Passive control of coherent structures in a modified backwards-facing step flow

NASA Astrophysics Data System (ADS)

Ormonde, Pedro C.; Cavalieri, André V. G.; Silva, Roberto G. A. da; Avelar, Ana C.

2018-05-01

We study a modified backwards-facing step flow, with the addition of two different plates; one is a baseline, impermeable plate and the second a perforated one. An experimental investigation is carried out for a turbulent reattaching shear layer downstream of the two plates. The proposed setup is a model configuration to study how the plate characteristics affect the separated shear layer and how turbulent kinetic energies and large-scale coherent structures are modified. Measurements show that the perforated plate changes the mean flow field, mostly by reducing the intensity of reverse flow close to the bottom wall. Disturbance amplitudes are significantly reduced up to five step heights downstream of the trailing edge of the plate, more specifically in the recirculation region. A loudspeaker is then used to introduce phase-locked, low-amplitude perturbations upstream of the plates, and phase-averaged measurements allow a quantitative study of large-scale structures in the shear-layer. The evolution of such coherent structures is evaluated in light of linear stability theory, comparing the eigenfunction of the Kelvin-Helmholtz mode to the experimental results. We observe a close match of linear-stability eigenfunctions with phase-averaged amplitudes for the two tested Strouhal numbers. The perforated plate is found to reduce the amplitude of the Kelvin-Helmholtz coherent structures in comparison to the baseline, impermeable plate, a behavior consistent with the predicted amplification trends from linear stability.

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.

The dispersion of particles in a separated backward-facing step flow

NASA Astrophysics Data System (ADS)

Ruck, B.; Makiola, B.

1991-05-01

Flows in technical and natural circuits often involve a particulate phase. To measure the dynamics of suspended, naturally resident or artificially seeded particles in the flow, optical measuring techniques, e.g., laser Doppler anemometry (LDA) can be used advantageously. In this paper the dispersion of particles in a single-sided backward-facing step flow is investigated by LDA. The investigation is of relevance for both, two-phase flow problems in separated flows with the associated particle diameter range of 1-70 μm and the accuracy of LDA with tracer particles of different sizes. The latter is of interest for all LDA applications to measure continuous phase properties, where interest for experimental restraints require tracer diameters in the upper micrometer range, e.g., flame resistant particles for measurements inside reactors, cylinders, etc. For the experiments, a closed-loop wind tunnel with a step expansion was used. Part of this tunnel, the test section, was made of glass. The step had a height H=25 mm (channel height before the step 25 mm, after 50 mm, i.e., an expansion ratio of 2). The width of the channel was 500 mm. The length of the glass test section was chosen as 116 step heights. The wind tunnel, driven by a radial fan, allowed flow velocities up to 50 m/sec which is equivalent to ReH=105. Seeding was performed with particles of well-known size: 1, 15, 30, and 70 μm in diameter. As 1 μm tracers oil droplets were used, whereas for the upper micron range starch particles (density 1.500 kg/m3) were chosen. Starch particles have a spherical shape and are not soluble in cold water. Particle velocities were measured locally using a conventional 1-D LDA system. The measurements deliver the resultant ``flow'' field information stemming from different particle size classes. Thus, the particle behavior in the separated flow field can be resolved. The results show that with increasing particle size, the particle velocity field differs increasingly from

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.

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.

Effect of wall cooling on the stability of compressible subsonic flows over smooth humps and backward-facing steps

NASA Technical Reports Server (NTRS)

Al-Maaitah, Ayman A.; Nayfeh, Ali, H.; Ragab, Saad A.

1989-01-01

The effect of wall cooling on the two-dimensional linear stability of subsonic flows over two-dimensional surface imperfections is investigated. Results are presented for flows over smooth humps and backward-facing steps with Mach numbers up to 0.8. The results show that, whereas cooling decreases the viscous instability, it increases the shear-layer instability and hence it increases the growth rates in the separation region. The coexistence of more than one instability mechanism makes a certain degree of wall cooling most effective. For the Mach numbers 0.5 and 0.8, the optimum wall temperatures are about 80 pct and 60 pct of the adiabatic wall temperature, respectively. Increasing the Mach number decreases the effectiveness of cooling slightly and reduces the optimum wall temperature.

Experimental study of the flow over a backward-facing rounded ramp

NASA Astrophysics Data System (ADS)

Duriez, Thomas; Aider, Jean-Luc; Wesfreid, Jose Eduardo

2010-11-01

The backward-facing rounded ramp (BFR) is a very simple geometry leading to boundary layer separation, close to the backward facing step (BFS) flow. The main difference with the BFS flow is that the separation location depends on the incoming flow while it is fixed to the step edge for the BFS flow. Despite the simplicity of the geometry, the flow is complex and the transition process still has to be investigated. In this study we investigate the BFR flow using time-resolved PIV. For Reynolds number ranging between 300 and 12 000 we first study the time averaged properties such as the positions of the separation and reattachment, the recirculation length and the shear layer thickness. The time resolution also gives access to the characteristic frequencies of the time-dependant flow. An appropriate Fourier filtering of the flow field, around each frequency peak in the global spectrum, allows an investigation of each mode in order to extract its wavelength, phase velocity, and spatial distribution. We then sort the spectral content and relate the main frequencies to the most amplified Kelvin-Helmholtz instability mode and its harmonics, the vortex pairing, the low frequency recirculation bubble oscillation and the interactions between all these phenomena.

Recovery of forward stepping in spinal cord injured patients does not transfer to untrained backward stepping.

PubMed

Grasso, Renato; Ivanenko, Yuri P; Zago, Myrka; Molinari, Marco; Scivoletto, Giorgio; Lacquaniti, Francesco

2004-08-01

Six spinal cord injured (SCI) patients were trained to step on a treadmill with body-weight support for 1.5-3 months. At the end of training, foot motion recovered the shape and the step-by-step reproducibility that characterize normal gait. They were then asked to step backward on the treadmill belt that moved in the opposite direction relative to standard forward training. In contrast to healthy subjects, who can immediately reverse the direction of walking by time-reversing the kinematic waveforms, patients were unable to step backward. Similarly patients were unable to perform another untrained locomotor task, namely stepping in place on the idle treadmill. Two patients who were trained to step backward for 2-3 weeks were able to develop control of foot motion appropriate for this task. The results show that locomotor improvement does not transfer to untrained tasks, thus supporting the idea of task-dependent plasticity in human locomotor networks.

Separated and Recovering Turbulent Boundary Layer Flow Behind a Backward Facing Step For Different Reynolds Numbers

NASA Technical Reports Server (NTRS)

Jovic, Srba; Kutler, Paul F. (Technical Monitor)

1994-01-01

Experimental results for a two-dimensional separated turbulent boundary layer behind a backward facing step for five different Reynolds numbers are reported. Results are presented in the form of tables, graphs and a floppy disk for an easy access of the data. Reynolds number based on the step height was varied by changing the reference velocity upstream of the step, U(sub o), and the step height, h. Hot-wire measurement techniques were used to measure three Reynolds stresses and four triple-velocity correlations. In addition, surface pressure and skin friction coefficients were measured. All hot-wire measurements were acquired in a measuring domain which excluded recirculating flow region due to the directional insensitivity of hot-wires. The downstream extent of the domain from the step was 51 h for the largest and I 14h for the smallest step height. This significant downstream length permitted extensive study of the flow recovery. Prediction of perturbed flows and their recovery is particularly attractive for popular turbulence models since variations of turbulence length and time scales and flow interactions in different regions are generally inadequately predicted. The data indicate that the flow in the free shear layer region behaves like the plane mixing layer up to about 2/3 of the mean reattachment length when the flow interaction with the wall commences the flow recovery to that of an ordinary turbulent boundary layer structure. These changes of the flow do not occur abruptly with the change of boundary conditions. A reattachment region represents a transitional region where the flow undergoes the most dramatic adjustments to the new boundary conditions. Large eddies, created in the upstream free-shear layer region, are being torn, recirculated, reentrained back into the main stream interacting with the incoming flow structure. It is foreseeable that it is quite difficult to describe the physics of this region in a rational and quantitative manner other

Whole-Motion Model of Perception during Forward- and Backward-Facing Centrifuge Runs

PubMed Central

Holly, Jan E.; Vrublevskis, Arturs; Carlson, Lindsay E.

2009-01-01

Illusory perceptions of motion and orientation arise during human centrifuge runs without vision. Asymmetries have been found between acceleration and deceleration, and between forward-facing and backward-facing runs. Perceived roll tilt has been studied extensively during upright fixed-carriage centrifuge runs, and other components have been studied to a lesser extent. Certain, but not all, perceptual asymmetries in acceleration-vs-deceleration and forward-vs-backward motion can be explained by existing analyses. The immediate acceleration-deceleration roll-tilt asymmetry can be explained by the three-dimensional physics of the external stimulus; in addition, longer-term data has been modeled in a standard way using physiological time constants. However, the standard modeling approach is shown in the present research to predict forward-vs-backward-facing symmetry in perceived roll tilt, contradicting experimental data, and to predict perceived sideways motion, rather than forward or backward motion, around a curve. The present work develops a different whole-motion-based model taking into account the three-dimensional form of perceived motion and orientation. This model predicts perceived forward or backward motion around a curve, and predicts additional asymmetries such as the forward-backward difference in roll tilt. This model is based upon many of the same principles as the standard model, but includes an additional concept of familiarity of motions as a whole. PMID:19208962

Entrainment effects in periodic forcing of the flow over a backward-facing step

NASA Astrophysics Data System (ADS)

Berk, T.; Medjnoun, T.; Ganapathisubramani, B.

2017-07-01

The effect of the Strouhal number on periodic forcing of the flow over a backward-facing step (height, H ) is investigated experimentally. Forcing is applied by a synthetic jet at the edge of the step at Strouhal numbers ranging from 0.21

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.

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.

Numerical solutions of pulsating flow and heat transfer characteristics in a channel with a backward-facing step

NASA Astrophysics Data System (ADS)

Valencia, A.; Hinojosa, L.

The incompressible laminar flow of air and heat transfer in a channel with a backward-facing step is studied for steady cases and for pulsatile inlet conditions. For steady flows the influence of the inlet velocity profile, the height of the step and the Reynolds number on the reattachment length is investigated. A parabolic entrance profile was used for pulsatile flow. It was found with amplitude of oscillation of one by Re=100 that the primary vortex breakdown through one pulsatile cycle. The wall shear rate in the separation zone varied markedly with pulsatile flows and the wall heat transfer remained relatively constant. The time-average pulsatile heat transfer at the walls was greater as with steady flow with the same mean Reynolds number. Zusammenfassung Es wird eine zweidimensionale numerische Untersuchung des instationären Wärmeübergangs und Druckverlustes im laminar durchströmten Spaltkanal mit einer plötzlichen Kanalerweiterung dargelegt und zwar für stationäre und periodische Geschwindigkeitsprofile am Eintritt des Kanals. Für stationäre Strömungen wurden die Form des Eintrittsprofils, die Reynoldszahl und die Kanalerweiterung variiert. Als Lösung der Navier/Stokes-und der Energiegleichungen mit periodischen Randbedingungen resultiert eine oszillierende Strömung, die das Aufplatzen des Primärwirbels in einer Schwingungsperiode zur Folge hat. Der Einfluß dieser Oszillation auf den Wärmeübergang und den Strömungsverlust wurde für die maximale Amplitude und für Re=100 eingehend untersucht.

The Effect of Acoustic Forcing on Instabilities and Breakdown in Swept-Wing Flow over a Backward-Facing Step

NASA Technical Reports Server (NTRS)

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

2016-01-01

Instability interaction and breakdown were experimentally investigated in the flow over a swept backward-facing step. Acoustic forcing was used to excite the Tollmien-Schlichting (TS) instability and to acquire phase-locked results. The phase-averaged results illustrate the complex nature of the interaction between the TS and stationary cross flow instabilities. The weak stationary cross flow disturbance causes a distortion of the TS wavefront. The breakdown process is characterized by large positive and negative spikes in velocity. The positive spikes occur near the same time and location as the positive part of the TS wave. Higher-order spectral analysis was used to further investigate the nonlinear interactions between the TS instability and the traveling cross flow disturbances. The results reveal that a likely cause for the generation of the spikes corresponds to nonlinear interactions between the TS, traveling cross flow, and stationary cross flow disturbances. The spikes begin at low amplitudes of the unsteady and steady disturbances (2-4% U (sub e) (i.e. boundary layer edge velocity)) but can achieve very large amplitudes (20-30 percent U (sub e) (i.e. boundary layer edge velocity)) that initiate an early, though highly intermittent, breakdown to turbulence.

Investigation of obstacle effect to improve conjugate heat transfer in backward facing step channel using fast simulation of incompressible flow

NASA Astrophysics Data System (ADS)

Nouri-Borujerdi, Ali; Moazezi, Arash

2018-01-01

The current study investigates the conjugate heat transfer characteristics for laminar flow in backward facing step channel. All of the channel walls are insulated except the lower thick wall under a constant temperature. The upper wall includes a insulated obstacle perpendicular to flow direction. The effect of obstacle height and location on the fluid flow and heat transfer are numerically explored for the Reynolds number in the range of 10 ≤ Re ≤ 300. Incompressible Navier-Stokes and thermal energy equations are solved simultaneously in fluid region by the upwind compact finite difference scheme based on flux-difference splitting in conjunction with artificial compressibility method. In the thick wall, the energy equation is obtained by Laplace equation. A multi-block approach is used to perform parallel computing to reduce the CPU time. Each block is modeled separately by sharing boundary conditions with neighbors. The developed program for modeling was written in FORTRAN language with OpenMP API. The obtained results showed that using of the multi-block parallel computing method is a simple robust scheme with high performance and high-order accurate. Moreover, the obtained results demonstrated that the increment of Reynolds number and obstacle height as well as decrement of horizontal distance between the obstacle and the step improve the heat transfer.

Hot Film Velocity Measurements Downstream of a Swept Backward-Facing Step

DTIC Science & Technology

1990-08-01

WR ~4’ nol w of tdl. O64" $l"uwe. suite 424 i lV~lZdO . 00 to effice at UAqeww0fl" S4 aud ’mpeom t, 0edUOM ’l~c 004 S~ a lleq~k Dc 2010). I. AGENCY USE ...Velocity measurements were made using a single component hot film anemometer. Results from this study indicate the following: the flow in the recirculation...velocity component parallel to the step face retains a finite magnitude. Coles’ law of the wall and wake was used to corralate the data from this study. The

A successful backward step correlates with hip flexion moment of supporting limb in elderly people.

PubMed

Takeuchi, Yahiko

2018-01-01

The objective of this study was to determine the positional relationship between the center of mass (COM) and the center of pressure (COP) at the time of step landing, and to examine their relationship with the joint moments exerted by the supporting limb, with regard to factors of the successful backward step response. The study population comprised 8 community-dwelling elderly people that were observed to take successive multi steps after the landing of a backward stepping. Using a motion capture system and force plate, we measured the COM, COP and COM-COP deviation distance on landing during backward stepping. In addition, we measured the moment of the supporting limb joint during backward stepping. The multi-step data were compared with data from instances when only one step was taken (single-step). Variables that differed significantly between the single- and multi-step data were used as objective variables and the joint moments of the supporting limb were used as explanatory variables in single regression analyses. The COM-COP deviation in the anteroposterior was significantly larger in the single-step. A regression analysis with COM-COP deviation as the objective variable obtained a significant regression equation in the hip flexion moment (R2 = 0.74). The hip flexion moment of supporting limb was shown to be a significant explanatory variable in both the PS and SS phases for the relationship with COM-COP distance. This study found that to create an appropriate backward step response after an external disturbance (i.e. the ability to stop after 1 step), posterior braking of the COM by a hip flexion moment are important during the single-limbed standing phase.

The Importance of Splat Events to the Spatiotemporal Structure of Near-Bed Fluid Velocity and Bed Load Motion Over Bed Forms: Laboratory Experiments Downstream of a Backward Facing Step

NASA Astrophysics Data System (ADS)

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

2017-12-01

Flow separation/reattachment on the lee side of alluvial bed forms is known to produce a complex turbulence field, but the spatiotemporal details of the associated patterns of bed load sediment transported remain largely unknown. Here we report turbulence-resolving, simultaneous measurements of bed load motion and near-bed fluid velocity downstream of a backward facing step in a laboratory flume. 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 (PIV) and Acoustic Doppler Velocimetry (ADV) were used to characterize fluid turbulent patterns, while manual particle tracking techniques were used to characterize bed load transport. Octant analysis, conducted using ADV data, coupled with Markovian sequence probability analysis highlights differences in the flow near reattachment versus farther downstream. Near reattachment, three distinct flow patterns are apparent. Farther downstream we see the development of a dominant flow sequence. Localized, intermittent, high-magnitude transport events are more apparent near flow reattachment. These events are composed of streamwise and cross-stream fluxes of comparable magnitudes. Transport pattern and fluid velocity data are consistent with the existence of permeable "splat events," wherein a volume of fluid moves toward and impinges on the bed (sweep) causing a radial movement of fluid in all directions around the point of impingement (outward interaction). This is congruent with flow patterns, identified with octant analysis, proximal to flow reattachment.

Regularization techniques for backward--in--time evolutionary PDE problems

NASA Astrophysics Data System (ADS)

Gustafsson, Jonathan; Protas, Bartosz

2007-11-01

Backward--in--time evolutionary PDE problems have applications in the recently--proposed retrograde data assimilation. We consider the terminal value problem for the Kuramoto--Sivashinsky equation (KSE) in a 1D periodic domain as our model system. The KSE, proposed as a model for interfacial and combustion phenomena, is also often adopted as a toy model for hydrodynamic turbulence because of its multiscale and chaotic dynamics. Backward--in--time problems are typical examples of ill-posed problem, where disturbances are amplified exponentially during the backward march. Regularization is required to solve such problems efficiently and we consider approaches in which the original ill--posed problem is approximated with a less ill--posed problem obtained by adding a regularization term to the original equation. While such techniques are relatively well--understood for linear problems, they less understood in the present nonlinear setting. We consider regularization terms with fixed magnitudes and also explore a novel approach in which these magnitudes are adapted dynamically using simple concepts from the Control Theory.

Back off! The effect of emotion on backward step initiation.

PubMed

Bouman, Daniëlle; Stins, John F

2018-02-01

The distance regulation (DR) hypothesis states that actors are inclined to increase their distance from an unpleasant stimulus. The current study investigated the relation between emotion and its effect on the control of backward step initiation, which constitutes an avoidance-like behavior. Participants stepped backward on a force plate in response to neutral, high-arousing pleasant and high-arousing unpleasant visual emotional stimuli. Gait initiation parameters and the results of an exploratory analysis of postural sway were compared across the emotion categories using significance testing and Bayesian statistics. Evidence was found that gait initiation parameters were largely unaffected by emotional conditions. In contrast, the exploratory analysis of postural immobility showed a significant effect: highly arousing stimuli (pleasant and unpleasant) resulted in more postural sway immediately preceding gait initiation compared to neutral stimuli. This suggests that arousal, rather than valence, affects pre-step sway. These results contradict the DR hypothesis, since avoidance gait-initiation in response to unpleasant stimuli was no different compared to pleasant stimuli. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Time Resolved Stereo Particle Image Velocimetry Measurements of the Instabilities Downstream of a Backward-Facing Step in a Swept-Wing Boundary Layer

NASA Technical Reports Server (NTRS)

Eppink, Jenna L.; Yao, Chung-Sheng

2017-01-01

Time-resolved particle image velocimetry (TRPIV) measurements are performed down-stream of a swept backward-facing step, with a height of 49% of the boundary-layer thickness. The results agree well qualitatively with previously reported hotwire measurements, though the amplitudes of the fluctuating components measured using TRPIV are higher. Nonetheless, the low-amplitude instabilities in the flow are fairly well resolved using TR- PIV. Proper orthogonal decomposition is used to study the development of the traveling cross flow and Tollmien-Schlichting (TS) instabilities downstream of the step and to study how they interact to form the large velocity spikes that ultimately lead to transition. A secondary mode within the traveling cross flow frequency band develops with a wavelength close to that of the stationary cross flow instability, so that at a certain point in the phase, it causes an increase in the spanwise modulation initially caused by the stationary cross flow mode. This increased modulation leads to an increase in the amplitude of the TS mode, which, itself, is highly modulated through interactions with the stationary cross flow. When the traveling cross flow and TS modes align in time and space, the large velocity spikes occur. Thus, these three instabilities, which are individually of low amplitude when the spikes start to occur (U'rms/Ue <0.03), interact and combine to cause a large flow disturbance that eventually leads to transition.

