anesthesiometer-induced paw withdrawal threshold increased with gabapentin in phase I, in osteoarthritic cats ( P <0.001) but not in non-osteoarthritic cats ( P = 0.075). Night-time activity increased during gabapentin treatment. Objective measures also detected tramadol and/or meloxicam treatment effects in osteoarthritic cats in phases II and III. There was some treatment responsiveness: in phase I, 3/10 subcategory scores improved ( P <0.09) in treated osteoarthritic cats; in phase II, 3/8 subcategories; and in phase III, 1/5 subcategories improved ( P <0.096). Conclusions and relevance The revised scale detected naturally occurring osteoarthritis, but not treatment effects, in laboratory cats, suggesting future potential for screening of at-risk cats. Further study is needed to confirm reliability, validity (disease sensitivity and treatment responsiveness) and clinical feasibility, as well as cut-off scores for osteoarthritic vs non-osteoarthritic status, in client-owned cats.

[Effectiveness of a mindfulness program in primary care professionals].

PubMed

Martín Asuero, Andrés; Rodríguez Blanco, Teresa; Pujol-Ribera, Enriqueta; Berenguera, Anna; Moix Queraltó, Jenny

2013-01-01

To determine the long-term effects of a mindfulness program on burnout, mood states, empathy, and mindfulness in primary care professionals. A repeated measures before-after study was performed in 87 participants working in primary care. The variables evaluated were scores of the Burnout Inventory (Maslach), mood states (Profile of Mood States [POMS]), empathy (Jefferson Scale of Physician Empathy [JSPE]) and mindfulness (Five Facet Mindfulness Questionnaire [FFMQ]), adherence to the intervention, and changes in attitudes. Evaluations were performed at baseline, at 8 weeks, and at 6 and 12 months. The intervention lasted for 1 year and consisted of two training phases, an intensive first phase lasting 28 hours, spread over 8 weeks, and a second, maintenance phase of 25 hours spread over 10 months. The effect of the intervention was assessed through observed change, standardized response mean (SRM), and linear mixed-effects models on repeated measures. The scores of all the scales improved significantly during the follow-up compared with baseline scores. The greatest differences were obtained at 12 months, especially in the the FFMQ (SRM: 1.4), followed by the POMS (SRM: 0,8). The greatest improvement in the maintenance phase was found in the difference between consecutive scores. The only scale that showed major changes in all phases was the FFMQ scale. At the end of the intervention, 89% of participants practiced the exercises of the program on their own and 94% reported improvements in self-care and greater professionalism. A psychoeducational program based on mindfulness reduces burnout and improves mood states, empathy, and mindfulness, while encouraging better self-care. Copyright © 2013 SESPAS. Published by Elsevier Espana. All rights reserved.

Mesoscale Effective Property Simulations Incorporating Conductive Binder

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

Trembacki, Bradley L.; Noble, David R.; Brunini, Victor E.

Lithium-ion battery electrodes are composed of active material particles, binder, and conductive additives that form an electrolyte-filled porous particle composite. The mesoscale (particle-scale) interplay of electrochemistry, mechanical deformation, and transport through this tortuous multi-component network dictates the performance of a battery at the cell-level. Effective electrode properties connect mesoscale phenomena with computationally feasible battery-scale simulations. We utilize published tomography data to reconstruct a large subsection (1000+ particles) of an NMC333 cathode into a computational mesh and extract electrode-scale effective properties from finite element continuum-scale simulations. We present a novel method to preferentially place a composite binder phase throughout the mesostructure,more » a necessary approach due difficulty distinguishing between non-active phases in tomographic data. We compare stress generation and effective thermal, electrical, and ionic conductivities across several binder placement approaches. Isotropic lithiation-dependent mechanical swelling of the NMC particles and the consideration of strain-dependent composite binder conductivity significantly impact the resulting effective property trends and stresses generated. Lastly, our results suggest that composite binder location significantly affects mesoscale behavior, indicating that a binder coating on active particles is not sufficient and that more accurate approaches should be used when calculating effective properties that will inform battery-scale models in this inherently multi-scale battery simulation challenge.« less

Mesoscale Effective Property Simulations Incorporating Conductive Binder

DOE PAGES

Trembacki, Bradley L.; Noble, David R.; Brunini, Victor E.; ...

2017-07-26

Lithium-ion battery electrodes are composed of active material particles, binder, and conductive additives that form an electrolyte-filled porous particle composite. The mesoscale (particle-scale) interplay of electrochemistry, mechanical deformation, and transport through this tortuous multi-component network dictates the performance of a battery at the cell-level. Effective electrode properties connect mesoscale phenomena with computationally feasible battery-scale simulations. We utilize published tomography data to reconstruct a large subsection (1000+ particles) of an NMC333 cathode into a computational mesh and extract electrode-scale effective properties from finite element continuum-scale simulations. We present a novel method to preferentially place a composite binder phase throughout the mesostructure,more » a necessary approach due difficulty distinguishing between non-active phases in tomographic data. We compare stress generation and effective thermal, electrical, and ionic conductivities across several binder placement approaches. Isotropic lithiation-dependent mechanical swelling of the NMC particles and the consideration of strain-dependent composite binder conductivity significantly impact the resulting effective property trends and stresses generated. Lastly, our results suggest that composite binder location significantly affects mesoscale behavior, indicating that a binder coating on active particles is not sufficient and that more accurate approaches should be used when calculating effective properties that will inform battery-scale models in this inherently multi-scale battery simulation challenge.« less

Multifunctional picoliter droplet manipulation platform and its application in single cell analysis.

PubMed

Gu, Shu-Qing; Zhang, Yun-Xia; Zhu, Ying; Du, Wen-Bin; Yao, Bo; Fang, Qun

2011-10-01

We developed an automated and multifunctional microfluidic platform based on DropLab to perform flexible generation and complex manipulations of picoliter-scale droplets. Multiple manipulations including precise droplet generation, sequential reagent merging, and multistep solid-phase extraction for picoliter-scale droplets could be achieved in the present platform. The system precision in generating picoliter-scale droplets was significantly improved by minimizing the thermo-induced fluctuation of flow rate. A novel droplet fusion technique based on the difference of droplet interfacial tensions was developed without the need of special microchannel networks or external devices. It enabled sequential addition of reagents to droplets on demand for multistep reactions. We also developed an effective picoliter-scale droplet splitting technique with magnetic actuation. The difficulty in phase separation of magnetic beads from picoliter-scale droplets due to the high interfacial tension was overcome using ferromagnetic particles to carry the magnetic beads to pass through the phase interface. With this technique, multistep solid-phase extraction was achieved among picoliter-scale droplets. The present platform had the ability to perform complex multistep manipulations to picoliter-scale droplets, which is particularly required for single cell analysis. Its utility and potentials in single cell analysis were preliminarily demonstrated in achieving high-efficiency single-cell encapsulation, enzyme activity assay at the single cell level, and especially, single cell DNA purification based on solid-phase extraction.

Space cryogenics components based on the thermomechanical effect - Vapor-liquid phase separation

NASA Technical Reports Server (NTRS)

Yuan, S. W. K.; Frederking, T. H. K.

1989-01-01

Applications of the thermomechanical effect has been qualified including incorporation in large-scale space systems in the area of vapor-liquid phase separation (VLPS). The theory of the porous-plug phase separator is developed for the limit of a high thermal impedance of the solid-state grains. Extensions of the theory of nonlinear turbulent flow are presented based on experimental results.

Entanglement convertibility by sweeping through the quantum phases of the alternating bonds XXZ chain

PubMed Central

Tzeng, Yu-Chin; Dai, Li; Chung, Ming-Chiang; Amico, Luigi; Kwek, Leong-Chuan

2016-01-01

We study the entanglement structure and the topological edge states of the ground state of the spin-1/2 XXZ model with bond alternation. We employ parity-density matrix renormalization group with periodic boundary conditions. The finite-size scaling of Rényi entropies S2 and S∞ are used to construct the phase diagram of the system. The phase diagram displays three possible phases: Haldane type (an example of symmetry protected topological ordered phases), Classical Dimer and Néel phases, the latter bounded by two continuous quantum phase transitions. The entanglement and non-locality in the ground state are studied and quantified by the entanglement convertibility. We found that, at small spatial scales, the ground state is not convertible within the topological Haldane dimer phase. The phenomenology we observe can be described in terms of correlations between edge states. We found that the entanglement spectrum also exhibits a distinctive response in the topological phase: the effective rank of the reduced density matrix displays a specifically large “susceptibility” in the topological phase. These findings support the idea that although the topological order in the ground state cannot be detected by local inspection, the ground state response at local scale can tell the topological phases apart from the non-topological phases. PMID:27216970

Entanglement convertibility by sweeping through the quantum phases of the alternating bonds XXZ chain.

PubMed

Tzeng, Yu-Chin; Dai, Li; Chung, Ming-Chiang; Amico, Luigi; Kwek, Leong-Chuan

2016-05-24

We study the entanglement structure and the topological edge states of the ground state of the spin-1/2 XXZ model with bond alternation. We employ parity-density matrix renormalization group with periodic boundary conditions. The finite-size scaling of Rényi entropies S2 and S∞ are used to construct the phase diagram of the system. The phase diagram displays three possible phases: Haldane type (an example of symmetry protected topological ordered phases), Classical Dimer and Néel phases, the latter bounded by two continuous quantum phase transitions. The entanglement and non-locality in the ground state are studied and quantified by the entanglement convertibility. We found that, at small spatial scales, the ground state is not convertible within the topological Haldane dimer phase. The phenomenology we observe can be described in terms of correlations between edge states. We found that the entanglement spectrum also exhibits a distinctive response in the topological phase: the effective rank of the reduced density matrix displays a specifically large "susceptibility" in the topological phase. These findings support the idea that although the topological order in the ground state cannot be detected by local inspection, the ground state response at local scale can tell the topological phases apart from the non-topological phases.

Low-noise phase of a two-dimensional active nematic system

NASA Astrophysics Data System (ADS)

Shankar, Suraj; Ramaswamy, Sriram; Marchetti, M. Cristina

2018-01-01

We consider a collection of self-driven apolar particles on a substrate that organize into an active nematic phase at sufficiently high density or low noise. Using the dynamical renormalization group, we systematically study the two-dimensional fluctuating ordered phase in a coarse-grained hydrodynamic description involving both the nematic director and the conserved density field. In the presence of noise, we show that the system always displays only quasi-long-ranged orientational order beyond a crossover scale. A careful analysis of the nonlinearities permitted by symmetry reveals that activity is dangerously irrelevant over the linearized description, allowing giant number fluctuations to persist although now with strong finite-size effects and a nonuniversal scaling exponent. Nonlinear effects from the active currents lead to power-law correlations in the density field, thereby preventing macroscopic phase separation in the thermodynamic limit.

Experimental Investigation of a Helicopter Rotor Hub Flow

NASA Astrophysics Data System (ADS)

Reich, David

The rotor hub system is by far the largest contributor to helicopter parasite drag and a barrier to increasing helicopter forward-flight speed and range. Additionally, the hub sheds undesirable vibration- and instability-inducing unsteady flow over the empennage. The challenges associated with rotor hub flows are discussed, including bluff body drag, interactional aerodynamics, and the effect of the turbulent hub wake on the helicopter empennage. This study was conducted in three phases to quantify model-scale rotor hub flows in water tunnels at The Pennsylvania State University Applied research lab. The first phase investigated scaling and component interaction effects on a 1:17 scale rotor hub model in the 12-inch diameter water tunnel. Effects of Reynolds number, advance ratio, and hub geometry configuration on the drag and wake shed from the rotor hub were quantified using load cell measurements and particle-image velocimetry (PIV). The second phase focused on flow visualization and measurement on a rotor hub and rotor hub/pylon geometry in the 12-inch diameter water tunnel. Stereo PIV was conducted in a cross plane downstream of the hub and flow visualization was conducted using oil paint and fluorescent dye. The third phase concentrated on high accuracy load measurement and prediction up to full-scale Reynolds number on a 1:4.25 scale model in the 48-inch diameter water tunnel. Measurements include 6 degree of freedom loads on the hub and two-component laser-Doppler velocimetry in the wake. Finally, results and conclusions are discussed, followed by recommendations for future investigations.

Universal monopole scaling near transitions from the Coulomb phase.

PubMed

Powell, Stephen

2012-08-10

Certain frustrated systems, including spin ice and dimer models, exhibit a Coulomb phase at low temperatures, with power-law correlations and fractionalized monopole excitations. Transitions out of this phase, at which the effective gauge theory becomes confining, provide examples of unconventional criticality. This Letter studies the behavior at nonzero monopole density near such transitions, using scaling theory to arrive at universal expressions for the crossover phenomena. For a particular transition in spin ice, quantitative predictions are made by mapping to the XY model and confirmed using Monte Carlo simulations.

Numerical experiments to explain multiscale hydrological responses to mountain pine beetle tree mortality in a headwater watershed

USGS Publications Warehouse

Penn, Colin A.; Bearup, Lindsay A.; Maxwell, Reed M.; Clow, David W.

2016-01-01

The effects of mountain pine beetle (MPB)-induced tree mortality on a headwater hydrologic system were investigated using an integrated physical modeling framework with a high-resolution computational grid. Simulations of MPB-affected and unaffected conditions, each with identical atmospheric forcing for a normal water year, were compared at multiple scales to evaluate the effects of scale on MPB-affected hydrologic systems. Individual locations within the larger model were shown to maintain hillslope-scale processes affecting snowpack dynamics, total evapotranspiration, and soil moisture that are comparable to several field-based studies and previous modeling work. Hillslope-scale analyses also highlight the influence of compensating changes in evapotranspiration and snow processes. Reduced transpiration in the Grey Phase of MPB-induced tree mortality was offset by increased late-summer evaporation, while overall snowpack dynamics were more dependent on elevation effects than MPB-induced tree mortality. At the watershed scale, unaffected areas obscured the magnitude of MPB effects. Annual water yield from the watershed increased during Grey Phase simulations by 11 percent; a difference that would be difficult to diagnose with long-term gage observations that are complicated by inter-annual climate variability. The effects on hydrology observed and simulated at the hillslope scale can be further damped at the watershed scale, which spans more life zones and a broader range of landscape properties. These scaling effects may change under extreme conditions, e.g., increased total MPB-affected area or a water year with above average snowpack.

On the saturation of the refractive index structure function. II - Influence of the correlation length on astronomical 'seeing'

NASA Technical Reports Server (NTRS)

Venkatakrishnan, P.

1987-01-01

A physical length scale in the wavefront corresponding to the parameter (r sub 0) characterizing the loss in detail in a long exposure image is identified, and the influence of the correlation scale of turbulence as r sub 0 approaches this scale is shown. Allowing for the effect of 2-point correlations in the fluctuations of the refractive index, Venkatakrishnan and Chatterjee (1987) proposed a modified law for the phase structure function. It is suggested that the departure of the phase structure function from the 5/3 power law for length scales in the wavefront approaching the correlation scale of turbulence may lead to better 'seeing' at longer wavelengths.

Large-Scale Phase Synchrony Reflects Clinical Status After Stroke: An EEG Study.

PubMed

Kawano, Teiji; Hattori, Noriaki; Uno, Yutaka; Kitajo, Keiichi; Hatakenaka, Megumi; Yagura, Hajime; Fujimoto, Hiroaki; Yoshioka, Tomomi; Nagasako, Michiko; Otomune, Hironori; Miyai, Ichiro

2017-06-01

Stroke-induced focal brain lesions often exert remote effects via residual neural network activity. Electroencephalographic (EEG) techniques can assess neural network modifications after brain damage. Recently, EEG phase synchrony analyses have shown associations between the level of large-scale phase synchrony of brain activity and clinical symptoms; however, few reports have assessed such associations in stroke patients. The aim of this study was to investigate the clinical relevance of hemispheric phase synchrony in stroke patients by calculating its correlation with clinical status. This cross-sectional study included 19 patients with post-acute ischemic stroke admitted for inpatient rehabilitation. Interhemispheric phase synchrony indices (IH-PSIs) were computed in 2 frequency bands (alpha [α], and beta [β]), and associations between indices and scores of the Functional Independence Measure (FIM), the National Institutes of Health Stroke Scale (NIHSS), and the Fugl-Meyer Motor Assessment (FMA) were analyzed. For further assessments of IH-PSIs, ipsilesional intrahemispheric PSIs (IntraH-PSIs) as well as IH- and IntraH-phase lag indices (PLIs) were also evaluated. IH-PSIs correlated significantly with FIM scores and NIHSS scores. In contrast, IH-PSIs did not correlate with FMA scores. IntraH-PSIs correlate with FIM scores after removal of the outlier. The results of analysis with PLIs were consistent with IH-PSIs. The PSIs correlated with performance on the activities of daily living scale but not with scores on a pure motor impairment scale. These results suggest that large-scale phase synchrony represented by IH-PSIs provides a novel surrogate marker for clinical status after stroke.

Observable consequences of zero-point energy

NASA Astrophysics Data System (ADS)

Sen, Siddhartha; Gupta, Kumar S.

2017-12-01

Spectral line widths, the Lamb shift and the Casimir effect are generally accepted to be observable consequences of the zero-point electromagnetic (ZPEM) fields. A new class of observable consequences of ZPEM field at the mesoscopic scale were recently proposed and observed. Here, we extend this class of observable effects and predict that mesoscopic water layers should have a high value for its solid-liquid phase transition temperature, as illustrated by water inside a single-walled carbon nanotube (CNT). For this case, our analysis predicts that the phase transition temperature scales inversely with the square of the effective radius available for the water flow within the CNT.

Effect of nano/micro-Ag compound particles on the bio-corrosion, antibacterial properties and cell biocompatibility of Ti-Ag alloys.

PubMed

Chen, Mian; Yang, Lei; Zhang, Lan; Han, Yong; Lu, Zheng; Qin, Gaowu; Zhang, Erlin

2017-06-01

In this research, Ti-Ag alloys were prepared by powder metallurgy, casting and heat treatment method in order to investigate the effect of Ag compound particles on the bio-corrosion, the antibacterial property and the cell biocompatibility. Ti-Ag alloys with different sizes of Ag or Ag-compounds particles were successfully prepared: small amount of submicro-scale (100nm) Ti 2 Ag precipitates with solid solution state of Ag, large amount of nano-scale (20-30nm) Ti 2 Ag precipitates with small amount of solid solution state of Ag and micro-scale lamellar Ti 2 Ag phases, and complete solid solution state of Ag. The mechanical tests indicated that both nano/micro-scale Ti 2 Ag phases had a strong dispersion strengthening ability and Ag had a high solid solution strengthening ability. Electrochemical results shown the Ag content and the size of Ag particles had a limited influence on the bio-corrosion resistance although nano-scale Ti 2 Ag precipitates slightly improved corrosion resistance. It was demonstrated that the nano Ag compounds precipitates have a significant influence on the antibacterial properties of Ti-Ag alloys but no effect on the cell biocompatibility. It was thought that both Ag ions release and Ti 2 Ag precipitates contributed to the antibacterial ability, in which nano-scale and homogeneously distributed Ti 2 Ag phases would play a key role in antibacterial process. Copyright © 2017 Elsevier B.V. All rights reserved.

Scale effect of slip boundary condition at solid–liquid interface

PubMed Central

Nagayama, Gyoko; Matsumoto, Takenori; Fukushima, Kohei; Tsuruta, Takaharu

2017-01-01

Rapid advances in microelectromechanical systems have stimulated the development of compact devices, which require effective cooling technologies (e.g., microchannel cooling). However, the inconsistencies between experimental and classical theoretical predictions for the liquid flow in microchannel remain unclarified. Given the larger surface/volume ratio of microchannel, the surface effects increase as channel scale decreases. Here we show the scale effect of the boundary condition at the solid–liquid interface on single-phase convective heat transfer characteristics in microchannels. We demonstrate that the deviation from classical theory with a reduction in hydraulic diameters is due to the breakdown of the continuum solid–liquid boundary condition. The forced convective heat transfer characteristics of single-phase laminar flow in a parallel-plate microchannel are investigated. Using the theoretical Poiseuille and Nusselt numbers derived under the slip boundary condition at the solid–liquid interface, we estimate the slip length and thermal slip length at the interface. PMID:28256536

Advanced turbo-prop airplane interior noise reduction-source definition

NASA Technical Reports Server (NTRS)

Magliozzi, B.; Brooks, B. M.

1979-01-01

Acoustic pressure amplitudes and phases were measured in model scale on the surface of a rigid semicylinder mounted in an acoustically treated wind tunnel near a prop-fan (an advanced turboprop with many swept blades) model. Operating conditions during the test simulated those of a prop-fan at 0.8 Mach number cruise. Acoustic pressure amplitude and phase contours were defined on the semicylinder surface. Measurements obtained without the semi-cylinder in place were used to establish the magnitude of pressure doubling for an aircraft fuselage located near a prop-fan. Pressure doubling effects were found to be 6dB at 90 deg incidence decreasing to no effect at grazing incidence. Comparisons of measurements with predictions made using a recently developed prop-fan noise prediction theory which includes linear and non-linear source terms showed good agreement in phase and in peak noise amplitude. Predictions of noise amplitude and phase contours, including pressure doubling effects derived from test, are included for a full scale prop-fan installation.

Nanometer-scale displacement measurement with high resolution using dual cavity Fabry-Pérot interferometer for biomimetic robots.

PubMed

Lee, Jin-Hyuk; Kim, Dae-Hyun

2014-10-01

A sensor of a biomimetic robot has to measure very small environmental changes such as, nanometer scale strains or displacements. Fiber optic sensor can be also one of candidates for the biomimetic sensor because the sensor is like thread and the shape of the sensor is similar to muscle fiber. A fiber optic interferometer, which is an optical-based sensor, can measure displacement precisely, so such device has been widely studied for the measurement of displacement on a nanometer-scale. Especially, a Quadrature Phase-Shifted Fiber Fabry-Pérot interferometer (QPS-FFPI) uses phase-information for this measurement, allowing it to provide a precision result with high resolution. In theory, the QPS-FFPI generates two sinusoidal signals of which the phase difference should be 90 degrees for the exact measurement of the displacement. In order to guarantee the condition of the phase difference, the relative adjustment of the cavities of the optical fibers is required. However, with such precise adjustment it is very hard to fix the proper difference of the two cavities for quadrature-phase-shifting. In this paper, a dual-cavity FFPI is newly proposed to measure the displacement on a nanometer-scale with a specific type of signal processing. In the signal processing, a novel phase-compensation algorithm is applied to force the phase difference to be exactly 90 degrees without any physical adjustment. As a result, the paper shows that the phase-compensated dual-cavity FFPI can effectively measure nanometer-scale displacement with high resolution under dynamic conditions.

Hybrid network modeling and the effect of image resolution on digitally-obtained petrophysical and two-phase flow properties

NASA Astrophysics Data System (ADS)

Aghaei, A.

2017-12-01

Digital imaging and modeling of rocks and subsequent simulation of physical phenomena in digitally-constructed rock models are becoming an integral part of core analysis workflows. One of the inherent limitations of image-based analysis, at any given scale, is image resolution. This limitation becomes more evident when the rock has multiple scales of porosity such as in carbonates and tight sandstones. Multi-scale imaging and constructions of hybrid models that encompass images acquired at multiple scales and resolutions are proposed as a solution to this problem. In this study, we investigate the effect of image resolution and unresolved porosity on petrophysical and two-phase flow properties calculated based on images. A helical X-ray micro-CT scanner with a high cone-angle is used to acquire digital rock images that are free of geometric distortion. To remove subjectivity from the analyses, a semi-automated image processing technique is used to process and segment the acquired data into multiple phases. Direct and pore network based models are used to simulate physical phenomena and obtain absolute permeability, formation factor and two-phase flow properties such as relative permeability and capillary pressure. The effect of image resolution on each property is investigated. Finally a hybrid network model incorporating images at multiple resolutions is built and used for simulations. The results from the hybrid model are compared against results from the model built at the highest resolution and those from laboratory tests.

Phase correction for ALMA. Investigating water vapour radiometer scaling: The long-baseline science verification data case study

NASA Astrophysics Data System (ADS)

Maud, L. T.; Tilanus, R. P. J.; van Kempen, T. A.; Hogerheijde, M. R.; Schmalzl, M.; Yoon, I.; Contreras, Y.; Toribio, M. C.; Asaki, Y.; Dent, W. R. F.; Fomalont, E.; Matsushita, S.

2017-09-01

The Atacama Large millimetre/submillimetre Array (ALMA) makes use of water vapour radiometers (WVR), which monitor the atmospheric water vapour line at 183 GHz along the line of sight above each antenna to correct for phase delays introduced by the wet component of the troposphere. The application of WVR derived phase corrections improve the image quality and facilitate successful observations in weather conditions that were classically marginal or poor. We present work to indicate that a scaling factor applied to the WVR solutions can act to further improve the phase stability and image quality of ALMA data. We find reduced phase noise statistics for 62 out of 75 datasets from the long-baseline science verification campaign after a WVR scaling factor is applied. The improvement of phase noise translates to an expected coherence improvement in 39 datasets. When imaging the bandpass source, we find 33 of the 39 datasets show an improvement in the signal-to-noise ratio (S/N) between a few to 30 percent. There are 23 datasets where the S/N of the science image is improved: 6 by <1%, 11 between 1 and 5%, and 6 above 5%. The higher frequencies studied (band 6 and band 7) are those most improved, specifically datasets with low precipitable water vapour (PWV), <1 mm, where the dominance of the wet component is reduced. Although these improvements are not profound, phase stability improvements via the WVR scaling factor come into play for the higher frequency (>450 GHz) and long-baseline (>5 km) observations. These inherently have poorer phase stability and are taken in low PWV (<1 mm) conditions for which we find the scaling to be most effective. A promising explanation for the scaling factor is the mixing of dry and wet air components, although other origins are discussed. We have produced a python code to allow ALMA users to undertake WVR scaling tests and make improvements to their data.

Development and Validation of a Fatigue Assessment Scale for U.S. Construction Workers

PubMed Central

Zhang, Mingzong; Sparer, Emily H.; Murphy, Lauren A.; Dennerlein, Jack T.; Fang, Dongping; Katz, Jeffrey N.; Caban-Martinez, Alberto J.

2015-01-01

Objective To develop a fatigue assessment scale and test its reliability and validity for commercial construction workers. Methods Using a two-phased approach, we first identified items for the development of a Fatigue Assessment Scale for Construction Workers (FASCW) through review of existing scales in the scientific literature, key informant interviews (n=11) and focus groups (3 groups with 6 workers each) with construction workers. The second phase included assessment for the reliability, validity and sensitivity of the new scale using a repeated-measures study design with a convenience sample of construction workers (n=144). Results Phase one resulted in a 16-item preliminary scale that after factor analysis yielded a final 10-item scale with two sub-scales (“Lethargy” and “Bodily Ailment”).. During phase two, the FASCW and its subscales demonstrated satisfactory internal consistency (alpha coefficients were FASCW (0.91), Lethargy (0.86) and Bodily Ailment (0.84)) and acceptable test-retest reliability (Pearson Correlations Coefficients: 0.59–0.68; Intraclass Correlation Coefficients: 0.74–0.80). Correlation analysis substantiated concurrent and convergent validity. A discriminant analysis demonstrated that the FASCW differentiated between groups with arthritis status and different work hours. Conclusions The 10-item FASCW with good reliability and validity is an effective tool for assessing the severity of fatigue among construction workers. PMID:25603944

A prototype automatic phase compensation module

NASA Technical Reports Server (NTRS)

Terry, John D.

1992-01-01

The growing demands for high gain and accurate satellite communication systems will necessitate the utilization of large reflector systems. One area of concern of reflector based satellite communication is large scale surface deformations due to thermal effects. These distortions, when present, can degrade the performance of the reflector system appreciable. This performance degradation is manifested by a decrease in peak gain, and increase in sidelobe level, and pointing errors. It is essential to compensate for these distortion effects and to maintain the required system performance in the operating space environment. For this reason the development of a technique to offset the degradation effects is highly desirable. Currently, most research is direct at developing better material for the reflector. These materials have a lower coefficient of linear expansion thereby reducing the surface errors. Alternatively, one can minimize the distortion effects of these large scale errors by adaptive phased array compensation. Adaptive phased array techniques have been studied extensively at NASA and elsewhere. Presented in this paper is a prototype automatic phase compensation module designed and built at NASA Lewis Research Center which is the first stage of development for an adaptive array compensation module.

Phase transitions and baryogenesis from decays

DOE PAGES

Shuve, Brian; Tamarit, Carlos

2017-10-18

Here, we study scenarios in which the baryon asymmetry is generated from the decay of a particle whose mass originates from the spontaneous breakdown of a symmetry. This is realized in many models, including low-scale leptogenesis and theories with classical scale invariance. Symmetry breaking in the early universe proceeds through a phase transition that gives the parent particle a time-dependent mass, which provides an additional departure from thermal equilibrium that could modify the efficiency of baryogenesis from out-of-equilibrium decays. We characterize the effects of various types of phase transitions and show that an enhancement in the baryon asymmetry from decaysmore » is possible if the phase transition is of the second order, although such models are typically fine-tuned. We also stress the role of new annihilation modes that deplete the parent particle abundance in models realizing such a phase transition, reducing the efficacy of baryogenesis. A proper treatment of baryogenesis in such models therefore requires the inclusion of the effects we study in this paper.« less

Phase transitions and baryogenesis from decays

NASA Astrophysics Data System (ADS)

Shuve, Brian; Tamarit, Carlos

2017-10-01

We study scenarios in which the baryon asymmetry is generated from the decay of a particle whose mass originates from the spontaneous breakdown of a symmetry. This is realized in many models, including low-scale leptogenesis and theories with classical scale invariance. Symmetry breaking in the early universe proceeds through a phase transition that gives the parent particle a time-dependent mass, which provides an additional departure from thermal equilibrium that could modify the efficiency of baryogenesis from out-of-equilibrium decays. We characterize the effects of various types of phase transitions and show that an enhancement in the baryon asymmetry from decays is possible if the phase transition is of the second order, although such models are typically fine-tuned. We also stress the role of new annihilation modes that deplete the parent particle abundance in models realizing such a phase transition, reducing the efficacy of baryogenesis. A proper treatment of baryogenesis in such models therefore requires the inclusion of the effects we study in this paper.

Nanoscale phase transition behavior of shape memory alloys — closed form solution of 1D effective modelling

NASA Astrophysics Data System (ADS)

Li, M. P.; Sun, Q. P.

2018-01-01

We investigate the roles of grain size (lg) and grain boundary thickness (lb) on the stress-induced phase transition (PT) behaviors of nanocrystalline shape memory alloys (SMAs) by using a Core-shell type "crystallite-amorphous composite" model. A non-dimensionalized length scale lbarg(=lg /lb) is identified as the governing parameter which is indicative of the energy competition between the crystallite and the grain boundary. Closed form analytical solutions of a reduced effective 1D model with embedded microstructure length scales of lg and lb are presented in this paper. It is shown that, with lbarg reduction, the energy of the elastic non-transformable grain boundary will gradually become dominant in the phase transition process, and eventually bring fundamental changes of the deformation behaviors: breakdown of two-phase coexistence and vanishing of superelastic hysteresis. The predictions are supported by experimental data of nanocrystalline NiTi SMAs.

Two-harmonic complex spectral-domain optical coherence tomography using achromatic sinusoidal phase modulation

NASA Astrophysics Data System (ADS)

Lu, Sheng-Hua; Huang, Siang-Ru; Chou, Che-Chung

2018-03-01

We resolve the complex conjugate ambiguity in spectral-domain optical coherence tomography (SD-OCT) by using achromatic two-harmonic method. Unlike previous researches, the optical phase of the fiber interferometer is modulated by an achromatic phase shifter based on an optical delay line. The achromatic phase modulation leads to a wavelength-independent scaling coefficient for the two harmonics. Dividing the mean absolute value of the first harmonic by that of the second harmonic in a B-scan interferogram directly gives the scaling coefficient. It greatly simplifies the determination of the magnitude ratio between the two harmonics without the need of third harmonic and cumbersome iterative calculations. The inverse fast Fourier transform of the complex-valued interferogram constructed with the scaling coefficient, first and second harmonics yields a full-range OCT image. Experimental results confirm the effectiveness of the proposed achromatic two-harmonic technique for suppressing the mirror artifacts in SD-OCT images.

Pore-scale modeling of wettability effects on CO2-brine displacement during geological storage

NASA Astrophysics Data System (ADS)

Basirat, Farzad; Yang, Zhibing; Niemi, Auli

2017-11-01

Wetting properties of reservoir rocks and caprocks can vary significantly, and they strongly influence geological storage of carbon dioxide in deep saline aquifers, during which CO2 is supposed to displace the resident brine and to become permanently trapped. Fundamental understanding of the effect of wettability on CO2-brine displacement is thus important for improving storage efficiency and security. In this study, we investigate the influence of wetting properties on two-phase flow of CO2 and brine at the pore scale. A numerical model based on the phase field method is implemented to simulate the two-phase flow of CO2-brine in a realistic pore geometry. Our focus is to study the pore-scale fluid-fluid displacement mechanisms under different wetting conditions and to quantify the effect of wettability on macroscopic parameters such as residual brine saturation, capillary pressure, relative permeability, and specific interfacial area. Our simulation results confirm that both the trapped wetting phase saturation and the normalized interfacial area increase with decreasing contact angle. However, the wetting condition does not appear to influence the CO2 breakthrough time and saturation. We also show that the macroscopic capillary pressures based on the pressure difference between inlet and outlet can differ significantly from the phase averaging capillary pressures for all contact angles when the capillary number is high (log Ca > -5). This indicates that the inlet-outlet pressure difference may not be a good measure of the continuum-scale capillary pressure. In addition, the results show that the relative permeability of CO2 can be significantly lower in strongly water-wet conditions than in the intermediate-wet conditions.

Phase-dependent outbreak dynamics of geometrid moth linked to host plant phenology.

PubMed

Jepsen, Jane U; Hagen, Snorre B; Karlsen, Stein-Rune; Ims, Rolf A

2009-12-07

Climatically driven Moran effects have often been invoked as the most likely cause of regionally synchronized outbreaks of insect herbivores without identifying the exact mechanism. However, the degree of match between host plant and larval phenology is crucial for the growth and survival of many spring-feeding pest insects, suggesting that a phenological match/mismatch-driven Moran effect may act as a synchronizing agent. We analyse the phase-dependent spatial dynamics of defoliation caused by cyclically outbreaking geometrid moths in northern boreal birch forest in Fennoscandia through the most recent massive outbreak (2000-2008). We use satellite-derived time series of the prevalence of moth defoliation and the onset of the growing season for the entire region to investigate the link between the patterns of defoliation and outbreak spread. In addition, we examine whether a phase-dependent coherence in the pattern of spatial synchrony exists between defoliation and onset of the growing season, in order to evaluate if the degree of matching phenology between the moth and their host plant could be the mechanism behind a Moran effect. The strength of regional spatial synchrony in defoliation and the pattern of defoliation spread were both highly phase-dependent. The incipient phase of the outbreak was characterized by high regional synchrony in defoliation and long spread distances, compared with the epidemic and crash phase. Defoliation spread was best described using a two-scale stratified spread model, suggesting that defoliation spread is governed by two processes operating at different spatial scale. The pattern of phase-dependent spatial synchrony was coherent in both defoliation and onset of the growing season. This suggests that the timing of spring phenology plays a role in the large-scale synchronization of birch forest moth outbreaks.

Phase-dependent outbreak dynamics of geometrid moth linked to host plant phenology

PubMed Central

Jepsen, Jane U.; Hagen, Snorre B.; Karlsen, Stein-Rune; Ims, Rolf A.

2009-01-01

Climatically driven Moran effects have often been invoked as the most likely cause of regionally synchronized outbreaks of insect herbivores without identifying the exact mechanism. However, the degree of match between host plant and larval phenology is crucial for the growth and survival of many spring-feeding pest insects, suggesting that a phenological match/mismatch-driven Moran effect may act as a synchronizing agent. We analyse the phase-dependent spatial dynamics of defoliation caused by cyclically outbreaking geometrid moths in northern boreal birch forest in Fennoscandia through the most recent massive outbreak (2000–2008). We use satellite-derived time series of the prevalence of moth defoliation and the onset of the growing season for the entire region to investigate the link between the patterns of defoliation and outbreak spread. In addition, we examine whether a phase-dependent coherence in the pattern of spatial synchrony exists between defoliation and onset of the growing season, in order to evaluate if the degree of matching phenology between the moth and their host plant could be the mechanism behind a Moran effect. The strength of regional spatial synchrony in defoliation and the pattern of defoliation spread were both highly phase-dependent. The incipient phase of the outbreak was characterized by high regional synchrony in defoliation and long spread distances, compared with the epidemic and crash phase. Defoliation spread was best described using a two-scale stratified spread model, suggesting that defoliation spread is governed by two processes operating at different spatial scale. The pattern of phase-dependent spatial synchrony was coherent in both defoliation and onset of the growing season. This suggests that the timing of spring phenology plays a role in the large-scale synchronization of birch forest moth outbreaks. PMID:19740876

Priming effects on labile and stable soil organic carbon decomposition: Pulse dynamics over two years

PubMed Central

Han, Xiaozeng; Yu, Wantai; Wang, Peng; Cheng, Weixin

2017-01-01

Soil organic carbon (SOC) is a major component in the global carbon cycle. Yet how input of plant litter may influence the loss of SOC through a phenomenon called priming effect remains highly uncertain. Most published results about the priming effect came from short-term investigations for a few weeks or at the most for a few months in duration. The priming effect has not been studied at the annual time scale. In this study for 815 days, we investigated the priming effect of added maize leaves on SOC decomposition of two soil types and two treatments (bare fallow for 23 years, and adjacent old-field, represent stable and relatively labile SOC, respectively) of SOC stabilities within each soil type, using a natural 13C-isotope method. Results showed that the variation of the priming effect through time had three distinctive phases for all soils: (1) a strong negative priming phase during the first period (≈0–90 days); (2) a pulse of positive priming phase in the middle (≈70–160 and 140–350 days for soils from Hailun and Shenyang stations, respectively); and (3) a relatively stabilized phase of priming during the last stage of the incubation (>160 days and >350 days for soils from Hailun and Shenyang stations, respectively). Because of major differences in soil properties, the two soil types produced different cumulative priming effects at the end of the experiment, a positive priming effect of 3–7% for the Mollisol and a negative priming effect of 4–8% for the Alfisol. Although soil types and measurement times modulated most of the variability of the priming effect, relative SOC stabilities also influenced the priming effect for a particular soil type and at a particular dynamic phase. The stable SOC from the bare fallow treatment tended to produce a narrower variability during the first phase of negative priming and also during the second phase of positive priming. Averaged over the entire experiment, the stable SOC (i.e., the bare fallow) was at least as responsive to priming as the relatively labile SOC (i.e., the old-field) if not more responsive. The annual time scale of our experiment allowed us to demonstrate the three distinctive phases of the priming effect. Our results highlight the importance of studying the priming effect by investigating the temporal dynamics over longer time scales. PMID:28934287

Surface acidity scales: Experimental measurements of Brønsted acidities on anatase TiO2 and comparison with coinage metal surfaces

NASA Astrophysics Data System (ADS)

Silbaugh, Trent L.; Boaventura, Jaime S.; Barteau, Mark A.

2016-08-01

The first quantitative surface acidity scale for Brønsted acids on a solid surface is presented through the use of titration-displacement and equilibrium experiments on anatase TiO2. Surface acidities of species on TiO2 correlated with gas phase acidities, as was previously observed in qualitative studies of Brønsted acid displacement on Ag(110), Cu(110) and Au(111). A 90% compression of the surface acidity scale relative to the gas phase was observed due to compensation from the covalent component of the conjugate base - surface bond. Adsorbed conjugate bases need not be completely anionic for correlations with gas phase acidities to hold. Positive and negative substituent effects, such as substituted fluorine and hydrocarbon sidechain dispersion interactions with the surface, may modify the surface acidity scale, in agreement with previous experimental and theoretical work on Au(111).

Effects of the underlying topology on perturbation spreading in the Axelrod model for cultural dissemination

NASA Astrophysics Data System (ADS)

Kim, Yup; Cho, Minsoo; Yook, Soon-Hyung

2011-10-01

We study the effects of the underlying topologies on a single feature perturbation imposed to the Axelrod model of consensus formation. From the numerical simulations we show that there are successive updates which are similar to avalanches in many self-organized criticality systems when a perturbation is imposed. We find that the distribution of avalanche size satisfies the finite-size scaling (FSS) ansatz on two-dimensional lattices and random networks. However, on scale-free networks with the degree exponent γ≤3 we show that the avalanche size distribution does not satisfy the FSS ansatz. The results indicate that the disordered configurations on two-dimensional lattices or on random networks are still stable against the perturbation in the limit N (network size) →∞. However, on scale-free networks with γ≤3 the perturbation always drives the disordered phase into an ordered phase. The possible relationship between the properties of phase transition of the Axelrod model and the avalanche distribution is also discussed.

The Impact of Nonequilibrium and Equilibrium Fractionation on Two Different Deuterium Excess Definitions

NASA Astrophysics Data System (ADS)

Dütsch, Marina; Pfahl, Stephan; Sodemann, Harald

2017-12-01

The deuterium excess (d) is a useful measure for nonequilibrium effects of isotopic fractionation and can therefore provide information about the meteorological conditions in evaporation regions or during ice cloud formation. In addition to nonequilibrium fractionation, two other effects can change d during phase transitions. The first is the dependence of the equilibrium fractionation factors on temperature, and the second is the nonlinearity of the δ scale on which d is defined. The second effect can be avoided by using an alternative definition that is based on the logarithmic scale. However, in this case d is not conserved when air parcels mix, which can lead to changes without phase transitions. Here we provide a systematic analysis of the benefits and limitations of both deuterium excess definitions by separately quantifying the impact of the nonequilibrium effect, the temperature effect, the δ-scale effect, and the mixing effect in a simple Rayleigh model simulating the isotopic composition of air parcels during moist adiabatic ascent. The δ-scale effect is important in depleted air parcels, for which it can change the sign of the traditional deuterium excess in the remaining vapor from negative to positive. The alternative definition mainly reflects the nonequilibrium and temperature effect, while the mixing effect is about 2 orders of magnitude smaller. Thus, the alternative deuterium excess definition appears to be a more accurate measure for nonequilibrium effects in situations where moisture is depleted and the δ-scale effect is large, for instance, at high latitudes or altitudes.

Effect of deformation induced nucleation and phase mixing, a two phase model for the ductile deformation of rocks.

NASA Astrophysics Data System (ADS)

Bevillard, Benoit; Richard, Guillaume; Raimbourg, Hugues

2017-04-01

Rocks are complex materials and particularly their rheological behavior under geological stresses remains a long-standing question in geodynamics. To test large scale lithosphere dynamics numerical modeling is the main tool but encounter substantial difficulties to account for this complexity. One major unknown is the origin and development of the localization of deformation. This localization is observed within a large range of scales and is commonly characterized by sharp grain size reduction. These considerations argues for a control of the microscopical scale over the largest ones through one predominant variable: the mean grain-size. However, the presence of second phase and broad grain-size distribution may also have a important impact on this phenomenon. To address this question, we built a model for ductile rocks deformation based on the two-phase damage theory of Bercovici & Ricard 2012. We aim to investigate the role of grain-size reduction but also phase mixing on strain localization. Instead of considering a Zener-pining effect on damage evolution, we propose to take into account the effect of the grain-boundary sliding (GBS)-induced nucleation mechanism which is better supported by experimental or natural observations (Precigout et al 2016). This continuum theory allows to represent a two mineral phases aggregate with explicit log-normal grain-size distribution as a reasonable approximation for polymineralic rocks. Quantifying microscopical variables using a statistical approach may allow for calibration at small (experimental) scale. The general set of evolutions equations remains up-scalable provided some conditions on the homogenization scale. Using the interface density as a measure of mixture quality, we assume unlike Bercovici & Ricard 2012 that it may depend for some part on grain-size . The grain-size independent part of it is being represented by a "contact fraction" variable, whose evolution may be constrained by the dominant deformation mechanism. To derive the related evolution equations and account for the interdependence of thermodynamic state variables, we use Onsager's thermodynamic extremum principle. Eventually, we solve for our set of equations using an Anorthite/Pyroxene gabbroic composition. The results are used to discuss the interaction between grain-size reduction and phase mixing on strain localization on several simple cases. Bercovici D, Ricard Y (2012) Mechanisms for the generation of plate tectonics by two phase grain damage and pinning. Physics of the Earth and Planetary Interiors 202-203:27-55 Precigout J, Stunitz H (2016) Evidence of phase nucleation during olivine diffusion creep: A new perspective for mantle strain localisation. Earth and Planetary Science Letters 405:94-105

Polarizable molecular interactions in condensed phase and their equivalent nonpolarizable models.

PubMed

Leontyev, Igor V; Stuchebrukhov, Alexei A

2014-07-07

Earlier, using phenomenological approach, we showed that in some cases polarizable models of condensed phase systems can be reduced to nonpolarizable equivalent models with scaled charges. Examples of such systems include ionic liquids, TIPnP-type models of water, protein force fields, and others, where interactions and dynamics of inherently polarizable species can be accurately described by nonpolarizable models. To describe electrostatic interactions, the effective charges of simple ionic liquids are obtained by scaling the actual charges of ions by a factor of 1/√(ε(el)), which is due to electronic polarization screening effect; the scaling factor of neutral species is more complicated. Here, using several theoretical models, we examine how exactly the scaling factors appear in theory, and how, and under what conditions, polarizable Hamiltonians are reduced to nonpolarizable ones. These models allow one to trace the origin of the scaling factors, determine their values, and obtain important insights on the nature of polarizable interactions in condensed matter systems.

The effects of fluoxetine on the subjective and physiological effects of 3,4-methylenedioxymethamphetamine (MDMA) in humans.

PubMed

Tancer, Manuel; Johanson, Chris-Ellyn

2007-01-01

The purpose of this study was to investigate the role of serotonin (5-HT) in the effects of oral 3,4-methylenedioxymethamphetamine (MDMA) in humans. The subjective and physiological effects of 1.5 mg/kg MDMA were evaluated after 20 mg fluoxetine in eight recreational MDMA users in a double-blind, placebo-controlled study. During phase 1, participants were maintained on placebo for at least 5 days and tested with MDMA and placebo on separate sessions. In phase 2, the procedure was the same except fluoxetine was administered daily for at least 5 days. During sessions, placebo or fluoxetine was given 1 h before the session drug and effects were measured over the next 7 h. MDMA increased positive-like subjective effects on all the Addiction Research Center Inventory scales; Arousal, Elation, Positive Mood, and Vigor on the Profile of Mood States; Drug Liking, Friendly, Good Drug Effect, High, Stimulated, and Talkative on the Visual Analog Scale; and End-of-Session Liking and Crossover Point on the Multiple Choice Procedure. MDMA also increased measures of anxiety. On the Hallucinogenic Rating Scale, all scales except Volition were increased. MDMA also increased blood pressure and heart rate. Fluoxetine treatment attenuated most of the positive-like subjective effects including the Affect and Soma scales of the Hallucinogen Rating Scale. In addition, heart rate but not blood pressure increases were reduced. These results suggest that blockade of 5-HT reuptake by fluoxetine can dampen the effects of MDMA and further supports the role of 5-HT in its behavioral effects in humans.

Small Scale Response and Modeling of Periodically Forced Turbulence

NASA Technical Reports Server (NTRS)

Bos, Wouter; Clark, Timothy T.; Rubinstein, Robert

2007-01-01

The response of the small scales of isotropic turbulence to periodic large scale forcing is studied using two-point closures. The frequency response of the turbulent kinetic energy and dissipation rate, and the phase shifts between production, energy and dissipation are determined as functions of Reynolds number. It is observed that the amplitude and phase of the dissipation exhibit nontrivial frequency and Reynolds number dependence that reveals a filtering effect of the energy cascade. Perturbation analysis is applied to understand this behavior which is shown to depend on distant interactions between widely separated scales of motion. Finally, the extent to which finite dimensional models (standard two-equation models and various generalizations) can reproduce the observed behavior is discussed.

Effects of liquid layers and distribution patterns on three-phase saturation and relative permeability relationships: a micromodel study.

PubMed

Tsai, Jui-Pin; Chang, Liang-Cheng; Hsu, Shao-Yiu; Shan, Hsin-Yu

2017-12-01

In the current study, we used micromodel experiments to study three-phase fluid flow in porous media. In contrast to previous studies, we simultaneously observed and measured pore-scale fluid behavior and three-phase constitutive relationships with digital image acquisition/analysis, fluid pressure control, and permeability assays. Our results showed that the fluid layers significantly influenced pore-scale, three-phase fluid displacement as well as water relative permeability. At low water saturation, water relative permeability not only depended on water saturation but also on the distributions of air and diesel. The results also indicate that the relative permeability-saturation model proposed by Parker et al. (1987) could not completely describe the experimental data from our three-phase flow experiments because these models ignore the effects of phase distribution. A simple bundle-of-tubes model shows that the water relative permeability was proportional to the number of apparently continuous water paths before the critical stage in which no apparently continuous water flow path could be found. Our findings constitute additional information about the essential constitutive relationships involved in both the understanding and the modeling of three-phase flows in porous media.

Effective density and morphology of particles emitted from small-scale combustion of various wood fuels.

PubMed

Leskinen, Jani; Ihalainen, Mika; Torvela, Tiina; Kortelainen, Miika; Lamberg, Heikki; Tiitta, Petri; Jakobi, Gert; Grigonyte, Julija; Joutsensaari, Jorma; Sippula, Olli; Tissari, Jarkko; Virtanen, Annele; Zimmermann, Ralf; Jokiniemi, Jorma

2014-11-18

The effective density of fine particles emitted from small-scale wood combustion of various fuels were determined with a system consisting of an aerosol particle mass analyzer and a scanning mobility particle sizer (APM-SMPS). A novel sampling chamber was combined to the system to enable measurements of highly fluctuating combustion processes. In addition, mass-mobility exponents (relates mass and mobility size) were determined from the density data to describe the shape of the particles. Particle size, type of fuel, combustion phase, and combustion conditions were found to have an effect on the effective density and the particle shape. For example, steady combustion phase produced agglomerates with effective density of roughly 1 g cm(-3) for small particles, decreasing to 0.25 g cm(-3) for 400 nm particles. The effective density was higher for particles emitted from glowing embers phase (ca. 1-2 g cm(-3)), and a clear size dependency was not observed as the particles were nearly spherical in shape. This study shows that a single value cannot be used for the effective density of particles emitted from wood combustion.

Intermediate scale plasma density irregularities in the polar ionosphere inferred from radio occultation

NASA Astrophysics Data System (ADS)

Shume, E. B.; Komjathy, A.; Langley, R. B.; Verkhoglyadova, O. P.; Butala, M.; Mannucci, A. J.

2014-12-01

In this research, we report intermediate scale plasma density irregularities in the high-latitude ionosphere inferred from high-resolution radio occultation (RO) measurements in the CASSIOPE (CAScade Smallsat and IOnospheric Polar Explorer) - GPS (Global Positioning System) satellites radio link. The high inclination of the CASSIOPE satellite and high rate of signal receptionby the occultation antenna of the GPS Attitude, Positioning and Profiling (GAP) instrument on the Enhanced Polar Outflow Probe platform on CASSIOPE enable a high temporal and spatial resolution investigation of the dynamics of the polar ionosphere, magnetosphere-ionospherecoupling, solar wind effects, etc. with unprecedented details compared to that possible in the past. We have carried out high spatial resolution analysis in altitude and geomagnetic latitude of scintillation-producing plasma density irregularities in the polar ionosphere. Intermediate scale, scintillation-producing plasma density irregularities, which corresponds to 2 to 40 km spatial scales were inferred by applying multi-scale spectral analysis on the RO phase delay measurements. Using our multi-scale spectral analysis approach and Polar Operational Environmental Satellites (POES) and Defense Meteorological Satellite Program (DMSP) observations, we infer that the irregularity scales and phase scintillations have distinct features in the auroral oval and polar cap regions. In specific terms, we found that large length scales and and more intense phase scintillations are prevalent in the auroral oval compared to the polar cap region. Hence, the irregularity scales and phase scintillation characteristics are a function of the solar wind and the magnetospheric forcing. Multi-scale analysis may become a powerful diagnostic tool for characterizing how the ionosphere is dynamically driven by these factors.

Persistent Homology to describe Solid and Fluid Structures during Multiphase Flow

NASA Astrophysics Data System (ADS)

Herring, A. L.; Robins, V.; Liu, Z.; Armstrong, R. T.; Sheppard, A.

2017-12-01

The question of how to accurately and effectively characterize essential fluid and solid distributions and structures is a long-standing topic within the field of porous media and fluid transport. For multiphase flow applications, considerable research effort has been made to describe fluid distributions under a range of conditions; including quantification of saturation levels, fluid-fluid pressure differences and interfacial areas, and fluid connectivity. Recent research has effectively used topological metrics to describe pore space and fluid connectivity, with researchers demonstrating links between pore-scale nonwetting phase topology to fluid mobilization and displacement mechanisms, relative permeability, fluid flow regimes, and thermodynamic models of multiphase flow. While topology is clearly a powerful tool to describe fluid distribution, topological metrics by definition provide information only on the connectivity of a phase, not its geometry (shape or size). Physical flow characteristics, e.g. the permeability of a fluid phase within a porous medium, are dependent on the connectivity of the pore space or fluid phase as well as the size of connections. Persistent homology is a technique which provides a direct link between topology and geometry via measurement of topological features and their persistence from the signed Euclidean distance transform of a segmented digital image (Figure 1). We apply persistent homology analysis to measure the occurrence and size of pore-scale topological features in a variety of sandstones, for both the dry state and the nonwetting phase fluid during two-phase fluid flow (drainage and imbibition) experiments, visualized with 3D X-ray microtomography. The results provide key insights into the dominant topological features and length scales of a media which control relevant field-scale engineering properties such as fluid trapping, absolute permeability, and relative permeability.

Drastic disorder-induced reduction of signal amplification in scale-free networks.

PubMed

Chacón, Ricardo; Martínez, Pedro J

2015-07-01

Understanding information transmission across a network is a fundamental task for controlling and manipulating both biological and manmade information-processing systems. Here we show how topological resonant-like amplification effects in scale-free networks of signaling devices are drastically reduced when phase disorder in the external signals is considered. This is demonstrated theoretically by means of a starlike network of overdamped bistable systems, and confirmed numerically by simulations of scale-free networks of such systems. The taming effect of the phase disorder is found to be sensitive to the amplification's strength, while the topology-induced amplification mechanism is robust against this kind of quenched disorder in the sense that it does not significantly change the values of the coupling strength where amplification is maximum in its absence.

Parametric study of the effect of phase anisotropy on the micromechanical behaviour of dentin–adhesive interfaces

PubMed Central

Misra, Anil; Spencer, Paulette; Marangos, Orestes; Wang, Yong; Katz, J. Lawrence

2005-01-01

A finite element (FE) model has been developed based upon the recently measured micro-scale morphological, chemical and mechanical properties of dentin–adhesive (d–a) interfaces using confocal Raman microspectroscopy and scanning acoustic microscopy (SAM). The results computed from this FE model indicated that the stress distributions and concentrations are affected by the micro-scale elastic properties of various phases composing the d–a interface. However, these computations were performed assuming isotropic material properties for the d–a interface. The d–a interface components, such as the peritubular and intertubular dentin, the partially demineralized dentin and the so-called ‘hybrid layer’ adhesive-collagen composite, are probably anisotropic. In this paper, the FE model is extended to account for the probable anisotropic properties of these d–a interface phases. A parametric study is performed to study the effect of anisotropy on the micromechanical stress distributions in the hybrid layer and the peritubular dentin phases of the d–a interface. It is found that the anisotropy of the phases affects the region and extent of stress concentration as well as the location of the maximum stress concentrations. Thus, the anisotropy of the phases could effect the probable location of failure initiation, whether in the peritubular region or in the hybrid layer. PMID:16849175

Pore-scale characterization of biogeochemical controls on iron and uranium speciation under flow conditions.

PubMed

Pearce, Carolyn I; Wilkins, Michael J; Zhang, Changyong; Heald, Steve M; Fredrickson, Jim K; Zachara, John M

2012-08-07

Etched silicon microfluidic pore network models (micromodels) with controlled chemical and redox gradients, mineralogy, and microbiology under continuous flow conditions are used for the incremental development of complex microenvironments that simulate subsurface conditions. We demonstrate the colonization of micromodel pore spaces by an anaerobic Fe(III)-reducing bacterial species (Geobacter sulfurreducens) and the enzymatic reduction of a bioavailable Fe(III) phase within this environment. Using both X-ray microprobe and X-ray absorption spectroscopy, we investigate the combined effects of the precipitated Fe(III) phases and the microbial population on uranium biogeochemistry under flow conditions. Precipitated Fe(III) phases within the micromodel were most effectively reduced in the presence of an electron shuttle (AQDS), and Fe(II) ions adsorbed onto the precipitated mineral surface without inducing any structural change. In the absence of Fe(III), U(VI) was effectively reduced by the microbial population to insoluble U(IV), which was precipitated in discrete regions associated with biomass. In the presence of Fe(III) phases, however, both U(IV) and U(VI) could be detected associated with biomass, suggesting reoxidation of U(IV) by localized Fe(III) phases. These results demonstrate the importance of the spatial localization of biomass and redox active metals, and illustrate the key effects of pore-scale processes on contaminant fate and reactive transport.

On effects of topography in rotating flows

NASA Astrophysics Data System (ADS)

Burmann, Fabian; Noir, Jerome; Jackson, Andrew

2017-11-01

Both, seismological studies and geodynamic arguments suggest that there is significant topography at the core mantle boundary (CMB). This leads to the question whether the topography of the CMB could influence the flow in the Earth's outer core. As a preliminary experiment, we investigate the effects of bottom topography in the so-called Spin-Up, where motion of a contained fluid is created by a sudden increase of rotation rate. Experiments are performed in a cylindrical container mounted on a rotating table and quantitative results are obtained with particle image velocimetry. Several horizontal length scales of topography (λ) are investigated, ranging from cases where λ is much smaller then the lateral extend of the experiment (R) to cases where λ is a fraction of R. We find that there is an optimal λ that creates maximum dissipation of kinetic energy. Depending on the length scale of the topography, kinetic energy is either dissipated in the boundary layer or in the bulk of the fluid. Two different phases of fluid motion are present: a starting flow in the from of solid rotation (phase I), which is later replaced by meso scale vortices on the length scale of bottom topography (phase II).

Macroscopic modeling of heat and water vapor transfer with phase change in dry snow based on an upscaling method: Influence of air convection

NASA Astrophysics Data System (ADS)

Calonne, N.; Geindreau, C.; Flin, F.

2015-12-01

At the microscopic scale, i.e., pore scale, dry snow metamorphism is mainly driven by the heat and water vapor transfer and the sublimation-deposition process at the ice-air interface. Up to now, the description of these phenomena at the macroscopic scale, i.e., snow layer scale, in the snowpack models has been proposed in a phenomenological way. Here we used an upscaling method, namely, the homogenization of multiple-scale expansions, to derive theoretically the macroscopic equivalent modeling of heat and vapor transfer through a snow layer from the physics at the pore scale. The physical phenomena under consideration are steady state air flow, heat transfer by conduction and convection, water vapor transfer by diffusion and convection, and phase change (sublimation and deposition). We derived three different macroscopic models depending on the intensity of the air flow considered at the pore scale, i.e., on the order of magnitude of the pore Reynolds number and the Péclet numbers: (A) pure diffusion, (B) diffusion and moderate convection (Darcy's law), and (C) strong convection (nonlinear flow). The formulation of the models includes the exact expression of the macroscopic properties (effective thermal conductivity, effective vapor diffusion coefficient, and intrinsic permeability) and of the macroscopic source terms of heat and vapor arising from the phase change at the pore scale. Such definitions can be used to compute macroscopic snow properties from 3-D descriptions of snow microstructures. Finally, we illustrated the precision and the robustness of the proposed macroscopic models through 2-D numerical simulations.

Interfacial area transport of steam-water two-phase flow in a vertical annulus at elevated pressures

NASA Astrophysics Data System (ADS)

Ozar, Basar

Analysis of accident scenarios in nuclear reactors are done by using codes such as TRACE and RELAP5. Large oscillations in the core void fraction are observed in calculations of advanced passive light water reactors (ALWRs), especially during the low pressure long-term cooling phase. These oscillations are attributed to be numerical in nature and served to limit the accuracy as well as the credibility of the calculations. One of the root causes of these unphysical oscillations is determined to be flow regime transitions caused by the usage of static flow regime maps. The interfacial area transport equation was proposed earlier in order to address these issues. Previous research successfully developed the foundation of the interfacial area transport equation and the experimental techniques needed for the measurement of interfacial area, bubble diameters and velocities. In the past, an extensive database has been then generated for adiabatic air-water conditions in vertical upward and downward bubbly-churn turbulent flows in pipes. Using this database, mechanistic models for the creation (bubble breakup) and destruction (bubble coalescence) of interfacial area have been developed for the bubblyslug flow regime transition. However, none of these studies investigated the effect of phase change. To address this need, a heated annular test section was designed and constructed. The design relied on a three level scaling approach: geometric scaling; hydrodynamic scaling; thermal scaling. The test section consisted of a heated and unheated section in order to study the sub-cooled boiling and bulk condensation/flashing and evaporation phenomena, respectively. Steam-water two-phase flow tests were conducted under sub-cooled boiling conditions in the heated section and with sub-cooled/super-heated bulk liquid in the unheated section. The modeling of interfacial area transport equation with phase change effects was introduced and discussed. Constitutive relations, which took phase change effects into account, for interfacial area transport equation were proposed and implemented. Effects of these constitutive relations on the prediction capability of the transport equation were discussed.

Carrier-envelope phase effects for a dipolar molecule interacting with two-color pump-probe laser pulses

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

Cheng Taiwang; Brown, Alex

2004-12-01

The interaction of a two-level dipolar molecule with two laser pulses, where one laser's frequency is tuned to the energy level separation (pump laser) while the second laser's frequency is extremely small (probe laser), is investigated. A dipolar molecule is one with a nonzero difference between the permanent dipole moments of the molecular states. As shown previously [A. Brown, Phys. Rev. A 66, 053404 (2002)], the final population transfer between the two levels exhibits a dependence on the carrier-envelope phase of the probe laser. Based on the rotating-wave approximation (RWA), an effective Hamiltonian is derived to account for the basicmore » characteristics of the carrier-envelope phase dependence effect. By analysis of the effective Hamiltonian, scaling properties of the system are found with regard to field strengths, pulse durations, and frequencies. According to these scaling properties, the final-state population transfer can be controlled by varying the carrier-envelope phase of the probe laser field using lasers with weak field strengths (low intensities) and relatively long pulse durations. In order to examine the possible roles of background states, the investigation is extended to a three-level model. It is demonstrated that the carrier-envelope phase effect still persists in a well-defined manner even when neighboring energy levels are present. These results illustrate the potential of utilizing excitation in dipolar molecules as a means of measuring the carrier-envelope phase of a laser pulse or if one can manipulate the carrier envelope phase, as a method of controlling population transfer in dipolar molecules. The results also suggest that the carrier-envelope phases must be taken into account properly when performing calculations involving pump-probe excitation schemes with laser frequencies which differ widely in magnitude.« less

Meso-Scale Modeling of Spall in a Heterogeneous Two-Phase Material

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

Springer, Harry Keo

2008-07-11

The influence of the heterogeneous second-phase particle structure and applied loading conditions on the ductile spall response of a model two-phase material was investigated. Quantitative metallography, three-dimensional (3D) meso-scale simulations (MSS), and small-scale spall experiments provided the foundation for this study. Nodular ductile iron (NDI) was selected as the model two-phase material for this study because it contains a large and readily identifiable second- phase particle population. Second-phase particles serve as the primary void nucleation sites in NDI and are, therefore, central to its ductile spall response. A mathematical model was developed for the NDI second-phase volume fraction that accountedmore » for the non-uniform particle size and spacing distributions within the framework of a length-scale dependent Gaussian probability distribution function (PDF). This model was based on novel multiscale sampling measurements. A methodology was also developed for the computer generation of representative particle structures based on their mathematical description, enabling 3D MSS. MSS were used to investigate the effects of second-phase particle volume fraction and particle size, loading conditions, and physical domain size of simulation on the ductile spall response of a model two-phase material. MSS results reinforce existing model predictions, where the spall strength metric (SSM) logarithmically decreases with increasing particle volume fraction. While SSM predictions are nearly independent of applied load conditions at lower loading rates, which is consistent with previous studies, loading dependencies are observed at higher loading rates. There is also a logarithmic decrease in SSM for increasing (initial) void size, as well. A model was developed to account for the effects of loading rate, particle size, matrix sound-speed, and, in the NDI-specific case, the probabilistic particle volume fraction model. Small-scale spall experiments were designed and executed for the purpose of validating closely-coupled 3D MSS. While the spall strength is nearly independent of specimen thickness, the fragment morphology varies widely. Detailed MSS demonstrate that the interactions between the tensile release waves are altered by specimen thickness and that these interactions are primarily responsible for fragment formation. MSS also provided insights on the regional amplification of damage, which enables the development of predictive void evolution models.« less

Nature of Continuous Phase Transitions in Interacting Topological Insulators

DOE PAGES

Zeng, Tian-sheng; Zhu, Wei; Zhu, Jianxin; ...

2017-11-08

Here, we revisit the effects of the Hubbard repulsion on quantum spin Hall effects (QSHE) in two-dimensional quantum lattice models. We present both unbiased exact diagonalization and density-matrix renormalization group simulations with numerical evidence for a continuous quantum phase transition (CQPT) separating QSHE from the topologically trivial antiferromagnetic phase. Our numerical results suggest that the nature of CQPT exhibits distinct finite-size scaling behaviors, which may be consistent with either Ising or XY universality classes for different time-reversal symmetric QSHE systems.

Nature of Continuous Phase Transitions in Interacting Topological Insulators

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

Zeng, Tian-sheng; Zhu, Wei; Zhu, Jianxin

Here, we revisit the effects of the Hubbard repulsion on quantum spin Hall effects (QSHE) in two-dimensional quantum lattice models. We present both unbiased exact diagonalization and density-matrix renormalization group simulations with numerical evidence for a continuous quantum phase transition (CQPT) separating QSHE from the topologically trivial antiferromagnetic phase. Our numerical results suggest that the nature of CQPT exhibits distinct finite-size scaling behaviors, which may be consistent with either Ising or XY universality classes for different time-reversal symmetric QSHE systems.

Effect of microstructural parameters on the mechanical behavior of TiAlNb(Cr,Mo) alloys with γ+σ microstructure at ambient temperature

DOE PAGES

Kesler, Michael S.; Goyel, Sonalika; Ebrahimi, Fereshteh; ...

2016-11-15

The mechanical properties of novel alloys with two-phase γ-TiAl + σ-Nb 2Al microstructures were evaluated under compression at room temperature. Microstructures of varying scales were developed through solutionizing and aging heat treatments and the volume fraction of phases were varied with changes in composition. Ultra-fine, aged γ+σ microstructures were achieved for the alloys which affectively retained high volume fractions of the parent β-phase upon quenching from the solutionizing temperature. The yield strength and compressive strain to failure of these alloys show a strong dependence on the relative scale and volume fraction of phases. Surprisingly, the hard brittle σ-phase particles weremore » not found to control fracture in the refined microstructures.« less

An efficient implementation of 3D high-resolution imaging for large-scale seismic data with GPU/CPU heterogeneous parallel computing

NASA Astrophysics Data System (ADS)

Xu, Jincheng; Liu, Wei; Wang, Jin; Liu, Linong; Zhang, Jianfeng

2018-02-01

De-absorption pre-stack time migration (QPSTM) compensates for the absorption and dispersion of seismic waves by introducing an effective Q parameter, thereby making it an effective tool for 3D, high-resolution imaging of seismic data. Although the optimal aperture obtained via stationary-phase migration reduces the computational cost of 3D QPSTM and yields 3D stationary-phase QPSTM, the associated computational efficiency is still the main problem in the processing of 3D, high-resolution images for real large-scale seismic data. In the current paper, we proposed a division method for large-scale, 3D seismic data to optimize the performance of stationary-phase QPSTM on clusters of graphics processing units (GPU). Then, we designed an imaging point parallel strategy to achieve an optimal parallel computing performance. Afterward, we adopted an asynchronous double buffering scheme for multi-stream to perform the GPU/CPU parallel computing. Moreover, several key optimization strategies of computation and storage based on the compute unified device architecture (CUDA) were adopted to accelerate the 3D stationary-phase QPSTM algorithm. Compared with the initial GPU code, the implementation of the key optimization steps, including thread optimization, shared memory optimization, register optimization and special function units (SFU), greatly improved the efficiency. A numerical example employing real large-scale, 3D seismic data showed that our scheme is nearly 80 times faster than the CPU-QPSTM algorithm. Our GPU/CPU heterogeneous parallel computing framework significant reduces the computational cost and facilitates 3D high-resolution imaging for large-scale seismic data.

A numerical model of two-phase flow at the micro-scale using the volume-of-fluid method

NASA Astrophysics Data System (ADS)

Shams, Mosayeb; Raeini, Ali Q.; Blunt, Martin J.; Bijeljic, Branko

2018-03-01

This study presents a simple and robust numerical scheme to model two-phase flow in porous media where capillary forces dominate over viscous effects. The volume-of-fluid method is employed to capture the fluid-fluid interface whose dynamics is explicitly described based on a finite volume discretization of the Navier-Stokes equations. Interfacial forces are calculated directly on reconstructed interface elements such that the total curvature is preserved. The computed interfacial forces are explicitly added to the Navier-Stokes equations using a sharp formulation which effectively eliminates spurious currents. The stability and accuracy of the implemented scheme is validated on several two- and three-dimensional test cases, which indicate the capability of the method to model two-phase flow processes at the micro-scale. In particular we show how the co-current flow of two viscous fluids leads to greatly enhanced flow conductance for the wetting phase in corners of the pore space, compared to a case where the non-wetting phase is an inviscid gas.

Effect of length scale on mechanical properties of Al-Cu eutectic alloy

NASA Astrophysics Data System (ADS)

Tiwary, C. S.; Roy Mahapatra, D.; Chattopadhyay, K.

2012-10-01

This paper attempts a quantitative understanding of the effect of length scale on two phase eutectic structure. We first develop a model that considers both the elastic and plastic properties of the interface. Using Al-Al2Cu lamellar eutectic as model system, the parameters of the model were experimentally determined using indentation technique. The model is further validated using the results of bulk compression testing of the eutectics having different length scales.

Emerging single-phase state in small manganite nanodisks

DOE PAGES

Shao, Jian; Liu, Hao; Zhang, Kai; ...

