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Sample records for additional length scale

  1. Multi-Length-Scale Morphologies Driven by Mixed Additives in Porphyrin-Based Organic Photovoltaics.

    PubMed

    Gao, Ke; Miao, Jingsheng; Xiao, Liangang; Deng, Wanyuan; Kan, Yuanyuan; Liang, Tianxiang; Wang, Cheng; Huang, Fei; Peng, Junbiao; Cao, Yong; Liu, Feng; Russell, Thomas P; Wu, Hongbin; Peng, Xiaobin

    2016-06-01

    A new category of deep-absorbing small molecules is developed. Optimized devices driven by mixed additives show a remarkable short-circuit current of ≈20 mA cm(-2) and a highest power conversion efficiency of 9.06%. A multi-length-scale morphology is formed, which is fully characterized by resonant soft X-ray scattering, high-angle annular dark film image transmission electron microscopy, etc.

  2. Softness Correlations Across Length Scales

    NASA Astrophysics Data System (ADS)

    Ivancic, Robert; Shavit, Amit; Rieser, Jennifer; Schoenholz, Samuel; Cubuk, Ekin; Durian, Douglas; Liu, Andrea; Riggleman, Robert

    In disordered systems, it is believed that mechanical failure begins with localized particle rearrangements. Recently, a machine learning method has been introduced to identify how likely a particle is to rearrange given its local structural environment, quantified by softness. We calculate the softness of particles in simulations of atomic Lennard-Jones mixtures, molecular Lennard-Jones oligomers, colloidal systems and granular systems. In each case, we find that the length scale characterizing spatial correlations of softness is approximately a particle diameter. These results provide a rationale for why localized rearrangements--whose size is presumably set by the scale of softness correlations--might occur in disordered systems across many length scales. Supported by DOE DE-FG02-05ER46199.

  3. Addition of low concentrations of an ionic liquid to a base oil reduces friction over multiple length scales: a combined nano- and macrotribology investigation.

    PubMed

    Li, Hua; Somers, Anthony E; Howlett, Patrick C; Rutland, Mark W; Forsyth, Maria; Atkin, Rob

    2016-03-01

    The efficacy of ionic liquids (ILs) as lubricant additives to a model base oil has been probed at the nanoscale and macroscale as a function of IL concentration using the same materials. Silica surfaces lubricated with mixtures of the IL trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate and hexadecane are probed using atomic force microscopy (AFM) (nanoscale) and ball-on-disc tribometer (macroscale). At both length scales the pure IL is a much more effective lubricant than hexadecane. At the nanoscale, 2.0 mol% IL (and above) in hexadecane lubricates the silica as well as the pure IL due to the formation of a robust IL boundary layer that separates the sliding surfaces. At the macroscale the lubrication is highly load dependent; at low loads all the mixtures lubricate as effectively as the pure IL, whereas at higher loads rather high concentrations are required to provide IL like lubrication. Wear is also pronounced at high loads, for all cases except the pure IL, and a tribofilm is formed. Together, the nano- and macroscales results reveal that the IL is an effective lubricant additive - it reduces friction - in both the boundary regime at the nanoscale and mixed regime at the macroscale.

  4. The NIST Length Scale Interferometer

    PubMed Central

    Beers, John S.; Penzes, William B.

    1999-01-01

    The National Institute of Standards and Technology (NIST) interferometer for measuring graduated length scales has been in use since 1965. It was developed in response to the redefinition of the meter in 1960 from the prototype platinum-iridium bar to the wavelength of light. The history of the interferometer is recalled, and its design and operation described. A continuous program of modernization by making physical modifications, measurement procedure changes and computational revisions is described, and the effects of these changes are evaluated. Results of a long-term measurement assurance program, the primary control on the measurement process, are presented, and improvements in measurement uncertainty are documented.

  5. Mixing lengths scaling in a gravity flow

    SciTech Connect

    Ecke, Robert E; Rivera, Micheal; Chen, Jun; Ecke, Robert E

    2009-01-01

    We present an experimental study of the mixing processes in a gravity current. The turbulent transport of momentum and buoyancy can be described in a very direct and compact form by a Prandtl mixing length model [1]: the turbulent vertical fluxes of momentum and buoyancy are found to scale quadraticatly with the vertical mean gradients of velocity and density. The scaling coefficient is the square of the mixing length, approximately constant over the mixing zone of the stratified shear layer. We show in this paper how, in different flow configurations, this length can be related to the shear length of the flow {radical}({var_epsilon}/{partial_derivative}{sub z}u{sup 3}).

  6. Polymers for gene delivery across length scales

    NASA Astrophysics Data System (ADS)

    Putnam, David

    2006-06-01

    A number of human diseases stem from defective genes. One approach to treating such diseases is to replace, or override, the defective genes with normal genes, an approach called 'gene therapy'. However, the introduction of correctly functioning DNA into cells is a non-trivial matter, and cells must be coaxed to internalize, and then use, the DNA in the desired manner. A number of polymer-based synthetic systems, or 'vectors', have been developed to entice cells to use exogenous DNA. These systems work across the nano, micro and macro length scales, and have been under continuous development for two decades, with varying degrees of success. The design criteria for the construction of more-effective delivery vectors at each length scale are continually evolving. This review focuses on the most recent developments in polymer-based vector design at each length scale.

  7. Coupled length scales in eroding landscapes

    SciTech Connect

    Chan, Kelvin K.; Rothman, Daniel H.

    2001-05-01

    We report results from an empirical study of the anisotropic structure of eroding landscapes. By constructing a novel correlation function, we show quantitatively that small-scale channel-like features of landscapes are coupled to the large-scale structure of drainage basins. We show additionally that this two-scale interaction is scale-dependent. The latter observation suggests that a commonly applied effective equation for erosive transport may itself depend on scale.

  8. The length-scaling properties of topography

    NASA Technical Reports Server (NTRS)

    Weissel, Jeffrey K.; Pratson, Lincoln F.; Malinverno, Alberto

    1994-01-01

    The scaling properties of synthetic topographic surfaces and digital elevation models (DEMs) of topography are examined by analyzing their 'structure functions,' i.e., the qth order powers of the absolute elevation differences: delta h(sub q) (l) = E((absolute value of h(x + l) - h(x))(exp q)). We find that the relation delta h(sub 1 l) approximately equal cl(exp H) describes well the scaling behavior of natural topographic surfaces, as represented by DEMs gridded at 3 arc sec. Average values of the scaling exponent H between approximately 0.5 and 0.7 characterize DEMs from Ethiopia, Saudi Arabia, and Somalia over 3 orders of magnitude range in length scale l (approximately 0.1-150 km). Differences in appparent topographic roughness among the three areas most likely reflect differences in the amplitude factor c. Separate determination of scaling properties in the x and y coordinate directions allows us to assess whether scaling exponents are azimuthally dependent (anisotropic) or whether they are isotropic while the surface itself is anisotropic over a restricted range of length scale. We explore ways to determine whether topographic surfaces are characterized by simple or multiscaling properties.

  9. Topographical length scales of hierarchical superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Dhillon, P. K.; Brown, P. S.; Bain, C. D.; Badyal, J. P. S.; Sarkar, S.

    2014-10-01

    The morphology of hydrophobic CF4 plasma fluorinated polybutadiene surfaces has been characterised using atomic force microscopy (AFM). Judicious choice of the plasma power and exposure duration leads to formation of three different surface morphologies (Micro, Nano, and Micro + Nano). Scaling theory analysis shows that for all three surface topographies, there is an initial increase in roughness with length scale followed by a levelling-off to a saturation level. At length scales around 500 nm, it is found that the roughness is very similar for all three types of surfaces, and the saturation roughness value for the Micro + Nano morphology is found to be intermediate between those for the Micro and Nano surfaces. Fast Fourier Transform (FFT) analysis has shown that the Micro + Nano topography comprises a hierarchical superposition of Micro and Nano morphologies. Furthermore, the Micro + Nano surfaces display the highest local roughness (roughness exponent α = 0.42 for length scales shorter than ∼500 nm), which helps to explain their superhydrophobic behaviour (large water contact angle (>170°) and low hysteresis (<1°)).

  10. Quantum criticality with two length scales.

    PubMed

    Shao, Hui; Guo, Wenan; Sandvik, Anders W

    2016-04-01

    The theory of deconfined quantum critical (DQC) points describes phase transitions at absolute temperature T = 0 outside the standard paradigm, predicting continuous transformations between certain ordered states where conventional theory would require discontinuities. Numerous computer simulations have offered no proof of such transitions, instead finding deviations from expected scaling relations that neither were predicted by the DQC theory nor conform to standard scenarios. Here we show that this enigma can be resolved by introducing a critical scaling form with two divergent length scales. Simulations of a quantum magnet with antiferromagnetic and dimerized ground states confirm the form, proving a continuous transition with deconfined excitations and also explaining anomalous scaling at T > 0. Our findings revise prevailing paradigms for quantum criticality, with potential implications for many strongly correlated materials. PMID:26989196

  11. Quantum criticality with two length scales

    NASA Astrophysics Data System (ADS)

    Shao, Hui; Guo, Wenan; Sandvik, Anders W.

    2016-04-01

    The theory of deconfined quantum critical (DQC) points describes phase transitions at absolute temperature T = 0 outside the standard paradigm, predicting continuous transformations between certain ordered states where conventional theory would require discontinuities. Numerous computer simulations have offered no proof of such transitions, instead finding deviations from expected scaling relations that neither were predicted by the DQC theory nor conform to standard scenarios. Here we show that this enigma can be resolved by introducing a critical scaling form with two divergent length scales. Simulations of a quantum magnet with antiferromagnetic and dimerized ground states confirm the form, proving a continuous transition with deconfined excitations and also explaining anomalous scaling at T > 0. Our findings revise prevailing paradigms for quantum criticality, with potential implications for many strongly correlated materials.

  12. Critical length scale controls adhesive wear mechanisms.

    PubMed

    Aghababaei, Ramin; Warner, Derek H; Molinari, Jean-Francois

    2016-01-01

    The adhesive wear process remains one of the least understood areas of mechanics. While it has long been established that adhesive wear is a direct result of contacting surface asperities, an agreed upon understanding of how contacting asperities lead to wear debris particle has remained elusive. This has restricted adhesive wear prediction to empirical models with limited transferability. Here we show that discrepant observations and predictions of two distinct adhesive wear mechanisms can be reconciled into a unified framework. Using atomistic simulations with model interatomic potentials, we reveal a transition in the asperity wear mechanism when contact junctions fall below a critical length scale. A simple analytic model is formulated to predict the transition in both the simulation results and experiments. This new understanding may help expand use of computer modelling to explore adhesive wear processes and to advance physics-based wear laws without empirical coefficients. PMID:27264270

  13. Critical length scale controls adhesive wear mechanisms

    PubMed Central

    Aghababaei, Ramin; Warner, Derek H.; Molinari, Jean-Francois

    2016-01-01

    The adhesive wear process remains one of the least understood areas of mechanics. While it has long been established that adhesive wear is a direct result of contacting surface asperities, an agreed upon understanding of how contacting asperities lead to wear debris particle has remained elusive. This has restricted adhesive wear prediction to empirical models with limited transferability. Here we show that discrepant observations and predictions of two distinct adhesive wear mechanisms can be reconciled into a unified framework. Using atomistic simulations with model interatomic potentials, we reveal a transition in the asperity wear mechanism when contact junctions fall below a critical length scale. A simple analytic model is formulated to predict the transition in both the simulation results and experiments. This new understanding may help expand use of computer modelling to explore adhesive wear processes and to advance physics-based wear laws without empirical coefficients. PMID:27264270

  14. Critical length scale controls adhesive wear mechanisms

    NASA Astrophysics Data System (ADS)

    Aghababaei, Ramin; Warner, Derek H.; Molinari, Jean-Francois

    2016-06-01

    The adhesive wear process remains one of the least understood areas of mechanics. While it has long been established that adhesive wear is a direct result of contacting surface asperities, an agreed upon understanding of how contacting asperities lead to wear debris particle has remained elusive. This has restricted adhesive wear prediction to empirical models with limited transferability. Here we show that discrepant observations and predictions of two distinct adhesive wear mechanisms can be reconciled into a unified framework. Using atomistic simulations with model interatomic potentials, we reveal a transition in the asperity wear mechanism when contact junctions fall below a critical length scale. A simple analytic model is formulated to predict the transition in both the simulation results and experiments. This new understanding may help expand use of computer modelling to explore adhesive wear processes and to advance physics-based wear laws without empirical coefficients.

  15. Going up in time and length scales in modeling polymers

    NASA Astrophysics Data System (ADS)

    Grest, Gary S.

    Polymer properties depend on a wide range of coupled length and time scales, with unique macroscopic viscoelastic behavior stemming from interactions at the atomistic level. The need to probe polymers across time and length scales and particularly computational modeling is inherently challenging. Here new paths to probing long time and length scales including introducing interactions into traditional bead-spring models and coarse graining of atomistic simulations will be compared and discussed. Using linear polyethylene as a model system, the degree of coarse graining with two to six methylene groups per coarse-grained bead derived from a fully atomistic melt simulation were probed. We show that the degree of coarse graining affects the measured dynamic. Using these models we were successful in probing highly entangled melts and were able reach the long-time diffusive regime which is computationally inaccessible using atomistic simulations. We simulated the relaxation modulus and shear viscosity of well-entangled polyethylene melts for scaled times of 500 µs. Results for plateau modulus are in good agreement with experiment. The long time and length scale is coupled to the macroscopic viscoelasticity where the degree of coarse graining sets the minimum length scale instrumental in defining polymer properties and dynamics. Results will be compared to those obtained from simple bead-spring models to demonstrate the additional insight that can be gained from atomistically inspired coarse grained models. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  16. How Cells Measure Length on Subcellular Scales.

    PubMed

    Marshall, Wallace F

    2015-12-01

    Cells are not just amorphous bags of enzymes, but precise and complex machines. With any machine, it is important that the parts be of the right size, yet our understanding of the mechanisms that control size of cellular structures remains at a rudimentary level in most cases. One problem with studying size control is that many cellular organelles have complex 3D structures that make their size hard to measure. Here we focus on linear structures within cells, for which the problem of size control reduces to the problem of length control. We compare and contrast potential mechanisms for length control to understand how cells solve simple geometry problems. PMID:26437596

  17. Length Scales in Bayesian Automatic Adaptive Quadrature

    NASA Astrophysics Data System (ADS)

    Adam, Gh.; Adam, S.

    2016-02-01

    Two conceptual developments in the Bayesian automatic adaptive quadrature approach to the numerical solution of one-dimensional Riemann integrals [Gh. Adam, S. Adam, Springer LNCS 7125, 1-16 (2012)] are reported. First, it is shown that the numerical quadrature which avoids the overcomputing and minimizes the hidden floating point loss of precision asks for the consideration of three classes of integration domain lengths endowed with specific quadrature sums: microscopic (trapezoidal rule), mesoscopic (Simpson rule), and macroscopic (quadrature sums of high algebraic degrees of precision). Second, sensitive diagnostic tools for the Bayesian inference on macroscopic ranges, coming from the use of Clenshaw-Curtis quadrature, are derived.

  18. Interaction of turbulent length scales with wind turbine blades

    NASA Astrophysics Data System (ADS)

    Torres-Nieves, Sheilla N.

    wind turbine blade as a consequence of its geometry) on the behavior of turbulent boundary layers and to identify and quantify the length scales that are affected by these external conditions. Laser Doppler and hot-wire anemometry measurements, for smooth and rough surfaces, confirmed that FST and FPG cause a reduction in the wake of the boundary layer. Moreover, results show a discrepancy in the behavior of the stream-wise and wall-normal variances due to free-stream turbulence. As a result, the addition of FST increases the anisotropy in the body of the boundary layer. For FPG flows, a budget analysis of the Reynolds stresses shows that turbulent transport and pressure strain terms are responsible for the increase in the stream-wise Reynolds stress component when FST is present. Second-order structure functions and energy spectra are examined to identify and quantify which turbulence length-scales contribute mostly to the increased anisotropy, and to compare these effects to the case of a zero pressure gradient (ZPG) boundary layer. For ZPG flows, it is shown that the anisotropy created by adding nearly isotropic turbulence in the free-stream resides mostly in the larger scales of the flow, in a range between r/delta95 = 3 and 10. With an imposed FPG, the effect of FST resides in the very-largest length scales of the flow, r ≥ 4.3delta95, corresponding to scales of the same size, and even larger, than the integral scale of the outer free-stream turbulence. However, the free-stream turbulence is not increasing the anisotropy to the extent that it did for the ZPG case. The effects of surface roughness on the different length scales of the flow, when a FPG and additional levels of FST are present, are also examined. Second-order structure functions and energy spectra analysis suggests that for highly turbulent favorable pressure gradient flows, the effect of roughness at the surface is felt, not only by the small length scales of the flow, but also by large (e.g. r

  19. Localization length scales of triplet excitons in singlet fission materials

    NASA Astrophysics Data System (ADS)

    Bayliss, Sam L.; Thorley, Karl J.; Anthony, John E.; Bouchiat, Hélène; Greenham, Neil C.; Chepelianskii, Alexei D.

    2015-09-01

    We measure the dielectric confinement length scales of triplet excitons in organic semiconductors by jointly measuring their microwave-domain electric and magnetic susceptibilities. We apply this technique to characterize triplet excitons in two singlet fission materials with distinct solid-state packing and correlate the extracted localization length scales with the role of the excitonic environment. By using the magnetic susceptibility simultaneously determined through our experiments, we compare the independently extracted dielectric and spin-spin localization length scales, highlighting the role of local anisotropy on the properties of excitonic triplet states.

  20. Hydrodynamic length-scale selection in microswimmer suspensions

    NASA Astrophysics Data System (ADS)

    Heidenreich, Sebastian; Dunkel, Jörn; Klapp, Sabine H. L.; Bär, Markus

    2016-08-01

    A universal characteristic of mesoscale turbulence in active suspensions is the emergence of a typical vortex length scale, distinctly different from the scale invariance of turbulent high-Reynolds number flows. Collective length-scale selection has been observed in bacterial fluids, endothelial tissue, and active colloids, yet the physical origins of this phenomenon remain elusive. Here, we systematically derive an effective fourth-order field theory from a generic microscopic model that allows us to predict the typical vortex size in microswimmer suspensions. Building on a self-consistent closure condition, the derivation shows that the vortex length scale is determined by the competition between local alignment forces, rotational diffusion, and intermediate-range hydrodynamic interactions. Vortex structures found in simulations of the theory agree with recent measurements in Bacillus subtilis suspensions. Moreover, our approach yields an effective viscosity enhancement (reduction), as reported experimentally for puller (pusher) microorganisms.

  1. Hydrodynamic length-scale selection in microswimmer suspensions.

    PubMed

    Heidenreich, Sebastian; Dunkel, Jörn; Klapp, Sabine H L; Bär, Markus

    2016-08-01

    A universal characteristic of mesoscale turbulence in active suspensions is the emergence of a typical vortex length scale, distinctly different from the scale invariance of turbulent high-Reynolds number flows. Collective length-scale selection has been observed in bacterial fluids, endothelial tissue, and active colloids, yet the physical origins of this phenomenon remain elusive. Here, we systematically derive an effective fourth-order field theory from a generic microscopic model that allows us to predict the typical vortex size in microswimmer suspensions. Building on a self-consistent closure condition, the derivation shows that the vortex length scale is determined by the competition between local alignment forces, rotational diffusion, and intermediate-range hydrodynamic interactions. Vortex structures found in simulations of the theory agree with recent measurements in Bacillus subtilis suspensions. Moreover, our approach yields an effective viscosity enhancement (reduction), as reported experimentally for puller (pusher) microorganisms. PMID:27627229

  2. DHS Internship Summary-Crystal Assembly at Different Length Scales

    SciTech Connect

    Mishchenko, L

    2009-08-06

    I was part of a project in which in situ atomic force microscopy (AFM) was used to monitor growth and dissolution of atomic and colloidal crystals. At both length scales, the chemical environment of the system greatly altered crystal growth and dissolution. Calcium phosphate was used as a model system for atomic crystals. A dissolution-reprecipitation reaction was observed in this first system, involving the conversion of brushite (DCPD) to octacalcium phosphate (OCP). In the second system, polymeric colloidal crystals were dissolved in an ionic solvent, revealing the underlying structure of the crystal. The dissolved crystal was then regrown through an evaporative step method. Recently, we have also found that colloids can be reversibly deposited in situ onto an ITO (indium tin oxide) substrate via an electrochemistry setup. The overall goal of this project was to develop an understanding of the mechanisms that control crystallization and order, so that these might be controlled during material synthesis. Controlled assembly of materials over a range of length scales from molecules to nanoparticles to colloids is critical for designing new materials. In particular, developing materials for sensor applications with tailorable properties and long range order is important. In this work, we examine two of these length scales: small molecule crystallization of calcium phosphate (whose crystal phases include DCPD, OCP, and HAP) and colloidal crystallization of Poly(methyl methacrylate) beads. Atomic Force Microscopy is ideal for this line of work because it allows for the possibility of observing non-conducting samples in fluid during growth with high resolution ({approx} 10 nm). In fact, during atomic crystal growth one can observe changes in atomic steps, and with colloidal crystals, one can monitor the individual building blocks of the crystal. Colloids and atoms crystallize under the influence of different forces acting at different length scales as seen in Table 1

  3. SQUID magnetometry from nanometer to centimeter length scales

    NASA Astrophysics Data System (ADS)

    Hatridge, Michael Jonathan

    Information stored in magnetic fields plays an important role in everyday life. This information exists over a remarkably wide range of sizes, so that magnetometry at a variety of length scales can extract useful information. Examples at centimeter to millimeter length scales include measurement of spatial and temporal character of fields generated in the human brain and heart, and active manipulation of spins in the human body for non-invasive magnetic resonance imaging (MRI). At micron length scales, magnetometry can be used to measure magnetic objects such as flux qubits; at nanometer length scales it can be used to study individual magnetic domains, and even individual spins. The development of Superconducting QUantum Interference Device (SQUID) based magnetometer for two such applications, in vivo prepolarized, ultra-low field MRI of humans and dispersive readout of SQUIDs for micro- and nanoscale magnetometry, are the focus of this thesis. Conventional MRI has developed into a powerful clinical tool for imaging the human body. This technique is based on nuclear magnetic resonance of protons with the addition application of three-dimensional magnetic field gradients to encode spatial information. Most clinical MRI systems involve magnetic fields generated by superconducting magnets, and the current trend is to higher magnetic fields than the widely used 1.5-T systems. Nonetheless, there is ongoing interest in the development of less expensive imagers operating at lower fields. The prepolarized, SQUID detected ultra-low field MRI (ULF MRI) developed by the Clarke group allows imaging in very weak fields (typically 132 muT, corresponding to a resonant frequency of 5.6 kHz). At these low field strengths, there is enhanced contrast in the longitudinal relaxation time of various tissue types, enabling imaging of objects which are not visible to conventional MRI, for instance prostate cancer. We are currently investigating the contrast between normal and cancerous

  4. Length scales and self-organization in dense suspension flows

    NASA Astrophysics Data System (ADS)

    Düring, Gustavo; Lerner, Edan; Wyart, Matthieu

    2014-02-01

    Dense non-Brownian suspension flows of hard particles display mystifying properties: As the jamming threshold is approached, the viscosity diverges, as well as a length scale that can be identified from velocity correlations. To unravel the microscopic mechanism governing dissipation and its connection to the observed correlation length, we develop an analogy between suspension flows and the rigidity transition occurring when floppy networks are pulled, a transition believed to be associated with the stress stiffening of certain gels. After deriving the critical properties near the rigidity transition, we show numerically that suspension flows lie close to it. We find that this proximity causes a decoupling between viscosity and the correlation length of velocities ξ, which scales as the length lc characterizing the response to a local perturbation, previously predicted to follow lc˜1/√zc-z ˜p0.18, where p is the dimensionless particle pressure, z is the coordination of the contact network made by the particles, and zc is twice the spatial dimension. We confirm these predictions numerically and predict the existence of a larger length scale lr˜√p with mild effects on velocity correlation and of a vanishing strain scale δγ ˜1/p that characterizes decorrelation in flow.

  5. Procedure for Determining Turbulence Length Scales Using Hotwire Anemometry

    NASA Technical Reports Server (NTRS)

    El-Gabry, Lamyaa A.; Thurman, Douglas R.; Poinsatte, Philip E.

    2014-01-01

    Hotwire anemometers are used to measure instantaneous velocity from which the mean velocity and the velocity fluctuation can be determined. Using a hotwire system, it is possible to deduce not only the velocity components and their fluctuation but to also analyze the energy spectra and from that the turbulence length scales. In this experiment, hotwire anemometry is used to measure the flow field turbulence for an array of film cooling holes. The objective of this paper is to document the procedure that is used to reduce the instantaneous velocity measurements to determine the turbulence length scales using data from the film-cooling experiments to illustrate the procedure.

  6. A two-scale damage model with material length

    NASA Astrophysics Data System (ADS)

    Dascalu, Cristian

    2009-09-01

    The Note presents the formulation of a class of two-scale damage models involving a micro-structural length. A homogenization method based on asymptotic developments is employed to deduce the macroscopic damage equations. The damage model completely results from energy-based micro-crack propagation laws, without supplementary phenomenological assumptions. We show that the resulting two-scale model has the property of capturing micro-structural lengths. When damage evolves, the micro-structural length is given by the ratio of the surface density of energy dissipated during the micro-crack growth and the macroscopic damage energy release rate per unit volume of the material. The use of fracture criteria based on resistance curves or power laws for sub-critical growth of micro-cracks leads to quasi-brittle and, respectively, time-dependent damage models. To cite this article: C. Dascalu, C. R. Mecanique 337 (2009).

  7. Estimation of Length-Scales in Soils by MRI

    NASA Technical Reports Server (NTRS)

    Daidzic, N. E.; Altobelli, S.; Alexander, J. I. D.

    2004-01-01

    Soil can be best described as an unconsolidated granular media that forms porous structure. The present macroscopic theory of water transport in porous media rests upon the continuum hypothesis that the physical properties of porous media can be associated with continuous, twice-differentiable field variables whose spatial domain is a set of centroids of Representative Elementary Volume (REV) elements. MRI is an ideal technique to estimate various length-scales in porous media. A 0.267 T permanent magnet at NASA GRC was used for this study. A 2D or 3D spatially-resolved porosity distribution were obtained from the NMR signal strength from each voxel and the spin-lattice relaxation time. A classical spin-warp imaging with Multiple Spin Echos (MSE) was used to evaluate proton density in each voxel. Initial resolution of 256 x 256 was subsequently reduced by averaging neighboring voxels and the porosity convergence was observed. A number of engineered "space candidate" soils such as Isolite(trademark), Zeoponics(trademark), Turface(trademark), and Profile(trademark) were used. Glass beads in the size range between 50 microns to 2 mm were used as well. Initial results with saturated porous samples have shown a good estimate of the average porosity consistent with the gravimetric porosity measurement results. For Profile(trademark) samples with particle sizes ranging between 0.25 to 1 mm and characteristic interparticle pore size of 100 microns the characteristic Darcy scale was estimated to be about delta(sub REV) = 10 mm. Glass beads porosity show clear convergence toward a definite REV which stays constant throughout homogeneous sample. Additional information is included in the original extended abstract.

  8. Internal length scales in rotating and stratified Boussinesq flows

    NASA Astrophysics Data System (ADS)

    Kurien, Susan; Zhai, X. M.; Yeung, P. K.

    2015-11-01

    We study the characteristic length scales of the propagating (wave) and non-propagating (vortical) modes, in a suite of simulations of forced, rotating, stably stratified Boussinesq flows. We employ a pseudo-spectral code, periodic boundary conditions and grid resolutions ranging from 5123 to 20483 on Blue Gene/Q (Argonne) under DOE's INCITE program. The relative strength of rotation to stratification frequencies is given by the Burger number Bu . Integral length scales in the vertical and horizontal directions are chosen as the characteristic scales and their ratio defines an internal aspect ratio. Nominally quasi-geostrophic (QG) scaling of Bu?1 is recovered for the vortical scale aspect ratio in the stratification-dominated regime Bu >> 4 . Much weaker scaling in Bu emerges for the vortical mode in the rotation-dominated regime Bu << 1 / 4 . The aspect ratio of the wave modes in both regimes are only weakly dependent on Bu . Turbulence affects the wave modes in the strongly rotating case by increasing the aspect ratio systematically but has no impact on the weak Bu dependence. It appears that for unit aspect ratio domains, QG scaling of the vortical mode holds only for stratification-dominated flows irrespective of the strength of rotation.

  9. Progress in Long Scale Length Laser-Plasma Interactions

    SciTech Connect

    Glenzer, S H; Arnold, P; Bardsley, G; Berger, R L; Bonanno, G; Borger, T; Bower, D E; Bowers, M; Bryant, R; Buckman, S; Burkhart, S C; Campbell, K; Chrisp, M P; Cohen, B I; Constantin, G; Cooper, F; Cox, J; Dewald, E; Divol, L; Dixit, S; Duncan, J; Eder, D; Edwards, J; Erbert, G; Felker, B; Fornes, J; Frieders, G; Froula, D H; Gardner, S D; Gates, C; Gonzalez, M; Grace, S; Gregori, G; Greenwood, A; Griffith, R; Hall, T; Hammel, B A; Haynam, C; Heestand, G; Henesian, M; Hermes, G; Hinkel, D; Holder, J; Holdner, F; Holtmeier, G; Hsing, W; Huber, S; James, T; Johnson, S; Jones, O S; Kalantar, D; Kamperschroer, J H; Kauffman, R; Kelleher, T; Knight, J; Kirkwood, R K; Kruer, W L; Labiak, W; Landen, O L; Langdon, A B; Langer, S; Latray, D; Lee, A; Lee, F D; Lund, D; MacGowan, B; Marshall, S; McBride, J; McCarville, T; McGrew, L; Mackinnon, A J; Mahavandi, S; Manes, K; Marshall, C; Mertens, E; Meezan, N; Miller, G; Montelongo, S; Moody, J D; Moses, E; Munro, D; Murray, J; Neumann, J; Newton, M; Ng, E; Niemann, C; Nikitin, A; Opsahl, P; Padilla, E; Parham, T; Parrish, G; Petty, C; Polk, M; Powell, C; Reinbachs, I; Rekow, V; Rinnert, R; Riordan, B; Rhodes, M

    2003-11-11

    The first experiments on the National Ignition Facility (NIF) have employed the first four beams to measure propagation and laser backscattering losses in large ignition-size plasmas. Gas-filled targets between 2 mm and 7 mm length have been heated from one side by overlapping the focal spots of the four beams from one quad operated at 351 nm (3{omega}) with a total intensity of 2 x 10{sup 15} W cm{sup -2}. The targets were filled with 1 atm of CO{sub 2} producing of up to 7 mm long homogeneously heated plasmas with densities of n{sub e} = 6 x 10{sup 20} cm{sup -3} and temperatures of T{sub e} = 2 keV. The high energy in a NIF quad of beams of 16kJ, illuminating the target from one direction, creates unique conditions for the study of laser plasma interactions at scale lengths not previously accessible. The propagation through the large-scale plasma was measured with a gated x-ray imager that was filtered for 3.5 keV x rays. These data indicate that the beams interact with the full length of this ignition-scale plasma during the last {approx}1 ns of the experiment. During that time, the full aperture measurements of the stimulated Brillouin scattering and stimulated Raman scattering show scattering into the four focusing lenses of 6% for the smallest length ({approx}2 mm). increasing to 12% for {approx}7 mm. These results demonstrate the NIF experimental capabilities and further provide a benchmark for three-dimensional modeling of the laser-plasma interactions at ignition-size scale lengths.

  10. Past and Future Blurring at Fundamental Length Scale

    SciTech Connect

    Neves, M. J.; Farina, C.; Cougo-Pinto, M. V.

    2010-11-19

    We obtain the {kappa}-deformed versions of the retarded and advanced Green functions and show that their causality properties are blurred in a time interval of the order of a length parameter q=1/(2{kappa}). The functions also indicate a smearing of the light cone. These results favor the interpretation of q as a fundamental length scale below which the concept of a point in space-time should be substituted by the concept of a fuzzy region of radius q, as proposed long ago by Heisenberg.

  11. Multiple-length-scale deformation analysis in a thermoplastic polyurethane

    PubMed Central

    Sui, Tan; Baimpas, Nikolaos; Dolbnya, Igor P.; Prisacariu, Cristina; Korsunsky, Alexander M.

    2015-01-01

    Thermoplastic polyurethane elastomers enjoy an exceptionally wide range of applications due to their remarkable versatility. These block co-polymers are used here as an example of a structurally inhomogeneous composite containing nano-scale gradients, whose internal strain differs depending on the length scale of consideration. Here we present a combined experimental and modelling approach to the hierarchical characterization of block co-polymer deformation. Synchrotron-based small- and wide-angle X-ray scattering and radiography are used for strain evaluation across the scales. Transmission electron microscopy image-based finite element modelling and fast Fourier transform analysis are used to develop a multi-phase numerical model that achieves agreement with the combined experimental data using a minimal number of adjustable structural parameters. The results highlight the importance of fuzzy interfaces, that is, regions of nanometre-scale structure and property gradients, in determining the mechanical properties of hierarchical composites across the scales. PMID:25758945

  12. Multiple-length-scale deformation analysis in a thermoplastic polyurethane.

    PubMed

    Sui, Tan; Baimpas, Nikolaos; Dolbnya, Igor P; Prisacariu, Cristina; Korsunsky, Alexander M

    2015-01-01

    Thermoplastic polyurethane elastomers enjoy an exceptionally wide range of applications due to their remarkable versatility. These block co-polymers are used here as an example of a structurally inhomogeneous composite containing nano-scale gradients, whose internal strain differs depending on the length scale of consideration. Here we present a combined experimental and modelling approach to the hierarchical characterization of block co-polymer deformation. Synchrotron-based small- and wide-angle X-ray scattering and radiography are used for strain evaluation across the scales. Transmission electron microscopy image-based finite element modelling and fast Fourier transform analysis are used to develop a multi-phase numerical model that achieves agreement with the combined experimental data using a minimal number of adjustable structural parameters. The results highlight the importance of fuzzy interfaces, that is, regions of nanometre-scale structure and property gradients, in determining the mechanical properties of hierarchical composites across the scales. PMID:25758945

  13. Length scales and interfacial potentials in ion hydration

    NASA Astrophysics Data System (ADS)

    Shi, Yu; Beck, Thomas L.

    2013-07-01

    The Quasichemical Theory (QCT) involves a length-scale organization of solvation thermodynamics. The QCT has been employed in studies of solutes ranging in size from small molecules and ions to proteins. There are three contributions to the QCT free energy: (1) an inner-shell term that includes the direct solute-solvent chemical interactions, (2) an outer-shell packing term that is the free energy to dig out a cavity in the solvent, and (3) an outer-shell long-ranged term that includes all interactions of the solute with the solvent conditional on an empty inner shell. The present study utilizes a regularizing generalization of the QCT and classical simulations to compute these three contributions to the ion hydration free energy out to large cavity radii for eight ions in the alkali halide series. The accuracy of simple approximations for the long-ranged term is also examined. The inner-shell contribution exhibits ion specificity for cavity sizes less than 4-5 Å, followed by a common length scale of 6.15 Å at which its value equals the bulk hydration free energy for all eight of the ions. The 6.15 Å length scale is closely approximated by the distance at which the revised scaled-particle theory packing contribution matches the magnitude of a simple Born estimate for the long-ranged term.

  14. Atomistic Simulation of Polymer Crystallization at Realistic Length Scales

    SciTech Connect

    Gee, R H; Fried, L E

    2005-01-28

    Understanding the dynamics of polymer crystallization during the induction period prior to crystal growth is a key goal in polymer physics. Here we present the first study of primary crystallization of polymer melts via molecular dynamics simulations at physically realistic (about 46 nm) length scales. Our results show that the crystallization mechanism involves a spinodal decomposition microphase separation caused by an increase in the average length of rigid trans segments along the polymer backbone during the induction period. Further, the characteristic length of the growing dense domains during the induction period is longer than predicted by classical nucleation theory. These results indicate a new 'coexistence period' in the crystallization, where nucleation and growth mechanisms coexist with a phase separation mechanism. Our results provide an atomistic verification of the fringed micelle model.

  15. Emergence of Chirality from Isotropic Interactions of Three Length Scales

    NASA Astrophysics Data System (ADS)

    Mkhonta, S. K.; Elder, K. R.; Huang, Zhi-Feng

    2016-05-01

    Chirality is known to play a pivotal role in determining material properties and functionalities. However, it remains a great challenge to understand and control the emergence of chirality and the related enantioselective process particularly when the building components of the system are achiral. Here we explore the generic mechanisms driving the formation of two-dimensional chiral structures in systems characterized by isotropic interactions and three competing length scales. We demonstrate that starting from isotropic and rotationally invariant interactions, a variety of chiral ordered patterns and superlattices with anisotropic but achiral units can self-assemble. The mechanisms for selecting specific states are related to the length-scale coupling and the selection of resonant density wave vectors. Sample phase diagrams and chiral elastic properties are identified. These findings provide a viable route for predicting chiral phases and selecting the desired handedness.

  16. Instability of Stratified Shear Flow: Intermittency and Length Scales

    NASA Astrophysics Data System (ADS)

    Ecke, Robert; Odier, Philippe

    2015-11-01

    The stability of stratified shear flows which occur in oceanic overflows, wind-driven thermoclines, and atmospheric inversion layers is governed by the Richardson Number Ri , a non-dimensional balance between stabilizing stratification and destabilizing shear. For a shear flow with velocity difference U, density difference Δρ and characteristic length H, one has Ri = g (Δρ / ρ) H /U2 . A more precise definition is the gradient Richardson Number Rig =N2 /S2 where the buoyancy frequency N =√{ (g / ρ) ∂ρ / ∂z } , the mean strain S = ∂U / ∂z with z parallel to gravity and with ensemble or time averages defining the gradients. We explore the stability and mixing properties of a wall-bounded shear flow for 0 . 1 < Rig < 1 using simultaneous measurements of density and velocity fields. The flow, confined from the top by a horizontal boundary, is a lighter alcohol-water mixture injected from a nozzle into quiescent heavier salt-water fluid. The injected flow is turbulent with Taylor Reynolds number about 75. We compare a set of length scales that characterize the mixing properties of our turbulent stratified shear flow including Thorpe Length LT, Ozmidov Length LO, and Ellison Length LE.

  17. Cloud Shading Effects on Characteristic Boundary-Layer Length Scales

    NASA Astrophysics Data System (ADS)

    Horn, G. L.; Ouwersloot, H. G.; Vilà-Guerau de Arellano, J.; Sikma, M.

    2015-11-01

    We studied the effects of shading by shallow cumulus (shallow Cu) and the subsequent effect of inducing heterogeneous conditions at the surface on boundary-layer characteristics. We placed special emphasis on quantifying the changes in the characteristic length and time scales associated with thermals, shallow Cu and induced thermal circulation structures. A series of systematic numerical experiments, inspired by Amazonian thermodynamic conditions, was performed using a large-eddy simulation model coupled to a land-surface model. We used four different experiments to disentangle the effects of shallow Cu on the surface and the response of clouds to these surface changes. The experiments include a `clear case', `transparent clouds', `shading clouds' and a case with a prescribed uniform domain and reduced surface heat flux. We also performed a sensitivity study on the effect of introducing a weak background flow. Length and time scales were calculated using autocorrelation and two-dimensional spectral analysis, and we found that shading controlled by shallow Cu locally lowers surface temperatures and consequently reduces the sensible and latent heat fluxes, thus inducing spatial and temporal variability in these fluxes. The length scale of this surface heterogeneity is not sufficiently large to generate circulations that are superimposed on the boundary-layer scale, but the heterogeneity does disturb boundary-layer dynamics and generates a flow opposite to the normal thermal circulation. Besides this effect, shallow Cu shading reduces turbulent kinetic energy and lowers the convective velocity scale, thus reducing the mass flux. This hampers the thermal lifetime, resulting in a decrease in the shallow Cu residence time (from 11 to 7 min). This reduction in lifetime, combined with a decrease in mass flux, leads to smaller clouds. This is partially compensated for by a decrease in thermal cell size due to a reduction in turbulent kinetic energy. As a result, inter

  18. Laser Acoustic Microstructure Analysis at the Micron and Nanometer Length Scale

    SciTech Connect

    Telschow, Kenneth Louis; Hurley, David Howard

    2002-05-01

    Laser acoustic approaches to investigating the interaction of elastic waves with microstructure in materials is presented that probe both the micron and nanometer length scales. At the micron length scale, a full-field imaging approach is described that provides quantitative measurement of amplitude and phase of the out-of-plane acoustical motion at GHz frequencies. Specific lateral acoustic modes can be identified in addition to the primary thickness mode with spatial resolution sufficient to image wavelengths as small as 4.5 microns.

  19. Length scale selects directionality of droplets on vibrating pillar ratchet

    SciTech Connect

    Agapov, Rebecca L.; Boreyko, Jonathan B.; Briggs, Dayrl P.; Srijanto, Bernadeta R.; Retterer, Scott T.; Collier, C. Patrick; Lavrik, Nickolay V.

    2014-09-22

    Directional control of droplet motion at room temperature is of interest for applications such as microfluidic devices, self-cleaning coatings, and directional adhesives. Here, arrays of tilted pillars ranging in height from the nanoscale to the microscale are used as structural ratchets to directionally transport water at room temperature. Water droplets deposited on vibrating chips with a nanostructured ratchet move preferentially in the direction of the feature tilt while the opposite directionality is observed in the case of microstructured ratchets. This remarkable switch in directionality is consistent with changes in the contact angle hysteresis. To glean further insights into the length scale dependent asymmetric contact angle hysteresis, the contact lines formed by a nonvolatile room temperature ionic liquid placed onto the tilted pillar arrays were visualized and analyzed in situ in a scanning electron microscope. As a result, the ability to tune droplet directionality by merely changing the length scale of surface features all etched at the same tilt angle would be a versatile tool for manipulating multiphase flows and for selecting droplet directionality in other lap-on-chip applications.

  20. Length-Scale Dependent Viscosity in Semidilute Polyelectrolyte Solutions

    NASA Astrophysics Data System (ADS)

    Poling-Skutvik, Ryan; Krishnamoorti, Ramanan; Conrad, Jacinta

    2015-03-01

    Using optical microscopy and particle tracking algorithms, we measured the mean-squared displacements (MSDs) of fluorescent polystyrene particles with diameters ranging from 300 nm to 2 μm suspended in semidilute solutions of high molecular weight partially hydrolyzed polyacrylamide. The solutions had polymer concentrations ranging from 0.67 to 67c*, where c* is the overlap concentration, and estimated correlation lengths of ~ 100 to 900 nm. At short times, the particles exhibited subdiffusive behavior characterized by MSD ~tα with α < 1 . On long time scales, the particles transitioned to Fickian diffusion (α = 1) and their diffusivity was calculated from the slope of the MSD. Whereas the large particles agreed with predictions using the Stokes-Einstein equation and bulk zero-shear viscosity, the smaller particles diffused much faster than predicted. The relative diffusivities do not collapse onto a single curve, but rather form a continuum that varies with particle size. This indicates that the particles experience a size-dependent effective viscosity mediated by the ratio of particle diameter to characteristic length scales in the polymer solution.

  1. Scale length study in TFTR (Tokamak Fusion Test Reactor)

    SciTech Connect

    Hiroe, S.; Goldston, R.J.; Bitter, M.; Bush, C.E.; Efthimion, P.C.; Grek, B.; Johnson, D.W.; Murakami, M.; Schivell, J.; Towner, H.H.

    1988-12-01

    The scale lengths of the electron density (L/sub n//sub e/), temperature (L/sub T//sub e/), and pressure (L/sub p//sub e/) gradients were investigated during the 1985 operating period of the Tokamak Fusion Test Reactor (TFTR) for gas-fueled plasmas with neutral beam injection and movable limiter. Although the global energy confinement time degrades as the heating power increases or the plasma current decreases, the radial profiles of the scale lengths (L/sub T//sub e/ and L/sup p//sub e/) remain unchanged. Especially, the electron pressure profile is constrained not to change. This trend appears to hold over a fairly wide range of TFTR operational regimes. The radial profiles of L/sub n//sub e/ and /eta//sub e/ (= L/sub n//sub e//L/sub T//sub e/) also appear to remain unchanged, although the uncertainties of the experimental data for these quantities are greater than those for L/sub T//sub e/ and L/sub p//sub e/. The experimental parameters are used to evaluate theoretical predictions of the electron thermal diffusivity, and the results are compared with the empirical thermal diffusivity. 34 refs., 18 figs., 2 tabs.

  2. A Two-length Scale Turbulence Model for Single-phase Multi-fluid Mixing

    SciTech Connect

    Schwarzkopf, J. D.; Livescu, D.; Baltzer, J. R.; Gore, R. A.; Ristorcelli, J. R.

    2015-09-08

    A two-length scale, second moment turbulence model (Reynolds averaged Navier-Stokes, RANS) is proposed to capture a wide variety of single-phase flows, spanning from incompressible flows with single fluids and mixtures of different density fluids (variable density flows) to flows over shock waves. The two-length scale model was developed to address an inconsistency present in the single-length scale models, e.g. the inability to match both variable density homogeneous Rayleigh-Taylor turbulence and Rayleigh-Taylor induced turbulence, as well as the inability to match both homogeneous shear and free shear flows. The two-length scale model focuses on separating the decay and transport length scales, as the two physical processes are generally different in inhomogeneous turbulence. This allows reasonable comparisons with statistics and spreading rates over such a wide range of turbulent flows using a common set of model coefficients. The specific canonical flows considered for calibrating the model include homogeneous shear, single-phase incompressible shear driven turbulence, variable density homogeneous Rayleigh-Taylor turbulence, Rayleigh-Taylor induced turbulence, and shocked isotropic turbulence. The second moment model shows to compare reasonably well with direct numerical simulations (DNS), experiments, and theory in most cases. The model was then applied to variable density shear layer and shock tube data and shows to be in reasonable agreement with DNS and experiments. Additionally, the importance of using DNS to calibrate and assess RANS type turbulence models is highlighted.

  3. Additional Results of Ice-Accretion Scaling at SLD Conditions

    NASA Technical Reports Server (NTRS)

    Bond, Thomas H. (Technical Monitor); Anderson, David N.; Tsao, Jen-Ching

    2005-01-01

    To determine scale velocity an additional similarity parameter is needed to supplement the Ruff scaling method. A Weber number based on water droplet MVD has been included in several studies because the effect of droplet splashing on ice accretion was believed to be important, particularly for SLD conditions. In the present study, ice shapes recorded at Appendix-C conditions and recent results at SLD conditions are reviewed to show that droplet diameter cannot be important to main ice shape, and for low airspeeds splashing does not appear to affect SLD ice shapes. Evidence is presented to show that while a supplementary similarity parameter probably has the form of a Weber number, it must be based on a length proportional to model size rather than MVD. Scaling comparisons were made between SLD reference conditions and Appendix-C scale conditions using this Weber number. Scale-to-reference model size ratios were 1:1.7 and 1:3.4. The reference tests used a 91-cm-chord NACA 0012 model with a velocity of approximately 50 m/s and an MVD of 160 m. Freezing fractions of 0.3, 0.4, and 0.5 were included in the study.

  4. Minimal length and small scale structure of spacetime

    NASA Astrophysics Data System (ADS)

    Kothawala, Dawood

    2013-11-01

    Many generic arguments support the existence of a minimum spacetime interval L0. Such a “zero-point” length can be naturally introduced in a locally Lorentz invariant manner via Synge’s world function biscalar Ω(p,P) which measures squared geodesic interval between spacetime events p and P. I show that there exists a nonlocal deformation of spacetime geometry given by a disformal coupling of metric to the biscalar Ω(p,P), which yields a geodesic interval of L0 in the limit p→P. Locality is recovered when Ω(p,P)≫L02/2. I discuss several conceptual implications of the resultant small-scale structure of spacetime for QFT propagators as well as spacetime singularities.

  5. Hybrid supramolecular and colloidal hydrogels that bridge multiple length scales.

    PubMed

    Janeček, Emma-Rose; McKee, Jason R; Tan, Cindy S Y; Nykänen, Antti; Kettunen, Marjo; Laine, Janne; Ikkala, Olli; Scherman, Oren A

    2015-04-27

    Hybrid nanocomposites were constructed based on colloidal nanofibrillar hydrogels with interpenetrating supramolecular hydrogels, displaying enhanced rheological yield strain and a synergistic improvement in storage modulus. The supramolecular hydrogel consists of naphthyl-functionalized hydroxyethyl cellulose and a cationic polystyrene derivative decorated with methylviologen moieties, physically cross-linked with cucurbit[8]uril macrocyclic hosts. Fast exchange kinetics within the supramolecular system are enabled by reversible cross-linking through the binding of the naphthyl and viologen guests. The colloidal hydrogel consists of nanofibrillated cellulose that combines a mechanically strong nanofiber skeleton with a lateral fibrillar diameter of a few nanometers. The two networks interact through hydroxyethyl cellulose adsorption to the nanofibrillated cellulose surfaces. This work shows methods to bridge the length scales of molecular and colloidal hybrid hydrogels, resulting in synergy between reinforcement and dynamics.

  6. Dynamic Leidenfrost Effect: Relevant Time and Length Scales.

    PubMed

    Shirota, Minori; van Limbeek, Michiel A J; Sun, Chao; Prosperetti, Andrea; Lohse, Detlef

    2016-02-12

    When a liquid droplet impacts a hot solid surface, enough vapor may be generated under it to prevent its contact with the solid. The minimum solid temperature for this so-called Leidenfrost effect to occur is termed the Leidenfrost temperature, or the dynamic Leidenfrost temperature when the droplet velocity is non-negligible. We observe the wetting or drying and the levitation dynamics of the droplet impacting on an (isothermal) smooth sapphire surface using high-speed total internal reflection imaging, which enables us to observe the droplet base up to about 100 nm above the substrate surface. By this method we are able to reveal the processes responsible for the transitional regime between the fully wetting and the fully levitated droplet as the solid temperature increases, thus shedding light on the characteristic time and length scales setting the dynamic Leidenfrost temperature for droplet impact on an isothermal substrate. PMID:26918994

  7. Hybrid Supramolecular and Colloidal Hydrogels that Bridge Multiple Length Scales**

    PubMed Central

    Janeček, Emma-Rose; McKee, Jason R; Tan, Cindy S Y; Nykänen, Antti; Kettunen, Marjo; Laine, Janne; Ikkala, Olli; Scherman, Oren A

    2015-01-01

    Hybrid nanocomposites were constructed based on colloidal nanofibrillar hydrogels with interpenetrating supramolecular hydrogels, displaying enhanced rheological yield strain and a synergistic improvement in storage modulus. The supramolecular hydrogel consists of naphthyl-functionalized hydroxyethyl cellulose and a cationic polystyrene derivative decorated with methylviologen moieties, physically cross-linked with cucurbit[8]uril macrocyclic hosts. Fast exchange kinetics within the supramolecular system are enabled by reversible cross-linking through the binding of the naphthyl and viologen guests. The colloidal hydrogel consists of nanofibrillated cellulose that combines a mechanically strong nanofiber skeleton with a lateral fibrillar diameter of a few nanometers. The two networks interact through hydroxyethyl cellulose adsorption to the nanofibrillated cellulose surfaces. This work shows methods to bridge the length scales of molecular and colloidal hybrid hydrogels, resulting in synergy between reinforcement and dynamics. PMID:25772264

  8. Channel length scaling of MoS2 MOSFETs.

    PubMed

    Liu, Han; Neal, Adam T; Ye, Peide D

    2012-10-23

    In this article, we investigate electrical transport properties in ultrathin body (UTB) MoS(2) two-dimensional (2D) crystals with channel lengths ranging from 2 μm down to 50 nm. We compare the short channel behavior of sets of MOSFETs with various channel thickness, and reveal the superior immunity to short channel effects of MoS(2) transistors. We observe no obvious short channel effects on the device with 100 nm channel length (L(ch)) fabricated on a 5 nm thick MoS(2) 2D crystal even when using 300 nm thick SiO(2) as gate dielectric, and has a current on/off ratio up to ~10(9). We also observe the on-current saturation at short channel devices with continuous scaling due to the carrier velocity saturation. Also, we reveal the performance limit of short channel MoS(2) transistors is dominated by the large contact resistance from the Schottky barrier between Ni and MoS(2) interface, where a fully transparent contact is needed to achieve a high-performance short channel device.

  9. Morphodynamic length scale and long term river meandering dynamics

    NASA Astrophysics Data System (ADS)

    Lanzoni, S.; Frascati, A.

    2009-12-01

    The fully nonlinear simulation of the lateral migration of meandering channels, combined with an analytical description of the linearized flow field, gives a powerful and yet computationally accessible tool to investigate short and long term evolution of alluvial rivers. In the present contribution we focus on the long term behavior of meandering rivers. This class of dynamical systems is driven by the coexistence of various intrinsically nonlinear mechanisms which determine the possible occurrence of two different morphodynamic regimes: the sub-resonant and the super-resonant regime. Investigating the full range of morphodynamic conditions, we end up with a new morphodynamic length scale associated with spatially oscillating disturbances, accounting for both curvature-forced variations in velocity and depth and alternate bars. Once normalized with this length scale, the relevant morphologic features of the simulated long term patterns (i.e. the probability density function of the local channel curvature and the geometric characteristics of the oxbow lakes) tend to collapse on two distinct behaviors, depending on the dominant morphologic regime. The long term river meandering dynamics is then investigated. The occurrence of cutoff events is a key mechanism in the dynamics of these systems. They introduce a strong source of nonlinearity in the evolution of river meandering, which strongly contributes to the formation of the complex planform patterns usually observed in nature. To detect the possible signatures of a chaotic behavior or a self-organized criticality state triggered in river meandering dynamics by the repeated occurrence of cutoffs, some robust nonlinear methodologies have been applied to both the spatial series of local curvatures and the time series of long term channel sinuosity. The temporal distribution of cutoff inter-arrivals is also investigated. The results are consistent and show that, at least from a modelling point of view, no evidence of

  10. Length scale selects directionality of droplets on vibrating pillar ratchet

    DOE PAGES

    Agapov, Rebecca L.; Boreyko, Jonathan B.; Briggs, Dayrl P.; Srijanto, Bernadeta R.; Retterer, Scott T.; Collier, C. Patrick; Lavrik, Nickolay V.

    2014-09-22

    Directional control of droplet motion at room temperature is of interest for applications such as microfluidic devices, self-cleaning coatings, and directional adhesives. Here, arrays of tilted pillars ranging in height from the nanoscale to the microscale are used as structural ratchets to directionally transport water at room temperature. Water droplets deposited on vibrating chips with a nanostructured ratchet move preferentially in the direction of the feature tilt while the opposite directionality is observed in the case of microstructured ratchets. This remarkable switch in directionality is consistent with changes in the contact angle hysteresis. To glean further insights into the lengthmore » scale dependent asymmetric contact angle hysteresis, the contact lines formed by a nonvolatile room temperature ionic liquid placed onto the tilted pillar arrays were visualized and analyzed in situ in a scanning electron microscope. As a result, the ability to tune droplet directionality by merely changing the length scale of surface features all etched at the same tilt angle would be a versatile tool for manipulating multiphase flows and for selecting droplet directionality in other lap-on-chip applications.« less

  11. Modelling Time and Length Scales of Scour Around a Pipeline

    NASA Astrophysics Data System (ADS)

    Smith, H. D.; Foster, D. L.

    2002-12-01

    The scour and burial of submarine objects is an area of interest for engineers, oceanographers and military personnel. Given the limited availability of field observations, there exists a need to accurately describe the hydrodynamics and sediment response around an obstacle using numerical models. In this presentation, we will compare observations of submarine pipeline scour with model predictions. The research presented here uses the computational fluid dynamics (CFD) model FLOW-3D. FLOW-3D, developed by Flow Science in Santa Fe, NM, is a 3-dimensional finite-difference model that solves the Navier-Stokes and continuity equations. Using the Volume of Fluid (VOF) technique, FLOW-3D is able to resolve fluid-fluid and fluid-air interfaces. The FAVOR technique allows for complex geometry to be resolved with rectangular grids. FLOW-3D uses a bulk transport method to describe sediment transport and feedback to the hydrodynamic solver is accomplished by morphology evolution and fluid viscosity due to sediment suspension. Previous investigations by the authors have shown FLOW-3D to well-predict the hydrodynamics around five static scoured bed profiles and a stationary pipeline (``Modelling of Flow Around a Cylinder Over a Scoured Bed,'' submit to Journal of Waterway, Port, Coastal, and Ocean Engineering). Following experiments performed by Mao (1986, Dissertation, Technical University of Denmark), we will be performing model-data comparisons of length and time scales for scour around a pipeline. Preliminary investigations with LES and k-ɛ closure schemes have shown that the model predicts shorter time scales in scour hole development than that observed by Mao. Predicted time and length scales of scour hole development are shown to be a function of turbulence closure scheme, grain size, and hydrodynamic forcing. Subsequent investigations consider variable wave-current flow regimes and object burial. This investigation will allow us to identify different regimes for the

  12. Characteristic length scales of spatial models in ecology via fluctuation analysis

    PubMed Central

    Keeling, M. J.; Mezić, I.; Hendry, R. J.; McGlade, J.; Rand, D. A.

    1997-01-01

    A technique of fluctuation analysis is introduced for the identification of characteristic length scales in spatial models, with similarities to the recently introduced methods using correlations. The identified length scale provides the optimal size to extract non-trivial large-scale behaviour in such models. The method is demonstrated for three biological models: genetic selection, plant competition and a complex marine system; the first two are coupled map lattices and the last one is a cellular automaton. These cover the three possibilities for asymptotic (long time) dynamics: fixation (the system converges to a fixed point); statistical fixation (the spatial statistics converge to fixed values); and complex statistical structure (the statistics do not converge to fixed values). The technique is shown to have an additional use in the identification of aggregation or dispersal at various scales. The method is rigorously justifiable in the cases when the system under analysis satisfies the FKG (Fortuin-Kasteleyn-Ginibre) property and has a fast decay of correlations. We also discuss the connection between the fluctuation analysis length scale and hydrodynamic limits methods to derive large scale equations for ecological models.

  13. Optically controlled thermal management on the nanometer length scale

    NASA Astrophysics Data System (ADS)

    Garwe, F.; Bauerschäfer, U.; Csaki, A.; Steinbrück, A.; Ritter, K.; Bochmann, A.; Bergmann, J.; Weise, A.; Akimov, D.; Maubach, G.; König, K.; Hüttmann, G.; Paa, W.; Popp, J.; Fritzsche, W.

    2008-02-01

    The manipulation of polymers and biological molecules or the control of chemical reactions on a nanometer scale by means of laser pulses shows great promise for applications in modern nanotechnology, biotechnology, molecular medicine or chemistry. A controllable, parallel, highly efficient and very local heat conversion of the incident laser light into metal nanoparticles without ablation or fragmentation provides the means for a tool like a 'nanoreactor', a 'nanowelder', a 'nanocrystallizer' or a 'nanodesorber'. In this paper we explain theoretically and show experimentally the interaction of laser radiation with gold nanoparticles on a polymethylmethacrylate (PMMA) layer (one-photon excitation) by means of different laser pulse lengths, wavelengths and pulse repetition rates. To the best of our knowledge this is the first report showing the possibility of highly local (in a 40 nm range) regulated heat insertion into the nanoparticle and its surroundings without ablation of the gold nanoparticles. In an earlier paper we showed that near-infrared femtosecond irradiation can cut labeled DNA sequences in metaphase chromosomes below the diffraction-limited spot size. Now, we use gold as well as silver-enhanced gold nanoparticles on DNA (also within chromosomes) as energy coupling objects for femtosecond laser irradiation with single-and two-photon excitation. We show the results of highly localized destruction effects on DNA that occur only nearby the nanoparticles.

  14. Broadband dielectric microwave microscopy on micron length scales.

    PubMed

    Tselev, Alexander; Anlage, Steven M; Ma, Zhengkun; Melngailis, John

    2007-04-01

    We demonstrate that a near-field microwave microscope based on a transmission line resonator allows imaging in a substantially wide range of frequencies, so that the microscope properties approach those of a spatially resolved impedance analyzer. In the case of an electric probe, the broadband imaging can be used in a direct fashion to separate contributions from capacitive and resistive properties of a sample at length scales on the order of one micron. Using a microwave near-field microscope based on a transmission line resonator we imaged the local dielectric properties of a focused ion beam milled structure on a high-dielectric-constant Ba(0.6)Sr(0.4)TiO(3) thin film in the frequency range from 1.3 to 17.4 GHz. The electrostatic approximation breaks down already at frequencies above approximately 10 GHz for the probe geometry used, and a full-wave analysis is necessary to obtain qualitative information from the images.

  15. Scale Length of Mantle Heterogeneities: Helium Diffusion Constraints

    NASA Astrophysics Data System (ADS)

    Hart, S.; Kurz, M.; Wang, Z.

    2007-12-01

    will be >20 Ra. In essence, slabs may lose their He signature by diffusion, but it will remain recorded in the surrounding mantle; i.e. veins may run but they can't hide! For both enriched and depleted upper mantle slabs, sampled along a spreading ridge, the 3/4He variability on 10-20 km scale lengths would be easily observed; even massive along-axis melt mixing (50-100 km) would not hide these signatures. We have evaluated 3 extant ridge-crest data sets in this context (MAR 0-47S; EPR 19-23S; SWIR 16- 24E), with a view to defining scale-lengths of He isotope variability. The average 3/4He variability for these 3 areas is 0.47, 0.19 and 0.21 Ra (±1 sigma); a well-sampled sub-area on the MAR (25.7-26.5S) is 0.13 Ra. There is a monotonic variation along the SWIR, from 6.6 to 7.3 Ra; variability about a best fit line is 0.09 Ra (maximum deviation is only 0.20 Ra). At the smallest scale, a single 20 km EPR flow field shows similar variability (0.29 Ra) to the above examples. Since these ridges range from slow to very fast-spreading, the variability in size of along- axis magma chambers will lead inevitably to various scales of melt averaging. We conclude that these ridge areas are not sampling mantle that contains enriched veins or recycled oceanic crust slabs of any significant size. This is especially clear for the 500 km domain on the SWIR, where very small He variability is observed, superimposed on a large scale He gradient. In particular, the view of the upper mantle as a ubiquitous mixture of veins and depleted matrix, with MORB always representing an averaging of this mixture, appears untenable.

  16. A Two-length Scale Turbulence Model for Single-phase Multi-fluid Mixing

    DOE PAGES

    Schwarzkopf, J. D.; Livescu, D.; Baltzer, J. R.; Gore, R. A.; Ristorcelli, J. R.

    2015-09-08

    A two-length scale, second moment turbulence model (Reynolds averaged Navier-Stokes, RANS) is proposed to capture a wide variety of single-phase flows, spanning from incompressible flows with single fluids and mixtures of different density fluids (variable density flows) to flows over shock waves. The two-length scale model was developed to address an inconsistency present in the single-length scale models, e.g. the inability to match both variable density homogeneous Rayleigh-Taylor turbulence and Rayleigh-Taylor induced turbulence, as well as the inability to match both homogeneous shear and free shear flows. The two-length scale model focuses on separating the decay and transport length scales,more » as the two physical processes are generally different in inhomogeneous turbulence. This allows reasonable comparisons with statistics and spreading rates over such a wide range of turbulent flows using a common set of model coefficients. The specific canonical flows considered for calibrating the model include homogeneous shear, single-phase incompressible shear driven turbulence, variable density homogeneous Rayleigh-Taylor turbulence, Rayleigh-Taylor induced turbulence, and shocked isotropic turbulence. The second moment model shows to compare reasonably well with direct numerical simulations (DNS), experiments, and theory in most cases. The model was then applied to variable density shear layer and shock tube data and shows to be in reasonable agreement with DNS and experiments. Additionally, the importance of using DNS to calibrate and assess RANS type turbulence models is highlighted.« less

  17. Length scale of Leidenfrost ratchet switches droplet directionality

    NASA Astrophysics Data System (ADS)

    Agapov, Rebecca L.; Boreyko, Jonathan B.; Briggs, Dayrl P.; Srijanto, Bernadeta R.; Retterer, Scott T.; Collier, C. Patrick; Lavrik, Nickolay V.

    2014-07-01

    Arrays of tilted pillars with characteristic heights spanning from hundreds of nanometers to tens of micrometers were created using wafer level processing and used as Leidenfrost ratchets to control droplet directionality. Dynamic Leidenfrost droplets on the ratchets with nanoscale features were found to move in the direction of the pillar tilt while the opposite directionality was observed on the microscale ratchets. This remarkable switch in the droplet directionality can be explained by varying contributions from the two distinct mechanisms controlling droplet motion on Leidenfrost ratchets with nanoscale and microscale features. In particular, asymmetric wettability of dynamic Leidenfrost droplets upon initial impact appears to be the dominant mechanism determining their directionality on tilted nanoscale pillar arrays. By contrast, asymmetric wetting does not provide a strong enough driving force compared to the forces induced by asymmetric vapour flow on arrays of much taller tilted microscale pillars. Furthermore, asymmetric wetting plays a role only in the dynamic Leidenfrost regime, for instance when droplets repeatedly jump after their initial impact. The point of crossover between the two mechanisms coincides with the pillar heights comparable to the values of the thinnest vapor layers still capable of cushioning Leidenfrost droplets upon their initial impact. The proposed model of the length scale dependent interplay between the two mechanisms points to the previously unexplored ability to bias movement of dynamic Leidenfrost droplets and even switch their directionality.Arrays of tilted pillars with characteristic heights spanning from hundreds of nanometers to tens of micrometers were created using wafer level processing and used as Leidenfrost ratchets to control droplet directionality. Dynamic Leidenfrost droplets on the ratchets with nanoscale features were found to move in the direction of the pillar tilt while the opposite directionality was

  18. Modeling CO 2 and CO dissociation scale lengths in NEOWISE comets

    NASA Astrophysics Data System (ADS)

    Lovell, Amy J.; Kramer, Emily A.; Fernandez, Yanga R.; Bauer, James M.

    2016-10-01

    NEOWISE images of comets provide important constraints on CO and CO2 dissociation scale lengths, as well as gas production rates for these rarely-observed species. Radial profiles constructed from mid-infrared images are compared to Monte Carlo simulations to investigate extended volatile source regions. In addition, NEOWISE observations of comet 67P/Churyumov-Gerasimenko provide a link to the larger-scale behavior of the Rosetta mission target. CO2 gas production rates, as observed by NEOWISE, are consistent with those observed during the previous perihelion passage. We will present initial results of our modeling efforts on gas species in 67P and other comets.

  19. Scale-lengths and instabilities in magnetized classical and relativistic plasma fluid models

    NASA Astrophysics Data System (ADS)

    Diver, D. A.; Laing, E. W.

    2015-02-01

    The validity of the traditional plasma continuum is predicated on a hierarchy of scale-lengths, with the Debye length being considered to be effectively unresolvable in the continuum limit. In this article, we revisit the strong magnetic field case in which the Larmor radius is comparable or smaller than the Debye length in the classical plasma, and also for a relativistic plasma. Fresh insight into the validity of the continuum assumption in each case is offered, including a fluid limit on the Alfvén speed that may impose restrictions on the validity of magnetohydrodynamics (MHD) in some solar and fusion contexts. Additional implications concerning the role of the firehose instability are also explored.

  20. Inlet Turbulence and Length Scale Measurements in a Large Scale Transonic Turbine Cascade

    NASA Technical Reports Server (NTRS)

    Thurman, Douglas; Flegel, Ashlie; Giel, Paul

    2014-01-01

    Constant temperature hotwire anemometry data were acquired to determine the inlet turbulence conditions of a transonic turbine blade linear cascade. Flow conditions and angles were investigated that corresponded to the take-off and cruise conditions of the Variable Speed Power Turbine (VSPT) project and to an Energy Efficient Engine (EEE) scaled rotor blade tip section. Mean and turbulent flowfield measurements including intensity, length scale, turbulence decay, and power spectra were determined for high and low turbulence intensity flows at various Reynolds numbers and spanwise locations. The experimental data will be useful for establishing the inlet boundary conditions needed to validate turbulence models in CFD codes.

  1. Numerical analysis of scalar dissipation length-scales and their scaling properties

    NASA Astrophysics Data System (ADS)

    Vaishnavi, Pankaj; Kronenburg, Andreas

    2006-11-01

    Scalar dissipation rate, χ, is fundamental to the description of scalar-mixing in turbulent non-premixed combustion. Most contributions to the statistics for χ come from the finest turbulent mixing-scales and thus its adequate characterisation requires good resolution. Reliable χ-measurement is complicated by the trade-off between higher resolution and greater signal-to-noise ratio. Thus, the present numerical study utilises the error-free mixture fraction, Z, and fluid mechanical data from the turbulent reacting jet DNS of Pantano (2004). The aim is to quantify the resolution requirements for χ-measurement in terms of easily measurable properties of the flow like the integral-scale Reynolds number, Reδ, using spectral and spatial-filtering [cf. Barlow and Karpetis (2005)] analyses. Analysis of the 1-D cross-stream dissipation spectra enables the estimation of the dissipation length scales. It is shown that these spectrally-computed scales follow the expected Kolmogorov scaling with Reδ-0.75 . The work also involves local smoothening of the instantaneous χ-field over a non-overlapping spatial-interval (filter-width, wf), to study the smoothened χ-value as a function of wf, as wf is extrapolated to the smallest scale of interest. The dissipation length-scales thus captured show a stringent Reδ-1 scaling, compared to the usual Kolmogorov-type. This concurs with the criterion of 'resolution adequacy' of the DNS, as set out by Sreenivasan (2004) using the theory of multi-fractals.

  2. Proton conduction in exchange membranes across multiple length scales.

    PubMed

    Jorn, Ryan; Savage, John; Voth, Gregory A

    2012-11-20

    Concerns over global climate change associated with fossil-fuel consumption continue to drive the development of electrochemical alternatives for energy technology. Proton exchange fuel cells are a particularly promising technology for stationary power generation, mobile electronics, and hybrid engines in automobiles. For these devices to work efficiently, direct electrical contacts between the anode and cathode must be avoided; hence, the separator material must be electronically insulating but highly proton conductive. As a result, researchers have examined a variety of polymer electrolyte materials for use as membranes in these systems. In the optimization of the membrane, researchers are seeking high proton conductivity, low electronic conduction, and mechanical stability with the inclusion of water in the polymer matrix. A considerable number of potential polymer backbone and side chain combinations have been synthesized to meet these requirements, and computational studies can assist in the challenge of designing the next generation of technologically relevant membranes. Such studies can also be integrated in a feedback loop with experiment to improve fuel cell performance. However, to accurately simulate the currently favored class of membranes, perfluorosulfonic acid containing moieties, several difficulties must be addressed including a proper treatment of the proton-hopping mechanism through the membrane and the formation of nanophase-separated water networks. We discuss our recent efforts to address these difficulties using methods that push the limits of computer simulation and expand on previous theoretical developments. We describe recent advances in the multistate empirical valence bond (MS-EVB) method that can probe proton diffusion at the nanometer-length scale and accurately model the so-called Grotthuss shuttling mechanism for proton diffusion in water. Using both classical molecular dynamics and coarse-grained descriptions that replace atomistic

  3. Proton conduction in exchange membranes across multiple length scales.

    PubMed

    Jorn, Ryan; Savage, John; Voth, Gregory A

    2012-11-20

    Concerns over global climate change associated with fossil-fuel consumption continue to drive the development of electrochemical alternatives for energy technology. Proton exchange fuel cells are a particularly promising technology for stationary power generation, mobile electronics, and hybrid engines in automobiles. For these devices to work efficiently, direct electrical contacts between the anode and cathode must be avoided; hence, the separator material must be electronically insulating but highly proton conductive. As a result, researchers have examined a variety of polymer electrolyte materials for use as membranes in these systems. In the optimization of the membrane, researchers are seeking high proton conductivity, low electronic conduction, and mechanical stability with the inclusion of water in the polymer matrix. A considerable number of potential polymer backbone and side chain combinations have been synthesized to meet these requirements, and computational studies can assist in the challenge of designing the next generation of technologically relevant membranes. Such studies can also be integrated in a feedback loop with experiment to improve fuel cell performance. However, to accurately simulate the currently favored class of membranes, perfluorosulfonic acid containing moieties, several difficulties must be addressed including a proper treatment of the proton-hopping mechanism through the membrane and the formation of nanophase-separated water networks. We discuss our recent efforts to address these difficulties using methods that push the limits of computer simulation and expand on previous theoretical developments. We describe recent advances in the multistate empirical valence bond (MS-EVB) method that can probe proton diffusion at the nanometer-length scale and accurately model the so-called Grotthuss shuttling mechanism for proton diffusion in water. Using both classical molecular dynamics and coarse-grained descriptions that replace atomistic

  4. Recognition and assembly at multiple length-scales

    NASA Astrophysics Data System (ADS)

    Olmsted, Brian Keith

    contours to study how symmetry and packing originates at the micron length-scale. Although much is known about assembly at the molecular level for symmetry and packing, the assembly of anisotropic particles at longer length scales, which involve different interactive forces, has not been studied. This work concludes by performing preliminary work in elucidating the general behavior towards symmetry and packing in two-dimensions of micron-sized particles by using gravitational gradients and dielectrophoresis.

  5. Finite-size scaling for the glass transition: The role of a static length scale

    NASA Astrophysics Data System (ADS)

    Karmakar, Smarajit; Procaccia, Itamar

    2012-12-01

    Over the past decade, computer simulations have had an increasing role in shedding light on difficult statistical physical phenomena, and in particular on the ubiquitous problem of the glass transition. Here in a wide variety of materials the viscosity of a supercooled liquid increases by many orders of magnitude upon decreasing the temperature over a modest range. A natural concern in these computer simulations is the very small size of the simulated systems compared to experimental ones, raising the issue of how to assess the thermodynamic limit. Here we turn this limitation to our advantage by performing finite size scaling on the system size dependence of the relaxation time for supercooled liquids to emphasize the importance of a growing static length scale in the theory of glass transition. We demonstrate that the static length scale that was discovered by us in Physica A0378-437110.1016/j.physa.2011.11.020 391, 1001 (2012) fits the bill extremely well, allowing us to provide a finite-size scaling theory for the α-relaxation time of the glass transition, including predictions for the thermodynamic limit based on simulations in small systems.

  6. Finite-size scaling for the glass transition: the role of a static length scale.

    PubMed

    Karmakar, Smarajit; Procaccia, Itamar

    2012-12-01

    Over the past decade, computer simulations have had an increasing role in shedding light on difficult statistical physical phenomena, and in particular on the ubiquitous problem of the glass transition. Here in a wide variety of materials the viscosity of a supercooled liquid increases by many orders of magnitude upon decreasing the temperature over a modest range. A natural concern in these computer simulations is the very small size of the simulated systems compared to experimental ones, raising the issue of how to assess the thermodynamic limit. Here we turn this limitation to our advantage by performing finite size scaling on the system size dependence of the relaxation time for supercooled liquids to emphasize the importance of a growing static length scale in the theory of glass transition. We demonstrate that the static length scale that was discovered by us in Physica A 391, 1001 (2012) fits the bill extremely well, allowing us to provide a finite-size scaling theory for the α-relaxation time of the glass transition, including predictions for the thermodynamic limit based on simulations in small systems. PMID:23367953

  7. Chain length scaling of protein folding time: Beta sheet structures

    NASA Astrophysics Data System (ADS)

    Dimitrievski, K.; Kasemo, B.; Zhdanov, V. P.