Hybrid mesh finite volume CFD code for studying heat transfer in a forward-facing step

NASA Astrophysics Data System (ADS)

Jayakumar, J. S.; Kumar, Inder; Eswaran, V.

2010-12-01

Computational fluid dynamics (CFD) methods employ two types of grid: structured and unstructured. Developing the solver and data structures for a finite-volume solver is easier than for unstructured grids. But real-life problems are too complicated to be fitted flexibly by structured grids. Therefore, unstructured grids are widely used for solving real-life problems. However, using only one type of unstructured element consumes a lot of computational time because the number of elements cannot be controlled. Hence, a hybrid grid that contains mixed elements, such as the use of hexahedral elements along with tetrahedral and pyramidal elements, gives the user control over the number of elements in the domain, and thus only the domain that requires a finer grid is meshed finer and not the entire domain. This work aims to develop such a finite-volume hybrid grid solver capable of handling turbulence flows and conjugate heat transfer. It has been extended to solving flow involving separation and subsequent reattachment occurring due to sudden expansion or contraction. A significant effect of mixing high- and low-enthalpy fluid occurs in the reattached regions of these devices. This makes the study of the backward-facing and forward-facing step with heat transfer an important field of research. The problem of the forward-facing step with conjugate heat transfer was taken up and solved for turbulence flow using a two-equation model of k-ω. The variation in the flow profile and heat transfer behavior has been studied with the variation in Re and solid to fluid thermal conductivity ratios. The results for the variation in local Nusselt number, interface temperature and skin friction factor are presented.

Influence of emotion on the biomechanical organization of backward and forward step initiation.

PubMed

Yiou, Eric; Gendre, Manon; Deroche, Thomas; Le Bozec, Serge

2014-10-01

This study examined how pleasant and unpleasant emotional states influence the biomechanical organization of both forward and backward step initiation (SI). Participants (N = 31) purposely took a single step toward or away from a screen following the presentation of a pleasant (erotic), unpleasant (mutilation) or neutral (objects and landscapes) image. The main results showed that the reaction time for forward SI was shortened when individuals were exposed to pleasant pictures as compared with unpleasant pictures. The anticipatory whole-body center-of-mass velocity associated with backward SI, as well as the peak of center-of-mass velocity associated with forward SI both reached lower values when individuals were exposed to pleasant pictures as compared with neutral pictures. In contrast, unpleasant pictures did not significantly induce any change in the forward or backward SI parameters. Overall, these results obtained for whole-body approach/avoidance-like behaviors provided mitigated support for the so-called "motivational direction hypothesis."

Body configuration at first stepping-foot contact predicts backward balance recovery capacity in people with chronic stroke.

PubMed

de Kam, Digna; Roelofs, Jolanda M B; Geurts, Alexander C H; Weerdesteyn, Vivian

2018-01-01

To determine the predictive value of leg and trunk inclination angles at stepping-foot contact for the capacity to recover from a backward balance perturbation with a single step in people after stroke. Twenty-four chronic stroke survivors and 21 healthy controls were included in a cross-sectional study. We studied reactive stepping responses by subjecting participants to multidirectional stance perturbations at different intensities on a translating platform. In this paper we focus on backward perturbations. Participants were instructed to recover from the perturbations with maximally one step. A trial was classified as 'success' if balance was restored according to this instruction. We recorded full-body kinematics and computed: 1) body configuration parameters at first stepping-foot contact (leg and trunk inclination angles) and 2) spatiotemporal step parameters (step onset, step length, step duration and step velocity). We identified predictors of balance recovery capacity using a stepwise logistic regression. Perturbation intensity was also included as a predictor. The model with spatiotemporal parameters (perturbation intensity, step length and step duration) could correctly classify 85% of the trials as success or fail (Nagelkerke R2 = 0.61). In the body configuration model (Nagelkerke R2 = 0.71), perturbation intensity and leg and trunk angles correctly classified the outcome of 86% of the recovery attempts. The goodness of fit was significantly higher for the body configuration model compared to the model with spatiotemporal variables (p<0.01). Participant group and stepping leg (paretic or non-paretic) did not significantly improve the explained variance of the final body configuration model. Body configuration at stepping-foot contact is a valid and clinically feasible indicator of backward fall risk in stroke survivors, given its potential to be derived from a single sagittal screenshot.

Data-driven backward chaining

NASA Technical Reports Server (NTRS)

Haley, Paul

1991-01-01

The C Language Integrated Production System (CLIPS) cannot effectively perform sound and complete logical inference in most real-world contexts. The problem facing CLIPS is its lack of goal generation. Without automatic goal generation and maintenance, forward chaining can only deduce all instances of a relationship. Backward chaining, which requires goal generation, allows deduction of only that subset of what is logically true which is also relevant to ongoing problem solving. Goal generation can be mimicked in simple cases using forward chaining. However, such mimicry requires manual coding of additional rules which can assert an inadequate goal representation for every condition in every rule that can have corresponding facts derived by backward chaining. In general, for N rules with an average of M conditions per rule the number of goal generation rules required is on the order of N*M. This is clearly intractable from a program maintenance perspective. We describe the support in Eclipse for backward chaining which it automatically asserts as it checks rule conditions. Important characteristics of this extension are that it does not assert goals which cannot match any rule conditions, that 2 equivalent goals are never asserted, and that goals persist as long as, but no longer than, they remain relevant.

Backward masked fearful faces enhance contralateral occipital cortical activity for visual targets within the spotlight of attention

PubMed Central

Reinke, Karen S.; LaMontagne, Pamela J.; Habib, Reza

2011-01-01

Spatial attention has been argued to be adaptive by enhancing the processing of visual stimuli within the ‘spotlight of attention’. We previously reported that crude threat cues (backward masked fearful faces) facilitate spatial attention through a network of brain regions consisting of the amygdala, anterior cingulate and contralateral visual cortex. However, results from previous functional magnetic resonance imaging (fMRI) dot-probe studies have been inconclusive regarding a fearful face-elicited contralateral modulation of visual targets. Here, we tested the hypothesis that the capture of spatial attention by crude threat cues would facilitate processing of subsequently presented visual stimuli within the masked fearful face-elicited ‘spotlight of attention’ in the contralateral visual cortex. Participants performed a backward masked fearful face dot-probe task while brain activity was measured with fMRI. Masked fearful face left visual field trials enhanced activity for spatially congruent targets in the right superior occipital gyrus, fusiform gyrus and lateral occipital complex, while masked fearful face right visual field trials enhanced activity in the left middle occipital gyrus. These data indicate that crude threat elicited spatial attention enhances the processing of subsequent visual stimuli in contralateral occipital cortex, which may occur by lowering neural activation thresholds in this retinotopic location. PMID:20702500

Lagrangian coherent structures during combustion instability in a premixed-flame backward-step combustor.

PubMed

Sampath, Ramgopal; Mathur, Manikandan; Chakravarthy, Satyanarayanan R

2016-12-01

This paper quantitatively examines the occurrence of large-scale coherent structures in the flow field during combustion instability in comparison with the flow-combustion-acoustic system when it is stable. For this purpose, the features in the recirculation zone of the confined flow past a backward-facing step are studied in terms of Lagrangian coherent structures. The experiments are conducted at a Reynolds number of 18600 and an equivalence ratio of 0.9 of the premixed fuel-air mixture for two combustor lengths, the long duct corresponding to instability and the short one to the stable case. Simultaneous measurements of the velocity field using time-resolved particle image velocimetry and the CH^{*} chemiluminescence of the flame along with pressure time traces are obtained. The extracted ridges of the finite-time Lyapunov exponent (FTLE) fields delineate dynamically distinct regions of the flow field. The presence of large-scale vortical structures and their modulation over different time instants are well captured by the FTLE ridges for the long combustor where high-amplitude acoustic oscillations are self-excited. In contrast, small-scale vortices signifying Kelvin-Helmholtz instability are observed in the short duct case. Saddle-type flow features are found to separate the distinct flow structures for both combustor lengths. The FTLE ridges are found to align with the flame boundaries in the upstream regions, whereas farther downstream, the alignment is weaker due to dilatation of the flow by the flame's heat release. Specifically, the FTLE ridges encompass the flame curl-up for both the combustor lengths, and thus act as the surrogate flame boundaries. The flame is found to propagate upstream from an earlier vortex roll-up to a newer one along the backward-time FTLE ridge connecting the two structures.

A least-squares finite element method for incompressible Navier-Stokes problems

NASA Technical Reports Server (NTRS)

Jiang, Bo-Nan

1992-01-01

A least-squares finite element method, based on the velocity-pressure-vorticity formulation, is developed for solving steady incompressible Navier-Stokes problems. This method leads to a minimization problem rather than to a saddle-point problem by the classic mixed method and can thus accommodate equal-order interpolations. This method has no parameter to tune. The associated algebraic system is symmetric, and positive definite. Numerical results for the cavity flow at Reynolds number up to 10,000 and the backward-facing step flow at Reynolds number up to 900 are presented.

How to find home backwards? Locomotion and inter-leg coordination during rearward walking of Cataglyphis fortis desert ants.

PubMed

Pfeffer, Sarah E; Wahl, Verena L; Wittlinger, Matthias

2016-07-15

For insects, flexibility in the performance of terrestrial locomotion is a vital part of facing the challenges of their often unpredictable environment. Arthropods such as scorpions and crustaceans can switch readily from forward to backward locomotion, but in insects this behaviour seems to be less common and, therefore, is only poorly understood. Here we present an example of spontaneous and persistent backward walking in Cataglyphis desert ants that allows us to investigate rearward locomotion within a natural context. When ants find a food item that is too large to be lifted up and to be carried in a normal forward-faced orientation, they will drag the load walking backwards to their home nest. A detailed examination of this behaviour reveals a surprising flexibility of the locomotor output. Compared with forward walks with regular tripod coordination, no main coordination pattern can be assigned to rearward walks. However, we often observed leg-pair-specific stepping patterns. The front legs frequently step with small stride lengths, while the middle and the hind legs are characterized by less numerous but larger strides. But still, these specializations show no rigidly fixed leg coupling, nor are they strictly embedded within a temporal context; therefore, they do not result in a repetitive coordination pattern. The individual legs act as separate units, most likely to better maintain stability during backward dragging. © 2016. Published by The Company of Biologists Ltd.

The Analysis of Forward and Backward Dynamic Programming for Multistage Graph

NASA Astrophysics Data System (ADS)

Sitinjak, Anna Angela; Pasaribu, Elvina; Simarmata, Justin E.; Putra, Tedy; Mawengkang, Herman

2018-01-01

Dynamic programming is an optimization approach that divides the complex problems into the simple sequences of problems in which they are interrelated leading to decisions. In the dynamic programming, there is no standard formula that can be used to make a certain formulation. In this paper we use forward and backward method to find path which have the minimum cost and to know whether they make the same final decision. Convert the problem into several successive sequential stages starting on from stages 1,2,3 and 4 for forward dynamic programming and the step back from stage 4.3,2,1 for backward dynamic programming and interconnected with a decision rule in each stage. Find the optimal solution with cost principle at next stage. Based on the characteristics of the dynamic programming, the case is divided into several stages and the decision is has to be made (xk) at each stage. The results obtained at a stage are used for the states in the next stage so that at the forward stage 1, f1 (s) is obtained and used as a consideration of the decision in the next stage. In the backward, used firstly stage 4, f4 (s) is obtained and used as a consideration of the decision in the next stage. Cost forward and backward always increase steadily, because the cost in the next stage depends on the cost in the previous stage and formed the decision of each stage by taking the smallest fk value. Therefore the forward and backward approaches have the same result.

Linear system identification via backward-time observer models

NASA Technical Reports Server (NTRS)

Juang, Jer-Nan; Phan, Minh

1993-01-01

This paper presents an algorithm to identify a state-space model of a linear system using a backward-time approach. The procedure consists of three basic steps. First, the Markov parameters of a backward-time observer are computed from experimental input-output data. Second, the backward-time observer Markov parameters are decomposed to obtain the backward-time system Markov parameters (backward-time pulse response samples) from which a backward-time state-space model is realized using the Eigensystem Realization Algorithm. Third, the obtained backward-time state space model is converted to the usual forward-time representation. Stochastic properties of this approach will be discussed. Experimental results are given to illustrate when and to what extent this concept works.

Numerical analysis of laminar and turbulent incompressible flows using the finite element Fluid Dynamics Analysis Package (FIDAP)

NASA Technical Reports Server (NTRS)

Sohn, Jeong L.

1988-01-01

The purpose of the study is the evaluation of the numerical accuracy of FIDAP (Fluid Dynamics Analysis Package). Accordingly, four test problems in laminar and turbulent incompressible flows are selected and the computational results of these problems compared with other numerical solutions and/or experimental data. These problems include: (1) 2-D laminar flow inside a wall-driven cavity; (2) 2-D laminar flow over a backward-facing step; (3) 2-D turbulent flow over a backward-facing step; and (4) 2-D turbulent flow through a turn-around duct.

A Semi-linear Backward Parabolic Cauchy Problem with Unbounded Coefficients of Hamilton–Jacobi–Bellman Type and Applications to Optimal Control

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

Addona, Davide, E-mail: d.addona@campus.unimib.it

2015-08-15

We obtain weighted uniform estimates for the gradient of the solutions to a class of linear parabolic Cauchy problems with unbounded coefficients. Such estimates are then used to prove existence and uniqueness of the mild solution to a semi-linear backward parabolic Cauchy problem, where the differential equation is the Hamilton–Jacobi–Bellman equation of a suitable optimal control problem. Via backward stochastic differential equations, we show that the mild solution is indeed the value function of the controlled equation and that the feedback law is verified.

Physical modeling of vortical cross-step flow in the American paddlefish, Polyodon spathula

PubMed Central

Brooks, Hannah; Haines, Grant E.; Lin, M. Carly

2018-01-01

Vortical cross-step filtration in suspension-feeding fish has been reported recently as a novel mechanism, distinct from other biological and industrial filtration processes. Although crossflow passing over backward-facing steps generates vortices that can suspend, concentrate, and transport particles, the morphological factors affecting this vortical flow have not been identified previously. In our 3D-printed models of the oral cavity for ram suspension-feeding fish, the angle of the backward-facing step with respect to the model’s dorsal midline affected vortex parameters significantly, including rotational, tangential, and axial speed. These vortices were comparable to those quantified downstream of the backward-facing steps that were formed by the branchial arches of preserved American paddlefish in a recirculating flow tank. Our data indicate that vortices in cross-step filtration have the characteristics of forced vortices, as the flow of water inside the oral cavity provides the external torque required to sustain forced vortices. Additionally, we quantified a new variable for ram suspension feeding termed the fluid exit ratio. This is defined as the ratio of the total open pore area for water leaving the oral cavity via spaces between branchial arches that are not blocked by gill rakers, divided by the total area for water entering through the gape during ram suspension feeding. Our experiments demonstrated that the fluid exit ratio in preserved paddlefish was a significant predictor of the flow speeds that were quantified anterior of the rostrum, at the gape, directly dorsal of the first ceratobranchial, and in the forced vortex generated by the first ceratobranchial. Physical modeling of vortical cross-step filtration offers future opportunities to explore the complex interactions between structural features of the oral cavity, vortex parameters, motile particle behavior, and particle morphology that determine the suspension, concentration, and

How to find home backwards? Navigation during rearward homing of Cataglyphis fortis desert ants.

PubMed

Pfeffer, Sarah E; Wittlinger, Matthias

2016-07-15

Cataglyphis ants are renowned for their impressive navigation skills, which have been studied in numerous experiments during forward locomotion. However, the ants' navigational performance during backward homing when dragging large food loads has not been investigated until now. During backward locomotion, the odometer has to deal with unsteady motion and irregularities in inter-leg coordination. The legs' sensory feedback during backward walking is not just a simple reversal of the forward stepping movements: compared with forward homing, ants are facing towards the opposite direction during backward dragging. Hence, the compass system has to cope with a flipped celestial view (in terms of the polarization pattern and the position of the sun) and an inverted retinotopic image of the visual panorama and landmark environment. The same is true for wind and olfactory cues. In this study we analyze for the first time backward-homing ants and evaluate their navigational performance in channel and open field experiments. Backward-homing Cataglyphis fortis desert ants show remarkable similarities in the performance of homing compared with forward-walking ants. Despite the numerous challenges emerging for the navigational system during backward walking, we show that ants perform quite well in our experiments. Direction and distance gauging was comparable to that of the forward-walking control groups. Interestingly, we found that backward-homing ants often put down the food item and performed foodless search loops around the left food item. These search loops were mainly centred around the drop-off position (and not around the nest position), and increased in length the closer the ants came to their fictive nest site. © 2016. Published by The Company of Biologists Ltd.

Using Backward Design in Education Research: A Research Methods Essay †

PubMed Central

Jensen, Jamie L.; Bailey, Elizabeth G.; Kummer, Tyler A.; Weber, K. Scott

2017-01-01

Education research within the STEM disciplines applies a scholarly approach to teaching and learning, with the intent of better understanding how people learn and of improving pedagogy at the undergraduate level. Most of the professionals practicing in this field have ‘crossed over’ from other disciplinary fields and thus have faced challenges in becoming experts in a new discipline. In this article, we offer a novel framework for approaching education research design called Backward Design in Education Research. It is patterned on backward curricular design and provides a three-step, systematic approach to designing education projects: 1) Define a research question that leads to a testable causal hypothesis based on a theoretical rationale; 2) Choose or design the assessment instruments to test the research hypothesis; and 3) Develop an experimental protocol that will be effective in testing the research hypothesis. This approach provides a systematic method to develop and carry out evidence-based research design. PMID:29854045

Groundwater Source Identification Using Backward Fractional-Derivative Models

NASA Astrophysics Data System (ADS)

Zhang, Y.; Sun, H.; Zheng, C.

2017-12-01

The forward Fractional Advection Dispersion Equation (FADE) provides a useful model for non-Fickian transport in heterogeneous porous media. This presentation introduces the corresponding backward FADE model, to identify groundwater source location and release time. The backward method is developed from the theory of inverse problems, and the resultant backward FADE differs significantly from the traditional backward ADE because the fractional derivative is not self-adjoint and the probability density function for backward locations is highly skewed. Finally, the method is validated using tracer data from well-known field experiments.

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…

Ordered Backward XPath Axis Processing against XML Streams

NASA Astrophysics Data System (ADS)

Nizar M., Abdul; Kumar, P. Sreenivasa

Processing of backward XPath axes against XML streams is challenging for two reasons: (i) Data is not cached for future access. (ii) Query contains steps specifying navigation to the data that already passed by. While there are some attempts to process parent and ancestor axes, there are very few proposals to process ordered backward axes namely, preceding and preceding-sibling. For ordered backward axis processing, the algorithm, in addition to overcoming the limitations on data availability, has to take care of ordering constraints imposed by these axes. In this paper, we show how backward ordered axes can be effectively represented using forward constraints. We then discuss an algorithm for XML stream processing of XPath expressions containing ordered backward axes. The algorithm uses a layered cache structure to systematically accumulate query results. Our experiments show that the new algorithm gains remarkable speed up over the existing algorithm without compromising on bufferspace requirement.