2016-08-01

In complex oxides systems such as manganites, electronic phase separation (EPS), a consequence of strong electronic correlations, dictates the exotic electrical and magnetic properties of these materials. A fundamental yet unresolved issue is how EPS responds to spatial confinement; will EPS just scale with size of an object, or will the one of the phases be pinned? Understanding this behavior is critical for future oxides electronics and spintronics because scaling down of the system is unavoidable for these applications. In this work, we use La 0.325Pr 0.3Ca 0.375MnO 3 (LPCMO) single crystalline disks to study the effect of spatial confinementmore » on EPS. The EPS state featuring coexistence of ferromagnetic metallic and charge order insulating phases appears to be the low-temperature ground state in bulk, thin films, and large disks, a previously unidentified ground state (i.e., a single ferromagnetic phase state emerges in smaller disks). The critical size is between 500 nm and 800 nm, which is similar to the characteristic length scale of EPS in the LPCMO system. The ability to create a pure ferromagnetic phase in manganite nanodisks is highly desirable for spintronic applications.« less

Collective backscattering of gyrotron radiation by small-scale plasma density fluctuations in large helical device

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

Kharchev, Nikolay; Batanov, German; Petrov, Alexandr

2008-10-15

A version of the collective backscattering diagnostic using gyrotron radiation for small-scale turbulence is described. The diagnostic is used to measure small-scale (k{sub s}{approx_equal}34 cm{sup -1}) plasma density fluctuations in large helical device experiments on the electron cyclotron heating of plasma with the use of 200 kW 82.7 GHz heating gyrotron. A good signal to noise ratio during plasma production phase was obtained, while contamination of stray light increased during plasma build-up phase. The effect of the stray radiation was investigated. The available quasioptical system of the heating system was utilized for this purpose.

High temperature oxidation behavior of gamma-nickel+gamma'-nickel aluminum alloys and coatings modified with platinum and reactive elements

NASA Astrophysics Data System (ADS)

Mu, Nan

Materials for high-pressure turbine blades must be able to operate in the high-temperature gases (above 1000°C) emerging from the combustion chamber. Accordingly, the development of nickel-based superalloys has been constantly motivated by the need to have improved engine efficiency, reliability and service lifetime under the harsh conditions imposed by the turbine environment. However, the melting point of nickel (1455°C) provides a natural ceiling for the temperature capability of nickel-based superalloys. Thus, surface-engineered turbine components with modified diffusion coatings and overlay coatings are used. Theses coatings are capable of forming a compact and adherent oxide scale, which greatly impedes the further transport of reactants between the high-temperature gases and the underlying metal and thus reducing attack by the atmosphere. Typically, these coatings contain beta-NiAl as a principal constituent phase in order to have sufficient aluminum content to form an Al2O3 scale at elevated temperatures. The drawbacks to the currently-used beta-based coatings, such as phase instabilities, associated stresses induced by such phase instabilities, and extensive coating/substrate interdiffusion, are major motivations in this study to seek next-generation coatings. The high-temperature oxidation resistance of novel Pt+Hf-modified gamma-Ni+gamma'-Ni 3Al-based alloys and coatings were investigated in this study. Both early-stage and 4-days isothermal oxidation behavior of single-phase gamma-Ni and gamma'-Ni3Al alloys were assessed by examining the weight changes, oxide-scale structures, and elemental concentration profiles through the scales and subsurface alloy regions. It was found that Pt promotes Al 2O3 formation by suppressing the NiO growth on both gamma-Ni and gamma'-Ni3Al single-phase alloys. This effect increases with increasing Pt content. Moreover, Pt exhibits this effect even at lower temperatures (˜970°C) in the very early stage of oxidation. It was also inferred that Pt enhances the diffusive flux of aluminum from the substrate to the scale/alloy interface. Relatively low levels of hafnium addition to Pt-free gamma'-Ni 3Al increased the extent of external NiO formation due to non-protective HfO2 formation. Accordingly, this effect intensified with increasing Hf content from 0.2 to 0.5at.%. The synergistic effect of Pt and Hf co-addition was realized by examining Pt+Hf-modified gamma'-Ni3Al alloys. It was inferred that Pt decreases the chemical activity of Hf so that HfO2 formation could be suppressed with increasing Pt content. Thus, the early-stage Al2O3 formation facilitated by Pt additions and NiO development assisted by Hf additions are the competing scale growth processes that are influenced by the relative contents of Pt and Hf. Large interfacial voids were observed on the gamma'-Ni 3Al alloy after 4-days isothermal oxidation at 1150°C, which could be attributed to the Kirkendall effect. Platinum addition was also found to improve Al2O3-scale adhesion. Pt and Hf effects on two-phase gamma-Ni+gamma'-Ni3Al alloys of compositions Ni-20Al-20Pt-xHf (x ranges from 0 to 0.91) were examined by both thermal gravimetric analyses and cyclic oxidation tests. Scale microstructures were characterized by confocal photo-stimulated microspectroscopy (CPSM), in-lens SEM, and FIB-TEM. Hafnium additions up to about 0.48at.% markedly decreased the weight change of isothermally oxidized Pt-modified gamma+gamma' alloys by forming thinner oxide scales than that on the Hf-free Ni-20Al-20Pt base alloy. This could be attributed to an Al2O3 grain boundary blocking effect imparted by the segregated Hf. However, an over-doped alloy with 0.91at.% Hf exhibited detrimental effect by forming internal HfO 2. It was observed that Hf additions altered the Al2O3 scale microstructure. The most remarkable difference was that the columnar width of the Al2O3 scale grains formed on Ni-20Al-20Pt was much larger than it was on Ni-20Al-20Pt-0.48Hf. Even so, the Hf-doped alloys exhibited much slower scaling kinetics with a correspondingly thinner scale. This behavior could be ascribed to the Hf blocking diffusing paths as it segregated into Al2O3 grain boundaries. Therefore, the Hf-doped scale grew at a lower rate even though it contained more grain boundaries. Accompanied with this scale microstructure modification, Hf additions led to the following two additional effects: (1) Hf delayed the theta→alpha structural transformation of Al2O3; and (2) compressive residual stress in the scale formed on Hf-doped alloys was lower than that on the Hf-free Ni-20Al-20Pt alloy. Guided by the results from the bulk-alloy studies, a feasible method to deposit Pt+Hf-modified gamma+gamma' coatings having overall compositions closely approaching Ni-Al15-20-Pt15-20-Hf was subsequently developed. A key improvement of the application of Pt+Hf-modified gamma-Ni+gamma'-Ni 3Al coatings is the relief of TCP phases generated from coating/substrate interdiffusion. This could be simply attributed to the inherited phase compatibility between gamma+gamma' coatings with Ni-based superalloys. Another important advantage of gamma+gamma' coatings is the exclusion of phase transformations during thermal cycling. The Pt+Hf-modified gamma-Ni+gamma'-Ni3Al coating compositions had a strong dependence on the temperature and time in both pack cementation and post-heat-treatment processes. Meanwhile, coating performance was apparently more sensitive to the Hf content than what was observed with the alloys. Coating performance was also considerable affected by the surface finish and the composition of the superalloy substrate.

Pore scale Assessment of Heat and Mass transfer in Porous Medium Using Phase Field Method with Application to Soil Borehole Thermal Storage (SBTES) Systems

NASA Astrophysics Data System (ADS)

Moradi, A.

2015-12-01

To properly model soil thermal performance in unsaturated porous media, for applications such as SBTES systems, knowledge of both soil hydraulic and thermal properties and how they change in space and time is needed. Knowledge obtained from pore scale to macroscopic scale studies can help us to better understand these systems and contribute to the state of knowledge which can then be translated to engineering applications in the field (i.e. implementation of SBTES systems at the field scale). One important thermal property that varies with soil water content, effective thermal conductivity, is oftentimes included in numerical models through the use of empirical relationships and simplified mathematical formulations developed based on experimental data obtained at either small laboratory or field scales. These models assume that there is local thermodynamic equilibrium between the air and water phases for a representative elementary volume. However, this assumption may not always be valid at the pore scale, thus questioning the validity of current modeling approaches. The purpose of this work is to evaluate the validity of the local thermodynamic equilibrium assumption as related to the effective thermal conductivity at pore scale. A numerical model based on the coupled Cahn-Hilliard and heat transfer equation was developed to solve for liquid flow and heat transfer through variably saturated porous media. In this model, the evolution of phases and the interfaces between phases are related to a functional form of the total free energy of the system. A unique solution for the system is obtained by solving the Navier-Stokes equation through free energy minimization. Preliminary results demonstrate that there is a correlation between soil temperature / degree of saturation and equivalent thermal conductivity / heat flux. Results also confirm the correlation between pressure differential magnitude and equilibrium time for multiphase flow to reach steady state conditions. Based on these results, the equivalent time for steady-state heat transfer is much larger than the equivalent time for steady-state multiphase flow for a given pressure differential. Moreover, the wetting phase flow and consequently heat transfer appear to be sensitive to contact angle and porosity of the domain.

Phase structure of NJL model with weak renormalization group

NASA Astrophysics Data System (ADS)

Aoki, Ken-Ichi; Kumamoto, Shin-Ichiro; Yamada, Masatoshi

2018-06-01

We analyze the chiral phase structure of the Nambu-Jona-Lasinio model at finite temperature and density by using the functional renormalization group (FRG). The renormalization group (RG) equation for the fermionic effective potential V (σ ; t) is given as a partial differential equation, where σ : = ψ bar ψ and t is a dimensionless RG scale. When the dynamical chiral symmetry breaking (DχSB) occurs at a certain scale tc, V (σ ; t) has singularities originated from the phase transitions, and then one cannot follow RG flows after tc. In this study, we introduce the weak solution method to the RG equation in order to follow the RG flows after the DχSB and to evaluate the dynamical mass and the chiral condensate in low energy scales. It is shown that the weak solution of the RG equation correctly captures vacuum structures and critical phenomena within the pure fermionic system. We show the chiral phase diagram on temperature, chemical potential and the four-Fermi coupling constant.

Precipitation and Phase Transformations in 2101 Lean Duplex Stainless Steel During Isothermal Aging

NASA Astrophysics Data System (ADS)

Maetz, Jean-Yves; Cazottes, Sophie; Verdu, Catherine; Kleber, Xavier

2016-01-01

The effect of isothermal aging at 963 K (690 °C) on the microstructure of a 2101 lean duplex stainless steel, with the composition Fe-21.5Cr-5Mn-1.6Ni-0.22N-0.3Mo, was investigated using a multi-technique and multi-scale approach. The kinetics of phase transformation and precipitation was followed from a few minutes to thousands of hours using thermoelectric power measurements; based on these results, certain aging states were selected for electron microscopy characterization. Scanning electron microscopy, electron back-scattered diffraction, and transmission electron microscopy were used to quantitatively describe the microstructural evolution through crystallographic analysis, chemical analysis, and volume fraction measurements from the macroscopic scale down to the nanometric scale. During aging, the precipitation of M23C6 carbides, Cr2N nitrides, and σ phase as well as the transformation of ferrite into austenite and austenite into martensite was observed. These complex microstructural changes are controlled by Cr volume diffusion. The precipitation and phase transformation mechanisms are described.

Uncovering the nonadiabatic response of geosynchronous electrons to geomagnetic disturbance

USGS Publications Warehouse

Gannon, Jennifer; Elkington, Scot R.; Onsager, Terrance G.

2012-01-01

We describe an energy spectrum method for scaling electron integral flux, which is measured at a constant energy, to phase space density at a constant value of the first adiabatic invariant which removes much of the variation due to reversible adiabatic effects. Applying this method to nearly a solar cycle (1995 - 2006) of geosynchronous electron integral flux (E>2.0MeV) from the GOES satellites, we see that much of the diurnal variation in electron phase space density at constant energy can be removed by the transformation to phase space density at constant μ (4000 MeV/G). This allows us a clearer picture of underlying non-adiabatic electron population changes due to geomagnetic activity. Using scaled phase space density, we calculate the percentage of geomagnetic storms resulting in an increase, decrease or no change in geosynchronous electrons as 38%, 7%, and 55%, respectively. We also show examples of changes in the electron population that may be different than the unscaled fluxes alone suggest. These examples include sudden electron enhancements during storms which appear during the peak of negative Dst for μ-scaled phase space density, contrary to the slow increase seen during the recovery phase for unscaled phase space density for the same event.

Evolution of the electrical resistivity anisotropy during saline tracer tests: insights from geoelectrical milli-fluidic experiments

NASA Astrophysics Data System (ADS)

Jougnot, D.; Jimenez-Martinez, J.; Legendre, R.; Le Borgne, T.; Meheust, Y.; Linde, N.

2017-12-01

The use of time-lapse electrical resistivity tomography has been largely developed in environmental studies to remotely monitor water saturation and contaminant plumes migration. However, subsurface heterogeneities, and corresponding preferential transport paths, yield a potentially large anisotropy in the electrical properties of the subsurface. In order to study this effect, we have used a newly developed geoelectrical milli-fluidic experimental set-up with a flow cell that contains a 2D porous medium consisting of a single layer of cylindrical solid grains. We performed saline tracer tests under full and partial water saturations in that cell by jointly injecting air and aqueous solutions with different salinities. The flow cell is equipped with four electrodes to measure the bulk electrical resistivity at the cell's scale. The spatial distribution of the water/air phases and the saline solute concentration field in the water phase are captured simultaneously with a high-resolution camera by combining a fluorescent tracer with the saline solute. These data are used to compute the longitudinal and transverse effective electrical resistivity numerically from the measured spatial distributions of the fluid phases and the salinity field. This approach is validated as the computed longitudinal effective resistivities are in good agreement with the laboratory measurements. The anisotropy in electrical resistivity is then inferred from the computed longitudinal and transverse effective resistivities. We find that the spatial distribution of saline tracer, and potentially air phase, drive temporal changes in the effective resistivity through preferential paths or barriers for electrical current at the pore scale. The resulting heterogeneities in the solute concentrations lead to strong anisotropy of the effective bulk electrical resistivity, especially for partially saturated conditions. Therefore, considering the electrical resistivity as a tensor could improve our understanding of transport properties from field-scale time-lapse ERT.

The effect of pore-scale geometry and wettability on two-phase relative permeabilities within elementary cells

NASA Astrophysics Data System (ADS)

Bianchi Janetti, Emanuela; Riva, Monica; Guadagnini, Alberto

2017-04-01

We study the relative role of the complex pore space geometry and wettability of the solid matrix on the quantification of relative permeabilities characterizing steady state immiscible two-phase flow in porous media. We do so by considering elementary cells, which are typically employed in upscaling frameworks based on, e.g., homogenization or volume averaging. In this context one typically relies on the solution of pore-scale physics at a scale which is much smaller than that of an investigated porous system. Pressure-driven two-phase flow following simultaneous co-current injection of water and oil is numerically solved for a suite of regular and stochastically generated two-dimensional explicit elementary cells with fixed porosity and sharing main topological/morphological features. We show that relative permeabilities of the randomly generated elementary cells are significantly influenced by the formation of preferential percolation paths (principal pathways), giving rise to a strongly nonuniform distribution of fluid fluxes. These pathways are a result of the spatially variable resistance that the random pore structures exert on the fluid. The overall effect on relative permeabilities of the diverse organization of principal pathways, as driven by a given random realization at the scale of the unit cell, is significantly larger than that of the wettability of the host rock. In contrast to what can be observed for the random cells analyzed, relative permeabilities of regular cells display a clear trend with contact angle at the investigated scale. Our findings suggest the need to perform systematic upscaling studies in a stochastic context, to propagate the effects of uncertain pore space geometries to a probabilistic description of relative permeability curves at the continuum scale.

Efficient implicit LES method for the simulation of turbulent cavitating flows

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

Egerer, Christian P., E-mail: christian.egerer@aer.mw.tum.de; Schmidt, Steffen J.; Hickel, Stefan

2016-07-01

We present a numerical method for efficient large-eddy simulation of compressible liquid flows with cavitation based on an implicit subgrid-scale model. Phase change and subgrid-scale interface structures are modeled by a homogeneous mixture model that assumes local thermodynamic equilibrium. Unlike previous approaches, emphasis is placed on operating on a small stencil (at most four cells). The truncation error of the discretization is designed to function as a physically consistent subgrid-scale model for turbulence. We formulate a sensor functional that detects shock waves or pseudo-phase boundaries within the homogeneous mixture model for localizing numerical dissipation. In smooth regions of the flowmore » field, a formally non-dissipative central discretization scheme is used in combination with a regularization term to model the effect of unresolved subgrid scales. The new method is validated by computing standard single- and two-phase test-cases. Comparison of results for a turbulent cavitating mixing layer obtained with the new method demonstrates its suitability for the target applications.« less

Spatial and temporal variations of evapotranspiration, groundwater and precipitation in Amazonia

NASA Astrophysics Data System (ADS)

Niu, J.; Riley, W. J.; Shen, C.; Melack, J. M.; Qiu, H.

2017-12-01

We used wavelet coherence analysis to investigate the effects of precipitation (P) and groundwater dynamics (total water storage anomaly, TWSA) on evapotranspiration (ET) at kilometer, sub-basin, and whole basin scales in the Amazon basin. The Amazon-scale averaged ET, P, and TWSA have about the same annual periodicity. The phase lag between ET and P (ΦET-P) is 1 to 3 months, and between ET and TWSA (ΦET-TWSA) is 3 to 7 months. The phase patterns have a south-north divide due to significant variation in climatic conditions. The correlation between ΦET-P and ΦET-TWSA is affected by the aridity index (the ratio between potential ET (PET) and P, PET / P), of each sub-basin, as determined using the Budyko framework at the sub-basin level. The spatial structure of ΦET-P is negatively correlated with the spatial structure of annual ET. At Amazon-scale during a drought year (e.g., 2010), both phases decreased, while in the subsequent years, ΦET-TWSA increased, indicating strong groundwater effects on ET immediately following dry years Amazon-wide.

Acute and long-term treatment of late-life major depressive disorder: duloxetine versus placebo.

PubMed

Robinson, Michael; Oakes, Tina Myers; Raskin, Joel; Liu, Peng; Shoemaker, Scarlett; Nelson, J Craig

2014-01-01

To compare the efficacy of duloxetine with placebo on depression in elderly patients with major depressive disorder. Multicenter, 24-week (12-week short-term and 12-week continuation), randomized, placebo-controlled, double-blind trial. United States, France, Mexico, Puerto Rico. Age 65 years or more with major depressive disorder diagnosis (one or more previous episode); Mini-Mental State Examination score ≥20; Montgomery-Asberg Depression Rating Scale total score ≥20. Duloxetine 60 or 120 mg/day or placebo; placebo rescue possible. Primary-Maier subscale of the 17-item Hamilton Depression Rating Scale (HAMD-17) at week 12. Secondary-Geriatric Depression Scale, HAMD-17 total score, cognitive measures, Brief Pain Inventory (BPI), Numeric Rating Scales (NRS) for pain, Clinical Global Impression-Severity scale, Patient Global Impression of Improvement in acute phase and acute plus continuation phase of treatment. Compared with placebo, duloxetine did not show significantly greater improvement from baseline on Maier subscale at 12 weeks, but did show significantly greater improvement at weeks 4, 8, 16, and 20. Similar patterns for Geriatric Depression Scale and Clinical Global Impression-Severity scale emerged, with significance also seen at week 24. There was a significant treatment effect for all BPI items and 4 of 6 NRS pain measures in the acute phase, most BPI items and half of the NRS measures in the continuation phase. More duloxetine-treated patients completed the study (63% versus 55%). A significantly higher percentage of duloxetine-treated patients versus placebo discontinued due to adverse event (15.3% versus 5.8%). Although the antidepressant efficacy of duloxetine was not confirmed by the primary outcome, several secondary measures at multiple time points suggested efficacy. Duloxetine had significant and meaningful beneficial effects on pain. Copyright © 2014 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.

Sound production due to large-scale coherent structures

NASA Technical Reports Server (NTRS)

Gatski, T. B.

1979-01-01

The acoustic pressure fluctuations due to large-scale finite amplitude disturbances in a free turbulent shear flow are calculated. The flow is decomposed into three component scales; the mean motion, the large-scale wave-like disturbance, and the small-scale random turbulence. The effect of the large-scale structure on the flow is isolated by applying both a spatial and phase average on the governing differential equations and by initially taking the small-scale turbulence to be in energetic equilibrium with the mean flow. The subsequent temporal evolution of the flow is computed from global energetic rate equations for the different component scales. Lighthill's theory is then applied to the region with the flowfield as the source and an observer located outside the flowfield in a region of uniform velocity. Since the time history of all flow variables is known, a minimum of simplifying assumptions for the Lighthill stress tensor is required, including no far-field approximations. A phase average is used to isolate the pressure fluctuations due to the large-scale structure, and also to isolate the dynamic process responsible. Variation of mean square pressure with distance from the source is computed to determine the acoustic far-field location and decay rate, and, in addition, spectra at various acoustic field locations are computed and analyzed. Also included are the effects of varying the growth and decay of the large-scale disturbance on the sound produced.

Local and global synchronization transitions induced by time delays in small-world neuronal networks with chemical synapses.

PubMed

Yu, Haitao; Wang, Jiang; Du, Jiwei; Deng, Bin; Wei, Xile

2015-02-01

Effects of time delay on the local and global synchronization in small-world neuronal networks with chemical synapses are investigated in this paper. Numerical results show that, for both excitatory and inhibitory coupling types, the information transmission delay can always induce synchronization transitions of spiking neurons in small-world networks. In particular, regions of in-phase and out-of-phase synchronization of connected neurons emerge intermittently as the synaptic delay increases. For excitatory coupling, all transitions to spiking synchronization occur approximately at integer multiples of the firing period of individual neurons; while for inhibitory coupling, these transitions appear at the odd multiples of the half of the firing period of neurons. More importantly, the local synchronization transition is more profound than the global synchronization transition, depending on the type of coupling synapse. For excitatory synapses, the local in-phase synchronization observed for some values of the delay also occur at a global scale; while for inhibitory ones, this synchronization, observed at the local scale, disappears at a global scale. Furthermore, the small-world structure can also affect the phase synchronization of neuronal networks. It is demonstrated that increasing the rewiring probability can always improve the global synchronization of neuronal activity, but has little effect on the local synchronization of neighboring neurons.

Pore-Scale Characterization of Biogeochemical Controls on Iron and Uranium Speciation under Flow Conditions

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

Pearce, Carolyn I.; Wilkins, Michael J.; Zhang, Changyong

2012-09-17

Etched silicon microfluidic pore network models (micromodels) with controlled chemical and redox gradients, mineralogy, and microbiology under continuous flow conditions are used for the incremental development of complex microenvironments that simulate subsurface conditions. We demonstrate the colonization of micromodel pore spaces by an anaerobic Fe(III)-reducing bacterial species (Geobacter sulfurreducens) and the enzymatic reduction of a bioavailable Fe(III) phase within this environment. Using both X-ray Microprobe and X-ray Absorption Spectroscopy, we investigate the combined effects of the precipitated Fe(III) phases and the microbial population on uranium biogeochemistry under flow conditions. Precipitated Fe(III) phases within the micromodel were most effectively reduced inmore » the presence of an electron shuttle (AQDS), and Fe(II) ions adsorbed onto the precipitated mineral surface without inducing any structural change. In the absence of Fe(III), U(VI) was effectively reduced by the microbial population to insoluble U(IV), which was precipitated in discrete regions associated with biomass. In the presence of Fe(III) phases, however, both U(IV) and U(VI) could be detected associated with biomass, suggesting re-oxidation of U(IV) by localized Fe(III) phases. These results demonstrate the importance of the spatial localization of biomass and redox active metals, and illustrate the key effects of pore-scale processes on contaminant fate and reactive transport.« less

Modeling of Bulk Evaporation and Condensation

NASA Technical Reports Server (NTRS)

Anghaie, S.; Ding, Z.

1996-01-01

This report describes the modeling and mathematical formulation of the bulk evaporation and condensation involved in liquid-vapor phase change processes. An internal energy formulation, for these phase change processes that occur under the constraint of constant volume, was studied. Compared to the enthalpy formulation, the internal energy formulation has a more concise and compact form. The velocity and time scales of the interface movement were obtained through scaling analysis and verified by performing detailed numerical experiments. The convection effect induced by the density change was analyzed and found to be negligible compared to the conduction effect. Two iterative methods for updating the value of the vapor phase fraction, the energy based (E-based) and temperature based (T-based) methods, were investigated. Numerical experiments revealed that for the evaporation and condensation problems the E-based method is superior to the T-based method in terms of computational efficiency. The internal energy formulation and the E-based method were used to compute the bulk evaporation and condensation processes under different conditions. The evolution of the phase change processes was investigated. This work provided a basis for the modeling of thermal performance of multi-phase nuclear fuel elements under variable gravity conditions, in which the buoyancy convection due to gravity effects and internal heating are involved.

Improved Separations of Proteins and Sugar Derivatives Using the Small-Scale Cross-Axis Coil Planet Centrifuge with Locular Multilayer Coiled Columns.

PubMed

Shinomiya, Kazufusa; Umezawa, Motoki; Seki, Manami; Nitta, Jun; Zaima, Kazumasa; Harikai, Naoki; Ito, Yoichiro

2016-12-01

Countercurrent chromatography (CCC) is liquid-liquid partition chromatography without using a solid support matrix. This technique requires further improvement of partition efficiency and shortening theseparation time. The locular multilayer coils modified with and without mixer glass beads were developed for the separation of proteins and 4-methylumbelliferyl (MU) sugar derivatives using the small-scale cross-axis coil planet centrifuge. Proteins were well separated from each other and the separation was improved at a low flow rate of the mobile phase. On the other hand, 4-MU sugar derivatives were sufficiently resolved with short separation time at a highflow rate of the mobile phase under satisfactory stationary phase retention. Effective separations were achieved using the locular multilayer coil for proteins with aqueous-aqueous polymer phase systems and for 4-MU sugar derivatives with organic-aqueous two-phase solvent systems by inserting a glass bead into each locule.

Metaproteomics reveals major microbial players and their biodegradation functions in a large-scale aerobic composting plant

PubMed Central

Liu, Dongming; Li, Mingxiao; Xi, Beidou; Zhao, Yue; Wei, Zimin; Song, Caihong; Zhu, Chaowei

2015-01-01

Composting is an appropriate management alternative for municipal solid waste; however, our knowledge about the microbial regulation of this process is still scare. We employed metaproteomics to elucidate the main biodegradation pathways in municipal solid waste composting system across the main phases in a large-scale composting plant. The investigation of microbial succession revealed that Bacillales, Actinobacteria and Saccharomyces increased significantly with respect to abundance in composting process. The key microbiologic population for cellulose degradation in different composting stages was different. Fungi were found to be the main producers of cellulase in earlier phase. However, the cellulolytic fungal communities were gradually replaced by a purely bacterial one in active phase, which did not support the concept that the thermophilic fungi are active through the thermophilic phase. The effective decomposition of cellulose required the synergy between bacteria and fungi in the curing phase. PMID:25989417

Cooling of solar flares plasmas. 1: Theoretical considerations

NASA Technical Reports Server (NTRS)

Cargill, Peter J.; Mariska, John T.; Antiochos, Spiro K.

1995-01-01

Theoretical models of the cooling of flare plasma are reexamined. By assuming that the cooling occurs in two separate phase where conduction and radiation, respectively, dominate, a simple analytic formula for the cooling time of a flare plasma is derived. Unlike earlier order-of-magnitude scalings, this result accounts for the effect of the evolution of the loop plasma parameters on the cooling time. When the conductive cooling leads to an 'evaporation' of chromospheric material, the cooling time scales L(exp 5/6)/p(exp 1/6), where the coronal phase (defined as the time maximum temperature). When the conductive cooling is static, the cooling time scales as L(exp 3/4)n(exp 1/4). In deriving these results, use was made of an important scaling law (T proportional to n(exp 2)) during the radiative cooling phase that was forst noted in one-dimensional hydrodynamic numerical simulations (Serio et al. 1991; Jakimiec et al. 1992). Our own simulations show that this result is restricted to approximately the radiative loss function of Rosner, Tucker, & Vaiana (1978). for different radiative loss functions, other scaling result, with T and n scaling almost linearly when the radiative loss falls off as T(exp -2). It is shown that these scaling laws are part of a class of analytic solutions developed by Antiocos (1980).

FLARE (Facility for Laboratory Reconnection Experiments): A Major Next-Step for Laboratory Studies of Magnetic Reconnection

NASA Astrophysics Data System (ADS)

Ji, H.; Bhattacharjee, A.; Prager, S.; Daughton, W. S.; Bale, S. D.; Carter, T. A.; Crocker, N.; Drake, J. F.; Egedal, J.; Sarff, J.; Wallace, J.; Belova, E.; Ellis, R.; Fox, W. R., II; Heitzenroeder, P.; Kalish, M.; Jara-Almonte, J.; Myers, C. E.; Que, W.; Ren, Y.; Titus, P.; Yamada, M.; Yoo, J.

2014-12-01

A new intermediate-scale plasma experiment, called the Facility for Laboratory Reconnection Experiments or FLARE, is under construction at Princeton as a joint project by five universities and two national labs to study magnetic reconnection in regimes directly relevant to space, solar and astrophysical plasmas. The currently existing small-scale experiments have been focusing on the single X-line reconnection process in plasmas either with small effective sizes or at low Lundquist numbers, both of which are typically very large in natural plasmas. These new regimes involve multiple X-lines as guided by a reconnection "phase diagram", in which different coupling mechanisms from the global system scale to the local dissipation scale are classified into different reconnection phases [H. Ji & W. Daughton, Phys. Plasmas 18, 111207 (2011)]. The design of the FLARE device is based on the existing Magnetic Reconnection Experiment (MRX) at Princeton (http://mrx.pppl.gov) and is to provide experimental access to the new phases involving multiple X-lines at large effective sizes and high Lundquist numbers, directly relevant to space and solar plasmas. The motivating major physics questions, the construction status, and the planned collaborative research especially with space and solar research communities will be discussed.

FLARE (Facility for Laboratory Reconnection Experiments): A Major Next-Step for Laboratory Studies of Magnetic Reconnection

NASA Astrophysics Data System (ADS)

Ji, Hantao; Bhattacharjee, A.; Prager, S.; Daughton, W.; Bale, Stuart D.; Carter, T.; Crocker, N.; Drake, J.; Egedal, J.; Sarff, J.; Fox, W.; Jara-Almonte, J.; Myers, C.; Ren, Y.; Yamada, M.; Yoo, J.

2015-04-01

A new intermediate-scale plasma experiment, called the Facility for Laboratory Reconnection Experiments or FLARE (flare.pppl.gov), is under construction at Princeton as a joint project by five universities and two national labs to study magnetic reconnection in regimes directly relevant to heliophysical and astrophysical plasmas. The currently existing small-scale experiments have been focusing on the single X-line reconnection process in plasmas either with small effective sizes or at low Lundquist numbers, both of which are typically very large in natural plasmas. These new regimes involve multiple X-lines as guided by a reconnection "phase diagram", in which different coupling mechanisms from the global system scale to the local dissipation scale are classified into different reconnection phases [H. Ji & W. Daughton, Phys. Plasmas 18, 111207 (2011)]. The design of the FLARE device is based on the existing Magnetic Reconnection Experiment (MRX) (mrx.pppl.gov) and is to provide experimental access to the new phases involving multiple X-lines at large effective sizes and high Lundquist numbers, directly relevant to magnetospheric, solar wind, and solar coronal plasmas. After a brief summary of recent laboratory results on the topic of magnetic reconnection, the motivating major physics questions, the construction status, and the planned collaborative research especially with heliophysics communities will be discussed.

Statistical mechanics of soft-boson phase transitions

NASA Technical Reports Server (NTRS)

Gupta, Arun K.; Hill, Christopher T.; Holman, Richard; Kolb, Edward W.

1991-01-01

The existence of structure on large (100 Mpc) scales, and limits to anisotropies in the cosmic microwave background radiation (CMBR), have imperiled models of structure formation based solely upon the standard cold dark matter scenario. Novel scenarios, which may be compatible with large scale structure and small CMBR anisotropies, invoke nonlinear fluctuations in the density appearing after recombination, accomplished via the use of late time phase transitions involving ultralow mass scalar bosons. Herein, the statistical mechanics are studied of such phase transitions in several models involving naturally ultralow mass pseudo-Nambu-Goldstone bosons (pNGB's). These models can exhibit several interesting effects at high temperature, which is believed to be the most general possibilities for pNGB's.

Accelerated long-term assessment of thermal and chemical stability of bio-based phase change materials

USDA-ARS?s Scientific Manuscript database

Thermal energy storage (TES) systems incorporated with phase change materials (PCMs) have potential applications to control energy use by building envelopes. However, it is essential to evaluate long term performance of the PCMs and cost effectiveness prior to full scale implementation. For this rea...

Scaling and modeling of turbulent suspension flows

NASA Technical Reports Server (NTRS)

Chen, C. P.

1989-01-01

Scaling factors determining various aspects of particle-fluid interactions and the development of physical models to predict gas-solid turbulent suspension flow fields are discussed based on two-fluid, continua formulation. The modes of particle-fluid interactions are discussed based on the length and time scale ratio, which depends on the properties of the particles and the characteristics of the flow turbulence. For particle size smaller than or comparable with the Kolmogorov length scale and concentration low enough for neglecting direct particle-particle interaction, scaling rules can be established in various parameter ranges. The various particle-fluid interactions give rise to additional mechanisms which affect the fluid mechanics of the conveying gas phase. These extra mechanisms are incorporated into a turbulence modeling method based on the scaling rules. A multiple-scale two-phase turbulence model is developed, which gives reasonable predictions for dilute suspension flow. Much work still needs to be done to account for the poly-dispersed effects and the extension to dense suspension flows.

Effects of massage therapy and presence of attendant on pain, anxiety and satisfaction during labor.

PubMed

Mortazavi, Seyedeh Hamideh; Khaki, Siavash; Moradi, Rayhaneh; Heidari, Kazem; Vasegh Rahimparvar, Seyedeh Fatemeh

2012-07-01

To investigate the effects of massage and presenting an attendant on pain, anxiety and satisfaction during labor to clarify some aspects of using an alternative complementary strategy. 120 primiparous women with term pregnancy were divided into massage, attendant and control groups randomly. Massage group received firm and rhythmic massage during labor in three phases. After 30 min massage at each stage, pain, anxiety and satisfaction levels were evaluated. Self-reported present pain intensity scale was used to measure the labor pain. Anxiety and satisfaction were measured with the standard visual analog scale. Massage group had lower pain state in second and third phases (p < 0.05) in comparison with attendant group but reversely, the level of anxiety was lower in attendant group in second and third phases (p < 0.05) and satisfaction was higher in massage group in all four phases (p < 0.001). The massage group had lower pain and anxiety state in three phases in comparison with control group (p < 0.05). Data analysis of satisfaction level showed higher values in four phases in massage group compared with control (p < 0.001) and comparison of attendant and control groups showed higher satisfaction in attendant group in phases 2, 3 and 4 as well (p < 0.001). Duration of active phase was lower in massage group (p < 0.001). Findings suggest that massage is an effective alternative intervention, decreasing pain and anxiety during labor and increasing the level of satisfaction. Also, the supportive role of presenting an attendant can positively influence the level of anxiety and satisfaction.

Theoretical prediction and impact of fundamental electric dipole moments

DOE PAGES

Ellis, Sebastian A. R.; Kane, Gordon L.

2016-01-13

The predicted Standard Model (SM) electric dipole moments (EDMs) of electrons and quarks are tiny, providing an important window to observe new physics. Theories beyond the SM typically allow relatively large EDMs. The EDMs depend on the relative phases of terms in the effective Lagrangian of the extended theory, which are generally unknown. Underlying theories, such as string/M-theories compactified to four dimensions, could predict the phases and thus EDMs in the resulting supersymmetric (SUSY) theory. Earlier one of us, with collaborators, made such a prediction and found, unexpectedly, that the phases were predicted to be zero at tree level inmore » the theory at the unification or string scale ~O(10 16 GeV). Electroweak (EW) scale EDMs still arise via running from the high scale, and depend only on the SM Yukawa couplings that also give the CKM phase. Here we extend the earlier work by studying the dependence of the low scale EDMs on the constrained but not fully known fundamental Yukawa couplings. The dominant contribution is from two loop diagrams and is not sensitive to the choice of Yukawa texture. The electron EDM should not be found to be larger than about 5 × 10 –30e cm, and the neutron EDM should not be larger than about 5 × 10 –29e cm. These values are quite a bit smaller than the reported predictions from Split SUSY and typical effective theories, but much larger than the Standard Model prediction. Also, since models with random phases typically give much larger EDMs, it is a significant testable prediction of compactified M-theory that the EDMs should not be above these upper limits. The actual EDMs can be below the limits, so once they are measured they could provide new insight into the fundamental Yukawa couplings of leptons and quarks. As a result, we comment also on the role of strong CP violation. EDMs probe fundamental physics near the Planck scale.« less

Theoretical prediction and impact of fundamental electric dipole moments

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

Ellis, Sebastian A. R.; Kane, Gordon L.

The predicted Standard Model (SM) electric dipole moments (EDMs) of electrons and quarks are tiny, providing an important window to observe new physics. Theories beyond the SM typically allow relatively large EDMs. The EDMs depend on the relative phases of terms in the effective Lagrangian of the extended theory, which are generally unknown. Underlying theories, such as string/M-theories compactified to four dimensions, could predict the phases and thus EDMs in the resulting supersymmetric (SUSY) theory. Earlier one of us, with collaborators, made such a prediction and found, unexpectedly, that the phases were predicted to be zero at tree level inmore » the theory at the unification or string scale ~O(10 16 GeV). Electroweak (EW) scale EDMs still arise via running from the high scale, and depend only on the SM Yukawa couplings that also give the CKM phase. Here we extend the earlier work by studying the dependence of the low scale EDMs on the constrained but not fully known fundamental Yukawa couplings. The dominant contribution is from two loop diagrams and is not sensitive to the choice of Yukawa texture. The electron EDM should not be found to be larger than about 5 × 10 –30e cm, and the neutron EDM should not be larger than about 5 × 10 –29e cm. These values are quite a bit smaller than the reported predictions from Split SUSY and typical effective theories, but much larger than the Standard Model prediction. Also, since models with random phases typically give much larger EDMs, it is a significant testable prediction of compactified M-theory that the EDMs should not be above these upper limits. The actual EDMs can be below the limits, so once they are measured they could provide new insight into the fundamental Yukawa couplings of leptons and quarks. As a result, we comment also on the role of strong CP violation. EDMs probe fundamental physics near the Planck scale.« less

Spontaneous helix formation in non-chiral bent-core liquid crystals with fast linear electro-optic effect

PubMed Central

Sreenilayam, Sithara P.; Panarin, Yuri P.; Vij, Jagdish K.; Panov, Vitaly P.; Lehmann, Anne; Poppe, Marco; Prehm, Marko; Tschierske, Carsten

2016-01-01

Liquid crystals (LCs) represent one of the foundations of modern communication and photonic technologies. Present display technologies are based mainly on nematic LCs, which suffer from limited response time for use in active colour sequential displays and limited image grey scale. Herein we report the first observation of a spontaneously formed helix in a polar tilted smectic LC phase (SmC phase) of achiral bent-core (BC) molecules with the axis of helix lying parallel to the layer normal and a pitch much shorter than the optical wavelength. This new phase shows fast (∼30 μs) grey-scale switching due to the deformation of the helix by the electric field. Even more importantly, defect-free alignment is easily achieved for the first time for a BC mesogen, thus providing potential use in large-scale devices with fast linear and thresholdless electro-optical response. PMID:27156514

Understanding dislocation mechanics at the mesoscale using phase field dislocation dynamics

PubMed Central

Hunter, A.

2016-01-01

In this paper, we discuss the formulation, recent developments and findings obtained from a mesoscale mechanics technique called phase field dislocation dynamics (PFDD). We begin by presenting recent advancements made in modelling face-centred cubic materials, such as integration with atomic-scale simulations to account for partial dislocations. We discuss calculations that help in understanding grain size effects on transitions from full to partial dislocation-mediated slip behaviour and deformation twinning. Finally, we present recent extensions of the PFDD framework to alternative crystal structures, such as body-centred cubic metals, and two-phase materials, including free surfaces, voids and bi-metallic crystals. With several examples we demonstrate that the PFDD model is a powerful and versatile method that can bridge the length and time scales between atomistic and continuum-scale methods, providing a much needed understanding of deformation mechanisms in the mesoscale regime. PMID:27002063

Spontaneous helix formation in non-chiral bent-core liquid crystals with fast linear electro-optic effect

NASA Astrophysics Data System (ADS)

Sreenilayam, Sithara P.; Panarin, Yuri P.; Vij, Jagdish K.; Panov, Vitaly P.; Lehmann, Anne; Poppe, Marco; Prehm, Marko; Tschierske, Carsten

2016-05-01

Liquid crystals (LCs) represent one of the foundations of modern communication and photonic technologies. Present display technologies are based mainly on nematic LCs, which suffer from limited response time for use in active colour sequential displays and limited image grey scale. Herein we report the first observation of a spontaneously formed helix in a polar tilted smectic LC phase (SmC phase) of achiral bent-core (BC) molecules with the axis of helix lying parallel to the layer normal and a pitch much shorter than the optical wavelength. This new phase shows fast (~30 μs) grey-scale switching due to the deformation of the helix by the electric field. Even more importantly, defect-free alignment is easily achieved for the first time for a BC mesogen, thus providing potential use in large-scale devices with fast linear and thresholdless electro-optical response.

Effects of surface properties on droplet formation inside a microfluidic device

NASA Astrophysics Data System (ADS)

Steinhaus, Ben; Shen, Amy

2004-11-01

Micro-fluidic devices offer a unique method of creating and controlling droplets on small length scales. A microfluidic device is used to study the effects of surface properties on droplet formation of a 2-phase flow system. Four phase diagrams are generated to compare the dynamics of the 2 immiscible fluid system (silicone oil and water) inside microchannels with different surface properties. Results show that the channel surface plays an important role in determining the flow patterns and the droplet formation of the 2-phase fluid system.

Scaling-up vaccine production: implementation aspects of a biomass growth observer and controller.

PubMed

Soons, Zita I T A; van den IJssel, Jan; van der Pol, Leo A; van Straten, Gerrit; van Boxtel, Anton J B

2009-04-01

This study considers two aspects of the implementation of a biomass growth observer and specific growth rate controller in scale-up from small- to pilot-scale bioreactors towards a feasible bulk production process for whole-cell vaccine against whooping cough. The first is the calculation of the oxygen uptake rate, the starting point for online monitoring and control of biomass growth, taking into account the dynamics in the gas-phase. Mixing effects and delays are caused by amongst others the headspace and tubing to the analyzer. These gas phase dynamics are modelled using knowledge of the system in order to reconstruct oxygen consumption. The second aspect is to evaluate performance of the monitoring and control system with the required modifications of the oxygen consumption calculation on pilot-scale. In pilot-scale fed-batch cultivation good monitoring and control performance is obtained enabling a doubled concentration of bulk vaccine compared to standard batch production.

Multiple time scale analysis of pressure oscillations in solid rocket motors

NASA Astrophysics Data System (ADS)

Ahmed, Waqas; Maqsood, Adnan; Riaz, Rizwan

2018-03-01

In this study, acoustic pressure oscillations for single and coupled longitudinal acoustic modes in Solid Rocket Motor (SRM) are investigated using Multiple Time Scales (MTS) method. Two independent time scales are introduced. The oscillations occur on fast time scale whereas the amplitude and phase changes on slow time scale. Hopf bifurcation is employed to investigate the properties of the solution. The supercritical bifurcation phenomenon is observed for linearly unstable system. The amplitude of the oscillations result from equal energy gain and loss rates of longitudinal acoustic modes. The effect of linear instability and frequency of longitudinal modes on amplitude and phase of oscillations are determined for both single and coupled modes. For both cases, the maximum amplitude of oscillations decreases with the frequency of acoustic mode and linear instability of SRM. The comparison of analytical MTS results and numerical simulations demonstrate an excellent agreement.

The unified mechanism of aging effects in both martensite and parent phase for shape-memory alloys: atomic-level simulations

NASA Astrophysics Data System (ADS)

Deng, J.; Ding, X.; Suzuki, T.; Otsuka, K.; Lookman, T.; Saxena, A.; Sun, J.; Ren, X.

2011-03-01

Most shape-memory alloys (SMAs) subject to the aging effects not only in the martensite phase but also in the parent phase. These aging effects have been attracted much attention as they strongly affect the practical applications of SMAs. So far, the intrinsic mechanism of them has remained controversial due to the difficulty in visualization of what happens in atomic scale. In the present study, by using a combination of molecular dynamics method and Monte-Carlo method [1], we investigate the aging effects in both martensite and parent phase. We successfully reproduced the thermal behaviors of aging effects for SMAs, i.e., the Af temperature increase with aging time in martensite and the Ms temperature decrease with aging time in parent phase, which keep good agreement with the experimental observations [2]. In addition, quantitative analysis of the atomic configurations during aging reveals that the aging effects are not associated with a change in the average structure.

Effects of rotation on coolant passage heat transfer. Volume 2: Coolant passages with trips normal and skewed to the flow

NASA Technical Reports Server (NTRS)

Johnson, B. V.; Wagner, J. H.; Steuber, G. D.

1993-01-01

An experimental program was conducted to investigate heat transfer and pressure loss characteristics of rotating multipass passages, for configurations and dimensions typical of modem turbine blades. This experimental program is one part of the NASA Hot Section Technology (HOST) Initiative, which has as its overall objective the development and verification of improved analysis methods that will form the basis for a design system that will produce turbine components with improved durability. The objective of this program was the generation of a data base of heat transfer and pressure loss data required to develop heat transfer correlations and to assess computational fluid dynamic techniques for rotating coolant passages. The experimental work was broken down into two phases. Phase 1 consists of experiments conducted in a smooth wall large scale heat transfer model. A detailed discussion of these results was presented in volume 1 of a NASA Report. In Phase 2 the large scale model was modified to investigate the effects of skewed and normal passage turbulators. The results of Phase 2 along with comparison to Phase 1 is the subject of this Volume 2 NASA Report.

Patterns Cancer Prevention Through Induction of Phase 2 Enzymes

DTIC Science & Technology

2003-04-01

2) enzymes. During our Phase I Award, we identified sulforaphane as the most potent inducer of carcinogen defenses in the prostate cell. We have...characterized global effects of sulforaphane in prostate cancer cell lines using cDNA microarray technology that allows large-scale determination of...changes in gene expression. These findings argue strongly for a preventive intervention trial involving with sulforaphane . During our Phase 2 Award, we used

Innovative grinding wheel design for cost-effective machining of advanced ceramics

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

Licht, R.H.; Kuo, P.; Liu, S.

2000-05-01

This Final Report covers the Phase II Innovative Grinding Wheel (IGW) program in which Norton Company successfully developed a novel grinding wheel for cost-effective cylindrical grinding of advanced ceramics. In 1995, Norton Company successfully completed the 16-month Phase I technical effort to define requirements, design, develop, and evaluate a next-generation grinding wheel for cost-effective cylindrical grinding of advanced ceramics using small prototype wheels. The Phase II program was initiated to scale-up the new superabrasive wheel specification to larger diameters, 305-mm to 406-mm, required for most production grinding of cylindrical ceramic parts, and to perform in-house and independent validation grinding tests.

Acoustic Effects in Classical Nucleation Theory

NASA Technical Reports Server (NTRS)

Baird, J. K.; Su, C.-H.

2017-01-01

The effect of sound wave oscillations on the rate of nucleation in a parent phase can be calculated by expanding the free energy of formation of a nucleus of the second phase in powers of the acoustic pressure. Since the period of sound wave oscillation is much shorter than the time scale for nucleation, the acoustic effect can be calculated as a time average of the free energy of formation of the nucleus. The leading non-zero term in the time average of the free energy is proportional to the square of the acoustic pressure. The Young-Laplace equation for the surface tension of the nucleus can be used to link the time average of the square of the pressure in the parent phase to its time average in the nucleus of the second phase. Due to the surface tension, the pressure in the nuclear phase is higher than the pressure in the parent phase. The effect is to lower the free energy of formation of the nucleus and increase the rate of nucleation.

Effect of Modulation of ENSO by Decadal and Multidecadal Ocean-Atmospheric Oscillations on Continental US Streamflows

NASA Astrophysics Data System (ADS)

Singh, S.; Abebe, A.; Srivastava, P.; Chaubey, I.

2017-12-01

Evaluation of the influences of individual and coupled oceanic-atmospheric oscillations on streamflow at a regional scale in the United States is the focus of this study. The main climatic oscillations considered in this study are: El Niño Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO), and North Atlantic Oscillation (NAO). Unimpacted or minimally impacted by water management streamflow data from the Model Parameter Estimation Experiment (MOPEX) were used in this study. Two robust and novel non-parametric tests, namely, the rank based partial least square (PLS) and the Joint Rank Fit (JRFit) procedures were used to identify the individual and coupled effect of oscillations on streamflow across continental U.S. (CONUS), respectively. Moreover, the interactive effects of ENSO with decadal and multidecadal cycles were tested and quantified using the JRFit interaction test. The analysis of ENSO indicated higher streamflows during La Niña phase compared to the El Niño phase in Northwest, Northeast and the lower part of Ohio Valley while the opposite occurs for rest of the climatic regions in US. Two distinct climate regions (Northwest and Southeast) were identified from the PDO analysis where PDO negative phase results in increased streamflow than PDO positive phase. Consistent negative and positive correlated regions around the CONUS were identified for AMO and NAO, respectively. The interaction test of ENSO with decadal and multidecadal oscillations showed that El Niño is modulated by the negative phase of PDO and NAO, and the positive phase of AMO, respectively, in the Upper Midwest. However, La Niña is modulated by the positive phase of AMO and PDO in Ohio Valley and Northeast while in Southeast and the South it is modulated by AMO negative phase. Results of this study will assist water managers to understand the streamflow change patterns across the CONUS at decadal and multi-decadal time scales. The information derived from this study would be helpful for regional water managers in forecasting regional water availability and help them develop drought adaptation and mitigation policies by incorporating information based on the large scale ocean-atmospheric cycles.

Numerical Simulation of Two Phase Flows

NASA Technical Reports Server (NTRS)

Liou, Meng-Sing

2001-01-01

Two phase flows can be found in broad situations in nature, biology, and industry devices and can involve diverse and complex mechanisms. While the physical models may be specific for certain situations, the mathematical formulation and numerical treatment for solving the governing equations can be general. Hence, we will require information concerning each individual phase as needed in a single phase. but also the interactions between them. These interaction terms, however, pose additional numerical challenges because they are beyond the basis that we use to construct modern numerical schemes, namely the hyperbolicity of equations. Moreover, due to disparate differences in time scales, fluid compressibility and nonlinearity become acute, further complicating the numerical procedures. In this paper, we will show the ideas and procedure how the AUSM-family schemes are extended for solving two phase flows problems. Specifically, both phases are assumed in thermodynamic equilibrium, namely, the time scales involved in phase interactions are extremely short in comparison with those in fluid speeds and pressure fluctuations. Details of the numerical formulation and issues involved are discussed and the effectiveness of the method are demonstrated for several industrial examples.

Bench-Scale Process for Low-Cost Carbon Dioxide (CO2) Capture Using a Phase-Changing Absorbent

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

Westendorf, Tiffany; Caraher, Joel; Chen, Wei

2015-03-31

The objective of this project is to design and build a bench-scale process for a novel phase-changing aminosilicone-based CO2-capture solvent. The project will establish scalability and technical and economic feasibility of using a phase-changing CO2-capture absorbent for post-combustion capture of CO2 from coal-fired power plants with 90% capture efficiency and 95% CO2 purity at a cost of $40/tonne of CO2 captured by 2025 and a cost of <$10/tonne of CO2 captured by 2035. In the first budget period of this project, the bench-scale phase-changing CO2 capture process was designed using data and operating experience generated under a previous project (ARPA-emore » project DE-AR0000084). Sizing and specification of all major unit operations was completed, including detailed process and instrumentation diagrams. The system was designed to operate over a wide range of operating conditions to allow for exploration of the effect of process variables on CO2 capture performance.« less

Effects of plant downtime on the microbial community composition in the highly saline brine of a geothermal plant in the North German Basin.

PubMed

Westphal, Anke; Lerm, Stephanie; Miethling-Graff, Rona; Seibt, Andrea; Wolfgramm, Markus; Würdemann, Hilke

2016-04-01

The microbial biocenosis in highly saline fluids produced from the cold well of a deep geothermal heat store located in the North German Basin was characterized during regular plant operation and immediately after plant downtime phases. Genetic fingerprinting revealed the dominance of sulfate-reducing bacteria (SRB) and fermentative Halanaerobiaceae during regular plant operation, whereas after shutdown phases, sequences of sulfur-oxidizing bacteria (SOB) were also detected. The detection of SOB indicated oxygen ingress into the well during the downtime phase. High 16S ribosomal RNA (rRNA) and dsrA gene copy numbers at the beginning of the restart process showed an enrichment of bacteria, SRB, and SOB during stagnant conditions consistent with higher concentrations of dissolved organic carbon (DOC), sulfate, and hydrogen sulfide in the produced fluids. The interaction of SRB and SOB during plant downtimes might have enhanced the corrosion processes occurring in the well. It was shown that scale content of fluids was significantly increased after stagnant phases. Moreover, the sulfur isotopic signature of the mineral scales indicated microbial influence on scale formation.

Wave Tank Studies of Phase Velocities of Short Wind Waves

NASA Astrophysics Data System (ADS)

Ermakov, S.; Sergievskaya, I.; Shchegolkov, Yu.

Wave tank studies of phase velocities of short wind waves have been carried out using Ka-band radar and an Optical Spectrum Analyser. The phase velocities were retrieved from measured radar and optical Doppler shifts, taking into account measurements of surface drift velocities. The dispersion relationship was studied in centimetre (cm)- and millimetre(mm)-scale wavelength ranges at different fetches and wind speeds, both for a clean water surface and for water covered with surfactant films. It is ob- tained that the phase velocities do not follow the dispersion relation of linear capillary- gravity waves, increasing with fetch and, therefore, depending on phase velocities of dominant decimetre (dm)-centimetre-scale wind waves. One thus can conclude that nonlinear cm-mm-scale harmonics bound to the dominant wind waves and propagat- ing with the phase velocities of the decimetric waves are present in the wind wave spectrum. The resulting phase velocities of short wind waves are determined by re- lation between free and bound waves. The relative intensity of the bound waves in the spectrum of short wind waves is estimated. It is shown that this relation depends strongly on the surfactant concentration, because the damping effect due to films is different for free and bound waves; this results to changes of phase velocities of wind waves in the presence of surfactant films. This work was supported by MOD, UK via DERA Winfrith (Project ISTC 1774P) and by RFBR (Project 02-05-65102).

Inferring the effects of compositional boundary layers on crystal nucleation, growth textures, and mineral chemistry in natural volcanic tephras through submicron-resolution imaging

NASA Astrophysics Data System (ADS)

Zellmer, Georg; Sakamoto, Naoya; Hwang, Shyh-Lung; Matsuda, Nozomi; Iizuka, Yoshiyuki; Moebis, Anja; Yurimoto, Hisayoshi

2016-09-01

Crystal nucleation and growth are first order processes captured in volcanic rocks and record important information about the rates of magmatic processes and chemical evolution of magmas during their ascent and eruption. We have studied glass-rich andesitic tephras from the Central Plateau of the Southern Taupo Volcanic Zone by electron- and ion-microbeam imaging techniques to investigate down to sub-micrometre scale the potential effects of compositional boundary layers (CBLs) of melt around crystals on the nucleation and growth of mineral phases and the chemistry of crystal growth zones. We find that CBLs may influence the types of mineral phases nucleating and growing, and growth textures such as the development of swallowtails. The chemistry of the CBLs also has the capacity to trigger intermittent overgrowths of nanometre-scale bands of different phases in rapidly growing crystals, resulting in what we refer to as cryptic phase zoning. The existence of cryptic phase zoning has implications for the interpretation of microprobe compositional data, and the resulting inferences made on the conditions of magmatic evolution. Identification of cryptic phase zoning may in future lead to more accurate thermobarometric estimates and thus geospeedometric constraints. In future, a more quantitative characterization of CBL formation and its effects on crystal nucleation and growth may contribute to a better understanding of melt rheology and magma ascent processes at the onset of explosive volcanic eruptions, and will likely be of benefit to hazard mitigation efforts.

Integrated low emissions cleanup system for direct coal-fueled turbines

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

Lippert, T.E.; Newby, R.A.; Alvin, M.A.

1992-01-01

The Westinghouse Electric Corporation, Science Technology Center (W-STC) is developing an Integrated Low Emissions Cleanup (ILEC) concept for high-temperature gas cleaning to meet environmental standards, as well as to economical gas turbine life. The ILEC concept simultaneously controls sulfur, particulate, and alkali contaminants in high-pressure fuel gases or combustion gases at temperatures up to 1850[degrees]F for advanced power generation systems (PFBC, APFBC, IGCC, DCF7). The objective of this program is to demonstrate, at a bench scale, the conceptual, technical feasibility of the REC concept. The ELEC development program has a 3 phase structure: Phase 1 - laboratory-scale testing; phase 2more » - bench-scale equipment; design and fabrication; and phase 3 - bench-scale testing. Phase 1 laboratory testing has been completed. In Phase 1, entrained sulfur and alkali sorbent kinetics were measured and evaluated, and commercial-scale performance was projected. Related cold flow model testing has shown that gas-particle contacting within the ceramic barrier filter vessel will provide a good reactor environment. The Phase 1 test results and the commercial evaluation conducted in the Phase 1 program support the bench-scale facility testing to be performed in Phase 3. Phase 2 is nearing completion with the design and assembly of a modified, bench-scale test facility to demonstrate the technical feasibility of the ILEC features. This feasibility testing will be conducted in Phase 3.« less

Vanishing-Overhead Linear-Scaling Random Phase Approximation by Cholesky Decomposition and an Attenuated Coulomb-Metric.

PubMed

Luenser, Arne; Schurkus, Henry F; Ochsenfeld, Christian

2017-04-11

A reformulation of the random phase approximation within the resolution-of-the-identity (RI) scheme is presented, that is competitive to canonical molecular orbital RI-RPA already for small- to medium-sized molecules. For electronically sparse systems drastic speedups due to the reduced scaling behavior compared to the molecular orbital formulation are demonstrated. Our reformulation is based on two ideas, which are independently useful: First, a Cholesky decomposition of density matrices that reduces the scaling with basis set size for a fixed-size molecule by one order, leading to massive performance improvements. Second, replacement of the overlap RI metric used in the original AO-RPA by an attenuated Coulomb metric. Accuracy is significantly improved compared to the overlap metric, while locality and sparsity of the integrals are retained, as is the effective linear scaling behavior.

Joint Inversion of Phase and Amplitude Data of Surface Waves for North American Upper Mantle

NASA Astrophysics Data System (ADS)

Hamada, K.; Yoshizawa, K.

2015-12-01

For the reconstruction of the laterally heterogeneous upper-mantle structure using surface waves, we generally use phase delay information of seismograms, which represents the average phase velocity perturbation along a ray path, while the amplitude information has been rarely used in the velocity mapping. Amplitude anomalies of surface waves contain a variety of information such as anelastic attenuation, elastic focusing/defocusing, geometrical spreading, and receiver effects. The effects of elastic focusing/defocusing are dependent on the second derivative of phase velocity across the ray path, and thus, are sensitive to shorter-wavelength structure than the conventional phase data. Therefore, suitably-corrected amplitude data of surface waves can be useful for improving the lateral resolution of phase velocity models. In this study, we collect a large-number of inter-station phase velocity and amplitude ratio data for fundamental-mode surface waves with a non-linear waveform fitting between two stations of USArray. The measured inter-station phase velocity and amplitude ratios are then inverted simultaneously for phase velocity maps and local amplification factor at receiver locations in North America. The synthetic experiments suggest that, while the phase velocity maps derived from phase data only reflect large-scale tectonic features, those from phase and amplitude data tend to exhibit better recovery of the strength of velocity perturbations, which emphasizes local-scale tectonic features with larger lateral velocity gradients; e.g., slow anomalies in Snake River Plain and Rio Grande Rift, where significant local amplification due to elastic focusing are observed. Also, the spatial distribution of receiver amplification factor shows a clear correlation with the velocity structure. Our results indicate that inter-station amplitude-ratio data can be of help in reconstructing shorter-wavelength structures of the upper mantle.

The microdopant effects of surfactant elements on structure-phase transitions during the rapid quenched crystallization of Fe-C-based melts

NASA Astrophysics Data System (ADS)

Polukhin, V. A.; Belyakova, R. M.; Rigmant, L. K.

2008-02-01

The nature of microdopant effects of surfactant Te and H2 reagents on structure-phase transitions in rapidly quenched and crystallized eutectic Fe-C-based melts were studied by experimental and computer methods. On the base of results of statistic-geometrical analysis the new information about the structure changes in multi-scaling systems -from meso- to nano-ones were obtained.

Analysis of Nuclear Propagation Effects Utilizing Wideband Satellite Data.

DTIC Science & Technology

1981-04-01

integrated phase spectral energy on scales shorter than - 30 km. Like the TEC, the standard deviation of phase depends on the effective thickness of...Vila, P., "Etude Experimentale de L’Anomalie lonospherique Equatoriale en Afrique en Periode de Minimum Solaire ," Annales de Geophysique, Vol. 22, No...AFRDSP AT[: OP 65 ATTN: AFRDSS 82 DEPARTMENT OF THE AIR FORCE (Continued) DEPARTMENT OF ENERGY CONTRACTORS Electronic Systems Div EG&U, Inc Air force

Modulation of Small-scale Turbulence Structure by Large-scale Motions in the Absence of Direct Energy Transfer.

NASA Astrophysics Data System (ADS)

Brasseur, James G.; Juneja, Anurag

1996-11-01

Previous DNS studies indicate that small-scale structure can be directly altered through ``distant'' dynamical interactions by energetic forcing of the large scales. To remove the possibility of stimulating energy transfer between the large- and small-scale motions in these long-range interactions, we here perturb the large scale structure without altering its energy content by suddenly altering only the phases of large-scale Fourier modes. Scale-dependent changes in turbulence structure appear as a non zero difference field between two simulations from identical initial conditions of isotropic decaying turbulence, one perturbed and one unperturbed. We find that the large-scale phase perturbations leave the evolution of the energy spectrum virtually unchanged relative to the unperturbed turbulence. The difference field, on the other hand, is strongly affected by the perturbation. Most importantly, the time scale τ characterizing the change in in turbulence structure at spatial scale r shortly after initiating a change in large-scale structure decreases with decreasing turbulence scale r. Thus, structural information is transferred directly from the large- to the smallest-scale motions in the absence of direct energy transfer---a long-range effect which cannot be explained by a linear mechanism such as rapid distortion theory. * Supported by ARO grant DAAL03-92-G-0117

The putative liquid-liquid transition is a liquid-solid transition in atomistic models of water. II

NASA Astrophysics Data System (ADS)

Limmer, David T.; Chandler, David

2013-06-01

This paper extends our earlier studies of free energy functions of density and crystalline order parameters for models of supercooled water, which allows us to examine the possibility of two distinct metastable liquid phases [D. T. Limmer and D. Chandler, J. Chem. Phys. 135, 134503 (2011), 10.1063/1.3643333 and preprint arXiv:1107.0337 (2011)]. Low-temperature reversible free energy surfaces of several different atomistic models are computed: mW water, TIP4P/2005 water, Stillinger-Weber silicon, and ST2 water, the last of these comparing three different treatments of long-ranged forces. In each case, we show that there is one stable or metastable liquid phase, and there is an ice-like crystal phase. The time scales for crystallization in these systems far exceed those of structural relaxation in the supercooled metastable liquid. We show how this wide separation in time scales produces an illusion of a low-temperature liquid-liquid transition. The phenomenon suggesting metastability of two distinct liquid phases is actually coarsening of the ordered ice-like phase, which we elucidate using both analytical theory and computer simulation. For the latter, we describe robust methods for computing reversible free energy surfaces, and we consider effects of electrostatic boundary conditions. We show that sensible alterations of models and boundary conditions produce no qualitative changes in low-temperature phase behaviors of these systems, only marginal changes in equations of state. On the other hand, we show that altering sampling time scales can produce large and qualitative non-equilibrium effects. Recent reports of evidence of a liquid-liquid critical point in computer simulations of supercooled water are considered in this light.

The putative liquid-liquid transition is a liquid-solid transition in atomistic models of water. II.

PubMed

Limmer, David T; Chandler, David

2013-06-07

This paper extends our earlier studies of free energy functions of density and crystalline order parameters for models of supercooled water, which allows us to examine the possibility of two distinct metastable liquid phases [D. T. Limmer and D. Chandler, J. Chem. Phys. 135, 134503 (2011) and preprint arXiv:1107.0337 (2011)]. Low-temperature reversible free energy surfaces of several different atomistic models are computed: mW water, TIP4P/2005 water, Stillinger-Weber silicon, and ST2 water, the last of these comparing three different treatments of long-ranged forces. In each case, we show that there is one stable or metastable liquid phase, and there is an ice-like crystal phase. The time scales for crystallization in these systems far exceed those of structural relaxation in the supercooled metastable liquid. We show how this wide separation in time scales produces an illusion of a low-temperature liquid-liquid transition. The phenomenon suggesting metastability of two distinct liquid phases is actually coarsening of the ordered ice-like phase, which we elucidate using both analytical theory and computer simulation. For the latter, we describe robust methods for computing reversible free energy surfaces, and we consider effects of electrostatic boundary conditions. We show that sensible alterations of models and boundary conditions produce no qualitative changes in low-temperature phase behaviors of these systems, only marginal changes in equations of state. On the other hand, we show that altering sampling time scales can produce large and qualitative non-equilibrium effects. Recent reports of evidence of a liquid-liquid critical point in computer simulations of supercooled water are considered in this light.

Identifying stereotypic evolving micro-scale seizures (SEMS) in the hypoxic-ischemic EEG of the pre-term fetal sheep with a wavelet type-II fuzzy classifier.

PubMed

Abbasi, Hamid; Bennet, Laura; Gunn, Alistair J; Unsworth, Charles P

2016-08-01

Perinatal hypoxic-ischemic encephalopathy (HIE) around the time of birth due to lack of oxygen can lead to debilitating neurological conditions such as epilepsy and cerebral palsy. Experimental data have shown that brain injury evolves over time, but during the first 6-8 hours after HIE the brain has recovered oxidative metabolism in a latent phase, and brain injury is reversible. Treatments such as therapeutic cerebral hypothermia (brain cooling) are effective when started during the latent phase, and continued for several days. Effectiveness of hypothermia is lost if started after the latent phase. Post occlusion monitoring of particular micro-scale transients in the hypoxic-ischemic (HI) Electroencephalogram (EEG), from an asphyxiated fetal sheep model in utero, could provide precursory evidence to identify potential biomarkers of injury when brain damage is still treatable. In our studies, we have reported how it is possible to automatically detect HI EEG transients in the form of spikes and sharp waves during the latent phase of the HI EEG of the preterm fetal sheep. This paper describes how to identify stereotypic evolving micro-scale seizures (SEMS) which have a relatively abrupt onset and termination in a frequency range of 1.8-3Hz (Delta waves) superimposed on a suppressed EEG amplitude background post occlusion. This research demonstrates how a Wavelet Type-II Fuzzy Logic System (WT-Type-II-FLS) can be used to automatically identify subtle abnormal SEMS that occur during the latent phase with a preliminary average validation overall performance of 78.71%±6.63 over the 390 minutes of the latent phase, post insult, using in utero pre-term hypoxic fetal sheep models.

Observation of the seismic nucleation phase in the Ridgecrest, California, earthquake sequence

USGS Publications Warehouse

Ellsworth, W.L.; Beroza, G.C.

1998-01-01

Near-source observations of five M 3.8-5.2 earthquakes near Ridgecrest, California are consistent with the presence of a seismic nucleation phase. These earthquakes start abruptly, but then slow or stop before rapidly growing again toward their maximum rate of moment release. Deconvolution of instrument and path effects by empirical Green's functions demonstrates that the initial complexity at the start of the earthquake is a source effect. The rapid growth of the P-wave arrival at the start of the seismic nucleation phase supports the conclusion of Mori and Kanamori [1996] that these earthquakes begin without a magnitude-scaled slow initial phase of the type observed by Iio [1992, 1995].

Future utilization of space: Silverton Conference on material science and phase transformations in zero-gravity, summary of proceeding

NASA Technical Reports Server (NTRS)

Eisner, M. (Editor)

1975-01-01

The importance of zero gravity environment in the development and production of new and improved materials is considered along with the gravitational effects on phase changes or critical behavior in a variety of materials. Specific experiments discussed include: fine scale phase separation in zero gravity; glass formation in zero gravity; effects of gravitational perturbations on determination of critical exponents; and light scattering from long wave fluctuations in liquids in zero gravity. It is concluded that the space shuttle/spacelab system is applicable to various fields of interest.

Lunar Phase Function at 1064 Nm from Lunar Orbiter Laser Altimeter Passive and Active Radiometry

NASA Technical Reports Server (NTRS)

Barker, M. K.; Sun, X.; Mazarico, E.; Neumann, G. A.; Zuber, M. T.; Smith, D. E.

2016-01-01

We present initial calibration and results of passive radiometry collected by the Lunar Orbiter Laser Altimeter onboard the Lunar Reconnaissance Orbiter over the course of 12 months. After correcting for time- and temperature-dependent dark noise and detector responsivity variations, the LOLA passive radiometry measurements are brought onto the absolute radiance scale of the SELENE Spectral Profiler. The resulting photometric precision is estimated to be 5%. We leverage the unique ability of LOLA to measure normal albedo to explore the 1064 nm phase function's dependence on various geologic parameters. On a global scale, we find that iron abundance and optical maturity (quantified by FeO and OMAT) are the dominant controlling parameters. Titanium abundance (TiO2), surface roughness on decimeter to decameter scales, and soil thermo- physical properties have a smaller effect, but the latter two are correlated with OMAT, indicating that exposure age is the driving force behind their effects in a globally-averaged sense. The phase function also exhibits a dependence on surface slope at approximately 300 m baselines, possibly the result of mass wasting exposing immature material and/or less space weathering due to reduced sky visibility. Modeling the photometric function in the Hapke framework, we find that, relative to the highlands, the maria exhibit decreased backscattering, a smaller opposition effect (OE) width, and a smaller OE amplitude. Immature highlands regolith has a higher backscattering fraction and a larger OE width compared to mature highlands regolith. Within the maria, the backscattering fraction and OE width show little dependence on TiO2 and OMAT. Variations in the phase function shape at large phase angles are observed in and around the Copernican-aged Jackson crater, including its dark halo, a putative impact melt deposit. Finally, the phase function of the Reiner Gamma Formation behaves more optically immature than is typical for its composition and OMAT, suggesting the visible-to-near-infrared spectrum and phase function respond differently to the unusual regolith evolution and properties at this location. The phase difference map revealed additional geologically-influenced variations in the phase function's shape. In particular, variations were observed associated with the dark halo around Jackson crater, the impact ejecta of Copernicus and Giordano Bruno, and the Reiner Gamma Formation. For the latter, we 915 found that the phase function behaves more optically immature than the global phase function for its composition and OMAT, suggesting a difference in how the visible-to-near-IR spectrum and phase function respond to the unusual regolith evolution and properties at this location.