    2000-07-01

    We present comprehensive 3D lattice Monte Carlo simulations of the folding kinetics of two-turn antiparallel β sheets. The model employed takes into account isotropic nonspecific interactions as in previous flexible heteropolymer models and also orientation-dependent monomer-monomer interactions, mimicking the formation of hydrogen bonds and chain rigidity. The chain length is varied from N=15 to 33. For each chain length, we calculate the fastest folding temperature, Tfast, folding temperature, Tfold, and glass-transition temperature, Tg. The time-averaged occupation probability of the native state is found to be nearly independent of N at all temperatures. The dependence of Tfast and Tfold on N is accordingly relatively weak. The temperature interval where the folding is fast rapidly decreases with increasing N. For the chain lengths chosen, Tfold slightly exceeds Tg. The dependence of the folding time τf on N is well fitted by using the power law, τf∝Nλ. The exponent λ is found to depend on temperature and on the distribution of nonspecific interactions in the chain. In particular, λ=2.7-4.0 at T=Tfast and 5.2 at T slightly below Tfold. Evaluating τf in real units at T near Tfold yields physically reasonable results.

  8. Direct observation of electron propagation and dielectric screening on the atomic length scale.

    PubMed

    Neppl, S; Ernstorfer, R; Cavalieri, A L; Lemell, C; Wachter, G; Magerl, E; Bothschafter, E M; Jobst, M; Hofstetter, M; Kleineberg, U; Barth, J V; Menzel, D; Burgdörfer, J; Feulner, P; Krausz, F; Kienberger, R

    2015-01-15

    The propagation and transport of electrons in crystals is a fundamental process pertaining to the functioning of most electronic devices. Microscopic theories describe this phenomenon as being based on the motion of Bloch wave packets. These wave packets are superpositions of individual Bloch states with the group velocity determined by the dispersion of the electronic band structure near the central wavevector in momentum space. This concept has been verified experimentally in artificial superlattices by the observation of Bloch oscillations--periodic oscillations of electrons in real and momentum space. Here we present a direct observation of electron wave packet motion in a real-space and real-time experiment, on length and time scales shorter than the Bloch oscillation amplitude and period. We show that attosecond metrology (1 as = 10(-18) seconds) now enables quantitative insight into weakly disturbed electron wave packet propagation on the atomic length scale without being hampered by scattering effects, which inevitably occur over macroscopic propagation length scales. We use sub-femtosecond (less than 10(-15) seconds) extreme-ultraviolet light pulses to launch photoelectron wave packets inside a tungsten crystal that is covered by magnesium films of varied, well-defined thicknesses of a few ångströms. Probing the moment of arrival of the wave packets at the surface with attosecond precision reveals free-electron-like, ballistic propagation behaviour inside the magnesium adlayer--constituting the semi-classical limit of Bloch wave packet motion. Real-time access to electron transport through atomic layers and interfaces promises unprecedented insight into phenomena that may enable the scaling of electronic and photonic circuits to atomic dimensions. In addition, this experiment allows us to determine the penetration depth of electrical fields at optical frequencies at solid interfaces on the atomic scale. PMID:25592539

  9. Length scales in glass-forming liquids and related systems: a review

    NASA Astrophysics Data System (ADS)

    Karmakar, Smarajit; Dasgupta, Chandan; Sastry, Srikanth

    2016-01-01

    The central problem in the study of glass-forming liquids and other glassy systems is the understanding of the complex structural relaxation and rapid growth of relaxation times seen on approaching the glass transition. A central conceptual question is whether one can identify one or more growing length scale(s) associated with this behavior. Given the diversity of molecular glass-formers and a vast body of experimental, computational and theoretical work addressing glassy behavior, a number of ideas and observations pertaining to growing length scales have been presented over the past few decades, but there is as yet no consensus view on this question. In this review, we will summarize the salient results and the state of our understanding of length scales associated with dynamical slow down. After a review of slow dynamics and the glass transition, pertinent theories of the glass transition will be summarized and a survey of ideas relating to length scales in glassy systems will be presented. A number of studies have focused on the emergence of preferred packing arrangements and discussed their role in glassy dynamics. More recently, a central object of attention has been the study of spatially correlated, heterogeneous dynamics and the associated length scale, studied in computer simulations and theoretical analysis such as inhomogeneous mode coupling theory. A number of static length scales have been proposed and studied recently, such as the mosaic length scale discussed in the random first-order transition theory and the related point-to-set correlation length. We will discuss these, elaborating on key results, along with a critical appraisal of the state of the art. Finally we will discuss length scales in driven soft matter, granular fluids and amorphous solids, and give a brief description of length scales in aging systems. Possible relations of these length scales with those in glass-forming liquids will be discussed.

  10. Length scales in glass-forming liquids and related systems: a review.

    PubMed

    Karmakar, Smarajit; Dasgupta, Chandan; Sastry, Srikanth

    2016-01-01

    The central problem in the study of glass-forming liquids and other glassy systems is the understanding of the complex structural relaxation and rapid growth of relaxation times seen on approaching the glass transition. A central conceptual question is whether one can identify one or more growing length scale(s) associated with this behavior. Given the diversity of molecular glass-formers and a vast body of experimental, computational and theoretical work addressing glassy behavior, a number of ideas and observations pertaining to growing length scales have been presented over the past few decades, but there is as yet no consensus view on this question. In this review, we will summarize the salient results and the state of our understanding of length scales associated with dynamical slow down. After a review of slow dynamics and the glass transition, pertinent theories of the glass transition will be summarized and a survey of ideas relating to length scales in glassy systems will be presented. A number of studies have focused on the emergence of preferred packing arrangements and discussed their role in glassy dynamics. More recently, a central object of attention has been the study of spatially correlated, heterogeneous dynamics and the associated length scale, studied in computer simulations and theoretical analysis such as inhomogeneous mode coupling theory. A number of static length scales have been proposed and studied recently, such as the mosaic length scale discussed in the random first-order transition theory and the related point-to-set correlation length. We will discuss these, elaborating on key results, along with a critical appraisal of the state of the art. Finally we will discuss length scales in driven soft matter, granular fluids and amorphous solids, and give a brief description of length scales in aging systems. Possible relations of these length scales with those in glass-forming liquids will be discussed.

  11. Length Scale Correlations of Cellular Microstructures in Directionally Solidified Binary System

    SciTech Connect

    Yunxue Shen

    2002-08-01

    In a cellular array, a range of primary spacing is found to be stable under given growth conditions. Since a strong coupling of solute field exists between the neighboring cells, primary spacing variation should also influence other microstructure features such as cell shape and cell length. The existence of multiple solutions is examined in this study both theoretically as well as experimentally. A theoretical model is developed that identifies and relates four important microstructural lengths, which are found to be primary spacing, tip radius, cell width and cell length. This general microstructural relationship is shown to be valid for different cells in an array as well as for other cellular patterns obtained under different growth conditions. The unique feature of the model is that the microstructure correlation does not depend on composition or growth conditions since these variables scale microstructural lengths to satisfy the relationship obtained in this study. Detailed directional solidification experimental studies have been carried out in the succinonitrile-salol system to characterize and measure these four length scales. Besides the validation of the model, experimental results showed additional scaling laws to be present. In the regime where only a cellular structure is formed, the shape of the cell, the cell tip radius and the length of the cell are all found to scale individually with the local primary spacing. The presence of multiple solutions of primary spacing is also shown to influence the cell-dendrite transition that is controlled not only by the processing variables (growth velocity, thermal gradient and composition) but also by the local cell spacing. The cell-dendrite transition was found not to be sharp, but occurred over a range of processing conditions. Two critical conditions have been identified such that only cells are present below lower critics condition, and only dendrites are formed above the upper critics condition. Between

  12. Length Scale Correlations of Cellular Microstructures in Directionally Solidified Binary System

    SciTech Connect

    Yunxue Shen

    2002-06-27

    In a cellular array, a range of primary spacing is found to be stable under given growth conditions. Since a strong coupling of solute field exists between the neighboring cells, primary spacing variation should also influence other microstructure features such as cell shape and cell length. The existence of multiple solutions is examined in this study both theoretically as well as experimentally. A theoretical model is developed that identifies and relates four important microstructural lengths, which are found to be primary spacing, tip radius, cell width and cell length. This general microstructural relationship is shown to be valid for different cells in an array as well as for other cellular patterns obtained under different growth conditions. The unique feature of the model is that the microstructure correlation does not depend on composition or growth conditions since these variables scale microstructural lengths to satisfy the relationship obtained in this study. Detailed directional solidification experimental studies have been carried out in the succinonitrile-salol system to characterize and measure these four length scales. Besides the validation of the model, experimental results showed additional scaling laws to be present. In the regime where only a cellular structure is formed, the shape of the cell, the cell tip radius and the length of the cell are all found to scale individually with the local primary spacing. The presence of multiple solutions of primary spacing is also shown to influence the cell-dendrite transition that is controlled not only by the processing variables (growth velocity, thermal gradient and composition) but also by the local cell spacing. The cell-dendrite transition was found not to be sharp, but occurred over a range of processing conditions. Two critical conditions have been identified such that only cells are present below lower critics condition, and only dendrites are formed above the upper critics condition. Between

  13. SQUID magnetometry from nanometer to centimeter length scales

    SciTech Connect

    Hatridge, Michael J.

    2010-06-01

    The development of Superconducting QUantum Interference Device (SQUID)-based magnetometer for two applications, in vivo prepolarized, ultra-low field MRI of humans and dispersive readout of SQUIDs for micro- and nano-scale magnetometery, are the focus of this thesis.

  14. Length scale of a chaotic element in Rayleigh-Bénard convection.

    PubMed

    Karimi, A; Paul, M R

    2012-12-01

    We describe an approach to quantify the length scale of a chaotic element of a Rayleigh-Bénard convection layer exhibiting spatiotemporal chaos. The length scale of a chaotic element is determined by simultaneously evolving the dynamics of two convection layers with a unidirectional coupling that involves only the time-varying values of the fluid velocity and temperature on the lateral boundaries of the domain. In our results we numerically simulate the full Boussinesq equations for the precise conditions of experiment. By varying the size of the boundary used for the coupling we identify a length scale that describes the size of a chaotic element. The length scale of the chaotic element is of the same order of magnitude, and exhibits similar trends, as the natural chaotic length scale that is based upon the fractal dimension.

  15. Application of nonlocal models to nano beams. Part I: Axial length scale effect.

    PubMed

    Kim, Jun-Sik

    2014-10-01

    Applicability of nonlocal models to nano-beams is discussed in terms of physical implications via the similarity between a nonlocal Euler-Bernoulli (EB) beam theory and a classical Rankine-Timoshenko (RT) beam theory. The nonlocal EB beam model, Eringen's model, is briefly reviewed and the classical RT beam theory is recast by the primary variables of the EB model. A careful comparison of these two models reveals that the scale parameter used to the Eringen's model has a strike resemblance to the shear flexibility in the RT model. This implies that the nonlocal model employed in literature consider the axial length scale effect only. In addition, the paradox for a cantilevered nano-beam subjected to tip shear force is clearly explained by finding appropriate displacement prescribed boundary conditions. PMID:25942831

  16. Displacement–length scaling of brittle faults in ductile shear

    PubMed Central

    Grasemann, Bernhard; Exner, Ulrike; Tschegg, Cornelius

    2011-01-01

    Within a low-grade ductile shear zone, we investigated exceptionally well exposed brittle faults, which accumulated antithetic slip and rotated into the shearing direction. The foliation planes of the mylonitic host rock intersect the faults approximately at their centre and exhibit ductile reverse drag. Three types of brittle faults can be distinguished: (i) Faults developing on pre-existing K-feldspar/mica veins that are oblique to the shear direction. These faults have triclinic flanking structures. (ii) Wing cracks opening as mode I fractures at the tips of the triclinic flanking structures, perpendicular to the shear direction. These cracks are reactivated as faults with antithetic shear, extend from the parent K-feldspar/mica veins and form a complex linked flanking structure system. (iii) Joints forming perpendicular to the shearing direction are deformed to form monoclinic flanking structures. Triclinic and monoclinic flanking structures record elliptical displacement–distance profiles with steep displacement gradients at the fault tips by ductile flow in the host rocks, resulting in reverse drag of the foliation planes. These structures record one of the greatest maximum displacement/length ratios reported from natural fault structures. These exceptionally high ratios can be explained by localized antithetic displacement along brittle slip surfaces, which did not propagate during their rotation during surrounding ductile flow. PMID:26806996

  17. Failure analysis of fuel cell electrodes using three-dimensional multi-length scale X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Pokhrel, A.; El Hannach, M.; Orfino, F. P.; Dutta, M.; Kjeang, E.

    2016-10-01

    X-ray computed tomography (XCT), a non-destructive technique, is proposed for three-dimensional, multi-length scale characterization of complex failure modes in fuel cell electrodes. Comparative tomography data sets are acquired for a conditioned beginning of life (BOL) and a degraded end of life (EOL) membrane electrode assembly subjected to cathode degradation by voltage cycling. Micro length scale analysis shows a five-fold increase in crack size and 57% thickness reduction in the EOL cathode catalyst layer, indicating widespread action of carbon corrosion. Complementary nano length scale analysis shows a significant reduction in porosity, increased pore size, and dramatically reduced effective diffusivity within the remaining porous structure of the catalyst layer at EOL. Collapsing of the structure is evident from the combination of thinning and reduced porosity, as uniquely determined by the multi-length scale approach. Additionally, a novel image processing based technique developed for nano scale segregation of pore, ionomer, and Pt/C dominated voxels shows an increase in ionomer volume fraction, Pt/C agglomerates, and severe carbon corrosion at the catalyst layer/membrane interface at EOL. In summary, XCT based multi-length scale analysis enables detailed information needed for comprehensive understanding of the complex failure modes observed in fuel cell electrodes.

  18. Laser profilometry and length-scale analysis of stone tools: second series experiment results.

    PubMed

    James Stemp, W; Childs, Ben E; Vionnet, Samuel

    2010-01-01

    Based on the need to develop a method to reliably and objectively document and discriminate the use-wear on archaeological stone tools, Stemp et al. (2009) tested whether the surface roughness measured on experimentally worn stone tools used on different contact materials could be discriminated. Results of these initial experiments indicated that discrimination was possible and also determined the scales over which this discrimination occurred. In this article, we report the results of additional experiments using the same method on a second set of tools to test its reliability and reproducibility. In these experiments, four flint flakes were intensively used for 20 min on either conch shell or dry deer antler. The surface roughness or texture of the stone tools was measured by generating 2D profiles using a UBM laser profilometer. Relative lengths (RLs) calculated from the profiles were used directly as characterization parameters and subsequently compared statistically at each scale using the F-test to establish a level of confidence for the differentiation at each scale represented in the measured profiles. The mean square ratios of measurement data were used to determine whether the variation in roughness was statistically significant and to what level of confidence. The scales at which there was a high level of confidence were the ones at which the tools were differentiable. The results of these experiments confirm our previous findings that RLs, over certain scale ranges, can discriminate the stone tool surface wear profiles produced by the different contact materials.

  19. Laser profilometry and length-scale analysis of stone tools: second series experiment results.

    PubMed

    James Stemp, W; Childs, Ben E; Vionnet, Samuel

    2010-01-01

    Based on the need to develop a method to reliably and objectively document and discriminate the use-wear on archaeological stone tools, Stemp et al. (2009) tested whether the surface roughness measured on experimentally worn stone tools used on different contact materials could be discriminated. Results of these initial experiments indicated that discrimination was possible and also determined the scales over which this discrimination occurred. In this article, we report the results of additional experiments using the same method on a second set of tools to test its reliability and reproducibility. In these experiments, four flint flakes were intensively used for 20 min on either conch shell or dry deer antler. The surface roughness or texture of the stone tools was measured by generating 2D profiles using a UBM laser profilometer. Relative lengths (RLs) calculated from the profiles were used directly as characterization parameters and subsequently compared statistically at each scale using the F-test to establish a level of confidence for the differentiation at each scale represented in the measured profiles. The mean square ratios of measurement data were used to determine whether the variation in roughness was statistically significant and to what level of confidence. The scales at which there was a high level of confidence were the ones at which the tools were differentiable. The results of these experiments confirm our previous findings that RLs, over certain scale ranges, can discriminate the stone tool surface wear profiles produced by the different contact materials. PMID:20853403

  20. Identification and application of additional restriction fragment length polymorphisms at the human ornithine transcarbamylase locus.

    PubMed

    Fox, J E; Hack, A M; Fenton, W A; Rosenberg, L E

    1986-06-01

    Two additional restriction fragment length polymorphisms (RFLPs) have been identified at the human ornithine transcarbamylase (OTC) locus. Approximately 11% of women are heterozygous for an RFLP characterized by polymorphic bands at 3.7 and 3.6 kilobasepairs (kbp) observed after DNA digestion with TaqI. Twenty-nine percent of women are heterozygous for an RFLP characterized by polymorphic bands at 18.0 and 5.2 kbp observed after digestion with BamHI. Thus, in combination with the previously reported RFLPs identified using MspI, the X chromosomes in approximately 80% of women at risk for having a son with OTC deficiency are distinguishable by RFLPs at the OTC locus. Furthermore, we show that these RFLPs will be useful in families for prenatal diagnosis of OTC deficiency, carrier detection, and carrier exclusion.

  1. Macroscopic and Microscopic Capillary Length and Time Scales From Field Infiltration

    NASA Astrophysics Data System (ADS)

    White, I.; Sully, M. J.

    1987-08-01

    Estimates of characteristic times to approach steady state flow in multidimensional infiltration in the landscape depend on the magnitude and character of the capillary length scale λc and the associated capillary time scale tc. Here we derive relationships between λc and tc and readily measured field properties sorptivity S and hydraulic conductivity K or S at two supply heads. We explore the relations between λc and tc and other macroscopic and microscopic length, potential, and time scales. In addition, we show that the microscopic characteristic length λm associated with λc gives physically plausible estimates of flow-weighted mean pore dimensions. We contrast values of λc, tc, and λm for undisturbed field soils with those of repacked materials for water supply potentials close to zero. Large λm for the undisturbed surface soils are attributed to preferential flow. Data from here and elsewhere reveal no apparent trend of λc with soil texture, with most λc of the order of 100 mm. We suggest that the characteristic size of devices used to determine hydraulic properties of field soils should be greater than or equal to λc for representative measurements. The geometric mean time of approach to steady state flow when water is supplied at potentials near or greater than zero is found to be 1.7 hours. This value together with published results suggest that the time of approach to steady state flow from multidimensional cavities is of the order of 1 hour for many field situations.

  2. Radiation Damage on Multiple Length Scales in Uranium Dioxide

    NASA Astrophysics Data System (ADS)

    Gupta, Mahima

    Radiation damage in UO2 has been well studied but there exists little correlation between point defect accumulation, lattice structure changes and microstructure. This is partly because irradiated nuclear fuel is highly radioactive and its defect chemistry is extremely complicated resulting from fission of the material and consequent fission products being embedded in the fuel matrix [Olander1976]. To adequately study the evolution of defects from point defects through to microstructure features, the resulting defects have to be intentionally simplified for characterization. Ion accelerators have the unique capability of creating simple microstructure features using specific ions, without the added complication of fission and neutron activation from nuclear reactors. As an example, H+ ions have been used to create (only) a distribution of dislocations that were studied using various techniques. The ability to tune the energy or type of the ion to achieve desirable implantation depth and ideally simple microstructure renders it a lucrative instrument for this type of analysis. X-ray diffraction (XRD) studies and transmission electron microscopy (TEM) have been utilized to study extended structure changes and microstructure evolution. Ion beam irradiations create displacements and displacement networks, voids, surface fracturing, gas bubbles and several other microstructure changes to model nuclear reactor damage [Noris1972]. Using an ion accelerator, it has been possible to isolate these radiation induced defects and study their subsequent evolution with increasing dose. Insofar, since all of the phenomena caused by radiation damage originate from point defects, the elucidation of radiation effects on the atomic scale is crucial. This is rendered complicated due to aperiodic irradiation defects. This lack of periodicity renders standard approaches, such as TEM and XRD ineffective, as these methods probe average structure over tens of Angstroms. Therefore, techniques

  3. Exploring heavy fermions from macroscopic to microscopic length scales

    NASA Astrophysics Data System (ADS)

    Wirth, Steffen; Steglich, Frank

    2016-10-01

    Strongly correlated systems present fundamental challenges, especially in materials in which electronic correlations cause a strong increase of the effective mass of the charge carriers. Heavy fermion metals — intermetallic compounds of rare earth metals (such as Ce, Sm and Yb) and actinides (such as U, Np and Pu) — are prototype systems for complex and collective quantum states; they exhibit both a lattice Kondo effect and antiferromagnetic correlations. These materials show unexpected phenomena; for example, they display unconventional superconductivity (beyond Bardeen–Cooper–Schrieffer (BCS) theory) and unconventional quantum criticality (beyond the Landau framework). In this Review, we focus on systems in which Landau's Fermi-liquid theory does not apply. Heavy fermion metals and semiconductors are well suited for the study of strong electronic correlations, because the relevant energy scales (for charge carriers, magnetic excitations and lattice dynamics) are well separated from each other, allowing the exploration of concomitant physical phenomena almost independently. Thus, the study of these materials also provides valuable insight for the understanding — and tailoring — of other correlated systems.

  4. Nonsymmorphic Phononic Metamaterials: shaping waves over multiple length scales

    NASA Astrophysics Data System (ADS)

    Koh, Cheongyang; Thomas, Edwin

    2012-02-01

    The vector nature of the phonon makes rational design of phononic metamaterials challenging, despite potential in unique wave propagation behavior, such as negative refraction and hyper-lensing. While most designs to date focus on the ``meta-atom'' (building block) design, their ``spatial arrangement'' (non-locality) is equally instrumental in dispersion engineering. Here, we present a generalized design framework (DF) for PMM design, utilizing both ``global'' and ``local'' symmetry concepts. We demonstrate, utilizing specific properties of nonsymmorphic plane groups, PMMs possessing i) a low-frequency in-plane complete spectral gap (ICSG) of 102% (CSG of 88%), ii) a set of polychromatic ICSGs totaling over 100% in normalized gap size. Within the same DF, we further integrate broken symmetry states (BSS) (edge states, waveguides, etc) with designed polarization, (de)localization and group velocities. In particular, we demonstrate how these BSS may be utilized to elucidate signatures of complex polarization fields through phonon-structure interactions, leading to interesting applications in elastic-wave imaging, as well as information retrieval by probing polarization states of scattering bodies over multiple scales.

  5. A large scale membrane-binding protein conformational change that initiates at small length scales

    NASA Astrophysics Data System (ADS)

    Grandpre, Trevor; Andorf, Matthew; Chakravarthy, Srinivas; Lamb, Robert; Poor, Taylor; Landahl, Eric

    2013-03-01

    The fusion (F) protein of parainfluenza virus 5 (PIV5) is a membrane-bound, homotrimeric glycoprotein located on the surface of PIV5 viral envelopes. Upon being triggered by the receptor-binding protein (HN), F undergoes a greater than 100Å ATP-independent refolding event. This refolding event results in the insertion of a hydrophobic fusion peptide into the membrane of the target cell, followed by the desolvation and subsequent fusion event as the two membranes are brought together. Isothermal calorimetry and hydrophobic dye incorporation experiments indicate that the soluble construct of the F protein undergoes a conformational rearrangement event at around 55 deg C. We present the results of an initial Time-Resolved Small-Angle X-Ray Scattering (TR-SAXS) study of this large scale, entropically driven conformational change using a temperature jump. Although we the measured radius of gyration of this protein changes on a 110 second timescale, we find that the x-ray scattering intensity at higher angles (corresponding to smaller length scales in the protein) changes nearly an order of magnitude faster. We believe this may be a signature of entropically-driven conformational change. To whom correspondence should be addressed

  6. A New Method for Measuring River Sinuosity across Varying Length Scales

    NASA Astrophysics Data System (ADS)

    Liu, T.; Johnson, K. N.

    2015-12-01

    Sinuosity is an emergent characteristic of meandering rivers. In bedrock rivers, climate (Stark 2009) and bedrock lithology (Johnson and Finnegan 2015) likely influence sinuosity. Comparing trends in sinuosity between and along rivers with different climates, lithology, and tectonics has the potential to shed light on what controls sinuosity. However, measuring sinuosity in a meaningful way is challenging. The length scale over which sinuosity is calculated affects the measurement. For example, a river with many tight curves generates greater sinuosities with a shorter length scale, and a river with a curved valley might generate greater sinuosities with a longer length scale. Therefore, to find the distribution of sinuosity across length scales, a method is needed that can compare sinuosities at a variety of length scales. To achieve this goal, we made a tool that calculates sinuosities across many length scales along a river and derives both the maximum sinuosity and the length scale at which these maximums occur for each point on the river. Using digital elevation models (DEMs) of a number of landscapes with varying climate, lithology and uplift rate, we extracted river networks using a flow accumulation method. From this, our code works within the ArcGIS Python window. It applies a moving window to calculate sinuosity at each point along the river for a wide range of length scales. All the points' maximum sinuosities can be displayed, even if they are derived from different length scales. Because the code is run within ArcGIS, it is easy to display these sinuosity data as attributes of the original river networks. This tool opens new possibilities for tracking patterns in sinuosity along and between rivers. Our preliminary data suggests that this method will be useful for interpreting trends in sinuosity and learning about what factors influence them.

  7. Topographic Roughness of Hawaiian Volcanic Terrains: Analysis of Multiple Datasets Indicates Length Scales are Critical

    NASA Astrophysics Data System (ADS)

    Morris, A. R.; Anderson, F. S.; Mouginis-Mark, P.; Haldemann, A.; Brooks, B.; Foster, J.

    2007-12-01

    The roughness of a natural surface is often defined by the topography of the surface at scales of a few tens of meters or less. To ensure the safety of rovers and scientific instruments on Mars, these scales are of critical importance during landing site selection and rover traverse operations. Published work on terrestrial and Martian topography datasets has demonstrated that statistical values such as the Hurst exponent can be used in conjunction with related statistical measures such as RMS slope or deviation to quantify the relationship between scale-dependent roughness values and the morphology of a surface. In our detailed studies of the statistical behavior of meter-scale surface roughness on Earth, we determine that the length scales used to calculate the surface roughness affect the resulting roughness statistics and must be taken into account when analyzing planetary surface roughness. Extensive airborne Light Detection and Ranging (a-LiDAR) coverage of the summit of Kilauea volcano on the Big Island of Hawaii (1 m DEM) provides an opportunity for simulating higher resolution Martian topography data such as will be obtained from photoclinometry and stereo imaging using the HiRISE camera on MRO. In addition to the a-LiDAR data, we use high-resolution topography (2 cm DEM) generated from a tripod-mounted scanning LiDAR system (t-LiDAR). Previous authors have described techniques for calculating roughness statistics in one dimension using topographic profiles. We adapt the 1D method for use with 2D topographic datasets to generate maps of the Hurst exponent of Martian analog flows in Hawaii. Results from the surface roughness analysis suggest that the calculated RMS deviation or slope and Hurst exponent exhibit systematic variations as the length of a profile segment (in 1D studies) or size of the cell (in 2D studies) changes. These new results, combined with previously described data, indicate that the length scales used to calculate roughness statistics

  8. Plasma scale-length effects on electron energy spectra in high-irradiance laser plasmas.

    PubMed

    Culfa, O; Tallents, G J; Rossall, A K; Wagenaars, E; Ridgers, C P; Murphy, C D; Dance, R J; Gray, R J; McKenna, P; Brown, C D R; James, S F; Hoarty, D J; Booth, N; Robinson, A P L; Lancaster, K L; Pikuz, S A; Faenov, A Ya; Kampfer, T; Schulze, K S; Uschmann, I; Woolsey, N C

    2016-04-01

    An analysis of an electron spectrometer used to characterize fast electrons generated by ultraintense (10^{20}Wcm^{-2}) laser interaction with a preformed plasma of scale length measured by shadowgraphy is presented. The effects of fringing magnetic fields on the electron spectral measurements and the accuracy of density scale-length measurements are evaluated. 2D EPOCH PIC code simulations are found to be in agreement with measurements of the electron energy spectra showing that laser filamentation in plasma preformed by a prepulse is important with longer plasma scale lengths (>8 μm). PMID:27176413

  9. Rater Experience, Rating Scale Length, and Judgments of L2 Pronunciation: Revisiting Research Conventions

    ERIC Educational Resources Information Center

    Isaacs, Talia; Thomson, Ron I.

    2013-01-01

    This mixed-methods study examines the effects of rating scale length and rater experience on listeners' judgments of second-language (L2) speech. Twenty experienced and 20 novice raters, who were randomly assigned to 5-point or 9-point rating scale conditions, judged speech samples of 38 newcomers to Canada on numerical rating scales for…

  10. Bridging Length Scales to Study Self-Assembly and Self-Organization

    NASA Astrophysics Data System (ADS)

    Kaye, Bryan; Needleman, Daniel

    A variety of proteins can assemble into large polymers as an integral part of their biological function. Studying the biochemistry and biophysics of polymer formation often involves time-resolvable measurements of the amount of polymer. Non-invasive measurements of polymer can be divided into two categories: short (spectroscopy) and large (microscopy) length scale measurements. Microscopy-based estimates of polymer amount are often dependent on spatial non-uniformity of polymer, whereas spectroscopy-based estimates of polymer amount are often based on models that are difficult to test. Here we show how both large and small length scale measurements can be combined to validate the assumptions behind both measurements while incorporating both measurements to make more accurate estimates of polymer amount. We utilize this approach with two-photon microscopy and FRET to measure the amount of tubulin (monomer) in microtubules (polymer) in order to study microtubule nucleation in cell extracts. In addition, this approach may be useful to study a wide variety of polymers, including actin filaments, viruses, lipid membranes, and other protein aggregates.

  11. A Length Scale Defining Partially-Resolved Boundary-Layer Turbulence Simulations

    NASA Astrophysics Data System (ADS)

    Beare, Robert J.

    2014-04-01

    Numerical weather prediction (NWP) model forecasts at horizontal grid lengths in the range of 100 m to 1 km are now possible. Within this range of grid lengths, the convective boundary layer (CBL) is partially resolved and thus in the so-called `grey zone'. For simulations in the grey zone, numerical dissipation sources from both the advection scheme and the subgrid model are likely to be significant. Until now, these effects have not been incorporated fully into our understanding of the grey zone. In order to quantify these effects, a dissipation length scale is defined based on the second moment of the turbulent kinetic energy (TKE) spectrum. An ensemble of simulations of a CBL are performed using a large-eddy model across the grey-zone resolutions and for a range of subgrid model, advection scheme and vertical grid configurations. The dissipation length scale distinguishes the effects of the different model configurations in the grey zone. In the middle of the boundary layer, the resolved TKE is strongly controlled by the numerical dissipation. This leads to a similarity law for the resolved TKE in the grey zone using the dissipation length scale. A new definition of the grey zone emerges where the inversion depth and dissipation length scale are the same size. This contrasts with the typical definition using the horizontal grid length. At the inversion, however, the variation of the dissipation length scale with grid length is less predictable, reflecting significant challenges for modelling entrainment in the grey zone. The dissipation length scale is thus a simple diagnostic to aid both NWP and large-eddy modellers in understanding the grey zone.

  12. Additional Saturday rehabilitation improves functional independence and quality of life and reduces length of stay: a randomized controlled trial

    PubMed Central

    2013-01-01

    Background Many inpatients receive little or no rehabilitation on weekends. Our aim was to determine what effect providing additional Saturday rehabilitation during inpatient rehabilitation had on functional independence, quality of life and length of stay compared to 5 days per week of rehabilitation. Methods This was a multicenter, single-blind (assessors) randomized controlled trial with concealed allocation and 12-month follow-up conducted in two publically funded metropolitan inpatient rehabilitation facilities in Melbourne, Australia. Patients were eligible if they were adults (aged ≥18 years) admitted for rehabilitation for any orthopedic, neurological or other disabling conditions excluding those admitted for slow stream rehabilitation/geriatric evaluation and management. Participants were randomly allocated to usual care Monday to Friday rehabilitation (control) or to Monday to Saturday rehabilitation (intervention). The additional Saturday rehabilitation comprised physiotherapy and occupational therapy. The primary outcomes were functional independence (functional independence measure (FIM); measured on an 18 to 126 point scale), health-related quality of life (EQ-5D utility index; measured on a 0 to 1 scale, and EQ-5D visual analog scale; measured on a 0 to 100 scale), and patient length of stay. Outcome measures were assessed on admission, discharge (primary endpoint), and at 6 and 12 months post discharge. Results We randomly assigned 996 adults (mean (SD) age 74 (13) years) to Monday to Saturday rehabilitation (n = 496) or usual care Monday to Friday rehabilitation (n = 500). Relative to admission scores, intervention group participants had higher functional independence (mean difference (MD) 2.3, 95% confidence interval (CI) 0.5 to 4.1, P = 0.01) and health-related quality of life (MD 0.04, 95% CI 0.01 to 0.07, P = 0.009) on discharge and may have had a shorter length of stay by 2 days (95% CI 0 to 4, P = 0.1) when compared to

  13. A robust increase in the eddy length scale in the simulation of future climates

    NASA Astrophysics Data System (ADS)

    Kidston, J.; Dean, S. M.; Renwick, J. A.; Vallis, G. K.

    2010-02-01

    Output from the Coupled Model Intercomparison Phase 3 are analysed. It is shown that for the ‘A2’ business as usual scenario, every model exhibits an increase in the eddy length scale in the future compared with the simulation of 20th Century climate. The increase in length scale is on the order of 5% by the end of the 21st century, and the Southern Hemisphere exhibits a larger increase than the Northern Hemisphere. The inter-model variability in the increase in the eddy length scale is correlated with the variability in the increase in dry static stability at 700 hPa. Inspection of the NCEP/NCAR reanalysis data indicates that the eddy length scale in the Southern Hemisphere may have increased in recent decades.

  14. Kelvin Absolute Temperature Scale Identified as Length Scale and Related to de Broglie Thermal Wavelength

    NASA Astrophysics Data System (ADS)

    Sohrab, Siavash

    Thermodynamic equilibrium between matter and radiation leads to de Broglie wavelength λdβ = h /mβvrβ and frequency νdβ = k /mβvrβ of matter waves and stochastic definitions of Planck h =hk =mk <λrk > c and Boltzmann k =kk =mk <νrk > c constants, λrkνrk = c , that respectively relate to spatial (λ) and temporal (ν) aspects of vacuum fluctuations. Photon massmk =√{ hk /c3 } , amu =√{ hkc } = 1 /No , and universal gas constant Ro =No k =√{ k / hc } result in internal Uk = Nhνrk = Nmkc2 = 3 Nmkvmpk2 = 3 NkT and potential pV = uN\\vcirc / 3 = N\\ucirc / 3 = NkT energy of photon gas in Casimir vacuum such that H = TS = 4 NkT . Therefore, Kelvin absolute thermodynamic temperature scale [degree K] is identified as length scale [meter] and related to most probable wavelength and de Broglie thermal wavelength as Tβ =λmpβ =λdβ / 3 . Parallel to Wien displacement law obtained from Planck distribution, the displacement law λwS T =c2 /√{ 3} is obtained from Maxwell -Boltzmann distribution of speed of ``photon clusters''. The propagation speeds of sound waves in ideal gas versus light waves in photon gas are described in terms of vrβ in harmony with perceptions of Huygens. Newton formula for speed of long waves in canals √{ p / ρ } is modified to √{ gh } =√{ γp / ρ } in accordance with adiabatic theory of Laplace.

  15. Desert bird associations with broad-scale boundary length: Applications in avian conservation

    USGS Publications Warehouse

    Gutzwiller, K.J.; Barrow, W.C.

    2008-01-01

    1. Current understanding regarding the effects of boundaries on bird communities has originated largely from studies of forest-non-forest boundaries in mesic systems. To assess whether broad-scale boundary length can affect bird community structure in deserts, and to identify patterns and predictors of species' associations useful in avian conservation, we studied relations between birds and boundary-length variables in Chihuahuan Desert landscapes. Operationally, a boundary was the border between two adjoining land covers, and broad-scale boundary length was the total length of such borders in a large area. 2. Within 2-km radius areas, we measured six boundary-length variables. We analysed bird-boundary relations for 26 species, tested for assemblage-level patterns in species' associations with boundary-length variables, and assessed whether body size, dispersal ability and cowbird-host status were correlates of these associations. 3. The abundances or occurrences of a significant majority of species were associated with boundary-length variables, and similar numbers of species were related positively and negatively to boundary-length variables. 4. Disproportionately small numbers of species were correlated with total boundary length, land-cover boundary length and shrubland-grassland boundary length (variables responsible for large proportions of boundary length). Disproportionately large numbers of species were correlated with roadside boundary length and riparian vegetation-grassland boundary length (variables responsible for small proportions of boundary length). Roadside boundary length was associated (positively and negatively) with the most species. 5. Species' associations with boundary-length variables were not correlated with body size, dispersal ability or cowbird-host status. 6. Synthesis and applications. For the species we studied, conservationists can use the regressions we report as working models to anticipate influences of boundary-length changes

  16. Intrinsic region length scaling of heavily doped carbon nanotube p-i-n junctions

    NASA Astrophysics Data System (ADS)

    Li, Zheng; Zheng, Jiaxin; Ni, Zeyuan; Quhe, Ruge; Wang, Yangyang; Gao, Zhengxiang; Lu, Jing

    2013-07-01

    We investigated the dependence of the transport properties of heavily doped intratube single-walled carbon nanotube (SWCNT) p-i-n junctions on the length of the intrinsic region by using empirical self-consistent quantum transport simulations. When the length of the intrinsic region is scaled from a few angstroms to over 10 nanometers, the SWCNT p-i-n junction evolves from a tunneling diode with a large negative rectification and large negative differential resistance to one with a large positive rectification (like a conventional positive rectifying diode). The critical length of the intrinsic length is about 8.0 nm. Therefore, one can obtain nanoscale diodes of different performance types by changing the intrinsic region length.We investigated the dependence of the transport properties of heavily doped intratube single-walled carbon nanotube (SWCNT) p-i-n junctions on the length of the intrinsic region by using empirical self-consistent quantum transport simulations. When the length of the intrinsic region is scaled from a few angstroms to over 10 nanometers, the SWCNT p-i-n junction evolves from a tunneling diode with a large negative rectification and large negative differential resistance to one with a large positive rectification (like a conventional positive rectifying diode). The critical length of the intrinsic length is about 8.0 nm. Therefore, one can obtain nanoscale diodes of different performance types by changing the intrinsic region length. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01462b

  17. Size effects and internal length scales in the elasticity of random fiber networks

    NASA Astrophysics Data System (ADS)

    Picu, Catalin; Berkache, Kamel; Shahsavari, Ali; Ganghoffer, Jean-Francois

    Random fiber networks are the structural element of many biological and man-made materials, including connective tissue, various consumer products and packaging materials. In all cases of practical interest the scale at which the material is used and the scale of the fiber diameter or the mean segment length of the network are separated by several orders of magnitude. This precludes solving boundary value problems defined on the scale of the application while resolving every fiber in the system, and mandates the development of continuum equivalent models. To this end, we study the intrinsic geometric and mechanical length scales of the network and the size effect associated with them. We consider both Cauchy and micropolar continuum models and calibrate them based on the discrete network behavior. We develop a method to predict the characteristic length scales of the problem and the minimum size of a representative element of the network based on network structural parameters and on fiber properties.

  18. Virtual Testing of Large Composite Structures: A Multiple Length/Time-Scale Framework

    NASA Astrophysics Data System (ADS)

    Gigliotti, Luigi; Pinho, Silvestre T.

    2015-12-01

    This paper illustrates a multiple length/time-scale framework for the virtual testing of large composite structures. Such framework hinges upon a Mesh Superposition Technique (MST) for the coupling between areas of the structure modelled at different length-scales and upon an efficient solid-to-shell numerical homogenization which exploits the internal symmetries of Unit Cells (UCs). Using this framework, it is possible to minimize the areas of the structure modelled at the lowest- (and computationally demanding) scales and the computational cost required to calculate the homogenised to be used in the higher-scales subdomains of multiscale FE models, as well as to simulate the mechanical response of different parts of the structure using different solvers, depending on where they are expected to provide the most computationally efficient solution. The relevance and key-aspects of the multiple length/time-scale framework are demonstrated through the analysis of a real-sized aeronautical composite component.

  19. Characteristic length scales of the secondary relaxations in glass-forming glycerol.

    PubMed

    Gupta, S; Mamontov, E; Jalarvo, N; Stingaciu, L; Ohl, M

    2016-03-01

    We investigate the secondary relaxations and their link to the main structural relaxation in glass-forming liquids using glycerol as a model system. We analyze the incoherent neutron scattering signal dependence on the scattering momentum transfer, Q , in order to obtain the characteristic length scale for different secondary relaxations. Such a capability of neutron scattering makes it somewhat unique and highly complementary to the traditional techniques of glass physics, such as light scattering and broadband dielectric spectroscopy, which provide information on the time scale, but not the length scales, of relaxation processes. The choice of suitable neutron scattering techniques depends on the time scale of the relaxation of interest. We use neutron backscattering to identify the characteristic length scale of 0.7 Å for the faster secondary relaxation described in the framework of the mode-coupling theory (MCT). Neutron spin-echo is employed to probe the slower secondary relaxation of the excess wing type at a low temperature ( ∼ 1.13T g . The characteristic length scale for this excess wing dynamics is approximately 4.7 Å. Besides the Q -dependence, the direct coupling of neutron scattering signal to density fluctuation makes this technique indispensable for measuring the length scale of the microscopic relaxation dynamics. PMID:27021657

  20. Does Scale Length Matter? A Comparison of Nine- versus Five-Point Rating Scales for the Mini-CEX

    ERIC Educational Resources Information Center

    Cook, David A.; Beckman, Thomas J.

    2009-01-01

    Educators must often decide how many points to use in a rating scale. No studies have compared interrater reliability for different-length scales, and few have evaluated accuracy. This study sought to evaluate the interrater reliability and accuracy of mini-clinical evaluation exercise (mini-CEX) scores, comparing the traditional mini-CEX…

  1. The effects of geometry and length scale on nanomechanical properties in constrained systems

    NASA Astrophysics Data System (ADS)

    Jungk, John Michael

    2005-07-01

    The determination of mechanical properties in nanoscale geometries is becoming increasingly important as microsystem and integrated circuit technologies continue to mature. Many devices produced by these technologies are composed of materials with critical sample dimensions smaller than 100 nm. In microelectronics, this can be the thickness of a metallization or dielectric layer, while wear coatings on MEMS devices are frequently thinner than this length scale. Since structures of this type are susceptible to plasticity and fracture as a result of either contact or residual stresses, it is critical that the mechanical behavior of the individual components be well described. This thesis is directed at the development of methods for characterizing the mechanical properties in small volume systems. Using instrumented indentation techniques, typically called nanoindentation, a systematic study of the mechanical response of materials ranging from ductile metals to brittle ceramics was executed. More specifically, investigations into how single length scale approaches may be used to describe mechanical properties such as indentation hardening, ductile film delamination and strain energy release rates were performed. In addition, the acoustic energy released during the fracture of brittle ceramics was related to both stress intensity and a strain energy release rate. Finite element simulations of nanoindentation tests were performed using ABAQUS, a commercially available material modeling software program. These simulations were used to separate individual film and substrate responses from the experimentally observed film/substrate composite mechanical behavior. Finally, quasi-tribological experiments were performed to probe for transitions in friction or wear response as the local deformation varied from the nanoscale to the macroscale.

  2. A crystal plasticity analysis of length-scale dependent internal stresses with image effects

    NASA Astrophysics Data System (ADS)

    Aghababaei, Ramin; Joshi, Shailendra P.

    2012-12-01

    In this work, we present a stress functions approach to include image effects in continuum crystal plasticity arising from the long-range elastic interactions (LRI) between the GND density and free surfaces. The resulting length-scale dependent internal stresses augment those produced by the GND density variation. The formulation is applied to the case of a long, thin specimen subjected to uniform curvature. The analysis shows that under nominally uniform GND density distribution, internal stresses arise from two sources: (1) GND-GND LRI arising from the finite spatial extent of the uniform GND density field and (2) the LRI between the GND density and free surfaces appearing as image fields. A comparison with experimental results suggests that the length-scale for internal stresses, described as a correlation length-scale, should increase with decreasing specimen thickness. This observation is rationalized by associating the internal length-scale with the average slip-plane spacing, which may increase with decreasing specimen size due to paucity of dislocation sources. Finally, we also discuss the length-scale dependent image stress in terms of the Peach-Koehler force density proposed by Gurtin (2002).

  3. Dramatically growing shear rigidity length scale in the supercooled glass former NiZr2

    NASA Astrophysics Data System (ADS)

    Weingartner, Nicholas B.; Soklaski, Ryan; Kelton, K. F.; Nussinov, Zohar

    2016-06-01

    Finding a suitably growing length scale that increases in tandem with the immense viscous slowdown of supercooled liquids is an open problem associated with the glass transition. Here, we define and demonstrate the existence of one such length scale which may be experimentally verifiable. This is the length scale over which external shear perturbations appreciably penetrate into a liquid as the glass transition is approached. We provide simulation based evidence of its existence, and its growth by at least an order of magnitude, by using molecular dynamics simulations of NiZr2, a good fragile glass former. On the probed timescale, upon approaching the glass transition temperature Tg from above, this length scale ξ is also shown to be consistent with Ising-like scaling, ξ ∝(T/-Tg Tg)-ν , with ν ≈0.7 . Furthermore, we demonstrate the possible scaling of ξ about the temperature at which super-Arrhenius growth of viscosity, and a marked growth of the penetration depth, sets in. Our simulation results suggest that upon supercooling, marked initial increase of the shear penetration depth in fluids may occur in tandem with the breakdown of the Stokes-Einstein relation.

  4. Critical length scales and strain localization govern the mechanical performance of multi-layer graphene assemblies

    NASA Astrophysics Data System (ADS)

    Xia, Wenjie; Ruiz, Luis; Pugno, Nicola M.; Keten, Sinan

    2016-03-01

    Multi-layer graphene assemblies (MLGs) or fibers with a staggered architecture exhibit high toughness and failure strain that surpass those of the constituent single sheets. However, how the architectural parameters such as the sheet overlap length affect these mechanical properties remains unknown due in part to the limitations of mechanical continuum models. By exploring the mechanics of MLG assemblies under tensile deformation using our established coarse-grained molecular modeling framework, we have identified three different critical interlayer overlap lengths controlling the strength, plastic stress, and toughness of MLGs, respectively. The shortest critical length scale Lsc governs the strength of the assembly as predicted by the shear-lag model. The intermediate critical length Lpc is associated with a dynamic frictional process that governs the strain localization propensity of the assembly, and hence the failure strain. The largest critical length scale LTc corresponds to the overlap length necessary to achieve 90% of the maximum theoretical toughness of the material. Our analyses provide the general guidelines for tuning the constitutive properties and toughness of multilayer 2D nanomaterials using elasticity, interlayer adhesion energy and geometry as molecular design parameters.Multi-layer graphene assemblies (MLGs) or fibers with a staggered architecture exhibit high toughness and failure strain that surpass those of the constituent single sheets. However, how the architectural parameters such as the sheet overlap length affect these mechanical properties remains unknown due in part to the limitations of mechanical continuum models. By exploring the mechanics of MLG assemblies under tensile deformation using our established coarse-grained molecular modeling framework, we have identified three different critical interlayer overlap lengths controlling the strength, plastic stress, and toughness of MLGs, respectively. The shortest critical length scale

  5. Dynamics and correlation length scales of a glass-forming liquid in quiescent and sheared conditions

    NASA Astrophysics Data System (ADS)

    Xu, Wen-Sheng; Sun, Zhao-Yan; An, Li-Jia

    2012-08-01

    We numerically study dynamics and correlation length scales of a colloidal liquid in both quiescent and sheared conditions to further understand the origin of slow dynamics and dynamic heterogeneity in glass-forming systems. The simulation is performed in a weakly frustrated two-dimensional liquid, where locally preferred order is allowed to develop with increasing density. The four-point density correlations and bond-orientation correlations, which have been frequently used to capture dynamic and static length scales ξ in a quiescent condition, can be readily extended to a system under steady shear in this case. In the absence of shear, we confirmed the previous findings that the dynamic slowing down accompanies the development of dynamic heterogeneity. The dynamic and static length scales increase with α-relaxation time τα as a power law \\xi \\sim {\\tau }_{\\alpha }^{\\mu }, with μ > 0. In the presence of shear, both viscosity and τα have power-law dependences on shear rate in the marked shear-thinning regime. However, the dependence of correlation lengths cannot be described by power laws in the same regime. Furthermore, the relation \\xi \\sim {\\tau }_{\\alpha }^{\\mu } between length scales and dynamics holds for not too strong shear where thermal fluctuations and external forces are both important in determining the properties of dense liquids. Thus, our results demonstrate a link between slow dynamics and structure in glass-forming liquids even under nonequilibrium conditions.

  6. Critical length scales and strain localization govern the mechanical performance of multi-layer graphene assemblies.

    PubMed

    Xia, Wenjie; Ruiz, Luis; Pugno, Nicola M; Keten, Sinan

    2016-03-28

    Multi-layer graphene assemblies (MLGs) or fibers with a staggered architecture exhibit high toughness and failure strain that surpass those of the constituent single sheets. However, how the architectural parameters such as the sheet overlap length affect these mechanical properties remains unknown due in part to the limitations of mechanical continuum models. By exploring the mechanics of MLG assemblies under tensile deformation using our established coarse-grained molecular modeling framework, we have identified three different critical interlayer overlap lengths controlling the strength, plastic stress, and toughness of MLGs, respectively. The shortest critical length scale L(C)(S) governs the strength of the assembly as predicted by the shear-lag model. The intermediate critical length L(C)(P) is associated with a dynamic frictional process that governs the strain localization propensity of the assembly, and hence the failure strain. The largest critical length scale L(C)(T) corresponds to the overlap length necessary to achieve 90% of the maximum theoretical toughness of the material. Our analyses provide the general guidelines for tuning the constitutive properties and toughness of multilayer 2D nanomaterials using elasticity, interlayer adhesion energy and geometry as molecular design parameters. PMID:26935048

  7. Critical length scales and strain localization govern the mechanical performance of multi-layer graphene assemblies.

    PubMed

    Xia, Wenjie; Ruiz, Luis; Pugno, Nicola M; Keten, Sinan

    2016-03-28

    Multi-layer graphene assemblies (MLGs) or fibers with a staggered architecture exhibit high toughness and failure strain that surpass those of the constituent single sheets. However, how the architectural parameters such as the sheet overlap length affect these mechanical properties remains unknown due in part to the limitations of mechanical continuum models. By exploring the mechanics of MLG assemblies under tensile deformation using our established coarse-grained molecular modeling framework, we have identified three different critical interlayer overlap lengths controlling the strength, plastic stress, and toughness of MLGs, respectively. The shortest critical length scale L(C)(S) governs the strength of the assembly as predicted by the shear-lag model. The intermediate critical length L(C)(P) is associated with a dynamic frictional process that governs the strain localization propensity of the assembly, and hence the failure strain. The largest critical length scale L(C)(T) corresponds to the overlap length necessary to achieve 90% of the maximum theoretical toughness of the material. Our analyses provide the general guidelines for tuning the constitutive properties and toughness of multilayer 2D nanomaterials using elasticity, interlayer adhesion energy and geometry as molecular design parameters.

  8. Healthcare-associated Staphylococcus aureus bloodstream infection: length of stay, attributable mortality, and additional direct costs.

    PubMed

    Primo, Mariusa Gomes Borges; Guilarde, Adriana Oliveira; Martelli, Celina M Turchi; Batista, Lindon Johnson de Abreu; Turchi, Marília Dalva

    2012-01-01

    This study aimed to determine the excess length of stay, extra expenditures, and attributable mortality to healthcare-associated S. aureus bloodstream infection (BSI) at a teaching hospital in central Brazil. The study design was a matched (1:1) case-control. Cases were defined as patients >13 years old, with a healthcare-associated S. aureus BSI. Controls included patients without an S. aureus BSI, who were matched to cases by gender, age (± 7 years), morbidity, and underlying disease. Data were collected from medical records and from the Brazilian National Hospital Information System (Sistema de Informações Hospitalares do Sistema Único de Saúde - SIH/SUS). A Wilcoxon rank sum test was performed to compare length of stay and costs between cases and controls. Differences in mortality between cases and controls were compared using McNemar's tests. The Mantel-Haenzel stratified analysis was performed to compare invasive device utilization. Data analyses were conducted using Epi Info 6.0 and Statistical Package for Social Sciences (SPSS 13.0). 84 case-control pairs matched by gender, age, admission period, morbidity, and underlying disease were analyzed. The mean lengths of hospital stay were 48.3 and 16.2 days for cases and controls, respectively (p<0.01), yielding an excess hospital stay among cases of 32.1 days. The excess mortality among cases compared to controls that was attributable to S. aureus bloodstream infection was 45.2%. Cases had a higher risk of dying compared to controls (OR 7.3, 95% CI 3.1-21.1). Overall costs of hospitalization (SIH/SUS) reached US$ 123,065 for cases versus US$ 40,247 for controls (p<0.01). The cost of antimicrobial therapy was 6.7 fold higher for cases compared to controls. Healthcare-associated S. aureus BSI was associated with statistically significant increases in length of hospitalization, attributable mortality, and economic burden. Implementation of measures to minimize the risk of healthcare-associated bacterial

  9. Infrared length scale and extrapolations for the no-core shell model

    NASA Astrophysics Data System (ADS)

    Wendt, K. A.; Forssén, C.; Papenbrock, T.; Sääf, D.

    2015-06-01

    We precisely determine the infrared (IR) length scale of the no-core shell model (NCSM). In the NCSM, the A -body Hilbert space is truncated by the total energy, and the IR length can be determined by equating the intrinsic kinetic energy of A nucleons in the NCSM space to that of A nucleons in a 3 (A -1 ) -dimensional hyper-radial well with a Dirichlet boundary condition for the hyper radius. We demonstrate that this procedure indeed yields a very precise IR length by performing large-scale NCSM calculations for 6Li. We apply our result and perform accurate IR extrapolations for bound states of 4He,6He,6Li , and 7Li . We also attempt to extrapolate NCSM results for 10B and 16O with bare interactions from chiral effective field theory over tens of MeV.

  10. Infrared length scale and extrapolations for the no-core shell model

    DOE PAGES

    Wendt, K. A.; Forssén, C.; Papenbrock, T.; Sääf, D.

    2015-06-03

    In this paper, we precisely determine the infrared (IR) length scale of the no-core shell model (NCSM). In the NCSM, the A-body Hilbert space is truncated by the total energy, and the IR length can be determined by equating the intrinsic kinetic energy of A nucleons in the NCSM space to that of A nucleons in a 3(A-1)-dimensional hyper-radial well with a Dirichlet boundary condition for the hyper radius. We demonstrate that this procedure indeed yields a very precise IR length by performing large-scale NCSM calculations for 6Li. We apply our result and perform accurate IR extrapolations for bound statesmore » of 4He, 6He, 6Li, and 7Li. Finally, we also attempt to extrapolate NCSM results for 10B and 16O with bare interactions from chiral effective field theory over tens of MeV.« less

  11. Nano-scaled graphene platelets with a high length-to-width aspect ratio

    DOEpatents

    Zhamu, Aruna; Guo, Jiusheng; Jang, Bor Z.

    2010-09-07

    This invention provides a nano-scaled graphene platelet (NGP) having a thickness no greater than 100 nm and a length-to-width ratio no less than 3 (preferably greater than 10). The NGP with a high length-to-width ratio can be prepared by using a method comprising (a) intercalating a carbon fiber or graphite fiber with an intercalate to form an intercalated fiber; (b) exfoliating the intercalated fiber to obtain an exfoliated fiber comprising graphene sheets or flakes; and (c) separating the graphene sheets or flakes to obtain nano-scaled graphene platelets. The invention also provides a nanocomposite material comprising an NGP with a high length-to-width ratio. Such a nanocomposite can become electrically conductive with a small weight fraction of NGPs. Conductive composites are particularly useful for shielding of sensitive electronic equipment against electromagnetic interference (EMI) or radio frequency interference (RFI), and for electrostatic charge dissipation.

  12. A modification in the technique of computing average lengths from the scales of fishes

    USGS Publications Warehouse

    Van Oosten, John

    1953-01-01

    In virtually all the studies that employ scales, otollths, or bony structures to obtain the growth history of fishes, it has been the custom to compute lengths for each individual fish and from these data obtain the average growth rates for any particular group. This method involves a considerable amount of mathematical manipulation, time, and effort. Theoretically it should be possible to obtain the same information simply by averaging the scale measurements for each year of life and the length of the fish employed and computing the average lengths from these data. This method would eliminate all calculations for individual fish. Although Van Oosten (1929: 338) pointed out many years ago the validity of this method of computation, his statements apparently have been overlooked by subsequent investigators.

  13. Studying fractal geometry on submicron length scales by small-angle scattering

    SciTech Connect

    Wong, P.; Lin, J.

    1988-08-01

    Recent studies have shown that internal surfaces of porous geological materials, such as rocks and lignite coals, can be described by fractals down to atomic length scales. In this paper, the basic properties of self-similar and self-affine fractals are reviewed and how fractal dimensions can be measured by small-angle scattering experiments are discussed.

  14. Understanding the mechanisms of length scale competition: The sine-Gordan soliton case

    SciTech Connect

    Sanchez, A.; Bishop, A.R.; Dominguez-Adame, F.

    1994-08-01

    We have examined the dynamical behavior of the kink solutions of the one-dimensional sine-Gordon equation in the presence of a spatially periodic parametric perturbation. We report on a novel occurrence of length scale competition in this system and show how it can be understood by means of linear stability analysis.

  15. Depletion stabilization in nanoparticle-polymer suspensions: multi-length-scale analysis of microstructure.

    PubMed

    Kim, Sunhyung; Hyun, Kyu; Moon, Joo Yong; Clasen, Christian; Ahn, Kyung Hyun

    2015-02-17

    We study the mechanism of depletion stabilization and the resultant microstructure of aqueous suspensions of nanosized silica and poly(vinyl alcohol) (PVA). Rheology, small-angle light scattering (SALS), and small-angle X-ray scattering (SAXS) techniques enable us to analyze the microstructure at broad length scale from single particle size to the size of a cluster of aggregated particles. As PVA concentration increases, the microstructure evolves from bridging flocculation, steric stabilization, depletion flocculation to depletion stabilization. To our surprise, when depletion stabilization occurs, the suspension shows the stabilization at the cluster length scale, while maintaining fractal aggregates at the particle length scale. This sharply contrasts previously reported studies on the depletion stabilization of microsized particle and polymer suspensions, which exhibits the stabilization at the particle length scale. On the basis of the evaluation of depletion interaction, we propose that the depletion energy barrier exists between clusters rather than particles due to the comparable size of silica particle and the radius gyration of PVA.

  16. Scale and time dependence of serial correlations in word-length time series of written texts

    NASA Astrophysics Data System (ADS)

    Rodriguez, E.; Aguilar-Cornejo, M.; Femat, R.; Alvarez-Ramirez, J.

    2014-11-01

    This work considered the quantitative analysis of large written texts. To this end, the text was converted into a time series by taking the sequence of word lengths. The detrended fluctuation analysis (DFA) was used for characterizing long-range serial correlations of the time series. To this end, the DFA was implemented within a rolling window framework for estimating the variations of correlations, quantified in terms of the scaling exponent, strength along the text. Also, a filtering derivative was used to compute the dependence of the scaling exponent relative to the scale. The analysis was applied to three famous English-written literary narrations; namely, Alice in Wonderland (by Lewis Carrol), Dracula (by Bram Stoker) and Sense and Sensibility (by Jane Austen). The results showed that high correlations appear for scales of about 50-200 words, suggesting that at these scales the text contains the stronger coherence. The scaling exponent was not constant along the text, showing important variations with apparent cyclical behavior. An interesting coincidence between the scaling exponent variations and changes in narrative units (e.g., chapters) was found. This suggests that the scaling exponent obtained from the DFA is able to detect changes in narration structure as expressed by the usage of words of different lengths.

  17. Integrated measurements of acoustical and optical thin layers II: Horizontal length scales

    NASA Astrophysics Data System (ADS)

    Moline, Mark A.; Benoit-Bird, Kelly J.; Robbins, Ian C.; Schroth-Miller, Maddie; Waluk, Chad M.; Zelenke, Brian

    2010-01-01

    The degree of layered organization of planktonic organisms in coastal systems impacts trophic interactions, the vertical availability of nutrients, and many biological rate processes. While there is reasonable characterization of the vertical structure of these phenomena, the extent and horizontal length scale of variation has rarely been addressed. Here we extend the examination of the vertical scale in the first paper of the series to the horizontal scale with combined shipboard acoustic measurements and bio-optic measurements taken on an autonomous underwater vehicle. Measurements were made in Monterey Bay, CA from 2002 to 2008 for the bio-optical parameters and during 2006 for acoustic scattering measurements. The combined data set was used to evaluate the horizontal decorrelation length scales of the bio-optical and acoustic scattering layers themselves. Because biological layers are often decoupled from the physical structure of the water column, assessment of the variance within identified layers was appropriate. This differs from other studies in that physical parameters were not used as a basis for the layer definition. There was a significant diel pattern to the decorrelation length scale for acoustic layers with the more abundant nighttime layers showing less horizontal variability despite their smaller horizontal extent. A significant decrease in the decorrelation length scale was found in bio-optical parameters over six years of study, coinciding with a documented shift in the plankton community. Results highlight the importance of considering plankton behavior and time of day with respect to scale when studying layers, and the challenges of sampling these phenomena.

  18. Intermediate length scale organisation in tin borophosphate glasses: new insights from high field correlation NMR.

    PubMed

    Tricot, G; Saitoh, A; Takebe, H

    2015-11-28

    The structure of tin borophosphate glasses, considered for the development of low temperature sealing glasses or anode materials for Li-batteries, has been analysed at the intermediate length scale by a combination of high field standard and advanced 1D/2D nuclear magnetic resonance techniques. The nature and extent of B/P mixing were analysed using the (11)B((31)P) dipolar heteronuclear multiple quantum coherence NMR sequence and the data interpretation allowed (i) detecting the presence and analysing the nature of the B-O-P linkages, (ii) re-interpreting the 1D (31)P spectra and (iii) extracting the proportion of P connected to borate species. Interaction between the different borate species was analysed using the (11)B double quantum-simple quantum experiment to (i) investigate the presence and nature of the B-O-B linkage, (ii) assign the different borate species observed all along the composition line and (iii) monitor the borate network formation. In addition, (119)Sn static NMR was used to investigate the evolution of the chemical environment of the tin polyhedra. Altogether, the set of data allowed determining the structural units constituting the glass network and quantifying the extent of B/P mixing. The structural data were then used to explain the non-linear and unusual evolution of the glass transition temperature.

  19. Length scales in alloy dissolution and measurement of absolute interfacial free energy.

    PubMed

    Rugolo, J; Erlebacher, J; Sieradzki, K

    2006-12-01

    De-alloying is the selective dissolution of one or more of the elemental components of an alloy. In binary alloys that exhibit complete solid solubility, de-alloying of the less noble component results in the formation of nanoporous metals, a materials class that has attracted attention for applications such as catalysis, sensing and actuation. In addition, the occurrence of de-alloying in metallic alloy systems under stress is known to result in stress-corrosion cracking, a key failure mechanism in fossil fuel and nuclear plants, ageing aircraft, and also an important concern in the design of nuclear-waste storage containers. Central to the design of corrosion-resistant alloys is the identification of a composition-dependent electrochemical critical potential, Vcrit, above which the current rises dramatically with potential, signalling the onset of bulk de-alloying. Below Vcrit, the surface is passivated by the accumulation of up to several monolayers of the more noble component. The current understanding of the processes that control Vcrit is incomplete. Here, we report on de-alloying results of Ag/Au superlattices that clarify the role of pre-existing length scales in alloy dissolution. Our data motivated us to re-analyse existing data on critical potentials of Ag-Au alloys and develop a simple unifying picture that accounts for the compositional dependence of solid-solution alloy critical potentials.

  20. Length Scales of Local Glass Transition Temperature Gradients Near Soft and Hard Polymer-Polymer Interfaces

    NASA Astrophysics Data System (ADS)

    Baglay, Roman; Roth, Connie

    Polymer-polymer interfaces are ubiquitous in polymer blends and block copolymers, while opening up another avenue for the study of interfacial perturbations to the local glass transition temperature Tg(z). We have previously reported the full local Tg(z) profile across a glassy-rubbery polymer interface between polystyrene (PS) and poly(n-butyl methacrylate) (PnBMA), an 80 K difference in bulk Tg [Baglay & Roth, J Chem Phys 2015, 143, 111101]. By using local fluorescence measurements, we revealed how the Tg(z) profile extends hundreds of nanometers away from the interface showing an asymmetric behavior penetrating deeper into the glassy PS side relative to the composition profile. Here, we extend these measurements to investigate how the local Tg profile in PS varies when in contact with a variety of immiscible polymers whose Tgs vary between +90 K and -80 K relative to the bulk Tg of PS, so-called hard vs. soft confinement. The data reveal that the onset of local Tg deviation from bulk in PS occurs at two distinct length scales, which depend on whether PS is the low Tg component (hard confinement) or the high Tg component (soft confinement). In addition, we explore the influence of finite system size on the range of dynamics by the introduction of periodic boundary conditions, as is commonly encountered in computer simulations or block copolymer systems.

  1. Energy-Filtering Transmission Electron Microscopy on the Nanometer Length Scale

    SciTech Connect

    Grogger, Werner; Varela del Arco, Maria; Ristau, Roger; Schaffer, Bernhard; Hofer, Ferdinand; Krishnan, Kannan M.

    2004-01-01

    Energy-filtering transmission electron microscopy (EFTEM), developed about ten years ago, is now a routine analysis tool in the characterization of materials. Based on the physical principles of electron energy-loss spectrometry (EELS), but with the addition of in-column or post-column energy-filters, it forms images of microstructures using a narrow energy band of inelastically scattered electrons. Post-column energy-filters, developed commercially by Gatan (Gatan Imaging Filter, GIF) in the early 1990s, could be attached to nearly any TEM. Almost at the same time, the introduction of the EM-912 microscope with an integrated {Omega}-filter by Zeiss, made it possible to use in-column filters as well. These two developments made EFTEM possible on an almost routine basis. The operation of these filters is rather straightforward and it is now possible to acquire element specific images within a few minutes. However, the optimal setup for data acquisition, the judicious choice of experimental parameters to solve specific materials science problems and the interpretation of the results can be rather difficult. For best results, a fundamental knowledge of the underlying physics of EELS and a systematic development of the technical details is necessary. In this work, we discuss the current status of EFTEM in terms of spatial resolution and illustrate it with a few technologically relevant applications at the nanometer length scale.

  2. Probing sub-alveolar length scales with hyperpolarized-gas diffusion NMR

    NASA Astrophysics Data System (ADS)

    Miller, Wilson; Carl, Michael; Mooney, Karen; Mugler, John; Cates, Gordon

    2009-05-01

    Diffusion MRI of the lung is a promising technique for detecting alterations of normal lung microstructure in diseases such as emphysema. The length scale being probed using this technique is related to the time scale over which the helium-3 or xenon-129 diffusion is observed. We have developed new MR pulse sequence methods for making diffusivity measurements at sub-millisecond diffusion times, allowing one to probe smaller length scales than previously possible in-vivo, and opening the possibility of making quantitative measurements of the ratio of surface area to volume (S/V) in the lung airspaces. The quantitative accuracy of simulated and experimental measurements in microstructure phantoms will be discussed, and preliminary in-vivo results will be presented.

  3. Composition dependence of charge and magnetic length scales in mixed valence manganite thin films.

    PubMed

    Singh, Surendra; Freeland, J W; Fitzsimmons, M R; Jeen, H; Biswas, A

    2016-01-01

    Mixed-valence manganese oxides present striking properties like the colossal magnetoresistance, metal-insulator transition (MIT) that may result from coexistence of ferromagnetic, metallic and insulating phases. Percolation of such phase coexistence in the vicinity of MIT leads to first-order transition in these manganites. However the length scales over which the electronic and magnetic phases are separated across MIT which appears compelling for bulk systems has been elusive in (La1-yPry)1-xCaxMnO3 films. Here we show the in-plane length scale over which charge and magnetism are correlated in (La0.4Pr0.6)1-xCaxMnO3 films with x = 0.33 and 0.375, across the MIT temperature. We combine electrical transport (resistance) measurements, x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and specular/off-specular x-ray resonant magnetic scattering (XRMS) measurements as a function of temperature to elucidate relationships between electronic, magnetic and morphological structure of the thin films. Using off-specular XRMS we obtained the charge-charge and charge-magnetic correlation length of these LPCMO films across the MIT. We observed different charge-magnetic correlation length for two films which increases below the MIT. The different correlation length shown by two films may be responsible for different macroscopic (transport and magnetic) properties. PMID:27461993

  4. Composition dependence of charge and magnetic length scales in mixed valence manganite thin films

    NASA Astrophysics Data System (ADS)

    Singh, Surendra; Freeland, J. W.; Fitzsimmons, M. R.; Jeen, H.; Biswas, A.

    2016-07-01

    Mixed-valence manganese oxides present striking properties like the colossal magnetoresistance, metal-insulator transition (MIT) that may result from coexistence of ferromagnetic, metallic and insulating phases. Percolation of such phase coexistence in the vicinity of MIT leads to first-order transition in these manganites. However the length scales over which the electronic and magnetic phases are separated across MIT which appears compelling for bulk systems has been elusive in (La1‑yPry)1‑xCaxMnO3 films. Here we show the in-plane length scale over which charge and magnetism are correlated in (La0.4Pr0.6)1‑xCaxMnO3 films with x = 0.33 and 0.375, across the MIT temperature. We combine electrical transport (resistance) measurements, x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and specular/off-specular x-ray resonant magnetic scattering (XRMS) measurements as a function of temperature to elucidate relationships between electronic, magnetic and morphological structure of the thin films. Using off-specular XRMS we obtained the charge-charge and charge-magnetic correlation length of these LPCMO films across the MIT. We observed different charge-magnetic correlation length for two films which increases below the MIT. The different correlation length shown by two films may be responsible for different macroscopic (transport and magnetic) properties.

  5. Composition dependence of charge and magnetic length scales in mixed valence manganite thin films

    PubMed Central

    Singh, Surendra; Freeland, J. W.; Fitzsimmons, M. R.; Jeen, H.; Biswas, A.

    2016-01-01

    Mixed-valence manganese oxides present striking properties like the colossal magnetoresistance, metal-insulator transition (MIT) that may result from coexistence of ferromagnetic, metallic and insulating phases. Percolation of such phase coexistence in the vicinity of MIT leads to first-order transition in these manganites. However the length scales over which the electronic and magnetic phases are separated across MIT which appears compelling for bulk systems has been elusive in (La1−yPry)1−xCaxMnO3 films. Here we show the in-plane length scale over which charge and magnetism are correlated in (La0.4Pr0.6)1−xCaxMnO3 films with x = 0.33 and 0.375, across the MIT temperature. We combine electrical transport (resistance) measurements, x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and specular/off-specular x-ray resonant magnetic scattering (XRMS) measurements as a function of temperature to elucidate relationships between electronic, magnetic and morphological structure of the thin films. Using off-specular XRMS we obtained the charge-charge and charge-magnetic correlation length of these LPCMO films across the MIT. We observed different charge-magnetic correlation length for two films which increases below the MIT. The different correlation length shown by two films may be responsible for different macroscopic (transport and magnetic) properties. PMID:27461993

  6. Natural length scales define the range of applicability of the Richards equation for capillary flows

    NASA Astrophysics Data System (ADS)

    Or, Dani; Lehmann, Peter; Assouline, Shmuel

    2015-09-01

    The rapid expansion of remotely sensed spatial information and enhanced computational capabilities fuel raising scientific and public expectations for reliable hydrologic predictions across time and spatial scales. Process-based hydrologic models often rely on the Richards equation (RE) formalism to represent unsaturated flow processes at multiple scales which raises the much debated question: does the underlying physics in the RE formulation apply at large scales of practical interest? The study analyses recent findings from different unsaturated flow processes (soil evaporation, internal redistribution, and capillary flow from point sources) revealing inherent characteristic length scales that delineate the spatial range of applicability of the RE. These length scales reflect the role of intrinsic porous medium properties that shape liquid phase continuity and interplay of forces that drive and resist unsaturated flow. The study revisits some of the key assumptions in the RE and their ramifications for numerical discretization. An intrinsic length scale for hydraulic continuity deduced from pore size distribution has been shown to control soil evaporation dynamics (i.e., stage 1 to stage 2 transition), to provide upper bounds for regional evaporative losses, and governs the dynamics of internal redistribution toward field capacity. For large-scale hydrologic applications, we show that the spatial extent of lateral flow interactions under most natural capillary gradients rarely exceed a few meters. The study provides a framework for guiding numerical and mathematical models for capillary flows across different scales considering the conditions for coexistence of stationarity, hydraulic continuity, and capillary gradients—essential ingredients for physically consistent application of the RE.

  7. Scaling analysis of random walks with persistence lengths: Application to self-avoiding walks

    NASA Astrophysics Data System (ADS)

    Granzotti, C. R. F.; Martinez, A. S.; da Silva, M. A. A.

    2016-05-01

    We develop an approach for performing scaling analysis of N -step random walks (RWs). The mean square end-to-end distance, , is written in terms of inner persistence lengths (IPLs), which we define by the ensemble averages of dot products between the walker's position and displacement vectors, at the j th step. For RW models statistically invariant under orthogonal transformations, we analytically introduce a relation between and the persistence length, λN, which is defined as the mean end-to-end vector projection in the first step direction. For self-avoiding walks (SAWs) on 2D and 3D lattices we introduce a series expansion for λN, and by Monte Carlo simulations we find that λ∞ is equal to a constant; the scaling corrections for λN can be second- and higher-order corrections to scaling for . Building SAWs with typically 100 steps, we estimate the exponents ν0 and Δ1 from the IPL behavior as function of j . The obtained results are in excellent agreement with those in the literature. This shows that only an ensemble of paths with the same length is sufficient for determining the scaling behavior of , being that the whole information needed is contained in the inner part of the paths.

  8. A Genome-Wide Association Analysis Reveals Epistatic Cancellation of Additive Genetic Variance for Root Length in Arabidopsis thaliana.