Forward-facing steps induced transition in a subsonic boundary layer

NASA Astrophysics Data System (ADS)

Zh, Hui; Fu, Song

2017-10-01

A forward-facing step (FFS) immersed in a subsonic boundary layer is studied through a high-order flux reconstruction (FR) method to highlight the flow transition induced by the step. The step height is a third of the local boundary-layer thickness. The Reynolds number based on the step height is 720. Inlet disturbances are introduced giving rise to streamwise vortices upstream of the step. It is observed that these small-scale streamwise structures interact with the step and hairpin vortices are quickly developed after the step leading to flow transition in the boundary layer.

Using an isomorphic problem pair to learn introductory physics: Transferring from a two-step problem to a three-step problem

NASA Astrophysics Data System (ADS)

Lin, Shih-Yin; Singh, Chandralekha

2013-12-01

In this study, we examine introductory physics students’ ability to perform analogical reasoning between two isomorphic problems which employ the same underlying physics principles but have different surface features. 382 students from a calculus-based and an algebra-based introductory physics course were administered a quiz in the recitation in which they had to learn from a solved problem provided and take advantage of what they learned from it to solve another isomorphic problem (which we call the quiz problem). The solved problem provided has two subproblems while the quiz problem has three subproblems, which is known from previous research to be challenging for introductory students. In addition to the solved problem, students also received extra scaffolding supports that were intended to help them discern and exploit the underlying similarities of the isomorphic solved and quiz problems. The data analysis suggests that students had great difficulty in transferring what they learned from a two-step problem to a three-step problem. Although most students were able to learn from the solved problem to some extent with the scaffolding provided and invoke the relevant principles in the quiz problem, they were not necessarily able to apply the principles correctly. We also conducted think-aloud interviews with six introductory students in order to understand in depth the difficulties they had and explore strategies to provide better scaffolding. The interviews suggest that students often superficially mapped the principles employed in the solved problem to the quiz problem without necessarily understanding the governing conditions underlying each principle and examining the applicability of the principle in the new situation in an in-depth manner. Findings suggest that more scaffolding is needed to help students in transferring from a two-step problem to a three-step problem and applying the physics principles appropriately. We outline a few possible strategies

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.

Stepped Care Versus Direct Face-to-Face Cognitive Behavior Therapy for Social Anxiety Disorder and Panic Disorder: A Randomized Effectiveness Trial.

PubMed

Nordgreen, Tine; Haug, Thomas; Öst, Lars-Göran; Andersson, Gerhard; Carlbring, Per; Kvale, Gerd; Tangen, Tone; Heiervang, Einar; Havik, Odd E

2016-03-01

The aim of this study was to assess the effectiveness of a cognitive behavioral therapy (CBT) stepped care model (psychoeducation, guided Internet treatment, and face-to-face CBT) compared with direct face-to-face (FtF) CBT. Patients with panic disorder or social anxiety disorder were randomized to either stepped care (n=85) or direct FtF CBT (n=88). Recovery was defined as meeting two of the following three criteria: loss of diagnosis, below cut-off for self-reported symptoms, and functional improvement. No significant differences in intention-to-treat recovery rates were identified between stepped care (40.0%) and direct FtF CBT (43.2%). The majority of the patients who recovered in the stepped care did so at the less therapist-demanding steps (26/34, 76.5%). Moderate to large within-groups effect sizes were identified at posttreatment and 1-year follow-up. The attrition rates were high: 41.2% in the stepped care condition and 27.3% in the direct FtF CBT condition. These findings indicate that the outcome of a stepped care model for anxiety disorders is comparable to that of direct FtF CBT. The rates of improvement at the two less therapist-demanding steps indicate that stepped care models might be useful for increasing patients' access to evidence-based psychological treatments for anxiety disorders. However, attrition in the stepped care condition was high, and research regarding the factors that can improve adherence should be prioritized. Copyright © 2015. Published by Elsevier Ltd.

Re-evaluation of an Optimized Second Order Backward Difference (BDF2OPT) Scheme for Unsteady Flow Applications

NASA Technical Reports Server (NTRS)

Vatsa, Veer N.; Carpenter, Mark H.; Lockard, David P.

2009-01-01

Recent experience in the application of an optimized, second-order, backward-difference (BDF2OPT) temporal scheme is reported. The primary focus of the work is on obtaining accurate solutions of the unsteady Reynolds-averaged Navier-Stokes equations over long periods of time for aerodynamic problems of interest. The baseline flow solver under consideration uses a particular BDF2OPT temporal scheme with a dual-time-stepping algorithm for advancing the flow solutions in time. Numerical difficulties are encountered with this scheme when the flow code is run for a large number of time steps, a behavior not seen with the standard second-order, backward-difference, temporal scheme. Based on a stability analysis, slight modifications to the BDF2OPT scheme are suggested. The performance and accuracy of this modified scheme is assessed by comparing the computational results with other numerical schemes and experimental data.

Theoretical face pressure and drag characteristics of forward-facing steps in supersonic turbulent boundary layers

NASA Technical Reports Server (NTRS)

Patel, D. K.; Czarnecki, K. R.

1975-01-01

A theoretical investigation of the pressure distributions and drag characteristics was made for forward facing steps in turbulent flow at supersonic speeds. An approximate solution technique proposed by Uebelhack has been modified and extended to obtain a more consistent numerical procedure. A comparison of theoretical calculations with experimental data generally indicated good agreement over the experimentally available range of ratios of step height to boundary layer thickness from 7 to 0.05.

A numerical solution of the supersonic flow over a rearward facing step with transverse non-reacting hydrogen injection

NASA Technical Reports Server (NTRS)

Berman, H. A.; Anderson, J. D., Jr.; Drummond, J. P.

1982-01-01

The present investigation represents an application of computational fluid dynamics to a problem associated with the flow in the combustor region of a supersonic combustion ramjet engine (scramjet). The governing equations are considered, taking into account the Navier-Stokes equations, a molecular viscosity calculation, the molecular thermal conductivity, molecular diffusion, and a turbulence model. The employed numerical solution is patterned after the explicit, time-dependent, unsplit, predictor-corrector, finite-difference method given by MacCormack (1969). The calculation is concerned with the supersonic flow over a rearward-facing step with transverse H2 injection at conditions germane to the combustor region of a scramjet engine. The H2 jet acts as an effective body which essentially shields the primary flow from the rearward-facing step, thus substantially changing the wave pattern in the primary flow.

How Ants Use Vision When Homing Backward.

PubMed

Schwarz, Sebastian; Mangan, Michael; Zeil, Jochen; Webb, Barbara; Wystrach, Antoine

2017-02-06

Ants can navigate over long distances between their nest and food sites using visual cues [1, 2]. Recent studies show that this capacity is undiminished when walking backward while dragging a heavy food item [3-5]. This challenges the idea that ants use egocentric visual memories of the scene for guidance [1, 2, 6]. Can ants use their visual memories of the terrestrial cues when going backward? Our results suggest that ants do not adjust their direction of travel based on the perceived scene while going backward. Instead, they maintain a straight direction using their celestial compass. This direction can be dictated by their path integrator [5] but can also be set using terrestrial visual cues after a forward peek. If the food item is too heavy to enable body rotations, ants moving backward drop their food on occasion, rotate and walk a few steps forward, return to the food, and drag it backward in a now-corrected direction defined by terrestrial cues. Furthermore, we show that ants can maintain their direction of travel independently of their body orientation. It thus appears that egocentric retinal alignment is required for visual scene recognition, but ants can translate this acquired directional information into a holonomic frame of reference, which enables them to decouple their travel direction from their body orientation and hence navigate backward. This reveals substantial flexibility and communication between different types of navigational information: from terrestrial to celestial cues and from egocentric to holonomic directional memories. VIDEO ABSTRACT. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

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

Considering the reversibility of passive and reactive transport problems: Are forward-in-time and backward-in-time models ever equivalent?

NASA Astrophysics Data System (ADS)

Engdahl, N.

2017-12-01

Backward in time (BIT) simulations of passive tracers are often used for capture zone analysis, source area identification, and generation of travel time and age distributions. The BIT approach has the potential to become an immensely powerful tool for direct inverse modeling but the necessary relationships between the processes modeled in the forward and backward models have yet to be formally established. This study explores the time reversibility of passive and reactive transport models in a variety of 2D heterogeneous domains using particle-based random walk methods for the transport and nonlinear reaction steps. Distributed forward models are used to generate synthetic observations that form the initial conditions for the backward in time models and we consider both linear-flood and point injections. The results for passive travel time distributions show that forward and backward models are not exactly equivalent but that the linear-flood BIT models are reasonable approximations. Point based BIT models fall within the travel time range of the forward models, though their distributions can be distinctive in some cases. The BIT approximation is not as robust when nonlinear reactive transport is considered and we find that this reaction system is only exactly reversible under uniform flow conditions. We use a series of simplified, longitudinally symmetric, but heterogeneous, domains to illustrate the causes of these discrepancies between the two model types. Many of the discrepancies arise because diffusion is a "self-adjoint" operator, which causes mass to spread in the forward and backward models. This allows particles to enter low velocity regions in the both models, which has opposite effects in the forward and reverse models. It may be possible to circumvent some of these limitations using an anti-diffusion model to undo mixing when time is reversed, but this is beyond the capabilities of the existing Lagrangian methods.

The effects of backward walking training on balance and mobility in an individual with chronic incomplete spinal cord injury: A case report.

PubMed

Foster, Hannah; DeMark, Lou; Spigel, Pamela M; Rose, Dorian K; Fox, Emily J

2016-10-01

Individuals with incomplete spinal cord injuries (ISCIs) commonly face persistent gait impairments. Backward walking training may be a useful rehabilitation approach, providing novel gait and balance challenges. However, little is known about the effects of this approach for individuals with ISCIs. The purpose of this case report was to describe the effects of backward walking training on strength, balance, and upright mobility in an individual with chronic ISCI. A 28-year-old female, 11-years post ISCI (C4, AIS D) completed 18-sessions of backward walking training on a treadmill with partial body-weight support and overground. Training emphasized stepping practice, speed, and kinematics. Outcome measures included: Lower Extremity Motor Score, Berg Balance Scale (BBS), Sensory Organization Test (SOT), 10-Meter Walk Test (10MWT), 3-meter backward walking test, Timed Up and Go (TUG), and Activities-Specific Balance Confidence (ABC) Scale. Strength did not change. Improved balance was evident based on BBS (20 to 37/56) and SOT scores (27 to 40/100). Upright mobility improved based on TUG times (57 to 32.7 s), increased 10MWT speed (0.23 to 0.31 m/s), and backward gait speed (0.07 to 0.12 m/s). Additionally, self-reported balance confidence (ABC Scale) increased from 36.9% to 49.6%. The results suggest that backward walking may be a beneficial rehabilitation approach; examination of the clinical efficacy is warranted.

The effects of backward walking training on balance and mobility in an individual with chronic incomplete spinal cord injury: A case report

PubMed Central

Foster, Hannah; DeMark, Lou; Spigel, Pamela M.; Rose, Dorian K.; Fox, Emily J.

2016-01-01

Background/Purpose Individuals with incomplete spinal cord injuries (ISCIs) commonly face persistent gait impairments. Backward walking training may be a useful rehabilitation approach, providing novel gait and balance challenges. However, little is known about the effects of this approach for individuals with ISCIs. The purpose of this case report was to describe the effects of backward walking training on strength, balance and upright mobility in an individual with chronic ISCI. Methods A 28-year-old female, 11-years post ISCI (C4, AIS D) completed 18-sessions of backward walking training on a treadmill with partial body-weight support and overground. Training emphasized stepping practice, speed, and kinematics. Outcome measures included: Lower Extremity Motor Score, Berg Balance Scale (BBS), Sensory Organization Test (SOT); 10-Meter Walk Test (10MWT), 3-meter backward walking test, Timed Up and Go (TUG), and Activities-Specific Balance Confidence (ABC) Scale. Results Strength did not change. Improved balance was evident based on BBS (20 to 37/56) and SOT scores (27 to 40/100). Upright mobility improved based on TUG times (57 to 32.7 s), increased 10MWT speed (0.23 to 0.31 m/s), and backward gait speed (0.07 to 0.12 m/s). Additionally, self-reported balance confidence (ABC Scale) increased from 36.9% to 49.6%. Conclusions The results suggest that backward walking may be a beneficial rehabilitation approach; examination of the clinical efficacy is warranted. PMID:27482619

Teaching Domestic Violence Online: A Step Forward or a Step Backward?

PubMed

Danis, Fran S

2016-10-01

With the increasing number of courses and degree programs available online, faculty may be interested in developing an online course on domestic violence. This article analyzes the similarities and differences involved in teaching about domestic violence online versus face-to-face. Highlights of course activities and notable online resources are identified including YouTube videos, webinars, online training modules, and websites. The limitations and challenges of teaching domestic violence in an asynchronous online course and recommendations for future teaching are discussed. © The Author(s) 2016.

Variations in backward masking with different masking stimuli: II. The effects of spatially quantised masks in the light of local contour interaction, interchannel inhibition, perceptual retouch, and substitution theories.

PubMed

Bachmann, Talis; Luiga, Iiris; Põder, Endel

2005-01-01

In part I we showed that with spatially non-overlapping targets and masks both local metacontrast-like interactions and attentional processes are involved in backward masking. In this second part we extend the strategy of varying the contents of masks to pattern masking where targets and masks overlap in space, in order to compare different masking theories. Images of human faces were backward-masked by three types of spatially quantised masks (the same faces as targets, faces different from targets, and Gaussian noise with power spectra typical for faces). Configural characteristics, rather than the spectral content of the mask, predicted the extent of masking at relatively long stimulus onset asynchronies (SOAs). This poses difficulties for the theory of transient-on-sustained inhibition as the principal mechanism of masking and also for local contour interaction being a decisive factor in pattern masking. The scale of quantisation had no effect on the masking capacity of noise masks and a strong effect on the capacity of different-face masks. Also, the decrease of configural masking with an increase in the coarseness of the quantisation of the mask highlights ambiguities inherent in the re-entrance-based substitution theory of masking. Different masking theories cannot solve the problems of masking separately. They should be combined in order to create a complex, yet comprehensible mode of interaction for the different mechanisms involved in visual backward masking.

On regularization and error estimates for the backward heat conduction problem with time-dependent thermal diffusivity factor

NASA Astrophysics Data System (ADS)

Karimi, Milad; Moradlou, Fridoun; Hajipour, Mojtaba

2018-10-01

This paper is concerned with a backward heat conduction problem with time-dependent thermal diffusivity factor in an infinite "strip". This problem is drastically ill-posed which is caused by the amplified infinitely growth in the frequency components. A new regularization method based on the Meyer wavelet technique is developed to solve the considered problem. Using the Meyer wavelet technique, some new stable estimates are proposed in the Hölder and Logarithmic types which are optimal in the sense of given by Tautenhahn. The stability and convergence rate of the proposed regularization technique are proved. The good performance and the high-accuracy of this technique is demonstrated through various one and two dimensional examples. Numerical simulations and some comparative results are presented.

Technology Confidence, Competence and Problem Solving Strategies: Differences within Online and Face-to-Face Formats

ERIC Educational Resources Information Center

Peterson, Sharon L.; Palmer, Louann Bierlein

2011-01-01

This study identified the problem solving strategies used by students within a university course designed to teach pre-service teachers educational technology, and whether those strategies were influenced by the format of the course (i.e., face-to-face computer lab vs. online). It also examined to what extent the type of problem solving strategies…

Being forward not backward: lexical limits to masked priming.

PubMed

Davis, Chris; Kim, Jeesun; Forster, Kenneth I

2008-05-01

This study investigated whether masked priming is mediated by existing memory representations by determining whether nonwords targets would show repetition priming. To avoid the potential confound that nonword repetition priming would be obscured by a familiarity response bias, the standard lexical decision and naming tasks were modified to make targets unfamiliar. Participants were required to read a target string from right to left (i.e., "ECAF" should be read as "FACE") and then make a response. To examine if priming was based on lexical representations, repetition primes consisted of words when read forwards or backwards (e.g., "face", "ecaf") and nonwords (e.g., "pame", "emap"). Forward and backward primes were used to test if task instruction affected prime encoding. The lexical decision and naming tasks showed the same pattern of results: priming only occurred for forward primes with word targets (e.g., "face-ECAF"). Additional experiments to test if response priming affected the LDT indicated that the lexical status of the prime per se did not affect target responses. These results showed that the encoding of masked primes was unaffected by the novel task instruction and support the view that masked priming is due to the automatic triggering of pre-established computational processes based on stored information.

The Effect of Forward-Facing Steps on Stationary Crossflow Instability Growth and Breakdown

NASA Technical Reports Server (NTRS)

Eppink, Jenna L.

2018-01-01

The e?ect of a forward-facing step on stationary cross?ow transition was studied using standard stereo particle image velocimetry (PIV) and time-resolved PIV. Step heights ranging from 53 to 71% of the boundary-layer thickness were studied in detail. The steps above a critical step height of approximately 60% of the boundary-layer thickness had a signi?cant impact on the stationary cross?ow growth downstream of the step. For the critical cases, the stationary cross?ow amplitude grew suddenly downstream of the step, decayed for a short region, then grew again. The adverse pressure gradient upstream of the step resulted in a region of cross?ow reversal. A secondary set of vortices, rotating in the opposite direction to the primary vortices, developed underneath the uplifted primary vortices. The wall-normal velocity disturbance (V' ) created by these secondary vortices impacted the step, and is believed to feed into the strong vortex that developed downstream of the step. A large but very short negative cross?ow region formed for a short region downstream of the step due to a sharp inboard curvature of the streamlines near the wall. For the larger step height cases, a cross?ow-reversal region formed just downstream of the strong negative cross?ow region. This cross?ow reversal region is believed to play an important role in the growth of the stationary cross?ow vortices downstream of the step, and may be a good indication of the critical forward-facing step height.

Critical Problems Facing Technology Education: Perceptions of Indiana Teachers

ERIC Educational Resources Information Center

Lazaros, Edward J.; Rogers, George E.

2006-01-01

In 1993 Wicklein conducted a study to determine the present and the future critical issues and problems facing the technology education (TE) profession. The Wicklein study questioned 25 panelists from 15 states and the District of Columbia to ascertain the issues and problems facing TE. However, in the Wicklein study, only seven of the panelists…

Spatial Attention-Related Modulation of the N170 by Backward Masked Fearful Faces

ERIC Educational Resources Information Center

Carlson, Joshua M.; Reinke, Karen S.

2010-01-01

Facial expressions are a basic form of non-verbal communication that convey important social information to others. The relevancy of this information is highlighted by findings that backward masked facial expressions facilitate spatial attention. This attention effect appears to be mediated through a neural network consisting of the amygdala,…

Kinematic Adaptations of Forward And Backward Walking on Land and in Water

PubMed Central

Cadenas-Sanchez, Cristina; Arellano, Raúl; Vanrenterghem, Jos; López-Contreras, Gracia

2015-01-01

The aim of this study was to compare sagittal plane lower limb kinematics during walking on land and submerged to the hip in water. Eight healthy adults (age 22.1 ± 1.1 years, body height 174.8 ± 7.1 cm, body mass 63.4 ± 6.2 kg) were asked to cover a distance of 10 m at comfortable speed with controlled step frequency, walking forward or backward. Sagittal plane lower limb kinematics were obtained from three dimensional video analysis to compare spatiotemporal gait parameters and joint angles at selected events using two-way repeated measures ANOVA. Key findings were a reduced walking speed, stride length, step length and a support phase in water, and step length asymmetry was higher compared to the land condition (p<0.05). At initial contact, knees and hips were more flexed during walking forward in water, whilst, ankles were more dorsiflexed during walking backward in water. At final stance, knees and ankles were more flexed during forward walking, whilst the hip was more flexed during backward walking. These results show how walking in water differs from walking on land, and provide valuable insights into the development and prescription of rehabilitation and training programs. PMID:26839602

A face versus non-face context influences amygdala responses to masked fearful eye whites.

