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Sample records for facing step channel

  1. Experimental investigation of turbulent flow in a channel with the backward-facing inclined step

    NASA Astrophysics Data System (ADS)

    Příhoda, Jaromír; Kotek, Michal; Uruba, Václav; Kopecký, Václav; Hladík, Ondřej

    2012-04-01

    The work deals with the experimental investigation of turbulent flow in a closed channel with the backward-facing inclined step. Experiments were carried by means of the PIV optical measuring method in the channel of the rectangular cross-section in the inlet part and with inclined steps of the constant height H mm and various inclination angles for a wide range of the Reynolds number. The attention was paid especially to the separation region behind the step and to the relaxation of the shear layer after the reattachment in the outlet part of the channel. The dependence of the length of the separation region on the Reynolds number was obtained for various step angles. Optical measurements were completed by the measurement of static pressure distribution in the inlet and outlet part of the channel to estimate energy losses.

  2. Stepped Hydraulic Geometry in Stepped Channels

    NASA Astrophysics Data System (ADS)

    Comiti, F.; Cadol, D. D.; Wohl, E.

    2007-12-01

    Steep mountain streams typically present a stepped longitudinal profile. Such stepped channels feature tumbling flow, where hydraulic jumps represent an important source of channel roughness (spill resistance). However, the extent to which spill resistance persists up to high flows has not been ascertained yet, such that a faster, skimming flow has been envisaged to begin at those conditions. In order to analyze the relationship between flow resistance and bed morphology, a mobile bed physical model was developed at Colorado State University (Fort Collins, USA). An 8 m-long, 0.6 m-wide flume tilted at a constant 14% slope was used, testing 2 grain-size mixtures differing only for the largest fraction. Experiments were conducted under clear water conditions. Reach-averaged flow velocity was measured using salt tracers, bed morphology and flow depth by a point gage, and surface grain size using commercial image-analysis software. Starting from an initial plane bed, progressively higher flow rates were used to create different bed structures. After each bed morphology was stable with its forming discharge, lower-than-forming flows were run to build a hydraulic geometry curve. Results show that even though equilibrium slopes ranged from 8.5% to 14%, the reach-averaged flow was always sub-critical. Steps formed through a variety of mechanisms, with immobile clasts playing a dominant role by causing local scouring and/or trapping moving smaller particles. Overall, step height, step pool steepness, relative pool area and volume increased with discharge up to the threshold when the bed approached fully- mobilized conditions. For bed morphologies surpassing a minimum profile roughness, a stepped velocity- discharge relationship is evident, with sharp rises in velocity correlated with the disappearance of rollers in pools at flows approaching the formative discharge for each morphology. Flow resistance exhibits an opposite pattern, with drops in resistance being a function

  3. 12. DETAIL VIEW OF STEPPED CONCRETE GRAVITY DAM FACE AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. DETAIL VIEW OF STEPPED CONCRETE GRAVITY DAM FACE AND ROCK OUTCROPPING, WITH LAKE IN BACKGROUND, SHOWN AT MINIMUM WATER FLOW, LOOKING SOUTHEAST (UPSTREAM) - Van Arsdale Dam, South Fork of Eel River, Ukiah, Mendocino County, CA

  4. 5. Detail of tower bottom step and stairway structure, facing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. Detail of tower bottom step and stairway structure, facing southeast - Cold Mountain Fire Lookout Station, Lookout Tower, Krassel District, Frank Church River of No Return Wilderness, Dixie, Idaho County, ID

  5. CHANNEL EROSION BEHIND FACILITIES 316 AND 362. VIEW FACING NORTH. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CHANNEL EROSION BEHIND FACILITIES 316 AND 362. VIEW FACING NORTH. - U.S. Naval Base, Pearl Harbor, Naval Housing Area Hospital Point, Along First Avenue to west of & along Ford Island Way, Pearl City, Honolulu County, HI

  6. 4. SPILLWAY DRUM GATES AND CHANNEL, LOOKING NORTHEAST (upstream face ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. SPILLWAY DRUM GATES AND CHANNEL, LOOKING NORTHEAST (upstream face and Control House in background) - Tieton Dam, Spillway & Drum Gates, South & East side of State Highway 12, Naches, Yakima County, WA

  7. Ventilated cavity flow over a backward-facing step

    NASA Astrophysics Data System (ADS)

    Pearce, B. W.; Brandner, P. A.; Foster, S. J.

    2015-12-01

    Ventilated cavities detaching from a backward facing step (BFS) are investigated for a range of upstream boundary layer thicknesses in a cavitation tunnel. The upstream turbulent boundary layer thickness is varied by artificial thickening of the test section natural boundary layer using an array of transversely injected jets. Momentum thickness Reynolds numbers from 6.6 to 44 x 103 were tested giving boundary layer thickness to step height ratios from 1.25 to 3.8. A range of cavity lengths were obtained by variation of the ventilation flow rate for several freestream Reynolds numbers. Cavity length to step height ratios from 20 to 80 were achieved. Cavity length was found to be linearly dependent on ventilation rate and to decrease with increasing boundary layer thickness and/or Reynolds number. This result may have implications in the practical optimization of these flows which occur in applications such as drag reduction on marine hull forms.

  8. Computation of turbulent flows over backward-facing step

    NASA Technical Reports Server (NTRS)

    Mansour, N. N.; Kim, J.; Moin, P.

    1983-01-01

    A numerical method for computing incompressible turbulent flows is presented. The method is tested by calculating laminar recirculating flows and is applied in conjunction with a modified Kappa-epsilon model to compute the flow over a backward-facing step. In the laminar regime, the computational results are in good agreement with the experimental data. The turbulent flow study shows that the reattachment length is underpredicted by the standard Kappa-epsilon model. The addition of a term to the standard model that accounts for the effects of rotation on turbulent flow improves the results in the recirculation region and increases the computed reattachment length.

  9. Three-component laser velocimeter surveys of the flow over a backward-facing step

    NASA Technical Reports Server (NTRS)

    Kjelgaard, Scott O.

    1991-01-01

    A three-component laser velocimeter is used to investigate the flow over a backward-facing step. The backward-facing step had an expansion ratio of 2, a boundary layer height to step height ratio of 0.34 and a Reynolds number based on step height of 19,000. Results from three-component velocimeter surveys of the flow over the backward-facing step are presented with comparisons of the current experiment with previous experiments and computational results. The present results compared well with previous experiments with the exception of the reattachment length. The short reattachment length was due to the short length of the channel downstream. The measurement of the lateral velocity component showed that there is a mean flow in and out of the centerline plane as high as 7 percent of the freestream velocity. However, the shear stresses show no correlation between the lateral fluctuations and the longitudinal and vertical fluctuations, indicating that the flow is 2D in terms of the turbulence quantities.

  10. Experimental investigation of a cavitating backward-facing step flow

    NASA Astrophysics Data System (ADS)

    Maurice, G.; Djeridi, H.; Barre, S.

    2014-03-01

    The present study is the first part of global experimental work which is intended to produce a refined database of liquid and vapor phases and to improve CFD modeling of turbulent cavitating flows which can occur in rocket engine turbo-pump inducers. The purpose of the present experimental study is to get a better understanding of the dynamics of the liquid phase in a cavitating backward facing step flow and provide a refined database for the physical analysis of interaction between turbulence and cavitation. The backward facing step flow provides us a well-known test case to compare vortex dynamics and a realistic industrial configuration such as backflow in turbo machinery. Experiments were conducted in the hydrodynamic tunnel of CREMHyG at Grenoble,which was especially designed to study cavitating shear flows at high Reynolds numbers. To highlight the liquid phase topology and dynamics such as large vortex structures, free shear layer instability, reattachment wall interaction and reverse flow, the flow is characterized by Laser Induced Fluoresence Particles Image Velocimetry (PIV-LIF) measurements techniques and by Laser Doppler Velocimetry (LDV) techniques using spectral analysis to characterize the vortex shedding dynamics. The liquid phase was analyzed at different cavitation levels corresponding to 1% to 45% of void ratio range inside the shear layer, recirculation area and reattachment zone. The mean and fluctuating liquid velocities are clearly modified by the vapor phase and the scale of the vortical structures tends to be smaller inducing a destructuration of turbulence by cavitation.

  11. 66. VIEW OF DELUGE CHANNEL; NORTH FACE OF THEODOLITE SHELTER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    66. VIEW OF DELUGE CHANNEL; NORTH FACE OF THEODOLITE SHELTER (BLDG. 788); TELEVISION CAMERA TOWER; CAMERA TOWER FROM SOUTH END OF LAUNCH DECK - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  12. Lattice-Boltzmann Simulations of Flows Over Backward-Facing Inclined Steps

    NASA Astrophysics Data System (ADS)

    Kotapati, Rupesh B.; Shock, Richard; Chen, Hudong

    2014-01-01

    The lattice-Boltzmann method (LBM) is used in conjunction with a very large-eddy simulation (VLES) turbulence modeling approach to compute separated flows over backward-facing steps at different wall inclination angles. The Reynolds number ReH based on the step height H and center-line velocity at the channel inlet ucl is 64 000. The expansion ratio of the outlet section to the inlet section of the channel is 1.48. Wall inclination angles α considered include 10°, 15°, 20°, 25°, 30° and 90°. The computed flow fields for different inclination angles of the step are assessed against the laser Doppler anemometry (LDA) measurements of Makiola [B. Makiola, Ph.D. Thesis, University of Karlsruhe (1992); B. Ruck and B. Makiola, Flow separation over the step with inclined walls, in Near-Wall Turbulent Flows, eds. R. M. C. So, C. G. Speziale and B. E. Launder (Elsevier, 1993), p. 999.]. In addition to validating the lattice-Boltzmann solution with the experiments, this study also investigates the effects of three dimensionality, the proximity of the inlet to the step, and the grid resolution on the quality of the predictions.

  13. Turbulent atmospheric flow over a backward-facing step

    NASA Technical Reports Server (NTRS)

    Kaul, U. K.; Frost, W.

    1976-01-01

    The phenomenon of atmospheric shear layer separation over a man-made structure such as a building (modeled as a backward-facing step) has been analyzed theoretically by (1) solving the two-dimensional equations of motion in the two variables, stream function and vorticity, and by (2) employing an approximate integral technique. Boundary conditions for the undisturbed flow are that of the turbulent atmospheric shear flow over a rough terrain. In the first approach a two-equation model of turbulence was used. In the second approach an approximate technique was utilized in an attempt to describe the details of the flow in the recirculation zone behind the step. The results predict velocity profiles in sufficient detail that the presence of the corner eddy in the region of negative surface pressure gradient is evident. The magnitude of the reversed flow velocity in the recirculation eddy has been found to agree with that found from experiments. Also, a surface eddy viscosity distribution has been an outgrowth of the method which realistically follows the magnitude of the surface pressure gradient distribution as found experimentally.

  14. An Approximate Analytical Solution for Backward-Facing Step Flow

    NASA Astrophysics Data System (ADS)

    Celik, Ismail; Parsons, Don; Karaismail, Ertan; Nanduri, Jagannath

    2007-11-01

    Flow past a backward facing step is a classical bench mark for both laminar and turbulent flow calculations. Due to the near-singular behavior arising from the presence of the sharp step, it is very difficult to predict the size of the recirculation region and the reattachment length. This difficulty, in turn, manifests itself as a significant discrepancy between predicted and measured velocity profiles. The aim of the current work is to formulate an analytical solution to the 2D, steady flow in question that satisfies the Navier-Stokes equations with a source term. The proposed solution is a superposition of two stream functions, one being a semi-potential solution that satisfies all the boundary conditions for real incompressible fluids, and another composed of rotational vortices (e.g. Rankine vortices) which enable flow separation. The location and distribution of the vortices is selected to emulate the Reynolds number dependence of the re-attachment length, while other parameters in the model are used to minimize the additional source term that is needed. The proposed solution can be primarily used in code-verification, and quantification of discretization errors in CFD (Computational Fluid Dynamics). It can also be used to assess modeling errors, by adding additional source terms that represent the spatial variations in turbulent-eddy viscosity, the key quantity used in Boussinesq-type turbulence models.

  15. Effects of Adverse Pressure Gradient on the Incompressible Reattaching Flow Over a Rearward-Facing Step

    NASA Technical Reports Server (NTRS)

    Kuehn, Donald M.

    1980-01-01

    The turbulent, incompressible reattaching flow over a rearward-facing step has been studied by many researchers over the years. One of the principal quantities determined in these experiments has been the distance from the step to the point (or region) where the separated shear layer reattaches to the surface (x(r)). The values for x(r)/h, where h is the step height, have covered a wider range than can reasonably be attributed to experimental technique or inaccuracy. Often the reason for a largely different value of x(r)/h can be attributed to an incompletely developed turbulent layer, or a transitional or laminar boundary layer. However, for the majority of experiments where the boundary layer is believed to be fully developed and turbulent, x(r)/h still varies several step heights; generally, 5 1/2 approximately < x(r)/h approximately < 7 1/2. This observed variation has usually been attributed to such variables as l/h (step length to height, h/delta (step height to initial boundary-layer thickness), R(e)(theta)), or the experimental technique for determining reattachment location. However, there are so many different combinations of variables in the previous experiments that it was not possible to sort out the effects of particular conditions on the location of reattachment. In the present experiment velocity profiles have been measured in and around the region of separated flow. Results show a large influence of adverse pressure gradient on the reattaching flow over a rearward-facing step that has not been reported previously. Further, the many previous experiments for fully developed, turbulent flow in parallel-walled channels have shown a range of reattachment location that has not been explained by differences in initial flow conditions. Although these initial flow conditions might contribute to the observed variation of reattachment location, it appears that the pressure gradient effect can explain most of that variation.

  16. Flow and forced-convection heat transfer over forward-facing double steps (effects of step ratio)

    SciTech Connect

    Shakouchi, Toshihiko; Kajino, Itsuki

    1994-07-01

    The flow and heat transfer over a step (a forward- or backward-facing step) result in complicated flow conditions, such as a shear flow field, flow separation, and generation of vortices, and provide some interesting information that improves understanding of the heat transfer on the surface. This is a very frequent flow, and basic to various kinds of chemical equipment, fluid machinery, combustion furnaces, and IC-packages. Recently, there have been many studies on this flow situation by numerical analysis, measurement of mean and fluctuating velocities within the separation bubble using laser Doppler anemometer, and heat transfer analysis. A flow passage having two steps in tiers (forward- or backward-facing double steps) is also frequent, and it is very important to clarify the effects of each step on the flow and the heat-transfer characteristics. This however, has not yet been investigated. This study presents the results of an experimental investigation on the flow and forced convective heat transfer over forward-facing single and double steps. Measurements of velocity and turbulence intensity, flow visualization, pressure distribution, and heat transfer over forward-facing double steps were carried out for various step ratios, L/a (L: step length, a: step height). From these results, the effects of the step ratio on the flow and heat-transfer characteristics were clarified and the following results were confirmed. Heat-transfer enhancement of a double step is considerable compared with that of a single step or a flat plate.

  17. Acoustic investigation of wall jet over a backward-facing step using a microphone phased array

    NASA Astrophysics Data System (ADS)

    Perschke, Raimund F.; Ramachandran, Rakesh C.; Raman, Ganesh

    2015-02-01

    The acoustic properties of a wall jet over a hard-walled backward-facing step of aspect ratios 6, 3, 2, and 1.5 are studied using a 24-channel microphone phased array at Mach numbers up to M=0.6. The Reynolds number based on inflow velocity and step height assumes values from Reh = 3.0 ×104 to 7.2 ×105. Flow without and with side walls is considered. The experimental setup is open in the wall-normal direction and the expansion ratio is effectively 1. In case of flow through a duct, symmetry of the flow in the spanwise direction is lost downstream of separation at all but the largest aspect ratio as revealed by oil paint flow visualization. Hydrodynamic scattering of turbulence from the trailing edge of the step contributes significantly to the radiated sound. Reflection of acoustic waves from the bottom plate results in a modulation of power spectral densities. Acoustic source localization has been conducted using a 24-channel microphone phased array. Convective mean-flow effects on the apparent source origin have been assessed by placing a loudspeaker underneath a perforated flat plate and evaluating the displacement of the beamforming peak with inflow Mach number. Two source mechanisms are found near the step. One is due to interaction of the turbulent wall jet with the convex edge of the step. Free-stream turbulence sound is found to be peaked downstream of the step. Presence of the side walls increases free-stream sound. Results of the flow visualization are correlated with acoustic source maps. Trailing-edge sound and free-stream turbulence sound can be discriminated using source localization.

  18. Effects of an aft facing step on the surface of a laminar flow glider wing

    NASA Technical Reports Server (NTRS)

    Sandlin, Doral R.; Saiki, Neal

    1993-01-01

    A motor glider was used to perform a flight test study on the effects of aft facing steps in a laminar boundary layer. This study focuses on two dimensional aft facing steps oriented spanwise to the flow. The size and location of the aft facing steps were varied in order to determine the critical size that will force premature transition. Transition over a step was found to be primarily a function of Reynolds number based on step height. Both of the step height Reynolds numbers for premature and full transition were determined. A hot film anemometry system was used to detect transition.

  19. Step Bunch Evolution on Vicinal Faces of KDP

    NASA Technical Reports Server (NTRS)

    Booth, N. A.; Chernov, A. A.; Vekilov, P. G.

    2003-01-01

    For in-situ studies of the formation and evolution of step patterns in solution growth, we have assembled an experimental setup based on Michelson interferometry with the growing crystal surface as one of the reflective surfaces. The device allows data collection over a relatively large area (approximately 4 sq. mm) in situ and in real time during growth. The depth resolution is improved over traditional interferometry using phase-shifted images combining by a suitable algorithm. We achieve a depth resolution of approximately 50 Angstroms. Lateral resolution, dependent on the degree of magnification, is around 0.3 to 5 microns. The crystal chosen as a model in this work is potassium dihydrogen phosphate (KDP), the optically non-linear material widely used in frequency doubling applications. Kinetics of KDP crystallization is well studied so that KDP can serve as a benchmark for our investigations. We present quantitative results on the onset, initial stages and development of instabilities in moving step trains on vicinal crystal surfaces at varying supersaturation, flow rate, and flow direction. The kinetics data suggest that at low supersaturations, step bunching is caused by impurity retardation of the steps, while at higher supersaturations, we link the non-linearity during growth to interdependence of the velocity and density of the steps evidenced in independent experiments. The behavior on the surface is very dynamic, small bunches both merge and split from larger bunches as they travel across the facet. We present evidence that despite these dynamics, under steady conditions there exists a limiting value to step bunch height. This height is reached at distances between 600 and 1000 microns from the step source. In our experiments, we observed the retention of this step bunch height limit up to the path of 1500 microns.

  20. The face hallucinating two-step framework using hallucinated high-resolution residual

    NASA Astrophysics Data System (ADS)

    Naleer, H. M. M.; Lu, Yao; An, Yaozu

    2011-06-01

    In video surveillance, the attention human faces are frequently of small size. Image hallucination is an imperative factor disturbing the face classification by human and computer. In this paper, we propose a two-step face hallucination framework by means of training data sets which have a small quantity of low and high resolution images. In the first step, the global face is constructed based on optimal weights of training images. In the second step, a local residual compensation method bases on position patch via residual training face image data sets. Moreover, the hallucinated highresolution residual image which is obtained by the identical process can be subsequent for the local face. Finally, the hallucinated high-resolution residual image is appended with the input low-resolution face image which is interpolated to the high-resolution image dimension by an upsampling factor. Experiments fully demonstrate that our framework is very flexible and accomplishs good performance via small training data sets.

  1. Performance characteristics of a curved-channel microchannel plate with a curved input face and a plane output face

    NASA Technical Reports Server (NTRS)

    Slater, David C.; Morgan, Jeffrey S.; Timothy, J. Gethyn

    1989-01-01

    The presently performance-evaluated format, in which a high-gain curved-channel microchannel plate (M2MCP) has a spherical concave input face and a plane output face, allows the input face of the MCP (1) to match such curved focal surfaces as that of a Rowland-circle spectrometer mounting, while (2) having a high-resolution plane readout array in proximity focus with the output face. This MCP has been evaluated in a discrete-anode multicathode microchannel array detector system. The saturated modal gain was found to be inversely proportional to the length/diameter ratio of the channels and directly proportional to the applied MCP voltage.

  2. Characteristics of channel steps and reach morphology in headwater streams, southeast Alaska

    NASA Astrophysics Data System (ADS)

    Gomi, Takashi; Sidle, Roy C.; Woodsmith, Richard D.; Bryant, Mason D.

    2003-03-01

    The effect of timber harvesting and mass movement on channel steps and reach morphology was examined in 16 headwater streams of SE Alaska. Channel steps formed by woody debris and boulders are significant channel units in headwater streams. Numbers, intervals, and heights of steps did not differ among management and disturbance regimes. A negative exponential relationship between channel gradient and mean length of step intervals was observed in the fluvial reaches (<0.25 unit gradient) of recent landslide and old-growth channels. No such relationship was found in upper reaches (≥0.25 gradient) where colluvial processes dominated. Woody debris and sediment recruitment from regenerating riparian stands may have obscured any strong relationship between step geometry and channel gradient in young alder, young conifer, and recent clear-cut channels. Channel reaches are described as pool-riffles, step-pools, step-steps, cascades, rapids, and bedrock. Geometry of channel steps principally characterized channel reach types. We infer that fluvial processes dominated in pool-riffle and step-pool reaches, while colluvial processes dominated in bedrock reaches. Step-step, rapids, and cascade reaches occurred in channels dominated by both fluvial processes and colluvial processes. Step-step reaches were transitional from cascades (upstream) to step-pool reaches (downstream). Woody debris recruited from riparian corridors and logging activities formed steps and then sequentially might modify channel reach types from step-pools to step-steps. Scour, runout, and deposition of sediment and woody debris from landslides and debris flows modified the distribution of reach types (bedrock, cascade, and step-pool) and the structure of steps within reaches.

  3. DNS and LES of Turbulent Backward-Facing Step Flow Using 2ND-and 4TH-Order Discretization

    NASA Astrophysics Data System (ADS)

    Meri, Adnan; Wengle, Hans

    Results are presented from a Direct Numerical Simulation (DNS) and Large-Eddy Simulations (LES) of turbulent flow over a backward-facing step (Reh=3300) with a fully developed channel flow (Rcτ=180) utilized asatime-dependent inflow condition. Numerical solutions using a fourth-order compact (Hermitian) scheme, which was formulated directly for anon-equidistant and staggered grid in [1] are compared with numerical solutions using the classical second-order central scheme. There sults from LES (using the dynamic subgrid scale model) are evaluated against a corresponding DNS reference data set (fourth-order solution).

  4. Suboptimal feedback control of turbulent flow over a backward-facing step

    NASA Astrophysics Data System (ADS)

    Kang, Seongwon; Choi, Haecheon

    2002-07-01

    The objective of the present numerical study is to increase mixing in turbulent flow behind a backward-facing step using a systematic feedback control method. Spatially and temporally varying blowing and suction with zero-net mass flow rate are provided at the step edge, based on the sensing of the spanwise distribution of the wall pressure fluctuations at a downstream location. The cost functional to be increased is the root-mean-square spanwise pressure-gradient fluctuations at the sensing location, which may be associated with mixing behind the backward-facing step. Given the cost functional, the actuation at the step edge is determined through the suboptimal feedback control procedure of Choi et al. (1993). Large-eddy simulations of turbulent flow are conducted at a Reynolds number of 5100 based on the step height and free-stream velocity. The results of suboptimal feedback controls are compared with those of non-feedback single-frequency actuations. In case of the suboptimal control, velocity and vorticity fluctuations substantially increase downstream of the backward-facing step as well as in the recirculation zone. As a result, the reattachment length is significantly reduced, as compared to those of uncontrolled flow and flow with single-frequency actuations. A simple open-loop control method is devised from the suboptimal feedback control result, producing nearly the same mixing enhancement as the feedback control.

  5. Assessment of secondary bubble formation on a backward-facing step geometry

    NASA Astrophysics Data System (ADS)

    Juste, G. L.; Fajardo, P.; Guijarro, A.

    2016-07-01

    Flow visualization experiments and numerical simulations were performed on a narrow three-dimensional backward-facing step (BFS) flow with the main objective of characterizing the secondary bubble appearing at the top wall. The BFS has been widely studied because of its geometrical simplicity as well as its ability to reproduce most of the flow features appearing in many applications in which separation occurs. A BFS test rig with an expansion ratio of 2 and two aspect ratios (AR = 4 and AR = 8) was developed. Tests were performed at range of Reynolds numbers ranging from 50 to 1000; visualization experiments provided a qualitative description of secondary bubble and wall-jet flows. Large eddy simulations were carried out with two different codes for validation. Numerical solutions, once validated with experimental data from the literature, were used to acquire a deeper understanding of the experimental visualizations, to characterize the secondary bubble as a function of the flow variables (Reynolds and AR) and to analyze the effect of the secondary bubble on primary reattachment length. Finally, to decouple the sidewall effects due to the non-slip condition and the intrinsic flow three-dimensionality, numerical experiments with free-slip conditions over the sidewalls were computed. The main differences were as follows: When the non-slip condition is used, the secondary bubble appears at a Reynolds number of approximately 200, increases with the Reynolds number, and is limited to a small part of the span. This recirculation zone interacts with the wall-jets and causes the maximum and minimum lengths in the reattachment line of the primary recirculation. Under free slip conditions, the recirculation bubble appears at a higher Reynolds number and covers the entire channel span.

  6. Laser holographic interferometric measurements of the flow behind a rearward facing step

    NASA Technical Reports Server (NTRS)

    Leonard, Rachel; Chokani, Ndaona

    1993-01-01

    A holographic interferometer has been designed, constructed, and evaluated in an experimental study of the supersonic flow over a rearward facing step. The nominal Mach number at the corner was 2.05 +/- 0.04 and the Reynolds number per inch was 11.9 x 10 exp 6. The holographic interferometric measurements were supplemented by classical measurements of surface pressure, oil flow, and schlieren visualization. The effects of step height and step width were examined. A method to determine the reattachment point from the interferograms was examined and found to be in good agreement with the other measurement techniques. The reattachment point moved closer to the step as the step height was decreased, but its location did not change with varying step width. In addition to providing surface data for the flow over a rearward facing step, this study provides quantitative off-surface density data and Mach number data throughout the flow, obtained from the holographic interferometry measurements, which are suited for code validation.

  7. Design of step composition gradient thin film transistor channel layers grown by atomic layer deposition

    SciTech Connect

    Ahn, Cheol Hyoun; Hee Kim, So; Gu Yun, Myeong; Koun Cho, Hyung

    2014-12-01

    In this study, we proposed the artificially designed channel structure in oxide thin-film transistors (TFTs) called a “step-composition gradient channel.” We demonstrated Al step-composition gradient Al-Zn-O (AZO) channel structures consisting of three AZO layers with different Al contents. The effects of stacking sequence in the step-composition gradient channel on performance and electrical stability of bottom-gate TFT devices were investigated with two channels of inverse stacking order (ascending/descending step-composition). The TFT with ascending step-composition channel structure (5 → 10 → 14 at. % Al composition) showed relatively negative threshold voltage (−3.7 V) and good instability characteristics with a reduced threshold voltage shift (Δ 1.4 V), which was related to the alignment of the conduction band off-set within the channel layer depending on the Al contents. Finally, the reduced Al composition in the initial layer of ascending step-composition channel resulted in the best field effect mobility of 4.5 cm{sup 2}/V s. We presented a unique active layer of the “step-composition gradient channel” in the oxide TFTs and explained the mechanism of adequate channel design.

  8. Active flow control over a backward-facing step using plasma actuation

    NASA Astrophysics Data System (ADS)

    Ruisi, R.; Zare-Behtash, H.; Kontis, K.; Erfani, R.

    2016-09-01

    Due to the more stringent aviation regulations on fuel consumption and noise reduction, the interest for smaller and mechanically less complex devices for flow separation control has increased. Plasma actuators are currently among the most studied typology of devices for active flow control purposes due to their small size and lightweight. In this study, a single dielectric barrier discharge (SDBD) actuator is used on a backward-facing step to assess its effects on the separated turbulent shear layer and its reattachment location. A range of actuating modulation frequencies, related to the natural frequencies of shear layer instability (flapping) and vortex shedding instability, are examined. The particle image velocimetry technique is used to analyse the flow over the step and the reattachment location. The bulk-flow experiments show negligible effects both on the shear layer and on the reattachment location for every frequency considered, and the actuator is not able to induce a sufficient velocity increase at the step separation point.

  9. Effect of initial conditions on turbulent reattachment downstream of a backward-facing step

    NASA Technical Reports Server (NTRS)

    Westphal, R. V.; Johnston, J. P.