    PubMed

    Lachowiec, Jennifer; Shen, Xia; Queitsch, Christine; Carlborg, Örjan

    2015-01-01

    Efforts to identify loci underlying complex traits generally assume that most genetic variance is additive. Here, we examined the genetics of Arabidopsis thaliana root length and found that the genomic narrow-sense heritability for this trait in the examined population was statistically zero. The low amount of additive genetic variance that could be captured by the genome-wide genotypes likely explains why no associations to root length could be found using standard additive-model-based genome-wide association (GWA) approaches. However, as the broad-sense heritability for root length was significantly larger, and primarily due to epistasis, we also performed an epistatic GWA analysis to map loci contributing to the epistatic genetic variance. Four interacting pairs of loci were revealed, involving seven chromosomal loci that passed a standard multiple-testing corrected significance threshold. The genotype-phenotype maps for these pairs revealed epistasis that cancelled out the additive genetic variance, explaining why these loci were not detected in the additive GWA analysis. Small population sizes, such as in our experiment, increase the risk of identifying false epistatic interactions due to testing for associations with very large numbers of multi-marker genotypes in few phenotyped individuals. Therefore, we estimated the false-positive risk using a new statistical approach that suggested half of the associated pairs to be true positive associations. Our experimental evaluation of candidate genes within the seven associated loci suggests that this estimate is conservative; we identified functional candidate genes that affected root development in four loci that were part of three of the pairs. The statistical epistatic analyses were thus indispensable for confirming known, and identifying new, candidate genes for root length in this population of wild-collected A. thaliana accessions. We also illustrate how epistatic cancellation of the additive genetic variance

  9. A Genome-Wide Association Analysis Reveals Epistatic Cancellation of Additive Genetic Variance for Root Length in Arabidopsis thaliana

    PubMed Central

    Lachowiec, Jennifer; Shen, Xia; Queitsch, Christine; Carlborg, Örjan

    2015-01-01

    Efforts to identify loci underlying complex traits generally assume that most genetic variance is additive. Here, we examined the genetics of Arabidopsis thaliana root length and found that the genomic narrow-sense heritability for this trait in the examined population was statistically zero. The low amount of additive genetic variance that could be captured by the genome-wide genotypes likely explains why no associations to root length could be found using standard additive-model-based genome-wide association (GWA) approaches. However, as the broad-sense heritability for root length was significantly larger, and primarily due to epistasis, we also performed an epistatic GWA analysis to map loci contributing to the epistatic genetic variance. Four interacting pairs of loci were revealed, involving seven chromosomal loci that passed a standard multiple-testing corrected significance threshold. The genotype-phenotype maps for these pairs revealed epistasis that cancelled out the additive genetic variance, explaining why these loci were not detected in the additive GWA analysis. Small population sizes, such as in our experiment, increase the risk of identifying false epistatic interactions due to testing for associations with very large numbers of multi-marker genotypes in few phenotyped individuals. Therefore, we estimated the false-positive risk using a new statistical approach that suggested half of the associated pairs to be true positive associations. Our experimental evaluation of candidate genes within the seven associated loci suggests that this estimate is conservative; we identified functional candidate genes that affected root development in four loci that were part of three of the pairs. The statistical epistatic analyses were thus indispensable for confirming known, and identifying new, candidate genes for root length in this population of wild-collected A. thaliana accessions. We also illustrate how epistatic cancellation of the additive genetic variance

  10. Physics on the Smallest Scales: An Introduction to Minimal Length Phenomenology

    ERIC Educational Resources Information Center

    Sprenger, Martin; Nicolini, Piero; Bleicher, Marcus

    2012-01-01

    Many modern theories which try to unify gravity with the Standard Model of particle physics, such as e.g. string theory, propose two key modifications to the commonly known physical theories: the existence of additional space dimensions; the existence of a minimal length distance or maximal resolution. While extra dimensions have received a wide…

  11. Scaling Between Localization Length and TC in Disordered YBa2Cu3 O6.9

    NASA Astrophysics Data System (ADS)

    Gauzzi, Andrea; Pavuna, Davor

    We quantitatively study the effect of growth-induced reduction of long range structural order on the superconducting transition in epitaxial YBa2Cu3O6.9 films. The corresponding reduction of structural coherence length rc is determined from the width of X-ray diffraction rocking curves. Tc measurements in the films give evidence for the validity of the empirical scaling relation ΔTc~ rc,ab-2, where ΔTc is the disorder-induced reduction of Tc and rc,ab is the structural coherence length in the ab-plane. To explain this algebraic law we propose a simple phenomenological model based on the disorder-induced localization of the charge carriers within each ordered domain of size rc,ab. This picture enables us to precisely determine the Ginzburg-Landau superconducting coherence length in the ab-plane, and we obtain ξab=1.41±0.04 nm.

  12. Influence of length of hot soak of melt on properties of lithium greases with additives

    SciTech Connect

    El'-Shaban, I.; Fuks, I.G.; Safi, M.; Uvarova, E.M.; Yaroshevich, S.V.

    1983-11-01

    An extension of the time during which the melt is hot-soaked at the maximum cooking temperature tends to improve the dispersion of the thickening agent in the oil but also increases oxidation and evaporation. This paper investigates the influence of hot-soaking the soap/oil melt of Li greases on the effectiveness of selected additives. Extending the hot-soak time in manufacturing Li greases leads to oxidation as well as accumulation of oxygen-containing substances in the grease. The end result is poorer properties of the grease.

  13. Intraflagellar transport particle size scales inversely with flagellar length: revisiting the balance-point length control model

    PubMed Central

    Engel, Benjamin D.; Ludington, William B.

    2009-01-01

    The assembly and maintenance of eukaryotic flagella are regulated by intraflagellar transport (IFT), the bidirectional traffic of IFT particles (recently renamed IFT trains) within the flagellum. We previously proposed the balance-point length control model, which predicted that the frequency of train transport should decrease as a function of flagellar length, thus modulating the length-dependent flagellar assembly rate. However, this model was challenged by the differential interference contrast microscopy observation that IFT frequency is length independent. Using total internal reflection fluorescence microscopy to quantify protein traffic during the regeneration of Chlamydomonas reinhardtii flagella, we determined that anterograde IFT trains in short flagella are composed of more kinesin-associated protein and IFT27 proteins than trains in long flagella. This length-dependent remodeling of train size is consistent with the kinetics of flagellar regeneration and supports a revised balance-point model of flagellar length control in which the size of anterograde IFT trains tunes the rate of flagellar assembly. PMID:19805630

  14. Phase field modelling of stressed grain growth: Analytical study and the effect of microstructural length scale

    SciTech Connect

    Jamshidian, M.; Rabczuk, T.

    2014-03-15

    We establish the correlation between the diffuse interface and sharp interface descriptions for stressed grain boundary migration by presenting analytical solutions for stressed migration of a circular grain boundary in a bicrystalline phase field domain. The validity and accuracy of the phase field model is investigated by comparing the phase field simulation results against analytical solutions. The phase field model can reproduce precise boundary kinetics and stress evolution provided that a thermodynamically consistent theory and proper expressions for model parameters in terms of physical material properties are employed. Quantitative phase field simulations are then employed to investigate the effect of microstructural length scale on microstructure and texture evolution by stressed grain growth in an elastically deformed polycrystalline aggregate. The simulation results reveal a transitional behaviour from normal to abnormal grain growth by increasing the microstructural length scale.

  15. Structure, dynamics and multiple length-scales in network-forming materials

    NASA Astrophysics Data System (ADS)

    Wilson, Mark

    2016-07-01

    Relationships between the structural and dynamical properties of network-forming materials are investigated. A generic model is utilised for systems of stoichiometry MX2 which are linked in the sense that they can all be usefully considered as constructed from linked MX4 tetrahedra. A single model parameter (the anion polarizability) is varied systematically to control the mean MXM bond angles (and hence the network topologies). The networks evolve from those dominated by corner-sharing units to those dominated by edge-sharing structural motifs. These changes are accompanied by changes in the characteristic length-scales, with the emergence of ordering on intermediate length-scales. Key dynamical properties (the liquid relaxation just above the melting point and the liquid fragility) are studied and their relationship to the underlying static structure analysed.

  16. The accuracy of climate models' simulated season lengths and the effectiveness of grid scale correction factors

    DOE PAGES

    Winterhalter, Wade E.

    2011-09-01

    Global climate change is expected to impact biological populations through a variety of mechanisms including increases in the length of their growing season. Climate models are useful tools for predicting how season length might change in the future. However, the accuracy of these models tends to be rather low at regional geographic scales. Here, I determined the ability of several atmosphere and ocean general circulating models (AOGCMs) to accurately simulate historical season lengths for a temperate ectotherm across the continental United States. I also evaluated the effectiveness of regional-scale correction factors to improve the accuracy of these models. I foundmore » that both the accuracy of simulated season lengths and the effectiveness of the correction factors to improve the model's accuracy varied geographically and across models. These results suggest that regional specific correction factors do not always adequately remove potential discrepancies between simulated and historically observed environmental parameters. As such, an explicit evaluation of the correction factors' effectiveness should be included in future studies of global climate change's impact on biological populations.« less

  17. Mitotic chromosome length scales in response to both cell and nuclear size

    PubMed Central

    Ladouceur, Anne-Marie; Dorn, Jonas F.

    2015-01-01

    Multicellular development requires that cells reduce in size as a result of consecutive cell divisions without increase in embryo volume. To maintain cellular integrity, organelle size adapts to cell size throughout development. During mitosis, the longest chromosome arm must be shorter than half of the mitotic spindle for proper chromosome segregation. Using high-resolution time-lapse microscopy of living Caenorhabditis elegans embryos, we have quantified the relation between cell size and chromosome length. In control embryos, chromosome length scaled to cell size. Artificial reduction of cell size resulted in a shortening of chromosome length, following a trend predicted by measurements from control embryos. Disturbing the RAN (Ras-related nuclear protein)-GTP gradient decoupled nuclear size from cell size and resulted in chromosome scaling to nuclear size rather than cell size; smaller nuclei contained shorter chromosomes independent of cell size. In sum, quantitative analysis relating cell, nuclear, and chromosome size predicts two levels of chromosome length regulation: one through cell size and a second in response to nuclear size. PMID:26033258

  18. The accuracy of climate models' simulated season lengths and the effectiveness of grid scale correction factors

    SciTech Connect

    Winterhalter, Wade E.

    2011-09-01

    Global climate change is expected to impact biological populations through a variety of mechanisms including increases in the length of their growing season. Climate models are useful tools for predicting how season length might change in the future. However, the accuracy of these models tends to be rather low at regional geographic scales. Here, I determined the ability of several atmosphere and ocean general circulating models (AOGCMs) to accurately simulate historical season lengths for a temperate ectotherm across the continental United States. I also evaluated the effectiveness of regional-scale correction factors to improve the accuracy of these models. I found that both the accuracy of simulated season lengths and the effectiveness of the correction factors to improve the model's accuracy varied geographically and across models. These results suggest that regional specific correction factors do not always adequately remove potential discrepancies between simulated and historically observed environmental parameters. As such, an explicit evaluation of the correction factors' effectiveness should be included in future studies of global climate change's impact on biological populations.

  19. Observing Evolution in the Supergranular Network Length Scale During Periods of Low Solar Activity

    NASA Astrophysics Data System (ADS)

    McIntosh, Scott W.; Leamon, Robert J.; Hock, Rachel A.; Rast, Mark P.; Ulrich, Roger K.

    2011-03-01

    We present the initial results of an observational study into the variation of the dominant length scale of quiet solar emission: supergranulation. The distribution of magnetic elements in the lanes that from the network affects, and reflects, the radiative energy in the plasma of the upper solar chromosphere and transition region at the magnetic network boundaries forming as a result of the relentless interaction of magnetic fields and convective motions of the Suns' interior. We demonstrate that a net difference of ~0.5 Mm in the supergranular emission length scale occurs when comparing observation cycle 22/23 and cycle 23/24 minima. This variation in scale is reproduced in the data sets of multiple space- and ground-based instruments and using different diagnostic measures. By means of extension, we consider the variation of the supergranular length scale over multiple solar minima by analyzing a subset of the Mount Wilson Solar Observatory Ca II K image record. The observations and analysis presented provide a tantalizing look at solar activity in the absence of large-scale flux emergence, offering insight into times of "extreme" solar minimum and general behavior such as the phasing and cross-dependence of different components of the spectral irradiance. Given that the modulation of the supergranular scale imprints itself in variations of the Suns' spectral irradiance, as well as in the mass and energy transport into the entire outer atmosphere, this preliminary investigation is an important step in understanding the impact of the quiet Sun on the heliospheric system.

  20. A mass-length scaling law for modeling muscle strength in the lower limb.

    PubMed

    Correa, Tomas A; Pandy, Marcus G

    2011-11-10

    Musculoskeletal computer models are often used to study muscle function in children with and without impaired mobility. Calculations of muscle forces depend in part on the assumed strength of each muscle, represented by the peak isometric force parameter, which is usually based on measurements obtained from cadavers of adult donors. The aim of the present study was twofold: first, to develop a method for scaling lower-limb peak isometric muscle forces in typically-developing children; and second, to determine the effect of this scaling method on model calculations of muscle forces obtained for normal gait. Muscle volumes were determined from magnetic resonance (MR) images obtained from ten children aged from 7 to 13yr. A new mass-length scaling law was developed based on the assumption that muscle volume and body mass are linearly related, which was confirmed by the obtained volume and body mass data. Two musculoskeletal models were developed for each subject: one in which peak isometric muscle forces were estimated using the mass-length scaling law; and another in which these parameters were determined directly from the MR-derived muscle volumes. Musculoskeletal modeling and quantitative gait analysis were then used to calculate lower-limb muscle forces in normal walking. The patterns of muscle forces predicted by the model with scaled peak isometric force values were similar to those predicted by the MR-based model, implying that assessments of muscle function obtained from these two methods are practically equivalent. These results support the use of mass-length scaling in the development of subject-specific musculoskeletal models of children.

  1. Factorial Moments Analyses Show a Characteristic Length Scale in DNA Sequences

    NASA Astrophysics Data System (ADS)

    Mohanty, A. K.; Narayana Rao, A. V. S. S.

    2000-02-01

    A unique feature of most of the DNA sequences, found through the factorial moments analysis, is the existence of a characteristic length scale around which the density distribution is nearly Poissonian. Above this point, the DNA sequences, irrespective of their intron contents, show long range correlations with a significant deviation from the Gaussian statistics, while, below this point, the DNA statistics are essentially Gaussian. The famous DNA walk representation is also shown to be a special case of the present analysis.

  2. The role of reactant unmixedness, strain rate, and length scale on premixed combustor performance

    SciTech Connect

    Samuelsen, S.; LaRue, J.; Vilayanur, S.; Guillaume, D.

    1995-12-31

    Lean premixed combustion provides a means to reduce pollutant formation and increase combustion efficiency. However, fuel-air mixing is rarely uniform in space and time. This nonuniformity in concentration will lead to relative increases in pollutant formation and decreases in combustion efficiency. The nonuniformity of the concentration at the exit of the premixer has been defined by Lyons (1981) as the ``unmixedness.`` Although turbulence properties such as length scales and strain rate are known to effect unmixedness, the exact relationship is unknown. Evaluating this relationship and the effect of unmixedness in premixed combustion on pollutant formation and combustion efficiency are an important part of the overall goal of US Department of Energy`s Advanced Turbine System (ATS) program and are among the goals of the program described herein. The information obtained from ATS is intended to help to develop and commercialize gas turbines. The contributions to the program which the University of California (Irvine) Combustion Lab (UCICL) will provide are: (1) establish the relationship of inlet unmixedness, length scales, and mean strain rate to performance, (2) determine the optimal levels of inlet unmixedness, length scales, and mean strain rates to maximize combustor performance, and (3) identify efficient premixing methods for achieving the necessary inlet conditions. The program during this reporting period is focused on developing a means to measure and qualify different degrees of temporal and spatial unmixedness. Laser diagnostic methods for planer unmixedness measurements are being developed and preliminary results are presented herein. These results will be used to (1), aid in the design of experimental premixers, and (2), determine the unmixedness which will be correlated with the emissions of the combustor. This measure of unmixedness coupled with length scale, strain rate and intensity information is required to attain the UCI goals.

  3. Millimeter-wave backscatter diagnostic for the study of short scale length plasma fluctuations (invited)

    SciTech Connect

    Rhodes, T. L.; Peebles, W. A.; Nguyen, X.; VanZeeland, M. A.; De Grassie, J. S.; Doyle, E. J.; Wang, G.; Zeng, L.

    2006-10-15

    The development, laboratory tests, and experimental results relating to a new high-k diagnostic technique for the study of short scale length turbulence are reported. The system is based on backscattering of a millimeter-wave (94 GHz) probe beam by density fluctuations within the plasma. This diagnostic has been fully integrated with an upgraded far-infrared forward scattering system on the DIII-D tokamak. The combined system monitors a broad turbulent spectral range from 0 to 40 cm{sup -1}. Short-scale (e.g., electron temperature gradient scale) modes as well as longer wavelength (e.g., ion temperature gradient and trapped electron mode scale) instabilities are simultaneously monitored to accurately characterize plasma turbulence. The backscattering geometry and innovative use of the second harmonic electron cyclotron resonance as an internal 'beam dump' allow detection of small level fluctuations at high k, while maximizing discrimination against the ubiquitous, larger level, low-k fluctuations.

  4. Energy Dependence and Scaling Property of Localization Length near a Gapped Flat Band

    NASA Astrophysics Data System (ADS)

    Ge, Li; Tureci, Hakan

    Using a tight-binding model for a one-dimensional Lieb lattice, we show that the localization length near a gapped flat band behaves differently from the typical Urbach tail in a band gap: instead of reducing monotonically as the energy E moves away from the flat band energy Ef, the presence of the flat band causes a nonmonotonic energy dependence of the localization length. This energy dependence follows a scaling property when the energy is within the spread (W) of uniformly distributed diagonal disorder, i.e. the localization length is only a function of (E-Ef)/W. Several other lattices are compared to distinguish the effect of the flat band on the localization length, where we eliminate, shift, or duplicate the flat band, without changing the dispersion relations of other bands. Using the top right element of the Green's matrix, we derive an analytical relation between the density of states and the localization length, which shines light on these properties of the latter, including a summation rule for its inverse. This work is partially supported by NSF under Grant No. DMR-1506987.

  5. Large-scale evidence of dependency length minimization in 37 languages.

    PubMed

    Futrell, Richard; Mahowald, Kyle; Gibson, Edward

    2015-08-18

    Explaining the variation between human languages and the constraints on that variation is a core goal of linguistics. In the last 20 y, it has been claimed that many striking universals of cross-linguistic variation follow from a hypothetical principle that dependency length--the distance between syntactically related words in a sentence--is minimized. Various models of human sentence production and comprehension predict that long dependencies are difficult or inefficient to process; minimizing dependency length thus enables effective communication without incurring processing difficulty. However, despite widespread application of this idea in theoretical, empirical, and practical work, there is not yet large-scale evidence that dependency length is actually minimized in real utterances across many languages; previous work has focused either on a small number of languages or on limited kinds of data about each language. Here, using parsed corpora of 37 diverse languages, we show that overall dependency lengths for all languages are shorter than conservative random baselines. The results strongly suggest that dependency length minimization is a universal quantitative property of human languages and support explanations of linguistic variation in terms of general properties of human information processing.

  6. Length scales of magma transport in reactive two-phase flow

    NASA Astrophysics Data System (ADS)

    Hier-Majumder, S.; Takei, Y.

    2007-12-01

    During magma migration, both interfacial tension and mass exchange between the matrix and the melt play an important role in controlling the efficiency and rate of melt extraction and the chemical signature of the magma. In this work, we develop a new formulation governing the dynamics of a two-phase aggregate coupling effects of interfacial tension and mass exchange between the melt and the matrix by dissolution-precipitation. Dissolution-precipitation, which is limited by the rate and length scales of diffusive mass transport of ions, typically redistributes melt over small length scales. A process likely to dominate in the length scale of laboratory experiments. Rapid diffusive mass redistribution can also significantly reduce the rate of segregation of buoyant small-wavelength melt pockets. Growth or decay of large wavelength melt structures such as melt-rich layers in the Earth's lower mantle, blobs of core-forming material in the proto-Earth, and magma bodies beneath volcanic arcs and midoceanic ridges is dominated by a balance between interfacial tension, buoyancy, and viscous deformation of the matrix. Efficiency of buoyancy-driven extraction of large wavelength melt structures are strongly modulated by interfacial tension depending on the average grain size of the matrix and the state of disaggregation of the matrix.

  7. Convergence of macroscopic tongue anatomy in ruminants and scaling relationships with body mass or tongue length.

    PubMed

    Meier, Andrea R; Schmuck, Ute; Meloro, Carlo; Clauss, Marcus; Hofmann, Reinhold R

    2016-03-01

    Various morphological measures demonstrate convergent evolution in ruminants with their natural diet, in particular with respect to the browser/grazer dichotomy. Here, we report quantitative macroanatomical measures of the tongue (length and width of specific parts) of 65 ruminant species and relate them to either body mass (BM) or total tongue length, and to the percentage of grass in the natural diet (%grass). Models without and with accounting for the phylogenetic structures of the dataset were used, and models were ranked using Akaike's Information Criterion. Scaling relationships followed geometric principles, that is, length measures scaled with BM to the power of 0.33. Models that used tongue length rather than BM as a body size proxy were consistently ranked better, indicating that using size proxies that are less susceptible to a wider variety of factors (such as BM that fluctuates with body condition) should be attempted whenever possible. The proportion of the freely mobile tongue tip of the total tongue (and hence also the corpus length) was negatively correlated to %grass, in accordance with concepts that the feeding mechanism of browsers requires more mobile tongues. It should be noted that some nonbrowsers, such as cattle, use a peculiar mechanism for grazing that also requires long, mobile tongues, but they appear to be exceptions. A larger corpus width with increasing %grass corresponds to differences in snout shape with broader snouts in grazers. The Torus linguae is longer with increasing %grass, a finding that still warrants functional interpretation. This study shows that tongue measures covary with diet in ruminants. In contrast, the shape of the tongue (straight or "hourglass-shaped" as measured by the ratio of the widest and smallest corpus width) is unrelated to diet and is influenced strongly by phylogeny.

  8. The small length scale effect for a non-local cantilever beam: a paradox solved.

    PubMed

    Challamel, N; Wang, C M

    2008-08-27

    Non-local continuum mechanics allows one to account for the small length scale effect that becomes significant when dealing with microstructures or nanostructures. This paper presents some simplified non-local elastic beam models, for the bending analyses of small scale rods. Integral-type or gradient non-local models abandon the classical assumption of locality, and admit that stress depends not only on the strain value at that point but also on the strain values of all points on the body. There is a paradox still unresolved at this stage: some bending solutions of integral-based non-local elastic beams have been found to be identical to the classical (local) solution, i.e. the small scale effect is not present at all. One example is the Euler-Bernoulli cantilever nanobeam model with a point load which has application in microelectromechanical systems and nanoelectromechanical systems as an actuator. In this paper, it will be shown that this paradox may be overcome with a gradient elastic model as well as an integral non-local elastic model that is based on combining the local and the non-local curvatures in the constitutive elastic relation. The latter model comprises the classical gradient model and Eringen's integral model, and its application produces small length scale terms in the non-local elastic cantilever beam solution. PMID:21730658

  9. Magnetic braking, ambipolar diffusion, cloud cores, and star formation - Natural length scales and protostellar masses

    NASA Astrophysics Data System (ADS)

    Mouschovias, Telemachos Ch.

    1991-05-01

    Magnetic braking is essential for cloud contraction and star formation. Ambipolar diffusion is unavoidable in self-gravitating, magnetic clouds and leads to single-stage (as opposed to hierarchical) fragmentation (or core formation) and protostar formation. Magnetic forces dominate thermal-pressure and centrifugal forces over scales comparable to molecular cloud radii. Magnetic support of molecular clouds and the imperfect collisional coupling between charged and neutral particles introduce a critical magnetic length scale (λM,cr = 0.62υAτff) and an Alfvén length scale ((λA = πυAτni), respectively, in the problem which together with a critical thermal length scale (λT,cr = 1.09Caτff) explain naturally the formation of fragments (or cores) in otherwise quiescent clouds and determine the sizes and masses of these fragments during the subsequent stages of contraction. (The quantity υA is the Alfvén speed, τni the mean neutral-ion collision time, Ca the adiabatic speed of sound, and τff the free4all time scale.) Numerical calculations based on new adaptive-grid techniques follow the formation of fragments by ambipolar diffusion and their subsequent collapse up to an enhancement in central density above its initial equilibrium value by a factor ≃106 with excellent spatial resolution. The results confirm the existence and relevance of the three length scales and extend the analytical understanding of fragmentation and star formation derived from them. The ultimately bimodal opposition to gravity (by magnetic forces in the envelope and by thermal-pressure forces in the core) introduces a break in the slope of the log pn -log r profile. The relation Bc ∞ pkc between the magnetic field strength and the gas density in cloud cores holds with K = 0.4 - 0.5 even in the presence of ambipolar diffusion up to densities ˜109 cm-3 for a wide variety of clouds. The value K ≃ ½ is fairly typical. At the late stages of evolution, for example, at a central density

  10. Fracture Testing at Small-Length Scales: From Plasticity in Si to Brittleness in Pt

    NASA Astrophysics Data System (ADS)

    Jaya, B. Nagamani; Jayaram, Vikram

    2016-01-01

    The field of micro-/nano-mechanics of materials has been driven, on the one hand by the development of ever smaller structures in devices, and, on the other, by the need to map property variations in large systems that are microstructurally graded. Observations of `smaller is stronger' have also brought in questions of accompanying fracture property changes in the materials. In the wake of scattered articles on micro-scale fracture testing of various material classes, this review attempts to provide a holistic picture of the current state of the art. In the process, various reliable micro-scale geometries are shown, challenges with respect to instrumentation to probe ever smaller length scales are discussed and examples from recent literature are put together to exhibit the expanse of unusual fracture response of materials, from ductility in Si to brittleness in Pt. Outstanding issues related to fracture mechanics of small structures are critically examined for plausible solutions.

  11. Scaling of the critical free length for progressive unfolding of self-bonded graphene

    SciTech Connect

    Kwan, Kenny; Cranford, Steven W.

    2014-05-19

    Like filled pasta, rolled or folded graphene can form a large nanocapsule surrounding a hollow interior. Use as a molecular carrier, however, requires understanding of the opening of such vessels. Here, we investigate a monolayer sheet of graphene as a theoretical trial platform for such a nanocapsule. The graphene is bonded to itself via aligned disulfide (S-S) bonds. Through theoretical analysis and atomistic modeling, we probe the critical nonbonded length (free length, L{sub crit}) that induces fracture-like progressive unfolding as a function of folding radius (R{sub i}). We show a clear linear scaling relationship between the length and radius, which can be used to determine the necessary bond density to predict mechanical opening/closing. However, stochastic dissipated energy limits any exact elastic formulation, and the required energy far exceeds the dissociation energy of the S-S bond. We account for the necessary dissipated kinetic energy through a simple scaling factor (Ω), which agrees well with computational results.

  12. Persistence length and scaling properties of single-stranded DNA adsorbed on modified graphite.

    PubMed

    Rechendorff, Kristian; Witz, Guillaume; Adamcik, Jozef; Dietler, Giovanni

    2009-09-01

    We have characterized the polymer physics of single-stranded DNA (ssDNA) using atomic force microscopy. The persistence length l(p) of circular ssDNA adsorbed on a modified graphite surface was determined independently of secondary structure. At a very low ionic strength we obtained l(p)=9.1 nm from the bond correlation function. Increasing the salt concentration lead to a decrease in l(p); at 1 mM NaCl we found l(p)=6.7 nm, while at 10 mM NaCl a value l(p)=4.6 nm was obtained. The persistence length was also extracted from the root-mean-square end-to-end distance and the end-to-end distance distribution function. Finally, we have investigated the scaling behavior using the two latter quantities, and found that on long length scales ssDNA behaves as a two-dimensional self-avoiding walk.

  13. Infrared length scale and extrapolations for the no-core shell model

    SciTech Connect

    Wendt, K. A.; Forssén, C.; Papenbrock, T.; Sääf, D.

    2015-06-03

    In this paper, we precisely determine the infrared (IR) length scale of the no-core shell model (NCSM). In the NCSM, the A-body Hilbert space is truncated by the total energy, and the IR length can be determined by equating the intrinsic kinetic energy of A nucleons in the NCSM space to that of A nucleons in a 3(A-1)-dimensional hyper-radial well with a Dirichlet boundary condition for the hyper radius. We demonstrate that this procedure indeed yields a very precise IR length by performing large-scale NCSM calculations for 6Li. We apply our result and perform accurate IR extrapolations for bound states of 4He, 6He, 6Li, and 7Li. Finally, we also attempt to extrapolate NCSM results for 10B and 16O with bare interactions from chiral effective field theory over tens of MeV.

  14. Large-scale evidence of dependency length minimization in 37 languages

    PubMed Central

    Futrell, Richard; Mahowald, Kyle; Gibson, Edward

    2015-01-01

    Explaining the variation between human languages and the constraints on that variation is a core goal of linguistics. In the last 20 y, it has been claimed that many striking universals of cross-linguistic variation follow from a hypothetical principle that dependency length—the distance between syntactically related words in a sentence—is minimized. Various models of human sentence production and comprehension predict that long dependencies are difficult or inefficient to process; minimizing dependency length thus enables effective communication without incurring processing difficulty. However, despite widespread application of this idea in theoretical, empirical, and practical work, there is not yet large-scale evidence that dependency length is actually minimized in real utterances across many languages; previous work has focused either on a small number of languages or on limited kinds of data about each language. Here, using parsed corpora of 37 diverse languages, we show that overall dependency lengths for all languages are shorter than conservative random baselines. The results strongly suggest that dependency length minimization is a universal quantitative property of human languages and support explanations of linguistic variation in terms of general properties of human information processing. PMID:26240370

  15. Roughness of fault surfaces over a length-scale range from nano- to milimeters

    NASA Astrophysics Data System (ADS)

    Kishida, M.; Mizoguchi, K.; Takahashi, M.; Hirose, T.

    2014-12-01

    Fault-surface roughness is one of the primary factors affecting the mechanics of earthquakes and faulting. We report on the topographic roughness measurements on two natural fault surfaces with a continuous length-scale range from 1 nm to 3 mm. The fault surfaces observed in this study include (1) the Corona Heights fault in the Castro Area of San Francisco, detail microstructures reported by Kirkpatrick et al., (2013), and (2) the Itozawa fault in Fukushima prefecture, a fault moved just after the 2011 Off the Pacific Coast of Tohoku earthquake. To measure fault surface to we performed line-measurements both parallel and perpendicular to the slickenlines using two scanner devices; a confocal white-light scanning microscope (measurable range: 0.15 ˜ 3000 μm) and a scanning probe microscope (1 ˜ 50000 nm). The topographic properties of the measured surfaces were expressed either as a Hurst exponent (H) which are calculated from Power Spectrum Density (PSD) of topography data. The measurements revealed that the Corona Heights fault and the Itozawa fault exhibit a similar geometrical property, a linear behavior on a log-log plot where axes are PSD and spatial length scale. A slope of the log-log plot, H, of the Corona Heights fault and the Itozawa fault shows HN = 0.76 ± 0.01 perpendicular to the slickenslide and HP = 0.84 ± 0.01 parallel to it, and HN = 0.88 ± 0.01 and HP = 0.91 ± 0.01, respectively. The measurements on both faults show HP are higher than HN, which is inconsistent with previous results that HP is small compared to HN because surface roughness in the slip direction becomes less pronounced selectively with progressive displacement. (e.g., Sagy et al., 2007). There is a hypotheses that explain the difference that HP and HN are undifferentiated with displacement in the length-scale range from 1 nm to 3 mm. Candela et al., (2012) measured roughness of 13 earthquake fault surfaces and suggested that the fault geometry can be expressed as a single

  16. Insulating behavior for DNA molecules between nanoelectrodes at the 100 nm length scale

    NASA Astrophysics Data System (ADS)

    Storm, A. J.; van Noort, J.; de Vries, S.; Dekker, C.

    2001-12-01

    Electrical transport measurements are reported for double-stranded DNA molecules located between nanofabricated electrodes. We observe the absence of any electrical conduction through these DNA-based devices, both at the single-molecule level as well as for small bundles of DNA. We obtain a lower bound of 10 TΩ for the resistance of a DNA molecule at length scales larger than 40 nm. It is concluded that DNA is insulating. This conclusion is based on an extensive set of experiments in which we varied key parameters such as the base-pair sequence [mixed sequence and homogeneous poly(dG)ṡpoly(dC)], length between contacts (40-500 nm), substrate (SiO2 or mica), electrode material (gold or platinum), and electrostatic doping fields. Discrepancies with other reports in the literature are discussed.

  17. Condensation on superhydrophobic surfaces: the role of local energy barriers and structure length scale.

    PubMed

    Enright, Ryan; Miljkovic, Nenad; Al-Obeidi, Ahmed; Thompson, Carl V; Wang, Evelyn N

    2012-10-01

    Water condensation on surfaces is a ubiquitous phase-change process that plays a crucial role in nature and across a range of industrial applications, including energy production, desalination, and environmental control. Nanotechnology has created opportunities to manipulate this process through the precise control of surface structure and chemistry, thus enabling the biomimicry of natural surfaces, such as the leaves of certain plant species, to realize superhydrophobic condensation. However, this "bottom-up" wetting process is inadequately described using typical global thermodynamic analyses and remains poorly understood. In this work, we elucidate, through imaging experiments on surfaces with structure length scales ranging from 100 nm to 10 μm and wetting physics, how local energy barriers are essential to understand non-equilibrium condensed droplet morphologies and demonstrate that overcoming these barriers via nucleation-mediated droplet-droplet interactions leads to the emergence of wetting states not predicted by scale-invariant global thermodynamic analysis. This mechanistic understanding offers insight into the role of surface-structure length scale, provides a quantitative basis for designing surfaces optimized for condensation in engineered systems, and promises insight into ice formation on surfaces that initiates with the condensation of subcooled water.

  18. Characteristic length scale of input data in distributed models: implications for modeling grain size

    USGS Publications Warehouse

    Artan, Guleid A.; Neale, C. M. U.; Tarboton, D. G.

    2000-01-01

    The appropriate spatial scale for a distributed energy balance model was investigated by: (a) determining the scale of variability associated with the remotely sensed and GIS-generated model input data; and (b) examining the effects of input data spatial aggregation on model response. The semi-variogram and the characteristic length calculated from the spatial autocorrelation were used to determine the scale of variability of the remotely sensed and GIS-generated model input data. The data were collected from two hillsides at Upper Sheep Creek, a sub-basin of the Reynolds Creek Experimental Watershed, in southwest Idaho. The data were analyzed in terms of the semivariance and the integral of the autocorrelation. The minimum characteristic length associated with the variability of the data used in the analysis was 15 m. Simulated and observed radiometric surface temperature fields at different spatial resolutions were compared. The correlation between agreement simulated and observed fields sharply declined after a 10×10 m2 modeling grid size. A modeling grid size of about 10×10 m2 was deemed to be the best compromise to achieve: (a) reduction of computation time and the size of the support data; and (b) a reproduction of the observed radiometric surface temperature.

  19. Additional Results of Glaze Icing Scaling in SLD Conditions

    NASA Technical Reports Server (NTRS)

    Tsao, Jen-Ching

    2016-01-01

    New guidance of acceptable means of compliance with the super-cooled large drops (SLD) conditions has been issued by the U.S. Department of Transportation's Federal Aviation Administration (FAA) in its Advisory Circular AC 25-28 in November 2014. The Part 25, Appendix O is developed to define a representative icing environment for super-cooled large drops. Super-cooled large drops, which include freezing drizzle and freezing rain conditions, are not included in Appendix C. This paper reports results from recent glaze icing scaling tests conducted in NASA Glenn Icing Research Tunnel (IRT) to evaluate how well the scaling methods recommended for Appendix C conditions might apply to SLD conditions. The models were straight NACA 0012 wing sections. The reference model had a chord of 72 in. and the scale model had a chord of 21 in. Reference tests were run with airspeeds of 100 and 130.3 kn and with MVD's of 85 and 170 micron. Two scaling methods were considered. One was based on the modified Ruff method with scale velocity found by matching the Weber number WeL. The other was proposed and developed by Feo specifically for strong glaze icing conditions, in which the scale liquid water content and velocity were found by matching reference and scale values of the nondimensional water-film thickness expression and the film Weber number Wef. All tests were conducted at 0 deg AOA. Results will be presented for stagnation freezing fractions of 0.2 and 0.3. For nondimensional reference and scale ice shape comparison, a new post-scanning ice shape digitization procedure was developed for extracting 2-D ice shape profiles at any selected span-wise location from the high fidelity 3-D scanned ice shapes obtained in the IRT.

  20. Determination of critical length scales for corrosion processes using microelectroanalytical techniques.

    SciTech Connect

    Zavadil, Kevin Robert; Wall, Frederick Douglas

    2004-03-01

    A key factor in our ability to produce and predict the stability of metal-based macro- to nano-scale structures and devices is a fundamental understanding of the localized nature of corrosion. Corrosion processes where physical dimensions become critical in the degradation process include localized corrosion initiation in passivated metals, microgalvanic interactions in metal alloys, and localized corrosion in structurally complex materials like nanocrystalline metal films under atmospheric and inundated conditions. This project focuses on two areas of corrosion science where a fundamental understanding of processes occurring at critical dimensions is not currently available. Sandia will study the critical length scales necessary for passive film breakdown in the inundated aluminum (Al) system and the chemical processes and transport in ultra-thin water films relevant to the atmospheric corrosion of nanocrystalline tungsten (W) films. Techniques are required that provide spatial information without significantly perturbing or masking the underlying relationships. Al passive film breakdown is governed by the relationship between area of the film sampled and its defect structure. We will combine low current measurements with microelectrodes to study the size scale required to observe a single initiation event and record electrochemical breakdown events. The resulting quantitative measure of stability will be correlated with metal grain size, secondary phase size and distribution to understand which metal properties control stability at the macro- and nano-scale. Mechanisms of atmospheric corrosion on W are dependent on the physical dimensions and continuity of adsorbed water layers as well as the chemical reactions that take place in this layer. We will combine electrochemical and scanning probe microscopic techniques to monitor the chemistry and resulting material transport in these thin surface layers. A description of the length scales responsible for driving the

  1. A Generic Length-scale Equation For Second-order Turbulence Models of Oceanic Boundary Layers

    NASA Astrophysics Data System (ADS)

    Umlauf, L.; Burchard, H.

    A generic transport equation for a generalized length-scale in second-order turbulence closure models for geophysical boundary layers is suggested. This variable consists of the products of powers of the turbulent kinetic energy, k, and the integral length-scale, l. The new approach generalizes traditional second-order models used in geophysical boundary layer modelling, e.g. the Mellor-Yamada model and the k- model, which, however, can be recovered as special cases. It is demonstrated how this new model can be calibrated with measurements in some typical geophysical boundary layer flows. As an example, the generic model is applied to the uppermost oceanic boundary layer directly influenced by the effects of breaking surface waves. Recent measurements show that in this layer the classical law of the wall is invalid, since there turbulence is dominated by turbulent transport of TKE from above, and not by shear-production. A widely accepted approach to describe the wave-affected layer with a one-equation turbulence model was suggested by Craig and Banner (1994). Here, some deficien- cies of their solutions are pointed out and a generalization of their ideas for the case of two-equation models is suggested. Direct comparison with very recently obtained measurements of the dissipation rate, , in the wave-affected boundary layer with com- puted results clearly demonstrate that only the generic two-equation model yields cor- rect predictions for the profiles of and the turbulent length scale, l. Also, the pre- dicted velocity profiles in the wave-affected layer, important e.g. for the interpretation of surface drifter experiments, are reproduced correctly only by the generic model. Implementation and computational costs of the generic model are comparable with traditonal two-equation models.

  2. Atmospheric lateral and longitudinal turbulent length scales (measured at 600 to 800 meters above grade level)

    NASA Technical Reports Server (NTRS)

    Cliff, W. C.; Skarda, J. R.

    1987-01-01

    NASA's Airborne Doppler Lidar System has been used to obtain a detailed 'instantaneous' mapping of horizontal spatial wind fields at 600-800 m elevations on the east side of the San Gorgonio Pass in California, in the form of checkerboard-fashion horizontal wind vectors spaced at 300 m intervals along and normal to the flight path. Spatial autocorrelations for the lateral and longitudinal components are ensemble-averaged, and integral turbulent length scales are computed for the wind fields' longitudinal and lateral directions. The flow in the region studied does not appear to be isotropic.

  3. Explanation of the values of Hack's drainage basin, river length scaling exponent

    NASA Astrophysics Data System (ADS)

    Hunt, A. G.

    2015-08-01

    Percolation theory can be used to find water flow paths of least resistance. The application of percolation theory to drainage networks allows identification of the range of exponent values that describe the tortuosity of rivers in real river networks, which is then used to generate the observed scaling between drainage basin area and channel length, a relationship known as Hack's law. Such a theoretical basis for Hack's law allows interpretation of the range of exponent values based on an assessment of the heterogeneity of the substrate.

  4. Brief communication: Possible explanation of the values of Hack's drainage basin, river length scaling exponent

    NASA Astrophysics Data System (ADS)

    Hunt, Allen G.

    2016-04-01

    Percolation theory can be used to find water flow paths of least resistance. Application of percolation theory to drainage networks allows identification of the range of exponent values that describe the tortuosity of rivers in real river networks, which is then used to generate the observed scaling between drainage basin area and channel length, a relationship known as Hack's law. Such a theoretical basis for Hack's law may allow interpretation of the range of exponent values based on an assessment of the heterogeneity of the substrate.

  5. Temperature gradient scale length measurement: A high accuracy application of electron cyclotron emission without calibration

    NASA Astrophysics Data System (ADS)

    Houshmandyar, S.; Yang, Z. J.; Phillips, P. E.; Rowan, W. L.; Hubbard, A. E.; Rice, J. E.; Hughes, J. W.; Wolfe, S. M.

    2016-11-01

    Calibration is a crucial procedure in electron temperature (Te) inference from a typical electron cyclotron emission (ECE) diagnostic on tokamaks. Although the calibration provides an important multiplying factor for an individual ECE channel, the parameter ΔTe/Te is independent of any calibration. Since an ECE channel measures the cyclotron emission for a particular flux surface, a non-perturbing change in toroidal magnetic field changes the view of that channel. Hence the calibration-free parameter is a measure of Te gradient. BT-jog technique is presented here which employs the parameter and the raw ECE signals for direct measurement of electron temperature gradient scale length.

  6. Lab on a chip Canada--rapid diffusion over large length scales.

    PubMed

    Juncker, David; Wheeler, Aaron R; Sinton, David

    2013-07-01

    The roots of lab on a chip in Canada are deep, comprising of some of the earliest contributions and first demonstrations of the potential of microfluidic chips. In an editorial leading off this special issue, Jed Harrison of University of Alberta reflects on these early days and Canada's role in the field's development (DOI: 10.1039/c3lc50522g). Over the last decade, microfluidics and lab-on-a-chip research efforts grew exponentially - rapidly diffusing across the vast Canadian length scales.

  7. KL4 Peptide Induces Reversible Collapse Structures on Multiple Length Scales in Model Lung Surfactant

    PubMed Central

    Holten-Andersen, Niels; Michael Henderson, J.; Walther, Frans J.; Waring, Alan J.; Ruchala, Piotr; Notter, Robert H.; Lee, Ka Yee C.

    2011-01-01

    We investigated the effects of KL4, a 21-residue amphipathic peptide approximating the overall ratio of positively charged to hydrophobic amino acids in surfactant protein B (SP-B), on the structure and collapse of dipalmitoylphosphatidylcholine and palmitoyl-oleoyl-phosphatidylglycerol monolayers. As reported in prior work on model lung surfactant phospholipid films containing SP-B and SP-B peptides, our experiments show that KL4 improves surfactant film reversibility during repetitive interfacial cycling in association with the formation of reversible collapse structures on multiple length scales. Emphasis is on exploring a general mechanistic connection between peptide-induced nano- and microscale reversible collapse structures (silos and folds). PMID:22208194

  8. Length Scale Dependence of the Dynamic Properties of Hyaluronic Acid Solutions in the Presence of Salt

    SciTech Connect

    Horkay, Ferenc; Falus, Peter; Hecht, Anne-Marie; Geissler, Erik

    2010-12-07

    In solutions of the charged semirigid biopolymer hyaluronic acid in salt-free conditions, the diffusion coefficient D{sub NSE} measured at high transfer momentum q by neutron spin echo is more than an order of magnitude smaller than that determined by dynamic light scattering, D{sub DLS}. This behavior contrasts with neutral polymer solutions. With increasing salt content, D{sub DLS} approaches D{sub NSE}, which is independent of ionic strength. Contrary to theoretical expectation, the ion-polymer coupling, which dominates the low q dynamics of polyelectrolyte solutions, already breaks down at distance scales greater than the Debye-Hueckel length.

  9. Localization and length-scale doubling in disordered films on soft substrates

    NASA Astrophysics Data System (ADS)

    Semler, Matthew R.; Harris, John M.; Croll, Andrew B.; Hobbie, Erik K.

    2013-09-01

    Wrinkling and folding are examined experimentally for three distinct types of disordered films on polydimethylsiloxane (PDMS) substrates; diblock copolymers, glassy polymers, and single-wall carbon nanotubes. All three of these systems exhibit localization and length-scale doubling at small strains, and we qualitatively account for these observations with a simple physical argument related to the width of the stress correlation function and the interaction of localization sites. Our results have relevance to wrinkling and folding in a diverse array of disordered films on soft substrates, and the insights offered here should help guide the development of theoretical models for the influence of structural disorder on thin-film wrinkling instabilities.

  10. Influence of dust particles on the absorption scale length of snow

    NASA Astrophysics Data System (ADS)

    Kaufmann, E.; Hagermann, A.

    2014-04-01

    In contrast to rock and soil surface layers, which absorb and reflect incoming solar radiation immediately at the surface, ices are partially transparent in the visible spectral range, while they are opaque in the infrared. These properties are responsible for the "Solid-State Greenhouse Effect" (SSGE), which may play an important role in the energy balance of icy surfaces in the solar system. To model the SSGE, we need to know not only thermal properties but also optical properties like the albedo and the absorption scale length of the ice. Within the scope of a project conducted at the Open University (UK), a series of tests measuring the e-folding scales of snow/dust mixtures was done.

  11. Relations between overturning length scales at the Spanish planetary boundary layer

    NASA Astrophysics Data System (ADS)

    López, Pilar; Cano, José L.

    2016-04-01

    We analyze the behavior of the maximum Thorpe displacement (dT)max and the Thorpe scale LTat the atmospheric boundary layer (ABL), extending previous research with new data and improving our studies related to the novel use of the Thorpe method applied to ABL. The maximum Thorpe displacements vary between -900 m and 950 m for the different field campaigns. The maximum Thorpe displacement is always greater under convective conditions than under stable ones, independently of its sign. The Thorpe scale LT ranges between 0.2 m and 680 m for the different data sets which cover different stratified mixing conditions (turbulence shear-driven and convective regions). The Thorpe scale does not exceed several tens of meters under stable and neutral stratification conditions related to instantaneous density gradients. In contrast, under convective conditions, Thorpe scales are relatively large, they exceed hundreds of meters which may be related to convective bursts. We analyze the relation between (dT)max and the Thorpe scale LT and we deduce that they verify a power law. We also deduce that there is a difference in exponents of the power laws for convective conditions and shear-driven conditions. These different power laws could identify overturns created under different mechanisms. References Cuxart, J., Yagüe, C., Morales, G., Terradellas, E., Orbe, J., Calvo, J., Fernández, A., Soler, M., Infante, C., Buenestado, P., Espinalt, Joergensen, H., Rees, J., Vilà, J., Redondo, J., Cantalapiedra, I. and Conangla, L.: Stable atmospheric boundary-layer experiment in Spain (Sables 98). A report, Boundary-Layer Meteorology, 96, 337-370, 2000. Dillon, T. M.: Vertical Overturns: A Comparison of Thorpe and Ozmidov Length Scales, J. Geophys. Res., 87(C12), 9601-9613, 1982. Itsweire, E. C.: Measurements of vertical overturns in stably stratified turbulent flow, Phys. Fluids, 27(4), 764-766, 1984. Kitade, Y., Matsuyama, M. and Yoshida, J.: Distribution of overturn induced by internal

  12. Eating Disorder Diagnostic Scale: Additional Evidence of Reliability and Validity

    ERIC Educational Resources Information Center

    Stice, Eric; Fisher, Melissa; Martinez, Erin

    2004-01-01

    The authors conducted 4 studies investigating the reliability and validity of the Eating Disorder Diagnostic Scale (HDDS; E. Stice, C. F. Telch, & S. L. Rizvi, 2000), a brief self-report measure for diagnosing anorexia nervosa, bulimia nervosa, and binge eating disorder. Study 1 found that the HDDS showed criterion validity with interview-based…

  13. Identifying and characterising the different structural length scales in liquids and glasses: an experimental approach.

    PubMed

    Salmon, Philip S; Zeidler, Anita

    2013-10-01

    The structure of several network-forming liquids and glasses is considered, where a focus is placed on the detailed information that is made available by using the method of neutron diffraction with isotope substitution (NDIS). In the case of binary network glass-forming materials with the MX2 stoichiometry (e.g. GeO2, GeSe2, ZnCl2), two different length scales at distances greater than the nearest-neighbour distance manifest themselves by peaks in the measured diffraction patterns. The network properties are influenced by a competition between the ordering on these "intermediate" and "extended" length scales, which can be manipulated by changing the chemical identity of the atomic constituents or by varying state parameters such as the temperature and pressure. The extended-range ordering, which describes the decay of the pair-correlation functions at large-r, can be represented by making a pole analysis of the Ornstein-Zernike equations, an approach that can also be used to describe the large-r behaviour of the pair-correlation functions for liquid and amorphous metals where packing constraints are important. The first applications are then described of the NDIS method to measure the detailed structure of aerodynamically-levitated laser-heated droplets of "fragile" glass-forming liquid oxides (CaAl2O4 and CaSiO3) at high-temperatures (~2000 K) and the structure of a "strong" network-forming glass (GeO2) under pressures ranging from ambient to ~8 GPa. The high-temperature experiments show structural changes on multiple length scales when the oxides are vitrified. The high-pressure experiment offers insight into the density-driven mechanisms of network collapse in GeO2 glass, and parallels are drawn with the high-pressure behaviour of silica glass. Finally, the hydrogen-bonded network of water is considered, where the first application of the method of oxygen NDIS is used to measure the structures of light versus heavy water and a difference of approximately equal

  14. Strain rate, temperature and representative length scale influence on plasticity and yield stress in copper

    SciTech Connect

    Dupont, Virginie; Germann, Timothy C

    2011-01-18

    Shock compression of materials constitutes a complex process involving high strain rates, elevated temperatures and compression of the lattice. Materials properties are greatly affected by temperature, the representative length scale and the strain rate of the deformation. Experimentally, it is difficult to study the dynamic microscopic mechanisms that affect materials properties following high intensity shock loading, but they can be investigated using molecular dynamics (MD) simulations. Moreover, MD allows a better control over some parameters. We are using MD simulations to study the effect of the strain rate, representative length scale and temperature on the properties of metals during compression. A half-million-atom Cu sample is subjected to strain rates ranging from 10{sup 7} s{sup -1} to 10{sup 12} s{sup -1} at different temperatures ranging from 50K to 1500K. Single crystals as well as polycrystals are investigated. Plasticity mechanisms as well as the evolution of the micro- and macro-yield stress are observed. Our results show that the yield stress increases with increasing strain rate and decreasing temperature. We also show that the strain rate at which the transition between constant and increasing yield stress as a function of the temperature occurs increases with increasing temperature. Calculations at different grain sizes will give an insight into the grain size effect on the plasticity mechanisms and the yield stress.

  15. Thermal conductivity of semiconductor nanowires from micro to nano length scales

    NASA Astrophysics Data System (ADS)

    Maldovan, Martin

    2012-01-01

    We study the influence of phonon boundary scattering on the transport of thermal energy in semiconductor nanowires from micro to nano length scales. We use a kinetic theory model based on the Boltzmann transport equation that accurately calculates the reduction of the phonon mean free paths by considering their directional dependence and the fundamental statistical definition of the mean free path. As a result, our model does not use phenomenological formulas to account for the reduction of the phonon mean free paths due to boundary scattering. The transport of thermal energy is also fully divided into that carried by different polarizations by separating phonon group velocities and relaxation times for transverse and longitudinal phonons. We study the correctness of using frequency independent versus frequency dependent models for describing the specularity of the nanowire boundary. We also examine the validity of the assumption that phonons in the semiconductor nanowire maintain their bulk phonon dispersion relations and that modifications to the dispersion relations due to phonon confinement effects can be neglected. The thermal conductivities of silicon nanowires are calculated for different length scales and temperatures and good agreement is obtained with experiments. The theoretical results in this paper can be used to understand and quantitatively predict heat transport in nanowires, which is critical for increasing the efficiency of thermoelectric and electronic devices.

  16. The role of elastic anisotropy, length scale and crystallographic slip in fatigue crack nucleation

    NASA Astrophysics Data System (ADS)

    Sweeney, C. A.; Vorster, W.; Leen, S. B.; Sakurada, E.; McHugh, P. E.; Dunne, F. P. E.

    2013-05-01

    Fatigue crack nucleation in polycrystal ferritic steel is investigated through experimental observation of multiple large-grained, notched, four-point bend tests combined with explicit microstructural representation of the same samples using crystal plasticity finite element techniques in order to assess fatigue indicator parameters, together with the roles of elastic anisotropy and length scale effects in slip development, and hence in crack nucleation. Elastic anisotropy has been demonstrated to play a pivotal role in the distribution and magnitude of polycrystal slip relative to observed crack nucleation sites in the context of constrained cyclic microplasticity. Length scale effects were found not to alter substantively the distributions or magnitudes of slip relative to the observed crack nucleation site, but in detailed analyses of an experimental sample, the location of highest magnitude of geometrically necessary dislocations was found to coincide precisely with the position of predicted peak plasticity and the experimentally observed crack nucleation site. The distributions of microplasticity within polycrystal samples were found to change quite significantly between the first yield and after multiple cycles. As a result, the effective plastic strain per cycle was found to be a better indicator of fatigue crack nucleation than peak effective plastic strain. In nine independently tested and analysed polycrystal samples, the cyclic effective plastic strain and crystallographic system peak accumulated slip were found to be good indicators of a fatigue crack nucleation site.

  17. Short length scale mantle heterogeneity beneath Iceland probed by glacial modulation of melting

    NASA Astrophysics Data System (ADS)

    Sims, Kenneth W. W.; Maclennan, John; Blichert-Toft, Janne; Mervine, Evelyn M.; Blusztajn, Jurek; Grönvold, Karl

    2013-10-01

    Glacial modulation of melting beneath Iceland provides a unique opportunity to better understand both the nature and length scale of mantle heterogeneity. At the end of the last glacial period, ∼13 000 yr BP, eruption rates were ∼20-100 times greater than in glacial or late postglacial times and geophysical modeling posits that rapid melting of the large ice sheet covering Iceland caused a transient increase in mantle decompression melting rates. Here we present the first time-series of Sr-Nd-Hf-Pb isotopic data for a full glacial cycle from a spatially confined region of basaltic volcanism in northern Iceland. Basalts and picrites erupted during the early postglacial burst of volcanic activity are systematically offset to more depleted isotopic compositions than those of lavas erupted during glacial or recent (<7 kyr) times. These new isotopic data, coupled with major and trace element data, show that the mantle underneath northern Iceland is heterogeneous on small (<100 km) length scales. The temporal response of the isotopic compositions of the basalts to glacial unloading indicates that the isotopic composition of mantle heterogeneities can be linked to their melting behavior. The present geochemical data can be accounted for by a melting model in which a lithologically heterogeneous mantle source contains an enriched component more fusible than its companion depleted component.

  18. New Large Length Scale Capillary Fluidics Investigations Using a Drop Tower

    NASA Astrophysics Data System (ADS)

    Weislogel, Mark; Wollman, Andrew; Wiles, Brentley

    2013-11-01

    Drop Towers provide brief terrestrial access to microgravity environments. When exploited for capillary fluidics research, the drop tower allows for unique control over an experiment's initial conditions which can enable, enhance, or otherwise improve methods to study capillary flows and phenomena at significantly larger length scales than can be achieved on the ground. In this work a new, highly accessible, 2.1 s tower is introduced for such research. Enabled in part by simple macro-fabrication methods, a variety of new demonstrative experiments are presented for purely capillarity-driven flows leading to droplet ejections, bubble ingestions, sinking flows, particle injections, and multiphase flows. Due to the repeatability of the passive flows, each experiment may be used in turn as a means to study other phenomena and forward-looking research themes are suggested that include large length scale passive phase separations, heat and mass transfer, droplet dynamics, combustion, and more. NASA NNX09AP66A Glenn Research Center, NASA NNX10AK68H Oregon Space Grant Consortium.

  19. Large-Scale Spray Releases: Additional Aerosol Test Results

    SciTech Connect

    Daniel, Richard C.; Gauglitz, Phillip A.; Burns, Carolyn A.; Fountain, Matthew S.; Shimskey, Rick W.; Billing, Justin M.; Bontha, Jagannadha R.; Kurath, Dean E.; Jenks, Jeromy WJ; MacFarlan, Paul J.; Mahoney, Lenna A.

    2013-08-01

    One of the events postulated in the hazard analysis for the Waste Treatment and Immobilization Plant (WTP) and other U.S. Department of Energy (DOE) nuclear facilities is a breach in process piping that produces aerosols with droplet sizes in the respirable range. The current approach for predicting the size and concentration of aerosols produced in a spray leak event involves extrapolating from correlations reported in the literature. These correlations are based on results obtained from small engineered spray nozzles using pure liquids that behave as a Newtonian fluid. The narrow ranges of physical properties on which the correlations are based do not cover the wide range of slurries and viscous materials that will be processed in the WTP and in processing facilities across the DOE complex. To expand the data set upon which the WTP accident and safety analyses were based, an aerosol spray leak testing program was conducted by Pacific Northwest National Laboratory (PNNL). PNNL’s test program addressed two key technical areas to improve the WTP methodology (Larson and Allen 2010). The first technical area was to quantify the role of slurry particles in small breaches where slurry particles may plug the hole and prevent high-pressure sprays. The results from an effort to address this first technical area can be found in Mahoney et al. (2012a). The second technical area was to determine aerosol droplet size distribution and total droplet volume from prototypic breaches and fluids, including sprays from larger breaches and sprays of slurries for which literature data are mostly absent. To address the second technical area, the testing program collected aerosol generation data at two scales, commonly referred to as small-scale and large-scale testing. The small-scale testing and resultant data are described in Mahoney et al. (2012b), and the large-scale testing and resultant data are presented in Schonewill et al. (2012). In tests at both scales, simulants were used

  20. Small-Scale Spray Releases: Additional Aerosol Test Results

    SciTech Connect

    Schonewill, Philip P.; Gauglitz, Phillip A.; Kimura, Marcia L.; Brown, G. N.; Mahoney, Lenna A.; Tran, Diana N.; Burns, Carolyn A.; Kurath, Dean E.

    2013-08-01

    One of the events postulated in the hazard analysis at the Waste Treatment and Immobilization Plant (WTP) and other U.S. Department of Energy (DOE) nuclear facilities is a breach in process piping that produces aerosols with droplet sizes in the respirable range. The current approach for predicting the size and concentration of aerosols produced in a spray leak involves extrapolating from correlations reported in the literature. These correlations are based on results obtained from small engineered spray nozzles using pure liquids with Newtonian fluid behavior. The narrow ranges of physical properties on which the correlations are based do not cover the wide range of slurries and viscous materials that will be processed in the WTP and across processing facilities in the DOE complex. To expand the data set upon which the WTP accident and safety analyses were based, an aerosol spray leak testing program was conducted by Pacific Northwest National Laboratory (PNNL). PNNL’s test program addressed two key technical areas to improve the WTP methodology (Larson and Allen 2010). The first technical area was to quantify the role of slurry particles in small breaches where slurry particles may plug the hole and prevent high-pressure sprays. The results from an effort to address this first technical area can be found in Mahoney et al. (2012a). The second technical area was to determine aerosol droplet size distribution and total droplet volume from prototypic breaches and fluids, including sprays from larger breaches and sprays of slurries for which literature data are largely absent. To address the second technical area, the testing program collected aerosol generation data at two scales, commonly referred to as small-scale and large-scale. The small-scale testing and resultant data are described in Mahoney et al. (2012b) and the large-scale testing and resultant data are presented in Schonewill et al. (2012). In tests at both scales, simulants were used to mimic the

  1. Simulation of driven self assembly of complex polymeric systems across multiple length scales

    NASA Astrophysics Data System (ADS)

    de Pablo, Juan

    2007-03-01

    The self assembly of macromolecular systems is often driven or facilitated by the application of external fields, including flow, voltage, or confinement. The structures that arise when external fields are applied often depend on the history of the sample, and it is therefore important to develop theoretical and computational methods capable of describing the order formation process across multiple length and time scales. Over the past several years we have developed several new classes of multiscale modeling techniques for study of the structure and properties of polymeric materials under external fields, including confinement or flows. For systems at equilibrium, these systems permit precise calculation of the free energy. For systems beyond equilibrium, these methods include the effects of fluctuating hydrodynamic interactions (for dilute and semidilute systems) and the effects of constraining molecules (for concentrated melts). These models and methods can be used to investigate the equilibrium structure and relaxation of a variety of fluids, including solutions of biological macromolecules. The usefulness and limitations of our proposed approach will be discussed in the context of three applications. The first application is concerned with the elongation and presentation of long DNA molecules in nanofluidic channels. A multiscale model, that includes fluctuating hydrodynamic interactions, has been used to design a gene mapping device and to interpret experimental data pertaining to the structure and dynamics of confined chromosome-length DNA. The second application is concerned with the study of liquid-crystal based biosensors. A multiscale model has been used to design a liquid-crystal based device in which nanoscale particles suspended in a liquid crystal self assemble into highly regular structures, including chains, upon exposure to proteins or virions. The third application focuses on the formation of ordered block copolymer structures on nanopatterned

  2. Correlation Length Scales of Isotopic Variations Along Mid-Ocean Ridges and Upper Mantle Dynamics

    NASA Astrophysics Data System (ADS)

    Graham, D. W.; Spera, F. J.

    2003-12-01

    How isotopic variations in basalts erupted at the Earth's surface are linked to convective mixing in the underlying mantle is a central problem in geodynamics. The objective of this study is to quantify the length scales of upper mantle heterogeneity through spatial statistical analysis of MORB. We define a characteristic length scale, the scale of segregation L, computed from the spatial self-correlations for 3He/4He, 87Sr/86Sr, 143Nd/144Nd and 206,207,208Pb/204Pb in "zero age" lavas from mid-ocean ridges. Our working hypothesis is that small scale convection in the upper mantle controls dispersion of geochemical tracers. Differences in L between ocean basins may then be quantitatively related to unsteadiness in this convection, due to thickening of the lithosphere, plume impingement, or lateral temperature/compositional differences between continental and oceanic lithosphere induced by batholith formation. The correlation coefficient R, and the separation distance r, are calculated for every i,j pair of points. Ri,j is given by the product of the deviations in isotope composition from the population mean, normalized to the population variance, and R(r) is computed as an ensemble average. The total number of point pairs (N) for n sample locations is given by N=n(n-1)/2. For the global MORB data set (n=1265 and 735 for Sr and He, respectively), N exceeds 105 (799480 and 269745, respectively). A value of R(r) close to 1 indicates that an isotope ratio above (or below) the population average is likely to be associated with an above (or below) average value at a distance r away. A value of R(r) close to zero implies a random relationship, and a value close to -1 implies an anti-correlation. R(r) approaches unity at small r by definition, as points close together are from the same "clump" of mantle. The value of r at which R first goes to zero is denoted as r*. On a diagram of R(r) vs. r (the correlogram), the integral of R(r) from r=0 to r=r* is the scale of

  3. Comet P/Halley - Spatial distributions and scale lengths for C2, CN, NH2, and H2O

    NASA Technical Reports Server (NTRS)

    Fink, Uwe; Combi, Michael R.; Disanti, Michael A.

    1991-01-01

    Long-slit spectroscopic observations of Comet P/Halley on 12 dates between October 1985 and May 1986 were used to extract spatial profiles for C2, CN, NH2, and O I (1D) (which effectively map out the comet's H2O distribution), and Haser model scale lengths were fitted to these data. The preperihelion analysis yielded Haser model scale lengths of sufficient consistency that they could be used for the production rate determinations. It was found that the average parent scale lengths found for NH2 were consistent with photodissociation lifetimes for NH3 and confirm the dissociation chain NH3-NH2-NH.

  4. Development of a scanning tunneling potentiometry system for measurement of electronic transport at short length scales

    NASA Astrophysics Data System (ADS)

    Rozler, Michael

    It is clear that complete understanding of macroscopic properties of materials is impossible without a thorough knowledge of behavior at the smallest length scales. While the past 25 years have witnessed major advances in a variety of techniques that probe the nanoscale properties of matter, electrical transport measurements -- the heart of condensed matter research -- have lagged behind, never progressing beyond bulk measurements. This thesis describes a scanning tunneling potentiometry (STP) system developed to simultaneously map the transport-related electrochemical potential distribution of a biased sample along with its surface topography, extending electronic transport measurements to the nanoscale. Combining a novel sample biasing technique with a continuous current-nulling feedback scheme pushes the noise performance of the measurement to its fundamental limit - the Johnson noise of the STM tunnel junction. The resulting 130 nV voltage sensitivity allows us to spatially resolve local potentials at scales down to 2 nm, while maintaining atomic scale STM imaging, all at scan sizes of up to 15 microns. A mm-range two-dimensional coarse positioning stage and the ability to operate from liquid helium to room temperature with a fast turn-around time greatly expand the versatility of the instrument. Use of carefully selected model materials, combined with excellent topographic and voltage resolution has allowed us to distinguish measurement artifacts caused by surface roughness from true potentiometric features, a major problem in previous STP measurements. The measurements demonstrate that STP can produce physically meaningful results for homogeneous transport as well as non-uniform conduction dominated by material microstructures. Measurements of several physically interesting materials systems are presented as well, revealing new behaviors at the smallest length sales. The results establish scanning tunneling potentiometry as a useful tool for physics and

  5. Short Length Scale Mantle Heterogeneity Beneath Iceland Probed by Glacial Modulation of Melting

    NASA Astrophysics Data System (ADS)

    Sims, K. W.; Maclennan, J.; Blichert-Toft, J.; Mervine, E. M.; Gronvold, K.

    2012-12-01

    While isotopic variability in basaltic lavas indisputably documents long-lived mantle heterogeneity, the nature of this heterogeneity (lithologic variability or cryptic metasomatism) and its length scales remain uncertain. We show that glacial modulation of melting beneath Iceland provides a unique opportunity to better understand both the nature and length scale of mantle heterogeneity. At the end of the last glacial period, ~13,000 yr BP, eruption rates were ~20-100 times greater than in glacial or late postglacial times and geophysical modeling posits that rapid melting of the large ice sheet covering Iceland caused a transient increase in decompression mantle melting. Here we present the first time-series of Sr-Nd-Hf-Pb isotopic data for a full glacial cycle (glacial-early postglacial-late postglacial/modern) from a spatially confined region of basaltic volcanism in Northern Iceland. Our new isotopic data coupled with major and trace element data for lavas from Krafla and Theistareykir allow for comparison of lava flows erupted during the early postglacial volcanic pulse, when melting rates are thought to have increased dramatically in the shallow part of the melting region, with glacial and late postglacial lavas. These new isotopic data show that the early postglacial lavas at Theistareykir and Krafla carry a larger contribution from a long-term time-averaged incompatible element-depleted source than glacial and recent lavas. This observation suggests that the mantle underneath northern Iceland is heterogeneous on small (<100 km) scales within the melting column, and that the isotopic and trace element data are best explained by melting of a lithologically heterogeneous mantle source in which the enriched component is more fusible than the depleted component. Our study of temporal variation in isotopic compositions provides important evidence of a link between isotopic and major element variations in the mantle, removing much of the ambiguity associated with

  6. Variability of interconnected wind plants: correlation length and its dependence on variability time scale

    SciTech Connect

    St. Martin, Clara M.; Lundquist, Julie K.; Handschy, Mark A.

    2015-04-02

    The variability in wind-generated electricity complicates the integration of this electricity into the electrical grid. This challenge steepens as the percentage of renewably-generated electricity on the grid grows, but variability can be reduced by exploiting geographic diversity: correlations between wind farms decrease as the separation between wind farms increases. However, how far is far enough to reduce variability? Grid management requires balancing production on various timescales, and so consideration of correlations reflective of those timescales can guide the appropriate spatial scales of geographic diversity grid integration. To answer 'how far is far enough,' we investigate the universal behavior of geographic diversity by exploring wind-speed correlations using three extensive datasets spanning continents, durations and time resolution. First, one year of five-minute wind power generation data from 29 wind farms span 1270 km across Southeastern Australia (Australian Energy Market Operator). Second, 45 years of hourly 10 m wind-speeds from 117 stations span 5000 km across Canada (National Climate Data Archive of Environment Canada). Finally, four years of five-minute wind-speeds from 14 meteorological towers span 350 km of the Northwestern US (Bonneville Power Administration). After removing diurnal cycles and seasonal trends from all datasets, we investigate dependence of correlation length on time scale by digitally high-pass filtering the data on 0.25–2000 h timescales and calculating correlations between sites for each high-pass filter cut-off. Correlations fall to zero with increasing station separation distance, but the characteristic correlation length varies with the high-pass filter applied: the higher the cut-off frequency, the smaller the station separation required to achieve de-correlation. Remarkable similarities between these three datasets reveal behavior that, if universal, could be particularly useful for grid management. For high

  7. Variability of interconnected wind plants: correlation length and its dependence on variability time scale

    NASA Astrophysics Data System (ADS)

    St. Martin, Clara M.; Lundquist, Julie K.; Handschy, Mark A.

    2015-04-01

    The variability in wind-generated electricity complicates the integration of this electricity into the electrical grid. This challenge steepens as the percentage of renewably-generated electricity on the grid grows, but variability can be reduced by exploiting geographic diversity: correlations between wind farms decrease as the separation between wind farms increases. But how far is far enough to reduce variability? Grid management requires balancing production on various timescales, and so consideration of correlations reflective of those timescales can guide the appropriate spatial scales of geographic diversity grid integration. To answer ‘how far is far enough,’ we investigate the universal behavior of geographic diversity by exploring wind-speed correlations using three extensive datasets spanning continents, durations and time resolution. First, one year of five-minute wind power generation data from 29 wind farms span 1270 km across Southeastern Australia (Australian Energy Market Operator). Second, 45 years of hourly 10 m wind-speeds from 117 stations span 5000 km across Canada (National Climate Data Archive of Environment Canada). Finally, four years of five-minute wind-speeds from 14 meteorological towers span 350 km of the Northwestern US (Bonneville Power Administration). After removing diurnal cycles and seasonal trends from all datasets, we investigate dependence of correlation length on time scale by digitally high-pass filtering the data on 0.25-2000 h timescales and calculating correlations between sites for each high-pass filter cut-off. Correlations fall to zero with increasing station separation distance, but the characteristic correlation length varies with the high-pass filter applied: the higher the cut-off frequency, the smaller the station separation required to achieve de-correlation. Remarkable similarities between these three datasets reveal behavior that, if universal, could be particularly useful for grid management. For high

  8. Large-scale statistical analysis of early failures in Cu electromigration, Part II: Scaling behavior and short-length effects

    NASA Astrophysics Data System (ADS)

    Gall, Martin; Hauschildt, Meike; Hernandez, Richard

    2010-07-01

    The first part of this study, presented in a separate paper, focused on the early failure mechanisms in down-flow electromigration. Since bimodality can occur at very small percentage levels, specific test structures were designed based on the Wheatstone Bridge technique. The use of these structures enabled a tested sample size past 800,000 for the 90 nm technology node, allowing a direct analysis of electromigration failure mechanisms at the single-digit ppm regime. The activation energy for the down-flow early failure mechanism was determined to be 0.83±0.01 eV, significantly lower than the usually reported activation energy of about 0.90 eV for electromigration-induced diffusion along Cu/SiCN interfaces. Very short experimental lifetimes due to small, slit-shaped voids under vias were found to control the chip lifetime at operating conditions. In this second part of our large-scale, statistical study, we will discuss the electromigration scaling behavior across 90, 65, and 45 nm technologies. Results indicate that the early failure mechanism follows the expected dependency, i.e., the lifetimes scale with the interconnect line height and the critical void size. The slitlike character of the early failure void morphology also raises concerns about the validity of the short-length effect for this mechanism. A very small amount of Cu depletion may cause failure even before a stress gradient is established. We therefore conducted large-scale statistical experiments close to the critical current density-length product (jL)∗. The results indicate that at very small failure percentages, the critical product extrapolates to about 2100±300 A/cm for SiCOH-based dielectrics in 90 nm technology. This value represents a decrease from the previously determined (jL)∗ product of about 3000±500 A/cm for the same dielectric material and technology node, acquired with single link interconnects. Utilizing the advantages of the Wheatstone Bridge technique, the total sample

  9. The P/Halley: Spatial distribution and scale lengths for C2, CN, NH2, and H2O

    NASA Technical Reports Server (NTRS)

    Fink, Uwe; Combi, Michael; Disanti, Michael A.

    1991-01-01

    From P/Halley long slit spectroscopic exposures on 12 dates, extending from Oct. 1985 to May 1986, spatial profiles were obtained for emissions by C2, CN, NH2, and OI(1D). Haser model scale lengths were fitted to these data. The extended time coverage allowed the checking for consistency between the various dates. The time varying production rate of P/Halley severely affected the profiles after perihelion, which is shown in two profile sequences on adjacent dates. Because of the time varying production rate, it was not possible to obtain reliable Haser model scale lengths after perihelion. The pre-perihelion analysis yielded Haser model scale lengths of sufficient consistency that they can be used for production rate determinations, whenever it is necessary to extrapolate from observed column densities within finite observing apertures. Results of scale lengths reduced to 1 AU are given and discussed.

  10. Addition of restriction fragment length polymorphism markers to the genetic linkage map of Brassica rapa L. (syn. campestris).

    PubMed

    Panigrahi, Jogeswar; Patnaik, Anjana; Kole, Phullara; Koleb, Chitta ranjan

    2009-01-01

    Genetic linkage analysis of 151 restriction fragment length polymorphism (RFLP) loci, that included eight new loci, detected by the six probes in the present study, and four trait loci including seed colour, leaf pubescence, resistance to white rust caused by Albugo candida race-2 (AC-2) and race-7 (AC-7) employing the MAPMAKER/EXP 3.0 programme led to the development of 10 linkage groups (LGs) spanning over 44.4 centiMorgan (cM) to 130.4 cM containing 9 to 22 loci and two short LGs with two or three marker loci in Brassica rapa. The enriched map covers 993.1 cM of B. rapa genome with an average marker interval of 6.41. Eight new RFLP loci occupied new map positions on five linkage groups, LG 2, 3, 6, 8 and 9. Addition of these RFLP loci led to appreciable changes in the corresponding linkage groups and resulted in an increase of the total map length by 102.8 cM and of the marker interval by 0.35 cM. Interval mapping by using the computer programme MAPMAKER/ QTL 1.1 for scanning the genetic map led to the detection of one major quantitative trait locus (QTL) in LG 4 and one minor QTL in LG 8 governing resistance to AC-7. Both QTLs contributed 7.89 to the interaction phenotype (IP) score with 96.3% genetic variation. The multi-locus model suggested additive gene action with 96.8% genetic variation.

  11. 3D X-ray Strain Microscopy in Two-Phase Composites at Submicron Length Scale

    SciTech Connect

    Barabash, Rozaliya; Bei, Hongbin; Ice, Gene E; Gao, Yanfei; Barabash, Oleg M

    2011-01-01

    Author note: Part of this research summary is based on findings first reported in Refs. [3-5, 18]. Renewed interest in composite materials is driven by the fact that their mechanical properties can be superior to those of individual constituent phases. Interfaces between the phases are the key elements responsible for the unique micro-mechanisms of plastic deformation in composites. In this study the depth-dependent residual strain distributed in the two phases and partitioned across the composite interfaces is directly measured at submicron length-scale using X-ray microdiffraction and compared to a detailed simulation within the framework of micromechanical stress analysis. Interface strength is determined from the analysis of the so-called slip zone caused by the near-surface stress relaxation. Two examples are discussed including NiAl/Mo and Ni/Mo composites.

  12. Polarized Enhanced Backscattering Spectroscopy for Characterization of Biological Tissues at Subdiffusion Length-scales.

    PubMed

    Radosevich, Andrew J; Rogers, Jeremy D; Turzhitsky, Vladimir; Mutyal, Nikhil N; Yi, Ji; Roy, Hemant K; Backman, Vadim

    2012-07-01

    Since the early 1980's, the enhanced backscattering (EBS) phenomenon has been well-studied in a large variety of non-biological materials. Yet, until recently the use of conventional EBS for the characterization of biological tissue has been fairly limited. In this work we detail the unique ability of EBS to provide spectroscopic, polarimetric, and depth-resolved characterization of biological tissue using a simple backscattering instrument. We first explain the experimental and numerical procedures used to accurately measure and model the full azimuthal EBS peak shape in biological tissue. Next we explore the peak shape and height dependencies for different polarization channels and spatial coherence of illumination. We then illustrate the extraordinary sensitivity of EBS to the shape of the scattering phase function using suspensions of latex microspheres. Finally, we apply EBS to biological tissue samples in order to measure optical properties and observe the spatial length-scales at which backscattering is altered in early colon carcinogenesis.