Virtual Patterson Experiment - A Way to Access the Rheology of Aggregates and Melanges

NASA Astrophysics Data System (ADS)

Delannoy, Thomas; Burov, Evgueni; Wolf, Sylvie

2014-05-01

Understanding the mechanisms of lithospheric deformation requires bridging the gap between human-scale laboratory experiments and the huge geological objects they represent. Those experiments are limited in spatial and time scale as well as in choice of materials (e.g., mono-phase minerals, exaggerated temperatures and strain rates), which means that the resulting constitutive laws may not fully represent real rocks at geological spatial and temporal scales. We use the thermo-mechanical numerical modelling approach as a tool to link both experiments and nature and hence better understand the rheology of the lithosphere, by enabling us to study the behavior of polymineralic aggregates and their impact on the localization of the deformation. We have adapted the large strain visco-elasto-plastic Flamar code to allow it to operate at all spatial and temporal scales, from sub-grain to geodynamic scale, and from seismic time scales to millions of years. Our first goal was to reproduce real rock mechanics experiments on deformation of mono and polymineralic aggregates in Patterson's load machine in order to deepen our understanding of the rheology of polymineralic rocks. In particular, we studied in detail the deformation of a 15x15 mm mica-quartz sample at 750 °C and 300 MPa. This mixture includes a molten phase and a solid phase in which shear bands develop as a result of interactions between ductile and brittle deformation and stress concentration at the boundaries between weak and strong phases. We used digitized x-ray scans of real samples as initial configuration for the numerical models so the model-predicted deformation and stress-strain behavior can match those observed in the laboratory experiment. Analyzing the numerical experiments providing the best match with the press experiments and making other complementary models by changing different parameters in the initial state (strength contrast between the phases, proportions, microstructure, etc.) provides a number of new elements of understanding of the mechanisms governing the localization of the deformation across the aggregates. We next used stress-strain curves derived from the numerical experiments to study in detail the evolution of the rheological behavior of each mineral phase as well as that of the mixtures in order to formulate constitutive relations for mélanges and polymineralic aggregates. The next step of our approach would be to link the constitutive laws obtained at small scale (laws that govern the rheology of a polymineralic aggregate, the effect of the presence of a molten phase, etc.) to the large-scale behavior of the Earth by implementing them in lithosphere-scale models.

Application of Emulsified Zero-Valent Iron to Marine Environments

NASA Technical Reports Server (NTRS)

Quinn, Jacqueline W.; Brooks, Kathleen B.; Geiger, Cherie L.; Clausen, Christian A.; Milum, Kristen M.

2006-01-01

Contamination of marine waters and sediments with heavy metals and dense non-aqueous phase liquids (DNAPLs) including chlorinated solvents, pesticides and PCBs pose ecological and human health risks through the potential of the contaminant to bioaccumulate in fish, shellfish and avian populations. The contaminants enter marine environments through improper disposal techniques and storm water runoff. Current remediation technologies for application to marine environments include costly dredging and off-site treatment of the contaminated media. Emulsified zero-valent iron (EZVI) has been proven to effectively degrade dissolved-phase and DNAPL-phase contaminants in freshwater environments on both the laboratory and field-scale level. Emulsified Zero-Valent Metal (EZVM) using metals such as iron and/or magnesium have been shown in the laboratory and on the bench scale to be effective at removing metals contamination in freshwater environments. The application to marine environments, however, is only just being explored. This paper discusses. the potential use of EZVI or EZVM in brackish and saltwater environments, with supporting laboratory data detailing its effectiveness on trichloroethylene, lead, copper, nickel and cadmium.

Multi scale modeling of ignition and combustion of micro and nano aluminum particles

NASA Astrophysics Data System (ADS)

Puri, Puneesh

With renewed interest in nano scale energetic materials like aluminum, many fundamental issues concerning the ignition and combustion characteristics at nano scales, remain to be clarified. The overall aim of the current study is the establishment of a unified theory accommodating the various processes and mechanisms involved in the combustion and ignition of aluminum particles at micro and nano scales. A comprehensive review on the ignition and combustion of aluminum particles at multi scales was first performed identifying various processes and mechanisms involved. Research focus was also placed on the establishment of a Molecular Dynamics (MD) simulation tool to investigate the characteristics of nano-particulate aluminum through three major studies. The general computational framework involved parallelized preprocessing, post-processing and main code with capability to simulate different ensembles using appropriate algorithms. Size dependence of melting temperature of pure aluminum particles was investigated in the first study. Phenomena like dynamic coexistence of solid and liquid phase and effect of surface charges on melting were explored. The second study involved the study of effect of defects in the form of voids on melting of bulk and particulate phase aluminum. The third MD study was used to analyze the thermo-mechanical behavior of nano-sized aluminum particles with total diameter of 5-10 nm and oxide thickness of 1-2.5 nm. The ensuing solid-solid and solid-liquid phase changes in the core and shell, stresses developed within the shell, and the diffusion of aluminum cations in the oxide layer, were explored in depth for amorphous and crystalline oxide layers. In the limiting case, the condition for pyrophoricity/explosivity of nano-particulate aluminum was analyzed and modified. The size dependence of thermodynamic properties at nano scales were considered and incorporated into the existing theories developed for micro and larger scales. Finally, a phenomenological theory for ignition and combustion of aluminum particles was proposed. The whole time history from ignition till particle burnout was divided into five stages. An attempt was made to explore different modes of ignition based on the effect of pressure, temperature, oxidizer, oxide thickness and particle diameter and was investigated using length and time scales involved during ignition and combustion.

Unidirectional waveguide grating antennas with uniform emission for optical phased arrays.

PubMed

Raval, Manan; Poulton, Christopher V; Watts, Michael R

2017-07-01

We demonstrate millimeter-scale optical waveguide grating antennas with unidirectional emission for integrated optical phased arrays. Unidirectional emission eliminates the fundamental problem of blind spots in the element factor of a phased array caused by reflections of antenna radiation within the substrate. Over 90% directionality is demonstrated using a design consisting of two silicon nitride layers. Furthermore, the perturbation strength along the antenna is apodized to achieve uniform emission for the first time, to the best of our knowledge, on a millimeter scale. This allows for a high effective aperture and receiving efficiency. The emission profile of the measured 3 mm long antenna has a standard deviation of 8.65% of the mean. These antennas are state of the art and will allow for integrated optical phased arrays with blind-spot-free high transmission output power and high receiving efficiency for LIDAR and free-space communication systems.

Impact of tissue atrophy on high-pass filtered MRI signal phase-based assessment in large-scale group-comparison studies: A simulation study

NASA Astrophysics Data System (ADS)

Schweser, Ferdinand; Dwyer, Michael G.; Deistung, Andreas; Reichenbach, Jürgen R.; Zivadinov, Robert

2013-10-01

The assessment of abnormal accumulation of tissue iron in the basal ganglia nuclei and in white matter plaques using the gradient echo magnetic resonance signal phase has become a research focus in many neurodegenerative diseases such as multiple sclerosis or Parkinson’s disease. A common and natural approach is to calculate the mean high-pass-filtered phase of previously delineated brain structures. Unfortunately, the interpretation of such an analysis requires caution: in this paper we demonstrate that regional gray matter atrophy, which is concomitant with many neurodegenerative diseases, may itself directly result in a phase shift seemingly indicative of increased iron concentration even without any real change in the tissue iron concentration. Although this effect is relatively small results of large-scale group comparisons may be driven by anatomical changes rather than by changes of the iron concentration.

Integrated low emissions cleanup system for direct coal-fueled turbines

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

Lippert, T.E.; Newby, R.A.; Alvin, M.A.

1992-12-31

The Westinghouse Electric Corporation, Science & Technology Center (W-STC) is developing an Integrated Low Emissions Cleanup (ILEC) concept for high-temperature gas cleaning to meet environmental standards, as well as to economical gas turbine life. The ILEC concept simultaneously controls sulfur, particulate, and alkali contaminants in high-pressure fuel gases or combustion gases at temperatures up to 1850{degrees}F for advanced power generation systems (PFBC, APFBC, IGCC, DCF7). The objective of this program is to demonstrate, at a bench scale, the conceptual, technical feasibility of the REC concept. The ELEC development program has a 3 phase structure: Phase 1 - laboratory-scale testing; phasemore » 2 - bench-scale equipment; design and fabrication; and phase 3 - bench-scale testing. Phase 1 laboratory testing has been completed. In Phase 1, entrained sulfur and alkali sorbent kinetics were measured and evaluated, and commercial-scale performance was projected. Related cold flow model testing has shown that gas-particle contacting within the ceramic barrier filter vessel will provide a good reactor environment. The Phase 1 test results and the commercial evaluation conducted in the Phase 1 program support the bench-scale facility testing to be performed in Phase 3. Phase 2 is nearing completion with the design and assembly of a modified, bench-scale test facility to demonstrate the technical feasibility of the ILEC features. This feasibility testing will be conducted in Phase 3.« less

Improved Separations of Proteins and Sugar Derivatives Using the Small-Scale Cross-Axis Coil Planet Centrifuge with Locular Multilayer Coiled Columns

PubMed Central

Shinomiya, Kazufusa; Umezawa, Motoki; Seki, Manami; Nitta, Jun; Zaima, Kazumasa; Harikai, Naoki; Ito, Yoichiro

2016-01-01

1) Background Countercurrent chromatography (CCC) is liquid-liquid partition chromatography without using a solid support matrix. This technique requires further improvement of partition efficiency and shortening theseparation time. 2) Methods The locular multilayer coils modified with and without mixer glass beads were developed for the separation of proteins and 4-methylumbelliferyl (MU) sugar derivatives using the small-scale cross-axis coil planet centrifuge. 3) Results Proteins were well separated from each other and the separation was improved at a low flow rate of the mobile phase. On the other hand, 4-MU sugar derivatives were sufficiently resolved with short separation time at a highflow rate of the mobile phase under satisfactory stationary phase retention. 4) Conclusion Effective separations were achieved using the locular multilayer coil for proteins with aqueous-aqueous polymer phase systems and for 4-MU sugar derivatives with organic-aqueous two-phase solvent systems by inserting a glass bead into each locule. PMID:27891507

Natural Length Scales Shape Liquid Phase Continuity in Unsaturated Flows

NASA Astrophysics Data System (ADS)

Assouline, S.; Lehmann, P. G.; Or, D.

2015-12-01

Unsaturated flows supporting soil evaporation and internal drainage play an important role in various hydrologic and climatic processes manifested at a wide range of scales. We study inherent natural length scales that govern these flow processes and constrain the spatial range of their representation by continuum models. These inherent length scales reflect interactions between intrinsic porous medium properties that affect liquid phase continuity, and the interplay among forces that drive and resist unsaturated flow. We have defined an intrinsic length scale for hydraulic continuity based on pore size distribution that controls soil evaporation dynamics (i.e., stage 1 to stage 2 transition). This simple metric may be used to delineate upper bounds for regional evaporative losses or the depth of soil-atmosphere interactions (in the absence of plants). A similar length scale governs the dynamics of internal redistribution towards attainment of field capacity, again through its effect on hydraulic continuity in the draining porous medium. The study provides a framework for guiding numerical and mathematical models for capillary flows across different scales considering the necessary conditions for coexistence of stationarity (REV), hydraulic continuity and intrinsic capillary gradients.

Novel Approach to Conducting Blast Load Analyses Using Abaqus/Explicit-CEL

DTIC Science & Technology

2010-05-01

versus uncased, effects of afterburning , angle of incidence with respect to incoming shock, nearby geometry/barriers interacting with the shock...2. Blast parameters as a function of scaled distance – from TNT air blast data (DOE/TIC-11268, 1981). Due to inertial effects, the volume of air...positive phase duration) can be determined for a particular scaled distance. Figure 2 was generated from TNT air blast data for bare, spherical charges

Organic Single-Crystal Semiconductor Films on a Millimeter Domain Scale.

PubMed

Kwon, Sooncheol; Kim, Jehan; Kim, Geunjin; Yu, Kilho; Jo, Yong-Ryun; Kim, Bong-Joong; Kim, Junghwan; Kang, Hongkyu; Park, Byoungwook; Lee, Kwanghee

2015-11-18

Nucleation and growth processes can be effectively controlled in organic semiconductor films through a new concept of template-mediated molecular crystal seeds during the phase transition; the effective control of these processes ensures millimeter-scale crystal domains, as well as the performance of the resulting organic films with intrinsic hole mobility of 18 cm(2) V(-1) s(-1). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A model problem concerning ionic transport in microstructured solid electrolytes

NASA Astrophysics Data System (ADS)

Curto Sillamoni, Ignacio J.; Idiart, Martín I.

2015-11-01

We consider ionic transport by diffusion and migration through microstructured solid electrolytes. The assumed constitutive relations for the constituent phases follow from convex energy and dissipation potentials which guarantee thermodynamic consistency. The effective response is determined by homogenizing the relevant field equations via the notion ofmulti-scale convergence. The resulting homogenized response involves several effective tensors, but they all require the solution of just one standard conductivity problem over the representative volume element. A multi-scale model for semicrystalline polymer electrolytes with spherulitic morphologies is derived by applying the theory to a specific class of two-dimensional microgeometries for which the effective response can be computed exactly. An enriched model accounting for a random dispersion of filler particles with interphases is also derived. In both cases, explicit expressions for the effective material parameters are provided. The models are used to explore the effect of crystallinity and filler content on the overall response. Predictions support recent experimental observations on doped poly-ethylene-oxide systems which suggest that the anisotropic crystalline phase can actually support faster ion transport than the amorphous phase along certain directions dictated by the morphology of the polymeric chains. Predictions also support the viewpoint that ceramic fillers improve ionic conductivity and cation transport number via interphasial effects.

A geometrical shift results in erroneous appearance of low frequency tissue eddy current induced phase maps.

PubMed

Mandija, Stefano; van Lier, Astrid L H M W; Katscher, Ulrich; Petrov, Petar I; Neggers, Sebastian F W; Luijten, Peter R; van den Berg, Cornelis A T

2016-09-01

Knowledge on low frequency (LF) tissue conductivity is relevant for various biomedical purposes. To obtain this information, LF phase maps arising from time-varying imaging gradients have been demonstrated to create a LF conductivity contrast. Essential in this methodology is the subtraction of phase images acquired with opposite gradient polarities to separate LF and RF phase effects. Here we demonstrate how sensitive these subtractions are with respect to geometrical distortions. The effect of geometrical distortions on LF phase maps is mathematically defined. After quantifying typical geometrical distortions, their effects on LF phase maps are evaluated using conductive phantoms. For validation, electromagnetic simulations of LF phase maps were performed. Even sub-voxel distortions of 10% of the voxel size, measured for a typical LF MR sequence, cause leakage of RF phase into LF phase of several milli-radians, leading to a misleading pattern of LF phase maps. This leakage is mathematically confirmed, while simulations indicate that the expected LF phase should be in order of micro-radians. The conductivity scaling of LF phase maps is attributable to the RF phase leakage, thus dependent on the RF conductivity. In fact, simulations show that the LF phase is not measurable. Magn Reson Med 76:905-912, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

High Temperature Oxidation Behavior of gamma-Ni+gamma'-Ni3Al Alloys and Coatings Modified with Pt and Reactive Elements

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

Mu, Nan

2007-12-01

Materials for high-pressure turbine blades must be able to operate in the high-temperature gases (above 1000 C) emerging from the combustion chamber. Accordingly, the development of nickel-based superalloys has been constantly motivated by the need to have improved engine efficiency, reliability and service lifetime under the harsh conditions imposed by the turbine environment. However, the melting point of nickel (1455 C) provides a natural ceiling for the temperature capability of nickel-based superalloys. Thus, surface-engineered turbine components with modified diffusion coatings and overlay coatings are used. Theses coatings are capable of forming a compact and adherent oxide scale, which greatly impedesmore » the further transport of reactants between the high-temperature gases and the underlying metal and thus reducing attack by the atmosphere. Typically, these coatings contain β-NiAl as a principal constituent phase in order to have sufficient aluminum content to form an Al 2O 3 scale at elevated temperatures. The drawbacks to the currently-used {beta}-based coatings, such as phase instabilities, associated stresses induced by such phase instabilities, and extensive coating/substrate interdiffusion, are major motivations in this study to seek next-generation coatings. The high-temperature oxidation resistance of novel Pt + Hf-modified γ-Ni + γ-Ni 3Al-based alloys and coatings were investigated in this study. Both early-stage and 4-days isothermal oxidation behavior of single-phase γ-Ni and γ'-Ni 3Al alloys were assessed by examining the weight changes, oxide-scale structures, and elemental concentration profiles through the scales and subsurface alloy regions. It was found that Pt promotes Al 2O 3 formation by suppressing the NiO growth on both γ-Ni and γ'Ni 3Al single-phase alloys. This effect increases with increasing Pt content. Moreover, Pt exhibits this effect even at lower temperatures (~970 C) in the very early stage of oxidation. It was also inferred that Pt enhances the diffusive flux of aluminum from the substrate to the scale/alloy interface. Relatively low levels of hafnium addition to Pt-free γ'-Ni 3Al increased the extent of external NiO formation due to non-protective HfO 2 formation. Accordingly, this effect intensified with increasing Hf content from 0.2 to 0.5 at.%.« less

Phase of Illness in palliative care: Cross-sectional analysis of clinical data from community, hospital and hospice patients.

PubMed

Mather, Harriet; Guo, Ping; Firth, Alice; Davies, Joanna M; Sykes, Nigel; Landon, Alison; Murtagh, Fliss Em

2018-02-01

Phase of Illness describes stages of advanced illness according to care needs of the individual, family and suitability of care plan. There is limited evidence on its association with other measures of symptoms, and health-related needs, in palliative care. The aims of the study are as follows. (1) Describe function, pain, other physical problems, psycho-spiritual problems and family and carer support needs by Phase of Illness. (2) Consider strength of associations between these measures and Phase of Illness. Secondary analysis of patient-level data; a total of 1317 patients in three settings. Function measured using Australia-modified Karnofsky Performance Scale. Pain, other physical problems, psycho-spiritual problems and family and carer support needs measured using items on Palliative Care Problem Severity Scale. Australia-modified Karnofsky Performance Scale and Palliative Care Problem Severity Scale items varied significantly by Phase of Illness. Mean function was highest in stable phase (65.9, 95% confidence interval = 63.4-68.3) and lowest in dying phase (16.6, 95% confidence interval = 15.3-17.8). Mean pain was highest in unstable phase (1.43, 95% confidence interval = 1.36-1.51). Multinomial regression: psycho-spiritual problems were not associated with Phase of Illness ( χ 2  = 2.940, df = 3, p = 0.401). Family and carer support needs were greater in deteriorating phase than unstable phase (odds ratio (deteriorating vs unstable) = 1.23, 95% confidence interval = 1.01-1.49). Forty-nine percent of the variance in Phase of Illness is explained by Australia-modified Karnofsky Performance Scale and Palliative Care Problem Severity Scale. Phase of Illness has value as a clinical measure of overall palliative need, capturing additional information beyond Australia-modified Karnofsky Performance Scale and Palliative Care Problem Severity Scale. Lack of significant association between psycho-spiritual problems and Phase of Illness warrants further investigation.

Sensitivity of the Positive and Negative Syndrome Scale (PANSS) in Detecting Treatment Effects via Network Analysis.

PubMed

Esfahlani, Farnaz Zamani; Sayama, Hiroki; Visser, Katherine Frost; Strauss, Gregory P

2017-12-01

Objective: The Positive and Negative Syndrome Scale is a primary outcome measure in clinical trials examining the efficacy of antipsychotic medications. Although the Positive and Negative Syndrome Scale has demonstrated sensitivity as a measure of treatment change in studies using traditional univariate statistical approaches, its sensitivity to detecting network-level changes in dynamic relationships among symptoms has yet to be demonstrated using more sophisticated multivariate analyses. In the current study, we examined the sensitivity of the Positive and Negative Syndrome Scale to detecting antipsychotic treatment effects as revealed through network analysis. Design: Participants included 1,049 individuals diagnosed with psychotic disorders from the Phase I portion of the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) study. Of these participants, 733 were clinically determined to be treatment-responsive and 316 were found to be treatment-resistant. Item level data from the Positive and Negative Syndrome Scale were submitted to network analysis, and macroscopic, mesoscopic, and microscopic network properties were evaluated for the treatment-responsive and treatment-resistant groups at baseline and post-phase I antipsychotic treatment. Results: Network analysis indicated that treatment-responsive patients had more densely connected symptom networks after antipsychotic treatment than did treatment-responsive patients at baseline, and that symptom centralities increased following treatment. In contrast, symptom networks of treatment-resistant patients behaved more randomly before and after treatment. Conclusions: These results suggest that the Positive and Negative Syndrome Scale is sensitive to detecting treatment effects as revealed through network analysis. Its findings also provide compelling new evidence that strongly interconnected symptom networks confer an overall greater probability of treatment responsiveness in patients with psychosis, suggesting that antipsychotics achieve their effect by enhancing a number of central symptoms, which then facilitate reduction of other highly coupled symptoms in a network-like fashion.

Phase diagrams of vortex matter with multi-scale inter-vortex interactions in layered superconductors.

PubMed

Meng, Qingyou; Varney, Christopher N; Fangohr, Hans; Babaev, Egor

2017-01-25

It was recently proposed to use the stray magnetic fields of superconducting vortex lattices to trap ultracold atoms for building quantum emulators. This calls for new methods for engineering and manipulating of the vortex states. One of the possible routes utilizes type-1.5 superconducting layered systems with multi-scale inter-vortex interactions. In order to explore the possible vortex states that can be engineered, we present two phase diagrams of phenomenological vortex matter models with multi-scale inter-vortex interactions featuring several attractive and repulsive length scales. The phase diagrams exhibit a plethora of phases, including conventional 2D lattice phases, five stripe phases, dimer, trimer, and tetramer phases, void phases, and stable low-temperature disordered phases. The transitions between these states can be controlled by the value of an applied external field.

Sample-based synthesis of two-scale structures with anisotropy

DOE PAGES

Liu, Xingchen; Shapiro, Vadim

2017-05-19

A vast majority of natural or synthetic materials are characterized by their anisotropic properties, such as stiffness. Such anisotropy is effected by the spatial distribution of the fine-scale structure and/or anisotropy of the constituent phases at a finer scale. In design, proper control of the anisotropy may greatly enhance the efficiency and performance of synthesized structures. In this paper, we propose a sample-based two-scale structure synthesis approach that explicitly controls anisotropic effective material properties of the structure on the coarse scale by orienting sampled material neighborhoods at the fine scale. We first characterize the non-uniform orientations distribution of the samplemore » structure by showing that the principal axes of an orthotropic material may be determined by the eigenvalue decomposition of its effective stiffness tensor. Such effective stiffness tensors can be efficiently estimated based on the two-point correlation functions of the fine-scale structures. Then we synthesize the two-scale structure by rotating fine-scale structures from the sample to follow a given target orientation field. Finally, the effectiveness of the proposed approach is demonstrated through examples in both 2D and 3D.« less

Sample-based synthesis of two-scale structures with anisotropy

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

Liu, Xingchen; Shapiro, Vadim

A vast majority of natural or synthetic materials are characterized by their anisotropic properties, such as stiffness. Such anisotropy is effected by the spatial distribution of the fine-scale structure and/or anisotropy of the constituent phases at a finer scale. In design, proper control of the anisotropy may greatly enhance the efficiency and performance of synthesized structures. In this paper, we propose a sample-based two-scale structure synthesis approach that explicitly controls anisotropic effective material properties of the structure on the coarse scale by orienting sampled material neighborhoods at the fine scale. We first characterize the non-uniform orientations distribution of the samplemore » structure by showing that the principal axes of an orthotropic material may be determined by the eigenvalue decomposition of its effective stiffness tensor. Such effective stiffness tensors can be efficiently estimated based on the two-point correlation functions of the fine-scale structures. Then we synthesize the two-scale structure by rotating fine-scale structures from the sample to follow a given target orientation field. Finally, the effectiveness of the proposed approach is demonstrated through examples in both 2D and 3D.« less

Phase diagram, correlation gap, and critical properties of the coulomb glass.

PubMed

Goethe, Martin; Palassini, Matteo

2009-07-24

We investigate the lattice Coulomb glass model in three dimensions via Monte Carlo simulations. No evidence for an equilibrium glass phase is found down to very low temperatures, although the correlation length increases rapidly near T = 0. A charge-ordered phase exists at low disorder. The transition to this phase is consistent with the random field Ising universality class, which shows that the interaction is effectively screened at moderate temperature. For large disorder, the single-particle density of states near the Coulomb gap satisfies the scaling relation g(epsilon, T) = T;{delta}f(|epsilon|/T) with delta = 2.01 +/- 0.05 in agreement with the prediction of Efros and Shklovskii. For decreasing disorder, a crossover to a larger effective exponent occurs due to the proximity of the charge-ordered phase.

Panoscopic approach for high-performance Te-doped skutterudite

DOE PAGES

Liang, Tao; Su, Xianli; Yan, Yonggao; ...

2017-02-24

One-step plasma-activated sintering (OS-PAS) fabrication of single-phase high-performance CoSb 3-based skutterudite thermoelectric material with a hierarchical structure on a time scale of a few minutes is first reported here. The formation mechanism of the CoSb 3 phase and the effects of the current and pressure fields on the phase transformation and microstructure evolution are studied in the one-step PAS process. The application of the panoscopic approach to this system and its effect on the transport properties are investigated. The results show that the hierarchical structure forms during the formation of the skutterudite phase under the effects of both current andmore » sintering pressure. The samples fabricated by the OS-PAS technique have defined hierarchical structures, which scatter phonons more intensely over a broader range of frequencies and significantly reduce the lattice thermal conductivity. High-performance bulk Te-doped skutterudite with the maximum ZT of 1.1 at 820 K for the composition CoSb 2.875Te 0.125 was obtained. Such high ZT values rival those obtained from single filled skutterudites. As a result, this newly developed OS-PAS technique enhances the thermoelectric performance, dramatically shortens the synthesis period and provides a facile method for obtaining hierarchical thermoelectric materials on a large scale.« less

Phase of the Wilson line at high temperature in the standard model

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

Korthals Altes, C.P.; Lee, K.; Pisarski, R.D.

1994-09-26

We compute the effective potential for the phase of the Wilson line at high temperature in the standard model to one-loop order. Besides the trivial vacua, there are metastable states in the direction of U(1) hypercharge. Assuming that the Universe starts out in such a metastable state at the Planck scale, it easily persists to the time of the electroweak phase transition, which then proceeds by an unusual mechanism. All remnants of the metastable state evaporate about the time of the QCD phase transition.

A new statistical model for subgrid dispersion in large eddy simulations of particle-laden flows

NASA Astrophysics Data System (ADS)

Muela, Jordi; Lehmkuhl, Oriol; Pérez-Segarra, Carles David; Oliva, Asensi

2016-09-01

Dispersed multiphase turbulent flows are present in many industrial and commercial applications like internal combustion engines, turbofans, dispersion of contaminants, steam turbines, etc. Therefore, there is a clear interest in the development of models and numerical tools capable of performing detailed and reliable simulations about these kind of flows. Large Eddy Simulations offer good accuracy and reliable results together with reasonable computational requirements, making it a really interesting method to develop numerical tools for particle-laden turbulent flows. Nonetheless, in multiphase dispersed flows additional difficulties arises in LES, since the effect of the unresolved scales of the continuous phase over the dispersed phase is lost due to the filtering procedure. In order to solve this issue a model able to reconstruct the subgrid velocity seen by the particles is required. In this work a new model for the reconstruction of the subgrid scale effects over the dispersed phase is presented and assessed. This innovative methodology is based in the reconstruction of statistics via Probability Density Functions (PDFs).

Ultralow-power switching via defect engineering in germanium telluride phase-change memory devices.

PubMed

Nukala, Pavan; Lin, Chia-Chun; Composto, Russell; Agarwal, Ritesh

2016-01-25

Crystal-amorphous transformation achieved via the melt-quench pathway in phase-change memory involves fundamentally inefficient energy conversion events; and this translates to large switching current densities, responsible for chemical segregation and device degradation. Alternatively, introducing defects in the crystalline phase can engineer carrier localization effects enhancing carrier-lattice coupling; and this can efficiently extract work required to introduce bond distortions necessary for amorphization from input electrical energy. Here, by pre-inducing extended defects and thus carrier localization effects in crystalline GeTe via high-energy ion irradiation, we show tremendous improvement in amorphization current densities (0.13-0.6 MA cm(-2)) compared with the melt-quench strategy (∼50 MA cm(-2)). We show scaling behaviour and good reversibility on these devices, and explore several intermediate resistance states that are accessible during both amorphization and recrystallization pathways. Existence of multiple resistance states, along with ultralow-power switching and scaling capabilities, makes this approach promising in context of low-power memory and neuromorphic computation.

Ultralow-power switching via defect engineering in germanium telluride phase-change memory devices

PubMed Central

Nukala, Pavan; Lin, Chia-Chun; Composto, Russell; Agarwal, Ritesh

2016-01-01

Crystal–amorphous transformation achieved via the melt-quench pathway in phase-change memory involves fundamentally inefficient energy conversion events; and this translates to large switching current densities, responsible for chemical segregation and device degradation. Alternatively, introducing defects in the crystalline phase can engineer carrier localization effects enhancing carrier–lattice coupling; and this can efficiently extract work required to introduce bond distortions necessary for amorphization from input electrical energy. Here, by pre-inducing extended defects and thus carrier localization effects in crystalline GeTe via high-energy ion irradiation, we show tremendous improvement in amorphization current densities (0.13–0.6 MA cm−2) compared with the melt-quench strategy (∼50 MA cm−2). We show scaling behaviour and good reversibility on these devices, and explore several intermediate resistance states that are accessible during both amorphization and recrystallization pathways. Existence of multiple resistance states, along with ultralow-power switching and scaling capabilities, makes this approach promising in context of low-power memory and neuromorphic computation. PMID:26805748

Lunar phase function at 1064 nm from Lunar Orbiter Laser Altimeter passive and active radiometry

NASA Astrophysics Data System (ADS)

Barker, M. K.; Sun, X.; Mazarico, E.; Neumann, G. A.; Zuber, M. T.; Smith, D. E.

2016-07-01

We present initial calibration and results of passive radiometry collected by the Lunar Orbiter Laser Altimeter onboard the Lunar Reconnaissance Orbiter over the course of 12 months. After correcting for time- and temperature-dependent dark noise and detector responsivity variations, the LOLA passive radiometry measurements are brought onto the absolute radiance scale of the SELENE Spectral Profiler. The resulting photometric precision is estimated to be ∼5%. We leverage the unique ability of LOLA to measure normal albedo to explore the 1064 nm phase function's dependence on various geologic parameters. On a global scale, we find that iron abundance and optical maturity (quantified by FeO and OMAT) are the dominant controlling parameters. Titanium abundance (TiO2), surface roughness on decimeter to decameter scales, and soil thermophysical properties have a smaller effect, but the latter two are correlated with OMAT, indicating that exposure age is the driving force behind their effects in a globally-averaged sense. The phase function also exhibits a dependence on surface slope at ∼300 m baselines, possibly the result of mass wasting exposing immature material and/or less space weathering due to reduced sky visibility. Modeling the photometric function in the Hapke framework, we find that, relative to the highlands, the maria exhibit decreased backscattering, a smaller opposition effect (OE) width, and a smaller OE amplitude. Immature highlands regolith has a higher backscattering fraction and a larger OE width compared to mature highlands regolith. Within the maria, the backscattering fraction and OE width show little dependence on TiO2 and OMAT. Variations in the phase function shape at large phase angles are observed in and around the Copernican-aged Jackson crater, including its dark halo, a putative impact melt deposit. Finally, the phase function of the Reiner Gamma Formation behaves more optically immature than is typical for its composition and OMAT, suggesting the visible-to-near-infrared spectrum and phase function respond differently to the unusual regolith evolution and properties at this location.

Lunar Phase Function at 1064 Nm from Lunar Orbiter Laser Altimeter Passive and Active Radiometry

NASA Technical Reports Server (NTRS)

Barker, M. K.; Sun, X.; Mazarico, E.; Neumann, G. A.; Zuber, M. T.; Smith, D. E.

2016-01-01

We present initial calibration and results of passive radiometry collected by the Lunar Orbiter Laser Al- timeter onboard the Lunar Reconnaissance Orbiter over the course of 12 months. After correcting for time- and temperature-dependent dark noise and detector responsivity variations, the LOLA passive radiometry measurements are brought onto the absolute radiance scale of the SELENE Spectral Profiler. The resulting photometric precision is estimated to be approximately 5%. We leverage the unique ability of LOLA to measure normal albedo to explore the 1064 nm phase function's dependence on various geologic parameters. On a global scale, we find that iron abundance and optical maturity (quantified by FeO and OMAT) are the dominant controlling parameters. Titanium abundance (TiO2 ), surface roughness on decimeter to decameter scales, and soil thermophysical properties have a smaller effect, but the latter two are correlated with OMAT, indicating that exposure age is the driving force behind their effects in a globally-averaged sense. The phase function also exhibits a dependence on surface slope at approximately 300 m baselines, possibly the result of mass wasting exposing immature material and/or less space weathering due to reduced sky visibility. Modeling the photometric function in the Hapke framework, we find that, relative to the highlands, the maria exhibit decreased backscattering, a smaller opposition effect (OE) width, and a smaller OE amplitude. Immature highlands regolith has a higher backscattering fraction and a larger OE width compared to mature highlands regolith. Within the maria, the backscattering fraction and OE width show little dependence on TiO2 and OMAT. Variations in the phase function shape at large phase angles are observed in and around the Copernican-aged Jackson crater, including its dark halo, a putative impact melt deposit. Finally, the phase function of the Reiner Gamma Formation behaves more optically immature than is typical for its composition and OMAT, suggesting the visible-to-near-infrared spectrum and phase function respond differently to the unusual regolith evolution and properties at this location.

Creation of current filaments in the solar corona

NASA Technical Reports Server (NTRS)

Mikic, Z.; Schnack, D. D.; Van Hoven, G.

1989-01-01

It has been suggested that the solar corona is heated by the dissipation of electric currents. The low value of the resistivity requires the magnetic field to have structure at very small length scales if this mechanism is to work. In this paper it is demonstrated that the coronal magnetic field acquires small-scale structure through the braiding produced by smooth, randomly phased, photospheric flows. The current density develops a filamentary structure and grows exponentially in time. Nonlinear processes in the ideal magnetohydrodynamic equations produce a cascade effect, in which the structure introduced by the flow at large length scales is transferred to smaller scales. If this process continues down to the resistive dissipation length scale, it would provide an effective mechanism for coronal heating.

X-ray computed tomography of wood-adhesive bondlines: Attenuation and phase-contrast effects

DOE PAGES

Paris, Jesse L.; Kamke, Frederick A.; Xiao, Xianghui

2015-07-29

Microscale X-ray computed tomography (XCT) is discussed as a technique for identifying 3D adhesive distribution in wood-adhesive bondlines. Visualization and material segmentation of the adhesives from the surrounding cellular structures require sufficient gray-scale contrast in the reconstructed XCT data. Commercial wood-adhesive polymers have similar chemical characteristics and density to wood cell wall polymers and therefore do not provide good XCT attenuation contrast in their native form. Here, three different adhesive types, namely phenol formaldehyde, polymeric diphenylmethane diisocyanate, and a hybrid polyvinyl acetate, are tagged with iodine such that they yield sufficient X-ray attenuation contrast. However, phase-contrast effects at material edgesmore » complicate image quality and segmentation in XCT data reconstructed with conventional filtered backprojection absorption contrast algorithms. A quantitative phase retrieval algorithm, which isolates and removes the phase-contrast effect, was demonstrated. The paper discusses and illustrates the balance between material X-ray attenuation and phase-contrast effects in all quantitative XCT analyses of wood-adhesive bondlines.« less

X-ray computed tomography of wood-adhesive bondlines: Attenuation and phase-contrast effects

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

Paris, Jesse L.; Kamke, Frederick A.; Xiao, Xianghui

Microscale X-ray computed tomography (XCT) is discussed as a technique for identifying 3D adhesive distribution in wood-adhesive bondlines. Visualization and material segmentation of the adhesives from the surrounding cellular structures require sufficient gray-scale contrast in the reconstructed XCT data. Commercial wood-adhesive polymers have similar chemical characteristics and density to wood cell wall polymers and therefore do not provide good XCT attenuation contrast in their native form. Here, three different adhesive types, namely phenol formaldehyde, polymeric diphenylmethane diisocyanate, and a hybrid polyvinyl acetate, are tagged with iodine such that they yield sufficient X-ray attenuation contrast. However, phase-contrast effects at material edgesmore » complicate image quality and segmentation in XCT data reconstructed with conventional filtered backprojection absorption contrast algorithms. A quantitative phase retrieval algorithm, which isolates and removes the phase-contrast effect, was demonstrated. The paper discusses and illustrates the balance between material X-ray attenuation and phase-contrast effects in all quantitative XCT analyses of wood-adhesive bondlines.« less

Effects of the 7-8-year cycle in daily mean air temperature as a cross-scale information transfer

NASA Astrophysics Data System (ADS)

Jajcay, Nikola; Hlinka, Jaroslav; Paluš, Milan

2015-04-01

Using a novel nonlinear time-series analysis method, an information transfer from larger to smaller scales of the air temperature variability has been observed in daily mean surface air temperature (SAT) data from European stations as the influence of the phase of slow oscillatory phenomena with periods around 6-11 years on amplitudes of the variability characterized by smaller temporal scales from a few months to 4-5 years [1]. The strongest effect is exerted by an oscillatory mode with the period close to 8 years and its influence can be seen in 1-2 °C differences of the conditional SAT means taken conditionally on the phase of the 8-year cycle. The size of this effect, however, changes in space and time. The changes in time are studied using sliding window technique, showing that the effect evolves in time, and during the last decades the effect is stronger and significant. Sliding window technique was used along with seasonal division of the data, and it has been found that the cycle is most pronounced in the winter season. Different types of surrogate data are applied in order to establish statistical significance and distinguish the effect of the 7-8-yr cycle from climate variability on shorter time scales. [1] M. Palus, Phys. Rev. Lett. 112 078702 (2014) This study is supported by the Ministry of Education, Youth and Sports of the Czech Republic within the Program KONTAKT II, Project No. LH14001.

Effects of point defect concentrations of the reactive element oxides on the oxidation kinetics of pure Ni and Ni-Cr alloys

NASA Astrophysics Data System (ADS)

Yan, Ruey-Fong

The addition of some reactive element oxides, e.g. Ysb2Osb3 or ZrOsb2, has significant effects, e.g. improvement in scale adhesion and reduction in oxidation rate, on the oxidation behavior of chromia and alumina scale forming alloys at high temperatures. However, there is little agreement about how a small addition of an oxygen-active element can cause such profound effects. It was the goal of this project to study the growth kinetics of an oxide scale when different reactive-element oxides were added to pure Ni and Ni-Cr alloys and, consequently, to aid in clarifying the mechanism of reactive element effects. The oxidation kinetics were measured using a thermogravimetric analysis (TGA) method and the material characterization of oxide scale was conducted. The relationship between point defect structures and oxidation kinetics was discussed. The results in this research showed that Ysb2Osb3 and ZrOsb2 exhibited the reactive element effects on the oxidation behaviors of Ni and Ni-Cr alloys. In addition, the point defect concentrations of the reactive element oxide, Ysb2Osb3, were changed by doping of different valent oxides. The modification of point defect concentrations of the reactive element oxide dispersed phases did change the oxidation kinetics of the pure Ni and Ni-Cr alloys containing Ysb2Osb3. These results indicate that the transport properties of the reactive element oxide dispersed phases are one of the important factors in determining the growth rate of an oxide scale.

Effects of frustration on explosive synchronization

NASA Astrophysics Data System (ADS)

Huang, Xia; Gao, Jian; Sun, Yu-Ting; Zheng, Zhi-Gang; Xu, Can

2016-12-01

In this study, we consider the emergence of explosive synchronization in scale-free networks by considering the Kuramoto model of coupled phase oscillators. The natural frequencies of oscillators are assumed to be correlated with their degrees and frustration is included in the system. This assumption can enhance or delay the explosive transition to synchronization. Interestingly, a de-synchronization phenomenon occurs and the type of phase transition is also changed. Furthermore, we provide an analytical treatment based on a star graph, which resembles that obtained in scale-free networks. Finally, a self-consistent approach is implemented to study the de-synchronization regime. Our findings have important implications for controlling synchronization in complex networks because frustration is a controllable parameter in experiments and a discontinuous abrupt phase transition is always dangerous in engineering in the real world.

Introducing causality violation for improved DPOAE component unmixing

NASA Astrophysics Data System (ADS)

Moleti, Arturo; Sisto, Renata; Shera, Christopher A.

2018-05-01

The DPOAE response consists of the linear superposition of two components, a nonlinear distortion component generated in the overlap region, and a reflection component generated by roughness in the DP resonant region. Due to approximate scaling symmetry, the DPOAE distortion component has approximately constant phase. As the reflection component may be considered as a SFOAE generated by the forward DP traveling wave, it has rapidly rotating phase, relative to that of its source, which is also equal to the phase of the DPOAE distortion component. This different phase behavior permits effective separation of the DPOAE components (unmixing), using time-domain or time-frequency domain filtering. Departures from scaling symmetry imply fluctuations around zero delay of the distortion component, which may seriously jeopardize the accuracy of these filtering techniques. The differential phase-gradient delay of the reflection component obeys causality requirements, i.e., the delay is positive only, and the fine-structure oscillations of amplitude and phase are correlated to each other, as happens for TEOAEs and SFOAEs relative to their stimulus phase. Performing the inverse Fourier (or wavelet) transform of a modified DPOAE complex spectrum, in which a constant phase function is substituted for the measured one, the time (or time-frequency) distribution shows a peak at (exactly) zero delay and long-latency specular symmetric components, with a modified (positive and negative) delay, which is that relative to that of the distortion component in the original response. Component separation, applied to this symmetrized distribution, becomes insensitive to systematic errors associated with violation of the scaling symmetry in specific frequency ranges.

Aperture scaling effects with monolithic periodically poled lithium niobate optical parametric oscillators and generators.

PubMed

Missey, M; Dominic, V; Powers, P; Schepler, K L

2000-02-15

We used elliptical beams to demonstrate aperture scaling effects in nanosecond single-grating and multigrating periodically poled lithium niobate (PPLN) monolithic optical parametric oscillators and generators. Increasing the cavity Fresnel number in single-grating crystals broadened both the beam divergence and the spectral bandwidth. Both effects are explained in terms of the phase-matching geometry. These effects are suppressed when a multigrating PPLN crystal is used because the individual gratings provide small effective subapertures. A flood-pumped multigrating optical parametric generator displayed a low output beam divergence and contained 19 pairs of signal and idler frequencies.

Irreversible opinion spreading on scale-free networks

NASA Astrophysics Data System (ADS)

Candia, Julián

2007-02-01

We study the dynamical and critical behavior of a model for irreversible opinion spreading on Barabási-Albert (BA) scale-free networks by performing extensive Monte Carlo simulations. The opinion spreading within an inhomogeneous society is investigated by means of the magnetic Eden model, a nonequilibrium kinetic model for the growth of binary mixtures in contact with a thermal bath. The deposition dynamics, which is studied as a function of the degree of the occupied sites, shows evidence for the leading role played by hubs in the growth process. Systems of finite size grow either ordered or disordered, depending on the temperature. By means of standard finite-size scaling procedures, the effective order-disorder phase transitions are found to persist in the thermodynamic limit. This critical behavior, however, is absent in related equilibrium spin systems such as the Ising model on BA scale-free networks, which in the thermodynamic limit only displays a ferromagnetic phase. The dependence of these results on the degree exponent is also discussed for the case of uncorrelated scale-free networks.

Cirrus clouds. I - A cirrus cloud model. II - Numerical experiments on the formation and maintenance of cirrus

NASA Technical Reports Server (NTRS)

Starr, D. OC.; Cox, S. K.

1985-01-01

A simplified cirrus cloud model is presented which may be used to investigate the role of various physical processes in the life cycle of a cirrus cloud. The model is a two-dimensional, time-dependent, Eulerian numerical model where the focus is on cloud-scale processes. Parametrizations are developed to account for phase changes of water, radiative processes, and the effects of microphysical structure on the vertical flux of ice water. The results of a simulation of a thin cirrostratus cloud are given. The results of numerical experiments performed with the model are described in order to demonstrate the important role of cloud-scale processes in determining the cloud properties maintained in response to larger scale forcing. The effects of microphysical composition and radiative processes are considered, as well as their interaction with thermodynamic and dynamic processes within the cloud. It is shown that cirrus clouds operate in an entirely different manner than liquid phase stratiform clouds.

Personality and symptom change in treatment-refractory inpatients: evaluation of the phase model of change using Rorschach,TAT, and DSM-IV Axis V.

PubMed

Fowler, J Christopher; Ackerman, Steven J; Speanburg, Stefanie; Bailey, Adrian; Blagys, Matthew; Conklin, Adam C

2004-12-01

In this study, we examined global treatment outcomes during 16 months of intensive, psychodynamic treatment for 77 inpatients suffering from treatment-refractory disorders. Hypotheses based on the phase model of treatment change (Howard, Lueger, Maling, & Martinovich, 1993; Howard, Moras, Brill, Martinovich, & Lutz, 1996) were supported in the study results. Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) Axis V scales assessing behavioral functioning demonstrated large and medium effect size change, whereas stable, enduring personality functioning assessed by psychoanalytic Rorschach scales and the Social Cognition and Object Relations Scale (Westen, 1995) for the Thematic Apperception Test (Murray, 1943) demonstrated small and medium effect size change. We also report assessment of reliable change index and clinical significance. The ecological validity of Rorschach measures is supported by significant validity coefficients (in the hypothesized directions) between implicit measures of personality functioning and behavioral ratings.

Adaptation of a Developmental Test to Accommodate Young Children with Low Vision

ERIC Educational Resources Information Center

Ferreira, Viviana; Albuquerque, Cristina P.

2017-01-01

Introduction: This study analyzed the effects of accommodations for children with low vision in the Griffiths Mental Development Scales--Extended Revised (GMDS-ER). Methods: The sample comprised 25 children with low vision and chronological ages between 28 and 76 months. There were two assessment phases: in the first, the Griffiths Scales were…

A deformation-formulated micromechanics model of the effective Young's modulus and strength of laminated composites containing local ply curvature

NASA Technical Reports Server (NTRS)

Lee, Jong-Won; Harris, Charles E.

1990-01-01

A mathematical model based on the Euler-Bermoulli beam theory is proposed for predicting the effective Young's moduli of piecewise isotropic composite laminates with local ply curvatures in the main load-carrying layers. Strains in corrugated layers, in-phase layers, and out-of-phase layers are predicted for various geometries and material configurations by assuming matrix layers as elastic foundations of different spring constants. The effective Young's moduli measured from corrugated aluminum specimens and aluminum/epoxy specimens with in-phase and out-of-phase wavy patterns coincide very well with the model predictions. Moire fringe analysis of an in-phase specimen and an out-of-phase specimen are also presented, confirming the main assumption of the model related to the elastic constraint due to the matrix layers. The present model is also compared with the experimental results and other models, including the microbuckling models, published in the literature. The results of the present study show that even a very small-scale local ply curvature produces a noticeable effect on the mechanical constitutive behavior of a laminated composite.

Effects of Random Circuit Fabrication Errors on Small Signal Gain and on Output Phase In a Traveling Wave Tube

NASA Astrophysics Data System (ADS)

Rittersdorf, I. M.; Antonsen, T. M., Jr.; Chernin, D.; Lau, Y. Y.

2011-10-01

Random fabrication errors may have detrimental effects on the performance of traveling-wave tubes (TWTs) of all types. A new scaling law for the modification in the average small signal gain and in the output phase is derived from the third order ordinary differential equation that governs the forward wave interaction in a TWT in the presence of random error that is distributed along the axis of the tube. Analytical results compare favorably with numerical results, in both gain and phase modifications as a result of random error in the phase velocity of the slow wave circuit. Results on the effect of the reverse-propagating circuit mode will be reported. This work supported by AFOSR, ONR, L-3 Communications Electron Devices, and Northrop Grumman Corporation.

Evaluation of the Effects of AFFF Inputs on the VIP Biological Nutrient Removal Process and Pass-Through Toxicity. Phase 1A. Volume I.

DTIC Science & Technology

1997-10-01

This report discusses the results of a bench scale study conducted to evaluate the potential inhibitory effects of untreated AFFF wastewater to the...untreated AFFF wastewater to the nitrification process of the Virginia Initiative Plant biological nutrient removal system. Under this testing, bench...scale reactors simulating the nitrification process were loaded at various AFFF concentrations and the influence on the process performance was

New Phenomena in Propagation of Radio Polarizations due to Magnetic Fields on Cosmological Scales

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

Ralston, J.P.; Jain, P.; Nodland, B.

1998-07-01

We discuss a new mechanism which could cause a rotation of polarization of electromagnetic waves due to magnetic fields on cosmological scales. The effect hinges on the geometrical phase of Pancharatnam and Berry, and causes a corkscrew twisting of the plane of polarization. The new effect represents an additional tool that allows possible intergalactic and cosmological magnetic fields to be studied using radio propagation. {copyright} {ital 1998} {ital The American Physical Society}

Physiological-phased kinetic characteristics of microalgae Chlorella vulgaris growth and lipid synthesis considering synergistic effects of light, carbon and nutrients.

PubMed

Liao, Qiang; Chang, Hai-Xing; Fu, Qian; Huang, Yun; Xia, Ao; Zhu, Xun; Zhong, Nianbing

2018-02-01

To comprehensively understand kinetic characteristics of microalgae growth and lipid synthesis in different phases, a phase-feeding strategy was proposed to simultaneously regulate light, carbon and nutrients in adaption, growth and stationary phases of microalgae cultivation. Physiological-phased kinetic characteristics of microalgae Chlorella vulgaris growth and lipid synthesis under synergistic effects of light, carbon and nutrients were investigated, and supply-demand relationships of electrons and energy between light and dark reactions of photosynthesis process were discussed. Finally, the optimized cultivation strategy for microalgae in various phases were obtained, under which the lipid productivity was significantly improved from 130.11 mg/L/d to 163.42 mg/L/d. The study provided some important guidance for the large-scale production of biofuels from microalgae. Copyright © 2017 Elsevier Ltd. All rights reserved.

Scale interaction and arrangement in a turbulent boundary layer perturbed by a wall-mounted cylindrical element

NASA Astrophysics Data System (ADS)

Tang, Zhanqi; Jiang, Nan

2018-05-01

This study reports the modifications of scale interaction and arrangement in a turbulent boundary layer perturbed by a wall-mounted circular cylinder. Hot-wire measurements were executed at multiple streamwise and wall-normal wise locations downstream of the cylindrical element. The streamwise fluctuating signals were decomposed into large-, small-, and dissipative-scale signatures by corresponding cutoff filters. The scale interaction under the cylindrical perturbation was elaborated by comparing the small- and dissipative-scale amplitude/frequency modulation effects downstream of the cylinder element with the results observed in the unperturbed case. It was obtained that the large-scale fluctuations perform a stronger amplitude modulation on both the small and dissipative scales in the near-wall region. At the wall-normal positions of the cylinder height, the small-scale amplitude modulation coefficients are redistributed by the cylinder wake. The similar observation was noted in small-scale frequency modulation; however, the dissipative-scale frequency modulation seems to be independent of the cylindrical perturbation. The phase-relationship observation indicated that the cylindrical perturbation shortens the time shifts between both the small- and dissipative-scale variations (amplitude and frequency) and large-scale fluctuations. Then, the integral time scale dependence of the phase-relationship between the small/dissipative scales and large scales was also discussed. Furthermore, the discrepancy of small- and dissipative-scale time shifts relative to the large-scale motions was examined, which indicates that the small-scale amplitude/frequency leads the dissipative scales.

Far-field phase contrast from orbiting objects: Characterizing progenitors of binary mergers

NASA Astrophysics Data System (ADS)

Matthias, P.; Hofmann, R.

2018-05-01

We propose an idea to determine the size of a binary, composed of two compact stars or black holes, its diffractive power, the distance between components, and the distance to an observer, in exploiting the emergence of intensity contrast by free-space propagation when the phase of coherent light from a very distant background source is affected by diffraction. We assume that this effect can be characterized by the projected real part of an effective refractive index n . Here we model the according two-dimensional exit phase-map by a superposition of two Gaussians. In the extreme far field, phase information is captured by scaling functions which are analyzed here. Both spatial and temporal scanning of the intensity contrast are discussed. While the former mode can be used, e.g., to determine the distance to the observer, the latter allows, e.g., one to measure the overall diffractive power of the binary in terms of the particular dependence of a scaling curve on the projected spatial separation between the binary's components. Both modes of observation may be of relevance in monitoring the progenitor dynamics of binary collapse using radio telescopes.

The Pathophysiology of Decompression Sickness and the Effects of Doppler Detectable Bubbles.

DTIC Science & Technology

1980-12-18

Doppler Ultrasound and a calibrated 6 1 Venous Gas Embol i Scale. C. Electronic Counting of Doppler Bubble Signals 72 £ III. Pulmonary Embolism Studies...IA. Background 75 B. Right Ventricular Systolic Pressure following Gas 81 Embolization and Venous Gas Phase Content IC. Effects of Pulmonary Gas... Embolism on the Development 9 of Limb-Bend Decompression Sickness 1 IV. Gas Phase Formation in Highly Perfused Tissues IA. Renal 9 B. Cerebral 9 1 I I V

Influence of coexisting phases on the surface dilatational viscosity of Langmuir monolayers.

PubMed

Lopez, Juan M; Vogel, Michael J; Hirsa, Amir H

2004-11-01

Monolayer hydrodynamics are usually described in terms of a Newtonian constitutive relationship. However, this macroscopic view fails to account for small-scale coexisting phase domains, which are generally present in the monolayer and appear to have profound macroscopic effects. Here, we provide direct evidence of these effects, consisting of Brewster angle microscopy images of the monolayer, space- and time-resolved interfacial velocity measurements, and comparisons with predictions based on the Navier-Stokes equations together with the classic model for a Newtonian interface.

Impulsive effects of phase-locked pulse pairs on nuclear motion in the electronic ground state

NASA Astrophysics Data System (ADS)

Cina, J. A.; Smith, T. J.

1993-06-01

The nonlinear effects of ultrashort phase-locked electronically resonant pulse pairs on the ground state nuclear motion are investigated theoretically. The pulse-pair propagator, momentum impulse, and displacement are determined in the weak field limit for pulse pairs separated by a time delay short on a nuclear time scale. Possible application to large amplitude vibrational excitation of the 104 cm-1 mode of α-perylene is considered and comparisons are made to other Raman excitation methods.

Phase change paint tests on Rockwell orbiter/tank and orbiter alone configurations (OH3A/OH3B)

NASA Technical Reports Server (NTRS)

Quan, M.; Craig, C.

1974-01-01

Wind tunnel tests were conducted on scale models of the space shuttle orbiter and external tank. The tests were designed to determine the basic heating rate and interference effects on the orbiter-tank configuration and to analyze the effectiveness of the thermal protective system on the reentry vehicle. The phase change paint techniques were used to determine areodynamic heating rates. Oil flow and schlieren photographs were used for flow visualization.

Development of an HPV Educational Protocol for Adolescents

PubMed Central

Wetzel, Caitlin; Tissot, Abbigail; Kollar, Linda M.; Hillard, Paula A.; Stone, Rachel; Kahn, Jessica A.

2007-01-01

Study Objectives To develop an educational protocol about HPV and Pap tests for adolescents, to evaluate the protocol for understandability and clarity, and to evaluate the protocol for its effectiveness in increasing knowledge about HPV. Design In phase 1, investigators and adolescents developed the protocol. In phase 2, adolescents evaluated the protocol qualitatively, investigators evaluated its effectiveness in increasing HPV knowledge in a sample of adolescents, and the protocol was revised. In phase 3, investigators evaluated the effectiveness of the revised protocol in an additional adolescent sample. Setting Urban, hospital-based teen health center. Participants A total of 252 adolescent girls and boys in the three study phases. Main Outcome Measures Pre- and post-protocol knowledge about HPV, measured using a 10- or 11-item scale. Results Scores on the HPV knowledge scale increased significantly (p<.0001) among adolescents who participated in phases 2 and 3 after they received the protocol. Initial differences in scores based on race, insurance type and condom use were not noted post-protocol. Conclusion The protocol significantly increased knowledge scores about HPV in this population, regardless of sociodemographic characteristics and risk behaviors. Effective, developmentally appropriate educational protocols about HPV and Pap tests are particularly important in clinical settings as cervical cancer screening guidelines evolve, HPV DNA testing is integrated into screening protocols, and HPV vaccines become available. In-depth, one-on-one education about HPV may also prevent adverse psychosocial responses and promote healthy sexual and Pap screening behaviors in adolescents with abnormal HPV or Pap test results. Synopsis The investigators developed an educational protocol about HPV and Pap tests and evaluated its effectiveness in increasing knowledge about HPV among adolescents. PMID:17868894

Isolated Liquid Droplet Combustion: Inhibition and Extinction Studies

NASA Technical Reports Server (NTRS)

Dryer, F. L.; Kroenlein, K. G.; Kazakov, A.; Williams, F. A.; Nayagam, V.

2004-01-01

Introduction of fire suppressants to the ambient environment surrounding a heterogeneous diffusion flame may be an inefficient technique for fire safety in systems without buoyant flows. Carbon dioxide substitution for nitrogen diluent leads to significant modifications of the sphero-symmetric burning behavior of isolated n-heptane droplets, partly through increased heat capacity within the gaseous diffusion flame, but mostly because of modifications in spectral radiative coupling in the gas phase. Effects of longer time scale phenomena such as sooting and slow gas-phase/droplet convection remain to be determined. Similar methodologies can be applied to evaluate the effects and efficacy of chemical inhibitors in the liquid and gas phases.

Multi-GPU hybrid programming accelerated three-dimensional phase-field model in binary alloy

NASA Astrophysics Data System (ADS)

Zhu, Changsheng; Liu, Jieqiong; Zhu, Mingfang; Feng, Li

2018-03-01

In the process of dendritic growth simulation, the computational efficiency and the problem scales have extremely important influence on simulation efficiency of three-dimensional phase-field model. Thus, seeking for high performance calculation method to improve the computational efficiency and to expand the problem scales has a great significance to the research of microstructure of the material. A high performance calculation method based on MPI+CUDA hybrid programming model is introduced. Multi-GPU is used to implement quantitative numerical simulations of three-dimensional phase-field model in binary alloy under the condition of multi-physical processes coupling. The acceleration effect of different GPU nodes on different calculation scales is explored. On the foundation of multi-GPU calculation model that has been introduced, two optimization schemes, Non-blocking communication optimization and overlap of MPI and GPU computing optimization, are proposed. The results of two optimization schemes and basic multi-GPU model are compared. The calculation results show that the use of multi-GPU calculation model can improve the computational efficiency of three-dimensional phase-field obviously, which is 13 times to single GPU, and the problem scales have been expanded to 8193. The feasibility of two optimization schemes is shown, and the overlap of MPI and GPU computing optimization has better performance, which is 1.7 times to basic multi-GPU model, when 21 GPUs are used.

Determination of electrostatic force and its characteristics based on phase difference by amplitude modulation atomic force microscopy

NASA Astrophysics Data System (ADS)

Wang, Kesheng; Cheng, Jia; Yao, Shiji; Lu, Yijia; Ji, Linhong; Xu, Dengfeng

2016-12-01

Electrostatic force measurement at the micro/nano scale is of great significance in science and engineering. In this paper, a reasonable way of applying voltage is put forward by taking an electrostatic chuck in a real integrated circuit manufacturing process as a sample, applying voltage in the probe and the sample electrode, respectively, and comparing the measurement effect of the probe oscillation phase difference by amplitude modulation atomic force microscopy. Based on the phase difference obtained from the experiment, the quantitative dependence of the absolute magnitude of the electrostatic force on the tip-sample distance and applied voltage is established by means of theoretical analysis and numerical simulation. The results show that the varying characteristics of the electrostatic force with the distance and voltage at the micro/nano scale are similar to those at the macroscopic scale. Electrostatic force gradually decays with increasing distance. Electrostatic force is basically proportional to the square of applied voltage. Meanwhile, the applicable conditions of the above laws are discussed. In addition, a comparison of the results in this paper with the results of the energy dissipation method shows the two are consistent in general. The error decreases with increasing distance, and the effect of voltage on the error is small.

Effect of blonanserin on cognitive and social function in acute phase Japanese schizophrenia compared with risperidone.

PubMed

Hori, Hikaru; Yamada, Kenji; Kamada, Dan; Shibata, Yuka; Katsuki, Asuka; Yoshimura, Reiji; Nakamura, Jun

2014-01-01

This study aims to determine the effectiveness of blonanserin (BNS) on the cognitive and social functions of patients with schizophrenia compared with risperidone (RIS) during acute-phase (8-week) treatment. A total of 39 schizophrenia inpatients were included in this study. The subjects received either BNS (N=20) or RIS (N=19), and the clinical responses were evaluated periodically. The concomitant use of mood stabilizers was not allowed. Efficacy was assessed with the Positive and Negative Syndrome Scale for schizophrenia. Cognition was assessed using the Brief Assessment of Cognition in Schizophrenia, Japanese-language version. Social function was assessed using the Life Assessment Scale for the Mentally Ill. For both groups, each assessment exhibited a decrease in the mean change from baseline on the Positive and Negative Syndrome Scale. The depression subscale was significantly improved in the BNS group compared with the RIS group at 8 weeks after administration. BNS improved verbal fluency and executive function (cognitive function) and daily living and work skills (social function). Compared with the RIS group, BNS was observed to improve daily living. BNS may improve psychotic symptoms, cognitive function, and daily living in patients with acute-phase schizophrenia. BNS may be superior to RIS in the improvement of daily living.

Effect of blonanserin on cognitive and social function in acute phase Japanese schizophrenia compared with risperidone

PubMed Central

Hori, Hikaru; Yamada, Kenji; Kamada, Dan; Shibata, Yuka; Katsuki, Asuka; Yoshimura, Reiji; Nakamura, Jun

2014-01-01

Background This study aims to determine the effectiveness of blonanserin (BNS) on the cognitive and social functions of patients with schizophrenia compared with risperidone (RIS) during acute-phase (8-week) treatment. Methods A total of 39 schizophrenia inpatients were included in this study. The subjects received either BNS (N=20) or RIS (N=19), and the clinical responses were evaluated periodically. The concomitant use of mood stabilizers was not allowed. Efficacy was assessed with the Positive and Negative Syndrome Scale for schizophrenia. Cognition was assessed using the Brief Assessment of Cognition in Schizophrenia, Japanese-language version. Social function was assessed using the Life Assessment Scale for the Mentally Ill. Results For both groups, each assessment exhibited a decrease in the mean change from baseline on the Positive and Negative Syndrome Scale. The depression subscale was significantly improved in the BNS group compared with the RIS group at 8 weeks after administration. BNS improved verbal fluency and executive function (cognitive function) and daily living and work skills (social function). Compared with the RIS group, BNS was observed to improve daily living. Conclusion BNS may improve psychotic symptoms, cognitive function, and daily living in patients with acute-phase schizophrenia. BNS may be superior to RIS in the improvement of daily living. PMID:24707178

Time-resolved quantitative-phase microscopy of laser-material interactions using a wavefront sensor.

PubMed

Gallais, Laurent; Monneret, Serge

2016-07-15

We report on a simple and efficient technique based on a wavefront sensor to obtain time-resolved amplitude and phase images of laser-material interactions. The main interest of the technique is to obtain quantitative self-calibrated phase measurements in one shot at the femtosecond time-scale, with high spatial resolution. The technique is used for direct observation and quantitative measurement of the Kerr effect in a fused silica substrate and free electron generation by photo-ionization processes in an optical coating.

Theory of disordered unconventional superconductors

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

Keles, A.; Andreev, A. V.; Spivak, B. Z., E-mail: spivak@uw.edu

In contrast to conventional s-wave superconductivity, unconventional (e.g., p- or d-wave) superconductivity is strongly suppressed even by relatively weak disorder. Upon approaching the superconductormetal transition, the order parameter amplitude becomes increasingly inhomogeneous, leading to effective granularity and a phase ordering transition described by the Mattis model of spin glasses. One consequence of this is that at sufficiently low temperatures, between the clean unconventional superconducting and the diffusive metallic phases, there is necessarily an intermediate superconducting phase that exhibits s-wave symmetry on macroscopic scales.

FIBER AND INTEGRATED OPTICS, LASER APPLICATIONS, AND OTHER PROBLEMS IN QUANTUM ELECTRONICS: Numerical simulation of an unstable ring resonator with a Fourier phase corrector

NASA Astrophysics Data System (ADS)

Kliment'ev, S. I.; Kuprenyuk, V. I.; Lyubimov, V. V.; Sherstobitov, V. E.

1989-04-01

The results are given of calculations of the parameters of an unstable ring resonator with an internal angular selector based on a Fourier phase corrector. It is shown that the use of such a selector makes it possible to compensate partly for the effects of small-scale phase inhomogeneities and to reduce also the influence of the edge diffraction on the structure of the field in a resonator.

Polymer Dispersed Liquid Crystal Displays

NASA Astrophysics Data System (ADS)

Doane, J. William

The following sections are included: * INTRODUCTION AND HISTORICAL DEVELOPMENT * PDLC MATERIALS PREPARATION * Polymerization induced phase separation (PIPS) * Thermally induced phase separation (TIPS) * Solvent induced phase separation (SIPS) * Encapsulation (NCAP) * RESPONSE VOLTAGE * Dielectric and resistive effects * Radial configuration * Bipolar configuration * Other director configurations * RESPONSE TIME * DISPLAY CONTRAST * Light scattering and index matching * Incorporation of dyes * Contrast measurements * PDLC DISPLAY DEVICES AND INNOVATIONS * Reflective direct view displays * Large-scale, flexible displays * Switchable windows * Projection displays * High definition spatial light modulator * Haze-free PDLC shutters: wide angle view displays * ENVIRONMENTAL STABILITY * ACKNOWLEDGEMENTS * REFERENCES

Multi-scale diffuse interface modeling of multi-component two-phase flow with partial miscibility

NASA Astrophysics Data System (ADS)

Kou, Jisheng; Sun, Shuyu

2016-08-01

In this paper, we introduce a diffuse interface model to simulate multi-component two-phase flow with partial miscibility based on a realistic equation of state (e.g. Peng-Robinson equation of state). Because of partial miscibility, thermodynamic relations are used to model not only interfacial properties but also bulk properties, including density, composition, pressure, and realistic viscosity. As far as we know, this effort is the first time to use diffuse interface modeling based on equation of state for modeling of multi-component two-phase flow with partial miscibility. In numerical simulation, the key issue is to resolve the high contrast of scales from the microscopic interface composition to macroscale bulk fluid motion since the interface has a nanoscale thickness only. To efficiently solve this challenging problem, we develop a multi-scale simulation method. At the microscopic scale, we deduce a reduced interfacial equation under reasonable assumptions, and then we propose a formulation of capillary pressure, which is consistent with macroscale flow equations. Moreover, we show that Young-Laplace equation is an approximation of this capillarity formulation, and this formulation is also consistent with the concept of Tolman length, which is a correction of Young-Laplace equation. At the macroscopical scale, the interfaces are treated as discontinuous surfaces separating two phases of fluids. Our approach differs from conventional sharp-interface two-phase flow model in that we use the capillary pressure directly instead of a combination of surface tension and Young-Laplace equation because capillarity can be calculated from our proposed capillarity formulation. A compatible condition is also derived for the pressure in flow equations. Furthermore, based on the proposed capillarity formulation, we design an efficient numerical method for directly computing the capillary pressure between two fluids composed of multiple components. Finally, numerical tests are carried out to verify the effectiveness of the proposed multi-scale method.

Multi-scale diffuse interface modeling of multi-component two-phase flow with partial miscibility

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

Kou, Jisheng; Sun, Shuyu, E-mail: shuyu.sun@kaust.edu.sa; School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an 710049

2016-08-01

In this paper, we introduce a diffuse interface model to simulate multi-component two-phase flow with partial miscibility based on a realistic equation of state (e.g. Peng–Robinson equation of state). Because of partial miscibility, thermodynamic relations are used to model not only interfacial properties but also bulk properties, including density, composition, pressure, and realistic viscosity. As far as we know, this effort is the first time to use diffuse interface modeling based on equation of state for modeling of multi-component two-phase flow with partial miscibility. In numerical simulation, the key issue is to resolve the high contrast of scales from themore » microscopic interface composition to macroscale bulk fluid motion since the interface has a nanoscale thickness only. To efficiently solve this challenging problem, we develop a multi-scale simulation method. At the microscopic scale, we deduce a reduced interfacial equation under reasonable assumptions, and then we propose a formulation of capillary pressure, which is consistent with macroscale flow equations. Moreover, we show that Young–Laplace equation is an approximation of this capillarity formulation, and this formulation is also consistent with the concept of Tolman length, which is a correction of Young–Laplace equation. At the macroscopical scale, the interfaces are treated as discontinuous surfaces separating two phases of fluids. Our approach differs from conventional sharp-interface two-phase flow model in that we use the capillary pressure directly instead of a combination of surface tension and Young–Laplace equation because capillarity can be calculated from our proposed capillarity formulation. A compatible condition is also derived for the pressure in flow equations. Furthermore, based on the proposed capillarity formulation, we design an efficient numerical method for directly computing the capillary pressure between two fluids composed of multiple components. Finally, numerical tests are carried out to verify the effectiveness of the proposed multi-scale method.« less

The Effect of Ocean Currents on Sea Surface Temperature Anomalies

NASA Technical Reports Server (NTRS)

Stammer, Detlef; Leeuwenburgh, Olwijn

2000-01-01

We investigate regional and global-scale correlations between observed anomalies in sea surface temperature and height. A strong agreement between the two fields is found over a broad range of latitudes for different ocean basins. Both time-longitude plots and wavenumber-frequency spectra suggest an advective forcing of SST anomalies by a first-mode baroclinic wave field on spatial scales down to 400 km and time scales as short as 1 month. Even though the magnitude of the mean background temperature gradient is determining for the effectiveness of the forcing, there is no obvious seasonality that can be detected in the amplitudes of SST anomalies. Instead, individual wave signatures in the SST can in some cases be followed over periods of two years. The phase relationship between SST and SSH anomalies is dependent upon frequency and wavenumber and displays a clear decrease of the phase lag toward higher latitudes where the two fields come into phase at low frequencies. Estimates of the damping coefficient are larger than generally obtained for a purely atmospheric feedback. From a global frequency spectrum a damping time scale of 2-3 month was found. Regionally results are very variable and range from 1 month near strong currents to 10 month at low latitudes and in the sub-polar North Atlantic. Strong agreement is found between the first global EOF modes of 10 day averaged and spatially smoothed SST and SSH grids. The accompanying time series display low frequency oscillations in both fields.