    1984-01-01

    The reattachment of a fully turbulent, two-dimentional shear layer downstream of a backward-facing step has been studied experimentally. The work examines the effect of variations in inlet conditions on the process of reattachment. A series of experiments was conducted in a low-speed wind tunnel using specialized instrumentation suited to the highly turbulent reversing flow near reattachment. Accurate characterization of the time-mean features of the reattaching flows was possible. Assuming linear scaling normalized on distance from reattachment, distributions of normalized pressure coefficient and forward flow fraction, and time-averaged skin friction coefficient appear universal for two-dimensional reattachment, independent of initial conditions and step height, for given duct geometry (area ratio) and for high step-height Reyolds numbers with thin separating boundary layers. The results suggest universal flow structure in the reattachment zone.

  10. Effects of Forward- and Backward-Facing Steps on the Crossflow Receptivity and Stability in Supersonic Boundary Layers

    NASA Technical Reports Server (NTRS)

    Balakumar, P.; King, Rudolph A.; Eppink, Jenna L.

    2014-01-01

    The effects of forward- and backward-facing steps on the receptivity and stability of three-dimensional supersonic boundary layers over a swept wing with a blunt leading edge are numerically investigated for a freestream Mach number of 3 and a sweep angle of 30 degrees. The flow fields are obtained by solving the full Navier-Stokes equations. The evolution of instability waves generated by surface roughness is simulated with and without the forward- and backward-facing steps. The separation bubble lengths are about 5-10 step heights for the forward-facing step and are about 10 for the backward-facing step. The linear stability calculations show very strong instability in the separated region with a large frequency domain. The simulation results show that the presence of backward-facing steps decreases the amplitude of the stationary crossflow vortices with longer spanwise wavelengths by about fifty percent and the presence of forward-facing steps does not modify the amplitudes noticeably across the steps. The waves with the shorter wavelengths grow substantially downstream of the step in agreement with the linear stability prediction.

  11. Direct Numerical Simulation of Air Layer Drag Reduction over a Backward-facing Step

    NASA Astrophysics Data System (ADS)

    Kim, Dokyun; Moin, Parviz

    2010-11-01

    Direct Numerical Simulation (DNS) of two-phase flow is performed to investigate the air layer drag reduction (ALDR) phenomenon in turbulent flow over a backward-facing step. In their experimental study, Elbing et al. (JFM, 2008) have observed a stable air layer on an entire flat plate if air is injected beyond the critical air-flow rate. In the present study, air is injected at the step on the wall into turbulent water flow for ALDR. The Reynolds and Weber numbers based on the water properties and step height are 22,800 and 560, respectively. An inlet section length before the step is 3h and the post expansion length is 30h, where h is the step height. The total number of grid points is about 271 million for DNS. The level set method is used to track the phase interface and the structured-mesh finite volume solver is used with an efficient algorithm for two-phase DNS. Two cases with different air-flow rates are performed to investigate the mechanism and stability of air layer. For high air-flow rate, the stable air layer is formed on the plate and more than 90% drag reduction is obtained. In the case of low air-flow rate, the air layer breaks up and ALDR is not achieved. The parameters governing the stability of air layer from the numerical simulations is also consistent with the results of stability analysis.

  12. Film thickness measurement for spiral groove and Rayleigh step lift pad self-acting face seals

    NASA Technical Reports Server (NTRS)

    Dirusso, E.

    1982-01-01

    One Rayleigh step lift pad and three spiral groove self-acting face seal configurations were tested to measure film thickness and frictional torque as a function of shaft speed. The seals were tested at a constant face load of 73 N (16.4 lb) with ambient air at room temperature and atmospheric pressure as the fluid medium. The test speed range was from 7000 to 17,000 rpm. The measured film thickness was compared with theoretical data from mathematical models. The mathematical models overpredicted the measured film thickness at the lower speeds of the test speed range and underpredicted the measured film thickness at the higher speeds of the test speed range.

  13. Laminar CuO-water nano-fluid flow and heat transfer in a backward-facing step with and without obstacle

    NASA Astrophysics Data System (ADS)

    Togun, Hussein

    2016-03-01

    This paper presents a numerical investigate on CuO-water nano-fluid and heat transfer in a backward-facing step with and without obstacle. The range of Reynolds number varied from 75 to 225 with volume fraction on CuO nanoparticles varied from 1 to 4 % at constant heat flux was investigated. Continuity, momentum, and energy equations with finite volume method in two dimensions were employed. Four different configurations of backward-facing step (without obstacle, with obstacle of 1.5 mm, with obstacle of 3 mm, with obstacle of 4.5 mm) were considered to find the best thermal performance. The results show that the maximum augmentation in heat transfer was about 22 % for backward-facing step with obstacle of 4.5 mm and using CuO nanoparticles at Reynolds number of 225 compared with backward-facing step without obstacle. It is also observed that increase in size of recirculation region with increase of height obstacle on the channel wall has remarkable effect on thermal performance. The results also found that increases in Reynolds number, height obstacle, and volume fractions of CuO nanoparticles lead to increase of pressure drop.

  14. Flow regimes, bed morphology, and flow resistance in self-formed step-pool channels

    NASA Astrophysics Data System (ADS)

    Comiti, F.; Cadol, D.; Wohl, E.

    2009-04-01

    We used a mobile bed flume with scaled grain size distribution, channel geometry, and flow to examine morphology and hydraulics of stepped channels. We hypothesized that (1) step geometry and flow resistance differs significantly as a function of the range of grain sizes present, (2) a transition from nappe to skimming flow occurs in stepped channels with mobile beds for conditions similar to stepped spillways, and (3) the partitioning of flow resistance changes significantly when flow passes from nappe to skimming conditions. Results support each of these hypotheses and help to illuminate the complexity of V-Q relationships in stepped channels, in which a dramatic decrease in flow resistance and increase in velocity accompany the transition from nappe to skimming flow near step-forming events. Therefore, a single flow resistance equation applicable to both ordinary and large floods may not be ideal in stepped channels. Nonetheless, models based on dimensionless velocity and unit discharge appear more robust compared to those based on the Darcy-Weisbach friction factor.

  15. Stability of compressible boundary layers over a smooth backward-facing step

    NASA Technical Reports Server (NTRS)

    Ragab, S. A.; Nayfeh, A. H.; Krishna, R. C.

    1990-01-01

    An investigation is conducted into the determination of the credibility of interacting boundary layers in predicting compressible subsonic flows over smooth surface imperfections. The case of smooth backward-facing steps is considered. The predicted mean flows are compared with those obtained using a Navier-Stokes solver. Moreover, the linear 2-D compressible stability characteristics of both mean flows are compared. The results show that the interacting boundary-layer formulation produces accurate mean flows that yield accurate linear stability characteristics, such as growth rates and amplification factors.

  16. Stability of compressible boundary layers over a smooth backward-facing step

    NASA Technical Reports Server (NTRS)

    Ragab, S. A.; Nayfeh, A. H.; Krishna, R. C.

    1989-01-01

    An investigation is conducted into the determination of the credibility of interacting boundary layers in predicting compressible subsonic flows over smooth surface imperfections. The case of smooth backward-facing steps is considered. The predicted mean flows are compared with those obtained using a Navier-Stokes solver. Moreover, the linear 2-D compressible stability characteristics of both mean flows are compared. The results show that the interacting boundary-layer formulation produces accurate mean flows that yield accurate linear stability characteristics, such as growth rates and amplification factors.

  17. Solutions of turbulent backward-facing step flow with heat transfer using the finite volume method

    NASA Astrophysics Data System (ADS)

    Horstman, R. H.; Cochran, R. J.; Emergy, A. F.

    1995-03-01

    The heated turbulent flow over a backward-facing step is numerically solved using the commercial computational fluid dynamics program FLUENT. The methods used here consist of the default power-law upwinding scheme, default multigrid equation solution method and a standard k-epsilon turbulence model with wall functions. A total of four separate cases are reported. The four cases consist of combinations of partially and fully developed flow at the inlet with uniform or developed temperature profiles. Three mesh refinements are reported for each flow.

  18. Solutions of turbulent backward-facing step flow with heat transfer using the finite volume method

    SciTech Connect

    Horstman, R.H.; Cochran, R.J.; Emergy, A.F.

    1995-12-31

    The heated turbulent flow over a backward-facing step is numerically solved using the commercial computational fluid dynamics program FLUENT. The methods used here consist of the default power-law upwinding scheme, default multigrid equation solution method and a standard k-{var_epsilon} turbulence model with wall functions. A total of four separate cases are reported. The four cases consist of combinations of partially and fully developed flow at the inlet with uniform or developed temperature profiles. Three mesh refinements are reported for each flow.

  19. Applicability of the independence principle to subsonic turbulent flow over a swept rearward-facing step

    NASA Technical Reports Server (NTRS)

    Selby, G. V.

    1983-01-01

    Prandtl (1946) has concluded that for yawed laminar incompressible flows the streamwise flow is independent of the spanwise flow. However, Ashkenas and Riddell (1955) have reported that for turbulent flow the 'independence principle' does not apply to yawed flat plates. On the other hand, it was also found that this principle may be applicable to many turbulent flows. As the sweep angle is increased, a sweep angle is reached which defines the interval over which the 'independence principle' is valid. The results obtained in the present investigation indicate the magnitude of the critical angle for subsonic turbulent flow over a swept rearward-facing step.

  20. Numerical simulation of unsteady flow behind a backward-facing step by the vortex method

    NASA Astrophysics Data System (ADS)

    Noda, Toshiaki; Nakanishi, Yuji; Kamemoto, Kyoji

    1993-09-01

    In this study, a two-dimensional flow behind a backward-facing step was calculated by the boundary element method with the vortex method. As a result of this analysis, velocity distributions and flow patterns were obtained. A tendency of reattachment point approached the result of the experiment. Reynolds stress and RMS (Root Mean Square) velocity fluctuation were calculated by using velocity distributions. The flow patterns show the development of a recirculating region in the initial stage. The calculated results have a qualitative good agreement with that of the experiment.

  1. Backward-facing step measurements at low Reynolds number, Re(sub h)=5000

    NASA Technical Reports Server (NTRS)

    Jovic, Srba; Driver, David M.

    1994-01-01

    An experimental study of the flow over a backward-facing step at low Reynolds number was performed for the purpose of validating a direct numerical simulation (DNS) which was performed by the Stanford/NASA Center for Turbulence Research. Previous experimental data on back step flows were conducted at Reynolds numbers and/or expansion ratios which were significantly different from that of the DNS. The geometry of the experiment and the simulation were duplicated precisely, in an effort to perform a rigorous validation of the DNS. The Reynolds number used in the DNS was Re(sub h)=5100 based on step height, h. This was the maximum possible Reynolds number that could be economically simulated. The boundary layer thickness, d, was approximately 1.0 h in the simulation and the expansion ratio was 1.2. The Reynolds number based on the momentum thickness, Re(sub theta), upstream of the step was 610. All of these parameters were matched experimentally. Experimental results are presented in the form of tables, graphs and a floppy disk (for easy access to the data). An LDV instrument was used to measure mean velocity components and three Reynolds stresses components. In addition, surface pressure and skin friction coefficients were measured. LDV measurements were acquired in a measuring domain which included the recirculating flow region.

  2. Monodisperse and Polydisperse Particle Flow over a Backward Facing Step Preceding a Porous Medium

    NASA Astrophysics Data System (ADS)

    Chambers, Frank; Dange, Alok

    2011-11-01

    Computational Fluid Dynamic predictions were performed for the flow of monodisperse and polydisperse particles over a backward facing step with and without a porous medium downstream. The carrier fluid was air and the particles had a density of 500 kg/m3. Monodisperse particles with diameters of 10 and 40 microns and polydispersed particles from 1 to 50 microns with a Rosin-Rammler size distribution were used. The step had an expansion ratio of 2 and the step Reynolds numbers were 6550 and 10000. The k-epsilon RNG model with standard wall functions was used with FLUENT's discrete phase model for the particles. Velocity and particle residence time tracks were examined. The placement of the medium at 4.25h from the step was found to control the velocity profiles and the length of the recirculation zone while placement at 6.75h had negligible effects. The particle tracks show that more particles with lower Stokes number enter the recirculation zone while the particles with higher Stokes number tend to bypass the recirculation zone and move directly to the filter. The results for the monodispersed and the polydispersed particles appear virtually the same at low particle concentrations, but the polydispersed results provide a very good view of the phenomena.

  3. A comparative study of computational solutions to flow over a backward-facing step

    NASA Technical Reports Server (NTRS)

    Mizukami, M.; Georgiadis, N. J.; Cannon, M. R.

    1993-01-01

    A comparative study was conducted for computational fluid dynamic solutions to flow over a backward-facing step. This flow is a benchmark problem, with a simple geometry, but involves complicated flow physics such as free shear layers, reattaching flow, recirculation, and high turbulence intensities. Three Reynolds-averaged Navier-Stokes flow solvers with k-epsilon turbulence models were used, each using a different solution algorithm: finite difference, finite element, and hybrid finite element - finite difference. Comparisons were made with existing experimental data. Results showed that velocity profiles and reattachment lengths were predicted reasonably well by all three methods, while the skin friction coefficients were more difficult to predict accurately. It was noted that, in general, selecting an appropriate solver for each problem to be considered is important.

  4. Separated flow behind a backward-facing step under a stationary temperature disturbance

    NASA Astrophysics Data System (ADS)

    Boiko, A. V.; Dovgal, A. V.; Sorokin, A. M.

    2015-11-01

    The flow in the separation region of laminar boundary layer behind a rectangular backward-facing step has been experimentally examined under temperature non-uniformity of the flow. The data were obtained in a subsonic wind tunnel at Reynolds numbers M ≪ 1. The temperature disturbance was generated using a system of Peltier elements provided on the model surface upstream of the separation line. The effect of heating/cooling of the wall on the mean and fluctuating flow components was evaluated using hot-wire measurements. The experimental data were supplemented with calculations of linear-stability characteristics of model velocity profiles in the separated boundary layer. As a result, the response of the separated flow to a stationary thermal perturbation was revealed.

  5. Investigation of Particle Sampling Bias in the Shear Flow Field Downstream of a Backward Facing Step

    NASA Technical Reports Server (NTRS)

    Meyers, James F.; Kjelgaard, Scott O.; Hepner, Timothy E.

    1990-01-01

    The flow field about a backward facing step was investigated to determine the characteristics of particle sampling bias in the various flow phenomena. The investigation used the calculation of the velocity:data rate correlation coefficient as a measure of statistical dependence and thus the degree of velocity bias. While the investigation found negligible dependence within the free stream region, increased dependence was found within the boundary and shear layers. Full classic correction techniques over-compensated the data since the dependence was weak, even in the boundary layer and shear regions. The paper emphasizes the necessity to determine the degree of particle sampling bias for each measurement ensemble and not use generalized assumptions to correct the data. Further, it recommends the calculation of the velocity:data rate correlation coefficient become a standard statistical calculation in the analysis of all laser velocimeter data.

  6. Turbulent flow past a backward-facing step - A critical evaluation of two-equation models

    NASA Technical Reports Server (NTRS)

    Thangam, S.; Speziale, C. G.

    1992-01-01

    The ability of two-equation models to accurately predict separated flows is analyzed from a combined theoretical and computational standpoint. Turbulent flow past a backward facing step is chosen as a test case in an effort to resolve the variety of conflicting results that were published during the past decade concerning the performance of two-equation models. It is found that the errors in the reported predictions of the k-epsilon model have two major origins: (1) numerical problems arising from inadequate resolution, and (2) inaccurate predictions for normal Reynolds stress differences arising from the use of an isotropic eddy viscosity. Inadequacies in near wall modelling play a substantially smaller role. Detailed calculations are presented which strongly indicate the standard k-epsilon model - when modified with an independently calibrated anisotropic eddy viscosity - can yield surprisingly good predictions for the backstep problem.

  7. Progress in multi-channel image fusion for face image matching

    NASA Astrophysics Data System (ADS)

    DelMarco, Stephen

    2013-05-01

    Fusion techniques have proven to be very useful for many signal and image processing applications including image recognition, image registration, and biometric matching. Along with standard fusion techniques, hypercomplex image processing techniques have been developed recently. These techniques represent a form of image fusion in which several image components are combined to form a multi-channel image. The multi-channel imagery may be processed using hypercomplex transforms, such as the hypercomplex Fourier transform, for image matching and registration. In this paper we investigate performance of multi-channel image fusion for face image matching. We use 3-D color face imagery and investigate fusion of various combinations of grayscale intensity, color, and range information. We conduct a theoretical investigation to identify conditions under which matchers using image channel fusion provide superior matching performance relative to matchers fusing single channel image matching results. We present numerical performance results in the form of Receiver Operating Characteristics curves quantifying matching performance for verification hypothesis testing problems.

  8. A DPIV study of a starting flow downstream of a backward-facing step

    NASA Astrophysics Data System (ADS)

    Huang, H. T.; Fiedler, H. E.

    In this paper an experimental investigation of a starting water flow downstream of a backward-facing step is described. The Reynolds number of the asymptotic steady flow is Re 4300 based on the step height of s=2 cm and the free stream velocity of U=21.4 cm/s. Velocity measurements were performed with video-based DPIV (Digital Particle Image Velocimetry) at a sampling frequency of 25 Hz. The main purpose of this study is to reveal the temporal development of global structures which could not be analyzed with single-point probes. It was found that at initialization of the flow a regular vorticity street is formed, which collapses at a normalized time t*=U t/s 17 due to vorticity interactions. After this the flow is dominated by complicated vorticity roll-up and shedding dynamics in the recirculation region. The starting phase is terminated for t*>40. Prior to the collapse of the vorticity street values of 9 times the steady state asymptotic wall normal stress and of twice the steady state negative wall shear stress were observed. The early increasing slope of the reattachment length is constant over a time of approximately t*=8. The collapse of the vorticity street and the vorticity interactions thereafter cause fluctuations both in the velocity in the free shear layer and in the reattachment length. The fully developed flow has a dominant frequency corresponding to a Strouhal number St=fs/U 0.04.

  9. Dielectric barrier discharge plasma actuator to control turbulent flow downstream of a backward-facing step

    NASA Astrophysics Data System (ADS)

    Sujar-Garrido, P.; Benard, N.; Moreau, E.; Bonnet, J. P.

    2015-04-01

    The objective of these experiments was to determine the optimal forcing location and unsteady forcing actuation produced by a single dielectric barrier discharge plasma actuator for controlling the flow downstream of a backward-facing step. The investigated configuration is a 30-mm-height step mounted in a closed-loop wind tunnel. The flow velocity is fixed at 15 m/s, corresponding to a Reynolds number based on the step height equal to 3 × 104 ( Re θ = 1400). The control authority of the plasma discharge is highlighted by the time-averaged modification of the reattachment point and by the effects obtained on the turbulent dynamics of the reattached shear layer. Several locations of the device actuator are considered, and a parametric study of the input signal is investigated for each location. This procedure leads to the definition of an optimal control configuration regarding the minimization of the reattachment length. When the actuator—that produces an electrohydrodynamic force resulting in an electric wind jet—is located upstream the separation point, it can manipulate the first stages of the formation of the turbulent free shear layer and consequently to modify the flow dynamics. Maximum effects have been observed when the high voltage is burst modulated at a frequency f BM = 125 Hz with a duty-cycle of 50 %. This forcing corresponds to a Strouhal number based on the momentum thickness equal to 0.011, a value corresponding to the convective instability or Kelvin-Helmholtz instability of the separated shear layer.

  10. The Effect of Backward-Facing Step Height on Instability Growth and Breakdown in Swept Wing Boundary-Layer Transition

    NASA Technical Reports Server (NTRS)

    Eppink, Jenna L.; Wlezien, Richard W.; King, Rudolph A.; Choudhari, Meelan

    2015-01-01

    A low-speed experiment was performed on a swept at plate model with an imposed pressure gradient to determine the effect of a backward-facing step on transition in a stationary-cross flow dominated flow. Detailed hot-wire boundary-layer measurements were performed for three backward-facing step heights of approximately 36, 45, and 49% of the boundary-layer thickness at the step. These step heights correspond to a subcritical, nearly-critical, and critical case. Three leading-edge roughness configurations were tested to determine the effect of stationary-cross flow amplitude on transition. The step caused a local increase in amplitude of the stationary cross flow for the two larger step height cases, but farther downstream the amplitude decreased and remained below the baseline amplitude. The smallest step caused a slight local decrease in amplitude of the primary stationary cross flow mode, but the amplitude collapsed back to the baseline case far downstream of the step. The effect of the step on the amplitude of the primary cross flow mode increased with step height, however, the stationary cross flow amplitudes remained low and thus, stationary cross flow was not solely responsible for transition. Unsteady disturbances were present downstream of the step for all three step heights, and the amplitudes increased with increasing step height. The only exception is that the lower frequency (traveling crossflow-like) disturbance was not present in the lowest step height case. Positive and negative spikes in instantaneous velocity began to occur for the two larger step height cases and then grew in number and amplitude downstream of reattachment, eventually leading to transition. The number and amplitude of spikes varied depending on the step height and cross flow amplitude. Despite the low amplitude of the disturbances in the intermediate step height case, breakdown began to occur intermittently and the flow underwent a long transition region.

  11. KCNE1 divides the voltage sensor movement in KCNQ1/KCNE1 channels into two steps

    NASA Astrophysics Data System (ADS)

    Barro-Soria, Rene; Rebolledo, Santiago; Liin, Sara I.; Perez, Marta E.; Sampson, Kevin J.; Kass, Robert S.; Larsson, H. Peter

    2014-04-01

    The functional properties of KCNQ1 channels are highly dependent on associated KCNE-β subunits. Mutations in KCNQ1 or KCNE subunits can cause congenital channelopathies, such as deafness, cardiac arrhythmias and epilepsy. The mechanism by which KCNE1-β subunits slow the kinetics of KCNQ1 channels is a matter of current controversy. Here we show that KCNQ1/KCNE1 channel activation occurs in two steps: first, mutually independent voltage sensor movements in the four KCNQ1 subunits generate the main gating charge movement and underlie the initial delay in the activation time course of KCNQ1/KCNE1 currents. Second, a slower and concerted conformational change of all four voltage sensors and the gate, which opens the KCNQ1/KCNE1 channel. Our data show that KCNE1 divides the voltage sensor movement into two steps with widely different voltage dependences and kinetics. The two voltage sensor steps in KCNQ1/KCNE1 channels can be pharmacologically isolated and further separated by a disease-causing mutation.

  12. A permeation theory for single-file ion channels: One- and two-step models

    NASA Astrophysics Data System (ADS)

    Nelson, Peter Hugo

    2011-04-01

    How many steps are required to model permeation through ion channels? This question is investigated by comparing one- and two-step models of permeation with experiment and MD simulation for the first time. In recent MD simulations, the observed permeation mechanism was identified as resembling a Hodgkin and Keynes knock-on mechanism with one voltage-dependent rate-determining step [Jensen et al., PNAS 107, 5833 (2010)]. These previously published simulation data are fitted to a one-step knock-on model that successfully explains the highly non-Ohmic current-voltage curve observed in the simulation. However, these predictions (and the simulations upon which they are based) are not representative of real channel behavior, which is typically Ohmic at low voltages. A two-step association/dissociation (A/D) model is then compared with experiment for the first time. This two-parameter model is shown to be remarkably consistent with previously published permeation experiments through the MaxiK potassium channel over a wide range of concentrations and positive voltages. The A/D model also provides a first-order explanation of permeation through the Shaker potassium channel, but it does not explain the asymmetry observed experimentally. To address this, a new asymmetric variant of the A/D model is developed using the present theoretical framework. It includes a third parameter that represents the value of the "permeation coordinate" (fractional electric potential energy) corresponding to the triply occupied state n of the channel. This asymmetric A/D model is fitted to published permeation data through the Shaker potassium channel at physiological concentrations, and it successfully predicts qualitative changes in the negative current-voltage data (including a transition to super-Ohmic behavior) based solely on a fit to positive-voltage data (that appear linear). The A/D model appears to be qualitatively consistent with a large group of published MD simulations, but no

  13. Flow control of micro-ramps on supersonic forward-facing step flow

    NASA Astrophysics Data System (ADS)

    Qing-Hu, Zhang; Tao, Zhu; Shihe, Yi; Anping, Wu

    2016-05-01

    The effects of the micro-ramps on supersonic turbulent flow over a forward-facing step (FFS) was experimentally investigated in a supersonic low-noise wind tunnel at Mach number 3 using nano-tracer planar laser scattering (NPLS) and particle image velocimetry (PIV) techniques. High spatiotemporal resolution images and velocity fields of supersonic flow over the testing model were captured. The fine structures and their spatial evolutionary characteristics without and with the micro-ramps were revealed and compared. The large-scale structures generated by the micro-ramps can survive the downstream FFS flowfield. The micro-ramps control on the flow separation and the separation shock unsteadiness was investigated by PIV results. With the micro-ramps, the reduction in the range of the reversal flow zone in streamwise direction is 50% and the turbulence intensity is also reduced. Moreover, the reduction in the average separated region and in separation shock unsteadiness are 47% and 26%, respectively. The results indicate that the micro-ramps are effective in reducing the flow separation and the separation shock unsteadiness. Project supported by the National Natural Science Foundation of China (Grant Nos. 11172326 and 11502280).

  14. Nonstationary heat transfer in a channel containing saturated He II: stepped heat loading

    SciTech Connect

    Shaposhnikov, V.A.; Mikhailov, I.I.; Efimova, L.N.; Romchenko, D.G.

    1988-09-01

    Measurements have been made on the nonstationary temperature distribution in a channel containing saturated superfluid He II under countercurrent conditions with local heat input to the middle of the channel as a stepped function. A numerical method has been developed which incorporates the variable thermophysical parameters for the helium. Those parameters include local heat flux and thermal conductivity related to internal component convection, heat flux density, specific enthalpy and entropy, the Goerter-Mellink friction constant, and the Kapitza conductivity coefficient. Agreement of the variable-property calculations with experiment is evaluated. It is concluded that saturated He II responds to pulse loading as does underheated He II.

  15. Response of Step-pool Mountain Channels to Wildfire Under Changing Climate-fire Regimes

    NASA Astrophysics Data System (ADS)

    Chin, A.; O'Dowd, A. P.; Storesund, R.; Parker, A.; Roberts-Niemann, C.

    2013-12-01

    The western U.S. is becoming more susceptible to wildfire, even though wildfires have occurred throughout history and pre-history. Warming climates leading to drier conditions have increased the occurrence of wildfires. Fire suppression policies throughout the twentieth century have also allowed fuel loads to build and increased the potential for larger and more frequent fires. These trends have growing impacts on human society, as evidenced in increasing number of structures destroyed and related costs of firefighting and resulting damages. Besides the first-order effects of wildfire, such as burned vegetation and reduced infiltration capacities, changing climate-fire regimes have significant indirect effects on hydrologic and geomorphologic responses. This contribution explores how these changes affect the stability and functioning of step-pool mountain streams in the context of landscape evolution. Step-pool systems are stable features adjusted to the prevailing flow and channel morphology, serving important functions of energy dissipation in high-energy environments. Steps and pools are also important ecologically, as they provide diverse habitats for sensitive organisms. Whereas step-pool channels are typically restructured by flows with recurrence intervals often exceeding 50 years, these flows are reached more frequently under changing climate-fire regimes. Following the Waldo Canyon Fire of June/July 2012, one of several recent wildfires that spread along the Colorado Front Range, we track the stability, destruction, and re-development of step-pool systems in two basins in Pike National Forest using terrestrial LiDAR scanning and surveys of longitudinal profiles and cross sections. We document how the first geomorphologically significant event on 1 July 2013 obliterated the step-pool structure in Williams Canyon, widened river channels and lowered channel beds by as much as one meter. Changes in ecological character accompanied the conversion of channel

  16. Variation of nanopore diameter along porous anodic alumina channels by multi-step anodization.

    PubMed

    Lee, Kwang Hong; Lim, Xin Yuan; Wai, Kah Wing; Romanato, Filippo; Wong, Chee Cheong

    2011-02-01

    In order to form tapered nanocapillaries, we investigated a method to vary the nanopore diameter along the porous anodic alumina (PAA) channels using multi-step anodization. By anodizing the aluminum in either single acid (H3PO4) or multi-acid (H2SO4, oxalic acid and H3PO4) with increasing or decreasing voltage, the diameter of the nanopore along the PAA channel can be varied systematically corresponding to the applied voltages. The pore size along the channel can be enlarged or shrunken in the range of 20 nm to 200 nm. Structural engineering of the template along the film growth direction can be achieved by deliberately designing a suitable voltage and electrolyte together with anodization time. PMID:21456152

  17. Optofluidic refractive-index sensor in step-index fiber with parallel hollow micro-channel.

    PubMed

    Lee, H W; Schmidt, M A; Uebel, P; Tyagi, H; Joly, N Y; Scharrer, M; Russell, P St J

    2011-04-25

    We present a simple refractive index sensor based on a step-index fiber with a hollow micro-channel running parallel to its core. This channel becomes waveguiding when filled with a liquid of index greater than silica, causing sharp dips to appear in the transmission spectrum at wavelengths where the glass-core mode phase-matches to a mode of the liquid-core. The sensitivity of the dip-wavelengths to changes in liquid refractive index is quantified and the results used to study the dynamic flow characteristics of fluids in narrow channels. Potential applications of this fiber microstructure include measuring the optical properties of liquids, refractive index sensing, biophotonics and studies of fluid dynamics on the nanoscale. PMID:21643070

  18. A stepped leader model for lightning including charge distribution in branched channels

    SciTech Connect

    Shi, Wei; Zhang, Li; Li, Qingmin

    2014-09-14

    The stepped leader process in negative cloud-to-ground lightning plays a vital role in lightning protection analysis. As lightning discharge usually presents significant branched or tortuous channels, the charge distribution along the branched channels and the stochastic feature of stepped leader propagation were investigated in this paper. The charge density along the leader channel and the charge in the leader tip for each lightning branch were approximated by introducing branch correlation coefficients. In combination with geometric characteristics of natural lightning discharge, a stochastic stepped leader propagation model was presented based on the fractal theory. By comparing simulation results with the statistics of natural lightning discharges, it was found that the fractal dimension of lightning trajectory in simulation was in the range of that observed in nature and the calculation results of electric field at ground level were in good agreement with the measurements of a negative flash, which shows the validity of this proposed model. Furthermore, a new equation to estimate the lightning striking distance to flat ground was suggested based on the present model. The striking distance obtained by this new equation is smaller than the value estimated by previous equations, which indicates that the traditional equations may somewhat overestimate the attractive effect of the ground.