  13. Local transport measurements at mesoscopic length scales using scanning tunneling potentiometry.

    PubMed

    Wang, Weigang; Munakata, Ko; Rozler, Michael; Beasley, Malcolm R

    2013-06-01

    Under mesoscopic conditions, the transport potential on a thin film carrying a current is theoretically expected to bear spatial variation due to quantum interference. Scanning tunneling potentiometry is the ideal tool to investigate such variation, by virtue of its high spatial resolution. We report in this Letter the first detailed measurement of transport potential under mesoscopic conditions. Epitaxial graphene at a temperature of 17 K was chosen as the initial system for study because the characteristic transport length scales in this material are relatively large. Tip jumping artifacts are a major possible contribution to systematic errors; and we mitigate such problems by using custom-made slender and sharp tips manufactured by focused ion beam. In our data, we observe residual resistivity dipoles associated with topographical defects, and local peaks and dips in the potential that are not associated with topographical defects.

  14. Advancing the speed, sensitivity and accuracy of biomolecular detection using multi-length-scale engineering

    NASA Astrophysics Data System (ADS)

    Kelley, Shana O.; Mirkin, Chad A.; Walt, David R.; Ismagilov, Rustem F.; Toner, Mehmet; Sargent, Edward H.

    2014-12-01

    Rapid progress in identifying disease biomarkers has increased the importance of creating high-performance detection technologies. Over the last decade, the design of many detection platforms has focused on either the nano or micro length scale. Here, we review recent strategies that combine nano- and microscale materials and devices to produce large improvements in detection sensitivity, speed and accuracy, allowing previously undetectable biomarkers to be identified in clinical samples. Microsensors that incorporate nanoscale features can now rapidly detect disease-related nucleic acids expressed in patient samples. New microdevices that separate large clinical samples into nanocompartments allow precise quantitation of analytes, and microfluidic systems that utilize nanoscale binding events can detect rare cancer cells in the bloodstream more accurately than before. These advances will lead to faster and more reliable clinical diagnostic devices.

  15. Measurement of growing dynamical length scale on approach to jamming in granular systems

    NASA Astrophysics Data System (ADS)

    Durian, Douglas

    2009-03-01

    The flow of granular materials is of widespread practical and fundamental interest. One challenge to understanding and controlling behavior is that the response is nonlinear, with a forcing threshold below which the medium is static. Furthermore, just above threshold the response may be intermittent even though the forcing is steady. Two familiar examples are avalanches on a heap and clogging in a silo. Another example is dynamical heterogeneities for systems brought close to jamming, where intermediate-time motion is correlated in the form of intermitted string-like swirls. Here this will be illustrated with experiments on air-driven beads, where jamming is approached by lowering the effective temperature, as well as by experiments on rapid heap flow, where jamming is approached as a function of depth from the free surface. Use of novel statistical quantities and optical spectroscopies reveal a growing dynamical length scale on approach to jamming. Collaborators: Adam Abate, Hiroaki Katsuragi, Aaron Keys, Sharon Glotzer.

  16. Indentation size effects in polydimethylsiloxane at micro- and nanometer length scales

    NASA Astrophysics Data System (ADS)

    Wrucke, Andrew J.

    2011-12-01

    Previous indentation testing on polydimethylsiloxane (PDMS) has shown amazing size dependent deformation at the micro- and millimeter length scales. PDMS is a soft silicone elastomer which has been previously investigated to lesser degrees. Nano- and micro-indentation tests have been conducted on two different PDMS formulations to study the universal hardness and elastic modulus at various indentation depths and crosslink densities to study the indentation size effects within the polymer. In these experiments, PDMS exhibited an 80 fold increase in hardness over the indentation depth range of 200 nm to 120 microm. The indentation size effects are analyzed with respect to theoretical models that rationalizes the size dependent deformation rotation gradients caused by indentation work and corresponding molecular mechanisms. The rationale is discussed in view of other experiments and explanations in the literature.

  17. Local Transport Measurements at Mesoscopic Length Scales Using Scanning Tunneling Potentiometry

    NASA Astrophysics Data System (ADS)

    Wang, Weigang; Munakata, Ko; Rozler, Michael; Beasley, Malcolm R.

    2013-06-01

    Under mesoscopic conditions, the transport potential on a thin film carrying a current is theoretically expected to bear spatial variation due to quantum interference. Scanning tunneling potentiometry is the ideal tool to investigate such variation, by virtue of its high spatial resolution. We report in this Letter the first detailed measurement of transport potential under mesoscopic conditions. Epitaxial graphene at a temperature of 17 K was chosen as the initial system for study because the characteristic transport length scales in this material are relatively large. Tip jumping artifacts are a major possible contribution to systematic errors; and we mitigate such problems by using custom-made slender and sharp tips manufactured by focused ion beam. In our data, we observe residual resistivity dipoles associated with topographical defects, and local peaks and dips in the potential that are not associated with topographical defects.

  18. Turbulent transport and length scale measurement experiments with comfined coaxial jets

    NASA Technical Reports Server (NTRS)

    Johnson, B. V.; Roback, R.

    1984-01-01

    A three phase experimental study of mixing downstream of swirling and nonswirling confined coaxial jets was conducted to obtain data for the evaluation and improvement of turbulent transport models currently employed in a variety of computational procedures. The present effort was directed toward the acquisition of length scale and dissipation rate data that provide more accurate inlet boundary conditions for the computational procedures and a data base to evaluate the turbulent transport models in the near jet region where recirculation does not occur, and the acquisition of mass and momentum turbulent transport data for a nonswirling flow condition with a blunt inner jet inlet configuration rather than the tapered inner jet inlet. A measurement technique, generally used to obtain approximate integral length and microscales of turbulence and dissipation rates, was computerized. Results showed the dissipation rate varied by 2 1/2 orders of magnitude across the inlet plane, by 2 orders of magnitude 51 mm from the inlet plane, and by 1 order of magnitude at 102 mm from the inlet plane for a nonswirling flow test conditions.

  19. THE DURABILITY OF LARGE-SCALE ADDITIVE MANUFACTURING COMPOSITE MOLDS

    SciTech Connect

    Post, Brian K; Love, Lonnie J; Duty, Chad; Vaidya, Uday; Pipes, R. Byron; Kunc, Vlastimil

    2016-01-01

    Oak Ridge National Laboratory s Big Area Additive Manufacturing (BAAM) technology permits the rapid production of thermoplastic composite molds using a carbon fiber filled Acrylonitrile-Butadiene-Styrene (ABS) thermoplastic. Demonstration tools (i.e. 0.965 m X 0.559 m X 0.152 m) for composite part fabrication have been printed, coated, and finished with a traditional tooling gel. We present validation results demonstrating the stability of thermoplastic printed molds for room temperature Vacuum Assisted Resin Transfer Molding (VARTM) processes. Arkema s Elium thermoplastic resin was investigated with a variety of reinforcement materials. Experimental results include dimensional characterization of the tool surface using laser scanning technique following demolding of 10 parts. Thermoplastic composite molds offer rapid production compared to traditionally built thermoset molds in that near-net deposition allows direct digital production of the net geometry at production rate of 45 kg/hr.

  20. Turbulence length scales in stably stratified free shear flow analyzed from slant aircraft profiles

    SciTech Connect

    Tjernstroem, M. )

    1993-05-01

    The vertical turbulence structure in the marine atmosphere close to a coastline is investigated using airborne measurements. The measurements are from a field experiment close to the coast in the southeast of Sweden, in the Baltic Sea. The Baltic Sea has two main properties that make it particularly interesting to study: significant annual lag in sea surface temperature compared to inland surface temperatures and the fact that it is surrounded by land in all directions within advection distances of from a few hours up to 10-15 hours in normal meteorological conditions. The present results are mostly from spring or early summer with mainly cool water: with a stable or neutral marine boundary layer but with substantial heating of the land area during daytime. When the daytime inland convective boundary layer is advected out over the cool sea, there is a frictional decoupling in space analogous to the same nocturnal process in time. This sometimes creates a residual layer, a remnant of the inland convective boundary layer, that can be advected for considerable distances over the sea. At the top of this layer, wind shear gives rise to a local increase in turbulent kinetic energy. These layers are used for an analysis of turbulent scales for free shear flow in stable stratification. The analysis is based on different length scales used in numerical model closures for turbulence processes and reveals the asymptotic behavior of different scales in the neutral limit and their functional form, and illustrates the nonlinear relationship between scales for different properties. The profiles from the aircraft are taken from 25 slant soundings performed in connection to low-level boundary-layer flights. The results are calculated from turbulence data extracted through filtering techniques on instantaneous time series (individual profiles). The calculated turbulence parameters from all profiles are grouped and averaged compositely over all profiles. 48 refs., 12 figs., 1 tab.

  1. Experimental determination of the cooperative length scale of a glass-forming liquid near the glass transition temperature

    NASA Astrophysics Data System (ADS)

    Rizos, A. K.; Ngai, K. L.

    1999-01-01

    Photon correlation spectroscopy and dielectric relaxation are used to examine the molecular reorientation relaxation dynamics of a fragile glass-forming liquid Aroclor (a mixture of polychlorinated biphenyls), modified by the addition of low- and high-molecular-weight polyisoprene and polybutadiene as a function of temperature and polymer solute concentration. Concentration fluctuation contributes a temperature-dependent broadening of the relaxation spectrum of Aroclor. The rate of change of the Aroclor relaxation spectrum with temperature is more pronounced when the polymers added are of low molecular weight and exhibits a steplike decrease in the neighborhood of some characteristic molecular weight. The radius of gyration of the polymer with this characteristic molecular weight is about 15 Å, which determines the cooperative length scale L(T) of Aroclor to be approximately 30 Å near and above the glass transition temperature.

  2. Influence of Growth Rate on Microstructural Length Scales in Directionally Solidified NiAl-Mo Hypo-Eutectic Alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Jianfei; Ma, Xuewei; Ren, Huiping; Chen, Lin; Jin, Zili; Li, Zhenliang; Shen, Jun

    2016-01-01

    In this article, the Ni-46.1Al-7.8Mo (at.%) alloy was directionally solidified at different growth rates ranging from 15 μm/s to 1000 μm/s under a constant temperature gradient (334 K/cm). The dependence of microstructural length scales on the growth rate was investigated. The results show that, with the growth rate increasing, the primary dendritic arm spacings (PDAS) and secondary dendritic arm spacings (SDAS) decreased. There exists a large distribution range in PDAS under directional solidification conditions at a constant temperature gradient. The average PDAS and SDAS as a function of growth rate can be given as λ1 = 848.8967 V-0.4509 and λ2 = 64.2196 V-0.4140, respectively. In addition, a comparison of our results with the current theoretical models and previous experimental results has also been made.

  3. Influence of the course boundary value problem on length scale parmeters for second-gradient continuum theories

    SciTech Connect

    Luscher, Darby J; Bronkhorst, Curt A; Mc Dowell, David L

    2010-12-20

    All nonlocal continuum descriptions of inelastic material response involve length scale parameters that either directly or implicitly quantify the physical dimensions of a neighborhood of response which influences the behavior at a particular point. The second-gradient continuum theories such as those developed by Germain, Toupin and Mindlin, and Eringen, and giving rise to strain-gradient plasticity, is becoming a common coarse-scale basis for homogenization of material response that respects the non local nature of heterogeneous material response. Ideally, the length scale parameters involved in such homogenization would be intrinsically associated with dominant aspects of the microstructure. However, these parameters, at least in some cases, are inextricably linked to the details of the coarse scale boundary value problem. Accordingly, they cannot be viewed as pure constitutive parameters. An example problem of multiscale homogenization is presented to underscore the dependence of second-gradient length scale parameters on the coarse scale boundary value problem, namely the multiscale response of an idealized porous microstructure. The fine scale (microstructure) comprises elastic perfectly plastic matrix with a periodic array of circular voids. This fine scale description of the problem is identical for two separate classes of coarse scale boundary value problem, viz. an extruded channel subject to compression and eventually developing plastic shear bands and a thin layer of material with larger (coarse scale) elliptical voids subject to shear deformation. Implications of the relationship between length scale parameters and the details of the coarse scale boundary value problem are discussed and ideas to ascertain such length parameters from evolving response fields are presented.

  4. Scrape-off Layer Flows With Pressure Gradient Scale Length ~ {rho}{sub p}

    SciTech Connect

    Robert J. Goldston

    2013-03-08

    A heuristic model for the plasma scrape-off width balances magnetic drifts against parallel loss at c{sub s} /2, resulting in a SOL width ~ {rho}{sub p}. T{sub sep} is calculated from Spitzer–Härm parallel thermal conduction. This results in a prediction for the power scrape-off width in quantitative agreement both in magnitude and scaling with recent experimental data. To achieve the ~ c{sub s} /2 flow assumed in this model and measured experimentally sets requirements on the ratio of upstream to total SOL particle sources, relative to the square-root of the ratio of target to upstream temperature. The Pfisch-Schlüter model for equilibrium flows has been modified to allow near-sonic flows, appropriate for gradient scale lengths of order {rho}{sub p}, resulting in a new quadrupole radial flow pattern. The strong parallel flows and plasma charging implied by this model suggest a mechanism for H-mode transition, consistent with many observations

  5. Zebrafish brain mapping--standardized spaces, length scales, and the power of N and n.

    PubMed

    Hunter, Paul R; Hendry, Aenea C; Lowe, Andrew S

    2015-06-01

    Mapping anatomical and functional parameters of the zebrafish brain is moving apace. Research communities undertaking such studies are becoming ever larger and more diverse. The unique features, tools, and technologies associated with zebrafish are propelling them as the 21st century model organism for brain mapping. Uniquely positioned as a vertebrate model system, the zebrafish enables imaging of anatomy and function at different length scales from intraneuronal compartments to sparsely distributed whole brain patterns. With a variety of diverse and established statistical modeling and analytic methods available from the wider brain mapping communities, the richness of zebrafish neuroimaging data is being realized. The statistical power of population observations (N) within and across many samples (n) projected onto a standardized space will provide vast databases for data-driven biological approaches. This article reviews key brain mapping initiatives at different levels of scale that highlight the potential of zebrafish brain mapping. By way of introduction to the next wave of brain mappers, an accessible introduction to the key concepts and caveats associated with neuroimaging are outlined and discussed.

  6. A phenomenological description of BslA assemblies across multiple length scales.

    PubMed

    Morris, Ryan J; Bromley, Keith M; Stanley-Wall, Nicola; MacPhee, Cait E

    2016-07-28

    Intrinsically interfacially active proteins have garnered considerable interest recently owing to their potential use in a range of materials applications. Notably, the fungal hydrophobins are known to form robust and well-organized surface layers with high mechanical strength. Recently, it was shown that the bacterial biofilm protein BslA also forms highly elastic surface layers at interfaces. Here we describe several self-assembled structures formed by BslA, both at interfaces and in bulk solution, over a range of length scales spanning from nanometres to millimetres. First, we observe transiently stable and highly elongated air bubbles formed in agitated BslA samples. We study their behaviour in a range of solution conditions and hypothesize that their dissipation is a consequence of the slow adsorption kinetics of BslA to an air-water interface. Second, we describe elongated tubules formed by BslA interfacial films when shear stresses are applied in both a Langmuir trough and a rheometer. These structures bear a striking resemblance, although much larger in scale, to the elongated air bubbles formed during agitation. Taken together, this knowledge will better inform the conditions and applications of how BslA can be used in the stabilization of multi-phase materials.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'.

  7. Quantifying Contributions to Transport in Ionic Polymers Across Multiple Length Scales

    NASA Astrophysics Data System (ADS)

    Madsen, Louis

    Self-organized polymer membranes conduct mobile species (ions, water, alcohols, etc.) according to a hierarchy of structural motifs that span sub-nm to >10 μm in length scale. In order to comprehensively understand such materials, our group combines multiple types of NMR dynamics and transport measurements (spectroscopy, diffusometry, relaxometry, imaging) with structural information from scattering and microscopy as well as with theories of porous media,1 electrolytic transport, and oriented matter.2 In this presentation, I will discuss quantitative separation of the phenomena that govern transport in polymer membranes, from intermolecular interactions (<= 2 nm),3 to locally ordered polymer nanochannels (a few to 10s of nm),2 to larger polymer domain structures (10s of nm and larger).1 Using this multi-scale information, we seek to give informed feedback on the design of polymer membranes for use in, e . g . , efficient batteries, fuel cells, and mechanical actuators. References: [1] J. Hou, J. Li, D. Mountz, M. Hull, and L. A. Madsen. Journal of Membrane Science448, 292-298 (2013). [2] J. Li, J. K. Park, R. B. Moore, and L. A. Madsen. Nature Materials 10, 507-511 (2011). [3] M. D. Lingwood, Z. Zhang, B. E. Kidd, K. B. McCreary, J. Hou, and L. A. Madsen. Chemical Communications 49, 4283 - 4285 (2013).

  8. A phenomenological description of BslA assemblies across multiple length scales.

    PubMed

    Morris, Ryan J; Bromley, Keith M; Stanley-Wall, Nicola; MacPhee, Cait E

    2016-07-28

    Intrinsically interfacially active proteins have garnered considerable interest recently owing to their potential use in a range of materials applications. Notably, the fungal hydrophobins are known to form robust and well-organized surface layers with high mechanical strength. Recently, it was shown that the bacterial biofilm protein BslA also forms highly elastic surface layers at interfaces. Here we describe several self-assembled structures formed by BslA, both at interfaces and in bulk solution, over a range of length scales spanning from nanometres to millimetres. First, we observe transiently stable and highly elongated air bubbles formed in agitated BslA samples. We study their behaviour in a range of solution conditions and hypothesize that their dissipation is a consequence of the slow adsorption kinetics of BslA to an air-water interface. Second, we describe elongated tubules formed by BslA interfacial films when shear stresses are applied in both a Langmuir trough and a rheometer. These structures bear a striking resemblance, although much larger in scale, to the elongated air bubbles formed during agitation. Taken together, this knowledge will better inform the conditions and applications of how BslA can be used in the stabilization of multi-phase materials.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'. PMID:27298433

  9. Predicting the roughness length of turbulent flows over landscapes with multi-scale microtopography

    NASA Astrophysics Data System (ADS)

    Pelletier, Jon D.; Field, Jason P.

    2016-05-01

    The fully rough form of the law of the wall is commonly used to quantify velocity profiles and associated bed shear stresses in fluvial, aeolian, and coastal environments. A key parameter in this law is the roughness length, z0. Here we propose a predictive formula for z0 that uses the amplitude and slope of each wavelength of microtopography within a discrete-Fourier-transform-based approach. Computational fluid dynamics (CFD) modeling is used to quantify the effective z0 value of sinusoidal microtopography as a function of the amplitude and slope. The effective z0 value of landscapes with multi-scale roughness is then given by the sum of contributions from each Fourier mode of the microtopography. Predictions of the equation are tested against z0 values measured in ˜ 105 wind-velocity profiles from southwestern US playa surfaces. Our equation is capable of predicting z0 values to 50 % accuracy, on average, across a 4 order of magnitude range. We also use our results to provide an alternative formula that, while somewhat less accurate than the one obtained from a full multi-scale analysis, has an advantage of being simpler and easier to apply.

  10. A phenomenological description of BslA assemblies across multiple length scales

    PubMed Central

    Morris, Ryan J.; Bromley, Keith M.; Stanley-Wall, Nicola

    2016-01-01

    Intrinsically interfacially active proteins have garnered considerable interest recently owing to their potential use in a range of materials applications. Notably, the fungal hydrophobins are known to form robust and well-organized surface layers with high mechanical strength. Recently, it was shown that the bacterial biofilm protein BslA also forms highly elastic surface layers at interfaces. Here we describe several self-assembled structures formed by BslA, both at interfaces and in bulk solution, over a range of length scales spanning from nanometres to millimetres. First, we observe transiently stable and highly elongated air bubbles formed in agitated BslA samples. We study their behaviour in a range of solution conditions and hypothesize that their dissipation is a consequence of the slow adsorption kinetics of BslA to an air–water interface. Second, we describe elongated tubules formed by BslA interfacial films when shear stresses are applied in both a Langmuir trough and a rheometer. These structures bear a striking resemblance, although much larger in scale, to the elongated air bubbles formed during agitation. Taken together, this knowledge will better inform the conditions and applications of how BslA can be used in the stabilization of multi-phase materials. This article is part of the themed issue ‘Soft interfacial materials: from fundamentals to formulation’. PMID:27298433

  11. Variability of interconnected wind plants: correlation length and its dependence on variability time scale

    DOE PAGES

    St. Martin, Clara M.; Lundquist, Julie K.; Handschy, Mark A.

    2015-04-02

    The variability in wind-generated electricity complicates the integration of this electricity into the electrical grid. This challenge steepens as the percentage of renewably-generated electricity on the grid grows, but variability can be reduced by exploiting geographic diversity: correlations between wind farms decrease as the separation between wind farms increases. However, how far is far enough to reduce variability? Grid management requires balancing production on various timescales, and so consideration of correlations reflective of those timescales can guide the appropriate spatial scales of geographic diversity grid integration. To answer 'how far is far enough,' we investigate the universal behavior of geographic diversity by exploring wind-speed correlations using three extensive datasets spanning continents, durations and time resolution. First, one year of five-minute wind power generation data from 29 wind farms span 1270 km across Southeastern Australia (Australian Energy Market Operator). Second, 45 years of hourly 10 m wind-speeds from 117 stations span 5000 km across Canada (National Climate Data Archive of Environment Canada). Finally, four years of five-minute wind-speeds from 14 meteorological towers span 350 km of the Northwestern US (Bonneville Power Administration). After removing diurnal cycles and seasonal trends from all datasets, we investigate dependence of correlation length on time scale by digitally high-pass filtering the data on 0.25–2000 h timescales and calculating correlations between sites for each high-pass filter cut-off. Correlations fall to zero with increasing station separation distance, but the characteristic correlation length varies with the high-pass filter applied: the higher the cut-off frequency, the smaller the station separation required to achieve de-correlation. Remarkable similarities between these three datasets reveal behavior that, if universal, could be particularly useful for grid management. For high

  12. A role for self-gravity at multiple length scales in the process of star formation.

    PubMed

    Goodman, Alyssa A; Rosolowsky, Erik W; Borkin, Michelle A; Foster, Jonathan B; Halle, Michael; Kauffmann, Jens; Pineda, Jaime E

    2009-01-01

    Self-gravity plays a decisive role in the final stages of star formation, where dense cores (size approximately 0.1 parsecs) inside molecular clouds collapse to form star-plus-disk systems. But self-gravity's role at earlier times (and on larger length scales, such as approximately 1 parsec) is unclear; some molecular cloud simulations that do not include self-gravity suggest that 'turbulent fragmentation' alone is sufficient to create a mass distribution of dense cores that resembles, and sets, the stellar initial mass function. Here we report a 'dendrogram' (hierarchical tree-diagram) analysis that reveals that self-gravity plays a significant role over the full range of possible scales traced by (13)CO observations in the L1448 molecular cloud, but not everywhere in the observed region. In particular, more than 90 per cent of the compact 'pre-stellar cores' traced by peaks of dust emission are projected on the sky within one of the dendrogram's self-gravitating 'leaves'. As these peaks mark the locations of already-forming stars, or of those probably about to form, a self-gravitating cocoon seems a critical condition for their existence. Turbulent fragmentation simulations without self-gravity-even of unmagnetized isothermal material-can yield mass and velocity power spectra very similar to what is observed in clouds like L1448. But a dendrogram of such a simulation shows that nearly all the gas in it (much more than in the observations) appears to be self-gravitating. A potentially significant role for gravity in 'non-self-gravitating' simulations suggests inconsistency in simulation assumptions and output, and that it is necessary to include self-gravity in any realistic simulation of the star-formation process on subparsec scales.

  13. A role for self-gravity at multiple length scales in the process of star formation.

    PubMed

    Goodman, Alyssa A; Rosolowsky, Erik W; Borkin, Michelle A; Foster, Jonathan B; Halle, Michael; Kauffmann, Jens; Pineda, Jaime E

    2009-01-01

    Self-gravity plays a decisive role in the final stages of star formation, where dense cores (size approximately 0.1 parsecs) inside molecular clouds collapse to form star-plus-disk systems. But self-gravity's role at earlier times (and on larger length scales, such as approximately 1 parsec) is unclear; some molecular cloud simulations that do not include self-gravity suggest that 'turbulent fragmentation' alone is sufficient to create a mass distribution of dense cores that resembles, and sets, the stellar initial mass function. Here we report a 'dendrogram' (hierarchical tree-diagram) analysis that reveals that self-gravity plays a significant role over the full range of possible scales traced by (13)CO observations in the L1448 molecular cloud, but not everywhere in the observed region. In particular, more than 90 per cent of the compact 'pre-stellar cores' traced by peaks of dust emission are projected on the sky within one of the dendrogram's self-gravitating 'leaves'. As these peaks mark the locations of already-forming stars, or of those probably about to form, a self-gravitating cocoon seems a critical condition for their existence. Turbulent fragmentation simulations without self-gravity-even of unmagnetized isothermal material-can yield mass and velocity power spectra very similar to what is observed in clouds like L1448. But a dendrogram of such a simulation shows that nearly all the gas in it (much more than in the observations) appears to be self-gravitating. A potentially significant role for gravity in 'non-self-gravitating' simulations suggests inconsistency in simulation assumptions and output, and that it is necessary to include self-gravity in any realistic simulation of the star-formation process on subparsec scales. PMID:19122636

  14. Characterization of aging in organic materials on atomic-, meso- and macro-length scales by {sup 13}C NMR spectroscopy

    SciTech Connect

    Assink, R.A.; Jamison, G.M.; Alam, T.M.; Gillen, K.T.

    1997-10-01

    A fundamental understanding of aging in an organic material requires that one understand how aging affects the chemical structure of a material, and how these chemical changes are related to the material`s macroscopic properties. This level of understanding is usually achieved by examining the material on a variety of length scales ranging from atomic to meso-scale to macroscopic. The authors are developing and applying several {sup 13}C nuclear magnetic resonance (NMR) spectroscopy experiments to characterize the aging process of organic materials over a broad range of length scales. Examples of studies which range from atomic to macroscopic will be presented.

  15. Clinical Frailty Scale in an Acute Medicine Unit: a Simple Tool That Predicts Length of Stay

    PubMed Central

    Juma, Salina; Taabazuing, Mary-Margaret; Montero-Odasso, Manuel

    2016-01-01

    Background Frailty is characterized by increased vulnerability to external stressors. When frail older adults are admitted to hospital, they are at increased risk of adverse events including falls, delirium, and disability. The Clinical Frailty Scale (CFS) is a practical and efficient tool for assessing frailty; however, its ability to predict outcomes has not been well studied within the acute medical service. Objective To examine the CFS in elderly patients admitted to the acute medical ward and its association with length of stay. Design Prospective cohort study in an acute care university hospital in London, Ontario, Canada, involving 75 patients over age 65, admitted to the general internal medicine clinical teaching units (CTU). Measurements Patient demographics were collected through chart review, and CFS score was assigned to each patient after brief clinician assessment. The CFS ranges from 1 (very fit) to 9 (terminally ill) based on descriptors and pictographs of activity and functional status. The CFS was collapsed into three categories: non-frail (CFS 1–4), mild-to-moderately frail (CFS 5–6), and severely frail (CFS 7–8). Outcomes of length of stay and 90-day readmission were gathered through the LHSC electronic patient record. Results Severe frailty was associated with longer lengths of stay (Mean = 12.6 ± 12.7 days) compared to mild-to-moderate frailty (mean = 11.2 ± 10.8 days), and non-frailty (mean = 4.1 ± 2.1 days, p = .014). This finding was significant after adjusting for age, sex, and number of medications. Participants with higher frailty scores showed higher readmission rates when compared with those with no frailty (31.2% for severely frail, vs. 34.2% for mild-to-moderately frail vs. 19% for non-frail) although there was no significant difference in the adjusted analysis. Conclusion The CFS helped identify patients that are more likely to have prolonged hospital stays on the acute medical ward. The CFS is an easy to use tool which

  16. Rapid prototyping of multi-scale biomedical microdevices by combining additive manufacturing technologies.

    PubMed

    Hengsbach, Stefan; Lantada, Andrés Díaz

    2014-08-01

    The possibility of designing and manufacturing biomedical microdevices with multiple length-scale geometries can help to promote special interactions both with their environment and with surrounding biological systems. These interactions aim to enhance biocompatibility and overall performance by using biomimetic approaches. In this paper, we present a design and manufacturing procedure for obtaining multi-scale biomedical microsystems based on the combination of two additive manufacturing processes: a conventional laser writer to manufacture the overall device structure, and a direct-laser writer based on two-photon polymerization to yield finer details. The process excels for its versatility, accuracy and manufacturing speed and allows for the manufacture of microsystems and implants with overall sizes up to several millimeters and with details down to sub-micrometric structures. As an application example we have focused on manufacturing a biomedical microsystem to analyze the impact of microtextured surfaces on cell motility. This process yielded a relevant increase in precision and manufacturing speed when compared with more conventional rapid prototyping procedures.

  17. Analog/RF Study of Self-aligned In0.53Ga0.47As MOSFET with Scaled Gate Length

    NASA Astrophysics Data System (ADS)

    Dehzangi, Arash; Larki, Farhad; Mohd Razip Wee, M. F.; Wichmann, Nicolas; Majlis, Burhanuddin Y.; Bollaert, Sylvain

    2016-10-01

    This study presents the impact of gate length scaling on analog and radio frequency (RF) performance of a self- aligned multi-gate n-type In0.53Ga0.47As metal oxide semiconductor field effect transistor. The device is fabricated using a self-aligned method, air-bridge technology, and 8 nm thickness of the Al2O3 oxide layer with different gate lengths. The transconductance-to-normalized drain current ratio (g m/I D) method is implemented to investigate analog parameters. Moreover, g m and drain conductance (g D) as key parameters in analog performance of the device are evaluated with g m/I D and gate length variation, where g m and g D are both showing enhancement due to scaling of the gate length. Early voltage (V EA) and intrinsic voltage gain (A V) value presents a decreasing trend by shrinking the gate length. In addition, the results of RF measurement for cut-off and maximum oscillation frequency for devices with different gate lengths are compared.

  18. Constructing new seismograms from old earthquakes: Retrospective seismology at multiple length scales

    NASA Astrophysics Data System (ADS)

    Entwistle, Elizabeth; Curtis, Andrew; Galetti, Erica; Baptie, Brian; Meles, Giovanni

    2015-04-01

    If energy emitted by a seismic source such as an earthquake is recorded on a suitable backbone array of seismometers, source-receiver interferometry (SRI) is a method that allows those recordings to be projected to the location of another target seismometer, providing an estimate of the seismogram that would have been recorded at that location. Since the other seismometer may not have been deployed at the time the source occurred, this renders possible the concept of 'retrospective seismology' whereby the installation of a sensor at one period of time allows the construction of virtual seismograms as though that sensor had been active before or after its period of installation. Using the benefit of hindsight of earthquake location or magnitude estimates, SRI can establish new measurement capabilities closer to earthquake epicenters, thus potentially improving earthquake location estimates. Recently we showed that virtual SRI seismograms can be constructed on target sensors in both industrial seismic and earthquake seismology settings, using both active seismic sources and ambient seismic noise to construct SRI propagators, and on length scales ranging over 5 orders of magnitude from ~40 m to ~2500 km[1]. Here we present the results from earthquake seismology by comparing virtual earthquake seismograms constructed at target sensors by SRI to those actually recorded on the same sensors. We show that spatial integrations required by interferometric theory can be calculated over irregular receiver arrays by embedding these arrays within 2D spatial Voronoi cells, thus improving spatial interpolation and interferometric results. The results of SRI are significantly improved by restricting the backbone receiver array to include approximately those receivers that provide a stationary phase contribution to the interferometric integrals. We apply both correlation-correlation and correlation-convolution SRI, and show that the latter constructs virtual seismograms with fewer

  19. Hydrodynamic interactions and Brownian forces in colloidal suspensions: Coarse-graining over time and length scales

    NASA Astrophysics Data System (ADS)

    Padding, J. T.; Louis, A. A.

    2006-09-01

    We describe in detail how to implement a coarse-grained hybrid molecular dynamics and stochastic rotation dynamics simulation technique that captures the combined effects of Brownian and hydrodynamic forces in colloidal suspensions. The importance of carefully tuning the simulation parameters to correctly resolve the multiple time and length scales of this problem is emphasized. We systematically analyze how our coarse-graining scheme resolves dimensionless hydrodynamic numbers such as the Reynolds number Re, which indicates the importance of inertial effects, the Schmidt number Sc, which indicates whether momentum transport is liquidlike or gaslike, the Mach number, which measures compressibility effects, the Knudsen number, which describes the importance of noncontinuum molecular effects, and the Peclet number, which describes the relative effects of convective and diffusive transport. With these dimensionless numbers in the correct regime the many Brownian and hydrodynamic time scales can be telescoped together to maximize computational efficiency while still correctly resolving the physically relevant processes. We also show how to control a number of numerical artifacts, such as finite-size effects and solvent-induced attractive depletion interactions. When all these considerations are properly taken into account, the measured colloidal velocity autocorrelation functions and related self-diffusion and friction coefficients compare quantitatively with theoretical calculations. By contrast, these calculations demonstrate that, notwithstanding its seductive simplicity, the basic Langevin equation does a remarkably poor job of capturing the decay rate of the velocity autocorrelation function in the colloidal regime, strongly underestimating it at short times and strongly overestimating it at long times. Finally, we discuss in detail how to map the parameters of our method onto physical systems and from this extract more general lessons—keeping in mind that there

  20. Hydrodynamic interactions and Brownian forces in colloidal suspensions: coarse-graining over time and length scales.

    PubMed

    Padding, J T; Louis, A A

    2006-09-01

    We describe in detail how to implement a coarse-grained hybrid molecular dynamics and stochastic rotation dynamics simulation technique that captures the combined effects of Brownian and hydrodynamic forces in colloidal suspensions. The importance of carefully tuning the simulation parameters to correctly resolve the multiple time and length scales of this problem is emphasized. We systematically analyze how our coarse-graining scheme resolves dimensionless hydrodynamic numbers such as the Reynolds number Re, which indicates the importance of inertial effects, the Schmidt number Sc, which indicates whether momentum transport is liquidlike or gaslike, the Mach number, which measures compressibility effects, the Knudsen number, which describes the importance of noncontinuum molecular effects, and the Peclet number, which describes the relative effects of convective and diffusive transport. With these dimensionless numbers in the correct regime the many Brownian and hydrodynamic time scales can be telescoped together to maximize computational efficiency while still correctly resolving the physically relevant processes. We also show how to control a number of numerical artifacts, such as finite-size effects and solvent-induced attractive depletion interactions. When all these considerations are properly taken into account, the measured colloidal velocity autocorrelation functions and related self-diffusion and friction coefficients compare quantitatively with theoretical calculations. By contrast, these calculations demonstrate that, notwithstanding its seductive simplicity, the basic Langevin equation does a remarkably poor job of capturing the decay rate of the velocity autocorrelation function in the colloidal regime, strongly underestimating it at short times and strongly overestimating it at long times. Finally, we discuss in detail how to map the parameters of our method onto physical systems and from this extract more general lessons-keeping in mind that there

  1. Multi Length Scale Imaging of Flocculated Estuarine Sediments; Insights into their Complex 3D Structure

    NASA Astrophysics Data System (ADS)

    Wheatland, Jonathan; Bushby, Andy; Droppo, Ian; Carr, Simon; Spencer, Kate

    2015-04-01

    Suspended estuarine sediments form flocs that are compositionally complex, fragile and irregularly shaped. The fate and transport of suspended particulate matter (SPM) is determined by the size, shape, density, porosity and stability of these flocs and prediction of SPM transport requires accurate measurements of these three-dimensional (3D) physical properties. However, the multi-scaled nature of flocs in addition to their fragility makes their characterisation in 3D problematic. Correlative microscopy is a strategy involving the spatial registration of information collected at different scales using several imaging modalities. Previously, conventional optical microscopy (COM) and transmission electron microscopy (TEM) have enabled 2-dimensional (2D) floc characterisation at the gross (> 1 µm) and sub-micron scales respectively. Whilst this has proven insightful there remains a critical spatial and dimensional gap preventing the accurate measurement of geometric properties and an understanding of how structures at different scales are related. Within life sciences volumetric imaging techniques such as 3D micro-computed tomography (3D µCT) and focused ion beam scanning electron microscopy [FIB-SEM (or FIB-tomography)] have been combined to characterise materials at the centimetre to micron scale. Combining these techniques with TEM enables an advanced correlative study, allowing material properties across multiple spatial and dimensional scales to be visualised. The aims of this study are; 1) to formulate an advanced correlative imaging strategy combining 3D µCT, FIB-tomography and TEM; 2) to acquire 3D datasets; 3) to produce a model allowing their co-visualisation; 4) to interpret 3D floc structure. To reduce the chance of structural alterations during analysis samples were first 'fixed' in 2.5% glutaraldehyde/2% formaldehyde before being embedding in Durcupan resin. Intermediate steps were implemented to improve contrast and remove pore water, achieved by the

  2. Genetic variability of the stable fly assessed on a global scale using amplified fragment length polymorphism.

    PubMed

    Kneeland, Kathleen M; Skoda, Steven R; Foster, John E

    2016-10-01

    The stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae), is a blood-feeding, economically important pest of animals and humans worldwide. Improved management strategies are essential and their development would benefit from studies on genetic diversity of stable flies. Especially if done on a global scale, such research could generate information necessary for the development and application of more efficient control methods. Herein we report on a genetic study of stable flies using amplified fragment length polymorphism, with samples of 10-40 individuals acquired from a total of 25 locations in the Nearctic, Neotropic, Palearctic, Afrotropic and Australasian biogeographical regions. We hypothesized that genetic differentiation would exist across geographical barriers. Although FST (0.33) was moderately high, the GST (0.05; representing genetic diversity between individuals) was very low; Nm values (representing gene flow) were high (9.36). The mismatch distribution and tests of neutrality suggested population expansion, with no genetic differentiation between locations. The analysis of molecular variance (AMOVA) results showed the majority of genetic diversity was within groups. The mantel test showed no correlation between geographic and genetic distance; this strongly supports the AMOVA results. These results suggest that stable flies did not show genetic differentiation but are panmictic, with no evidence of isolation by distance or across geographical barriers. PMID:25788399

  3. Polarized Enhanced Backscattering Spectroscopy for Characterization of Biological Tissues at Subdiffusion Length-scales

    PubMed Central

    Radosevich, Andrew J.; Rogers, Jeremy D.; Turzhitsky, Vladimir; Mutyal, Nikhil N.; Yi, Ji; Roy, Hemant K.; Backman, Vadim

    2013-01-01

    Since the early 1980’s, the enhanced backscattering (EBS) phenomenon has been well-studied in a large variety of non-biological materials. Yet, until recently the use of conventional EBS for the characterization of biological tissue has been fairly limited. In this work we detail the unique ability of EBS to provide spectroscopic, polarimetric, and depth-resolved characterization of biological tissue using a simple backscattering instrument. We first explain the experimental and numerical procedures used to accurately measure and model the full azimuthal EBS peak shape in biological tissue. Next we explore the peak shape and height dependencies for different polarization channels and spatial coherence of illumination. We then illustrate the extraordinary sensitivity of EBS to the shape of the scattering phase function using suspensions of latex microspheres. Finally, we apply EBS to biological tissue samples in order to measure optical properties and observe the spatial length-scales at which backscattering is altered in early colon carcinogenesis. PMID:24163574

  4. Revealing Optical Properties of Reduced-Dimensionality Materials at Relevant Length Scales.

    PubMed

    Ogletree, D Frank; Schuck, P James; Weber-Bargioni, Alexander F; Borys, Nicholas J; Aloni, Shaul; Bao, Wei; Barja, Sara; Lee, Jiye; Melli, Mauro; Munechika, Keiko; Whitelam, Stephan; Wickenburg, Sebastian

    2015-10-14

    Reduced-dimensionality materials for photonic and optoelectronic applications including energy conversion, solid-state lighting, sensing, and information technology are undergoing rapid development. The search for novel materials based on reduced-dimensionality is driven by new physics. Understanding and optimizing material properties requires characterization at the relevant length scale, which is often below the diffraction limit. Three important material systems are chosen for review here, all of which are under investigation at the Molecular Foundry, to illustrate the current state of the art in nanoscale optical characterization: 2D semiconducting transition metal dichalcogenides; 1D semiconducting nanowires; and energy-transfer in assemblies of 0D semiconducting nanocrystals. For each system, the key optical properties, the principal experimental techniques, and important recent results are discussed. Applications and new developments in near-field optical microscopy and spectroscopy, scanning probe microscopy, and cathodoluminescence in the electron microscope are given detailed attention. Work done at the Molecular Foundry is placed in context within the fields under review. A discussion of emerging opportunities and directions for the future closes the review.

  5. Length scale dependent of thermal conductivity of Si-Ge alloys

    NASA Astrophysics Data System (ADS)

    Chen, Long; Poon, S. Joseph; Donovan, Brian; Gaskins, John T.; Hopkins, Patrick

    2015-03-01

    A crucial aspect of the optimization of the thermoelectric figure of merit involves manipulation of the lattice thermal conductivity without significantly effecting electronic mobility. In order to fully understand the contributions to the lattice thermal conductivity, we present a calculations based on a phonon frequency-dependent model. This model, derived using the effective medium method, predicts the lattice thermal conductivity reduction due to the presence of nanoinclusions in a matrix. We further extend our work to study fully nanostructured materials. By using this method, the dependence of lattice thermal conductivity on various length scale is determined. We validate these models with experiment results obtained via time-domain thermoreflectance. By varying the modulation frequency of this pump-probe technique, we are able to measure the thermal conductivity of Si and Si-Ge systems over a variety of thermal penetration depths. We use this combination of modeling and experimental findings to gain insight into the relationship between phonon mean free path and the lattice thermal conductivity.

  6. Extending the length and time scales of Gram–Schmidt Lyapunov vector computations

    SciTech Connect

    Costa, Anthony B.; Green, Jason R.

    2013-08-01

    Lyapunov vectors have found growing interest recently due to their ability to characterize systems out of thermodynamic equilibrium. The computation of orthogonal Gram–Schmidt vectors requires multiplication and QR decomposition of large matrices, which grow as N{sup 2} (with the particle count). This expense has limited such calculations to relatively small systems and short time scales. Here, we detail two implementations of an algorithm for computing Gram–Schmidt vectors. The first is a distributed-memory message-passing method using Scalapack. The second uses the newly-released MAGMA library for GPUs. We compare the performance of both codes for Lennard–Jones fluids from N=100 to 1300 between Intel Nahalem/Infiniband DDR and NVIDIA C2050 architectures. To our best knowledge, these are the largest systems for which the Gram–Schmidt Lyapunov vectors have been computed, and the first time their calculation has been GPU-accelerated. We conclude that Lyapunov vector calculations can be significantly extended in length and time by leveraging the power of GPU-accelerated linear algebra.

  7. Ion acceleration in the transparent regime and the critical influence of the plasma density scale length

    NASA Astrophysics Data System (ADS)

    Loch, R. A.; Ceccotti, T.; Quéré, F.; George, H.; Bonnaud, G.; Réau, F.; D'Oliveira, P.; Luttikhof, M. J. H.; Bijkerk, F.; Boller, K.-J.; Blaclard, G.; Combis, P.

    2016-09-01

    The influence of a plasma density gradient on ions accelerated along the specular (back reflection) direction in the transparent Target Normal Sheath Acceleration regime is investigated. Enhanced acceleration of ions is experimentally observed in this regime using high-intensity and ultra-high contrast laser pulses and extremely thin foils of few nanometer thicknesses. The experimental trend for the maximum proton energy appeared quite different from the already published numerical results in this regime where an infinitely steep plasma gradient was assumed. We showed that for a realistic modelling, a finite density gradient has to be taken into account. By means of particle-in-cell (PIC) simulations, we studied for the first time the influence of the plasma density scale length on ion acceleration from these nanofoil targets. Through a qualitative agreement between our numerical particle-in-cell simulations and our experiments, the main conclusion with regard to the experimental requirements is that, in the transparent regime evidenced with nanofoils as compared to the opaque regime, the plasma expansion has to be taken into account and both the pulse contrast and the damage threshold of the material are essential parameters.

  8. Double gravitational bound system in virial equilibrium: tidal scale length induced on one subsystem by another

    NASA Astrophysics Data System (ADS)

    Secco, L.

    2000-11-01

    When a gravitational bound system of two components, one completely inside the other, is considered, and virial equilibrium holds, Clausius' virial generalization of each subcomponent, defined as that which balances twice the kinetic energy of the corresponding virial equation, does not, in general, match the total potential energy of the same subsystem. When the substructures are modeled as two concentric homothetic and oblate spheroids of spheroidal, similar and coaxial strata mass distributions, the conditions for the existence of a minimum in Clausius' virial function, related to the inner component, are searched and discussed as a function of both the two power-law density profiles. The semimajor axis at which the minimum appears leads to the definition of a tidal scale length induced from the outer subsystem, assumed frozen in size and shape, on the the inner one. The special case of two homogeneous spheroidal subsystems is also considered in order to highlight the effect of different eccentricities between the inner and the outer component. The tidal interaction term between the two matter distributions is taken into account, by using tensor virial theorem. Applications to the world of galaxies are considered and some possible consequences for galaxy dynamics are taken into account.

  9. A multiple length scale description of the mechanism of elastomer stretching

    DOE PAGES

    Neuefeind, Joerg C.; Skov, Anne L.; Daniels, John E.; Honkimaeki, Veijo; Jakobsen, Bo; Oddershede, Jette; Poulsen, Henning F.

    2016-10-03

    Conventionally, the stretching of rubber is modeled exclusively by rotations of segments of the embedded polymer chains; i.e. changes in entropy. However models have not been tested on all relevant length scales due to a lack of appropriate probes. Here we present a universal X-ray based method for providing data on the structure of rubbers in the 2–50 Å range. First results relate to the elongation of a silicone rubber. We identify several non-entropic contributions to the free energy and describe the associated structural changes. By far the largest contribution comes from structural changes within the individual monomers, but amongmore » the contributions is also an elastic strain, acting between chains, which is 3–4 orders of magnitude smaller than the macroscopic strain, and of the opposite sign, i.e. extension of polymer chains in the direction perpendicular to the stretch. We find this may be due to trapped entanglements relaxing to positions close to the covalent crosslinks.« less

  10. The role of reactant unmixedness, strain rate, and length scale on premixed combustor performance

    SciTech Connect

    Samuelsen, S.; LaRue, J.; Vilayanur, S.

    1995-10-01

    Lean premixed combustion provides a means to reduce pollutant formation and increase combustion efficiency. However, fuel-air mixing is rarely uniform in space and time. This nonuniformity in concentration will lead to relative increases in pollutant formation and decreases in combustion efficiency. The nonuniformity of the concentration at the exit of the premixer has been defined by Lyons (1981) as the {open_quotes}unmixedness.{close_quotes} Although turbulence properties such as length scales and strain rate are known to effect unmixedness, the exact relationship is unknown. Evaluating this relationship and the effect of unmixedness in premixed combustion on pollutant formation and combustion efficiency are an important part of the overall goal of US Department of Energy`s Advanced Turbine Systems (ATS) program and are among the goals of the program described herein. The information obtained from ATS is intended to help to develop and commercialize gas turbines which have (1) a wide range of operation/stability, (2) a minimal amount of pollutant formation, and (3) high combustion efficiency. Specifically, with regard to pollutants, the goals are to reduce the NO{sub x} emissions by at least 10%, obtain less than 20 PPM of both CO and UHC, and increase the combustion efficiency by 5%.

  11. Comparison of friction and wear of articular cartilage on different length scales.

    PubMed

    Kienle, Sandra; Boettcher, Kathrin; Wiegleb, Lorenz; Urban, Joanna; Burgkart, Rainer; Lieleg, Oliver; Hugel, Thorsten

    2015-09-18

    The exceptional tribological properties of articular cartilage are still far from being fully understood. Articular cartilage is able to withstand high loads and provide exceptionally low friction. Although the regeneration abilities of the tissue are very limited, it can last for many decades. These biomechanical properties are realized by an interplay of different lubrication and wear protection mechanisms. The deterioration of cartilage due to aging or injury leads to the development of osteoarthritis. A current treatment strategy focuses on supplementing the intra-articular fluid with a saline solution containing hyaluronic acid. In the work presented here, we investigated how changing the lubricating fluid affects friction and wear of articular cartilage, focusing on the boundary and mixed lubrication as well as interstitial fluid pressurization mechanisms. Different length and time scales were probed by atomic force microscopy, tribology and profilometry. We compared aqueous solutions with different NaCl concentrations to a viscosupplement containing hyaluronic acid (HA). In particular, we found that the presence of ions changes the frictional behavior and the wear resistance. In contrast, hyaluronic acid showed no significant impact on the friction coefficient, but considerably reduced wear. This study confirms the previous notion that friction and wear are not necessarily correlated in articular cartilage tribology and that the main role of HA might be to provide wear protection for the articular surface.

  12. Full-Field Imaging of Acoustic Motion at Nanosecond Time and Micron Length Scales

    SciTech Connect

    Telschow, Kenneth Louis; Deason, Vance Albert; Cottle, David Lynn; Larson III, John D.

    2002-10-01

    A full-field view laser ultrasonic imaging method has been developed that measures acoustic motion at a surface without scanning. Images are recorded at normal video frame rates by employing dynamic holography using photorefractive interferometric detection. By extending the approach to ultra high frequencies, an acoustic microscope has been developed capable of operation on the nanosecond time and micron length scales. Both acoustic amplitude and phase are recorded allowing full calibration and determination of phases to within a single arbitrary constant. Results are presented of measurements at frequencies at 800-900 MHz illustrating a multitude of normal mode behavior in electrically driven thin film acoustic resonators. Coupled with microwave electrical impedance measurements, this imaging mode provides an exceptionally fast method for evaluation of electric to acoustic coupling and performance of these devices. Images of 256x240 pixels are recorded at 18Hz rates synchronized to obtain both in-phase and quadrature detection of the acoustic motion. Simple averaging provides sensitivity to the subnanometer level calibrated over the image using interferometry. Identification of specific acoustic modes and their relationship to electrical impedance characteristics show the advantages and overall high speed of the technique.

  13. Review of the synergies between computational modeling and experimental characterization of materials across length scales

    DOE PAGES

    Dingreville, Rémi; Karnesky, Richard A.; Puel, Guillaume; Schmitt, Jean -Hubert

    2015-11-16

    With the increasing interplay between experimental and computational approaches at multiple length scales, new research directions are emerging in materials science and computational mechanics. Such cooperative interactions find many applications in the development, characterization and design of complex material systems. This manuscript provides a broad and comprehensive overview of recent trends in which predictive modeling capabilities are developed in conjunction with experiments and advanced characterization to gain a greater insight into structure–property relationships and study various physical phenomena and mechanisms. The focus of this review is on the intersections of multiscale materials experiments and modeling relevant to the materials mechanicsmore » community. After a general discussion on the perspective from various communities, the article focuses on the latest experimental and theoretical opportunities. Emphasis is given to the role of experiments in multiscale models, including insights into how computations can be used as discovery tools for materials engineering, rather than to “simply” support experimental work. This is illustrated by examples from several application areas on structural materials. In conclusion this manuscript ends with a discussion on some problems and open scientific questions that are being explored in order to advance this relatively new field of research.« less

  14. Review of the synergies between computational modeling and experimental characterization of materials across length scales

    SciTech Connect

    Dingreville, Rémi; Karnesky, Richard A.; Puel, Guillaume; Schmitt, Jean -Hubert

    2015-11-16

    With the increasing interplay between experimental and computational approaches at multiple length scales, new research directions are emerging in materials science and computational mechanics. Such cooperative interactions find many applications in the development, characterization and design of complex material systems. This manuscript provides a broad and comprehensive overview of recent trends in which predictive modeling capabilities are developed in conjunction with experiments and advanced characterization to gain a greater insight into structure–property relationships and study various physical phenomena and mechanisms. The focus of this review is on the intersections of multiscale materials experiments and modeling relevant to the materials mechanics community. After a general discussion on the perspective from various communities, the article focuses on the latest experimental and theoretical opportunities. Emphasis is given to the role of experiments in multiscale models, including insights into how computations can be used as discovery tools for materials engineering, rather than to “simply” support experimental work. This is illustrated by examples from several application areas on structural materials. In conclusion this manuscript ends with a discussion on some problems and open scientific questions that are being explored in order to advance this relatively new field of research.

  15. Hybrid Simulation Strategy for Simulating Self-Assembled Morphologies at the Atomistic Length Scales

    NASA Astrophysics Data System (ADS)

    Sethuraman, Vaidyanathan; Ganesan, Venkat

    In the context of Lithium-ion batteries, an enhancement in both ionic conductivity and mechanical properties, were observed for block copolymer electrolytes with increasing MW. On the contrary, when homopolymers were used as electrolytes, the ionic conductivity decreased with increasing MW. However, the origins of such increase in conductivity are unclear and are speculated to be tied to both the morphology and the atomistic details of the copolymer themselves. Motivated by such issues, we present a strategy to create ordered morphologies of block copolymers at the atomistic level using a combination of coarse-graining and inverse coarse-graining techniques. A mapping which is developed using the long-ranged structural mapping in the disordered phases will be utilized to generate self-assembled morphologies. In particular we focus on generating self-assembled morphologies of PS-PEO at the atomistic length scales. Statics and dynamics of such self-assembled morphologies will be presented and the effect of self assembly on the transport properties of ions will also be explored. Funded by NSF.

  16. Additives

    NASA Technical Reports Server (NTRS)

    Smalheer, C. V.

    1973-01-01

    The chemistry of lubricant additives is discussed to show what the additives are chemically and what functions they perform in the lubrication of various kinds of equipment. Current theories regarding the mode of action of lubricant additives are presented. The additive groups discussed include the following: (1) detergents and dispersants, (2) corrosion inhibitors, (3) antioxidants, (4) viscosity index improvers, (5) pour point depressants, and (6) antifouling agents.

  17. Quantum electrodynamics and the electron self-energy in a deformed space with a minimal length scale

    NASA Astrophysics Data System (ADS)

    Silva, Apollo V.; Abreu, E. M. C.; Neves, M. J.

    2016-06-01

    The main motivation to study models in the presence of a minimal length is to obtain a quantum field theory free of the divergences. In this way, in this paper, we have constructed a new framework for quantum electrodynamics embedded in a minimal length scale background. New operators are introduced and the Green function method was used for the solution of the field equations, i.e. the Maxwell, Klein-Gordon and Dirac equations. We have analyzed specifically the scalar field and its one loop propagator. The mass of the scalar field regularized by the minimal length was obtained. The QED Lagrangian containing a minimal length was also constructed and the divergences were analyzed. The electron and photon propagators, and the electron self-energy at one loop as a function of the minimal length was also obtained.

  18. P/Halley: Spatial distribution and scale lengths for C2, CN, NH2, and H2O

    NASA Technical Reports Server (NTRS)

    Fink, Uwe; Combi, Michael; Disanti, Michael A.

    1992-01-01

    From P/Halley, long slit spectroscopic exposures on 12 dates, extending from Oct. 1985 to May 1986, spatial profiles were obtained for emissions by C2, CN, NH2, and OI ((sup 1)D). Examples of our derived spatial profiles are given. The qualitative trend of the scale lengths for the different species is nicely exemplified in this example. C2 has the longest parent scale length followed by CN and NH2. OI which tracks the parent H2O distribution is quite narrow but slightly wider than the continuum profile which has a center essentially indistinguishable from the stellar seeing disk. Comparison of C2 and CN also shows that C2 is falling off faster in the wings so that the daughter scale length of CN must be larger than that of C2.

  19. Bridging length and time scales in sheared demixing systems: from the Cahn-Hilliard to the Doi-Ohta model.

    PubMed

    Jelić, Asja; Ilg, Patrick; Ottinger, Hans Christian

    2010-01-01

    We develop a systematic coarse-graining procedure which establishes the connection between models of mixtures of immiscible fluids at different length and time scales. We start from the Cahn-Hilliard model of spinodal decomposition in a binary fluid mixture under flow from which we derive the coarse-grained description. The crucial step in this procedure is to identify the relevant coarse-grained variables and find the appropriate mapping which expresses them in terms of the more microscopic variables. In order to capture the physics of the Doi-Ohta level, we introduce the interfacial width as an additional variable at that level. In this way, we account for the stretching of the interface under flow and derive analytically the convective behavior of the relevant coarse-grained variables, which in the long wavelength limit recovers the familiar phenomenological Doi-Ohta model. In addition, we obtain the expression for the interfacial tension in terms of the Cahn-Hilliard parameters as a direct result of the developed coarse-graining procedure. Finally, by analyzing the numerical results obtained from the simulations on the Cahn-Hilliard level, we discuss that dissipative processes at the Doi-Ohta level are of the same origin as in the Cahn-Hilliard model. The way to estimate the interface relaxation times of the Doi-Ohta model from the underlying morphology dynamics simulated at the Cahn-Hilliard level is established. PMID:20365347

  20. Assessing the role of static length scales behind glassy dynamics in polydisperse hard disks.

    PubMed

    Russo, John; Tanaka, Hajime

    2015-06-01

    The possible role of growing static order in the dynamical slowing down toward the glass transition has recently attracted considerable attention. On the basis of random first-order transition theory, a new method to measure the static correlation length of amorphous order, called "point-to-set" (PTS) length, has been proposed and used to show that the dynamic length grows much faster than the static length. Here, we study the nature of the PTS length, using a polydisperse hard-disk system, which is a model that is known to exhibit a growing hexatic order upon densification. We show that the PTS correlation length is decoupled from the steeper increase of the correlation length of hexatic order and dynamic heterogeneity, while closely mirroring the decay length of two-body density correlations. Our results thus provide a clear example that other forms of order can play an important role in the slowing down of the dynamics, casting a serious doubt on the order-agnostic nature of the PTS length and its relevance to slow dynamics, provided that a polydisperse hard-disk system is a typical glass former. PMID:26038545

  1. Application of the linear/exponential hybrid force field scaling scheme to the bond length alternation modes of polyacetylene

    NASA Astrophysics Data System (ADS)

    Yang, Shujiang; Kertesz, Miklos

    2006-12-01

    The two bond length alternation related backbone carbon-carbon stretching Raman active normal modes of polyacetylene are notoriously difficulty to predict theoretically. We apply our new linear/exponential scaled quantum mechanical force field scheme to tackle this problem by exponentially adjusting the decay of the coupling force constants between backbone stretchings based on their distance which extends over many neighbors. With transferable scaling parameters optimized by least squares fitting to the experimental vibrational frequencies of short oligoenes, the scaled frequencies of trans-polyacetylene and its isotopic analogs agree very well with experiments. The linear/exponential scaling scheme is also applicable to the cis-polyacetylene case.

  2. Compositional variations at ultra-structure length scales in coral skeleton

    NASA Astrophysics Data System (ADS)

    Meibom, Anders; Cuif, Jean-Pierre; Houlbreque, Fanny; Mostefaoui, Smail; Dauphin, Yannicke; Meibom, Karin L.; Dunbar, Robert

    2008-03-01

    Distributions of Mg and Sr in the skeletons of a deep-sea coral ( Caryophyllia ambrosia) and a shallow-water, reef-building coral ( Pavona clavus) have been obtained with a spatial resolution of 150 nm, using the NanoSIMS ion microprobe at the Muséum National d'Histoire Naturelle in Paris. These trace element analyses focus on the two primary ultra-structural components in the skeleton: centers of calcification (COC) and fibrous aragonite. In fibrous aragonite, the trace element variations are typically on the order of 10% or more, on length scales on the order of 1-10 μm. Sr/Ca and Mg/Ca variations are not correlated. However, Mg/Ca variations in Pavona are strongly correlated with the layered organization of the skeleton. These data allow for a direct comparison of trace element variations in zooxanthellate and non-zooxanthellate corals. In both corals, all trace elements show variations far beyond what can be attributed to variations in the marine environment. Furthermore, the observed trace element variations in the fibrous (bulk) part of the skeletons are not related to the activity of zooxanthellae, but result from other biological activity in the coral organism. To a large degree, this biological forcing is independent of the ambient marine environment, which is essentially constant on the growth timescales considered here. Finally, we discuss the possible detection of a new high-Mg calcium carbonate phase, which appears to be present in both deep-sea and reef-building corals and is neither aragonite nor calcite.

  3. Additional field verification of convective scaling for the lateral dispersion parameter

    SciTech Connect

    Sakiyama, S.K.; Davis, P.A.

    1988-07-01

    The results of a series of diffusion trials over the heterogeneous surface of the Canadian Precambrian Shield provide additional support for the convective scaling of the lateral dispersion parameter. The data indicate that under convective conditions, the lateral dispersion parameter can be scaled with the convective velocity scale and the mixing depth. 10 references.

  4. Determining pore length scales and pore surface relaxivity of rock cores by internal magnetic fields modulation at 2MHz NMR.

    PubMed

    Liu, Huabing; Nogueira d'Eurydice, Marcel; Obruchkov, Sergei; Galvosas, Petrik

    2014-09-01

    Pore length scales and pore surface relaxivities of rock cores with different lithologies were studied on a 2MHz Rock Core Analyzer. To determine the pore length scales of the rock cores, the high eigenmodes of spin bearing molecules satisfying the diffusion equation were detected with optimized encoding periods in the presence of internal magnetic fields Bin. The results were confirmed using a 64MHz NMR system, which supports the feasibility of high eigenmode detection at fields as low as 2MHz. Furthermore, this methodology was combined with relaxometry measurements to a two-dimensional experiment, which provides correlation between pore length and relaxation time. This techniques also yields information on the surface relaxivity of the rock cores. The estimated surface relaxivities were then compared to the results using an independent NMR method.

  5. Structural Order of Water Molecules around Hydrophobic Solutes: Length-Scale Dependence and Solute-Solvent Coupling.

    PubMed

    Hande, Vrushali R; Chakrabarty, Suman

    2015-08-27

    It has been suggested that the structure and thermodynamics of the water molecules in the hydration layer of simple hydrophobic solutes undergo an order-disorder transition around a nanometer length-scale of the solute size. Using extensive atomistic molecular dynamics (MD) and replica exchange molecular dynamics (REMD) simulation studies, we have probed this order-disorder transition around model hydrophobic solutes of varying size and shape (spherical, planar, and linear), as well as flexible hydrophobic homopolymer chains (n-alkanes), where the conformational fluctuations are likely to create both spatial and temporal heterogeneity on the solvent accessible surface. We have explored the structural response of the water molecules in the hydration shell due to the local variations of the length-scale (or curvature) upon hydrophobic collapse and/or local conformational changes of these polymers. We have shown that the tetrahedral order of the water molecules in the hydration shell is practically independent of the polymer size in the extended state of the polymer due to the availability of a subnanometer cross-sectional length-scale, allowing the water molecules to form hydrogen bonds around the polymer chain. Beyond a certain length of the polymer chains, the collapsed states (associated with larger solute length-scale) start to induce disorder in the surface water molecules. We demonstrate that the local structure (both local number density and tetrahedral order) of the hydration layer is dynamically coupled to the local topology of the polymer. Thus, we envisage that in a flexible (bio)polymer, the hydration shell properties will be sensitive to the local conformational state of the molecule (both spatially and temporally), and the overall observed water structure and dynamics will be dependent on the topological/chemical heterogeneity, and the time-scale of fluctuations in the local curvature (length-scale) of the solvent accessible surface. Moreover, we have

  6. Unidirectional solidification of Zn-rich Zn-Cu peritectic alloys -- 2. Microstructural length scales

    SciTech Connect

    Ma, D.; Li, Y.; Ng, S.C.; Jones, H.

    2000-05-11

    Experimental results are presented of solidification microstructure length scale including {eta}-phase cell spacing, primary {epsilon} secondary dendrite arm spacing, size of nonaligned dendrite of primary {epsilon}, and volume fraction of primary {epsilon}, as functions of alloy concentration (containing up to 7.37 wt% Cu) and growth velocity (ranging from 0.02 to 4.82 mm/s) in the unidirectional solidification of Zn-rich Zn-Cu peritectic alloys. Intercellular spacing ({lambda}) of two-phase cellular structure decreases with increasing growth velocity (V) such that {lambda}V{sup 1/2} is constant at a fixed alloy concentration in parametric agreement with the KGT and Hunt-Lu models. The value of {lambda}V{sup 1/2} varies from 216 {+-} 10 to 316 {+-} 55 {micro}m{sup 3/2}/s{sup 1/2} with decrease in alloy concentration from 4.94 to 2.17 wt% Cu. These values are much greater than for normal eutectic systems but comparable with monotectic alloys. Dendritic secondary arm spacing ({lambda}{sub 2}) of primary {epsilon} decreases with increasing V such that {lambda}{sub 2}V{sup 1/3} is constant ranging 14.9 {+-} 0.9 to 75.6 {+-} 8.1 {micro}m{sup 4/3}/s{sup 1/3} with increase in alloy concentration (C{sub 0}) from 2.17 to 7.37 wt% Cu, which is in parametric agreement with predictions of arm-coarsening theory. The volume fraction (f{sub e}) of primary {epsilon} increases with increasing V for Zn-rich Zn-3.37, 4.94 and 7.37 wt% Cu hyperperitectic alloys. Predictions of the Scheil and Sarreal-Abbaschian models show good agreement with the observed f{sub {epsilon}} for Zn-4.94 wt% Cu at moderate V from 0.19 to 2.64 mm/s, but fail at low V of less than 0.16 mm/s and at high V of greater than 3.54 mm/s. The measured average size, {Lambda}V{sup 1/2} is constant for a given alloy, increasing from (0.98 {+-} 0.04) x 10{sup 3} to (7.2 {+-} 0.7) x 10{sup 3} {micro}m{sup 3/2}/s{sup 1/2} with increase in alloy concentration from 2.17 to 4.94 wt% Cu.

  7. Performance of four turbulence closure models implemented using a generic length scale method

    USGS Publications Warehouse

    Warner, J.C.; Sherwood, C.R.; Arango, H.G.; Signell, R.P.

    2005-01-01

    A two-equation turbulence model (one equation for turbulence kinetic energy and a second for a generic turbulence length-scale quantity) proposed by Umlauf and Burchard [J. Marine Research 61 (2003) 235] is implemented in a three-dimensional oceanographic model (Regional Oceanographic Modeling System; ROMS v2.0). These two equations, along with several stability functions, can represent many popular turbulence closures, including the k-kl (Mellor-Yamada Level 2.5), k-??, and k-?? schemes. The implementation adds flexibility to the model by providing an unprecedented range of turbulence closure selections in a single 3D oceanographic model and allows comparison and evaluation of turbulence models in an otherwise identical numerical environment. This also allows evaluation of the effect of turbulence models on other processes such as suspended-sediment distribution or ecological processes. Performance of the turbulence models and sediment-transport schemes is investigated with three test cases for (1) steady barotropic flow in a rectangular channel, (2) wind-induced surface mixed-layer deepening in a stratified fluid, and (3) oscillatory stratified pressure-gradient driven flow (estuarine circulation) in a rectangular channel. Results from k-??, k-??, and gen (a new closure proposed by Umlauf and Burchard [J. Marine Research 61 (2003) 235]) are very similar for these cases, but the k-kl closure results depend on a wall-proximity function that must be chosen to suit the flow. Greater variations appear in simulations of suspended-sediment concentrations than in salinity simulations because the transport of suspended-sediment amplifies minor variations in the methods. The amplification is caused by the added physics of a vertical settling rate, bottom stress dependent resuspension, and diffusive transport of sediment in regions of well mixed salt and temperature. Despite the amplified sensitivity of sediment to turbulence models in the estuary test case, the four

  8. Hierarchical Self-Assembly of Peptide Amphiphiles: Form and Function at Multiple Length Scales

    NASA Astrophysics Data System (ADS)

    Zha, Runye Helen

    Hierarchical self-assembly, the organization of molecules into supramolecular structures of increasing size and complexity, is a potent tool for materials synthesis and requires understanding the connections of structure across multiple length scales. Herein, self-assembly of peptide amphiphiles (PAs) into nanoscopic and macroscopic materials is explored, and their anti-cancer applications are investigated. First, nanoscale assembly is examined in the context of an anti-angiogenic PA bearing the G-helix motif of maspin, a tumor suppressor protein. Assembly of this maspin-mimetic PA (MMPA) stabilizes the native G-helix conformation and improves binding to endothelial cells. Furthermore, PA nanostructures significantly increase cell adhesion to fibronectin as compared to G-helix peptide alone. Combined with its inhibitory effect on cell migration, MMPA nanostructures thus show anti-angiogenic activity on par with maspin protein in vitro and in vivo. Second, assembly of cationic PAs with hyaluronic acid (HA), an anionic polyelectrolyte, into macroscopic membranes is explored using PAs with identical formal charge but systematically varied self-assembly domains. Results suggest that membrane formation is dictated by the initial moments of component aggregation and is highly sensitive to PA molecular structure via nanoscale assembly. Specifically, PAs with beta-sheet forming residues are nanofibrous and have high surface charge density, leading to robust membranes with aligned-fiber microstructure. PAs without beta-sheet forming residues are nanospherical and have low surface charge density, leading to weak membranes with non-fibrous finger-like microstructure. Lastly, the principles of PA-HA membrane assembly are applied towards development of anti-cancer therapeutic biomaterials. Here, cytotoxic PAs bearing the epitope (KLAKLAKbeta)2 are co-assembled with non-bioactive cationic PA in order to achieve varying nanoscale morphology. These nanostructures are then

  9. Soft x-ray microscopy - a powerful analytical tool to image magnetism down to fundamental length and times scales

    SciTech Connect

    Fischer, Peter

    2008-08-01

    The magnetic properties of low dimensional solid state matter is of the utmost interest both scientifically as well as technologically. In addition to the charge of the electron which is the base for current electronics, by taking into account the spin degree of freedom in future spintronics applications open a new avenue. Progress towards a better physical understanding of the mechanism and principles involved as well as potential applications of nanomagnetic devices can only be achieved with advanced analytical tools. Soft X-ray microscopy providing a spatial resolution towards 10nm, a time resolution currently in the sub-ns regime and inherent elemental sensitivity is a very promising technique for that. This article reviews the recent achievements of magnetic soft X-ray microscopy by selected examples of spin torque phenomena, stochastical behavior on the nanoscale and spin dynamics in magnetic nanopatterns. The future potential with regard to addressing fundamental magnetic length and time scales, e.g. imaging fsec spin dynamics at upcoming X-ray sources is pointed out.

  10. Imaging of Acoustically Coupled Oscillations Due to Flow Past a Shallow Cavity: Effect of Cavity Length Scale

    SciTech Connect

    P. Oshkai; M. Geveci; D. Rockwell; M. Pollack

    2002-12-12

    Flow-acoustic interactions due to fully turbulent inflow past a shallow axisymmetric cavity mounted in a pipe are investigated using a technique of high-image-density particle image velocimetry in conjunction with unsteady pressure measurements. This imaging leads to patterns of velocity, vorticity, streamline topology, and hydrodynamic contributions to the acoustic power integral. Global instantaneous images, as well as time-averaged images, are evaluated to provide insight into the flow physics during tone generation. Emphasis is on the manner in which the streamwise length scale of the cavity alters the major features of the flow structure. These image-based approaches allow identification of regions of the unsteady shear layer that contribute to the instantaneous hydrodynamic component of the acoustic power, which is necessary to maintain a flow tone. In addition, combined image analysis and pressure measurements allow categorization of the instantaneous flow patterns that are associated with types of time traces and spectra of the fluctuating pressure. In contrast to consideration based solely on pressure spectra, it is demonstrated that locked-on tones may actually exhibit intermittent, non-phase-locked images, apparently due to low damping of the acoustic resonator. Locked-on flow tones (without modulation or intermittency), locked-on flow tones with modulation, and non-locked-on oscillations with short-term, highly coherent fluctuations are defined and represented by selected cases. Depending on which of,these regimes occur, the time-averaged Q (quality)-factor and the dimensionless peak pressure are substantially altered.

  11. Quantum mechanical and molecular mechanical simulation approaches bridging length and time scales for simulation of interface reactions in realistic environments

    NASA Astrophysics Data System (ADS)

    Knaup, J. M.; Tölle, P.; Köhler, Ch.; Frauenheim, Th.

    2009-10-01

    Computer-assisted design of functional materials requires methods that are able to simultaneously describe these with the necessary accuracy at the relevant time and length scales. One such possibility is the combination of classical interatomic force fields with density-functional based tight-binding (DFTB), an efficient and accurate quantum method. We employ this combination to study porous silicon dioxide functionalized with imidazole, which is used as an additive to polymer electrolyte membranes (PEM) for fuel cells applications. We analyze the water density and the dynamics of the functional groups at different temperatures by molecular dynamics simulation, whereas we calculate DFTB free energy barriers for proton transport reactions within the functionalized surface at different water contents. Combining both results, a macroscopic picture of the proton diffusion is drawn. Furthermore, we simulate the adsorption reactions of different components of an epoxide adhesive system on gamma alumina, using a direct coupling of DFTB and classical modeling. This yields direct chemical insight, how water and excess protons at the interface weaken the adhesion between epoxy polymers and natively oxidized aluminium.

  12. The Compaction of Ultramafic Cumulates in Layered Intrusions - Time and Length Scales (Invited)

    NASA Astrophysics Data System (ADS)

    Schmidt, M. W.; Manoochehri, S.

    2013-12-01

    Many large mafic intrusions have thick series of mostly ultramafic cumulates composed of dense cumulus minerals (chromite, olivine, pyroxenes) precipitated from low viscosity (roughly basaltic) liquids. To understand the time and length scales involved, the crystal settling and compaction process was simulated through centrifuge-assisted experiments of olivine or chromite in basaltic melt. Experiments were performed in a centrifuging piston cylinder at 200-1500 g, 1200-1300 C, 0.5-1.1 GPa on previously annealed and texturally equilibrated samples. The mechanical settling of the dense olivine or chromite suspensions occurs at 1/6 and 1/2 the speed of simple Stokes settling. The porosity (φm ) of orthocumulates resulting from gravitational settling is 50-55 %, pile up times for natural grain sizes result to 0.1-10 m/day. Hence, gravitational deposition (including re-deposition) of crystals may take place within years, i.e. almost instantaneously with progressing crystallization. After (re-)deposition, grains rest on each other. Further (chemical) compaction occurs through pressure dissolution at grain contacts, olivine or chromite re-precipitates where in contact with melt. Concomitantly excess liquid is expulsed from the cumulate layer. Centrifugation let to porosities as low as 30.3 vol% for olivine. The crystal content at the bottom of the experimentally compacted cumulate is 1-φm ~ log(Δρ h a t), where Δρ = crystal-melt density difference, h = crystal layer thickness, a = acceleration and t = time. Compaction is hence proportional to effective stress integrated over time indicating that pressure dissolution is the dominant mechanism. Notably, chromite crystals compact only about half as fast as olivine crystals. The compaction limit, i.e. the lowermost porosity to be reached, is calculated by equating the lithostatic and hydraulic pressure gradients in the cumulate and results to 3-5 % porosity for the experiments. Crystal size distribution curves and a

  13. Motion of nanoprobes in complex liquids within the framework of the length-scale dependent viscosity model.

    PubMed

    Kalwarczyk, Tomasz; Sozanski, Krzysztof; Ochab-Marcinek, Anna; Szymanski, Jedrzej; Tabaka, Marcin; Hou, Sen; Holyst, Robert

    2015-09-01

    This paper deals with the recent phenomenological model of the motion of nanoscopic objects (colloidal particles, proteins, nanoparticles, molecules) in complex liquids. We analysed motion in polymer, micellar, colloidal and protein solutions and the cytoplasm of living cells using the length-scale dependent viscosity model. Viscosity monotonically approaches macroscopic viscosity as the size of the object increases and thus gives a single, coherent picture of motion at the nano and macro scale. The model includes interparticle interactions (solvent-solute), temperature and the internal structure of a complex liquid. The depletion layer ubiquitously occurring in complex liquids is also incorporated into the model. We also discuss the biological aspects of crowding in terms of the length-scale dependent viscosity model.