Phase of Illness in palliative care: Cross-sectional analysis of clinical data from community, hospital and hospice patients

PubMed Central

Mather, Harriet; Guo, Ping; Firth, Alice; Davies, Joanna M; Sykes, Nigel; Landon, Alison; Murtagh, Fliss EM

2017-01-01

Background: Phase of Illness describes stages of advanced illness according to care needs of the individual, family and suitability of care plan. There is limited evidence on its association with other measures of symptoms, and health-related needs, in palliative care. Aims: The aims of the study are as follows. (1) Describe function, pain, other physical problems, psycho-spiritual problems and family and carer support needs by Phase of Illness. (2) Consider strength of associations between these measures and Phase of Illness. Design and setting: Secondary analysis of patient-level data; a total of 1317 patients in three settings. Function measured using Australia-modified Karnofsky Performance Scale. Pain, other physical problems, psycho-spiritual problems and family and carer support needs measured using items on Palliative Care Problem Severity Scale. Results: Australia-modified Karnofsky Performance Scale and Palliative Care Problem Severity Scale items varied significantly by Phase of Illness. Mean function was highest in stable phase (65.9, 95% confidence interval = 63.4–68.3) and lowest in dying phase (16.6, 95% confidence interval = 15.3–17.8). Mean pain was highest in unstable phase (1.43, 95% confidence interval = 1.36–1.51). Multinomial regression: psycho-spiritual problems were not associated with Phase of Illness (χ2 = 2.940, df = 3, p = 0.401). Family and carer support needs were greater in deteriorating phase than unstable phase (odds ratio (deteriorating vs unstable) = 1.23, 95% confidence interval = 1.01–1.49). Forty-nine percent of the variance in Phase of Illness is explained by Australia-modified Karnofsky Performance Scale and Palliative Care Problem Severity Scale. Conclusion: Phase of Illness has value as a clinical measure of overall palliative need, capturing additional information beyond Australia-modified Karnofsky Performance Scale and Palliative Care Problem Severity Scale. Lack of significant association between psycho-spiritual problems and Phase of Illness warrants further investigation. PMID:28812945

Characteristics of lead corrosion scales formed during drinking water distribution and their potential influence on the release of lead and other contaminants.

PubMed

Kim, Eun Jung; Herrera, Jose E

2010-08-15

Destabilization of the corrosion scale present in lead pipes used in drinking water distribution systems is currently considered a major problem for municipalities serviced in part by lead pipes. Although several lead corrosion strategies have been deployed with success, a clear understanding of the chemistry of corrosion products present in the scale is needed for an effective lead control. This contribution focuses on a comprehensive characterization of the layers present in the corrosion scale formed on the inner surfaces of lead pipes used in the drinking water distribution system of the City on London, ON, Canada. Solid corrosion products were characterized using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Toxic elements accumulated in the corrosion scale were also identified using inductively coupled plasma (ICP) spectrometry after acid digestion. Based on the XRD results, hydrocerussite was identified as the major lead crystalline corrosion phase in most of the pipes sampled, while cerussite was observed as the main crystalline component only in a few cases. Lead oxides including PbO(2) and Pb(3)O(4) were also observed in the inner layers of the corrosion scale. The presence of these highly oxidized lead species is rationalized in terms of the lead(II) carbonate phase transforming into lead(IV) oxide through an intermediate Pb(3)O(4) (2Pb(II)O x Pb(IV)O(2)) phase. In addition to lead corrosion products, an amorphous aluminosilicate phase was also identified in the corrosion scale. Its concentration is particularly high at the outer surface layers. Accumulation of toxic contaminants such as As, V, Sb, Cu, and Cr was observed in the corrosion scales, together with a strong correlation between arsenic accumulation and aluminum concentration.

The large-scale modulation of cosmic rays in mid-1982: Its dependence on heliospheric longitude and radius

NASA Technical Reports Server (NTRS)

Pyle, K. R.; Simpson, J. A.

1985-01-01

Near solar maximum, a series of large radial solar wind shocks in June and July 1982 provided a unique opportunity to study the solar modulation of galactic cosmic rays with an array of spacecraft widely separated both in heliocentric radius and longitude. By eliminating hysteresis effects it is possible to begin to separate radial and azimuthal effects in the outer heliosphere. On the large scale, changes in modulation (both the increasing and recovery phases) propagate outward at close to the solar wind velocity, except for the near-term effects of solar wind shocks, which may propagate at a significantly higher velocity. In the outer heliosphere, azimuthal effects are small in comparison with radial effects for large-scale modulation at solar maximum.

Pore-scale mechanisms of gas flow in tight sand reservoirs

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

Silin, D.; Kneafsey, T.J.; Ajo-Franklin, J.B.

2010-11-30

Tight gas sands are unconventional hydrocarbon energy resource storing large volume of natural gas. Microscopy and 3D imaging of reservoir samples at different scales and resolutions provide insights into the coaredo not significantly smaller in size than conventional sandstones, the extremely dense grain packing makes the pore space tortuous, and the porosity is small. In some cases the inter-granular void space is presented by micron-scale slits, whose geometry requires imaging at submicron resolutions. Maximal Inscribed Spheres computations simulate different scenarios of capillary-equilibrium two-phase fluid displacement. For tight sands, the simulations predict an unusually low wetting fluid saturation threshold, at whichmore » the non-wetting phase becomes disconnected. Flow simulations in combination with Maximal Inscribed Spheres computations evaluate relative permeability curves. The computations show that at the threshold saturation, when the nonwetting fluid becomes disconnected, the flow of both fluids is practically blocked. The nonwetting phase is immobile due to the disconnectedness, while the permeability to the wetting phase remains essentially equal to zero due to the pore space geometry. This observation explains the Permeability Jail, which was defined earlier by others. The gas is trapped by capillarity, and the brine is immobile due to the dynamic effects. At the same time, in drainage, simulations predict that the mobility of at least one of the fluids is greater than zero at all saturations. A pore-scale model of gas condensate dropout predicts the rate to be proportional to the scalar product of the fluid velocity and pressure gradient. The narrowest constriction in the flow path is subject to the highest rate of condensation. The pore-scale model naturally upscales to the Panfilov's Darcy-scale model, which implies that the condensate dropout rate is proportional to the pressure gradient squared. Pressure gradient is the greatest near the matrix-fracture interface. The distinctive two-phase flow properties of tight sand imply that a small amount of gas condensate can seriously affect the recovery rate by blocking gas flow. Dry gas injection, pressure maintenance, or heating can help to preserve the mobility of gas phase. A small amount of water can increase the mobility of gas condensate.« less

Nonaqueous Phase Liquid Dissolution in Porous Media: Multi-Scale Effects of Multi-Component Dissolution Kinetics on Cleanup Time

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

McNab, W; Ezzedine, S; Detwiler, R

2007-02-26

Industrial organic solvents such as trichloroethylene (TCE) and tetrachloroethylene (PCE) constitute a principal class of groundwater contaminants. Cleanup of groundwater plume source areas associated with these compounds is problematic, in part, because the compounds often exist in the subsurface as dense nonaqueous phase liquids (DNAPLs). Ganglia (or 'blobs') of DNAPL serve as persistent sources of contaminants that are difficult to locate and remediate (e.g. Fenwick and Blunt, 1998). Current understanding of the physical and chemical processes associated with dissolution of DNAPLs in the subsurface is incomplete and yet is critical for evaluating long-term behavior of contaminant migration, groundwater cleanup, andmore » the efficacy of source area cleanup technologies. As such, a goal of this project has been to contribute to this critical understanding by investigating the multi-phase, multi-component physics of DNAPL dissolution using state-of-the-art experimental and computational techniques. Through this research, we have explored efficient and accurate conceptual and numerical models for source area contaminant transport that can be used to better inform the modeling of source area contaminants, including those at the LLNL Superfund sites, to re-evaluate existing remediation technologies, and to inspire or develop new remediation strategies. The problem of DNAPL dissolution in natural porous media must be viewed in the context of several scales (Khachikian and Harmon, 2000), including the microscopic level at which capillary forces, viscous forces, and gravity/buoyancy forces are manifested at the scale of individual pores (Wilson and Conrad, 1984; Chatzis et al., 1988), the mesoscale where dissolution rates are strongly influenced by the local hydrodynamics, and the field-scale. Historically, the physico-chemical processes associated with DNAPL dissolution have been addressed through the use of lumped mass transfer coefficients which attempt to quantify the dissolution rate in response to local dissolved-phase concentrations distributed across the source area using a volume-averaging approach (Figure 1). The fundamental problem with the lumped mass transfer parameter is that its value is typically derived empirically through column-scale experiments that combine the effects of pore-scale flow, diffusion, and pore-scale geometry in a manner that does not provide a robust theoretical basis for upscaling. In our view, upscaling processes from the pore-scale to the field-scale requires new computational approaches (Held and Celia, 2001) that are directly linked to experimental studies of dissolution at the pore scale. As such, our investigation has been multi-pronged, combining theory, experiments, numerical modeling, new data analysis approaches, and a synthesis of previous studies (e.g. Glass et al, 2001; Keller et al., 2002) aimed at quantifying how the mechanisms controlling dissolution at the pore-scale control the long-term dissolution of source areas at larger scales.« less

Symmetry energy effects on the mixed hadron-quark phase at high baryon density

NASA Astrophysics Data System (ADS)

di Toro, M.; Liu, B.; Greco, V.; Baran, V.; Colonna, M.; Plumari, S.

2011-01-01

The phase transition of hadronic to quark matter at high baryon and isospin density is analyzed. Relativistic mean-field models are used to describe hadronic matter, and the MIT bag model is adopted for quark matter. The boundaries of the mixed phase and the related critical points for symmetric and asymmetric matter are obtained. Due to the different symmetry term in the two phases, isospin effects appear to be rather significant. With increasing isospin asymmetry the binodal transition line of the (T,ρB) diagram is lowered to a region accessible through heavy-ion collisions in the energy range of the new planned facilities (e.g., the FAIR/NICA projects). Some observable effects are suggested, in particular an isospin distillation mechanism with a more isospin asymmetric quark phase, to be seen in charged meson yield ratios, and an onset of quark number scaling of the meson-baryon elliptic flows. The presented isospin effects on the mixed phase appear to be robust with respect to even large variations of the poorly known symmetry term at high baryon density in the hadron phase. The dependence of the results on a suitable treatment of isospin contributions in effective QCD Lagrangian approaches, at the level of explicit isovector parts and/or quark condensates, is discussed.

Experimental evidence of stress-field-induced selection of variants in Ni-Mn-Ga ferromagnetic shape-memory alloys

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

Wang, Y. D.; Key Laboratory for Anisotropy and Texture of Materials; Brown, D. W.

2007-05-01

The in situ time-of-flight neutron-diffraction measurements captured well the martensitic transformation behavior of the Ni-Mn-Ga ferromagnetic shape-memory alloys under uniaxial stress fields. We found that a small uniaxial stress applied during phase transformation dramatically disturbed the distribution of variants in the product phase. The observed changes in the distributions of variants may be explained by considering the role of the minimum distortion energy of the Bain transformation in the effective partition among the variants belonging to the same orientation of parent phase. It was also found that transformation kinetics under various stress fields follows the scale law. The present investigationsmore » provide the fundamental approach for scaling the evolution of microstructures in martensitic transitions, which is of general interest to the condensed matter community.« less

A CSF-SPH method for simulating drainage and imbibition at pore-scale resolution while tracking interfacial areas

NASA Astrophysics Data System (ADS)

Sivanesapillai, Rakulan; Falkner, Nadine; Hartmaier, Alexander; Steeb, Holger

2016-09-01

We present a conservative smoothed particle hydrodynamics (SPH) model to study the flow of multiple, immiscible fluid phases in porous media using direct pore-scale simulations. Particular focus is put on continuously tracking the evolution of interfacial areas, which are considered to be important morphological quantities affecting multiphase transport in porous media. In addition to solving the Navier-Stokes equations, the model accounts for the effects of capillarity at interfaces and contact lines. This is done by means of incorporating the governing interfacial mass and momentum balances using the continuum surface force (CSF) method, thus rendering model calibration routines unnecessary and minimizing the set of constitutive and kinematic assumptions. We address the application of boundary conditions at rigid solid surfaces and study the predictive capability of the model as well as optimal choices for numerical parameters using an extensive model validation procedure. We demonstrate the applicability of the model to simulate multiphase flows involving partial wettability, dynamic effects, large density ratios (up to 1000), large viscosity ratios (up to 100), as well as fragmentation and coalescence of fluid phases. The model is used to study the evolution of fluid-fluid interfacial areas during saturation-controlled primary drainage and main imbibition of heterogeneous pore spaces at low capillary numbers. A variety of pore-scale effects, such as wetting phase entrapment and fragmentation due to snap-off, are observed. Specific fluid-fluid interfacial area is observed to monotonically increase during primary drainage and hysteretic effects are apparent during main imbibition.

Effects of blending of desalinated and conventionally treated surface water on iron corrosion and its release from corroding surfaces and pre-existing scales.

PubMed

Liu, Haizhou; Schonberger, Kenneth D; Peng, Ching-Yu; Ferguson, John F; Desormeaux, Erik; Meyerhofer, Paul; Luckenbach, Heidi; Korshin, Gregory V

2013-07-01

This study examined effects of blending desalinated water with conventionally treated surface water on iron corrosion and release from corroding metal surfaces and pre-existing scales exposed to waters having varying fractions of desalinated water, alkalinities, pH values and orthophosphate levels. The presence of desalinated water resulted in markedly decreased 0.45 μm-filtered soluble iron concentrations. However, higher fractions of desalinated water in the blends were also associated with more fragile corroding surfaces, lower retention of iron oxidation products and release of larger iron particles in the bulk water. SEM, XRD and XANES data showed that in surface water, a dense layer of amorphous ferrihydrite phase predominated in the corrosion products. More crystalline surface phases developed in the presence of desalinated water. These solid phases transformed from goethite to lepidocrocite with increased fraction of desalinated water. These effects are likely to result from a combination of chemical parameters, notably variations of the concentrations of natural organic matter, calcium, chloride and sulfate when desalinated and conventionally treated waters are blended. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of phase proprioceptive training on balance in patients with chronic stroke.

PubMed

Chae, Seung Hun; Kim, You Lim; Lee, Suk Min

2017-05-01

[Purpose] This study aimed to investigate the effect of phase proprioceptive training on balance in patients with chronic stroke. [Subjects and Methods] Participants included 30 patients with stroke who were randomly assigned to the proprioceptive training group (n=15) or control group (n=15). Participants in the proprioceptive training group underwent proprioceptive training and received general physical therapy each for a total of 20 thirty-minute sessions, five times per week, during a period of four weeks; the control group received general physical therapy for a total of 20 sixty-minute sessions, five times per week, during a period of four weeks. [Results] All participants were evaluated with the Berg Balance Scale, Timed Up and Go (TUG) test, and Activities-specific Balance Confidence (ABC) Scale instrument before and after intervention. After training, the differences in BBS, TUG, and ABC scores in the proprioceptive group were significantly greater than those in the control group. [Conclusion] In conclusion, proprioceptive training was effective on balance ability. Therefore, proprioceptive training may be efficient when combining general physical therapy with phase proprioceptive training for patients with impairments of balance. Further research is needed to investigate proprioceptive training methods.

The Influence of Multi-Scale Stratal Architecture on Multi-Phase Flow

NASA Astrophysics Data System (ADS)

Soltanian, M.; Gershenzon, N. I.; Ritzi, R. W.; Dominic, D.; Ramanathan, R.

2012-12-01

Geological heterogeneity affects flow and transport in porous media, including the migration and entrapment patterns of oil, and efforts for enhanced oil recovery. Such effects are only understood through their relation to a hierarchy of reservoir heterogeneities over a range of scales. Recent work on modern rivers and ancient sediments has led to a conceptual model of the hierarchy of fluvial forms within channel-belts of gravelly braided rivers, and a quantitative model for the corresponding scales of heterogeneity within the stratal architecture (e.g. [Lunt et al (2004) Sedimentology, 51 (3), 377]). In related work, a three-dimensional digital model was developed which represents these scales of fluvial architecture, the associated spatial distribution of permeability, and the connectivity of high-permeability pathways across the different scales of the stratal hierarchy [Ramanathan et al, (2010) Water Resour. Res., 46, W04515; Guin et al, (2010) Water Resour. Res., 46, W04516]. In the present work we numerically examine three-phase fluid flow (water-oil-gas) incorporating the multi-scale model for reservoir heterogeneity spanning the scales from 10^-1 to 10^3 meters. Comparison with results of flow in a reservoir with homogeneous permeability is made showing essentially different flow dynamics.

Solution of the Eshelby problem in gradient elasticity for multilayer spherical inclusions

NASA Astrophysics Data System (ADS)

Volkov-Bogorodskii, D. B.; Lurie, S. A.

2016-03-01

We consider gradient models of elasticity which permit taking into account the characteristic scale parameters of the material. We prove the Papkovich-Neuber theorems, which determine the general form of the gradient solution and the structure of scale effects. We derive the Eshelby integral formula for the gradient moduli of elasticity, which plays the role of the closing equation in the self-consistent three-phase method. In the gradient theory of deformations, we consider the fundamental Eshelby-Christensen problem of determining the effective elastic properties of dispersed composites with spherical inclusions; the exact solution of this problem for classical models was obtained in 1976. This paper is the first to present the exact analytical solution of the Eshelby-Christensen problem for the gradient theory, which permits estimating the influence of scale effects on the stress state and the effective properties of the dispersed composites under study.We also analyze the influence of scale factors.

Toward direct pore-scale modeling of three-phase displacements

NASA Astrophysics Data System (ADS)

Mohammadmoradi, Peyman; Kantzas, Apostolos

2017-12-01

A stable spreading film between water and gas can extract a significant amount of bypassed non-aqueous phase liquid (NAPL) through immiscible three-phase gas/water injection cycles. In this study, the pore-scale displacement mechanisms by which NAPL is mobilized are incorporated into a three-dimensional pore morphology-based model under water-wet and capillary equilibrium conditions. The approach is pixel-based and the sequence of invasions is determined by the fluids' connectivity and the threshold capillary pressure of the advancing interfaces. In addition to the determination of three-phase spatial saturation profiles, residuals, and capillary pressure curves, dynamic finite element simulations are utilized to predict the effective permeabilities of the rock microtomographic images as reasonable representations of the geological formations under study. All the influential features during immiscible fluid flow in pore-level domains including wetting and spreading films, saturation hysteresis, capillary trapping, connectivity, and interface development strategies are taken into account. The capabilities of the model are demonstrated by the successful prediction of saturation functions for Berea sandstone and the accurate reconstruction of three-phase fluid occupancies through a micromodel.

Large-scale Chromosomal Movements During Interphase Progression in Drosophila

PubMed Central

Csink, Amy K.; Henikoff, Steven

1998-01-01

We examined the effect of cell cycle progression on various levels of chromosome organization in Drosophila. Using bromodeoxyuridine incorporation and DNA quantitation in combination with fluorescence in situ hybridization, we detected gross chromosomal movements in diploid interphase nuclei of larvae. At the onset of S-phase, an increased separation was seen between proximal and distal positions of a long chromsome arm. Progression through S-phase disrupted heterochromatic associations that have been correlated with gene silencing. Additionally, we have found that large-scale G1 nuclear architecture is continually dynamic. Nuclei display a Rabl configuration for only ∼2 h after mitosis, and with further progression of G1-phase can establish heterochromatic interactions between distal and proximal parts of the chromosome arm. We also find evidence that somatic pairing of homologous chromosomes is disrupted during S-phase more rapidly for a euchromatic than for a heterochromatic region. Such interphase chromosome movements suggest a possible mechanism that links gene regulation via nuclear positioning to the cell cycle: delayed maturation of heterochromatin during G1-phase delays establishment of a silent chromatin state. PMID:9763417

Modeling Physical Processes at the Nanoscale—Insight into Self-Organization of Small Systems (abstract)

NASA Astrophysics Data System (ADS)

Proykova, Ana

2009-04-01

Essential contributions have been made in the field of finite-size systems of ingredients interacting with potentials of various ranges. Theoretical simulations have revealed peculiar size effects on stability, ground state structure, phases, and phase transformation of systems confined in space and time. Models developed in the field of pure physics (atomic and molecular clusters) have been extended and successfully transferred to finite-size systems that seem very different—small-scale financial markets, autoimmune reactions, and social group reactions to advertisements. The models show that small-scale markets diverge unexpectedly fast as a result of small fluctuations; autoimmune reactions are sequences of two discontinuous phase transitions; and social groups possess critical behavior (social percolation) under the influence of an external field (advertisement). Some predicted size-dependent properties have been experimentally observed. These findings lead to the hypothesis that restrictions on an object's size determine the object's total internal (configuration) and external (environmental) interactions. Since phases are emergent phenomena produced by self-organization of a large number of particles, the occurrence of a phase in a system containing a small number of ingredients is remarkable.

Validation and Simulation of Ares I Scale Model Acoustic Test - 3 - Modeling and Evaluating the Effect of Rainbird Water Deluge Inclusion

NASA Technical Reports Server (NTRS)

Strutzenberg, Louise L.; Putman, Gabriel C.

2011-01-01

The Ares I Scale Model Acoustics Test (ASMAT) is a series of live-fire tests of scaled rocket motors meant to simulate the conditions of the Ares I launch configuration. These tests have provided a well documented set of high fidelity measurements useful for validation including data taken over a range of test conditions and containing phenomena like Ignition Over-Pressure and water suppression of acoustics. Building on dry simulations of the ASMAT tests with the vehicle at 5 ft. elevation (100 ft. real vehicle elevation), wet simulations of the ASMAT test setup have been performed using the Loci/CHEM computational fluid dynamics software to explore the effect of rainbird water suppression inclusion on the launch platform deck. Two-phase water simulation has been performed using an energy and mass coupled lagrangian particle system module where liquid phase emissions are segregated into clouds of virtual particles and gas phase mass transfer is accomplished through simple Weber number controlled breakup and boiling models. Comparisons have been performed to the dry 5 ft. elevation cases, using configurations with and without launch mounts. These cases have been used to explore the interaction between rainbird spray patterns and launch mount geometry and evaluate the acoustic sound pressure level knockdown achieved through above-deck rainbird deluge inclusion. This comparison has been anchored with validation from live-fire test data which showed a reduction in rainbird effectiveness with the presence of a launch mount.

Prostate Cancer Prevention Through Induction of Phase 2 Enzymes

DTIC Science & Technology

2001-04-01

enzymes. During our Phase I Award, we identified sulforaphane as the most potent inducer of carcinogen defenses in the prostate cell. We have...characterized global effects of sulforaphane in prostate cancer cell lines using cDNA microarray technology that allows large-scale determination of changes...of sulforaphane ) and decreased risk of prostate cancer. These findings argue strongly for a preventive intervention trial involving supplementation

Assessment of the factors affecting protective alumina formation under hot corrosion conditions

NASA Astrophysics Data System (ADS)

Task, Michael Nathan

In this study, the influence of microstructure, composition, and phase constitution on the Type I (900°C) and Type II (700°C) hot corrosion resistance of MCrAlY and β-NiAl base alloys was investigated. The Type II hot corrosion resistance of MCrAlY alloys is generally enhanced by microstructural refinement. This can be attributed to the more rapid establishment of a protective Al2O3-rich scale due to the higher density of short-circuit diffusion paths for Al (phase boundaries). However, it was shown that for a given bulk composition, the compositions of the individual phases is also extremely important. If one phase is lean in an element which is highly beneficial from a hot corrosion standpoint, e.g., Cr, Type II hot corrosion resistance is quite poor, regardless of the microstructural scale. In addition, coarse reactive-element-rich phases, which are commonly found in MCrAlY alloys, can be incorporated into the thermally grown Al2O 3 scale and act as initiation sites for Type II attack. This stresses the importance of reactive element content and distribution in MCrAlY coatings. During Type I hot corrosion exposure of β-Ni-36Al (at. %) base alloys, the incubation stage is greatly extended by the addition of 5% Pt, Co, or Cr. In each case, the beneficial effects can be linked to an enhanced ability to rapidly form a protective Al2O3 scale, and to heal this scale when it sustains damage during exposure. With regard to Type II hot corrosion, individual additions of 5 at. % Pt or Cr are beneficial, largely for the same reason; however, additions of 5 at. % Co and co-additions of 5 at. % Pt + 5 at. % Cr result in a decrease in the duration of the incubation stage. Subsurface phase transformations that occur in the latter systems prevent the alloy from maintaining the growth of the Al2O3 scale. This mechanism is discussed in detail. Finally, the influence of alloy composition and exposure environment on the kinetics of the θ→α Al2O3 transformation in scales grown on β-NiAl alloys at 900°C was thoroughly investigated. The relative importance of the kinetics of this transformation during Type I hot corrosion exposure is discussed.

Intermittent strong transport of the quasi-adiabatic plasma state.

PubMed

Kim, Chang-Bae; An, Chan-Yong; Min, Byunghoon

2018-06-05

The dynamics of the fluctuating electrostatic potential and the plasma density couched in the resistive-drift model at nearly adiabatic state are simulated. The linear modes are unstable if the phase difference between the potential and the density are positive. Exponential growth of the random small perturbations slows down due to the nonlinear E × B flows that work in two ways. They regulate the strength of the fluctuations by transferring the energy from the energy-producing scale to neighboring scales and reduce the cross phase at the same time. During quasi-steady relaxation sporadic appearance of very strong turbulent particle flux is observed that is characterized by the flat energy spectrum and the broad secondary peak in the mesoscale of the order of the gyro-radius. Such boost of the transport is found to be caused by presence of relatively large cross phase as the E × B flows are not effective in cancelling out the cross phase.

Effects of music therapy on labour pain and anxiety in Taiwanese first-time mothers.

PubMed

Liu, Yu-Hsiang; Chang, Mei-Yueh; Chen, Chung-Hey

2010-04-01

The purpose of the study was to investigate the effects of music on pain reaction and anxiety during labour. Music therapy has been used on clinical medicine. Only few scientific studies validate the value on labour women. Randomised controlled trial. Sixty primiparas expected to have a normal spontaneous delivery were randomly assigned to either the experimental group (n = 30) or the control group (n = 30). The experimental group received routine care and music therapy, whereas the control group received routine care only. A self-report visual analogue scale for pain and a nurse-rated present behavioural intensity were used to measure labour pain. Anxiety was measured with a visual analogue scale for anxiety and finger temperature. Pain and anxiety between groups were compared during the latent phase (2-4 cm cervical dilation) and active phase (5-7 cm) separately. Our results revealed that compared with the control group, the experimental group had significantly lower pain, anxiety and a higher finger temperature during the latent phase of labour. However, no significant differences were found between the two groups on all outcome measures during the active phase. This study provides evidence for the use of music as an empirically based intervention of women for labour pain and anxiety during the latent phase of labour. The findings support that music listening is an acceptable and non-medical coping strategy for labouring women. Especially, apply in reducing the pain and anxiety for women who are at the early phase of labour.

Two-phase interdigitated microelectrode arrays for electrokinetic transport of microparticles

NASA Astrophysics Data System (ADS)

Bligh, Mathew; Stanley, Kevin G.; Hubbard, Ted; Kujath, Marek

2008-05-01

In this paper, we demonstrate long-range particle transport using linear two-phase interdigitated arrays with electrodes of equal size but with asymmetric spacing between them. We report net motion of 6 µm polystyrene spheres in an aqueous electrolyte and characterize the dependence of particle velocity on frequency, potential and phase, and show consistency with previous experiments that involved four-phase arrays producing AC electroosmotic and dielectrophoretic forces. We explore the effect of increasing the asymmetry of the electrode spacing and show that this decreases the performance of the array. We also examine the effect of increasing the overall scale of the array while maintaining geometric proportions and particle size and report that this also decreases the performance. We compare our results to previous analytical theoretical predictions and find general agreement.

The Effect of Peer Education upon Breast Self-Examination Behaviors and Self-Esteem among University Students.

PubMed

Ayran, Gulsun; Fırat, Meryem; Kucukakca, Gulden; Cuneydioğlu, Beyazıt; Tahta, Kubra; Avcı, Esra

2017-07-01

The current study was semi-experimentally designed in order to identify the effect of peer education upon breast self-examination (BSE) behaviors and self-esteem among university students. The study was undertaken with 100 female students who studied at Erzincan University. Peer educators were recruited from the 4th year students. The data were collected with a questionnaire form, BSE skill form and Rosenberg Self-esteem Scale in two phases one month before and after the BSE peer education. For the data assessment; percentage distributions, frequency, mean, standard deviation and Simple T test were employed. The mean age of the participant students was 20.45±1.67 year and all of them were single. It was found that during the first data collection phase, only 16 % of the students performed BSE while during the final data collection phase, the rate of the students performing BSE rose to 77 %. During the first data collection phase, students received a mean score of 2.36±4.13 from BSE skill form while during the last data collection phase they had a mean score of 10.70±3.40 from BSE skill form. When the scores obtained from Rosenberg Self-esteem Scale by the students were examined, it was seen that they received a mean score of 1.20±1.34 during the first data collection phase while they had a mean score of 0.84±1.07 during the final data collection phase. Although short-term feedback was obtained, it was noted that students' BSE knowledge and skills increased considerably.

Remediation of Uranium in the Hanford Vadose Zone Using Gas-Transported Reactants: Laboratory Scale Experiments in Support of the Deep Vadose Zone Treatability Test Plan for the Hanford Central Plateau

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

Szecsody, James E.; Truex, Michael J.; Zhong, Lirong

2010-01-04

This laboratory-scale investigation is focused on decreasing mobility of uranium in subsurface contaminated sediments in the vadose zone by in situ geochemical manipulation at low water content. This geochemical manipulation of the sediment surface phases included reduction, pH change (acidic and alkaline), and additions of chemicals (phosphate, ferric iron) to form specific precipitates. Reactants were advected into 1-D columns packed with Hanford 200 area U-contaminated sediment as a reactive gas (for CO2, NH3, H2S, SO2), with a 0.1% water content mist (for NaOH, Fe(III), HCl, PO4) and with a 1% water content foam (for PO4). Uranium is present in themore » sediment in multiple phases that include (in decreasing mobility): aqueous U(VI) complexes, adsorbed U, reduced U(IV) precipitates, rind-carbonates, total carbonates, oxides, silicates, phosphates, and in vanadate minerals. Geochemical changes were evaluated in the ability to change the mixture of surface U phases to less mobile forms, as defined by a series of liquid extractions that dissolve progressively less soluble phases. Although liquid extractions provide some useful information as to the generalized uranium surface phases (and are considered operational definitions of extracted phases), positive identification (by x-ray diffraction, electron microprobe, other techniques) was also used to positively identify U phases and effects of treatment. Some of the changes in U mobility directly involve U phases, whereas other changes result in precipitate coatings on U surface phases. The long-term implication of the U surface phase changes to alter U mass mobility in the vadose zone was then investigated using simulations of 1-D infiltration and downward migration of six U phases to the water table. In terms of the short-term decrease in U mobility (in decreasing order), NH3, NaOH mist, CO2, HCl mist, and Fe(III) mist showed 20% to 35% change in U surface phases. Phosphate addition (mist or foam advected) showed inconsistent change in aqueous and adsorbed U, but significant coating (likely phosphates) on U-carbonates. The two reductive gas treatments (H2S and SO2) showed little change. For long-term decrease in U reduction, mineral phases created that had low solubility (phosphates, silicates) were desired, so NH3, phosphates (mist and foam delivered), and NaOH mist showed the greatest formation of these minerals. In addition, simulations showed the greatest decrease in U mass transport time to reach groundwater (and concentration) for these silicate/phosphate minerals. Advection of reactive gasses was the easiest to implement at the laboratory scale (and presumably field scale). Both mist and foam advection show promise and need further development, but current implementation move reactants shorter distances relative to reactive gasses. Overall, the ammonia and carbon dioxide gas had the greatest overall geochemical performance and ability to implement at field scale. Corresponding mist-delivered technologies (NaOH mist for ammonia and HCl mist for carbon dioxide) performed as well or better geochemically, but are not as easily upscaled. Phosphate delivery by mist was rated slightly higher than by foam delivery simply due to the complexity of foam injection and unknown effect of U mobility by the presence of the surfactant.« less

Toward modeling of supercritical CO2 flow using the one-dimensional turbulence model

NASA Astrophysics Data System (ADS)

Schulz, F. T.; Glawe, C.; Schmidt, H.; Kerstein, A. R.

2012-04-01

Within the CCS (Carbon Capture and Storage) technology the transport of captured CO2 is increasingly regarded as the missing link in research. For industrial applications it is essential to transport CO2 from power plants to geological sites through pipelines and well bores. The effectiveness of such a transport could be increased by keeping CO2 in a supercritical state. This however requires a temperature of at least 31Celsius and a pressure above 73.8 bar. If these conditions are not maintained throughout the whole pipeline, which is challenging and expensive under non-laboratory conditions, density and phase changes and pressure fluctuations may result in harmful vibrations of the pipelines. Typically, simulations of pipeline flow are based on large-eddy simulations (LES) or the Reynolds averaged Navier-Stokes (RANS) equations which both do not resolve the smallest turbulent scales or even phase boundaries. Due to the effect that on pipe diameter scales the flow statistically changes predominantly in the wall normal direction one might consider 1D modeling approaches. The work presented here is part of the GeoEn II activities funded by the Federal Ministry of Education and Research (BMBF) to better understand risks and benefits of CCS technology. Our project goal is to better understand the small scale physics in turbulent CO2 flows and to improve subgrid-scale models used in LES codes. To achieve this we use ODT (One-Dimensional Turbulence), a statistical turbulence modeling strategy, where turbulent flow evolution along a notional 1D line of sight is emulated by applying instantaneous maps to represent the effect of individual turbulent eddies on property profiles along the line. The occurrence of an eddy itself is affected by the property profiles, resulting in a self-contained flow evolution that obeys the applicable conservation laws. Using a 1D ansatz permits a higher resolution of boundary and single phase density gradients which is key to understand the local CO2 pipe flow. Additionally, a level set technique can be used to track phase boundaries along the line of sight through a multi phase flow. Thus, artificial numerical smearing of the phase boundaries can be avoided. The ODT process can then move, create, and annihilate such interfaces. On the poster we illustrate some milestones to be reached to contribute to a better understanding of the small scale CO2 pipe flow problem. First ODT is validated and calibrated against a turbulent channel flow DNS at Reτ = 590 from Moser [1]. Second the evolution of turbulence statistics from a liquid jet experiment [2] is compared to ODT results. Concerning the single supercritical phase we give illustrative examples on how expectable temperature (density) changes in the pipe influence the turbulence [3]. Note that the numerical frame work presented here is not restricted to CO2 flows. The milestones and test cases already indicate other technical applications.

A Synergistic Combination of Advanced Separation and Chemical Scale Inhibitor Technologies for Efficient Use of Imparied Water As Cooling Water in Coal-based Power Plants

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

Jasbir Gill

2010-08-30

Nalco Company is partnering with Argonne National Laboratory (ANL) in this project to jointly develop advanced scale control technologies that will provide cost-effective solutions for coal-based power plants to operate recirculating cooling water systems at high cycles using impaired waters. The overall approach is to use combinations of novel membrane separations and scale inhibitor technologies that will work synergistically, with membrane separations reducing the scaling potential of the cooling water and scale inhibitors extending the safe operating range of the cooling water system. The project started on March 31, 2006 and ended in August 30, 2010. The project was amore » multiyear, multi-phase project with laboratory research and development as well as a small pilot-scale field demonstration. In Phase 1 (Technical Targets and Proof of Concept), the objectives were to establish quantitative technical targets and develop calcite and silica scale inhibitor chemistries for high stress conditions. Additional Phase I work included bench-scale testing to determine the feasibility of two membrane separation technologies (electrodialysis ED and electrode-ionization EDI) for scale minimization. In Phase 2 (Technology Development and Integration), the objectives were to develop additional novel scale inhibitor chemistries, develop selected separation processes, and optimize the integration of the technology components at the laboratory scale. Phase 3 (Technology Validation) validated the integrated system's performance with a pilot-scale demonstration. During Phase 1, Initial evaluations of impaired water characteristics focused on produced waters and reclaimed municipal wastewater effluents. Literature and new data were collected and evaluated. Characteristics of produced waters vary significantly from one site to another, whereas reclaimed municipal wastewater effluents have relatively more uniform characteristics. Assessment to date confirmed that calcite and silica/silicate are two common potential cycle-limiting minerals for using impaired waters. For produced waters, barium sulfate and calcium sulfate are two additional potential cycle-limiting minerals. For reclaimed municipal wastewater effluents, calcium phosphate scaling can be an issue, especially in the co-presence of high silica. Computational assessment, using a vast amount of Nalco's field data from coal fired power plants, showed that the limited use and reuse of impaired waters is due to the formation of deposit caused by the presence of iron, high hardness, high silica and high alkalinity in the water. Appropriate and cost-effective inhibitors were identified and developed - LL99B0 for calcite and gypsum inhibition and TX-15060 for silica inhibition. Nalco's existing dispersants HSP-1 and HSP-2 has excellent efficacy for dispersing Fe and Mn. ED and EDI were bench-scale tested by the CRADA partner Argonne National Laboratory for hardness, alkalinity and silica removal from synthetic make-up water and then cycled cooling water. Both systems showed low power consumption and 98-99% salt removal, however, the EDI system required 25-30% less power for silica removal. For Phase 2, the EDI system's performance was optimized and the length of time between clean-in-place (CIP) increased by varying the wafer composition and membrane configuration. The enhanced EDI system could remove 88% of the hardness and 99% of the alkalinity with a processing flux of 19.2 gal/hr/m{sup 2} and a power consumption of 0.54 kWh/100 gal water. Bench tests to screen alternative silica/silicate scale inhibitor chemistries have begun. The silica/silicate control approaches using chemical inhibitors include inhibition of silicic acid polymerization and dispersion of silica/silicate crystals. Tests were conducted with an initial silica concentration of 290-300 mg/L as SiO{sub 2} at pH 7 and room temperature. A proprietary new chemistry was found to be promising, compared with a current commercial product commonly used for silica/silicate control. Additional pilot cooling tower testing confirmed the bench study. We also developed a molecule to inhibit calcium carbonate precipitation and calcium sulfate precipitation at high supersaturations. During Phase 3, a long-term test of the EDI system and scale inhibitors was done at Nalco's cooling tower water testing facility, producing 850 gallons of high purity water (90+% salt removal) at a rate of 220 L/day. The EDI system's performance was stable when the salt concentration in the concentrate compartment (i.e. the EDI waste stream) was controlled and a CIP was done after every 48 hours of operation time. A combination of EDI and scale inhibitors completely eliminated blowdown discharge from the Pilot cooling Tower. The only water-consumption came from evaporation, CIP and EDI concentrate. Silica Inhibitor was evaluated in the field at a western coal fired power plant.« less

Strongly first-order electroweak phase transition and classical scale invariance

NASA Astrophysics Data System (ADS)

Farzinnia, Arsham; Ren, Jing

2014-10-01

In this work, we examine the possibility of realizing a strongly first-order electroweak phase transition within the minimal classically scale-invariant extension of the standard model (SM), previously proposed and analyzed as a potential solution to the hierarchy problem. By introducing one complex gauge-singlet scalar and three (weak scale) right-handed Majorana neutrinos, the scenario was successfully rendered capable of achieving a radiative breaking of the electroweak symmetry (by means of the Coleman-Weinberg mechanism), inducing nonzero masses for the SM neutrinos (via the seesaw mechanism), presenting a pseudoscalar dark matter candidate (protected by the CP symmetry of the potential), and predicting the existence of a second CP-even boson (with suppressed couplings to the SM content) in addition to the 125 GeV scalar. In the present treatment, we construct the full finite-temperature one-loop effective potential of the model, including the resummed thermal daisy loops, and demonstrate that finite-temperature effects induce a first-order electroweak phase transition. Requiring the thermally driven first-order phase transition to be sufficiently strong at the onset of the bubble nucleation (corresponding to nucleation temperatures TN˜100-200 GeV) further constrains the model's parameter space; in particular, an O(0.01) fraction of the dark matter in the Universe may be simultaneously accommodated with a strongly first-order electroweak phase transition. Moreover, such a phase transition disfavors right-handed Majorana neutrino masses above several hundreds of GeV, confines the pseudoscalar dark matter masses to ˜1-2 TeV, predicts the mass of the second CP-even scalar to be ˜100-300 GeV, and requires the mixing angle between the CP-even components of the SM doublet and the complex singlet to lie within the range 0.2≲sinω ≲0.4. The obtained results are displayed in comprehensive exclusion plots, identifying the viable regions of the parameter space. Many of these predictions lie within the reach of the next LHC run.

Toward industrial scale synthesis of ultrapure singlet nanoparticles with controllable sizes in a continuous gas-phase process

NASA Astrophysics Data System (ADS)

Feng, Jicheng; Biskos, George; Schmidt-Ott, Andreas

2015-10-01

Continuous gas-phase synthesis of nanoparticles is associated with rapid agglomeration, which can be a limiting factor for numerous applications. In this report, we challenge this paradigm by providing experimental evidence to support that gas-phase methods can be used to produce ultrapure non-agglomerated “singlet” nanoparticles having tunable sizes at room temperature. By controlling the temperature in the particle growth zone to guarantee complete coalescence of colliding entities, the size of singlets in principle can be regulated from that of single atoms to any desired value. We assess our results in the context of a simple analytical model to explore the dependence of singlet size on the operating conditions. Agreement of the model with experimental measurements shows that these methods can be effectively used for producing singlets that can be processed further by many alternative approaches. Combined with the capabilities of up-scaling and unlimited mixing that spark ablation enables, this study provides an easy-to-use concept for producing the key building blocks for low-cost industrial-scale nanofabrication of advanced materials.

Correlated disorder in the Kuramoto model: Effects on phase coherence, finite-size scaling, and dynamic fluctuations.

PubMed

Hong, Hyunsuk; O'Keeffe, Kevin P; Strogatz, Steven H

2016-10-01

We consider a mean-field model of coupled phase oscillators with quenched disorder in the natural frequencies and coupling strengths. A fraction p of oscillators are positively coupled, attracting all others, while the remaining fraction 1-p are negatively coupled, repelling all others. The frequencies and couplings are deterministically chosen in a manner which correlates them, thereby correlating the two types of disorder in the model. We first explore the effect of this correlation on the system's phase coherence. We find that there is a critical width γ c in the frequency distribution below which the system spontaneously synchronizes. Moreover, this γ c is independent of p. Hence, our model and the traditional Kuramoto model (recovered when p = 1) have the same critical width γ c . We next explore the critical behavior of the system by examining the finite-size scaling and the dynamic fluctuation of the traditional order parameter. We find that the model belongs to the same universality class as the Kuramoto model with deterministically (not randomly) chosen natural frequencies for the case of p < 1.

Nanometric Scale Investigation of Phase Transformations in Advanced Steels for Automotive Application

NASA Astrophysics Data System (ADS)

Drillet, Josée; Valle, Nathalie; Iung, Thierry

2012-12-01

The current trend toward producing lighter vehicles in the automotive industry is driven by the need to conform to the new exhaust emission control regulations. This objective presents a challenge to steel manufacturers. The difficulty lies in designing new alloys with an optimum strength/formability/cost balance for the various components. Here, the key to success lies in controlling the steel microstructure and especially the phase transformations at the smallest possible scale. Among the different alloying elements, light elements such as carbon and boron are of prime importance due to their major effects on the kinetics of phase transformations. Characterization tools combining high spatial and analytical resolution such as secondary ion mass spectrometry (SIMS) and field emission gun-transmission electron microscopy (TEM) were used. In this article, the examples presented are as follows. (1) Boron segregation and precipitation effects to control hardenability in martensitic steels. (2) Local carbon distribution in advanced high-strength steels, with a specific emphasis on martensite tempering. Links have been established between the boron and carbon distribution and the formability.

Effect of crystallographic orientations of grains on the global mechanical properties of steel sheets by depth sensing indentation

NASA Astrophysics Data System (ADS)

Burik, P.; Pesek, L.; Kejzlar, P.; Andrsova, Z.; Zubko, P.

2017-01-01

The main idea of this work is using a physical model to prepare a virtual material with required properties. The model is based on the relationship between the microstructure and mechanical properties. The macroscopic (global) mechanical properties of steel are highly dependent upon microstructure, crystallographic orientation of grains, distribution of each phase present, etc... We need to know the local mechanical properties of each phase separately in multiphase materials. The grain size is a scale, where local mechanical properties are responsible for the behavior. Nanomechanical testing using depth sensing indentation (DSI) provides a straightforward solution for quantitatively characterizing each of phases in microstructure because it is very powerful technique for characterization of materials in small volumes. The aim of this experimental investigation is: (i) to prove how the mixing rule works for local mechanical properties (indentation hardness HIT) in microstructure scale using the DSI technique on steel sheets with different microstructure; (ii) to compare measured global properties with properties achieved by mixing rule; (iii) to analyze the effect of crystallographic orientations of grains on the mixing rule.

Scale-up protein separation on stainless steel wide bore toroidal columns in the type-J counter-current chromatography.

PubMed

Guan, Yue Hugh; Hewitson, Peter; van den Heuvel, Remco N A M; Zhao, Yan; Siebers, Rick P G; Zhuang, Ying-Ping; Sutherland, Ian

2015-12-11

Manufacturing high-value added biotech biopharmaceutical products (e.g. therapeutic proteins) requires quick-to-develop, GMP-compliant, easy-to-scale and cost effective preparatory chromatography technologies. In this work, we describe the construction and testing of a set of 5-mm inner diameter stainless steel toroidal columns for use on commercially available preparatory scale synchronous J-type counter-current chromatography (CCC) machinery. We used a 20.2m long column with an aqueous two-phase system containing 14% (w/w) PEG1000 and 14% (w/w) potassium phosphate at pH 7, and tested a sample loading of 5% column volume and a mobile phase flow rate of 20ml/min. We then satisfactorily demonstrated the potential for a weekly protein separation and preparation throughput of ca. 11g based on a normal weekly routine for separating a pair of model proteins by making five stacked injections on a single portion of stationary phase with no stripping. Compared to our previous 1.6mm bore PTFE toroidal column, the present columns enlarged the nominal column processing throughput by nearly 10. For an ideal model protein injection modality, we observed a scaling up factor of at least 21. The 2 scales of protein separation and purification steps were realized on the same commercial CCC device. Copyright © 2015 Elsevier B.V. All rights reserved.

Multi-thread parallel algorithm for reconstructing 3D large-scale porous structures

NASA Astrophysics Data System (ADS)

Ju, Yang; Huang, Yaohui; Zheng, Jiangtao; Qian, Xu; Xie, Heping; Zhao, Xi

2017-04-01

Geomaterials inherently contain many discontinuous, multi-scale, geometrically irregular pores, forming a complex porous structure that governs their mechanical and transport properties. The development of an efficient reconstruction method for representing porous structures can significantly contribute toward providing a better understanding of the governing effects of porous structures on the properties of porous materials. In order to improve the efficiency of reconstructing large-scale porous structures, a multi-thread parallel scheme was incorporated into the simulated annealing reconstruction method. In the method, four correlation functions, which include the two-point probability function, the linear-path functions for the pore phase and the solid phase, and the fractal system function for the solid phase, were employed for better reproduction of the complex well-connected porous structures. In addition, a random sphere packing method and a self-developed pre-conditioning method were incorporated to cast the initial reconstructed model and select independent interchanging pairs for parallel multi-thread calculation, respectively. The accuracy of the proposed algorithm was evaluated by examining the similarity between the reconstructed structure and a prototype in terms of their geometrical, topological, and mechanical properties. Comparisons of the reconstruction efficiency of porous models with various scales indicated that the parallel multi-thread scheme significantly shortened the execution time for reconstruction of a large-scale well-connected porous model compared to a sequential single-thread procedure.

Tempo and scale of biogenic effects on high-frequency acoustic propagation near the marine sediment-water interface in shallow water

NASA Astrophysics Data System (ADS)

Jumars, Peter

2003-04-01

Organisms have natural scales, such as lifetimes, body sizes, frequencies of movement to new locations, and residence times of material in digestive systems, and each scale has potential implications for acoustic effects. The effects of groups of organisms, like organisms themselves, aggregate in space and time. This review, including an assortment of unpublished information, examines examples of such aggregations, many of them documented acoustically. Light synchronizes many activities. Macroscopic animals forage primarily under cover of darkness. This phasing applies both to animals that extend appendages above the sediment-water interface and to animals that leave the seabed at night. Whereas their bottom-modifying activities are concentrated in nocturnal or crepuscular fashion, the bottom-modifying activities of the visual feeders follow a different phasing and often dominate the rate of change in acoustic backscatter from the interface. Light also acts through its effects on primary production, often concentrated in a very thin surficial layer atop the seabed. The supersaturation of oxygen does, and microbubble nucleation may, result. Where tidal velocities are large, light-set patterns are often tidally modulated. Activities of animals living below the seabed, however, remain a mystery, whose primary hope for solution is acoustic. [Work supported by ONR and DEPSCoR.

Realising effective theories of tribrid inflation: are there effects from messenger fields?

NASA Astrophysics Data System (ADS)

Antusch, Stefan; Nolde, David

2015-09-01

Tribrid inflation is a variant of supersymmetric hybrid inflation in which the inflaton is a matter field (which can be charged under gauge symmetries) and inflation ends by a GUT-scale phase transition of a waterfall field. These features make tribrid inflation a promising framework for realising inflation with particularly close connections to particle physics. Superpotentials of tribrid inflation involve effective operators suppressed by some cutoff scale, which is often taken as the Planck scale. However, these operators may also be generated by integrating out messenger superfields with masses below the Planck scale, which is in fact quite common in GUT and/or flavour models. The values of the inflaton field during inflation can then lie above this mass scale, which means that for reliably calculating the model predictions one has to go beyond the effective theory description. We therefore discuss realisations of effective theories of tribrid inflation and specify in which cases effects from the messenger fields are expected, and under which conditions they can safely be neglected. In particular, we point out how to construct realisations where, despite the fact that the inflaton field values are above the messenger mass scale, the predictions for the observables are (to a good approximation) identical to the ones calculated in the effective theory treatment where the messenger mass scale is identified with the (apparent) cutoff scale.

Realising effective theories of tribrid inflation: are there effects from messenger fields?

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

Antusch, Stefan; Max-Planck-Institut für Physik; Nolde, David

2015-09-22

Tribrid inflation is a variant of supersymmetric hybrid inflation in which the inflaton is a matter field (which can be charged under gauge symmetries) and inflation ends by a GUT-scale phase transition of a waterfall field. These features make tribrid inflation a promising framework for realising inflation with particularly close connections to particle physics. Superpotentials of tribrid inflation involve effective operators suppressed by some cutoff scale, which is often taken as the Planck scale. However, these operators may also be generated by integrating out messenger superfields with masses below the Planck scale, which is in fact quite common in GUTmore » and/or flavour models. The values of the inflaton field during inflation can then lie above this mass scale, which means that for reliably calculating the model predictions one has to go beyond the effective theory description. We therefore discuss realisations of effective theories of tribrid inflation and specify in which cases effects from the messenger fields are expected, and under which conditions they can safely be neglected. In particular, we point out how to construct realisations where, despite the fact that the inflaton field values are above the messenger mass scale, the predictions for the observables are (to a good approximation) identical to the ones calculated in the effective theory treatment where the messenger mass scale is identified with the (apparent) cutoff scale.« less

Realising effective theories of tribrid inflation: are there effects from messenger fields?

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

Antusch, Stefan; Nolde, David, E-mail: stefan.antusch@unibas.ch, E-mail: david.nolde@unibas.ch

2015-09-01

Tribrid inflation is a variant of supersymmetric hybrid inflation in which the inflaton is a matter field (which can be charged under gauge symmetries) and inflation ends by a GUT-scale phase transition of a waterfall field. These features make tribrid inflation a promising framework for realising inflation with particularly close connections to particle physics. Superpotentials of tribrid inflation involve effective operators suppressed by some cutoff scale, which is often taken as the Planck scale. However, these operators may also be generated by integrating out messenger superfields with masses below the Planck scale, which is in fact quite common in GUTmore » and/or flavour models. The values of the inflaton field during inflation can then lie above this mass scale, which means that for reliably calculating the model predictions one has to go beyond the effective theory description. We therefore discuss realisations of effective theories of tribrid inflation and specify in which cases effects from the messenger fields are expected, and under which conditions they can safely be neglected. In particular, we point out how to construct realisations where, despite the fact that the inflaton field values are above the messenger mass scale, the predictions for the observables are (to a good approximation) identical to the ones calculated in the effective theory treatment where the messenger mass scale is identified with the (apparent) cutoff scale.« less

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

Willey, Trevor M.; Lauderbach, Lisa; Gagliardi, Franco

HMX-based explosives LX-10 and PBX-9501 were heated through the β-δ phase transition. Ultra-small angle x-ray scattering (USAXS) and molecular diffraction were simultaneously recorded as the HMX was heated. Mesoscale voids and structure dramatically change promptly with the β-δ phase transition, rather than with other thermal effects. Also, x-ray induced damage, observed in the USAXS, occurs more readily at elevated temperatures; as such, the dose was reduced to mitigate this effect. Optical microscopy performed during a similar heating cycle gives an indication of changes on longer length scales, while x-ray microtomography, performed before and after heating, shows the character of extensivemore » microstructural damage resulting from the temperature cycle and solid-state phase transition.« less

Length-Scale-Dependent Phase Transformation of LiFePO4 : An In situ and Operando Study Using Micro-Raman Spectroscopy and XRD.

PubMed

Siddique, N A; Salehi, Amir; Wei, Zi; Liu, Dong; Sajjad, Syed D; Liu, Fuqiang

2015-08-03

The charge and discharge of lithium ion batteries are often accompanied by electrochemically driven phase-transformation processes. In this work, two in situ and operando methods, that is, micro-Raman spectroscopy and X-ray diffraction (XRD), have been combined to study the phase-transformation process in LiFePO4 at two distinct length scales, namely, particle-level scale (∼1 μm) and macroscopic scale (∼several cm). In situ Raman studies revealed a discrete mode of phase transformation at the particle level. Besides, the preferred electrochemical transport network, particularly the carbon content, was found to govern the sequence of phase transformation among particles. In contrast, at the macroscopic level, studies conducted at four different discharge rates showed a continuous but delayed phase transformation. These findings uncovered the intricate phase transformation in LiFePO4 and potentially offer valuable insights into optimizing the length-scale-dependent properties of battery materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Letter report on PCT/Monolith glass ceramic corrosion tests

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

Crawford, Charles L.

2015-09-24

The Savannah River National Laboratory (SRNL) is collaborating with personnel from Pacific Northwest National Laboratory (PNNL) to study advanced waste form glass ceramics for immobilization of waste from Used Nuclear Fuel (UNF) separations processes. The glass ceramic waste forms take advantage of both crystalline and glassy phases where ‘troublesome’ elements (e.g., low solubility in glass or very long-lived) partition to highly durable ceramic phases with the remainder of elements residing in the glassy phase. The ceramic phases are tailored to create certain minerals or unique crystalline structures that can host the radionuclides by binding them in their specific crystalline networkmore » while not adversely impacting the residual glass network (Crum et al., 2011). Glass ceramics have been demonstrated using a scaled melter test performed in a pilot scale (1/4 scale) cold crucible induction melter (CCIM) (Crum et al., 2014; Maio et al., 2015). This report summarizes recent results from both Phase I and Phase II bench scale tests involving crucible fabrication and corrosion testing of glass ceramics using the Product Consistency Test (PCT). Preliminary results from both Phase I and Phase II bench scale tests involving statistically designed matrices have previously been reported (Crawford, 2013; Crawford, 2014).« less

Infection Threshold for an Epidemic Model in Site and Bond Percolation Worlds

NASA Astrophysics Data System (ADS)

Sakisaka, Yukio; Yoshimura, Jin; Takeuchi, Yasuhiro; Sugiura, Koji; Tainaka, Kei-ichi

2010-02-01

We investigate an epidemic model on a square lattice with two protection treatments: prevention and quarantine. To explore the effects of both treatments, we apply the site and bond percolations. Computer simulations reveal that the threshold between endemic and disease-free phases can be represented by a single scaling law. The mean-field theory qualitatively predicts such infection dynamics and the scaling law.

A study of complex scaling transformation using the Wigner representation of wavefunctions.

PubMed

Kaprálová-Ždánská, Petra Ruth

2011-05-28

The complex scaling operator exp(-θ ̂x̂p/ℏ), being a foundation of the complex scaling method for resonances, is studied in the Wigner phase-space representation. It is shown that the complex scaling operator behaves similarly to the squeezing operator, rotating and amplifying Wigner quasi-probability distributions of the respective wavefunctions. It is disclosed that the distorting effect of the complex scaling transformation is correlated with increased numerical errors of computed resonance energies and widths. The behavior of the numerical error is demonstrated for a computation of CO(2+) vibronic resonances. © 2011 American Institute of Physics

Adjunctive treatment of manic agitation with lorazepam versus haloperidol: a double-blind study.

PubMed

Lenox, R H; Newhouse, P A; Creelman, W L; Whitaker, T M

1992-02-01

While lithium is effective in treating the majority of bipolar patients during a manic episode, the addition of neuroleptic during the early phase of treatment has been common clinical practice in inpatient settings. In an earlier open study, we demonstrated the utility of the short-acting benzodiazepine lorazepam as an adjunct to lithium for the clinical management of manic agitation. We now present data from a randomized, double-blind clinical study of lorazepam versus haloperidol in 20 hospitalized patients with a DSM-III-R diagnosis of bipolar disorder who were being treated concomitantly with lithium. Patients were rated using the Mania Rating Scale, Brief Psychiatric Rating Scale, Physician Global Impression Scale, and side effects scales. Data were analyzed using standard group comparisons and survival analysis. There was no evidence for a significant difference between the two treatment groups in the magnitude of or time to response (5.0 +/- .82 days for haloperidol; 6.5 +/- .93 days for lorazepam). Of the patients who were terminated from the protocol early, nonresponse was the primary reason in the lorazepam group while side effects were the reason in the haloperidol group. Lorazepam may offer an efficacious and safe alternative to haloperidol as an adjunctive treatment to lithium in the clinical management of the early phase of manic agitation in a subgroup of bipolar patients.

Hofmeister series salts enhance purification of plasmid DNA by non-ionic detergents

PubMed Central

Lezin, George; Kuehn, Michael R.; Brunelli, Luca

2011-01-01

Ion-exchange chromatography is the standard technique used for plasmid DNA purification, an essential molecular biology procedure. Non-ionic detergents (NIDs) have been used for plasmid DNA purification, but it is unclear whether Hofmeister series salts (HSS) change the solubility and phase separation properties of specific NIDs, enhancing plasmid DNA purification. After scaling-up NID-mediated plasmid DNA isolation, we established that NIDs in HSS solutions minimize plasmid DNA contamination with protein. In addition, large-scale NID/HSS solutions eliminated LPS contamination of plasmid DNA more effectively than Qiagen ion-exchange columns. Large-scale NID isolation/NID purification generated increased yields of high quality DNA compared to alkali isolation/column purification. This work characterizes how HSS enhance NID-mediated plasmid DNA purification, and demonstrates that NID phase transition is not necessary for LPS removal from plasmid DNA. Specific NIDs such as IGEPAL CA-520 can be utilized for rapid, inexpensive and efficient laboratory-based large-scale plasmid DNA purification, outperforming Qiagen-based column procedures. PMID:21351074

Length scales and pinning of interfaces

PubMed Central

Tan, Likun

2016-01-01

The pinning of interfaces and free discontinuities by defects and heterogeneities plays an important role in a variety of phenomena, including grain growth, martensitic phase transitions, ferroelectricity, dislocations and fracture. We explore the role of length scale on the pinning of interfaces and show that the width of the interface relative to the length scale of the heterogeneity can have a profound effect on the pinning behaviour, and ultimately on hysteresis. When the heterogeneity is large, the pinning is strong and can lead to stick–slip behaviour as predicted by various models in the literature. However, when the heterogeneity is small, we find that the interface may not be pinned in a significant manner. This shows that a potential route to making materials with low hysteresis is to introduce heterogeneities at a length scale that is small compared with the width of the phase boundary. Finally, the intermediate setting where the length scale of the heterogeneity is comparable to that of the interface width is characterized by complex interactions, thereby giving rise to a non-monotone relationship between the relative heterogeneity size and the critical depinning stress. PMID:27002068

Modification of the Clinical Global Impressions (CGI) Scale for use in bipolar illness (BP): the CGI-BP.

PubMed

Spearing, M K; Post, R M; Leverich, G S; Brandt, D; Nolen, W

1997-12-05

The Clinical Global Impressions Scale (CGI) was modified specifically for use in assessing global illness severity and change in patients with bipolar disorder. Criticisms of the original CGI were addressed by correcting inconsistencies in scaling, identifying time frames for comparison, clarifying definitions of illness severity and change, and separating out assessment of treatment side effects from illness improvement during treatment. A Detailed User's Guide was developed to train clinicians in the use of the new CGI-Bipolar Version (CGI-BP) for rating severity of manic and depressive episodes and the degree of change from the immediately preceding phase and from the worst phase of illness. The revised scale and manual provide a focused set of instructions to facilitate the reliability of these ratings of mania, depression, and overall bipolar illness during treatment of an acute episode or in longer-term illness prophylaxis. Interrater reliability of the scale was demonstrated in preliminary analyses. Thus, the modified CGI-BP is anticipated to be more useful than the original CGI in studies of bipolar disorder.

Impact of inward turbulence spreading on energy loss of edge-localized modes

DOE PAGES

Ma, C. H.; Xu, X. Q.; Xi, P. W.; ...

2015-05-18

Nonlinear two-fluid and gyrofluid simulations show that an edge localized modes(ELM) crash has two phases: fast initial crash of ion temperature perturbation on the Alfvén time scale and slow turbulence spreading. The turbulencetransport phase is a slow encroachment of electron temperature perturbation due to the ELM event into pedestal region. Because of the inward turbulence spreading effect, the energy loss of an ELM decreases when density pedestal height increases. The Landau resonance yields the different cross phase-shift of ions and electrons. A 3 + 1 gyro-Landau-fluid model is implemented in BOUT++ framework. As a result, the gyrofluid simulations show thatmore » the kinetic effects have stabilizing effects on the ideal ballooning mode and the energy loss increases with the pedestal height.« less

Edge detection based on adaptive threshold b-spline wavelet for optical sub-aperture measuring

NASA Astrophysics Data System (ADS)

Zhang, Shiqi; Hui, Mei; Liu, Ming; Zhao, Zhu; Dong, Liquan; Liu, Xiaohua; Zhao, Yuejin

2015-08-01

In the research of optical synthetic aperture imaging system, phase congruency is the main problem and it is necessary to detect sub-aperture phase. The edge of the sub-aperture system is more complex than that in the traditional optical imaging system. And with the existence of steep slope for large-aperture optical component, interference fringe may be quite dense when interference imaging. Deep phase gradient may cause a loss of phase information. Therefore, it's urgent to search for an efficient edge detection method. Wavelet analysis as a powerful tool is widely used in the fields of image processing. Based on its properties of multi-scale transform, edge region is detected with high precision in small scale. Longing with the increase of scale, noise is reduced in contrary. So it has a certain suppression effect on noise. Otherwise, adaptive threshold method which sets different thresholds in various regions can detect edge points from noise. Firstly, fringe pattern is obtained and cubic b-spline wavelet is adopted as the smoothing function. After the multi-scale wavelet decomposition of the whole image, we figure out the local modulus maxima in gradient directions. However, it also contains noise, and thus adaptive threshold method is used to select the modulus maxima. The point which greater than threshold value is boundary point. Finally, we use corrosion and expansion deal with the resulting image to get the consecutive boundary of image.

Diffusivity in Alumina Scales Grown on Al-MAX Phases

NASA Technical Reports Server (NTRS)

Smialek, James L.

2014-01-01

Ti3AlC2, Ti2AlC, and Cr2AlC are oxidation resistant MAX phase compounds distinguished by the formation of protective Al2O3 scales with well controlled kinetics. A modified Wagner treatment was used to obtain interfacial grain boundary diffusivity, deltaD(sub gb,O,int.), from scale growth rates and corresponding grain size. It is based on the p(O2)(exp -1/6) dependency of the double charged oxygen vacancy and oxygen diffusivity, coupled with the effective diffusion constant for short circuit grain boundary paths. Data from the literature for MAX phases was analyzed accordingly, and deltaD(sub gb,O,int.) was found to nearly coincide with the Arrhenius line developed for Zr-doped FeCrAl, where: deltaD(sub gb,O,int.) = 1.8x10(exp -10) exp(-375 kJ/RT) cubic meters/s. Furthermore, this oxidation relation suggests the more general format applicable to bulk samples under ambient conditions: deltaD(sub gb,O) = 7.567x10(exp -8) exp(-544 kJ/RT) p(O2)(exp -1/6) cubic meters/[s x Pa(exp -1/6)]. Data from many other FeCrAl(X) studies were similarly assessed to show general agreement with the relation for deltaD(sub gb,O,int.). This analysis reinforces the view that protective alumina scales grow by similar mechanisms for these Al-MAX phases and oxidation resistant FeCrAl alloys.

Antibiotics Smart Use: a workable model for promoting the rational use of medicines in Thailand

PubMed Central

Chongtrakul, Pisonthi; Anuwong, Kunyada; Pumtong, Somying; Kongsomboon, Kedsenee; Butdeemee, Parichart; Khonglormyati, Jurairat; Chomyong, Santi; Tongyoung, Parnuchote; Losiriwat, Suraphol; Seesuk, Piyanooch; Suwanwaree, Pongthep; Tangcharoensathien, Viroj

2012-01-01

Abstract The Antibiotics Smart Use (ASU) programme was introduced in Thailand as a model to promote the rational use of medicines, starting with antibiotics. The programme’s first phase consisted of assessing interventions intended to change prescribing practices; the second phase examined the feasibility of programme scale-up. Currently the programme is in its third phase, which centres on sustainability. This paper describes the concept behind ASU, the programme’s functional modalities, the development of its conceptual framework and the implementation of its first and second phases. To change antibiotic prescription practices, multifaceted interventions at the individual and organizational levels were implemented; to maintain behaviour change and scale up the programme, interventions at the network and policy levels were used. The National Health Security Office has adopted ASU as a pay-for-performance criterion, a major achievement that has led to the programme’s expansion nationwide. Despite limited resources, programme scale-up and sustainability have been facilitated by the promotion of local ownership and mutual recognition, which have generated pride and commitment. ASU is clearly a workable entry point for efforts to rationalize the use of medicines in Thailand. Its long-term sustainability will require continued local commitment and political support, effective auditing and integration of ASU into routine systems with appropriate financial incentives. PMID:23284196

Antibiotics Smart Use: a workable model for promoting the rational use of medicines in Thailand.

PubMed

Sumpradit, Nithima; Chongtrakul, Pisonthi; Anuwong, Kunyada; Pumtong, Somying; Kongsomboon, Kedsenee; Butdeemee, Parichart; Khonglormyati, Jurairat; Chomyong, Santi; Tongyoung, Parnuchote; Losiriwat, Suraphol; Seesuk, Piyanooch; Suwanwaree, Pongthep; Tangcharoensathien, Viroj

2012-12-01

The Antibiotics Smart Use (ASU) programme was introduced in Thailand as a model to promote the rational use of medicines, starting with antibiotics. The programme's first phase consisted of assessing interventions intended to change prescribing practices; the second phase examined the feasibility of programme scale-up. Currently the programme is in its third phase, which centres on sustainability. This paper describes the concept behind ASU, the programme's functional modalities, the development of its conceptual framework and the implementation of its first and second phases. To change antibiotic prescription practices, multifaceted interventions at the individual and organizational levels were implemented; to maintain behaviour change and scale up the programme, interventions at the network and policy levels were used. The National Health Security Office has adopted ASU as a pay-for-performance criterion, a major achievement that has led to the programme's expansion nationwide. Despite limited resources, programme scale-up and sustainability have been facilitated by the promotion of local ownership and mutual recognition, which have generated pride and commitment. ASU is clearly a workable entry point for efforts to rationalize the use of medicines in Thailand. Its long-term sustainability will require continued local commitment and political support, effective auditing and integration of ASU into routine systems with appropriate financial incentives.

From atomistic interfaces to dendritic patterns

NASA Astrophysics Data System (ADS)

Galenko, P. K.; Alexandrov, D. V.

2018-01-01

Transport processes around phase interfaces, together with thermodynamic properties and kinetic phenomena, control the formation of dendritic patterns. Using the thermodynamic and kinetic data of phase interfaces obtained on the atomic scale, one can analyse the formation of a single dendrite and the growth of a dendritic ensemble. This is the result of recent progress in theoretical methods and computational algorithms calculated using powerful computer clusters. Great benefits can be attained from the development of micro-, meso- and macro-levels of analysis when investigating the dynamics of interfaces, interpreting experimental data and designing the macrostructure of samples. The review and research articles in this theme issue cover the spectrum of scales (from nano- to macro-length scales) in order to exhibit recently developing trends in the theoretical analysis and computational modelling of dendrite pattern formation. Atomistic modelling, the flow effect on interface dynamics, the transition from diffusion-limited to thermally controlled growth existing at a considerable driving force, two-phase (mushy) layer formation, the growth of eutectic dendrites, the formation of a secondary dendritic network due to coalescence, computational methods, including boundary integral and phase-field methods, and experimental tests for theoretical models-all these themes are highlighted in the present issue. This article is part of the theme issue `From atomistic interfaces to dendritic patterns'.

Instrument development and validation of a quality scale for historical research papers (QSHRP): a pilot study.

PubMed

Kelly, Jacinta; Watson, Roger

2014-12-01

To report a pilot study for the development and validation of an instrument to measure quality in historical research papers. There are no set criteria to assess historical papers published in nursing journals. A three phase mixed method sequential confirmatory design. In 2012, we used a three-phase approach to item generation and content evaluation. In phase 1, we consulted nursing historians using an online survey comprising three open-ended questions and revised the items. In phase 2, we evaluated the revised items for relevance with expert historians using a 4-point Likert scale and Content Validity Index calculation. In phase 3, we conducted reliability testing of the instrument using a 3-point Likert scale. In phase 1, 121 responses were generated via the online survey and revised to 40 interrogatively phrased items. In phase 2, five items with an Item Content Validity Index score of ≥0·7 remained. In phase 3, responses from historians resulted in 100% agreement to questions 1, 2 and 4 and 89% and 78%, respectively, to questions 3 and 5. Items for the QSHRP have been identified, content validated and reliability tested. This scale improves on previous scales, which over-emphasized source criticism. However, a full-scale study is needed with nursing historians to increase its robustness. © 2014 John Wiley & Sons Ltd.

Program for the improvement of downhole drilling motor bearings and seals. Phase V. Final report

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

DeLafosse, P.H.; Tibbitts, G.A.; Black, A.D.

1983-08-01

The work done during the fifth and final phase of a program to improve downhole drilling motor bearing and seals is described. The principal activities in this phase were: (a) testing seals with abrasive-laden mud on the low-pressure side; (b) test second and third generation designs of both elastomeric chevron seals and Teflon U-seals; and (c) testing a full-scale bearing/seal package. Several operating parameters which have a radical effect on seal life were identified, and some promising designs and materials were tested.

Measuring Challenge, Fun and Sterility on a "Phunometre" Scale: Evaluating Creative Teaching and Learning with Children and Their Student Teachers in the Primary School

ERIC Educational Resources Information Center

Elton-Chalcraft, Sally; Mills, Kären

2015-01-01

"It was the funnest week in the whole history of funnest weeks": our case study, the second phase in a three-phase research project, evaluates the successes and limitations of creative teaching and learning during the "The Creative and Effective Curriculum" module for PGCE primary student teachers which includes a one-week…

Finite volume solution for two-phase flow in a straight capillary

NASA Astrophysics Data System (ADS)

Yelkhovsky, Alexander; Pinczewski, W. Val

2018-04-01

The problem of two-phase flow in straight capillaries of polygonal cross section displays many of the dynamic characteristics of rapid interfacial motions associated with pore-scale displacements in porous media. Fluid inertia is known to be important in these displacements but is usually ignored in network models commonly used to predict macroscopic flow properties. This study presents a numerical model for two-phase flow which describes the spatial and temporal evolution of the interface between the fluids. The model is based on an averaged Navier-Stokes equation and is shown to be successful in predicting the complex dynamics of both capillary rise in round capillaries and imbibition along the corners of polygonal capillaries. The model can form the basis for more realistic network models which capture the effect of capillary, viscous, and inertial forces on pore-scale interfacial dynamics and consequent macroscopic flow properties.