  19. Fabrication of parylene channels embedded in silicon using a single parylene deposition step

    NASA Astrophysics Data System (ADS)

    Tolstosheeva, Elena; Pimentel, João. V.; Schander, Andreas; Kempen, Ludger; Vellekoop, Michael; Lang, Walter

    2015-06-01

    In-situ integration of microfluidic channels into the microfabrication process flow of implantable microsystems is desirable, for example to enable efficient drug delivery. We propose a fabrication method for such microfluidic channels using parylene C, a biocompatible material whose inert nature favours water flow. A single deposition of parylene C enabled monolithical integration of fully-sealed micro-channels in a silicon substrate. The channel geometry was predefined by etching 100 μm-deep grooves into a silicon substrate. A PVC foil was fixed manually on the wafer and served as a top-cover for the grooves. The wafers were coated with the adhesion promoter AdPro Poly® and a 15 μm-thick parylene C film was deposited conformally into the grooves-foil enclosed space. The outgasing nature of the PVC foil hindered the adhesion of parylene C, allowing the foil to be peeled off easily from the parylene surface. The functionality of the fully-sealed parylene channels, embedded in the silicon wafer, was verified by injecting DI water with dispersed polystyrene microbeads (diameter 6 μm): the polystyrene beads were successfully transported along the channel. Further, a fully-sealed parylene chamber remained leak-tight throughout a stepwise application of hydrostatic pressures from 0.2 to 3.0 bar (15 s step-interval). In short, our parylene channels are: (1) suitable for microsystem drug-delivery; (2) in-situ enclosed hollow spaces embedded in the silicon substrate, realized with a single parylene deposition; (3) intact at hydrostatic pressures up to 3 bar.

  20. Flow resistance dynamics in step-pool stream channels: 1. Large woody debris and controls on total resistance

    USGS Publications Warehouse

    Wilcox, A.C.; Wohl, E.E.

    2006-01-01

    Flow resistance dynamics in step-pool channels were investigated through physical modeling using a laboratory flume. Variables contributing to flow resistance in step-pool channels were manipulated in order to measure the effects of various large woody debris (LWD) configurations, steps, grains, discharge, and slope on total flow resistance. This entailed nearly 400 flume runs, organized into a series of factorial experiments. Factorial analyses of variance indicated significant two-way and three-way interaction effects between steps, grains, and LWD, illustrating the complexity of flow resistance in these channels. Interactions between steps and LWD resulted in substantially greater flow resistance for steps with LWD than for steps lacking LWD. LWD position contributed to these interactions, whereby LWD pieces located near the lip of steps, analogous to step-forming debris in natural channels, increased the effective height of steps and created substantially higher flow resistance than pieces located farther upstream on step treads. Step geometry and LWD density and orientation also had highly significant effects on flow resistance. Flow resistance dynamics and the resistance effect of bed roughness configurations were strongly discharge-dependent; discharge had both highly significant main effects on resistance and highly significant interactions with all other variables. Copyright 2006 by the American Geophysical Union.

  1. Two-step aminoacylation of tRNA without channeling in Archaea

    PubMed Central

    Bhaskaran, Hari; Perona, John J.

    2011-01-01

    Catalysis of sequential reactions is often envisaged to occur by channeling of substrate between enzyme active sites without release into bulk solvent. However, while there are compelling physiological rationales for direct substrate transfer, proper experimental support for the hypothesis is often lacking, particularly for metabolic pathways involving RNA. Here we apply transient kinetics approaches developed to study channeling in bienzyme complexes, to an archaeal protein synthesis pathway featuring the misaminoacylated tRNA intermediate Glu-tRNAGln. Experimental and computational elucidation of a kinetic and thermodynamic framework for two-step cognate Gln-tRNAGln synthesis demonstrates that the misacylating aminoacyl-tRNA synthetase (GluRSND) and tRNA-dependent amidotransferase (GatDE) function sequentially without channeling. Instead, rapid processing of the misacylated tRNA intermediate by GatDE, and preferential elongation factor binding to the cognate Gln-tRNAGln, together permit accurate protein synthesis without formation of a binary protein-protein complex between GluRSND and GatDE. These findings establish an alternate paradigm for protein quality control via two-step pathways for cognate aminoacyl-tRNA formation. PMID:21726564

  2. Stepped inlet optical panel

    DOEpatents

    Veligdan, James T.

    2001-01-01

    An optical panel includes stacked optical waveguides having stepped inlet facets collectively defining an inlet face for receiving image light, and having beveled outlet faces collectively defining a display screen for displaying the image light channeled through the waveguides by internal reflection.

  3. Optimizing planar lipid bilayer single-channel recordings for high resolution with rapid voltage steps.

    PubMed Central

    Wonderlin, W F; Finkel, A; French, R J

    1990-01-01

    We describe two enhancements of the planar bilayer recording method which enable low-noise recordings of single-channel currents activated by voltage steps in planar bilayers formed on apertures in partitions separating two open chambers. First, we have refined a simple and effective procedure for making small bilayer apertures (25-80 micrograms diam) in plastic cups. These apertures combine the favorable properties of very thin edges, good mechanical strength, and low stray capacitance. In addition to enabling formation of small, low-capacitance bilayers, this aperture design also minimizes the access resistance to the bilayer, thereby improving the low-noise performance. Second, we have used a patch-clamp headstage modified to provide logic-controlled switching between a high-gain (50 G omega) feedback resistor for high-resolution recording and a low-gain (50 M omega) feedback resistor for rapid charging of the bilayer capacitance. The gain is switched from high to low before a voltage step and then back to high gain 25 microseconds after the step. With digital subtraction of the residual currents produced by the gain switching and electrostrictive changes in bilayer capacitance, we can achieve a steady current baseline within 1 ms after the voltage step. These enhancements broaden the range of experimental applications for the planar bilayer method by combining the high resolution previously attained only with small bilayers formed on pipette tips with the flexibility of experimental design possible with planar bilayers in open chambers. We illustrate application of these methods with recordings of the voltage-step activation of a voltage-gated potassium channel. PMID:1698470

  4. Misread protein creates membrane channels: an essential step in the bactericidal action of aminoglycosides.

    PubMed Central

    Davis, B D; Chen, L L; Tai, P C

    1986-01-01

    Among the pleiotropic effects of aminoglycosides, their irreversible uptake and their blockade of initiating ribosomes have appeared to explain their bactericidal action, while the contributions of translational misreading and membrane damage and the mechanism of that damage have remained uncertain. We now present evidence that incorporation of misread proteins into the membrane can account for the membrane damage. The bactericidal action thus appears to result from the following sequence, in which each step is essential: slight initial entry of the antibiotic; interaction with chain-elongating ribosomes, resulting in misreading; incorporation of misread protein into the membrane, creating abnormal channels; increased (and irreversible) entry through these channels, and hence increased misreading and formation of channels; and, finally, blockade of initiating ribosomes. This mechanism can account for several previously unexplained observations: that streptomycin uptake requires protein synthesis during, but not after, the lag before the membrane damage; that streptomycin-resistant cells, which fail to take up streptomycin, can do so after treatment by another aminoglycoside; and that puromycin at moderate concentrations accelerates streptomycin uptake, while high concentrations (which release shorter chains) prevent it. In addition, puromycin, prematurely releasing polypeptides of normal sequence, also evidently creates channels, since it is reported to promote streptomycin uptake even in streptomycin-resistant cells. These findings imply that normal membrane proteins must be selected not only for a hydrophobic anchoring surface, but also for a tight fit in the membrane. Images PMID:2426712

  5. An experimental study of turbulent diffusion flames established on a porous plate behind a backward-facing step

    SciTech Connect

    Rohmat, T.A.; Yoshihashi, Teruo; Obara, Tetsuro; Ohyagi, Shigeharu

    1999-07-01

    A study on diffusion flame established on a porous plate behind a backward-facing step disturbed in a parallel air stream was performed experimentally using an apparatus shown in a figure. As a turbulence generator, a turbulent grid or a cylinder was located upstream of the step. Methane was used as fuel and injected uniformly through a porous plate burner. Visualization of flame was performed by both direct and color schlieren photography. Thermal structures of the flame were measured using thin thermocouple and the data obtained were compensated digitally for thermal response.

  6. Phenomenological study of subsonic turbulent flow over a swept rearward-facing step. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Selby, G. V.

    1982-01-01

    The phenomenology of turbulent, subsonic flow over a swept, rearward-facing step was studied. Effects of variations in step height, sweep angle, base geometry, and end conditions on the 3-D separated flow were examined. The separated flow was visualized using smoke wire, oil drop, and surface tuft techniques. Measurements include surface pressure, reattachment distance and swirl angle. Results indicate: (1) model/test section coupling affects the structure of the separated flow, but spanwise end conditions do not; (2) the independence principle is evidently valid for sweep angles up to 38 deg; (3) a sweep angle/swirl angle correlation exists; and (4) base modifications can significantly reduce the reattachment distance.

  7. Comprehensive Approach to Verification and Validation of CFD Simulations Applied to Backward Facing Step-Application of CFD Uncertainty Analysis

    NASA Technical Reports Server (NTRS)

    Groves, Curtis E.; LLie, Marcel; Shallhorn, Paul A.

    2012-01-01

    There are inherent uncertainties and errors associated with using Computational Fluid Dynamics (CFD) to predict the flow field and there is no standard method for evaluating uncertainty in the CFD community. This paper describes an approach to -validate the . uncertainty in using CFD. The method will use the state of the art uncertainty analysis applying different turbulence niodels and draw conclusions on which models provide the least uncertainty and which models most accurately predict the flow of a backward facing step.

  8. Computation of turbulent flows over backward and forward-facing steps using a near-wall Reynolds stress model

    NASA Technical Reports Server (NTRS)

    Ko, Sung HO

    1993-01-01

    Separation and reattachment of turbulent shear layers is observed in many important engineering applications, yet it is poorly understood. This has motivated many studies on understanding and predicting the processes of separation and reattachment of turbulent shear layers. Both of the situations in which separation is induced by adverse pressure gradient, or by discontinuities of geometry, have attracted attention of turbulence model developers. Formulation of turbulence closure models to describe the essential features of separated turbulent flows accurately is still a formidable task. Computations of separated flows associated with sharp-edged bluff bodies are described. For the past two decades, the backward-facing step flow, the simplest separated flow, has been a popular test case for turbulence models. Detailed studies on the performance of many turbulence models, including two equation turbulence models and Reynolds stress models, for flows over steps can be found in the papers by Thangam & Speziale and Lasher & Taulbee). These studies indicate that almost all the existing turbulence models fail to accurately predict many important features of back step flow such as reattachment length, recovery rate of the redeveloping boundary layers downstream of the reattachment point, streamlines near the reattachment point, and the skin friction coefficient. The main objectives are to calculate flows over backward and forward-facing steps using the NRSM and to make use of the newest DNS data for detailed comparison. This will give insights for possible improvements of the turbulence model.

  9. First wide-angle view of channelized turbidity currents links migrating cyclic steps to flow characteristics

    NASA Astrophysics Data System (ADS)

    Hughes Clarke, John E.

    2016-06-01

    Field observations of turbidity currents remain scarce, and thus there is continued debate about their internal structure and how they modify underlying bedforms. Here, I present the results of a new imaging method that examines multiple surge-like turbidity currents within a delta front channel, as they pass over crescent-shaped bedforms. Seven discrete flows over a 2-h period vary in speed from 0.5 to 3.0 ms-1. Only flows that exhibit a distinct acoustically attenuating layer at the base, appear to cause bedform migration. That layer thickens abruptly downstream of the bottom of the lee slope of the bedform, and the upper surface of the layer fluctuates rapidly at that point. The basal layer is inferred to reflect a strong near-bed gradient in density and the thickening is interpreted as a hydraulic jump. These results represent field-scale flow observations in support of a cyclic step origin of crescent-shaped bedforms.

  10. Coarser and rougher: Effects of fine gravel pulses on experimental step-pool channel morphodynamics

    NASA Astrophysics Data System (ADS)

    Johnson, J. P. L.; Aronovitz, A. C.; Kim, W.

    2015-10-01

    Understanding how steep mountain rivers respond to natural and anthropogenic sediment supply perturbations is important for predicting effects of extreme events (e.g., floods and landslides) and for restoring rivers to more natural conditions. Using flume experiments, we show that stabilized step-pool-like channel beds can respond to pulses of finer gravel by becoming even coarser and rougher than before. Adding finer gravel initially reduces bed roughness and also increases the mobility of previously stable bed grains. Small- and intermediate-diameter clasts are then preferentially winnowed from the bed surface, leaving behind higher concentrations of even larger clasts. Ultimately, this results in both a coarser and rougher bed. Our experiments demonstrate that steep river beds become stable through the coevolution of bed roughness and surface grain size distribution and that these morphological variables can be sensitive to the history of upstream sediment supply.

  11. Large-eddy simulation of a backward facing step flow using a least-squares spectral element method

    NASA Technical Reports Server (NTRS)

    Chan, Daniel C.; Mittal, Rajat

    1996-01-01

    We report preliminary results obtained from the large eddy simulation of a backward facing step at a Reynolds number of 5100. The numerical platform is based on a high order Legendre spectral element spatial discretization and a least squares time integration scheme. A non-reflective outflow boundary condition is in place to minimize the effect of downstream influence. Smagorinsky model with Van Driest near wall damping is used for sub-grid scale modeling. Comparisons of mean velocity profiles and wall pressure show good agreement with benchmark data. More studies are needed to evaluate the sensitivity of this method on numerical parameters before it is applied to complex engineering problems.

  12. Thermal Unfolding of a Mammalian Pentameric Ligand-gated Ion Channel Proceeds at Consecutive, Distinct Steps*

    PubMed Central

    Tol, Menno B.; Deluz, Cédric; Hassaine, Gherici; Graff, Alexandra; Stahlberg, Henning; Vogel, Horst

    2013-01-01

    Pentameric ligand-gated ion channels (LGICs) play an important role in fast synaptic signal transduction. Binding of agonists to the β-sheet-structured extracellular domain opens an ion channel in the transmembrane α-helical region of the LGIC. How the structurally distinct and distant domains are functionally coupled for such central transmembrane signaling processes remains an open question. To obtain detailed information about the stability of and the coupling between these different functional domains, we analyzed the thermal unfolding of a homopentameric LGIC, the 5-hydroxytryptamine receptor (ligand binding, secondary structure, accessibility of Trp and Cys residues, and aggregation), in plasma membranes as well as during detergent extraction, purification, and reconstitution into artificial lipid bilayers. We found a large loss in thermostability correlating with the loss of the lipid bilayer during membrane solubilization and purification. Thermal unfolding of the 5-hydroxytryptamine receptor occurred in consecutive steps at distinct protein locations. A loss of ligand binding was detected first, followed by formation of different transient low oligomeric states of receptor pentamers, followed by partial unfolding of helical parts of the protein, which finally lead to the formation receptor aggregates. Structural destabilization of the receptor in detergents could be partially reversed by reconstituting the receptor into lipid bilayers. Our results are important because they quantify the stability of LGICs during detergent extraction and purification and can be used to create stabilized receptor proteins for structural and functional studies. PMID:23275379

  13. A critical comparison of several low Reynolds number k-epsilon turbulence models for flow over a backward facing step

    NASA Technical Reports Server (NTRS)

    Steffen, C. J., Jr.

    1993-01-01

    Turbulent backward-facing step flow was examined using four low turbulent Reynolds number k-epsilon models and one standard high Reynolds number technique. A tunnel configuration of 1:9 (step height: exit tunnel height) was used. The models tested include: the original Jones and Launder; Chien; Launder and Sharma; and the recent Shih and Lumley formulation. The experimental reference of Driver and Seegmiller was used to make detailed comparisons between reattachment length, velocity, pressure, turbulent kinetic energy, Reynolds shear stress, and skin friction predictions. The results indicated that the use of a wall function for the standard k-epsilon technique did not reduce the calculation accuracy for this separated flow when compared to the low turbulent Reynolds number techniques.

  14. Heat-transfer and pressure distributions for laminar separated flows downstream of rearward-facing steps with and without mass suction

    NASA Technical Reports Server (NTRS)

    Brown, R. D.; Jakubowski, A. K.

    1974-01-01

    Heat-transfer and pressure distributions were measured for laminar separated flows downstream of rearward-facing steps with and without mass suction. The flow conditions were such that the boundary-layer thickness was comparable to or larger than the step height. For both suction and no-suction cases, an increase in the step height resulted in a sharp decrease in the initial heat-transfer rates behind the step. Downstream, however, the heat transfer gradually recovered back to less than or near attached-flow values. Mass suction from the step base area increased the local heat-transfer rates; however, this effect was relatively weak for the laminar flows considered. Even removal of the entire approaching boundary layer raised the post-step heat-transfer rates only about 10 percent above the flatplate values. Post-step pressure distributions were found to depend on the entrainment conditions at separation. In the case of the solid-faced step, a sharp pressure drop behind the step was followed by a very short plateau and relatively fast recompression. For the slotted-step connected to a large plenum but without suction, the pressure drop at the base was much smaller and the downstream recompression more gradual than that for solid-faced step.

  15. First wide-angle view of channelized turbidity currents links migrating cyclic steps to flow characteristics.

    PubMed

    Hughes Clarke, John E

    2016-01-01

    Field observations of turbidity currents remain scarce, and thus there is continued debate about their internal structure and how they modify underlying bedforms. Here, I present the results of a new imaging method that examines multiple surge-like turbidity currents within a delta front channel, as they pass over crescent-shaped bedforms. Seven discrete flows over a 2-h period vary in speed from 0.5 to 3.0 ms(-1). Only flows that exhibit a distinct acoustically attenuating layer at the base, appear to cause bedform migration. That layer thickens abruptly downstream of the bottom of the lee slope of the bedform, and the upper surface of the layer fluctuates rapidly at that point. The basal layer is inferred to reflect a strong near-bed gradient in density and the thickening is interpreted as a hydraulic jump. These results represent field-scale flow observations in support of a cyclic step origin of crescent-shaped bedforms. PMID:27283503

  16. Various shapes of silicon freestanding microfluidic channels and microstructures in one-step lithography

    NASA Astrophysics Data System (ADS)

    Pal, Prem; Sato, Kazuo

    2009-05-01

    In this research, we have developed and demonstrated a fabrication method for the formation of various shapes of silicon freestanding microfluidic channels and microstructures in one-step photolithography. The fabrication process utilizes the silicon direct wafer bonding with silicon nitride as an intermediate layer, local oxidation of the silicon (LOCOS) process and wet anisotropic etching. Two different types of etchants (non-ionic surfactant (Triton-X-100) added and pure 25 wt% TMAH solutions) are used in series to perform silicon anisotropic etching. Surfactant-added tetramethyl ammonium hydroxide (TMAH) is employed to define the shapes of the structures, while pure TMAH is used to get high undercutting for their fast releasing. The non-ionic surfactant is preferred considering the complementary metal-oxide semiconductor (CMOS) post process issue of wet anisotropic etching. The undercutting at sharp and rounded concave corners, edges aligned along lang1 0 0rang directions, is measured and analyzed in both pure and surfactant-added TMAH solutions. Mask design issues that must be taken into consideration for the fabrication of desired shape and size structures are also presented.

  17. Numerical solution of turbulent flow past a backward facing step using a nonlinear K-epsilon model

    NASA Technical Reports Server (NTRS)

    Speziale, C. G.; Ngo, Tuan

    1987-01-01

    The problem of turbulent flow past a backward facing step is important in many technological applications and has been used as a standard test case to evaluate the performance of turbulence models in the prediction of separated flows. It is well known that the commonly used kappa-epsilon (and K-l) models of turbulence yield inaccurate predictions for the reattachment points in this problem. By an analysis of the mean vorticity transport equation, it will be argued that the intrinsically inaccurate prediction of normal Reynolds stress differences by the Kappa-epsilon and K-l models is a major contributor to this problem. Computations using a new nonlinear kappa-epsilon model (which alleviates this deficiency) are made with the TEACH program. Comparisons are made between the improved results predicted by this nonlinear kappa-epsilon model and those obtained from the linear kappa-epsilon model as well as from second-order closure models.

  18. Turbulent separated flow past a backward-facing step: A critical evaluation of two-equation turbulence models

    NASA Technical Reports Server (NTRS)

    Thangam, S.; Speziale, C. G.

    1991-01-01

    The ability of two-equation models to accurately predict separated flows is analyzed from a combined theoretical and computational standpoint. Turbulent flow past a backward facing step is chosen as a test case in an effort to resolve the variety of conflicting results that were published during the past decade concerning the performance of two-equation models. It is found that the errors in the reported predictions of the k-epsilon model have two major origins: (1) numerical problems arising from inadequate resolution, and (2) inaccurate predictions for normal Reynolds stress differences arising from the use of an isotropic eddy viscosity. Inadequacies in near wall modelling play a substantially smaller role. Detailed calculations are presented which strongly indicate the standard k-epsilon model - when modified with an independently calibrated anisotropic eddy viscosity - can yield surprisingly good predictions for the backstep problem.

  19. Solvent-dependent rate-limiting steps in the conformational change of sodium channel gating in squid giant axon.

    PubMed Central

    Kukita, F

    1997-01-01

    of the solution osmolarity. A predicted solute-inaccessible volume Va ranged (in nm3 per molecule) between 0.09 and 1.45. The value of Va increased as a logarithmic function of the molecular weight of the non-electrolyte. 8. This solute-inaccessible volume should be distributed in all hydrophilic parts of the sodium channel protein, but is not located in the channel conducting pore itself. The slowing of gating could be explained by a model in which a rate-limiting step is a hydration process that occurs after local small structural changes have exposed new, unhydrated faces (transient hydrated-states model). 9. Considering the opposite dependencies of parameters alpha (or gamma) and beta on the molecular weight, sodium channel gating is likely to reflect a combination of these two models, which are coupled in microscopic segment movements. We emphasize with this combination of models that fluctuating hydrophilic structures play an important role in determining time constants in the gating process. PMID:9023772

  20. Structure of backward facing step flow in low Reynolds number controlled by synthetic jet array with different injection velocities

    NASA Astrophysics Data System (ADS)

    Takano, Saneyuki

    2013-11-01

    This study presents detailed structure of separated flow downstream of a backward facing step affected by a non-uniform periodic disturbance along spanwise direction induced by synthetic jet array. The Reynolds number based on the step height ranged from 300 to 900. The frequency of the synthetic jet actuation was selected within the acceptance frequency range of separating shear layer. The periodic disturbance generates periodic transverse vortices whose size and shape change corresponding to the strength of the disturbance. The effect of different injection velocities in the synthetic jet array from those of adjacent jets on the transverse vortex structure and resulting reattachment process is discussed based on the wall shear stress measured by the Micro Flow Sensor (MFS) and flow visualization. Near wall behavior of the transverse vortex above the MFS was related to the sensor output. The results show that non-uniform injection velocity manipulated in the jet array induces difference in the distorted vortex structure and reattachment process in spanwise direction, which strongly depend on the Reynolds number and injection velocities of the synthetic jets.

  1. Flow resistance dynamics in step-pool channels: 2. Partitioning between grain, spill, and woody debris resistance

    USGS Publications Warehouse

    Wilcox, A.C.; Nelson, J.M.; Wohl, E.E.

    2006-01-01

    In step-pool stream channels, flow resistance is created primarily by bed sediments, spill over step-pool bed forms, and large woody debris (LWD). In order to measure resistance partitioning between grains, steps, and LWD in step-pool channels we completed laboratory flume runs in which total resistance was measured with and without grains and steps, with various LWD configurations, and at multiple slopes and discharges. Tests of additive approaches to resistance partitioning found that partitioning estimates are highly sensitive to the order in which components are calculated and that such approaches inflate the values of difficult-to-measure components that are calculated by subtraction from measured components. This effect is especially significant where interactions between roughness features create synergistic increases in resistance such that total resistance measured for combinations of resistance components greatly exceeds the sum of those components measured separately. LWD contributes large proportions of total resistance by creating form drag on individual pieces and by increasing the spill resistance effect of steps. The combined effect of LWD and spill over steps was found to dominate total resistance, whereas grain roughness on step treads was a small component of total resistance. The relative contributions of grain, spill, and woody debris resistance were strongly influenced by discharge and to a lesser extent by LWD density. Grain resistance values based on published formulas and debris resistance values calculated using a cylinder drag approach typically underestimated analogous flume-derived values, further illustrating sources of error in partitioning methods and the importance of accounting for interaction effects between resistance components. Copyright 2006 by the American Geophysical Union.

  2. Fully implicit solutions of the benchmark backward facing step problem using finite element discretization and inexact Newton's method

    SciTech Connect

    McHugh, P.R.; Knoll, D.A.

    1992-01-01

    A fully implicit solution algorithm based on Newton's method is used to solve the steady, incompressible Navier-Stokes and energy equations. An efficiently evaluated numerical Jacobian is used to simplify implementation, and mesh sequencing is used to increase the radius of convergence of the algorithm. We employ finite volume discretization using the power law scheme of Patankar to solve the benchmark backward facing step problem defined by the ASME K-12 Aerospace Heat Transfer Committee. LINPACK banded Gaussian elimination and the preconditioned transpose-free quasi-minimal residual (TFQMR) algorithm of Freund are studied as possible linear equation solvers. Implementation of the preconditioned TFQMR algorithm requires use of the switched evolution relaxation algorithm of Mulder and Van Leer to ensure convergence. The preconditioned TFQMR algorithm is more memory efficient than the direct solver, but our implementation is not as CPU efficient. Results show that for the level of grid refinement used, power law differencing was not adequate to yield the desired accuracy for this problem.

  3. Step density model of laser sustained ion channel and Coulomb explosion

    NASA Astrophysics Data System (ADS)

    Rajouria, Satish Kumar; Malik, H. K.; Tripathi, V. K.; Kumar, Pawan

    2015-02-01

    An analytical model of laser sustained ion channel in plasma is developed, assuming electron density to be zero in the inner region and constant outside. The radius of the channel is such that the ponderomotive force on electrons at the channel boundary is balanced by the channel space charge force. The laser is TM eigen mode of the system with Bessel function profile in the interior and modified Bessel function outside. The channel radius increases with laser intensity and the ratio of laser frequency to plasma frequency. Ion Coulomb explosion of the channel, on longer time scale, produces ion energy distribution, an increasing function of energy with a sharp cutoff equal to electron ponderomotive energy at the channel boundary. At peak laser intensity ≈2 ×1019W/cm 2 at 1 μm wavelength and spot size of 8 μm , the cutoff ion energy in a plasma of density ˜1019cm-3 is ˜0.73 MeV .