  14. Lagrangian Formulation of a Magnetostatic Field in the Presence of a Minimal Length Scale Based on the Kempf Algebra

    NASA Astrophysics Data System (ADS)

    Moayedi, S. K.; Setare, M. R.; Khosropour, B.

    2013-11-01

    In the 1990s, Kempf and his collaborators Mangano and Mann introduced a D-dimensional (β, β‧)-two-parameter deformed Heisenberg algebra which leads to an isotropic minimal length (\\triangle Xi)\\min = \\hbar √ {Dβ +β '}, \\forall i\\in \\{1, 2, ..., D\\}. In this work, the Lagrangian formulation of a magnetostatic field in three spatial dimensions (D = 3) described by Kempf algebra is presented in the special case of β‧ = 2β up to the first-order over β. We show that at the classical level there is a similarity between magnetostatics in the presence of a minimal length scale (modified magnetostatics) and the magnetostatic sector of the Abelian Lee-Wick model in three spatial dimensions. The integral form of Ampere's law and the energy density of a magnetostatic field in the modified magnetostatics are obtained. Also, the Biot-Savart law in the modified magnetostatics is found. By studying the effect of minimal length corrections to the gyromagnetic moment of the muon, we conclude that the upper bound on the isotropic minimal length scale in three spatial dimensions is 4.42×10-19 m. The relationship between magnetostatics with a minimal length and the Gaete-Spallucci nonlocal magnetostatics [J. Phys. A: Math. Theor. 45, 065401 (2012)] is investigated.

  15. Scaling between superconducting critical temperature and structural coherence length in YBa2Cu3O6.9 films

    NASA Astrophysics Data System (ADS)

    Gauzzi, A.; Jönsson-Åkerman, B. Johan; Clerc-Dubois, A.; Pavuna, D.

    2000-09-01

    Measurements of critical temperature Tc in superconducting YBa2Cu3O6.9 films with reduced long-range structural order show the validity of the empirical scaling relation ΔTc propto rc-2 between disorder-induced reduction of Tc and structural coherence length rc in the ab-plane. This result is quantitatively explained by the disorder-induced confinement of the charge carriers within each ordered domain of size rc. Our analysis of the data based on this picture enables us to precisely determine the Ginzburg-Landau superconducting coherence length in the ab-plane, ξab = 1.41 ± 0.04 nm.

  16. On determining characteristic length scales in pressure-gradient turbulent boundary layers

    NASA Astrophysics Data System (ADS)

    Vinuesa, R.; Bobke, A.; Örlü, R.; Schlatter, P.

    2016-05-01

    In the present work, we analyze three commonly used methods to determine the edge of pressure gradient turbulent boundary layers: two based on composite profiles, the one by Chauhan et al. ["Criteria for assessing experiments in zero pressure gradient boundary layers," Fluid Dyn. Res. 41, 021404 (2009)] and the one by Nickels ["Inner scaling for wall-bounded flows subject to large pressure gradients," J. Fluid Mech. 521, 217-239 (2004)], and the other one based on the condition of vanishing mean velocity gradient. Additionally, a new method is introduced based on the diagnostic plot concept by Alfredsson et al. ["A new scaling for the streamwise turbulence intensity in wall-bounded turbulent flows and what it tells us about the `outer' peak," Phys. Fluids 23, 041702 (2011)]. The boundary layers developing over the suction and pressure sides of a NACA4412 wing section, extracted from a direct numerical simulation at chord Reynolds number Rec = 400 000, are used as the test case, besides other numerical and experimental data from favorable, zero, and adverse pressure-gradient flat-plate turbulent boundary layers. We find that all the methods produce robust results with mild or moderate pressure gradients, although the composite-profile techniques require data preparation, including initial estimations of fitting parameters and data truncation. Stronger pressure gradients (with a Rotta-Clauser pressure-gradient parameter β larger than around 7) lead to inconsistent results in all the techniques except the diagnostic plot. This method also has the advantage of providing an objective way of defining the point where the mean streamwise velocity is 99% of the edge velocity and shows consistent results in a wide range of pressure gradient conditions, as well as flow histories. Collapse of intermittency factors obtained from a wide range of pressure-gradient and Re conditions on the wing further highlights the robustness of the diagnostic plot method to determine the

  17. Dependence of displacement-length scaling relations for fractures and deformation bands on the volumetric changes across them

    USGS Publications Warehouse

    Schultz, R.A.; Soliva, R.; Fossen, H.; Okubo, C.H.; Reeves, D.M.

    2008-01-01

    Displacement-length data from faults, joints, veins, igneous dikes, shear deformation bands, and compaction bands define two groups. The first group, having a power-law scaling relation with a slope of n = 1 and therefore a linear dependence of maximum displacement and discontinuity length (Dmax = ??L), comprises faults and shear (non-compactional or non-dilational) deformation bands. These shearing-mode structures, having shearing strains that predominate over volumetric strains across them, grow under conditions of constant driving stress, with the magnitude of near-tip stress on the same order as the rock's yield strength in shear. The second group, having a power-law scaling relation with a slope of n = 0.5 and therefore a dependence of maximum displacement on the square root of discontinuity length (Dmax = ??L0.5), comprises joints, veins, igneous dikes, cataclastic deformation bands, and compaction bands. These opening- and closing-mode structures grow under conditions of constant fracture toughness, implying significant amplification of near-tip stress within a zone of small-scale yielding at the discontinuity tip. Volumetric changes accommodated by grain fragmentation, and thus control of propagation by the rock's fracture toughness, are associated with scaling of predominantly dilational and compactional structures with an exponent of n = 0.5. ?? 2008 Elsevier Ltd.

  18. Effect of regional lung inflation on ventilation heterogeneity at different length scales during mechanical ventilation of normal sheep lungs.

    PubMed

    Wellman, Tyler J; Winkler, Tilo; Costa, Eduardo L V; Musch, Guido; Harris, R Scott; Venegas, Jose G; Vidal Melo, Marcos F

    2012-09-01

    Heterogeneous, small-airway diameters and alveolar derecruitment in poorly aerated regions of normal lungs could produce ventilation heterogeneity at those anatomic levels. We modeled the washout kinetics of (13)NN with positron emission tomography to examine how specific ventilation (sV) heterogeneity at different length scales is influenced by lung aeration. Three groups of anesthetized, supine sheep were studied: high tidal volume (Vt; 18.4 ± 4.2 ml/kg) and zero end-expiratory pressure (ZEEP) (n = 6); low Vt (9.2 ± 1.0 ml/kg) and ZEEP (n = 6); and low Vt (8.2 ± 0.2 ml/kg) and positive end-expiratory pressure (PEEP; 19 ± 1 cmH(2)O) (n = 4). We quantified fractional gas content with transmission scans, and sV with emission scans of infused (13)NN-saline. Voxel (13)NN-washout curves were fit with one- or two-compartment models to estimate sV. Total heterogeneity, measured as SD[log(10)(sV)], was divided into length-scale ranges by measuring changes in variance of log(10)(sV), resulting from progressive filtering of sV images. High-Vt ZEEP showed higher sV heterogeneity at <12- (P < 0.01), 12- to 36- (P < 0.01), and 36- to 60-mm (P < 0.05) length scales compared with low-Vt PEEP, with low-Vt ZEEP in between. Increased heterogeneity was associated with the emergence of low sV units in poorly aerated regions, with a high correlation (r = 0.95, P < 0.001) between total heterogeneity and the fraction of lung with slow washout. Regional mean fractional gas content was inversely correlated with regional sV heterogeneity at <12- (r = -0.67), 12- to 36- (r = -0.74), and >36-mm (r = -0.72) length scales (P < 0.001). We conclude that sV heterogeneity at length scales <60 mm increases in poorly aerated regions of mechanically ventilated normal lungs, likely due to heterogeneous small-airway narrowing and alveolar derecruitment. PEEP reduces sV heterogeneity by maintaining lung expansion and airway patency at those small length scales.

  19. Static and dynamic length scales in supercooled liquids: insights from molecular dynamics simulations of water and tri-propylene oxide.

    PubMed

    Klameth, F; Henritzi, P; Vogel, M

    2014-04-14

    We perform molecular dynamics simulations to study static and dynamic length scales in molecular supercooled liquids, in particular, water. For a determination of these scales, we use equilibrium configurations and pin appropriate subsets of molecules so as to obtain random matrices, cylindrical pores, and slit confinements. Static length scales ξ(s) are determined by analyzing overlap correlation functions for various fractions of pinned molecules or distances to the confining walls. For water in all confinements and for propylene oxide trimers in random geometry, a linear increase of ξ(s) with inverse temperature is found. Dynamic length scales ξ(d) are determined by analogous analysis of fraction-dependent or position-resolved correlation times of structural relaxation. While ξ(d) continuously grows upon cooling in the cylindrical and slit confinements, we find no evidence for a temperature dependence in random matrices, implying that molecular dynamics in parsed volumes is qualitatively different from that in bulk liquids. Finally, we study possible connections between the growth of the static and dynamic length scales and the slowdown of the structural relaxation of the supercooled bulk liquids. For water, we observe a linear relation between ln τ(α) and ξ(s)²/T in the whole accessible range down to the critical temperature of mode-coupling theory, T(c). In the weakly supercooled regime, the same relation holds also for ξ(d), as obtained from cylindrical and slit confinements, but deviations from this behavior are observed near T(c). The results are discussed in connection with random first-order theory and experimental studies of liquid dynamics in nanoscopic confinements and binary mixtures.

  20. Additional Validity Evidence and Across-Group Equivalency of the "HOPE Teacher Rating Scale"

    ERIC Educational Resources Information Center

    Peters, Scott J.; Gentry, Marcia

    2013-01-01

    The "HOPE Scale" was developed to identify academic and social components of giftedness and talent in elementary-aged students with particular attention to students from low-income and/or culturally diverse families. Based on previous findings, additional research was conducted on revisions made to the "HOPE Scale". Items were added, and 71…

  1. CHARACTERISTIC LENGTH SCALE OF INPUT DATA IN DISTRIBUTED MODELS: IMPLICATIONS FOR MODELING GRID SIZE. (R824784)

    EPA Science Inventory

    The appropriate spatial scale for a distributed energy balance model was investigated by: (a) determining the scale of variability associated with the remotely sensed and GIS-generated model input data; and (b) examining the effects of input data spatial aggregation on model resp...

  2. Evaluation of a Two-Length Scale Turbulence Model with Experiments on Shock-Driven Turbulent Mixing

    NASA Astrophysics Data System (ADS)

    Carter, John; Gore, Rob; Ranjan, Devesh

    2015-11-01

    A new second moment turbulence model which uses separate transport and decay length scales is used to model the shock-driven instability. The ability of the model to capture the evolution of turbulence statistics and mixing is discussed. Evaluation is based on comparison to the Georgia Tech shock tube experiments. In the experiments a membraneless light-over-heavy interface is created. There is a long-wavelength perturbation which exists due to inclination of the entire shock tube. By limiting calculations to one dimension, there is not a geometric description of the incline, and the ability of the transport length scale alone to capture the effect of the long-wavelength perturbation is tested.

  3. The radial scale length of turbulent fluctuations in the main core of TFTR plasmas

    SciTech Connect

    Mazzucato, E.; Nazikian, R.

    1993-07-01

    A new theory of microwave reflectometry in tokamaks has been developed which accounts for all the major characteristics of waves reflected from strong fluctuations near the cutoff layer. The theory has been used for studying the turbulence in the main core of neutral beam heated plasmas of the TFTR tokamak in the supershot regime. The results indicate that the radial correlation length of density fluctuations is a weak decreasing function of beam power, from {approx}4 cm in Ohmic to {approx}2 cm at 14 MW of heating power. This corresponds to the range of wavelengths k{sub {perpendicular}}{rho}{sub i}{approx}0.1--0.3. Over the same interval of heating powers, the level of density fluctuations is observed to steadily increase with beam power by more than an order of magnitude. This trend is inconsistent with mixing length estimates of the fluctuation level.

  4. Distinct Length Scales in the VO{sub 2} Metal–Insulator Transition Revealed by Bi-chromatic Optical Probing

    SciTech Connect

    Wang, Lei; Novikova, Irina B.; Klopf, John M.; Madaras, Scott E.; Williams, Gwyn P.; Madaras, Eric; Lu, Liwei; Wolf, Stuart A.; Lukaszew, Rosa A.

    2014-01-01

    Upon a heating-induced metal–instulator transition (MIT) in VO{sub 2}, microscopic metallic VO{sub 2} puddles nucleate and coarsen within the insulating matrix. This coexistence of the two phases across the transition spans distinct length scales as their relative domain sizes change. Far-field optical probing is applied to follow the dynamic evolution of the highly correlated metallic domains as the MIT progresses.

  5. Does the orbit-averaged theory require a scale separation between periodic orbit size and perturbation correlation length?

    SciTech Connect

    Zhang, Wenlu; Lin, Zhihong

    2013-10-15

    Using the canonical perturbation theory, we show that the orbit-averaged theory only requires a time-scale separation between equilibrium and perturbed motions and verifies the widely accepted notion that orbit averaging effects greatly reduce the microturbulent transport of energetic particles in a tokamak. Therefore, a recent claim [Hauff and Jenko, Phys. Rev. Lett. 102, 075004 (2009); Jenko et al., ibid. 107, 239502 (2011)] stating that the orbit-averaged theory requires a scale separation between equilibrium orbit size and perturbation correlation length is erroneous.

  6. Dispersive and mixing characteristics for turbulent porous media flows based on local length and time scale measurements

    NASA Astrophysics Data System (ADS)

    Liburdy, James; Patil, Vishal

    2012-11-01

    Porous media flows have a very wide range of applications, both in engineering applications and natural flows. Local mixing and dispersion is strongly influenced by the complex pore geometry. Understanding mixing properties requires knowledge of the range of scales present within the flow and how they vary with Reynolds number. Experiments have been conducted using time resolved two component PIV based on refractive index matching of the solid and liquid phases. The flow characteristics vary over a large range of Reynolds numbers, typically based on an average pore velocity and hydraulic diameter or bead size as the characteristic length. In this study we examine the effect of increased pore Reynolds number on the turbulence characteristics for Reynolds numbers from approximately 400 to 4000. In particular the integral and Kolmogorov length scales are estimated, along with the determination of the integral velocity and Eulerian time scales. These are then used to estimate the Lagrangian time scale. The asymptotic behavior associated with increasing pore Reynolds number is shown, and used to evaluate the scaling relationships. Results are also used to demonstrate the evaluation of the mechanical dispersion coefficient and that it compares well with results obtained using global methods such as solute breakthrough curves. Funding by NSF grant 0933857, Particulate and Multiphase Processing.

  7. Length-scale mediated adhesion and directed growth of neural cells by surface-patterned poly(ethylene glycol) hydrogels.

    PubMed

    Krsko, Peter; McCann, Thomas E; Thach, Thu-Trang; Laabs, Tracy L; Geller, Herbert M; Libera, Matthew R

    2009-02-01

    We engineered surfaces that permit the adhesion and directed growth of neuronal cell processes but that prevent the adhesion of astrocytes. This effect was achieved based on the spatial distribution of sub-micron-sized cell-repulsive poly(ethylene glycol) [PEG] hydrogels patterned on an otherwise cell-adhesive substrate. Patterns were identified that promoted cellular responses ranging from complete non-attachment, selective attachment, and directed growth at both cellular and subcellular length scales. At the highest patterning density where the individual hydrogels almost overlapped, there was no cellular adhesion. As the spacing between individual hydrogels was increased, patterns were identified where neurites could grow on the adhesive surface between hydrogels while astrocytes were unable to adhere. Patterns such as lines or arrays were identified that could direct the growth of these subcellular neuronal processes. At higher hydrogel spacings, both neurons and astrocytes adhered and grew in a manner approaching that of unpatterned control surfaces. Patterned lines could once again direct growth at cellular length scales. Significantly, we have demonstrated that the patterning of sub-micron/nano scale cell-repulsive features at microscale lengths on an otherwise cell-adhesive surface can differently control the adhesion and growth of cells and cell processes based on the difference in their characteristic sizes. This concept could potentially be applied to an implantable nerve-guidance device that would selectively enable regrowing axons to bridge a spinal-cord injury without interference from the glial scar.

  8. Field Testing of a Wet FGD Additive for Enhanced Mercury Control - Pilot-Scale Test Results

    SciTech Connect

    Gary M. Blythe

    2006-03-01

    This Topical Report summarizes progress on Cooperative Agreement DE-FC26-04NT42309, ''Field Testing of a Wet FGD Additive.'' The objective of the project is to demonstrate the use of a flue gas desulfurization (FGD) additive, Degussa Corporation's TMT-15, to prevent the reemissions of elemental mercury (Hg{sup 0}) in flue gas exiting wet FGD systems on coal-fired boilers. Furthermore, the project intends to demonstrate that the additive can be used to precipitate most of the mercury (Hg) removed in the wet FGD system as a fine TMT salt that can be separated from the FGD liquor and bulk solid byproducts for separate disposal. The project will conduct pilot and full-scale tests of the TMT-15 additive in wet FGD absorbers. The tests are intended to determine required additive dosage requirements to prevent Hg{sup 0} reemissions and to separate mercury from the normal FGD byproducts for three coal types: Texas lignite/Power River Basin (PRB) coal blend, high-sulfur Eastern bituminous coal, and low-sulfur Eastern bituminous coal. The project team consists of URS Group, Inc., EPRI, TXU Generation Company LP, Southern Company, and Degussa Corporation. TXU Generation has provided the Texas lignite/PRB co-fired test site for pilot FGD tests, Monticello Steam Electric Station Unit 3. Southern Company is providing the low-sulfur Eastern bituminous coal host site for wet scrubbing tests, as well as the pilot and full-scale jet bubbling reactor (JBR) FGD systems to be tested. A third utility, to be named later, will provide the high-sulfur Eastern bituminous coal full-scale FGD test site. Degussa Corporation is providing the TMT-15 additive and technical support to the test program. The project is being conducted in six tasks. Of the six project tasks, Task 1 involves project planning and Task 6 involves management and reporting. The other four tasks involve field testing on FGD systems, either at pilot or full scale. The four tasks include: Task 2 - Pilot Additive Testing in

  9. Imaging of Acoustically Coupled Oscillations Due to Flow Past a Shallow Cavity: Effect of Cavity Length Scale

    SciTech Connect

    P Oshkai; M Geveci; D Rockwell; M Pollack

    2004-05-24

    Flow-acoustic interactions due to fully turbulent inflow past a shallow axisymmetric cavity mounted in a pipe, which give rise to flow tones, are investigated using a technique of high-image-density particle image velocimetry in conjunction with unsteady pressure measurements. This imaging leads to patterns of velocity, vorticity, streamline topology, and hydrodynamic contributions to the acoustic power integral. Global instantaneous images, as well as time-averaged images, are evaluated to provide insight into the flow physics during tone generation. Emphasis is on the manner in which the streamwise length scale of the cavity alters the major features of the flow structure. These image-based approaches allow identification of regions of the unsteady shear layer that contribute to the instantaneous hydrodynamic component of the acoustic power, which is necessary to maintain a flow tone. In addition, combined image analysis and pressure measurements allow categorization of the instantaneous flow patterns that are associated with types of time traces and spectra of the fluctuating pressure. In contrast to consideration based solely on pressure spectra, it is demonstrated that locked-on tones may actually exhibit intermittent, non-phase-locked images, apparently due to low damping of the acoustic resonator. Locked-on flow tones (without modulation or intermittency), locked-on flow tones with modulation, and non-locked-on oscillations with short-term, highly coherent fluctuations are defined and represented by selected cases. Depending on which of these regimes occur, the time-averaged Q (quality)-factor and the dimensionless peak pressure are substantially altered.

  10. The radial scale length of turbulent fluctuations in the main core of TFTR plasmas

    SciTech Connect

    Mazzucato, E.; Nazikian, R.

    1993-07-01

    A new theory of microwave reflectometry in tokamaks has been developed which accounts for all the major characteristics of waves reflected from strong fluctuations near the cutoff layer. The theory has been used for studying the turbulence in the main core of neutral beam heated plasmas of the TFTR tokamak in the supershot regime. The results indicate that the radial correlation length of density fluctuations is a weak decreasing function of beam power, from [approximately]4 cm in Ohmic to [approx]2 cm at 14 MW of heating power. This corresponds to the range of wavelengths k[sub [perpendicular

  11. Diamagnetic length scales of the Condon domain phase in Lifschitz-Kosevich-Shoenberg approximation

    NASA Astrophysics Data System (ADS)

    Logoboy, Nathan; Joss, Walter

    2009-12-01

    Equilibrium properties of the non-uniform diamagnetic phase in normal metals (Condon domains) are studied theoretically in the framework of Lifschitz-Kosevich-Shoenberg (LKS) approximation. It is found that characteristic diamagnetic lengths of the phase, e.g. a period of the domain structure and width of interface boundary between domains, as well as specific surface energy of domain wall, are strongly affected by electron correlations and depend on temperature, magnetic field and purity of the sample. The developed theory is in a good agreement with existent experiment data.

  12. The narrow pulse approximation and long length scale determination in xenon gas diffusion NMR studies of model porous media.

    PubMed

    Mair, R W; Sen, P N; Hürlimann, M D; Patz, S; Cory, D G; Walsworth, R L

    2002-06-01

    We report a systematic study of xenon gas diffusion NMR in simple model porous media, random packs of mono-sized glass beads, and focus on three specific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion of spins on the order of the pore dimensions during the application of the diffusion encoding gradient pulses in a PGSE experiment (breakdown of the narrow pulse approximation and imperfect background gradient cancellation), (ii) the ability to derive long length scale structural information, and (iii) effects of finite sample size. We find that the time-dependent diffusion coefficient, D(t), of the imbibed xenon gas at short diffusion times in small beads is significantly affected by the gas pressure. In particular, as expected, we find smaller deviations between measured D(t) and theoretical predictions as the gas pressure is increased, resulting from reduced diffusion during the application of the gradient pulse. The deviations are then completely removed when water D(t) is observed in the same samples. The use of gas also allows us to probe D(t) over a wide range of length scales and observe the long time asymptotic limit which is proportional to the inverse tortuosity of the sample, as well as the diffusion distance where this limit takes effect (approximately 1-1.5 bead diameters). The Padé approximation can be used as a reference for expected xenon D(t) data between the short and the long time limits, allowing us to explore deviations from the expected behavior at intermediate times as a result of finite sample size effects. Finally, the application of the Padé interpolation between the long and the short time asymptotic limits yields a fitted length scale (the Padé length), which is found to be approximately 0.13b for all bead packs, where b is the bead diameter. PMID:12165255

  13. The narrow pulse approximation and long length scale determination in xenon gas diffusion NMR studies of model porous media

    NASA Technical Reports Server (NTRS)

    Mair, R. W.; Sen, P. N.; Hurlimann, M. D.; Patz, S.; Cory, D. G.; Walsworth, R. L.

    2002-01-01

    We report a systematic study of xenon gas diffusion NMR in simple model porous media, random packs of mono-sized glass beads, and focus on three specific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion of spins on the order of the pore dimensions during the application of the diffusion encoding gradient pulses in a PGSE experiment (breakdown of the narrow pulse approximation and imperfect background gradient cancellation), (ii) the ability to derive long length scale structural information, and (iii) effects of finite sample size. We find that the time-dependent diffusion coefficient, D(t), of the imbibed xenon gas at short diffusion times in small beads is significantly affected by the gas pressure. In particular, as expected, we find smaller deviations between measured D(t) and theoretical predictions as the gas pressure is increased, resulting from reduced diffusion during the application of the gradient pulse. The deviations are then completely removed when water D(t) is observed in the same samples. The use of gas also allows us to probe D(t) over a wide range of length scales and observe the long time asymptotic limit which is proportional to the inverse tortuosity of the sample, as well as the diffusion distance where this limit takes effect (approximately 1-1.5 bead diameters). The Pade approximation can be used as a reference for expected xenon D(t) data between the short and the long time limits, allowing us to explore deviations from the expected behavior at intermediate times as a result of finite sample size effects. Finally, the application of the Pade interpolation between the long and the short time asymptotic limits yields a fitted length scale (the Pade length), which is found to be approximately 0.13b for all bead packs, where b is the bead diameter. c. 2002 Elsevier Sciences (USA).

  14. AC electrified jets in a flow-focusing device: Jet length scaling.

    PubMed

    Castro-Hernández, Elena; García-Sánchez, Pablo; Alzaga-Gimeno, Javier; Tan, Say Hwa; Baret, Jean-Christophe; Ramos, Antonio

    2016-07-01

    We use a microfluidic flow-focusing device with integrated electrodes for controlling the production of water-in-oil drops. In a previous work, we reported that very long jets can be formed upon application of AC fields. We now study in detail the appearance of the long jets as a function of the electrical parameters, i.e., water conductivity, signal frequency, and voltage amplitude. For intermediate frequencies, we find a threshold voltage above which the jet length rapidly increases. Interestingly, this abrupt transition vanishes for high frequencies of the signal and the jet length grows smoothly with voltage. For frequencies below a threshold value, we previously reported a transition from a well-behaved uniform jet to highly unstable liquid structures in which axisymmetry is lost rather abruptly. These liquid filaments eventually break into droplets of different sizes. In this work, we characterize this transition with a diagram as a function of voltage and liquid conductivity. The electrical response of the long jets was studied via a distributed element circuit model. The model allows us to estimate the electric potential at the tip of the jet revealing that, for any combination of the electrical parameters, the breakup of the jet occurs at a critical value of this potential. We show that this voltage is around 550 V for our device geometry and choice of flow rates.

  15. AC electrified jets in a flow-focusing device: Jet length scaling.

    PubMed

    Castro-Hernández, Elena; García-Sánchez, Pablo; Alzaga-Gimeno, Javier; Tan, Say Hwa; Baret, Jean-Christophe; Ramos, Antonio

    2016-07-01

    We use a microfluidic flow-focusing device with integrated electrodes for controlling the production of water-in-oil drops. In a previous work, we reported that very long jets can be formed upon application of AC fields. We now study in detail the appearance of the long jets as a function of the electrical parameters, i.e., water conductivity, signal frequency, and voltage amplitude. For intermediate frequencies, we find a threshold voltage above which the jet length rapidly increases. Interestingly, this abrupt transition vanishes for high frequencies of the signal and the jet length grows smoothly with voltage. For frequencies below a threshold value, we previously reported a transition from a well-behaved uniform jet to highly unstable liquid structures in which axisymmetry is lost rather abruptly. These liquid filaments eventually break into droplets of different sizes. In this work, we characterize this transition with a diagram as a function of voltage and liquid conductivity. The electrical response of the long jets was studied via a distributed element circuit model. The model allows us to estimate the electric potential at the tip of the jet revealing that, for any combination of the electrical parameters, the breakup of the jet occurs at a critical value of this potential. We show that this voltage is around 550 V for our device geometry and choice of flow rates. PMID:27375826

  16. Scaling Between Fault Length, Damaged Zone Thickness and Width of Secondary Fault Fans Derived from Fracture Mechanics

    NASA Astrophysics Data System (ADS)

    Ampuero, Jean Paul; Mao, Xiaolin

    2016-04-01

    The interaction between earthquakes, fault network geometry and fault zone structure is a key question motivating the integration of dynamic rupture and long-term crustal deformation modeling. Here, we address the scaling between fault structural properties from the perspective of dynamic and quasi-static processes involved in fault system evolution. Faults are surrounded by materials damaged through quasi-static and dynamic processes, forming damaged zones whose thickness and damage intensity may vary as a function of fault maturity and length. In the vicinity (typically less than a few hundred meters) of their principal slip surface, faults develop an "inner damage zone", usually characterized by micro-fracture observations. At a larger scale, faults develop an "outer damage zone" of secondary macroscopic fault branches at their tips, which organize into fans of splay faults. Inner damage zones can significantly affect earthquake ruptures, enhance near-field ground motions and facilitate fluid transport in the crust. Fault zone trapped waves can generate pulse-like rupture and oscillatory rupture speed, facilitate supershear rupture transition and allow for steady rupture propagation at speeds that are unstable or inadmissible in homogeneous media. The effects of a fault damage zone crucially depend on its thickness. Field observations of inner damage zone thickness as a function of cumulated slip show linear scaling at small slip but saturation at large slip, with maximum damage zone thickness of a few hundred meters. We previously developed fracture mechanics theoretical arguments and dynamic rupture simulations with off-fault inelastic deformation that predict saturation of the thickness of co-seismic damage zone controlled by the depth extent of the seismogenic zone. In essence, the stress intensity factor at the front of a rupture, which controls the distance reached by the large off-fault stresses that cause damage, scales with the shortest characteristic

  17. Characterization of light transport in scattering media at sub-diffusion length scales with Low-coherence Enhanced Backscattering.

    PubMed

    Turzhitsky, Vladimir; Rogers, Jeremy D; Mutyal, Nikhil N; Roy, Hemant K; Backman, Vadim

    2010-01-01

    Low-coherence enhanced backscattering (LEBS) is a technique that has recently shown promise for tissue characterization and the detection of early pre-cancer. Although several Monte Carlo models of LEBS have been described, these models have not been accurate enough to predict all of the experimentally observed LEBS features. We present an appropriate Monte Carlo model to simulate LEBS peak properties from polystyrene microsphere suspensions in water. Results show that the choice of the phase function greatly impacts the accuracy of the simulation when the transport mean free path (ls*) is much greater than the spatial coherence length (L(SC)). When ls* < L(SC), a diffusion approximation based model of LEBS is sufficiently accurate. We also use the Monte Carlo model to validate that LEBS can be used to measure the radial scattering probability distribution (radial point spread function), p(r), at small length scales and demonstrate LEBS measurements of p(r) from biological tissue. In particular, we show that pre-cancerous and benign mucosal tissues have different small length scale light transport properties.

  18. Characterization of light transport in scattering media at sub-diffusion length scales with Low-coherence Enhanced Backscattering

    PubMed Central

    Turzhitsky, Vladimir; Rogers, Jeremy D.; Mutyal, Nikhil N.; Roy, Hemant K.; Backman, Vadim

    2009-01-01

    Low-coherence enhanced backscattering (LEBS) is a technique that has recently shown promise for tissue characterization and the detection of early pre-cancer. Although several Monte Carlo models of LEBS have been described, these models have not been accurate enough to predict all of the experimentally observed LEBS features. We present an appropriate Monte Carlo model to simulate LEBS peak properties from polystyrene microsphere suspensions in water. Results show that the choice of the phase function greatly impacts the accuracy of the simulation when the transport mean free path (ls*) is much greater than the spatial coherence length (LSC). When ls* < LSC, a diffusion approximation based model of LEBS is sufficiently accurate. We also use the Monte Carlo model to validate that LEBS can be used to measure the radial scattering probability distribution (radial point spread function), p(r), at small length scales and demonstrate LEBS measurements of p(r) from biological tissue. In particular, we show that pre-cancerous and benign mucosal tissues have different small length scale light transport properties. PMID:21037980

  19. Length-Scale Mediated Adhesion and Directed Growth of Neural Cells by Surface-Patterned Poly(ethylene glycol) Hydrogels

    PubMed Central

    Krsko, Peter; McCann, Thomas; Thach, Thu-Trang; Laabs, Tracy; Geller, Herbert M.; Libera, Matthew

    2012-01-01

    We engineered surfaces that permit the adhesion and directed growth of neuronal cell processes – axons – but that prevent the adhesion of astrocytes. This effect was achieved based on the spatial distribution of cell-repulsive poly(ethylene glycol) [PEG] nanohydrogels patterned on an otherwise cell-adhesive substrate. Patterns were identified that promoted cellular responses ranging from complete non-attachment, selective attachment, and directed growth at both cellular and subcellular length scales. At the highest patterning density where the individual nanohydrogels almost overlapped, there was no cellular adhesion. As the spacing between individual nanohydrogels was increased, patterns were identified where axons could grow on the adhesive surface between nanohydrogels while astrocytes were unable to adhere. Patterns such as lines or arrays were identified that could direct the growth of these subcellular neuronal processes. At higher nanohydrogel spacings, both neurons and astrocytes adhered and grew in a manner approaching that of unpatterned control surfaces. Patterned lines could once again direct growth at cellular length scales. Significantly, we have demonstrated that the patterning of nanoscale cell-repulsive features at microscale lengths on an otherwise cell-adhesive surface can differently control the adhesion and growth of cells and cell processes based on the difference in their characteristic sizes. This concept could potentially be applied to an implantable nerve-guidance device that would selectively enable regrowing axons to bridge a spinal-cord injury without interference from the glial scar. PMID:19026443

  20. Effects of Physical Processes and Sampling Resolution on Fault Displacement Versus Length Scaling: The Case of the Cantarell Complex Oilfield, Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Xu, Shunshan; Nieto-Samaniego, Angel F.; Murillo-Muñetón, Gustavo; Alaniz-Álvarez, Susana A.; Grajales-Nishimura, José M.; Velasquillo-Martinez, Luis G.

    2016-04-01

    In this paper, we first review some factors that may alter the fault D max /L ratio and scaling relationship. The three main physical processes are documented as follows: (1) The D max /L ratio increases in an individual segmented fault, whereas it decreases in a fault array consisting of two or more fault segments. This effect occurs at any scale during fault growth and in any type of rock. (2) Vertical restriction decreases the D max /L ratio along the fault strike due to mechanical layers. (3) The D max /L ratio increases or decreases due to fault reactivation depending on the type of reactivation. Thus, using data from the normal faults of the Cantarell oilfield in the southern Gulf of Mexico, we document that the displacement ( D max ) and length ( L) show a weak correlation of linear or power-law scaling, with exponents that are much less than 1 ( n ≈ 0.5). This scaling relation is due to the combination of the physical processes mentioned above, as well as sampling effects, such as technique resolution. These results indicate that sublinear scaling ( n ≈ 0.5) can occur as a result of more than one physical process during faulting in a studied area. In addition to the physical processes associated with brittle deformation in the studied area, the sampling resolution dramatically affects the exponents of the D max - L scaling.

  1. Intensification of sonochemical degradation of phenol using additives at pilot scale operation.

    PubMed

    Khokhawala, Ismail M; Gogate, Parag R

    2011-01-01

    The present work reports the use of sonochemical reactors for the degradation of phenol in the presence of additives with an objective of enhancing the rates of degradation at a pilot scale operation. Process intensification studies have been carried out using additives such as hydrogen peroxide (H2O2) (0.5-2.0 g/L), sodium chloride (0.5-1.5 g/L) and solid particles viz. cupric oxide (CuO) and titanium dioxide (TiO2) (0.5-2.5 g/L). Optimum concentration for H2O2 and sodium chloride has been observed beyond which no beneficial effects are obtained even with additional loadings. Maximum extent of degradation has been observed by using ultrasound/H2O2/CuO approach at a solid loading of 1.5 g/L followed by ultrasound/H2O2/TiO2 approach at a loading of 2.0 g/L. The obtained results at pilot scale operation in the current work are very important especially due to the fact that the majority of earlier studies are at laboratory scale which cannot provide the design related information for large scale operation as required scale up ratios are quite high adding a degree of uncertainty in the design. The novelty of the present work lies in the fact that it highlights successful application of sonochemical reactors for wastewater treatment at pilot scale operation.

  2. The role of discharge variation in scaling of drainage area and food chain length in rivers

    USGS Publications Warehouse

    Sabo, John L.; Finlay, Jacques C.; Kennedy, Theodore A.; Post, David M.

    2010-01-01

    Food chain length (FCL) is a fundamental component of food web structure. Studies in a variety of ecosystems suggest that FCL is determined by energy supply, environmental stability, and/or ecosystem size, but the nature of the relationship between environmental stability and FCL, and the mechanism linking ecosystem size to FCL, remain unclear. Here we show that FCL increases with drainage area and decreases with hydrologic variability and intermittency across 36 North American rivers. Our analysis further suggests that hydrologic variability is the mechanism underlying the correlation between ecosystem size and FCL in rivers. Ecosystem size lengthens river food chains by integrating and attenuating discharge variation through stream networks, thereby enhancing environmental stability in larger river systems.

  3. The role of discharge variation in scaling of drainage area and food chain length in rivers.

    PubMed

    Sabo, John L; Finlay, Jacques C; Kennedy, Theodore; Post, David M

    2010-11-12

    Food chain length (FCL) is a fundamental component of food web structure. Studies in a variety of ecosystems suggest that FCL is determined by energy supply, environmental stability, and/or ecosystem size, but the nature of the relationship between environmental stability and FCL, and the mechanism linking ecosystem size to FCL, remain unclear. Here we show that FCL increases with drainage area and decreases with hydrologic variability and intermittency across 36 North American rivers. Our analysis further suggests that hydrologic variability is the mechanism underlying the correlation between ecosystem size and FCL in rivers. Ecosystem size lengthens river food chains by integrating and attenuating discharge variation through stream networks, thereby enhancing environmental stability in larger river systems.

  4. Modeling complex phenomena: Multiple length and time scales in extended dynamical systems

    SciTech Connect

    Lomdahl, P.; Bishop, A.; Jensen, N.G.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). Using nonlinear techniques and large-scale simulations, we have systematically studied meso-scale pattern formation and dynamics in nonlinear, nonequilibrium systems exhibiting topological excitations (dislocations, vortices, vortex lines, domain walls); dislocation generation from crack fronts in ductile materials; the smoothing of rough surfaces in solid-on-solid models; ordering and melting of moving flux lattices in three-dimensional Josephson junction arrays with external magnetic field, current, and disorder; filamentary and plastic vortex flow in disordered thin films superconductors; magnetic vortices in Heisenberg spin layers; and hierarchical twinning and tweed texture in elastic models.

  5. Halogen-bonded mesogens direct polymer self-assemblies up to millimetre length scale

    PubMed Central

    Houbenov, Nikolay; Milani, Roberto; Poutanen, Mikko; Haataja, Johannes; Dichiarante, Valentina; Sainio, Jani; Ruokolainen, Janne; Resnati, Giuseppe; Metrangolo, Pierangelo; Ikkala, Olli

    2014-01-01

    Aligning polymeric nanostructures up to macroscale in facile ways remains a challenge in materials science and technology. Here we show polymeric self-assemblies where nanoscale organization guides the macroscopic alignment up to millimetre scale. The concept is shown by halogen bonding mesogenic 1-iodoperfluoroalkanes to a star-shaped ethyleneglycol-based polymer, having chloride end-groups. The mesogens segregate and stack parallel into aligned domains. This leads to layers at ~10 nm periodicity. Combination of directionality of halogen bonding, mesogen parallel stacking and minimization of interfacial curvature translates into an overall alignment in bulk and films up to millimetre scale. Upon heating, novel supramolecular halogen-bonded polymeric liquid crystallinity is also shown. As many polymers present sites capable of receiving halogen bonding, we suggest generic potential of this strategy for aligning polymer self-assemblies. PMID:24893843

  6. Polymorphism of highly cross-linked F-actin networks: Probing multiple length scales

    NASA Astrophysics Data System (ADS)

    Nguyen, Lam T.; Hirst, Linda S.

    2011-03-01

    The assembly properties of F-actin filaments in the presence of different biological cross-linker concentrations and types have been investigated using a combined approach of fluorescence confocal microscopy and coarse-grained molecular dynamics simulation. In particular for highly cross-linked regimes, new network morphologies are observed. Complex network formation and the details of the resulting structure are strongly dependent on the ratio of cross-linkers to actin monomers and cross-linker shape but only weakly dependent on overall actin concentration and filament length. The work presented here may help to provide some fundamental understanding of how excessive cross-linkers interact with the actin filament solution, creating different structures in the cell under high cross-linker concentrations. F-actin is not only of biological importance but also, as an example of a semiflexible polymer, has attracted significant interest in its physical behavior. In combination with different cross-linkers semiflexible filaments may provide new routes to bio-materials development and act as the inspiration for new hierarchical network-based materials.

  7. Compositional Patterning in Systems Driven by Competing Dynamics Of Different Length Scale

    SciTech Connect

    Enrique, Raul A.; Bellon, Pascal

    2000-03-27

    We study an alloy system where short-ranged, thermally driven diffusion competes with externally imposed, finite-ranged, athermal atomic exchanges, as is the case in alloys under irradiation. Using a Cahn-Hilliard-type approach, we show that when the range of these exchanges exceeds a critical value labyrinthine concentration patterns at a mesoscopic scale can be stabilized. Furthermore, these steady-state patterns appear only for a window of the frequency of forced exchanges. Our results suggest that ion beams may provide a novel route to stabilize and tune the size of nanoscale structural features in materials. (c) 2000 The American Physical Society.

  8. Characteristic length scales and time-averaged transport velocities of suspended sediment in the mid-Atlantic Region, USA

    NASA Astrophysics Data System (ADS)

    Pizzuto, James; Schenk, Edward R.; Hupp, Cliff R.; Gellis, Allen; Noe, Greg; Williamson, Elyse; Karwan, Diana L.; O'Neal, Michael; Marquard, Julia; Aalto, Rolf; Newbold, Denis

    2014-02-01

    Watershed Best Management Practices (BMPs) are often designed to reduce loading from particle-borne contaminants, but the temporal lag between BMP implementation and improvement in receiving water quality is difficult to assess because particles are only moved downstream episodically, resting for long periods in storage between transport events. A theory is developed that describes the downstream movement of suspended sediment particles accounting for the time particles spend in storage given sediment budget data (by grain size fraction) and information on particle transit times through storage reservoirs. The theory is used to define a suspended sediment transport length scale that describes how far particles are carried during transport events, and to estimate a downstream particle velocity that includes time spent in storage. At 5 upland watersheds of the mid-Atlantic region, transport length scales for silt-clay range from 4 to 60 km, while those for sand range from 0.4 to 113 km. Mean sediment velocities for silt-clay range from 0.0072 km/yr to 0.12 km/yr, while those for sand range from 0.0008 km/yr to 0.20 km/yr, 4-6 orders of magnitude slower than the velocity of water in the channel. These results suggest lag times of 100-1000 years between BMP implementation and effectiveness in receiving waters such as the Chesapeake Bay (where BMPs are located upstream of the characteristic transport length scale). Many particles likely travel much faster than these average values, so further research is needed to determine the complete distribution of suspended sediment velocities in real watersheds.

  9. Characteristic length scales and time-averaged transport velocities of suspended sediment in the mid-Atlantic Region, USA

    USGS Publications Warehouse

    Pizzuto, James; Schenk, Edward R.; Hupp, Cliff R.; Gellis, Allen; Noe, Greg; Williamson, Elyse; Karwan, Diana L.; O'Neal, Michael; Marquard, Julia; Aalto, Rolf; Newbold, Denis

    2014-01-01

    Watershed Best Management Practices (BMPs) are often designed to reduce loading from particle-borne contaminants, but the temporal lag between BMP implementation and improvement in receiving water quality is difficult to assess because particles are only moved downstream episodically, resting for long periods in storage between transport events. A theory is developed that describes the downstream movement of suspended sediment particles accounting for the time particles spend in storage given sediment budget data (by grain size fraction) and information on particle transit times through storage reservoirs. The theory is used to define a suspended sediment transport length scale that describes how far particles are carried during transport events, and to estimate a downstream particle velocity that includes time spent in storage. At 5 upland watersheds of the mid-Atlantic region, transport length scales for silt-clay range from 4 to 60 km, while those for sand range from 0.4 to 113 km. Mean sediment velocities for silt-clay range from 0.0072 km/yr to 0.12 km/yr, while those for sand range from 0.0008 km/yr to 0.20 km/yr, 4–6 orders of magnitude slower than the velocity of water in the channel. These results suggest lag times of 100–1000 years between BMP implementation and effectiveness in receiving waters such as the Chesapeake Bay (where BMPs are located upstream of the characteristic transport length scale). Many particles likely travel much faster than these average values, so further research is needed to determine the complete distribution of suspended sediment velocities in real watersheds.

  10. Constitutive models for linear compressible viscoelastic flows of simple liquids at nanometer length scales

    NASA Astrophysics Data System (ADS)

    Chakraborty, Debadi; Sader, John E.

    2015-05-01

    Simple bulk liquids such as water are commonly assumed to be Newtonian. While this assumption holds widely, the fluid-structure interaction of mechanical devices at nanometer scales can probe the intrinsic molecular relaxation processes in a surrounding liquid. This was recently demonstrated through measurement of the high frequency (20 GHz) linear mechanical vibrations of bipyramidal nanoparticles in simple liquids [Pelton et al., "Viscoelastic flows in simple liquids generated by vibrating nanostructures," Phys. Rev. Lett. 111, 244502 (2013)]. In this article, we review and critically assess the available constitutive equations for compressible viscoelastic flows in their linear limits—such models are required for analysis of the above-mentioned measurements. We show that previous models, with the exception of a very recent proposal, do not reproduce the required response at high frequency. We explain the physical origin of this recent model and show that it recovers all required features of a linear viscoelastic flow. This constitutive equation thus provides a rigorous foundation for the analysis of vibrating nanostructures in simple liquids. The utility of this model is demonstrated by solving the fluid-structure interaction of two common problems: (1) a sphere executing radial oscillations in liquid, which depends strongly on the liquid compressibility and (2) the extensional mode vibration of bipyramidal nanoparticles in liquid, where the effects of liquid compressibility are negligible. This highlights the importance of shear and compressional relaxation processes, as a function of flow geometry, and the impact of the shear and bulk viscosities on nanometer scale flows.

  11. Backscatter Reduction Using Combined Spatial, Temporal, and Polarization Beam Smoothing in a Long-Scale-length Laser Plasma

    SciTech Connect

    Moody, J. D.; MacGowan, B. J.; Rothenberg, J. E.; Berger, R. L.; Divol, L.; Glenzer, S. H.; Kirkwood, R. K.; Williams, E. A.; Young, P. E.

    2001-03-26

    Spatial, temporal, and polarization smoothing schemes are combined for the first time to reduce to a few percent the total stimulated backscatter of a NIF-like probe laser beam (2x10{sup 15} W/cm{sup 2}, 351 nm, f/8) in a long-scale-length laser plasma. Combining temporal and polarization smoothing reduces simulated Brillouin scattering and simulated Raman scattering (SRS) up to an order of magnitude although neither smoothing scheme by itself is uniformly effective. The results agree with trends observed in simulations performed with the laser-plasma interaction code F3D simulations [R.L. Berger et al., Phys. Plasma 6, 1043 (1999)].

  12. Scalar wave propagation in random amplifying media: Influence of localization effects on length and time scales and threshold behavior

    SciTech Connect

    Frank, Regine; Lubatsch, Andreas

    2011-07-15

    We present a detailed discussion of scalar wave propagation and light intensity transport in three-dimensional random dielectric media with optical gain. The intrinsic length and time scales of such amplifying systems are studied and comprehensively discussed as well as the threshold characteristics of single- and two-particle propagators. Our semianalytical theory is based on a self-consistent Cooperon resummation, representing the repeated self-interference, and incorporates as well optical gain and absorption, modeled in a semianalytical way by a finite imaginary part of the dielectric function. Energy conservation in terms of a generalized Ward identity is taken into account.

  13. Seeing the Forest in Lieu of the Trees: Continuum Simulations of Cell Membranes at Large Length Scales

    PubMed Central

    Sapp, Kayla; Shlomovitz, Roie; Maibaum, Lutz

    2015-01-01

    Biological membranes exhibit long-range spatial structure in both chemical composition and geometric shape, which gives rise to remarkable physical phenomena and important biological functions. Continuum models that describe these effects play an important role in our understanding of membrane biophysics at large length scales. We review the mathematical framework used to describe both composition and shape degrees of freedom, and present best practices to implement such models in a computer simulation. We discuss in detail two applications of continuum models of cell membranes: the formation of microemulsion and modulated phases, and the effect of membrane-mediated interactions on the assembly of membrane proteins. PMID:26366141

  14. Chemical additive to maximize antimicrobial effect of chlorine during pilot scale immersion chilling of broiler carcasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A prior laboratory scale study demonstrated the potential for T-128, a proprietary blend including propylene glycol and phosphoric acid, to enhance the antimicrobial efficacy of chlorine during immersion chilling of broiler parts. The objective of the current study was to test the addition of T-128...

  15. Problems in biology with many scales of length: Cell-cell adhesion and cell jamming in collective cellular migration.

    PubMed

    Pegoraro, Adrian F; Fredberg, Jeffrey J; Park, Jin-Ah

    2016-04-10

    As do all things in biology, cell mechanosensation, adhesion and migration begin at the scale of the molecule. Collections of molecules assemble to comprise microscale objects such as adhesions, organelles and cells. And collections of cells in turn assemble to comprise macroscale tissues. From the points of view of mechanism and causality, events at the molecular scale are seen most often as being the most upstream and, therefore, the most fundamental and the most important. In certain collective systems, by contrast, events at many scales of length conspire to make contributions of equal importance, and even interact directly and strongly across disparate scales. Here we highlight recent examples in cellular mechanosensing and collective cellular migration where physics at some scale bigger than the cell but smaller than the tissue - the mesoscale - becomes the missing link that is required to tie together findings that might otherwise seem counterintuitive or even unpredictable. These examples, taken together, establish that the phenotypes and the underlying physics of collective cellular migration are far richer than previously anticipated. PMID:26546401

  16. Patchiness of ion-exchanged mica revealed by DNA binding dynamics at short length scales.

    PubMed

    Billingsley, D J; Lee, A J; Johansson, N A B; Walton, A; Stanger, L; Crampton, N; Bonass, W A; Thomson, N H

    2014-01-17

    The binding of double-stranded (ds) DNA to mica can be controlled through ion-exchanging the mica with divalent cations. Measurements of the end-to-end distance of linear DNA molecules discriminate whether the binding mechanism occurs through 2D surface equilibration or kinetic trapping. A range of linear dsDNA fragments have been used to investigate length dependences of binding. Mica, ion-exchanged with Ni(II) usually gives rise to kinetically trapped DNA molecules, however, short linear fragments (<800 bp) are seen to deviate from the expected behaviour. This indicates that ion-exchanged mica is heterogeneous, and contains patches or domains, separating different ionic species. These results correlate with imaging of dsDNA under aqueous buffer on Ni(II)-mica and indicate that binding domains are of the order of 100 nm in diameter. Shorter DNA fragments behave intermediate to the two extreme cases of 2D equilibration and kinetic trapping. Increasing the incubation time of Ni(II) on mica, from minutes to hours, brings the conformations of the shorter DNA fragments closer to the theoretical value for kinetic trapping, indicating that long timescale kinetics play a role in ion-exchange. X-ray photoelectron spectroscopy (XPS) was used to confirm that the relative abundance of Ni(II) ions on the mica surface increases with time. These findings can be used to enhance spatial control of binding of DNA to inorganic surfaces with a view to patterning high densities arrays.

  17. Application of nonlocal models to nano beams. Part II: Thickness length scale effect.

    PubMed

    Kim, Jun-Sik

    2014-10-01

    Applicability of nonlocal models to nano-beams is discussed in terms of the Eringen's nonlocal Euler-Bernoulli (EB) beam model. In literature, most work has taken the axial coordinate derivative in the Laplacian operator presented in nonlocal elasticity. This causes that the non-locality always makes the beam soften as compared to the local counterpart. In this paper, the thickness scale effect is solely considered to investigate if the nonlocal model can simulate stiffening effect. Taking the thickness derivative in the Laplacian operator leads to the presence of a surface stress state. The governing equation derived is compared to that of the EB model with the surface stress. The results obtained reveal that the nonlocality tends to decrease the bending moment stiffness whereas to increase the bending rigidity in the governing equation. This tendency also depends on the surface conditions. PMID:25942832

  18. Search for Screened Interactions Associated with Dark Energy below the 100 μ m Length Scale

    NASA Astrophysics Data System (ADS)

    Rider, Alexander D.; Moore, David C.; Blakemore, Charles P.; Louis, Maxime; Lu, Marie; Gratta, Giorgio

    2016-09-01

    We present the results of a search for unknown interactions that couple to mass between an optically levitated microsphere and a gold-coated silicon cantilever. The scale and geometry of the apparatus enable a search for new forces that appear at distances below 100 μ m and which would have evaded previous searches due to screening mechanisms. The data are consistent with electrostatic backgrounds and place upper limits on the strength of new interactions at <0.1 fN in the geometry tested. For the specific example of a chameleon interaction with an inverse power law potential, these results exclude matter couplings β >5.6 ×1 04 in the region of parameter space where the self-coupling Λ ≳5 meV and the microspheres are not fully screened.

  19. Kinesin-5 Contributes to Spindle-length Scaling in the Evolution of Cancer toward Metastasis

    PubMed Central

    Yang, Ching-Feng; Tsai, Wan-Yu; Chen, Wei-An; Liang, Kai-Wen; Pan, Cheng-Ju; Lai, Pei-Lun; Yang, Pan-Chyr; Huang, Hsiao-Chun

    2016-01-01

    During natural evolution, the spindles often scale with cell sizes to orchestrate accurate chromosome segregation. Whether in cancer evolution, when the constraints on genome integrity are relaxed, cancer cells may evolve the spindle to confer other advantages has not been investigated. Using invasion as a selective pressure in vitro, we found that a highly metastatic cancer clone displays a lengthened metaphase spindle, with faster spindle elongation that correlates with transiently elevated speed of cell migration. We found that kinesin-5 is upregulated in this malignant clone, and weak inhibition of kinesin-5 activity could revert the spindle to a smaller aspect ratio, decrease the speed of spindle pole separation, and suppress post-mitotic cell migration. A correlation was found between high aspect ratio and strong metastatic potential in cancers that evolved and were selected in vivo, implicating that the spindle aspect ratio could serve as a promising cellular biomarker for metastatic cancer clones. PMID:27767194

  20. Applicability of Macroscopic Wear and Friction Laws on the Atomic Length Scale

    NASA Astrophysics Data System (ADS)

    Eder, S. J.; Feldbauer, G.; Bianchi, D.; Cihak-Bayr, U.; Betz, G.; Vernes, A.

    2015-07-01

    Using molecular dynamics, we simulate the abrasion process of an atomically rough Fe surface with multiple hard abrasive particles. By quantifying the nanoscopic wear depth in a time-resolved fashion, we show that Barwell's macroscopic wear law can be applied at the atomic scale. We find that in this multiasperity contact system, the Bowden-Tabor term, which describes the friction force as a function of the real nanoscopic contact area, can predict the kinetic friction even when wear is involved. From this the Derjaguin-Amontons-Coulomb friction law can be recovered, since we observe a linear dependence of the contact area on the applied load in accordance with Greenwood-Williamson contact mechanics.

  1. Characterization of tissue structure at varying length scales using temporal diffusion spectroscopy.

    PubMed

    Gore, John C; Xu, Junzhong; Colvin, Daniel C; Yankeelov, Thomas E; Parsons, Edward C; Does, Mark D

    2010-08-01

    The concepts, theoretical behavior and experimental applications of temporal diffusion spectroscopy are reviewed and illustrated. Temporal diffusion spectra are obtained using oscillating-gradient waveforms in diffusion-weighted measurements, and represent the manner in which various spectral components of molecular velocity correlations vary in different geometrical structures that restrict or hinder free movements. Measurements made at different gradient frequencies reveal information on the scale of restrictions or hindrances to free diffusion, and the shape of a spectrum reveals the relative contributions of spatial restrictions at different distance scales. Such spectra differ from other so-called diffusion spectra which depict spatial frequencies and are defined at a fixed diffusion time. Experimentally, oscillating gradients at moderate frequency are more feasible for exploring restrictions at very short distances which, in tissues, correspond to structures smaller than cells. We describe the underlying concepts of temporal diffusion spectra and provide analytical expressions for the behavior of the diffusion coefficient as a function of gradient frequency in simple geometries with different dimensions. Diffusion in more complex model media that mimic tissues has been simulated using numerical methods. Experimental measurements of diffusion spectra have been obtained in suspensions of particles and cells, as well as in vivo in intact animals. An observation of particular interest is the increased contrast and heterogeneity observed in tumors using oscillating gradients at moderate frequency compared with conventional pulse gradient methods, and the potential for detecting changes in tumors early in their response to treatment. Computer simulations suggest that diffusion spectral measurements may be sensitive to intracellular structures, such as nuclear size, and that changes in tissue diffusion properties may be measured before there are changes in cell

  2. Characterization of Tissue Structure at Varying Length Scales Using Temporal Diffusion Spectroscopy

    PubMed Central

    Gore, John C.; Xu, Junzhong; Colvin, Daniel C.; Yankeelov, Thomas E.; Parsons, Edward C.; Does, Mark D.

    2011-01-01

    The concepts, theoretical behavior and experimental applications of temporal diffusion spectroscopy are reviewed and illustrated. Temporal diffusion spectra are obtained by using oscillating gradient waveforms in diffusion-weighted measurements, and represent the manner in which various spectral components of molecular velocity correlations vary in different geometrical structures that restrict or hinder free movements. Measurements made at different gradient frequencies reveal information on the scale of restrictions or hindrances to free diffusion, and the shape of a spectrum reveals the relative contributions of spatial restrictions at different distance scales. Such spectra differ from other so-called diffusion spectra which depict spatial frequencies and are defined at a fixed diffusion time. Experimentally, oscillating gradients at moderate frequency are more feasible for exploring restrictions at very short distances, which in tissues correspond to structures smaller than cells. We describe the underlying concepts of temporal diffusion spectra and provide analytical expressions for the behavior of the diffusion coefficient as a function of gradient frequency in simple geometries with different dimensions. Diffusion in more complex model media that mimic tissues has been simulated using numerical methods. Experimental measurements of diffusion spectra have been obtained in suspensions of particles and cells, as well as in vivo in intact animals. An observation of particular interest is the increased contrast and heterogeneity observed in tumors using oscillating gradients at moderate frequency compared to conventional pulse gradient methods, and the potential for detecting changes in tumors early in their response to treatment. Computer simulations suggest that diffusion spectral measurements may be sensitive to intracellular structures such as nuclear size, and that changes in tissue diffusion properties may be measured before there are changes in cell

  3. Effect of Addition of Mill Scale on Sintering of Iron Ores

    NASA Astrophysics Data System (ADS)

    Wang, Zhe; Pinson, David; Chew, Sheng; Monaghan, Brian J.; Pownceby, Mark I.; Webster, Nathan A. S.; Rogers, Harold; Zhang, Guangqing

    2016-10-01

    Iron-rich (65 to 70 pct total Fe) mill scale generated during processing by steel mills can be recycled by using it as a ferrous raw material in the sintering process. The effect of mill scale addition on the phase formation of sintered specimens from an industrial sinter blend containing 0 to 15 wt pct mill scale was examined, and the mineral phases formed during sintering under various conditions ( T = 1523 K to 1598 K [1250 °C to 1325 °C] and gas compositions of pO2 = 0.5, 5 and 21 kPa) were quantitatively measured. For samples sintered in air (pO2 = 21 kPa), there was negligible effect of mill scale addition on the phases formed. The oxidation of the mill scale was complete, and phases such as Silico-Ferrite of Calcium and Aluminum (SFCA), SFCA-I, and hematite dominated. Under lower oxygen partial pressures (pO2 = 0.5 or 5 kPa), and throughout the temperature range examined, the mill scale was converted to magnetite, with the extent of reaction controlled by the hematite-magnetite conversion kinetics. When sintered in the gas mixture with pO2 = 5 kPa, an increase in the mill scale content from 0 to 15 wt pct resulted in a decrease of hematite and total SFCA phases and a corresponding increase in the amount of magnetite which formed. The oxidation of wustite in mill scale to magnetite decreased the local partial pressure of O2 and increased sintering temperature, which promoted the decomposition of hematite.

  4. Effect of Addition of Mill Scale on Sintering of Iron Ores

    NASA Astrophysics Data System (ADS)

    Wang, Zhe; Pinson, David; Chew, Sheng; Monaghan, Brian J.; Pownceby, Mark I.; Webster, Nathan A. S.; Rogers, Harold; Zhang, Guangqing

    2016-06-01

    Iron-rich (65 to 70 pct total Fe) mill scale generated during processing by steel mills can be recycled by using it as a ferrous raw material in the sintering process. The effect of mill scale addition on the phase formation of sintered specimens from an industrial sinter blend containing 0 to 15 wt pct mill scale was examined, and the mineral phases formed during sintering under various conditions (T = 1523 K to 1598 K [1250 °C to 1325 °C] and gas compositions of pO2 = 0.5, 5 and 21 kPa) were quantitatively measured. For samples sintered in air (pO2 = 21 kPa), there was negligible effect of mill scale addition on the phases formed. The oxidation of the mill scale was complete, and phases such as Silico-Ferrite of Calcium and Aluminum (SFCA), SFCA-I, and hematite dominated. Under lower oxygen partial pressures (pO2 = 0.5 or 5 kPa), and throughout the temperature range examined, the mill scale was converted to magnetite, with the extent of reaction controlled by the hematite-magnetite conversion kinetics. When sintered in the gas mixture with pO2 = 5 kPa, an increase in the mill scale content from 0 to 15 wt pct resulted in a decrease of hematite and total SFCA phases and a corresponding increase in the amount of magnetite which formed. The oxidation of wustite in mill scale to magnetite decreased the local partial pressure of O2 and increased sintering temperature, which promoted the decomposition of hematite.

  5. The jamming transition and beyond: Density dependence of the relevant length and time scales in a horizontally vibrated granular monolayer

    NASA Astrophysics Data System (ADS)

    Lechenault, Frederic; Dauchot, Olivier

    2007-03-01

    A dense amorphous monolayer of hard disks is horizontally driven by a glass plate oscillating underneath while confined in a fixed rectangular cell. As the packing fraction is decreased, the system exhibits a transition between a totally jammed state in which the pressure is driven by the contact network and a ``supercooled'' regime in which the kinetic contribution becomes dominant. We characterize the diffusion properties of such packing across the transition. Furthermore, we compute the self- intermediate scattering function Fs(,k) and the so- called dynamical susceptibility χ4(,k). First we show that the former scales with the diffusive length. Then we find that the cooperative scale associated to the latter increases as the packing is increased toward the transition and then drops abruptly as a certain critical density φc is crossed. Finally we uncover a relationship between Fs and χ4 and discuss its link with a dynamical fluctuation dissipation relation.

  6. Evaluating pedestal gradients and scale lengths without functional fits in order to test for non-diffusive transport processes

    NASA Astrophysics Data System (ADS)

    Eldon, D. P.; Tynan, G. R.; Groebner, R. J.; Osborne, T. H.; Bray, B. D.; Boivin, R. L.; Nazikian, R.

    2012-10-01

    The advent of the recent spatial resolution upgrade to the edge Thomson scattering diagnostic at DIII-D allows re-examination of methods for measuring electron density and temperature scale lengths. The modified hyperbolic tangent fit is widely used, however, this function is clearly inappropriate in some situations such as when density profiles are distorted by applied resonant magnetic perturbations (RMPs). In these cases, a flattening of the density profile is observed at or near the separatrix while the RMP is applied. However, no similar structure is observed in the temperature profile so far. Furthermore, the tanh fit is based on a diffusive model and recently observed differences between the tanh fit and measured profiles using newly available high spatial resolution data are revealing more subtle transport processes at the mm scale.

  7. Probing grain boundary sink strength at the nanoscale: Energetics and length scales of vacancy and interstitial absorption by grain boundaries in α-Fe

    NASA Astrophysics Data System (ADS)

    Tschopp, M. A.; Solanki, K. N.; Gao, F.; Sun, X.; Khaleel, M. A.; Horstemeyer, M. F.

    2012-02-01

    The energetics and length scales associated with the interaction between point defects (vacancies and self-interstitial atoms) and grain boundaries in bcc Fe was explored. Molecular statics simulations were used to generate a grain boundary structure database that contained ≈170 grain boundaries with varying tilt and twist character. Then, vacancy and self-interstitial atom formation energies were calculated at all potential grain boundary sites within 15 Å of the boundary. The present results provide detailed information about the interaction energies of vacancies and self-interstitial atoms with symmetric tilt grain boundaries in iron and the length scales involved with absorption of these point defects by grain boundaries. Both low- and high-angle grain boundaries were effective sinks for point defects, with a few low-Σ grain boundaries (e.g., the Σ3{112} twin boundary) that have properties different from the rest. The formation energies depend on both the local atomic structure and the distance from the boundary center. Additionally, the effect of grain boundary energy, disorientation angle, and Σ designation on the boundary sink strength was explored; the strongest correlation occurred between the grain boundary energy and the mean point defect formation energies. Based on point defect binding energies, interstitials have ≈80% more grain boundary sites per area and ≈300% greater site strength than vacancies. Last, the absorption length scale of point defects by grain boundaries is over a full lattice unit larger for interstitials than for vacancies (mean of 6-7 Å versus 10-11 Å for vacancies and interstitials, respectively).

  8. Singular value decomposition of genome-scale mRNA lengths distribution reveals asymmetry in RNA gel electrophoresis band broadening.

    PubMed

    Alter, Orly; Golub, Gene H

    2006-08-01

    We describe the singular value decomposition (SVD) of yeast genome-scale mRNA lengths distribution data measured by DNA microarrays. SVD uncovers in the mRNA abundance levels data matrix of genes x arrays, i.e., electrophoretic gel migration lengths or mRNA lengths, mathematically unique decorrelated and decoupled "eigengenes." The eigengenes are the eigenvectors of the arrays x arrays correlation matrix, with the corresponding series of eigenvalues proportional to the series of the "fractions of eigen abundance." Each fraction of eigen abundance indicates the significance of the corresponding eigengene relative to all others. We show that the eigengenes fit "asymmetric Hermite functions," a generalization of the eigenfunctions of the quantum harmonic oscillator and the integral transform which kernel is a generalized coherent state. The fractions of eigen abundance fit a geometric series as do the eigenvalues of the integral transform which kernel is a generalized coherent state. The "asymmetric generalized coherent state" models the measured data, where the profiles of mRNA abundance levels of most genes as well as the distribution of the peaks of these profiles fit asymmetric Gaussians. We hypothesize that the asymmetry in the distribution of the peaks of the profiles is due to two competing evolutionary forces. We show that the asymmetry in the profiles of the genes might be due to a previously unknown asymmetry in the gel electrophoresis thermal broadening of a moving, rather than a stationary, band of RNA molecules.

  9. Long-length, long-lived flow-shear stabilized Z-pinches: Background and Experimental plans for scaling studies

    NASA Astrophysics Data System (ADS)

    Nelson, B. A.; Shumlak, U.; Golingo, R. P.; Claveau, E. L.; McLean, H. S.; Schmidt, A. E.

    2015-11-01

    The ZaP experiment produces long-lived sheared-flow-stabilized Z-pinch plasmas up to 126 cm in length for several flow-through times, and up to thousands of Alfvén times. Experimental measurements of the magnetic structure along the full length of the plasma column show an axially uniform Z-pinch plasma during the observed quiescent period. Interferometry, fast-framing images, and Rogowskii coils corroborate the existence of a pinched plasma during this quiescent period of time. Detailed two-dimensional non-linear magnetohydrodynamic (MHD) calculations have been performed showing the formation and assembly of long-length, long-lived Z-pinches. Experimentally-observed plasma lifetimes and velocity-shear profiles are shown to be consistent with calculations of viscous-damping timescales based on the measured plasma parameters. A newly-funded ARPA-E ALPHA project, the Fusion Z-pinch Experiment ``FuZE'' is being constructed at the University of Washington, in collaboration with the Lawrence Livermore National Laboratory. FuZE will study scaling and stability of the successful ZaP experiment to higher pinch currents. The FuZE experimental design, goals, and plans, based on ZaP experimental results, will be presented.

  10. Plasma-field Coupling at Small Length Scales in Solar Wind Near 1 AU

    NASA Astrophysics Data System (ADS)

    Livadiotis, G.; Desai, M. I.

    2016-10-01

    In collisionless plasmas such as the solar wind, the coupling between plasma constituents and the embedded magnetic field occurs on various temporal and spatial scales, and is primarily responsible for the transfer of energy between waves and particles. Recently, it was shown that the transfer of energy between solar wind plasma particles and waves is governed by a new and unique relationship: the ratio between the magnetosonic energy and the plasma frequency is constant, E ms/ω pl ˜ ℏ*. This paper examines the variability and substantial departure of this ratio from ℏ* observed at ˜1 au, which is caused by a dispersion of fast magnetosonic (FMS) waves. In contrast to the efficiently transferred energy in the fast solar wind, the lower efficiency of the slow solar wind can be caused by this dispersion, whose relation and characteristics are derived and studied. In summary, we show that (i) the ratio E ms/ω pl transitions continuously from the slow to the fast solar wind, tending toward the constant ℏ* (ii) the transition is more efficient for larger thermal, Alfvén, or FMS speeds; (iii) the fast solar wind is almost dispersionless, characterized by quasi-constant values of the FMS speed, while the slow wind is subject to dispersion that is less effective for larger wind or magnetosonic speeds; and (iv) the constant ℏ* is estimated with the best known precision, ℏ* ≈ (1.160 ± 0.083) × 10-22 Js.

  11. Mechanical measurements of heterogeneity and length scale effects in PEG-based hydrogels

    PubMed Central

    Bush, Brian G.; Shapiro, Jenna M.; DelRio, Frank W.; Cook, Robert F.; Oyen, Michelle L.

    2015-01-01

    Colloidal-probe spherical indentation load-relaxation experiments with a probe radius of 3 μm are conducted on poly(ethylene glycol) (PEG) hydrogel materials to quantify their steady-state mechanical properties and time-dependent transport properties via a single experiment. PEG-based hydrogels are shown to be heterogeneous in both morphology and mechanical stiffness at this scale; a linear-harmonic interpolation of hyperelastic Mooney-Rivlin and Boussinesq flat-punch indentation models was used to describe the steady-state response of the hydrogels and determine upper and lower bounds for indentation moduli. Analysis of the transient load-relaxation response during displacement-controlled hold periods provides a means of extracting two time constants τ1 and τ2, where τ1 and τ2 are assigned to the viscoelastic and poroelastic properties, respectively. Large τ2 values at small indentation depths provide evidence of a non-equilibrium state characterized by a phenomenon that restricts poroelastic fluid flow through the material; for larger indentations, the variability in τ2 values decreases and pore sizes estimated from τ2 via indentation approach those measured via macroscopic swelling experiments. The contact probe methodology developed here provides a means of assessing hydrogel heterogeneity, including time-dependent mechanical and transport properties, and has potential implications in hydrogel biomedical and engineering applications. PMID:26255839

  12. Biological length scale topography enhances cell-substratum adhesion of human corneal epithelial cells

    PubMed Central

    Karuri, Nancy W.; Liliensiek, Sara; Teixeira, Ana I.; Abrams, George; Campbell, Sean; Nealey, Paul F.; Murphy, Christopher J.

    2006-01-01

    Summary The basement membrane possesses a rich 3-dimensional nanoscale topography that provides a physical stimulus, which may modulate cell-substratum adhesion. We have investigated the strength of cell-substratum adhesion on nanoscale topographic features of a similar scale to that of the native basement membrane. SV40 human corneal epithelial cells were challenged by well-defined fluid shear, and cell detachment was monitored. We created silicon substrata with uniform grooves and ridges having pitch dimensions of 400-4000 nm using X-ray lithography. F-actin labeling of cells that had been incubated for 24 hours revealed that the percentage of aligned and elongated cells on the patterned surfaces was the same regardless of pitch dimension. In contrast, at the highest fluid shear, a biphasic trend in cell adhesion was observed with cells being most adherent to the smaller features. The 400 nm pitch had the highest percentage of adherent cells at the end of the adhesion assay. The effect of substratum topography was lost for the largest features evaluated, the 4000 nm pitch. Qualitative and quantitative analyses of the cells during and after flow indicated that the aligned and elongated cells on the 400 nm pitch were more tightly adhered compared to aligned cells on the larger patterns. Selected experiments with primary cultured human corneal epithelial cells produced similar results to the SV40 human corneal epithelial cells. These findings have relevance to interpretation of cell-biomaterial interactions in tissue engineering and prosthetic design. PMID:15226393

  13. Biological length scale topography enhances cell-substratum adhesion of human corneal epithelial cells.

    PubMed

    Karuri, Nancy W; Liliensiek, Sara; Teixeira, Ana I; Abrams, George; Campbell, Sean; Nealey, Paul F; Murphy, Christopher J

    2004-07-01

    The basement membrane possesses a rich 3-dimensional nanoscale topography that provides a physical stimulus, which may modulate cell-substratum adhesion. We have investigated the strength of cell-substratum adhesion on nanoscale topographic features of a similar scale to that of the native basement membrane. SV40 human corneal epithelial cells were challenged by well-defined fluid shear, and cell detachment was monitored. We created silicon substrata with uniform grooves and ridges having pitch dimensions of 400-4000 nm using X-ray lithography. F-actin labeling of cells that had been incubated for 24 hours revealed that the percentage of aligned and elongated cells on the patterned surfaces was the same regardless of pitch dimension. In contrast, at the highest fluid shear, a biphasic trend in cell adhesion was observed with cells being most adherent to the smaller features. The 400 nm pitch had the highest percentage of adherent cells at the end of the adhesion assay. The effect of substratum topography was lost for the largest features evaluated, the 4000 nm pitch. Qualitative and quantitative analyses of the cells during and after flow indicated that the aligned and elongated cells on the 400 nm pitch were more tightly adhered compared to aligned cells on the larger patterns. Selected experiments with primary cultured human corneal epithelial cells produced similar results to the SV40 human corneal epithelial cells. These findings have relevance to interpretation of cell-biomaterial interactions in tissue engineering and prosthetic design.

  14. Dominant length scale of the ``pure'' turbulent fluctuations in the outer region of wall turbulence

    NASA Astrophysics Data System (ADS)

    Kwon, Yong Seok; Monty, Jason; Hutchins, Nick

    2014-11-01

    A new method of decomposing the total velocity in boundary layers, which removes the influence of instantaneous boundary layer thickness variations to the fluctuating velocity component, is proposed. The recent proposition of the quiescent core of turbulent channel flow by Kwon et al. (J. Fluid Mech., 751, 228 (2014)) permits us to apply the same decomposition to channel flows where the quiescent core is analogous to the free-stream. Using this decomposition, it is observed that the majority of the large-scale streamwise velocity fluctuation within the intermittent region is attributed to the oscillation of the turbulent/non-turbulent interface or the quiescent core. It suggests that the quiescent core and the free-stream play a similar role and the flow nearer to the wall in both flows is more similar than previously thought while the different characteristics of the free-stream and the quiescent core account for the differences in the outer region of two flows. These findings re-affirm the analogy between the quiescent core and the free-stream, which could potentially lead to the unified conceptual model between internal and external flows. This work is financially supported by the Australian Research Council and the Defence Science and Technology Organisation.

  15. Strategies for Directing the Structure and Function of 3D Collagen Biomaterials across Length Scales

    PubMed Central

    Walters, Brandan D.; Stegemann, Jan P.