PubMed

Kim, M Justin; Solomon, Kimberly M; Neta, Maital; Davis, F Caroline; Oler, Jonathan A; Mazzulla, Emily C; Whalen, Paul J

2016-12-01

The structure of the mask stimulus is crucial in backward masking studies and we recently demonstrated such an effect when masking faces. Specifically, we showed that activity of the amygdala is increased to fearful facial expressions masked with neutral faces and decreased to fearful expressions masked with a pattern mask-but critically both masked conditions discriminated fearful expressions from happy expressions. Given this finding, we sought to test whether masked fearful eye whites would produce a similar profile of amygdala response in a face vs non-face context. During functional magnetic resonance imaging scanning sessions, 30 participants viewed fearful or happy eye whites masked with either neutral faces or pattern images. Results indicated amygdala activity was increased to fearful vs happy eye whites in the face mask condition, but decreased to fearful vs happy eye whites in the pattern mask condition-effectively replicating and expanding our previous report. Our data support the idea that the amygdala is responsive to fearful eye whites, but that the nature of this activity observed in a backward masking design depends on the mask stimulus. © The Author (2016). Published by Oxford University Press.

Relative Effects of Forward and Backward Planning on Goal Pursuit.

PubMed

Park, Jooyoung; Lu, Fang-Chi; Hedgcock, William M

2017-11-01

Considerable research has shown that planning plays an important role in goal pursuit. But how does the way people plan affect goal pursuit? Research on this question is scarce. In the current research, we examined how planning the steps required for goal attainment in chronological order (i.e., forward planning) and reverse chronological order (i.e., backward planning) influences individuals' motivation for and perceptions of goal pursuit. Compared with forward planning, backward planning not only led to greater motivation, higher goal expectancy, and less time pressure but also resulted in better goal-relevant performance. We further demonstrated that this motivational effect occurred because backward planning allowed people to think of tasks required to reach their goals more clearly, especially when goals were complex to plan. These findings suggest that the way people plan matters just as much as whether or not they plan.

Backward Masking: Evidence of Reduced Subcortical Amygdala Engagement in Autism

ERIC Educational Resources Information Center

Hall, Geoffrey B. C.; West, C. Dianne; Szatmari, Peter

2007-01-01

Recent data suggest that subthreshold presentation of emotional information is relayed to the amygdala along subcortical pathways. We examined the effect of backward masked neutral and anxious faces on the social decisions of a group of high functioning children with autism ages 7-13 years and matched controls. Participants were asked to select…

Aerodynamic Impact of an Aft-Facing Slat-Step on High Re Airfoils

NASA Astrophysics Data System (ADS)

Kibble, Geoffrey; Petrin, Chris; Jacob, Jamey; Elbing, Brian; Ireland, Peter; Black, Buddy

2016-11-01

Typically, the initial aerodynamic design and subsequent testing and simulation of an aircraft wing assumes an ideal wing surface without imperfections. In reality, however the surface of an in-service aircraft wing rarely matches the surface characteristics of the test wings used during the conceptual design phase and certification process. This disconnect is usually deemed negligible or overlooked entirely. Specifically, many aircraft incorporate a leading edge slat; however, the mating between the slat and the top surface of the wing is not perfectly flush and creates a small aft-facing step behind the slat. In some cases, the slat can create a step as large as one millimeter tall, which is entirely submerged within the boundary layer. This abrupt change in geometry creates a span-wise vortex behind the step and in transonic flow causes a shock to form near the leading edge. This study investigates both experimentally and computationally the implications of an aft-facing slat-step on an aircraft wing and is compared to the ideal wing surface for subsonic and transonic flow conditions. The results of this study are useful for design of flow control modifications for aircraft currently in service and important for improving the next generation of aircraft wings.

Counting to 20: Online Implementation of a Face-to-Face, Elementary Mathematics Methods Problem-Solving Activity

ERIC Educational Resources Information Center

Schwartz, Catherine Stein

2012-01-01

This study describes implementation of the same problem-solving activity in both online and face-to-face environments. The activity, done in the first class period or first module of a K-2 mathematics methods course, was initially used in a face-to-face class and then adapted later for use in an online class. While the task was originally designed…

A stochastic maximum principle for backward control systems with random default time

NASA Astrophysics Data System (ADS)

Shen, Yang; Kuen Siu, Tak

2013-05-01

This paper establishes a necessary and sufficient stochastic maximum principle for backward systems, where the state processes are governed by jump-diffusion backward stochastic differential equations with random default time. An application of the sufficient stochastic maximum principle to an optimal investment and capital injection problem in the presence of default risk is discussed.

Biomechanical characteristics of adults walking forward and backward in water at different stride frequencies.

PubMed

Cadenas-Sánchez, Cristina; Arellano, Raúl; Taladriz, Sonia; López-Contreras, Gracia

2016-01-01

The aim of this study was to examine spatiotemporal characteristics and joint angles during forward and backward walking in water at low and high stride frequency. Eight healthy adults (22.1 ± 1.1 years) walked forward and backward underwater at low (50 pulses) and high frequency (80 pulses) at the xiphoid process level with arms crossed at the chest. The main differences observed were that the participants presented a greater speed (0.58 vs. 0.85 m/s) and more asymmetry of the step length (1.24 vs. 1.48) at high frequency whilst the stride and step length (0.84 vs. 0.7 m and 0.43 vs. 0.35 m, respectively) were lower compared to low frequency (P < 0.05). Support phase duration was higher at forward walking than backward walking (61.2 vs. 59.0%). At initial contact, we showed that during forward walking, the ankle and hip presented more flexion than during backward walking (ankle: 84.0 vs. 91.8º and hip: 22.8 vs. 8.0º; P < 0.001). At final stance, the knee and hip were more flexed at low frequency than at high frequency (knee: 150.0 vs. 157.0º and hip: -12.2 vs. -14.5º; P < 0.001). The knee angle showed more flexion at forward walking (134.0º) than backward walking (173.1º) (P < 0.001). In conclusion, these results show how forward and backward walking in water at different frequencies differ and contribute to a better understanding of this activity in training and rehabilitation.

Computation and analysis of backward ray-tracing in aero-optics flow fields.

PubMed

Xu, Liang; Xue, Deting; Lv, Xiaoyi

2018-01-08

A backward ray-tracing method is proposed for aero-optics simulation. Different from forward tracing, the backward tracing direction is from the internal sensor to the distant target. Along this direction, the tracing in turn goes through the internal gas region, the aero-optics flow field, and the freestream. The coordinate value, the density, and the refractive index are calculated at each tracing step. A stopping criterion is developed to ensure the tracing stops at the outer edge of the aero-optics flow field. As a demonstration, the analysis is carried out for a typical blunt nosed vehicle. The backward tracing method and stopping criterion greatly simplify the ray-tracing computations in the aero-optics flow field, and they can be extended to our active laser illumination aero-optics study because of the reciprocity principle.

Experimental instruction in photonics for high school students: approaches to managing problems faced

NASA Astrophysics Data System (ADS)

Choong, Zhengyang

2017-08-01

Student research projects are increasingly common at the K-12 level. However, students often face difficulties in the course of their school research projects such as setting realistic timelines and expectations, handling problems stemming from a lack of self-confidence, as well as being sufficiently disciplined for sustained communication and experimentation. In this work, we explore manifestations of these problems in the context of a photonics project, characterising the spectrum of the breakdown flash from Silicon Avalanche Photodiodes. We report on the process of planning and building the setup, data collection, analysis and troubleshooting, as well as the technical and human problems at each step. Approaches that were found to be helpful in managing the aforementioned problems are discussed, including an attention to detail during experimental work, as well as communicating in a forthcoming manner. Œe former allowed for clearer planning and the setting of quantifiable proximal goals; the latter helped in motivating discipline, and also helped in the understanding of research as an iterative learning process without a clear definition of success or failure.

Discrete maximal regularity of time-stepping schemes for fractional evolution equations.

PubMed

Jin, Bangti; Li, Buyang; Zhou, Zhi

2018-01-01

In this work, we establish the maximal [Formula: see text]-regularity for several time stepping schemes for a fractional evolution model, which involves a fractional derivative of order [Formula: see text], [Formula: see text], in time. These schemes include convolution quadratures generated by backward Euler method and second-order backward difference formula, the L1 scheme, explicit Euler method and a fractional variant of the Crank-Nicolson method. The main tools for the analysis include operator-valued Fourier multiplier theorem due to Weis (Math Ann 319:735-758, 2001. doi:10.1007/PL00004457) and its discrete analogue due to Blunck (Stud Math 146:157-176, 2001. doi:10.4064/sm146-2-3). These results generalize the corresponding results for parabolic problems.

A Meta-Analytic and Qualitative Review of Online versus Face-to-Face Problem-Based Learning

ERIC Educational Resources Information Center

Jurewitsch, Brian

2012-01-01

Problem-based learning (PBL) is an instructional strategy that is poised for widespread application in the current, growing, on-line digital learning environment. While enjoying a track record as a defensible strategy in face-to-face learning settings, the research evidence is not clear regarding PBL in on-line environments. A review of the…

Specific problems in visual cognition of dyslexic readers: Face discrimination deficits predict dyslexia over and above discrimination of scrambled faces and novel objects.

PubMed

Sigurdardottir, Heida Maria; Fridriksdottir, Liv Elisabet; Gudjonsdottir, Sigridur; Kristjánsson, Árni

2018-06-01

Evidence of interdependencies of face and word processing mechanisms suggest possible links between reading problems and abnormal face processing. In two experiments we assessed such high-level visual deficits in people with a history of reading problems. Experiment 1 showed that people who were worse at face matching had greater reading problems. In experiment 2, matched dyslexic and typical readers were tested, and difficulties with face matching were consistently found to predict dyslexia over and above both novel-object matching as well as matching noise patterns that shared low-level visual properties with faces. Furthermore, ADHD measures could not account for face matching problems. We speculate that reading difficulties in dyslexia are partially caused by specific deficits in high-level visual processing, in particular for visual object categories such as faces and words with which people have extensive experience. Copyright © 2018 Elsevier B.V. All rights reserved.

Prediction of the backflow and recovery regions in the backward facing step at various Reynolds numbers

NASA Technical Reports Server (NTRS)

Michelassi, V.; Durbin, P. A.; Mansour, N. N.

1996-01-01

A four-equation model of turbulence is applied to the numerical simulation of flows with massive separation induced by a sudden expansion. The model constants are a function of the flow parameters, and two different formulations for these functions are tested. The results are compared with experimental data for a high Reynolds-number case and with experimental and DNS data for a low Reynolds-number case. The computations prove that the recovery region downstream of the massive separation is properly modeled only for the high Re case. The problems in this case stem from the gradient diffusion hypothesis, which underestimates the turbulent diffusion.

Development of Turbulence Models for Shear Flows by a Double Expansion technique.

DTIC Science & Technology

1991-07-01

Let us introduce the dimensionless variables 7 = -; I -_o E ~ Ko where S = (2Sij Sij)112 and K0 is the initial turbulent kinetic energy. In...simulation of Bardina eta 1 4 for co/ SKo = 0.296 Figure 2 19 IlI H- L -1 y x Turbulent flow over a backward facing step Figure 3 20 BACKWARD-FACING STEP

Forward and backward motion of artificial helical swimmers in cylindrical channels

NASA Astrophysics Data System (ADS)

Acemoglu, Alperen; Temel, Fatma Zeynep; Yesilyurt, Serhat

2013-11-01

Motion of micro swimmers in confined geometries such as channels is important due to its relevance in in vivo medical applications such as minimally invasive surgery and drug delivery. Here, swimmers with diameters 0.8 mm and lengths 2 to 3 mm are produced with a 3D printer and cylindrical Nd2Fe14B magnets are placed inside the bodies. Rotating external magnetic field is used for the actuation of artificial swimmers. Different body and tail geometries are produced and experiments are conducted with a glycerol filled circular channel. Result demonstrate that decreasing channel diameter directly affects the forward motion of the swimmer due to the increasing drag. It is observed that step-out frequency, which defines maximum frequency at which the swimmer can establish a synchronous rotation with the external magnetic field, depends on the geometry of the swimmer and the channel diameter. There are significant differences between low and high frequency motion and forward and backward swimming. Longer tails enable higher forward velocities in high frequencies than backward ones, whereas forward and backward velocities are approximately the same at low frequencies. Furthermore backward motion is more stable than the forward one; at high frequencies, swimmers travel almost at the center of the channel for backward motion, and follow a helical trajectory near the wall during the forward motion. According to simulation results there is a flow which is induced by the rotation of the swimmer rotation that affects the swimmer's trajectory. We acknowledge the support from TUBITAK (Techonological & Research Council of Turkey) under the grant no: 111M376.

Modeling myosin VI stepping dynamics

NASA Astrophysics Data System (ADS)

Tehver, Riina

Myosin VI is a molecular motor that transports intracellular cargo as well as acts as an anchor. The motor has been measured to have unusually large step size variation and it has been reported to make both long forward and short inchworm-like forward steps, as well as step backwards. We have been developing a model that incorporates this diverse stepping behavior in a consistent framework. Our model allows us to predict the dynamics of the motor under different conditions and investigate the evolutionary advantages of the large step size variation.

Performance of the Seven-Step Procedure in Problem-Based Hospitality Management Education

ERIC Educational Resources Information Center

Zwaal, Wichard; Otting, Hans

2016-01-01

The study focuses on the seven-step procedure (SSP) in problem-based learning (PBL). The way students apply the seven-step procedure will help us understand how students work in a problem-based learning curriculum. So far, little is known about how students rate the performance and importance of the different steps, the amount of time they spend…

Full-orbit and backward Monte Carlo simulation of runaway electrons

NASA Astrophysics Data System (ADS)

Del-Castillo-Negrete, Diego

2017-10-01

High-energy relativistic runaway electrons (RE) can be produced during magnetic disruptions due to electric fields generated during the thermal and current quench of the plasma. Understanding this problem is key for the safe operation of ITER because, if not avoided or mitigated, RE can severely damage the plasma facing components. In this presentation we report on RE simulation efforts centered in two complementary approaches: (i) Full orbit (6-D phase space) relativistic numerical simulations in general (integrable or chaotic) 3-D magnetic and electric fields, including radiation damping and collisions, using the recently developed particle-based Kinetic Orbit Runaway electron Code (KORC) and (ii) Backward Monte-Carlo (MC) simulations based on a recently developed efficient backward stochastic differential equations (BSDE) solver. Following a description of the corresponding numerical methods, we present applications to: (i) RE synchrotron radiation (SR) emission using KORC and (ii) Computation of time-dependent runaway probability distributions, RE production rates, and expected slowing-down and runaway times using BSDE. We study the dependence of these statistical observables on the electric and magnetic field, and the ion effective charge. SR is a key energy dissipation mechanism in the high-energy regime, and it is also extensively used as an experimental diagnostic of RE. Using KORC we study full orbit effects on SR and discuss a recently developed SR synthetic diagnostic that incorporates the full angular dependence of SR, and the location and basic optics of the camera. It is shown that oversimplifying the angular dependence of SR and/or ignoring orbit effects can significantly modify the shape and overestimate the amplitude of the spectra. Applications to DIII-D RE experiments are discussed.

A dynamically adaptive multigrid algorithm for the incompressible Navier-Stokes equations: Validation and model problems

NASA Technical Reports Server (NTRS)

Thompson, C. P.; Leaf, G. K.; Vanrosendale, J.

1991-01-01

An algorithm is described for the solution of the laminar, incompressible Navier-Stokes equations. The basic algorithm is a multigrid based on a robust, box-based smoothing step. Its most important feature is the incorporation of automatic, dynamic mesh refinement. This algorithm supports generalized simple domains. The program is based on a standard staggered-grid formulation of the Navier-Stokes equations for robustness and efficiency. Special grid transfer operators were introduced at grid interfaces in the multigrid algorithm to ensure discrete mass conservation. Results are presented for three models: the driven-cavity, a backward-facing step, and a sudden expansion/contraction.

Experimental study of the active control applied to the flow past a backward facing ramp

NASA Astrophysics Data System (ADS)

Hlevca, Dan; Gilliéron, Patrick; Grasso, Francesco

2018-03-01

An experimental study of open loop active flow control on a backward facing ramp is presented. The ramp has finite span and a slant angle of 25°. Wind tunnel experiments were performed both for the uncontrolled and the controlled cases where time periodic forcing by pulsed jets is considered. The control system exploits an electro-magnetic valve system to generate pulsed jets with an operating frequency and duty cycle ranging, respectively, between 50 and 250 Hz and between 25 and 60%. A parametric study was carried out for three different freestream velocities and varying the frequency of the pulsed jets and the duty cycle. The control strategy relies on the injection of periodic perturbations before separation at the edge of the slant, considering various combinations of frequencies and duty cycles while keeping constant the blowing time for every Reynolds number, so as to excite the flow with the same jet structure over different actuation cycle extents. The receptivity of the flow to periodic forcing was assessed by characterizing mean and unsteady flow properties, turbulence statistics and flow topology. The study focused on the impact of control on reattachement and showed that the flow locks with excitation frequencies typical of initial Kelvin-Helmholtz instabilities. However, the flow was found to respond to any injected unsteady perturbation locking to the forcing frequencies and the extent of the region where locking occurs was found to be of the order of a few slant heights. A relaxation process was observed and the flow was found to relax past the slant trailing edge toward frequencies close to the natural ones.

PETOOL: MATLAB-based one-way and two-way split-step parabolic equation tool for radiowave propagation over variable terrain

NASA Astrophysics Data System (ADS)

Ozgun, Ozlem; Apaydin, Gökhan; Kuzuoglu, Mustafa; Sevgi, Levent

2011-12-01

Vista Classification: 10 Nature of problem: Simulation of radio-wave propagation over variable terrain on the Earth's surface, and through homogeneous and inhomogeneous atmosphere. Solution method: The program implements one-way and two-way Split-Step Parabolic Equation (SSPE) algorithm, with wide-angle propagator. The SSPE is, in general, an initial-value problem starting from a reference range (typically from an antenna), and marching out in range by obtaining the field along the vertical direction at each range step, through the use of step-by-step Fourier transformations. The two-way algorithm incorporates the backward-propagating waves into the standard one-way SSPE by utilizing an iterative forward-backward scheme for modeling multipath effects over a staircase-approximated terrain. Unusual features: This is the first software package implementing a recursive forward-backward SSPE algorithm to account for the multipath effects during radio-wave propagation, and enabling the user to easily analyze and visualize the results of the two-way propagation with GUI capabilities. Running time: Problem dependent. Typically, it is about 1.5 ms (for conducting ground) and 4 ms (for lossy ground) per range step for a vertical field profile of vector length 1500, on Intel Core 2 Duo 1.6 GHz with 2 GB RAM under Windows Vista.

Fish mouths as engineering structures for vortical cross-step filtration

NASA Astrophysics Data System (ADS)

Sanderson, S. Laurie; Roberts, Erin; Lineburg, Jillian; Brooks, Hannah

2016-03-01

Suspension-feeding fishes such as goldfish and whale sharks retain prey without clogging their oral filters, whereas clogging is a major expense in industrial crossflow filtration of beer, dairy foods and biotechnology products. Fishes' abilities to retain particles that are smaller than the pore size of the gill-raker filter, including extraction of particles despite large holes in the filter, also remain unexplained. Here we show that unexplored combinations of engineering structures (backward-facing steps forming d-type ribs on the porous surface of a cone) cause fluid dynamic phenomena distinct from current biological and industrial filter operations. This vortical cross-step filtration model prevents clogging and explains the transport of tiny concentrated particles to the oesophagus using a hydrodynamic tongue. Mass transfer caused by vortices along d-type ribs in crossflow is applicable to filter-feeding duck beak lamellae and whale baleen plates, as well as the fluid mechanics of ventilation at fish gill filaments.