  4. Step density model of laser sustained ion channel and Coulomb explosion

    SciTech Connect

    Rajouria, Satish Kumar; Malik, H. K.; Tripathi, V. K.; Kumar, Pawan

    2015-02-15

    An analytical model of laser sustained ion channel in plasma is developed, assuming electron density to be zero in the inner region and constant outside. The radius of the channel is such that the ponderomotive force on electrons at the channel boundary is balanced by the channel space charge force. The laser is TM eigen mode of the system with Bessel function profile in the interior and modified Bessel function outside. The channel radius increases with laser intensity and the ratio of laser frequency to plasma frequency. Ion Coulomb explosion of the channel, on longer time scale, produces ion energy distribution, an increasing function of energy with a sharp cutoff equal to electron ponderomotive energy at the channel boundary. At peak laser intensity ≈2×10{sup 19}W/cm{sup 2} at 1 μm wavelength and spot size of 8 μm, the cutoff ion energy in a plasma of density ∼10{sup 19}cm{sup −3} is ∼0.73 MeV.

  5. The use of a linear Halbach array combined with a step-SPLITT channel for continuous sorting of magnetic species

    NASA Astrophysics Data System (ADS)

    Hoyos, Mauricio; Moore, Lee; Williams, P. Stephen; Zborowski, Maciej

    2011-05-01

    The Quadrupole Magnetic Sorter (QMS), employing an annular flow channel concentric with the aperture of a quadrupole magnet, is well established for cell and particle separations. Here we propose a magnetic particle separator comprising a linear array of cylindrical magnets, analogous to the array proposed by Klaus Halbach, mated to a substantially improved form of a parallel plate SPLITT channel, known as the step-SPLITT channel. While the magnetic force and throughput are generally lower than for the QMS, the new separator has advantages in ease of fabrication and the ability to vary the magnetic force to suit the separands. Preliminary experiments yield results consistent with prediction and show promise regarding future separations of cells of biomedical interest.

  6. Atypical Modulation of Face-Elicited Saccades in Autism Spectrum Disorder in a Double-Step Saccade Paradigm

    ERIC Educational Resources Information Center

    Senju, Atsushi; Kikuchi, Yukiko; Akechi, Hironori; Hasegawa, Toshikazu; Tojo, Yoshikuni; Osanai, Hiroo; Johnson, Mark H.

    2011-01-01

    Atypical development of face processing is a major characteristic in autism spectrum disorder (ASD), which could be due to atypical interactions between subcortical and cortical face processing. The current study investigated the saccade planning towards faces in ASD. Seventeen children with ASD and 17 typically developing (TD) children observed a…

  7. Dynamics of premixed flames in a narrow channel with a step-wise wall temperature

    SciTech Connect

    Kurdyumov, Vadim N.; Pizza, Gianmarco; Frouzakis, Christos E.; Mantzaras, John

    2009-11-15

    The effect of channel height, inflow velocity and wall temperature on the dynamics and stability of unity Lewis number premixed flames in channels with specified wall temperature is investigated with steady and transient numerical simulations using a two-dimensional thermo-diffusive model. The simplified model is capable of capturing many of the transitions and the combustion modes observed experimentally and in direct numerical simulations in micro- and meso-scale channels, and indicates that the thermal flame/wall interaction is the mechanism leading to the observed flame instabilities. Finally, an ad-hoc one-dimensional model based on the flame-sheet approximation is tested in its capacity to reproduce some of the flame dynamics of the two-dimensional thermo-diffusive model. (author)

  8. A Power-Efficient Clustering Protocol for Coal Mine Face Monitoring with Wireless Sensor Networks Under Channel Fading Conditions.

    PubMed

    Ren, Peng; Qian, Jiansheng

    2016-01-01

    This study proposes a novel power-efficient and anti-fading clustering based on a cross-layer that is specific to the time-varying fading characteristics of channels in the monitoring of coal mine faces with wireless sensor networks. The number of active sensor nodes and a sliding window are set up such that the optimal number of cluster heads (CHs) is selected in each round. Based on a stable expected number of CHs, we explore the channel efficiency between nodes and the base station by using a probe frame and the joint surplus energy in assessing the CH selection. Moreover, the sending power of a node in different periods is regulated by the signal fade margin method. The simulation results demonstrate that compared with several common algorithms, the power-efficient and fading-aware clustering with a cross-layer (PEAFC-CL) protocol features a stable network topology and adaptability under signal time-varying fading, which effectively prolongs the lifetime of the network and reduces network packet loss, thus making it more applicable to the complex and variable environment characteristic of a coal mine face. PMID:27338380

  9. A Power-Efficient Clustering Protocol for Coal Mine Face Monitoring with Wireless Sensor Networks Under Channel Fading Conditions

    PubMed Central

    Ren, Peng; Qian, Jiansheng

    2016-01-01

    This study proposes a novel power-efficient and anti-fading clustering based on a cross-layer that is specific to the time-varying fading characteristics of channels in the monitoring of coal mine faces with wireless sensor networks. The number of active sensor nodes and a sliding window are set up such that the optimal number of cluster heads (CHs) is selected in each round. Based on a stable expected number of CHs, we explore the channel efficiency between nodes and the base station by using a probe frame and the joint surplus energy in assessing the CH selection. Moreover, the sending power of a node in different periods is regulated by the signal fade margin method. The simulation results demonstrate that compared with several common algorithms, the power-efficient and fading-aware clustering with a cross-layer (PEAFC-CL) protocol features a stable network topology and adaptability under signal time-varying fading, which effectively prolongs the lifetime of the network and reduces network packet loss, thus making it more applicable to the complex and variable environment characteristic of a coal mine face. PMID:27338380

  10. The K+ battery-regulating Arabidopsis K+ channel AKT2 is under the control of multiple post-translational steps

    PubMed Central

    Michard, Erwan; Rocha, Marcio; Gomez-Porras, Judith L; González, Wendy; Corrâa, Luiz Gustavo Guedes; Ramírez-Aguilar, Santiago J; Cuin, Tracey Ann

    2011-01-01

    Potassium (K+) is an important nutrient for plants. It serves as a cofactor of various enzymes and as the major inorganic solute maintaining plant cell turgor. In a recent study, an as yet unknown role of K+ in plant homeostasis was shown. It was demonstrated that K+ gradients in vascular tissues can serve as an energy source for phloem (re)loading processes and that the voltage-gated K+ channels of the AKT2-type play a unique role in this process. The AKT2 channel can be converted by phosphorylation of specific serine residues (S210 and S329) into a non-rectifying channel that allows a rapid efflux of K+ from the sieve element/companion cells (SE/CC) complex. The energy of this flux is used by other transporters for phloem (re)loading processes. Nonetheless, the results do indicate that post-translational modifications at S210 and S329 alone cannot explain AKT2 regulation. Here, we discuss the existence of multiple post-translational modification steps that work in concert to convert AKT2 from an inward-rectifying into a non-rectifying K+ channel. PMID:21445013

  11. Thin Film Complementary Metal Oxide Semiconductor (CMOS) Device Using a Single-Step Deposition of the Channel Layer

    PubMed Central

    Nayak, Pradipta K.; Caraveo-Frescas, J. A.; Wang, Zhenwei; Hedhili, M. N.; Wang, Q. X.; Alshareef, H. N.

    2014-01-01

    We report, for the first time, the use of a single step deposition of semiconductor channel layer to simultaneously achieve both n- and p-type transport in transparent oxide thin film transistors (TFTs). This effect is achieved by controlling the concentration of hydroxyl groups (OH-groups) in the underlying gate dielectrics. The semiconducting tin oxide layer was deposited at room temperature, and the maximum device fabrication temperature was 350°C. Both n and p-type TFTs showed fairly comparable performance. A functional CMOS inverter was fabricated using this novel scheme, indicating the potential use of our approach for various practical applications. PMID:24728223

  12. Thin film complementary metal oxide semiconductor (CMOS) device using a single-step deposition of the channel layer.

    PubMed

    Nayak, Pradipta K; Caraveo-Frescas, J A; Wang, Zhenwei; Hedhili, M N; Wang, Q X; Alshareef, H N

    2014-01-01

    We report, for the first time, the use of a single step deposition of semiconductor channel layer to simultaneously achieve both n- and p-type transport in transparent oxide thin film transistors (TFTs). This effect is achieved by controlling the concentration of hydroxyl groups (OH-groups) in the underlying gate dielectrics. The semiconducting tin oxide layer was deposited at room temperature, and the maximum device fabrication temperature was 350 °C. Both n and p-type TFTs showed fairly comparable performance. A functional CMOS inverter was fabricated using this novel scheme, indicating the potential use of our approach for various practical applications. PMID:24728223

  13. Heat Transfer in a Liquid Metal Flowing Turbulently through a Channel with a Step Function Boundary Temperature

    NASA Technical Reports Server (NTRS)

    Poppendiek, H. F.

    1959-01-01

    An analytical heat transfer solution is derived and evaluated for the general case of a turbulently flowing liquid metal which suddenly encounters a step-function boundary temperature in a channel system. Local Nusselt moduli, dimensionless mixed-mean fluid temperatures, and arithmetic-mean Nusselt moduli are given as functions of Reynolds and Prandtl moduli and a dimensionless axial-distance modulus. These solutions are compared with known solutions of more specific systems as well as with a set of experimental liquid-metal heat transfer data for a thermal entrance region.

  14. A family of variable step-size affine projection adaptive filter algorithms using statistics of channel impulse response

    NASA Astrophysics Data System (ADS)

    Shams Esfand Abadi, Mohammad; AbbasZadeh Arani, Seyed Ali Asghar

    2011-12-01

    This paper extends the recently introduced variable step-size (VSS) approach to the family of adaptive filter algorithms. This method uses prior knowledge of the channel impulse response statistic. Accordingly, optimal step-size vector is obtained by minimizing the mean-square deviation (MSD). The presented algorithms are the VSS affine projection algorithm (VSS-APA), the VSS selective partial update NLMS (VSS-SPU-NLMS), the VSS-SPU-APA, and the VSS selective regressor APA (VSS-SR-APA). In VSS-SPU adaptive algorithms the filter coefficients are partially updated which reduce the computational complexity. In VSS-SR-APA, the optimal selection of input regressors is performed during the adaptation. The presented algorithms have good convergence speed, low steady state mean square error (MSE), and low computational complexity features. We demonstrate the good performance of the proposed algorithms through several simulations in system identification scenario.

  15. Transverse injection into Mach 2 flow behind a rearward-facing step - A 3-D, compressible flow test case for hypersonic combustor CFD validation

    SciTech Connect

    Mcdaniel, J.C.; Fletcher, D.G.; Hartfield, R.J.; Hollo, S.D. NASA, Ames Research Center, Moffett Field, CA )

    1991-12-01

    A spatially-complete data set of the important primitive flow variables is presented for the complex, nonreacting, 3D unit combustor flow field employing transverse injection into a Mach 2 flow behind a rearward-facing step. A unique wind tunnel facility providing the capability for iodine seeding was built specifically for these measurements. Two optical techniques based on laser-induced-iodine fluorescence were developed and utilized for nonintrusive, in situ flow field measurements. LDA provided both mean and fluctuating velocity component measurements. A thermographic phosphor wall temperature measurement technique was developed and employed. Data from the 2D flow over a rearward-facing step and the complex 3D mixing flow with injection are reported. 25 refs.

  16. Membrane Tension Accelerates Rate-limiting Voltage-dependent Activation and Slow Inactivation Steps in a Shaker Channel

    PubMed Central

    Laitko, Ulrike; Morris, Catherine E.

    2004-01-01

    A classical voltage-sensitive channel is tension sensitive—the kinetics of Shaker and S3–S4 linker deletion mutants change with membrane stretch (Tabarean, I.V., and C.E. Morris. 2002. Biophys. J. 82:2982–2994.). Does stretch distort the channel protein, producing novel channel states, or, more interestingly, are existing transitions inherently tension sensitive? We examined stretch and voltage dependence of mutant 5aa, whose ultra-simple activation (Gonzalez, C., E. Rosenman, F. Bezanilla, O. Alvarez, and R. Latorre. 2000. J. Gen. Physiol. 115:193–208.) and temporally matched activation and slow inactivation were ideal for these studies. We focused on macroscopic patch current parameters related to elementary channel transitions: maximum slope and delay of current rise, and time constant of current decline. Stretch altered the magnitude of these parameters, but not, or minimally, their voltage dependence. Maximum slope and delay versus voltage with and without stretch as well as current rising phases were well described by expressions derived for an irreversible four-step activation model, indicating there is no separate stretch-activated opening pathway. This model, with slow inactivation added, explains most of our data. From this we infer that the voltage-dependent activation path is inherently stretch sensitive. Simulated currents for schemes with additional activation steps were compared against datasets; this showed that generally, additional complexity was not called for. Because the voltage sensitivities of activation and inactivation differ, it was not possible to substitute depolarization for stretch so as to produce the same overall PO time course. What we found, however, was that at a given voltage, stretch-accelerated current rise and decline almost identically—normalized current traces with and without stretch could be matched by a rescaling of time. Rate-limitation of the current falling phase by activation was ruled out. We hypothesize

  17. Membrane tension accelerates rate-limiting voltage-dependent activation and slow inactivation steps in a Shaker channel.

    PubMed

    Laitko, Ulrike; Morris, Catherine E

    2004-02-01

    A classical voltage-sensitive channel is tension sensitive--the kinetics of Shaker and S3-S4 linker deletion mutants change with membrane stretch (Tabarean, I.V., and C.E. Morris. 2002. Biophys. J. 82:2982-2994.). Does stretch distort the channel protein, producing novel channel states, or, more interestingly, are existing transitions inherently tension sensitive? We examined stretch and voltage dependence of mutant 5aa, whose ultra-simple activation (Gonzalez, C., E. Rosenman, F. Bezanilla, O. Alvarez, and R. Latorre. 2000. J. Gen. Physiol. 115:193-208.) and temporally matched activation and slow inactivation were ideal for these studies. We focused on macroscopic patch current parameters related to elementary channel transitions: maximum slope and delay of current rise, and time constant of current decline. Stretch altered the magnitude of these parameters, but not, or minimally, their voltage dependence. Maximum slope and delay versus voltage with and without stretch as well as current rising phases were well described by expressions derived for an irreversible four-step activation model, indicating there is no separate stretch-activated opening pathway. This model, with slow inactivation added, explains most of our data. From this we infer that the voltage-dependent activation path is inherently stretch sensitive. Simulated currents for schemes with additional activation steps were compared against datasets; this showed that generally, additional complexity was not called for. Because the voltage sensitivities of activation and inactivation differ, it was not possible to substitute depolarization for stretch so as to produce the same overall PO time course. What we found, however, was that at a given voltage, stretch-accelerated current rise and decline almost identically--normalized current traces with and without stretch could be matched by a rescaling of time. Rate-limitation of the current falling phase by activation was ruled out. We hypothesize, therefore

  18. A critical comparison of several low Reynolds number k-epsilon turbulence models for flow over a backward-facing step

    NASA Technical Reports Server (NTRS)

    Steffen, Christopher J., Jr.

    1993-01-01

    Turbulent backward-facing step flow was examined using four low turbulent Reynolds number k-epsilon models and one standard high Reynolds number technique. A tunnel configuration of 1:9 (step height: exit tunnel height) was used. The models tested include: the original Jones and Launder; Chien; Launder and Sharma; and the recent Shih and Lumley formulation. The experimental reference of Driver and Seegmiller was used to make detailed comparisons between reattachment length, velocity, pressure, turbulent kinetic energy, Reynolds shear stress, and skin friction predictions. The results indicated that the use of a wall function for the standard k-epsilon technique did not reduce the calculation accuracy for this separated flow when compared to the low turbulent Reynolds number techniques.

  19. A critical comparison of several low Reynolds number k-epsilon turbulence models for flow over a backward-facing step

    NASA Astrophysics Data System (ADS)

    Steffen, Christopher J., Jr.

    1993-06-01

    Turbulent backward-facing step flow was examined using four low turbulent Reynolds number k-epsilon models and one standard high Reynolds number technique. A tunnel configuration of 1:9 (step height: exit tunnel height) was used. The models tested include: the original Jones and Launder; Chien; Launder and Sharma; and the recent Shih and Lumley formulation. The experimental reference of Driver and Seegmiller was used to make detailed comparisons between reattachment length, velocity, pressure, turbulent kinetic energy, Reynolds shear stress, and skin friction predictions. The results indicated that the use of a wall function for the standard k-epsilon technique did not reduce the calculation accuracy for this separated flow when compared to the low turbulent Reynolds number techniques.

  20. Co-evolving Physical and Biological Organization in Step-pool Channels: Experiments from a Restoration Reach on Wildcat Creek, California

    NASA Astrophysics Data System (ADS)

    Chin, A.; O'Dowd, A. P.; Mendez, P. K.; Velasco, K. Z.; Leventhal, R. D.; Storesund, R.; Laurencio, L. R.

    2014-12-01

    Step-pools are important features in fluvial systems. Through energy dissipation, step-pools provide stability in high-energy environments that otherwise may erode and degrade. Although research has focused on geomorphological aspects of step-pool channels, the ecological significance of step-pool streams is increasingly recognized. Step-pool streams often contain higher density and diversity of benthic macroinvertebrates and are critical habitats for organisms such as salmonids and tailed frogs. Step-pools are therefore increasingly used to restore eroding channels and improve ecological conditions. This paper addresses a restoration reach of Wildcat Creek in Berkeley, California that featured an installation of step-pools in 2012. The design framework recognized step-pool formation as a self-organizing process that produces a rhythmic morphology. After placing step particles at locations where step-pools are expected to form according to hydraulic theory, the self-organizing approach allowed fluvial processes to refine the rocks into adjusted sequences over time. In addition, a 30-meter "experimental" reach was created to explore the co-evolution of geomorphological and ecological characteristics. After constructing a plane bed channel, boulders and cobbles piled at the upstream end allowed natural flows to mobilize and sort them into step-pool sequences. Ground surveys and LiDAR recorded the development of step-pool sequences over several seasons. Concurrent sampling of benthic macroinvertebrates documented the formation of biological communities in conjunction with habitat. Biological sampling in an upstream reference reach provided a comparison with the restored reach over time. Results to date show an emergent step-pool channel with steps that segment the plane bed into initial step and pool habitats. Biological communities are beginning to form, showing more distinction among habitat types during some seasons, although they do not yet approach reference

  1. Implementation of 3DPTV for turbulence analysis and subgrid-scale stress model testing of a backward-facing step flow

    NASA Astrophysics Data System (ADS)

    Dona, Nicholas

    Large-Eddy Simulation (LES) is a constantly-expanding field with many new applications and models being introduced on a regular basis. The active nature of this field establishes the need for high-resolution, 3-dimensional experimental data for assessment and development of Subgrid-Scale (SGS) Models. An experimental technique well-suited to this application is Three-Dimensional Particle Tracking Velocimetry (3DPTV) utilizing the epipolar line triangulation method is an accepted method of quantifying volumes of 3-Dimension 3-Component (3D3C) velocity vector fields. This study adapted the epipolar line search triangulation methodology, as it was applied in micro-scale systems, to a backward-facing step flow in a small-scale water tunnel testing facility. The camera system, consisting of three 4008 x 2672 CCDs, was aligned and calibrated using a custom grid and dot target plate mounted on a purpose-built rig, containing a precision single-axis translation stage. Dual-pulsed, Nd:YAG lasers at 532 nm, 120mJ/pulse, illuminated the 28 mm x 18 mm x 4.5 mm volume of interest, located downstream of a 2.858 cm step in a 15.24 cm x 30.48 cm cross-section water tunnel. The turbulent flow, uin = 22cm/s, Reh=6274, Rlambda ≈ 130, and ER=1.208 was seeded with TiO2 particles, <5mum diameter, to maintain one-way coupling. The resulting 3DPTV system was shown to have uncertainty comparable to that of previous experimentation. Utilizing the acquired data, a priori testing of universally notable LES SGS Models, including the Smagorinsky, Similarity, Mixed, Coherent Structures, and Dynamic Models was accomplished and results are presented and discussed. This application of 3DPTV to a turbulent, backward-facing step flow and the results presented herein not only establish the technique as a promising source of experimental data in the development of LES, it lays a foundation for future study of the phenomena-rich backward-facing step flow and the testing and development of new LES SGS

  2. Self-Assembly of Synthetic Metabolons through Synthetic Protein Scaffolds: One-Step Purification, Co-immobilization, and Substrate Channeling

    SciTech Connect

    You, C; Zhang, YHP

    2013-02-01

    One-step purification of a multi-enzyme complex was developed based on a mixture of cell extracts containing three dockerin-containing enzymes and one family 3 cellulose-binding module (CBM3)-containing scaffoldin through high-affinity adsorption on low-cost solid regenerated amorphous cellulose (RAC). The three-enzyme complex, called synthetic metabolon, was self-assembled through the high-affinity interaction between the dockerin in each enzyme and three cohesins in the synthetic scaffoldin. The metabolons were either immobilized on the external surface of RAC or free when the scaffoldin contained an intein between the CBM3 and three cohesins. The immobilized and free metabolons containing triosephosphate isomerase, aldolase, and fructose 1,6-biphosphatase exhibited initial reaction rates 48 and 38 times, respectively, that of the non-complexed three-enzyme mixture at the same enzyme loading. Such reaction rate enhancements indicated strong substrate channeling among synthetic metabolons due to the close spatial organization among cascade enzymes. These results suggested that the construction of synthetic metabolons by using cohesins, dockerins, and cellulose-binding modules from cellulosomes not only decreased protein purification labor and cost for in vitro synthetic biology projects but also accelerated reaction rates by 1 order of magnitude compared to non-complexed enzymes. Synthetic metabolons would be an important biocatalytic module for in vitro and in vivo synthetic biology projects.

  3. An Experimental Study of a Separated/Reattached Flow Behind a Backward-Facing Step. Re(sub h) = 37,000

    NASA Technical Reports Server (NTRS)

    Jovic, Srba

    1996-01-01

    An experimental study was carried out to investigate turbulent structure of a two-dimensional incompressible separating/reattaching boundary layer behind a backward-facing step. Hot-wire measurement technique was used to measure three Reynolds stresses and higher-order mean products of velocity fluctuations. The Reynolds number, Re(sub h), based on the step height, h, and the reference velocity, U(sub 0), was 37,000. The upstream oncoming flow was fully developed turbulent boundary layer with the Re(sub theta) = 3600. All turbulent properties, such as Reynolds stresses, increase dramatically downstream of the step within an internally developing mixing layer. Distributions of dimensionless mean velocity, turbulent quantities and antisymmetric distribution of triple velocity products in the separated free shear layer suggest that the shear layer above the recirculating region strongly resembles free-shear mixing layer structure. In the reattachment region close to the wall, turbulent diffusion term balances the rate of dissipation since advection and production terms appear to be negligibly small. Further downstream, production and dissipation begin to dominate other transport processes near the wall indicating the growth of an internal turbulent boundary layer. In the outer region, however, the flow still has a memory of the upstream disturbance even at the last measuring station of 51 step-heights. The data show that the structure of the inner layer recovers at a much faster rate than the outer layer structure. The inner layer structure resembles the near-wall structure of a plane zero pressure-gradient turbulent boundary layer (plane TBL) by 25h to 30h, while the outer layer structure takes presumably over 100h.

  4. An experimental study of combustion: The turbulent structure of a reacting shear layer formed at a rearward-facing step. Ph.D. Thesis. Final Report

    NASA Technical Reports Server (NTRS)

    Pitz, R. W.

    1981-01-01

    A premixed propane-air flame is stabilized in a turbulent free shear layer formed at a rearward-facing step. The mean and rms averages of the turbulent velocity flow field were determined by LDV for both reacting and non-reacting flows. The reaching flow was visualized by high speed schlieren photography. Large scale structures dominate the reacting shear layer. The growth of the large scale structures is tied to the propagation of the flame. The linear growth rate of the reacting shear layer defined by the mean velocity profiles is unchanged by combustion but the virtual origin is shifted downstream. The reacting shear layer based on the mean velocity profiles is shifted toward the recirculation zone and the reattachments lengths are shortened by 30%.

  5. The role of velocity, pressure, and bed stress fluctuations in bed load transport over bed forms: numerical simulation downstream of a backward-facing step

    NASA Astrophysics Data System (ADS)

    Schmeeckle, M. W.

    2015-02-01

    Bed load transport over ripples and dunes in rivers exhibits strong spatial and temporal variability due to the complex turbulence field caused by flow separation at bedform crests. A turbulence-resolving flow model downstream of a backward-facing step, coupled with a model integrating the equations of motion of individual sand grains, is used to investigate the physical interaction between bed load motion and turbulence downstream of separated flow. Large bed load transport events are found to correspond to low-frequency positive pressure fluctuations. Episodic penetration of fluid into the bed increases the bed stress and moves grains. Fluid penetration events are larger in magnitude near the point of reattachment than farther downstream. Models of bed load transport over ripples and dunes must incorporate the effects of these penetration events of high stress and sediment flux.

  6. The role of velocity, pressure, and bed stress fluctuations in bed load transport over bed forms: numerical simulation downstream of a backward-facing step

    NASA Astrophysics Data System (ADS)

    Schmeeckle, M. W.

    2014-07-01

    Bed load transport over ripples and dunes in rivers exhibits strong spatial and temporal variability due to the complex turbulence field caused by flow separation at bedform crests. A turbulence-resolving flow model downstream of a backward-facing step, coupled with a model integrating the equations of motion of individual sand grains, is used to investigate the physical interaction between bed load motion and turbulence downstream of separated flow. Large bed load transport events are found to correspond to low-frequency, positive pressure fluctuations. Episodic penetration of fluid into the bed increases the bed stress and moves grains. Fluid penetration events are larger in magnitude near the point of reattachment than further downstream. Models of bed load transport over ripples and dunes must incorporate the effects of these penetration events of high stress and sediment flux.

  7. Spatiotemporal Structure and Covariance of Bedload Motion and Near-Bed Fluid Velocity over Bedforms: Laboratory and Numerical Experiments Downstream of a Backward-Facing Step

    NASA Astrophysics Data System (ADS)

    Leary, K. P.; Schmeeckle, M. W.

    2014-12-01

    Despite numerous experimental and numerical studies investigating transport over ripples and dunes in rivers, the spatiotemporal details of the pattern of transport over bedforms remain largely unknown. Here we report turbulence-resolving, simultaneous measurements of bedload motion and near-bed fluid velocity downstream of a backward facing step in a laboratory flume. Details are compared to a coupled large eddy simulation and distinct element simulation (LES-DEM) of the same geometry. Two synchronized high-speed video cameras simultaneously observed bed load motion and the motion of neutrally buoyant particles in a laser light sheet 6 mm above the bed at 250 frames/s downstream of a 3.8 cm backward-facing step. Particle imaging velocimetry algorithms were applied to the laser sheet images to obtain two-dimensional field of two-dimensional vectors while manual particle tracking techniques were applied to the video images of the bed. As expected, there is a strong positive correlation between sediment flux and near-bed fluid velocity. Sediment flux was determined by manually tracking grains that passed over a 6 cm long line in the middle of the field of view on the bedload images. Sediment flux increased monotonically downstream of flow reattachment. Localized, intermittent, high-magnitude transport events were more apparent near flow reattachment than further downstream. Often, these high-magnitude events were seen to have significant cross-stream particle velocities. These events are consistent with permeable "splat events" visualized in the LES-DEM numerical simulations, wherein a volume of fluid moves toward and impinges on the bed. Fluid impingement and penetration of the bed results in outward flow and sediment motion from the center of the splat. Work is ongoing to quantify spatial and temporal autocorrelations and covariances of the fluid velocity and sediment motions.

  8. Particle Image Velocimetry Measurements of a Two/Three-dimensional Separating/Reattaching Boundary Layer Downstream of an Axisymmetric Backward-facing Step

    NASA Technical Reports Server (NTRS)

    Hudy, Laura M.; Naguib, Ahmed M.; Humphreys, William M.; Bartram, Scott M.

    2005-01-01

    Planar Particle Image Velocimetry measurements were obtained in the separating/reattaching flow region downstream of an axisymmetric backward-facing step. Data were acquired for a two-dimensional (2D) separating boundary layer at five different Reynolds numbers based on step height (Re(sub h)), spanning 5900-33000, and for a three-dimensional (3D) separating boundary layer at Re(sub h) = 5980 and 8081. Reynolds number effects were investigated in the 2D cases using mean-velocity field, streamwise and wall-normal turbulent velocity, and Reynolds stress statistics. Results show that both the reattachment length (x(sub r)) and the secondary separation point are Reynolds number dependent. The reattachment length increased with rising Re(sub h) while the secondary recirculation region decreased in size. These and other Re(sub h) effects were interpreted in terms of changes in the separating boundary layer thickness and wall-shear stress. On the other hand, in the 3D case, it was found that the imposed cross-flow component was relatively weak in comparison to the streamwise component. As a result, the primary influences of three dimensionality only affected the near-separation region rather than the entire separation bubble.