    2013-01-01

    Collagen type I is a widely used natural biomaterial that has found utility in a variety of biological and medical applications. Its well characterized structure and role as an extracellular matrix protein make it a highly relevant material for controlling cell function and mimicking tissue properties. Collagen type I is abundant in a number of tissues, and can be isolated as a purified protein. This review focuses on hydrogel biomaterials made by reconstituting collagen type I from a solubilized form, with an emphasis on in vitro studies in which collagen structure can be controlled. The hierarchical structure of collagen from the nanoscale to the macroscale is described, with an emphasis on how structure is related to function across scales. Methods of reconstituting collagen into hydrogel materials are presented, including molding of macroscopic constructs, creation of microscale modules, and electrospinning of nanoscale fibers. The modification of collagen biomaterials to achieve desired structures and functions is also addressed, with particular emphasis on mechanical control of collagen structure, creation of collagen composite materials, and crosslinking of collagenous matrices. Biomaterials scientists have made remarkable progress in rationally designing collagen-based biomaterials and in applying them to both the study of biology and for therapeutic benefit. This broad review illustrates recent examples of techniques used to control collagen structure, and to thereby direct its biological and mechanical functions. PMID:24012608

  16. Strategies for directing the structure and function of three-dimensional collagen biomaterials across length scales.

    PubMed

    Walters, B D; Stegemann, J P

    2014-04-01

    Collagen type I is a widely used natural biomaterial that has found utility in a variety of biological and medical applications. Its well-characterized structure and role as an extracellular matrix protein make it a highly relevant material for controlling cell function and mimicking tissue properties. Collagen type I is abundant in a number of tissues, and can be isolated as a purified protein. This review focuses on hydrogel biomaterials made by reconstituting collagen type I from a solubilized form, with an emphasis on in vitro studies in which collagen structure can be controlled. The hierarchical structure of collagen from the nanoscale to the macroscale is described, with an emphasis on how structure is related to function across scales. Methods of reconstituting collagen into hydrogel materials are presented, including molding of macroscopic constructs, creation of microscale modules and electrospinning of nanoscale fibers. The modification of collagen biomaterials to achieve the desired structures and functions is also addressed, with particular emphasis on mechanical control of collagen structure, creation of collagen composite materials and crosslinking of collagenous matrices. Biomaterials scientists have made remarkable progress in rationally designing collagen-based biomaterials and in applying them both to the study of biology and for therapeutic benefit. This broad review illustrates recent examples of techniques used to control collagen structure and thereby to direct its biological and mechanical functions.

  17. Molecular density functional theory of water describing hydrophobicity at short and long length scales.

    PubMed

    Jeanmairet, Guillaume; Levesque, Maximilien; Borgis, Daniel

    2013-10-21

    We present an extension of our recently introduced molecular density functional theory of water [G. Jeanmairet et al., J. Phys. Chem. Lett. 4, 619 (2013)] to the solvation of hydrophobic solutes of various sizes, going from angstroms to nanometers. The theory is based on the quadratic expansion of the excess free energy in terms of two classical density fields: the particle density and the multipolar polarization density. Its implementation requires as input a molecular model of water and three measurable bulk properties, namely, the structure factor and the k-dependent longitudinal and transverse dielectric susceptibilities. The fine three-dimensional water structure around small hydrophobic molecules is found to be well reproduced. In contrast, the computed solvation free-energies appear overestimated and do not exhibit the correct qualitative behavior when the hydrophobic solute is grown in size. These shortcomings are corrected, in the spirit of the Lum-Chandler-Weeks theory, by complementing the functional with a truncated hard-sphere functional acting beyond quadratic order in density, and making the resulting functional compatible with the Van-der-Waals theory of liquid-vapor coexistence at long range. Compared to available molecular simulations, the approach yields reasonable solvation structure and free energy of hard or soft spheres of increasing size, with a correct qualitative transition from a volume-driven to a surface-driven regime at the nanometer scale.

  18. High-resolution MALDI imaging mass spectrometry allows localization of peptide distributions at cellular length scales in pituitary tissue sections

    NASA Astrophysics Data System (ADS)

    Altelaar, A. F. Maarten; Taban, Ioana M.; McDonnell, Liam A.; Verhaert, Peter D. E. M.; de Lange, Robert P. J.; Adan, Roger A. H.; Mooi, Wolter J.; Heeren, Ron M. A.; Piersma, Sander R.

    2007-02-01

    Matrix assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) has been used to determine peptide distributions directly from rat, mouse and human pituitary tissue sections. Since these organs are small (102-103 [mu]m) the spatial resolution of IMS is a key issue in molecular imaging of pituitary tissue sections. Here we show that high-resolution IMS allows localization of neuropeptide distributions within different cell clusters of a single organ of a pituitary tissue section. The sample preparation protocol does not result in analyte redistribution and is therefore applicable to IMS experiments at cellular length scales. The stigmatic imaging mass spectrometer used in this study produces selected-ion-count images with pixel sizes of 500 nm and a resolving power of 4 [mu]m, yielding superior spatial detail compared to images obtained in microprobe imaging experiments. Furthermore, we show that with imaging mass spectrometry a distinction can be made between different mammalian tissue sections based on differences in the amino acid sequence of neuropeptides with the same function. This example demonstrates the power of IMS for label-free molecular imaging at relevant biological length scales.

  19. Imaging Acoustic Phonon Dynamics on the Nanometer-Femtosecond Spatiotemporal Length-Scale with Ultrafast Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Plemmons, Dayne; Flannigan, David

    Coherent collective lattice oscillations known as phonons dictate a broad range of physical observables in condensed matter and act as primary energy carriers across a wide range of material systems. Despite this omnipresence, analysis of phonon dynamics on their ultrashort native spatiotemporal length scale - that is, the combined nanometer (nm), spatial and femtosecond (fs), temporal length-scales - has largely remained experimentally inaccessible. Here, we employ ultrafast electron microscopy (UEM) to directly image discrete acoustic phonons in real-space with combined nm-fs resolution. By directly probing electron scattering in the image plane (as opposed to the diffraction plane), we retain phase information critical for following the evolution, propagation, scattering, and decay of phonons in relation to morphological features of the specimen (i.e. interfaces, grain boundaries, voids, ripples, etc.). We extract a variety of morphologically-specific quantitative information from the UEM videos including phonon frequencies, phase velocities, and decays times. We expect these direct manifestations of local elastic properties in the vicinity of material defects and interfaces will aide in the understanding and application of phonon-mediated phenomena in nanostructures. Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA.

  20. Beam displacement as a function of temperature and turbulence length scale at two different laser radiation wavelengths.

    PubMed

    Isterling, William M; Dally, Bassam B; Alwahabi, Zeyad T; Dubovinsky, Miro; Wright, Daniel

    2012-01-01

    Narrow laser beams directed from aircraft may at times pass through the exhaust plume of the engines and potentially degrade some of the laser beam characteristics. This paper reports on controlled studies of laser beam deviation arising from propagation through turbulent hot gases, in a well-characterized laboratory burner, with conditions of relevance to aircraft engine exhaust plumes. The impact of the temperature, laser wavelength, and turbulence length scale on the beam deviation has been investigated. It was found that the laser beam displacement increases with the turbulent integral length scale. The effect of temperature on the laser beam angular deviation, σ, using two different laser wavelengths, namely 4.67 μm and 632.8 nm, was recorded. It was found that the beam deviation for both wavelengths may be semiempirically modeled using a single function of the form, σ=a(b+(1/T)(2))(-1), with two parameters only, a and b, where σ is in microradians and T is the temperature in °C.

  1. Optimal length scales emerging from shear load transfer in natural materials: application to carbon-based nanocomposite design.

    PubMed

    Wei, Xiaoding; Naraghi, Mohammad; Espinosa, Horacio D

    2012-03-27

    Numerous theoretical and experimental studies on various species of natural composites, such as nacre in abalone shells, collagen fibrils in tendon, and spider silk fibers, have been pursued to provide insight into the synthesis of novel bioinspired high-performance composites. However, a direct link between the mechanical properties of the constituents and the various geometric features and hierarchies remains to be fully established. In this paper, we explore a common denominator leading to the outstanding balance between strength and toughness in natural composite materials. We present an analytical model to link the mechanical properties of constituents, their geometric arrangement, and the chemistries used in their lateral interactions. Key critical overlap length scales between adjacent reinforcement constituents, which directly control strength and toughness of composite materials, emerge from the analysis. When these length scales are computed for three natural materials-nacre, collagen molecules, and spider silk fibers-very good agreement is found as compared with experimental measurements. The model was then used to interpret load transfer capabilities in synthetic carbon-based materials through parametrization of in situ SEM shear experiments on overlapping multiwall carbon nanotubes. PMID:22316210

  2. Manipulating surface diffusion and elastic interactions to obtain quantum dot multilayer arrangements over different length scales

    SciTech Connect

    Placidi, E. Arciprete, F.; Latini, V.; Latini, S.; Patella, F.; Magri, R.

    2014-09-15

    An innovative multilayer growth of InAs quantum dots on GaAs(100) is demonstrated to lead to self-aggregation of correlated quantum dot chains over mesoscopic distances. The fundamental idea is that at critical growth conditions is possible to drive the dot nucleation only at precise locations corresponding to the local minima of the Indium chemical potential. Differently from the known dot multilayers, where nucleation of new dots on top of the buried ones is driven by the surface strain originating from the dots below, here the spatial correlations and nucleation of additional dots are mostly dictated by a self-engineering of the surface occurring during the growth, close to the critical conditions for dot formation under the fixed oblique direction of the incoming As flux, that drives the In surface diffusion.

  3. Age-related changes in the plasticity and toughness of human cortical bone at multiple length-scales

    SciTech Connect

    Zimmermann, Elizabeth A.; Schaible, Eric; Bale, Hrishikesh; Barth, Holly D.; Tang, Simon Y.; Reichert, Peter; Busse, Bjoern; Alliston, Tamara; Ager III, Joel W.; Ritchie, Robert O.

    2011-08-10

    The structure of human cortical bone evolves over multiple length-scales from its basic constituents of collagen and hydroxyapatite at the nanoscale to osteonal structures at nearmillimeter dimensions, which all provide the basis for its mechanical properties. To resist fracture, bone’s toughness is derived intrinsically through plasticity (e.g., fibrillar sliding) at structural-scales typically below a micron and extrinsically (i.e., during crack growth) through mechanisms (e.g., crack deflection/bridging) generated at larger structural-scales. Biological factors such as aging lead to a markedly increased fracture risk, which is often associated with an age-related loss in bone mass (bone quantity). However, we find that age-related structural changes can significantly degrade the fracture resistance (bone quality) over multiple lengthscales. Using in situ small-/wide-angle x-ray scattering/diffraction to characterize sub-micron structural changes and synchrotron x-ray computed tomography and in situ fracture-toughness measurements in the scanning electron microscope to characterize effects at micron-scales, we show how these age-related structural changes at differing size-scales degrade both the intrinsic and extrinsic toughness of bone. Specifically, we attribute the loss in toughness to increased non-enzymatic collagen cross-linking which suppresses plasticity at nanoscale dimensions and to an increased osteonal density which limits the potency of crack-bridging mechanisms at micron-scales. The link between these processes is that the increased stiffness of the cross-linked collagen requires energy to be absorbed by “plastic” deformation at higher structural levels, which occurs by the process of microcracking.

  4. On determining characteristic length scales in pressure gradient turbulent boundary layers

    NASA Astrophysics Data System (ADS)

    Vinuesa, Ricardo; Örlü, Ramis; Schlatter, Philipp

    2016-04-01

    In the present work we analyze three methods used to determine the edge of pressure gradient turbulent boundary layers: two based on composite profiles, the one by Chauhan et al. (Fluid Dyn. Res. 41:021401, 2009) and the one by Nickels (J. Fluid Mech. 521:217–239, 2004), and the other one based on the condition of vanishing mean velocity gradient. Additionally, a new method is introduced based on the diagnostic plot concept by Alfredsson et al. (Phys. Fluids 23:041702, 2011). The boundary layer developing over the suction side of a NACA4412 wing profile, extracted from a direct numerical simulation at Rec = 400,000, is used as the test case. We find that all the methods produce robust results with mild or moderate pressure gradients, but stronger pressure gradients (with β larger than around 7) lead to inconsistent results in all the techniques except the diagnostic plot. This method also has the advantage of providing an objective way of defining the point where the mean streamwise velocity is 99% of the edge velocity, and shows consistent results in a wide range of pressure gradient conditions, as well as flow histories. Therefore, the technique based on the diagnostic plot is a robust method to determine the boundary layer thickness (equivalent to δ99) and edge velocity in pressure gradient turbulent boundary layers.

  5. On determining characteristic length scales in pressure gradient turbulent boundary layers

    NASA Astrophysics Data System (ADS)

    Vinuesa, Ricardo; Örlü, Ramis; Schlatter, Philipp

    2016-04-01

    In the present work we analyze three methods used to determine the edge of pressure gradient turbulent boundary layers: two based on composite profiles, the one by Chauhan et al. (Fluid Dyn. Res. 41:021401, 2009) and the one by Nickels (J. Fluid Mech. 521:217-239, 2004), and the other one based on the condition of vanishing mean velocity gradient. Additionally, a new method is introduced based on the diagnostic plot concept by Alfredsson et al. (Phys. Fluids 23:041702, 2011). The boundary layer developing over the suction side of a NACA4412 wing profile, extracted from a direct numerical simulation at Rec = 400,000, is used as the test case. We find that all the methods produce robust results with mild or moderate pressure gradients, but stronger pressure gradients (with β larger than around 7) lead to inconsistent results in all the techniques except the diagnostic plot. This method also has the advantage of providing an objective way of defining the point where the mean streamwise velocity is 99% of the edge velocity, and shows consistent results in a wide range of pressure gradient conditions, as well as flow histories. Therefore, the technique based on the diagnostic plot is a robust method to determine the boundary layer thickness (equivalent to δ99) and edge velocity in pressure gradient turbulent boundary layers.

  6. Effects of characteristic length scales on the exciton dynamics in rubrene single crystals

    NASA Astrophysics Data System (ADS)

    Gieseking, Björn; Schmeiler, Teresa; Müller, Benjamin; Deibel, Carsten; Engels, Bernd; Dyakonov, Vladimir; Pflaum, Jens

    2014-11-01

    We present temperature dependent time-resolved photoluminescence (PL) investigations on well-defined morphologies of the prototypical organic semiconductor rubrene. By their respective degree of spatial constraint these morphologies directly influence the temperature dependent excitonic processes and their dynamics. While in bulk single crystals singlet exciton decay is governed by thermally activated fission at a time constant of 20 ps, this mechanism appears to be absent in rubrene microcrystals. Here the dynamics are characterized by a pronounced increase of the average exciton lifetime as confirmed by the dominating PL decay channel with an effective time constant of 100 ps. The enhanced surface-to-volume ratio indicates that the participating states might originate from microcrystal boundaries which could be reached by the substantial amount of migrating excitons prior to the onset of other decay processes. The suppression of singlet fission in these crystalline microstructures is promoted by the significantly lower activation energy of 25 meV for the 100 ps channel compared to the singlet fission barrier of 44 meV and imposes severe consequences for its utilization in, e.g., thin film photovoltaics. For the crystalline samples, an additional relaxation channel with a time constant of around 500 ps becomes relevant at very low temperatures. As this process is the only one observed for amorphous rubrene thin films it points at the local nature of the underlying decay mechanism.

  7. Microfibril Orientation Dominates the Microelastic Properties of Human Bone Tissue at the Lamellar Length Scale

    PubMed Central

    Rupin, Fabienne; Raum, Kay; Peyrin, Françoise; Burghammer, Manfred; Saïed, Amena; Laugier, Pascal

    2013-01-01

    The elastic properties of bone tissue determine the biomechanical behavior of bone at the organ level. It is now widely accepted that the nanoscale structure of bone plays an important role to determine the elastic properties at the tissue level. Hence, in addition to the mineral density, the structure and organization of the mineral nanoparticles and of the collagen microfibrils appear as potential key factors governing the elasticity. Many studies exist on the role of the organization of collagen microfibril and mineral nanocrystals in strongly remodeled bone. However, there is no direct experimental proof to support the theoretical calculations. Here, we provide such evidence through a novel approach combining several high resolution imaging techniques: scanning acoustic microscopy, quantitative scanning small-Angle X-ray scattering imaging and synchrotron radiation computed microtomography. We find that the periodic modulations of elasticity across osteonal bone are essentially determined by the orientation of the mineral nanoparticles and to a lesser extent only by the particle size and density. Based on the strong correlation between the orientation of the mineral nanoparticles and the collagen molecules, we conclude that the microfibril orientation is the main determinant of the observed undulations of microelastic properties in regions of constant mineralization in osteonal lamellar bone. This multimodal approach could be applied to a much broader range of fibrous biological materials for the purpose of biomimetic technologies. PMID:23472132

  8. Additive Partitioning of Coral Reef Fish Diversity across Hierarchical Spatial Scales throughout the Caribbean

    PubMed Central

    Francisco-Ramos, Vanessa; Arias-González, Jesús Ernesto

    2013-01-01

    There is an increasing need to examine regional patterns of diversity in coral-reef systems since their biodiversity is declining globally. In this sense, additive partitioning might be useful since it quantifies the contribution of alpha and beta to total diversity across different scales. We applied this approach using an unbalanced design across four hierarchical scales (80 sites, 22 subregions, six ecoregions, and the Caribbean basin). Reef-fish species were compiled from the Reef Environmental Education Foundation (REEF) database and distributions were confirmed with published data. Permutation tests were used to compare observed values to those expected by chance. The primary objective was to identify patterns of reef-fish diversity across multiple spatial scales under different scenarios, examining factors such as fisheries and demographic connectivity. Total diversity at the Caribbean scale was attributed to β-diversity (nearly 62% of the species), with the highest β-diversity at the site scale. α¯-diversity was higher than expected by chance in all scenarios and at all studied scales. This suggests that fish assemblages are more homogenous than expected, particularly at the ecoregion scale. Within each ecoregion, diversity was mainly attributed to alpha, except for the Southern ecoregion where there was a greater difference in species among sites. β-components were lower than expected in all ecoregions, indicating that fishes within each ecoregion are a subsample of the same species pool. The scenario involving the effects of fisheries showed a shift in dominance for β-diversity from regions to subregions, with no major changes to the diversity patterns. In contrast, demographic connectivity partially explained the diversity pattern. β-components were low within connectivity regions and higher than expected by chance when comparing between them. Our results highlight the importance of ecoregions as a spatial scale to conserve local and regional

  9. Quantification of Treatment Effect Modification on Both an Additive and Multiplicative Scale

    PubMed Central

    Girerd, Nicolas; Rabilloud, Muriel; Pibarot, Philippe; Mathieu, Patrick; Roy, Pascal

    2016-01-01

    Background In both observational and randomized studies, associations with overall survival are by and large assessed on a multiplicative scale using the Cox model. However, clinicians and clinical researchers have an ardent interest in assessing absolute benefit associated with treatments. In older patients, some studies have reported lower relative treatment effect, which might translate into similar or even greater absolute treatment effect given their high baseline hazard for clinical events. Methods The effect of treatment and the effect modification of treatment were respectively assessed using a multiplicative and an additive hazard model in an analysis adjusted for propensity score in the context of coronary surgery. Results The multiplicative model yielded a lower relative hazard reduction with bilateral internal thoracic artery grafting in older patients (Hazard ratio for interaction/year = 1.03, 95%CI: 1.00 to 1.06, p = 0.05) whereas the additive model reported a similar absolute hazard reduction with increasing age (Delta for interaction/year = 0.10, 95%CI: -0.27 to 0.46, p = 0.61). The number needed to treat derived from the propensity score-adjusted multiplicative model was remarkably similar at the end of the follow-up in patients aged < = 60 and in patients >70. Conclusions The present example demonstrates that a lower treatment effect in older patients on a relative scale can conversely translate into a similar treatment effect on an additive scale due to large baseline hazard differences. Importantly, absolute risk reduction, either crude or adjusted, can be calculated from multiplicative survival models. We advocate for a wider use of the absolute scale, especially using additive hazard models, to assess treatment effect and treatment effect modification. PMID:27045168

  10. Kinetics of phase transition in protein solutions on microscopic and mesoscopic length scales

    NASA Astrophysics Data System (ADS)

    Filobelo, Luis F.

    2005-11-01

    Phase transformations in solutions of macromolecules are fundamental for all living things, and of great importance in science and industry. For instance, insulin is biosynthesized in the beta cells of the pancreas and stored in crystalline form, which protects it form cleavage, until it is needed. Certain diseases such as Alzheimer, sickle cell anemia, and eye cataract are produced by the polymerization of protein molecules, which loose their functionality after the phase transition. Additionally, separation operations in manufacturing of pharmaceuticals can be eliminated if the crystals produced have a narrow size distribution. The nucleation and growth of crystals can be adequately controlled only if the mechanisms that govern these processes are well understood. Here we have investigated several facets of the kinetics controlling the behavior of phase transition in protein solutions. We performed experiments to determine the homogenous nucleation rate for lysozyme and insulin crystals and the contribution of heterogeneously nucleated crystals. In the first segment of this work we discuss the existence of a solution-to-crystal spinodal boundary derived from these determinations, and showed that the formation of crystalline nuclei from solution occur in two steps for lysozyme: the formation of quasi-droplets of a disordered intermediate, followed by the nucleation of ordered crystalline embryos within these droplets in which the rate of each step depends on a respective free energy barrier and on the growth rate of its near-critical clusters. We addressed experimentally the relative significance of the free-energy barriers and the kinetic factors for the nucleation of crystals from solution. Using dynamic and static light scattering along with differential refractometry, we also characterized the appearance of dense liquid droplets and the magnitude of the second osmotic virial coefficient B2 for insulin in both aqueous solution and in solution containing 15% (v

  11. From nuclei to micro-structure in colloidal crystallization: Investigating intermediate length scales by small angle laser light scattering

    NASA Astrophysics Data System (ADS)

    Beyer, Richard; Franke, Markus; Schöpe, Hans Joachim; Bartsch, Eckhard; Palberg, Thomas

    2015-08-01

    Hard sphere suspensions are well recognized model systems of statistical physics and soft condensed matter. We here investigate the temporal evolution of the immediate environment of nucleating and growing crystals and/or their global scale distribution using time resolved Small Angle Light Scattering (SALS). Simultaneously performed Bragg scattering measurements provide an accurate temporal gauging of the sequence of events. We apply this approach to studies of re-crystallization in several different shear molten hard sphere and attractive hard sphere samples with the focus being on the diversity of observable signal shapes and their change in time. We demonstrate that depending on the preparation conditions different processes occur on length scales larger than the structural scale, which significantly influence both the crystallization kinetics and the final micro-structure. By careful analysis of the SALS signal evolution and by comparing different suggestions for small angle signal shapes to our data, we can for most cases identify the processes leading to the observed signals. These include form factor scattering from crystals surrounded by depletion zones and structure factor scattering from late stage inter-crystallite ordering. The large variety of different small angle signals thus in principle contains valuable information complementary to that gained from Bragg scattering or microscopy. Our comparison, however, also shows that further refinement and adaptation of the theoretical expressions to the sample specific boundary conditions is desired for a quantitative kinetic analysis of micro-structural evolution.

  12. Extraction of Channel Length Independent Series Resistance for Deeply Scaled Metal-Oxide-Semiconductor Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Ma, Li-Juan; Ji, Xiao-Li; Chen, Yuan-Cong; Xia, Hao-Guang; Zhu, Chen-Xin; Guo, Qiang; Yan, Feng

    2014-09-01

    The recently developed four Rsd extraction methods from a single device, involving the constant-mobility method, the direct Id—Vgs method, the conductance method and the Y-function method, are evaluated on 32 nm n-channel metal-oxide-semiconductor field-effect transistors (nMOSFETs). It is found that Rsd achieved from the constant-mobility method exhibits the channel length independent characteristics. The L-dependent Rsd extracted from the other three methods is proven to be associated with the gate-voltage-induced mobility degradation in the extraction procedures. Based on L-dependent behaviors of Rsd, a new method is proposed for accurate series resistance extraction on deeply scaled MOSFETs.

  13. Characteristic length scale of the magnon accumulation in Fe3O4/Pt bilayer structures by incoherent thermal excitation

    NASA Astrophysics Data System (ADS)

    Anadón, A.; Ramos, R.; Lucas, I.; Algarabel, P. A.; Morellón, L.; Ibarra, M. R.; Aguirre, M. H.

    2016-07-01

    The dependence of Spin Seebeck effect (SSE) with the thickness of the magnetic materials is studied by means of incoherent thermal excitation. The SSE voltage signal in Fe3O4/Pt bilayer structure increases with the magnetic material thickness up to 100 nm, approximately, showing signs of saturation for larger thickness. This dependence is well described in terms of a spin current pumped in the platinum film by the magnon accumulation in the magnetic material. The spin current is generated by a gradient of temperature in the system and detected by the Pt top contact by means of inverse spin Hall effect. Calculations in the frame of the linear response theory adjust with a high degree of accuracy the experimental data, giving a thermal length scale of the magnon accumulation (Λ) of 17 ± 3 nm at 300 K and Λ = 40 ± 10 nm at 70 K.

  14. Transport and self-organization across different length scales powered by motor proteins and programmed by DNA

    NASA Astrophysics Data System (ADS)

    Wollman, Adam J. M.; Sanchez-Cano, Carlos; Carstairs, Helen M. J.; Cross, Robert A.; Turberfield, Andrew J.

    2014-01-01

    In eukaryotic cells, cargo is transported on self-organized networks of microtubule trackways by kinesin and dynein motor proteins. Synthetic microtubule networks have previously been assembled in vitro, and microtubules have been used as shuttles to carry cargoes on lithographically defined tracks consisting of surface-bound kinesin motors. Here, we show that molecular signals can be used to program both the architecture and the operation of a self-organized transport system that is based on kinesin and microtubules and spans three orders of magnitude in length scale. A single motor protein, dimeric kinesin-1, is conjugated to various DNA nanostructures to accomplish different tasks. Instructions encoded into the DNA sequences are used to direct the assembly of a polar array of microtubules and can be used to control the loading, active concentration and unloading of cargo on this track network, or to trigger the disassembly of the network.

  15. Sizing Up the Milky Way: A Bayesian Mixture Model Meta-analysis of Photometric Scale Length Measurements

    NASA Astrophysics Data System (ADS)

    Licquia, Timothy C.; Newman, Jeffrey A.

    2016-11-01

    The exponential scale length (L d ) of the Milky Way’s (MW’s) disk is a critical parameter for describing the global physical size of our Galaxy, important both for interpreting other Galactic measurements and helping us to understand how our Galaxy fits into extragalactic contexts. Unfortunately, current estimates span a wide range of values and are often statistically incompatible with one another. Here, we perform a Bayesian meta-analysis to determine an improved, aggregate estimate for L d , utilizing a mixture-model approach to account for the possibility that any one measurement has not properly accounted for all statistical or systematic errors. Within this machinery, we explore a variety of ways of modeling the nature of problematic measurements, and then employ a Bayesian model averaging technique to derive net posterior distributions that incorporate any model-selection uncertainty. Our meta-analysis combines 29 different (15 visible and 14 infrared) photometric measurements of L d available in the literature; these involve a broad assortment of observational data sets, MW models and assumptions, and methodologies, all tabulated herein. Analyzing the visible and infrared measurements separately yields estimates for L d of {2.71}-0.20+0.22 kpc and {2.51}-0.13+0.15 kpc, respectively, whereas considering them all combined yields 2.64 ± 0.13 kpc. The ratio between the visible and infrared scale lengths determined here is very similar to that measured in external spiral galaxies. We use these results to update the model of the Galactic disk from our previous work, constraining its stellar mass to be {4.8}-1.1+1.5× {10}10 M ⊙, and the MW’s total stellar mass to be {5.7}-1.1+1.5× {10}10 M ⊙.

  16. Irreversible Wash Aid Additive for Cesium Mitigation. Small-Scale Demonstration and Lessons Learned

    SciTech Connect

    Kaminski, Michael

    2015-01-01

    The Irreversible Wash Aid Additive process has been under development by the U.S. Environmental Protection Agency (EPA) and Argonne National Laboratory (Argonne). This process for radioactive cesium mitigation consists of a solution to wash down contaminated structures, roadways, and vehicles and a sequestering agent to bind the radionuclides from the wash water and render them environmentally immobile. The purpose of this process is to restore functionality to basic services and immediately reduce the consequences of a radiologically-contaminated urban environment. Research and development have resulted in a down-selection of technologies for integration and demonstration at the pilot-scale level as part of the Wide Area Recovery and Resiliency Program (WARRP) under the Department of Homeland Security and the Denver Urban Area Security Initiative. As part of developing the methods for performing a pilot-scale demonstration at the WARRP conference in Denver in 2012, Argonne conducted small-scale field experiments at Separmatic Systems. The main purpose of these experiments was to refine the wash water collection and separations systems and demonstrate key unit operations to help in planning for the large scale demonstration in Denver. Since the purpose of these tests was to demonstrate the operations of the system, we used no radioactive materials. After a brief set of experiments with the LAKOS unit to familiarize ourselves with its operation, two experiments were completed on two separate dates with the Separmatic systems.

  17. On mechanics and material length scales of failure in heterogeneous interfaces using a finite strain high performance solver

    NASA Astrophysics Data System (ADS)

    Mosby, Matthew; Matouš, Karel

    2015-12-01

    Three-dimensional simulations capable of resolving the large range of spatial scales, from the failure-zone thickness up to the size of the representative unit cell, in damage mechanics problems of particle reinforced adhesives are presented. We show that resolving this wide range of scales in complex three-dimensional heterogeneous morphologies is essential in order to apprehend fracture characteristics, such as strength, fracture toughness and shape of the softening profile. Moreover, we show that computations that resolve essential physical length scales capture the particle size-effect in fracture toughness, for example. In the vein of image-based computational materials science, we construct statistically optimal unit cells containing hundreds to thousands of particles. We show that these statistically representative unit cells are capable of capturing the first- and second-order probability functions of a given data-source with better accuracy than traditional inclusion packing techniques. In order to accomplish these large computations, we use a parallel multiscale cohesive formulation and extend it to finite strains including damage mechanics. The high-performance parallel computational framework is executed on up to 1024 processing cores. A mesh convergence and a representative unit cell study are performed. Quantifying the complex damage patterns in simulations consisting of tens of millions of computational cells and millions of highly nonlinear equations requires data-mining the parallel simulations, and we propose two damage metrics to quantify the damage patterns. A detailed study of volume fraction and filler size on the macroscopic traction-separation response of heterogeneous adhesives is presented.

  18. Modified Bose-Einstein and Fermi-Dirac statistics if excitations are localized on an intermediate length scale: applications to non-Debye specific heat.

    PubMed

    Chamberlin, Ralph V; Davis, Bryce F

    2013-10-01

    Disordered systems show deviations from the standard Debye theory of specific heat at low temperatures. These deviations are often attributed to two-level systems of uncertain origin. We find that a source of excess specific heat comes from correlations between quanta of energy if excitations are localized on an intermediate length scale. We use simulations of a simplified Creutz model for a system of Ising-like spins coupled to a thermal bath of Einstein-like oscillators. One feature of this model is that energy is quantized in both the system and its bath, ensuring conservation of energy at every step. Another feature is that the exact entropies of both the system and its bath are known at every step, so that their temperatures can be determined independently. We find that there is a mismatch in canonical temperature between the system and its bath. In addition to the usual finite-size effects in the Bose-Einstein and Fermi-Dirac distributions, if excitations in the heat bath are localized on an intermediate length scale, this mismatch is independent of system size up to at least 10(6) particles. We use a model for correlations between quanta of energy to adjust the statistical distributions and yield a thermodynamically consistent temperature. The model includes a chemical potential for units of energy, as is often used for other types of particles that are quantized and conserved. Experimental evidence for this model comes from its ability to characterize the excess specific heat of imperfect crystals at low temperatures.

  19. Deformation across length scales in polyolefines: effect of the chain microstructure on the polymorphism, phase transitions and morphological changes

    NASA Astrophysics Data System (ADS)

    Auriemma, Finizia; De Rosa, Claudio; di Girolamo, Rocco; Malafronte, Anna; Scoti, Miriam

    The transformations related to phase changes of the crystals, and at lamellar length scales by effect of tensile deformation are studied in the case of some isotactic polypropylene samples having high molecular mass, polydispersity index ~2, and stereodefects at different concentrations and with a uniform distribution, The stress induced transformations are followed in real time during stretching through wide and small angle X-ray scattering measurements. The data analysis evidences that during the transformations of the spherulitic into the fibrillar morphology, stress-induced phase transitions occurring during plastic deformation are regulated by the same factors that govern the textural and morphological changes, that is the ability of the entangled amorphous chains to transmit the stress and the intrinsic stability of the lamellar crystals. Since the relative stability of the different polymorphic forms involved in the structural transformations and the intrinsic flexibility of the chains depend on the stereoregularity, precise correlations between the stereoregularity of the chains, and the deformation behavior are outlined, paving the way for understanding the material properties at molecular level.

  20. The seasonal and solar cycle variations of electron density gradient scale length during magnetically disturbed days: implications for Spread F

    NASA Astrophysics Data System (ADS)

    Manju, G.; Devasia, C. V.; Ravindran, S.

    2009-07-01

    The behaviour of electron density gradient scale length, L, around post-sunset hours during the magnetically disturbed days of the summer, winter and equinox seasons of solar maximum (2002) and minimum years (1995) has been studied, using ionosonde data of Trivandrum (8.5°N, 76.5°E, dip = 0.5°N) in the Indian longitude sector. The results indicate a clear seasonal and solar cycle variation in L. Seasonal variations of the maximum vertical drift of the F layer were also examined on these days. In particular, the seasonal variation of the Equatorial Spread F (ESF) during this period is examined in terms of the relative roles of L and the vertical drift of the F layer in the triggering of the collisional Rayleigh-Taylor instability. Our results on the clear-cut seasonal and solar cycle variation in L for disturbed days and its control of ESF occurrence are presented and discussed.

  1. Geometry- and Length Scale-Dependent Deformation and Recovery on Micro- and Nanopatterned Shape Memory Polymer Surfaces

    NASA Astrophysics Data System (ADS)

    Lee, Wei Li; Low, Hong Yee

    2016-03-01

    Micro- and nanoscale surface textures, when optimally designed, present a unique approach to improve surface functionalities. Coupling surface texture with shape memory polymers may generate reversibly tuneable surface properties. A shape memory polyetherurethane is used to prepare various surface textures including 2 μm- and 200 nm-gratings, 250 nm-pillars and 200 nm-holes. The mechanical deformation via stretching and recovery of the surface texture are investigated as a function of length scales and shapes. Results show the 200 nm-grating exhibiting more deformation than 2 μm-grating. Grating imparts anisotropic and surface area-to-volume effects, causing different degree of deformation between gratings and pillars under the same applied macroscopic strain. Full distribution of stress within the film causes the holes to deform more substantially than the pillars. In the recovery study, unlike a nearly complete recovery for the gratings after 10 transformation cycles, the high contribution of surface energy impedes the recovery of holes and pillars. The surface textures are shown to perform a switchable wetting function. This study provides insights into how geometric features of shape memory surface patterns can be designed to modulate the shape programming and recovery, and how the control of reversibly deformable surface textures can be applied to transfer microdroplets.

  2. Creep deformation behavior of Sn-3.5Ag solder/Cu couple at small length scales

    SciTech Connect

    Kerr, M.; Chawla, N

    2004-09-06

    In order to adequately characterize the behavior of solder balls in electronic devices, the mechanical behavior of solder joints needs to be studied at small length scales. The creep behavior of single solder ball Sn-Ag/Cu solder joints was studied in shear, at 25, 60, 95, and 130 deg. C, using a microforce testing system. A change in the creep stress exponent with increasing stress was observed and explained in terms of a threshold stress for bypass of Ag{sub 3}Sn particles by dislocations. The stress exponent was also temperature dependent, exhibiting an increase in exponent of two from lower to higher temperature. The activation energy for creep was found to be temperature dependant, correlating with self-diffusion of pure Sn at high temperatures, and dislocation core diffusion of pure Sn at lower temperatures. Normalizing the creep rate for activation energy and the temperature-dependence of shear modulus allowed for unification of the creep data. Microstructure characterization, including preliminary TEM analysis, and fractographic analysis were conducted in order to fully describe the creep behavior of the material.

  3. Seeing with the nano-eye: accessing structure, function, and dynamics of matter on its natural length and time scales

    NASA Astrophysics Data System (ADS)

    Raschke, Markus

    2015-03-01

    To understand and ultimately control the properties of most functional materials, from molecular soft-matter to quantum materials, requires access to the structure, coupling, and dynamics on the elementary time and length scales that define the microscopic interactions in these materials. To gain the desired nanometer spatial resolution with simultaneous spectroscopic specificity we combine scanning probe microscopy with different optical, including coherent, nonlinear, and ultrafast spectroscopies. The underlying near-field interaction mediated by the atomic-force or scanning tunneling microscope tip provides the desired deep-sub wavelength nano-focusing enabling few-nm spatial resolution. I will introduce our generalization of the approach in terms of the near-field impedance matching to a quantum system based on special optical antenna-tip designs. The resulting enhanced and qualitatively new forms of light-matter interaction enable measurements of quantum dynamics in an interacting environment or to image the electromagnetic local density of states of thermal radiation. Other applications include the inter-molecular coupling and dynamics in soft-matter hetero-structures, surface plasmon interferometry as a probe of electronic structure and dynamics in graphene, and quantum phase transitions in correlated electron materials. These examples highlight the general applicability of the new near-field microscopy approach, complementing emergent X-ray and electron imaging tools, aiming towards the ultimate goal of probing matter on its most elementary spatio-temporal level.

  4. Pulsed 86Sr-labeling and NanoSIMS imaging to study coral biomineralization at ultra-structural length scales

    NASA Astrophysics Data System (ADS)

    Brahmi, C.; Domart-Coulon, I.; Rougée, L.; Pyle, D. G.; Stolarski, J.; Mahoney, J. J.; Richmond, R. H.; Ostrander, G. K.; Meibom, A.

    2012-09-01

    A method to label marine biocarbonates is developed based on a concentration enrichment of a minor stable isotope of a trace element that is a natural component of seawater, resulting in the formation of biocarbonate with corresponding isotopic enrichments. This biocarbonate is subsequently imaged with a NanoSIMS ion microprobe to visualize the locations of the isotopic marker on sub-micrometric length scales, permitting resolution of all ultra-structural details. In this study, a scleractinian coral, Pocillopora damicornis, was labeled 3 times with 86Sr-enhanced seawater for a period of 48 h with 5 days under normal seawater conditions separating each labeling event. Two non-specific cellular stress biomarkers, glutathione-S-transferase activity and porphyrin concentration plus carbonic anhydrase, an enzymatic marker involved in the physiology of carbonate biomineralization, as well as unchanged levels of zooxanthellae photosynthesis efficiency indicate that coral physiological processes are not affected by the 86Sr-enhancement. NanoSIMS images of the 86Sr/44Ca ratio in skeleton formed during the experiment allow for a determination of the average extension rate of the two major ultra-structural components of the coral skeleton: Rapid Accretion Deposits are found to form on average about 4.5 times faster than Thickening Deposits. The method opens up new horizons in the study of biocarbonate formation because it holds the potential to observe growth of calcareous structures such as skeletons, shells, tests, spines formed by a wide range of organisms under essentially unperturbed physiological conditions.

  5. Global-scale pattern of peatland Sphagnum growth driven by photosynthetically active radiation and growing season length

    NASA Astrophysics Data System (ADS)

    Loisel, J.; Gallego-Sala, A. V.; Yu, Z.

    2012-02-01

    High-latitude peatlands contain about one third of the world's soil organic carbon, most of which is derived from partly decomposed Sphagnum (peat moss) plants. We conducted a meta-analysis based on a global dataset of Sphagnum growth measurements collected from published literature to investigate the effects of bioclimatic variables on Sphagnum growth. Analysis of variance and general linear models were used to relate Sphagnum magellanicum and S. fuscum growth rates to photosynthetically active radiation integrated over the growing season (PAR0) and a moisture index. We found that PAR0 was the main predictor of Sphagnum growth for the global dataset, and effective moisture was only correlated with moss growth at continental sites. The strong correlation between Sphagnum growth and PAR0 suggests the existence of a global pattern of growth, with slow rates under cool climate and short growing seasons, highlighting the important role of temperature and growing season length in explaining peatland biomass production. Large-scale patterns of cloudiness during the growing season might also limit moss growth. Although considerable uncertainty remains over the carbon balance of peatlands under a changing climate, our results suggest that increasing PAR0 as a result of global warming and lengthening growing seasons could promote Sphagnum growth. Assuming that production and decomposition have the same sensitivity to temperature, this enhanced growth could lead to greater peat-carbon sequestration, inducing a negative feedback to climate change.

  6. Global-scale pattern of peatland Sphagnum growth driven by photosynthetically active radiation and growing season length

    NASA Astrophysics Data System (ADS)

    Loisel, J.; Gallego-Sala, A. V.; Yu, Z.

    2012-07-01

    High-latitude peatlands contain about one third of the world's soil organic carbon, most of which is derived from partly decomposed Sphagnum (peat moss) plants. We conducted a meta-analysis based on a global data set of Sphagnum growth measurements collected from published literature to investigate the effects of bioclimatic variables on Sphagnum growth. Analysis of variance and general linear models were used to relate Sphagnum magellanicum and S. fuscum growth rates to photosynthetically active radiation integrated over the growing season (PAR0) and a moisture index. We found that PAR0 was the main predictor of Sphagnum growth for the global data set, and effective moisture was only correlated with moss growth at continental sites. The strong correlation between Sphagnum growth and PAR0 suggests the existence of a global pattern of growth, with slow rates under cool climate and short growing seasons, highlighting the important role of growing season length in explaining peatland biomass production. Large-scale patterns of cloudiness during the growing season might also limit moss growth. Although considerable uncertainty remains over the carbon balance of peatlands under a changing climate, our results suggest that increasing PAR0 as a result of global warming and lengthening growing seasons, without major change in cloudiness, could promote Sphagnum growth. Assuming that production and decomposition have the same sensitivity to temperature, this enhanced growth could lead to greater peat-carbon sequestration, inducing a negative feedback to climate change.

  7. Geometry- and Length Scale-Dependent Deformation and Recovery on Micro- and Nanopatterned Shape Memory Polymer Surfaces

    PubMed Central

    Lee, Wei Li; Low, Hong Yee

    2016-01-01

    Micro- and nanoscale surface textures, when optimally designed, present a unique approach to improve surface functionalities. Coupling surface texture with shape memory polymers may generate reversibly tuneable surface properties. A shape memory polyetherurethane is used to prepare various surface textures including 2 μm- and 200 nm-gratings, 250 nm-pillars and 200 nm-holes. The mechanical deformation via stretching and recovery of the surface texture are investigated as a function of length scales and shapes. Results show the 200 nm-grating exhibiting more deformation than 2 μm-grating. Grating imparts anisotropic and surface area-to-volume effects, causing different degree of deformation between gratings and pillars under the same applied macroscopic strain. Full distribution of stress within the film causes the holes to deform more substantially than the pillars. In the recovery study, unlike a nearly complete recovery for the gratings after 10 transformation cycles, the high contribution of surface energy impedes the recovery of holes and pillars. The surface textures are shown to perform a switchable wetting function. This study provides insights into how geometric features of shape memory surface patterns can be designed to modulate the shape programming and recovery, and how the control of reversibly deformable surface textures can be applied to transfer microdroplets. PMID:27026290

  8. Probabilistic approach to the length-scale dependence of the effect of water hydrogen bonding on hydrophobic hydration.

    PubMed

    Djikaev, Y S; Ruckenstein, E

    2013-06-13

    We present a probabilistic approach to water-water hydrogen bonding that allows one to obtain an analytic expression for the number of bonds per water molecule as a function of both its distance to a hydrophobic particle and hydrophobe radius. This approach can be used in density functional theory (DFT) and computer simulations to examine particle size effects on the hydration of particles and on their solvent-mediated interaction. For example, it allows one to explicitly identify a water hydrogen bond contribution to the external potential, whereto a water molecule is subjected near a hydrophobe. The DFT implementation of the model predicts the hydration free energy per unit area of a spherical hydrophobe to be sharply sensitive to the hydrophobe radius for small radii and weakly sensitive thereto for large ones; this corroborates the vision of the hydration of small and large length-scale particles as occurring via different mechanisms. On the other hand, the model predicts that the hydration of even apolar particles of small enough radii may become thermodynamically favorable owing to the interplay of the energies of pairwise (dispersion) water-water and water-hydrophobe interactions. This sheds light on previous counterintuitive observations (both theoretical and simulational) that two inert gas molecules would prefer to form a solvent-separated pair rather than a contact one.

  9. Interpretation of Single- and Multiple-Beam SBS Observations in OMEGA, Long-Scale-Length Plasma Experiments

    NASA Astrophysics Data System (ADS)

    Short, R. W.; Craxton, R. S.; Seka, W.; Meyerhofer, D. D.

    2001-10-01

    Recent experiments on OMEGA have studied stimulated Brillouin backscatter in preformed long-scale-length plasmas for both single and multiple interaction beams. Scattered light intensities and spectra were obtained for a variety of irradiation conditions. Ion Landau damping is estimated to be sufficiently strong in these plasmas that the locally driven approximation for the ion-sound wave response can be applied. The linear SBS gain coefficient can then obtained by integrating the coupled wave equations for the incident and scattered light throughout the underdense plasma corona. Using density, velocity, and temperature profiles obtained from the two-dimensional Eulerian hydrocode SAGE, we have calculated as a function of wavelength the SBS gain coefficients to be expected in these experiments. Comparison with the observed scattering levels and spectra allows several conclusions to be drawn regarding the SBS process in these plasmas. Most saliently, the scattering appears to be dominated by SBS occurring in hot spots, and plasma velocity profiles have a strong influence on the location and level of scattering. Generally good agreement is found between the observations and the calculations, though some discrepancies remain, particularly in the absorption levels and spectral shifts. This work was supported by the U.S. DOE of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

  10. Review and evaluation of literature on testing of chemical additives for scale control in geothermal fluids. Final report

    SciTech Connect

    Crane, C.H.; Kenkeremath, D.C.

    1981-01-01

    A selected group of reported tests of chemical additives in actual geothermal fluids are reviewed and evaluated to summarize the status of chemical scale-control testing and identify information and testing needs. The task distinguishes between scale control in the cooling system of a flash plant and elsewhere in the utilization system due to the essentially different operating environments involved. Additives for non-cooling geothermal fluids are discussed by scale type: silica, carbonate, and sulfide.

  11. Nutrient addition effects on tropical dry forests: a mini-review from microbial to ecosystem scales

    NASA Astrophysics Data System (ADS)

    Powers, Jennifer; Becklund, Kristen; Gei, Maria; Iyengar, Siddarth; Meyer, Rebecca; O'Connell, Christine; Schilling, Erik; Smith, Christina; Waring, Bonnie; Werden, Leland

    2015-06-01

    Humans have more than doubled inputs of reactive nitrogen globally and greatly accelerated the biogeochemical cycles of phosphorus and metals. However, the impacts of increased element mobility on tropical ecosystems remain poorly quantified, particularly for the vast tropical dry forest biome. Tropical dry forests are characterized by marked seasonality, relatively little precipitation, and high heterogeneity in plant functional diversity and soil chemistry. For these reasons, increased nutrient deposition may affect tropical dry forests differently than wet tropical or temperate forests. Here we review studies that investigated how nutrient availability affects ecosystem and community processes from the microsite to ecosystem scales in tropical dry forests. The effects of N and P addition on ecosystem carbon cycling and plant and microbial dynamics depend on forest successional stage, soil parent material and rainfall regime. Responses may depend on whether overall productivity is N- versus P-limited, although data to test this hypothesis are limited. These results highlight the many important gaps in our understanding of tropical dry forest responses to global change. Large-scale experiments are required to resolve these uncertainties.

  12. Scaling plant nitrogen use and uptake efficiencies in response to nutrient addition in peatlands

    SciTech Connect

    Iversen, Colleen M; Bridgham, Scott; Kellogg, Laurie E.

    2010-01-01

    Nitrogen (N) is the primary growth-limiting nutrient in many terrestrial ecosystems, and therefore plant production per unit N taken up (i.e., N use efficiency, NUE) is a fundamentally important component of ecosystem function. Nitrogen use efficiency comprises two components: N productivity (AN, plant production per peak biomass N content) and the mean residence time of N in plant biomass (MRTN). We utilized a five-year fertilization experiment to examine the manner in which increases in N and phosphorus (P) availability affected plant NUE at multiple biological scales (i.e., from leaf to community level). We fertilized a natural gradient of nutrient-limited peatland ecosystems in the Upper Peninsula of Michigan, USA, with 6 g Nm2yr1, 2 g Pm2yr1, or a combination of N and P. Our objectives were to determine how changes in carbon and N allocation within a plant to leaf and woody tissue and changes in species composition within a community, both above- and belowground, would affect (1) NUE; (2) the adaptive trade-off between the components of NUE; (3) the efficiency with which plants acquired N from the soil (N uptake efficiency); and (4) plant community production per unit soil N availability (N response efficiency, NRE). As expected, N and P addition generally increased aboveground production and N uptake. In particular, P availability strongly affected the way in which plants took up and used N. Nitrogen use efficiency response to nutrient addition was not straightforward. Nitrogen use efficiency differed between leaf and woody tissue, among species, and across the ombrotrophic minerotrophic gradient because plants and communities were adapted to maximize either AN or MRTN, but not both concurrently. Increased N availability strongly decreased plant and community N uptake efficiency, while increased P availability increased N uptake efficiency, particularly in a nitrogen-fixing shrub. Nitrogen uptake efficiency was more important in controlling overall plant

  13. Scaling plant nitrogen use and uptake efficiencies in response to nutrient addition in peatlands.

    PubMed

    Iversen, Colleen M; Bridgham, Scott D; Kellogg, Laurie E

    2010-03-01

    Nitrogen (N) is the primary growth-limiting nutrient in many terrestrial ecosystems, and therefore plant production per unit N taken up (i.e., N use efficiency, NUE) is a fundamentally important component of ecosystem function. Nitrogen use efficiency comprises two components: N productivity (A(N), plant production per peak biomass N content) and the mean residence time of N in plant biomass (MRT(N)). We utilized a five-year fertilization experiment to examine the manner in which increases in N and phosphorus (P) availability affected plant NUE at multiple biological scales (i.e., from leaf to community level). We fertilized a natural gradient of nutrient-limited peatland ecosystems in the Upper Peninsula of Michigan, USA, with 6 g N x m(-2) x yr(-1), 2 g P x m(-2) x yr(-1), or a combination of N and P. Our objectives were to determine how changes in carbon and N allocation within a plant to leaf and woody tissue and changes in species composition within a community, both above- and belowground, would affect (1) NUE; (2) the adaptive trade-off between the components of NUE; (3) the efficiency with which plants acquired N from the soil (N uptake efficiency); and (4) plant community production per unit soil N availability (N response efficiency, NRE). As expected, N and P addition generally increased aboveground production and N uptake. In particular, P availability strongly affected the way in which plants took up and used N. Nitrogen use efficiency response to nutrient addition was not straightforward. Nitrogen use efficiency differed between leaf and woody tissue, among species, and across the ombrotrophic-minerotrophic gradient because plants and communities were adapted to maximize either A(N) or MRT(N), but not both concurrently. Increased N availability strongly decreased plant and community N uptake efficiency, while increased P availability increased N uptake efficiency, particularly in a nitrogen-fixing shrub. Nitrogen uptake efficiency was more important

  14. Atomistic simulation of laser-pulse surface modification: Predictions of models with various length and time scales

    SciTech Connect

    Starikov, Sergey V. Pisarev, Vasily V.

    2015-04-07

    In this work, the femtosecond laser pulse modification of surface is studied for aluminium (Al) and gold (Au) by use of two-temperature atomistic simulation. The results are obtained for various atomistic models with different scales: from pseudo-one-dimensional to full-scale three-dimensional simulation. The surface modification after laser irradiation can be caused by ablation and melting. For low energy laser pulses, the nanoscale ripples may be induced on a surface by melting without laser ablation. In this case, nanoscale changes of the surface are due to a splash of molten metal under temperature gradient. Laser ablation occurs at a higher pulse energy when a crater is formed on the surface. There are essential differences between Al ablation and Au ablation. In the first step of shock-wave induced ablation, swelling and void formation occur for both metals. However, the simulation of ablation in gold shows an additional athermal type of ablation that is associated with electron pressure relaxation. This type of ablation takes place at the surface layer, at a depth of several nanometers, and does not induce swelling.

  15. Near-tip dual-length scale mechanics of mode-I cracking in laminate brittle matrix composites

    NASA Technical Reports Server (NTRS)

    Ballarini, R.; Islam, S.; Charalambides, P. G.

    1992-01-01

    This paper presents the preliminary results of an on-going study of the near-tip mechanics of mode-I cracking in brittle matrix composite laminates. A finite element model is developed within the context of two competing characteristic lengths present in the composite: the microstructural length (the thickness of the layers) and a macro-length (crack-length, uncracked ligament size, etc.). For various values of the parameters which describe the ratio of these lengths and the constituent properties, the stresses ahead of a crack perpendicular to the laminates are compared with those predicted by assuming the composite is homogeneous orthotropic. The results can be used to determine the conditions for which homogenization can provide a sufficiently accurate description of the stresses in the vicinity of the crack-tip.

  16. A study protocol of a randomised controlled trial incorporating a health economic analysis to investigate if additional allied health services for rehabilitation reduce length of stay without compromising patient outcomes

    PubMed Central

    2010-01-01

    Background Reducing patient length of stay is a high priority for health service providers. Preliminary information suggests additional Saturday rehabilitation services could reduce the time a patient stays in hospital by three days. This large trial will examine if providing additional physiotherapy and occupational therapy services on a Saturday reduces health care costs, and improves the health of hospital inpatients receiving rehabilitation compared to the usual Monday to Friday service. We will also investigate the cost effectiveness and patient outcomes of such a service. Methods/Design A randomised controlled trial will evaluate the effect of providing additional physiotherapy and occupational therapy for rehabilitation. Seven hundred and twelve patients receiving inpatient rehabilitation at two metropolitan sites will be randomly allocated to the intervention group or control group. The control group will receive usual care physiotherapy and occupational therapy from Monday to Friday while the intervention group will receive the same amount of rehabilitation as the control group Monday to Friday plus a full physiotherapy and occupational therapy service on Saturday. The primary outcomes will be patient length of stay, quality of life (EuroQol questionnaire), the Functional Independence Measure (FIM), and health utilization and cost data. Secondary outcomes will assess clinical outcomes relevant to the goals of therapy: the 10 metre walk test, the timed up and go test, the Personal Care Participation Assessment and Resource Tool (PC PART), and the modified motor assessment scale. Blinded assessors will assess outcomes at admission and discharge, and follow up data on quality of life, function and health care costs will be collected at 6 and 12 months after discharge. Between group differences will be analysed with analysis of covariance using baseline measures as the covariate. A health economic analysis will be carried out alongside the randomised

  17. Upscaling analysis of aerodynamic roughness length based on in situ data at different spatial scales and remote sensing in north Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Sun, Genhou; Hu, Zeyong; Wang, Jiemin; Xie, Zhipeng; Lin, Yun; Huang, Fangfang

    2016-07-01

    The aerodynamic roughness length (z0m) is a crucial parameter in quantifying momentum, sensible and latent heat fluxes between land surface and atmosphere, and it depends greatly on spatial scales. This paper presents a tentative study on the upscaling analysis of z0m in the north Tibetan Plateau based on in situ data from eddy covariance (EC) and large aperture scintillometer (LAS) and leaf area index (LAI) of MODerate-resolution Imaging Spectroradiometer (MODIS) with 250 m and 2 km spatial resolutions. The comparison of z0m calculated from EC (z0m_EC) and LAS (z0m _LAS) data indicates that z0m at both scales has apparent seasonal variations and is in good agreement with the LAI result. However, z0m_LAS is higher than z0m_EC, which is attributed to the differences in roughness elements in their footprints. An upscaling relationship for z0m is developed with z0m_EC, z0m _LAS and LAI with 250 m spatial resolution of MODIS. In addition, an altitude correction factor is introduced into the vegetation height estimation equation because the cold environment in the north Tibetan Plateau, which is due to its high altitude, has a strong influence on vegetation height. The z0m retrieval with 250 m spatial resolution in the rain season is validated with z0m_EC at sites Nagqu/Amdo, Nagqu/MS3478 and Nagqu/NewD66, and the agreement is acceptable. The spatial distribution of z0m retrievals at small spatial scale in the north Tibetan Plateau from June to September 2012 shows that the z0m values are less than 0.015 m in most areas, with the exception of the area in the southeast part, where z0m reaches 0.025 m owing to low altitudes. The z0m retrievals at large spatial scale in the north Tibetan Plateau from June to September 2012 range from 0.015 to 0.065 m, and high values appear in the area with low altitudes. The spatial distribution and frequency statistics of z0m retrievals at both spatial scales reveal the influence of altitude and LAI on the z0m in the north Tibetan

  18. Combined single crystal polarized XAFS and XRD at high pressure: probing the interplay between lattice distortions and electronic order at multiple length scales in high T c cuprates

    DOE PAGES

    Fabbris, G.; Hücker, M.; Gu, G. D.; Tranquada, J. M.; Haskel, D.

    2016-07-14

    Some of the most exotic material properties derive from electronic states with short correlation length (~10-500 Å), suggesting that the local structural symmetry may play a relevant role in their behavior. In this study, we discuss the combined use of polarized x-ray absorption fine structure and x-ray diffraction at high pressure as a powerful method to tune and probe structural and electronic orders at multiple length scales. Besides addressing some of the technical challenges associated with such experiments, we illustrate this approach with results obtained in the cuprate La1.875Ba0.125CuO4, in which the response of electronic order to pressure can onlymore » be understood by probing the structure at the relevant length scales.« less

  19. "Bottom-up" meets "top-down" : self-assembly to direct manipulation of nanostructures on length scales from atoms to microns.

    SciTech Connect

    Swartzentruber, Brian Shoemaker

    2009-04-01

    This document is the final SAND Report for the LDRD Project 102660 - 'Bottomup' meets 'top-down': Self-assembly to direct manipulation of nanostructures on length scales from atoms to microns - funded through the Strategic Partnerships investment area as part of the National Institute for Nano-Engineering (NINE) project.

  20. The Scales of Time, Length, Mass, Energy, and Other Fundamental Physical Quantities in the Atomic World and the Use of Atomic Units in Quantum Mechanical Calculations

    ERIC Educational Resources Information Center

    Teo, Boon K.; Li, Wai-Kee

    2011-01-01

    This article is divided into two parts. In the first part, the atomic unit (au) system is introduced and the scales of time, space (length), and speed, as well as those of mass and energy, in the atomic world are discussed. In the second part, the utility of atomic units in quantum mechanical and spectroscopic calculations is illustrated with…

  1. Bridging the Gap Between Large-scale Data Sets and Analyses: Semi-automated Methods to Facilitate Length Polymorphism Scoring and Data Analyses.

    EPA Science Inventory

    Amplified fragment length polymorphism (AFLP) markers can be developed more quickly and at a lower cost than microsatellite and single nucleotide polymorphism markers, which makes them ideal markers for large-scale studies of understudied taxa — such as species at risk. However,...

  2. DNA-protein interactions as the source of large-length-scale chirality evident in the liquid crystal behavior of filamentous bacteriophages.

    PubMed

    Tomar, Sonit; Green, Mark M; Day, Loren A

    2007-03-21

    Although all filamentous phages are constructed of chiral components, this study of eight of these phages (fd, IKe, I(2)2, X-2, Pf1, Pf3, tf-1, and X) shows that some form nematic liquid crystals, which are apparently oblivious to the chirality of the components, while others form cholesteric liquid crystals revealing a type of structural chirality not normally encountered. Additions of dopants that interact with the DNA or protein components of the viruses change the liquid crystal properties of seven of the phages. In these seven, DNA-capsid symmetry differences do not allow strict structural equivalency among the protein subunits. The polymorphism arising from this nonequivalency is proposed here to give rise to coiling of the filaments, a large-length-scale chirality that is responsible for forming cholesteric liquid crystal phases. Only one phage of those studied here, Pf1, which is distinguished from the others in its DNA-capsid interactions, forms nematic phases under all conditions tried. The formation of liquid crystals has been developed as a method to detect subtle overall shape effects arising from DNA-subunit-derived polymorphism, an unusual role for the mesogenic state and a new tool for the study of filamentous phage structure.

  3. Predicting the Effects of Nano-Scale Cerium Additives in Diesel Fuel on Regional-Scale Air Quality

    EPA Science Inventory

    Diesel vehicles are a major source of air pollutant emissions. Fuel additives containing nanoparticulate cerium (nCe) are currently being used in some diesel vehicles to improve fuel efficiency. These fuel additives also reduce fine particulate matter (PM2.5) emissio...

  4. Field Testing of a Wet FGD Additive for Enhanced Mercury Control - Task 3 Full-scale Test Results

    SciTech Connect

    Gary Blythe

    2007-05-01

    This Topical Report summarizes progress on Cooperative Agreement DE-FC26-04NT42309, 'Field Testing of a Wet FGD Additive'. The objective of the project is to demonstrate the use of a flue gas desulfurization (FGD) additive, Degussa Corporation's TMT-15, to prevent the reemission of elemental mercury (Hg{sup 0}) in flue gas exiting wet FGD systems on coal-fired boilers. Furthermore, the project intends to demonstrate whether the additive can be used to precipitate most of the mercury (Hg) removed in the wet FGD system as a fine TMT salt that can be separated from the FGD liquor and bulk solid byproducts for separate disposal. The project is conducting pilot- and full-scale tests of the TMT-15 additive in wet FGD absorbers. The tests are intended to determine required additive dosages to prevent Hg{sup 0} reemissions and to separate mercury from the normal FGD byproducts for three coal types: Texas lignite/Power River Basin (PRB) coal blend, high-sulfur Eastern bituminous coal, and low-sulfur Eastern bituminous coal. The project team consists of URS Group, Inc., EPRI, TXU Generation Company LP, Southern Company, and Degussa Corporation. TXU Generation has provided the Texas lignite/PRB cofired test site for pilot FGD tests, Monticello Steam Electric Station Unit 3. Southern Company is providing the low-sulfur Eastern bituminous coal host site for wet scrubbing tests, as well as the pilot- and full-scale jet bubbling reactor (JBR) FGD systems to be tested. IPL, an AES company, provided the high-sulfur Eastern bituminous coal full-scale FGD test site and cost sharing. Degussa Corporation is providing the TMT-15 additive and technical support to the test program as cost sharing. The project is being conducted in six tasks. Of the six project tasks, Task 1 involves project planning and Task 6 involves management and reporting. The other four tasks involve field testing on FGD systems, either at pilot or full scale. The four tasks include: Task 2 - Pilot Additive Testing

  5. Dynamics of lithium ions in borotellurite mixed former glasses: Correlation between the characteristic length scales of mobile ions and glass network structural units

    SciTech Connect

    Shaw, A.; Ghosh, A.

    2014-10-28

    We have studied the mixed network former effect on the dynamics of lithium ions in borotellurite glasses in wide composition and temperature ranges. The length scales of ion dynamics, such as characteristic mean square displacement and spatial extent of sub-diffusive motion of lithium ions have been determined from the ac conductivity and dielectric spectra, respectively, in the framework of linear response theory. The relative concentrations of different network structural units have been determined from the deconvolution of the FTIR spectra. A direct correlation between the ion dynamics and the characteristic length scales and the relative concentration of BO{sub 4} units has been established for different compositions of the borotellurite glasses.

  6. Influence of long-scale length radial electric field components on zonal flow-like structures in the TJ-II stellarator

    NASA Astrophysics Data System (ADS)

    Losada, U.; Alonso, A.; van Milligen, B. Ph; Hidalgo, C.; Liu, B.; Pedrosa, M. A.; Silva, C.; the TJ-II team

    2016-08-01

    The influence of long-scale length radial electric fields on zonal flows-like structures has been studied in the TJ-II stellarator. This relation has been investigated in the edge plasma using two electrical rake probes. The results presented here show an empirical correlation between the properties of long-range correlations (LRCs) with zonal flow-like structures and the magnitude of radial (neoclassical, NC) electric fields in TJ-II neutral beam heated plasmas. These experimental findings show that the enhancement of the NC radial electric field \\boldsymbol{E}{\\mathbf{r}} increases the magnitude of LRCs, considered as a proxy of zonal flows, while the radial correlation length of the plasma potential fluctuations was found to decrease by about 40%. A strong relation between the magnitude of electric field structures with long and short radial scales was found. The calculated \\boldsymbol{E}{\\mathbf{r}}× \\boldsymbol{B} shearing rate corresponding to the short scale length structures of the radial electric field may be sufficient to regulate turbulence.

  7. EnviroAtlas: Incorporation of Community-Scale Data for Additional Communities

    EPA Science Inventory

    EnviroAtlas is ORD’s online spatial decision support tool for viewing and analyzing the supply, demand, and drivers of change related to natural and built infrastructure at multiple scales for the nation. Maps and text identify known relationships between the goods and services ...

  8. Geometrical constraints in the scaling relationships between genome size, cell size and cell cycle length in herbaceous plants.

    PubMed

    Símová, Irena; Herben, Tomás

    2012-03-01

    Plant nuclear genome size (GS) varies over three orders of magnitude and is correlated with cell size and growth rate. We explore whether these relationships can be owing to geometrical scaling constraints. These would produce an isometric GS-cell volume relationship, with the GS-cell diameter relationship with the exponent of 1/3. In the GS-cell division relationship, duration of processes limited by membrane transport would scale at the 1/3 exponent, whereas those limited by metabolism would show no relationship. We tested these predictions by estimating scaling exponents from 11 published datasets on differentiated and meristematic cells in diploid herbaceous plants. We found scaling of GS-cell size to almost perfectly match the prediction. The scaling exponent of the relationship between GS and cell cycle duration did not match the prediction. However, this relationship consists of two components: (i) S phase duration, which depends on GS, and has the predicted 1/3 exponent, and (ii) a GS-independent threshold reflecting the duration of the G1 and G2 phases. The matches we found for the relationships between GS and both cell size and S phase duration are signatures of geometrical scaling. We propose that a similar approach can be used to examine GS effects at tissue and whole plant levels.

  9. Identification of stress-tolerance-related transcription-factor genes via mini-scale Full-length cDNA Over-eXpressor (FOX) gene hunting system.

    PubMed

    Fujita, Miki; Mizukado, Saho; Fujita, Yasunari; Ichikawa, Takanari; Nakazawa, Miki; Seki, Motoaki; Matsui, Minami; Yamaguchi-Shinozaki, Kazuko; Shinozaki, Kazuo

    2007-12-14

    Recently, we developed a novel system known as Full-length cDNA Over-eXpressor (FOX) gene hunting [T. Ichikawa, M. Nakazawa, M. Kawashima, H. Iizumi, H. Kuroda, Y. Kondou, Y. Tsuhara, K. Suzuki, A. Ishikawa, M. Seki, M. Fujita, R. Motohashi, N. Nagata, T. Takagi, K. Shinozaki, M. Matsui, The FOX hunting system: an alternative gain-of-function gene hunting technique, Plant J. 48 (2006) 974-985], which involves the random overexpression of a normalized Arabidopsis full-length cDNA library. While our system allows large-scale collection of full-length cDNAs for gene discovery, we sought to downsize it to analyze a small pool of full-length cDNAs. As a model system, we focused on stress-inducible transcription factors. The full-length cDNAs of 43 stress-inducible transcription factors were mixed to create a transgenic plant library. We screened for salt-stress-resistant lines in the T1 generation and identified a number of salt-tolerant lines that harbored the same transgene (F39). F39 encodes a bZIP-type transcription factor that is identical to AtbZIP60, which is believed to be involved in the endoplasmic reticulum stress response. Microarray analysis revealed that a number of stress-inducible genes were up-regulated in the F39-overexpressing lines, suggesting that AtbZIP60 is involved in stress signal transduction. Thus, our mini-scale FOX system may be used to screen for genes with valuable functions, such as transcription factors, from a small pool of genes that show similar expression profiles.

  10. Field Testing of a Wet FGD Additive for Enhanced Mercury Control - Task 5 Full-Scale Test Results

    SciTech Connect

    Gary Blythe; MariJon Owens

    2007-12-01

    This Topical Report summarizes progress on Cooperative Agreement DE-FC26-04NT42309, 'Field Testing of a Wet FGD Additive'. The objective of the project is to demonstrate the use of two flue gas desulfurization (FGD) additives, Evonik Degussa Corporation's TMT-15 and Nalco Company's Nalco 8034, to prevent the re-emission of elemental mercury (Hg{sup 0}) in flue gas exiting wet FGD systems on coal-fired boilers. Furthermore, the project intends to demonstrate whether the additive can be used to precipitate most of the mercury (Hg) removed in the wet FGD system as a fine salt that can be separated from the FGD liquor and bulk solid byproducts for separate disposal. The project is conducting pilot- and full-scale tests of the additives in wet FGD absorbers. The tests are intended to determine required additive dosages to prevent Hg{sup 0} re-emissions and to separate mercury from the normal FGD byproducts for three coal types: Texas lignite/Powder River Basin (PRB) coal blend, high-sulfur Eastern bituminous coal, and low-sulfur Eastern bituminous coal. The project team consists of URS Group, Inc., EPRI, Luminant Power (was TXU Generation Company LP), Southern Company, IPL (an AES company), Evonik Degussa Corporation and the Nalco Company. Luminant Power has provided the Texas lignite/PRB co-fired test site for pilot FGD tests and cost sharing. Southern Company has provided the low-sulfur Eastern bituminous coal host site for wet scrubbing tests, as well as the pilot- and full-scale jet bubbling reactor (JBR) FGD systems tested. IPL provided the high-sulfur Eastern bituminous coal full-scale FGD test site and cost sharing. Evonik Degussa Corporation is providing the TMT-15 additive, and the Nalco Company is providing the Nalco 8034 additive. Both companies are also supplying technical support to the test program as in-kind cost sharing. The project is being conducted in six tasks. Of the six project tasks, Task 1 involves project planning and Task 6 involves management

  11. PILOT-SCALE STUDIES ON THE EFFECT OF BROMINE ADDITION ON THE EMISSIONS OF CHLORINATED ORGANIC COMBUSTION BY-PRODUCTS

    EPA Science Inventory

    The addition of brominated organic compounds to the feed of a pilot-scale incinerator burning chlorinated waste has been found previously, under some circumstances, to enhance emissions of volatile and semivolatile organic chlorinated products of incomplete combustion (PiCs) incl...

  12. Impact of Alkyl Chain Length on the Transition of Hexagonal Liquid Crystal-Wormlike Micelle-Gel in Ionic Liquid-Type Surfactant Aqueous Solutions without Any Additive.

    PubMed

    Hu, Yimin; Han, Jie; Ge, Lingling; Guo, Rong

    2015-11-24

    The search for functional supramolecular aggregations with different structure has attracted interest of chemists because they have the potential in industrial and technological application. Hydrophobic interaction has great influence on the formation of these aggregations, such as hexagonal liquid crystals, wormlike micelles, hydrogels, etc. So a systematical investigation was done to investigate the influence of alkyl chain length of surfactants on the aggregation behavior in water. The aggregation behavior of 1-hexadecyl-3-alkyl imidazolium bromide and water has been systematically investigated. These ionic liquid surfactants are denoted as C16-Cn (n = 2, 3, 4, 6, 8, 9, 10, 12, 14, 16). The rheological behavior and microstructure were characterized via a combination of rheology, cryo-etch scanning electron microscopy, polarization optical microscopy, and X-ray crystallography. The alkyl chain has great influence on the formation of surfactant aggregates in water at the molecular level. With increasing alkyl chain length, different aggregates, such as hexagonal liquid crystals, wormlike micelles, and hydrogels can be fabricated: C16-C2 aqueous solution only forms hexagonal liquid crystal; C16-C3 aqueous solution forms wormlike micelle and hexagonal liquid crystal; C16-C4, C16-C6 and C16-C8 aqueous solutions only form wormlike micelle; C16-C9 aqueous solution experiences a transition between wormlike micelle and hydrogel; C16-C10, C16-C12, C16-C14 and C16-C16 only form hydrogel. The mechanism of the transition of different aggregation with increasing alkyl chain length was also proposed.

  13. Criterion Noise in Ratings-Based Recognition: Evidence from the Effects of Response Scale Length on Recognition Accuracy

    ERIC Educational Resources Information Center

    Benjamin, Aaron S.; Tullis, Jonathan G.; Lee, Ji Hae

    2013-01-01

    Rating scales are a standard measurement tool in psychological research. However, research has suggested that the cognitive burden involved in maintaining the criteria used to parcel subjective evidence into ratings introduces "decision noise" and affects estimates of performance in the underlying task. There has been debate over whether…

  14. Preliminary simulation of hyporheic hydrology suggests systematic changes in hyporheic flow path length and residence time in response to reach-scale channel restoration in Meacham Creek, OR

    NASA Astrophysics Data System (ADS)

    Amerson, B. E.; Poole, G.

    2011-12-01

    Hyporheic hydrologic response to stream restoration has typically focused on hydrodynamics associated with individual features or habitat units rather than whole reaches. Here we present preliminary results from MODFLOW simulations that compare modeled hyporheic hydrology prior to and after major channel reconfiguration associated with a recently completed reach-scale channel restoration on Meacham Creek in northeastern Oregon. Our model was parameterized using LiDAR floodplain surface elevation data and empirically-derived estimates of aquifer properties. Results show that groundwater flow path length and cumulative residence time distributions are apt to be altered by channel reconfiguration. For example, our model shows that the relatively high-gradient and straight baseline channel is dominated by either short or long flow path lengths, with relatively few medium length flow paths. In contrast, the proposed restoration channel is more sinuous and has a lower gradient. Our modeling suggests that the restoration channel will have a broader distribution of flow path lengths and residence times. We used model results to select well locations for intensive monitoring of groundwater surface elevation and temperature. Monitoring will continue through 2012 and is designed to evaluate model predictions as well as to document the effects of the channel restoration on surface water-groundwater interactions and concomitant effects on water temperature.

  15. Long-term storage and transport length scale of fine sediment: Analysis of a mercury release into a river

    NASA Astrophysics Data System (ADS)

    Pizzuto, J. E.

    2014-08-01

    Excessive suspended sediment concentrations create important water quality problems, but scientists disagree on how to predict its movement through watersheds. Most models assume that fine-grained sediment moves rapidly far downstream, without recognizing the importance of episodic, long-term storage. Here a historic industrial release of mercury is interpreted as a decadal sediment tracer experiment, releasing sediment particles "tagged" with mercury that are deposited on floodplains. As expected, floodplain mercury inventories decrease exponentially downstream, with a characteristic decay length of 10 km (95% confidence interval: 5-25 km) that defines the distance suspended particles typically move downstream before entering storage. Floodplain mercury inventories are not significantly different above and below three colonial age mill dams (present at the time of mercury release but now breached), suggesting that these results reflect ongoing processes. Suspended sediment routing models that neglect long-term storage, and the watershed management plans based on them, may need revision.

  16. Response of soybean rhizosphere communities to human hygiene water addition as determined by community level physiological profiling (CLPP) and terminal restriction fragment length polymorphism (TRFLP) analysis

    NASA Technical Reports Server (NTRS)

    Kerkhof, L.; Santoro, M.; Garland, J.

    2000-01-01

    In this report, we describe an experiment conducted at Kennedy Space Center in the biomass production chamber (BPC) using soybean plants for purification and processing of human hygiene water. Specifically, we tested whether it was possible to detect changes in the root-associated bacterial assemblage of the plants and ultimately to identify the specific microorganism(s) which differed when plants were exposed to hygiene water and other hydroponic media. Plants were grown in hydroponics media corresponding to four different treatments: control (Hoagland's solution), artificial gray water (Hoagland's+surfactant), filtered gray water collected from human subjects on site, and unfiltered gray water. Differences in rhizosphere microbial populations in all experimental treatments were observed when compared to the control treatment using both community level physiological profiles (BIOLOG) and molecular fingerprinting of 16S rRNA genes by terminal restriction fragment length polymorphism analysis (TRFLP). Furthermore, screening of a clonal library of 16S rRNA genes by TRFLP yielded nearly full length SSU genes associated with the various treatments. Most 16S rRNA genes were affiliated with the Klebsiella, Pseudomonas, Variovorax, Burkholderia, Bordetella and Isosphaera groups. This molecular approach demonstrated the ability to rapidly detect and identify microorganisms unique to experimental treatments and provides a means to fingerprint microbial communities in the biosystems being developed at NASA for optimizing advanced life support operations.