Atomic scale modelling of hexagonal structured metallic fission product alloys

PubMed Central

Middleburgh, S. C.; King, D. M.; Lumpkin, G. R.

2015-01-01

Noble metal particles in the Mo-Pd-Rh-Ru-Tc system have been simulated on the atomic scale using density functional theory techniques for the first time. The composition and behaviour of the epsilon phases are consistent with high-entropy alloys (or multi-principal component alloys)—making the epsilon phase the only hexagonally close packed high-entropy alloy currently described. Configurational entropy effects were considered to predict the stability of the alloys with increasing temperatures. The variation of Mo content was modelled to understand the change in alloy structure and behaviour with fuel burnup (Mo molar content decreases in these alloys as burnup increases). The predicted structures compare extremely well with experimentally ascertained values. Vacancy formation energies and the behaviour of extrinsic defects (including iodine and xenon) in the epsilon phase were also investigated to further understand the impact that the metallic precipitates have on fuel performance. PMID:26064629

Influence of geographical scale on the detection of density dependence in the host-parasite system, Arvicola terrestris and Taenia taeniaeformis.

PubMed

Deter, J; Berthier, K; Chaval, Y; Cosson, J F; Morand, S; Charbonnel, N

2006-04-01

Infection by the cestode Taenia taeniaeformis was investigated within numerous cyclic populations of the fossorial water vole Arvicola terrestris sampled during 4 years in Franche-Comté (France). The relative influence of different rodent demographic parameters on the presence of this cestode was assessed by considering (1) the demographic phase of the cycle; (2) density at the local geographical scale (<0.1 km2); (3) mean density at a larger scale (>10 km2). The local scale corresponded to the rodent population (intermediate host), while the large scale corresponded to the definitive host population (wild and feral cats). General linear models based on analyses of 1804 voles revealed the importance of local density but also of year, rodent age, season and interactions between year and season and between age and season. Prevalence was significantly higher in low vole densities than during local outbreaks. By contrast, the large geographical scale density and the demographic phase had less influence on infection by the cestode. The potential impacts of the cestode on the fitness of the host were assessed and infection had no effect on the host body mass, litter size or sexual activity of voles.

Impact of Antarctic mixed-phase clouds on climate.

PubMed

Lawson, R Paul; Gettelman, Andrew

2014-12-23

Precious little is known about the composition of low-level clouds over the Antarctic Plateau and their effect on climate. In situ measurements at the South Pole using a unique tethered balloon system and ground-based lidar reveal a much higher than anticipated incidence of low-level, mixed-phase clouds (i.e., consisting of supercooled liquid water drops and ice crystals). The high incidence of mixed-phase clouds is currently poorly represented in global climate models (GCMs). As a result, the effects that mixed-phase clouds have on climate predictions are highly uncertain. We modify the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM) GCM to align with the new observations and evaluate the radiative effects on a continental scale. The net cloud radiative effects (CREs) over Antarctica are increased by +7.4 Wm(-2), and although this is a significant change, a much larger effect occurs when the modified model physics are extended beyond the Antarctic continent. The simulations show significant net CRE over the Southern Ocean storm tracks, where recent measurements also indicate substantial regions of supercooled liquid. These sensitivity tests confirm that Southern Ocean CREs are strongly sensitive to mixed-phase clouds colder than -20 °C.

Impact of Antarctic mixed-phase clouds on climate

PubMed Central

Lawson, R. Paul; Gettelman, Andrew

2014-01-01

Precious little is known about the composition of low-level clouds over the Antarctic Plateau and their effect on climate. In situ measurements at the South Pole using a unique tethered balloon system and ground-based lidar reveal a much higher than anticipated incidence of low-level, mixed-phase clouds (i.e., consisting of supercooled liquid water drops and ice crystals). The high incidence of mixed-phase clouds is currently poorly represented in global climate models (GCMs). As a result, the effects that mixed-phase clouds have on climate predictions are highly uncertain. We modify the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM) GCM to align with the new observations and evaluate the radiative effects on a continental scale. The net cloud radiative effects (CREs) over Antarctica are increased by +7.4 Wm−2, and although this is a significant change, a much larger effect occurs when the modified model physics are extended beyond the Antarctic continent. The simulations show significant net CRE over the Southern Ocean storm tracks, where recent measurements also indicate substantial regions of supercooled liquid. These sensitivity tests confirm that Southern Ocean CREs are strongly sensitive to mixed-phase clouds colder than −20 °C. PMID:25489069

Non-Boussinesq Dissolution-Driven Convection in Porous Media

NASA Astrophysics Data System (ADS)

Amooie, M. A.; Soltanian, M. R.; Moortgat, J.

2017-12-01

Geological carbon dioxide (CO2) sequestration in deep saline aquifers has been increasingly recognized as a feasible technology to stabilize the atmospheric carbon concentrations and subsequently mitigate the global warming. Solubility trapping is one of the most effective storage mechanisms, which is associated initially with diffusion-driven slow dissolution of gaseous CO2 into the aqueous phase, followed by density-driven convective mixing of CO2 throughout the aquifer. The convection includes both diffusion and fast advective transport of the dissolved CO2. We study the fluid dynamics of CO2 convection in the underlying single aqueous-phase region. Two modeling approaches are employed to define the system: (i) a constant-concentration condition for CO2 in aqueous phase at the top boundary, and (ii) a sufficiently low, constant injection-rate for CO2 from top boundary. The latter allows for thermodynamically consistent evolution of the CO2 composition and the aqueous phase density against the rate at which the dissolved CO2 convects. Here we accurately model the full nonlinear phase behavior of brine-CO2 mixture in a confined domain altered by dissolution and compressibility, while relaxing the common Boussinesq approximation. We discover new flow regimes and present quantitative scaling relations for global characters of spreading, mixing, and dissolution flux in two- and three-dimensional media for the both model types. We then revisit the universal Sherwood-Rayleigh scaling that is under debate for porous media convective flows. Our findings confirm the sublinear scaling for the constant-concentration case, while reconciling the classical linear scaling for the constant-injection model problem. The results provide a detailed perspective into how the available modeling strategies affect the prediction ability for the total amount of CO2 dissolved in the long term within saline aquifers of different permeabilities.

Continuum theory of phase separation kinetics for active Brownian particles.

PubMed

Stenhammar, Joakim; Tiribocchi, Adriano; Allen, Rosalind J; Marenduzzo, Davide; Cates, Michael E

2013-10-04

Active Brownian particles (ABPs), when subject to purely repulsive interactions, are known to undergo activity-induced phase separation broadly resembling an equilibrium (attraction-induced) gas-liquid coexistence. Here we present an accurate continuum theory for the dynamics of phase-separating ABPs, derived by direct coarse graining, capturing leading-order density gradient terms alongside an effective bulk free energy. Such gradient terms do not obey detailed balance; yet we find coarsening dynamics closely resembling that of equilibrium phase separation. Our continuum theory is numerically compared to large-scale direct simulations of ABPs and accurately accounts for domain growth kinetics, domain topologies, and coexistence densities.

Generalized thermodynamics of phase equilibria in scalar active matter

NASA Astrophysics Data System (ADS)

Solon, Alexandre P.; Stenhammar, Joakim; Cates, Michael E.; Kafri, Yariv; Tailleur, Julien

2018-02-01

Motility-induced phase separation (MIPS) arises generically in fluids of self-propelled particles when interactions lead to a kinetic slowdown at high densities. Starting from a continuum description of scalar active matter akin to a generalized Cahn-Hilliard equation, we give a general prescription for the mean densities of coexisting phases in flux-free steady states that amounts, at a hydrodynamics scale, to extremizing an effective free energy. We illustrate our approach on two well-known models: self-propelled particles interacting either through a density-dependent propulsion speed or via direct pairwise forces. Our theory accounts quantitatively for their phase diagrams, providing a unified description of MIPS.

The Role of Partial Surface Charge Compensation in the Properties of Ferroelectric and Antiferroelectric Thin Films

NASA Astrophysics Data System (ADS)

Swedberg, Elena

Ferroelectric and antiferroelectric ultrathin films have attracted a lot of attention recently due to their remarkable properties and their potential to allow for device miniaturization in numerous applications. However, when the ferroelectric films are scaled down, it brings about an unavoidable depolarizing field. A partial surface charge compensation allows to control the residual depolarizing field and manipulate the properties of ultrathin ferroelectric films. In this dissertation we take advantage of atomistic first-principles-based simulations to expand our understanding of the role of the partial surface charge compensation in the properties of ferroelectric and antiferroelectric ultrathin films. The application of our computational methodology to study the effect of the partial surface charge compensation in ferroelectric ultrathin films led to the prediction that, depending on the quality of the surface charge compensation, ferroelectric thin films respond to an electric field in a qualitatively different manner. They can be tuned to behave like a linear dielectric, a ferroelectric or even an antiferroelectric. This effect was shown to exist in films with different mechanical boundary conditions and different crystal symmetries. There are a number of potential applications where such properties of ferroelectric thin films can be used. One of these potential applications is energy storage. We will show that, in the antiferroelectric regime, ferroelectric thin films exhibit drastic enhancement of energy storage density which is a desirable property. One of the most promising applications of ferroelectric ultrathin films that emerged only recently is the harvesting of the giant electrocaloric effect. Interestingly, despite numerous studies of the electrocaloric effect in ferroelectric thin films, it is presently unknown how a residual depolarizing field affects the electrocaloric properties of such films. Application of state-of-the-art computational methods to investigate the electrocaloric effect in ferroelectric films with partial surface charge compensation led to the prediction that the residual depolarizing field can perform a dual role in the electrocaloric effect in these films. When the depolarizing field creates competition between the monodomain and nanodomain states, we predict an enhancement of the electrocaloric effect due to the frustration that increases the entropy of the state and therefore the electrocaloric temperature change. On the other hand, when the depolarizing field leads to a formation of nanodomains, thin films either exhibit a small electrocaloric effect or lose their electrocaloric properties altogether to the irreversible nanodomain motion. When the residual depolarizing field is weak enough to permit the formation of monodomain phases, the electrocaloric effect is significantly reduced as compared to bulk. We believe that our findings could potentially reveal additional opportunities to optimize solid state cooling technology. While the electrocaloric effect has been a popular topic of interest in recent years [12], there still exists numerous gaps in the fundamental understanding of the effect. In particular, it is presently unknown whether the scaling laws, known to exist for magnetocaloric materials, can be applied to ferroelectric and antiferroelectric electrocalorics. We predict the existence of scaling laws for low-field electrocaloric temperature change in antiferroelectric and ferroelectric materials. With the help of first-principles-based simulations, we showed computationally that the scaling laws exist for antiferroelectric PbZrO3 along with ferroelectrics PbTiO3, BaTiO 3 and KNbO3. Additional evidence of the scaling laws existence are provided using experimental data from the literature. Interestingly, our studies on ferroelectric films predicted the existence of antiferroelectric behavior in ultrathin films with partial surface charge compensation. One may wonder whether it is possible to stabilize the ferroelectric phase in antiferroelectric films and what role the surface charge screening would play in such a transition. Motivated to address these fundamental questions, we used computational experiments to study antiferroelectric ultrathin films with a residual depolarizing field. Our studies led to the following predictions. We found that PbZrO3 thin films exhibit the ferroelectric phase upon scaling down and under the condition of efficient surface charge compensation. We also found a strong competition between the antiferroelectric and ferroelectric phases for the thin films of the critical size associated with antiferroelectric-ferroelectric phase transition. This finding motivated us to study the electrocaloric effect in PbZrO3 thin films with antiferroelectric-ferroelectric phase competition. We found that high tunability of the phase transition by the electric field leads to a wide range of temperatures associated with a strong electrocaloric effect. In addition, we found that epitaxial strain provides further tunability to the electrocaloric properties. In summary, our studies led to a broader and deeper understanding of the abundantly many roles surface charge compensation plays in ultrathin ferroelectrics and antiferroelectrics.

Nanophase change for data storage applications.

PubMed

Shi, L P; Chong, T C

2007-01-01

Phase change materials are widely used for date storage. The most widespread and important applications are rewritable optical disc and Phase Change Random Access Memory (PCRAM), which utilizes the light and electric induced phase change respectively. For decades, miniaturization has been the major driving force to increase the density. Now the working unit area of the current data storage media is in the order of nano-scale. On the nano-scale, extreme dimensional and nano-structural constraints and the large proportion of interfaces will cause the deviation of the phase change behavior from that of bulk. Hence an in-depth understanding of nanophase change and the related issues has become more and more important. Nanophase change can be defined as: phase change at the scale within nano range of 100 nm, which is size-dependent, interface-dominated and surrounding materials related. Nanophase change can be classified into two groups, thin film related and structure related. Film thickness and clapping materials are key factors for thin film type, while structure shape, size and surrounding materials are critical parameters for structure type. In this paper, the recent development of nanophase change is reviewed, including crystallization of small element at nano size, thickness dependence of crystallization, effect of clapping layer on the phase change of phase change thin film and so on. The applications of nanophase change technology on data storage is introduced, including optical recording such as super lattice like optical disc, initialization free disc, near field, super-RENS, dual layer, multi level, probe storage, and PCRAM including, superlattice-like structure, side edge structure, and line type structure. Future key research issues of nanophase change are also discussed.

Lack of exercise leads to significant and reversible loss of scale invariance in both aged and young mice.

PubMed

Gu, Changgui; Coomans, Claudia P; Hu, Kun; Scheer, Frank A J L; Stanley, H Eugene; Meijer, Johanna H

2015-02-24

In healthy humans and other animals, behavioral activity exhibits scale invariance over multiple timescales from minutes to 24 h, whereas in aging or diseased conditions, scale invariance is usually reduced significantly. Accordingly, scale invariance can be a potential marker for health. Given compelling indications that exercise is beneficial for mental and physical health, we tested to what extent a lack of exercise affects scale invariance in young and aged animals. We studied six or more mice in each of four age groups (0.5, 1, 1.5, and 2 y) and observed an age-related deterioration of scale invariance in activity fluctuations. We found that limiting the amount of exercise, by removing the running wheels, leads to loss of scale-invariant properties in all age groups. Remarkably, in both young and old animals a lack of exercise reduced the scale invariance in activity fluctuations to the same level. We next showed that scale invariance can be restored by returning the running wheels. Exercise during the active period also improved scale invariance during the resting period, suggesting that activity during the active phase may also be beneficial for the resting phase. Finally, our data showed that exercise had a stronger influence on scale invariance than the effect of age. The data suggest that exercise is beneficial as revealed by scale-invariant parameters and that, even in young animals, a lack of exercise leads to strong deterioration in these parameters.

Phase-field Model for Interstitial Loop Growth Kinetics and Thermodynamic and Kinetic Models of Irradiated Fe-Cr Alloys

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

Li, Yulan; Hu, Shenyang Y.; Sun, Xin

2011-06-15

Microstructure evolution kinetics in irradiated materials has strongly spatial correlation. For example, void and second phases prefer to nucleate and grow at pre-existing defects such as dislocations, grain boundaries, and cracks. Inhomogeneous microstructure evolution results in inhomogeneity of microstructure and thermo-mechanical properties. Therefore, the simulation capability for predicting three dimensional (3-D) microstructure evolution kinetics and its subsequent impact on material properties and performance is crucial for scientific design of advanced nuclear materials and optimal operation conditions in order to reduce uncertainty in operational and safety margins. Very recently the meso-scale phase-field (PF) method has been used to predict gas bubblemore » evolution, void swelling, void lattice formation and void migration in irradiated materials,. Although most results of phase-field simulations are qualitative due to the lake of accurate thermodynamic and kinetic properties of defects, possible missing of important kinetic properties and processes, and the capability of current codes and computers for large time and length scale modeling, the simulations demonstrate that PF method is a promising simulation tool for predicting 3-D heterogeneous microstructure and property evolution, and providing microstructure evolution kinetics for higher scale level simulations of microstructure and property evolution such as mean field methods. This report consists of two parts. In part I, we will present a new phase-field model for predicting interstitial loop growth kinetics in irradiated materials. The effect of defect (vacancy/interstitial) generation, diffusion and recombination, sink strength, long-range elastic interaction, inhomogeneous and anisotropic mobility on microstructure evolution kinetics is taken into account in the model. The model is used to study the effect of elastic interaction on interstitial loop growth kinetics, the interstitial flux, and sink strength of interstitial loop for interstitials. In part II, we present a generic phase field model and discuss the thermodynamic and kinetic properties in phase-field models including the reaction kinetics of radiation defects and local free energy of irradiated materials. In particular, a two-sublattice thermodynamic model is suggested to describe the local free energy of alloys with irradiated defects. Fe-Cr alloy is taken as an example to explain the required thermodynamic and kinetic properties for quantitative phase-field modeling. Finally the great challenges in phase-field modeling will be discussed.« less

Multi-scale imaging and elastic simulation of carbonates

NASA Astrophysics Data System (ADS)

Faisal, Titly Farhana; Awedalkarim, Ahmed; Jouini, Mohamed Soufiane; Jouiad, Mustapha; Chevalier, Sylvie; Sassi, Mohamed

2016-05-01

Digital Rock Physics (DRP) is an emerging technology that can be used to generate high quality, fast and cost effective special core analysis (SCAL) properties compared to conventional experimental techniques and modeling techniques. The primary workflow of DRP conssits of three elements: 1) image the rock sample using high resolution 3D scanning techniques (e.g. micro CT, FIB/SEM), 2) process and digitize the images by segmenting the pore and matrix phases 3) simulate the desired physical properties of the rocks such as elastic moduli and velocities of wave propagation. A Finite Element Method based algorithm, that discretizes the basic Hooke's Law equation of linear elasticity and solves it numerically using a fast conjugate gradient solver, developed by Garboczi and Day [1] is used for mechanical and elastic property simulations. This elastic algorithm works directly on the digital images by treating each pixel as an element. The images are assumed to have periodic constant-strain boundary condition. The bulk and shear moduli of the different phases are required inputs. For standard 1.5" diameter cores however the Micro-CT scanning reoslution (around 40 μm) does not reveal smaller micro- and nano- pores beyond the resolution. This results in an unresolved "microporous" phase, the moduli of which is uncertain. Knackstedt et al. [2] assigned effective elastic moduli to the microporous phase based on self-consistent theory (which gives good estimation of velocities for well cemented granular media). Jouini et al. [3] segmented the core plug CT scan image into three phases and assumed that micro porous phase is represented by a sub-extracted micro plug (which too was scanned using Micro-CT). Currently the elastic numerical simulations based on CT-images alone largely overpredict the bulk, shear and Young's modulus when compared to laboratory acoustic tests of the same rocks. For greater accuracy of numerical simulation prediction, better estimates of moduli inputs for this current unresolved phase is important. In this work we take a multi-scale imaging approach by first extracting a smaller 0.5" core and scanning at approx 13 µm, then further extracting a 5mm diameter core scanned at 5 μm. From this last scale, region of interests (containing unresolved areas) are identified for scanning at higher resolutions using Focalised Ion Beam (FIB/SEM) scanning technique reaching 50 nm resolution. Numerical simulation is run on such a small unresolved section to obtain a better estimate of the effective moduli which is then used as input for simulations performed using CT-images. Results are compared with expeirmental acoustic test moduli obtained also at two scales: 1.5" and 0.5" diameter cores.

Hydrodynamic effects on phase separation morphologies in evaporating thin films of polymer solutions

NASA Astrophysics Data System (ADS)

Zoumpouli, Garyfalia A.; Yiantsios, Stergios G.

2016-08-01

We examine effects of hydrodynamics on phase separation morphologies developed during drying of thin films containing a volatile solvent and two dissolved polymers. Cahn-Hilliard and Flory-Huggins theories are used to describe the free energy of the phase separating systems. The thin films, considered as Newtonian fluids, flow in response to Korteweg stresses arising due to concentration non-uniformities that develop during solvent evaporation. Numerical simulations are employed to investigate the effects of a Peclet number, defined in terms of system physical properties, as well as the effects of parameters characterizing the speed of evaporation and preferential wetting of the solutes at the gas interface. For systems exhibiting preferential wetting, diffusion alone is known to favor lamellar configurations for the separated phases in the dried film. However, a mechanism of hydrodynamic instability of a short length scale is revealed, which beyond a threshold Peclet number may deform and break the lamellae. The critical Peclet number tends to decrease as the evaporation rate increases and to increase with the tendency of the polymers to selectively wet the gas interface. As the Peclet number increases, the instability moves closer to the gas interface and induces the formation of a lateral segregation template that guides the subsequent evolution of the phase separation process. On the other hand, for systems with no preferential wetting or any other property asymmetries between the two polymers, diffusion alone favors the formation of laterally separated configurations. In this case, concentration perturbation modes that lead to enhanced Korteweg stresses may be favored for sufficiently large Peclet numbers. For such modes, a second mechanism is revealed, which is similar to the solutocapillary Marangoni instability observed in evaporating solutions when interfacial tension increases with the concentration of the non-volatile component. This mechanism may lead to multiple length scales in the laterally phase separated configurations.

Investigation of Biogrout processes by numerical analysis at pore scale

NASA Astrophysics Data System (ADS)

Bergwerff, Luke; van Paassen, Leon A.; Picioreanu, Cristian; van Loosdrecht, Mark C. M.

2013-04-01

Biogrout is a soil improving process that aims to improve the strength of sandy soils. The process is based on microbially induced calcite precipitation (MICP). In this study the main process is based on denitrification facilitated by bacteria indigenous to the soil using substrates, which can be derived from pretreated waste streams containing calcium salts of fatty acids and calcium nitrate, making it a cost effective and environmentally friendly process. The goal of this research is to improve the understanding of the process by numerical analysis so that it may be improved and applied properly for varying applications, such as borehole stabilization, liquefaction prevention, levee fortification and mitigation of beach erosion. During the denitrification process there are many phases present in the pore space including a liquid phase containing solutes, crystals, bacteria forming biofilms and gas bubbles. Due to the amount of phases and their dynamic changes (multiphase flow with (non-linear) reactive transport), there are many interactions making the process very complex. To understand this complexity in the system, the interactions between these phases are studied in a reductionist approach, increasing the complexity of the system by one phase at a time. The model will initially include flow, solute transport, crystal nucleation and growth in 2D at pore scale. The flow will be described by Navier-Stokes equations. Initial study and simulations has revealed that describing crystal growth for this application on a fixed grid can introduce significant fundamental errors. Therefore a level set method will be employed to better describe the interface of developing crystals in between sand grains. Afterwards the model will be expanded to 3D to provide more realistic flow, nucleation and clogging behaviour at pore scale. Next biofilms and lastly gas bubbles may be added to the model. From the results of these pore scale models the behaviour of the system may be studied and eventually observations may be extrapolated to a larger continuum scale.

Producing a scale-invariant spectrum of perturbations in a Hagedorn phase of string cosmology.

PubMed

Nayeri, Ali; Brandenberger, Robert H; Vafa, Cumrun

2006-07-14

We study the generation of cosmological perturbations during the Hagedorn phase of string gas cosmology. Using tools of string thermodynamics we provide indications that it may be possible to obtain a nearly scale-invariant spectrum of cosmological fluctuations on scales which are of cosmological interest today. In our cosmological scenario, the early Hagedorn phase of string gas cosmology goes over smoothly into the radiation-dominated phase of standard cosmology, without having a period of cosmological inflation.

Magnetization reversal and confinement effects across the metamagnetic phase transition in mesoscale FeRh structures

NASA Astrophysics Data System (ADS)

Ander Arregi, Jon; Horký, Michal; Fabianová, Kateřina; Tolley, Robert; Fullerton, Eric E.; Uhlíř, Vojtěch

2018-03-01

The effects of mesoscale confinement on the metamagnetic behavior of lithographically patterned FeRh structures are investigated via Kerr microscopy. Combining the temperature- and field-dependent magnetization reversal of individual sub-micron FeRh structures provides specific phase-transition characteristics of single mesoscale objects. Relaxation of the epitaxial strain caused by patterning lowers the metamagnetic phase transition temperature by more than 15 K upon confining FeRh films below 500 nm in one lateral dimension. We also observe that the phase transition becomes highly asymmetric when comparing the cooling and heating cycles for 300 nm-wide FeRh structures. The investigation of FeRh under lateral confinement provides an interesting platform to explore emergent metamagnetic phenomena arising from the interplay of the structural, magnetic and electronic degrees of freedom at the mesoscopic length scale.

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

Armstrong, Clare L; Barrett, M; Heiss, Arno

Inelastic neutron scattering was used to study the effect of 5 and 40 mol% cholesterol on the lateral nanoscale dynamics of phospholipid membranes. By measuring the excitation spectrum at several lateral q || values (up to q || = 3 1), complete dispersion curves were determined of gel, fluid and liquid-ordered phase bilayers. The inclusion of cholesterol had a distinct effect on the collective dynamics of the bilayer s hydrocarbon chains; specifically, we observed a pronounced stiffening of the membranes on the nanometer length scale in both gel and fluid bilayers, even though they were experiencing a higher degree ofmore » molecular disorder. Also, for the first time we determined the nanoscale dynamics in the high-cholesterol liquid-ordered phase of bilayers containing cholesterol. Namely, this phase appears to be softer than fluid bilayers, but better ordered than bilayers in the gel phase.« less

Mesoscale evolution of voids and microstructural changes in HMX-based explosives during heating through the β-δ phase transition

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

Willey, Trevor M., E-mail: willey1@llnl.gov; Lauderbach, Lisa; Gagliardi, Franco

HMX-based explosives LX-10 and PBX-9501 were heated through the β-δ phase transition. Ultra-small angle x-ray scattering (USAXS) and molecular diffraction were simultaneously recorded as the HMX was heated. Mesoscale voids and structure dramatically change promptly with the β-δ phase transition, rather than with other thermal effects. Also, x-ray induced damage, observed in the USAXS, occurs more readily at elevated temperatures; as such, the dose was reduced to mitigate this effect. Optical microscopy performed during a similar heating cycle gives an indication of changes on longer length scales, while x-ray microtomography, performed before and after heating, shows the character of extensivemore » microstructural damage resulting from the temperature cycle and solid-state phase transition.« less

Mesoscale evolution of voids and microstructural changes in HMX-based explosives during heating through the β-δ phase transition

DOE PAGES

Willey, Trevor M.; Lauderbach, Lisa; Gagliardi, Franco; ...

2015-08-07

HMX-based explosives LX-10 and PBX-9501 were heated through the β-δ phase transition. Ultra-small angle x-ray scattering (USAXS) and molecular diffraction were simultaneously recorded as the HMX was heated. Mesoscale voids and structure dramatically change promptly with the β-δ phase transition, rather than with other thermal effects. Also, x-ray induced damage, observed in the USAXS, occurs more readily at elevated temperatures; as such, the dose was reduced to mitigate this effect. Optical microscopy performed during a similar heating cycle gives an indication of changes on longer length scales, while x-ray microtomography, performed before and after heating, shows the character of extensivemore » microstructural damage resulting from the temperature cycle and solid-state phase transition.« less

Nanoscale Properties of Rocks and Subduction Zone Rheology: Inferences for the Mechanisms of Deep Earthquakes

NASA Astrophysics Data System (ADS)

Riedel, M. R.

2007-12-01

Grain boundaries are the key for the understanding of mineral reaction kinetics. More generally, nanometer scale processes involved in breaking and establishing bonds at reaction sites determine how and at which rate bulk rock properties change in response to external tectonic forcing and possibly feed back into various geodynamic processes. A particular problem is the effects of grain-boundary energy on the kinetics of the olivine-spinel phase transformation in subducting slabs. Slab rheology is affected in many ways by this (metastable) mineral phase change. Sluggish kinetics due to metastable hindrance is likely to cause particular difficulties, because of possible strong non-linear feedback loops between strain-rate and change of creep properties during transformation. In order to get these nanoscale properties included into thermo-mechanical models, reliable kinetic data is required. The measurement of grain-boundary energies is, however, a rather difficult problem. Conventional methods of grain boundary surface tension measurement include (a) equilibrium angles at triple junction (b) rotating ball method (c) thermal groove method, and others (Gottstein & Shvindlerman, 1999). Here I suggest a new method that allows for the derivation of grain-boundary energies for an isochemical phase transformation based on experimental (in-situ) kinetic data in combination with a corresponding dynamic scaling law (Riedel and Karato, 1997). The application of this method to the olivine-spinel phase transformation in subducting slabs provides a solution to the extrapolation problem of measured kinetic data: Any kinetic phase boundary measured at the laboratory time scale can be "scaled" to the correct critical isotherm at subduction zones, under experimentelly "forbidden" conditions (Liou et al., 2000). Consequences for the metastability hypothesis that relates deep seismicity with olivine metastability are derived and discussed. References: Gottstein G, Shvindlerman LS (1999) Grain Boundary Migration in Metals, CRC Press, 385 pp., New York. Riedel MR, Karato S (1997) Grain-Size Evolution in Subducted Oceanic Lithosphere Associated with the Olivine- Spinel Transformation and Its Effects on Rheology. EPSL 148: 27-43. Liou JG, Hacker BR, Zhang RY (2000) Into the forbidden zone. Science 287, 1215-1216.

Negative refraction of elastic waves at the deep-subwavelength scale in a single-phase metamaterial.

PubMed

Zhu, R; Liu, X N; Hu, G K; Sun, C T; Huang, G L

2014-11-24

Negative refraction of elastic waves has been studied and experimentally demonstrated in three- and two-dimensional phononic crystals, but Bragg scattering is impractical for low-frequency wave control because of the need to scale the structures to manageable sizes. Here we present an elastic metamaterial with chiral microstructure made of a single-phase solid material that aims to achieve subwavelength negative refraction of elastic waves. Both negative effective mass density and modulus are observed owing to simultaneous translational and rotational resonances. We experimentally demonstrate negative refraction of the longitudinal elastic wave at the deep-subwavelength scale in the metamaterial fabricated in a stainless steel plate. The experimental measurements are in good agreement with numerical simulations. Moreover, wave mode conversion related with negative refraction is revealed and discussed. The proposed elastic metamaterial may thus be used as a flat lens for elastic wave focusing.

Continuous Easy-Plane Deconfined Phase Transition on the Kagome Lattice

NASA Astrophysics Data System (ADS)

Zhang, Xue-Feng; He, Yin-Chen; Eggert, Sebastian; Moessner, Roderich; Pollmann, Frank

2018-03-01

We use large scale quantum Monte Carlo simulations to study an extended Hubbard model of hard core bosons on the kagome lattice. In the limit of strong nearest-neighbor interactions at 1 /3 filling, the interplay between frustration and quantum fluctuations leads to a valence bond solid ground state. The system undergoes a quantum phase transition to a superfluid phase as the interaction strength is decreased. It is still under debate whether the transition is weakly first order or represents an unconventional continuous phase transition. We present a theory in terms of an easy plane noncompact C P1 gauge theory describing the phase transition at 1 /3 filling. Utilizing large scale quantum Monte Carlo simulations with parallel tempering in the canonical ensemble up to 15552 spins, we provide evidence that the phase transition is continuous at exactly 1 /3 filling. A careful finite size scaling analysis reveals an unconventional scaling behavior hinting at deconfined quantum criticality.

Metabolic Profiling of Geobacter sulfurreducens during Industrial Bioprocess Scale-Up.

PubMed

Muhamadali, Howbeer; Xu, Yun; Ellis, David I; Allwood, J William; Rattray, Nicholas J W; Correa, Elon; Alrabiah, Haitham; Lloyd, Jonathan R; Goodacre, Royston

2015-05-15

During the industrial scale-up of bioprocesses it is important to establish that the biological system has not changed significantly when moving from small laboratory-scale shake flasks or culturing bottles to an industrially relevant production level. Therefore, during upscaling of biomass production for a range of metal transformations, including the production of biogenic magnetite nanoparticles by Geobacter sulfurreducens, from 100-ml bench-scale to 5-liter fermentors, we applied Fourier transform infrared (FTIR) spectroscopy as a metabolic fingerprinting approach followed by the analysis of bacterial cell extracts by gas chromatography-mass spectrometry (GC-MS) for metabolic profiling. FTIR results clearly differentiated between the phenotypic changes associated with different growth phases as well as the two culturing conditions. Furthermore, the clustering patterns displayed by multivariate analysis were in agreement with the turbidimetric measurements, which displayed an extended lag phase for cells grown in a 5-liter bioreactor (24 h) compared to those grown in 100-ml serum bottles (6 h). GC-MS analysis of the cell extracts demonstrated an overall accumulation of fumarate during the lag phase under both culturing conditions, coinciding with the detected concentrations of oxaloacetate, pyruvate, nicotinamide, and glycerol-3-phosphate being at their lowest levels compared to other growth phases. These metabolites were overlaid onto a metabolic network of G. sulfurreducens, and taking into account the levels of these metabolites throughout the fermentation process, the limited availability of oxaloacetate and nicotinamide would seem to be the main metabolic bottleneck resulting from this scale-up process. Additional metabolite-feeding experiments were carried out to validate the above hypothesis. Nicotinamide supplementation (1 mM) did not display any significant effects on the lag phase of G. sulfurreducens cells grown in the 100-ml serum bottles. However, it significantly improved the growth behavior of cells grown in the 5-liter bioreactor by reducing the lag phase from 24 h to 6 h, while providing higher yield than in the 100-ml serum bottles. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

N = 2 → 0 super no-scale models and moduli quantum stability

NASA Astrophysics Data System (ADS)

Kounnas, Costas; Partouche, Hervé

2017-06-01

We consider a class of heterotic N = 2 → 0 super no-scale Z2-orbifold models. An appropriate stringy Scherk-Schwarz supersymmetry breaking induces tree level masses to all massless bosons of the twisted hypermultiplets and therefore stabilizes all twisted moduli. At high supersymmetry breaking scale, the tachyons that occur in the N = 4 → 0 parent theories are projected out, and no Hagedorn-like instability takes place in the N = 2 → 0 models (for small enough marginal deformations). At low supersymmetry breaking scale, the stability of the untwisted moduli is studied at the quantum level by taking into account both untwisted and twisted contributions to the 1-loop effective potential. The latter depends on the specific branch of the gauge theory along which the background can be deformed. We derive its expression in terms of all classical marginal deformations in the pure Coulomb phase, and in some mixed Coulomb/Higgs phases. In this class of models, the super no-scale condition requires having at the massless level equal numbers of untwisted bosonic and twisted fermionic degrees of freedom. Finally, we show that N = 1 → 0 super no-scale models are obtained by implementing a second Z2 orbifold twist on N = 2 → 0 super no-scale Z2-orbifold models.

Cannabis for dyskinesia in Parkinson disease: a randomized double-blind crossover study.

PubMed

Carroll, C B; Bain, P G; Teare, L; Liu, X; Joint, C; Wroath, C; Parkin, S G; Fox, P; Wright, D; Hobart, J; Zajicek, J P

2004-10-12

The long-term treatment of Parkinson disease (PD) may be complicated by the development of levodopa-induced dyskinesia. Clinical and animal model data support the view that modulation of cannabinoid function may exert an antidyskinetic effect. The authors conducted a randomized, double-blind, placebo-controlled crossover trial to examine the hypothesis that cannabis may have a beneficial effect on dyskinesia in PD. A 4-week dose escalation study was performed to assess the safety and tolerability of cannabis in six PD patients with levodopa-induced dyskinesia. Then a randomized placebo-controlled crossover study (RCT) was performed, in which 19 PD patients were randomized to receive oral cannabis extract followed by placebo or vice versa. Each treatment phase lasted for 4 weeks with an intervening 2-week washout phase. The primary outcome measure was a change in Unified Parkinson's Disease Rating Scale (UPDRS) (items 32 to 34) dyskinesia score. Secondary outcome measures included the Rush scale, Bain scale, tablet arm drawing task, and total UPDRS score following a levodopa challenge, as well as patient-completed measures of a dyskinesia activities of daily living (ADL) scale, the PDQ-39, on-off diaries, and a range of category rating scales. Seventeen patients completed the RCT. Cannabis was well tolerated, and had no pro- or antiparkinsonian action. There was no evidence for a treatment effect on levodopa-induced dyskinesia as assessed by the UPDRS, or any of the secondary outcome measures. Orally administered cannabis extract resulted in no objective or subjective improvement in dyskinesias or parkinsonism.

A didactic and hands-on module enhances resident microsurgical knowledge and technical skill.

PubMed

El Ahmadieh, Tarek Y; Aoun, Salah G; El Tecle, Najib E; Nanney, Allan D; Daou, Marc R; Harrop, James; Batjer, Hunt H; Bendok, Bernard R

2013-10-01

Simulation has been adopted as a powerful training tool in many areas of health care. However, it has not yet been systematically embraced in neurosurgery because of the absence of validated tools, assessment scales, and curricula. To use our validated microanastomosis module and scale to evaluate the effects of an educational intervention on the performance of neurosurgery residents at the 2012 Congress of Neurological Surgeons Annual Meeting. The module consisted of an end-to-end microanastomosis of a 3-mm vessel and was divided into 3 phases: (1) a cognitive and microsuture prelecture testing phase, (2) a didactic lecture, and (3) a cognitive and microsuture postlecture testing phase. We compared resident knowledge and technical proficiency from the pretesting and posttesting phases. One neurosurgeon and 7 neurosurgery residents participated in the study. None had previous experience in microsurgery. The average score on the microsuture prelecture and postlecture tests, as measured by our assessment scale, was 32.50 and 39.75, respectively (P = .001). The number of completed sutures at the end of each procedure was higher for 75% of participants in the postlecture testing phase (P = .03). The average score on the cognitive postlecture test (12.75) was significantly better than that of the cognitive prelecture test (8.38; P = .001). Simulation has the potential to enhance resident education and to elevate proficiency levels. Our data suggest that a focused microsurgical module that incorporates a didactic component and a technical component can enhance resident knowledge and technical proficiency in microsurgical anastomosis.

Statistical analysis of corn yields responding to climate variability at various spatio-temporal resolutions

NASA Astrophysics Data System (ADS)

Jiang, H.; Lin, T.

2017-12-01

Rain-fed corn production systems are subject to sub-seasonal variations of precipitation and temperature during the growing season. As each growth phase has varied inherent physiological process, plants necessitate different optimal environmental conditions during each phase. However, this temporal heterogeneity towards climate variability alongside the lifecycle of crops is often simplified and fixed as constant responses in large scale statistical modeling analysis. To capture the time-variant growing requirements in large scale statistical analysis, we develop and compare statistical models at various spatial and temporal resolutions to quantify the relationship between corn yield and weather factors for 12 corn belt states from 1981 to 2016. The study compares three spatial resolutions (county, agricultural district, and state scale) and three temporal resolutions (crop growth phase, monthly, and growing season) to characterize the effects of spatial and temporal variability. Our results show that the agricultural district model together with growth phase resolution can explain 52% variations of corn yield caused by temperature and precipitation variability. It provides a practical model structure balancing the overfitting problem in county specific model and weak explanation power in state specific model. In US corn belt, precipitation has positive impact on corn yield in growing season except for vegetative stage while extreme heat attains highest sensitivity from silking to dough phase. The results show the northern counties in corn belt area are less interfered by extreme heat but are more vulnerable to water deficiency.

Open-label dose optimization of methylphenidate modified release long acting (MPH-LA): a post hoc analysis of real-life titration from a 40-week randomized trial.

PubMed

Huss, Michael; Ginsberg, Ylva; Arngrim, Torben; Philipsen, Alexandra; Carter, Katherine; Chen, Chien-Wei; Gandhi, Preetam; Kumar, Vinod

2014-09-01

In the management of attention-deficit hyperactivity disorder (ADHD) in adults it is important to recognize that individual patients respond to a wide range of methylphenidate doses. Studies with methylphenidate modified release long acting (MPH-LA) in children have reported the need for treatment optimization for improved outcomes. We report the results from a post hoc analysis of a 5-week dose optimization phase from a large randomized, placebo-controlled, multicenter 40-week study (9-week double-blind dose confirmation phase, 5-week open-label dose optimization phase, and 26-week double-blind maintenance of effect phase). Patients entering the open-label dose optimization phase initiated treatment with MPH-LA 20 mg/day; up/down titrated to their optimal dose (at which there was balance between control of symptoms and side effects) of 40, 60, or 80 mg/day in increments of 20 mg/week by week 12 or 13. Safety was assessed by monitoring the adverse events (AEs) and serious AEs. Efficacy was assessed by the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, Attention-Deficit Hyperactivity Disorder Rating Scale (DSM-IV ADHD RS) and Sheehan Disability Scale (SDS) total scores. At the end of the dose confirmation phase, similar numbers of patients were treated optimally with each of the 40, 60, and 80 mg/day doses (152, 177, and 160, respectively) for MPH-LA. Mean improvement from baseline in the dose confirmation phase in total scores of DSM-IV ADHD RS and SDS were 23.5 ± 9.90 and 9.7 ± 7.36, respectively. Dose optimization with MPH-LA (40, 60, or 80 mg/day) improved treatment outcomes and was well-tolerated in adult ADHD patients.

The Effect of Peer Education upon Breast Self-Examination Behaviors and Self-Esteem among University Students

PubMed Central

Ayran, Gulsun; Fırat, Meryem; Kucukakca, Gulden; Cuneydioğlu, Beyazıt; Tahta, Kubra; Avcı, Esra

2017-01-01

Objective The current study was semi-experimentally designed in order to identify the effect of peer education upon breast self-examination (BSE) behaviors and self-esteem among university students. Materials and methods The study was undertaken with 100 female students who studied at Erzincan University. Peer educators were recruited from the 4th year students. The data were collected with a questionnaire form, BSE skill form and Rosenberg Self-esteem Scale in two phases one month before and after the BSE peer education. For the data assessment; percentage distributions, frequency, mean, standard deviation and Simple T test were employed. Results The mean age of the participant students was 20.45±1.67 year and all of them were single. It was found that during the first data collection phase, only 16 % of the students performed BSE while during the final data collection phase, the rate of the students performing BSE rose to 77 %. During the first data collection phase, students received a mean score of 2.36±4.13 from BSE skill form while during the last data collection phase they had a mean score of 10.70±3.40 from BSE skill form. When the scores obtained from Rosenberg Self-esteem Scale by the students were examined, it was seen that they received a mean score of 1.20±1.34 during the first data collection phase while they had a mean score of 0.84±1.07 during the final data collection phase. Conclusion Although short-term feedback was obtained, it was noted that students’ BSE knowledge and skills increased considerably. PMID:28894853

The Effects of Reinvestment of Conscious Processing on Switching Focus of Attention

ERIC Educational Resources Information Center

Weiss, Stephen M.

2011-01-01

The effects of switching focusing strategies on complex motor skill learning were investigated using a dart-throwing task. Participants were screened for reinvestment of conscious processing by completing the Reinvestment Scale (RS) of Masters, Polman, and Hammond (1993). After an initial baseline phase, two focusing strategies were described. Low…

Investigating the Effectiveness of Computer Simulations for Chemistry Learning

ERIC Educational Resources Information Center

Plass, Jan L.; Milne, Catherine; Homer, Bruce D.; Schwartz, Ruth N.; Hayward, Elizabeth O.; Jordan, Trace; Verkuilen, Jay; Ng, Florrie; Wang, Yan; Barrientos, Juan

2012-01-01

Are well-designed computer simulations an effective tool to support student understanding of complex concepts in chemistry when integrated into high school science classrooms? We investigated scaling up the use of a sequence of simulations of kinetic molecular theory and associated topics of diffusion, gas laws, and phase change, which we designed…

Effect of station-specific alerting and ramp-up tones on firefighters' alarm time heart rates.

PubMed

MacNeal, James J; Cone, David C; Wistrom, Christopher L

2016-11-01

A number of long-term health effects are suffered by emergency responders, some influenced by psychological stress and fatigue. This study explored if stress and fatigue can be reduced by changing the method by which firefighters are alerted to emergency responses. Over several months, the method by which responders at a fire department were alerted was altered. Firefighter heart rates were measured first with standard alerting as a control (phase 1: all stations alerted simultaneously, with high-volume tones). The department then implemented station-specific (phase 2) and gradual volume ramp-up (phase 3) tone alerting, and heart rate increases were compared. The Fatigue Severity Score was used to examine firefighter fatigue, and the department administered a follow-up survey on personnel preferences. Individual heart rate increases (Δbpm) ranged from 2-48 bpm. Median increases were 7 bpm (IQR 4-11 bpm) during phase 1 (72.2% of alarms Δbpm<10), 7 bpm (IQR 5-12 bpm) during phase 2 (60.7% of alarms Δbpm<10), and 5 bpm (IQR 3-8 bpm) during phase 3 (82.7% of alarms Δbpm<10). The difference in medians was lower for phases 1 and 2 than for phase 3 (p = 0.0069), and more alarms in phase 3 resulted in increases of <10 bpm than in phase 2 (p = 0.0089). The Fatigue Severity Scale showed little variability: median scores 7 in phase 1, 8 in phase 2, and 7 in phase 3. Firefighters reported a strong preference for the "ramp-up" tones, and were roughly evenly divided between preferring alerting all stations simultaneously 24/7 (40% rating this 4 or 5 on a five-point Likert scale), station-specific alerting 24/7 (47.5%), or all stations during the day but station-specific at night (40%). Ramp-up tones were perceived as the best method to reduce stress during the day and overnight. Small but significant decreases in the amount of tachycardic response to station alerting are associated with simple alterations in alerting methods. Station-specific and ramp-up tones improve perceived working conditions for emergency responders.

Stochastic dynamics and combinatorial optimization

NASA Astrophysics Data System (ADS)

Ovchinnikov, Igor V.; Wang, Kang L.

2017-11-01

Natural dynamics is often dominated by sudden nonlinear processes such as neuroavalanches, gamma-ray bursts, solar flares, etc., that exhibit scale-free statistics much in the spirit of the logarithmic Ritcher scale for earthquake magnitudes. On phase diagrams, stochastic dynamical systems (DSs) exhibiting this type of dynamics belong to the finite-width phase (N-phase for brevity) that precedes ordinary chaotic behavior and that is known under such names as noise-induced chaos, self-organized criticality, dynamical complexity, etc. Within the recently proposed supersymmetric theory of stochastic dynamics, the N-phase can be roughly interpreted as the noise-induced “overlap” between integrable and chaotic deterministic dynamics. As a result, the N-phase dynamics inherits the properties of the both. Here, we analyze this unique set of properties and conclude that the N-phase DSs must naturally be the most efficient optimizers: on one hand, N-phase DSs have integrable flows with well-defined attractors that can be associated with candidate solutions and, on the other hand, the noise-induced attractor-to-attractor dynamics in the N-phase is effectively chaotic or aperiodic so that a DS must avoid revisiting solutions/attractors thus accelerating the search for the best solution. Based on this understanding, we propose a method for stochastic dynamical optimization using the N-phase DSs. This method can be viewed as a hybrid of the simulated and chaotic annealing methods. Our proposition can result in a new generation of hardware devices for efficient solution of various search and/or combinatorial optimization problems.

Higher-order phase transitions on financial markets

NASA Astrophysics Data System (ADS)

Kasprzak, A.; Kutner, R.; Perelló, J.; Masoliver, J.

2010-08-01

Statistical and thermodynamic properties of the anomalous multifractal structure of random interevent (or intertransaction) times were thoroughly studied by using the extended continuous-time random walk (CTRW) formalism of Montroll, Weiss, Scher, and Lax. Although this formalism is quite general (and can be applied to any interhuman communication with nontrivial priority), we consider it in the context of a financial market where heterogeneous agent activities can occur within a wide spectrum of time scales. As the main general consequence, we found (by additionally using the Saddle-Point Approximation) the scaling or power-dependent form of the partition function, Z(q'). It diverges for any negative scaling powers q' (which justifies the name anomalous) while for positive ones it shows the scaling with the general exponent τ(q'). This exponent is the nonanalytic (singular) or noninteger power of q', which is one of the pilar of higher-order phase transitions. In definition of the partition function we used the pausing-time distribution (PTD) as the central one, which takes the form of convolution (or superstatistics used, e.g. for describing turbulence as well as the financial market). Its integral kernel is given by the stretched exponential distribution (often used in disordered systems). This kernel extends both the exponential distribution assumed in the original version of the CTRW formalism (for description of the transient photocurrent measured in amorphous glassy material) as well as the Gaussian one sometimes used in this context (e.g. for diffusion of hydrogen in amorphous metals or for aging effects in glasses). Our most important finding is the third- and higher-order phase transitions, which can be roughly interpreted as transitions between the phase where high frequency trading is most visible and the phase defined by low frequency trading. The specific order of the phase transition directly depends upon the shape exponent α defining the stretched exponential integral kernel. On this basis a simple practical hint for investors was formulated.

Observing a scale anomaly and a universal quantum phase transition in graphene.

PubMed

Ovdat, O; Mao, Jinhai; Jiang, Yuhang; Andrei, E Y; Akkermans, E

2017-09-11

One of the most interesting predictions resulting from quantum physics, is the violation of classical symmetries, collectively referred to as anomalies. A remarkable class of anomalies occurs when the continuous scale symmetry of a scale-free quantum system is broken into a discrete scale symmetry for a critical value of a control parameter. This is an example of a (zero temperature) quantum phase transition. Such an anomaly takes place for the quantum inverse square potential known to describe 'Efimov physics'. Broken continuous scale symmetry into discrete scale symmetry also appears for a charged and massless Dirac fermion in an attractive 1/r Coulomb potential. The purpose of this article is to demonstrate the universality of this quantum phase transition and to present convincing experimental evidence of its existence for a charged and massless fermion in an attractive Coulomb potential as realized in graphene.When the continuous scale symmetry of a quantum system is broken, anomalies occur which may lead to quantum phase transitions. Here, the authors provide evidence for such a quantum phase transition in the attractive Coulomb potential of vacancies in graphene, and further envision its universality for diverse physical systems.

Impact of temporal, spatial and cascaded effects on the pulse formation in ultra-broadband parametric amplifiers.

PubMed

Lang, T; Harth, A; Matyschok, J; Binhammer, T; Schultze, M; Morgner, U

2013-01-14

A 2 + 1 dimensional nonlinear pulse propagation model is presented, illustrating the weighting of different effects for the parametric amplification of ultra-broadband spectra in different regimes of energy scaling. Typical features in the distribution of intensity and phase of state-of-the-art OPA-systems can be understood by cascaded spatial and temporal effects.

MSE wall void repair effect on corrosion of reinforcement - phase 2 : specialty fill materials.

DOT National Transportation Integrated Search

2015-08-01

This project provided information and recommendations for material selection for best : corrosion control of reinforcement in mechanically stabilized earth (MSE) walls with void repairs. The : investigation consisted of small- and large-scale experim...

Do they actually work across borders? Evaluation of two measures of psychological distress as screening instruments in a non Anglo-Saxon country.

PubMed

Carrà, G; Sciarini, P; Segagni-Lusignani, G; Clerici, M; Montomoli, C; Kessler, R C

2011-03-01

Screening scales can be useful in searching for common mental disorders in primary care and in tracking relevant prevalence and correlates in community surveys. However, it is important to document their validity, before using them. We developed Italian versions of the widely-used K10 and K6 screening scales following the WHO forward-translation and back-translation protocol. To evaluate their effectiveness as screens for DSM-IV 12-month mood or anxiety disorders and "serious mental illness" (SMI), the scales were validated in a two-stage clinical reappraisal survey. In the first-phase, the scales were administered to 605 people. In the second-phase, a sub-sample of 147 first-phase respondents over-sampling screened positives was administered the 12-month version of the Structured Clinical Interview for DSM-IV Axis I Disorders as a clinical gold standard. Performance of the scales in screening for chosen disorders was assessed by calculating area under the receiver operating characteristic curve and stratum-specific likelihood ratios. Both the K10 and K6 performed well in detecting DSM-IV mood disorders, anxiety disorders, and serious mental illness (SMI), with areas under the curve (AUCs) (95% CIs) between 0.82 (0.75-0.89) and 0.91 (0.85-0.96). The Italian versions of the K6 and K10 scales have good psychometric properties, making them attractive inexpensive screens for mood disorders, anxiety disorders, and SMI. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

Heterogeneous fuel for hybrid rocket

NASA Technical Reports Server (NTRS)

Stickler, David B. (Inventor)

1996-01-01

Heterogeneous fuel compositions suitable for use in hybrid rocket engines and solid-fuel ramjet engines, The compositions include mixtures of a continuous phase, which forms a solid matrix, and a dispersed phase permanently distributed therein. The dispersed phase or the matrix vaporizes (or melts) and disperses into the gas flow much more rapidly than the other, creating depressions, voids and bumps within and on the surface of the remaining bulk material that continuously roughen its surface, This effect substantially enhances heat transfer from the combusting gas flow to the fuel surface, producing a correspondingly high burning rate, The dispersed phase may include solid particles, entrained liquid droplets, or gas-phase voids having dimensions roughly similar to the displacement scale height of the gas-flow boundary layer generated during combustion.

Galaxy clusters in the context of superfluid dark matter

NASA Astrophysics Data System (ADS)

Hodson, Alistair O.; Zhao, Hongsheng; Khoury, Justin; Famaey, Benoit

2017-11-01

Context. The mass discrepancy in the Universe has not been solved by the cold dark matter (CDM) or the modified Newtonian dynamics (MOND) paradigms so far. The problems and solutions of either scenario are mutually exclusive on large and small scales. It has recently been proposed, by assuming that dark matter is a superfluid, that MOND-like effects can be achieved on small scales whilst preserving the success of ΛCDM on large scales. Detailed models within this "superfluid dark matter" (SfDM) paradigm are yet to be constructed. Aims: Here, we aim to provide the first set of spherical models of galaxy clusters in the context of SfDM. We aim to determine whether the superfluid formulation is indeed sufficient to explain the mass discrepancy in galaxy clusters. Methods: The SfDM model is defined by two parameters. Λ can be thought of as a mass scale in the Lagrangian of the scalar field that effectively describes the phonons, and it acts as a coupling constant between the phonons and baryons. m is the mass of the DM particles. Based on these parameters, we outline the theoretical structure of the superfluid core and the surrounding "normal-phase" dark halo of quasi-particles. The latter are thought to encompass the largest part of galaxy clusters. Here, we set the SfDM transition at the radius where the density and pressure of the superfluid and normal phase coincide, neglecting the effect of phonons in the superfluid core. We then apply the formalism to a sample of galaxy clusters, and directly compare the SfDM predicted mass profiles to data. Results: We find that the superfluid formulation can reproduce the X-ray dynamical mass profile of clusters reasonably well, but with a slight under-prediction of the gravity in the central regions. This might be partly related to our neglecting of the effect of phonons in these regions. Two normal-phase halo profiles are tested, and it is found that clusters are better defined by a normal-phase halo resembling an Navarro-Frenk-White-like structure than an isothermal profile. Conclusions: In this first exploratory work on the topic, we conclude that depending on the amount of baryons present in the central galaxy and on the actual effect of phonons in the inner regions, this superfluid formulation could be successful in describing galaxy clusters. In the future, our model could be made more realistic by exploring non-sphericity and a more realistic SfDM to normal phase transition. The main result of this study is an estimate of the order of magnitude of the theory parameters for the superfluid formalism to be reasonably consistent with clusters. These values will have to be compared to the true values needed in galaxies.

Full-scale system impact analysis: Digital document storage project

NASA Technical Reports Server (NTRS)

1989-01-01

The Digital Document Storage Full Scale System can provide cost effective electronic document storage, retrieval, hard copy reproduction, and remote access for users of NASA Technical Reports. The desired functionality of the DDS system is highly dependent on the assumed requirements for remote access used in this Impact Analysis. It is highly recommended that NASA proceed with a phased, communications requirement analysis to ensure that adequate communications service can be supplied at a reasonable cost in order to validate recent working assumptions upon which the success of the DDS Full Scale System is dependent.

Universality from disorder in the random-bond Blume-Capel model

NASA Astrophysics Data System (ADS)

Fytas, N. G.; Zierenberg, J.; Theodorakis, P. E.; Weigel, M.; Janke, W.; Malakis, A.

2018-04-01

Using high-precision Monte Carlo simulations and finite-size scaling we study the effect of quenched disorder in the exchange couplings on the Blume-Capel model on the square lattice. The first-order transition for large crystal-field coupling is softened to become continuous, with a divergent correlation length. An analysis of the scaling of the correlation length as well as the susceptibility and specific heat reveals that it belongs to the universality class of the Ising model with additional logarithmic corrections which is also observed for the Ising model itself if coupled to weak disorder. While the leading scaling behavior of the disordered system is therefore identical between the second-order and first-order segments of the phase diagram of the pure model, the finite-size scaling in the ex-first-order regime is affected by strong transient effects with a crossover length scale L*≈32 for the chosen parameters.

Field-scale multi-phase LNAPL remediation: Validating a new computational framework against sequential field pilot trials.

PubMed

Sookhak Lari, Kaveh; Johnston, Colin D; Rayner, John L; Davis, Greg B

2018-03-05

Remediation of subsurface systems, including groundwater, soil and soil gas, contaminated with light non-aqueous phase liquids (LNAPLs) is challenging. Field-scale pilot trials of multi-phase remediation were undertaken at a site to determine the effectiveness of recovery options. Sequential LNAPL skimming and vacuum-enhanced skimming, with and without water table drawdown were trialled over 78days; in total extracting over 5m 3 of LNAPL. For the first time, a multi-component simulation framework (including the multi-phase multi-component code TMVOC-MP and processing codes) was developed and applied to simulate the broad range of multi-phase remediation and recovery methods used in the field trials. This framework was validated against the sequential pilot trials by comparing predicted and measured LNAPL mass removal rates and compositional changes. The framework was tested on both a Cray supercomputer and a cluster. Simulations mimicked trends in LNAPL recovery rates (from 0.14 to 3mL/s) across all remediation techniques each operating over periods of 4-14days over the 78day trial. The code also approximated order of magnitude compositional changes of hazardous chemical concentrations in extracted gas during vacuum-enhanced recovery. The verified framework enables longer term prediction of the effectiveness of remediation approaches allowing better determination of remediation endpoints and long-term risks. Copyright © 2017 Commonwealth Scientific and Industrial Research Organisation. Published by Elsevier B.V. All rights reserved.

Long-wave equivalent viscoelastic solids for porous rocks saturated by two-phase fluids

NASA Astrophysics Data System (ADS)

Santos, J. E.; Savioli, G. B.

2018-04-01

Seismic waves traveling across fluid-saturated poroelastic materials with mesoscopic-scale heterogeneities induce fluid flow and Biot's slow waves generating energy loss and velocity dispersion. Using Biot's equations of motion to model these type of heterogeneities would require extremely fine meshes. We propose a numerical upscaling procedure to determine the complex and frequency dependent P-wave and shear moduli of an effective viscoelastic medium long-wave equivalent to a poroelastic solid saturated by a two-phase fluid. The two-phase fluid is defined in terms of capillary pressure and relative permeability flow functions. The P-wave and shear effective moduli are determined using harmonic compressibility and shear experiments applied on representative samples of the bulk material. Each experiment is associated with a boundary value problem that is solved using the finite element method. Since a poroelastic solid saturated by a two-phase fluid supports the existence of two slow waves, this upscaling procedure allows to analyze their effect on the mesoscopic-loss mechanism in hydrocarbon reservoir formations. Numerical results show that a two-phase Biot medium model predicts higher attenuation than classic Biot models.

Bioremediation of diesel fuel contaminated soil: effect of non ionic surfactants and selected bacteria addition.

PubMed

Collina, Elena; Lasagni, Marina; Pitea, Demetrio; Franzetti, Andrea; Di Gennaro, Patrizia; Bestetti, Giuseppina

2007-09-01

Aim of this work was to evaluate influence of two commercial surfactants and inoculum of selected bacteria on biodegradation of diesel fuel in different systems. Among alkyl polyethossilates (Brij family) and sorbitan derivates (Tween family) a first selection of surfactants was performed by estimation of Koc and Dafnia magna EC50 with molecular descriptor and QSAR model. Further experiments were conducted to evaluate soil sorption, biodegradability and toxicity. In the second part of the research, the effect of Brij 56, Tween 80 and selected bacteria addition on biodegradation of diesel fuel was studied in liquid cultures and in slurry and solid phase systems. The latter experiments were performed with diesel contaminated soil in bench scale slurry phase bioreactor and solid phase columns. Tween 80 addition increased the biodegradation rate of hydrocarbons both in liquid and in slurry phase systems. Regarding the effect of inoculum, no enhancement of biodegradation rate was observed neither in surfactant added nor in experiments without addition. On the contrary, in solid phase experiments, inoculum addition resulted in enhanced biodegradation compared to surfactant addition.

Long-wave equivalent viscoelastic solids for porous rocks saturated by two-phase fluids

NASA Astrophysics Data System (ADS)

Santos, J. E.; Savioli, G. B.

2018-07-01

Seismic waves travelling across fluid-saturated poroelastic materials with mesoscopic-scale heterogeneities induce fluid flow and Biot's slow waves generating energy loss and velocity dispersion. Using Biot's equations of motion to model these type of heterogeneities would require extremely fine meshes. We propose a numerical upscaling procedure to determine the complex and frequency-dependent Pwave and shear moduli of an effective viscoelastic medium long-wave equivalent to a poroelastic solid saturated by a two-phase fluid. The two-phase fluid is defined in terms of capillary pressure and relative permeability flow functions. The Pwave and shear effective moduli are determined using harmonic compressibility and shear experiments applied on representative samples of the bulk material. Each experiment is associated with a boundary value problem that is solved using the finite element method. Since a poroelastic solid saturated by a two-phase fluid supports the existence of two slow waves, this upscaling procedure allows to analyse their effect on the mesoscopic loss mechanism in hydrocarbon reservoir formations. Numerical results show that a two-phase Biot medium model predicts higher attenuation than classic Biot models.

Pre-transition effects mediate forces of assembly between transmembrane proteins

DOE PAGES

Katira, Shachi; Mandadapu, Kranthi K.; Vaikuntanathan, Suriyanarayanan; ...

2016-02-24

We present a mechanism for a generic, powerful force of assembly and mobility for transmembrane proteins in lipid bilayers. This force is a pre-transition (or pre-melting) effect for the first-order transition between ordered and disordered phases in the membrane. Using large-scale molecular simulation, we show that a protein with hydrophobic thickness equal to that of the disordered phase embedded in an ordered bilayer stabilizes a microscopic order–disorder interface. The stiffness of that interface is finite. When two such proteins approach each other, they assemble because assembly reduces the net interfacial energy. Analogous to the hydrophobic effect, we refer to thismore » phenomenon as the 'orderphobic effect'. The effect is mediated by proximity to the order–disorder phase transition and the size and hydrophobic mismatch of the protein. The strength and range of forces arising from this effect are significantly larger than those that could arise from membrane elasticity for the membranes considered.« less

Pre-transition effects mediate forces of assembly between transmembrane proteins

PubMed Central

Katira, Shachi; Mandadapu, Kranthi K; Vaikuntanathan, Suriyanarayanan; Smit, Berend; Chandler, David

2016-01-01

We present a mechanism for a generic, powerful force of assembly and mobility for transmembrane proteins in lipid bilayers. This force is a pre-transition (or pre-melting) effect for the first-order transition between ordered and disordered phases in the membrane. Using large-scale molecular simulation, we show that a protein with hydrophobic thickness equal to that of the disordered phase embedded in an ordered bilayer stabilizes a microscopic order–disorder interface. The stiffness of that interface is finite. When two such proteins approach each other, they assemble because assembly reduces the net interfacial energy. Analogous to the hydrophobic effect, we refer to this phenomenon as the 'orderphobic effect'. The effect is mediated by proximity to the order–disorder phase transition and the size and hydrophobic mismatch of the protein. The strength and range of forces arising from this effect are significantly larger than those that could arise from membrane elasticity for the membranes considered. DOI: http://dx.doi.org/10.7554/eLife.13150.001 PMID:26910009

Pre-transition effects mediate forces of assembly between transmembrane proteins

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

Katira, Shachi; Mandadapu, Kranthi K.; Vaikuntanathan, Suriyanarayanan

We present a mechanism for a generic, powerful force of assembly and mobility for transmembrane proteins in lipid bilayers. This force is a pre-transition (or pre-melting) effect for the first-order transition between ordered and disordered phases in the membrane. Using large-scale molecular simulation, we show that a protein with hydrophobic thickness equal to that of the disordered phase embedded in an ordered bilayer stabilizes a microscopic order–disorder interface. The stiffness of that interface is finite. When two such proteins approach each other, they assemble because assembly reduces the net interfacial energy. Analogous to the hydrophobic effect, we refer to thismore » phenomenon as the 'orderphobic effect'. The effect is mediated by proximity to the order–disorder phase transition and the size and hydrophobic mismatch of the protein. The strength and range of forces arising from this effect are significantly larger than those that could arise from membrane elasticity for the membranes considered.« less

Genetic drift and collective dispersal can result in chaotic genetic patchiness.

PubMed

Broquet, Thomas; Viard, Frédérique; Yearsley, Jonathan M

2013-06-01

Chaotic genetic patchiness denotes unexpected patterns of genetic differentiation that are observed at a fine scale and are not stable in time. These patterns have been described in marine species with free-living larvae, but are unexpected because they occur at a scale below the dispersal range of pelagic larvae. At the scale where most larvae are immigrants, theory predicts spatially homogeneous, temporally stable genetic variation. Empirical studies have suggested that genetic drift interacts with complex dispersal patterns to create chaotic genetic patchiness. Here we use a co-ancestry model and individual-based simulations to test this idea. We found that chaotic genetic patterns (qualified by global FST and spatio-temporal variation in FST's between pairs of samples) arise from the combined effects of (1) genetic drift created by the small local effective population sizes of the sessile phase and variance in contribution among breeding groups and (2) collective dispersal of related individuals in the larval phase. Simulations show that patchiness levels qualitatively comparable to empirical results can be produced by a combination of strong variance in reproductive success and mild collective dispersal. These results call for empirical studies of the effective number of breeders producing larval cohorts, and population genetics at the larval stage. © 2012 The Author(s). Evolution © 2012 The Society for the Study of Evolution.

Angle-adjustable density field formulation for the modeling of crystalline microstructure

NASA Astrophysics Data System (ADS)

Wang, Zi-Le; Liu, Zhirong; Huang, Zhi-Feng

2018-05-01

A continuum density field formulation with particle-scale resolution is constructed to simultaneously incorporate the orientation dependence of interparticle interactions and the rotational invariance of the system, a fundamental but challenging issue in modeling the structure and dynamics of a broad range of material systems across variable scales. This generalized phase field crystal-type approach is based upon the complete expansion of particle direct correlation functions and the concept of isotropic tensors. Through applications to the modeling of various two- and three-dimensional crystalline structures, our study demonstrates the capability of bond-angle control in this continuum field theory and its effects on the emergence of ordered phases, and provides a systematic way of performing tunable angle analyses for crystalline microstructures.

Self-organized criticality in sandpiles - Nature of the critical phenomenon. [dynamic models in phase transition

NASA Technical Reports Server (NTRS)

Carlson, J. M.; Chayes, J. T.; Swindle, G. H.; Grannan, E. R.

1990-01-01

The scaling behavior of sandpile models is investigated analytically. First, it is shown that sandpile models contain a set of domain walls, referred to as troughs, which bound regions that can experience avalanches. It is further shown that the dynamics of the troughs is governed by a simple set of rules involving birth, death, and coalescence events. A simple trough model is then introduced, and it is proved that the model has a phase transition with the density of the troughs as an order parameter and that, in the thermodynamic limit, the trough density goes to zero at the transition point. Finally, it is shown that the observed scaling behavior is a consequence of finite-size effects.

Effects of learning-style environmental and tactal/kinesthetic preferences on the understanding of scientific terms and attitude test scores of fifth-grade students

NASA Astrophysics Data System (ADS)

Sullivan, Angela Tirino

This investigator analyzed the effects of learning-style environmental and tactual/kinesthetic preferences on the understanding of scientific terms and attitude test scores of fifth-grade students. To identify individual preferences, the Learning-Styles Inventory (Dunn, Dunn & Price, 1996) was administered to students who attended a suburban elementary school. Forty-six general education students were given instruction through the gradual establishment of an environmentally- and perceptually-responsive learning-style classroom. Instructional units were divided into three phases of two weeks each. The units of scientific terms were instructed for varied learning-style preferences and were gradually introduced during these instructional phases: Phase 1: Electricity was taught with traditional teaching methods; Phase 2: The Source of Energy was taught with accommodations for sound, light, temperature, design elements; Phase 3: Pollution was taught with accommodations for tactual/kinesthetic modalities. Pre and Post-tests, were administered in each of the three phases to determine scientific term gains. A repeated measures ANOVA and General Linear Model were employed to compare mean gains from phase to phase. Post-hoc comparisons were performed using the Bonferroni method and similar procedures were conducted on the Semantic Differential Scales (Pizzo, 1981). Correlations of relative gain scores during each phase were assessed by means of Pearson-product-moment correlations. Differences in the strengths of correlated correlations were evaluated by means of t-tests for related correlation coefficients. Significant gains were found when students were instructed employing incremental learning-styles strategies. To determine attitudinal changes toward science terms, the Semantic Differential Scale (Pizzo, 1981) was administered three times throughout this study: after Phase 1, traditional teaching; Phases 2 and 3, after learning-styles intervention. Statistically higher significance was achieved in both achievement (p < .001) and attitude (p < .001) as each sequential phase was introduced. Thus, the more the instruction and environment responded to students' instructional learning-styles, the better they performed and the more they liked learning. These data confirmed the importance of matching learning-styles with complementary instructional strategies and environments.

Unfitted Two-Phase Flow Simulations in Pore-Geometries with Accurate

NASA Astrophysics Data System (ADS)

Heimann, Felix; Engwer, Christian; Ippisch, Olaf; Bastian, Peter

2013-04-01

The development of better macro scale models for multi-phase flow in porous media is still impeded by the lack of suitable methods for the simulation of such flow regimes on the pore scale. The highly complicated geometry of natural porous media imposes requirements with regard to stability and computational efficiency which current numerical methods fail to meet. Therefore, current simulation environments are still unable to provide a thorough understanding of porous media in multi-phase regimes and still fail to reproduce well known effects like hysteresis or the more peculiar dynamics of the capillary fringe with satisfying accuracy. Although flow simulations in pore geometries were initially the domain of Lattice-Boltzmann and other particle methods, the development of Galerkin methods for such applications is important as they complement the range of feasible flow and parameter regimes. In the recent past, it has been shown that unfitted Galerkin methods can be applied efficiently to topologically demanding geometries. However, in the context of two-phase flows, the interface of the two immiscible fluids effectively separates the domain in two sub-domains. The exact representation of such setups with multiple independent and time depending geometries exceeds the functionality of common unfitted methods. We present a new approach to pore scale simulations with an unfitted discontinuous Galerkin (UDG) method. Utilizing a recursive sub-triangulation algorithm, we extent the UDG method to setups with multiple independent geometries. This approach allows an accurate representation of the moving contact line and the interface conditions, i.e. the pressure jump across the interface. Example simulations in two and three dimensions illustrate and verify the stability and accuracy of this approach.