  9. Flame-acoustic coupling of combustion instability in a non-premixed backward-facing step combustor: the role of acoustic-Reynolds stress

    NASA Astrophysics Data System (ADS)

    Kannan, Ashwin; Chellappan, Balaji; Chakravarthy, Satyanarayanan

    2016-07-01

    Combustion instability in a laboratory scale backward-facing step combustor is numerically investigated by carrying out an acoustically coupled incompressible large eddy simulation of turbulent reacting flow for various Reynolds numbers with fuel injection at the step. The problem is mathematically formulated as a decomposition of the full compressible Navier-Stokes equations using multi-scale analysis by recognising the small length scale and large time scale of the flow field relative to a longitudinal mode acoustic field for low mean Mach numbers. The equations are decomposed into those for an incompressible flow with temperature-dependent density to zeroth order and linearised Euler equations for acoustics as a first order compressibility correction. Explicit coupling terms between the two equation sets are identified to be the flow dilatation as a source of acoustic energy and the acoustic Reynolds stress (ARS) as a source of flow momentum. The numerical simulations are able to capture the experimentally observed flow-acoustic lock-on that signifies the onset of combustion instability, marked by a shift in the dominant frequency from an acoustic to a hydrodynamic mode and accompanied by a nonlinear variation of pressure amplitude. Attention is devoted to flow conditions at two Reynolds numbers before and after lock-on to show that, after lock-on, the ARS causes large-scale vortical rollup resulting in the evolution of a compact flame. As compared to acoustically uncoupled simulations at these Reynolds numbers that show an elongated flame with no significant roll up and disturbance in the upstream flow field, the ARS is seen to alter the shear layer dynamics by affecting the flow field upstream of the step as well, when acoustically coupled.

  10. Calculation of friction coefficient and analysis of fluid flow in a stepped micro-channel for wide range of Knudsen number using Lattice Boltzmann (MRT) method

    NASA Astrophysics Data System (ADS)

    Bakhshan, Younes; Omidvar, Alireza

    2015-12-01

    Micro scale gas flows have attracted significant research interest in the last two decades. In this research, the fluid flow of gases in a stepped micro-channel has been conducted. Wide range of Knudsen number has been implemented using the Lattice Boltzmann (MRT) method in this study. A modified second-order slip boundary condition and a Bosanquet-type effective viscosity are used to consider the velocity slip at the boundaries and to cover the slip and transition regimes of flow to obtain an accurate simulation of rarefied gases. The flow specifications such as pressure loss, velocity profile, stream lines and friction coefficient at different conditions have been presented. The results show, good agreement with available experimental data. The calculation shows, that the friction coefficient decreases with increasing the Knudsen number and stepping the micro-channel has an inverse effect on the friction coefficient value. Furthermore, a new correlation is suggested for calculation of the friction coefficient in the stepped micro-channel flows as below;

  11. Channel

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03693 Channel

    This channel is located south of Iani Chaos.

    Image information: VIS instrument. Latitude -10.9N, Longitude 345.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  12. A validation study of openfoam for hybrid rans-les simulation of incompressible flow over a backward facing step and delta wing

    NASA Astrophysics Data System (ADS)

    Craig, Cecilia Dosh-Bluhm

    The primary objective of this study is to validate and/or identify issues for available numerical methods and turbulence models in OpenFOAM 2.0.0. Such a study will provide a guideline for users, will aid acceptance of OpenFOAM as one of the research solvers at institutions and also guide future multidisciplinary research using OpenFOAM. In addition, a problem of aerospace interest such as the flow features and vortex breakdown around a VFE-II model is obtained for SA, SST RANS and SA-DDES models and compared with DLR experiment. The available numerical methods such as time schemes, convection schemes, P-V couplings and turbulence models are tested as available for a fundamental case of a backward facing step for RANS and Hybrid RANS-LES prediction of fully turbulent flow at a Reynolds number of 32000 and the OpenFOAM predictions are validated against experimental data by Driver et.al and compared with Fluent predictions.

  13. CHANNEL EVOLUTION IN MODIFIED ALLUVIAL STREAMS.

    USGS Publications Warehouse

    Simon, Andrew; Hupp, Cliff R.

    1987-01-01

    This study (a) assesses the channel changes and network trends of bed level response after modifications between 1959 and 1972 of alluvial channels in western Tennessee and (b) develops a conceptual model of bank slope development to qualitatively assess bank stability and potential channel widening. A six-step, semiquantitative model of channel evolution in disturbed channels was developed by quantifying bed level trends and recognizing qualitative stages of bank slope development. Development of the bank profile is defined in terms of three dynamic and observable surfaces: (a) vertical face (70 to 90 degrees), (b) upper bank (25 to 50 degrees), and (c) slough line (20 to 25 degrees).

  14. The Effects of Anti-Black Attitudes and Fear of Rape on Accuracy for the Recognition of Black and White Faces: Another Step Beyond the Layperson's Knowledge.

    ERIC Educational Resources Information Center

    Mack, David B.; And Others

    It was hypothesized that young white women who held antiblack attitudes and who were most fearful of being raped would be less accurate in recognizing photographs of black faces than of white faces, in comparison with young white women without these attitudes and fears. Subjects completed a racial attitude scale and a question measuring their fear…

  15. Observations of internal solitary wave reflection at a step-like submarine bank and strong oblique interaction at Race Point Channel, (Cape Cod).

    NASA Astrophysics Data System (ADS)

    da Silva, Jose C. B.; Grimshaw, Roger H. J.; Magalhaes, Jorge M.

    2010-05-01

    A recent study revealed that Race Point Channel (in Cape Cod, Massachusetts) is a hotspot of internal solitary wave generation. SAR images suggest that the waves are generated within the channel (which has a flat bottom) during the ebb phase of the tide (flowing offshore) and propagate upstream during the initial stages of their formation. Some of these waves propagate into Massachusetts Bay (further North) and interact with the well known Stellwagen Bank internal waves that are generated on the lee-side of the Bank. The southern flank of Stellwagen Bank has very sharp bathymetric gradients and can be considered as a vertical step. Here we discuss the results of analysis of 25 TerraSAR-X radar images (in very high spatial resolution, 3 meters) and a collection of ENVISAT/ERS tandem mission acquisitions (separated in time by approximately 30 minutes) that reveal details about internal wave reflection at the southern flank of Stellwagen Bank. The SAR data also show transmission of internal waves over the Bank and subsequent interaction with lee-waves generated at the eastern side of Stellwagen Bank. The radar backscatter profiles are compared with theory of the transformation of a weakly nonlinear interfacial solitary wave in a two-layer model over a step. The coefficients of wave reflection and transmission are calculated based on typical stratification of the region and assuming linear theory of long interfacial waves. In addition, collision of reflected waves from the Bank with internal waves generated at the Race Point channel (one tidal cycle after) has been occasionally observed. The radar backscatter profiles suggest that the total wave amplitude during the interaction is greater than that obtained by simply adding the individual solitary wave amplitudes, which is in agreement with the theory of obliquely interacting solitary waves at a near critical angle (150°). This may imply localized turbulent mixing as a result of internal solitary wave interaction at

  16. One-step fabrication of hollow-channel gold nanoflowers with excellent catalytic performance and large single-particle SERS activity.

    PubMed

    Ye, Sunjie; Benz, Felix; Wheeler, May C; Oram, Joseph; Baumberg, Jeremy J; Cespedes, Oscar; Christenson, Hugo K; Coletta, Patricia Louise; Jeuken, Lars J C; Markham, Alexander F; Critchley, Kevin; Evans, Stephen D

    2016-08-11

    Hollow metallic nanostructures have shown potential in various applications including catalysis, drug delivery and phototherapy, owing to their large surface areas, reduced net density, and unique optical properties. In this study, novel hollow gold nanoflowers (HAuNFs) consisting of an open hollow channel in the center and multiple branches/tips on the outer surface are fabricated for the first time, via a facile one-step synthesis using an auto-degradable nanofiber as a bifunctional template. The one-dimensional (1D) nanofiber acts as both a threading template as well as a promoter of the anisotropic growth of the gold crystal, the combination of which leads to the formation of HAuNFs with a hollow channel and nanospikes. The synergy of favorable structural/surface features, including sharp edges, open cavity and high-index facets, provides our HAuNFs with excellent catalytic performance (activity and cycling stability) coupled with large single-particle SERS activity (including ∼30 times of activity in ethanol electro-oxidation and ∼40 times of single-particle SERS intensity, benchmarked against similar-sized solid gold nanospheres with smooth surfaces, as well as retaining 86.7% of the initial catalytic activity after 500 cycles in ethanol electro-oxidation). This innovative synthesis gives a nanostructure of the geometry distinct from the template and is extendable to fabricating other systems for example, hollow-channel silver nanoflowers (HAgNFs). It thus provides an insight into the design of hollow nanostructures via template methods, and offers a versatile synthetic strategy for diverse metal nanomaterials suited for a broad range of applications. PMID:27352044

  17. Partial steps of charge translocation in the nonpumping N139L mutant of Rhodobacter sphaeroides cytochrome c oxidase with a blocked D-channel.

    PubMed

    Siletsky, Sergey A; Zhu, Jiapeng; Gennis, Robert B; Konstantinov, Alexander A

    2010-04-13

    The N139L substitution in the D-channel of cytochrome oxidase from Rhodobacter sphaeroides results in an approximately 15-fold decrease in the turnover number and a loss of proton pumping. Time-resolved absorption and electrometric assays of the F --> O transition in the N139L mutant oxidase result in three major findings. (1) Oxidation of the reduced enzyme by O(2) shows approximately 200-fold inhibition of the F --> O step (k approximately 2 s(-1) at pH 8) which is not compatible with enzyme turnover ( approximately 30 s(-1)). Presumably, an abnormal intermediate F(deprotonated) is formed under these conditions, one proton-deficient relative to a normal F state. In contrast, the F --> O transition in N139L oxidase induced by single-electron photoreduction of intermediate F, generated by reaction of the oxidized enzyme with H(2)O(2), decelerates to an extent compatible with enzyme turnover. (2) In the N139L mutant, the protonic phase of Deltapsi generation coupled to the flash-induced F --> O transition greatly decreases in rate and magnitude and can be assigned to the movement of a proton from E286 to the binuclear site, required for reduction of heme a(3) from the Fe(4+) horizontal lineO(2-) state to the Fe(3+)-OH(-) state. Electrogenic reprotonation of E286 from the inner aqueous phase is missing from the F --> O step in the mutant. (3) In the N139L mutant, the KCN-insensitive rapid electrogenic phase may be composed of two components with lifetimes of approximately 10 and approximately 40 mus and a magnitude ratio of approximately 3:2. The 10 mus phase matches vectorial electron transfer from Cu(A) to heme a, whereas the 40 mus component is assigned to intraprotein proton displacement across approximately 20% of the membrane dielectric thickness. This proton displacement might be triggered by rotation of the charged K362 side chain coupled to heme a reduction. The two components of the rapid electrogenic phase have been resolved subsequently with other D-channel

  18. Partial Steps of Charge Translocation in the Non-Pumping Mutant N139L of Rhodobacter Sphaeroides Cytochrome C Oxidase with a Blocked D-Channel

    PubMed Central

    Siletsky, Sergey A.; Zhu, Jiapeng; Gennis, Robert B.; Konstantinov, Alexander A.

    2010-01-01

    N139L substitution in D-channel of cytochrome oxidase from Rhodobacter sphaeroides results in a ∼15-fold decrease of turnover number and in loss of proton pumping. Time-resolved absorption and electrometric assays of the F→O transition in the N139L mutant oxidase result in 3 major findings. (1) Oxidation of the reduced enzyme by O2 shows ∼200-fold inhibition of the F→O step (k ∼ 2 s-1 at pH 8) which is not compatible with the enzyme turnover (∼30 s-1). Presumably, an abnormal intermediate Fdeprotonated is formed under these conditions, one proton-deficient relative to a normal F-state. In contrast, the F→O transition in N139L oxidase induced by single-electron photoreduction of intermediate F, generated by reaction of the oxidized enzyme with H2O2, decelerates to an extent compatible with enzyme turnover. (2) In the N139L, the protonic phase of Δψ-generation coupled to the flash-induced F→O transition greatly decreases in rate and magnitude and can be assigned to proton movement from E286 to the binuclear site, required for reduction of heme a3 from Fe4+=O2- to Fe3+-OH- state. Electrogenic reprotonation of E286 from the inner aqueous phase is missing from the F→O step in the mutant. (3) In the N139L, the KCN-insensitive rapid electrogenic phase may be actually composed of two components with lifetimes of ∼10 and ∼40 μs and the magnitude ratio of ∼3:2, respectively. The 10 μs phase matches vectorial electron transfer from CuA to heme a, whereas the 40 μs component is assigned to intraprotein proton displacement across ∼20% of the membrane dielectric thickness. This proton displacement might be triggered by rotation of the charged K362 side-chain coupled to heme a reduction. The two components of the rapid electrogenic phase have been resolved subsequently with other D-channel mutants as well as with cyanide-inhibited wild-type oxidase. The finding helps to reconcile the unusually high relative contribution of the microsecond

  19. One-step in-mould modification of PDMS surfaces and its application in the fabrication of self-driven microfluidic channels.

    PubMed

    Fatona, Ayodele; Chen, Yang; Reid, Michael; Brook, Michael A; Moran-Mirabal, Jose M

    2015-11-21

    Poly(dimethylsiloxane) (PDMS) has become the material of choice for fabricating microfluidic channels for lab-on-a-chip applications. Key challenges that limit the use of PDMS in microfluidic applications are its hydrophobic nature, and the difficulty in obtaining stable surface modifications. Although a number of approaches exist to render PDMS hydrophilic, they suffer from reversion to hydrophobicity and, frequently, surface cracking or roughening. In this study, we describe a one-step in-mould method for the chemical modification of PDMS surfaces, and its use to assess the ability of different surfactants to render PDMS surfaces hydrophilic. Thin films of ionic and non-ionic surfactants were patterned into an array format, transferred onto silicone pre-polymer, and subsequently immobilized onto the PDMS surface during vulcanization. The hydrophilicity of the resulting surfaces was assessed by contact angle measurements. The wettability was observed to be dependent on the chemical structure of the surfactants, their concentration and interactions with PDMS. The morphology of modified PDMS surfaces and their change after wetting and drying cycles were visualized using atomic force microscopy. Our results show that while all surfactants tested can render PDMS surfaces hydrophilic through the in-mould modification, only those modified with PEG-PDMS-PEG copolymer surfactants were stable over wetting/dying cycles and heat treatments. Finally, the in-mould functionalization approach was used to fabricate self-driven microfluidic devices that exhibited steady flow rates, which could be tuned by the device geometry. It is anticipated that the in-mould method can be applied to a range of surface modifications for applications in analytical separations, biosensing, cell isolation and small molecule discovery. PMID:26400365

  20. Fabrication of top-contact pentacene-based organic thin-film transistors with short channels using two-step SU8/poly(vinyl alcohol) lift-off photolithography process

    NASA Astrophysics Data System (ADS)

    Fan, Ching-Lin; Lin, Wei-Chun; Lee, Cheng-Chieh; Lin, Yu-Zuo; Huang, Bohr-Ran

    2016-02-01

    We propose a two-step SU8/poly(vinyl alcohol) (PVA) lift-off photolithography scheme for fabricating top-contact pentacene-based organic thin-film transistors (OTFTs) with small channels. The bilayer of PVA and SU8 will not damage the pentacene channel layer in the lift-off photolithography process used in forming the patterned pentacene channel layer and source/drain metal electrodes. We demonstrate a device that not only obtains a 5 µm short channel length for source/drain metal-electrode patterning but also avoids fringe current resulting from pentacene channel layer patterning. The field-effect mobility and threshold voltage of the pentacene-based OTFTs were changed from 0.29 to 0.12 cm2 V-1 s-1 and from -5.74 to -3.19 V by varying the channel length from 50 to 5 µm, respectively. The proposed scheme is a good candidate for use in the design and fabrication of high-performance short-channel organic electronics.

  1. A polyether biotoxin binding site on the lipid-exposed face of the pore domain of Kv channels revealed by the marine toxin gambierol

    PubMed Central

    Kopljar, Ivan; Labro, Alain J.; Cuypers, Eva; Johnson, Henry W. B.; Rainier, Jon D.; Tytgat, Jan; Snyders, Dirk J.

    2009-01-01

    Gambierol is a marine polycyclic ether toxin belonging to the group of ciguatera toxins. It does not activate voltage-gated sodium channels (VGSCs) but inhibits Kv1 potassium channels by an unknown mechanism. While testing whether Kv2, Kv3, and Kv4 channels also serve as targets, we found that Kv3.1 was inhibited with an IC50 of 1.2 ± 0.2 nM, whereas Kv2 and Kv4 channels were insensitive to 1 μM gambierol. Onset of block was similar from either side of the membrane, and gambierol did not compete with internal cavity blockers. The inhibition did not require channel opening and could not be reversed by strong depolarization. Using chimeric Kv3.1–Kv2.1 constructs, the toxin sensitivity was traced to S6, in which T427 was identified as a key determinant. In Kv3.1 homology models, T427 and other molecular determinants (L348, F351) reside in a space between S5 and S6 outside the permeation pathway. In conclusion, we propose that gambierol acts as a gating modifier that binds to the lipid-exposed surface of the pore domain, thereby stabilizing the closed state. This site may be the topological equivalent of the neurotoxin site 5 of VGSCs. Further elucidation of this previously undescribed binding site may explain why most ciguatoxins activate VGSCs, whereas others inhibit voltage-dependent potassium (Kv) channels. This previously undescribed Kv neurotoxin site may have wide implications not only for our understanding of channel function at the molecular level but for future development of drugs to alleviate ciguatera poisoning or to modulate electrical excitability in general. PMID:19482941

  2. Attenuation and bit error rate for four co-propagating spatially multiplexed optical communication channels of exactly same wavelength in step index multimode fibers

    NASA Astrophysics Data System (ADS)

    Murshid, Syed H.; Chakravarty, Abhijit

    2011-06-01

    Spatial domain multiplexing (SDM) utilizes co-propagation of exactly the same wavelength in optical fibers to increase the bandwidth by integer multiples. Input signals from multiple independent single mode pigtail laser sources are launched at different input angles into a single multimode carrier fiber. The SDM channels follow helical paths and traverse through the carrier fiber without interfering with each other. The optical energy from the different sources is spatially distributed and takes the form of concentric circular donut shaped rings, where each ring corresponds to an independent laser source. At the output end of the fiber these donut shaped independent channels can be separated either with the help of bulk optics or integrated concentric optical detectors. This presents the experimental setup and results for a four channel SDM system. The attenuation and bit error rate for individual channels of such a system is also presented.

  3. Face pain

    MedlinePlus

    Face pain may be dull and throbbing or an intense, stabbing discomfort in the face or forehead. It can occur in one or ... Pain that starts in the face may be caused by a nerve problem, injury, or infection. Face pain may also begin in other places in the body. ...

  4. Security: Step by Step

    ERIC Educational Resources Information Center

    Svetcov, Eric

    2005-01-01

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

  5. Game Face

    ERIC Educational Resources Information Center

    Weiner, Jill

    2005-01-01

    In this article, the author discusses "Game Face: Life Lessons Across the Curriculum", a teaching kit that challenges assumptions and builds confidence. Game Face, which is derived from a book and art exhibition, "Game Face: What Does a Female Athlete Look Like?", uses layered and powerful images of women and girls participating in sports to teach…

  6. Anisotropic Transport of Electrons in a Novel FET Channel with Chains of InGaAs Nano-Islands Embedded along Quasi-Periodic Multi-Atomic Steps on Vicinal (111)B GaAs

    SciTech Connect

    Akiyama, Y.; Kawazu, T.; Noda, T.; Sakaki, H.

    2010-01-04

    We have studied electron transport in n-AlGaAs/GaAs heterojunction FET channels, in which chains of InGaAs nano-islands are embedded along quasi-periodic steps. By using two samples, conductance G{sub para}(V{sub g}) parallel to the steps and G{sub perp}(V{sub g}) perpendicular to them were measured at 80 K as functions of gate voltage V{sub g}. At sufficiently high V{sub g}, G{sub para} at 80 K is several times as high as G{sub perp}, which manifests the anisotropic two-dimensional transport of electrons. When V{sub g} is reduced to -0.7 V, G{sub perp} almost vanishes, while {sub Gpara} stays sizable unless V{sub g} is set below -0.8 V. These results indicate that 'inter-chain' barriers play stronger roles than 'intra-chain' barriers.

  7. Next Step for STEP

    SciTech Connect

    Wood, Claire; Bremner, Brenda

    2013-08-09

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

  8. A Wall of Faces

    ERIC Educational Resources Information Center

    Stevens, Lori

    2008-01-01

    Visitors to the campus of Orland High School (OHS) will never question that they have stepped into a world of the masses: kids, activity, personalities, busyness, and playfulness--a veritable cloud of mild bedlam. The wall of ceramic faces that greets a visitor in the school office is another reminder of the organized chaos that the teachers…

  9. Exploring accessibility of structural elements of the mammalian 40S ribosomal mRNA entry channel at various steps of translation initiation.

    PubMed

    Sharifulin, Dmitri E; Bartuli, Yulia S; Meschaninova, Maria I; Ven'yaminova, Aliya G; Graifer, Dmitri M; Karpova, Galina G

    2016-10-01

    In this work, we studied how the accessibility of structural elements of the mammalian 40S ribosomal mRNA entry channel, ribosomal protein (rp) uS3 and helix (h) 16 of the 18S rRNA, changes upon the translation initiation. In particular, we examined the accessibility of rp uS3 for binding of unstructured RNAs and of riboses in h16 towards attack with benzoyl cyanide (BzCN) in complexes assembled in rabbit reticulocyte lysate utilizing synthetic oligoribonucleotides as well as full-length and truncated up to the initiation AUG codon hepatitis C virus IRES as model mRNAs. With both mRNA types, the rp uS3 peptide recognizing single-stranded RNAs was shown to become shielded only in those 48S preinitiation complexes (PICs) that contained eIF3j bound to 40S subunit in the area between the decoding site and the mRNA entry channel. Chemical probing with BzCN revealed that h16 in the 48S PICs containing eIF3j or scanning factor DHX29 is strongly shielded; the effect was observed with all the mRNAs used, and h16 remained protected as well in 80S post-initiation complexes lacking these factors. Altogether, the obtained results allowed us to suggest that eIF3j bound at the 48S PICs makes the rp uS3 inaccessible for binding of RNAs and this factor subunit is responsible for the decrease of h16 conformational flexibility; the latter is manifested as reduced accessibility of h16 to BzCN. Thus, our findings provide new insights into how eIF3j is implicated in ensuring the proper conformation of the mRNA entry channel, thereby facilitating mRNA loading. PMID:27346718

  10. Face Painting.

    ERIC Educational Resources Information Center

    Brooks, Diana

    1995-01-01

    Discusses the use of face painting as a technique for making the endangered species issue tangible for children while addressing the complexity of the issue. Children are "given" an animal of their own and are educated about the animal while having their faces painted to resemble the animal. (LZ)

  11. Face pain

    MedlinePlus

    ... gets worse when you bend forward) Tic douloureux Temporomandibular joint dysfunction syndrome Sometimes the reason for the face pain ... is persistent, unexplained, or accompanied by other unexplained symptoms. Call your primary provider. What to Expect at ...

  12. Activation of delta-opioid receptors inhibits neuronal-like calcium channels and distal steps of Ca(2+)-dependent secretion in human small-cell lung carcinoma cells.

    PubMed

    Sher, E; Cesare, P; Codignola, A; Clementi, F; Tarroni, P; Pollo, A; Magnelli, V; Carbone, E

    1996-06-01

    Human small-cell lung carcinoma (SCLC) cells express neuronal-like voltage-operated calcium channels (VOCCs) and release mitogenic hormones such as serotonin (5-HT). Opioid peptides, on the other hand, have been shown to reduce SCLC cell proliferation by an effective autocrine pathway. Here we show that in GLC8 SCLC cells, only delta-opioid receptor subtype mRNA is expressed. Consistently, the selective delta-opioid agonist [D-Pen2-Pen5]-enkephalin (DPDPE), but not mu and kappa agonists, potently and dose-dependently inhibits high-threshold (HVA) VOCCs in these cells. As in peripheral neurons, this modulation is largely voltage-dependent, mediated by pertussis toxin (PTX)-sensitive G-proteins, cAMP-independent, and mainly affecting N-type VOCCs. With the same potency and selectivity, DPDPE also antagonizes the Ca(2+)-dependent release of [3H]serotonin ([3H]5-HT) from GLC8 cells. However, DPDPE inhibits not only the depolarization-induced release, but also the Ca(2+)-dependent secretion induced by thapsigargin or ionomycin. This suggests that besides inhibiting HVA VOCCs, opioids also exert a direct depressive action on the secretory apparatus in GLC8 cells. This latter effect also is mediated by a PTX-sensitive G-protein but, contrary to VOCC inhibition, it can be reversed by elevations of cAMP levels. These results show for the first time that opioids effectively depress both Ca2+ influx and Ca(2+)-dependent hormone release in SCLC cells by using multiple modulatory pathways. It can be speculated that the two mechanisms may contribute to the opioid antimitogenic action on lung neuroendocrine carcinoma cells. PMID:8642411

  13. Another record of significant regional variation in toxicity of Tityus serrulatus venom in Brazil: a step towards understanding the possible role of sodium channel modulators.

    PubMed

    Oliveira, Fagner Neves; Mortari, Márcia Renata; Carneiro, Fabiana Pirani; Guerrero-Vargas, Jimmy Alexander; Santos, Daniel M; Pimenta, Adriano M C; Schwartz, Elisabeth F

    2013-10-01

    The scorpion Tityus serrulatus is responsible for the most severe accidents that have been registered in Brazil, mainly in the state of Minas Gerais (MG), being the lung edema (LE), the main cause of death in these accidents. Although an increased in the number of accidents caused to this species in Federal District (Distrito Federal - DF), it seems that this particular species is not responsible for severe scorpionism cases in this region. Given this observation, we tested the toxicity in mice and compared the ability of T. serrulatus venom from DF (Ts-DF) and Minas Gerais State (Ts-MG) to induce LE in rats. The LD50 of Ts-DF venom was 51.6 μg/mouse, almost twice (1.98) higher than that obtained for Ts-MG venom. The ability of venom (0.5 mg/kg) to induce LE in rats was determined by the wet weight differences between treated and untreated lungs, by pulmonary morphological analyses and by pulmonary vascular permeability (PVP) using the Evans blue protocol. Significant differences in the wet weight of lungs and changes in PVP were found in Ts-MG venom treated rats when compared to rats treated with Ts-DF venom or untreated rats (p < 0.001), but no differences occurred when comparing rats treated with Ts-DF venom and untreated rats (p < 0.05). These results were confirmed by evaluation of pulmonary morphology. Comparison of chromatographic profiles obtained from these venoms (Ts-DF and Ts-MG) using the fractal dimension (D) analysis and the molecular mass fingerprint of the chromatographic fractions showed a higher number of components between 35 and 40% acetonitrile in Ts-MG venom than in Ts-DF venom, indicating a higher diversity of sodium channel modulators in that venom. PMID:23851224

  14. Cyclic steps on ice

    NASA Astrophysics Data System (ADS)

    Yokokawa, M.; Izumi, N.; Naito, K.; Parker, G.; Yamada, T.; Greve, R.

    2016-05-01

    Boundary waves often form at the interface between ice and fluid flowing adjacent to it, such as ripples under river ice covers, and steps on the bed of supraglacial meltwater channels. They may also be formed by wind, such as the megadunes on the Antarctic ice sheet. Spiral troughs on the polar ice caps of Mars have been interpreted to be cyclic steps formed by katabatic wind blowing over ice. Cyclic steps are relatives of upstream-migrating antidunes. Cyclic step formation on ice is not only a mechanical but also a thermodynamic process. There have been very few studies on the formation of either cyclic steps or upstream-migrating antidunes on ice. In this study, we performed flume experiments to reproduce cyclic steps on ice by flowing water, and found that trains of steps form when the Froude number is larger than unity. The features of those steps allow them to be identified as ice-bed analogs of cyclic steps in alluvial and bedrock rivers. We performed a linear stability analysis and obtained a physical explanation of the formation of upstream-migrating antidunes, i.e., precursors of cyclic steps. We compared the results of experiments with the predictions of the analysis and found the observed steps fall in the range where the analysis predicts interfacial instability. We also found that short antidune-like undulations formed as a precursor to the appearance of well-defined steps. This fact suggests that such antidune-like undulations correspond to the instability predicted by the analysis and are precursors of cyclic steps.