Investigation of Content and Face Validity and Reliability of Sociocultural Attitude towards Appearance Questionnaire-3 (SATAQ-3) among Female Adolescents

PubMed Central

Mousazadeh, Somayeh; Rakhshan, Mahnaz; Mohammadi, Fateme

2017-01-01

Objective: This study aimed to determine the psychometric properties of sociocultural attitude towards appearance questionnaire in female adolescents. Method: This was a methodological study. The English version of the questionnaire was translated into Persian, using forward-backward method. Then the face validity, content validity and reliability were checked. To ensure face validity, the questionnaire was given to 25 female adolescents, a psychologist and three nurses, who were required to evaluate the items with respect to problems, ambiguity, relativity, proper terms and grammar, and understandability. For content validity, 15 experts in psychology and nursing, who met the inclusion criteria, were required. They were asked to assess the qualitative of content validity. To determine the quantitative content validity, content validity index and content validity ratio were calculated. At the end, internal consistency of the items was assessed, using Cronbach’s alpha method. Results: According to the expert judgments, content validity ratio was 0.81 and content validity index was 0.91. Besides, the reliability of the questionnaire was confirmed with Cronbach’s alpha = 0.91, and physical and developmental areas showed the highest reliability indices. Conclusion: The aforementioned questionnaire could be used in researches to assess female adolescents’ self-concept. This can be a stepping-stone towards identification of problems and improvement of adolescents’ body image. PMID:28496497

Linear system identification via backward-time observer models

NASA Technical Reports Server (NTRS)

Juang, Jer-Nan; Phan, Minh Q.

1992-01-01

Presented here is an algorithm to compute the Markov parameters of a backward-time observer for a backward-time model from experimental input and output data. The backward-time observer Markov parameters are decomposed to obtain the backward-time system Markov parameters (backward-time pulse response samples) for the backward-time system identification. The identified backward-time system Markov parameters are used in the Eigensystem Realization Algorithm to identify a backward-time state-space model, which can be easily converted to the usual forward-time representation. If one reverses time in the model to be identified, what were damped true system modes become modes with negative damping, growing as the reversed time increases. On the other hand, the noise modes in the identification still maintain the property that they are stable. The shift from positive damping to negative damping of the true system modes allows one to distinguish these modes from noise modes. Experimental results are given to illustrate when and to what extent this concept works.

Reactive Balance in Individuals With Chronic Stroke: Biomechanical Factors Related to Perturbation-Induced Backward Falling.

PubMed

Salot, Pooja; Patel, Prakruti; Bhatt, Tanvi

2016-03-01

An effective compensatory stepping response is the first line of defense for preventing a fall during sudden large external perturbations. The biomechanical factors that contribute to heightened fall risk in survivors of stroke, however, are not clearly understood. It is known that impending sensorimotor and balance deficits poststroke predispose these individuals to a risk of fall during sudden external perturbations. The purpose of this study was to examine the mechanism of fall risk in survivors of chronic stroke when exposed to sudden, slip-like forward perturbations in stance. This was a cross-sectional study. Fourteen individuals with stroke, 14 age-matched controls (AC group), and 14 young controls (YC group) were exposed to large-magnitude forward stance perturbations. Postural stability was computed as center of mass (COM) position (XCOM/BOS) and velocity (ẊCOM/BOS) relative to the base of support (BOS) at first step lift-off (LO) and touch-down (TD) and at second step TD. Limb support was quantified as vertical hip descent (Zhip) from baseline after perturbation onset. All participants showed a backward balance loss, with 71% of the stroke group experiencing a fall compared with no falls in the control groups (AC and YC groups). At first step LO, no between-group differences in XCOM/BOS and ẊCOM/BOS were noted. At first step TD, however, the stroke group had a significantly posterior XCOM/BOS and backward ẊCOM/BOS compared with the control groups. At second step TD, individuals with stroke were still more unstable (more posterior XCOM/BOS and backward ẊCOM/BOS) compared with the AC group. Individuals with stroke also showed greater peak Zhip compared with the control groups. Furthermore, the stroke group took a larger number of steps with shorter step length and delayed step initiation compared with the control groups. Although the study highlights the reactive balance deficits increasing fall risk in survivors of stroke compared with healthy

Behavioural signatures of backward planning in animals.

PubMed

Afsardeir, Arsham; Keramati, Mehdi

2018-03-01

Goal-directed planning in behavioural and neural sciences is theorized to involve a prospective mental simulation that, starting from the animal's current state in the environment, expands a decision tree in a forward fashion. Backward planning in the artificial intelligence literature, however, suggests that agents expand a mental tree in a backward fashion starting from a certain goal state they have in mind. Here, we show that several behavioural patterns observed in animals and humans, namely outcome-specific Pavlovian-to-instrumental transfer and differential outcome effect, can be parsimoniously explained by backward planning. Our basic assumption is that the presentation of a cue that has been associated with a certain outcome triggers backward planning from that outcome state. On the basis of evidence pointing to forward and backward planning models, we discuss the possibility of brain using a bidirectional planning mechanism where forward and backward trees are expanded in parallel to achieve higher efficiency. © 2018 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Two-step superresolution approach for surveillance face image through radial basis function-partial least squares regression and locality-induced sparse representation

NASA Astrophysics Data System (ADS)

Jiang, Junjun; Hu, Ruimin; Han, Zhen; Wang, Zhongyuan; Chen, Jun

2013-10-01

Face superresolution (SR), or face hallucination, refers to the technique of generating a high-resolution (HR) face image from a low-resolution (LR) one with the help of a set of training examples. It aims at transcending the limitations of electronic imaging systems. Applications of face SR include video surveillance, in which the individual of interest is often far from cameras. A two-step method is proposed to infer a high-quality and HR face image from a low-quality and LR observation. First, we establish the nonlinear relationship between LR face images and HR ones, according to radial basis function and partial least squares (RBF-PLS) regression, to transform the LR face into the global face space. Then, a locality-induced sparse representation (LiSR) approach is presented to enhance the local facial details once all the global faces for each LR training face are constructed. A comparison of some state-of-the-art SR methods shows the superiority of the proposed two-step approach, RBF-PLS global face regression followed by LiSR-based local patch reconstruction. Experiments also demonstrate the effectiveness under both simulation conditions and some real conditions.

Amygdala hypoactivity to fearful faces in boys with conduct problems and callous-unemotional traits.

PubMed

Jones, Alice P; Laurens, Kristin R; Herba, Catherine M; Barker, Gareth J; Viding, Essi

2009-01-01

Although early-onset conduct problems predict both psychiatric and health problems in adult life, little research has been done to index neural correlates of conduct problems. Emerging research suggests that a subgroup of children with conduct problems and elevated levels of callous-unemotional traits may be genetically vulnerable to manifesting disturbances in neural reactivity to emotional stimuli indexing distress. Using functional MRI, the authors evaluated differences in neural response to emotional stimuli between boys with conduct problems and elevated levels of callous-unemotional traits and comparison boys. Seventeen boys with conduct problems and elevated levels of callous-unemotional traits and 13 comparison boys of equivalent age (mean=11 years) and IQ (mean=100) viewed blocked presentations of fearful and neutral faces. For each face, participants distinguished the sex of the face via manual response. Relative to the comparison group, boys with conduct problems and elevated levels of callous-unemotional traits manifested lesser right amygdala activity to fearful faces. This finding is in line with data from studies of adults with antisocial behavior and callous-unemotional traits (i.e., psychopaths), as well as from a recent study of adolescents with callous-unemotional traits, and suggests that the neural substrates of emotional impairment associated with callous-unemotional antisocial behavior are already present in childhood.

Numerical solution of second order ODE directly by two point block backward differentiation formula

NASA Astrophysics Data System (ADS)

Zainuddin, Nooraini; Ibrahim, Zarina Bibi; Othman, Khairil Iskandar; Suleiman, Mohamed; Jamaludin, Noraini

2015-12-01

Direct Two Point Block Backward Differentiation Formula, (BBDF2) for solving second order ordinary differential equations (ODEs) will be presented throughout this paper. The method is derived by differentiating the interpolating polynomial using three back values. In BBDF2, two approximate solutions are produced simultaneously at each step of integration. The method derived is implemented by using fixed step size and the numerical results that follow demonstrate the advantage of the direct method as compared to the reduction method.

Solar array stepping problems in satellites and solutions

NASA Astrophysics Data System (ADS)

Maharana, P. K.; Goel, P. S.

1992-01-01

The dynamics problems arising due to stepping motion of the solar arrays of spacecraft are studied. To overcome these problems, design improvements in the drive logic based on the phase plane analysis are suggested. The improved designs are applied to the Solar Array Drive Assembly (SADA) of IRS-1B and INSAT-2A satellites. In addition, an alternate torquing strategy for very successful slewing of the arrays, and with minimum excitation of flexible modes, is proposed.

Design of far-infrared acousto-optic tunable filter based on backward collinear interaction.

PubMed

Voloshinov, Vitaly B; Porokhovnichenko, Dmitriy L; Dyakonov, Evgeniy A

2018-04-10

The paper proposes a design of acousto-optic cell applying backward collinear interaction and acoustic mode transformation in a KRS-5 crystal. This cell may serve as an acousto-optic tunable filter for far-infrared spectral range and is able to operate both with collimated optical beams and with divergent beams forming images. The problem of acoustic mode transformation by wave reflection from the crystal facet away from symmetry planes has been solved. Polarization properties of the backward collinear interaction in optically isotropic media are discussed. Copyright © 2018 Elsevier B.V. All rights reserved.

Backward Channel Protection Based on Randomized Tree-Walking Algorithm and Its Analysis for Securing RFID Tag Information and Privacy

NASA Astrophysics Data System (ADS)

Choi, Wonjoon; Yoon, Myungchul; Roh, Byeong-Hee

Eavesdropping on backward channels in RFID environments may cause severe privacy problems because it means the exposure of personal information related to tags that each person has. However, most existing RFID tag security schemes are focused on the forward channel protections. In this paper, we propose a simple but effective method to solve the backward channel eavesdropping problem based on Randomized-tree walking algorithm for securing tag ID information and privacy in RFID-based applications. In order to show the efficiency of the proposed scheme, we derive two performance models for the cases when CRC is used and not used. It is shown that the proposed method can lower the probability of eavesdropping on backward channels near to ‘0.’

Stepped care versus face-to-face cognitive behavior therapy for panic disorder and social anxiety disorder: Predictors and moderators of outcome.

PubMed

Haug, Thomas; Nordgreen, Tine; Öst, Lars-Göran; Kvale, Gerd; Tangen, Tone; Andersson, Gerhard; Carlbring, Per; Heiervang, Einar R; Havik, Odd E

2015-08-01

To investigate predictors and moderators of treatment outcome by comparing immediate face-to-face cognitive behavioral therapy (FtF-CBT) to a Stepped Care treatment model comprising three steps: Psychoeducation, Internet-delivered CBT, and FtF-CBT for panic disorder (PD) and social anxiety disorder (SAD). Patients (N = 173) were recruited from nine public mental health out-patient clinics and randomized to immediate FtF-CBT or Stepped Care treatment. Characteristics related to social functioning, impairment from the anxiety disorder, and comorbidity was investigated as predictors and moderators by treatment format and diagnosis in multiple regression analyses. Lower social functioning, higher impairment from the anxiety disorder, and a comorbid cluster C personality disorder were associated with significantly less improvement, particularly among patients with PD. Furthermore, having a comorbid anxiety disorder was associated with a better treatment outcome among patients with PD but not patients with SAD. Patients with a comorbid depression had similar outcomes from the different treatments, but patients without comorbid depression had better outcomes from immediate FtF-CBT compared to guided self-help. In general, the same patient characteristics appear to be associated with the treatment outcome for CBT provided in low- and high-intensity formats when treated in public mental health care clinics. The findings suggest that patients with lower social functioning and higher impairment from their anxiety disorder benefit less from these treatments and may require more adapted and extensive treatment. CLINICALTRIALS.GOV: Identifier: NCT00619138. Copyright © 2015 Elsevier Ltd. All rights reserved.

Students' Errors in Solving the Permutation and Combination Problems Based on Problem Solving Steps of Polya

ERIC Educational Resources Information Center

Sukoriyanto; Nusantara, Toto; Subanji; Chandra, Tjang Daniel

2016-01-01

This article was written based on the results of a study evaluating students' errors in problem solving of permutation and combination in terms of problem solving steps according to Polya. Twenty-five students were asked to do four problems related to permutation and combination. The research results showed that the students still did a mistake in…

Influence of gait speed on stability: recovery from anterior slips and compensatory stepping.

PubMed

Bhatt, T; Wening, J D; Pai, Y-C

2005-02-01

Falls precipitated by slipping are a major health concern, with the majority of all slip-related falls occurring during gait. Recent evidence shows that a faster and/or more anteriorly positioned center of mass (COM) is more stable against backward balance loss, and that compensatory stepping is the key to recovering stability upon balance loss. The purposes of this paper were to determine whether walking speed affected gait stability for backward balance loss at slip onset and touchdown of compensatory stepping, and whether compensatory stepping response resembled the regular gait pattern. Forty-seven young subjects were slipped unexpectedly either at a self-selected fast, natural or slow speed. Speed-related differences in stability at slip onset and touchdown of the subsequent compensatory step were analyzed using the COM position-velocity state. The results indicate that gait speed highly correlated with stability against backward balance loss at slip onset. The low COM velocity of the slow group was not sufficiently compensated for by a more anteriorly positioned COM associated with a shorter step length at slip onset. At touchdown of the compensatory step, the speed-related differences in stability diminished, due to the continued advantage of anterior COM positioning from a short compensatory step retained by the slow group, coupled with an increase in COM velocity. Compensatory step length and relative COM position altered as a function of gait speed, indicating the motor program for gait regulation may play a role in modulating the compensatory step.

Control problems in armored face conveyors for longwall mines

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

Broadfoot, A.R.; Betz, R.E.

1998-03-01

This paper is a tutorial discussion of the current difficulties being experienced with the performance of armored face conveyor (AFC) drive systems, as used in longwall mining. It presents the traditional approaches to the design of the drive system and highlights the inadequacies. The final part of the paper presents a possible solution approach using variable-speed drive systems, emphasizing the advantages of this approach. The paper is significant, in that it discusses, in one document, a number of problems related to the operation of longwall AFC`s. Furthermore, it presents a solution path for these problems. The details of the controlmore » strategies to solve the problems highlighted are left to a companion paper.« less

Masking with faces in central visual field under a variety of temporal schedules.

PubMed

Daar, Marwan; Wilson, Hugh R

2015-11-01

With a few exceptions, previous studies have explored masking using either a backward mask or a common onset trailing mask, but not both. In a series of experiments, we demonstrate the use of faces in central visual field as a viable method to study the relationship between these two types of mask schedule. We tested observers in a two alternative forced choice face identification task, where both target and mask comprised synthetic faces, and show that a simple model can successfully predict masking across a variety of masking schedules ranging from a backward mask to a common onset trailing mask and a number of intermediate variations. Our data are well accounted for by a window of sensitivity to mask interference that is centered at around 100 ms. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of subliminal backward-recorded messages on attitudes.

PubMed

Swart, L C; Morgan, C L

1992-12-01

This study was designed to measure the effects of subliminal backward messages on attitudes. It was hypothesized that subliminal backward-recorded messages would influence the attitudes of listeners. Three subliminal backward-recorded messages from a popular song were used. 82 undergraduates were randomly assigned to one of four conditions: a three-message group heard a tape containing the backward messages recorded three times in succession, a six-message group heard a tape with the same backward messages recorded six times in succession, two control groups heard nonbackward recorded music. No statistically significant differences were found between the groups on a posttape attitude questionnaire. The results are discussed in terms of unconscious processing and the tricomponent theory of attitudes and attitude change.

On the supersonic three-dimensional flow over an axisymmetric body with a forward-facing annular step

NASA Astrophysics Data System (ADS)

Simonenko, Mikhail; Zubkov, Alexander; Kuzmin, Alexander

2018-05-01

The 3D turbulent supersonic flow over a body of revolution at various angles of attack α is studied numerically and experimentally. The body surface incorporates a forward-facing step near its midpart and a nose cone. Experiments were conducted in a wind tunnel of the Research Institute of Mechanics, Moscow State University, at the Mach number of 3 for various lengths L of the distance between the step and nose cone. Numerical simulations were performed with a finite-volume solver ANSYS CFX-15. The study reveals bands of α and L in which the pressure on the leeward side of step abruptly increases and exceeds the pressure on the windward side.

Towards efficient backward-in-time adjoint computations using data compression techniques

DOE PAGES

Cyr, E. C.; Shadid, J. N.; Wildey, T.

2014-12-16

In the context of a posteriori error estimation for nonlinear time-dependent partial differential equations, the state-of-the-practice is to use adjoint approaches which require the solution of a backward-in-time problem defined by a linearization of the forward problem. One of the major obstacles in the practical application of these approaches, we found, is the need to store, or recompute, the forward solution to define the adjoint problem and to evaluate the error representation. Our study considers the use of data compression techniques to approximate forward solutions employed in the backward-in-time integration. The development derives an error representation that accounts for themore » difference between the standard-approach and the compressed approximation of the forward solution. This representation is algorithmically similar to the standard representation and only requires the computation of the quantity of interest for the forward solution and the data-compressed reconstructed solution (i.e. scalar quantities that can be evaluated as the forward problem is integrated). This approach is then compared with existing techniques, such as checkpointing and time-averaged adjoints. Lastly, we provide numerical results indicating the potential efficiency of our approach on a transient diffusion–reaction equation and on the Navier–Stokes equations. These results demonstrate memory compression ratios up to 450×450× while maintaining reasonable accuracy in the error-estimates.« less

Characterizing the Fundamental Intellectual Steps Required in the Solution of Conceptual Problems

NASA Astrophysics Data System (ADS)

Stewart, John

2010-02-01

At some level, the performance of a science class must depend on what is taught, the information content of the materials and assignments of the course. The introductory calculus-based electricity and magnetism class at the University of Arkansas is examined using a catalog of the basic reasoning steps involved in the solution of problems assigned in the class. This catalog was developed by sampling popular physics textbooks for conceptual problems. The solution to each conceptual problem was decomposed into its fundamental reasoning steps. These fundamental steps are, then, used to quantify the distribution of conceptual content within the course. Using this characterization technique, an exceptionally detailed picture of the information flow and structure of the class can be produced. The intellectual structure of published conceptual inventories is compared with the information presented in the class and the dependence of conceptual performance on the details of coverage extracted. )

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.

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.

Combination ring cavity and backward Raman waveguide amplifier

DOEpatents

Kurnit, Norman A.

1983-01-01

A combination regenerative ring and backward Raman waveguide amplifier and a combination regenerative ring oscillator and backward Raman waveguide amplifier which produce Raman amplification, pulse compression, and efficient energy extraction from the CO.sub.2 laser pump signal for conversion into a Stokes radiation signal. The ring cavity configuration allows the CO.sub.2 laser pump signal and Stokes signal to copropagate through the Raman waveguide amplifier. The backward Raman waveguide amplifier configuration extracts a major portion of the remaining energy from the CO.sub.2 laser pump signal for conversion to Stokes radiation. Additionally, the backward Raman amplifier configuration produces a Stokes radiation signal which has a high intensity and a short duration. Adjustment of the position of overlap of the Stokes signal and the CO.sub.2 laser pump signal in the backward Raman waveguide amplifiers alters the amount of pulse compression which can be achieved.

Regional source identification using Lagrangian stochastic particle dispersion and HYSPLIT backward-trajectory models.

PubMed

Koracin, Darko; Vellore, Ramesh; Lowenthal, Douglas H; Watson, John G; Koracin, Julide; McCord, Travis; DuBois, David W; Chen, L W Antony; Kumar, Naresh; Knipping, Eladio M; Wheeler, Neil J M; Craig, Kenneth; Reid, Stephen

2011-06-01

alleviate problems due to selection of a backward-trajectory starting level within a large complex set of 3-dimensional winds, turbulence, and dispersion, results were averaged from all heights, which yielded uniform improvement against all individual cases.