Deformation of the quintom cosmological model and its consequences

NASA Astrophysics Data System (ADS)

Sadeghi, J.; Pourhassan, B.; Nekouee, Z.; Shokri, M.

In this paper, we investigate the effects of noncommutative phase-space on the quintom cosmological model. In that case, we discuss about some cosmological parameters and show that they depend on the deformation parameters. We find that the noncommutative parameter plays important role which helps to re-arrange the divergency of cosmological constant. We draw time-dependent scale factor and investigate the effect of noncommutative parameters. Finally, we take advantage from noncommutative phase-space and obtain the deformed Lagrangian for the quintom model. In order to discuss some cosmological phenomena as dark energy and inflation, we employ Noether symmetry.

Mesoscopic fluctuations in biharmonically driven flux qubits

NASA Astrophysics Data System (ADS)

Ferrón, Alejandro; Domínguez, Daniel; Sánchez, María José

2017-01-01

We investigate flux qubits driven by a biharmonic magnetic signal, with a phase lag that acts as an effective time reversal broken parameter. The driving induced transition rate between the ground and the excited state of the flux qubit can be thought of as an effective transmittance, profiting from a direct analogy between interference effects at avoided level crossings and scattering events in disordered electronic systems. For time scales prior to full relaxation, but large compared to the decoherence time, this characteristic rate has been accessed experimentally by Gustavsson et al. [Phys. Rev. Lett. 110, 016603 (2013)], 10.1103/PhysRevLett.110.016603 and its sensitivity with both the phase lag and the dc flux detuning explored. In this way, signatures of universal conductance fluctuationslike effects have been analyzed and compared with predictions from a phenomenological model that only accounts for decoherence, as a classical noise. Here we go beyond the classical noise model and solve the full dynamics of the driven flux qubit in contact with a quantum bath employing the Floquet-Born-Markov master equation. Within this formalism, the computed relaxation and decoherence rates turn out to be strongly dependent on both the phase lag and the dc flux detuning. Consequently, the associated pattern of fluctuations in the characteristic rates display important differences with those obtained within the mentioned phenomenological model. In particular, we demonstrate the weak localizationlike effect in the average values of the relaxation rate. Our predictions can be tested for accessible but longer time scales than the current experimental times.

A multi-scale network method for two-phase flow in porous media

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

Khayrat, Karim, E-mail: khayratk@ifd.mavt.ethz.ch; Jenny, Patrick

Pore-network models of porous media are useful in the study of pore-scale flow in porous media. In order to extract macroscopic properties from flow simulations in pore-networks, it is crucial the networks are large enough to be considered representative elementary volumes. However, existing two-phase network flow solvers are limited to relatively small domains. For this purpose, a multi-scale pore-network (MSPN) method, which takes into account flow-rate effects and can simulate larger domains compared to existing methods, was developed. In our solution algorithm, a large pore network is partitioned into several smaller sub-networks. The algorithm to advance the fluid interfaces withinmore » each subnetwork consists of three steps. First, a global pressure problem on the network is solved approximately using the multiscale finite volume (MSFV) method. Next, the fluxes across the subnetworks are computed. Lastly, using fluxes as boundary conditions, a dynamic two-phase flow solver is used to advance the solution in time. Simulation results of drainage scenarios at different capillary numbers and unfavourable viscosity ratios are presented and used to validate the MSPN method against solutions obtained by an existing dynamic network flow solver.« less

Minimizing N2O emissions and carbon footprint on a full-scale activated sludge sequencing batch reactor.

PubMed

Rodriguez-Caballero, A; Aymerich, I; Marques, Ricardo; Poch, M; Pijuan, M

2015-03-15

A continuous, on-line quantification of the nitrous oxide (N2O) emissions from a full-scale sequencing batch reactor (SBR) placed in a municipal wastewater treatment plant (WWTP) was performed in this study. In general, N2O emissions from the biological wastewater treatment system were 97.1 ± 6.9 g N2O-N/Kg [Formula: see text] consumed or 6.8% of the influent [Formula: see text] load. In the WWTP of this study, N2O emissions accounted for over 60% of the total carbon footprint of the facility, on average. Different cycle configurations were implemented in the SBR aiming at reaching acceptable effluent values. Each cycle configuration consisted of sequences of aerated and non-aerated phases of different time length being controlled by the ammonium set-point fixed. Cycles with long aerated phases showed the largest N2O emissions, with the consequent increase in carbon footprint. Cycle configurations with intermittent aeration (aerated phases up to 20-30 min followed by short anoxic phases) were proven to effectively reduce N2O emissions, without compromising nitrification performance or increasing electricity consumption. This is the first study in which a successful operational strategy for N2O mitigation is identified at full-scale. Copyright © 2014 Elsevier Ltd. All rights reserved.

Electroacoustic dewatering of food and other suspensions

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

Kim, B.C.; Zelinski, M.S.; Criner, C.L.

1989-05-31

The food processing industry is a large user of energy for evaporative drying due to limited effectiveness of conventional mechanical dewatering machines. Battelle's Electroacoustic Dewatering (EAD) process improves the performance of mechanical dewatering machines by superimposing electric and ultrasonic fields. A two phase development program to demonstrate the benefits of EAD was carried out in cooperation with the food processing industry, the National Food Processors Association (NFPA) and two equipment vendors. In Phase I, laboratory scale studies were carried out on a variety of food suspensions. The process was scaled up to small commercial scale in Phase II. The technicalmore » feasibility of EAD for a variety of food materials, without adversely affecting the food properties, was successfully demonstrated during this phase, which is the subject of this report. Two Process Research Units (PRUs) were designed and built through joint efforts between Battelle and two equipment vendors. A 0.5-meter wide belt press was tested on apple mash, corn fiber, and corn gluten at sites provided by two food processors. A high speed citrus juice finisher (a hybrid form of screw press and centrifuge) was tested on orange pulp. These tests were carried out jointly by Battelle, equipment vendors, NFPA, and food processors. The apple and citrus juice products were analyzed by food processors and NFPA. 26 figs., 30 tabs.« less

Topological Quantum Phase Transition in Synthetic Non-Abelian Gauge Potential: Gauge Invariance and Experimental Detections

PubMed Central

Sun, Fadi; Yu, Xiao-Lu; Ye, Jinwu; Fan, Heng; Liu, Wu-Ming

2013-01-01

The method of synthetic gauge potentials opens up a new avenue for our understanding and discovering novel quantum states of matter. We investigate the topological quantum phase transition of Fermi gases trapped in a honeycomb lattice in the presence of a synthetic non-Abelian gauge potential. We develop a systematic fermionic effective field theory to describe a topological quantum phase transition tuned by the non-Abelian gauge potential and explore its various important experimental consequences. Numerical calculations on lattice scales are performed to compare with the results achieved by the fermionic effective field theory. Several possible experimental detection methods of topological quantum phase transition are proposed. In contrast to condensed matter experiments where only gauge invariant quantities can be measured, both gauge invariant and non-gauge invariant quantities can be measured by experimentally generating various non-Abelian gauges corresponding to the same set of Wilson loops. PMID:23846153

The effects of RCS jet firing on the isolated Orbiter and mated coast phases of the glide return to launch site maneuver at Mach number 6 (IA302B)

NASA Technical Reports Server (NTRS)

Garrett, L. V.; Buchanan, T. D.; Fryberger, P. E.

1988-01-01

An updated Space Shuttle aerodynamic data base was obtained in Tunnel B for two phases of the Glide Return to Launch Site (GRTLS) abort maneuver. One-and-a-quarter percent scale models of the Space Shuttle Orbiter and External Tank were used to measure the effects of various combinations of Reaction Control System (RCS) jet thrusters at Mach number 6. The angle-of-attack range for the isolated orbiter was -10 to 15 deg at sideslip angles from -5 to 10 deg during Phase 1 of testing. The angle-of-attack range for the mated orbiter and external tank was -5 to 15 deg with sideslip angles of -2 to 5 deg during Phase 2. The test was conducted at a unit Reynolds number of 0.75 million per foot.

Intrahemispheric theta rhythm desynchronization impairs working memory.

PubMed

Alekseichuk, Ivan; Pabel, Stefanie Corinna; Antal, Andrea; Paulus, Walter

2017-01-01

There is a growing interest in large-scale connectivity as one of the crucial factors in working memory. Correlative evidence has revealed the anatomical and electrophysiological players in the working memory network, but understanding of the effective role of their connectivity remains elusive. In this double-blind, placebo-controlled study we aimed to identify the causal role of theta phase connectivity in visual-spatial working memory. The frontoparietal network was over- or de-synchronized in the anterior-posterior direction by multi-electrode, 6 Hz transcranial alternating current stimulation (tACS). A decrease in memory performance and increase in reaction time was caused by frontoparietal intrahemispheric desynchronization. According to the diffusion drift model, this originated in a lower signal-to-noise ratio, known as the drift rate index, in the memory system. The EEG analysis revealed a corresponding decrease in phase connectivity between prefrontal and parietal areas after tACS-driven desynchronization. The over-synchronization did not result in any changes in either the behavioral or electrophysiological levels in healthy participants. Taken together, we demonstrate the feasibility of manipulating multi-site large-scale networks in humans, and the disruptive effect of frontoparietal desynchronization on theta phase connectivity and visual-spatial working memory.

Farsi version of social skills rating system-secondary student form: cultural adaptation, reliability and construct validity.

PubMed

Eslami, Ahmad Ali; Amidi Mazaheri, Maryam; Mostafavi, Firoozeh; Abbasi, Mohamad Hadi; Noroozi, Ensieh

2014-01-01

Assessment of social skills is a necessary requirement to develop and evaluate the effectiveness of cognitive and behavioral interventions. This paper reports the cultural adaptation and psychometric properties of the Farsi version of the social skills rating system-secondary students form (SSRS-SS) questionnaire (Gresham and Elliot, 1990), in a normative sample of secondary school students. A two-phase design was used that phase 1 consisted of the linguistic adaptation and in phase 2, using cross-sectional sample survey data, the construct validity and reliability of the Farsi version of the SSRS-SS were examined in a sample of 724 adolescents aged from 13 to 19 years. Content validity index was excellent, and the floor/ceiling effects were low. After deleting five of the original SSRS-SS items, the findings gave support for the item convergent and divergent validity. Factor analysis revealed four subscales. RESULTS showed good internal consistency (0.89) and temporal stability (0.91) for the total scale score. Findings demonstrated support for the use of the 27-item Farsi version in the school setting. Directions for future research regarding the applicability of the scale in other settings and populations of adolescents are discussed.

Scale-dependent coupling of hysteretic capillary pressure, trapping, and fluid mobilities

NASA Astrophysics Data System (ADS)

Doster, F.; Celia, M. A.; Nordbotten, J. M.

2012-12-01

Many applications of multiphase flow in porous media, including CO2-storage and enhanced oil recovery, require mathematical models that span a large range of length scales. In the context of numerical simulations, practical grid sizes are often on the order of tens of meters, thereby de facto defining a coarse model scale. Under particular conditions, it is possible to approximate the sub-grid-scale distribution of the fluid saturation within a grid cell; that reconstructed saturation can then be used to compute effective properties at the coarse scale. If both the density difference between the fluids and the vertical extend of the grid cell are large, and buoyant segregation within the cell on a sufficiently shorte time scale, then the phase pressure distributions are essentially hydrostatic and the saturation profile can be reconstructed from the inferred capillary pressures. However, the saturation reconstruction may not be unique because the parameters and parameter functions of classical formulations of two-phase flow in porous media - the relative permeability functions, the capillary pressure -saturation relationship, and the residual saturations - show path dependence, i.e. their values depend not only on the state variables but also on their drainage and imbibition histories. In this study we focus on capillary pressure hysteresis and trapping and show that the contribution of hysteresis to effective quantities is dependent on the vertical length scale. By studying the transition from the two extreme cases - the homogeneous saturation distribution for small vertical extents and the completely segregated distribution for large extents - we identify how hysteretic capillary pressure at the local scale induces hysteresis in all coarse-scale quantities for medium vertical extents and finally vanishes for large vertical extents. Our results allow for more accurate vertically integrated modeling while improving our understanding of the coupling of capillary pressure and relative permeabilities over larger length scales.

Spin-Hall effect and emergent antiferromagnetic phase transition in n-Si

NASA Astrophysics Data System (ADS)

Lou, Paul C.; Kumar, Sandeep

2018-04-01

Spin current experiences minimal dephasing and scattering in Si due to small spin-orbit coupling and spin-lattice interactions is the primary source of spin relaxation. We hypothesize that if the specimen dimension is of the same order as the spin diffusion length then spin polarization will lead to non-equilibrium spin accumulation and emergent phase transition. In n-Si, spin diffusion length has been reported up to 6 μm. The spin accumulation in Si will modify the thermal transport behavior of Si, which can be detected with thermal characterization. In this study, we report observation of spin-Hall effect and emergent antiferromagnetic phase transition behavior using magneto-electro-thermal transport characterization. The freestanding Pd (1 nm)/Ni80Fe20 (75 nm)/MgO (1 nm)/n-Si (2 μm) thin film specimen exhibits a magnetic field dependent thermal transport and spin-Hall magnetoresistance behavior attributed to Rashba effect. An emergent phase transition is discovered using self-heating 3ω method, which shows a diverging behavior at 270 K as a function of temperature similar to a second order phase transition. We propose that spin-Hall effect leads to the spin accumulation and resulting emergent antiferromagnetic phase transition. We propose that the length scale for Rashba effect can be equal to the spin diffusion length and two-dimensional electron gas is not essential for it. The emergent antiferromagnetic phase transition is attributed to the site inversion asymmetry in diamond cubic Si lattice.

Experimental investigation of supercritical CO 2 trapping mechanisms at the Intermediate Laboratory Scale in well-defined heterogeneous porous media

DOE PAGES

Trevisan, Luca; Pini, Ronny; Cihan, Abdullah; ...

2014-12-31

The heterogeneous nature of typical sedimentary formations can play a major role in the propagation of the CO 2 plume, eventually dampening the accumulation of mobile phase underneath the caprock. From core flooding experiments, it is also known that contrasts in capillary threshold pressure due to different pore size can affect the flow paths of the invading and displaced fluids and consequently influence the build- up of non-wetting phase (NWP) at interfaces between geological facies. The full characterization of the geologic variability at all relevant scales and the ability to make observations on the spatial and temporal distribution of themore » migration and trapping of supercritical CO 2 is not feasible from a practical perspective. To provide insight into the impact of well-defined heterogeneous systems on the flow dynamics and trapping efficiency of supercritical CO 2 under drainage and imbibition conditions, we present an experimental investigation at the meter scale conducted in synthetic sand reservoirs packed in a quasi-two-dimensional flow-cell. Two immiscible displacement experiments have been performed to observe the preferential entrapment of NWP in simple heterogeneous porous media. The experiments consisted of an injection, a fluid redistribution, and a forced imbibition stages conducted in an uncorrelated permeability field and a homogeneous base case scenario. We adopted x-ray attenuation analysis as a non-destructive technique that allows a precise measurement of phase saturations throughout the entire flow domain. By comparing a homogeneous and a heterogeneous scenario we have identified some important effects that can be attributed to capillary barriers, such as dampened plume advancement, higher non-wetting phase saturations, larger contact area between the injected and displaced phases, and a larger range of non-wetting phase saturations.« less

Paliperidone palmitate once-monthly maintains improvement in functioning domains of the Personal and Social Performance scale compared with placebo in subjects with schizoaffective disorder.

PubMed

Fu, Dong-Jing; Turkoz, Ibrahim; Walling, David; Lindenmayer, Jean-Pierre; Schooler, Nina R; Alphs, Larry

2018-02-01

Evaluate the effect of paliperidone palmitate once-monthly (PP1M) injectable on the specific functioning domains of the Personal and Social Performance (PSP) scale in patients with schizoaffective disorder (SCA) participating in a long-term study. This study (NCT01193153) included both in- and outpatient subjects with SCA experiencing an acute exacerbation of psychotic and mood symptoms. Subjects were treated with PP1M either as monotherapy or in combination with antidepressants or mood stabilizers during a 25-week open-label (OL) phase. Stabilized subjects were randomly assigned 1:1 (PP1M or placebo) into a 15-month double-blind (DB) relapse-prevention period. Functioning of the randomized subjects during OL and DB phases was evaluated using the PSP scale (four domains: socially useful activities, personal/social relationships, self-care, and disturbing/aggressive behaviors). Three statistical approaches were utilized to analyze PSP scores to assess robustness and consistency of findings. No adjustments were made for multiplicity. 334 of 667 enrolled subjects were stabilized with PP1M, randomly assigned to PP1M (n=164) or placebo (n=170) in the DB phase, and included in this analysis. Improvements in all PSP domain scores were observed during the OL phase and were maintained during the DB phase with PP1M, but decreased with placebo. Differences compared to placebo were significant in all four PSP domains during the DB phase (P≤0.008). The analysis in this study showed that PP1M improves functioning, as measured by the four PSP domain scores, in symptomatic subjects with SCA. Functioning was maintained compared with placebo. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Dynamic depinning phase transition in magnetic thin film with anisotropy

NASA Astrophysics Data System (ADS)

Xiong, L.; Zheng, B.; Jin, M. H.; Wang, L.; Zhou, N. J.

2018-02-01

The dynamic pinning effects induced by quenched disorder are significant in manipulating the domain-wall motion in nano-magnetic materials. Through numerical simulations of the nonstationary domain-wall dynamics with the Landau-Lifshitz-Gilbert equation, we confidently detect a dynamic depinning phase transition in a magnetic thin film with anisotropy, which is of second order. The transition field, static and dynamic exponents are accurately determined, based on the dynamic scaling behavior far from stationary.

Generic finite size scaling for discontinuous nonequilibrium phase transitions into absorbing states

NASA Astrophysics Data System (ADS)

de Oliveira, M. M.; da Luz, M. G. E.; Fiore, C. E.

2015-12-01

Based on quasistationary distribution ideas, a general finite size scaling theory is proposed for discontinuous nonequilibrium phase transitions into absorbing states. Analogously to the equilibrium case, we show that quantities such as response functions, cumulants, and equal area probability distributions all scale with the volume, thus allowing proper estimates for the thermodynamic limit. To illustrate these results, five very distinct lattice models displaying nonequilibrium transitions—to single and infinitely many absorbing states—are investigated. The innate difficulties in analyzing absorbing phase transitions are circumvented through quasistationary simulation methods. Our findings (allied to numerical studies in the literature) strongly point to a unifying discontinuous phase transition scaling behavior for equilibrium and this important class of nonequilibrium systems.

Timing matters: change depends on the stage of treatment in cognitive behavioral therapy for panic disorder with agoraphobia.

PubMed

Gloster, Andrew T; Klotsche, Jens; Gerlach, Alexander L; Hamm, Alfons; Ströhle, Andreas; Gauggel, Siegfried; Kircher, Tilo; Alpers, Georg W; Deckert, Jürgen; Wittchen, Hans-Ulrich

2014-02-01

The mechanisms of action underlying treatment are inadequately understood. This study examined 5 variables implicated in the treatment of panic disorder with agoraphobia (PD/AG): catastrophic agoraphobic cognitions, anxiety about bodily sensations, agoraphobic avoidance, anxiety sensitivity, and psychological flexibility. The relative importance of these process variables was examined across treatment phases: (a) psychoeducation/interoceptive exposure, (b) in situ exposure, and (c) generalization/follow-up. Data came from a randomized controlled trial of cognitive behavioral therapy for PD/AG (n = 301). Outcomes were the Panic and Agoraphobia Scale (Bandelow, 1995) and functioning as measured in the Clinical Global Impression scale (Guy, 1976). The effect of process variables on subsequent change in outcome variables was calculated using bivariate latent difference score modeling. Change in panic symptomatology was preceded by catastrophic appraisal and agoraphobic avoidance across all phases of treatment, by anxiety sensitivity during generalization/follow-up, and by psychological flexibility during exposure in situ. Change in functioning was preceded by agoraphobic avoidance and psychological flexibility across all phases of treatment, by fear of bodily symptoms during generalization/follow-up, and by anxiety sensitivity during exposure. The effects of process variables on outcomes differ across treatment phases and outcomes (i.e., symptomatology vs. functioning). Agoraphobic avoidance and psychological flexibility should be investigated and therapeutically targeted in addition to cognitive variables. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Impact of Antarctic mixed-phase clouds on climate

DOE PAGES

Lawson, R. Paul; Gettelman, Andrew

2014-12-08

Precious little is known about the composition of low-level clouds over the Antarctic Plateau and their effect on climate. In situ measurements at the South Pole using a unique tethered balloon system and ground-based lidar reveal a much higher than anticipated incidence of low-level, mixed-phase clouds (i.e., consisting of supercooled liquid water drops and ice crystals). The high incidence of mixed-phase clouds is currently poorly represented in global climate models (GCMs). As a result, the effects that mixed-phase clouds have on climate predictions are highly uncertain. In this paper, we modify the National Center for Atmospheric Research (NCAR) Community Earthmore » System Model (CESM) GCM to align with the new observations and evaluate the radiative effects on a continental scale. The net cloud radiative effects (CREs) over Antarctica are increased by +7.4 Wm –2, and although this is a significant change, a much larger effect occurs when the modified model physics are extended beyond the Antarctic continent. The simulations show significant net CRE over the Southern Ocean storm tracks, where recent measurements also indicate substantial regions of supercooled liquid. Finally, these sensitivity tests confirm that Southern Ocean CREs are strongly sensitive to mixed-phase clouds colder than –20 °C.« less

Importance of large-scale bathymetry features on 2011 Tohoku tsunami waveforms through comparison of simulations with the spatially dense ALBACORE OBS array data

NASA Astrophysics Data System (ADS)

Kohler, M. D.; Lynett, P. J.; Legg, M. R.; Weeraratne, D. S.

2012-12-01

In March 2011, a deployment of ocean bottom seismometers (OBSs) off the coast of Southern California recorded the tsunami resulting from the Mw=9.0 Tohoku, Japan earthquake with very high spatial resolution. The ALBACORE (Asthenosphere and Lithosphere Broadband Architecture from the California Offshore Region Experiment) OBS array spanned a region that was 150 km north-south by 400 km east-west, extending into deep open ocean west of the Patton escarpment. In that array, 22 stations with a spacing of 75 km had differential pressure gauges (DPGs) that recorded water pressure waveform data continuously at 50 samples/second. The DPG tsunami records across the entire array show multiple large-amplitude, coherent phases arriving one hour to more than 36 hours after the initial tsunami phase. To determine the source of the large-amplitude coherent phases, gravity ocean wave propagation calculations were carried out for the Pacific Ocean. Simulated pressure waveforms were compared with data for the ALBACORE stations, as well as for the NOAA DART buoys. The linear, non-dispersive shallow-water simulations include bottom frictional effects, and use the USGS NEIC Tohoku slip model and ETOPO2 (two-minute spatial resolution) bathymetry. The predicted travel times of the initial arrivals are found to be less than 1% different from the observed travel times in the southern California ALBACORE DPG data. In order to gauge the effects of large-scale features in Pacific Ocean bathymetry, several large-scale features were individually removed, and simulations were carried out for the modified bathymetry. The removed features include the Emperor Seamount chain, Hawaiian Islands, Oceania, French Polynesia, and the South American coastline. The results show that the removal of these features has an effect on the arrival time of the phases that depends on the feature proximity to the direct path, but their removal does not have a significant effect on the frequency content or phase amplitudes of the waves. The direct paths recorded in Southern California indicate that the tsunami wave did not interfere with distant above-water features such as the Aleutians, but was diffracted around Point Conception in the California coastline and around southern California islands. It is more likely that the scattered phases are the result of wave reflections off the western Japan coastline, or interactions with local structures such as the central-southern California coastline, plateaus beneath the Channel Islands, and the Patton Escarpment.

Interplanetary field and plasma during initial phase of geomagnetic storms

NASA Technical Reports Server (NTRS)

Patel, V. L.; Wiskerchen, M. J.

1975-01-01

A study has been conducted of a large number of geomagnetic storms occurring during the period from 1966 to 1970. Questions of data selection are discussed and the large-scale interplanetary magnetic field during the initial phase is examined. Small-scale interplanetary fields during the initial phase are also considered, taking into account important features of small-scale variations in the interplanetary field and plasma for three storms. Details concerning 23 geomagnetic storms and the interplanetary magnetic field are presented in a table. A study of the initial phase of these storms indicates that in most of these events, the solar-ecliptic Z component of the interplanetary magnetic field turns southward when the main phase decrease begins.

Direct numerical simulation of turbulent channel flow with spanwise alternatively distributed strips control

NASA Astrophysics Data System (ADS)

Ni, Weidan; Lu, Lipeng; Fang, Jian; Moulinec, Charles; Yao, Yufeng

2018-05-01

The effect of spanwise alternatively distributed strips (SADS) control on turbulent flow in a plane channel has been studied by direct numerical simulations to investigate the characteristics of large-scale streamwise vortices (LSSVs) induced by small-scale active wall actuation, and their potential in suppressing flow separation. SADS control is realized by alternatively arranging out-of-phase control (OPC) and in-phase control (IPC) wall actuations on the lower channel wall surface, in the spanwise direction. It is found that the coherent structures are suppressed or enhanced alternatively by OPC or IPC, respectively, leading to the formation of a vertical shear layer, which is responsible for the LSSVs’ presence. Large-scale low-speed region can also be observed above the OPC strips, which resemble large-scale low-speed streaks. LSSVs are found to be in a statistically-converged steady state and their cores are located between two neighboring OPC and IPC strips. Their motions contribute significantly to the momentum transport in the wall-normal and spanwise directions, demonstrating their potential ability to suppress flow separation.

Particle-In-Cell Modeling For MJ Dense Plasma Focus with Varied Anode Shape

NASA Astrophysics Data System (ADS)

Link, A.; Halvorson, C.; Schmidt, A.; Hagen, E. C.; Rose, D.; Welch, D.

2014-10-01

Megajoule scale dense plasma focus (DPF) Z-pinches with deuterium gas fill are compact devices capable of producing 1012 neutrons per shot but past predictive models of large-scale DPF have not included kinetic effects such as ion beam formation or anomalous resistivity. We report on progress of developing a predictive DPF model by extending our 2D axisymmetric collisional kinetic particle-in-cell (PIC) simulations to the 1 MJ, 2 MA Gemini DPF using the PIC code LSP. These new simulations incorporate electrodes, an external pulsed-power driver circuit, and model the plasma from insulator lift-off through the pinch phase. The simulations were performed using a new hybrid fluid-to-kinetic model transitioning from a fluid description to a fully kinetic PIC description during the run-in phase. Simulations are advanced through the final pinch phase using an adaptive variable time-step to capture the fs and sub-mm scales of the kinetic instabilities involved in the ion beam formation and neutron production. Results will be present on the predicted effects of different anode configurations. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory (LLNL) under Contract DE-AC52-07NA27344 and supported by the Laboratory Directed Research and Development Program (11-ERD-063) and the Computing Grand Challenge program at LLNL. This work supported by Office of Defense Nuclear Nonproliferation Research and Development within U.S. Department of Energy's National Nuclear Security Administration.

Pre-transition effects mediate forces of assembly between transmembrane proteins

DOE PAGES

Katira, Sachi; Mandadapu, Kranthi K.; Vaikuntanathan, Suriyanarayanan; ...

2016-02-24

We present a mechanism for a generic, powerful force of assembly and mobility for transmembrane proteins in lipid bilayers. This force is a pre-transition (or pre-melting) effect for the first-order transition between ordered and disordered phases in the membrane. Using large-scale molecular simulation, we show that a protein with hydrophobic thickness equal to that of the disordered phase embedded in an ordered bilayer stabilizes a microscopic order-disorder interface. The stiffness of that interface is finite. When two such proteins approach each other, they assemble because assembly reduces the net interfacial energy. Analogous to the hydrophobic effect, we refer to thismore » phenomenon as the ‘orderphobic effect’. The effect is mediated by proximity to the order-disorder phase transition and the size and hydrophobic mismatch of the protein. Furthermore, the strength and range of forces arising from this effect are significantly larger than those that could arise from membrane elasticity for the membranes considered.« less

Pre-transition effects mediate forces of assembly between transmembrane proteins

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

Katira, Sachi; Mandadapu, Kranthi K.; Vaikuntanathan, Suriyanarayanan

We present a mechanism for a generic, powerful force of assembly and mobility for transmembrane proteins in lipid bilayers. This force is a pre-transition (or pre-melting) effect for the first-order transition between ordered and disordered phases in the membrane. Using large-scale molecular simulation, we show that a protein with hydrophobic thickness equal to that of the disordered phase embedded in an ordered bilayer stabilizes a microscopic order-disorder interface. The stiffness of that interface is finite. When two such proteins approach each other, they assemble because assembly reduces the net interfacial energy. Analogous to the hydrophobic effect, we refer to thismore » phenomenon as the ‘orderphobic effect’. The effect is mediated by proximity to the order-disorder phase transition and the size and hydrophobic mismatch of the protein. Furthermore, the strength and range of forces arising from this effect are significantly larger than those that could arise from membrane elasticity for the membranes considered.« less

Development of high strength ferritic steel for interconnect application in SOFCs

NASA Astrophysics Data System (ADS)

Froitzheim, J.; Meier, G. H.; Niewolak, L.; Ennis, P. J.; Hattendorf, H.; Singheiser, L.; Quadakkers, W. J.

High-Cr ferritic model steels containing various additions of the refractory elements Nb and/or W were studied with respect to oxidation behaviour (hot) tensile properties, creep behaviour and high-temperature electrical conductivity of the surface oxide scales. Whereas W additions of around 2 wt.% had hardly any effect on the oxidation rates at 800 and 900 °C, Nb additions of 1% led to a substantially enhanced growth rate of the protective surface oxide scale. It was found that this adverse effect can be alleviated by suitable Si additions. This is related to the incorporation of Si and Nb into Laves phase precipitates which also contribute to increased creep and hot tensile strength. The dispersion of Laves phase precipitates was greatly refined by combined additions of Nb and W. The high-temperature electrical conductivity of the surface oxide scales was similar to that of the Nb/W-free alloys. Thus the combined additions of Nb, W and Si resulted in an alloy with oxidation resistance, ASR contribution and thermal expansion comparable to the commercial alloy Crofer 22 APU, but with creep strength far greater than that of Crofer 22 APU.

Phase boundaries of power-law Anderson and Kondo models: A poor man's scaling study

NASA Astrophysics Data System (ADS)

Cheng, Mengxing; Chowdhury, Tathagata; Mohammed, Aaron; Ingersent, Kevin

2017-07-01

We use the poor man's scaling approach to study the phase boundaries of a pair of quantum impurity models featuring a power-law density of states ρ (ɛ ) ∝|ɛ| r , either vanishing (for r >0 ) or diverging (for r <0 ) at the Fermi energy ɛ =0 , that gives rise to quantum phase transitions between local-moment and Kondo-screened phases. For the Anderson model with a pseudogap (i.e., r >0 ), we find the phase boundary for (a) 0 1 , where the phases are separated by first-order quantum phase transitions that are accessible only for broken p-h symmetry. For the p-h-symmetric Kondo model with easy-axis or easy-plane anisotropy of the impurity-band spin exchange, the phase boundary and scaling trajectories are obtained for both r >0 and r <0 . Throughout the regime of weak-to-moderate impurity-band coupling in which poor man's scaling is expected to be valid, the approach predicts phase boundaries in excellent qualitative and good quantitative agreement with the nonperturbative numerical renormalization group, while also establishing the functional relations between model parameters along these boundaries.

Development of a Decisional Balance Scale for Young Adult Marijuana Use

PubMed Central

Elliott, Jennifer C.; Carey, Kate B.; Scott-Sheldon, Lori A. J.

2010-01-01

This study describes the development and validation of a decisional balance scale for marijuana use in young adults. Scale development was accomplished in four phases. First, 53 participants (70% female, 68% freshman) provided qualitative data that yielded content for an initial set of 47 items. In the second phase, an exploratory factor analysis on the responses of 260 participants (52% female, 68% freshman) revealed two factors, corresponding to pros and cons. Items that did not load well on the factors were omitted, resulting in a reduced set of 36 items. In the third phase, 182 participants (49% female, 37% freshmen) completed the revised scale and an evaluation of factor structure led to scale revisions and model respecification to create a good-fitting model. The final scales consisted of 8 pros (α = 0.91) and 16 cons (α = 0.93), and showed evidence of validity. In the fourth phase (N = 248, 66% female, 70% freshman), we confirmed the factor structure, and provided further evidence for reliability and validity. The Marijuana Decisional Balance Scale enhances our ability to study motivational factors associated with marijuana use among young adults. PMID:21261405

Intermediate-scale plasma irregularities in the polar ionosphere inferred from GPS radio occultation

NASA Astrophysics Data System (ADS)

Shume, E. B.; Komjathy, A.; Langley, R. B.; Verkhoglyadova, O.; Butala, M. D.; Mannucci, A. J.

2015-02-01

We report intermediate-scale plasma irregularities in the polar ionosphere inferred from high-resolution radio occultation (RO) measurements using GPS (Global Positioning System) to CASSIOPE (CAScade Smallsat and IOnospheric Polar Explorer) satellite radio links. The high inclination of CASSIOPE and the high rate of signal reception by the GPS Attitude, Positioning, and Profiling RO receiver on CASSIOPE enable a high-resolution investigation of the dynamics of the polar ionosphere with unprecedented detail. Intermediate-scale, scintillation-producing irregularities, which correspond to 1 to 40 km scales, were inferred by applying multiscale spectral analysis on the RO phase measurements. Using our multiscale spectral analysis approach and satellite data (Polar Operational Environmental Satellites and Defense Meteorological Satellite Program), we discovered that the irregularity scales and phase scintillations have distinct features in the auroral oval and polar cap. We found that large length scales and more intense phase scintillations are prevalent in the auroral oval compared to the polar cap implying that the irregularity scales and phase scintillation characteristics are a function of the solar wind and magnetospheric forcings.

Phase and vortex correlations in superconducting Josephson-junction arrays at irrational magnetic frustration.

PubMed

Granato, Enzo

2008-07-11

Phase coherence and vortex order in a Josephson-junction array at irrational frustration are studied by extensive Monte Carlo simulations using the parallel-tempering method. A scaling analysis of the correlation length of phase variables in the full equilibrated system shows that the critical temperature vanishes with a power-law divergent correlation length and critical exponent nuph, in agreement with recent results from resistivity scaling analysis. A similar scaling analysis for vortex variables reveals a different critical exponent nuv, suggesting that there are two distinct correlation lengths associated with a decoupled zero-temperature phase transition.

Effect of biochar addition on hydrogen and methane production in two-phase anaerobic digestion of aqueous carbohydrates food waste.

PubMed

Sunyoto, Nimas M S; Zhu, Mingming; Zhang, Zhezi; Zhang, Dongke

2016-11-01

Effect of biochar addition on hydrogen and methane production in two-phase anaerobic digestion of aqueous carbohydrates was studied using bench-scale bioreactors. The cultures with biochar additions were placed in 100ml reactors and incubated at 35°C and pH 5 for hydrogen production. The residual cultures were then used for methane production, incubated at 35°C and pH 7. Daily yields of hydrogen and methane and weekly yield of volatile fatty acids (VFA) were measured. The hydrogen and methane production potentials, rate and lag phases of the two phases were analysed using the Gompertz model. The results showed that biochar addition increased the maximum production rates of hydrogen by 32.5% and methane 41.6%, improved hydrogen yield by 31.0% and methane 10.0%, and shortened the lag phases in the two phases by 36.0% and 41.0%, respectively. Biochar addition also enhanced VFA generation during hydrogen production and VFA degradation in methane production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development and validation of a patient-reported outcome measure for stroke patients.

PubMed

Luo, Yanhong; Yang, Jie; Zhang, Yanbo

2015-05-08

Family support and patient satisfaction with treatment are crucial for aiding in the recovery from stroke. However, current validated stroke-specific questionnaires may not adequately capture the impact of these two variables on patients undergoing clinical trials of new drugs. Therefore, the aim of this study was to develop and evaluate a new stroke patient-reported outcome measure (Stroke-PROM) instrument for capturing more comprehensive effects of stroke on patients participating in clinical trials of new drugs. A conceptual framework and a pool of items for the preliminary Stroke-PROM were generated by consulting the relevant literature and other questionnaires created in China and other countries, and interviewing 20 patients and 4 experts to ensure that all germane parameters were included. During the first item-selection phase, classical test theory and item response theory were applied to an initial scale completed by 133 patients with stroke. During the item-revaluation phase, classical test theory and item response theory were used again, this time with 475 patients with stroke and 104 healthy participants. During the scale assessment phase, confirmatory factor analysis was applied to the final scale of the Stroke-PROM using the same study population as in the second item-selection phase. Reliability, validity, responsiveness and feasibility of the final scale were tested. The final scale of Stroke-PROM contained 46 items describing four domains (physiology, psychology, society and treatment). These four domains were subdivided into 10 subdomains. Cronbach's α coefficients for the four domains ranged from 0.861 to 0.908. Confirmatory factor analysis supported the validity of the final scale, and the model fit index satisfied the criterion. Differences in the Stroke-PROM mean scores were significant between patients with stroke and healthy participants in nine subdomains (P < 0.001), indicating that the scale showed good responsiveness. The Stroke-PROM is a patient-reported outcome multidimensional questionnaire developed especially for clinical trials of new drugs and is focused on issues of family support and patient satisfaction with treatment. Extensive data analyses supported the validity, reliability and responsiveness of the Stroke-PROM.

V/STOL tilt rotor aircraft study. Volume 10: Performance and stability test of A 1-14.622 Froude scaled Boeing Vertol Model 222 tilt rotor aircraft (Phase 1)

NASA Technical Reports Server (NTRS)

Mchugh, F. J.; Eason, W.; Alexander, H. R.; Mutter, H.

1973-01-01

Wind tunnel test data obtained from a 1/4.622 Froude scale Boeing Model 222 with a full span, two prop, tilt rotor, powered model in the Boeing V/STOL wind tunnel are reported. Data were taken in transition and cruise flight conditions and include performance, stability and control and blade loads information. The effects of the rotors, tail surfaces and airframe on the performance and stability are isolated as are the effects of the airframe on the rotors.

Overlapping double potential wells in a single optical microtube cavity with vernier-scale-like tuning effect

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

Madani, A.; Schmidt, O. G.; Material Systems for Nanoelectronics, Chemnitz University of Technology, Reichenhainer Str. 70, 09107 Chemnitz

2016-04-25

Spatially and temporally overlapping double potential wells are realized in a hybrid optical microtube cavity due to the coexistence of an aggregate of luminescent quantum dots embedded in the tube wall and the cone-shaped tube's geometry. The double potential wells produce two independent sets of optical modes with different sets of mode numbers, indicating phase velocity separation for the modes overlapping at the same frequency. The overlapping mode position can be tuned by modifying the tube cavity, where these mode sets shift with different magnitudes, allowing for a vernier-scale-like tuning effect.

Outer scale of atmospheric turbulence

NASA Astrophysics Data System (ADS)

Lukin, Vladimir P.

2005-10-01

In the early 70's, the scientists in Italy (A.Consortini, M.Bertolotti, L.Ronchi), USA (R.Buser, Ochs, S.Clifford) and USSR (V.Pokasov, V.Lukin) almost simultaneously discovered the phenomenon of deviation from the power law and the effect of saturation for the structure phase function. During a period of 35 years we have performed successively the investigations of the effect of low-frequency spectral range of atmospheric turbulence on the optical characteristics. The influence of the turbulence models as well as a outer scale of turbulence on the characteristics of telescopes and systems of laser beam formations has been determined too.

Micropore Geometry Manipulation by Macroscopic Deformation Based on Shape Memory Effect in Porous PLLA Membrane and its Enhanced Separation Performance.

PubMed

Zhao, Jingxin; Yang, Qiucheng; Wang, Tao; Wang, Lian; You, Jichun; Li, Yongjin

2017-12-20

An effective strategy to tailor the microporous structures has been developed based on the shape memory effect in porous poly(l-lactic acid) membranes in which tiny crystals and amorphous matrix play the roles of shape-fixed phase and reversible-phase, respectively. Our results indicate that not only PLLA membranes but micropores exhibit shape memory properties. The proportional deformations on two scales have been achieved by uniaxial or biaxial tension, providing a facile way to manipulate continuously the size and the orientation degree of pores on microscale. The enhanced separation performance has been validated by taking polystyrene colloids with varying diameters as an example.

Flat-roof phenomenon of dynamic equilibrium phase in the negative bias temperature instability effect on a power MOSFET

NASA Astrophysics Data System (ADS)

Zhang, Yue; Zhuo, Qing-Qing; Liu, Hong-Xia; Ma, Xiao-Hua; Hao, Yue

2014-05-01

The effect of the static negative bias temperature (NBT) stress on a p-channel power metal—oxide—semiconductor field-effect transistor (MOSFET) is investigated by experiment and simulation. The time evolution of the negative bias temperature instability (NBTI) degradation has the trend predicted by the reaction—diffusion (R—D) model but with an exaggerated time scale. The phenomena of the flat-roof section are observed under various stress conditions, which can be considered as the dynamic equilibrium phase in the R—D process. Based on the simulated results, the variation of the flat-roof section with the stress condition can be explained.

Scaling of counter-current imbibition recovery curves using artificial neural networks

NASA Astrophysics Data System (ADS)

Jafari, Iman; Masihi, Mohsen; Nasiri Zarandi, Masoud

2018-06-01

Scaling imbibition curves are of great importance in the characterization and simulation of oil production from naturally fractured reservoirs. Different parameters such as matrix porosity and permeability, oil and water viscosities, matrix dimensions, and oil/water interfacial tensions have an effective on the imbibition process. Studies on the scaling imbibition curves along with the consideration of different assumptions have resulted in various scaling equations. In this work, using an artificial neural network (ANN) method, a novel technique is presented for scaling imbibition recovery curves, which can be used for scaling the experimental and field-scale imbibition cases. The imbibition recovery curves for training and testing the neural network were gathered through the simulation of different scenarios using a commercial reservoir simulator. In this ANN-based method, six parameters were assumed to have an effect on the imbibition process and were considered as the inputs for training the network. Using the ‘Bayesian regularization’ training algorithm, the network was trained and tested. Training and testing phases showed superior results in comparison with the other scaling methods. It is concluded that using the new technique is useful for scaling imbibition recovery curves, especially for complex cases, for which the common scaling methods are not designed.

8OCB and 8CB Liquid Crystals Confined in Nanoporous Alumina: Effect of Confinement on the Structure and Dynamics.

PubMed

Selevou, Aristoula; Papamokos, George; Steinhart, Martin; Floudas, George

2017-08-03

The effect of oxygen substitution is studied in two homologous compounds of n-cyanobiphenyls with n = 8 in the bulk and under confinement within self-ordered nanoporous alumina (AAO). Oxygen substitution in 8OCB increases the dipole moment and stabilizes the crystalline, smectic, and nematic phases to higher temperatures relative to 8CB. Within their smectic- A (SmA) phase both 8CB and 8OCB behave as weak viscoelastic solids with low shear moduli reflecting the underlying supramolecular defect structure. Dielectric spectroscopy assisted by DFT calculations identified strong dipolar associations within the isotropic phases characterized by a Kirkwood-Fröhlich interaction parameter, g ∼ 0.36. Dielectric spectroscopy further identified a slow process (∼ kHz) of low dielectric strength. The proximity of this process to the rheology time scale suggests as common origin a cooperative relaxation of the defect structure. Confinement alters the phase diagram by stabilizing certain crystalline phases and by reducing the N-I transition temperature in agreement with surface tension effects. However, the N-I transition seems to retain its first order character. Surface treatment with n-decyltrichlorosilane results in destabilization of the SmA phase at the expense of the N phase. This is consistent with a picture of surface anchored LC molecules at the pore walls that stabilize the nematic phase.

Phase diagram, correlation gap, and critical properties of the Coulomb glass

NASA Astrophysics Data System (ADS)

Palassini, Matteo; Goethe, Martin

2009-03-01

We investigate the lattice Coulomb glass model in three dimensions via extensive Monte Carlo simulations. 1. No evidence for an equilibrium glass phase is found down to very low temperatures, contrary to mean-field predictions, although the correlation length increases rapidly near T=0. 2. The single-particle density of states near the Coulomb gap satisfies the scaling law g(e,T)=T^λf(e/T) with λ 2.2. 3. A charge-ordered phase exists at low disorder. The phase transition from the fluid to the charge ordered phase is consistent with the Random Field Ising universality class, which shows that the interaction is effectively screened at moderate temperature. Results from nonequilibrium simulations will also be briefly discussed. Reference: M.Goethe and M.Palassini, arXiv:0810.1047

Three-state Potts model on non-local directed small-world lattices

NASA Astrophysics Data System (ADS)

Ferraz, Carlos Handrey Araujo; Lima, José Luiz Sousa

2017-10-01

In this paper, we study the non-local directed Small-World (NLDSW) disorder effects in the three-state Potts model as a form to capture the essential features shared by real complex systems where non-locality effects play a important role in the behavior of these systems. Using Monte Carlo techniques and finite-size scaling analysis, we estimate the infinite lattice critical temperatures and the leading critical exponents in this model. In particular, we investigate the first- to second-order phase transition crossover when NLDSW links are inserted. A cluster-flip algorithm was used to reduce the critical slowing down effect in our simulations. We find that for a NLDSW disorder densities p

Simulating the onset of spring vegetation growth across the Northern Hemisphere.

PubMed

Liu, Qiang; Fu, Yongshuo H; Liu, Yongwen; Janssens, Ivan A; Piao, Shilong

2018-03-01

Changes in the spring onset of vegetation growth in response to climate change can profoundly impact climate-biosphere interactions. Thus, robust simulation of spring onset is essential to accurately predict ecosystem responses and feedback to ongoing climate change. To date, the ability of vegetation phenology models to reproduce spatiotemporal patterns of spring onset at larger scales has not been thoroughly investigated. In this study, we took advantage of phenology observations via remote sensing to calibrate and evaluated six models, including both one-phase (considering only forcing temperatures) and two-phase (involving forcing, chilling, and photoperiod) models across the Northern Hemisphere between 1982 and 2012. Overall, we found that the model that integrated the photoperiod effect performed best at capturing spatiotemporal patterns of spring phenology in boreal and temperate forests. By contrast, all of the models performed poorly in simulating the onset of growth in grasslands. These results suggest that the photoperiod plays a role in controlling the onset of growth in most Northern Hemisphere forests, whereas other environmental factors (e.g., precipitation) should be considered when simulating the onset of growth in grasslands. We also found that the one-phase model performed as well as the two-phase models in boreal forests, which implies that the chilling requirement is probably fulfilled across most of the boreal zone. Conversely, two-phase models performed better in temperate forests than the one-phase model, suggesting that photoperiod and chilling play important roles in these temperate forests. Our results highlight the significance of including chilling and photoperiod effects in models of the spring onset of forest growth at large scales, and indicate that the consideration of additional drivers may be required for grasslands. © 2017 John Wiley & Sons Ltd.

LARGE-SCALE CONTRACTION AND SUBSEQUENT DISRUPTION OF CORONAL LOOPS DURING VARIOUS PHASES OF THE M6.2 FLARE ASSOCIATED WITH THE CONFINED FLUX ROPE ERUPTION

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

Kushwaha, Upendra; Joshi, Bhuwan; Moon, Yong-Jae

We investigate evolutionary phases of an M6.2 flare and the associated confined eruption of a prominence. The pre-flare phase exhibits spectacular large-scale contraction of overlying extreme ultraviolet (EUV) coronal loops during which the loop system was subjected to an altitude decrease of ∼20 Mm (40% of the initial height) for an extended span of ∼30 minutes. This contraction phase is accompanied by sequential EUV brightenings associated with hard X-ray (HXR; up to 25 keV) and microwave (MW) sources from low-lying loops in the core region which together with X-ray spectra indicate strong localized heating in the source region before themore » filament activation. With the onset of the flare’s impulsive phase, we detect HXR and MW sources that exhibit intricate temporal and spatial evolution in relation to the fast rise of the prominence. Following the flare maximum, the filament eruption slowed down and subsequently became confined within the large overlying active region loops. During the confinement process of the erupting prominence, we detect MW emission from the extended coronal region with multiple emission centroids, which likely represent emission from hot blobs of plasma formed after the collapse of the expanding flux rope and entailing prominence material. RHESSI spectroscopy reveals high plasma temperature (∼30 MK) and substantial non-thermal characteristics (δ ∼ 5) during the impulsive phase of the flare. The time evolution of thermal energy exhibits a good correspondence with the variations in cumulative non-thermal energy, which suggests that the energy of accelerated particles is efficiently converted to hot flare plasma, implying an effective validation of the Neupert effect.« less

Phase-field model for isothermal phase transitions in binary alloys

NASA Technical Reports Server (NTRS)

Wheeler, A. A.; Boettinger, W. J.; Mcfadden, G. B.

1992-01-01

A new phase field model is described which models isothermal phase transitions between ideal binary alloy solution phases. Equations are developed for the temporal and spatial variation of the phase field, which describes the identity of the phase, and of the composition. An asymptotic analysis, as the gradient energy coefficient of the phase field becomes small, was conducted. From the analysis, it is shown that the model recovers classical sharp interface models of this situation when the interfacial layers are thin, and they show how to relate the parameters appearing in the phase field model to material and growth parameters in real systems. Further, three stages of temporal evolution are identified: the first corresponding to interfacial genesis which occurs very rapidly; the second to interfacial motion controlled by the local energy difference across the interface and diffusion; the last taking place on a long time scale in which curvature effects are important and which correspond to Ostwald ripening. The results of the numerical calculations are presented.

Centralised, decentralised or hybrid sanitation systems? Economic evaluation under urban development uncertainty and phased expansion.

PubMed

Roefs, Ivar; Meulman, Brendo; Vreeburg, Jan H G; Spiller, Marc

2017-02-01

Sanitation systems are built to be robust, that is, they are dimensioned to cope with population growth and other variability that occurs throughout their lifetime. It was recently shown that building sanitation systems in phases is more cost effective than one robust design. This phasing can take place by building small autonomous decentralised units that operate closer to the actual demand. Research has shown that variability and uncertainty in urban development does affect the cost effectiveness of this approach. Previous studies do not, however, consider the entire sanitation system from collection to treatment. The aim of this study is to assess the economic performance of three sanitation systems with different scales and systems characteristics under a variety of urban development pathways. Three systems are studied: (I) a centralised conventional activated sludge treatment, (II) a community on site source separation grey water and black water treatment and (III) a hybrid with grey water treatment at neighbourhood scale and black water treatment off site. A modelling approach is taken that combines a simulation of greenfield urban growth, a model of the wastewater collection and treatment infrastructure design properties and a model that translates design parameters into discounted asset lifetime costs. Monte Carlo simulations are used to evaluate the economic performance under uncertain development trends. Results show that the conventional system outperforms both of the other systems when total discounted lifetime costs are assessed, because it benefits from economies of scale. However, when population growth is lower than expected, the source-separated system is more cost effective, because of reduced idle capacity. The hybrid system is not competitive under any circumstance due to the costly double piping and treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Aspects of extratropical synoptic-scale processes in opposing ENSO phases

NASA Astrophysics Data System (ADS)

Schwierz, C.; Wernli, H.; Hess, D.

2003-04-01

Energy and momentum provided by anomalous tropical heating/cooling affect the circulation on the global scale. Pacific Sea surface temperature anomalies strongly force local conditions in the equatorial Pacific, but are also known to change the climate in the extratropics, particularly over the American continent. The impact on more remote areas such as the Atlantic-European region is less clear. There the observed effects in both analyses and model studies show dependence on the resolution of the model/data, as well as on the time scales under consideration (Merkel and Latif, 2002; Compo et al., 2001). Most of the previous studies focus on larger-scale processes and seasonal time scales (or longer). Here we concentrate on the impact of opposing ENSO phases on extratropical synoptic-scale dynamics. The investigation is undertaken for the Niño/Niña events of 1972/3 and 1973/4 respectively, for 5 winter months (NDJFM) using ECMWF ERA40 data with 1o× 1o horizontal resolution and 60 vertical levels. The examination of the resulting differences in terms of standard dynamical fields (temperature, sea level pressure, precipitation, geopotential) is complemented with additional diagnostic fields (e.g. potential vorticity (PV), anti-/cyclone tracks and frequencies, PV streamers/cut-offs, blocking) in an attempt to gain more insight into aspects of extratropical synoptic-scale dynamical processes associated with ENSO SST anomalies.

Pore-scale dynamics of enzyme adsorption, swelling and reactive dissolution determine sugar yield in hemicellulose hydrolysis for biofuel production

NASA Astrophysics Data System (ADS)

Dutta, Sajal Kanti; Chakraborty, Saikat

2016-12-01

Hemicelluloses are the earth’s second most abundant structural polymers, found in lignocellulosic biomass. Efficient enzymatic depolymerization of xylans by cleaving their β-(1 → 4)-glycosidic bonds to produce soluble sugars is instrumental to the cost-effective production of liquid biofuels. Here we show that the multi-scale two-phase process of enzymatic hydrolysis of amorphous hemicelluloses is dominated by its smallest scale-the pores. In the crucial first five hours, two to fourfold swelling of the xylan particles allow the enzymes to enter the pores and undergo rapid non-equilibrium adsorption on the pore surface before they hydrolyze the solid polymers, albeit non-competitively inhibited by the products xylose and xylobiose. Rapid pore-scale reactive dissolution increases the solid carbohydrate’s porosity to 80-90%. This tightly coupled experimental and theoretical study quantifies the complex temporal dynamics of the transport and reaction processes coupled across scales and phases to show that this unique pore-scale phenomenon can be exploited to accelerate the depolymerization of hemicelluloses to monomeric sugars in the first 5-6 h. We find that an ‘optimal substrate loading’ of 5 mg/ml (above which substrate inhibition sets in) accelerates non-equilibrium enzyme adsorption and solid hemicellulose depolymerization at the pore-scale, which contributes three-quarters of the soluble sugars produced for bio-alcohol fermentation.

Effects of atmospheric dynamics and aerosols on the fraction of supercooled water clouds

NASA Astrophysics Data System (ADS)

Li, Jiming; Lv, Qiaoyi; Zhang, Min; Wang, Tianhe; Kawamoto, Kazuaki; Chen, Siyu; Zhang, Beidou

2017-02-01

Based on 8 years of (January 2008-December 2015) cloud phase information from the GCM-Oriented Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) Cloud Product (GOCCP), aerosol products from CALIPSO and meteorological parameters from the ERA-Interim products, the present study investigates the effects of atmospheric dynamics on the supercooled liquid cloud fraction (SCF) during nighttime under different aerosol loadings at global scale to better understand the conditions of supercooled liquid water gradually transforming to ice phase. Statistical results indicate that aerosols' effect on nucleation cannot fully explain all SCF changes, especially in those regions where aerosols' effect on nucleation is not a first-order influence (e.g., due to low ice nuclei aerosol frequency). By performing the temporal and spatial correlations between SCFs and different meteorological factors, this study presents specifically the relationship between SCF and different meteorological parameters under different aerosol loadings on a global scale. We find that the SCFs almost decrease with increasing of aerosol loading, and the SCF variation is closely related to the meteorological parameters but their temporal relationship is not stable and varies with the different regions, seasons and isotherm levels. Obviously negative temporal correlations between SCFs versus vertical velocity and relative humidity indicate that the higher vertical velocity and relative humidity the smaller SCFs. However, the patterns of temporal correlation for lower-tropospheric static stability, skin temperature and horizontal wind are relatively more complex than those of vertical velocity and humidity. For example, their close correlations are predominantly located in middle and high latitudes and vary with latitude or surface type. Although these statistical correlations have not been used to establish a certain causal relationship, our results may provide a unique point of view on the phase change of mixed-phase cloud and have potential implications for further improving the parameterization of the cloud phase and determining the climate feedbacks.

Scattering - a probe to Earth's small scale structure

NASA Astrophysics Data System (ADS)

Rost, S.; Earle, P.

2009-05-01

Much of the short-period teleseismic wavefield shows strong evidence for scattered waves in extended codas trailing the main arrivals predicted by ray theory. This energy mainly originates from high-frequency body waves interacting with fine-scale volumetric heterogeneities in the Earth. Studies of this energy revealed much of what we know about Earth's structure at scale lengths around 10 km throughout the Earth from crust to core. From these data we can gain important information about the mineral-physical and geochemical constitution of the Earth that is inaccessible to many other seismic imaging techniques. Previous studies used scattered energy related to PKP, PKiKP, and Pdiff to identify and map the small-scale structure of the mantle and core. We will present observations related to the core phases PKKP and P'P' to study fine-scale mantle heterogeneities. These phases are maximum travel-time phases with respect to perturbations at their reflection points. This allows observation of the scattered energy as precursors to the main phase avoiding common problems with traditional coda phases which arrive after the main pulse. The precursory arrival of the scattered energy allows the separation between deep Earth and crustal contributions to the scattered wavefield for certain source-receiver configurations. Using the information from these scattered phases we identify regions of the mantle that shows increased scattering potential likely linked to larger scale mantle structure identified in seismic tomography and geodynamical models.

Nonrelativistic fluids on scale covariant Newton-Cartan backgrounds

NASA Astrophysics Data System (ADS)

Mitra, Arpita

2017-12-01

The nonrelativistic covariant framework for fields is extended to investigate fields and fluids on scale covariant curved backgrounds. The scale covariant Newton-Cartan background is constructed using the localization of space-time symmetries of nonrelativistic fields in flat space. Following this, we provide a Weyl covariant formalism which can be used to study scale invariant fluids. By considering ideal fluids as an example, we describe its thermodynamic and hydrodynamic properties and explicitly demonstrate that it satisfies the local second law of thermodynamics. As a further application, we consider the low energy description of Hall fluids. Specifically, we find that the gauge fields for scale transformations lead to corrections of the Wen-Zee and Berry phase terms contained in the effective action.

'Getting to Know Me': The second phase roll-out of a staff training programme for supporting people with dementia in general hospitals.

PubMed

Elvish, Ruth; Burrow, Simon; Cawley, Rosanne; Harney, Kathryn; Pilling, Mark; Gregory, Julie; Keady, John

2018-01-01

Objectives The aims were to evaluate a second phase roll-out of a dementia care training programme for general hospital staff and to further develop two outcome scales: the Confidence in Dementia scale for measuring confidence in working with people with dementia and the Knowledge in Dementia scale for measuring knowledge in dementia. Method Following a 'training the trainers' phase, the study involved the delivery of the 'Getting to Know Me' training programme to a large number of staff (n = 517) across three National Health Service (NHS) Trusts situated in North-West England. The impact of the programme was evaluated using a pre-post design which explored: (i) changes in confidence in dementia, (ii) changes in knowledge in dementia, and (iii) changes in beliefs about behaviours that challenge. Results Statistically significant change was identified between pre-post training on all outcome measures (Confidence in Dementia: eight point increase, p < 0.001; Knowledge in Dementia: two point increase p < 0.001; controllability beliefs scale: four point decrease, p < 0.001). Medium to large effect sizes were demonstrated on all outcome measures. The psychometric properties of the Confidence in Dementia and Knowledge in Dementia scales are reported. Conclusion Staff knowledge in dementia and confidence in working with people with dementia significantly increased following attendance at the training sessions. The findings are consistent with preliminary findings and strengthen current knowledge about the impact of dementia care training in general hospitals. The Confidence in Dementia and Knowledge in Dementia scales continue to demonstrate psychometrically sound properties and demonstrate utility in the field of dementia research.

Evaluation of dispersion strengthened nickel-base alloy heat shields for space shuttle application

NASA Technical Reports Server (NTRS)

Johnson, R., Jr.; Killpatrick, D. H.

1973-01-01

The work reported constitutes the first phase of a two-phase program. Vehicle environments having critical effects on the thermal protection system are defined; TD Ni-20Cr material characteristics are reviewed and compared with TD Ni-20Cr produced in previous development efforts; cyclic load, temperature, and pressure effects on TD Ni-20Cr sheet material are investigated; the effects of braze reinforcement in improving the efficiency of spotwelded, diffusion-bonded, or seam-welded joints are evaluated through tests of simple lap-shear joint samples; parametric studies of metallic radiative thermal protection systems are reported; and the design, instrumentation, and testing of full-scale subsize heat shield panels are described. Tests of full-scale subsize panels included simulated meteoroid impact tests; simulated entry flight aerodynamic heating in an arc-heated plasma stream; programmed differential pressure loads and temperatures simulating mission conditions; and acoustic tests simulating sound levels experienced by heat shields during about boost flight. Test results are described, and the performances of two heat shield designs are compared and evaluated.

Baryon inhomogeneity generation in the quark-gluon plasma phase

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

Layek, Biswanath; Mishra, Ananta P.; Srivastava, Ajit M.

2006-05-15

We discuss the possibility of generation of baryon inhomogeneities in a quark-gluon plasma phase due to moving Z(3) interfaces. By modeling the dependence of effective mass of the quarks on the Polyakov loop order parameter, we study the reflection of quarks from collapsing Z(3) interfaces and estimate resulting baryon inhomogeneities in the context of the early universe. We argue that in the context of certain low energy scale inflationary models, it is possible that large Z(3) walls arise at the end of the reheating stage. Collapse of such walls could lead to baryon inhomogeneities which may be separated by largemore » distances near the QCD scale. Importantly, the generation of these inhomogeneities is insensitive to the order, or even the existence, of the quark-hadron phase transition. We also briefly discuss the possibility of formation of quark nuggets in this model, as well as baryon inhomogeneity generation in relativistic heavy-ion collisions.« less

Development of processes for the production of solar grade silicon from halides and alkali metals, phase 1 and phase 2

NASA Technical Reports Server (NTRS)

Dickson, C. R.; Gould, R. K.; Felder, W.

1981-01-01

High temperature reactions of silicon halides with alkali metals for the production of solar grade silicon are described. Product separation and collection processes were evaluated, measure heat release parameters for scaling purposes and effects of reactants and/or products on materials of reactor construction were determined, and preliminary engineering and economic analysis of a scaled up process were made. The feasibility of the basic process to make and collect silicon was demonstrated. The jet impaction/separation process was demonstrated to be a purification process. The rate at which gas phase species from silicon particle precursors, the time required for silane decomposition to produce particles, and the competing rate of growth of silicon seed particles injected into a decomposing silane environment were determined. The extent of silane decomposition as a function of residence time, temperature, and pressure was measured by infrared absorption spectroscopy. A simplistic model is presented to explain the growth of silicon in a decomposing silane enviroment.

Novel Downhole Electromagnetic Flowmeter for Oil-Water Two-Phase Flow in High-Water-Cut Oil-Producing Wells.

PubMed

Wang, Yanjun; Li, Haoyu; Liu, Xingbin; Zhang, Yuhui; Xie, Ronghua; Huang, Chunhui; Hu, Jinhai; Deng, Gang

2016-10-14

First, the measuring principle, the weight function, and the magnetic field of the novel downhole inserted electromagnetic flowmeter (EMF) are described. Second, the basic design of the EMF is described. Third, the dynamic experiments of two EMFs in oil-water two-phase flow are carried out. The experimental errors are analyzed in detail. The experimental results show that the maximum absolute value of the full-scale errors is better than 5%, the total flowrate is 5-60 m³/d, and the water-cut is higher than 60%. The maximum absolute value of the full-scale errors is better than 7%, the total flowrate is 2-60 m³/d, and the water-cut is higher than 70%. Finally, onsite experiments in high-water-cut oil-producing wells are conducted, and the possible reasons for the errors in the onsite experiments are analyzed. It is found that the EMF can provide an effective technology for measuring downhole oil-water two-phase flow.

Novel Downhole Electromagnetic Flowmeter for Oil-Water Two-Phase Flow in High-Water-Cut Oil-Producing Wells

PubMed Central

Wang, Yanjun; Li, Haoyu; Liu, Xingbin; Zhang, Yuhui; Xie, Ronghua; Huang, Chunhui; Hu, Jinhai; Deng, Gang

2016-01-01

First, the measuring principle, the weight function, and the magnetic field of the novel downhole inserted electromagnetic flowmeter (EMF) are described. Second, the basic design of the EMF is described. Third, the dynamic experiments of two EMFs in oil-water two-phase flow are carried out. The experimental errors are analyzed in detail. The experimental results show that the maximum absolute value of the full-scale errors is better than 5%, the total flowrate is 5–60 m3/d, and the water-cut is higher than 60%. The maximum absolute value of the full-scale errors is better than 7%, the total flowrate is 2–60 m3/d, and the water-cut is higher than 70%. Finally, onsite experiments in high-water-cut oil-producing wells are conducted, and the possible reasons for the errors in the onsite experiments are analyzed. It is found that the EMF can provide an effective technology for measuring downhole oil-water two-phase flow. PMID:27754412

Multi-scaling in the critical phenomena in the quenched disordered systems

NASA Astrophysics Data System (ADS)

Wu, X. T.

2018-04-01

The Landau-Ginzburg-Wilson Hamiltonian with random temperature for the phase transition in disordered systems from the Griffiths phase to ordered phase is reexamined. From the saddle point solutions, especially the excited state solutions, it is shown that the system self-organizes into blocks coupled with their neighbors like superspins, which are emergent variables. Taking the fluctuation around these saddle point solutions into account, we get an effective Hamiltonian, including the emergent superspins of the blocks, the fluctuation around the saddle point solutions, and their couplings. Applying Stratonovich-Hubbard transformation to the part of superspins, we get a Landau-Ginzburg-Wilson Hamiltonian for the blocks. From the saddle point equations for the blocks, we can get the second generation blocks, of which sizes are much larger than the first generation blocks. Repeating this procedure again and again, we get many generations of blocks to describe the asymptotic behavior. If a field is applied, the effective field on the superspins is multiplied greatly and proportional to the block size. For a very small field, the effective field on the higher generation superspins can be so strong to cause the superspins polarized radically. This can explain the extra large critical isotherm exponent discovered in the experiments. The phase space of reduced temperature vs. field is divided into many layers , in which different generation blocks dominate the critical behavior. The sizes of the different generation emergent blocks are new relevant length scales. This can explain a lot of puzzles in the experiments and the Monte Carlo simulation.

Outcome assessment of patients undergoing maxillofacial procedures for the treatment of sleep apnea: comparison of subjective and objective results.

PubMed

Dattilo, David J; Drooger, Scott A

2004-02-01

The purpose of this study was to compare the subjective findings of the Epworth Sleepiness Scale (ESS) to the objective findings of the overnight sleep study (OSS) in 57 patients who underwent phase I and phase II surgery for the correction of obstructive sleep apnea (OSA). Forty-two patients in phase I category (hyoid suspension, palatal surgery, and/or genioglossus advancement) and 15 patients in phase II category (maxillomandibular advancement) were examined. All patients had an OSS and completion of an ESS preoperatively and at a minimum of 8 weeks postoperatively. The results of each test were evaluated to examine any relationship between the improvements of the findings of the OSS to the changes in the ESS. Using accepted criteria, phase I surgery produced an 80% success rate and phase II surgery produced a greater than 95% success rate in both the respiratory disturbance index and the ESS. 1) Both phase I and phase II procedures are effective in treating OSA. 2) Phase II appears to be more effective in treating OSA using both objective and subjective evaluations. 3) Improvement in ESS scores and excessive daytime sleepiness seems to parallel the improvement in OSS scores in patients undergoing surgical correction of OSA.

Nanostructures having crystalline and amorphous phases

DOEpatents

Mao, Samuel S; Chen, Xiaobo

2015-04-28

The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

Occultation Experiment: Results of the First Direct Measurement of Mars's Atmosphere and Ionosphere.

PubMed

Kliore, A; Cain, D L; Levy, G S; Eshleman, V R; Fjeldbo, G; Drake, F D

1965-09-10

Changes in the frequency, phase, and amplitude of the Mariner IV radio signal, caused by passage through the atmosphere and ionosphere of Mars, were observed immediately before and after occultation by the planet. Preliminary analysis of these effects has yielded estimates of the refractivity and density of the atmosphere near the surface, the scale height in the atmosphere, and the electron density profile of the Martian ionosphere. The atmospheric density, temperature, and scale height are lower than previously predicted, as are the maximum density, temperature, scale height, and altitude of the ionosphere.

A comparison of isometric, isotonic concentric and isotonic eccentric exercises in the physiotherapy management of subacromial pain syndrome/rotator cuff tendinopathy: study protocol for a pilot randomised controlled trial.

PubMed

Kinsella, Rita; Cowan, Sallie M; Watson, Lyn; Pizzari, Tania

2017-01-01

Subacromial pain syndrome (SPS) involving rotator cuff tendinopathy is a common cause of shoulder pain and disability. Evidence suggests that structured physiotherapy may be as effective as surgery in this condition with significant improvements demonstrated in trials involving scapular retraining, rotator cuff strengthening and flexibility exercises. Most published programs typically utilise isotonic concentric and/or eccentric strengthening modes. Recently, immediate analgesic effects and muscle strength gains following heavy-load isometric exercises in lower limb tendinopathy conditions have been observed. It is pertinent to ascertain whether such outcomes can be replicated in SPS/rotator cuff tendinopathy. The primary aim of this study is to establish the feasibility of undertaking a full-scale randomised controlled trial (RCT) that compares the effects of isometric, isotonic concentric and isotonic eccentric rotator cuff contractions when used as part of a semi-standardised exercise-based physiotherapy program in patients diagnosed with SPS. The secondary aim is to explore potential trends or treatment effects of the exercise intervention. Thirty-six participants diagnosed with SPS will be randomised to one of three intervention groups and undergo a one-on-one exercise-based physiotherapy intervention, involving scapular and rotator cuff muscle retraining and strengthening. Each group will utilise a different mode of rotator cuff strengthening-isometric, isotonic concentric or isotonic eccentric. Rotator cuff tendon responses to isometric loading are not yet established in the literature; hence, individualised, progressive loading will be used in this pilot study in accordance with symptoms. The intervention will involve two phases: during Phase 1 (weeks 1-6) participants undertake the active group-specific physiotherapy treatment; in Phase 2 (weeks 6-12), they undertake a progressive, but no longer group-specific exercise program. To determine feasibility, an evaluation of key study parameters including (a) ease of recruitment (rate and number as well as suitability of the assessment algorithm), (b) adherence to all phases of the exercise intervention including home program compliance and logbook completion, (c) participant non-completion (drop out number and rate) and (d) adverse events (nature and number) will be undertaken. Secondary outcomes will measure immediate effects: (i) within-treatment changes in pain perception (verbal rating scale (VRS) and shoulder muscle strength (hand-held dynamometer) as well as longer-term changes: (ii) shoulder-related symptoms and disability (Western Ontario Rotator Cuff Index (WORC) and Shoulder Pain and Disability Index (SPADI)), (iii) perception of pain (11-point numerical rating scale (NRS), (iv) shoulder muscle strength (hand-held dynamometer) and (v) perceived global rating of change score. The immediate within-treatment assessment of pain and muscle strength will be undertaken in treatments 2 and 3, and the longer term measures will be collected at the primary (conclusion of Phase 1 at 6 weeks) and secondary (conclusion of Phase 2 at 12 weeks) end-points of the study. The findings of this pilot study will permit evaluation of this study design for a full-scale RCT. Australian New Zealand Clinical Trials Registry, ACTRN12616001676404.