  15. FACE Act

    THOMAS, 111th Congress

    Rep. Watson, Diane E. [D-CA-33

    2009-06-26

    08/19/2009 Referred to the Subcommittee on Immigration, Citizenship, Refugees, Border Security, and International Law. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

  16. Funny Faces.

    ERIC Educational Resources Information Center

    Greene, Yvonne

    2000-01-01

    Presents a torn-paper and gadget-print activity for younger students, specifically pre-kindergarten to first grade, that can be done any time over the school year or at Halloween. Discusses how the students create their funny faces and lists the materials needed. (CMK)

  17. PHOEBE - step by step manual

    NASA Astrophysics Data System (ADS)

    Zasche, P.

    2016-03-01

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

  18. Step Pultrusion

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  19. Stepping Forward

    ERIC Educational Resources Information Center

    Jackson, Nancy Mann

    2013-01-01

    Boards of trustees are enduring rough waters, churned by scandals at prominent public universities. In the wake of cases of institutional turmoil, board members at U.S. public universities are navigating myriad challenges facing higher education, including funding shortages, technological changes that are reshaping the way teaching and learning…

  20. Face recognition using 4-PSK joint transform correlation

    NASA Astrophysics Data System (ADS)

    Moniruzzaman, Md.; Alam, Mohammad S.

    2016-04-01

    This paper presents an efficient phase-encoded and 4-phase shift keying (PSK)-based fringe-adjusted joint transform correlation (FJTC) technique for face recognition applications. The proposed technique uses phase encoding and a 4- channel phase shifting method on the reference image which can be pre-calculated without affecting the system processing speed. The 4-channel PSK step eliminates the unwanted zero-order term, autocorrelation among multiple similar input scene objects while yield enhanced cross-correlation output. For each channel, discrete wavelet decomposition preprocessing has been used to accommodate the impact of various 3D facial expressions, effects of noise, and illumination variations. The performance of the proposed technique has been tested using various image datasets such as Yale, and extended Yale B under different environments such as illumination variation and 3D changes in facial expressions. The test results show that the proposed technique yields significantly better performance when compared to existing JTC-based face recognition techniques.

  1. Fast skin color detector for face extraction

    NASA Astrophysics Data System (ADS)

    Chen, Lihui; Grecos, Christos

    2005-02-01

    Face detection is the first step for an automatic face recognition system. For color images, skin color filter is considered as an important method for removing non-face pixels. In the paper, we will propose a novel and efficient detector for skin color regions for face extraction. The detector processes the image in four steps: lighting compensation, skin color filter and mask refinement and fast patch identification. Experimental results show that our detector is more robust and efficient than other skin color filters.

  2. Stepped nozzle

    DOEpatents

    Sutton, G.P.

    1998-07-14

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

  3. Stepped nozzle

    DOEpatents

    Sutton, George P.

    1998-01-01

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

  4. Face adaptation depends on seeing the face.

    PubMed

    Moradi, Farshad; Koch, Christof; Shimojo, Shinsuke

    2005-01-01

    Retinal input that is suppressed from visual awareness can nevertheless produce measurable aftereffects, revealing neural processes that do not directly result in a conscious percept. We here report that the face identity-specific aftereffect requires a visible face; it is effectively cancelled by binocular suppression or by inattentional blindness of the inducing face. Conversely, the same suppression does not interfere with the orientation-specific aftereffect. Thus, the competition between incompatible or interfering visual inputs to reach awareness is resolved before those aspects of information that are exploited in face identification are processed. We also found that the face aftereffect remained intact when the visual distracters in the inattention experiment were replaced with auditory distracters. Thus, cross-modal or cognitive interference that does not affect the visibility of the face does not interfere with the face aftereffect. We conclude that adaptation to face identity depends on seeing the face. PMID:15629711

  5. Comparison of face-to-face and telephone consultations in primary care: qualitative analysis

    PubMed Central

    Hewitt, Heather; Gafaranga, Joseph; McKinstry, Brian

    2010-01-01

    Background There is evidence that telephone consultations in general practice are typically shorter than face-to-face consultations and that fewer problems are presented in them. Aim To compare the communicative practices of doctors and patients in face-to-face and telephone consultations, in order to understand the contrasts between the two consulting modes. Design of study Conversation analysis. Setting Eight NHS GP surgeries in Scotland. Method Transcription and conversation analysis of 32 face-to-face and 33 telephone consultations. Participants Eighteen GPs and 65 patients. Results There are no underlying contrasts between the communicative practices used in face-to-face and telephone consultations. Telephone consultations are typically used by patients to deal with a limited range of single-issue concerns, whereas a wide range of different problem types is dealt with in face-to-face consultations. Most telephone consultations for new problems lead to a face-to-face meeting rather than a diagnosis, making them shorter than equivalent face-to-face consultations. Interaction in telephone consultations is continuous and orderly, but in face-to-face consultations there are periods of silence that facilitate the introduction of additional topics, including social speech and rapport building. Doctors on the telephone are less likely to elicit additional concerns than in face-to-face consultations, and ask fewer questions when patients present self-diagnosed problems or describe problems with treatment. Conclusion Doctors in general practice do not substantially change their communicative behaviour on the telephone. Telephone consultations are shorter and include less problem disclosure than face-to-face meetings, partly because they are typically mono-topical and partly because of intrinsic differences between the two channels. PMID:20423575

  6. Mapping Teacher-Faces

    ERIC Educational Resources Information Center

    Thompson, Greg; Cook, Ian

    2013-01-01

    This paper uses Deleuze and Guattari's concept of faciality to analyse the teacher's face. According to Deleuze and Guattari, the teacher-face is a special type of face because it is an "overcoded" face produced in specific landscapes. This paper suggests four limit-faces for teacher faciality that actualise different mixes of significance and…

  7. Learning Faces from Photographs

    ERIC Educational Resources Information Center

    Longmore, Christopher A.; Liu, Chang Hong; Young, Andrew W.

    2008-01-01

    Previous studies examining face learning have mostly used only a single exposure to 1 image of each of the faces to be learned. However, in daily life, faces are usually learned from multiple encounters. These 6 experiments examined the effects on face learning of repeated exposures to single or multiple images of a face. All experiments…

  8. A Face Inversion Effect without a Face

    ERIC Educational Resources Information Center

    Brandman, Talia; Yovel, Galit

    2012-01-01

    Numerous studies have attributed the face inversion effect (FIE) to configural processing of internal facial features in upright but not inverted faces. Recent findings suggest that face mechanisms can be activated by faceless stimuli presented in the context of a body. Here we asked whether faceless stimuli with or without body context may induce…

  9. Head and face reconstruction

    MedlinePlus

    Head and face reconstruction is surgery to repair or reshape deformities of the head and face (craniofacial). ... How surgery for head and face deformities (craniofacial reconstruction) ... and the person's condition. Surgical repairs involve the ...

  10. RFI channels

    NASA Technical Reports Server (NTRS)

    Mceliece, R. J.

    1980-01-01

    A class of channel models is presented which exhibit varying burst error severity much like channels encountered in practice. An information-theoretic analysis of these channel models is made, and conclusions are drawn that may aid in the design of coded communication systems for realistic noisy channels.

  11. Numerical modeling of turbulent flow in a channel

    NASA Technical Reports Server (NTRS)

    Dai, Y. W.; Ghoniem, A. F.; Sherman, F. S.; Oppenheim, A. K.

    1983-01-01

    Two-dimensional incompressible turbulent flow in a channel with a backward-facing step was studied numerically by Chorin's Random Vortex Method (RVM), an algorithm capable of tracing the action of elementary turbulent eddies and their cumulative effects without imposing any restrictions upon their motions. The step occurs in one side of a channel with otherwise flat, parallel walls; its height equals 1/3, 1/4 or 1/5 the width of the channel downstream. The main objective was to investigate the behavior of the large-scale turbulent eddies in a flow and the flow characteristics in the separated shear layer, the reattached zone, and the rebuilding boundary layer after reattachment. The unsteady vorticity field and the distribution of time-averaged turbulent statistics were obtained. The effects of expansion step height and initial boundary layer state were also studied. Comparisons were made with the available experimental results. The agreement is satisfactory in the velocity profiles and in the reattachment length, and fairly good in the turbulence profiles. Also a mechanism of the development of the reattaching turbulent flow was suggested by the numerical results.

  12. Sticky steps inhibit step motions near equilibrium

    NASA Astrophysics Data System (ADS)

    Akutsu, Noriko

    2012-12-01

    Using a Monte Carlo method on a lattice model of a vicinal surface with a point-contact-type step-step attraction, we show that, at low temperature and near equilibrium, there is an inhibition of the motion of macrosteps. This inhibition leads to a pinning of steps without defects, adsorbates, or impurities (self-pinning of steps). We show that this inhibition of the macrostep motion is caused by faceted steps, which are macrosteps that have a smooth side surface. The faceted steps result from discontinuities in the anisotropic surface tension (the surface free energy per area). The discontinuities are brought into the surface tension by the point-contact-type step-step attraction. The point-contact-type step-step attraction also originates “step droplets,” which are locally merged steps, at higher temperatures. We derive an analytic equation of the surface stiffness tensor for the vicinal surface around the (001) surface. Using the surface stiffness tensor, we show that step droplets roughen the vicinal surface. Contrary to what we expected, the step droplets slow down the step velocity due to the diminishment of kinks in the merged steps (smoothing of the merged steps).

  13. Facing facts: neuronal mechanisms of face perception.

    PubMed

    Dekowska, Monika; Kuniecki, Michał; Jaśkowski, Piotr

    2008-01-01

    The face is one of the most important stimuli carrying social meaning. Thanks to the fast analysis of faces, we are able to judge physical attractiveness and features of their owners' personality, intentions, and mood. From one's facial expression we can gain information about danger present in the environment. It is obvious that the ability to process efficiently one's face is crucial for survival. Therefore, it seems natural that in the human brain there exist structures specialized for face processing. In this article, we present recent findings from studies on the neuronal mechanisms of face perception and recognition in the light of current theoretical models. Results from brain imaging (fMRI, PET) and electrophysiology (ERP, MEG) show that in face perception particular regions (i.e. FFA, STS, IOA, AMTG, prefrontal and orbitofrontal cortex) are involved. These results are confirmed by behavioral data and clinical observations as well as by animal studies. The developmental findings reviewed in this article lead us to suppose that the ability to analyze face-like stimuli is hard-wired and improves during development. Still, experience with faces is not sufficient for an individual to become an expert in face perception. This thesis is supported by the investigation of individuals with developmental disabilities, especially with autistic spectrum disorders (ASD). PMID:18511959

  14. Attention Capture by Faces

    ERIC Educational Resources Information Center

    Langton, Stephen R. H.; Law, Anna S.; Burton, A. Mike; Schweinberger, Stefan R.

    2008-01-01

    We report three experiments that investigate whether faces are capable of capturing attention when in competition with other non-face objects. In Experiment 1a participants took longer to decide that an array of objects contained a butterfly target when a face appeared as one of the distracting items than when the face did not appear in the array.…

  15. Familiar face + novel face = familiar face? Representational bias in the perception of morphed faces in chimpanzees.

    PubMed

    Matsuda, Yoshi-Taka; Myowa-Yamakoshi, Masako; Hirata, Satoshi

    2016-01-01

    Highly social animals possess a well-developed ability to distinguish the faces of familiar from novel conspecifics to induce distinct behaviors for maintaining society. However, the behaviors of animals when they encounter ambiguous faces of familiar yet novel conspecifics, e.g., strangers with faces resembling known individuals, have not been well characterised. Using a morphing technique and preferential-looking paradigm, we address this question via the chimpanzee's facial-recognition abilities. We presented eight subjects with three types of stimuli: (1) familiar faces, (2) novel faces and (3) intermediate morphed faces that were 50% familiar and 50% novel faces of conspecifics. We found that chimpanzees spent more time looking at novel faces and scanned novel faces more extensively than familiar or intermediate faces. Interestingly, chimpanzees looked at intermediate faces in a manner similar to familiar faces with regards to the fixation duration, fixation count, and saccade length for facial scanning, even though the participant was encountering the intermediate faces for the first time. We excluded the possibility that subjects merely detected and avoided traces of morphing in the intermediate faces. These findings suggest a bias for a feeling-of-familiarity that chimpanzees perceive familiarity with an intermediate face by detecting traces of a known individual, as 50% alternation is sufficient to perceive familiarity. PMID:27602275

  16. Familiar face + novel face = familiar face? Representational bias in the perception of morphed faces in chimpanzees

    PubMed Central

    Myowa-Yamakoshi, Masako

    2016-01-01

    Highly social animals possess a well-developed ability to distinguish the faces of familiar from novel conspecifics to induce distinct behaviors for maintaining society. However, the behaviors of animals when they encounter ambiguous faces of familiar yet novel conspecifics, e.g., strangers with faces resembling known individuals, have not been well characterised. Using a morphing technique and preferential-looking paradigm, we address this question via the chimpanzee’s facial–recognition abilities. We presented eight subjects with three types of stimuli: (1) familiar faces, (2) novel faces and (3) intermediate morphed faces that were 50% familiar and 50% novel faces of conspecifics. We found that chimpanzees spent more time looking at novel faces and scanned novel faces more extensively than familiar or intermediate faces. Interestingly, chimpanzees looked at intermediate faces in a manner similar to familiar faces with regards to the fixation duration, fixation count, and saccade length for facial scanning, even though the participant was encountering the intermediate faces for the first time. We excluded the possibility that subjects merely detected and avoided traces of morphing in the intermediate faces. These findings suggest a bias for a feeling-of-familiarity that chimpanzees perceive familiarity with an intermediate face by detecting traces of a known individual, as 50% alternation is sufficient to perceive familiarity. PMID:27602275

  17. Programmed versus Face-to-Face Counseling

    ERIC Educational Resources Information Center

    Gilbert, William M.; Ewing, Thomas N.

    1971-01-01

    A comparison was made of the effectiveness of a programmed Self-Counseling Manual and a normal precollege counseling interview by experienced counselors. Findings supported the use of programmed counseling as an adjunct to or substitute for face-to-face counseling. (Author)

  18. Mechanisms of face perception

    PubMed Central

    Tsao, Doris Y.

    2009-01-01

    Faces are among the most informative stimuli we ever perceive: Even a split-second glimpse of a person's face tells us their identity, sex, mood, age, race, and direction of attention. The specialness of face processing is acknowledged in the artificial vision community, where contests for face recognition algorithms abound. Neurological evidence strongly implicates a dedicated machinery for face processing in the human brain, to explain the double dissociability of face and object recognition deficits. Furthermore, it has recently become clear that macaques too have specialized neural machinery for processing faces. Here we propose a unifying hypothesis, deduced from computational, neurological, fMRI, and single-unit experiments: that what makes face processing special is that it is gated by an obligatory detection process. We will clarify this idea in concrete algorithmic terms, and show how it can explain a variety of phenomena associated with face processing. PMID:18558862

  19. Insulated face brick

    SciTech Connect

    Cromrich, J.; Cromrich, L.B.

    1990-10-16

    This patent describes a method for forming insulated brick intended solely for use in building walls and having superior insulation qualities and lighter weight consonant with the load bearing capabilities of building bricks and the appearance of facing brick. It comprises dry mixing two parts of vermiculite and one part of brick clay, thereby forming a dry mixture having a vermiculite to clay ratio of approximately two-to-one by volume; adding water to the dry mixture and mixing, so that a substantially dry admixture having expanded vermiculite and brick clay is formed; forming a facing layer solely from brick clay; molding and compressing the substantially dry admixture, so as to form a generally rectangular main body layer having parallel top and bottom faces, a pair of parallel side faces and a pair of parallel end faces, respectively, the top and bottom faces being substantially larger in area than the respective side faces, and the side faces being substantially larger in area than the respective end faces, the body layer further having at least one bore formed therein, the bore running from the top face to the bottom face perpendicularly thereto and substantially parallel to the side surfaces thereof, the bore being substantially centrally disposed and wherein the facing layer is disposed on one of the side surfaces of the body portion; curing the molded admixture having the facing layer disposed thereon; whereby a cured brick is formed; and firing the cured brick and the facing layer disposed thereon, whereby an integral brick is formed having top and bottom faces of the brick which are entirely devoid of facing layers, wherein the brick has the desired load bearing capability substantially between its top and bottom faces, whereby the outer facing layer only provides the desired appearance and weather resistance, and further whereby the weight of the brick is substantially reduced.

  20. Gender recognition based on face geometric features

    NASA Astrophysics Data System (ADS)

    Xiao, Jie; Guo, Zhaoli; Cai, Chao

    2013-10-01

    Automatic gender recognition based on face images plays an important role in computer vision and machine vision. In this paper, a novel and simple gender recognition method based on face geometric features is proposed. The method is divided in three steps. Firstly, Pre-processing step provides standard face images for feature extraction. Secondly, Active Shape Model (ASM) is used to extract geometric features in frontal face images. Thirdly, Adaboost classifier is chosen to separate the two classes (male and female). We tested it on 2570 pictures (1420 males and 1150 females) downloaded from the internet, and encouraging results were acquired. The comparison of the proposed geometric feature based method and the full facial image based method demonstrats its superiority.

  1. Cholesterol binding to ion channels

    PubMed Central

    Levitan, Irena; Singh, Dev K.; Rosenhouse-Dantsker, Avia

    2014-01-01

    Numerous studies demonstrated that membrane cholesterol is a major regulator of ion channel function. The goal of this review is to discuss significant advances that have been recently achieved in elucidating the mechanisms responsible for cholesterol regulation of ion channels. The first major insight that comes from growing number of studies that based on the sterol specificity of cholesterol effects, show that several types of ion channels (nAChR, Kir, BK, TRPV) are regulated by specific sterol-protein interactions. This conclusion is supported by demonstrating direct saturable binding of cholesterol to a bacterial Kir channel. The second major advance in the field is the identification of putative cholesterol binding sites in several types of ion channels. These include sites at locations associated with the well-known cholesterol binding motif CRAC and its reversed form CARC in nAChR, BK, and TRPV, as well as novel cholesterol binding regions in Kir channels. Notably, in the majority of these channels, cholesterol is suggested to interact mainly with hydrophobic residues in non-annular regions of the channels being embedded in between transmembrane protein helices. We also discuss how identification of putative cholesterol binding sites is an essential step to understand the mechanistic basis of cholesterol-induced channel regulation. Clearly, however, these are only the first few steps in obtaining a general understanding of cholesterol-ion channels interactions and their roles in cellular and organ functions. PMID:24616704

  2. 22. View of Clark Fork Vehicle Bridge facing downwest side. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. View of Clark Fork Vehicle Bridge facing down-west side. Looking at road deck and vertical laced channel. - Clark Fork Vehicle Bridge, Spanning Clark Fork River, serves Highway 200, Clark Fork, Bonner County, ID

  3. Resolution-adaptive face alignment with head pose correction

    NASA Astrophysics Data System (ADS)

    Zhang, Lu; Allebach, Jan; Lin, Qian; Wang, Xianwang

    2015-03-01

    Faces often appear very small and oriented in surveillance videos because of the need of wide fields of view and typically a large distance between the cameras and the scene. Both low resolution and side-view faces make tasks such as face recognition difficult. As a result, face hallucination or super-resolution techniques of face images are generally needed, which has become a thriving research field. However, most existing methods assume face images have been well aligned into some canonical form (i.e. frontal, symmetric). Therefore, face alignment, especially for low-resolution face images, is a key and first step to the success of many face applications. In this paper, we propose an auto alignment approach for face images at different resolution, which consist of two fundamental steps: 1) To find the locations of facial landmarks or feature points (i.e. eyes, nose, and etc.) even for very low resolution faces; 2) To estimate and correct head poses based on the landmark locations and a 3D reference face model. The effectiveness of this method is shown by the aligned face images and the improved face recognition score on released data sets.

  4. Face powder poisoning

    MedlinePlus

    Face powder poisoning occurs when someone swallows or breathes in this substance. This article is for information ... The ingredients in face powder that can be harmful are: Baking soda Talcum powder Many other types of powder

  5. Face powder poisoning

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002700.htm Face powder poisoning To use the sharing features on this page, please enable JavaScript. Face powder poisoning occurs when someone swallows or breathes ...

  6. Innate face processing.

    PubMed

    Sugita, Yoichi

    2009-02-01

    Recent monkey studies provide intriguing information for an open question whether face processing is a special perceptual process and is organized as such at birth, or has its origin in a more general system that becomes specialized with experience. Before seeing any faces or face-like objects, macaque monkeys showed a preference for faces rather than nonface objects. Furthermore, they showed remarkable face processing abilities both for human and monkey faces. It was also shown that macaque newborns are able to imitate human facial gestures, indicating the ability to match their own facial movements to observed facial gestures. Taken together, it seems very likely that newborns can acquire the knowledge about the basic structure of their own face, presumably through proprioception, so that facial structure would become a familiar and attractive visual object without the experience of the face itself. PMID:19339171

  7. FacingDisability.com

    MedlinePlus

    ... About Blog Facing Disability Jeff Shannon Donate A Spinal Cord Injury Affects the Entire Family FacingDisability was specifically created ... and insights on spinal cord injury issues Interactive Spinal Cord Injury Map Shows what areas are affected by spinal ...

  8. Face to Face Communications in Space

    NASA Technical Reports Server (NTRS)

    Cohen, Malcolm M.; Davon, Bonnie P. (Technical Monitor)

    1999-01-01

    It has been reported that human face-to-face communications in space are compromised by facial edema, variations in the orientations of speakers and listeners, and background noises that are encountered in the shuttle and in space stations. To date, nearly all reports have been anecdotal or subjective, in the form of post-flight interviews or questionnaires; objective and quantitative data are generally lacking. Although it is acknowledged that efficient face-to-face communications are essential for astronauts to work safely and effectively, specific ways in which the space environment interferes with non-linguistic communication cues are poorly documented. Because we have only a partial understanding of how non-linguistic communication cues may change with mission duration, it is critically important to obtain objective data, and to evaluate these cues under well-controlled experimental conditions.

  9. TRP Channels

    PubMed Central

    Venkatachalam, Kartik; Montell, Craig

    2011-01-01

    The TRP (Transient Receptor Potential) superfamily of cation channels is remarkable in that it displays greater diversity in activation mechanisms and selectivities than any other group of ion channels. The domain organizations of some TRP proteins are also unusual, as they consist of linked channel and enzyme domains. A unifying theme in this group is that TRP proteins play critical roles in sensory physiology, which include contributions to vision, taste, olfaction, hearing, touch, and thermo- and osmosensation. In addition, TRP channels enable individual cells to sense changes in their local environment. Many TRP channels are activated by a variety of different stimuli and function as signal integrators. The TRP superfamily is divided into seven subfamilies: the five group 1 TRPs (TRPC, TRPV, TRPM, TRPN, and TRPA) and two group 2 subfamilies (TRPP and TRPML). TRP channels are important for human health as mutations in at least four TRP channels underlie disease. PMID:17579562

  10. Face hallucination using orthogonal canonical correlation analysis

    NASA Astrophysics Data System (ADS)

    Zhou, Huiling; Lam, Kin-Man

    2016-05-01

    A two-step face-hallucination framework is proposed to reconstruct a high-resolution (HR) version of a face from an input low-resolution (LR) face, based on learning from LR-HR example face pairs using orthogonal canonical correlation analysis (orthogonal CCA) and linear mapping. In the proposed algorithm, face images are first represented using principal component analysis (PCA). Canonical correlation analysis (CCA) with the orthogonality property is then employed, to maximize the correlation between the PCA coefficients of the LR and the HR face pairs to improve the hallucination performance. The original CCA does not own the orthogonality property, which is crucial for information reconstruction. We propose using orthogonal CCA, which is proven by experiments to achieve a better performance in terms of global face reconstruction. In addition, in the residual-compensation process, a linear-mapping method is proposed to include both the inter- and intrainformation about manifolds of different resolutions. Compared with other state-of-the-art approaches, the proposed framework can achieve a comparable, or even better, performance in terms of global face reconstruction and the visual quality of face hallucination. Experiments on images with various parameter settings and blurring distortions show that the proposed approach is robust and has great potential for real-world applications.

  11. Repetition probability effects for inverted faces.

    PubMed

    Grotheer, Mareike; Hermann, Petra; Vidnyánszky, Zoltán; Kovács, Gyula

    2014-11-15

    It has been shown, that the repetition related reduction of the blood-oxygen level dependent (BOLD) signal is modulated by the probability of repetitions (P(rep)) for faces (Summerfield et al., 2008), providing support for the predictive coding (PC) model of visual perception (Rao and Ballard, 1999). However, the stage of face processing where repetition suppression (RS) is modulated by P(rep) is still unclear. Face inversion is known to interrupt higher level configural/holistic face processing steps and if modulation of RS by P(rep) takes place at these stages of face processing, P(rep) effects are expected to be reduced for inverted when compared to upright faces. Therefore, here we aimed at investigating whether P(rep) effects on RS observed for face stimuli originate at the higher-level configural/holistic stages of face processing by comparing these effects for upright and inverted faces. Similarly to previous studies, we manipulated P(rep) for pairs of stimuli in individual blocks of fMRI recordings. This manipulation significantly influenced repetition suppression in the posterior FFA, the OFA and the LO, independently of stimulus orientation. Our results thus reveal that RS in the ventral visual stream is modulated by P(rep) even in the case of face inversion and hence strongly compromised configural/holistic face processing. An additional whole-brain analysis could not identify any areas where the modulatory effect of probability was orientation specific either. These findings imply that P(rep) effects on RS might originate from the earlier stages of face processing. PMID:25123974

  12. Energy efficient face seal

    NASA Technical Reports Server (NTRS)

    Sehnal, J.; Sedy, J.; Etsion, I.; Zobens, A.

    1982-01-01

    Torque, face temperature, leakage, and wear of a flat face seal were compared with three coned face seals at pressures up to 2758 kPa and speeds up to 8000 rpm. Axial movement of the mating seal parts was recorded by a digital data acquisition system. The coning of the tungsten carbide primary ring ranged from .51 micro-m to 5.6 micro-m. The torque of the coned face seal balanced to 76.3% was an average 42% lower, the leakage eleven times higher, than that of the standard flat face seal. The reduction of the balance of the coned face seal to 51.3% resulted by decreasing the torque by an additional 44% and increasing leakage 12 to 230 times, depending on the seal shaft speed. No measurable wear was observed on the face of the coned seals.

  13. Modeling Face Identification Processing in Children and Adults.

    ERIC Educational Resources Information Center

    Schwarzer, Gudrun; Massaro, Dominic W.

    2001-01-01

    Two experiments studied whether and how 5-year-olds integrate single facial features to identify faces. Results indicated that children could evaluate and integrate information from eye and mouth features to identify a face when salience of features was varied. A weighted Fuzzy Logical Model of Perception fit better than a Single Channel Model,…

  14. Single-shot full-field OCT based on four quadrature phase-stepped interferometer

    NASA Astrophysics Data System (ADS)

    Hrebesh, Molly Subhash; Watanabe, Yuuki; Dabu, Razvan; Sato, Manabu

    2008-02-01

    We demonstrate a compact single-shot full-field optical coherence tomography (OCT) system for obtaining real-time high-resolution depth resolved en-face OCT images from weakly scattering specimens. The experimental setup is based on a Linnik type polarization Michelson interferometer and a four-channel compact polarization phase stepper optics. The four-channel phase-stepper optics comprise of a dual channel beam splitter, a Wollaston prism and a pair of wave plate for simultaneously capturing four quadratually phase-stepped images on a single CCD. The interferometer is illuminated using a SLD source with a central wavelength of 842 nm and a bandwidth of 16.2 nm, yielding an axial resolution of 19.8 μm. Using a 10 × (0.25-NA) microscope objective and a CCD camera with 400 × 400 pixels, the system covers an area of 225 μm × 225 μm with a transverse resolution of 4.4 μm. The en-face OCT images of an onion is measured with an exposure time of 7ms and a frame rate of 28 fps.

  15. Social embodiment in directional stepping behavior.

    PubMed

    Stins, John F; Lobel, Adam; Roelofs, Karin; Beek, Peter J

    2014-08-01

    Embodiment theories emphasize the role played by sensory and motor processes in psychological states, such as social information processing. Motivated by this idea, we examined how whole-body postural behaviors couple to social affective cues, viz., pictures of smiling and angry faces. We adopted a Simon-like paradigm, whereby healthy female volunteers were asked to select and initiate a forward or backward step on a force plate in response to the gender of the poser (male/female), regardless of emotion. Detailed analysis of the spatiotemporal unfolding of the body center of pressure during the steps revealed that task-irrelevant emotion had no effect on the initiation times of the steps, i.e., there was no evidence of an affective Simon effect. An unexpected finding was that steps were initiated relatively slow in response to female angry faces. This Stroop-like effect suggests that postural behavior is influenced by whether certain stimulus features match or mismatch. PMID:24362584

  16. Acoustic imaging of the passage of turbidity currents and associated hydraulic jumps on underlying cyclic step bedforms. Squamish, BC

    NASA Astrophysics Data System (ADS)

    Hughes Clarke, J. E.