  17. Gate length scaling effect on high-electron mobility transistors devices using AlGaN/GaN and AlInN/AlN/GaN heterostructures.

    PubMed

    Liao, S Y; Lu, C C; Chang, T; Huang, C F; Cheng, C H; Chang, L B

    2014-08-01

    Compared to AlGaN/GaN HEMT with 0.15 μm T-gate length, the AlInN/AlN/GaN one exhibits much higher current density and transconductance of 1558 mA/mm at Vd = 2 V and 330 mS/mm, respectively. The high extrinsic ft and fmax of 82 GHz and 70 GHz are extracted from AlInN/AlN/GaN HEMT. Besides, we find that the transconductance roll-off is significant in AlGaN/GaN, but largely improved in AlInN/AlN/GaN HEMT, suggesting that the high carrier density and lattice-matched epitaxial heterostructure is important to reach both large RF output power and high operation frequency, especially for an aggressively gate length scaling.

  18. Gait dynamics in Parkinson’s disease: Common and distinct behavior among stride length, gait variability, and fractal-like scaling

    PubMed Central

    Hausdorff, Jeffrey M.

    2009-01-01

    Parkinson’s disease (PD) is a common, debilitating neurodegenerative disease. Gait disturbances are a frequent cause of disability and impairment for patients with PD. This article provides a brief introduction to PD and describes the gait changes typically seen in patients with this disease. A major focus of this report is an update on the study of the fractal properties of gait in PD, the relationship between this feature of gait and stride length and gait variability, and the effects of different experimental conditions on these three gait properties. Implications of these findings are also briefly described. This update highlights the idea that while stride length, gait variability, and fractal scaling of gait are all impaired in PD, distinct mechanisms likely contribute to and are responsible for the regulation of these disparate gait properties. PMID:19566273

  19. Identification of a kinetic length scale which dictates alloy phase composition in Ni-Al interfaces on annealing at low temperatures

    NASA Astrophysics Data System (ADS)

    Swain, Mitali; Singh, Surendra; Basu, Saibal; Bhattacharya, Debarati; Gupta, Mukul

    2014-12-01

    Ni-aluminides are an important class of intermetallics from technological point of view. Ni-Al phase diagram has been studied in detail experimentally as well as theoretically. It is known that if annealed at low temperature, the first alloy phase is usually NiAl3 according to Bené's rule. It is also understood that heat of formation may get modified by local densities of the constituents forming the alloy. In this regard, it is important to identify a kinetic length scale for defining "local density" in a system. We have deposited ultrathin multilayers of Ni and Al of layer thickness in tens of nanometres with Ni:Al stoichiometric ratio as 3:1 and 1:3, respectively. Considering these stoichiometry, Ni3Al and NiAl3 are the thermodynamically favoured alloy phases in these samples. We used x-ray reflectivity, polarized neutron reflectivity, x-ray diffraction, and secondary ion mass spectroscopy to follow the alloy formation after annealing and identified the alloy phases at interfaces with nanometre resolution. Diffusion length of Ni and Al was obtained using Darken's law. Our results predict that `diffusion length' is the unique length scale that connects kinetics to local density. In another interesting observation, using "virtual Kirkendall markers" at the interfaces, we showed asymmetry in consumption of Al for alloy formation, at Al on Ni (Al/Ni) and Ni on Al (Ni/Al) interfaces by comparing as-deposited and annealed states with respect to the markers.

  20. Density and temperature characterization of long-scale length, near-critical density controlled plasma produced from ultra-low density plastic foam

    NASA Astrophysics Data System (ADS)

    Chen, S. N.; Iwawaki, T.; Morita, K.; Antici, P.; Baton, S. D.; Filippi, F.; Habara, H.; Nakatsutsumi, M.; Nicolaï, P.; Nazarov, W.; Rousseaux, C.; Starodubstev, M.; Tanaka, K. A.; Fuchs, J.

    2016-02-01

    The ability to produce long-scale length (i.e. millimeter scale-length), homogeneous plasmas is of interest in studying a wide range of fundamental plasma processes. We present here a validated experimental platform to create and diagnose uniform plasmas with a density close or above the critical density. The target consists of a polyimide tube filled with an ultra low-density plastic foam where it was heated by x-rays, produced by a long pulse laser irradiating a copper foil placed at one end of the tube. The density and temperature of the ionized foam was retrieved by using x-ray radiography and proton radiography was used to verify the uniformity of the plasma. Plasma temperatures of 5-10 eV and densities around 1021 cm-3 are measured. This well-characterized platform of uniform density and temperature plasma is of interest for experiments using large-scale laser platforms conducting High Energy Density Physics investigations.

  1. Density and temperature characterization of long-scale length, near-critical density controlled plasma produced from ultra-low density plastic foam.

    PubMed

    Chen, S N; Iwawaki, T; Morita, K; Antici, P; Baton, S D; Filippi, F; Habara, H; Nakatsutsumi, M; Nicolaï, P; Nazarov, W; Rousseaux, C; Starodubstev, M; Tanaka, K A; Fuchs, J

    2016-02-29

    The ability to produce long-scale length (i.e. millimeter scale-length), homogeneous plasmas is of interest in studying a wide range of fundamental plasma processes. We present here a validated experimental platform to create and diagnose uniform plasmas with a density close or above the critical density. The target consists of a polyimide tube filled with an ultra low-density plastic foam where it was heated by x-rays, produced by a long pulse laser irradiating a copper foil placed at one end of the tube. The density and temperature of the ionized foam was retrieved by using x-ray radiography and proton radiography was used to verify the uniformity of the plasma. Plasma temperatures of 5-10 eV and densities around 10(21) cm(-3) are measured. This well-characterized platform of uniform density and temperature plasma is of interest for experiments using large-scale laser platforms conducting High Energy Density Physics investigations.

  2. Density and temperature characterization of long-scale length, near-critical density controlled plasma produced from ultra-low density plastic foam

    PubMed Central

    Chen, S. N.; Iwawaki, T.; Morita, K.; Antici, P.; Baton, S. D.; Filippi, F.; Habara, H.; Nakatsutsumi, M.; Nicolaï , P.; Nazarov, W.; Rousseaux, C.; Starodubstev, M.; Tanaka, K. A.; Fuchs, J.

    2016-01-01

    The ability to produce long-scale length (i.e. millimeter scale-length), homogeneous plasmas is of interest in studying a wide range of fundamental plasma processes. We present here a validated experimental platform to create and diagnose uniform plasmas with a density close or above the critical density. The target consists of a polyimide tube filled with an ultra low-density plastic foam where it was heated by x-rays, produced by a long pulse laser irradiating a copper foil placed at one end of the tube. The density and temperature of the ionized foam was retrieved by using x-ray radiography and proton radiography was used to verify the uniformity of the plasma. Plasma temperatures of 5–10 eV and densities around 1021 cm−3 are measured. This well-characterized platform of uniform density and temperature plasma is of interest for experiments using large-scale laser platforms conducting High Energy Density Physics investigations. PMID:26923471

  3. Density and temperature characterization of long-scale length, near-critical density controlled plasma produced from ultra-low density plastic foam.

    PubMed

    Chen, S N; Iwawaki, T; Morita, K; Antici, P; Baton, S D; Filippi, F; Habara, H; Nakatsutsumi, M; Nicolaï, P; Nazarov, W; Rousseaux, C; Starodubstev, M; Tanaka, K A; Fuchs, J

    2016-01-01

    The ability to produce long-scale length (i.e. millimeter scale-length), homogeneous plasmas is of interest in studying a wide range of fundamental plasma processes. We present here a validated experimental platform to create and diagnose uniform plasmas with a density close or above the critical density. The target consists of a polyimide tube filled with an ultra low-density plastic foam where it was heated by x-rays, produced by a long pulse laser irradiating a copper foil placed at one end of the tube. The density and temperature of the ionized foam was retrieved by using x-ray radiography and proton radiography was used to verify the uniformity of the plasma. Plasma temperatures of 5-10 eV and densities around 10(21) cm(-3) are measured. This well-characterized platform of uniform density and temperature plasma is of interest for experiments using large-scale laser platforms conducting High Energy Density Physics investigations. PMID:26923471

  4. Measuring Scale Errors in a Laser Tracker’s Horizontal Angle Encoder Through Simple Length Measurement and Two-Face System Tests

    PubMed Central

    Muralikrishnan, B.; Blackburn, C.; Sawyer, D.; Phillips, S.; Bridges, R.

    2010-01-01

    We describe a method to estimate the scale errors in the horizontal angle encoder of a laser tracker in this paper. The method does not require expensive instrumentation such as a rotary stage or even a calibrated artifact. An uncalibrated but stable length is realized between two targets mounted on stands that are at tracker height. The tracker measures the distance between these two targets from different azimuthal positions (say, in intervals of 20° over 360°). Each target is measured in both front face and back face. Low order harmonic scale errors can be estimated from this data and may then be used to correct the encoder’s error map to improve the tracker’s angle measurement accuracy. We have demonstrated this for the second order harmonic in this paper. It is important to compensate for even order harmonics as their influence cannot be removed by averaging front face and back face measurements whereas odd orders can be removed by averaging. We tested six trackers from three different manufacturers. Two of those trackers are newer models introduced at the time of writing of this paper. For older trackers from two manufacturers, the length errors in a 7.75 m horizontal length placed 7 m away from a tracker were of the order of ± 65 μm before correcting the error map. They reduced to less than ± 25 μm after correcting the error map for second order scale errors. Newer trackers from the same manufacturers did not show this error. An older tracker from a third manufacturer also did not show this error. PMID:27134789

  5. Multi-length-scale Material Model for SiC/SiC Ceramic-Matrix Composites (CMCs): Inclusion of In-Service Environmental Effects

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Galgalikar, R.; Snipes, J. S.; Ramaswami, S.

    2016-01-01

    In our recent work, a multi-length-scale room-temperature material model for SiC/SiC ceramic-matrix composites (CMCs) was derived and parameterized. The model was subsequently linked with a finite-element solver so that it could be used in a general room-temperature, structural/damage analysis of gas-turbine engine CMC components. Due to its multi-length-scale character, the material model enabled inclusion of the effects of fiber/tow (e.g., the volume fraction, size, and properties of the fibers; fiber-coating material/thickness; decohesion properties of the coating/matrix interfaces; etc.) and ply/lamina (e.g., the 0°/90° cross-ply versus plain-weave architectures, the extent of tow crimping in the case of the plain-weave plies, cohesive properties of the inter-ply boundaries, etc.) length-scale microstructural/architectural parameters on the mechanical response of the CMCs. One of the major limitations of the model is that it applies to the CMCs in their as-fabricated conditions (i.e., the effect of prolonged in-service environmental exposure and the associated material aging-degradation is not accounted for). In the present work, the model is upgraded to include such in-service environmental-exposure effects. To demonstrate the utility of the upgraded material model, it is used within a finite-element structural/failure analysis involving impact of a toboggan-shaped turbine shroud segment by a foreign object. The results obtained clearly revealed the effects that different aspects of the in-service environmental exposure have on the material degradation and the extent of damage suffered by the impacted CMC toboggan-shaped shroud segment.

  6. Reduction of laser beam spray at 0.527 (micron)m in an ignition scale length plasma with temporal beam smoothing

    SciTech Connect

    Niemann, C .; Divol, L; Froula, D H; Glenzer, S H; Gregori, G; Kirkwood, R K; MacKinnon, A J; Meezan, N B; Moody, J D; Sorce, C; Suter, L J; Bahr, R; Seka, W

    2004-02-04

    We have measured the effect of laser smoothing by spectral dispersion (SSD) on beam spray, transmission and deflection of a 2{omega} (527 nm) high intensity (10{sup 15} W/cm{sup 2}) interaction beam through an underdense large scale length plasma. We observe a 40% reduction of the beam spray when SSD is used, consistent with modeling by a fluid laser-plasma interaction code (pF3d). We measured a decrease in beam transmission with increasing laser intensity, consistent with the onset of parametric instabilities.

  7. Relations between surface conductance and spectral vegetation indices at intermediate (100 m2 to 15 km2) length scales

    NASA Astrophysics Data System (ADS)

    Sellers, Piers J.; Heiser, Mark D.; Hall, Forrest G.

    1992-11-01

    The theoretical analysis of Sellers et al. (1992) indicates that the relative response of the unstressed canopy conductance (g*c) to changes in incident (nonsaturating) PAR flux (F0) should be proportional to some spectral vegetation indices (SVI), specifically the simple ratio (SR) vegetation index, for vegetation covers of similar physiology and physiognomy; or ∇F ≡ (∂g*c/∂F0) ∝ SR. This relationship was tested using the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE) flux station data set (g*c) and the FIFE Landsat thematic mapper image data (SVI). The flux station data were used to invert a soil-plant-atmosphere model (the simple biosphere model (SiB) of Sellers et al., 1986) to derive estimates of g*c separate from the soil evaporation contribution and corrected for the "stress" effects of vapor pressure deficit and soil moisture deficit. The Landsat imagery was sampled to produce SR vegetation index values for small areas (90 × 90 m) centered on each flux station. The derived ∇F and SR values were found to be near-linearly related on a site-by-site basis. Differences between sites are thought to be related to the fractional cover of C3 versus C4 vegetation so that ∇S,F ≡ (∂∇F/∂(SR)) ∝ V3, where V3 is the fractional cover of C3 vegetation. The above equations form the basis for a simple biophysically based model of canopy-scale conductance. The model was applied on the flux station scale (100 m)2 and was also used to calculate fluxes for the entire FIFE site (15 × 15 km)2; the latter results were compared with airborne flux measurements. It is demonstrated that because the proposed relationship between ∇F and SR is near-linear, the calculation of evapotranspiration rates for large areas using this model is effectively scale-invariant.

  8. The role of length scales in bridging the gap between rock CPO and seismic signals of crustal anisotropy

    NASA Astrophysics Data System (ADS)

    Okaya, D.; Johnson, S. E.; Vel, S. S.; Song, W. J.; Christensen, N. I.

    2012-04-01

    Recent studies based on laboratory petrophysics and in particular EBSD-based calculations indicate material rock anisotropy for crustal rocks can possess significant low orders of symmetry. These symmetries based on elastic tensor calculations can range from hexagonal and orthorhombic down to monoclinic and triclinic. On the other hand, interpretation of field seismic data yield crustal anisotropy of fast- or slow-axis transverse isotropy (hexagonal) symmetry at best; identification of orthorhombic symmetry is barely possible. Seismic results are often limited to simple orientations of the symmetry axes, such as vertical (radial anisotropy) or horizontal (azimuthal anisotropy). The physical scales of earth anisotropic fabrics and of seismic waves affect the types of information that may be extracted from seismic signals. A seismic wave has inherent limits to resolving capabilities, usually measured as some percentage of its wavelength, λ. This wave will accumulate anisotropic signal in two ways based on its path through anisotropic media of physical size, L: (1) When the wave is much smaller than the anisotropic material (λ << L), the seismic signal will be produced integrating along its path. (2) When the wave is much larger than the material (λ >> L), the wave will not see details of the material but will respond to just the bulk average of the material. In the first case, the wave will be sensitive to large scale earth changes such as limbs of an antiformal mountain range. The accumulating anisotropic seismic signal can get complicated (e.g., shear wave splits of splits). In the second case, the wave is too large to see any fine detail, and the material can be represented by an equivalent "effective media" that produces the same seismic response. Geometrical structure is a factor that helps bridge the scales of rock CPO to lower resolution seismic signals. Local rock CPO can fill or be mapped into a structure that is large enough for a seismic wave to respond

  9. Search for Screened Interactions Associated with Dark Energy below the 100 μm Length Scale.

    PubMed

    Rider, Alexander D; Moore, David C; Blakemore, Charles P; Louis, Maxime; Lu, Marie; Gratta, Giorgio

    2016-09-01

    We present the results of a search for unknown interactions that couple to mass between an optically levitated microsphere and a gold-coated silicon cantilever. The scale and geometry of the apparatus enable a search for new forces that appear at distances below 100  μm and which would have evaded previous searches due to screening mechanisms. The data are consistent with electrostatic backgrounds and place upper limits on the strength of new interactions at <0.1  fN in the geometry tested. For the specific example of a chameleon interaction with an inverse power law potential, these results exclude matter couplings β>5.6×10^{4} in the region of parameter space where the self-coupling Λ≳5  meV and the microspheres are not fully screened.

  10. Search for Screened Interactions Associated with Dark Energy below the 100 μm Length Scale.

    PubMed

    Rider, Alexander D; Moore, David C; Blakemore, Charles P; Louis, Maxime; Lu, Marie; Gratta, Giorgio

    2016-09-01

    We present the results of a search for unknown interactions that couple to mass between an optically levitated microsphere and a gold-coated silicon cantilever. The scale and geometry of the apparatus enable a search for new forces that appear at distances below 100  μm and which would have evaded previous searches due to screening mechanisms. The data are consistent with electrostatic backgrounds and place upper limits on the strength of new interactions at <0.1  fN in the geometry tested. For the specific example of a chameleon interaction with an inverse power law potential, these results exclude matter couplings β>5.6×10^{4} in the region of parameter space where the self-coupling Λ≳5  meV and the microspheres are not fully screened. PMID:27636465

  11. Fluorous protic ionic liquids exhibit discrete segregated nano-scale solvent domains and form new populations of nano-scale objects upon primary alcohol addition.

    PubMed

    Greaves, Tamar L; Kennedy, Danielle F; Shen, Yan; Hawley, Adrian; Song, Gonghua; Drummond, Calum J

    2013-05-28

    Fluorous protic ionic liquids (FPILS) containing a perfluorinated anion and hydrocarbon cation have been observed to segregate into nano-scale fluorocarbon, hydrocarbon and polar domains. The solubility and interactions of ethanol and butanol in a series of FPILs has been investigated by synchrotron source small and wide angle X-ray scattering. Nano-scale objects were found to be present within the binary solutions from low concentrations of FPILs in alcohols to around 40 to 80 wt% FPIL. The FPILs retain their fluorocarbon, hydrocarbon and polar domains in binary mixtures with alcohols in addition to the formation of nano-scale alcohol associated objects. For comparison, the influence of alcohols on the nano-scale segregation of analogous protic ionic liquids (PILs) which contained hydrocarbon anions in place of the perfluorinated anions was also investigated. The ethanol and butanol were miscible with the PILs across the full concentration range, with no evidence for the formation of analogous nano-scale objects. The FPILs are prospective solvents which may enable simultaneous solubility of fluorocarbon, hydrocarbon and polar species.

  12. Molecular-scale evidence of aerosol particle formation via sequential addition of HIO3

    NASA Astrophysics Data System (ADS)

    Sipilä, Mikko; Sarnela, Nina; Jokinen, Tuija; Henschel, Henning; Junninen, Heikki; Kontkanen, Jenni; Richters, Stefanie; Kangasluoma, Juha; Franchin, Alessandro; Peräkylä, Otso; Rissanen, Matti P.; Ehn, Mikael; Vehkamäki, Hanna; Kurten, Theo; Berndt, Torsten; Petäjä, Tuukka; Worsnop, Douglas; Ceburnis, Darius; Kerminen, Veli-Matti; Kulmala, Markku; O'Dowd, Colin

    2016-09-01

    Homogeneous nucleation and subsequent cluster growth leads to the formation of new aerosol particles in the atmosphere. The nucleation of sulfuric acid and organic vapours is thought to be responsible for the formation of new particles over continents, whereas iodine oxide vapours have been implicated in particle formation over coastal regions. The molecular clustering pathways that are involved in atmospheric particle formation have been elucidated in controlled laboratory studies of chemically simple systems, but direct molecular-level observations of nucleation in atmospheric field conditions that involve sulfuric acid, organic or iodine oxide vapours have yet to be reported. Here we present field data from Mace Head, Ireland, and supporting data from northern Greenland and Queen Maud Land, Antarctica, that enable us to identify the molecular steps involved in new particle formation in an iodine-rich, coastal atmospheric environment. We find that the formation and initial growth process is almost exclusively driven by iodine oxoacids and iodine oxide vapours, with average oxygen-to-iodine ratios of 2.4 found in the clusters. On the basis of this high ratio, together with the high concentrations of iodic acid (HIO3) observed, we suggest that cluster formation primarily proceeds by sequential addition of HIO3, followed by intracluster restructuring to I2O5 and recycling of water either in the atmosphere or on dehydration. Our study provides ambient atmospheric molecular-level observations of nucleation, supporting the previously suggested role of iodine-containing species in the formation of new aerosol particles, and identifies the key nucleating compound.

  13. Turbulent CO2 Flux Measurements by Lidar: Length Scales, Results and Comparison with In-Situ Sensors

    NASA Technical Reports Server (NTRS)

    Gilbert, Fabien; Koch, Grady J.; Beyon, Jeffrey Y.; Hilton, Timothy W.; Davis, Kenneth J.; Andrews, Arlyn; Ismail, Syed; Singh, Upendra N.

    2009-01-01

    The vertical CO2 flux in the atmospheric boundary layer (ABL) is investigated with a Doppler differential absorption lidar (DIAL). The instrument was operated next to the WLEF instrumented tall tower in Park Falls, Wisconsin during three days and nights in June 2007. Profiles of turbulent CO2 mixing ratio and vertical velocity fluctuations are measured by in-situ sensors and Doppler DIAL. Time and space scales of turbulence are precisely defined in the ABL. The eddy-covariance method is applied to calculate turbulent CO2 flux both by lidar and in-situ sensors. We show preliminary mean lidar CO2 flux measurements in the ABL with a time and space resolution of 6 h and 1500 m respectively. The flux instrumental errors decrease linearly with the standard deviation of the CO2 data, as expected. Although turbulent fluctuations of CO2 are negligible with respect to the mean (0.1 %), we show that the eddy-covariance method can provide 2-h, 150-m range resolved CO2 flux estimates as long as the CO2 mixing ratio instrumental error is no greater than 10 ppm and the vertical velocity error is lower than the natural fluctuations over a time resolution of 10 s.

  14. Characteristics of the residual stress tensor as a function of length scale in simulations of stably stratified turbulence

    NASA Astrophysics Data System (ADS)

    de Braganca Alves, Felipe Augusto; de Bruyn Kops, Stephen

    2015-11-01

    A priori analysis of the relationships between the deviatoric residual stress tensor τr and kinematic tensors is made for stably stratified Boussinesq turbulence. Two data sets from direct numerical simulation are used for the analyses: the decaying Taylor-Green simulations of Riley and de Bruyn Kops (2003), and the forced homogeneous stratified turbulence simulations of Almalkie and de Bruyn Kops (2012) resolved on up to 8192 × 8192 × 4096 grid points. The data sets are filtered using a Gaussian kernel with filter widths up to the buoyancy scale. Through tensor decomposition theorems described in Thompson et al. (2010) the relationship between the strain rate tensor and the residual stress is quantified for each filter width and case. This is also done for the tensor formed by the Lie product between the strain rate and rate of rotation tensors. The role of each tensor, seen as a part of the residual stress tensor, is analyzed, in particular with respect to filtered kinetic energy budget equation. The authors acknowledge the support from CAPES grant BEX 13649/13-2, DoD HPCMP Frontier Project FPCFD-FY14-007 and ONR grant N00014-15-1-2248.

  15. Mechanical characterization of Ti-6Al-4V titanium alloy at multiple length scales using spherical indentation stress-strain measurements

    DOE PAGES

    Weaver, Jordan S.; Kalidindi, Surya R.

    2016-09-05

    Recent advances in spherical indentation stress-strain protocols and analyses have demonstrated the capability for measuring reliably the local mechanical responses in polycrystalline metal samples at different length scales, ranging from sub-micron (regions within individual grains) to several hundreds of microns (regions covering several grains). These recent advances have now made it possible to study systematically the mechanical behavior of a single material system at different length scales, with tremendous potential to obtain new insights into the role of individual phases, interfaces, and other microscale constituents on the macroscale mechanical response of the material. In this paper, we report spherical indentationmore » stress-strain measurements with different indenter sizes (microns to millimeters) on Ti-6Al-4V (Ti-64) which capture the mechanical response of single phase alpha-Ti-64, single colony (alpha-beta), few colonies, and many colonies of Ti-64. The results show that the average mechanical response (indentation modulus and yield strength) from multiple indentations remains relatively unchanged from single phase alpha to many colonies of Ti-64, while the variance in the response decreases with indenter size. In conclusion, the work-hardening response in indentation tests follows a similar behavior up to indentation zones of many colonies, which shows significantly higher work hardening rates.« less

  16. A FIRST CONSTRAINT ON THE THICK DISK SCALE LENGTH: DIFFERENTIAL RADIAL ABUNDANCES IN K GIANTS AT GALACTOCENTRIC RADII 4, 8, AND 12 kpc

    SciTech Connect

    Bensby, T.; Alves-Brito, A.; Oey, M. S.; Yong, D.; Melendez, J.

    2011-07-10

    Based on high-resolution spectra obtained with the MIKE spectrograph on the Magellan telescopes, we present detailed elemental abundances for 20 red giant stars in the outer Galactic disk, located at Galactocentric distances between 9 and 13 kpc. The outer disk sample is complemented with samples of red giants from the inner Galactic disk and the solar neighborhood, analyzed using identical methods. For Galactocentric distances beyond 10 kpc, we only find chemical patterns associated with the local thin disk, even for stars far above the Galactic plane. Our results show that the relative densities of the thick and thin disks are dramatically different from the solar neighborhood, and we therefore suggest that the radial scale length of the thick disk is much shorter than that of the thin disk. We make a first estimate of the thick disk scale length of L{sub thick} = 2.0 kpc, assuming L{sub thin} = 3.8 kpc for the thin disk. We suggest that radial migration may explain the lack of radial age, metallicity, and abundance gradients in the thick disk, possibly also explaining the link between the thick disk and the metal-poor bulge.

  17. Micellization of dodecyltrimethylammonium bromide in water-dimethylsulfoxide mixtures: a multi-length scale approach in a model system.

    PubMed

    Peyre, Véronique; Bouguerra, Sabah; Testard, Fabienne

    2013-01-01

    The micellization in mixed solvent was studied using conductimetry, density measurements (molar volumes), and small angle neutron scattering (SANS) to explore dodecyltrimethylammonium bromide (DTABr) micelle formation throughout the entire composition range of water-dimethylsulfoxide (DMSO) mixtures. As the concentration of DMSO was increased in the mixture, the critical micelle concentration (CMC) increased, the aggregation number decreased and the ionization degree increased, until no aggregates could be detected any more for DMSO molar fraction higher than 0.51. The results were consistent with the presence of globular micelles interacting via a coulombic potential. The experimental CMC values and aggregation numbers were successfully reconciled with a molecular thermodynamic model describing the micellization process in solvent mixtures (R. Nagarajan and C.-C. Wang, Langmuir 16 (2000) 5242). The structural and thermodynamic characterization of the micelles agreed with the prediction of a dissymmetric solvation of the surfactant entity: the hydrocarbon chain was surrounded only by DMSO while the polar head was surrounded only by water. The decrease in the ionization degree was due to the condensation of the counterions and was definitely linked to the geometrical characteristics of the aggregates and by no means to the CMC or salinity. This multi-technique study provides new insight into the role of solvation in micellization and the reason for the decrease in ionization degree, emphasizing the dissymmetric solvation of the chain by DMSO and the head by water. This is the first time that, for a given surfactant in solvent mixtures, micellization is described using combined analysis from molecular to macroscopic scale.

  18. Investigating the reversibility of structural modifications of LixNiyMnzCo1-y-zO₂ cathode materials during initial charge/discharge, at multiple length scales

    DOE PAGES

    Hwang, Sooyeon; Bak, Seong -Min; Kim, Seung Min; Chung, Kyung Yoon; Chang, Wonyoung

    2015-08-11

    In this work, we investigate the structural modifications occurring at the bulk, subsurface, and surface scales of LixNiyMnzCo1-y-zO₂ (NMC; y, z = 0.8, 0.1 and 0.4, 0.3, respectively) cathode materials during the initial charge/discharge. Various analytical tools, such as X-ray diffraction, selected-area electron diffraction, electron energy-loss spectroscopy, and high-resolution electron microscopy, are used to examine the structural properties of the NMC cathode materials at the three different scales. Cut-off voltages of 4.3 and 4.8 V are applied during the electrochemical tests as the normal and extreme conditions, respectively. The high-Ni-content NMC cathode materials exhibit unusual behaviors, which is deviate frommore » the general redox reactions during the charge or discharge. The transition metal (TM) ions in the high-Ni-content NMC cathode materials, which are mostly Ni ions, are reduced at 4.8 V, even though TMs are usually oxidized to maintain charge neutrality upon the removal of Li. It was found that any changes in the crystallographic and electronic structures are mostly reversible down to the sub-surface scale, despite the unexpected reduction of Ni ions. However, after the discharge, traces of the phase transitions remain at the edges of the NMC cathode materials at the scale of a few nanometers (i.e., surface scale). This study demonstrates that the structural modifications in NMC cathode materials are induced by charge as well as discharge at multiple length scales. These changes are nearly reversible after the first cycle, except at the edges of the samples, which should be avoided because these highly localized changes can initiate battery degradation.« less

  19. A Direct Dynamical Measurement of the Milky Way's Disk Surface Density Profile, Disk Scale Length, and Dark Matter Profile at 4 kpc <~ R <~ 9 kpc

    NASA Astrophysics Data System (ADS)

    Bovy, Jo; Rix, Hans-Walter

    2013-12-01

    We present and apply rigorous dynamical modeling with which we infer unprecedented constraints on the stellar and dark matter mass distribution within our Milky Way (MW), based on large sets of phase-space data on individual stars. Specifically, we model the dynamics of 16,269 G-type dwarfs from SEGUE, which sample 5 kpc < RGC < 12 kpc and 0.3 kpc <~ |Z| <~ 3 kpc. We independently fit a parameterized MW potential and a three-integral, action-based distribution function (DF) to the phase-space data of 43 separate abundance-selected sub-populations (MAPs), accounting for the complex selection effects affecting the data. We robustly measure the total surface density within 1.1 kpc of the mid-plane to 5% over 4.5 kpc < RGC < 9 kpc. Using metal-poor MAPs with small radial scale lengths as dynamical tracers probes 4.5 kpc <~ RGC <~ 7 kpc, while MAPs with longer radial scale lengths sample 7 kpc <~ RGC <~ 9 kpc. We measure the mass-weighted Galactic disk scale length to be Rd = 2.15 ± 0.14 kpc, in agreement with the photometrically inferred spatial distribution of stellar mass. We thereby measure dynamically the mass of the Galactic stellar disk to unprecedented accuracy: M * = 4.6 ± 0.3 + 3.0 (R 0/ kpc - 8) × 1010 M ⊙ and a total local surface density of \\Sigma _{R_0}(Z=1.1\\,{kpc}) = 68\\, {+/- }\\, 4\\,M_\\odot \\,{pc}^{-2} of which 38 ± 4 M ⊙ pc-2 is contributed by stars and stellar remnants. By combining our surface density measurements with the terminal velocity curve, we find that the MW's disk is maximal in the sense that V c, disk/V c, total = 0.83 ± 0.04 at R = 2.2 Rd . We also constrain for the first time the radial profile of the dark halo at such small Galactocentric radii, finding that ρDM(r ≈R 0)vprop1/r α with α < 1.53 at 95% confidence. Our results show that action-based DF modeling of complex stellar data sets is now a feasible approach that will be fruitful for interpreting Gaia data.

  20. Evidence of Rapidly Warming Rivers in the UK from an Extensive Additive Modelling Study at the National Scale Using R

    NASA Astrophysics Data System (ADS)

    Simpson, G. L.

    2011-12-01

    River water temperature data exhibit non-linear behaviour over the past 50 or so years. Standard techniques for identifying and quantifying trends have centred around the use of linear regression and Mann-Kendall and Thiel-Sen procedures. Observational data from UK rivers suggest that temperatures are far more variable then assumed under these statistical models. In a national-scale assessment of the response of riverine systems to global climatic change, an additive model framework was employed to model patterns in water temperatures from a large database of temporal observational data. Models were developed using R, which allowed for the deployment of cutting-edge additive modelling techniques to describe trends at 2773 sites across England and Wales, UK. At a subset of sites, additive models were used to model long-term trends, trends within seasons and the long-term variation in the seasonal pattern of water temperatures. Changes in water temperature have important consequences for aquatic ecology, with some species being particularly sensitive even to small shifts in temperature during some or all of their lifecycle. While there are many studies reporting increasing regional and global air temperatures, evidence for changes in river water temperature has thus far been site specific and/or from sites heavily influenced by human activities that could themselves lead to warming. Here I present selected results from a national-scale assessment of changing river water temperatures, covering the whole of England and Wales, comprising data from 2,773 locations. Positive trends in water temperature were observed at 86% of sites. At a subset of sites, seasonal trend models were developed, which showed that 90% of locations demonstrated statistically significant increases in water temperature during Autumn and Winter periods. Multivariate smoothers, that allow for within-year and longer-term trend interactions in time, suggest that periods of warmer waters now extend

  1. Neandertal clavicle length

    PubMed Central

    Trinkaus, Erik; Holliday, Trenton W.; Auerbach, Benjamin M.

    2014-01-01

    The Late Pleistocene archaic humans from western Eurasia (the Neandertals) have been described for a century as exhibiting absolutely and relatively long clavicles. This aspect of their body proportions has been used to distinguish them from modern humans, invoked to account for other aspects of their anatomy and genetics, used in assessments of their phylogenetic polarities, and used as evidence for Late Pleistocene population relationships. However, it has been unclear whether the usual scaling of Neandertal clavicular lengths to their associated humeral lengths reflects long clavicles, short humeri, or both. Neandertal clavicle lengths, along with those of early modern humans and latitudinally diverse recent humans, were compared with both humeral lengths and estimated body masses (based on femoral head diameters). The Neandertal do have long clavicles relative their humeri, even though they fall within the ranges of variation of early and recent humans. However, when scaled to body masses, their humeral lengths are relatively short, and their clavicular lengths are indistinguishable from those of Late Pleistocene and recent modern humans. The few sufficiently complete Early Pleistocene Homo clavicles seem to have relative lengths also well within recent human variation. Therefore, appropriately scaled clavicular length seems to have varied little through the genus Homo, and it should not be used to account for other aspects of Neandertal biology or their phylogenetic status. PMID:24616525

  2. The connection between chromatin motion on the 100 nm length scale and core histone dynamics in live XTC-2 cells and isolated nuclei.

    PubMed

    Davis, Sara K; Bardeen, Christopher J

    2004-01-01

    The diffusive motion of DNA-containing chromatin in live cells and isolated nuclei is investigated using a two-photon standing wave fluorescence photobleaching experiment with 100 nm spatial resolution. The chromatin is labeled using the minor groove binding dye Hoechst 33342. In live cells, the mean diffusion rate is 5 x 10(-4) micro m2/s, with considerable cell-to-cell variation. This diffusion is highly constrained and cannot be observed in a standard, single beam fluorescence recovery after photobleaching experiment. To determine the chemical origin of the diffusion, we study motion in isolated nuclei and vary the strength of the histone-DNA interactions by changing the ionic strength and using chemical and photocross-linking experiments. At higher NaCl concentrations, we see increased chromatin diffusion as the histone-DNA interaction is weakened due to ionic screening, whereas photocross-linking the core histones to the DNA results in a complete absence of diffusive motion. These trends are consistent with the 100 nm scale motion being correlated with the interactions of histone proteins with the DNA. If chromatin diffusion is connected to the nucleosomal dynamics on much smaller length scales, this may provide a way to assay biochemical activity in vivo based on larger scale macromolecular dynamics observed via fluorescence microscopy.

  3. Large Scale Full-Length cDNA Sequencing Reveals a Unique Genomic Landscape in a Lepidopteran Model Insect, Bombyx mori

    PubMed Central

    Suetsugu, Yoshitaka; Futahashi, Ryo; Kanamori, Hiroyuki; Kadono-Okuda, Keiko; Sasanuma, Shun-ichi; Narukawa, Junko; Ajimura, Masahiro; Jouraku, Akiya; Namiki, Nobukazu; Shimomura, Michihiko; Sezutsu, Hideki; Osanai-Futahashi, Mizuko; Suzuki, Masataka G; Daimon, Takaaki; Shinoda, Tetsuro; Taniai, Kiyoko; Asaoka, Kiyoshi; Niwa, Ryusuke; Kawaoka, Shinpei; Katsuma, Susumu; Tamura, Toshiki; Noda, Hiroaki; Kasahara, Masahiro; Sugano, Sumio; Suzuki, Yutaka; Fujiwara, Haruhiko; Kataoka, Hiroshi; Arunkumar, Kallare P.; Tomar, Archana; Nagaraju, Javaregowda; Goldsmith, Marian R.; Feng, Qili; Xia, Qingyou; Yamamoto, Kimiko; Shimada, Toru; Mita, Kazuei

    2013-01-01

    The establishment of a complete genomic sequence of silkworm, the model species of Lepidoptera, laid a foundation for its functional genomics. A more complete annotation of the genome will benefit functional and comparative studies and accelerate extensive industrial applications for this insect. To realize these goals, we embarked upon a large-scale full-length cDNA collection from 21 full-length cDNA libraries derived from 14 tissues of the domesticated silkworm and performed full sequencing by primer walking for 11,104 full-length cDNAs. The large average intron size was 1904 bp, resulting from a high accumulation of transposons. Using gene models predicted by GLEAN and published mRNAs, we identified 16,823 gene loci on the silkworm genome assembly. Orthology analysis of 153 species, including 11 insects, revealed that among three Lepidoptera including Monarch and Heliconius butterflies, the 403 largest silkworm-specific genes were composed mainly of protective immunity, hormone-related, and characteristic structural proteins. Analysis of testis-/ovary-specific genes revealed distinctive features of sexual dimorphism, including depletion of ovary-specific genes on the Z chromosome in contrast to an enrichment of testis-specific genes. More than 40% of genes expressed in specific tissues mapped in tissue-specific chromosomal clusters. The newly obtained FL-cDNA sequences enabled us to annotate the genome of this lepidopteran model insect more accurately, enhancing genomic and functional studies of Lepidoptera and comparative analyses with other insect orders, and yielding new insights into the evolution and organization of lepidopteran-specific genes. PMID:23821615

  4. Large scale full-length cDNA sequencing reveals a unique genomic landscape in a lepidopteran model insect, Bombyx mori.

    PubMed

    Suetsugu, Yoshitaka; Futahashi, Ryo; Kanamori, Hiroyuki; Kadono-Okuda, Keiko; Sasanuma, Shun-ichi; Narukawa, Junko; Ajimura, Masahiro; Jouraku, Akiya; Namiki, Nobukazu; Shimomura, Michihiko; Sezutsu, Hideki; Osanai-Futahashi, Mizuko; Suzuki, Masataka G; Daimon, Takaaki; Shinoda, Tetsuro; Taniai, Kiyoko; Asaoka, Kiyoshi; Niwa, Ryusuke; Kawaoka, Shinpei; Katsuma, Susumu; Tamura, Toshiki; Noda, Hiroaki; Kasahara, Masahiro; Sugano, Sumio; Suzuki, Yutaka; Fujiwara, Haruhiko; Kataoka, Hiroshi; Arunkumar, Kallare P; Tomar, Archana; Nagaraju, Javaregowda; Goldsmith, Marian R; Feng, Qili; Xia, Qingyou; Yamamoto, Kimiko; Shimada, Toru; Mita, Kazuei

    2013-09-04

    The establishment of a complete genomic sequence of silkworm, the model species of Lepidoptera, laid a foundation for its functional genomics. A more complete annotation of the genome will benefit functional and comparative studies and accelerate extensive industrial applications for this insect. To realize these goals, we embarked upon a large-scale full-length cDNA collection from 21 full-length cDNA libraries derived from 14 tissues of the domesticated silkworm and performed full sequencing by primer walking for 11,104 full-length cDNAs. The large average intron size was 1904 bp, resulting from a high accumulation of transposons. Using gene models predicted by GLEAN and published mRNAs, we identified 16,823 gene loci on the silkworm genome assembly. Orthology analysis of 153 species, including 11 insects, revealed that among three Lepidoptera including Monarch and Heliconius butterflies, the 403 largest silkworm-specific genes were composed mainly of protective immunity, hormone-related, and characteristic structural proteins. Analysis of testis-/ovary-specific genes revealed distinctive features of sexual dimorphism, including depletion of ovary-specific genes on the Z chromosome in contrast to an enrichment of testis-specific genes. More than 40% of genes expressed in specific tissues mapped in tissue-specific chromosomal clusters. The newly obtained FL-cDNA sequences enabled us to annotate the genome of this lepidopteran model insect more accurately, enhancing genomic and functional studies of Lepidoptera and comparative analyses with other insect orders, and yielding new insights into the evolution and organization of lepidopteran-specific genes.

  5. Construct validity of the Schwartz outcome scale-10: comparisons to interpersonal distress, adult attachment, alexithymia, the five-factor model, romantic relationship length and ratings of childhood memories.

    PubMed

    Haggerty, Greg; Blake, Margaret; Naraine, Melissa; Siefert, Caleb; Blais, Mark A

    2010-01-01

    The Schwartz Outcome Scale-10 (SOS-10) is a 10-item questionnaire that measures the broad domain of psychological well-being and quality of life. The SOS-10 is easy to administer and score. Past research has shown its utility, reliability and validity in different clinical settings (i.e., inpatient, outpatient and non-psychiatry medical settings) and with diverse clinical populations in measuring treatment outcome. The present study looks to extend the construct validity of the SOS-10 to assessing quality of life and psychological health in non-clinical samples as well. The results reveal that the SOS-10 is associated in predicted ways with established measures of attachment, interpersonal distress, alexithymia and the big five model whose construct validity and psychometric soundness has been well documented. The SOS-10 was also associated in predicted ways with ratings of childhood memories and the length of the participants' longest romantic relationship.

  6. Saturation of the Two-Plasmon Decay Instability in Long-Scale-Length Plasmas Relevant to Direct-Drive Inertial Confinement Fusion

    SciTech Connect

    Froula, D. H.; Yaakobi, B.; Hu, S. X.; Chang, P-Y.; Craxton, R. S.; Edgell, D. H.; Follett, R.; Michel, D. T.; Myatt, J. F.; Seka, W.; Short, R. W.; Solodov, A.; Stoeckl, C.

    2012-04-01

    Measurements of the hot-electron generation by the two-plasmon-decay instability are made in plasmas relevant to direct-drive inertial confinement fusion. Density-scale lengths of 400 {micro}m at n{sub cr}/4 in planar CH targets allowed the two-plasmon-decay instability to be driven to saturation for vacuum intensities above ~3.5 x 10{sup 14} W cm{sup -2}. In the saturated regime, ~1% of the laser energy is converted to hot electrons. The hot-electron temperature is measured to increase rapidly from 25 to 90 keV as the laser beam intensity is increased from 2 to 7 x 10{sup 14} W cm{sup -2}. This increase in the hot-electron temperature is compared with predictions from nonlinear Zakharov models.

  7. Patterning at the 10 nanometer length scale using a strongly segregating block copolymer thin film and vapor phase infiltration of inorganic precursors

    NASA Astrophysics Data System (ADS)

    Choi, Jonathan W.; Li, Zhaodong; Black, Charles T.; Sweat, Daniel P.; Wang, Xudong; Gopalan, Padma

    2016-06-01

    In this work, we demonstrate the use of self-assembled thin films of the cylinder-forming block copolymer poly(4-tert-butylstyrene-block-2-vinylpyridine) to pattern high density features at the 10 nm length scale. This material's large interaction parameter facilitates pattern formation in single-digit nanometer dimensions. This block copolymer's accessible order-disorder transition temperature allows thermal annealing to drive the assembly of ordered 2-vinylpyridine cylinders that can be selectively complexed with the organometallic precursor trimethylaluminum. This unique chemistry converts organic 2-vinylpyridine cylinders into alumina nanowires with diameters ranging from 8 to 11 nm, depending on the copolymer molecular weight. Graphoepitaxy of this block copolymer aligns and registers sub-12 nm diameter nanowires to larger-scale rectangular, curved, and circular features patterned by optical lithography. The alumina nanowires function as a robust hard mask to withstand the conditions required for patterning the underlying silicon by plasma etching. We conclude with a discussion of some of the challenges that arise with using block copolymers for patterning at sub-10 nm feature sizes.In this work, we demonstrate the use of self-assembled thin films of the cylinder-forming block copolymer poly(4-tert-butylstyrene-block-2-vinylpyridine) to pattern high density features at the 10 nm length scale. This material's large interaction parameter facilitates pattern formation in single-digit nanometer dimensions. This block copolymer's accessible order-disorder transition temperature allows thermal annealing to drive the assembly of ordered 2-vinylpyridine cylinders that can be selectively complexed with the organometallic precursor trimethylaluminum. This unique chemistry converts organic 2-vinylpyridine cylinders into alumina nanowires with diameters ranging from 8 to 11 nm, depending on the copolymer molecular weight. Graphoepitaxy of this block copolymer aligns and

  8. Photocurable high internal phase emulsions (HIPEs) containing hydroxyapatite for additive manufacture of tissue engineering scaffolds with multi-scale porosity.

    PubMed

    Wang, Ai-Juan; Paterson, Thomas; Owen, Robert; Sherborne, Colin; Dugan, James; Li, Jun-Ming; Claeyssens, Frederik

    2016-10-01

    Porous composites containing hydroxyapatite (HA) were templated from high internal phase emulsions (HIPEs) and were further structured using direct-write UV stereolithography to produce composite scaffolds with multi-scale porosity. FTIR, TGA and SEM analyses confirmed that HA was retained after photocuring and subsequent treatments and was incorporated within the polymerised HIPE (polyHIPE). The addition of HA particles to the polyHIPE caused changes in the mechanical properties of the material. An increase in both the Young's modulus and maximum stress at yield was observed compared with the pure polyHIPE from 1.544±0.231 to 4.614±0.775 and 0.177±0.009 to 0.267±0.034MPa, respectively. Except at very high concentrations, adding HA did not adversely cause the phase separation of the HIPE or the porous microstructure of the resulting polyHIPE. In combination with a photoinitiator, the HIPE emulsion containing HA was investigated as a photocurable resin for stereolithography-based additive manufacturing. The material was readily processable into "woodpile" structures via direct-write UV stereolithography, producing scaffolds with multi-scale porosity which may be useful for medical applications such as tissue engineering. In conclusion, HA was successfully added into polyHIPEs, producing a similar porous structure to that of the pure polyHIPE whilst improving the mechanical performance. PMID:27287098

  9. Photocurable high internal phase emulsions (HIPEs) containing hydroxyapatite for additive manufacture of tissue engineering scaffolds with multi-scale porosity.

    PubMed

    Wang, Ai-Juan; Paterson, Thomas; Owen, Robert; Sherborne, Colin; Dugan, James; Li, Jun-Ming; Claeyssens, Frederik

    2016-10-01

    Porous composites containing hydroxyapatite (HA) were templated from high internal phase emulsions (HIPEs) and were further structured using direct-write UV stereolithography to produce composite scaffolds with multi-scale porosity. FTIR, TGA and SEM analyses confirmed that HA was retained after photocuring and subsequent treatments and was incorporated within the polymerised HIPE (polyHIPE). The addition of HA particles to the polyHIPE caused changes in the mechanical properties of the material. An increase in both the Young's modulus and maximum stress at yield was observed compared with the pure polyHIPE from 1.544±0.231 to 4.614±0.775 and 0.177±0.009 to 0.267±0.034MPa, respectively. Except at very high concentrations, adding HA did not adversely cause the phase separation of the HIPE or the porous microstructure of the resulting polyHIPE. In combination with a photoinitiator, the HIPE emulsion containing HA was investigated as a photocurable resin for stereolithography-based additive manufacturing. The material was readily processable into "woodpile" structures via direct-write UV stereolithography, producing scaffolds with multi-scale porosity which may be useful for medical applications such as tissue engineering. In conclusion, HA was successfully added into polyHIPEs, producing a similar porous structure to that of the pure polyHIPE whilst improving the mechanical performance.

  10. Additional Radiative Cooling of the Mesopause Region due to Small-Scale Temperature Fluctuations Associated with Gravity Waves

    NASA Astrophysics Data System (ADS)

    Kutepov, A.; Feofilov, A.; Medvedev, A.; Pauldrach, A.; Hartogh, P.

    2008-05-01

    We address a previously unknown effect of the radiative cooling of the mesosphere and lower thermosphere (MLT) produced by small-scale irregular temperature fluctuations (ITFs) associated with gravity waves. These disturbances are not resolved by present GCMs, but they alter the radiative transfer and the heating/cooling rates significantly. We apply a statistical model of gravity waves superimposed on large-scale temperature profiles, and perform direct calculations of the radiative cooling/heating in the MLT in the IR bands of CO2, O3 and H2O molecules taking into account the breakdown of the local thermodynamic equilibrium (non-LTE). We found that in the periods of strong wave activity the subgrid ITFs can cause an additional cooling up to 3 K/day near the mesopause. The effect is produced mainly by the fundamental 15 μm band of the main CO2 isotope. We derived a simple expression for the correction to mean (resolved by GCMs) temperature profiles using the variance of the temperature perturbations to account for the additional cooling effect. The suggested parameterization can be applied in GCMs in conjunction with existing gravity wave drag parameterizations.

  11. Load partitioning between the bcc-iron matrix and NiAl-type precipitates in a ferritic alloy on multiple length scales.

    PubMed

    Sun, Zhiqian; Song, Gian; Sisneros, Thomas A; Clausen, Bjørn; Pu, Chao; Li, Lin; Gao, Yanfei; Liaw, Peter K

    2016-01-01

    An understanding of load sharing among constituent phases aids in designing mechanical properties of multiphase materials. Here we investigate load partitioning between the body-centered-cubic iron matrix and NiAl-type precipitates in a ferritic alloy during uniaxial tensile tests at 364 and 506 °C on multiple length scales by in situ neutron diffraction and crystal plasticity finite element modeling. Our findings show that the macroscopic load-transfer efficiency is not as high as that predicted by the Eshelby model; moreover, it depends on the matrix strain-hardening behavior. We explain the grain-level anisotropic load-partitioning behavior by considering the plastic anisotropy of the matrix and elastic anisotropy of precipitates. We further demonstrate that the partitioned load on NiAl-type precipitates relaxes at 506 °C, most likely through thermally-activated dislocation rearrangement on the microscopic scale. The study contributes to further understanding of load-partitioning characteristics in multiphase materials. PMID:26979660

  12. Load partitioning between the bcc-iron matrix and NiAl-type precipitates in a ferritic alloy on multiple length scales

    DOE PAGES

    Sun, Zhiqian; Song, Gian; Sisneros, Thomas A.; Clausen, Bjorn; Pu, Chao; Li, Lin; Gao, Yanfei; Liaw, Peter K.

    2016-03-16

    An understanding of load sharing among constituent phases aids in designing mechanical properties of multiphase materials. Here we investigate load partitioning between the body-centered-cubic iron matrix and NiAl-type precipitates in a ferritic alloy during uniaxial tensile tests at 364 and 506 C on multiple length scales by in situ neutron diffraction and crystal plasticity finite element modeling. Our findings show that the macroscopic load-transfer efficiency is not as high as that predicted by the Eshelby model; moreover, it depends on the matrix strain-hardening behavior. We explain the grain-level anisotropic load-partitioning behavior by considering the plastic anisotropy of the matrix andmore » elastic anisotropy of precipitates. We further demonstrate that the partitioned load on NiAl-type precipitates relaxes at 506 C, most likely through thermally-activated dislocation rearrangement on the microscopic scale. Furthermore, the study contributes to further understanding of load-partitioning characteristics in multiphase materials.« less

  13. Load partitioning between the bcc-iron matrix and NiAl-type precipitates in a ferritic alloy on multiple length scales

    PubMed Central

    Sun, Zhiqian; Song, Gian; Sisneros, Thomas A.; Clausen, Bjørn; Pu, Chao; Li, Lin; Gao, Yanfei; Liaw, Peter K.

    2016-01-01

    An understanding of load sharing among constituent phases aids in designing mechanical properties of multiphase materials. Here we investigate load partitioning between the body-centered-cubic iron matrix and NiAl-type precipitates in a ferritic alloy during uniaxial tensile tests at 364 and 506 °C on multiple length scales by in situ neutron diffraction and crystal plasticity finite element modeling. Our findings show that the macroscopic load-transfer efficiency is not as high as that predicted by the Eshelby model; moreover, it depends on the matrix strain-hardening behavior. We explain the grain-level anisotropic load-partitioning behavior by considering the plastic anisotropy of the matrix and elastic anisotropy of precipitates. We further demonstrate that the partitioned load on NiAl-type precipitates relaxes at 506 °C, most likely through thermally-activated dislocation rearrangement on the microscopic scale. The study contributes to further understanding of load-partitioning characteristics in multiphase materials. PMID:26979660

  14. Load partitioning between the bcc-iron matrix and NiAl-type precipitates in a ferritic alloy on multiple length scales

    NASA Astrophysics Data System (ADS)

    Sun, Zhiqian; Song, Gian; Sisneros, Thomas A.; Clausen, Bjørn; Pu, Chao; Li, Lin; Gao, Yanfei; Liaw, Peter K.

    2016-03-01

    An understanding of load sharing among constituent phases aids in designing mechanical properties of multiphase materials. Here we investigate load partitioning between the body-centered-cubic iron matrix and NiAl-type precipitates in a ferritic alloy during uniaxial tensile tests at 364 and 506 °C on multiple length scales by in situ neutron diffraction and crystal plasticity finite element modeling. Our findings show that the macroscopic load-transfer efficiency is not as high as that predicted by the Eshelby model; moreover, it depends on the matrix strain-hardening behavior. We explain the grain-level anisotropic load-partitioning behavior by considering the plastic anisotropy of the matrix and elastic anisotropy of precipitates. We further demonstrate that the partitioned load on NiAl-type precipitates relaxes at 506 °C, most likely through thermally-activated dislocation rearrangement on the microscopic scale. The study contributes to further understanding of load-partitioning characteristics in multiphase materials.

  15. Crystal modification of iron oxide scale by potassium addition and its application to lithium-ion battery anodes

    NASA Astrophysics Data System (ADS)

    Jung, Dong-Won; Han, Sang-Wook; Kong, Byung-Seon; Oh, Eun-Suok

    2013-11-01

    This paper proposes a valuable method to reuse the iron oxide scale (IOS) often produced in the steel industry as an anode active material in lithium-ion batteries (LIBs). The IOS samples are prepared via quenching of carbon steel and simple oxidation at a high temperature with or without sequential treatment by potassium hydroxide. Morphological and physical characterizations confirm the formation of a lamellar structure of orthorhombic KFeO2 with a high degree of crystallinity in the potassium-added IOSs. Additionally, the potassium addition decreases the particle size of the crystals and increases the d-spacing between crystal layers. Electrochemical performance tests show that the discharge capacities of the IOS samples monotonically increased with increasing number of charge/discharge cycles regardless of the existence of potassium. In addition, the rate of increase is larger in the potassium-added IOS samples containing the lamellar KFeO2 structure. Consequently, after prolonged cycling (more than 500 cycles), the potassium-added IOS sample retains a discharge capacity of 1020 mAh g-1 with good cycling stability, while the IOS quenched sample only exhibits a capacity of 956 mAh g-1. This result is attributed to the unique structure of the KFeO2 crystals formed in the potassium-added IOS particles.

  16. Effect of ensiling time and exogenous protease addition to whole-plant corn silage of various hybrids, maturities, and chop lengths on nitrogen fractions and ruminal in vitro starch digestibility.

    PubMed

    Ferraretto, L F; Crump, P M; Shaver, R D

    2015-12-01

    The objective of this study was to evaluate the effects of ensiling time and exogenous protease addition on soluble CP (% of CP), ammonia-N (% of N), and ruminal in vitro starch digestibility (ivSD) of whole-plant corn silage (WPCS) from 3 hybrids, 2 maturities, and 2 chop lengths. Samples from 3 nonisogenic hybrids [brown midrib containing the bm3 gene mutation (BM3), dual-purpose (DP), or floury-leafy (LFY)] at 2 harvest maturities [2/3 kernel milk line (early) or 7d later (late)] with 2 theoretical lengths of cut settings (0.64 or 1.95cm) on a forage harvester were collected at harvest, treated with or without exogenous protease, and ensiled in triplicate in vacuum heat-sealed plastic bags for 0, 30, 60, 120, and 240d. Thus, the experiment consisted of 120 treatments (3 hybrids × 2 maturities × 2 chop lengths × 2 protease treatments × 5 time points) and 360 mini-silos (3 replications per treatment). Vitreousness, measured by dissection on unfermented kernels on the day of harvest, averaged 66.8, 65.0, and 59.0% for BM3, DP, and LFY, respectively. A protease × maturity interaction was observed with protease increasing ivSD in late but not early maturity. Ensiling time × hybrid interactions were observed for ammonia-N and soluble CP concentrations with greater values for FLY than other hybrids only after 120d of ensiling. Ensiling time × hybrid or protease × hybrid interactions were not observed for ivSD. Measurements of ivSD were greatest for FLY and lowest for BM3. Length of the ensiling period did not attenuate negative effects of kernel vitreousness or maturity on ivSD in WPCS. Results suggest that the dosage of exogenous protease addition used in the present study may reduce but not overcome the negative effects of maturity on ivSD in WPCS. No interactions between chop length and ensiling time or exogenous protease addition were observed for ivSD. PMID:26433421

  17. Hierarchical random additive process and logarithmic scaling of generalized high order, two-point correlations in turbulent boundary layer flow

    NASA Astrophysics Data System (ADS)

    Yang, X. I. A.; Marusic, I.; Meneveau, C.

    2016-06-01

    Townsend [Townsend, The Structure of Turbulent Shear Flow (Cambridge University Press, Cambridge, UK, 1976)] hypothesized that the logarithmic region in high-Reynolds-number wall-bounded flows consists of space-filling, self-similar attached eddies. Invoking this hypothesis, we express streamwise velocity fluctuations in the inertial layer in high-Reynolds-number wall-bounded flows as a hierarchical random additive process (HRAP): uz+=∑i=1Nzai . Here u is the streamwise velocity fluctuation, + indicates normalization in wall units, z is the wall normal distance, and ai's are independently, identically distributed random additives, each of which is associated with an attached eddy in the wall-attached hierarchy. The number of random additives is Nz˜ln(δ /z ) where δ is the boundary layer thickness and ln is natural log. Due to its simplified structure, such a process leads to predictions of the scaling behaviors for various turbulence statistics in the logarithmic layer. Besides reproducing known logarithmic scaling of moments, structure functions, and correlation function [" close="]3/2 uz(x ) uz(x +r ) >, new logarithmic laws in two-point statistics such as uz4(x ) > 1 /2, 1/3, etc. can be derived using the HRAP formalism. Supporting empirical evidence for the logarithmic scaling in such statistics is found from the Melbourne High Reynolds Number Boundary Layer Wind Tunnel measurements. We also show that, at high Reynolds numbers, the above mentioned new logarithmic laws can be derived by assuming the arrival of an attached eddy at a generic point in the flow field to be a Poisson process [Woodcock and Marusic, Phys. Fluids 27, 015104 (2015), 10.1063/1.4905301]. Taken together, the results provide new evidence supporting the essential ingredients of the attached eddy hypothesis to describe streamwise velocity fluctuations of large, momentum transporting eddies in wall-bounded turbulence, while

  18. PS-b-PEO/Silica Films with Regular and Reverse Mesostructures of Large Characteristic Length Scales Prepared by Solvent Evaporation-Induced Self-Assembly

    SciTech Connect

    YU,KUI; BRINKER,C. JEFFREY; HURD,ALAN J.; EISENBERG,ADI

    2000-11-22

    Since the discovery of surfactant-templated silica by Mobil scientists in 1992, mesostructured silica has been synthesized in various forms including thin films, powders, particles, and fibers. In general, mesostructured silica has potential applications, such as in separation, catalysis, sensors, and fluidic microsystems. In respect to these potential applications, mesostructured silica in the form of thin films is perhaps one of the most promising candidates. The preparation of mesostructured silica films through preferential solvent evaporation-induced self-assembly (EISA) has recently received much attention in the laboratories. However, no amphiphile/silica films with reverse mesophases have ever been made through this EISA procedure. Furthermore, templates employed to date have been either surfactants or poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymers, such as pluronic P-123, both of which are water-soluble and alcohol-soluble. Due to their relatively low molecular weight, the templated silica films with mesoscopic order have been limited to relatively small characteristic length scales. In the present communication, the authors report a novel synthetic method to prepare mesostructured amphiphilic/silica films with regular and reverse mesophases of large characteristic length scales. This method involves evaporation-induced self-assembly (EISA) of amphiphilic polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymers. In the present study, the PS-b-PEO diblocks are denoted as, for example, PS(215)-b-PEO(100), showing that this particular sample contains 215 S repeat units and 100 EO repeat units. This PS(215)-b-PEO(100) diblock possesses high molecular weight and does not directly mix with water or alcohol. To the authors knowledge, no studies have reported the use of water-insoluble and alcohol-insoluble amphiphilic diblocks as structure-directing agents in the synthesis of mesostructured silica films through

  19. Large-scale Manufacturing of Nanoparticulate-based Lubrication Additives for Improved Energy Efficiency and Reduced Emissions

    SciTech Connect

    Erdemir, Ali

    2013-09-26

    This project was funded under the Department of Energy (DOE) Lab Call on Nanomanufacturing for Energy Efficiency and was directed toward the development of novel boron-based nanocolloidal lubrication additives for improving the friction and wear performance of machine components in a wide range of industrial and transportation applications. Argonne's research team concentrated on the scientific and technical aspects of the project, using a range of state-of-the art analytical and tribological test facilities. Argonne has extensive past experience and expertise in working with boron-based solid and liquid lubrication additives, and has intellectual property ownership of several. There were two industrial collaborators in this project: Ashland Oil (represented by its Valvoline subsidiary) and Primet Precision Materials, Inc. (a leading nanomaterials company). There was also a sub-contract with the University of Arkansas. The major objectives of the project were to develop novel boron-based nanocolloidal lubrication additives and to optimize and verify their performance under boundary-lubricated sliding conditions. The project also tackled problems related to colloidal dispersion, larger-scale manufacturing and blending of nano-additives with base carrier oils. Other important issues dealt with in the project were determination of the optimum size and concentration of the particles and compatibility with various base fluids and/or additives. Boron-based particulate additives considered in this project included boric acid (H{sub 3}BO{sub 3}), hexagonal boron nitride (h-BN), boron oxide, and borax. As part of this project, we also explored a hybrid MoS{sub 2} + boric acid formulation approach for more effective lubrication and reported the results. The major motivation behind this work was to reduce energy losses related to friction and wear in a wide spectrum of mechanical systems and thereby reduce our dependence on imported oil. Growing concern over greenhouse gas

  20. The seasonal and solar cycle variations of electron density gradient scale length, vertical drift and layer height during magnetically quiet days: Implications for Spread F over Trivandrum, India

    NASA Astrophysics Data System (ADS)

    Manju, G.; Devasia, C. V.; Ravindran, S.

    2009-12-01

    A study has been carried out on the behaviour of electron density gradient scale length, L, vertical drift and layer height, around post sunset hours, during the magnetically quiet days of summer, winter and equinox seasons of solar maximum (2002) and minimum years (1995), using ionosonde data of Trivandrum (8.5°N, 76.5°E, dip = 0.5°N) in the Indian longitude sector. The results indicate a clear seasonal and solar cycle variation in all the three parameters. Further, the seasonal variation of equatorial Spread F (ESF) during the above period is examined in terms of the relative roles of L, the vertical drift and layer height (of the F layer) in the triggering of the collisional Rayleigh-Taylor instability. The results, show for the first time, that L also plays an important role, in controlling the quiet time seasonal and solar cycle variability of ESF; whereas in earlier studies this parameter had been taken to be constant. The detailed results are presented and discussed.

  1. Derivation of effective fission gas diffusivities in UO2 from lower length scale simulations and implementation of fission gas diffusion models in BISON

    SciTech Connect

    Andersson, Anders David Ragnar; Pastore, Giovanni; Liu, Xiang-Yang; Perriot, Romain Thibault; Tonks, Michael; Stanek, Christopher Richard

    2014-11-07

    This report summarizes the development of new fission gas diffusion models from lower length scale simulations and assessment of these models in terms of annealing experiments and fission gas release simulations using the BISON fuel performance code. Based on the mechanisms established from density functional theory (DFT) and empirical potential calculations, continuum models for diffusion of xenon (Xe) in UO2 were derived for both intrinsic conditions and under irradiation. The importance of the large XeU3O cluster (a Xe atom in a uranium + oxygen vacancy trap site with two bound uranium vacancies) is emphasized, which is a consequence of its high mobility and stability. These models were implemented in the MARMOT phase field code, which is used to calculate effective Xe diffusivities for various irradiation conditions. The effective diffusivities were used in BISON to calculate fission gas release for a number of test cases. The results are assessed against experimental data and future directions for research are outlined based on the conclusions.

  2. Multi-Length Scale-Enriched Continuum-Level Material Model for Kevlar®-Fiber-Reinforced Polymer-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Pandurangan, B.; Snipes, J. S.; Yen, C.-F.; Cheeseman, B. A.

    2013-03-01

    Fiber-reinforced polymer matrix composite materials display quite complex deformation and failure behavior under ballistic/blast impact loading conditions. This complexity is generally attributed to a number of factors such as (a) hierarchical/multi-length scale architecture of the material microstructure; (b) nonlinear, rate-dependent and often pressure-sensitive mechanical response; and (c) the interplay of various intrinsic phenomena and processes such as fiber twisting, interfiber friction/sliding, etc. Material models currently employed in the computational engineering analyses of ballistic/blast impact protective structures made of this type of material do not generally include many of the aforementioned aspects of the material dynamic behavior. Consequently, discrepancies are often observed between computational predictions and their experimental counterparts. To address this problem, the results of an extensive set of molecular-level computational analyses regarding the role of various microstructural/morphological defects on the Kevlar® fiber mechanical properties are used to upgrade one of the existing continuum-level material models for fiber-reinforced composites. The results obtained show that the response of the material is significantly affected as a result of the incorporation of microstructural effects both under quasi-static simple mechanical testing condition and under dynamic ballistic-impact conditions.

  3. Investigation of the structure of human dental tissue at multiple length scales using high energy synchrotron X-ray SAXS/WAXS

    NASA Astrophysics Data System (ADS)

    Sui, Tan; Landini, Gabriel; Korsunsky, Alexander M.

    2011-10-01

    High energy (>50keV) synchrotron X-ray scattering experiments were carried out on beamline I12 JEEP at the Diamond Light Source (DLS, Oxford, UK). Although a complete human tooth could be studied, in the present study attention was focused on coupons from the region of the Dentin-Enamel Junction (DEJ). Simultaneous high energy SAXS/WAXS measurements were carried out. Quantitative analysis of the results allows multiple length scale characterization of the nano-crystalline structure of dental tissues. SAXS patterns analysis provide insight into the mean thickness and orientation of hydroxyapatite particles, while WAXS (XRD) patterns allow the determination of the crystallographic unit cell parameters of the hydroxyapatite phase. It was found that the average particle thickness determined from SAXS interpretation varies as a function of position in the vicinity of the DEJ. Most mineral particles are randomly orientated within dentin, although preferred orientation emerges and becomes stronger on approach to the enamel. Within the enamel, texture is stronger than anywhere in the dentin, and the determination of lattice parameters can be accomplished by Pawley refinement of the multiple peak diffraction pattern. The results demonstrate the feasibility of using high energy synchrotron X-ray beams for the characterization of human dental tissues. This opens up the opportunity of studying thick samples (e.g., complete teeth) in complex sample environments (e.g., under saline solution). This opens new avenues for the application of high energy synchrotron X-ray scattering to dental research.

  4. Field-scale investigation of enhanced petroleum hydrocarbon biodegradation in the vadose zone combining soil venting as an oxygen source with moisture and nutrient addition. Appendices. Doctoral thesis

    SciTech Connect

    Miller, R.N.

    1990-01-01

    This document contains appendices regarding a reprint on a field scale investigation of enhanced petroleum hydrocarbon biodegradation in the vadose zone combining soil venting as a oxygen source with moisture and nutrient addition.

  5. PILOT-SCALE STUDIES ON THE EFFECT OF BROMINE ADDITION ON THE EMISSIONS OF CHLORINATED ORGANIC COMBUSTION BY-PRODUCTS

    EPA Science Inventory

    The paper reports on a study to evaluate organic combustion by-product emissions while feeding varying amounts of bromine (Br) and chlorine (Cl) into a pilot-scale incinerator burning surrogate waste materials. (NOTE: Adding brominated organic compounds to a pilot-scale incinerat...

  6. Flue gas conditioning for improved particle collection in electrostatic precipitators. Second topical report, Results of bench-scale screening of additives

    SciTech Connect

    Durham, M.D.

    1993-08-13

    ADA Technologies, Inc. (ADA) has completed the bench-scale testing phase of a program to evaluate additives that will improve the collection of fine particles in electrostatic precipitators (ESPs). A bench-scale ESP was installed at the Consolidation Coal Company (CONSOL) combustion research and development facility in Library, PA in order to conduct the evaluation. During a two-week test, four candidate additives were injected into the flue gas ahead of a 100 acfm ESP to determine the effect on fly ash collectability. Two additives were found to reduce the emissions from the ESP. Additives ``C`` and ``D`` performed better than initially anticipated -- reducing emissions initially by 17%. Emissions were reduced by 27% after the ESP was modified by the installation of baffles to minimize sneakage. In addition to the measured improvements in performance, no detrimental effects (i.e., electrode fouling) were observed in the operation of the ESP during the testing. The measures of success identified for the bench-scale phase of the program have been surpassed. Since the additives will affect only non-rapping reentrainment particle losses, it is expected that an even greater improvement in particle collection will be observed in larger-scale ESPs. Therefore, positive results are anticipated during the pilot-scale phase of the program and during a future full-scale demonstration test. A preliminary economic analysis was performed to evaluate the cost of the additive process and to compare its costs against alternative means for reducing emissions from ESPs. The results show that conditioning with additive C at a rate of 0.05% (wt. additive to wt. fly ash) is much less expensive than adding new ESP capacity, and more cost competitive than existing chemical conditioning processes. Preliminary chemical analysis of conditioned fly ash shows that it passes the Toxicity Characteristic Leaching Procedure criteria.

  7. Sorbitol dehydrogenase. Full-length cDNA sequencing reveals a mRNA coding for a protein containing an additional 42 amino acids at the N-terminal end.

    PubMed

    Wen, Y; Bekhor, I

    1993-10-01

    A cDNA clone encoding rat sorbitol dehydrogenase (SDH) was isolated from a rat testis lambda ZAP II cDNA library. The full-length cDNA insert contained 2277 base pairs (bp), starting 182 bp upstream from an ATG codon where translation to the active enzyme SDH is presumed to be initiated. A second ATG codon, however, was found 126 bp upstream, aligned in the same reading frame as that of the active enzyme. Therefore, the coding sequence for SDH can be translated into an additional 42-amino-acid polypeptide linked to the N-terminal amino acid of the enzyme, generating a pre-sorbitol dehydrogenase. The sequence data indicate that the nucleotide environment around this ATG codon is more favorable towards it being the actual open reading frame (ORF) for a pre-SDH than the ATG codon preceding the nucleotide sequence for SDH. Since no known SDH starts with the additional 42 amino acids, it may be that post-translational removal of this polypeptide accompanies the release of the active enzyme. Next, the 3' untranslated region of the cDNA contained a non-coding 1021 bp downstream from the TAA stop codon. The latter sequence included three putative poly(A) signals: one at nucleotides 1362-1367, the second at nucleotides 1465-1470, and the third at nucleotides 2212-2217 [17 bp away from the poly(A) tail]. In addition to the above findings we also report a variance in one of the amino acids in the SDH cDNA sequence. This variance occurs at position 957-960, where threonine is coded for instead of aspartic acid; in the rat testis SDH cDNA, we find the sequence is ACG instead of GAC, as was reported for the rat liver SDH cDNA. Northern-blot hybridization analysis showed that SDH mRNA is a doublet, one band of 4 kb and the other of 2.3-2.4 kb, in both the rat liver and the rat lens, further confirming that the isolated SDH cDNA constituted a full-length cDNA.

  8. Are Dietary Restraint Scales Valid Measures of Dietary Restriction? Additional Objective Behavioral and Biological Data Suggest Not

    PubMed Central

    Stice, Eric; Sysko, Robyn; Roberto, Christina A.; Allison, Shelley

    2009-01-01

    Prospective studies find that individuals with elevated dietary restraint scores are at increased risk for bulimic symptom onset, yet experiments find that assignment to energy-deficit diet interventions reduce bulimic symptoms. One explanation for the conflicting findings is that the dietary restraint scales used in the former studies do not actually identify individuals who are restraining their caloric intake. Thus, we tested whether dietary restraint scales showed inverse relations to objectively measured caloric intake in three studies. Four dietary restraint scales did not correlate with doubly labeled water estimates of caloric intake over a 2-week period (M r = .01). One scale showed a significant inverse correlation with objectively measured caloric intake during a regular meal ordered from an ecologically valid menu (M r = −.30), but a significant positive relation that was qualified by a significant quadratic effect, to objectively measured caloric intake during multiple eating episodes in the lab (M r = .32). In balance, results suggest that dietary restraint scales are not valid measures of dietary restriction, replicating findings from prior studies that examined objective measures of caloric intake. PMID:20006662

  9. Large-scale collection and analysis of full-length cDNAs from Brachypodium distachyon and integration with Pooideae sequence resources.

    PubMed

    Mochida, Keiichi; Uehara-Yamaguchi, Yukiko; Takahashi, Fuminori; Yoshida, Takuhiro; Sakurai, Tetsuya; Shinozaki, Kazuo

    2013-01-01

    A comprehensive collection of full-length cDNAs is essential for correct structural gene annotation and functional analyses of genes. We constructed a mixed full-length cDNA library from 21 different tissues of Brachypodium distachyon Bd21, and obtained 78,163 high quality expressed sequence tags (ESTs) from both ends of ca. 40,000 clones (including 16,079 contigs). We updated gene structure annotations of Brachypodium genes based on full-length cDNA sequences in comparison with the latest publicly available annotations. About 10,000 non-redundant gene models were supported by full-length cDNAs; ca. 6,000 showed some transcription unit modifications. We also found ca. 580 novel gene models, including 362 newly identified in Bd21. Using the updated transcription start sites, we searched a total of 580 plant cis-motifs in the -3 kb promoter regions and determined a genome-wide Brachypodium promoter architecture. Furthermore, we integrated the Brachypodium full-length cDNAs and updated gene structures with available sequence resources in wheat and barley in a web-accessible database, the RIKEN Brachypodium FL cDNA database. The database represents a "one-stop" information resource for all genomic information in the Pooideae, facilitating functional analysis of genes in this model grass plant and seamless knowledge transfer to the Triticeae crops.

  10. The Study of the Tether Motion with Time-Varying Length Using the Absolute Nodal Coordinate Formulation with Multiple Nonlinear Time Scales

    NASA Astrophysics Data System (ADS)

    Kawaguti, Keisuke; Terumichi, Yoshiaki; Takehara, Shoichiro; Kaczmarczyk, Stefan; Sogabe, Kiyoshi

    In this study, the modeling and formulation for tether motion with time-varying length, large rotation, large displacement and large deformation are proposed. A tether or cable is an important element in lift systems, construction machines for transportation and often is used with a time-varying length. In some cases, these systems are large and the tether has a long length, large deformation and large displacement. The dynamic behavior of a tether in extension and retraction using the proposed method is discussed in this paper. In the passage through resonance, significant tether motions with large rotation and large deformation result. In the analysis of this phenomenon, the transient fluctuations of the motion amplitudes are examined and compared with the corresponding steady state motions. The accuracy and the cost of the calculations are also verified by comparison with the experimental results.