Exploring the dynamics of phase separation in colloid-polymer mixtures with long range attraction.

PubMed

Sabin, Juan; Bailey, Arthur E; Frisken, Barbara J

2016-06-28

We have studied the kinetics of phase separation and gel formation in a low-dispersity colloid - non-adsorbing polymer system with long range attraction using small-angle light scattering. This system exhibits two-phase and three-phase coexistence of gas, liquid and crystal phases when the strength of attraction is between 2 and 4kBT and gel phases when the strength of attraction is increased. For those samples that undergo macroscopic phase separation, whether to gas-crystal, gas-liquid or gas-liquid-crystal coexistence, we observe dynamic scaling of the structure factor and growth of a characteristic length scale that behaves as expected for phase separation in fluids. In samples that gel, the power law associated with the growth of the dominant length scale is not equal to 1/3, but appears to depend mainly on the strength of attraction, decreasing from 1/3 for samples near the coexistence region to 1/27 at 8kBT, over a wide range of colloid and polymer concentrations.

Atomic Force Microscopy Studies of Functional and Dysfunctional Pulmonary Surfactant Films. I. Micro- and Nanostructures of Functional Pulmonary Surfactant Films and the Effect of SP-A

PubMed Central

Zuo, Yi Y.; Keating, Eleonora; Zhao, Lin; Tadayyon, Seyed M.; Veldhuizen, Ruud A. W.; Petersen, Nils O.; Possmayer, Fred

2008-01-01

Monolayers of a functional pulmonary surfactant (PS) can reach very low surface tensions well below their equilibrium value. The mechanism by which PS monolayers reach such low surface tensions and maintain film stability remains unknown. As shown previously by fluorescence microscopy, phospholipid phase transition and separation seem to be important for the normal biophysical properties of PS. This work studied phospholipid phase transitions and separations in monolayers of bovine lipid extract surfactant using atomic force microscopy. Atomic force microscopy showed phospholipid phase separation on film compression and a monolayer-to-multilayer transition at surface pressure 40–50 mN/m. The tilted-condensed phase consisted of domains not only on the micrometer scale, as detected previously by fluorescence microscopy, but also on the nanometer scale, which is below the resolution limits of conventional optical methods. The nanodomains were embedded uniformly within the liquid-expanded phase. On compression, the microdomains broke up into nanodomains, thereby appearing to contribute to tilted-condensed and liquid-expanded phase remixing. Addition of surfactant protein A altered primarily the nanodomains and promoted the formation of multilayers. We conclude that the nanodomains play a predominant role in affecting the biophysical properties of PS monolayers and the monolayer-to-multilayer transition. PMID:18212010

The influence of listener training on the perceptual assessment of hypernasality.

PubMed

Oliveira, Adriana Cristina de Almeida Santos Furlan de; Scarmagnani, Rafaeli Higa; Fukushiro, Ana Paula; Yamashita, Renata Paciello

2016-04-01

Introduction A high agreement in the perceptual assessment of hypernasality among different listeners is difficult to achieve. Prior listener training and the standardization of analysis criteria may be effective strategies to decrease the effect of perceptual assessment subjectivity and increase the agreement among listeners. Objective To investigate the influence of prior training on agreement among different listeners in the perceptual assessment of hypernasality. Methods Three experienced speech-language pathologists analyzed 77 audio-recorded speech samples of individuals with repaired cleft palate. During the first phase, the listeners classified hypernasality according to their own criteria, using a 4-point scale. Seventy days later, they were required to complete the training to define the stimuli to be used as anchors for the assessment in the following phase. During the second phase, the listeners analyzed the same samples and rated hypernasality in a 4-point scale, using the anchors defined during training as the criteria. Intra- and interrater agreement in both the phases were calculated by the kappa coefficient. These values were statistically compared using the Z-test. Results The intrarater agreement obtained between the two phases of the study ranged from 0.38 to 0.92, with a statistically significant difference for one of the listeners (p=0.004). The agreement for the hypernasality degree obtained among the three listeners after training (0.54) was significantly higher than that obtained before training (0.37; p=0.044). Conclusion Listener training and the definition of criteria to rate hypernasality lead to the increase of intra- and interrater agreement.

Large-scale phase separation with nano-twin domains in manganite spinel (Co,Fe,Mn){sub 3}O{sub 4}

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

Horibe, Y., E-mail: horibe@post.matsc.kyutech.ac.jp; Takeyama, S.; Mori, S.

The effect of Mn concentration on the formation of nano-domain structures in the spinel oxide (Co,Fe,Mn){sub 3}O{sub 4} was investigated by electron diffraction, bright-, and dark-field imaging technique with transmission electron microscopy. Large scale phase separation with nano-twin domains was observed in Co{sub 0.6}Fe{sub 1.0}Mn{sub 1.4}O{sub 4}, in contrast to the highly aligned checkerboard nano-domains in Co{sub 0.6}Fe{sub 0.9}Mn{sub 1.5}O{sub 4}. Diffusion of the Mn{sup 3+} ions with the Jahn-Teller distortions is suggested to play an important role in the formation of checkerboard nano-domain structure.

Magnetic Properties of Heavy Fermion Compound Ce5Si4 with Chiral Structure

NASA Astrophysics Data System (ADS)

Sato, Yoshiki J.; Shimizu, Yusei; Nakamura, Ai; Homma, Yoshiya; Li, Dexin; Maurya, Arvind; Honda, Fuminori; Aoki, Dai

2018-07-01

The low-temperature magnetic properties of Ce5Si4 with a chiral structure have been studied by electrical resistivity, heat capacity, and magnetization measurements using single-crystalline samples. It is found that Ce5Si4 is an antiferromagnet with moderately correlated electronic states. The resistivity decreases strongly under magnetic fields, indicating scaling behavior based on the Coqblin-Schrieffer model. The obtained characteristic energy scale of the Kondo effect is clearly anisotropic for the magnetic field H ∥ a-axis and H ∥ c-axis in the tetragonal structure, possibly related to the anisotropic antiferromagnetic phase. Furthermore, in the antiferromagnetic phase, a shoulderlike crossover anomaly is observed in C/T. A possible scenario is that non-ordered Ce atoms exist even below TN in this chiral system.

Evaluation of curing compound application time on concrete surface durability.

DOT National Transportation Integrated Search

2015-03-01

The effect of curing compound application time after concrete finishing was examined in the study. Times of 30 minutes, 2 hours and 4 hours were considered and repeatability was evaluated with comparisons to a Phase I portion of the study. Scaling re...

Hot gas ingestion test results of a two-poster vectored thrust concept with flow visualization in the NASA Lewis 9- by 15-foot low speed wind tunnel

NASA Technical Reports Server (NTRS)

Johns, Albert L.; Neiner, George; Bencic, Timothy J.; Flood, Joseph D.; Amuedo, Kurt C.

1990-01-01

A 9.2 percent scale STOVL hot gas ingestion model was tested in the NASA Lewis 9 x 15-foot Low-Speed Wind Tunnel. Flow visualization from the Phase 1 test program, which evaluated the hot ingestion phenomena and control techniques, is covered. The Phase 2 test program evaluated the hot gas ingestion phenomena at higher temperatures and used a laser sheet to investigate the flow field. Hot gas ingestion levels were measured for the several forward nozzle splay configurations and with flow control/life improvement devices (LIDs) which reduced the hot gas ingestion. The test was conducted at full scale nozzle pressure ratios and inlet Mach numbers. Results are presented over a range of nozzle pressure ratios at a 10 kn headwind velocity. The Phase 2 program was conducted at exhaust nozzle temperatures up to 1460 R and utilized a sheet laser system for flow visualization of the model flow field in and out of ground effects. The results reported are for nozzle exhaust temperatures up to 1160 R and contain the compressor face pressure and temperature distortions, the total pressure recovery, the inlet temperature rise, and the environmental effects of the hot gas. The environmental effects include the ground plane contours, the model airframe heating, and the location of the ground flow separation.

A Two-Phase Pilot Study to Evaluate the Safety and Tolerability of an In Situ Polymerizing Collagen.

PubMed

Inglefield, Christopher; Rone-McCrate, Rebecca; Brooks, Robert; Zhu, Jiaxun; Grant, Sheila; DeVore, Dale P

2017-09-01

Demand for collagen-based fillers has declined primarily because of limited long-term clinical benefit and the introduction of hyaluronic acid compositions. In situ polymerizing collagen is a noncrosslinked solution of porcine collagen containing a collagenase shield that undergoes fibrillogenesis on injected into tissues forming a natural matrix. Conduct a prospective, single-center, dual-phase open-label study in 8 subjects to evaluate the safety, tolerability, and efficacy of the porcine collagen composition. In Phase I, potential hypersensitivity of the collagen composition was evaluated after skin testing in the back (men) or forearms of subjects (women). In Phase II, subjects showing no signs of hypersensitivity received collagen injections into the nasolabial area followed by evaluation at 1, 4, 8, and 12 weeks using the Global Aesthetic Improvement Scale. None of the subjects had signs of hypersensitivity and all continued in Phase II. The treating physician(s) reported no post-treatment adverse events. Improvement of the nasolabial fold was observed by the physicians and confirmed by assessment of high-resolution photographs and Global Aesthetic Improvement Scale scores over the 12-week treatment were maintained. In this pilot clinical study in situ polymerizing collagen was shown to be safe and effective throughout the 3-month study period.

Spectrophotovoltaic orbital power generation, phase 2

NASA Technical Reports Server (NTRS)

Lo, S. K.; Stoltzman, D.; Knowles, G.; Lin, R.

1981-01-01

A subscale model of the spectral splitting concentrator system with 10" aperture is defined and designed. The model is basically a scaled down version of Phase 1 design with an effective concentration ratio up to 1000:1. The system performance is predicted to be 21.5% for the 2 cell GaAs/Si system, and 20% for Si/GaAs at AM2 using realistic component efficiencies. Component cost of the model is projected in the $50K range. Component and system test plans are also detailed.

Two-Phase Flow Instrumentation Review Group Meeting. Proceedings of Meeting Held in Silver Spring, Maryland on January 13-14, 1977

DTIC Science & Technology

1978-03-01

ADWRESS OInclud Zip Code) 10. PROJECTfTASK/WORK UNI1 VO. Same as 9. above. I1. CONTRACT NO. 13. TYPE OF REPORT PERIOD COVERED (inclusive dews ) Meeting...Discussion of basic principles. c. Lists of y-emitling tracers for gas ; for liquid; commercially available radioisotope milking systems; elements easily...factors) - single phase loops, full flow, (2) prototype calibration (a) gas -water loop, (b) geometry effect. (c) scaling. (3) proof testing - simulation of

Fresnel diffractograms from pure-phase wave fields under perfect spatio-temporal coherence: Non-linear/non-local aspects and far-field behavior.

PubMed

Trost, F; Hahn, S; Müller, Y; Gasilov, S; Hofmann, R; Baumbach, T

2017-12-18

Recently, the diffractogram, that is, the Fourier transform of the intensity contrast induced by Fresnel free-space propagation of a given (exit) wave field, was investigated non-perturbatively in the phase-scaling factor S (controlling the strength of phase variation) for the special case of a Gaussian phase of width [Formula: see text]. Surprisingly, an additional low-frequency zero σ *  = σ * (S, F) >0 emerges critically at small Fresnel number F (σ proportional to square of 2D spatial frequency). Here, we study the S-scaling behavior of the entire diffractogram. We identify a valley of maximum S-scaling linearity in the F - σ plane corresponding to a nearly universal physical frequency ξml = (0:143 ± 0.001)w -1/2 . Large values of F (near field) are shown to imply S-scaling linearity for low σ but nowhere else (overdamped non-oscillatory). In contrast, small F values (far field) entail distinct, sizable s-bands of good S-scaling linearity (damped oscillatory). These bands also occur in simulated diffractograms induced by a complex phase map (Lena). The transition from damped oscillatory to overdamped non-oscillatory diffractograms is shown to be a critical phenomenon for the Gaussian case. We also give evidence for the occurrence of this transition in an X-ray imaging experiment. Finally, we show that the extreme far-field limit generates a σ-universal diffractogram under certain requirements on the phase map: information on phase shape then is solely encoded in S-scaling behavior.

Ceramics Derived from Organo-Metallic Precursors

DTIC Science & Technology

1991-10-01

spraying, and roller-coating may also be used to good effect . The films deposited by any of these techniques are ready to be fired immediately...films. The wet chemical route offers great potential for highly cost- effective processing; and the critical issue for its wide-scale implementation is...glasses and subsequently to crystallize single phase HTSC materials. The fourth composition, 4223, was made in order to test the effect of Bi on glass

The Influence of Various Vibration Frequency on Barium Sulfate Scale Formation Of Vibrated Piping System In The Presence Citric Acid

NASA Astrophysics Data System (ADS)

Karaman, N.; Mangestiyono, W.; Muryanto, S.; Jamari, J.; Bayuseno, A. P.

2018-01-01

In this paper, the influence of vibrated piping system for BaSO4 scale formation was investigated. The vibration frequency and presence of citric acid were independent variables determining the kinetics, mass deposit and polymorph of the crystals. Correspondingly, induction time and mass of scale were obtained during the experiments. The crystalline scale was observed by scanning electron microscopy (SEM) and X-Ray Diffraction (XRD) to investigate the morphology and the phase mineral deposits, respectively. This effect indicated that the increase in vibration frequency promoted the increased deposition rate, while the pure barite with a plate-like morphology was produced in the experiments.

Phase-driven collapse of the Cooper condensate in a nanosized superconductor

NASA Astrophysics Data System (ADS)

Ronzani, Alberto; D'Ambrosio, Sophie; Virtanen, Pauli; Giazotto, Francesco; Altimiras, Carles

2017-12-01

Superconductivity can be understood in terms of a phase transition from an uncorrelated electron gas to a condensate of Cooper pairs in which the relative phases of the constituent electrons are coherent over macroscopic length scales. The degree of correlation is quantified by a complex-valued order parameter, whose amplitude is proportional to the strength of the pairing potential in the condensate. Supercurrent-carrying states are associated with nonzero values of the spatial gradient of the phase. The pairing potential and several physical observables of the Cooper condensate can be manipulated by means of temperature, current bias, dishomogeneities in the chemical composition, or application of a magnetic field. Here we show evidence of complete suppression of the energy gap in the local density of quasiparticle states (DOS) of a superconducting nanowire upon establishing a phase difference equal to π over a length scale comparable to the superconducting coherence length. These observations are consistent with a complete collapse of the pairing potential in the center of the wire, in accordance with theoretical modeling based on the quasiclassical theory of superconductivity in diffusive systems. Our spectroscopic data, fully exploring the phase-biased states of the condensate, highlight the profound effect that extreme phase gradients exert on the amplitude of the pairing potential. Moreover, the sharp magnetic response (up to 27 mV/Φ0) observed near the onset of the superconducting gap collapse regime is exploited to realize magnetic flux detectors with noise-equivalent resolution as low as 260 n Φ0/√{Hz} .

The effects of blocking in the subtropics on the phase speed of the MJO

NASA Astrophysics Data System (ADS)

Roundy, P. E.

2016-12-01

The phase speed of the MJO might be regulated by many different factors. Previous works have suggested that moist processes govern the phase speed, and our results show that intensification of convection is associated with reduction of phase speed down to about 5 ms-1. However, convection and rainfall decline with declining phase speeds below 5 ms-1. This presentation shows that increased Rossby wave breaking and blocking east of MJO deep convection is associated with reduced phase speed below about 6 ms-1. A wavelet filter is applied to extract time series characterized by selected zonal wavenumbers and frequencies at select equatorial base longitudes over the Indian and West Pacific Oceans. Results show that anomalies of active convection characterized by wavenumber 2 (the dominant scale of MJO convection over the warm pool) are associated with meridional potential vorticity (PV) gradients across the tropics to the east of the active convection that are near climatology for events moving east at 5 ms-1. These gradients are much weaker for slower events. The slowest phase speed events have almost no meridional PV gradients across the tropics between the mean latitudes of the subtropical jet streams, suggesting that jet exit regions occur immediately east of the deep convection, dumping mass in the upper troposphere over the region of suppressed convection. In the absence of PV gradients, synoptic to planetary scale waves moving into that environment break or cease to propagate linearly.

Development of an Efficient Meso- scale Multi-phase Flow Solver in Nuclear Applications

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

Lee, Taehun

2015-10-20

The proposed research aims at formulating a predictive high-order Lattice Boltzmann Equation for multi-phase flows relevant to nuclear energy related application - namely, saturated and sub-cooled boiling in reactors, and liquid- liquid mixing and extraction for fuel cycle separation. An efficient flow solver will be developed based on the Finite Element based Lattice Boltzmann Method (FE- LBM), accounting for phase-change heat transfer and capable of treating multiple phases over length scales from the submicron to the meter. A thermal LBM will be developed in order to handle adjustable Prandtl number, arbitrary specific heat ratio, a wide range of temperature variations,more » better numerical stability during liquid-vapor phase change, and full thermo-hydrodynamic consistency. Two-phase FE-LBM will be extended to liquid–liquid–gas multi-phase flows for application to high-fidelity simulations building up from the meso-scale up to the equipment sub-component scale. While several relevant applications exist, the initial applications for demonstration of the efficient methods to be developed as part of this project include numerical investigations of Critical Heat Flux (CHF) phenomena in nuclear reactor fuel bundles, and liquid-liquid mixing and interfacial area generation for liquid-liquid separations. In addition, targeted experiments will be conducted for validation of this advanced multi-phase model.« less

Effect of head group orientation on phospholipid assembly

NASA Astrophysics Data System (ADS)

Paul, Tanay; Saha, Jayashree

2017-06-01

The relationship between bilayer stability and lipid head group orientation is reported. In this work, molecular-dynamics simulations are performed to analyze the structure-property relationship of lipid biomembranes, taking into account coarse-grained model lipid interactions. The work explains the molecular scale mechanism of the phase behavior of lipid systems due to ion-lipid or anesthetic-lipid interactions, where reorientations of dipoles play a key role in modifying lipid phases and thereby alter biomembrane function. Our study demonstrates that simple dipolar reorientation is indeed sufficient in tuning a bilayer to a randomly flipped nonbilayer lamellar phase. This study may be used to assess the impact of changes in lipid phase characteristics on biomembrane structure due to the presence of anesthetics and ions.

Generation of ultra-long pure magnetization needle and multiple spots by phase modulated doughnut Gaussian beam

NASA Astrophysics Data System (ADS)

Udhayakumar, M.; Prabakaran, K.; Rajesh, K. B.; Jaroszewicz, Z.; Belafhal, Abdelmajid; Velauthapillai, Dhayalan

2018-06-01

Based on vector diffraction theory and inverse Faraday effect (IFE), the light induced magnetization distribution of a tightly focused azimuthally polarized doughnut Gaussian beam superimposed with a helical phase and modulated by an optimized multi belt complex phase filter (MBCPF) is analysed numerically. It is noted that by adjusting the radii of different rings of the complex phase filter, one can achieve many novel magnetization focal distribution such as sub wavelength scale (0.29λ) and super long (52.2λ) longitudinal magnetic probe suitable for all optical magnetic recording and the formation of multiple magnetization chain with four, six and eight sub-wavelength spherical magnetization spots suitable for multiple trapping of magnetic particles are achieved.

Multiple scales and phases in discrete chains with application to folded proteins

NASA Astrophysics Data System (ADS)

Sinelnikova, A.; Niemi, A. J.; Nilsson, Johan; Ulybyshev, M.

2018-05-01

Chiral heteropolymers such as large globular proteins can simultaneously support multiple length scales. The interplay between the different scales brings about conformational diversity, determines the phase properties of the polymer chain, and governs the structure of the energy landscape. Most importantly, multiple scales produce complex dynamics that enable proteins to sustain live matter. However, at the moment there is incomplete understanding of how to identify and distinguish the various scales that determine the structure and dynamics of a complex protein. Here we address this impending problem. We develop a methodology with the potential to systematically identify different length scales, in the general case of a linear polymer chain. For this we introduce and analyze the properties of an order parameter that can both reveal the presence of different length scales and can also probe the phase structure. We first develop our concepts in the case of chiral homopolymers. We introduce a variant of Kadanoff's block-spin transformation to coarse grain piecewise linear chains, such as the C α backbone of a protein. We derive analytically, and then verify numerically, a number of properties that the order parameter can display, in the case of a chiral polymer chain. In particular, we propose that in the case of a chiral heteropolymer the order parameter can reveal traits of several different phases, contingent on the length scale at which it is scrutinized. We confirm that this is the case with crystallographic protein structures in the Protein Data Bank. Thus our results suggest relations between the scales, the phases, and the complexity of folding pathways.

The surface roughness of (433) Eros as measured by thermal-infrared beaming

NASA Astrophysics Data System (ADS)

Rozitis, B.

2017-01-01

In planetary science, surface roughness is regarded to be a measure of surface irregularity at small spatial scales, and causes the thermal-infrared beaming effect (I.e. re-radiation of absorbed sunlight back towards to the Sun). Typically, surface roughness exhibits a degeneracy with thermal inertia when thermophysical models are fitted to disc-integrated thermal-infrared observations of asteroids because of this effect. In this work, it is demonstrated how surface roughness can be constrained for near-Earth asteroid (433) Eros (I.e. the target of NASA's NEAR Shoemaker mission) when using the Advanced Thermophysical Model with thermal-infrared observations taken during an `almost pole-on' illumination and viewing geometry. It is found that the surface roughness of (433) Eros is characterized by an rms slope of 38 ± 8° at the 0.5-cm spatial scale associated with its thermal-infrared beaming effect. This is slightly greater than the rms slope of 25 ± 5° implied by the NEAR Shoemaker laser ranging results when extrapolated to this spatial scale, and indicates that other surface shaping processes might operate, in addition to collisions and gravity, at spatial scales under one metre in order to make asteroid surfaces rougher. For other high-obliquity asteroids observed during `pole-on' illumination conditions, the thermal-infrared beaming effect allows surface roughness to be constrained when the sub-solar latitude is greater than 60°, and if the asteroids are observed at phase angles of less than 40°. They will likely exhibit near-Earth asteroid thermal model beaming parameters that are lower than expected for a typical asteroid at all phase angles up to 100°.

A study of geomagnetic storms

NASA Technical Reports Server (NTRS)

Patel, V. L.

1975-01-01

Twenty-one geomagnetic storm events during 1966 and 1970 were studied by using simultaneous interplanetary magnetic field and plasma parameters. Explorer 33 and 35 field and plasma data were analyzed on large-scale (hourly) and small-scale (3 min.) during the time interval coincident with initial phase of the geomagnetic storms. The solar-ecliptic Bz component turns southward at the end of the initial phase, thus triggering the main phase decrease in Dst geomagnetic field. When the Bz is already negative, its value becomes further negative. The By component also shows large fluctuations along with Bz. When there are no clear changes in the Bz component, the By shows abrupt changes at the main phase onet. On the small-scale behavior of the magnetic field and electric field (E=-VxB) studied in details for the three events, it is found that the field fluctuations in By, Bz and Ey and Ez are present in the initial phase. These fluctuations become larger just before the main phase of the storm begins. In the largescale behavior field remains quiet because the small scale variations are averaged out.

ALMA Long Baseline Campaigns: Phase Characteristics of Atmosphere at Long Baselines in the Millimeter and Submillimeter Wavelengths

NASA Astrophysics Data System (ADS)

Matsushita, Satoki; Asaki, Yoshiharu; Fomalont, Edward B.; Morita, Koh-Ichiro; Barkats, Denis; Hills, Richard E.; Kawabe, Ryohei; Maud, Luke T.; Nikolic, Bojan; Tilanus, Remo P. J.; Vlahakis, Catherine; Whyborn, Nicholas D.

2017-03-01

We present millimeter- and submillimeter-wave phase characteristics measured between 2012 and 2014 of Atacama Large Millimeter/submillimeter Array long baseline campaigns. This paper presents the first detailed investigation of the characteristics of phase fluctuation and phase correction methods obtained with baseline lengths up to ˜15 km. The basic phase fluctuation characteristics can be expressed with the spatial structure function (SSF). Most of the SSFs show that the phase fluctuation increases as a function of baseline length, with a power-law slope of ˜0.6. In many cases, we find that the slope becomes shallower (average of ˜0.2-0.3) at baseline lengths longer than ˜1 km, namely showing a turn-over in SSF. These power law slopes do not change with the amount of precipitable water vapor (PWV), but the fitted constants have a weak correlation with PWV, so that the phase fluctuation at a baseline length of 10 km also increases as a function of PWV. The phase correction method using water vapor radiometers (WVRs) works well, especially for the cases where PWV > 1 {mm}, which reduces the degree of phase fluctuations by a factor of two in many cases. However, phase fluctuations still remain after the WVR phase correction, suggesting the existence of other turbulent constituent that cause the phase fluctuation. This is supported by occasional SSFs that do not exhibit any turn-over; these are only seen when the PWV is low (i.e., when the WVR phase correction works less effectively) or after WVR phase correction. This means that the phase fluctuation caused by this turbulent constituent is inherently smaller than that caused by water vapor. Since in these rare cases there is no turn-over in the SSF up to the maximum baseline length of ˜15 km, this turbulent constituent must have scale height of 10 km or more, and thus cannot be water vapor, whose scale height is around 1 km. Based on the characteristics, this large scale height turbulent constituent is likely to be water ice or a dry component. Excess path length fluctuation after the WVR phase correction at a baseline length of 10 km is large (≳ 200 μ {{m}}), which is significant for high frequency (> 450 {GHz} or < 700 μ {{m}}) observations. These results suggest the need for an additional phase correction method to reduce the degree of phase fluctuation, such as fast switching, in addition to the WVR phase correction. We simulated the fast switching phase correction method using observations of single quasars, and the result suggests that it works well, with shorter cycle times linearly improving the coherence.

Dynamics of inhomogeneous chiral condensates

NASA Astrophysics Data System (ADS)

Carlomagno, Juan Pablo; Krein, Gastão; Kroff, Daniel; Peixoto, Thiago

2018-01-01

We study the dynamics of the formation of inhomogeneous chirally broken phases in the final stages of a heavy-ion collision, with particular interest on the time scales involved in the formation process. The study is conducted within the framework of a Ginzburg-Landau time evolution, driven by a free energy functional motivated by the Nambu-Jona-Lasinio model. Expansion of the medium is modeled by one-dimensional Bjorken flow and its effect on the formation of inhomogeneous condensates is investigated. We also use a free energy functional from a nonlocal Nambu-Jona-Lasinio model which predicts metastable phases that lead to long-lived inhomogeneous condensates before reaching an equilibrium phase with homogeneous condensates.

Howling at the moon? The effect of lunar phases on post-surgical pain outcome.

PubMed

Komann, Marcus; Weinmann, Claudia; Meissner, Winfried

2014-05-01

Many people are convinced that lunar phases influence their lives - despite the fact that a lot of studies have shown that this belief is wrong. In this article, we investigate the effect of lunar phases on acute post-surgical pain and on treatment-related side effects. We hypothesize that there is no influence. The data for the study were collected in 2010 and 2011 in 10 international hospitals participating in the research project PAIN OUT. Hospitalized patients were asked for their pain after surgery and pain treatment side effects using numerical ratings scales from 0 to 10. We applied Kurskal-Wallis H-tests to find out if the four moon phases show significant differences in 14 outcome variables. Afterwards, we adjusted for age, gender and three tracer surgeries. A total of 12,224 patient data sets were assessed. For most variables and sub-groups, there is no lunar effect on the observed outcome variables. The only items that show statistically significant differences are pain interference with sleep (p = 0.01) and drowsiness (p = 0.01). The only sub-groups that show statistically significant connections to lunar phases in some variables are men (7 out of 14 variables significant) and elderly people (4 out of 14 variables significant). Even in the statistically significant sub-groups, the differences are small and only show up in some variables. We conclude that lunar phases have no effect on post-surgical pain or its side effects. The hypothesis holds. Thus, there is no reason for patients to postpone surgeries or to fear surgeries on any given date.

Structural studies of degradation process of zirconium dioxide tetragonal phase induced by grinding with dental bur

NASA Astrophysics Data System (ADS)

Piosik, A.; Żurowski, K.; Pietralik, Z.; Hędzelek, W.; Kozak, M.

2017-11-01

Zirconium dioxide has been widely used in dental prosthetics. However, the improper mechanical treatment can induce changes in the microstructure of zirconium dioxide. From the viewpoint of mechanical properties and performance, the phase transitions of ZrO2 from the tetragonal to the monoclinic phase induced by mechanical processing, are particularly undesirable. In this study, the phase transitions of yttrium stabilized zirconium dioxide (Y-TZP) induced by mechanical treatment are investigated by the scanning electron microscopy (SEM), atomic force microscopy (AFM) and powder diffraction (XRD). Mechanical stress was induced by different types of drills used presently in dentistry. At the same time the surface temperature was monitored during milling using a thermal imaging camera. Diffraction analysis allowed determination of the effect of temperature and mechanical processing on the scale of induced changes. The observed phase transition to the monoclinic phase was correlated with the methods of mechanical processing.

Pretransitional phenomena and pinning in liquid-crystalline blue phases

NASA Astrophysics Data System (ADS)

Demikhov, E.; Stegemeyer, H.; Tsukruk, V.

1992-10-01

Blue phases (BP's) in liquid-crystalline systems of high chirality exhibiting a short cholesteric temperature interval are investigated. In a BP I supercooled with respect to the cholesteric phase, the orientation of the cubic lattice with the (1,1,0) wave vector perpendicular to the substrate is spontaneously turned to a [200] orientation within small areas of several tenths of micrometers in diameter. A pinning of BP I lattice temperature waves is observed on the [200] orientational inhomogeneities. The pinning effect explains the observed saturation of the BP I lattice constant on decreasing temperature and its dependence on the cooling rate observed in supercooled region. A different type of cubic blue phase, BP S (``S'' represents supercooled), is observed transforming reversibly from the supercooled BP I but metastable with respect to the cholesteric phase. The BP S has two scales of order: a long-range orientational blue-phase-like order and a short-range positional smecticlike order.

Rehabilitation needs and participation restriction in patients with cognitive disorder in the chronic phase of traumatic brain injury

PubMed Central

Sashika, Hironobu; Takada, Kaoruko; Kikuchi, Naohisa

2017-01-01

Abstract The purpose of this study was to clarify psychosocial factors/problems, social participation, quality of life (QOL), and rehabilitation needs in chronic-phase traumatic brain injury (TBI) patients with cognitive disorder discharged from the level-1 trauma center (L1-TC), and to inspect the effects of rehabilitation intervention to these subjects. A mixed-method research (cross-sectional and qualitative study) was conducted at an outpatient rehabilitation department. Inclusion criteria of subjects were transfer to the L1-TC due to TBI; acute-stage rehabilitation treatment received in the L1-TC from November 2006 to October 2011; age of ≥18 and <70 years at the time of injury; a score of 0–3 on the Modified Rankin Scale at discharge and that of 4–5 due to physical or severe aggressive behavioral comorbid disorders. Study details were sent, via mail, to 84 suitable candidates, of whom 36 replied. Thirty-one subjects (median age: 33.4 years; male: 17; and average time since injury: 48.1 months), who had consented to study participation, were participated. Cognitive function, social participation, QOL, psychosocial factors/problems, rehabilitation needs, and chronic-phase rehabilitation outcomes were evaluated using the Wechsler Adult Intelligence Scale, Third Edition, the Wechsler Memory Scale-Revised, the Zung Self-Rating Depression Scale, the Sydney Psychosocial Reintegration Scale, Version 2, and the Short Form 36, Version 2, qualitative analysis of semistructured interviews, etc. Participants were classified into achieved-social-participation (n = 11; employed: 8), difficult-social-participation (n = 12; unemployed: 8), and no-cognitive-dysfunction groups (n = 8; no social participation restriction). Relative to the achieved-social-participation group, the difficult-social-participation group showed greater injury and cognitive dysfunction and lower Sydney Psychosocial Reintegration Scale and Short Form 36 role/social component summary scores (64.9/49.1 vs 44.3/30.4, respectively, P < 0.05). Linear regression analysis showed that the social participation status was greatly affected by the later cognitive disorders and psychosocial factors/problems not by the severity of TBI. No changes were observed in these scores following chronic-phase rehabilitation intervention. Chronic-phase TBI with cognitive disorder led to rehabilitation needs, and improvement of subjects’ psychosocial problems and QOL was difficult. PMID:28121947

Rehabilitation needs and participation restriction in patients with cognitive disorder in the chronic phase of traumatic brain injury.

PubMed

Sashika, Hironobu; Takada, Kaoruko; Kikuchi, Naohisa

2017-01-01

The purpose of this study was to clarify psychosocial factors/problems, social participation, quality of life (QOL), and rehabilitation needs in chronic-phase traumatic brain injury (TBI) patients with cognitive disorder discharged from the level-1 trauma center (L1-TC), and to inspect the effects of rehabilitation intervention to these subjects.A mixed-method research (cross-sectional and qualitative study) was conducted at an outpatient rehabilitation department.Inclusion criteria of subjects were transfer to the L1-TC due to TBI; acute-stage rehabilitation treatment received in the L1-TC from November 2006 to October 2011; age of ≥18 and <70 years at the time of injury; a score of 0-3 on the Modified Rankin Scale at discharge and that of 4-5 due to physical or severe aggressive behavioral comorbid disorders. Study details were sent, via mail, to 84 suitable candidates, of whom 36 replied. Thirty-one subjects (median age: 33.4 years; male: 17; and average time since injury: 48.1 months), who had consented to study participation, were participated. Cognitive function, social participation, QOL, psychosocial factors/problems, rehabilitation needs, and chronic-phase rehabilitation outcomes were evaluated using the Wechsler Adult Intelligence Scale, Third Edition, the Wechsler Memory Scale-Revised, the Zung Self-Rating Depression Scale, the Sydney Psychosocial Reintegration Scale, Version 2, and the Short Form 36, Version 2, qualitative analysis of semistructured interviews, etc.Participants were classified into achieved-social-participation (n = 11; employed: 8), difficult-social-participation (n = 12; unemployed: 8), and no-cognitive-dysfunction groups (n = 8; no social participation restriction). Relative to the achieved-social-participation group, the difficult-social-participation group showed greater injury and cognitive dysfunction and lower Sydney Psychosocial Reintegration Scale and Short Form 36 role/social component summary scores (64.9/49.1 vs 44.3/30.4, respectively, P < 0.05). Linear regression analysis showed that the social participation status was greatly affected by the later cognitive disorders and psychosocial factors/problems not by the severity of TBI. No changes were observed in these scores following chronic-phase rehabilitation intervention.Chronic-phase TBI with cognitive disorder led to rehabilitation needs, and improvement of subjects' psychosocial problems and QOL was difficult.

Effect of lensing non-Gaussianity on the CMB power spectra

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

Lewis, Antony; Pratten, Geraint, E-mail: antony@cosmologist.info, E-mail: geraint.pratten@gmail.com

2016-12-01

Observed CMB anisotropies are lensed, and the lensed power spectra can be calculated accurately assuming the lensing deflections are Gaussian. However, the lensing deflections are actually slightly non-Gaussian due to both non-linear large-scale structure growth and post-Born corrections. We calculate the leading correction to the lensed CMB power spectra from the non-Gaussianity, which is determined by the lensing bispectrum. Assuming no primordial non-Gaussianity, the lowest-order result gives ∼ 0.3% corrections to the BB and EE polarization spectra on small-scales. However we show that the effect on EE is reduced by about a factor of two by higher-order Gaussian lensing smoothing,more » rendering the total effect safely negligible for the foreseeable future. We give a simple analytic model for the signal expected from skewness of the large-scale lensing field; the effect is similar to a net demagnification and hence a small change in acoustic scale (and therefore out of phase with the dominant lensing smoothing that predominantly affects the peaks and troughs of the power spectrum).« less

Comparing different stimulus configurations for population receptive field mapping in human fMRI

PubMed Central

Alvarez, Ivan; de Haas, Benjamin; Clark, Chris A.; Rees, Geraint; Schwarzkopf, D. Samuel

2015-01-01

Population receptive field (pRF) mapping is a widely used approach to measuring aggregate human visual receptive field properties by recording non-invasive signals using functional MRI. Despite growing interest, no study to date has systematically investigated the effects of different stimulus configurations on pRF estimates from human visual cortex. Here we compared the effects of three different stimulus configurations on a model-based approach to pRF estimation: size-invariant bars and eccentricity-scaled bars defined in Cartesian coordinates and traveling along the cardinal axes, and a novel simultaneous “wedge and ring” stimulus defined in polar coordinates, systematically covering polar and eccentricity axes. We found that the presence or absence of eccentricity scaling had a significant effect on goodness of fit and pRF size estimates. Further, variability in pRF size estimates was directly influenced by stimulus configuration, particularly for higher visual areas including V5/MT+. Finally, we compared eccentricity estimation between phase-encoded and model-based pRF approaches. We observed a tendency for more peripheral eccentricity estimates using phase-encoded methods, independent of stimulus size. We conclude that both eccentricity scaling and polar rather than Cartesian stimulus configuration are important considerations for optimal experimental design in pRF mapping. While all stimulus configurations produce adequate estimates, simultaneous wedge and ring stimulation produced higher fit reliability, with a significant advantage in reduced acquisition time. PMID:25750620

Comparison of Ice Cloud Particle Sizes Retrieved From Satellite Data Derived From In Situ Measurements

NASA Technical Reports Server (NTRS)

Han, Qingyuan; Rossow, William B.; Chou, Joyce; Welch, Ronald M.

1997-01-01

Cloud microphysical parameterizations have attracted a great deal of attention in recent years due to their effect on cloud radiative properties and cloud-related hydrological processes in large-scale models. The parameterization of cirrus particle size has been demonstrated as an indispensable component in the climate feedback analysis. Therefore, global-scale, long-term observations of cirrus particle sizes are required both as a basis of and as a validation of parameterizations for climate models. While there is a global scale, long-term survey of water cloud droplet sizes (Han et al. 1994), there is no comparable study for cirrus ice crystals. In this paper a near-global survey of cirrus ice crystal sizes is conducted using ISCCP satellite data analysis. The retrieval scheme uses phase functions based upon hexagonal crystals calculated by a ray tracing technique. The results show that global mean values of D(e) are about 60 micro-m. This study also investigates the possible reasons for the significant difference between satellite retrieved effective radii (approx. 60 micro-m) and aircraft measured particle sizes (approx. 200 micro-m) during the FIRE I IFO experiment. They are (1) vertical inhomogeneity of cirrus particle sizes; (2) lower limit of the instrument used in aircraft measurements; (3) different definitions of effective particle sizes; and (4) possible inappropriate phase functions used in satellite retrieval.

Economic evaluation of public-private mix for tuberculosis care and control, India. Part II. Cost and cost-effectiveness.

PubMed

Pantoja, A; Lönnroth, K; Lal, S S; Chauhan, L S; Uplekar, M; Padma, M R; Unnikrishnan, K P; Rajesh, J; Kumar, P; Sahu, S; Wares, F; Floyd, K

2009-06-01

Bangalore City, India. To assess the cost and cost-effectiveness of public-private mix (PPM) for tuberculosis (TB) care and control when implemented on a large scale. DOTS implementation under the Revised National TB Control Programme (RNTCP) began in 1999, PPM was introduced in mid-2001 and a second phase of intensified PPM began in 2003. Data on the costs and effects of TB treatment from 1999 to 2005 were collected and used to compare the two distinct phases of PPM with a scenario of no PPM. Costs were assessed in 2005 $US for public and private providers, patients and patient attendants. Sources of data included expenditure records, medical records, interviews with staff and patient surveys. Effectiveness was measured as the number of cases successfully treated. When PPM was implemented, total provider costs increased in proportion to the number of successfully treated TB cases. The average cost per patient treated from the provider perspective when PPM was implemented was stable, at US$69, in the intensified phase compared with US$71 pre-PPM. PPM resulted in the shift of an estimated 7200 patients from non-DOTS to DOTS treatment over 5 years. PPM implementation substantially reduced costs to patients, such that the average societal cost per patient successfully treated fell from US$154 to US$132 in the 4 years following the initiation of PPM. Implementation of PPM on a large scale in an urban setting can be cost-effective, and considerably reduces the financial burden of TB for patients.

A Global Survey of Oceanic Mesoscale Convective Systems in Association with the Large-scale Water Vapor and Vertical Wind Shear

NASA Astrophysics Data System (ADS)

Yuan, J.; Zhan, T.

2017-12-01

Sizes and organizations of mesoscale scale convective systems (MCSs) usually are related to both their precipitation characteristics and anvil productivity, which are crucial but not well-represented in current climate models. This study aims to further our knowledge about MCSs by documenting the relationship between MCSs and their associated large-scale environmental moisture and wind shear in different phases of large-scale convection. A dataset derived from MODIS and AMSR-E and TRMM, CMOPH and ERA-Interim reanalysis are used. Larger and merged systems tend to occur more frequently when the large-scale convection is stronger. At the occurrence time of MCSs, the middle troposphere relative humidity (MRH, 800-400hPa) shows large increases ( 15%) from the suppressed to the active phases. Differences of the MRH across phases appear in a large area and reaches its maximum at 650 850 km away from the center of MCSs. Higher MRH is found within 650 km around the center of merged and large MCSs in all phases. This distance is much larger than the size of any single MCSs. The MRH shows larger spatial gradients around merged MCSs, indicating that moisture tends to cluster around merged systems. Similar spatial differences of MRH appear at all phases 1-3 days before the MCSs occur. In lower troposphere (1000-850hPa), differences in the relative humidity are much smaller than that of MRH. In all phases around all MCSs the oceanic boundary layer is always effectively moisturized (RH>92%). Temporally the lower troposphere relative humidity is dominated by diurnal variations. No clear difference across systems of the wind shear is found when the domain-wide upward motion is dominated. In all cases there are always large low-level (1000-750hPa) wind shear (7-9m/s) and middle level (1000-750hPa) wind shear (11-15m/s) occurring at large distances (>500km) away from MCSs. However, both the low-level and the middle level wind shear closely around the MCSs converge to moderate values of 3-4.2m/s and 5-7m/s, respectively. Indicating that weak or moderate wind shear conditions favor developments of MCSs. Small but systematical differences in wind shear across phases are found. This study provides an observational reference for both cloud resovling or climate models to diagnose and improve their representaions of organized convection.

ON-SITE ENGINEERING REPORT OF THE SLURRY-PHASE BIOLOGICAL REACTOR FOR PILOT-SCALE TESTING ON CONTAMINATED SOIL

EPA Science Inventory

The performance of pilot-scale bioslurry treatment on creosote-contaminated soil was evaluated. Five reactors containing 66 L of slurry (30% soil by weight), were operated in parallel. The soil was a sandy soil with minor gravel content. The pilot-scale phase utilized an inoculum...

Dark energy in six nearby galaxy flows: Synthetic phase diagrams and self-similarity

NASA Astrophysics Data System (ADS)

Chernin, A. D.; Teerikorpi, P.; Dolgachev, V. P.; Kanter, A. A.; Domozhilova, L. M.; Valtonen, M. J.; Byrd, G. G.

2012-09-01

Outward flows of galaxies are observed around groups of galaxies on spatial scales of about 1 Mpc, and around galaxy clusters on scales of 10 Mpc. Using recent data from the Hubble Space Telescope (HST), we have constructed two synthetic velocity-distance phase diagrams: one for four flows on galaxy-group scales and the other for two flows on cluster scales. It has been shown that, in both cases, the antigravity produced by the cosmic dark-energy background is stronger than the gravity produced by the matter in the outflow volume. The antigravity accelerates the flows and introduces a phase attractor that is common to all scales, corresponding to a linear velocity-distance relation (the local Hubble law). As a result, the bundle of outflow trajectories mostly follow the trajectory of the attractor. A comparison of the two diagrams reveals the universal self-similar nature of the outflows: their gross phase structure in dimensionless variables is essentially independent of their physical spatial scales, which differ by approximately a factor of 10 in the two diagrams.

Comparison of theory and experiment for NAPL dissolution in porous media

NASA Astrophysics Data System (ADS)

Bahar, T.; Golfier, F.; Oltéan, C.; Lefevre, E.; Lorgeoux, C.

2018-04-01

Contamination of groundwater resources by an immiscible organic phase commonly called NAPL (Non Aqueous Phase Liquid) represents a major scientific challenge considering the residence time of such a pollutant. This contamination leads to the formation of NAPL blobs trapped in the soil and impact of this residual saturation cannot be ignored for correct predictions of the contaminant fate. In this paper, we present results of micromodel experiments on the dissolution of pure hydrocarbon phase (toluene). They were conducted for two values of the Péclet number. These experiments provide data for comparison and validation of a two-phase non-equilibrium theoretical model developed by Quintard and Whitaker (1994) using the volume averaging method. The model was directly upscaled from the averaged pore-scale mass balance equations. The effective properties of the macroscopic model were calculated over periodic unit cells designed from images of the experimental flow cell. Comparison of experimental and numerical results shows that the transport model predicts correctly - with no fitting parameters - the main mechanisms of NAPL mass transfer. The study highlights the crucial need of having a fair recovery of pore-scale characteristic lengths to predict the mass transfer coefficient with accuracy.

Experimental and code simulation of a station blackout scenario for APR1400 with test facility ATLAS and MARS code

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

Yu, X. G.; Kim, Y. S.; Choi, K. Y.

2012-07-01

A SBO (station blackout) experiment named SBO-01 was performed at full-pressure IET (Integral Effect Test) facility ATLAS (Advanced Test Loop for Accident Simulation) which is scaled down from the APR1400 (Advanced Power Reactor 1400 MWe). In this study, the transient of SBO-01 is discussed and is subdivided into three phases: the SG fluid loss phase, the RCS fluid loss phase, and the core coolant depletion and core heatup phase. In addition, the typical phenomena in SBO-01 test - SG dryout, natural circulation, core coolant boiling, the PRZ full, core heat-up - are identified. Furthermore, the SBO-01 test is reproduced bymore » the MARS code calculation with the ATLAS model which represents the ATLAS test facility. The experimental and calculated transients are then compared and discussed. The comparison reveals there was malfunction of equipments: the SG leakage through SG MSSV and the measurement error of loop flow meter. As the ATLAS model is validated against the experimental results, it can be further employed to investigate the other possible SBO scenarios and to study the scaling distortions in the ATLAS. (authors)« less

Status of the Flooding Fragility Testing Development

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

Pope, C. L.; Savage, B.; Bhandari, B.

2016-06-01

This report provides an update on research addressing nuclear power plant component reliability under flooding conditions. The research includes use of the Component Flooding Evaluation Laboratory (CFEL) where individual components and component subassemblies will be tested to failure under various flooding conditions. The resulting component reliability data can then be incorporated with risk simulation strategies to provide a more thorough representation of overall plant risk. The CFEL development strategy consists of four interleaved phases. Phase 1 addresses design and application of CFEL with water rise and water spray capabilities allowing testing of passive and active components including fully electrified components.more » Phase 2 addresses research into wave generation techniques followed by the design and addition of the wave generation capability to CFEL. Phase 3 addresses methodology development activities including small scale component testing, development of full scale component testing protocol, and simulation techniques including Smoothed Particle Hydrodynamic (SPH) based computer codes. Phase 4 involves full scale component testing including work on full scale component testing in a surrogate CFEL testing apparatus.« less

Large-scale three-dimensional phase-field simulations for phase coarsening at ultrahigh volume fraction on high-performance architectures

NASA Astrophysics Data System (ADS)

Yan, Hui; Wang, K. G.; Jones, Jim E.

2016-06-01

A parallel algorithm for large-scale three-dimensional phase-field simulations of phase coarsening is developed and implemented on high-performance architectures. From the large-scale simulations, a new kinetics in phase coarsening in the region of ultrahigh volume fraction is found. The parallel implementation is capable of harnessing the greater computer power available from high-performance architectures. The parallelized code enables increase in three-dimensional simulation system size up to a 5123 grid cube. Through the parallelized code, practical runtime can be achieved for three-dimensional large-scale simulations, and the statistical significance of the results from these high resolution parallel simulations are greatly improved over those obtainable from serial simulations. A detailed performance analysis on speed-up and scalability is presented, showing good scalability which improves with increasing problem size. In addition, a model for prediction of runtime is developed, which shows a good agreement with actual run time from numerical tests.

A Physical Model to Study the Effects of Nozzle Design on Dispersed Two-Phase Flows in a Slab Mold Casting Ultra-Low-Carbon Steels

NASA Astrophysics Data System (ADS)

Salazar-Campoy, María M.; Morales, R. D.; Nájera-Bastida, A.; Calderón-Ramos, Ismael; Cedillo-Hernández, Valentín; Delgado-Pureco, J. C.

2018-04-01

The effects of nozzle design on dispersed, two-phase flows of the steel-argon system in a slab mold are studied using a water-air model with particle image velocimetry and ultrasound probe velocimetry techniques. Three nozzle designs were tested with the same bore size and different port geometries, including square (S), special bottom design with square ports (U), and circular (C). The meniscus velocities of the liquid increase two- or threefold in two-phase flows regarding one-phase flows using low flow rates of the gas phase. This effect is due to the dragging effects on bubbles by the liquid jets forming two-way coupled flows. Liquid velocities (primary phase) along the narrow face of the mold also are higher for two-phase flows. Flows using nozzle U are less dependent on the effects of the secondary phase (air). The smallest bubble sizes are obtained using nozzle U, which confirms that bubble breakup is dependent on the strain rates of the fluid and dissipation of kinetic energy in the nozzle bottom and port edges. Through dimensionless analysis, it was found that the bubble sizes are inversely proportional to the dissipation rate of the turbulent kinetic energy, ɛ 0.4. A simple expression involving ɛ, surface tension, and density of metal is derived to scale up bubble sizes in water to bubble sizes in steel with different degrees of deoxidation. The validity of water-air models to study steel-argon flows is discussed. Prior works related with experiments to model argon bubbling in steel slab molds under nonwetting conditions are critically reviewed.

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

Durham, M.D.

The purpose of this research program is to identify and evaluate a variety of additives capable of increasing particle cohesion which could be used for improving collection efficiency in an ESP. A three-phase screening process will be used to provide the, evaluation of many additives in a logical and cost-effective manner. The three step approach involves the following experimental setups: 1. Provide a preliminary screening in the laboratory by measuring the effects of various conditioning agents on reentrainment of flyash particles in an electric field operating at simulated flue gas conditions. 2. Evaluate the successful additives using a 100 acfmmore » bench-scale ESP operating on actual flue gas. 3. Obtain the data required for scaling up the technology by testing the two or three most promising conditioning agents at the pilot scale.« less

Why do large and small scales couple in a turbulent boundary layer?

NASA Astrophysics Data System (ADS)

Bandyopadhyay, Promode R.

2011-11-01

Correlation measurement, which is not definitive, suggests that large and small scales in a turbulent boundary layer (TBL) couple. A TBL is modeled as a jungle of interacting nonlinear oscillators to explore the origin of the coupling. These oscillators have the inherent property of self-sustainability, disturbance rejection, and of self-referential phase reset whereby several oscillators can phase align (or have constant phase difference between them) when an ``external'' impulse is applied. Consequently, these properties of a TBL are accounted for: self-sustainability, return of the wake component after a disturbance is removed, and the formation of the 18o large structures, which are composed of a sequential train of hairpin vortices. The nonlinear ordinary differential equations of the oscillators are solved using an analog circuit for rapid solution. The post-bifurcation limit cycles are determined. A small scale and a large scale are akin to two different oscillators. The state variables from the two disparate interacting oscillators are shown to couple and the small scales appear at certain regions of the phase of the large scale. The coupling is a consequence of the nonlinear oscillatory behavior. Although state planes exist where the disparate scales appear de-superposed, all scales in a TBL are in fact coupled and they cannot be monochromatically isolated.

Bench Scale Process for Low Cost CO 2 Capture Using a Phase-Changing Absorbent: Final Scientific/Technical Report

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

Westendorf, Tiffany; Buddle, Stanlee; Caraher, Joel

The objective of this project is to design and build a bench-scale process for a novel phase-changing aminosilicone-based CO 2-capture solvent. The project will establish scalability and technical and economic feasibility of using a phase-changing CO 2-capture absorbent for post-combustion capture of CO 2 from coal-fired power plants. The U.S. Department of Energy’s goal for Transformational Carbon Capture Technologies is the development of technologies available for demonstration by 2025 that can capture 90% of emitted CO 2 with at least 95% CO 2 purity for less than $40/tonne of CO 2 captured. In the first budget period of the project,more » the bench-scale phase-changing CO2 capture process was designed using data and operating experience generated under a previous project (ARPA-e project DE-AR0000084). Sizing and specification of all major unit operations was completed, including detailed process and instrumentation diagrams. The system was designed to operate over a wide range of operating conditions to allow for exploration of the effect of process variables on CO 2 capture performance. In the second budget period of the project, individual bench-scale unit operations were tested to determine the performance of each of each unit. Solids production was demonstrated in dry simulated flue gas across a wide range of absorber operating conditions, with single stage CO 2 conversion rates up to 75mol%. Desorber operation was demonstrated in batch mode, resulting in desorption performance consistent with the equilibrium isotherms for GAP-0/CO 2 reaction. Important risks associated with gas humidity impact on solids consistency and desorber temperature impact on thermal degradation were explored, and adjustments to the bench-scale process were made to address those effects. Corrosion experiments were conducted to support selection of suitable materials of construction for the major unit operations in the process. The bench scale unit operations were assembled into a continuous system to support steady state system testing. In the third budget period of the project, continuous system testing was conducted, including closed-loop operation of the absorber and desober systems. Slurries of GAP-0/GAP-0 carbamate/water mixtures produced in the absorber were pumped successfully to the desorber unit, and regenerated solvent was returned to the absorber. A techno-economic analysis, EH&S risk assessment, and solvent manufacturability study were completed.« less

Multi-scale mantle structure underneath the Americas from a new tomographic model of seismic shear velocity

NASA Astrophysics Data System (ADS)

Porritt, R. W.; Becker, T. W.; Auer, L.; Boschi, L.

2017-12-01

We present a whole-mantle, variable resolution, shear-wave tomography model based on newly available and existing seismological datasets including regional body-wave delay times and multi-mode Rayleigh and Love wave phase delays. Our body wave dataset includes 160,000 S wave delays used in the DNA13 regional tomographic model focused on the western and central US, 86,000 S and SKS delays measured on stations in western South America (Porritt et al., in prep), and 3,900,000 S+ phases measured by correlation between data observed at stations in the IRIS global networks (IU, II) and stations in the continuous US, against synthetic data generated with IRIS Syngine. The surface wave dataset includes fundamental mode and overtone Rayleigh wave data from Schaeffer and Levedev (2014), ambient noise derived Rayleigh wave and Love wave measurements from Ekstrom (2013), newly computed fundamental mode ambient noise Rayleigh wave phase delays for the continuous US up to July 2017, and other, previously published, measurements. These datasets, along with a data-adaptive parameterization utilized for the SAVANI model (Auer et al., 2014), should allow significantly finer-scale imaging than previous global models, rivaling that of regional-scale approaches, under the USArray footprint in the continuous US, while seamlessly integrating into a global model. We parameterize the model for both vertically (vSV) and horizontally (vSH) polarized shear velocities by accounting for the different sensitivities of the various phases and wave types. The resulting, radially anisotropic model should allow for a range of new geodynamic analysis, including estimates of mantle flow induced topography or seismic anisotropy, without generating artifacts due to edge effects, or requiring assumptions about the structure of the region outside the well resolved model space. Our model shows a number of features, including indications of the effects of edge-driven convection in the Cordillera and along the eastern margin and larger-scale convection due to the subduction of the Farallon slab and along the edge of the Laurentia cratonic margin.

Multiscale correlations of iron phases and heavy metals in technogenic magnetic particles from contaminated soils.

PubMed

Yu, Xiuling; Lu, Shenggao

2016-12-01

Technogenic magnetic particles (TMPs) are carriers of heavy metals and organic contaminants, which derived from anthropogenic activities. However, little information on the relationship between heavy metals and TMP carrier phases at the micrometer scale is available. This study determined the distribution and association of heavy metals and magnetic phases in TMPs in three contaminated soils at the micrometer scale using micro-X-ray fluorescence (μ-XRF) and micro-X-ray absorption near-edge structure (μ-XANES) spectroscopy. Multiscale correlations of heavy metals in TMPs were elucidated using wavelet transform analysis. μ-XRF mapping showed that Fe was enriched and closely correlated with Co, Cr, and Pb in TMPs from steel industrial areas. Fluorescence mapping and wavelet analysis showed that ferroalloy was a major magnetic signature and heavy metal carrier in TMPs, because most heavy metals were highly associated with ferroalloy at all size scales. Multiscale analysis revealed that heavy metals in the TMPs were from multiple sources. Iron K-edge μ-XANES spectra revealed that metallic iron, ferroalloy, and magnetite were the main iron magnetic phases in the TMPs. The relative percentage of these magnetic phases depended on their emission sources. Heatmap analysis revealed that Co, Pb, Cu, Cr, and Ni were mainly derived from ferroalloy particles, while As was derived from both ferroalloy and metallic iron phases. Our results indicated the scale-dependent correlations of magnetic phases and heavy metals in TMPs. The combination of synchrotron based X-ray microprobe techniques and multiscale analysis provides a powerful tool for identifying the magnetic phases from different sources and quantifying the association of iron phases and heavy metals at micrometer scale. Copyright © 2016 Elsevier Ltd. All rights reserved.

Symptom rating scale for assessing hyperthyroidism.

PubMed

Klein, I; Trzepacz, P T; Roberts, M; Levey, G S

1988-02-01

A hyperthyroid symptom scale (HSS) was designed and administered to ten subjects with untreated Graves' disease. All subjects had clinical and chemical evidence of hyperthyroidism and reproducible HSS scores of 20 or more points. During sequential treatments with propranolol hydrochloride (phase 2) followed by propylthiouracil (phase 3) there was a significant decline in the HSS scores at each phase. Accompanying the decrease in HSS scores was a decrease in heart rate, but there was no change in thyroid function test results at phase 2 and a decrease in heart rate, thyroid function test results, and goiter size at phase 3. This new scale includes ten categories of symptoms, it is sensitive to changes in both the adrenergic and metabolic components of hyperthyroidism, and it is useful in the clinical assessment and management of patients with thyrotoxicosis.

Nonlinear interferometry approach to photonic sequential logic

NASA Astrophysics Data System (ADS)

Mabuchi, Hideo

2011-10-01

Motivated by rapidly advancing capabilities for extensive nanoscale patterning of optical materials, I propose an approach to implementing photonic sequential logic that exploits circuit-scale phase coherence for efficient realizations of fundamental components such as a NAND-gate-with-fanout and a bistable latch. Kerr-nonlinear optical resonators are utilized in combination with interference effects to drive the binary logic. Quantum-optical input-output models are characterized numerically using design parameters that yield attojoule-scale energy separation between the latch states.

Non-Abelian Bosonization and Fractional Quantum Hall Transitions

NASA Astrophysics Data System (ADS)

Hui, Aaron; Mulligan, Michael; Kim, Eun-Ah

A fully satisfying theoretical description for the quantum phase transition between fractional quantum Hall plateaus remains an outstanding problem. Experiments indicate scaling exponents that are not readily obtained in conventional theories. Using insights from duality, we describe a class of quantum critical effective theories that produce qualitatively realistic scaling exponents for the transition. We discuss the implications of our results for the physically-relevant interactions controlling this broad class of quantum critical behavior. Supported by National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1650441.

Fire Hazards from Combustible Ammunition, Methodology Development. Phase I

DTIC Science & Technology

1980-06-01

5.3 Flame Length , Flame Diameter and Mass Burning Rate 37 5.4 Flame Emissive Power 41 5.5 Fire Plume Axial Gas Velocity 41 5.6 Flame Temperature...B.2 Exit Velocity 93 B.3 Rate of Energy Flow 93 B.4 Chamber Characteristics 94 B.5 Flame Length 95 B.6 Flame Lift Angle 95 B.7 Summary 97...Viewing Flame in Test Series 5 17. Flame Length Scaling 18. Scaling Trends for Mass Burning Rate 19. Effective Flame Emissive Power versus Flame

Scaling of Tripartite Entanglement at Impurity Quantum Phase Transitions.

PubMed

Bayat, Abolfazl

2017-01-20

The emergence of a diverging length scale in many-body systems at a quantum phase transition implies that total entanglement has to reach its maximum there. In order to fully characterize this, one has to consider multipartite entanglement as, for instance, bipartite entanglement between individual particles fails to signal this effect. However, quantification of multipartite entanglement is very hard, and detecting it may not be possible due to the lack of accessibility to all individual particles. For these reasons it will be more sensible to partition the system into relevant subsystems, each containing a few to many spins, and study entanglement between those constituents as a coarse-grain picture of multipartite entanglement between individual particles. In impurity systems, famously exemplified by two-impurity and two-channel Kondo models, it is natural to divide the system into three parts, namely, impurities and the left and right bulks. By exploiting two tripartite entanglement measures, based on negativity, we show that at impurity quantum phase transitions the tripartite entanglement diverges and shows scaling behavior. While the critical exponents are different for each tripartite entanglement measure, they both provide very similar critical exponents for the two-impurity and the two-channel Kondo models, suggesting that they belong to the same universality class.

Evolution of the phase-space density and the Jeans scale for dark matter derived from the Vlasov-Einstein equation

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

Piattella, O.F.; Rodrigues, D.C.; Fabris, J.C.

2013-11-01

We discuss solutions of Vlasov-Einstein equation for collisionless dark matter particles in the context of a flat Friedmann universe. We show that, after decoupling from the primordial plasma, the dark matter phase-space density indicator Q = ρ/(σ{sub 1D}{sup 2}){sup 3/2} remains constant during the expansion of the universe, prior to structure formation. This well known result is valid for non-relativistic particles and is not ''observer dependent'' as in solutions derived from the Vlasov-Poisson system. In the linear regime, the inclusion of velocity dispersion effects permits to define a physical Jeans length for collisionless matter as function of the primordial phase-spacemore » density indicator: λ{sub J} = (5π/G){sup 1/2}Q{sup −1/3}ρ{sub dm}{sup −1/6}. The comoving Jeans wavenumber at matter-radiation equality is smaller by a factor of 2-3 than the comoving wavenumber due to free-streaming, contributing to the cut-off of the density fluctuation power spectrum at the lowest scales. We discuss the physical differences between these two scales. For dark matter particles of mass equal to 200 GeV, the derived Jeans mass is 4.3 × 10{sup −6}M{sub ⊙}.« less

Bubble Size Distribution in a Vibrating Bubble Column

NASA Astrophysics Data System (ADS)

Mohagheghian, Shahrouz; Wilson, Trevor; Valenzuela, Bret; Hinds, Tyler; Moseni, Kevin; Elbing, Brian

2016-11-01

While vibrating bubble columns have increased the mass transfer between phases, a universal scaling law remains elusive. Attempts to predict mass transfer rates in large industrial scale applications by extrapolating laboratory scale models have failed. In a stationary bubble column, mass transfer is a function of phase interfacial area (PIA), while PIA is determined based on the bubble size distribution (BSD). On the other hand, BSD is influenced by the injection characteristics and liquid phase dynamics and properties. Vibration modifies the BSD by impacting the gas and gas-liquid dynamics. This work uses a vibrating cylindrical bubble column to investigate the effect of gas injection and vibration characteristics on the BSD. The bubble column has a 10 cm diameter and was filled with water to a depth of 90 cm above the tip of the orifice tube injector. BSD was measured using high-speed imaging to determine the projected area of individual bubbles, which the nominal bubble diameter was then calculated assuming spherical bubbles. The BSD dependence on the distance from the injector, injector design (1.6 and 0.8 mm ID), air flow rates (0.5 to 5 lit/min), and vibration conditions (stationary and vibration conditions varying amplitude and frequency) will be presented. In addition to mean data, higher order statistics will also be provided.

[The influence of the menstrual cycle on acute and persistent pain after laparoscopic cholecystectomy].

PubMed

Sari, Sinem; Kozanhan, Betul; Egilmez, Ayse Ilksen; Soyder, Aykut; Aydin, Osman Nuri; Galimberti, Fabrizio; Sessler, Daniel; Turan, Alparslan

Fluctuations of female sex hormones during menstrual cycle influence pain perception. Endogenous pain inhibition is impaired in follicular phase of menstrual cycle. We tested the primary hypothesis that the women having surgery during their follicular phase have more acute pain and require higher opioids than those in the luteal phase, and secondarily we tested that women who have surgery during their follicular phase have more incisional pain at 3 month postoperatively. 127 adult females having laparoscopic cholecystectomy were randomized to have surgery during the luteal or follicular phase of their menstrual cycle. Standardized anesthesia and pain management regimen was given to all patients. Pain and analgesic consumption were evaluated in post-anesthesia care unit and every 4h in the first 24h. Adverse effects were questioned every 4h. Time to oral intake and ambulation were recorded. Post-surgical pain, hospital anxiety, depression scale, SF-12 questionnaire were evaluated at 1 and 3 month visits. There was no difference in acute pain scores and analgesic consumption through the 24h period, Visual Analog Scale at 24h was 1.5±1.5cm for follicular group 1.4±1.7cm for luteal group (p=0.57). Persistent postoperative pain was significantly more common one and at three month, with an incidence was 33% and 32% in the patients at follicular phase versus 16% and 12% at luteal phase, respectively. The Visual Analog Scale at one and at three month was 1.6±0.7cm and 1.8±0.8cm for follicular group and 2.7±1.3cm and 2.9±1.7cm in the luteal group (p=0.02), respectively. There were no significant differences between the groups with respect to anxiety and depression, SF-12 scores at either time. Nausea was more common in follicular-phase group (p=0.01) and oral feeding time was shorter in follicular phase (5.9±0.9h) than in luteal phase (6.8±1.9h, p=0.02). Although persistent postoperative pain was significantly more common one and three months after surgery the magnitude of the pain was low. Our results do not support scheduling operations to target particular phases of the menstrual cycle. Copyright © 2017 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

Propulsion simulator for magnetically-suspended wind tunnel models

NASA Technical Reports Server (NTRS)

Joshi, Prakash B.; Goldey, C. L.; Sacco, G. P.; Lawing, Pierce L.

1991-01-01

The objective of phase two of a current investigation sponsored by NASA Langley Research Center is to demonstrate the measurement of aerodynamic forces/moments, including the effects of exhaust gases, in magnetic suspension and balance system (MSBS) wind tunnels. Two propulsion simulator models are being developed: a small-scale and a large-scale unit, both employing compressed, liquified carbon dioxide as propellant. The small-scale unit was designed, fabricated, and statically-tested at Physical Sciences Inc. (PSI). The large-scale simulator is currently in the preliminary design stage. The small-scale simulator design/development is presented, and the data from its static firing on a thrust stand are discussed. The analysis of this data provides important information for the design of the large-scale unit. A description of the preliminary design of the device is also presented.

An integrated model for the effects of self-reflection and clinical experiential learning on clinical nursing performance in nursing students: A longitudinal study.

PubMed

Pai, Hsiang-Chu

2016-10-01

The use of clinical simulation in undergraduate nursing programs in Taiwan has gradually increased over the past 5years. Previous research has shown that students' experience of anxiety during simulated laboratory sessions influences their self-reflection and learning effectiveness. Thus, further study that tracks what influences students' clinical performance in actual clinical sites is vital. The aim of the study is to develop an integrated model that considers the associations among anxiety, self-reflection, and learning effectiveness and to understand how this model applies to student nurses' clinical performance while on clinical placement. This study used a correlational and longitudinal study design. The 80 nursing students, who ranged in age from 19 to 21 (mean=20.38, SD=0.56), were recruited from a nursing school in southern Taiwan. Data were collected during three phases of implementation using four questionnaires. During the first phase, the State-Trait Anxiety Inventory (STAI), Simulation Learning Effectiveness Scale (SLES), and Self-Reflection and Insight Scale (SRIS) were used after students completed the simulation course in the school simulation laboratory. Nursing students also completed the Holistic Nursing Competence Scale at 2months (Phase 2) and 4months (Phase 3) after clinical practice experience. In Phase 3, students again completed the STAI and SRIS. Partial least squares (PLS), a structural equation modeling (SEM) procedure, was used to test the research model. The findings showed that: (1) at the start of the simulation laboratory, anxiety had a significant negative effect on students' simulation learning effectiveness (SLE; β=-0.14, p<0.05) and on self-reflection with insight (SRI; β=-0.52, p<0.01). Self-reflection also had a significant positive effect on simulation learning effectiveness (β=0.37, p<0.01). Anxiety had a significant negative effect on students' nursing competence during the first 2months of practice in a clinical nursing site (β=-0.20, p<0.01). Simulation learning effectiveness and self-reflection and insight also had a significant positive effect on nursing competence during the first 2months of practice in a clinical site (β=0.13; β=0.16, p<0.05), respectively; and (2) when students practice in a clinical setting, their previous experience of nursing competence during the first 2months of clinical care and their self-reflection and insight have a significant positive effect on their 4-month nursing competence (β=0.58; β=0.27, p<0.01). Anxiety, however, had a negative effect on 4-month nursing competence but not significantly. Overall, 41% of the variance in clinical nursing performance was accounted for by the variables in the integrated model. This study highlights that self-reflection with insight and clinical experience may help students to deflect anxiety that may influence the development of clinical competence. Of note is that real-life clinical experience has a stronger effect on enhancing clinical performance than does a simulation experience. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of spatial bias on the nonequilibrium phase transition in a system of coagulating and fragmenting particles.

PubMed

Rajesh, R; Krishnamurthy, Supriya

2002-10-01

We examine the effect of spatial bias on a nonequilibrium system in which masses on a lattice evolve through the elementary moves of diffusion, coagulation, and fragmentation. When there is no preferred directionality in the motion of the masses, the model is known to exhibit a nonequilibrium phase transition between two different types of steady state, in all dimensions. We show analytically that introducing a preferred direction in the motion of the masses inhibits the occurrence of the phase transition in one dimension, in the thermodynamic limit. A finite-size system, however, continues to show a signature of the original transition, and we characterize the finite-size scaling implications of this. Our analysis is supported by numerical simulations. In two dimensions, bias is shown to be irrelevant.

BIOMASS-FUELED, SMALL-SCALE, INTEGRATED-GASIFIER, GAS-TURBINE POWER PLANT: PROGRESS REPORT ON THE PHASE 2 DEVELOPMENT

EPA Science Inventory

The paper reports the latest efforts to complete development of Phase 2 of a three-phase effort to develop a family of small-scale (1 to 20 MWe) biomass-fueled power plants. The concept envisioned is an air-blown pressurized fluidized-bed gasifier followed by a dry hot gas clean...

Lab-scale investigation on remediation of diesel-contaminated aquifer using microwave energy.