    2013-12-01

    Active channelized turbidity currents have been repeatedly imaged in 60m of water on the Squamish prodelta. Previously in 2011 and 2012, the prodelta has been repetitively surveyed on daily and hourly timescales and is thus known to exhibit trains of bedforms along the channel floors that resemble cyclic steps that migrate upslope intermittently. Beyond the channel mouths, clear turbidity current flows had previously been detected using a seabed mounted ADCP. In order to directly observe the passage of the flow in the channelized section of the prodelta, in June 2013 a vessel was moored using 4 anchors directly above one of the channels. The vessel operated two hull-mounted single beam sonars at 28 and 200 kHz and a multibeam sonar at 95 kHz, all imaging a near stationary point or swath within or across the channel. In addition a 1200 kHz ADCP was suspended 12m above the seabed and two 500 kHz imaging multibeams were suspended 10m above the channel floor. One of the suspended multibeams was oriented facing upslope examining a 150m range, 120 degree, plan view sector of the channel. The second suspended multibeam was oriented downward to derive a ~30m long along-track section over the length of one of the bedforms. A mechanically dipped CTD and optical backscatter probe was lower repeatedly directly into the active flows until it touched the seabed at about one minute periods. Over a period of 5 days, between 1 and 7 discrete flows per day were monitored passing by within one hour of low water. Their head velocities ranged from ~ 0.5 to 2.5m/s and their thicknesses were generally in the 3-5m range. Looking upstream in plan view, the lobate head of the approaching flows could be seen to be constricted to specific talwegs within the channel floor and rise up and over successive cyclic step bedforms. The higher velocity flows exhibit clear turbulent eddies on their upper surface. The duration of the high velocity component of the flow rarely lasted for more than a few

  17. Video face recognition against a watch list

    NASA Astrophysics Data System (ADS)

    Abbas, Jehanzeb; Dagli, Charlie K.; Huang, Thomas S.

    2007-10-01

    Due to a large increase in the video surveillance data recently in an effort to maintain high security at public places, we need more robust systems to analyze this data and make tasks like face recognition a realistic possibility in challenging environments. In this paper we explore a watch-list scenario where we use an appearance based model to classify query faces from low resolution videos into either a watch-list or a non-watch-list face. We then use our simple yet a powerful face recognition system to recognize the faces classified as watch-list faces. Where the watch-list includes those people that we are interested in recognizing. Our system uses simple feature machine algorithms from our previous work to match video faces against still images. To test our approach, we match video faces against a large database of still images obtained from a previous work in the field from Yahoo News over a period of time. We do this matching in an efficient manner to come up with a faster and nearly real-time system. This system can be incorporated into a larger surveillance system equipped with advanced algorithms involving anomalous event detection and activity recognition. This is a step towards more secure and robust surveillance systems and efficient video data analysis.

  18. Adsorption on a stepped substrate

    NASA Astrophysics Data System (ADS)

    Merikoski, J.; Timonen, J.; Kaski, K.

    1994-09-01

    The effect of substrate steps on the adsorption of particles is considered. The problem is formulated as a lattice-gas model with nearest neighbor interactions and it is studied by a numerical transfer-matrix method. In particular, the influence of the substrate-induced row potential on adsorbed monolayers is discussed. It is found that strong row-transition-like features appear in the presence of a row potential and it is suggested that these may be seen in adsorption on vicinal faces.

  19. Ligand-bound structures of 3-deoxy-D-manno-octulosonate 8-phosphate phosphatase from Moraxella catarrhalis reveal a water channel connecting to the active site for the second step of catalysis.

    PubMed

    Dhindwal, Sonali; Priyadarshini, Priyanka; Patil, Dipak N; Tapas, Satya; Kumar, Pramod; Tomar, Shailly; Kumar, Pravindra

    2015-02-01

    KdsC, the third enzyme of the 3-deoxy-D-manno-octulosonic acid (KDO) biosynthetic pathway, catalyzes a substrate-specific reaction to hydrolyze 3-deoxy-D-manno-octulosonate 8-phosphate to generate a molecule of KDO and phosphate. KdsC is a phosphatase that belongs to the C0 subfamily of the HAD superfamily. To understand the molecular basis for the substrate specificity of this tetrameric enzyme, the crystal structures of KdsC from Moraxella catarrhalis (Mc-KdsC) with several combinations of ligands, namely metal ion, citrate and products, were determined. Various transition states of the enzyme have been captured in these crystal forms. The ligand-free and ligand-bound crystal forms reveal that the binding of ligands does not cause any specific conformational changes in the active site. However, the electron-density maps clearly showed that the conformation of KDO as a substrate is different from the conformation adopted by KDO when it binds as a cleaved product. Furthermore, structural evidence for the existence of an intersubunit tunnel has been reported for the first time in the C0 subfamily of enzymes. A role for this tunnel in transferring water molecules from the interior of the tetrameric structure to the active-site cleft has been proposed. At the active site, water molecules are required for the formation of a water bridge that participates as a proton shuttle during the second step of the two-step phosphoryl-transfer reaction. In addition, as the KDO biosynthesis pathway is a potential antibacterial target, pharmacophore-based virtual screening was employed to identify inhibitor molecules for the Mc-KdsC enzyme. PMID:25664734

  20. A special purpose knowledge-based face localization method

    NASA Astrophysics Data System (ADS)

    Hassanat, Ahmad; Jassim, Sabah

    2008-04-01

    This paper is concerned with face localization for visual speech recognition (VSR) system. Face detection and localization have got a great deal of attention in the last few years, because it is an essential pre-processing step in many techniques that handle or deal with faces, (e.g. age, face, gender, race and visual speech recognition). We shall present an efficient method for localization human's faces in video images captured on mobile constrained devices, under a wide variation in lighting conditions. We use a multiphase method that may include all or some of the following steps starting with image pre-processing, followed by a special purpose edge detection, then an image refinement step. The output image will be passed through a discrete wavelet decomposition procedure, and the computed LL sub-band at a certain level will be transformed into a binary image that will be scanned by using a special template to select a number of possible candidate locations. Finally, we fuse the scores from the wavelet step with scores determined by color information for the candidate location and employ a form of fuzzy logic to distinguish face from non-face locations. We shall present results of large number of experiments to demonstrate that the proposed face localization method is efficient and achieve high level of accuracy that outperforms existing general-purpose face detection methods.

  1. Learning discriminant face descriptor.

    PubMed

    Lei, Zhen; Pietikäinen, Matti; Li, Stan Z

    2014-02-01

    Local feature descriptor is an important module for face recognition and those like Gabor and local binary patterns (LBP) have proven effective face descriptors. Traditionally, the form of such local descriptors is predefined in a handcrafted way. In this paper, we propose a method to learn a discriminant face descriptor (DFD) in a data-driven way. The idea is to learn the most discriminant local features that minimize the difference of the features between images of the same person and maximize that between images from different people. In particular, we propose to enhance the discriminative ability of face representation in three aspects. First, the discriminant image filters are learned. Second, the optimal neighborhood sampling strategy is soft determined. Third, the dominant patterns are statistically constructed. Discriminative learning is incorporated to extract effective and robust features. We further apply the proposed method to the heterogeneous (cross-modality) face recognition problem and learn DFD in a coupled way (coupled DFD or C-DFD) to reduce the gap between features of heterogeneous face images to improve the performance of this challenging problem. Extensive experiments on FERET, CAS-PEAL-R1, LFW, and HFB face databases validate the effectiveness of the proposed DFD learning on both homogeneous and heterogeneous face recognition problems. The DFD improves POEM and LQP by about 4.5 percent on LFW database and the C-DFD enhances the heterogeneous face recognition performance of LBP by over 25 percent. PMID:24356350

  2. Stepping motor controller

    DOEpatents

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

    1982-07-02

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

  3. Stepping motor controller

    DOEpatents

    Bourret, Steven C.; Swansen, James E.

    1984-01-01

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

  4. Phosphate stimulates CFTR Cl- channels.

    PubMed Central

    Carson, M R; Travis, S M; Winter, M C; Sheppard, D N; Welsh, M J

    1994-01-01

    Cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels appear to be regulated by hydrolysis of ATP and are inhibited by a product of hydrolysis, ADP. We assessed the effect of the other product of hydrolysis, inorganic phosphate (P(i)), on CFTR Cl- channel activity using the excised inside-out configuration of the patch-clamp technique. Millimolar concentrations of P(i) caused a dose-dependent stimulation of CFTR Cl- channel activity. Single-channel analysis demonstrated that the increase in macroscopic current was due to an increase in single-channel open-state probability (po) and not single-channel conductance. Kinetic modeling of the effect of P(i) using a linear three-state model indicated that the effect on po was predominantly the result of an increase in the rate at which the channel passed from the long closed state to the bursting state. P(i) also potentiated activity of channels studied in the presence of 10 mM ATP and stimulated Cl- currents in CFTR mutants lacking much of the R domain. Binding studies with a photoactivatable ATP analog indicated that Pi decreased the amount of bound nucleotide. These results suggest that P(i) increased CFTR Cl- channel activity by stimulating a rate-limiting step in channel opening that may occur by an interaction of P(i) at one or both nucleotide-binding domains. Images FIGURE 8 PMID:7532021

  5. Generalization of affective learning about faces to perceptually similar faces.

    PubMed

    Verosky, Sara C; Todorov, Alexander

    2010-06-01

    Different individuals have different (and different-looking) significant others, friends, and foes. The objective of this study was to investigate whether these social face environments can shape individual face preferences. First, participants learned to associate faces with positive, neutral, or negative behaviors. Then, they evaluated morphs combining novel faces with the learned faces. The morphs (65% and 80% novel faces) were within the categorical boundary of the novel faces: They were perceived as those faces in a preliminary study. Moreover, a second preliminary study showed that following the learning, the morphs' categorization as similar to the learned faces was indistinguishable from the categorization of actual novel faces. Nevertheless, in the main experiment, participants evaluated morphs of "positive" faces more positively than morphs of "negative" faces. This learning generalization effect increased as a function of the similarity of the novel faces to the learned faces. The findings suggest that general learning mechanisms based on similarity can account for idiosyncratic face preferences. PMID:20483821

  6. MEMS in microfluidic channels.

    SciTech Connect

    Ashby, Carol Iris Hill; Okandan, Murat; Michalske, Terry A.; Sounart, Thomas L.; Matzke, Carolyn M.

    2004-03-01

    Microelectromechanical systems (MEMS) comprise a new class of devices that include various forms of sensors and actuators. Recent studies have shown that microscale cantilever structures are able to detect a wide range of chemicals, biomolecules or even single bacterial cells. In this approach, cantilever deflection replaces optical fluorescence detection thereby eliminating complex chemical tagging steps that are difficult to achieve with chip-based architectures. A key challenge to utilizing this new detection scheme is the incorporation of functionalized MEMS structures within complex microfluidic channel architectures. The ability to accomplish this integration is currently limited by the processing approaches used to seal lids on pre-etched microfluidic channels. This report describes Sandia's first construction of MEMS instrumented microfluidic chips, which were fabricated by combining our leading capabilities in MEMS processing with our low-temperature photolithographic method for fabricating microfluidic channels. We have explored in-situ cantilevers and other similar passive MEMS devices as a new approach to directly sense fluid transport, and have successfully monitored local flow rates and viscosities within microfluidic channels. Actuated MEMS structures have also been incorporated into microfluidic channels, and the electrical requirements for actuation in liquids have been quantified with an elegant theory. Electrostatic actuation in water has been accomplished, and a novel technique for monitoring local electrical conductivities has been invented.

  7. Solution structure of the potassium channel inhibitor agitoxin 2: caliper for probing channel geometry.

    PubMed Central

    Krezel, A. M.; Kasibhatla, C.; Hidalgo, P.; MacKinnon, R.; Wagner, G.

    1995-01-01

    The structure of the potassium channel blocker agitoxin 2 was solved by solution NMR methods. The structure consists of a triple-stranded antiparallel beta-sheet and a single helix covering one face of the beta-sheet. The cysteine side chains connecting the beta-sheet and the helix form the core of the molecule. One edge of the beta-sheet and the adjacent face of the helix form the interface with the Shaker K+ channel. The fold of agitoxin is homologous to the previously determined folds of scorpion venom toxins. However, agitoxin 2 differs significantly from the other channel blockers in the specificity of its interactions. This study was thus focused on a precise characterization of the surface residues at the face of the protein interacting with the Shaker K+ channel. The rigid toxin molecule can be used to estimate dimensions of the potassium channel. Surface-exposed residues, Arg24, Lys27, and Arg31 of the beta-sheet, have been identified from mutagenesis studies as functionally important for blocking the Shaker K+ channel. The sequential and spatial locations of Arg24 and Arg31 are not conserved among the homologous toxins. Knowledge on the details of the channel-binding sites of agitoxin 2 formed a basis for site-directed mutagenesis studies of the toxin and the K+ channel sequences. Observed interactions between mutated toxin and channel are being used to elucidate the channel structure and mechanisms of channel-toxin interactions. PMID:8520473

  8. Face Recognition in Humans and Machines

    NASA Astrophysics Data System (ADS)

    O'Toole, Alice; Tistarelli, Massimo

    The study of human face recognition by psychologists and neuroscientists has run parallel to the development of automatic face recognition technologies by computer scientists and engineers. In both cases, there are analogous steps of data acquisition, image processing, and the formation of representations that can support the complex and diverse tasks we accomplish with faces. These processes can be understood and compared in the context of their neural and computational implementations. In this chapter, we present the essential elements of face recognition by humans and machines, taking a perspective that spans psychological, neural, and computational approaches. From the human side, we overview the methods and techniques used in the neurobiology of face recognition, the underlying neural architecture of the system, the role of visual attention, and the nature of the representations that emerges. From the computational side, we discuss face recognition technologies and the strategies they use to overcome challenges to robust operation over viewing parameters. Finally, we conclude the chapter with a look at some recent studies that compare human and machine performances at face recognition.

  9. Channel catfish

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This book chapter provides a comprehensive overview of channel catfish aquaculture. Sections include fish biology; commercial culture; culture facilities; production practices; water quality management; nutrition, feeding and feed formulation; infectious diseases; harvesting and processing; and the...

  10. Stable face representations

    PubMed Central

    Jenkins, Rob; Burton, A. Mike

    2011-01-01

    Photographs are often used to establish the identity of an individual or to verify that they are who they claim to be. Yet, recent research shows that it is surprisingly difficult to match a photo to a face. Neither humans nor machines can perform this task reliably. Although human perceivers are good at matching familiar faces, performance with unfamiliar faces is strikingly poor. The situation is no better for automatic face recognition systems. In practical settings, automatic systems have been consistently disappointing. In this review, we suggest that failure to distinguish between familiar and unfamiliar face processing has led to unrealistic expectations about face identification in applied settings. We also argue that a photograph is not necessarily a reliable indicator of facial appearance, and develop our proposal that summary statistics can provide more stable face representations. In particular, we show that image averaging stabilizes facial appearance by diluting aspects of the image that vary between snapshots of the same person. We review evidence that the resulting images can outperform photographs in both behavioural experiments and computer simulations, and outline promising directions for future research. PMID:21536553

  11. INTERIOR VIEW OF THE LIVING ROOM. SHOWING THE STEPS UP ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW OF THE LIVING ROOM. SHOWING THE STEPS UP TO THE DINING ROOM WITH IRON RAILING. VIEW FACING NORTHEAST. - Hickam Field, Officers' Housing Type F, 602 Beard Avenue, Honolulu, Honolulu County, HI

  12. 13. MASS OF POURED CONCRETE IN IRREGULAR STEPPED LAYERS AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. MASS OF POURED CONCRETE IN IRREGULAR STEPPED LAYERS AT THE BASE OF THE LEFT (EAST) BUTTRESS. CAMERA FACING SOUTHWEST. - Salinas Dam, Salinas River near Pozo Road, Santa Margarita, San Luis Obispo County, CA

  13. Solar-Cell Encapsulation by One-Step Lamination

    NASA Technical Reports Server (NTRS)

    Sarbolouki, M. N.

    1983-01-01

    Simple method of potting solar cells reduces encapsulating to one-step lamination process. Simplified process saves time and expense. Potting material is added to two inside faces of solar-cell assembly before they are sandwiched and cured.

  14. Dynamic Face Seal Arrangement

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher (Inventor)

    1999-01-01

    A radial face seal arrangement is disclosed comprising a stationary seal ring that is spring loaded against a seal seat affixed to a rotating shaft. The radial face seal arrangement further comprises an arrangement that not only allows for preloading of the stationary seal ring relative to the seal seat, but also provides for dampening yielding a dynamic seating response for the radial face seal arrangement. The overall seal system, especially regarding the selection of the material for the stationary seal ring, is designed to operate over a wide temperature range from below ambient up to 900 C.

  15. Steps in Behavior Modividation.

    ERIC Educational Resources Information Center

    Straughan, James H.; And Others

    James H. Straughan lists five steps for modifying target behavior and four steps for working with teachers using behavior modification. Grant Martin and Harold Kunzelmann then outline an instructional program for pinpointing and recording classroom behaviors. (JD)

  16. Analyzing Interactions by an IIS-Map-Based Method in Face-to-Face Collaborative Learning: An Empirical Study

    ERIC Educational Resources Information Center

    Zheng, Lanqin; Yang, Kaicheng; Huang, Ronghuai

    2012-01-01

    This study proposes a new method named the IIS-map-based method for analyzing interactions in face-to-face collaborative learning settings. This analysis method is conducted in three steps: firstly, drawing an initial IIS-map according to collaborative tasks; secondly, coding and segmenting information flows into information items of IIS; thirdly,…

  17. Faces of root polytopes in all dimensions.

    PubMed

    Szajewska, Marzena

    2016-07-01

    In this paper the root polytopes of all finite reflection groups W with a connected Coxeter-Dynkin diagram in {\\bb R}^n are identified, their faces of dimensions 0 ≤ d ≤ n - 1 are counted, and the construction of representatives of the appropriate W-conjugacy class is described. The method consists of recursive decoration of the appropriate Coxeter-Dynkin diagram [Champagne et al. (1995). Can. J. Phys. 73, 566-584]. Each recursion step provides the essentials of faces of a specific dimension and specific symmetry. The results can be applied to crystals of any dimension and any symmetry. PMID:27357848

  18. A Step Circuit Program.

    ERIC Educational Resources Information Center

    Herman, Susan

    1995-01-01

    Aerobics instructors can use step aerobics to motivate students. One creative method is to add the step to the circuit workout. By incorporating the step, aerobic instructors can accommodate various fitness levels. The article explains necessary equipment and procedures, describing sample stations for cardiorespiratory fitness, muscular strength,…

  19. One Step to Learning.

    ERIC Educational Resources Information Center

    Thornton, Carol A.; And Others

    1980-01-01

    Described are activities and games incorporating a technique of "one step" which is used with children with learning difficulties. The purpose of "one step" is twofold, to minimize difficulties with typical trouble spots and to keep the step size of the instruction small. (Author/TG)

  20. Protective Face Mask

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Mask to protect the physically impaired from injuries to the face and head has been developed by Langley Research Center. It is made of composite materials, usually graphite or boron fibers woven into a matrix. Weighs less than three ounces.

  1. Future Faces of Physics

    NASA Astrophysics Data System (ADS)

    Sauncy, Toni

    2008-10-01

    In keeping with its commitment to help students transform themselves into contributing members of the professional physics community, the Society of Physics Students National Council began efforts aimed at addressing issued of diversity in physics several years ago. One of the projects stemming from these discussions is the adoption of a 2008 theme ``The Future Faces of Physics.'' With this theme, the council aims to raise visibility and focus on issues of student diversity in physics. The initiative included the distribution of ``Future Faces of Physics Kits'' to any chapter hosting zone meetings. A highlight of the kit is the Future Faces of Physics Jeopardy set, which consists of buzzers, a score board, instructions, and a game board. The Future Faces of Physics game is a vehicle for generating discussion and raising awareness. The diversity session is hosted by the SPS Zone 13 and Zone 16 leadership.

  2. Modified drill permits one-step drilling operation

    NASA Technical Reports Server (NTRS)

    Libertone, C.

    1966-01-01

    Drill with modified cutting faces permits one-step drilling operation without chatter upon contact and premature wear. The modification of the drill, which has the same diameter as that of the desired hole, consists of a groove across the bottom of each of the cutting faces of the drill flutes.

  3. Recognizing one's own face.

    PubMed

    Kircher, T T; Senior, C; Phillips, M L; Rabe-Hesketh, S; Benson, P J; Bullmore, E T; Brammer, M; Simmons, A; Bartels, M; David, A S

    2001-01-01

    We report two studies of facial self-perception using individually tailored, standardized facial photographs of a group of volunteers and their partners. A computerized morphing procedure was used to merge each target face with an unknown control face. In the first set of experiments, a discrimination task revealed a delayed response time for the more extensively morphed self-face stimuli. In a second set of experiments, functional magnetic resonance imaging (fMRI) was used to measure brain activation while subjects viewed morphed versions of either their own or their partner's face, alternating in blocks with presentation of an unknown face. When subjects viewed themselves (minus activation for viewing an unknown face), increased blood oxygenation was detected in right limbic (hippocampal formation, insula, anterior cingulate), left prefrontal cortex and superior temporal cortex. In the partner (versus unknown) experiment, only the right insula was activated. We suggest that a neural network involving the right hemisphere in conjunction with left-sided associative and executive regions underlies the process of visual self-recognition. Together, this combination produces the unique experience of self-awareness. PMID:11062324

  4. STEP: A Futurevision, Today

    NASA Technical Reports Server (NTRS)

    1994-01-01

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

  5. Is Face Distinctiveness Gender Based?

    ERIC Educational Resources Information Center

    Baudouin, Jean-Yves; Gallay, Mathieu

    2006-01-01

    Two experiments were carried out to study the role of gender category in evaluations of face distinctiveness. In Experiment 1, participants had to evaluate the distinctiveness and the femininity-masculinity of real or artificial composite faces. The composite faces were created by blending either faces of the same gender (sexed composite faces,…

  6. TRP channels.

    PubMed

    Benemei, Silvia; Patacchini, Riccardo; Trevisani, Marcello; Geppetti, Pierangelo

    2015-06-01

    Evidence is accumulating on the role of transient receptor potential (TRP) channels, namely TRPV1, TRPA1, TRPV4 and TRPM8, expressed by C- and Aδ-fibres primary sensory neurons, in cough mechanism. Selective stimuli for these channels have been proven to provoke and, more rarely, to inhibit cough. More importantly, cough threshold to TRP agonists is increased by proinflammatory conditions, known to favour cough. Off-target effects of various drugs, such as tiotropium or desflurane, seem to produce their protective or detrimental actions on airway irritation and cough via TRPV1 and TRPA1, respectively. Thus, TRPs appear to encode the process that initiates or potentiates cough, activated by exogenous irritants and endogenous proinflammatory mediators. More research on TRP channels may result in innovative cough medicines. PMID:25725213

  7. Successful Decoding of Famous Faces in the Fusiform Face Area

    PubMed Central

    Axelrod, Vadim; Yovel, Galit

    2015-01-01

    What are the neural mechanisms of face recognition? It is believed that the network of face-selective areas, which spans the occipital, temporal, and frontal cortices, is important in face recognition. A number of previous studies indeed reported that face identity could be discriminated based on patterns of multivoxel activity in the fusiform face area and the anterior temporal lobe. However, given the difficulty in localizing the face-selective area in the anterior temporal lobe, its role in face recognition is still unknown. Furthermore, previous studies limited their analysis to occipito-temporal regions without testing identity decoding in more anterior face-selective regions, such as the amygdala and prefrontal cortex. In the current high-resolution functional Magnetic Resonance Imaging study, we systematically examined the decoding of the identity of famous faces in the temporo-frontal network of face-selective and adjacent non-face-selective regions. A special focus has been put on the face-area in the anterior temporal lobe, which was reliably localized using an optimized scanning protocol. We found that face-identity could be discriminated above chance level only in the fusiform face area. Our results corroborate the role of the fusiform face area in face recognition. Future studies are needed to further explore the role of the more recently discovered anterior face-selective areas in face recognition. PMID:25714434

  8. Voltage-gated Proton Channels

    PubMed Central

    DeCoursey, Thomas E.

    2014-01-01

    Voltage-gated proton channels, HV1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely the mechanism by which voltage-dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage-sensing domain of most other voltage-gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single-channel conductance ~103 smaller than most ion channels, voltage-dependent gating that is strongly modulated by the pH gradient, ΔpH, and potent inhibition by Zn2+ (in many species) but an absence of other potent inhibitors. The recent identification of HV1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH-dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B-cell receptor mediated responses in B lymphocytes. The most elaborate and best-established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by HV1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H+ for the production of H2O2 and HOCl, reactive oxygen species crucial to killing pathogens. PMID:23798303

  9. Attention to Faces Modulates Early Face Processing during Low but not High Face Discriminability

    PubMed Central

    Sreenivasan, Kartik K.; Goldstein, Jonathan M.; Lustig, Audrey G.; Rivas, Luis R.; Jha, Amishi P.

    2010-01-01

    In the present study, we investigated if attention to faces results in sensory gain modulation. Participants were cued to attend to faces or scenes in superimposed face-scene images while face discriminability was parametrically manipulated across images. The face-sensitive N170 event-related potential component was used as a measure of early face processing. Attention to faces modulated N170 amplitude, but only when faces were not highly discriminable. Additionally, directing attention to faces modulated later processing (~230–300 msec) for all discriminability levels. These results demonstrate that attention to faces can modulate perceptual processing of faces at multiple stages of processing, including early sensory levels. Critically, the early attentional benefit is present only when the “face signal” (i.e., the perceptual quality of the face) in the environment is suboptimal. PMID:19429962

  10. How Well Do Computer-Generated Faces Tap Face Expertise?

    PubMed Central

    Crookes, Kate; Ewing, Louise; Gildenhuys, Ju-dith; Kloth, Nadine; Hayward, William G.; Oxner, Matt; Pond, Stephen; Rhodes, Gillian

    2015-01-01

    The use of computer-generated (CG) stimuli in face processing research is proliferating due to the ease with which faces can be generated, standardised and manipulated. However there has been surprisingly little research into whether CG faces are processed in the same way as photographs of real faces. The present study assessed how well CG faces tap face identity expertise by investigating whether two indicators of face expertise are reduced for CG faces when compared to face photographs. These indicators were accuracy for identification of own-race faces and the other-race effect (ORE)–the well-established finding that own-race faces are recognised more accurately than other-race faces. In Experiment 1 Caucasian and Asian participants completed a recognition memory task for own- and other-race real and CG faces. Overall accuracy for own-race faces was dramatically reduced for CG compared to real faces and the ORE was significantly and substantially attenuated for CG faces. Experiment 2 investigated perceptual discrimination for own- and other-race real and CG faces with Caucasian and Asian participants. Here again, accuracy for own-race faces was significantly reduced for CG compared to real faces. However the ORE was not affected by format. Together these results signal that CG faces of the type tested here do not fully tap face expertise. Technological advancement may, in the future, produce CG faces that are equivalent to real photographs. Until then caution is advised when interpreting results obtained using CG faces. PMID:26535910

  11. Recognition based on two separated singular value decomposition-enriched faces

    NASA Astrophysics Data System (ADS)

    Wang, Jing-Wein; Le, Ngoc Tuyen; Lee, Jiann-Shu; Wang, Chou-Chen

    2014-11-01

    In previous studies on human face recognition, illumination pretreatment has been considered to be among the most crucial steps. We propose the illumination compensation algorithm two separated singular value decomposition (TSVD). TSVD consists of two parts, namely the division of high- and low-level images and singular value decomposition, which are implemented according to self-adapted illumination compensation to resolve the problems associated with strong variation of light and to improve face recognition performance. The mean color values of the three color channels R, G, and B are used as the thresholds, and two subimages of two types of light levels are then input with the division of the maximal mean and minimal mean, which are incorporated with light templates at various horizontal levels. The dynamic compensation coefficient is proportionately adjusted to reconstruct the subimages. Finally, two subimages are integrated to achieve illumination compensation. In addition, we combined TSVD and the projection color space (PCS) to design a new method for converting the color space called the two-level PCS. Experimental results demonstrated the efficiency of our proposed method. The proposed method not only makes the skin color of facial images appear softer but also substantially improves the accuracy of face recognition, even in facial images that were taken under conditions of lateral light or exhibit variations in posture.