  11. Teachers' Awareness and Use of Scales to Map the Progress of Children Who Speak English as an Additional Language or Dialect

    ERIC Educational Resources Information Center

    de Courcy, Michele; Adoniou, Misty; Ngoc, Doan Ba

    2014-01-01

    With the development of the English as an Additional Language or Dialect (EAL/D) Teacher Resource, the educational needs and outcomes of refugee and immigrant children have been placed on the national mainstream teaching agenda. This new national resource sits alongside a plethora of other resources, known as scales and standards, which have been…

  12. Sequence-structure correlations in silk: Poly-Ala repeat of N. clavipes MaSp1 is naturally optimized at a critical length scale.

    PubMed

    Bratzel, Graham; Buehler, Markus J

    2012-03-01

    Spider silk is a self-assembling biopolymer that outperforms many known materials in terms of its mechanical performance despite being constructed from simple and inferior building blocks. While experimental studies have shown that the molecular structure of silk has a direct influence on the stiffness, toughness, and failure strength of silk, few molecular-level analyses of the nanostructure of silk assemblies in particular under variations of genetic sequences have been reported. Here we report atomistic-level structures of the MaSp1 protein from the Nephila Clavipes spider dragline silk sequence, obtained using an in silico approach based on replica exchange molecular dynamics (REMD) and explicit water molecular dynamics. We apply this method to study the effects of a systematic variation of the poly-alanine repeat lengths, a parameter controlled by the genetic makeup of silk, on the resulting molecular structure of silk at the nanoscale. Confirming earlier experimental and computational work, a structural analysis reveals that poly-alanine regions in silk predominantly form distinct and orderly β-sheet crystal domains while disorderly regions are formed by glycine-rich repeats that consist of 3(10)-helix type structures and β-turns. Our predictions are directly validated against experimental data based on dihedral angle pair calculations presented in Ramachandran plots combined with an analysis of the secondary structure content. The key result of our study is our finding of a strong dependence of the resulting silk nanostructure depending on the poly-alanine length. We observe that the wildtype poly-alanine repeat length of six residues defines a critical minimum length that consistently results in clearly defined β-sheet nanocrystals. For poly-alanine lengths below six, the β-sheet nanocrystals are not well-defined or not visible at all, while for poly-alanine lengths at and above six, the characteristic nanocomposite structure of silk emerges with no

  13. Sequence-structure correlations in silk: Poly-Ala repeat of N. clavipes MaSp1 is naturally optimized at a critical length scale.

    PubMed

    Bratzel, Graham; Buehler, Markus J

    2012-03-01

    Spider silk is a self-assembling biopolymer that outperforms many known materials in terms of its mechanical performance despite being constructed from simple and inferior building blocks. While experimental studies have shown that the molecular structure of silk has a direct influence on the stiffness, toughness, and failure strength of silk, few molecular-level analyses of the nanostructure of silk assemblies in particular under variations of genetic sequences have been reported. Here we report atomistic-level structures of the MaSp1 protein from the Nephila Clavipes spider dragline silk sequence, obtained using an in silico approach based on replica exchange molecular dynamics (REMD) and explicit water molecular dynamics. We apply this method to study the effects of a systematic variation of the poly-alanine repeat lengths, a parameter controlled by the genetic makeup of silk, on the resulting molecular structure of silk at the nanoscale. Confirming earlier experimental and computational work, a structural analysis reveals that poly-alanine regions in silk predominantly form distinct and orderly β-sheet crystal domains while disorderly regions are formed by glycine-rich repeats that consist of 3(10)-helix type structures and β-turns. Our predictions are directly validated against experimental data based on dihedral angle pair calculations presented in Ramachandran plots combined with an analysis of the secondary structure content. The key result of our study is our finding of a strong dependence of the resulting silk nanostructure depending on the poly-alanine length. We observe that the wildtype poly-alanine repeat length of six residues defines a critical minimum length that consistently results in clearly defined β-sheet nanocrystals. For poly-alanine lengths below six, the β-sheet nanocrystals are not well-defined or not visible at all, while for poly-alanine lengths at and above six, the characteristic nanocomposite structure of silk emerges with no

  14. Neurotoxin formation from pilot-scale incineration of synthetic ester turbine lubricants with a triaryl phosphate additive.

    PubMed

    Rubey, W A; Striebich, R C; Bush, J; Centers, P W; Wright, R L

    1996-01-01

    The high-temperature combustion of synthetic ester turbine engine lubricants has been performed by diluting the lubricant 5, 15, or 25% in diesel fuel and burning the mixture in a pilot-scale boiler facility. The effluent gas from this combustion system was carefully monitored for the formation of a potent neurotoxin, trimethylolpropane phosphate (TMPP). Although TMPP was not detected in the gaseous effluent, elevated levels of the neurotoxin were found in scrapings from the inside of the boiler system. Because of the extreme toxicity of this compound, significant dermal exposure could be a potential risk to incinerator operation and maintenance personnel. PMID:8783815

  15. Neurotoxin formation from pilot-scale incineration of synthetic ester turbine lubricants with a triaryl phosphate additive.

    PubMed

    Rubey, W A; Striebich, R C; Bush, J; Centers, P W; Wright, R L

    1996-01-01

    The high-temperature combustion of synthetic ester turbine engine lubricants has been performed by diluting the lubricant 5, 15, or 25% in diesel fuel and burning the mixture in a pilot-scale boiler facility. The effluent gas from this combustion system was carefully monitored for the formation of a potent neurotoxin, trimethylolpropane phosphate (TMPP). Although TMPP was not detected in the gaseous effluent, elevated levels of the neurotoxin were found in scrapings from the inside of the boiler system. Because of the extreme toxicity of this compound, significant dermal exposure could be a potential risk to incinerator operation and maintenance personnel.

  16. Large-scale identification and characterization of alternative splicing variants of human gene transcripts using 56 419 completely sequenced and manually annotated full-length cDNAs

    PubMed Central

    Takeda, Jun-ichi; Suzuki, Yutaka; Nakao, Mitsuteru; Barrero, Roberto A.; Koyanagi, Kanako O.; Jin, Lihua; Motono, Chie; Hata, Hiroko; Isogai, Takao; Nagai, Keiichi; Otsuki, Tetsuji; Kuryshev, Vladimir; Shionyu, Masafumi; Yura, Kei; Go, Mitiko; Thierry-Mieg, Jean; Thierry-Mieg, Danielle; Wiemann, Stefan; Nomura, Nobuo; Sugano, Sumio; Gojobori, Takashi; Imanishi, Tadashi

    2006-01-01

    We report the first genome-wide identification and characterization of alternative splicing in human gene transcripts based on analysis of the full-length cDNAs. Applying both manual and computational analyses for 56 419 completely sequenced and precisely annotated full-length cDNAs selected for the H-Invitational human transcriptome annotation meetings, we identified 6877 alternative splicing genes with 18 297 different alternative splicing variants. A total of 37 670 exons were involved in these alternative splicing events. The encoded protein sequences were affected in 6005 of the 6877 genes. Notably, alternative splicing affected protein motifs in 3015 genes, subcellular localizations in 2982 genes and transmembrane domains in 1348 genes. We also identified interesting patterns of alternative splicing, in which two distinct genes seemed to be bridged, nested or having overlapping protein coding sequences (CDSs) of different reading frames (multiple CDS). In these cases, completely unrelated proteins are encoded by a single locus. Genome-wide annotations of alternative splicing, relying on full-length cDNAs, should lay firm groundwork for exploring in detail the diversification of protein function, which is mediated by the fast expanding universe of alternative splicing variants. PMID:16914452

  17. Water reuse: >90% water yield in MBR/RO through concentrate recycling and CO2 addition as scaling control.

    PubMed

    Joss, Adriano; Baenninger, Claudia; Foa, Paolo; Koepke, Stephan; Krauss, Martin; McArdell, Christa S; Rottermann, Karin; Wei, Yuansong; Zapata, Ana; Siegrist, Hansruedi

    2011-11-15

    Over 1.5 years continuous piloting of a municipal wastewater plant upgraded with a double membrane system (ca. 0.6 m(3) d(-1) of product water produced) have demonstrated the feasibility of achieving high water quality with a water yield of 90% by combining a membrane bioreactor (MBR) with a submerged ultrafiltration membrane followed by a reverse osmosis membrane (RO). The novelty of the proposed treatment scheme consists of the appropriate conditioning of MBR effluent prior to the RO and in recycling the RO concentrates back to the biological unit. All the 15 pharmaceuticals measured in the influent municipal sewage were retained below 100 ng L(-1), a proposed quality parameter, and mostly below detection limits of 10 ng L(-1). The mass balance of the micropollutants shows that these are either degraded or discharged with the excess concentrate, while only minor quantities were found in the excess sludge. The micropollutant load in the concentrate can be significantly reduced by ozonation. A low treated water salinity (<10 mM inorganic salts; 280 ± 70 μS cm(-1)) also confirms that the resulting product has a high water quality. Solids precipitation and inorganic scaling are effectively mitigated by lowering the pH in the RO feed water with CO(2) conditioning, while the concentrate from the RO is recycled to the biological unit where CO(2) is stripped by aeration. This causes precipitation to occur in the bioreactor bulk, where it is much less of a process issue. SiO(2) is the sole exception. Equilibrium modeling of precipitation reactions confirms the effectiveness of this scaling-mitigation approach for CaCO(3) precipitation, calcium phosphate and sulfate minerals.

  18. Water reuse: >90% water yield in MBR/RO through concentrate recycling and CO2 addition as scaling control.

    PubMed

    Joss, Adriano; Baenninger, Claudia; Foa, Paolo; Koepke, Stephan; Krauss, Martin; McArdell, Christa S; Rottermann, Karin; Wei, Yuansong; Zapata, Ana; Siegrist, Hansruedi

    2011-11-15

    Over 1.5 years continuous piloting of a municipal wastewater plant upgraded with a double membrane system (ca. 0.6 m(3) d(-1) of product water produced) have demonstrated the feasibility of achieving high water quality with a water yield of 90% by combining a membrane bioreactor (MBR) with a submerged ultrafiltration membrane followed by a reverse osmosis membrane (RO). The novelty of the proposed treatment scheme consists of the appropriate conditioning of MBR effluent prior to the RO and in recycling the RO concentrates back to the biological unit. All the 15 pharmaceuticals measured in the influent municipal sewage were retained below 100 ng L(-1), a proposed quality parameter, and mostly below detection limits of 10 ng L(-1). The mass balance of the micropollutants shows that these are either degraded or discharged with the excess concentrate, while only minor quantities were found in the excess sludge. The micropollutant load in the concentrate can be significantly reduced by ozonation. A low treated water salinity (<10 mM inorganic salts; 280 ± 70 μS cm(-1)) also confirms that the resulting product has a high water quality. Solids precipitation and inorganic scaling are effectively mitigated by lowering the pH in the RO feed water with CO(2) conditioning, while the concentrate from the RO is recycled to the biological unit where CO(2) is stripped by aeration. This causes precipitation to occur in the bioreactor bulk, where it is much less of a process issue. SiO(2) is the sole exception. Equilibrium modeling of precipitation reactions confirms the effectiveness of this scaling-mitigation approach for CaCO(3) precipitation, calcium phosphate and sulfate minerals. PMID:21959090

  19. Scales

    MedlinePlus

    Scales are a visible peeling or flaking of outer skin layers. These layers are called the stratum ... Scales may be caused by dry skin, certain inflammatory skin conditions, or infections. Eczema , ringworm , and psoriasis ...

  20. World's largest coseismic strike-slip offset: The 1855 rupture of the Wairarapa Fault, New Zealand, and implications for displacement/length scaling of continental earthquakes

    NASA Astrophysics Data System (ADS)

    Rodgers, D. W.; Little, T. A.

    2006-12-01

    We used detailed microtopographic surveys to measure fault offset along the southern trace of the Wairarapa fault, near Wellington, New Zealand, which most recently experienced a Mw > 8.1 earthquake in 1855. Our measurements at 16 localities support the inference that dextral slip in 1855 reached 18.7 m and averaged ˜16 m over the 16 km length that we studied. Five measurements were made where a single active strand comprises the fault zone, yielding "smallest" dextral offsets of 13.0-18.7 m. At Pigeon Bush, sequential beheading of a stream and new 14C dating support the interpretation that its 18.7 ± 1.0 m of offset accumulated in 1855. We also measured three "next-smallest" offsets on single-strand faults of 26.3-32.7 m, evidence that dextral slip during the previous event was ˜14 m. Eight measurements were made where the Wairarapa fault includes two closely spaced strands, yielding smallest dextral offsets of 12.9-16.0 m. At Tauherenikau River, 14C dating of postoffset mud yielded ages indistinguishable from A.D. 1855. Combining all single-strand and two-strand (minimum) estimates yields an average dextral slip of 15.5 ± 1.4 m in the study area. Historical observations and our data indicate that vertical slip reached ˜2.5 m. The large displacement and short (˜145 km) strike length yield an unusually high displacement/length ratio for the rupture. As suggested by previous dislocation modeling, we propose that the rupture extended tens of kilometers downdip (W) to merge with the underlying subduction interface. Alternatively, the rupture may have been strongly segmented at depth, yielding an earthquake with an unusually large static stress drop.

  1. An Efficient Multi-Scale Simulation Architecture for the Prediction of Performance Metrics of Parts Fabricated Using Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Pal, Deepankar; Patil, Nachiket; Zeng, Kai; Teng, Chong; Stucker, Brent

    2015-09-01

    In this study, an overview of the computational tools developed in the area of metal-based additively manufactured (AM) to simulate the performance metrics along with their experimental validations will be presented. The performance metrics of the AM fabricated parts such as the inter- and intra-layer strengths could be characterized in terms of the melt pool dimensions, solidification times, cooling rates, granular microstructure, and phase morphologies along with defect distributions which are a function of the energy source, scan pattern(s), and the material(s). The four major areas of AM simulation included in this study are thermo-mechanical constitutive relationships during fabrication and in- service, the use of Euler angles for gaging static and dynamic strengths, the use of algorithms involving intelligent use of matrix algebra and homogenization extracting the spatiotemporal nature of these processes, a fast GPU architecture, and specific challenges targeted toward attaining a faster than real-time simulation efficiency and accuracy.

  2. Large-scale analysis of full-length cDNAs from the tomato (Solanum lycopersicum) cultivar Micro-Tom, a reference system for the Solanaceae genomics

    PubMed Central

    2010-01-01

    Background The Solanaceae family includes several economically important vegetable crops. The tomato (Solanum lycopersicum) is regarded as a model plant of the Solanaceae family. Recently, a number of tomato resources have been developed in parallel with the ongoing tomato genome sequencing project. In particular, a miniature cultivar, Micro-Tom, is regarded as a model system in tomato genomics, and a number of genomics resources in the Micro-Tom-background, such as ESTs and mutagenized lines, have been established by an international alliance. Results To accelerate the progress in tomato genomics, we developed a collection of fully-sequenced 13,227 Micro-Tom full-length cDNAs. By checking redundant sequences, coding sequences, and chimeric sequences, a set of 11,502 non-redundant full-length cDNAs (nrFLcDNAs) was generated. Analysis of untranslated regions demonstrated that tomato has longer 5'- and 3'-untranslated regions than most other plants but rice. Classification of functions of proteins predicted from the coding sequences demonstrated that nrFLcDNAs covered a broad range of functions. A comparison of nrFLcDNAs with genes of sixteen plants facilitated the identification of tomato genes that are not found in other plants, most of which did not have known protein domains. Mapping of the nrFLcDNAs onto currently available tomato genome sequences facilitated prediction of exon-intron structure. Introns of tomato genes were longer than those of Arabidopsis and rice. According to a comparison of exon sequences between the nrFLcDNAs and the tomato genome sequences, the frequency of nucleotide mismatch in exons between Micro-Tom and the genome-sequencing cultivar (Heinz 1706) was estimated to be 0.061%. Conclusion The collection of Micro-Tom nrFLcDNAs generated in this study will serve as a valuable genomic tool for plant biologists to bridge the gap between basic and applied studies. The nrFLcDNA sequences will help annotation of the tomato whole-genome sequence

  3. Chemical characteristics of beddings for swine: effects of bedding depths and of addition of inoculums in a pilot-scale.

    PubMed

    Corrêa, E K; Corezzolla, J L; Corrêa, M N; Bianchi, I; Gil-Turnes, C; Lucia, T

    2012-11-01

    The effect of depths and of addition of inoculums on the chemical content of swine beddings was evaluated. For beddings 0.25m (25D) and 0.50m (50D) deep, three treatments were tested in two repeats with the same beddings: control (no inoculums); T1 (250g of Bacillus cereus var. toyoii at 8.4×10(7)CFU/g); and T2 (250g of a pool of Bacillus sp. at 8.4×10(7)CFU/g) (250g for 25D and 500g for 50D). For 25D, the C:N ratio was lower, but N, K and C contents were greater than for 50D (P<0.05). The inoculums did not benefit any chemical parameter (P>0.05). In the second repeat, beddings presented lower C:N ratio and greater N, P and K contents than in the first repeat (P<0.05). Thus, the compost produced after using 25D twice had greater fertilizer value than that of 50D.

  4. Addition of Bacillus sp. inoculums in bedding for swine on a pilot scale: effect on microbial population and bedding temperature.

    PubMed

    Corrêa, E K; Ulguim, R R; Corrêa, L B; Castilhos, D D; Bianchi, I; Gil-Turnes, C; Lucia, T

    2012-10-01

    Thermal and microbiological characteristics of beddings for swine were compared according to their depth and of addition of inoculums. Bedding was added to boxes at 0.25 (25D) and 0.50 m (50D), with three treatments: control (no inoculums); T1, with 250 g of Bacillus cereus var. toyoii at 8.4 × 10(7) CFU; and T2, with 250 g of a pool of B. subtilis, Bacillus licheniformis and Bacillus polymyxa at 8.4 × 10(7) CFU (250 g for 25D and 500 g for 50D). Mean temperatures were 28.5 ± 3.9 at the surface and 35.2 ± 8.9 inside the beddings. The most probable number (MPN) of thermophilic bacteria was higher for T1 and T2 than for the control (P<0.05). The MPN of thermophilic bacteria and fungi was greater for D50 than for D25 (P<0.05). The use of 25D without inoculums is recommended due to the reduction of thermophilic microbiota.

  5. Genomic-scale comparison of sequence- and structure-based methods of function prediction: Does structure provide additional insight?

    PubMed Central

    Fetrow, Jacquelyn S.; Siew, Naomi; Di Gennaro, Jeannine A.; Martinez-Yamout, Maria; Dyson, H. Jane; Skolnick, Jeffrey

    2001-01-01

    A function annotation method using the sequence-to-structure-to-function paradigm is applied to the identification of all disulfide oxidoreductases in the Saccharomyces cerevisiae genome. The method identifies 27 sequences as potential disulfide oxidoreductases. All previously known thioredoxins, glutaredoxins, and disulfide isomerases are correctly identified. Three of the 27 predictions are probable false-positives. Three novel predictions, which subsequently have been experimentally validated, are presented. Two additional novel predictions suggest a disulfide oxidoreductase regulatory mechanism for two subunits (OST3 and OST6) of the yeast oligosaccharyltransferase complex. Based on homology, this prediction can be extended to a potential tumor suppressor gene, N33, in humans, whose biochemical function was not previously known. Attempts to obtain a folded, active N33 construct to test the prediction were unsuccessful. The results show that structure prediction coupled with biochemically relevant structural motifs is a powerful method for the function annotation of genome sequences and can provide more detailed, robust predictions than function prediction methods that rely on sequence comparison alone. PMID:11316881

  6. Generation and analysis of a large-scale expressed sequence tags from a full-length enriched cDNA library of Siberian tiger (Panthera tigris altaica).

    PubMed

    Guo, Yu; Liu, Changqing; Lu, Taofeng; Liu, Dan; Bai, Chunyu; Li, Xiangchen; Ma, Yuehui; Guan, Weijun

    2014-05-15

    In this study, a full-length enriched cDNA library was successfully constructed from Siberian tiger, the world's most endangered species. The titers of primary and amplified libraries were 1.28×10(6)pfu/mL and 1.59×10(10)pfu/mL respectively. The proportion of recombinants from unamplified library was 91.3% and the average length of exogenous inserts was 1.06kb. A total of 279 individual ESTs with sizes ranging from 316 to 1258bps were then analyzed. Furthermore, 204 unigenes were successfully annotated and involved in 49 functions of the GO classification, cell (175, 85.5%), cellular process (165, 80.9%), and binding (152, 74.5%) are the dominant terms. 198 unigenes were assigned to 156 KEGG pathways, and the pathways with the most representation are metabolic pathways (18, 9.1%). The proportion pattern of each COG subcategory was similar among Panthera tigris altaica, P. tigris tigris and Homo sapiens, and general function prediction only cluster (44, 15.8%) represents the largest group, followed by translation, ribosomal structure and biogenesis (33, 11.8%), replication, recombination and repair (24, 8.6%), and only 7.2% ESTs classified as novel genes. Moreover, the recombinant plasmid pET32a-TAT-COL6A2 was constructed, coded for the Trx-TAT-COL6A2 fusion protein with two 6× His-tags in N and C-terminal. After BCA assay, the concentration of soluble Trx-TAT-COL6A2 recombinant protein was 2.64±0.18mg/mL. This library will provide a useful platform for the functional genome and transcriptome research of for the P. tigris and other felid animals in the future.

  7. Generation and analysis of a large-scale expressed sequence tags from a full-length enriched cDNA library of Siberian tiger (Panthera tigris altaica).

    PubMed

    Guo, Yu; Liu, Changqing; Lu, Taofeng; Liu, Dan; Bai, Chunyu; Li, Xiangchen; Ma, Yuehui; Guan, Weijun

    2014-05-15

    In this study, a full-length enriched cDNA library was successfully constructed from Siberian tiger, the world's most endangered species. The titers of primary and amplified libraries were 1.28×10(6)pfu/mL and 1.59×10(10)pfu/mL respectively. The proportion of recombinants from unamplified library was 91.3% and the average length of exogenous inserts was 1.06kb. A total of 279 individual ESTs with sizes ranging from 316 to 1258bps were then analyzed. Furthermore, 204 unigenes were successfully annotated and involved in 49 functions of the GO classification, cell (175, 85.5%), cellular process (165, 80.9%), and binding (152, 74.5%) are the dominant terms. 198 unigenes were assigned to 156 KEGG pathways, and the pathways with the most representation are metabolic pathways (18, 9.1%). The proportion pattern of each COG subcategory was similar among Panthera tigris altaica, P. tigris tigris and Homo sapiens, and general function prediction only cluster (44, 15.8%) represents the largest group, followed by translation, ribosomal structure and biogenesis (33, 11.8%), replication, recombination and repair (24, 8.6%), and only 7.2% ESTs classified as novel genes. Moreover, the recombinant plasmid pET32a-TAT-COL6A2 was constructed, coded for the Trx-TAT-COL6A2 fusion protein with two 6× His-tags in N and C-terminal. After BCA assay, the concentration of soluble Trx-TAT-COL6A2 recombinant protein was 2.64±0.18mg/mL. This library will provide a useful platform for the functional genome and transcriptome research of for the P. tigris and other felid animals in the future. PMID:24630959

  8. Effect of red mud addition on tetracycline and copper resistance genes and microbial community during the full scale swine manure composting.

    PubMed

    Wang, Rui; Zhang, Junya; Sui, Qianwen; Wan, Hefeng; Tong, Juan; Chen, Meixue; Wei, Yuansong; Wei, Dongbin

    2016-09-01

    Swine manure has been considered as the reservoir of antibiotic resistance genes (ARGs). Composting is one of the most suitable technologies for treating livestock manures, and red mud was proved to have a positive effect on nitrogen conservation during composting. This study investigated the abundance of eight tetracycline and three copper resistance genes, the bacterial community during the full scale swine manure composting with or without addition of red mud. The results showed that ARGs in swine manure could be effectively removed through composting (reduced by 2.4log copies/g TS), especially during the thermophilic phase (reduced by 1.5log copies/g TS), which the main contributor might be temperature. Additionally, evolution of bacterial community could also have a great influence on ARGs. Although addition of red mud could enhance nitrogen conservation, it obviously hindered removal of ARGs (reduced by 1.7log copies/g TS) and affected shaping of bacterial community during composting.

  9. A two-dimensional analysis of the sensitivity of a pulse first break to wave speed contrast on a scale below the resolution length of ray tomography.

    PubMed

    Willey, Carson L; Simonetti, Francesco

    2016-06-01

    Mapping the speed of mechanical waves traveling inside a medium is a topic of great interest across many fields from geoscience to medical diagnostics. Much work has been done to characterize the fidelity with which the geometrical features of the medium can be reconstructed and multiple resolution criteria have been proposed depending on the wave-matter interaction model used to decode the wave speed map from scattering measurements. However, these criteria do not define the accuracy with which the wave speed values can be reconstructed. Using two-dimensional simulations, it is shown that the first-arrival traveltime predicted by ray theory can be an accurate representation of the arrival of a pulse first break even in the presence of diffraction and other phenomena that are not accounted for by ray theory. As a result, ray-based tomographic inversions can yield accurate wave speed estimations also when the size of a sound speed anomaly is smaller than the resolution length of the inversion method provided that traveltimes are estimated from the signal first break. This increased sensitivity however renders the inversion more susceptible to noise since the amplitude of the signal around the first break is typically low especially when three-dimensional anomalies are considered. PMID:27369139

  10. Extracting Length and Time Scales of Downstream Suspended Transport from Sediment Budget Data: ~100 to 1000-yr Travel Times from the Appalachians to the Chesapeake Bay, U.S.A

    NASA Astrophysics Data System (ADS)

    Pizzuto, J. E.; Schenk, E.; Hupp, C. R.; Gellis, A.; Noe, G. B.; Williamson, E.; Karwan, D. L.; O'Neal, M. A.; Marquard, J.; Aalto, R. E.; Newbold, J. D.

    2013-12-01

    Watershed Best Management Practices (BMPs) are often designed to reduce loadings of sediments and particle-borne contaminants, but the temporal lag between BMP implementation and improvement in receiving water quality is difficult to assess because particles spend long periods in storage between transport events. Here we present a theory that describes the downstream movement of suspended sediment particles accounting for the time particles spend in storage based on sediment budget data (by grain-size fraction) and information on particle transit times through storage reservoirs. The theory is used to define a suspended-sediment transport-length scale that describes how far particles are carried during transport events, and to estimate a downstream particle velocity that includes time spent in storage. At five upland watersheds of the mid-Atlantic region of the U.S.A., transport-length scales for silt-clay range from 3.5-76.1 km, while those for sand range from 0.9-139.6 km. Stratigraphic data and radiometric dating for a typical eroding bank section suggest an averaged sediment transit time through floodplain storage of 488 years. Mean sediment velocities for silt-clay range from 0.0072-0.16 km/yr, while those for sand range from 0.0008-0.25 km/yr, 4 to 6 orders of magnitude slower than the velocity of water in the channel. These results suggest lag times of 100-1000 years between BMP implementation and effectiveness in receiving waters such as the Chesapeake Bay (where BMPs are located upstream of the characteristic transport length scale). Many particles likely travel much faster than these average values, so further research is needed to define the range and distribution of transport rates within and across particle sizes.

  11. Impact of the addition of chicken litter on mercury speciation and emissions from coal combustion in a laboratory-scale fluidized bed combustor

    SciTech Connect

    Songgeng Li; Shuang Deng; Andy Wu; Wei-ping Pan

    2008-07-15

    Co-combustion of chicken litter with coal was performed in a laboratory-scale fluidized bed combustor to investigate the effect of chicken litter addition on the partitioning behavior of mercury. Gaseous total and elemental mercury concentrations in the flue gas were measured online, and ash was analyzed for particle-bound mercury along with other elemental and surface properties. The mercury mass balance was between 85 and 105%. The experimental results show that co-combustion of chicken litter decreases the amount of elemental and total mercury in the gas phase. Mercury content in fly ash increases with an increasing chicken litter share. 22 refs., 6 figs., 5 tabs.

  12. Lipid membrane expansion and micelle formation by polymer-grafted lipids: scaling with polymer length studied by spin-label electron spin resonance.

    PubMed Central

    Montesano, G; Bartucci, R; Belsito, S; Marsh, D; Sportelli, L

    2001-01-01

    Spin-label electron spin resonance (ESR) spectroscopy and auxiliary optical density measurements are used to study lipid dispersions of N-poly(ethylene glycol)-dipalmitoyl phosphatidylethanolamine (PEG:5000-DPPE) mixed with dipalmitoyl phosphatidylcholine (DPPC). PEG:5000-DPPE bears a large hydrophilic polymer headgroup (with approximately 114 oxyethylene monomers) and is commonly used for steric stabilization of liposomes used in drug delivery. Comparison is made with results from mixtures of DPPC with polymer lipids bearing shorter headgroups (approximately 45 and 8 oxyethylene monomers). ESR spectra of phosphatidylcholine spin-labeled on the 5-C atom position of the sn-2 chain are shown to reflect the area expansion of the lipid membranes by the lateral pressure exerted in the polymer brush, in a way that is consistent with theory. The lipid chain packing density at the onset of micelle formation is the same for all three PEG-lipids, although the mole fraction at which this occurs differs greatly. The mole fraction at onset scales inversely with the size of the polymer headgroup, where the experimental exponent of 0.7 is close to theoretical predictions (viz. 0.55-0.6). The mole fraction of PEG-lipid at completion of micelle formation is more weakly dependent on polymer size, which conforms with theoretical predictions. At high mole fractions of PEG:5000-DPPE the dependence of lipid packing density on mole fraction is multiphasic, which differs qualitatively from the monotonic decrease in packing density found with the shorter polymer lipids. Lipid spin-label ESR is an experimental tool that complements theoretical analysis using polymer models combined with the lipid equation of state. PMID:11222298

  13. Investigating the reversibility of structural modifications of LixNiyMnzCo1-y-zO₂ cathode materials during initial charge/discharge, at multiple length scales

    SciTech Connect

    Hwang, Sooyeon; Bak, Seong -Min; Kim, Seung Min; Chung, Kyung Yoon; Chang, Wonyoung

    2015-08-11

    In this work, we investigate the structural modifications occurring at the bulk, subsurface, and surface scales of LixNiyMnzCo1-y-zO₂ (NMC; y, z = 0.8, 0.1 and 0.4, 0.3, respectively) cathode materials during the initial charge/discharge. Various analytical tools, such as X-ray diffraction, selected-area electron diffraction, electron energy-loss spectroscopy, and high-resolution electron microscopy, are used to examine the structural properties of the NMC cathode materials at the three different scales. Cut-off voltages of 4.3 and 4.8 V are applied during the electrochemical tests as the normal and extreme conditions, respectively. The high-Ni-content NMC cathode materials exhibit unusual behaviors, which is deviate from the general redox reactions during the charge or discharge. The transition metal (TM) ions in the high-Ni-content NMC cathode materials, which are mostly Ni ions, are reduced at 4.8 V, even though TMs are usually oxidized to maintain charge neutrality upon the removal of Li. It was found that any changes in the crystallographic and electronic structures are mostly reversible down to the sub-surface scale, despite the unexpected reduction of Ni ions. However, after the discharge, traces of the phase transitions remain at the edges of the NMC cathode materials at the scale of a few nanometers (i.e., surface scale). This study demonstrates that the structural modifications in NMC cathode materials are induced by charge as well as discharge at multiple length scales. These changes are nearly reversible after the first cycle, except at the edges of the samples, which should be avoided because these highly localized changes can initiate battery degradation.

  14. Scale

    ERIC Educational Resources Information Center

    Schaffhauser, Dian

    2009-01-01

    The common approach to scaling, according to Christopher Dede, a professor of learning technologies at the Harvard Graduate School of Education, is to jump in and say, "Let's go out and find more money, recruit more participants, hire more people. Let's just keep doing the same thing, bigger and bigger." That, he observes, "tends to fail, and fail…

  15. The relative diffusive transport rate of SrI2 in water changes over the nanometer length scale as measured by coherent quasielastic neutron scattering.

    PubMed

    Rubinson, Kenneth A; Faraone, Antonio

    2016-05-14

    X-ray and neutron scattering have been used to provide insight into the structures of ionic solutions for over a century, but the probes have covered distances shorter than 8 Å. For the non-hydrolyzing salt SrI2 in aqueous solution, a locally ordered lattice of ions exists that scatters slow neutrons coherently down to at least 0.1 mol L(-1) concentration, where the measured average distance between scatterers is over 18 Å. To investigate the motions of these scatterers, coherent quasielastic neutron scattering (CQENS) data on D2O solutions with SrI2 at 1, 0.8, 0.6, and 0.4 mol L(-1) concentrations was obtained to provide an experimental measure of the diffusive transport rate for the motion between pairs of ions relative to each other. Because CQENS measures the motion of one ion relative to another, the frame of reference is centered on an ion, which is unique among all diffusion measurement methods. We call the measured quantity the pairwise diffusive transport rate Dp. In addition to this ion centered frame of reference, the diffusive transport rate can be measured as a function of the momentum transfer q, where q = (4π/λ)sin θ with a scattering angle of 2θ. Since q is related to the interion distance (d = 2π/q), for the experimental range 0.2 Å(-1)≤q≤ 1.0 Å(-1), Dp is, then, measured over interion distances from 40 Å to ≈6 Å. We find the measured diffusional transport rates increase with increasing distance between scatterers over the entire range covered and interpret this behavior to be caused by dynamic coupling among the ions. Within the model of Fickian diffusion, at the longer interionic distances Dp is greater than the Nernst-Hartley value for an infinitely dilute solution. For these nm-distance diffusional transport rates to conform with the lower, macroscopically measured diffusion coefficients, we propose that local, coordinated counter motion of at least pairs of ions is part of the transport process. PMID:27096293

  16. Symmetry of piezoelectric (1–x)Pb(Mg1/3Nb2/3)O₃-xPbTiO₃ (x=0.31) single crystal at different length scales in the morphotropic phase boundary region

    DOE PAGES

    Kim, Kyou-Hyun; Payne, David A.; Zuo, Jian-Min

    2012-11-29

    We use probes of three different length scales to examine symmetry of (1–x)Pb(Mg1/3Nb2/3)O₃-xPbTiO₃ (PMN-xPT) single crystals in the morphotropic phase boundary (MPB) region at composition x = 0.31 (PMN-31% PT). On the macroscopic scale, x-ray diffraction (XRD) shows a mixture of strong and weak diffraction peaks of different widths. The closest match to XRD peak data is made with monoclinic Pm (MC) symmetry. On the local scale of a few nanometers, convergent beam electron diffraction (CBED) studies, with a 1.6-nm electron probe, reveal no obvious symmetry. These CBED experimental patterns can be approximately matched with simulations based on monoclinic symmetry,more » which suggests locally distorted monoclinic structure. A monoclinic Cm (MA or MB)-like symmetry could also be obtained from certain regions of the crystal by using a larger electron probe size of several tens of nanometers in diameter. Thus the monoclinic symmetry of single crystal PMN-31%PT is developed only in parts of the crystal by averaging over locally distorted structure on the scale of few tens of nanometers. The macroscopic symmetry observed by XRD is a result of averaging from the local structure in PMN-31%PT single crystal. The lack of local symmetry at a few nanometers scale suggests that the polarization switching results from a change in local displacements, which are not restricted to specific symmetry planes or directions.« less

  17. Effects of inorganic nitrogen (NH₄Cl) and biodegradable organic carbon (CH₃COONa) additions on a pilot-scale seawater biofilter.

    PubMed

    Xavier Simon, F; Rudé, Elisabet; Berdalet, Elisa; Llorens, Joan; Baig, Sylvie

    2013-05-01

    Biofilters degrade a small fraction of the natural organic matter (NOM) contained in seawater which is the leading cause of biofouling in downstream processes. This work studies the effects of chemical additions on NOM biodegradation by biofilters. In this work, biofiltration of seawater with an empty bed contact time (EBCT) of 6 min and a hydraulic loading rate of 10 mh(-1) reduces the biological oxygen demand (BOD7) by 8%, the dissolved organic carbon (DOC) by 6% and the UV absorbance at 254 nm (A₂₅₄) by 7%. Different amounts of ammonium chloride are added to the seawater (up to twice the total dissolved nitrogen in untreated seawater) to study its possible effect on the removal of NOM by a pilot-scale biofilter. Seawater is amended with different amounts of easily biodegradable dissolved organic carbon (BDOC) supplied as sodium acetate (up to twice the DOC) for the same purpose. The results of this work reveal that the ammonium chloride additions do not significantly affect NOM removal and the sodium acetate is completely consumed by the biofiltration process. For both types of chemical additions, the BOD₇, DOC and A₂₅₄ in the outlet stream of the biofilter are similar to the values for the untreated control. These results indicate that this biofilter easily removes the BDOC from the seawater when the EBCT is not above 6 min. Furthermore, nitrogen does not limit the NOM biodegradation in seawater under these experimental conditions. PMID:23522031

  18. Scales

    SciTech Connect

    Murray Gibson

    2007-04-27

    Musical scales involve notes that, sounded simultaneously (chords), sound good together. The result is the left brain meeting the right brain — a Pythagorean interval of overlapping notes. This synergy would suggest less difference between the working of the right brain and the left brain than common wisdom would dictate. The pleasing sound of harmony comes when two notes share a common harmonic, meaning that their frequencies are in simple integer ratios, such as 3/2 (G/C) or 5/4 (E/C).

  19. Scales

    ScienceCinema

    Murray Gibson

    2016-07-12

    Musical scales involve notes that, sounded simultaneously (chords), sound good together. The result is the left brain meeting the right brain — a Pythagorean interval of overlapping notes. This synergy would suggest less difference between the working of the right brain and the left brain than common wisdom would dictate. The pleasing sound of harmony comes when two notes share a common harmonic, meaning that their frequencies are in simple integer ratios, such as 3/2 (G/C) or 5/4 (E/C).

  20. Chromosome length scaling in haploid, asexual reproduction

    NASA Astrophysics Data System (ADS)

    de Oliveira, P. M. C.

    2007-02-01

    We study the genetic behaviour of a population formed by haploid individuals which reproduce asexually. The genetic information for each individual is stored along a bit-string (or chromosome) with L bits, where 0-bits represent the wild allele and 1-bits correspond to harmful mutations. Each newborn inherits this chromosome from its parent with a few random mutations: on average a fixed number m of bits are flipped. Selection is implemented according to the number N of 1-bits counted along the individual's chromosome: the smaller N the higher the probability an individual has to survive a new time step. Such a population evolves, with births and deaths, and its genetic distribution becomes stabilized after sufficiently many generations have passed. The question we pose concerns the procedure of increasing L. The aim is to get the same distribution of genetic loads N/L among the equilibrated population, in spite of a larger L. Should we keep the same mutation rate m/L for different values of L? The answer is yes, which intuitively seems to be plausible. However, this conclusion is not trivial, according to our simulation results: the question also involves the population size.

  1. Measuring Thermodynamic Length

    SciTech Connect

    Crooks, Gavin E

    2007-09-07

    Thermodynamic length is a metric distance between equilibrium thermodynamic states. Among other interesting properties, this metric asymptotically bounds the dissipation induced by a finite time transformation of a thermodynamic system. It is also connected to the Jensen-Shannon divergence, Fisher information, and Rao's entropy differential metric. Therefore, thermodynamic length is of central interestin understanding matter out of equilibrium. In this Letter, we will consider how to denethermodynamic length for a small system described by equilibrium statistical mechanics and how to measure thermodynamic length within a computer simulation. Surprisingly, Bennett's classic acceptance ratio method for measuring free energy differences also measures thermodynamic length.

  2. NMR Measures of Heterogeneity Length

    NASA Astrophysics Data System (ADS)

    Spiess, Hans W.

    2002-03-01

    Advanced solid state NMR spectroscopy provides a wealth of information about structure and dynamics of complex systems. On a local scale, multidimensional solid state NMR has elucidated the geometry and the time scale of segmental motions at the glass transition. The higher order correlation functions which are provided by this technique led to the notion of dynamic heterogeneities, which have been characterized in detail with respect to their rate memory and length scale. In polymeric and low molar mass glass formers of different fragility, length scales in the range 2 to 4 nm are observed. In polymeric systems, incompatibility of backbone and side groups as in polyalkylmethacrylates leads to heteogeneities on the nm scale, which manifest themselves in unusual chain dynamics at the glass transition involving extended chain conformations. References: K. Schmidt-Rohr and H.W. Spiess, Multidimensional Solid-State NMR and Polymers,Academic Press, London (1994). U. Tracht, M. Wilhelm, A. Heuer, H. Feng, K. Schmidt-Rohr, H.W. Spiess, Phys. Rev. Lett. 81, 2727 (1998). S.A. Reinsberg, X.H. Qiu, M. Wilhelm, M.D. Ediger, H.W. Spiess, J.Chem.Phys. 114, 7299 (2001). S.A. Reinsberg, A. Heuer, B. Doliwa, H. Zimmermann, H.W. Spiess, J. Non-Crystal. Solids, in press (2002)

  3. Reaction and transport in debonded wellbore casing-cement interfaces under CO2 storage conditions: From batch reaction tests to flow-through experiments on the 2m length scale

    NASA Astrophysics Data System (ADS)

    Wolterbeek, Tim; Peach, Colin; Spiers, Chris

    2014-05-01

    . Ongoing changes in the temperature and stress state could lead these defects to propagate and connect, possibly resulting in a long-range pathway. Our second set of experiments is currently ongoing and addresses how such interconnected debonding-defects are affected by long-range chemical reaction and transport under flow-through conditions. Cement slurry was poured into a coil made of steel tube and was subsequently cured at 80°C. After curing, debonding was promoted by causing the steel tube to lift off the cement, providing us with a sample that contains a 2 m long section of (partially) debonded cement-steel interface. A flow-through permeameter, maintained at 80°C, will be used to one-sidedly flood the coil with CO2-bearing fluid, while continuously measuring sample permeability and pump/fluid volume (indicative for extent of reaction). Post-experiment microstructural analysis will be performed on the coil. To our knowledge, this will be the first experimental investigation of the cement-steel interface that includes reactive transport phenomena that occur on the metre length scale.

  4. Microbial community and removal of nitrogen via the addition of a carrier in a pilot-scale duckweed-based wastewater treatment system.

    PubMed

    Zhao, Yonggui; Fang, Yang; Jin, Yanling; Huang, Jun; Ma, Xinrong; He, Kaize; He, Zhiming; Wang, Feng; Zhao, Hai

    2015-03-01

    Carriers were added to a pilot-scale duckweed-based (Lemna japonica 0223) wastewater treatment system to immobilize and enhance microorganisms. This system and another parallel duckweed system without carriers were operated for 1.5 years. The results indicated the addition of the carrier did not significantly affect the growth and composition of duckweed, the recovery of total nitrogen (TN), total phosphorus (TP) and CO2 or the removal of TP. However, it significantly improved the removal efficiency of TN and NH4(+)-N (by 19.97% and 15.02%, respectively). The use of 454 pyrosequencing revealed large differences of the microbial communities between the different components within a system and similarities within the same components between the two systems. The carrier biofilm had the highest bacterial diversity and relative abundance of nitrifying bacteria (3%) and denitrifying bacteria (24% of Rhodocyclaceae), which improved nitrogen removal of the system. An efficient N-removal duckweed system with enhanced microorganisms was established. PMID:25579229

  5. Microbial community and removal of nitrogen via the addition of a carrier in a pilot-scale duckweed-based wastewater treatment system.

    PubMed

    Zhao, Yonggui; Fang, Yang; Jin, Yanling; Huang, Jun; Ma, Xinrong; He, Kaize; He, Zhiming; Wang, Feng; Zhao, Hai

    2015-03-01

    Carriers were added to a pilot-scale duckweed-based (Lemna japonica 0223) wastewater treatment system to immobilize and enhance microorganisms. This system and another parallel duckweed system without carriers were operated for 1.5 years. The results indicated the addition of the carrier did not significantly affect the growth and composition of duckweed, the recovery of total nitrogen (TN), total phosphorus (TP) and CO2 or the removal of TP. However, it significantly improved the removal efficiency of TN and NH4(+)-N (by 19.97% and 15.02%, respectively). The use of 454 pyrosequencing revealed large differences of the microbial communities between the different components within a system and similarities within the same components between the two systems. The carrier biofilm had the highest bacterial diversity and relative abundance of nitrifying bacteria (3%) and denitrifying bacteria (24% of Rhodocyclaceae), which improved nitrogen removal of the system. An efficient N-removal duckweed system with enhanced microorganisms was established.

  6. Overview of bunch length measurements.

    SciTech Connect

    Lumpkin, A. H.

    1999-02-19

    An overview of particle and photon beam bunch length measurements is presented in the context of free-electron laser (FEL) challenges. Particle-beam peak current is a critical factor in obtaining adequate FEL gain for both oscillators and self-amplified spontaneous emission (SASE) devices. Since measurement of charge is a standard measurement, the bunch length becomes the key issue for ultrashort bunches. Both time-domain and frequency-domain techniques are presented in the context of using electromagnetic radiation over eight orders of magnitude in wavelength. In addition, the measurement of microbunching in a micropulse is addressed.

  7. Myofilament length dependent activation

    SciTech Connect

    de Tombe, Pieter P.; Mateja, Ryan D.; Tachampa, Kittipong; Mou, Younss Ait; Farman, Gerrie P.; Irving, Thomas C.

    2010-05-25

    The Frank-Starling law of the heart describes the interrelationship between end-diastolic volume and cardiac ejection volume, a regulatory system that operates on a beat-to-beat basis. The main cellular mechanism that underlies this phenomenon is an increase in the responsiveness of cardiac myofilaments to activating Ca{sup 2+} ions at a longer sarcomere length, commonly referred to as myofilament length-dependent activation. This review focuses on what molecular mechanisms may underlie myofilament length dependency. Specifically, the roles of inter-filament spacing, thick and thin filament based regulation, as well as sarcomeric regulatory proteins are discussed. Although the 'Frank-Starling law of the heart' constitutes a fundamental cardiac property that has been appreciated for well over a century, it is still not known in muscle how the contractile apparatus transduces the information concerning sarcomere length to modulate ventricular pressure development.

  8. Length Paradox in Relativity

    ERIC Educational Resources Information Center

    Martins, Roberto de A.

    1978-01-01

    Describes a thought experiment using a general analysis approach with Lorentz transformations to show that the apparent self-contradictions of special relativity concerning the length-paradox are really non-existant. (GA)

  9. Editorial: Redefining Length

    SciTech Connect

    Sprouse, Gene D.

    2011-07-15

    Technological changes have moved publishing to electronic-first publication where the print version has been relegated to simply another display mode. Distribution in HTML and EPUB formats, for example, changes the reading environment and reduces the need for strict pagination. Therefore, in an effort to streamline the calculation of length, the APS journals will no longer use the printed page as the determining factor for length. Instead the journals will now use word counts (or word equivalents for tables, figures, and equations) to establish length; for details please see http://publish.aps.org/authors/length-guide. The title, byline, abstract, acknowledgment, and references will not be included in these counts allowing authors the freedom to appropriately credit coworkers, funding sources, and the previous literature, bringing all relevant references to the attention of readers. This new method for determining length will be easier for authors to calculate in advance, and lead to fewer length-associated revisions in proof, yet still retain the quality of concise communication that is a virtue of short papers.

  10. Equilibrium CO bond lengths

    NASA Astrophysics Data System (ADS)

    Demaison, Jean; Császár, Attila G.

    2012-09-01

    Based on a sample of 38 molecules, 47 accurate equilibrium CO bond lengths have been collected and analyzed. These ultimate experimental (reEX), semiexperimental (reSE), and Born-Oppenheimer (reBO) equilibrium structures are compared to reBO estimates from two lower-level techniques of electronic structure theory, MP2(FC)/cc-pVQZ and B3LYP/6-311+G(3df,2pd). A linear relationship is found between the best equilibrium bond lengths and their MP2 or B3LYP estimates. These (and similar) linear relationships permit to estimate the CO bond length with an accuracy of 0.002 Å within the full range of 1.10-1.43 Å, corresponding to single, double, and triple CO bonds, for a large number of molecules. The variation of the CO bond length is qualitatively explained using the Atoms in Molecules method. In particular, a nice correlation is found between the CO bond length and the bond critical point density and it appears that the CO bond is at the same time covalent and ionic. Conditions which permit the computation of an accurate ab initio Born-Oppenheimer equilibrium structure are discussed. In particular, the core-core and core-valence correlation is investigated and it is shown to roughly increase with the bond length.

  11. Incubation length of dabbling ducks

    USGS Publications Warehouse

    Wells-Berlin, A. M.; Prince, H.H.; Arnold, T.W.

    2005-01-01

    We collected unincubated eggs from wild Mallard (Anas platyrhynchos), Gadwall (A. strepera), Blue-winged Teal (A. discors), and Northern Shoveler (A. clypeata) nests and artificially incubated them at 37.5??C. Average incubation lengths of Mallard, Gadwall, and Northern Shoveler eggs did not differ from their wild-nesting counterparts, but artificially incubated Blue-winged Teal eggs required an additional 1.7 days to hatch, suggesting that wild-nesting teal incubated more effectively. A small sample of Mallard, Gadwall, and Northern Shoveler eggs artificially incubated at 38.3??C hatched 1 day sooner, indicating that incubation temperature affected incubation length. Mean incubation length of Blue-winged Teal declined by 1 day for each 11-day delay in nesting, but we found no such seasonal decline among Mallards, Gadwalls, or Northern Shovelers. There is no obvious explanation for the seasonal reduction in incubation length for Blue-winged Teal eggs incubated in a constant environment, and the phenomenon deserves further study. ?? The Cooper Ornithological Society 2005.

  12. Proposed Modifications to the Conceptual Model of Coaching Efficacy and Additional Validity Evidence for the Coaching Efficacy Scale II-High School Teams

    ERIC Educational Resources Information Center

    Myers, Nicholas; Feltz, Deborah; Chase, Melissa

    2011-01-01

    The purpose of this study was to determine whether theoretically relevant sources of coaching efficacy could predict the measures derived from the Coaching Efficacy Scale II-High School Teams (CES II-HST). Data were collected from head coaches of high school teams in the United States (N = 799). The analytic framework was a multiple-group…

  13. Food additives

    PubMed Central

    Spencer, Michael

    1974-01-01

    Food additives are discussed from the food technology point of view. The reasons for their use are summarized: (1) to protect food from chemical and microbiological attack; (2) to even out seasonal supplies; (3) to improve their eating quality; (4) to improve their nutritional value. The various types of food additives are considered, e.g. colours, flavours, emulsifiers, bread and flour additives, preservatives, and nutritional additives. The paper concludes with consideration of those circumstances in which the use of additives is (a) justified and (b) unjustified. PMID:4467857

  14. Zero-point length from string fluctuations

    NASA Astrophysics Data System (ADS)

    Fontanini, Michele; Spallucci, Euro; Padmanabhan, T.

    2006-02-01

    One of the leading candidates for quantum gravity, viz. string theory, has the following features incorporated in it. (i) The full spacetime is higher-dimensional, with (possibly) compact extra-dimensions; (ii) there is a natural minimal length below which the concept of continuum spacetime needs to be modified by some deeper concept. On the other hand, the existence of a minimal length (zero-point length) in four-dimensional spacetime, with obvious implications as UV regulator, has been often conjectured as a natural aftermath of any correct quantum theory of gravity. We show that one can incorporate the apparently unrelated pieces of information-zero-point length, extra-dimensions, string T-duality-in a consistent framework. This is done in terms of a modified Kaluza-Klein theory that interpolates between (high-energy) string theory and (low-energy) quantum field theory. In this model, the zero-point length in four dimensions is a "virtual memory" of the length scale of compact extra-dimensions. Such a scale turns out to be determined by T-duality inherited from the underlying fundamental string theory. From a low energy perspective short distance infinities are cutoff by a minimal length which is proportional to the square root of the string slope, i.e., √{α‧}. Thus, we bridge the gap between the string theory domain and the low energy arena of point-particle quantum field theory.

  15. Mappability and read length

    PubMed Central

    Li, Wentian; Freudenberg, Jan

    2014-01-01

    Power-law distributions are the main functional form for the distribution of repeat size and repeat copy number in the human genome. When the genome is broken into fragments for sequencing, the limited size of fragments and reads may prevent an unique alignment of repeat sequences to the reference sequence. Repeats in the human genome can be as long as 104 bases, or 105 − 106 bases when allowing for mismatches between repeat units. Sequence reads from these regions are therefore unmappable when the read length is in the range of 103 bases. With a read length of 1000 bases, slightly more than 1% of the assembled genome, and slightly less than 1% of the 1 kb reads, are unmappable, excluding the unassembled portion of the human genome (8% in GRCh37/hg19). The slow decay (long tail) of the power-law function implies a diminishing return in converting unmappable regions/reads to become mappable with the increase of the read length, with the understanding that increasing read length will always move toward the direction of 100% mappability. PMID:25426137

  16. Seismic Hazard and Fault Length

    NASA Astrophysics Data System (ADS)

    Black, N. M.; Jackson, D. D.; Mualchin, L.

    2005-12-01

    If mx is the largest earthquake magnitude that can occur on a fault, then what is mp, the largest magnitude that should be expected during the planned lifetime of a particular structure? Most approaches to these questions rely on an estimate of the Maximum Credible Earthquake, obtained by regression (e.g. Wells and Coppersmith, 1994) of fault length (or area) and magnitude. Our work differs in two ways. First, we modify the traditional approach to measuring fault length, to allow for hidden fault complexity and multi-fault rupture. Second, we use a magnitude-frequency relationship to calculate the largest magnitude expected to occur within a given time interval. Often fault length is poorly defined and multiple faults rupture together in a single event. Therefore, we need to expand the definition of a mapped fault length to obtain a more accurate estimate of the maximum magnitude. In previous work, we compared fault length vs. rupture length for post-1975 earthquakes in Southern California. In this study, we found that mapped fault length and rupture length are often unequal, and in several cases rupture broke beyond the previously mapped fault traces. To expand the geologic definition of fault length we outlined several guidelines: 1) if a fault truncates at young Quaternary alluvium, the fault line should be inferred underneath the younger sediments 2) faults striking within 45° of one another should be treated as a continuous fault line and 3) a step-over can link together faults at least 5 km apart. These definitions were applied to fault lines in Southern California. For example, many of the along-strike faults lines in the Mojave Desert are treated as a single fault trending from the Pinto Mountain to the Garlock fault. In addition, the Rose Canyon and Newport-Inglewood faults are treated as a single fault line. We used these more generous fault lengths, and the Wells and Coppersmith regression, to estimate the maximum magnitude (mx) for the major faults in

  17. A variable mixing-length ratio for convection theory

    NASA Technical Reports Server (NTRS)

    Chan, K. L.; Wolff, C. L.; Sofia, S.

    1981-01-01

    It is argued that a natural choice for the local mixing length in the mixing-length theory of convection has a value proportional to the local density scale height of the convective bubbles. The resultant variable mixing-length ratio (the ratio between the mixing length and the pressure scale height) of this theory is enhanced in the superadiabatic region and approaches a constant in deeper layers. Numerical tests comparing the new mixing length successfully eliminate most of the density inversion that typically plagues conventional results. The new approach also seems to indicate the existence of granular motion at the top of the convection zone.

  18. Vowel length in Farsi

    NASA Astrophysics Data System (ADS)

    Shademan, Shabnam

    2001-05-01

    This study tests whether Farsi vowels are contrastive with respective to length. Farsi has a six-vowel system with three lax vowels and three tense vowels. Both traditional grammarians and modern linguists believe that Farsi tense vowels are longer than lax vowels, and that there are no vowel pairs that contrast only in length. However, it has been suggested that Farsi exhibits compensatory lengthening, which is triggered by the deletion of glottal consonants in coda position in informal speech (Darzi, 1991). As a result, minimal pairs such as [tar] and [tarh] should contrast only with respect to vowel length. A corpus of 90 words of the form CVC, CVCG, CVGC, and CVCC (where V=a vowel and G=a glottal consonant) was recorded, and durations of vowels in different contexts were measured and compared. Preliminary results show that lax vowel durations fall into three groups with CVCC longer than CVCG/CVGC, and the latter longer than CVC. It remains to be seen whether CVCG/CVGC words show compensatory lengthening when the glottal consonant is deleted.

  19. Kilogram-scale production of SnO(2) yolk-shell powders by a spray-drying process using dextrin as carbon source and drying additive.

    PubMed

    Choi, Seung Ho; Kang, Yun Chan

    2014-05-01

    A simple and general method for the large-scale production of yolk-shell powders with various compositions by a spray-drying process is reported. Metal salt/dextrin composite powders with a spherical and dense structure were obtained by spray drying and transformed into yolk-shell powders by simple combustion in air. Dextrin plays a key role in the preparation of precursor powders for fabricating yolk-shell powders by spray drying. Droplets containing metal salts and dextrin show good drying characteristics even in a severe environment of high humidity. Sucrose, glucose, and polyvinylpyrrolidone are widely used as carbon sources in the preparation of metal oxide/carbon composite powders; however, they are not appropriate for large-scale spray-drying processes because of their caramelization properties and adherence to the surface of the spray dryer. SnO2 yolk-shell powders were studied as the first target material in the spray-drying process. Combustion of tin oxalate/dextrin composite powders at 600 °C in air produced single-shelled SnO2 yolk-shell powders with the configuration SnO2 @void@SnO2 . The SnO2 yolk-shell powders prepared by the simple spray-drying process showed superior electrochemical properties, even at high current densities. The discharge capacities of the SnO2 yolk-shell powders at a current density of 2000 mA g(-1) were 645 and 570 mA h g(-1) for the second and 100th cycles, respectively; the corresponding capacity retention measured for the second cycle was 88 %.

  20. Geometry of area without length

    NASA Astrophysics Data System (ADS)

    Ho, Pei-Ming; Inami, Takeo

    2016-01-01

    To define a free string by the Nambu-Goto action, all we need is the notion of area, and mathematically the area can be defined directly in the absence of a metric. Motivated by the possibility that string theory admits backgrounds where the notion of length is not well defined but a definition of area is given, we study space-time geometries based on the generalization of a metric to an area metric. In analogy with Riemannian geometry, we define the analogues of connections, curvatures, and Einstein tensor. We propose a formulation generalizing Einstein's theory that will be useful if at a certain stage or a certain scale the metric is ill defined and the space-time is better characterized by the notion of area. Static spherical solutions are found for the generalized Einstein equation in vacuum, including the Schwarzschild solution as a special case.

  1. Large-scale sequencing reveals 21U-RNAs and additional microRNAs and endogenous siRNAs in C. elegans.

    PubMed

    Ruby, J Graham; Jan, Calvin; Player, Christopher; Axtell, Michael J; Lee, William; Nusbaum, Chad; Ge, Hui; Bartel, David P

    2006-12-15

    We sequenced approximately 400,000 small RNAs from Caenorhabditis elegans. Another 18 microRNA (miRNA) genes were identified, thereby extending to 112 our tally of confidently identified miRNA genes in C. elegans. Also observed were thousands of endogenous siRNAs generated by RNA-directed RNA polymerases acting preferentially on transcripts associated with spermatogenesis and transposons. In addition, a third class of nematode small RNAs, called 21U-RNAs, was discovered. 21U-RNAs are precisely 21 nucleotides long, begin with a uridine 5'-monophosphate but are diverse in their remaining 20 nucleotides, and appear modified at their 3'-terminal ribose. 21U-RNAs originate from more than 5700 genomic loci dispersed in two broad regions of chromosome IV-primarily between protein-coding genes or within their introns. These loci share a large upstream motif that enables accurate prediction of additional 21U-RNAs. The motif is conserved in other nematodes, presumably because of its importance for producing these diverse, autonomously expressed, small RNAs (dasRNAs).

  2. Additional psychometric data for the Spanish Modified Dental Anxiety Scale, and psychometric data for a Spanish version of the Revised Dental Beliefs Survey

    PubMed Central

    2010-01-01

    Background Hispanics comprise the largest ethnic minority group in the United States. Previous work with the Spanish Modified Dental Anxiety Scale (MDAS) yielded good validity, but lower test-retest reliability. We report the performance of the Spanish MDAS in a new sample, as well as the performance of the Spanish Revised Dental Beliefs Survey (R-DBS). Methods One hundred sixty two Spanish-speaking adults attending Spanish-language church services or an Hispanic cultural festival completed questionnaires containing the Spanish MDAS, Spanish R-DBS, and dental attendance questions, and underwent a brief oral examination. Church attendees completed the questionnaire a second time, for test-retest purposes. Results The Spanish MDAS and R-DBS were completed by 156 and 136 adults, respectively. The test-retest reliability of the Spanish MDAS was 0.83 (95% CI = 0.60-0.92). The internal reliability of the Spanish R-DBS was 0.96 (95% CI = 0.94-0.97), and the test-retest reliability was 0.86 (95% CI = 0.64-0.94). The two measures were significantly correlated (Spearman's rho = 0.38, p < 0.001). Participants who do not currently go to a dentist had significantly higher MDAS scores (t = 3.40, df = 106, p = 0.003) as well as significantly higher R-DBS scores (t = 2.21, df = 131, p = 0.029). Participants whose most recent dental visit was for pain or a problem, rather than for a check-up, scored significantly higher on both the MDAS (t = 3.00, df = 106, p = 0.003) and the R-DBS (t = 2.85, df = 92, p = 0.005). Those with high dental fear (MDAS score 19 or greater) were significantly more likely to have severe caries (Chi square = 6.644, df = 2, p = 0.036). Higher scores on the R-DBS were significantly related to having more missing teeth (Spearman's rho = 0.23, p = 0.009). Conclusion In this sample, the test-retest reliability of the Spanish MDAS was higher. The significant relationships between dental attendance and questionnaire scores, as well as the difference in caries

  3. One-year clinical results of Er,Cr:YSGG laser application in addition to scaling and root planing in patients with early to moderate periodontitis.

    PubMed

    Kelbauskiene, Solveiga; Baseviciene, Nomeda; Goharkhay, Kawe; Moritz, Andreas; Machiulskiene, Vita

    2011-07-01

    In 30 patients with periodontitis, a total of 278 teeth exhibiting bleeding on probing, subgingival calculus, and a probing depth between 3-6 mm were examined. For each participant, two treatment types were alternatively applied on the contralateral quadrants: scaling and root planing (SRP) as control, and SRP followed by Er,Cr:YSGG laser application (SRP+laser), as a test method. Five clinical parameters: plaque level, bleeding on probing, probing depth, gingival recession and clinical attachment level were examined at baseline and at 2, 3, 6, 12 months after treatment. Of the total of 1,668 sites examined in all patients, 1,088 sites were found with a probing depth of 3-6 mm. In these sites, differences in clinical parameters between SRP and SRP+laser-treated quadrants were analyzed, assuming the level of p < 0.05 as significant. After 2 months from baseline, the mean probing depth reduction and the clinical attachment level gain were significantly greater in SRP+laser than in SRP quadrants, and remained so throughout the study (p < 0.001). A marked reduction of the bleeding scores occurred in all examined sites, irrespective of the treatment method. However, after 12 months, significantly less teeth exhibited bleeding on probing in SRP+laser quadrants than in SRP quadrants (p < 0.001). The mean plaque and gingival recession levels did not differ between the SRP and SRP+laser quadrants neither before nor after the treatment. The periodontal procedures either using Er,Cr:YSGG laser after SRP or SRP alone, lead to significant improvements in all clinical parameters investigated. However, laser application, as an adjunct to SRP, appeared to be more advantageous.

  4. Development of cost-effective media to increase the economic potential for larger-scale bioproduction of natural food additives by Lactobacillus rhamnosus , Debaryomyces hansenii , and Aspergillus niger.

    PubMed

    Salgado, José Manuel; Rodríguez, Noelia; Cortés, Sandra; Domínguez, José Manuel

    2009-11-11

    Yeast extract (YE) is the most common nitrogen source in a variety of bioprocesses in spite of the high cost. Therefore, the use of YE in culture media is one of the major technical hurdles to be overcome for the development of low-cost fermentation routes, making the search for alternative-cheaper nitrogen sources particularly desired. The aim of the current study is to develop cost-effective media based on corn steep liquor (CSL) and locally available vinasses in order to increase the economic potential for larger-scale bioproduction. Three microorganisms were evaluated: Lactobacillus rhamnosus , Debaryomyces hansenii , and Aspergillus niger . The amino acid profile and protein concentration was relevant for the xylitol and citric acid production by D. hansenii and A. niger , respectively. Metals also played an important role for citric acid production, meanwhile, D. hansenii showed a strong dependence with the initial amount of Mg(2+). Under the best conditions, 28.8 g lactic acid/L (Q(LA) = 0.800 g/L.h, Y(LA/S) = 0.95 g/g), 35.3 g xylitol/L (Q(xylitol) = 0.380 g/L.h, Y(xylitol/S) = 0.69 g/g), and 13.9 g citric acid/L (Q(CA) = 0.146 g/L.h, Y(CA/S) = 0.63 g/g) were obtained. The economic efficiency (E(p/euro)) parameter identify vinasses as a lower cost and more effective nutrient source in comparison to CSL.

  5. Length of stain dosimeter

    NASA Technical Reports Server (NTRS)

    Lueck, Dale E. (Inventor)

    1994-01-01

    Payload customers for the Space Shuttle have recently expressed concerns about the possibility of their payloads at an adjacent pad being contaminated by plume effluents from a shuttle at an active pad as they await launch on an inactive pad. As part of a study to satisfy such concerns a ring of inexpensive dosimeters was deployed around the active pad at the inter-pad distance. However, following a launch, dosimeters cannot be read for several hours after the exposure. As a consequence factors such as different substrates, solvent systems, and possible volatilization of HCl from the badges were studied. This observation led to the length of stain (LOS) dosimeters of this invention. Commercial passive LOS dosimeters are sensitive only to the extent of being capable of sensing 2 ppm to 20 ppm if the exposure is 8 hours. To map and quantitate the HCl generated by Shuttle launches, and in the atmosphere within a radius of 1.5 miles from the active pad, a sensitivity of 2 ppm HCl in the atmospheric gases on an exposure of 5 minutes is required. A passive length of stain dosimeter has been developed having a sensitivity rendering it capable of detecting a gas in a concentration as low as 2 ppm on an exposure of five minutes.

  6. Phosphazene additives

    DOEpatents

    Harrup, Mason K; Rollins, Harry W

    2013-11-26

    An additive comprising a phosphazene compound that has at least two reactive functional groups and at least one capping functional group bonded to phosphorus atoms of the phosphazene compound. One of the at least two reactive functional groups is configured to react with cellulose and the other of the at least two reactive functional groups is configured to react with a resin, such as an amine resin of a polycarboxylic acid resin. The at least one capping functional group is selected from the group consisting of a short chain ether group, an alkoxy group, or an aryloxy group. Also disclosed are an additive-resin admixture, a method of treating a wood product, and a wood product.

  7. Potlining Additives

    SciTech Connect

    Rudolf Keller

    2004-08-10

    In this project, a concept to improve the performance of aluminum production cells by introducing potlining additives was examined and tested. Boron oxide was added to cathode blocks, and titanium was dissolved in the metal pool; this resulted in the formation of titanium diboride and caused the molten aluminum to wet the carbonaceous cathode surface. Such wetting reportedly leads to operational improvements and extended cell life. In addition, boron oxide suppresses cyanide formation. This final report presents and discusses the results of this project. Substantial economic benefits for the practical implementation of the technology are projected, especially for modern cells with graphitized blocks. For example, with an energy savings of about 5% and an increase in pot life from 1500 to 2500 days, a cost savings of $ 0.023 per pound of aluminum produced is projected for a 200 kA pot.

  8. Meta-analysis of genome-wide association data and large-scale replication identifies additional susceptibility loci for type 2 diabetes

    PubMed Central

    Zeggini, Eleftheria; Scott, Laura J.; Saxena, Richa; Voight, Benjamin F.; Marchini, Jonathan L; Hu, Tainle; de Bakker, Paul IW; Abecasis, Gonçalo R; Almgren, Peter; Andersen, Gitte; Ardlie, Kristin; Boström, Kristina Bengtsson; Bergman, Richard N; Bonnycastle, Lori L; Borch-Johnsen, Knut; Burtt, Noël P; Chen, Hong; Chines, Peter S; Daly, Mark J; Deodhar, Parimal; Ding, Charles; Doney, Alex S F; Duren, William L; Elliott, Katherine S; Erdos, Michael R; Frayling, Timothy M; Freathy, Rachel M; Gianniny, Lauren; Grallert, Harald; Grarup, Niels; Groves, Christopher J; Guiducci, Candace; Hansen, Torben; Herder, Christian; Hitman, Graham A; Hughes, Thomas E; Isomaa, Bo; Jackson, Anne U; Jørgensen, Torben; Kong, Augustine; Kubalanza, Kari; Kuruvilla, Finny G; Kuusisto, Johanna; Langenberg, Claudia; Lango, Hana; Lauritzen, Torsten; Li, Yun; Lindgren, Cecilia M; Lyssenko, Valeriya; Marvelle, Amanda F; Meisinger, Christa; Midthjell, Kristian; Mohlke, Karen L; Morken, Mario A; Morris, Andrew D; Narisu, Narisu; Nilsson, Peter; Owen, Katharine R; Palmer, Colin NA; Payne, Felicity; Perry, John RB; Pettersen, Elin; Platou, Carl; Prokopenko, Inga; Qi, Lu; Qin, Li; Rayner, Nigel W; Rees, Matthew; Roix, Jeffrey J; Sandbæk, Anelli; Shields, Beverley; Sjögren, Marketa; Steinthorsdottir, Valgerdur; Stringham, Heather M; Swift, Amy J; Thorleifsson, Gudmar; Thorsteinsdottir, Unnur; Timpson, Nicholas J; Tuomi, Tiinamaija; Tuomilehto, Jaakko; Walker, Mark; Watanabe, Richard M; Weedon, Michael N; Willer, Cristen J; Illig, Thomas; Hveem, Kristian; Hu, Frank B; Laakso, Markku; Stefansson, Kari; Pedersen, Oluf; Wareham, Nicholas J; Barroso, Inês; Hattersley, Andrew T; Collins, Francis S; Groop, Leif; McCarthy, Mark I; Boehnke, Michael; Altshuler, David

    2009-01-01

    Genome-wide association (GWA) studies have identified multiple new genomic loci at which common variants modestly but reproducibly influence risk of type 2 diabetes (T2D)1-11. Established associations to common and rare variants explain only a small proportion of the heritability of T2D. As previously published analyses had limited power to discover loci at which common alleles have modest effects, we performed meta-analysis of three T2D GWA scans encompassing 10,128 individuals of European-descent and ~2.2 million SNPs (directly genotyped and imputed). Replication testing was performed in an independent sample with an effective sample size of up to 53,975. At least six new loci with robust evidence for association were detected, including the JAZF1 (p=5.0×10−14), CDC123/CAMK1D (p=1.2×10−10), TSPAN8/LGR5 (p=1.1×10−9), THADA (p=1.1×10−9), ADAMTS9 (p=1.2×10−8), and NOTCH2 (p=4.1×10−8) gene regions. The large number of loci with relatively small effects indicates the value of large discovery and follow-up samples in identifying additional clues about the inherited basis of T2D. PMID:18372903

  9. Effective normalization of complexity measurements for epoch length and sampling frequency.

    PubMed

    Rapp, P E; Cellucci, C J; Korslund, K E; Watanabe, T A; Jiménez-Montaño, M A

    2001-07-01

    The algorithmic complexity of a symbol sequence is sensitive to the length of the message. Additionally, in those cases where the sequence is constructed by the symbolic reduction of an experimentally observed wave form, the corresponding value of algorithmic complexity is also sensitive to the sampling frequency. In this contribution, we present definitions of algorithmic redundancy that are sequence-sensitive generalizations of Shannon's original definition of information redundancy. In contrast with algorithmic complexity, we demonstrate that algorithmic redundancy is not sensitive to message length or to observation scale (sampling frequency) when stationary systems are examined.

  10. The information theoretic interpretation of the length of a curve

    NASA Astrophysics Data System (ADS)

    Czech, Bartlomiej; Hayden, Patrick; Lashkari, Nima; Swingle, Brian

    2015-06-01

    In the context of holographic duality with AdS3 asymptotics, the Ryu-Takayanagi formula states that the entanglement entropy of a subregion is given by the length of a certain bulk geodesic. The entanglement entropy can be operationalized as the entanglement cost necessary to transmit the state of the subregion from one party to another while preserving all correlations with a reference party. The question then arises as to whether the lengths of other bulk curves can be interpreted as entanglement costs for some other information theoretic tasks. Building on recent results showing that the length of more general bulk curves is computed by the differential entropy, we introduce a new task called constrained state merging, whereby the state of the boundary subregion must be transmitted using operations restricted in location and scale in a way determined by the geometry of the bulk curve. Our main result is that the cost to transmit the state of a subregion under the conditions of constrained state merging is given by the differential entropy and hence the signed length of the corresponding bulk curve. When the cost is negative, constrained state merging distills entanglement rather than consuming it. This demon-stration has two parts: first, we exhibit a protocol whose cost is the length of the curve and second, we prove that this protocol is optimal in that it uses the minimum amount of entanglement. In order to complete the proof, we additionally demonstrate that single-shot smooth conditional entropies for intervals in 1+1-dimensional conformal field theories with large central charge are well approximated by their von Neumann counterparts. We also revisit the relationship between the differential entropy and the maximum entropy among locally consistent entropy density operators, demonstrating large quantitative discrepancy between the two quantities in conformal field theories. We conclude with a brief discussion of extensions and lessons.

  11. Density Functional Theory-Derived Group Additivity and Linear Scaling Methods for Prediction of Oxygenate Stability on Metal Catalysts. Adsorption of Open-Ring Alcohol and Polyol Dehydrogenation Intermediates on Pt-Based Metals

    SciTech Connect

    Salciccioli, Michael; Chen, Ying; Vlachos, Dion G.

    2010-11-09

    Semiempirical methods for prediction of thermochemical properties of adsorbed oxygenates are developed. Periodic density functional theory calculations are used to study the relative stability of ethanol, ethylene glycol, isopropyl alcohol, and glycerol dehydrogenation intermediates on Pt(111). For ethylene glycol dehydrogenation intermediates, it is found that the thermodynamically favored intermediates at each level of dehydrogenation are as follows: HOCH2CHOH, HOCHCHOH, HOCHCOH, HOCCOH ≈ HOCHCO, HOCCO, OCCO. Structural and energetic patterns emerge from these C2HxO2 adsorption calculations that lead to the formation of group additive properties for thermochemical property prediction of oxygenates on Pt(111). Finally, linear scaling relationships of atomic binding energy are used to predict the binding energy of the C2HxO2 species on the Ni(111) surface and Ni-Pt-Pt(111) bimetallic surface. It is shown that the linear scaling relationships can accurately predict the binding energy of larger oxygenates as well as of oxygenates on bimetallic catalysts. Corrections for ring strain and weak oxygen-metal and hydrogen-bonding interactions are added to increase the accuracy of group additivity and linear scaling relationships.

  12. Construction of Covariance Functions with Variable Length Fields

    NASA Technical Reports Server (NTRS)

    Gaspari, Gregory; Cohn, Stephen E.; Guo, Jing; Pawson, Steven

    2005-01-01

    This article focuses on construction, directly in physical space, of three-dimensional covariance functions parametrized by a tunable length field, and on an application of this theory to reproduce the Quasi-Biennial Oscillation (QBO) in the Goddard Earth Observing System, Version 4 (GEOS-4) data assimilation system. These Covariance models are referred to as multi-level or nonseparable, to associate them with the application where a multi-level covariance with a large troposphere to stratosphere length field gradient is used to reproduce the QBO from sparse radiosonde observations in the tropical lower stratosphere. The multi-level covariance functions extend well-known single level covariance functions depending only on a length scale. Generalizations of the first- and third-order autoregressive