Student Opinions about the Seven-Step Procedure in Problem-Based Hospitality Management Education

ERIC Educational Resources Information Center

Zwaal, Wichard; Otting, Hans

2014-01-01

This study investigates how hospitality management students appreciate the role and application of the seven-step procedure in problem-based learning. A survey was developed containing sections about personal characteristics, recall of the seven steps, overall report marks, and 30 statements about the seven-step procedure. The survey was…

In-shoe plantar pressure distribution and lower extremity muscle activity patterns of backward compared to forward running on a treadmill.

PubMed

Sterzing, Thorsten; Frommhold, Clivia; Rosenbaum, Dieter

2016-05-01

Backward locomotion in humans occurs during leisure, rehabilitation, and competitive sports. Little is known about its general biomechanical characteristics and how it affects lower extremity loading as well as muscle coordination. Thus, the purpose of this research was to analyze in-shoe plantar pressure patterns and lower extremity muscle activity patterns for backward compared to forward running. On a treadmill, nineteen runners performed forward running at their individually preferred speed, followed by backward running at 70% of their self-selected forward speed. In-shoe plantar pressures of nine foot regions and muscular activity of nine lower extremity muscles were recorded simultaneously over a one-minute interval. Backward and forward running variables were averaged over the accumulated steps and compared with Wilcoxon-signed rank tests (p<.05). For backward compared to forward running, in-shoe plantar pressure distribution showed a load increase under metatarsal heads I and II, as well as under the medial midfoot. This was indicated by higher maximum forces and peak pressures, and by longer contact times. Muscle activity showed significantly higher mean amplitudes during backward running in the semitendinosus, rectus femoris, vastus lateralis, and gluteus medius during stance, and in the rectus femoris during swing phase, while significantly lower mean amplitudes were observed in the tibialis anterior during swing phase. Observations indicate plantar foot loading and muscle activity characteristics that are specific for the running direction. Thus, backward running may be used on purpose for certain rehabilitation tasks, aiming to strengthen respective lower extremity muscles. Furthermore, the findings are relevant for sport specific backward locomotion training. Finally, results provide an initial baseline for innovative athletic footwear development aiming to increase comfort and performance during backward running. Copyright © 2016 Elsevier B.V. All

The numerical modeling of water/FMWCNT nanofluid flow and heat transfer in a backward-facing contracting channel

NASA Astrophysics Data System (ADS)

Alrashed, Abdullah A. A. A.; Akbari, Omid Ali; Heydari, Ali; Toghraie, Davood; Zarringhalam, Majid; Shabani, Gholamreza Ahmadi Sheikh; Seifi, Ali Reza; Goodarzi, Marjan

2018-05-01

In recent years, the study of rheological behavior and heat transfer of nanofluids in the industrial equipment has become widespread among the researchers and their results have led to great advancements in this field. In present study, the laminar flow and heat transfer of water/functional multi-walled carbon nanotube nanofluid have been numerically investigated in weight percentages of 0.00, 0.12 and 0.25 and Reynolds numbers of 1-150 by using finite volume method (FVM). The analyzed geometry is a two-dimensional backward-facing contracting channel and the effects of various weight percentages and Reynolds numbers have been studied in the supposed geometry. The results have been interpreted as the figures of Nusselt number, friction coefficient, pressure drop, velocity contours and static temperature. The results of this research indicate that, the enhancement of Reynolds number or weight percentage of nanoparticles causes the reduction of surface temperature and the enhancement of heat transfer coefficient. By increasing Reynolds number, the axial velocity enhances, causing the enhancement of momentum. By increasing fluid momentum at the beginning of channel, especially in areas close to the upper wall, the axial velocity reduces and the possibility of vortex generation increases. The mentioned behavior causes a great enhancement in velocity gradients and pressure drop at the inlet of channel. Also, in these areas, Nusselt number and local friction coefficient figures have a relative decline, which is due to the sudden reduction of velocity. In general, by increasing the mass fraction of solid nanoparticles, the average Nusselt number increases and in Reynolds number of 150, the enhancement of pumping power and pressure drop does not cause any significant changes. This behavior is an important advantage of choosing nanofluid which causes the enhancement of thermal efficiency.

New and Emerging Problems in School Adminstration.

ERIC Educational Resources Information Center

TenHaken, Richard E.

This paper examines a number of problems facing school board members and educational administrators today and suggests some possible approaches to addressing those problems effectively. In considering each problem area, the author emphasizes its impact on the activities and responsibilities of school officials and discusses concrete steps they can…

Expression-invariant representations of faces.

PubMed

Bronstein, Alexander M; Bronstein, Michael M; Kimmel, Ron

2007-01-01

Addressed here is the problem of constructing and analyzing expression-invariant representations of human faces. We demonstrate and justify experimentally a simple geometric model that allows to describe facial expressions as isometric deformations of the facial surface. The main step in the construction of expression-invariant representation of a face involves embedding of the facial intrinsic geometric structure into some low-dimensional space. We study the influence of the embedding space geometry and dimensionality choice on the representation accuracy and argue that compared to its Euclidean counterpart, spherical embedding leads to notably smaller metric distortions. We experimentally support our claim showing that a smaller embedding error leads to better recognition.

Dynamic Behavior of Spiral-Groove and Rayleigh-Step Self-Acting Face Seals

NASA Technical Reports Server (NTRS)

Dirusso, Eliseo

1984-01-01

Tests were performed to determine the dynamic behavior and establish baseline dynamic data for five self-acting face seals employing Rayleigh-step lift-pads and inward pumping as well as outward-pumping spiral grooves for the lift-generating mechanism. The primary parameters measured in the tests were film thickness, seal seat axial motion, and seal frictional torque. The data show the dynamic response of the film thickness to the motion of the seal seat. The inward-pumping spiral-groove seals exhibited a high-amplitude film thickness vibratory mode with a frequency of four times the shaft speed. This mode was not observed in the other seals tested. The tests also revealed that high film thickness vibration amplitude produces considerably higher average film thickness than do low amplitude film thickness vibrations. 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 17000 rpm. Seal tangential speed range was 34.5 to 83.7 m/sec (113 to 274 ft/sec).

Backward and forward plasmons in symmetric structures

NASA Astrophysics Data System (ADS)

Davidovich, Mikhael V.

2018-04-01

The electric and magnetic surface plasmons in symmetric structures of metallic and dielectric layers are considered. The existence of backward and forward waves and the slow and fast plasmon-polaritons are obtained. It is shown that the anomalous negative dispersion in the structures with dissipation does not necessarily indicate the backward surface plasmons.

Problems faced and coping strategies used by adolescents with mentally ill parents in Delhi.

PubMed

George, Shoba; Shaiju, Bindu; Sharma, Veena

2012-01-01

The present study was conducted to assess the problems faced by adolescents whose parents suffer from major mental illness at selected mental health institutes of Delhi. The objectives also included assessment of the coping strategies of the adolescents in dealing with these problems. The Stuart Stress Adaptation Model of Psychiatric Nursing Care was used as the conceptual framework. A descriptive survey approach with cross-sectional design was used in the study. A structured interview schedule was prepared. Purposive non-probability sampling technique was employed to interview 50 adolescents whose parents suffer from major mental illness. Data gathered was analysed and interpreted using both descriptive and inferential statistics. The study showed that majority of the adolescents had moderate problems as a result of their parent's mental illness. Area-wise analysis of the problems revealed that the highest problems faced were in family relationship and support and majority of the adolescents used maladaptive coping strategies. A set of guidelines on effective coping strategies was disseminated to these adolescents.

Coordination of rapid stepping with arm pointing: anticipatory changes and step adaptation.

PubMed

Yiou, Eric; Schneider, Cyril; Roussel, Didier

2007-06-01

The present study explored whether rapid stepping is influenced by the coordination of an arm pointing task. Nine participants were instructed to (a) point the index finger of the dominant arm towards a target from the standing posture, (b) initiate a rapid forward step with the contralateral leg, and (c) synchronize stepping and pointing (combined task). Force plate and ankle muscle electromyography (EMG) recordings were contrasted between (b) and (c). In the combined task, the arm acceleration trace most often peaked around foot-off, coinciding with a 15% increase in the forward acceleration of the center of gravity (CoG). Backward displacement of the center of foot pressure at foot-off, duration of anticipatory postural adjustments (APAs) and ankle muscle EMG activity remained unchanged. In contrast, durations of swing phase and whole step were reduced and step length was smaller in the combined task. A reduction in the swing phase was correlated with an increased CoG forward acceleration at foot-off. Changes in the biomechanics of step initiation during the combined task might be ascribed to the postural dynamics elicited by arm pointing, and not to a modulation of the step APAs programming.

Lower extremity joint kinetics and energetics during backward running.

PubMed

DeVita, P; Stribling, J

1991-05-01

The purpose of this study was to measure lower extremity joint moments of force and joint muscle powers used to perform backward running. Ten trials of high speed (100 Hz) sagittal plane film records and ground reaction force data (1000 Hz) describing backward running were obtained from each of five male runners. Fifteen trials of forward running data were obtained from one of these subjects. Inverse dynamics were performed on these data to obtain the joint moments and powers, which were normalized to body mass to make between-subject comparisons. Backward running hip moment and power patterns were similar in magnitude and opposite in direction to forward running curves and produced more positive work in stance. Functional roles of knee and ankle muscles were interchanged between backward and forward running. Knee extensors were the primary source of propulsion in backward running owing to greater moment and power output (peak moment = 3.60 N.m.kg-1; peak power = 12.40 W.kg-1) compared with the ankle (peak moment = 1.92 N.m.kg-1; peak power = 7.05 W.kg-1). The ankle plantarflexors were the primary shock absorbers, producing the greatest negative power (peak = -6.77 W.kg-1) during early stance. Forward running had greater ankle moment and power output for propulsion and greater knee negative power for impact attenuation. The large knee moment in backward running supported previous findings indicating that backward running training leads to increased knee extensor torque capabilities.

On the Unsteady Shock Wave Interaction with a Backward-Facing Step: Viscous Analysis

NASA Astrophysics Data System (ADS)

Mendoza, N.; Bowersox, R. D. W.

Unsteady shock propagation through ducts with varying cross-sectional area occurs in many engineering applications, such as explosions in underground tunnels, blast shelter design, engine exhaust systems, and high-speed propulsion systems. These complex, transient flows are rich in fundamental fluid-dynamic phenomena and are excellent testbeds for improving our understanding of unsteady fluid dynamics

Problem Analysis: The First Step in Prevention Planning. A Prevention 101 Series Publication

ERIC Educational Resources Information Center

DeJong, William

2009-01-01

Student alcohol and other drug abuse and violence (AODV) still reign as the most serious social problems faced by U.S. institutions of higher education. To tackle these problems, campus administrators--working in conjunction with partners from the surrounding community--need to put in place an integrated set of strategies that address the mix of…

Experimental study of combustion in a turbulent free shear layer formed at a rearward facing step

NASA Technical Reports Server (NTRS)

Pitz, R. W.; Daily, J. 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 are determined by LDV for both reacting (equivalence ratio 0.57) and nonreacting flows (Reynolds number 15,000-37,000 based on step height). The effect of combustion is to shift the layer toward the recirculation zone and reduce the flame spread. For reacting flow, the growth rate is unchanged except very near the step. The probability density function of the velocity is bimodial near the origin of the reacting layer and single-peaked but often skewed elsewhere. Large-scale structures dominate the reacting shear layer. Measurements of their passing frequency from LDV are consistent with high-speed Schlieren movies of the reacting layer and indicate that the coalescence rate of the eddies in the shear layer is reduced by combustion.

Finessing filter scarcity problem in face recognition via multi-fold filter convolution

NASA Astrophysics Data System (ADS)

Low, Cheng-Yaw; Teoh, Andrew Beng-Jin

2017-06-01

The deep convolutional neural networks for face recognition, from DeepFace to the recent FaceNet, demand a sufficiently large volume of filters for feature extraction, in addition to being deep. The shallow filter-bank approaches, e.g., principal component analysis network (PCANet), binarized statistical image features (BSIF), and other analogous variants, endure the filter scarcity problem that not all PCA and ICA filters available are discriminative to abstract noise-free features. This paper extends our previous work on multi-fold filter convolution (ℳ-FFC), where the pre-learned PCA and ICA filter sets are exponentially diversified by ℳ folds to instantiate PCA, ICA, and PCA-ICA offspring. The experimental results unveil that the 2-FFC operation solves the filter scarcity state. The 2-FFC descriptors are also evidenced to be superior to that of PCANet, BSIF, and other face descriptors, in terms of rank-1 identification rate (%).

3D Face Modeling Using the Multi-Deformable Method

PubMed Central

Hwang, Jinkyu; Yu, Sunjin; Kim, Joongrock; Lee, Sangyoun

2012-01-01

In this paper, we focus on the problem of the accuracy performance of 3D face modeling techniques using corresponding features in multiple views, which is quite sensitive to feature extraction errors. To solve the problem, we adopt a statistical model-based 3D face modeling approach in a mirror system consisting of two mirrors and a camera. The overall procedure of our 3D facial modeling method has two primary steps: 3D facial shape estimation using a multiple 3D face deformable model and texture mapping using seamless cloning that is a type of gradient-domain blending. To evaluate our method's performance, we generate 3D faces of 30 individuals and then carry out two tests: accuracy test and robustness test. Our method shows not only highly accurate 3D face shape results when compared with the ground truth, but also robustness to feature extraction errors. Moreover, 3D face rendering results intuitively show that our method is more robust to feature extraction errors than other 3D face modeling methods. An additional contribution of our method is that a wide range of face textures can be acquired by the mirror system. By using this texture map, we generate realistic 3D face for individuals at the end of the paper. PMID:23201976

Control of low-speed turbulent separated flow over a backward-facing ramp. Ph.D. Thesis - Old Dominion Univ.

NASA Technical Reports Server (NTRS)

Lin, John C.

1992-01-01

The relative performance and flow phenomena associated with several devices for controlling turbulent separated flow were investigated at low speeds. Relative performance of the devices was examined for flow over a curved, backward-facing ramp in a wind tunnel, and the flow phenomena were examined in a water tunnel using dye-flow visualization. Surface static pressure measurements and oil-flow visualization results from the wind tunnel tests indicated that transverse grooves, longitudinal grooves, submerged vortex generators, vortex generator jets (VGJ's), Viets' fluidic flappers, elongated arches at positive angle of attack, and large-eddy breakup devices (LEBU's) at positive angle of attack placed near the baseline separation location reduce flow separation and increase pressure recovery. Spanwise cylinders reduce flow separation but decrease pressure recovery downstream. Riblets, passive porous surfaces, swept grooves, Helmholtz resonators, and arches and LEBU's with angle of attack less than or = 0 degrees had no significant effect in reducing the extent of the separation region. Wall-cooling computations indicated that separation delay on a partially-cooled ramp is nearly the same as on a fully-cooled ramp, while minimizing the frictional drag increase associated with the wall cooling process. Dry-flow visualization tests in the water tunnel indicated that wishbone vortex generators in the forward orientation shed horseshoe vortices; wishbone vortex generators oriented in the reverse direction and doublet vortex generators shed streamwise counterrotating vortices; a spanewise cylinder located near the wall and LEBU's at angle of attack = -10 degrees produced eddies or transverse vortices which rotated with the same sign as the mean vorticity in a turbulent boundary layer; and the most effective VGJ's produced streamwise co-rotating vortices. Comparative wind-tunnel test results indicated that transferring momentum from the outer region of a turbulent boundary

Backward Raman amplification in the long-wavelength infrared

NASA Astrophysics Data System (ADS)

Johnson, L. A.; Gordon, D. F.; Palastro, J. P.; Hafizi, B.

2017-03-01

The wealth of work in backward Raman amplification in plasma has focused on the extreme intensity limit; however, backward Raman amplification may also provide an effective and practical mechanism for generating intense, broad bandwidth, long-wavelength infrared radiation (LWIR). An electromagnetic simulation coupled with a relativistic cold fluid plasma model is used to demonstrate the generation of picosecond pulses at a wavelength of 10 μm with terawatt powers through backward Raman amplification. The effects of collisional damping, Landau damping, pump depletion, and wave breaking are examined, as well as the resulting design considerations for an LWIR Raman amplifier.

Forward and backward uncertainty propagation: an oxidation ditch modelling example.

PubMed

Abusam, A; Keesman, K J; van Straten, G

2003-01-01

In the field of water technology, forward uncertainty propagation is frequently used, whereas backward uncertainty propagation is rarely used. In forward uncertainty analysis, one moves from a given (or assumed) parameter subspace towards the corresponding distribution of the output or objective function. However, in the backward uncertainty propagation, one moves in the reverse direction, from the distribution function towards the parameter subspace. Backward uncertainty propagation, which is a generalisation of parameter estimation error analysis, gives information essential for designing experimental or monitoring programmes, and for tighter bounding of parameter uncertainty intervals. The procedure of carrying out backward uncertainty propagation is illustrated in this technical note by working example for an oxidation ditch wastewater treatment plant. Results obtained have demonstrated that essential information can be achieved by carrying out backward uncertainty propagation analysis.

Two-step rating-based 'double-faced applicability' test for sensory analysis of spread products as an alternative to descriptive analysis with trained panel.

PubMed

Kim, In-Ah; den-Hollander, Elyn; Lee, Hye-Seong

2018-03-01

Descriptive analysis with a trained sensory panel has thus far been the most well defined methodology to characterize various products. However, in practical terms, intensive training in descriptive analysis has been recognized as a serious defect. To overcome this limitation, various novel rapid sensory profiling methodologies have been suggested in the literature. Among these, attribute-based methodologies such as check-all-that-apply (CATA) questions showed results comparable to those of conventional sensory descriptive analysis. Kim, Hopkinson, van Hout, and Lee (2017a, 2017b) have proposed a novel attribute-based methodology termed the two-step rating-based 'double-faced applicability' test with a novel output measure of applicability magnitude (d' A ) for measuring consumers' product usage experience throughout various product usage stages. In this paper, the potential of the two-step rating-based 'double-faced applicability' test with d' A was investigated as an alternative to conventional sensory descriptive analysis in terms of sensory characterization and product discrimination. Twelve commercial spread products were evaluated using both conventional sensory descriptive analysis with a trained sensory panel and two-step rating-based 'double-faced applicability' test with an untrained sensory panel. The results demonstrated that the 'double-faced applicability' test can be used to provide a direct measure of the applicability magnitude of sensory attributes of the samples tested in terms of d' A for sensory characterization of individual samples and multiple sample comparisons. This suggests that when the appropriate list of attributes to be used in the questionnaire is already available, the two-step rating-based 'double-faced applicability' test with d' A can be used as a more efficient alternative to conventional descriptive analysis, without requiring any intensive training process. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Great LEEP Backward?

ERIC Educational Resources Information Center

Allinson, Richard S.

1980-01-01

The federal government's Law Enforcement Education Program (LEEP) faces a precarious future. Three problems include: a bureaucratic tug-of-war between the Justice Department and the new Department of Education, the loss of appropriations, and a debate about the values of programs, and the types of courses and degrees offered. (MLW)

Prediction of 3D chip formation in the facing cutting with lathe machine using FEM

NASA Astrophysics Data System (ADS)

Prasetyo, Yudhi; Tauviqirrahman, Mohamad; Rusnaldy

2016-04-01

This paper presents the prediction of the chip formation at the machining process using a lathe machine in a more specific way focusing on facing cutting (face turning). The main purpose is to propose a new approach to predict the chip formation with the variation of the cutting directions i.e., the backward and forward direction. In addition, the interaction between stress analysis and chip formation on cutting process was also investigated. The simulations were conducted using three dimensional (3D) finite element method based on ABAQUS software with aluminum and high speed steel (HSS) as the workpiece and the tool materials, respectively. The simulation result showed that the chip resulted using a backward direction depicts a better formation than that using a conventional (forward) direction.