  12. Double face sealing device

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce C. (Inventor)

    1991-01-01

    A double face sealing device for mounting between two surfaces to provide an airtight and fluid-tight seal between a closure member bearing one of the surfaces and a structure or housing bearing the other surface which extends around the opening or hatchway to be closed. The double face sealing device includes a plurality of sections or segments mounted to one of the surfaces, each having a main body portion, a pair of outwardly extending and diverging, cantilever, spring arms, and a pair of inwardly extending and diverging, cantilever, spring arms, an elastomeric cover on the distal, free, ends of the outwardly extending and diverging spring arms, and an elastomeric cover on the distal, free, ends of the inwardly extending and diverging spring arms. The double face sealing device has application or use in all environments requiring a seal, but is particularly useful to seal openings or hatchways between compartments of spacecraft or aircraft.

  13. Golgi-Cox Staining Step by Step

    PubMed Central

    Zaqout, Sami; Kaindl, Angela M.

    2016-01-01

    Golgi staining remains a key method to study neuronal morphology in vivo. Since most protocols delineating modifications of the original staining method lack details on critical steps, establishing this method in a laboratory can be time-consuming and frustrating. Here, we describe the Golgi-Cox staining in such detail that should turn the staining into an easily feasible method for all scientists working in the neuroscience field. PMID:27065817

  14. Clocking in the face of unpredictability beyond quantum uncertainty

    NASA Astrophysics Data System (ADS)

    Madjid, F. Hadi; Myers, John M.

    2015-05-01

    In earlier papers we showed unpredictability beyond quantum uncertainty in atomic clocks, ensuing from a proven gap between given evidence and explanations of that evidence. Here we reconceive a clock, not as an isolated entity, but as enmeshed in a self-adjusting communications network adapted to one or another particular investigation, in contact with an unpredictable environment. From the practical uses of clocks, we abstract a clock enlivened with the computational capacity of a Turing machine, modified to transmit and to receive numerical communications. Such "live clocks" phase the steps of their computations to mesh with the arrival of transmitted numbers. We lift this phasing, known in digital communications, to a principle of logical synchronization, distinct from the synchronization defined by Einstein in special relativity. Logical synchronization elevates digital communication to a topic in physics, including applications to biology. One explores how feedback loops in clocking affect numerical signaling among entities functioning in the face of unpredictable influences, making the influences themselves into subjects of investigation. The formulation of communications networks in terms of live clocks extends information theory by expressing the need to actively maintain communications channels, and potentially, to create or drop them. We show how networks of live clocks are presupposed by the concept of coordinates in a spacetime. A network serves as an organizing principle, even when the concept of the rigid body that anchors a special-relativistic coordinate system is inapplicable, as is the case, for example, in a generic curved spacetime.

  15. Neural substrates of species-dependent visual processing of faces: use of morphed faces

    PubMed Central

    Yamada, Emi; Ogata, Katsuya; Kishimoto, Junji; Tanaka, Mutsuhide; Urakawa, Tomokazu; Yamasaki, Takao; Tobimatsu, Shozo

    2015-01-01

    Face identification and categorization are essential for social communication. The N170 event-related potential (ERP) is considered to be a biomarker of face perception. To elucidate the neural basis of species-dependent face processing, we recorded 128-ch high-density ERPs in 14 healthy adults while they viewed the images of morphed faces. The morphed stimuli contained different proportions of human and monkey faces, and the species boundary was shifted away from the center of the morph continuum. Three experiments were performed to determine how task requirement, facial orientation, and spatial frequency (SF) of visual stimuli affected ERPs. In an equal SF condition, the latency, and amplitude of the occipital P100 for upright faces were modulated in a monotonic-like fashion by the level of morphing. In contrast, the N170 latency for upright faces was modulated in a step-like fashion, showing a flexion point that may reflect species discrimination. Although N170 amplitudes for upright faces were not modulated by morph level, they were modulated in a monotonic-like fashion by inverted faces. The late positive (LP) component (350–550 msec) in the parietal region was modulated in a U-shaped function by morph level during a categorization task, but not in a simple reaction task. These results suggest that P100 reflects changes in the physical properties of faces and that N170 is involved in own-species selectivity. The LP component seems to represent species categorization that occurs 350 msec after stimulus onset. PMID:25975645

  16. Neural substrates of species-dependent visual processing of faces: use of morphed faces.

    PubMed

    Yamada, Emi; Ogata, Katsuya; Kishimoto, Junji; Tanaka, Mutsuhide; Urakawa, Tomokazu; Yamasaki, Takao; Tobimatsu, Shozo

    2015-05-01

    Face identification and categorization are essential for social communication. The N170 event-related potential (ERP) is considered to be a biomarker of face perception. To elucidate the neural basis of species-dependent face processing, we recorded 128-ch high-density ERPs in 14 healthy adults while they viewed the images of morphed faces. The morphed stimuli contained different proportions of human and monkey faces, and the species boundary was shifted away from the center of the morph continuum. Three experiments were performed to determine how task requirement, facial orientation, and spatial frequency (SF) of visual stimuli affected ERPs. In an equal SF condition, the latency, and amplitude of the occipital P100 for upright faces were modulated in a monotonic-like fashion by the level of morphing. In contrast, the N170 latency for upright faces was modulated in a step-like fashion, showing a flexion point that may reflect species discrimination. Although N170 amplitudes for upright faces were not modulated by morph level, they were modulated in a monotonic-like fashion by inverted faces. The late positive (LP) component (350-550 msec) in the parietal region was modulated in a U-shaped function by morph level during a categorization task, but not in a simple reaction task. These results suggest that P100 reflects changes in the physical properties of faces and that N170 is involved in own-species selectivity. The LP component seems to represent species categorization that occurs 350 msec after stimulus onset. PMID:25975645

  17. Power module assemblies with staggered coolant channels

    DOEpatents

    Herron, Nicholas Hayden; Mann, Brooks S; Korich, Mark D

    2013-07-16

    A manifold is provided for supporting a power module assembly with a plurality of power modules. The manifold includes a first manifold section. The first face of the first manifold section is configured to receive the first power module, and the second face of the first manifold section defines a first cavity with a first baseplate thermally coupled to the first power module. The first face of the second manifold section is configured to receive the second power module, and the second face of the second manifold section defines a second cavity with a second baseplate thermally coupled to the second power module. The second face of the first manifold section and the second face of the second manifold section are coupled together such that the first cavity and the second cavity form a coolant channel. The first cavity is at least partially staggered with respect to second cavity.

  18. Neural synchronization during face-to-face communication.

    PubMed

    Jiang, Jing; Dai, Bohan; Peng, Danling; Zhu, Chaozhe; Liu, Li; Lu, Chunming

    2012-11-01

    Although the human brain may have evolutionarily adapted to face-to-face communication, other modes of communication, e.g., telephone and e-mail, increasingly dominate our modern daily life. This study examined the neural difference between face-to-face communication and other types of communication by simultaneously measuring two brains using a hyperscanning approach. The results showed a significant increase in the neural synchronization in the left inferior frontal cortex during a face-to-face dialog between partners but none during a back-to-back dialog, a face-to-face monologue, or a back-to-back monologue. Moreover, the neural synchronization between partners during the face-to-face dialog resulted primarily from the direct interactions between the partners, including multimodal sensory information integration and turn-taking behavior. The communicating behavior during the face-to-face dialog could be predicted accurately based on the neural synchronization level. These results suggest that face-to-face communication, particularly dialog, has special neural features that other types of communication do not have and that the neural synchronization between partners may underlie successful face-to-face communication. PMID:23136442

  19. Pedagogical Characteristics of Online and Face-to-Face Classes

    ERIC Educational Resources Information Center

    Wuensch, Karl; Aziz, Shahnaz; Ozan, Erol; Kishore, Masao; Tabrizi, M. H. Nassehzadeh

    2008-01-01

    Currently, many students have had experience with both face-to-face and online classes. We asked such students at 46 different universities in the United States to evaluate the pedagogical characteristics of their most recently completed face-to-face class and their most recently completed online class. The results show that students rate online…

  20. Voicing on Virtual and Face to Face Discussion

    ERIC Educational Resources Information Center

    Yamat, Hamidah

    2013-01-01

    This paper presents and discusses findings of a study conducted on pre-service teachers' experiences in virtual and face to face discussions. Technology has brought learning nowadays beyond the classroom context or time zone. The learning context and process no longer rely solely on face to face communications in the presence of a teacher.…

  1. Bayesian Face Recognition and Perceptual Narrowing in Face-Space

    ERIC Educational Resources Information Center

    Balas, Benjamin

    2012-01-01

    During the first year of life, infants' face recognition abilities are subject to "perceptual narrowing", the end result of which is that observers lose the ability to distinguish previously discriminable faces (e.g. other-race faces) from one another. Perceptual narrowing has been reported for faces of different species and different races, in…

  2. Neural correlates of face detection.

    PubMed

    Xu, Xiaokun; Biederman, Irving

    2014-06-01

    Although face detection likely played an essential adaptive role in our evolutionary past and in contemporary social interactions, there have been few rigorous studies investigating its neural correlates. MJH, a prosopagnosic with bilateral lesions to the ventral temporal-occipital cortices encompassing the posterior face areas (fusiform and occipital face areas), expresses no subjective difficulty in face detection, suggesting that these posterior face areas do not mediate face detection exclusively. Despite his normal contrast sensitivity and visual acuity in foveal vision, the present study nevertheless revealed significant face detection deficits in MJH. Compared with controls, MJH showed a lower tolerance to noise in the phase spectrum for faces (vs. cars), reflected in his higher detection threshold for faces. MJH's lesions in bilateral occipito-temporal cortices thus appear to have produced a deficit not only in face individuation, but also in face detection. PMID:23365211

  3. Unusual venous drainage of face: a case report.

    PubMed

    Maskey, Dhiraj; Baral, Prakash; Kuwar, Ram Bahadur; Rai, Dilip; Dhungel, Shaligram; Jha, Chandra Bhusan; Bhattacharya, Sounmya

    2006-12-01

    Facial region has enormous blood supply. The maxillary vein, facial vein and superficial temporal vein are chief venous draining channels. There are numerous reports of unusual venous system of face, in the present case, retromandibular vein divides into anterior and posterior division soon after its formation, external carotid artery lying lateral to retromandibular vein, formation of common venous channel between internal jugular vein and anterior jugular vein where facial, lingual and submental vein drain. PMID:17357652

  4. Pose estimation and frontal face detection for face recognition

    NASA Astrophysics Data System (ADS)

    Lim, Eng Thiam; Wang, Jiangang; Xie, Wei; Ronda, Venkarteswarlu

    2005-05-01

    This paper proposes a pose estimation and frontal face detection algorithm for face recognition. Considering it's application in a real-world environment, the algorithm has to be robust yet computationally efficient. The main contribution of this paper is the efficient face localization, scale and pose estimation using color models. Simulation results showed very low computational load when compare to other face detection algorithm. The second contribution is the introduction of low dimensional statistical face geometrical model. Compared to other statistical face model the proposed method models the face geometry efficiently. The algorithm is demonstrated on a real-time system. The simulation results indicate that the proposed algorithm is computationally efficient.

  5. Reach-scale channel geometry of mountain streams

    NASA Astrophysics Data System (ADS)

    Wohl, Ellen; Merritt, David M.

    2008-01-01

    The basic patterns and processes of steep channels remain poorly known relative to lower-gradient channels. In this analysis, characteristics of step-pool, plane-bed, and pool-riffle channels are examined using a data set of 335 channel reaches from the western United States, Nepal, New Zealand, and Panama. We analyzed differences among the three channel types with respect to hydraulics, channel geometry, boundary roughness, and bedforms. Step-pool channels have significantly steeper gradients, coarser substrate, higher values of shear stress and stream power for a given discharge, and larger ratios of bedform amplitude/wavelength ( H/ L). Pool-riffle channels have greater width/depth ratios and relative grain submergence ( R/ D84) than the other channel types. Plane-bed channels tend to have intermediate values for most variables examined. Relative form submergence ( R/ H) is statistically similar for step-pool and pool-riffle channels. Despite the lesser relative grain submergence and greater bedform amplitude of step-pool channels, mean values of Darcy-Weisbach friction factor do not change in response to changes in relative grain submergence. These patterns suggest that adjustments along mountain streams effectively maximize resistance to flow and minimize downstream variability in resistance among the different channel types.

  6. Finding faces among faces: human faces are located more quickly and accurately than other primate and mammal faces.

    PubMed

    Simpson, Elizabeth A; Buchin, Zachary; Werner, Katie; Worrell, Rey; Jakobsen, Krisztina V

    2014-11-01

    We tested the specificity of human face search efficiency by examining whether there is a broad window of detection for various face-like stimuli-human and animal faces-or whether own-species faces receive greater attentional allocation. We assessed the strength of the own-species face detection bias by testing whether human faces are located more efficiently than other animal faces, when presented among various other species' faces, in heterogeneous 16-, 36-, and 64-item arrays. Across all array sizes, we found that, controlling for distractor type, human faces were located faster and more accurately than primate and mammal faces, and that, controlling for target type, searches were faster when distractors were human faces compared to animal faces, revealing more efficient processing of human faces regardless of their role as targets or distractors (Experiment 1). Critically, these effects remained when searches were for specific species' faces (human, chimpanzee, otter), ruling out a category-level explanation (Experiment 2). Together, these results suggest that human faces may be processed more efficiently than animal faces, both when task-relevant (targets) and task-irrelevant (distractors), even in direct competition with other faces. These results suggest that there is not a broad window of detection for all face-like patterns but that human adults process own-species' faces more efficiently than other species' faces. Such own-species search efficiencies may arise through experience with own-species faces throughout development or may be privileged early in development, due to the evolutionary importance of conspecifics' faces. PMID:25113852

  7. Face recognition system and method using face pattern words and face pattern bytes

    SciTech Connect

    Zheng, Yufeng

    2014-12-23

    The present invention provides a novel system and method for identifying individuals and for face recognition utilizing facial features for face identification. The system and method of the invention comprise creating facial features or face patterns called face pattern words and face pattern bytes for face identification. The invention also provides for pattern recognitions for identification other than face recognition. The invention further provides a means for identifying individuals based on visible and/or thermal images of those individuals by utilizing computer software implemented by instructions on a computer or computer system and a computer readable medium containing instructions on a computer system for face recognition and identification.

  8. The channels of Mars

    NASA Technical Reports Server (NTRS)

    Baker, Victor R.

    1988-01-01

    The geomorphology of Mars is discussed, focusing on the Martian channels. The great flood channels of Mars, the processes of channel erosion, and dendritic channel networks, are examined. The topography of the Channeled Scabland region of the northwestern U.S. is described and compared to the Martian channels. The importance of water in the evolution of the channel systems is considered.

  9. Many Faces Have I.

    ERIC Educational Resources Information Center

    Zilliox, Joseph T.; Lowery, Shannon G.

    1997-01-01

    Describes an extended investigation of polygons and polyhedra which was conducted in response to a challenge posed in Focus, a newsletter from the Mathematical Association of America (MAA). Students were challenged to construct a polyhedron with faces that measure more than 13 inches to a side. Outlines the process, including the questions posed…

  10. Restoration of face images

    NASA Astrophysics Data System (ADS)

    Srinivasan, Aparna

    2012-01-01

    Restoration techniques are applied to degraded face samples. The techniques considered are those of Wiener Filtering, Lucy Richardson deconvolution, Blind deconvolution and Constrained least squares filtering (CLSF). Images degraded by low blur, high blur and low blur with noise are experimented with and the results are expounded.

  11. Restoration of face images

    NASA Astrophysics Data System (ADS)

    Srinivasan, Aparna

    2011-12-01

    Restoration techniques are applied to degraded face samples. The techniques considered are those of Wiener Filtering, Lucy Richardson deconvolution, Blind deconvolution and Constrained least squares filtering (CLSF). Images degraded by low blur, high blur and low blur with noise are experimented with and the results are expounded.

  12. Challenges Facing Special Education.

    ERIC Educational Resources Information Center

    Meyen, Edward L., Ed.; And Others

    This book presents 17 selected papers from recent issues of the journal, "Focus on Exceptional Children," concerning current and emerging challenges facing the field of special education. The book is organized in two parts. Part 1, "Contemporary Challenges," includes the following articles: "Transitions in Early Childhood Special Education: Issues…

  13. Workforce Issues Facing HRD.

    ERIC Educational Resources Information Center

    1999

    This document contains four symposium papers on work force issues facing human resource development (HRD). "Contributing Factors to the Success of Women and People of Color in Leadership Roles: A Message to HRD Professionals" (Jean R. McFarland, Gary Leske, Caroline S. V. Turner) reports the results of a survey in which nonwhite males, nonwhite…

  14. Problems Facing Rural Schools.

    ERIC Educational Resources Information Center

    Stewart, C. E.; And Others

    Problems facing rural Scottish schools range from short term consideration of daily operation to long term consideration of organizational alternatives. Addressed specifically, such problems include consideration of: (1) liaison between a secondary school and its feeder primary schools; (2) preservice teacher training for work in small, isolated…

  15. Facing the Not Knowing

    ERIC Educational Resources Information Center

    Tennant, Roy

    2007-01-01

    In this article, the author talks about how to face the not knowing and offers a strategy to fill the gap of not knowing. In coping with constant change, he describes a strategy for library staff that might help in the absence of certainty. This includes: (a) guarding the data with one's life; (b) build not for longevity, but obsolescence; (c)…

  16. Workforce Issues Facing HRD.

    ERIC Educational Resources Information Center

    1995

    These four papers are from a symposium facilitated by Eugene Andette on work force issues facing human resources development (HRD) at the 1995 Academy of Human Resource Development conference. "Meaning Construction and Personal Transformation: Alternative Dimensions of Job Loss" (Terri A. Deems) reports a study conducted to explore the ways…

  17. TACOMA FACES SCHOOL SEGREGATION.

    ERIC Educational Resources Information Center

    HALEY, FRED T.

    THE CHAIRMAN OF THE TACOMA, WASHINGTON, BOARD OF EDUCATION PRESENTS HIS VIEWS ON THE PROBLEMS TO BE FACED BY THE CITY OF TACOMA IN THE AREA OF DE FACTO SEGREGATION. TACOMA'S POPULATION FROM 1950 TO 1960 INCREASED 3 PERCENT. VIRTUALLY THE ENTIRE INCREASE WAS NONWHITE. IT IS HELD THAT THE MAGNITUDE OF THE EXPLOSIVE GROWTH OF THE NEGRO POPULATION IS…

  18. Lightweight Face Mask

    NASA Technical Reports Server (NTRS)

    Cason, W. E. I.; Baucom, R. M.; Evans, R. C.

    1982-01-01

    Lightweight face mask originally developed to protect epileptic patients during seizures could have many other medical and nonmedical applications such as muscular distrophy patients, football linesmen and riot-control police. Masks are extremely lightweight, the lightest of the configurations weighing only 136 grams.

  19. The Twelve Steps Experientially.

    ERIC Educational Resources Information Center

    Horne, Lianne

    Experiential activities provide each participant with the ability to see, feel, and experience whatever therapeutic issue the facilitator is addressing, and usually much more. This paper presents experiential activities to address the 12 steps of recovery adopted from Alcoholics Anonymous. These 12 steps are used worldwide for many other recovery…

  20. Starburst Channels

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1

    Translucent carbon dioxide ice covers the polar regions of Mars seasonally. It is warmed and sublimates (evaporates) from below, and escaping gas carves a numerous channel morphologies.

    In this example (figure 1) the channels form a 'starburst' pattern, radiating out into feathery extensions. The center of the pattern is being buried with dust and new darker dust fans ring the outer edges. This may be an example of an expanding morphology, where new channels are formed as the older ones fill and are no longer efficiently channeling the subliming gas out.

    Observation Geometry Image PSP_003443_0980 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 21-Apr-2007. The complete image is centered at -81.8 degrees latitude, 76.2 degrees East longitude. The range to the target site was 247.1 km (154.4 miles). At this distance the image scale is 24.7 cm/pixel (with 1 x 1 binning) so objects 74 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel. The image was taken at a local Mars time of 04:52 PM and the scene is illuminated from the west with a solar incidence angle of 71 degrees, thus the sun was about 19 degrees above the horizon. At a solar longitude of 223.4 degrees, the season on Mars is Northern Autumn.

  1. STEP Experiment Requirements

    NASA Technical Reports Server (NTRS)

    Brumfield, M. L. (Compiler)

    1984-01-01

    A plan to develop a space technology experiments platform (STEP) was examined. NASA Langley Research Center held a STEP Experiment Requirements Workshop on June 29 and 30 and July 1, 1983, at which experiment proposers were invited to present more detailed information on their experiment concept and requirements. A feasibility and preliminary definition study was conducted and the preliminary definition of STEP capabilities and experiment concepts and expected requirements for support services are presented. The preliminary definition of STEP capabilities based on detailed review of potential experiment requirements is investigated. Topics discussed include: Shuttle on-orbit dynamics; effects of the space environment on damping materials; erectable beam experiment; technology for development of very large solar array deployers; thermal energy management process experiment; photovoltaic concentrater pointing dynamics and plasma interactions; vibration isolation technology; flight tests of a synthetic aperture radar antenna with use of STEP.

  2. The Caledonian face test: A new test of face discrimination.

    PubMed

    Logan, Andrew J; Wilkinson, Frances; Wilson, Hugh R; Gordon, Gael E; Loffler, Gunter

    2016-02-01

    This study aimed to develop a clinical test of face perception which is applicable to a wide range of patients and can capture normal variability. The Caledonian face test utilises synthetic faces which combine simplicity with sufficient realism to permit individual identification. Face discrimination thresholds (i.e. minimum difference between faces required for accurate discrimination) were determined in an "odd-one-out" task. The difference between faces was controlled by an adaptive QUEST procedure. A broad range of face discrimination sensitivity was determined from a group (N=52) of young adults (mean 5.75%; SD 1.18; range 3.33-8.84%). The test is fast (3-4min), repeatable (test-re-test r(2)=0.795) and demonstrates a significant inversion effect. The potential to identify impairments of face discrimination was evaluated by testing LM who reported a lifelong difficulty with face perception. While LM's impairment for two established face tests was close to the criterion for significance (Z-scores of -2.20 and -2.27) for the Caledonian face test, her Z-score was -7.26, implying a more than threefold higher sensitivity. The new face test provides a quantifiable and repeatable assessment of face discrimination ability. The enhanced sensitivity suggests that the Caledonian face test may be capable of detecting more subtle impairments of face perception than available tests. PMID:26607479

  3. The own-age face recognition bias is task dependent.

    PubMed

    Proietti, Valentina; Macchi Cassia, Viola; Mondloch, Catherine J

    2015-08-01

    The own-age bias (OAB) in face recognition (more accurate recognition of own-age than other-age faces) is robust among young adults but not older adults. We investigated the OAB under two different task conditions. In Experiment 1 young and older adults (who reported more recent experience with own than other-age faces) completed a match-to-sample task with young and older adult faces; only young adults showed an OAB. In Experiment 2 young and older adults completed an identity detection task in which we manipulated the identity strength of target and distracter identities by morphing each face with an average face in 20% steps. Accuracy increased with identity strength and facial age influenced older adults' (but not younger adults') strategy, but there was no evidence of an OAB. Collectively, these results suggest that the OAB depends on task demands and may be absent when searching for one identity. PMID:25491773

  4. 1. Northeast face of missile site control building, commonly known ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Northeast face of missile site control building, commonly known as the missile site radar building, showing open blast door #BD2. This emergency escape, at stair no. 12, is NEMP/RFI-shielded and 16" thick. The large circle in the center is the radar face, also known as the antennae array aperture. The small circle to the right of the radar face is the "Q" channel. The antennae atop the turret provided lightning protection for the building - Stanley R. Mickelsen Safeguard Complex, Missile Site Control Building, Northeast of Tactical Road; southeast of Tactical Road South, Nekoma, Cavalier County, ND

  5. Tritium Removal from Carbon Plasma Facing Components

    SciTech Connect

    C.H. Skinner; J.P. Coad; G. Federici

    2003-11-24

    Tritium removal is a major unsolved development task for next-step devices with carbon plasma-facing components. The 2-3 order of magnitude increase in duty cycle and associated tritium accumulation rate in a next-step tokamak will place unprecedented demands on tritium removal technology. The associated technical risk can be mitigated only if suitable removal techniques are demonstrated on tokamaks before the construction of a next-step device. This article reviews the history of codeposition, the tritium experience of TFTR (Tokamak Fusion Test Reactor) and JET (Joint European Torus) and the tritium removal rate required to support ITER's planned operational schedule. The merits and shortcomings of various tritium removal techniques are discussed with particular emphasis on oxidation and laser surface heating.

  6. Nursing student experiences with face-to-face learning.

    PubMed

    Gruendemann, Barbara J

    2011-12-01

    Face-to-face learning has been the mainstay of nursing student learning. Despite moves to online learning, face-to-face learning persists. This study focuses on how nursing students experience face-to-face learning and why it not only survives, but thrives. This study was anchored in a hermeneutic phenomenological approach, with Gadamerian concepts and van Manen's lifeworlds as frameworks to understand students' experiences of face-to-face learning. Patterns and themes were extracted from audiore-corded face-to-face interviews. Participants confirmed that face-to-face learning continues to be valued as a strong methodology in nursing education. Their experiences focused on humanism, the importance of "presence," physical proximity, classroom as "the real thing," immediacy of feedback, and learning and knowing by human connections and interaction. The study findings were a rich source for understanding how nursing students process learning experiences. Increased understanding of the meaning and essence of face-to-face learning is essential as we decide how nursing content will be taught. PMID:21956259

  7. [Subperiosteal face-lift].

    PubMed

    Tessier, P

    1989-01-01

    The "facial mask" is composed of all of the tissues lying on top of the skeleton: periosteum, deep adipose tissue, superficial musculo-aponeurotic tissue and skin. The periosteum is the intermediate zone between the skeleton, responsible for the shape of the face, and the more superficial tissues which complete the shapes and, most importantly, represent the mobile part of the face and consequently the site of facial expression. The secret of an effective "mask-lift" depends on complete subperiosteal dissection of the malar bones, zygomatic arches and orbital margins. This dissection can be performed via a coronal approach, but it is easier to start the subperiosteal dissection via a short vestibular incision. Subperiosteal dissection via a coronal incision is not only useful to lift the facial mask; it is also useful for remodelling the orbital margins and to obtain bone grafts from the parietal area in order to reinforce the glabella, check bones and nasogenial folds. PMID:2473674

  8. CRYSTAL/FACE

    NASA Technical Reports Server (NTRS)

    Baumgardner, Darrel; Kok, Greg; Anderson, Bruce

    2004-01-01

    Droplet Measurement Technologies (DMT), under funding from NASA, participated in the CRYSTAL/FACE field campaign in July, 2002 with measurements of cirrus cloud hydrometeors in the size range from 0.5 to 1600 microns. The measurements were made with the DMT Cloud, Aerosol and Precipitation Spectrometer (CAPS) that was flown on NASA's WB57F. With the exception of the first research flight when the data system failed two hours into the mission, the measurement system performed almost flawlessly during the thirteen flights. The measurements from the CAPS have been essential for interpretation of cirrus cloud properties and their impact on climate. The CAPS data set has been used extensively by the CRYSTAL/FACE investigators and as of the date of this report, have been included in five published research articles, 10 conference presentations and six other journal articles currently in preparation.

  9. 'Happy Face' Crater

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-361, 15 May 2003

    Every day, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle instruments obtain a global view of the planet to help monitor weather and seasonal patterns of frost deposition and removal. The two pictures shown here are taken from the same daily global image mosaic (the only difference is that each was processed slightly differently). The pictures show Galle Crater, informally known as 'Happy Face,' as it appeared in early southern winter. The white-ish gray surfaces are coated with wintertime carbon dioxide frost. The pattern of frost distribution gives the appearance that 'Happy Face' has opened its mouth. Galle Crater is located on the east rim of Argyre at 51oS, 31oW. Sunlight illuminates the scene from the upper left. Galle Crater is 230 km (143 mi) across.

  10. Producing desired ice faces

    PubMed Central

    Shultz, Mary Jane; Brumberg, Alexandra; Bisson, Patrick J.; Shultz, Ryan

    2015-01-01

    The ability to prepare single-crystal faces has become central to developing and testing models for chemistry at interfaces, spectacularly demonstrated by heterogeneous catalysis and nanoscience. This ability has been hampered for hexagonal ice, Ih––a fundamental hydrogen-bonded surface––due to two characteristics of ice: ice does not readily cleave along a crystal lattice plane and properties of ice grown on a substrate can differ significantly from those of neat ice. This work describes laboratory-based methods both to determine the Ih crystal lattice orientation relative to a surface and to use that orientation to prepare any desired face. The work builds on previous results attaining nearly 100% yield of high-quality, single-crystal boules. With these methods, researchers can prepare authentic, single-crystal ice surfaces for numerous studies including uptake measurements, surface reactivity, and catalytic activity of this ubiquitous, fundamental solid. PMID:26512102