PubMed

Falciglia, Pietro P; Maddalena, Riccardo; Mancuso, Giuseppe; Messina, Valeria; Vagliasindi, Federico G A

2016-02-01

Aquifer contamination with diesel fuel is a worldwide environmental problem, and related available remediation technologies may not be adequately efficient, especially for the simultaneous treatment of both solid and water phases. In this paper, a lab-scale 2.45 GHz microwave (MW) treatment of an artificially diesel-contaminated aquifer was applied to investigate the effects of operating power (160, 350 and 500 W) and time on temperature profiles and contaminant removal from both solid and water phases. Results suggest that in diesel-contaminated aquifer MW remediation, power significantly influences the final reachable temperature and, consequently, contaminant removal kinetics. A maximum temperature of about 120 °C was reached at 500 W. Observed temperature values depended on the simultaneous irradiation of both aquifer grains and groundwater. In this case, solid phase heating is limited by the maximum temperature that interstitial water can reach before evaporation. A minimal residual diesel concentration of about 100 mg kg(-1) or 100 mg L(-1) was achieved by applying a power of 500 W for a time of 60 min for the solid or water phase, respectively. Measured residual TPH fractions showed that MW heating resulted in preferential effects of the removal of different TPH molecular weight fractions and that the evaporation-stripping phenomena plays a major role in final contaminant removal processes. The power low kinetic equation shows an excellent fit (r(2) > 0.993) with the solid phase residual concentration observed for all the powers investigated. A maximum diesel removal of 88 or 80% was observed for the MW treatment of the solid or water phase, respectively, highlighting the possibility to successfully and simultaneously remediate both the aquifer phases. Consequently, MW, compared to other biological or chemical-physical treatments, appears to be a better choice for the fast remediation of diesel-contaminated aquifers. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modeling effects of climate change and phase shifts on detrital production of a kelp bed.

PubMed

Krumhansl, Kira A; Lauzon-Guay, Jean-Sébastien; Scheibling, Robert E

2014-03-01

The exchange of energy and nutrients between ecosystems (i.e., resource subsidies) plays a central role in ecological dynamics over a range of spatial and temporal scales. Little attention has been paid to the role of anthropogenic impacts on natural systems in altering the magnitude, timing, and quality of resource subsidies. Kelp ecosystems are highly productive on a local scale and export over 80% of kelp primary production as detritus, subsidizing consumers across broad spatial scales. Here, we generate a model of detrital production from a kelp bed in Nova Scotia to hindcast trends in detrital production based on temperature and wave height recorded in the study region from 1976 to 2009, and to project changes in detrital production that may result from future climate change. Historical and projected increases in temperature and wave height led to higher rates of detrital production through increased blade breakage and kelp dislodgment from the substratum, but this reduced kelp biomass and led to a decline in detrital production in the long-term. We also used the model to demonstrate that the phase shift from a highly productive kelp bed to a low-productivity barrens, driven by the grazing activity of sea urchins, reduces kelp detrital production by several orders of magnitude, an effect that would be exacerbated by projected increases in temperature and wave action. These results indicate that climate-mediated changes in ecological dynamics operating on local scales may alter the magnitude of resource subsidies to adjacent ecosystems, affecting ecological dynamics on regional scales.

Foaming phenomenon in bench-scale anaerobic digesters.

PubMed

Siebels, Amanda M; Long, Sharon C

2013-04-01

The Madison Metropolitan Sewerage District (The District) in Madison, Wisconsin has been experiencing seasonal foaming in their anaerobic biosolids digesters, which has occurred from mid-November to late June for the past few years. The exact cause(s) of foaming is unknown. Previous research findings are unclear as to whether applications of advanced anaerobic digestion processes reduce the foaming potential of digesters. The object of this study was to investigate how configurations of thermophilic and acid phase-thermophilic anaerobic digestion would affect foaming at the bench-scale level compared to single stage mesophilic digestion for The District. Bench-scale anaerobic digesters were fed with a 4 to 4.5% by dry weight of solids content blend of waste activated sludge (WAS) and primary sludge from The District. Foaming potential was monitored using Alka-Seltzer and aeration foaming tests. The bench-scale acid phase-thermophilic digester had a higher foaming potential than the bench-scale mesophilic digester. These results indicate that higher temperatures increase the foaming potential of the bench-scale anaerobic digesters. The bench-scale acid phase-thermophilic digesters had a greater percent (approximately 5 to 10%) volatile solids destruction and a greater percent (approximately 5 to 10%) total solids destruction when compared to the bench-scale mesophilic digester. Overall, for the full-scale foaming experienced by The District, it appears that adding an acid phase or switching to thermophilic digestion would not alleviate The District's foaming issues.

The Development and Psychometric Properties of the Immigration Law Concerns Scale (ILCS) for HIV Testing.

PubMed

Lechuga, Julia; Galletly, Carol L; Broaddus, Michelle R; Dickson-Gomez, Julia B; Glasman, Laura R; McAuliffe, Timothy L; Vega, Miriam Y; LeGrand, Sarah; Mena, Carla A; Barlow, Morgan L; Valera, Erik; Montenegro, Judith I

2017-11-08

To develop, pilot test, and conduct psychometric analyses of an innovative scale measuring the influence of perceived immigration laws on Latino migrants' HIV-testing behavior. The Immigration Law Concerns Scale (ILCS) was developed in three phases: Phase 1 involved a review of law and literature, generation of scale items, consultation with project advisors, and subsequent revision of the scale. Phase 2 involved systematic translation- back translation and consensus-based editorial processes conducted by members of a bilingual and multi-national study team. In Phase 3, 339 sexually active, HIV-negative Spanish-speaking, non-citizen Latino migrant adults (both documented and undocumented) completed the scale via audio computer-assisted self-interview. The psychometric properties of the scale were tested with exploratory factor analysis and estimates of reliability coefficients were generated. Bivariate correlations were conducted to test the discriminant and predictive validity of identified factors. Exploratory factor analysis revealed a three-factor, 17-item scale. subscale reliability ranged from 0.72 to 0.79. There were significant associations between the ILCS and the HIV-testing behaviors of participants. Results of the pilot test and psychometric analysis of the ILCS are promising. The scale is reliable and significantly associated with the HIV-testing behaviors of participants. Subscales related to unwanted government attention and concerns about meeting moral character requirements should be refined.

Kinetic Alfvén Wave Generation by Large-scale Phase Mixing

NASA Astrophysics Data System (ADS)

Vásconez, C. L.; Pucci, F.; Valentini, F.; Servidio, S.; Matthaeus, W. H.; Malara, F.

2015-12-01

One view of the solar wind turbulence is that the observed highly anisotropic fluctuations at spatial scales near the proton inertial length dp may be considered as kinetic Alfvén waves (KAWs). In the present paper, we show how phase mixing of large-scale parallel-propagating Alfvén waves is an efficient mechanism for the production of KAWs at wavelengths close to dp and at a large propagation angle with respect to the magnetic field. Magnetohydrodynamic (MHD), Hall magnetohydrodynamic (HMHD), and hybrid Vlasov–Maxwell (HVM) simulations modeling the propagation of Alfvén waves in inhomogeneous plasmas are performed. In the linear regime, the role of dispersive effects is singled out by comparing MHD and HMHD results. Fluctuations produced by phase mixing are identified as KAWs through a comparison of polarization of magnetic fluctuations and wave-group velocity with analytical linear predictions. In the nonlinear regime, a comparison of HMHD and HVM simulations allows us to point out the role of kinetic effects in shaping the proton-distribution function. We observe the generation of temperature anisotropy with respect to the local magnetic field and the production of field-aligned beams. The regions where the proton-distribution function highly departs from thermal equilibrium are located inside the shear layers, where the KAWs are excited, this suggesting that the distortions of the proton distribution are driven by a resonant interaction of protons with KAW fluctuations. Our results are relevant in configurations where magnetic-field inhomogeneities are present, as, for example, in the solar corona, where the presence of Alfvén waves has been ascertained.

Clinically Significant Symptom Reduction in Children with Attention-Deficit/Hyperactivity Disorder Treated with Micronutrients: An Open-Label Reversal Design Study

PubMed Central

Gordon, Heather A; Rucklidge, Julia J; Blampied, Neville M; Johnstone, Jeanette M

2015-01-01

Abstract Objective: The purpose of this study was to investigate the clinical effect and safety of a broad spectrum, 36 ingredient micronutrient (vitamins and minerals) in treating children with attention-deficit/hyperactivity disorder (ADHD). Methods: This open-label, on-off-on-off (reversal design) study followed 14 participants (8–12 years of age) with ADHD, diagnosed using standardized instruments, for 6 months with no dropouts. Following baseline assessment, including hematology and biochemistry screening, participants began an 8 week treatment phase with micronutrients titrated up to maximum dose (15 capsules/day). Treatment was withdrawn for 4 weeks, reinstated for a further 8 weeks, and then withdrawn for 4 weeks. Primary outcomes included the Conners' Parent Rating Scale, the Clinical Global Impressions Scale (CGI), and the Strengths and Difficulties Questionnaire – Parent version (SDQ). Secondary outcomes were mood and global functioning. Results: Modified Brinley plots revealed a reduction in ADHD symptoms, improved mood, and improved overall functioning during intervention phases, and deterioration in ADHD symptoms, mood, and overall functioning during the withdrawal phases. Reliable change analyses, Cohen's d and percent superiority effect sizes, 95% confidence intervals and t tests confirmed clinically and statistically significant change between the intervention and withdrawal phases, with large effect sizes observed pre- to post-exposure of micronutrients (d = 1.2–2.2) on ADHD symptoms during intervention phases. Seventy-one percent of participants showed at least a 30% decrease in ADHD symptoms by the end of the second treatment phase, and 79% were identified as “much improved” or “very much improved” at the end of the second phase (5 months) based on the clinician-rated CGI when considering functioning generally. The SDQ showed that these benefits occurred across other areas of functioning including emotional symptoms, conduct problems, and prosocial behaviours. The children's self-reports confirmed the improvements. Excellent adherence to treatment occurred throughout, side effects were mild and transitory, and no safety issues were identified through blood analyses. Conclusions: This study demonstrates the clinical benefit, feasibility, and safety of broad-spectrum micronutrients in the treatment of childhood ADHD. Replications utilizing double-blind placebo-controlled studies are warranted. Trial is registered with the Australia and New Zealand Clinical Trial Registry: ACTRN12612000645853 PMID:26682999

Pregabalin for painful HIV neuropathy

PubMed Central

Simpson, D. M.; Schifitto, G.; Clifford, D. B.; Murphy, T. K.; Durso-De Cruz, E.; Glue, P.; Whalen, E.; Emir, B.; Scott, G. N.; Freeman, R.

2010-01-01

Objective: Pregabalin is effective in several neuropathic pain syndromes. This trial evaluated its efficacy, safety, and tolerability for treatment of painful HIV-associated neuropathy. Methods: This randomized, double-blind, placebo-controlled, parallel-group trial included a 2-week double-blind dose-adjustment (150–600 mg/day BID) phase, a 12-week double-blind maintenance phase, and an optional 3-month open label extension phase. The primary efficacy measure was the mean Numeric Pain Rating Scale (NPRS) score, an 11-point numeric rating scale. Secondary measures included Patient Global Impression of Change (PGIC) and sleep measurements. Results: Baseline mean NPRS score was 6.93 for patients randomized to pregabalin (n = 151) and 6.72 for those to placebo (n = 151). Pregabalin average daily dosage (SD) was 385.7 (160.3) mg/d. At endpoint, pregabalin and placebo showed substantial reductions in mean NPRS score from baseline: −2.88 vs −2.63, p = 0.3941. Pregabalin had greater improvements in NPRS score relative to placebo at weeks 1 (−1.14 vs −0.69, p = 0.0131) and 2 (−1.92 vs −1.43, p = 0.0393), and at weeks 7 (−3.22 vs −2.53 p = 0.0307) and 8 (−3.33 vs −2.53, p = 0.0156). At all other time points, differences between groups were not significant. Sleep measurements and 7-item PGIC did not differ among treatment groups; however, collapsed PGIC scores showed 82.8% of pregabalin and 66.7% of placebo patients rated themselves in 1 of the 3 “improved” categories (p = 0.0077). Somnolence and dizziness were the most common adverse events with pregabalin. Conclusions: Pregabalin was well-tolerated, but not superior to placebo in the treatment of painful HIV neuropathy. Factors predicting analgesic response in HIV neuropathy warrant additional research. Classification of Evidence: This Class II trial showed that pregabalin is not more effective than placebo in treatment of painful HIV neuropathy. GLOSSARY AE = adverse events; ANCOVA = analysis of covariance; ARF = activity region finder; ARV = antiretroviral; GPS = Gracely Pain Scale; HADS = Hospital Anxiety and Depression Scale; HIV-DSP = HIV-associated distal sensory polyneuropathy; LOCF = last observation carried forward; mBPI-sf = modified Brief Pain Inventory–short form; NPRS = Numeric Pain Rating Scale; NPSI = Neuropathic Pain Symptom Inventory; NRS = Numeric Rating Scale; PGIC = Patient Global Impression of Change; VAS = visual analog scale. PMID:20124207

NH4+ ad-/desorption in sequencing batch reactors: simulation, laboratory and full-scale studies.

PubMed

Schwitalla, P; Mennerich, A; Austermann-Haun, U; Müller, A; Dorninger, C; Daims, H; Holm, N C; Rönner-Holm, S G E

2008-01-01

Significant NH4-N balance deficits were found during the measurement campaigns for the data collection for dynamic simulation studies at five full-scale sequencing batch reactor (SBR) waste water treatment plants (WWTPs), as well as during subsequent calibrations at the investigated plants. Subsequent lab scale investigations showed high evidence for dynamic, cycle-specific NH4+ ad-/desorption to the activated flocs as one reason for this balance deficit. This specific dynamic was investigated at five full-scale SBR plants for the search of the general causing mechanisms. The general mechanism found was a NH4+ desorption from the activated flocs at the end of the nitrification phase with subsequent nitrification and a chemical NH4+ adsorption at the flocs in the course of the filling phases. This NH4+ ad-/desorption corresponds to an antiparallel K+ ad/-desorption.One reasonable full-scale application was investigated at three SBR plants, a controlled filling phase at the beginning of the sedimentation phase. The results indicate that this kind of filling event must be specifically hydraulic controlled and optimised in order to prevent too high waste water break through into the clear water phase, which will subsequently be discarded. IWA Publishing 2008.

Beyond Darcy's law: The role of phase topology and ganglion dynamics for two-fluid flow

DOE PAGES

Armstrong, Ryan T.; McClure, James E.; Berrill, Mark A.; ...

2016-10-27

Relative permeability quantifies the ease at which immiscible phases flow through porous rock and is one of the most well known constitutive relationships for petroleum engineers. It however exhibits troubling dependencies on experimental conditions and is not a unique function of phase saturation as commonly accepted in industry practices. The problem lies in the multi-scale nature of the problem where underlying disequilibrium processes create anomalous macroscopic behavior. Here we show that relative permeability rate dependencies are explained by ganglion dynamic flow. We utilize fast X-ray micro-tomography and pore-scale simulations to identify unique flow regimes during the fractional flow of immisciblemore » phases and quantify the contribution of ganglion flux to the overall flux of non-wetting phase. We anticipate our approach to be the starting point for the development of sophisticated multi-scale flow models that directly link pore-scale parameters to macro-scale behavior. Such models will have a major impact on how we recover hydrocarbons from the subsurface, store sequestered CO 2 in geological formations, and remove non-aqueous environmental hazards from the vadose zone.« less

Pore-scale dynamics of enzyme adsorption, swelling and reactive dissolution determine sugar yield in hemicellulose hydrolysis for biofuel production

PubMed Central

Dutta, Sajal Kanti; Chakraborty, Saikat

2016-01-01

Hemicelluloses are the earth’s second most abundant structural polymers, found in lignocellulosic biomass. Efficient enzymatic depolymerization of xylans by cleaving their β-(1 → 4)-glycosidic bonds to produce soluble sugars is instrumental to the cost-effective production of liquid biofuels. Here we show that the multi-scale two-phase process of enzymatic hydrolysis of amorphous hemicelluloses is dominated by its smallest scale–the pores. In the crucial first five hours, two to fourfold swelling of the xylan particles allow the enzymes to enter the pores and undergo rapid non-equilibrium adsorption on the pore surface before they hydrolyze the solid polymers, albeit non-competitively inhibited by the products xylose and xylobiose. Rapid pore-scale reactive dissolution increases the solid carbohydrate’s porosity to 80–90%. This tightly coupled experimental and theoretical study quantifies the complex temporal dynamics of the transport and reaction processes coupled across scales and phases to show that this unique pore-scale phenomenon can be exploited to accelerate the depolymerization of hemicelluloses to monomeric sugars in the first 5–6 h. We find that an ‘optimal substrate loading’ of 5 mg/ml (above which substrate inhibition sets in) accelerates non-equilibrium enzyme adsorption and solid hemicellulose depolymerization at the pore-scale, which contributes three-quarters of the soluble sugars produced for bio-alcohol fermentation. PMID:27905534

Algebraic multigrid preconditioners for two-phase flow in porous media with phase transitions

NASA Astrophysics Data System (ADS)

Bui, Quan M.; Wang, Lu; Osei-Kuffuor, Daniel

2018-04-01

Multiphase flow is a critical process in a wide range of applications, including oil and gas recovery, carbon sequestration, and contaminant remediation. Numerical simulation of multiphase flow requires solving of a large, sparse linear system resulting from the discretization of the partial differential equations modeling the flow. In the case of multiphase multicomponent flow with miscible effect, this is a very challenging task. The problem becomes even more difficult if phase transitions are taken into account. A new approach to handle phase transitions is to formulate the system as a nonlinear complementarity problem (NCP). Unlike in the primary variable switching technique, the set of primary variables in this approach is fixed even when there is phase transition. Not only does this improve the robustness of the nonlinear solver, it opens up the possibility to use multigrid methods to solve the resulting linear system. The disadvantage of the complementarity approach, however, is that when a phase disappears, the linear system has the structure of a saddle point problem and becomes indefinite, and current algebraic multigrid (AMG) algorithms cannot be applied directly. In this study, we explore the effectiveness of a new multilevel strategy, based on the multigrid reduction technique, to deal with problems of this type. We demonstrate the effectiveness of the method through numerical results for the case of two-phase, two-component flow with phase appearance/disappearance. We also show that the strategy is efficient and scales optimally with problem size.

Reindeer habitat use in relation to two small wind farms, during preconstruction, construction, and operation.

PubMed

Skarin, Anna; Alam, Moudud

2017-06-01

Worldwide there is a rush toward wind power development and its associated infrastructure. In Fennoscandia, large-scale wind farms comprising several hundred windmills are currently built in important grazing ranges used for Sámi reindeer husbandry. In this study, reindeer habitat use was assessed using reindeer fecal pellet group counts in relation to two relatively small wind farms, with 8 and 10 turbines, respectively. In 2009, 1,315 15-m 2 plots were established and pellet groups were counted and cleaned from the plots. This was repeated once a year in May, during preconstruction, construction, and operation of the wind farms, covering 6 years (2009-2014) of reindeer habitat use in the area. We modeled the presence/absence of any pellets in a plot at both the local (wind farm site) and regional (reindeer calving to autumn range) scale with a hierarchical logistic regression, where spatial correlation was accounted for via random effects, using vegetation type, and the interaction between distance to wind turbine and time period as predictor variables. Our results revealed an absolute reduction in pellet groups by 66% and 86% around each wind farm, respectively, at local scale and by 61% at regional scale during the operation phase compared to the preconstruction phase. At the regional, scale habitat use declined close to the turbines in the same comparison. However, at the local scale, we observed increased habitat use close to the wind turbines at one of the wind farms during the operation phase. This may be explained by continued use of an important migration route close to the wind farm. The reduced use at the regional scale nevertheless suggests that there may be an overall avoidance of both wind farms during operation, but further studies of reindeer movement and behavior are needed to gain a better understanding of the mechanisms behind this suggested avoidance.

Visualization of Membrane Rafts Using a Perylene Monoimide Derivative and Fluorescence Lifetime Imaging

PubMed Central

Margineanu, Anca; Hotta, Jun-ichi; Van der Auweraer, Mark; Ameloot, Marcel; Stefan, Alina; Beljonne, David; Engelborghs, Yves; Herrmann, Andreas; Müllen, Klaus; De Schryver, Frans C.; Hofkens, Johan

2007-01-01

A new membrane probe, based on the perylene imide chromophore, with excellent photophysical properties (high absorption coefficient, quantum yield (QY) ≈ 1, high photostability) and excited in the visible domain is proposed for the study of membrane rafts. Visualization of separation between the liquid-ordered (Lo) and the liquid-disordered (Ld) phases can be achieved in artificial membranes by fluorescence lifetime imaging due to the different decay times of the membrane probe in the two phases. Rafts on micrometer-scale in cell membranes due to cellular activation can also be observed by this method. The decay time of the dye in the Lo phase is higher than in organic solvents where its QY is 1. This allows proposing a (possible general) mechanism for the decay time increase in the Lo phase, based on the local field effects of the surrounding molecules. For other fluorophores with QY < 1, the suggested mechanism could also contribute, in addition to effects reducing the nonradiative decay pathways, to an increase of the fluorescence decay time in the Lo phase. PMID:17573424

One-step resonant controlled-phase gate on distant transmon qutrits in different 1D superconducting resonators

PubMed Central

Hua, Ming; Tao, Ming-Jie; Deng, Fu-Guo; Lu Long, Gui

2015-01-01

We propose a scheme to construct the controlled-phase (c-phase) gate on distant transmon qutrits hosted in different resonators inter-coupled by a connected transmon qutrit. Different from previous works for entanglement generation and information transfer on two distant qubits in a dispersive regime in the similar systems, our gate is constructed in the resonant regime with one step. The numerical simulation shows that the fidelity of our c-phase gate is 99.5% within 86.3 ns. As an interesting application of our c-phase gate, we propose an effective scheme to complete a conventional square lattice of two-dimensional surface code layout for fault-tolerant quantum computing on the distant transmon qutrits. The four-step coupling between the nearest distant transmon qutrits, small coupling strengths of the distant transmon qutrits, and the non-population on the connection transmon qutrit can reduce the interactions among different parts of the layout effectively, which makes the layout be integrated with a large scale in an easier way. PMID:26486426

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

Kubo, Jisuke; Yamada, Masatoshi; Institut für Theoretische Physik, Universität Heidelberg,Philosophenweg 16, 69120 Heidelberg

We assume that the origin of the electroweak (EW) scale is a gauge-invariant scalar-bilinear condensation in a strongly interacting non-abelian gauge sector, which is connected to the standard model via a Higgs portal coupling. The dynamical scale genesis appears as a phase transition at finite temperature, and it can produce a gravitational wave (GW) background in the early Universe. We find that the critical temperature of the scale phase transition lies above that of the EW phase transition and below few O(100) GeV and it is strongly first-order. We calculate the spectrum of the GW background and find the scalemore » phase transition is strong enough that the GW background can be observed by DECIGO.« less

Laser induced hierarchical calcium phosphate structures.

PubMed

Kurella, Anil; Dahotre, Narendra B

2006-11-01

The surface properties of biomedical implant materials control the dynamic interactions at tissue-implant interfaces. At such interfaces, if the nanoscale features influence protein interactions, those of the microscale and mesoscale aid cell orientation and provide tissue integration, respectively. It seems imperative that the synthetic materials expected to replace natural hard tissues are engineered to mimic the complexity of their hierarchical assembly. However, the current surface engineering approaches are single scaled. It is demonstrated that using laser surface engineering a controlled multiscale surface can be synthesized for bioactive functions. A systematic organization of bioactive calcium phosphate coating with multiphase composition on Ti-alloy substrate ranging from nano- to mesoscale has been achieved by effectively controlling the thermo physical interactions during laser processing. The morphology of the coating consisted of a periodic arrangement of Ti-rich and Ca-P-deficient star-like phases uniformly distributed inside a Ca-P-rich self-assembled cellular structure with the presence of CaO, alpha-tricalcium phosphate, CaTiO(3), TiO(2) and Ti phase in the coating matrix. The cellular structures ranged in diameter from 2.5 microm to 10 microm as an assembly of cuboid shaped particles of dimensions of approximately 200 nm x 1 microm. The multiscale texture also included nanoscale particles that are the precursors for many of these phases. The rapid cooling associated with the laser processing resulted in formation, organization and controlling dimensions of the Ca-P-rich glassy phase into a micron scale cellular morphology and submicron scale clusters of CaTiO(3) phase inside the cellular structures. The self-assembly of the coating into multiscale structure was influenced by chemical and physical interactions among the multiphases that evolved during laser processing.

MEETING IN CHARLOTTE: SOLID-PHASE EXTRACTION OF 35 DBPS WITH ANALYSIS BY GC/ECD AND GC/MS

EPA Science Inventory

An analytical method for 35 disinfection by-products (DBPs) was developed for a U.S. Environmental Protection Agency health effects study. A toxicological evaluation was conducted on drinking water that was scaled-up (using reverse osmosis) by concentrating the total organic car...

SOLID-PHASE EXTRACTION OF 35 DBPS WITH ANALYSIS BY GC/ECD AND GC/MS

EPA Science Inventory

An analytical method for 35 disinfection by-products (DBPs) was developed for a U.S. Environmental Protection Agency (EPA) health effects study. A toxicological evaluation was conducted on drinking water that was "scaled-up" using reverse osmosis (RO) by concentrating the total ...

SOLID-PHASE EXTRACTION OF 35 DBPS WITH ANALYSIS BY GC/ECD AND GC/MS

EPA Science Inventory

An analytical method for 35 disinfection by-products (DBPs) was developed for a U.S. Environmental Protection Agency (EPA) health effects study. A toxicological evaluation was conducted on drinking water that was ‘scaled-up’ using reverse osmosis (RO) by concentrating the total o...

SOLID-PHASE EXTRACTION OF 35 DBPS WITH ANALYSIS BY GC/ECD AND GC/MS 2007

EPA Science Inventory

An analytical method for 35 disinfection by-products (DBPs) was developed for a U.S. Environmental Protection Agency (EPA) health effects study. A toxicological evaluation was conducted on drinking water that was ‘scaled-up’ using reverse osmosis (RO) by concentrating the total o...

Factors Affecting Intervention Fidelity of Differentiated Instruction in Kindergarten

ERIC Educational Resources Information Center

Dijkstra, Elma M.; Walraven, Amber; Mooij, Ton; Kirschner, Paul A.

2017-01-01

This paper reports on the findings in the first phase of a design-based research project as part of a large-scale intervention study in Dutch kindergartens. The project aims at enhancing differentiated instruction and evaluating its effects on children's development, in particular high-ability children. This study investigates relevant…

FIELD TEST OF CYCLODEXTRIN FOR ENHANCED IN-SITU FLUSHING OF MULTIPLE-COMPONENT IMMISCIBLE ORGANIC LIQUID CONTAMINATION: COMPARISON TO WATER FLUSHING

EPA Science Inventory

A pilot-scale field experiment was conducted to compare the remediation effectiveness of an enhanced-solubilization technique to that of water flushing for removal of multicomponent nonaqueous-phase organic liquid (NAPL) contaminants form a phreatic aquifer. This innovative remed...

Emissions from an automobile fire.

PubMed

Lönnermark, Anders; Blomqvist, Per

2006-02-01

The emissions from automobile fires have been investigated. The main gas phase components were analysed in small-scale tests with representative material from an automobile. A more detailed investigation of full-scale simulated automobile fires was also conducted, including the characterisation of gas phase components, particulates and run-off water from extinguishing activities. Three separate full scale fire tests have been characterised: a fire ignited and developed in the engine compartment; a fire ignited inside the coupé, that was extinguished in the early stages; and a similar fire ignited inside the coupé that was allowed to spread until the entire vehicle was involved in the fire. The quantitative analysis of the smoke gases from the full-scale fires showed that emissions with a potentially negative impact on the environment, or chronic toxic effect on humans, were produced in significant quantities. These emissions included HCl, SO2, VOCs (e.g. benzene), PAHs, and PCDDs/PCDFs. Analysis of run-off water indicated that it was severely contaminated, containing elevated levels of both organic compounds and metals. Comparison with data from other vehicle fires found in the literature shows that contamination by lead, copper, zinc, and antimony appears to be significant in water run-off from these types of fires.

Computational microscopy: illumination coding and nonlinear optimization enables gigapixel 3D phase imaging

NASA Astrophysics Data System (ADS)

Tian, Lei; Waller, Laura

2017-05-01

Microscope lenses can have either large field of view (FOV) or high resolution, not both. Computational microscopy based on illumination coding circumvents this limit by fusing images from different illumination angles using nonlinear optimization algorithms. The result is a Gigapixel-scale image having both wide FOV and high resolution. We demonstrate an experimentally robust reconstruction algorithm based on a 2nd order quasi-Newton's method, combined with a novel phase initialization scheme. To further extend the Gigapixel imaging capability to 3D, we develop a reconstruction method to process the 4D light field measurements from sequential illumination scanning. The algorithm is based on a 'multislice' forward model that incorporates both 3D phase and diffraction effects, as well as multiple forward scatterings. To solve the inverse problem, an iterative update procedure that combines both phase retrieval and 'error back-propagation' is developed. To avoid local minimum solutions, we further develop a novel physical model-based initialization technique that accounts for both the geometric-optic and 1st order phase effects. The result is robust reconstructions of Gigapixel 3D phase images having both wide FOV and super resolution in all three dimensions. Experimental results from an LED array microscope were demonstrated.

Assessing the Challenges in the Application of Potential Probiotic Lactic Acid Bacteria in the Large-Scale Fermentation of Spanish-Style Table Olives.

PubMed

Rodríguez-Gómez, Francisco; Romero-Gil, Verónica; Arroyo-López, Francisco N; Roldán-Reyes, Juan C; Torres-Gallardo, Rosa; Bautista-Gallego, Joaquín; García-García, Pedro; Garrido-Fernández, Antonio

2017-01-01

This work studies the inoculation conditions for allowing the survival/predominance of a potential probiotic strain ( Lactobacillus pentosus TOMC-LAB2) when used as a starter culture in large-scale fermentations of green Spanish-style olives. The study was performed in two successive seasons (2011/2012 and 2012/2013), using about 150 tons of olives. Inoculation immediately after brining (to prevent wild initial microbiota growth) followed by re-inoculation 24 h later (to improve competitiveness) was essential for inoculum predominance. Processing early in the season (September) showed a favorable effect on fermentation and strain predominance on olives (particularly when using acidified brines containing 25 L HCl/vessel) but caused the disappearance of the target strain from both brines and olives during the storage phase. On the contrary, processing in October slightly reduced the target strain predominance on olives (70-90%) but allowed longer survival. The type of inoculum used (laboratory vs. industry pre-adapted) never had significant effects. Thus, this investigation discloses key issues for the survival and predominance of starter cultures in large-scale industrial fermentations of green Spanish-style olives. Results can be of interest for producing probiotic table olives and open new research challenges on the causes of inoculum vanishing during the storage phase.

Effects of Shock-Breakout Pressure on Ejection of Micron-Scale Material from Shocked Tin Surfaces

NASA Astrophysics Data System (ADS)

Zellner, Michael; Hammerberg, James; Hixson, Robert; Morley, Kevin; Obst, Andrew; Olson, Russell; Payton, Jeremy; Rigg, Paulo; Buttler, William; Grover, Michael; Iverson, Adam; Macrum, Gregory; Stevens, Gerald; Turley, William; Veeser, Lynn; Routley, Nathan

2007-06-01

Los Alamos National Lab (LANL) is actively engaged in the development of a model to predict the formation of micron-scale fragments ejected (ejecta) from shocked metal surfaces. The LANL ejecta model considers that the amount of ejecta is mainly related to the material's phase on shock release at the free-surface. This effort investigates the relation between ejecta production and shock-breakout pressure for Sn shocked with high explosives to pressures near the solid-on-release/partial-liquid-on-release phase transition region. We found that the amount of ejecta produced for shock-breakout pressures that resulted in partial-liquid-on-release increased significantly compared to that which resulted in solid-on-release. Additionally, we found that the amount of ejecta remained relatively constant within the partial-liquid-on-release, regardless of shock-breakout pressure.

Silicon material task - Low cost solar array project /JPL/DOE/

NASA Technical Reports Server (NTRS)

Lutwack, R.

1979-01-01

The paper describes the silicon material task of the low-cost solar array project, which has the objective of establishing a silicon production capability equivalent to 500 mW per year at a price less than 10 dollars/kg (1975 dollars) in 1986. The task program is divided into four phases: technical feasibility, scale-up studies (the present phase), experimental process system development units, and implementation of large-scale production plants, and it involves the development of processes for two groups of materials, that is, semiconductor grade and solar cell grade. In addition, the effects of impurities on solar cell performance are being investigated. Attention is given to problem areas of the task program, such as environmental protection, material compatibility between the reacting chemicals and materials of construction of the equipment, and waste disposal.

Results of phase change paint heat transfer tests utilizing 0.040 scale 50% forebody models (No. 82-0) of the Rockwell International space shuttle orbiter in AEDC VKF hypersonic tunnel B (test OH54A)

NASA Technical Reports Server (NTRS)

Dye, W. H.

1976-01-01

Results of aerodynamic heating tests conducted in October 1974 on a space shuttle orbiter model using the phase change paint technique are presented. The model was a 0.040 scale representation of the forward 50 percent of the orbiter. Surface roughness effects on boundary layer transition were investigated. Roughness was simulated by using steel balls varying in diameter from 0 (no balls) to 0.039 inch with 0.040 inch wide by 0.080 inch deep gaps. A nominal Mach number of 8 was tested with Reynolds number varying from 0.75 through 3.5 million per foot. Angle of attack was varied from 20 deg to 40 deg.

Non-linear coherent mode interactions and the control of shear layers

NASA Technical Reports Server (NTRS)

Nikitopoulos, D. E.; Liu, J. T. C.

1990-01-01

A nonlinear integral formulation, based on local linear stability considerations, is used to study the collective interactions between discrete wave-modes associated with large-scale structures and the mean flow in a developing shear layer. Aspects of shear layer control are examined in light of the sensitivity of these interactions to the initial frequency parameter, modal energy contents and modal phases. Manipulation of the large-scale structure is argued to be an effective means of controlling the flow, including the small-scale turbulence dominated region far downstream. Cases of fundamental, 1st and 2nd subharmonic forcing are discussed in conjunction with relevant experiments.

Metrologically useful states of spin-1 Bose condensates with macroscopic magnetization

NASA Astrophysics Data System (ADS)

Kajtoch, Dariusz; Pawłowski, Krzysztof; Witkowska, Emilia

2018-02-01

We study theoretically the usefulness of spin-1 Bose condensates with macroscopic magnetization in a homogeneous magnetic field for quantum metrology. We demonstrate Heisenberg scaling of the quantum Fisher information for states in thermal equilibrium. The scaling applies to both antiferromagnetic and ferromagnetic interactions. The effect preserves as long as fluctuations of magnetization are sufficiently small. Scaling of the quantum Fisher information with the total particle number is derived within the mean-field approach in the zero-temperature limit and exactly in the high-magnetic-field limit for any temperature. The precision gain is intuitively explained owing to subtle features of the quasidistribution function in the phase space.

Kibble-Zurek Scaling and String-Net Coarsening in Topologically Ordered Systems

NASA Astrophysics Data System (ADS)

Khemani, Vedika; Chandran, Anushya; Burnell, F. J.; Sondhi, S. L.

2013-03-01

We consider the non-equilibrium dynamics of topologically ordered systems, such as spin liquids, driven across a continuous phase transition into proximate phases with no, or reduced, topological order. This dynamics exhibits scaling in the spirit of Kibble and Zurek but now without the presence of symmetry breaking and a local order parameter. The non-equilibrium dynamics near the critical point is universal in a particular scaling limit. The late stages of the process are seen to exhibit slow, quantum coarsening dynamics for the extended string-nets characterizing the topological phase, a potentially interesting signature of topological order. Certain gapped degrees of freedom that could potentially destroy coarsening are, at worst, dangerously irrelevant in the scaling limit. We also note a time dependent amplification of the energy splitting between topologically degenerate states on closed manifolds. We illustrate these phenomena in the context of particular phase transitions out of the abelian Z2 topologically ordered phase of the toric code, and the non-abelian SU(2)k ordered phases of the relevant Levin-Wen models. This research was supported in part by the National Science Foundation under Grant No. NSF PHY11-25915 and DMR 10-06608.

The influence of scale preferences on the design of a water innovation: a case in Dutch river management.

PubMed

Vreugdenhil, Heleen; Vreudenhil, Heleen; Slinger, Jill; Kater, Emiel; Thissen, Wil

2010-07-01

The debate on scale use in river management focuses primarily on the (lack of) fit between the bio-geophysical and institutional systems. However, in this article we focus on the 'subjective' aspect of scale preferences in water governance. We apply an adapted version of the Integrated Scale Hierarchy for Rivers to determine the degree of fit between the scale preferences of the actors involved in a Dutch case study and the scale requirements of the innovative river management concept. This allows us to understand which riverine processes and characteristics are regarded as important by the different actors and to identify mismatches in scale perspectives as they manifest themselves in water management practice. We discover that inflexibility in scale use on the part of the involved actors places bounds on the design and quality of interventions and demonstrate that a more flexible use of scales in the design phase of a river management intervention has the potential to lead to more effective solutions.

Implementation of the Agitated Behavior Scale in the Electronic Health Record.

PubMed

Wilson, Helen John; Dasgupta, Kritis; Michael, Kathleen

The purpose of the study was to implement an Agitated Behavior Scale through an electronic health record and to evaluate the usability of the scale in a brain injury unit at a rehabilitation hospital. A quality improvement project was conducted in the brain injury unit at a large rehabilitation hospital with registered nurses as participants using convenience sampling. The project consisted of three phases and included education, implementation of the scale in the electronic health record, and administration of the survey questionnaire, which utilized the system usability scale. The Agitated Behavior Scale was found to be usable, and there was 92.2% compliance with the use of the electronic Electronic Agitated Behavior Scale. The Agitated Behavior Scale was effectively implemented in the electronic health record and was found to be usable in the assessment of agitation. Utilization of the scale through the electronic health record on a daily basis will allow for an early identification of agitation in patients with traumatic brain injury and enable prompt interventions to manage agitation.

The Influence of Scale Preferences on the Design of a Water Innovation: A Case in Dutch River Management

PubMed Central

Slinger, Jill; Kater, Emiel; Thissen, Wil

2010-01-01

The debate on scale use in river management focuses primarily on the (lack of) fit between the bio-geophysical and institutional systems. However, in this article we focus on the ‘subjective’ aspect of scale preferences in water governance. We apply an adapted version of the Integrated Scale Hierarchy for Rivers to determine the degree of fit between the scale preferences of the actors involved in a Dutch case study and the scale requirements of the innovative river management concept. This allows us to understand which riverine processes and characteristics are regarded as important by the different actors and to identify mismatches in scale perspectives as they manifest themselves in water management practice. We discover that inflexibility in scale use on the part of the involved actors places bounds on the design and quality of interventions and demonstrate that a more flexible use of scales in the design phase of a river management intervention has the potential to lead to more effective solutions. PMID:20640852

The effectiveness and safety of amisulpride in Chinese patients with schizophrenia: An 8‐week, prospective, open‐label, multicenter, single‐arm study

PubMed Central

Liang, Ying; Cao, Changan; Zhu, Cheng; Wang, Chuanyue; Zhang, Congpei; Dong, Fang; Yang, Fude; Deng, Hong; Yu, Jingjie; Tang, Jisheng; Su, Lei; Xin, Limin; Hong, Ling; Gao, Minglong; Tang, Muni; Xie, Shiping; Lu, Shuiping; Liu, Tiebang; Xu, Xiaojin; Wang, Xijin; Li, Xuanzi; Wang, Xueyi; Li, Yi; Zhang, Yong; Chen, Zhiyu

2016-01-01

Abstract Introduction This study evaluated the effectiveness and safety of amisulpride in Chinese schizophrenia patients. Methods A multicenter, single‐arm Phase IV study (NCT01795183). Chinese patients with schizophrenia received amisulpride for 8 weeks. The primary endpoint was ≥50% decrease in Positive and Negative Syndrome Scale total score from Baseline to Week 8. Results A total of 316 patients were enrolled; 295 were included in the effectiveness analysis; 66.8% (197/295) achieved ≥50% decrease in Positive and Negative Syndrome Scale total score from Baseline to Week 8. Nine patients discontinued treatment because of adverse events. Discussion Amisulpride had clinical effectiveness and was relatively well tolerated in Chinese patients with schizophrenia. PMID:27020720

Algebraic multigrid preconditioners for two-phase flow in porous media with phase transitions [Algebraic multigrid preconditioners for multiphase flow in porous media with phase transitions

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

Bui, Quan M.; Wang, Lu; Osei-Kuffuor, Daniel

Multiphase flow is a critical process in a wide range of applications, including oil and gas recovery, carbon sequestration, and contaminant remediation. Numerical simulation of multiphase flow requires solving of a large, sparse linear system resulting from the discretization of the partial differential equations modeling the flow. In the case of multiphase multicomponent flow with miscible effect, this is a very challenging task. The problem becomes even more difficult if phase transitions are taken into account. A new approach to handle phase transitions is to formulate the system as a nonlinear complementarity problem (NCP). Unlike in the primary variable switchingmore » technique, the set of primary variables in this approach is fixed even when there is phase transition. Not only does this improve the robustness of the nonlinear solver, it opens up the possibility to use multigrid methods to solve the resulting linear system. The disadvantage of the complementarity approach, however, is that when a phase disappears, the linear system has the structure of a saddle point problem and becomes indefinite, and current algebraic multigrid (AMG) algorithms cannot be applied directly. In this study, we explore the effectiveness of a new multilevel strategy, based on the multigrid reduction technique, to deal with problems of this type. We demonstrate the effectiveness of the method through numerical results for the case of two-phase, two-component flow with phase appearance/disappearance. In conclusion, we also show that the strategy is efficient and scales optimally with problem size.« less

Algebraic multigrid preconditioners for two-phase flow in porous media with phase transitions [Algebraic multigrid preconditioners for multiphase flow in porous media with phase transitions

DOE PAGES

Bui, Quan M.; Wang, Lu; Osei-Kuffuor, Daniel

2018-02-06

Multiphase flow is a critical process in a wide range of applications, including oil and gas recovery, carbon sequestration, and contaminant remediation. Numerical simulation of multiphase flow requires solving of a large, sparse linear system resulting from the discretization of the partial differential equations modeling the flow. In the case of multiphase multicomponent flow with miscible effect, this is a very challenging task. The problem becomes even more difficult if phase transitions are taken into account. A new approach to handle phase transitions is to formulate the system as a nonlinear complementarity problem (NCP). Unlike in the primary variable switchingmore » technique, the set of primary variables in this approach is fixed even when there is phase transition. Not only does this improve the robustness of the nonlinear solver, it opens up the possibility to use multigrid methods to solve the resulting linear system. The disadvantage of the complementarity approach, however, is that when a phase disappears, the linear system has the structure of a saddle point problem and becomes indefinite, and current algebraic multigrid (AMG) algorithms cannot be applied directly. In this study, we explore the effectiveness of a new multilevel strategy, based on the multigrid reduction technique, to deal with problems of this type. We demonstrate the effectiveness of the method through numerical results for the case of two-phase, two-component flow with phase appearance/disappearance. In conclusion, we also show that the strategy is efficient and scales optimally with problem size.« less

Sound production due to large-scale coherent structures. [and identification of noise mechanisms in turbulent shear flow

NASA Technical Reports Server (NTRS)

Gatski, T. B.

1979-01-01

The sound due to the large-scale (wavelike) structure in an infinite free turbulent shear flow is examined. Specifically, a computational study of a plane shear layer is presented, which accounts, by way of triple decomposition of the flow field variables, for three distinct component scales of motion (mean, wave, turbulent), and from which the sound - due to the large-scale wavelike structure - in the acoustic field can be isolated by a simple phase average. The computational approach has allowed for the identification of a specific noise production mechanism, viz the wave-induced stress, and has indicated the effect of coherent structure amplitude and growth and decay characteristics on noise levels produced in the acoustic far field.

Particle-in-cell modeling for MJ scale dense plasma focus with varied anode shape

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

Link, A., E-mail: link6@llnl.gov; Halvorson, C., E-mail: link6@llnl.gov; Schmidt, A.

2014-12-15

Megajoule scale dense plasma focus (DPF) Z-pinches with deuterium gas fill are compact devices capable of producing 10{sup 12} neutrons per shot but past predictive models of large-scale DPF have not included kinetic effects such as ion beam formation or anomalous resistivity. We report on progress of developing a predictive DPF model by extending our 2D axisymmetric collisional kinetic particle-in-cell (PIC) simulations from the 4 kJ, 200 kA LLNL DPF to 1 MJ, 2 MA Gemini DPF using the PIC code LSP. These new simulations incorporate electrodes, an external pulsed-power driver circuit, and model the plasma from insulator lift-off throughmore » the pinch phase. To accommodate the vast range of relevant spatial and temporal scales involved in the Gemini DPF within the available computational resources, the simulations were performed using a new hybrid fluid-to-kinetic model. This new approach allows single simulations to begin in an electron/ion fluid mode from insulator lift-off through the 5-6 μs run-down of the 50+ cm anode, then transition to a fully kinetic PIC description during the run-in phase, when the current sheath is 2-3 mm from the central axis of the anode. Simulations are advanced through the final pinch phase using an adaptive variable time-step to capture the fs and sub-mm scales of the kinetic instabilities involved in the ion beam formation and neutron production. Validation assessments are being performed using a variety of different anode shapes, comparing against experimental measurements of neutron yield, neutron anisotropy and ion beam production.« less

Development of a new assessment scale for measuring interaction during staff-assisted transfer of residents in dementia special care units.

PubMed

Thunborg, Charlotta; von Heideken Wågert, Petra; Götell, Eva; Ivarsson, Ann-Britt; Söderlund, Anne

2015-02-10

Mobility problems and cognitive deficits related to transferring or moving persons suffering from dementia are associated with dependency. Physical assistance provided by staff is an important component of residents' maintenance of mobility in dementia care facilities. Unfortunately, hands-on assistance during transfers is also a source of confusion in persons with dementia, as well as a source of strain in the caregiver. The bidirectional effect of actions in a dementia care dyad involved in transfer is complicated to evaluate. This study aimed to develop an assessment scale for measuring actions related to transferring persons with dementia by dementia care dyads. This study was performed in four phases and guided by the framework of the biopsychosocial model and the approach presented by Social Cognitive Theory. These frameworks provided a starting point for understanding reciprocal effects in dyadic interaction. The four phases were 1) a literature review identifying existing assessment scales; 2) analyses of video-recorded transfer of persons with dementia for further generation of items, 3) computing the item content validity index of the 93 proposed items by 15 experts; and 4) expert opinion on the response scale and feasibility testing of the new assessment scale by video observation of the transfer situations. The development process resulted in a 17-item scale with a seven-point response scale. The scale consists of two sections. One section is related to transfer-related actions (e.g., capability of communication, motor skills performance, and cognitive functioning) of the person with dementia. The other section addresses the caregivers' facilitative actions (e.g., preparedness of transfer aids, interactional skills, and means of communication and interaction). The literature review and video recordings provided ideas for the item pool. Expert opinion decreased the number of items by relevance ratings and qualitative feedback. No further development of items was performed after feasibility testing of the scale. To enable assessment of transfer-related actions in dementia care dyads, our new scale shows potential for bridging the gap in this area. Results from this study could provide health care professionals working in dementia care facilities with a useful tool for assessing transfer-related actions.

The Combination Process for Preparative Separation and Purification of Paclitaxel and 10-Deacetylbaccatin III Using Diaion® Hp-20 Followed by Hydrophilic Interaction Based Solid Phase Extraction.

PubMed

Shirshekanb, Mahsa; Rezadoost, Hassan; Javanbakht, Mehran; Ghassempour, Ali Reza

2017-01-01

There is no other naturally occurring defense agent against cancer that has a stronger effect than paclitaxel, commonly known under the brand name of Taxol ® . The major drawback for the more widespread use of paclitaxel and its precious precursor, 10-deacetylbaccatin III (10-DAB III), is that they require large-scale extraction from different parts of yew trees ( Taxus species), cell cultures, taxane-producing endophytic fungi, and Corylus species. In our previous work, a novel online two-dimensional heart-cut liquid chromatography process using hydrophilic interaction/ reversed-phase chromatography was used to introduce a semi-preparative treatment for the separation of polar (10-deacetylbaccatin III) and non-polar (paclitaxel) taxanes from Taxus baccata L. In this work, a combination of the absorbent (Diaion ®  HP-20) and a silica based solid phase extraction is utilized as a new, efficient, and cost effective method for large-scale production of taxanes. This process avoids the technical problem of two-dimensional preparative liquid chromatography. The first stage of the process involves discarding co-extractive polar compounds including chlorophylls and pigments using a non-polar synthetic hydrophobic absorbent, Diaion ®  HP-20. Extract was then loaded on to a silica based hydrophilic interaction solid phase extraction (silica 40-60 micron). Taxanes was eluted using a mixture of water and methanol at the optimized ratio of 70:30. Finally, the fraction containing taxanes was applied to semi-preparative reversed phase HPLC. The results revealed that using this procedure, paclitaxel and 10-DAB III could be obtained at 8 and 3 times more, respectively than by the traditional method of extraction.

Phase Transitions in Geomorphology

NASA Astrophysics Data System (ADS)

Ortiz, C. P.; Jerolmack, D. J.

2015-12-01

Landscapes are patterns in a dynamic steady-state, due to competing processes that smooth or sharpen features over large distances and times. Geomorphic transport laws have been developed to model the mass-flux due to different processes, but are unreasonably effective at recovering the scaling relations of landscape features. Using a continuum approximation to compare experimental landscapes and the observed landscapes of the earth, one finds they share similar morphodynamics despite a breakdown of classical dynamical similarity between the two. We propose the origin of this effectiveness is a different kind of dynamic similarity in the statistics of initiation and cessation of motion of groups of grains, which is common to disordered systems of grains under external driving. We will show how the existing data of sediment transport points to common signatures with dynamical phase transitions between "mobile" and "immobile" phases in other disordered systems, particularly granular materials, colloids, and foams. Viewing landscape evolution from the lens of non-equilibrium statistical physics of disordered systems leads to predictions that the transition of bulk measurements such as particle flux is continuous from one phase to another, that the collective nature of the particle dynamics leads to very slow aging of bulk properties, and that the dynamics are history-dependent. Recent results from sediment transport experiments support these predictions, suggesting that existing geomorphic transport laws may need to be replaced by a new generation of stochastic models with ingredients based on the physics of disordered phase transitions. We discuss possible strategies for extracting the necessary information to develop these models from measurements of geomorphic transport noise by connecting particle-scale collective dynamics and space-time fluctuations over landscape features.

Responses of Cloud Type Distributions to the Large-Scale Dynamical Circulation: Water Budget-Related Dynamical Phase Space and Dynamical Regimes

NASA Technical Reports Server (NTRS)

Wong, Sun; Del Genio, Anthony; Wang, Tao; Kahn, Brian; Fetzer, Eric J.; L'Ecuyer, Tristan S.

2015-01-01

Goals: Water budget-related dynamical phase space; Connect large-scale dynamical conditions to atmospheric water budget (including precipitation); Connect atmospheric water budget to cloud type distributions.

Memantine as an Adjuvant Treatment for Obsessive Compulsive Symptoms in Manic Phase of Bipolar Disorder: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial.

PubMed

Sahraian, Ali; Jahromi, Leila Razeghian; Ghanizadeh, Ahmad; Mowla, Arash

2017-04-01

The aim of this study is to examine the effects of memantine as an adjuvant treatment for obsessive compulsive (OC) symptoms in patients with bipolar disorder (BD) type I, manic phase. In this 16-week double-blind placebo-controlled randomized clinical trial, 58 patients in the manic phase of BD who had OC symptoms were randomly allocated to receive memantine or placebo plus their routine medications (lithium + olanzapine + clonazepam). The Yale Brown Obsessive Compulsive Behavior Scale was used to assess the outcomes. Adverse effects were also recorded. Thirty-eight patients (19 in the memantine group and 19 in the placebo group) completed the trial. Throughout the trial, the mean score decreased from 20.26 ± 5.91 to 9.73 ± 5.44 in the memantine group (P < 0.000) and from 22.89 ± 5.70 to 16.63 ± 4.00 in the placebo group (P < 0.000). At the end of the study, 15 (78.94%) patients in the memantine group and 7 (36.84%) patients in the placebo group demonstrated more than 34% decline in the Yale Brown Obsessive Compulsive Behavior Scale score (P < 0.01). No serious adverse effects were reported. Our double-blind controlled clinical trial showed that memantine is an effective adjuvant agent for reducing OC symptoms in patients with BD. However, it needs to be noted that our study is preliminary, and larger double-blind controlled studies are needed to confirm the results.

Thermodynamics of Titanium-Aluminum-Oxygen Alloys Studied

NASA Technical Reports Server (NTRS)

Copland, Evan H.; Jacobson, Nathan S.

2001-01-01

Titanium-aluminum alloys are promising intermediate-temperature alloys for possible compressor applications in gas-turbine engines. These materials are based on the a2-Ti3Al + g-TiAl phases. The major issue with these materials is high oxygen solubility in a2-Ti3Al, and oxidation of unsaturated alloys generally leads to mixed non-protective TiO2+Al2O3 scales. From phase diagram studies, oxygen saturated a2-Ti3Al(O) is in equilibrium with Al2O3; however, oxygen dissolution has a detrimental effect on mechanical properties and cannot be accepted. To better understand the effect of oxygen dissolution, we examined the thermodynamics of titanium-aluminum-oxygen alloys.

Self-pulsing in a 2 km single-mode fiber with the seed source broadened via WNS phase modulation

NASA Astrophysics Data System (ADS)

Zha, Congwen; Sun, Yinhong; Wang, Yanshan; Li, Tenglong; Peng, Wanjing; Ma, Yi; Zhang, Kai

2018-03-01

The seed source with spectral linewidth broadening via phase modulation is potential to achieve the higher output power with effective SBS suppression. However, self-pulsing from the amplifier output is harmful. In this work, we study the self-pulsing characteristics in a long single-mode fiber with lower self-pulsing threshold instead of the high power amplifier. We provide a powerful experimental support for the self-pulsing mechanism in high-power narrow-linewidth fiber lasers, which is important for further output power scaling.

Heat transfer phase change paint tests of 0.0175-scale models (nos. 21-0 and 46-0) of the Rockwell International space shuttle orbiter in the AEDC tunnel B hypersonic wind tunnel (test OH25A)

NASA Technical Reports Server (NTRS)

Dye, W. H.

1975-01-01

Tests were conducted in a hypersonic wind tunnel using various truncated space shuttle orbiter configurations in an attempt to establish the optimum model size for other tests examining body shock-wing leading edge interference effects. The tests were conducted at Mach number 8 using the phase change paint technique. A test description, tabulated data, and tracings of isotherms made from photographs taken during the test are presented.

Prediction of gas-liquid two-phase flow regime in microgravity

NASA Technical Reports Server (NTRS)

Lee, Jinho; Platt, Jonathan A.

1993-01-01

An attempt is made to predict gas-liquid two-phase flow regime in a pipe in a microgravity environment through scaling analysis based on dominant physical mechanisms. Simple inlet geometry is adopted in the analysis to see the effect of inlet configuration on flow regime transitions. Comparison of the prediction with the existing experimental data shows good agreement, though more work is required to better define some physical parameters. The analysis clarifies much of the physics involved in this problem and can be applied to other configurations.

A Volume-Fraction Based Two-Phase Constitutive Model for Blood

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

Zhao, Rui; Massoudi, Mehrdad; Hund, S.J.

2008-06-01

Mechanically-induced blood trauma such as hemolysis and thrombosis often occurs at microscopic channels, steps and crevices within cardiovascular devices. A predictive mathematical model based on a broad understanding of hemodynamics at micro scale is needed to mitigate these effects, and is the motivation of this research project. Platelet transport and surface deposition is important in thrombosis. Microfluidic experiments have previously revealed a significant impact of red blood cell (RBC)-plasma phase separation on platelet transport [5], whereby platelet localized concentration can be enhanced due to a non-uniform distribution of RBCs of blood flow in a capillary tube and sudden expansion. However,more » current platelet deposition models either totally ignored RBCs in the fluid by assuming a zero sample hematocrit or treated them as being evenly distributed. As a result, those models often underestimated platelet advection and deposition to certain areas [2]. The current study aims to develop a two-phase blood constitutive model that can predict phase separation in a RBC-plasma mixture at the micro scale. The model is based on a sophisticated theory known as theory of interacting continua, i.e., mixture theory. The volume fraction is treated as a field variable in this model, which allows the prediction of concentration as well as velocity profiles of both RBC and plasma phases. The results will be used as the input of successive platelet deposition models.« less

Biological groundwater denitrification systems: Lab-scale trials aimed at nitrous oxide production and emission assessment.

PubMed

Capodici, Marco; Avona, Alessia; Laudicina, Vito Armando; Viviani, Gaspare

2018-07-15

Bio-trenches are a sustainable option for treating nitrate contamination in groundwater. However, a possible side effect of this technology is the production of nitrous oxide, a greenhouse gas that can be found both dissolved in the liquid effluent as well as emitted as off gas. The aim of this study was to analyze NO 3 - removal and N 2 O production in lab-scale column trials. The column contained olive nut as organic carbon media. The experimental study was divided into three phases (I, II and III) each characterized by different inlet NO 3 - concentrations (30, 50, 75mgNO 3 -NL -1 respectively). Sampling ports deployed along the length of the column allowed to observe the denitrification process as well as the formation and consumption of intermediate products, such as nitrite (NO 2 - ) and nitrous oxide (N 2 O). In particular, it was observed that N 2 O production represent only a small fraction of removed NO 3 - during Phase I and II, both for dissolved (0.007%) and emitted (0.003%) phase, and it was recorded a high denitrification efficiency, over 99%. Nevertheless, significantly higher values were recorded for Phase 3 concerning emitted phase (0.018%). This fact is due to increased inlet concentration which resulted in a carbon limitation and in a consequent decrease in denitrification efficiency (76%). Copyright © 2018 Elsevier B.V. All rights reserved.

A low-cost hierarchical nanostructured beta-titanium alloy with high strength

PubMed Central

Devaraj, Arun; Joshi, Vineet V.; Srivastava, Ankit; Manandhar, Sandeep; Moxson, Vladimir; Duz, Volodymyr A.; Lavender, Curt

2016-01-01

Lightweighting of automobiles by use of novel low-cost, high strength-to-weight ratio structural materials can reduce the consumption of fossil fuels and in turn CO2 emission. Working towards this goal we achieved high strength in a low cost β-titanium alloy, Ti–1Al–8V–5Fe (Ti185), by hierarchical nanostructure consisting of homogenous distribution of micron-scale and nanoscale α-phase precipitates within the β-phase matrix. The sequence of phase transformation leading to this hierarchical nanostructure is explored using electron microscopy and atom probe tomography. Our results suggest that the high number density of nanoscale α-phase precipitates in the β-phase matrix is due to ω assisted nucleation of α resulting in high tensile strength, greater than any current commercial titanium alloy. Thus hierarchical nanostructured Ti185 serves as an excellent candidate for replacing costlier titanium alloys and other structural alloys for cost-effective lightweighting applications. PMID:27034109

NONLINEAR OPTICAL EFFECTS AND FIBER OPTICS: Pulsed neodymium amplifier with phase conjugation and direct amplification

NASA Astrophysics Data System (ADS)

Basov, N. G.; Efimkov, V. F.; Zubarev, I. G.; Kolobrodov, V. V.; Pastukhov, S. A.; Smirnov, M. G.; Sobolev, V. B.

1988-12-01

A study was made of the characteristics of an amplifier containing neodymium-activated silicate rods, 45 mm in diameter, used in direct amplification and phase conjugation systems. At low output energies the divergence of the output radiation in the presence of a phase-conjugating mirror was half ( ~ 10- 4 rad) that in the case of direct amplification. An increase in the output power caused the divergence to rise more rapidly in the presence of a phase-conjugating mirror, which was tentatively attributed to an earlier manifestation of large-scale self-focusing. Output energies of 130 J in the case of direct amplification and 80 J in the presence of a phase-conjugating mirror were obtained when the output pulse duration was ~ 2 ns and the fraction of the total energy contained within an angle of ~ 10- 4 rad was ~ 0.3.

Examining Changes to the Madden-Julian Oscillation in a Warmer Climate Using CMIP5 Models

NASA Astrophysics Data System (ADS)

Rushley, Stephanie

Five models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) that reasonably represent the Madden-Julian Oscillation (MJO) are used to examine the response of the MJO to greenhouse gas induced warming. Changes in the MJO's amplitude, zonal scale, and phase speed are examined using daily-mean precipitation during boreal winter (November to April) when the MJO is strongest. The MJO precipitation variance increases with tropics mean surface temperature. However, the westward moving waves of the same temporal and spatial scales increase at about the same rate, suggesting that the maintenance mechanism for the MJO does not change with warming. On the other hand, a robust increase in phase speed of the MJO is found with a rate of 5-12% per degree of surface warming. The robust increase in the MJO phase speed are examined using the linear moisture wave theory of Adames and Kim (2016). In this theory, the MJO phase speed is determined by the horizontal moisture gradient in the lower troposphere, the gross dry stability, the convective moisture adjustment timescale, and zonal wavenumber of the MJO. All CMIP5 models examined show an increase in the horizontal humidity gradient, the gross dry stability and the convective moisture adjustment timescale, while exhibiting a decrease in the zonal wavenumber of the MJO. The increase in the horizontal humidity gradient and zonal scale of the MJO act to increase the speed of the MJO by enhancing horizontal moisture advection associated with the MJO, while the gross dry stability and convective moisture adjustment timescale act to slow down the MJO by dampening the horizontal moisture advection process. In all the models, the combined effects of the four key parameters act to speed up the MJO, matching the calculated phase speed changes with warming in the models.

Production of Hydrogen by Superadiabatic Decomposition of Hydrogen Sulfide - Final Technical Report for the Period June 1, 1999 - September 30, 2000

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

Rachid B. Slimane; Francis S. Lau; Javad Abbasian

2000-10-01

The objective of this program is to develop an economical process for hydrogen production, with no additional carbon dioxide emission, through the thermal decomposition of hydrogen sulfide (H{sub 2}S) in H{sub 2}S-rich waste streams to high-purity hydrogen and elemental sulfur. The novel feature of the process being developed is the superadiabatic combustion (SAC) of part of the H{sub 2}S in the waste stream to provide the thermal energy required for the decomposition reaction such that no additional energy is required. The program is divided into two phases. In Phase 1, detailed thermochemical and kinetic modeling of the SAC reactor withmore » H{sub 2}S-rich fuel gas and air/enriched air feeds is undertaken to evaluate the effects of operating conditions on exit gas products and conversion efficiency, and to identify key process parameters. Preliminary modeling results are used as a basis to conduct a thorough evaluation of SAC process design options, including reactor configuration, operating conditions, and productivity-product separation schemes, with respect to potential product yields, thermal efficiency, capital and operating costs, and reliability, ultimately leading to the preparation of a design package and cost estimate for a bench-scale reactor testing system to be assembled and tested in Phase 2 of the program. A detailed parametric testing plan was also developed for process design optimization and model verification in Phase 2. During Phase 2 of this program, IGT, UIC, and industry advisors UOP and BP Amoco will validate the SAC concept through construction of the bench-scale unit and parametric testing. The computer model developed in Phase 1 will be updated with the experimental data and used in future scale-up efforts. The process design will be refined and the cost estimate updated. Market survey and assessment will continue so that a commercial demonstration project can be identified.« less

Variability of a Stellar Corona on a Time Scale of Days: Evidence for Abundance Fractionation in an Emerging Coronal Active Region

NASA Technical Reports Server (NTRS)

Nordon, R.; Behar, E.; Drake, S. A.

2013-01-01

Elemental abundance effects in active coronae have eluded our understanding for almost three decades, since the discovery of the first ionization potential (FIP) effect on the sun. The goal of this paper is to monitor the same coronal structures over a time interval of six days and resolve active regions on a stellar corona through rotational modulation. We report on four iso-phase X-ray spectroscopic observations of the RS CVn binary EI Eri with XMM-Newton, carried out approximately every two days, to match the rotation period of EI Eri. We present an analysis of the thermal and chemical structure of the EI Eri corona as it evolves over the six days. Although the corona is rather steady in its temperature distribution, the emission measure and FIP bias both vary and seem to be correlated. An active region, predating the beginning of the campaign, repeatedly enters into our view at the same phase as it rotates from beyond the stellar limb. As a result, the abundances tend slightly, but consistently, to increase for high FIP elements (an inverse FIP effect) with phase. We estimate the abundance increase of high FIP elements in the active region to be of about 75% over the coronal mean. This observed fractionation of elements in an active region on time scales of days provides circumstantial clues regarding the element enrichment mechanism of non-flaring stellar coronae.

Hydrodynamic scaling of the deceleration-phase Rayleigh–Taylor instability

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

Bose, A., E-mail: abos@lle.rochester.edu; Woo, K. M.; Betti, R.

2015-07-15

The scaling of the deceleration phase of inertial fusion direct-drive implosions is investigated for OMEGA and National Ignition Facility (NIF)-size targets. It is shown that the deceleration-phase Rayleigh–Taylor instability (RTI) does not scale hydro-equivalently with implosion size. This is because ablative stabilization resulting from thermal conduction and radiation transport in a spherically converging geometry is different on the two scales. As a consequence, NIF-scale implosions show lower hot-spot density and mass ablation velocity, allowing for higher RTI growth. On the contrary, stabilization resulting from density-gradient enhancement, caused by reabsorption of radiation emitted from the hot spot, is higher on NIFmore » implosions. Since the RTI mitigation related to thermal conduction and radiation transport scale oppositely with implosion size, the degradation of implosion performance caused by the deceleration RTI is similar for NIF and OMEGA targets. It is found that a minimum threshold for the no-α Lawson ignition parameter of χ{sub Ω} ≈ 0.2 at the OMEGA scale is required to demonstrate hydro-equivalent ignition at the NIF scale for symmetric direct-drive implosions.« less

Hydrodynamic scaling of the deceleration-phase Rayleigh–Taylor instability

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

Bose, A.; Woo, K. M.; Nora, R.

2015-07-02

The scaling of the deceleration phase of inertial fusion direct-drive implosions is investigated for OMEGA and National Ignition Facility (NIF)-size targets. It is shown that the deceleration-phase Rayleigh–Taylor instability (RTI) does not scale hydro-equivalently with implosion size. This is because ablative stabilization resulting from thermal conduction and radiation transport in a spherically converging geometry is different on the two scales. As a consequence, NIF-scale implosions show lower hot-spot density and mass ablation velocity, allowing for higher RTI growth. On the contrary, stabilization resulting from density-gradient enhancement, caused by reabsorption of radiation emitted from the hot spot, is higher on NIFmore » implosions. Since the RTI mitigation related to thermal conduction and radiation transport scale oppositely with implosion size, the degradation of implosion performance caused by the deceleration RTI is similar for NIF and OMEGA targets. It is found that a minimum threshold for the no-α Lawson ignition parameter of ΧΩ ≈ 0.2 at the OMEGA scale is required to demonstrate hydro-equivalent ignition at the NIF scale for symmetric direct-drive implosions.« less

POLECAT: Preparatory and modelling studies

NASA Astrophysics Data System (ADS)

Peter, T.; Müller, R.; Pawson, S.; Volkert, H.

1995-02-01

“POLECAT” is the acronym for a mission to polar stratospheric clouds, lee waves, chemistry, aerosols and transport. It constitutes a lead project of the German ozone research program sponsored by the Federal Ministry of Education and Research (BMBF). It focusses on the investigation of polar stratospheric clouds (PSCs) in the northern hemisphere with special emphasis on mesoscale effects, in particular lee waves, and their effects on polar stratospheric chemistry. The project comprises two phases. Phase 1 will support laboratory studies on PSC microphysics and heterogeneous chemistry, modelling studies on all scales, and selected field experiments concerning particle measurements as well as characterization of the direct chemical products of heterogeneous reactions. Phase 2 will cover a mission of the high-altitude aircraft Strato-2C, used for flights along streamlines across orographically perturbed regions for direct investigation of PSC effects. This paper presents some preparatory work for the upcoming project and, hence, concentrates on modelling studies including the planning strategies for the future aircraft missions.

Effects of Swirler Shape on Two-Phase Swirling Flow in a Steam Separator

NASA Astrophysics Data System (ADS)

Kataoka, Hironobu; Shinkai, Yusuke; Tomiyama, Akio

Experiments on two-phase swirling flow in a separator are carried out using several swirlers having different vane angles, different hub diameters and different number of vanes to seek a way for improving steam separators of uprated boiling water reactors. Ratios of the separated liquid flow rate to the total liquid flow rate, flow patterns, liquid film thicknesses and pressure drops are measured to examine the effects of swirler shape on air-water two-phase swirling annular flows in a one-fifth scale model of the separator. As a result, the following conclusions are obtained for the tested swirlers: (1) swirler shape scarcely affects the pressure drop in the barrel of the separator, (2) decreasing the vane angle is an effective way for reducing the pressure drop in the diffuser of the separator, and (3) the film thickness at the inlet of the pick-off-ring of the separator is not sensitive to swirler shape, which explains the reason why the separator performance does not depend on swirler shape.

The effect of atmospheric diabatic heating on low-frequency oscillations

NASA Astrophysics Data System (ADS)

Yen, Ming-Cheng

A diagnostic scheme is devised to illustrate a chain relationship between diabatic heating and planetary-scale divergent and rotational circulations. The scheme consists of the velocity-potential maintenance equation, which relates diabatic heating and velocity potential, and the streamfunction budget equation, which depicts the streamfunction tendency caused by the imbalance between streamfunction tendencies induced by vorticity advection and source. The proposed scheme is employed to examine the effect of tropical diabatic heating on the annual variation of subtropical jet streams. It was found that annual variations of both tropical diabatic heating and planetary-scale divergent circulation exhibit an annual in-phase seesaw oscillation between the winter and summer hemispheres. The annual variation of subtropical jet streams is caused by the adjustment of atmospheric rotational flow through planetary-scale divergent circulation in response to the annual cycle of tropical diabatic heating.

Leading a change process to improve health service delivery.

PubMed Central

Bahamon, Claire; Dwyer, Joseph; Buxbaum, Ann

2006-01-01

In the fields of health and development, donors channel multiple resources into the design of new practices and technologies, as well as small-scale programmes to test them. But successful practices are rarely scaled up to the level where they beneficially impact large, impoverished populations. An effective process for change is to use the experiences of new practices gained at the programme level for full-scale implementation. To make an impact, new practices need to be applied, and supported by management systems, at many organizational levels. At every level, potential implementers and likely beneficiaries must first recognize some characteristics that would benefit them in the new practices. An effective change process, led by a dedicated internal change agent, comprises several well-defined phases that successively broaden and institutionalize the use of new practices. PMID:16917654

Flue gas conditioning for improved particle collection in electrostatic precipitators

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

Durham, M.D.

1992-04-27

The purpose of this research program is to identify and evaluate a variety of additives capable of increasing particle cohesion which could be used for improving collection efficiency in an ESP. A three-phase screening process will be used to provide the, evaluation of many additives in a logical and cost-effective manner. The three step approach involves the following experimental setups: 1. Provide a preliminary screening in the laboratory by measuring the effects of various conditioning agents on reentrainment of flyash particles in an electric field operating at simulated flue gas conditions. 2. Evaluate the successful additives using a 100 acfmmore » bench-scale ESP operating on actual flue gas. 3. Obtain the data required for scaling up the technology by testing the two or three most promising conditioning agents at the pilot scale.« less