Sparse Feature Extraction for Pose-Tolerant Face Recognition.

PubMed

Abiantun, Ramzi; Prabhu, Utsav; Savvides, Marios

2014-10-01

Automatic face recognition performance has been steadily improving over years of research, however it remains significantly affected by a number of factors such as illumination, pose, expression, resolution and other factors that can impact matching scores. The focus of this paper is the pose problem which remains largely overlooked in most real-world applications. Specifically, we focus on one-to-one matching scenarios where a query face image of a random pose is matched against a set of gallery images. We propose a method that relies on two fundamental components: (a) A 3D modeling step to geometrically correct the viewpoint of the face. For this purpose, we extend a recent technique for efficient synthesis of 3D face models called 3D Generic Elastic Model. (b) A sparse feature extraction step using subspace modeling and ℓ1-minimization to induce pose-tolerance in coefficient space. This in return enables the synthesis of an equivalent frontal-looking face, which can be used towards recognition. We show significant performance improvements in verification rates compared to commercial matchers, and also demonstrate the resilience of the proposed method with respect to degrading input quality. We find that the proposed technique is able to match non-frontal images to other non-frontal images of varying angles.

Seven-Step Problem-Based Learning in an Interaction Design Course

ERIC Educational Resources Information Center

Schultz, Nette; Christensen, Hans Peter

2004-01-01

The objective in this paper is the implementation of the highly structured seven-step problem-based learning (PBL) procedure as part of the learning process in a human-computer interaction (HCI) design course at the Technical University of Denmark, taking into account the common learning processes in PBL and the interaction design process. These…

Forward and backward transitions in pharmacy-based immunization services.

PubMed

Westrick, Salisa C

2010-03-01

Community pharmacies can engage in immunization services by contracting with an external workforce (outsourced mechanism) or staff pharmacists (in-house mechanism) to deliver the services. Because an outsourced mechanism generally requires lower organizational commitment, pharmacies often start with an outsourced mechanism. Later, these pharmacies can have 1 of the following transitions: sit on a fence by continuing with an outsourced mechanism, move backward by abandoning any immunization services, or move forward by implementing an in-house mechanism. Using Rogers' Diffusion of Innovations model and Behavioral Theory of the Firm as guidance, this study identified the associations between perceived characteristics of immunization services and backward/forward transitions. A cross-sectional mail survey was conducted to collect data from key informants of Washington State community pharmacies during May-July 2004 (response rate=46.9%). A total of 106 pharmacies were included in the analysis. Based on pharmacy's immunization service transitions, these pharmacies were identified as Fence sitters, Backward movers, or Forward movers. Relationships between these transitions, pharmacy characteristics, and perceived characteristics of immunization services were analyzed using bivariate and multinomial logistic regression techniques. Backward and Forward movers had less positive assessments of outsourced services when compared with Fence sitters. Backward and Forward movers differed in their perceptions of in-house services; Backward movers generally perceived no differences between these 2 services, whereas Forward movers generally perceived in-house services to be superior to outsourced services. Furthermore, the odds of being a Forward mover increased as perceived technical and social benefits of outsourced services decreased, perceived compatibility of in-house services increased, and perceived complexity of in-house services decreased. Perceived characteristics of

Forward-backward elliptic anisotropy correlations in parton cascades

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

Han, L. X.; Graduate School of the Chinese Academy of Sciences, Beijing 100080; Ma, G. L.

2011-04-15

A potential experimental probe, the forward-backward elliptic anisotropy correlation (C{sub FB}), has been proposed by Liao and Koch to distinguish the jet and true elliptic flow contribution to the measured elliptic flow (v{sub 2}) in relativistic heavy-ion collisions. The jet and flow fluctuation contribution to elliptic flow is investigated within the framework of a multiphase transport model using the C{sub FB} probe. We find that the C{sub FB} correlation is remarkably different from, and about two times that, proposed by Liao and Koch. It originates from the correlation between fluctuation of forward and that of backward elliptic flow at amore » low transverse momentum, which is mainly caused by the initial correlation between fluctuation of forward and that of backward eccentricity. This results in an amendment of the C{sub FB} by a term related to the correlation between fluctuation of forward and that of backward elliptic flow. Our results suggest that a suitable rapidity gap for C{sub FB} correlation studies is about {+-}3.5.« less

Semantic Structures of One-Step Word Problems Involving Multiplication or Division.

ERIC Educational Resources Information Center

Schmidt, Siegbert; Weiser, Werner

1995-01-01

Proposes a four-category classification of semantic structures of one-step word problems involving multiplication and division: forming the n-th multiple of measures, combinatorial multiplication, composition of operators, and multiplication by formula. This classification is compatible with semantic structures of addition and subtraction word…

A backward Monte Carlo method for efficient computation of runaway probabilities in runaway electron simulation

NASA Astrophysics Data System (ADS)

Zhang, Guannan; Del-Castillo-Negrete, Diego

2017-10-01

Kinetic descriptions of RE are usually based on the bounced-averaged Fokker-Planck model that determines the PDFs of RE. Despite of the simplification involved, the Fokker-Planck equation can rarely be solved analytically and direct numerical approaches (e.g., continuum and particle-based Monte Carlo (MC)) can be time consuming specially in the computation of asymptotic-type observable including the runaway probability, the slowing-down and runaway mean times, and the energy limit probability. Here we present a novel backward MC approach to these problems based on backward stochastic differential equations (BSDEs). The BSDE model can simultaneously describe the PDF of RE and the runaway probabilities by means of the well-known Feynman-Kac theory. The key ingredient of the backward MC algorithm is to place all the particles in a runaway state and simulate them backward from the terminal time to the initial time. As such, our approach can provide much faster convergence than the brute-force MC methods, which can significantly reduce the number of particles required to achieve a prescribed accuracy. Moreover, our algorithm can be parallelized as easy as the direct MC code, which paves the way for conducting large-scale RE simulation. This work is supported by DOE FES and ASCR under the Contract Numbers ERKJ320 and ERAT377.

"Cast Your Net Widely": Three Steps to Expanding and Refining Your Problem before Action Learning Application

ERIC Educational Resources Information Center

Reese, Simon R.

2015-01-01

This paper reflects upon a three-step process to expand the problem definition in the early stages of an action learning project. The process created a community-powered problem-solving approach within the action learning context. The simple three steps expanded upon in the paper create independence, dependence, and inter-dependence to aid the…

Exclusive Backward-Angle Omega Meson Electroproduction

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

Wenliang, Li

Exclusive meson electroproduction at different squared four-momenta of the exchanged virtual photon, Q 2 , and at different four-momentum transfers, t and u, can be used to probe QCD's transition from hadronic degrees of freedom at the long distance scale to quark-gluon degrees of freedom at the short distance scale. Backward-angle meson electroproduction was previously ignored, but is anticipated to offer complimentary information to conventional forward-angle meson electroproduction studies on nucleon structure. This work is a pioneering study of backward-angle ω cross sections through the exclusive 1H(e, e'p)ω reaction using the missing mass reconstruction technique. The extracted cross sections aremore » separated into the transverse (T), longitudinal (L), and LT, TT interference terms. The analyzed data were part of experiment E01-004 (Fπ-2), which used 2.6-5.2 GeV electron beams and HMS+SOS spectrometers in Jefferson Lab Hall C. The primary objective was to detect coincidence π in the forward-angle, where the backward-angle omega events were fortuitously detected. The experiment has central Q 2 values of 1.60 and 2.45 GeV 2 , at W = 2.21 GeV. There was significant coverage in phi and epsilon, which allowed separation of σ T,L,LT,TT . The data set has a unique u coverage of -u ~ 0, which corresponds to -t > 4 GeV 2 . The separated σ T result suggest a flat ~ 1/Q 1.33±1.21 dependence, whereas sigma_L seems to hold a stronger 1/Q 9.43±6.28 dependence. The σL/σ T ratio indicate σ T dominance at Q 2 = 2.45 GeV 2 at the ~90% confidence level. After translating the results into the -t space of the published CLAS data, our data show evidence of a backward-angle omega electroproduction peak at both Q 2 settings. Previously, this phenomenon showing both forward and backward-angle peaks was only observed in the meson photoproduction data. Through comparison of our σ T data with the prediction of the Transition Distribution Amplitude (TDA) model, and signs

Towards an Efficient Flooding Scheme Exploiting 2-Hop Backward Information in MANETs

NASA Astrophysics Data System (ADS)

Le, Trong Duc; Choo, Hyunseung

Flooding is an indispensable operation for providing control or routing functionalities to mobile ad hoc networks (MANETs). Previously, many flooding schemes have been studied with the intention of curtailing the problems of severe redundancies, contention, and collisions in traditional implementations. A recent approach with relatively high efficiency is 1HI by Liu et al., which uses only 1-hop neighbor information. The scheme achieves local optimality in terms of the number of retransmission nodes with time complexity &Theta(n log n), where n is the number of neighbors of a node; however, this method tends to make many redundant transmissions. In this paper, we present a novel flooding algorithm, 2HBI (2-hop backward information), that efficiently reduces the number of retransmission nodes and solves the broadcast storm problem in ad hoc networks using our proposed concept, “2-hop backward information.” The most significant feature of the proposed algorithm is that it does not require any extra communication overhead other than the exchange of 1-hop HELLO messages but maintains high deliverability. Comprehensive computer simulations show that the proposed scheme significantly reduces redundant transmissions in 1HI and in pure flooding, up to 38% and 91%, respectively; accordingly it alleviates contention and collisions in networks.

Effect of Turbulence Intensity on Cross-Injection Film Cooling at a Stepped or Smooth Endwall of a Gas Turbine Vane Passage

PubMed Central

Tsai, Shen-Ta; Jhuo, Yue-Hua

2014-01-01

This study is concerned with a film cooling technique applicable to the protection of the endwalls of a gas turbine vane. In the experiments, cross-injection coolant flow from two-row, paired, inclined holes with nonintersecting centerlines was utilized. The test model is a scaled two-half vane. The levels of turbulence intensity used in the experiments are T.I. = 1.8%, 7%, and 12%. Other parameters considered in the film cooling experiments include three inlet Reynolds numbers (9.20 × 104, 1.24 × 105, and 1.50 × 105), three blowing ratios (0.5, 1.0, and 2.0), and three endwall conditions (smooth endwall and stepped endwall with forward-facing or backward-facing step). Thermochromic liquid crystal (TLC) technique with steady-state heat transfer experiments was used to obtain the whole-field film cooling effectiveness. Results show that, at low turbulence intensity, increasing Reynolds number decreases the effectiveness in most of the vane passage. There is no monotonic trend of influence by Reynolds number at high turbulence intensity. The effect of blowing ratio on the effectiveness has opposite trends at low and high turbulence levels. Increasing turbulent intensity decreases the effectiveness, especially near the inlet of the vane passage. With a stepped endwall, turbulence intensity has only mild effect on the film cooling effectiveness. PMID:24592153

Effect of turbulence intensity on cross-injection film cooling at a stepped or smooth endwall of a gas turbine vane passage.

PubMed

Wu, Pey-Shey; Tsai, Shen-Ta; Jhuo, Yue-Hua

2014-01-01

This study is concerned with a film cooling technique applicable to the protection of the endwalls of a gas turbine vane. In the experiments, cross-injection coolant flow from two-row, paired, inclined holes with nonintersecting centerlines was utilized. The test model is a scaled two-half vane. The levels of turbulence intensity used in the experiments are T.I. = 1.8%, 7%, and 12%. Other parameters considered in the film cooling experiments include three inlet Reynolds numbers (9.20 × 10(4), 1.24 × 10(5), and 1.50 × 10(5)), three blowing ratios (0.5, 1.0, and 2.0), and three endwall conditions (smooth endwall and stepped endwall with forward-facing or backward-facing step). Thermochromic liquid crystal (TLC) technique with steady-state heat transfer experiments was used to obtain the whole-field film cooling effectiveness. Results show that, at low turbulence intensity, increasing Reynolds number decreases the effectiveness in most of the vane passage. There is no monotonic trend of influence by Reynolds number at high turbulence intensity. The effect of blowing ratio on the effectiveness has opposite trends at low and high turbulence levels. Increasing turbulent intensity decreases the effectiveness, especially near the inlet of the vane passage. With a stepped endwall, turbulence intensity has only mild effect on the film cooling effectiveness.

The backward phase flow and FBI-transform-based Eulerian Gaussian beams for the Schroedinger equation

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

Leung Shingyu, E-mail: masyleung@ust.h; Qian Jianliang, E-mail: qian@math.msu.ed

2010-11-20

We propose the backward phase flow method to implement the Fourier-Bros-Iagolnitzer (FBI)-transform-based Eulerian Gaussian beam method for solving the Schroedinger equation in the semi-classical regime. The idea of Eulerian Gaussian beams has been first proposed in . In this paper we aim at two crucial computational issues of the Eulerian Gaussian beam method: how to carry out long-time beam propagation and how to compute beam ingredients rapidly in phase space. By virtue of the FBI transform, we address the first issue by introducing the reinitialization strategy into the Eulerian Gaussian beam framework. Essentially we reinitialize beam propagation by applying themore » FBI transform to wavefields at intermediate time steps when the beams become too wide. To address the second issue, inspired by the original phase flow method, we propose the backward phase flow method which allows us to compute beam ingredients rapidly. Numerical examples demonstrate the efficiency and accuracy of the proposed algorithms.« less

Influence of curriculum type on student performance in the United States Medical Licensing Examination Step 1 and Step 2 exams: problem-based learning vs. lecture-based curriculum.

PubMed

Enarson, C; Cariaga-Lo, L

2001-11-01

The results of the United States Medical Licensing Examination Step 1 and 2 examinations are reported for students enrolled in a problem-based and traditional lecture-based curricula over a seven-year period at a single institution. There were no statistically significant differences in mean scores on either examination over the seven year period as a whole. There were statistically significant main effects noted by cohort year and curricular track for both the Step 1 and 2 examinations. These results support the general, long-term effectiveness of problem-based learning with respect to basic and clinical science knowledge acquisition. This paper reports the United States Medical Licensing Examination Step 1 and Step 2 results for students enrolled in a problem-based and traditional lecture-based learning curricula over the seven-year period (1992-98) in order to evaluate the adequacy of each curriculum in supporting students learning of the basic and clinical sciences. Six hundred and eighty-nine students who took the United States Medical Licensing Examination Step 1 and 540 students who took Step 2 for the first time over the seven-year period were included in the analyses. T-test analyses were utilized to compare students' Step 1 and Step 2 performance by curriculum groups. United States Medical Licensing Examination Step 1 scores over the seven-year period were 214 for Traditional Curriculum students and 208 for Parallel Curriculum students (t-value = 1.32, P=0.21). Mean Step 2 scores over the seven-year period were 208 for Traditional Curriculum students and 206 for Parallel Curriculum students (t-value=1.08, P=0.30). Statistically significant main effects were noted by cohort year and curricular track for both the Step 1 and Step 2 examinations. The totality of experience in both groups, although differing by curricular type, may be similar enough that the comparable scores are what should be expected. These results should be reassuring to curricular

Malagasy Backward Object Control

ERIC Educational Resources Information Center

Potsdam, Eric

2009-01-01

Backward control is an obligatory interpretational dependency between an overt controller and a nonovert controllee in which the controllee is structurally superior to the controller: "Meg persuaded [Delta]i" ["Roni to give up"]. It contrasts with ordinary forward control, in which the controller is structurally higher: "Meg persuaded Roni"…

Backward Blocking and Interference between Cues Are Empirically Equivalent in Non-Causally Framed Learning Tasks

ERIC Educational Resources Information Center

Luque, David; Moris, Joaquin; Orgaz, Cristina; Cobos, Pedro L.; Matute, Helena

2011-01-01

Backward blocking (BB) and interference between cues (IbC) are cue competition effects produced by very similar manipulations. In a standard BB design, both effects might occur simultaneously, which implies a potential problem for studying BB. In the present study with humans, the magnitude of both effects was compared using a non-causal scenario…

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

NASA Technical Reports Server (NTRS)

Mcdaniel, James C.; Fletcher, Douglas G.; Hartfield, Roy J.; Hollo, Steven D.

1991-01-01

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.

Step Bunching: Influence of Impurities and Solution Flow

NASA Technical Reports Server (NTRS)

Chernov, A. A.; Vekilov, P. G.; Coriell, S. R.; Murray, B. T.; McFadden, G. B.

1999-01-01

Step bunching results in striations even at relatively early stages of its development and in inclusions of mother liquor at the later stages. Therefore, eliminating step bunching is crucial for high crystal perfection. At least 5 major effects causing and influencing step bunching are known: (1) Basic morphological instability of stepped interfaces. It is caused by concentration gradient in the solution normal to the face and by the redistribution of solute tangentially to the interface which redistribution enhances occasional perturbations in step density due to various types of noise; (2) Aggravation of the above basic instability by solution flowing tangentially to the face in the same directions as the steps or stabilization of equidistant step train if these flows are antiparallel; (3) Enhanced bunching at supersaturation where step velocity v increases with relative supersaturation s much faster than linear. This v(s) dependence is believed to be associated with impurities. The impurities of which adsorption time is comparable with the time needed to deposit one lattice layer may also be responsible for bunching; (4) Very intensive solution flow stabilizes growing interface even at parallel solution and step flows; (5) Macrosteps were observed to nucleate at crystal corners and edges. Numerical simulation, assuming step-step interactions via surface diffusion also show that step bunching may be induced by random step nucleation at the facet edge and by discontinuity in the step density (a ridge) somewhere in the middle of a face. The corresponding bunching patterns produce the ones observed in experiment. The nature of step bunching generated at the corners and edges and by dislocation step sources, as well as the also relative importance and interrelations between mechanisms 1-5 is not clear, both from experimental and theoretical standpoints. Furthermore, several laws controlling the evolution of existing step bunches have been suggested, though

Backward bifurcation and optimal control of Plasmodium Knowlesi malaria

NASA Astrophysics Data System (ADS)

Abdullahi, Mohammed Baba; Hasan, Yahya Abu; Abdullah, Farah Aini

2014-07-01

A deterministic model for the transmission dynamics of Plasmodium Knowlesi malaria with direct transmission is developed. The model is analyzed using dynamical system techniques and it shows that the backward bifurcation occurs for some range of parameters. The model is extended to assess the impact of time dependent preventive (biological and chemical control) against the mosquitoes and vaccination for susceptible humans, while treatment for infected humans. The existence of optimal control is established analytically by the use of optimal control theory. Numerical simulations of the problem, suggest that applying the four control measure can effectively reduce if not eliminate the spread of Plasmodium Knowlesi in a community.

Ultrafast laser control of backward superfluorescence towards standoff sensing

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

Ariunbold, Gombojav O.; National University of Mongolia, Ulaanbaatar 210646; Baylor University, Waco, Texas 76798

2014-01-13

We study infrared backward cooperative emission in a rubidium vapor induced by ultrafast two-photon optical excitations. The laser coherent control of the backward emission is demonstrated by using a pair of 100 fs pulses with a variable time delay. The temporal variation (quantum beat) of the backward beam intensity due to interference of atomic transitions in the rubidium atomic level system 5S-5P-5D is produced and controlled. Based on the obtained experimental results, we discuss possible applications of the developed approach for creation of an effective “guide star” in the sodium atomic layer in the upper atmosphere (mesosphere)

Effects of Implied Motion and Facing Direction on Positional Preferences in Single-Object Pictures.

PubMed

Palmer, Stephen E; Langlois, Thomas A

2017-07-01

Palmer, Gardner, and Wickens studied aesthetic preferences for pictures of single objects and found a strong inward bias: Right-facing objects were preferred left-of-center and left-facing objects right-of-center. They found no effect of object motion (people and cars showed the same inward bias as chairs and teapots), but the objects were not depicted as moving. Here we measured analogous inward biases with objects depicted as moving with an implied direction and speed by having participants drag-and-drop target objects into the most aesthetically pleasing position. In Experiment 1, human figures were shown diving or falling while moving forward or backward. Aesthetic biases were evident for both inward-facing and inward-moving figures, but the motion-based bias dominated so strongly that backward divers or fallers were preferred moving inward but facing outward. Experiment 2 investigated implied speed effects using images of humans, horses, and cars moving at different speeds (e.g., standing, walking, trotting, and galloping horses). Inward motion or facing biases were again present, and differences in their magnitude due to speed were evident. Unexpectedly, faster moving objects were generally preferred closer to frame center than slower moving objects. These results are discussed in terms of the combined effects of prospective, future-oriented biases, and retrospective, past-oriented biases.

The Amygdala Is Involved in Affective Priming Effect for Fearful Faces

ERIC Educational Resources Information Center

Yang, J.; Cao, Z.; Xu, X.; Chen, G.

2012-01-01

The object of this study was to investigate whether the amygdala is involved in affective priming effect after stimuli are encoded unconsciously and consciously. During the encoding phase, each masked face (fearful or neutral) was presented to participants six times for 17 ms each, using a backward masking paradigm. During the retrieval phase,…

Steps in the bacterial flagellar motor.

PubMed

Mora, Thierry; Yu, Howard; Sowa, Yoshiyuki; Wingreen, Ned S

2009-10-01

The bacterial flagellar motor is a highly efficient rotary machine used by many bacteria to propel themselves. It has recently been shown that at low speeds its rotation proceeds in steps. Here we propose a simple physical model, based on the storage of energy in protein springs, that accounts for this stepping behavior as a random walk in a tilted corrugated potential that combines torque and contact forces. We argue that the absolute angular position of the rotor is crucial for understanding step properties and show this hypothesis to be consistent with the available data, in particular the observation that backward steps are smaller on average than forward steps. We also predict a sublinear speed versus torque relationship for fixed load at low torque, and a peak in rotor diffusion as a function of torque. Our model provides a comprehensive framework for understanding and analyzing stepping behavior in the bacterial flagellar motor and proposes novel, testable predictions. More broadly, the storage of energy in protein springs by the flagellar motor may provide useful general insights into the design of highly efficient molecular machines.

Problems Teachers Face When Doing Action Research and Finding Possible Solutions: Three Cases

ERIC Educational Resources Information Center

Zhou, Jun

2012-01-01

Through case studies, this paper explores problems teachers face when doing action research: for instance, teachers may misunderstand the research, mistrust university researchers, lack the time or adequate library resources to conduct research, lack theoretical guidance or knowledge of research methodology, and feel pressure or frustration during…

Forward and Backward Pressure Waveform Morphology in Hypertension

PubMed Central

Li, Ye; Gu, Haotian; Fok, Henry; Alastruey, Jordi

2017-01-01

We tested the hypothesis that increased pulse wave reflection and altered backward waveform morphology contribute to increased pulse pressure in subjects with higher pulse pressure compared with lower pulse pressure and to actions of vasoactive drugs to increase pulse pressure. We examined the relationship of backward to forward wave morphology in 158 subjects who were evaluated for hypertension (including some normotensive subjects) divided into 3 groups by central pulse pressure: group 1, 33±6.5 mm Hg; group 2, 45±4.1 mm Hg; and group 3, 64±12.9 mm Hg (means±SD) and in healthy normotensive subjects during administration of inotropic and vasomotor drugs. Aortic pressure and flow in the aortic root were estimated by carotid tonometry and Doppler sonography, respectively. Morphology of the backward wave relative to the forward wave was similar in subjects in the lowest and highest tertiles of pulse pressure. Similar results were seen with the inotropic, vasopressor and vasodilator drugs, dobutamine, norepinephrine, and phentolamine, with the backward wave maintaining a constant ratio to the forward wave. However, nitroglycerin, a drug with a specific action to dilate muscular conduit arteries, reduced the amplitude of the backward wave relative to the forward wave from 0.26±0.018 at baseline to 0.19±0.019 during nitroglycerin 30 μg/min IV (P<0.01). These results are best explained by an approximately constant amount of reflection of the forward wave from the peripheral vasculature. The amount of reflection can be modified by dilation of peripheral muscular conduit arteries but contributes little to increased pulse pressure in hypertension. PMID:27920128

Forward and Backward Pressure Waveform Morphology in Hypertension.

PubMed

Li, Ye; Gu, Haotian; Fok, Henry; Alastruey, Jordi; Chowienczyk, Philip

2017-02-01

We tested the hypothesis that increased pulse wave reflection and altered backward waveform morphology contribute to increased pulse pressure in subjects with higher pulse pressure compared with lower pulse pressure and to actions of vasoactive drugs to increase pulse pressure. We examined the relationship of backward to forward wave morphology in 158 subjects who were evaluated for hypertension (including some normotensive subjects) divided into 3 groups by central pulse pressure: group 1, 33±6.5 mm Hg; group 2, 45±4.1 mm Hg; and group 3, 64±12.9 mm Hg (means±SD) and in healthy normotensive subjects during administration of inotropic and vasomotor drugs. Aortic pressure and flow in the aortic root were estimated by carotid tonometry and Doppler sonography, respectively. Morphology of the backward wave relative to the forward wave was similar in subjects in the lowest and highest tertiles of pulse pressure. Similar results were seen with the inotropic, vasopressor and vasodilator drugs, dobutamine, norepinephrine, and phentolamine, with the backward wave maintaining a constant ratio to the forward wave. However, nitroglycerin, a drug with a specific action to dilate muscular conduit arteries, reduced the amplitude of the backward wave relative to the forward wave from 0.26±0.018 at baseline to 0.19±0.019 during nitroglycerin 30 μg/min IV (P<0.01). These results are best explained by an approximately constant amount of reflection of the forward wave from the peripheral vasculature. The amount of reflection can be modified by dilation of peripheral muscular conduit arteries but contributes little to increased pulse pressure in hypertension. © 2016 The Authors.

Across Space and Time: Infants Learn from Backward and Forward Visual Statistics

ERIC Educational Resources Information Center

Tummeltshammer, Kristen; Amso, Dima; French, Robert M.; Kirkham, Natasha Z.

2017-01-01

This study investigates whether infants are sensitive to backward and forward transitional probabilities within temporal and spatial visual streams. Two groups of 8-month-old infants were familiarized with an artificial grammar of shapes, comprising backward and forward base pairs (i.e. two shapes linked by strong backward or forward transitional…

Investigation of the capillary flow through open surface microfluidic structures

NASA Astrophysics Data System (ADS)

Taher, Ahmed; Jones, Benjamin; Fiorini, Paolo; Lagae, Liesbet

2017-02-01

The passive nature of capillary microfluidics for pumping and actuation of fluids is attractive for many applications including point of care medical diagnostics. For such applications, there is often the need to spot dried chemical reagents in the bottom of microfluidic channels after device fabrication; it is often more practical to have open surface devices (i.e., without a cover or lid). However, the dynamics of capillary driven flow in open surface devices have not been well studied for many geometries of interest. In this paper, we investigate capillary flow in an open surface microchannel with a backward facing step. An analytical model is developed to calculate the capillary pressure as the liquid-vapor interface traverses a backward facing step in an open microchannel. The developed model is validated against results from Surface Evolver liquid-vapor surface simulations and ANSYS Fluent two-phase flow simulations using the volume of fluid approach. Three different aspect ratios (inlet channel height by channel width) were studied. The analytical model shows good agreement with the simulation results from both modeling methods for all geometries. The analytical model is used to derive an expression for the critical aspect ratio (the minimum channel aspect ratio for flow to proceed across the backward facing step) as a function of contact angle.

Methicillin Resistant Staphylococcus Aureus Biofilm Formation Over A Separated Flow Region Under Steady And Pulsatile Flow Conditions

NASA Astrophysics Data System (ADS)

Salek, M. Mehdi; Martinuzzi, Robert

2012-02-01

Several researchers have observed that the formation, morphology and susceptibility of bacterial biofilms are affected by the local hydrodynamic condition and, in particular, shear stresses acting on the fluid-biofilm interface. A backwards facing step (BFS) experimental model has been widely utilized as an in vitro model to examine and characterize the effect of flow separation and recirculation zones comparable to those present within various medical devices as well as those observed in vivo. The specific geometry of BFS covers a vide range of flow features observed in physiological or environmental conditions. The hypothesis of this study is that the flow behavior and structures can effectively contribute to the transport and attachment of cells and affecting the morphology of adhered colonies as well as suspended structures (i.e. biofilm streamers). Hence, the formation of the recirculation region occurring within a backward facing step (BFS) under steady and pulsatile conditions as well as three-dimensional flow structures arising close to the side walls are investigated to correlate to biofilms behavior. This hypothesis is investigated using a backward facing step incorporated into a flow cell under steady and pulsatile flow regimes to study the growth of methicillin resistant Staphylococcus aureus (MRSA) UC18 as the study microorganism.

The New Workforce Generation: Understanding the Problems Facing Parental Involvement in Jordanian Kindergartens

ERIC Educational Resources Information Center

Ihmeideh, Fathi; Khasawneh, Samer; Mahfouz, Safi; Khawaldeh, Moustafa

2008-01-01

This study aimed to investigate the problems facing parental involvement in Jordanian kindergartens from the parents' perspectives. A 36-item questionnaire that addressed five domains was designed by the researchers and distributed among the study participants. The study sample consisted of 297 parents of kindergarten children from various…

Bench evaluation: three face-shield CPR barrier devices.

PubMed

Simmons, M; Deao, D; Moon, L; Peters, K; Cavanaugh, S

1995-06-01

Due to the fear of disease transmission, the practice of mouth-to-mouth (M-M) rescue breathing is rarely performed; to address this concern, many types of CPR barrier devices have been developed. These include bag-valve-mask devices, mouth-to-mask devices, and face shields (FS). The purpose of this study was to measure the volumes delivered during mouth-to-face shield (M-FS) breathing, to measure the back pressure and calculate the resistance to flow through their 1-way valves, and to test for backward leak of gas through the valves. Three FS brands were evaluated: Kiss of Life (KOL), MicroSHIELD (Micro) and Res-Cue Key (RCK). Volume delivered during M-M and M-FS breathing was evaluated by 10 rescuers who used the devices while performing rescue breathing on a CPR mannequin. Back pressure was measured and resistance calculated by directing airflow through the 1-way valves. Backward leak was evaluated by measuring the O2 concentration at the rescuer side of the valve while 100% O2 was directed toward the patient side of the valve. Differences among the brands were evaluated using analysis of variance. The mean (SD) values for volumes in L were: M-M 1.00 (0.25), Micro 0.77 (0.20), RCK 0.64 (0.10), and KOL 0.24 (0.11). Mean values for back pressure in cm H2O at 50 L/min were Micro 16.7 (1.29), KOL 7.22 (0.13), and RCK 2.15 (0.16). Significant backward leak only occurred with RCK. Not one of the FSs tested met all of the requirements suggested by the American Heart Association and by the International Standards Organization.

Current Welfare Problems Facing Horses in Great Britain as Identified by Equine Stakeholders.

PubMed

Horseman, Susan V; Buller, Henry; Mullan, Siobhan; Whay, Helen R

2016-01-01

Despite growing concerns about the welfare of horses in Great Britain (GB) there has been little surveillance of the welfare status of the horse population. Consequently we have limited knowledge of the range of welfare problems experienced by horses in GB and the situations in which poor welfare occurs. Thirty-one in-depth interviews were conducted with a cross -section of equine stakeholders, in order to explore their perceptions of the welfare problems faced by horses in GB. Welfare problems relating to health, management and riding and training were identified, including horses being under or over weight, stabling 24 hours a day and the inappropriate use of training aids. The interviewees also discussed broader contexts in which they perceived that welfare was compromised. The most commonly discussed context was where horses are kept in unsuitable environments, for example environments with poor grazing. The racing industry and travellers horses were identified as areas of the industry where horse welfare was particularly vulnerable to compromise. Lack of knowledge and financial constraints were perceived to be the root cause of poor welfare by many interviewees. The findings give insight into the range of welfare problems that may be faced by horses in GB, the contexts in which these may occur and their possible causes. Many of the problems identified by the interviewees have undergone limited scientific investigation pointing to areas where further research is likely to be necessary for welfare improvement. The large number of issues identified suggests that some form of prioritisation may be necessary to target research and resources effectively.

Current Welfare Problems Facing Horses in Great Britain as Identified by Equine Stakeholders

PubMed Central

Horseman, Susan V.; Buller, Henry

2016-01-01

Despite growing concerns about the welfare of horses in Great Britain (GB) there has been little surveillance of the welfare status of the horse population. Consequently we have limited knowledge of the range of welfare problems experienced by horses in GB and the situations in which poor welfare occurs. Thirty-one in-depth interviews were conducted with a cross -section of equine stakeholders, in order to explore their perceptions of the welfare problems faced by horses in GB. Welfare problems relating to health, management and riding and training were identified, including horses being under or over weight, stabling 24 hours a day and the inappropriate use of training aids. The interviewees also discussed broader contexts in which they perceived that welfare was compromised. The most commonly discussed context was where horses are kept in unsuitable environments, for example environments with poor grazing. The racing industry and travellers horses were identified as areas of the industry where horse welfare was particularly vulnerable to compromise. Lack of knowledge and financial constraints were perceived to be the root cause of poor welfare by many interviewees. The findings give insight into the range of welfare problems that may be faced by horses in GB, the contexts in which these may occur and their possible causes. Many of the problems identified by the interviewees have undergone limited scientific investigation pointing to areas where further research is likely to be necessary for welfare improvement. The large number of issues identified suggests that some form of prioritisation may be necessary to target research and resources effectively. PMID:27501387

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.

A study of fuzzy logic ensemble system performance on face recognition problem

NASA Astrophysics Data System (ADS)

Polyakova, A.; Lipinskiy, L.

2017-02-01

Some problems are difficult to solve by using a single intelligent information technology (IIT). The ensemble of the various data mining (DM) techniques is a set of models which are able to solve the problem by itself, but the combination of which allows increasing the efficiency of the system as a whole. Using the IIT ensembles can improve the reliability and efficiency of the final decision, since it emphasizes on the diversity of its components. The new method of the intellectual informational technology ensemble design is considered in this paper. It is based on the fuzzy logic and is designed to solve the classification and regression problems. The ensemble consists of several data mining algorithms: artificial neural network, support vector machine and decision trees. These algorithms and their ensemble have been tested by solving the face recognition problems. Principal components analysis (PCA) is used for feature selection.

The Embodiment of Success and Failure as Forward versus Backward Movements

PubMed Central

Robinson, Michael D.; Fetterman, Adam K.

2015-01-01

People often speak of success (e.g., “advance”) and failure (e.g., “setback”) as if they were forward versus backward movements through space. Two experiments sought to examine whether grounded associations of this type influence motor behavior. In Experiment 1, participants categorized success versus failure words by moving a joystick forward or backward. Failure categorizations were faster when moving backward, whereas success categorizations were faster when moving forward. Experiment 2 removed the requirement to categorize stimuli and used a word rehearsal task instead. Even without Experiment 1’s response procedures, a similar cross-over interaction was obtained (e.g., failure memorizations sped backward movements relative to forward ones). The findings are novel yet consistent with theories of embodied cognition and self-regulation. PMID:25658923

The embodiment of success and failure as forward versus backward movements.

PubMed

Robinson, Michael D; Fetterman, Adam K

2015-01-01

People often speak of success (e.g., "advance") and failure (e.g., "setback") as if they were forward versus backward movements through space. Two experiments sought to examine whether grounded associations of this type influence motor behavior. In Experiment 1, participants categorized success versus failure words by moving a joystick forward or backward. Failure categorizations were faster when moving backward, whereas success categorizations were faster when moving forward. Experiment 2 removed the requirement to categorize stimuli and used a word rehearsal task instead. Even without Experiment 1's response procedures, a similar cross-over interaction was obtained (e.g., failure memorizations sped backward movements relative to forward ones). The findings are novel yet consistent with theories of embodied cognition and self-regulation.

Development and Assessment of Altitude Adjustable Convergent Divergent Nozzles Using Passive Flow Control

NASA Astrophysics Data System (ADS)

Mandour Eldeeb, Mohamed

The backward facing steps nozzle (BFSN) is a new developed flow adjustable exit area nozzle. It consists of two parts, the first is a base nozzle with small area ratio and the second part is a nozzle extension with surface consists of backward facing steps. The steps number and heights are carefully chosen to produce controlled flow separation at steps edges that adjust the nozzle exit area at all altitudes (pressure ratios). The BFSN performance parameters are assessed numerically in terms of thrust and side loads against the dual-bell nozzle with the same pressure ratios and cross sectional areas. Cold flow inside the planar BFSN and planar DBN are simulated using three-dimensional turbulent Navier-Stoke equations solver at different pressure ratios. The pressure distribution over the upper and the lower nozzles walls show symmetrical flow separation location inside the BFSN and an asymmetrical flow separation location inside the DBN at same vertical plane. The side loads are calculated by integrate the pressure over the nozzles walls at different pressure ratios for both nozzles. Time dependent solution for the DBN and the BFSN are obtained by solving two-dimensional turbulent flow. The side loads over the upper and lower nozzles walls are plotted against the flow time. The BFSN side loads history shows a small values of fluctuated side loads compared with the DBN which shows a high values with high fluctuations. Hot flow 3-D numerical solutions inside the axi-symmetric BFSN and DBN are obtained at different pressure ratios and compared to assess the BFSN performance against the DBN. Pressure distributions over the nozzles walls at different circumferential angels are plotted for both nozzles. The results show that the flow separation location is axi-symmetric inside the BFSN with symmetrical pressure distributions over the nozzle circumference at different pressure ratios. While the DBN results show an asymmetrical flow separation locations over the nozzle

Stereo Particle Image Velocimetry Measurements of Transition Downstream of a Forward-Facing Step in a Swept-Wing Boundary Layer

NASA Technical Reports Server (NTRS)

Eppink, Jenna L.

2017-01-01

Stereo particle image velocimetry measurements were performed downstream of a forward-facing step in a stationary-crossflow dominated flow. Three different step heights were studied with the same leading-edge roughness configuration to determine the effect of the step on the evolution of the stationary-crossflow. Above the critical step height, which is approximately 68% of the boundary-layer thickness at the step, the step caused a significant increase in the growth of the stationary crossflow. For the largest step height studied (68%), premature transition occurred shortly downstream of the step. The stationary crossflow amplitude only reached approximately 7% of U(sub e) in this case, which suggests that transition does not occur via the high-frequency secondary instabilities typically associated with stationary crossflow transition. The next largest step of 60% delta still caused a significant impact on the growth of the stationary crossflow downstream of the step, but the amplitude eventually returned to that of the baseline case, and the transition front remained the same. The smallest step height (56%) only caused a small increase in the stationary crossflow amplitude and no change in the transition front. A final case was studied in which the roughness on the leading edge of the model was enhanced for the lowest step height case to determine the impact of the stationary crossflow amplitude on transition. The stationary crossflow amplitude was increased by approximately four times, which resulted in premature transition for this step height. However, some notable differences were observed in the behavior of the stationary crossflow mode, which indicate that the interaction mechanism which results in the increased growth of the stationary crossflow downstream of the step may be different in this case compared to the larger step heights.

Backward distraction osteogenesis in a patient with severe mandibular micrognathia.

PubMed

Mitsukawa, Nobuyuki; Morishita, Tadashi; Saiga, Atsuomi; Akita, Shinsuke; Kubota, Yoshitaka; Satoh, Kaneshige

2013-09-01

Maxillary skeletal prognathism can involve severe mandibular micrognathia with marked mandibular retrognathism or hypoplasia. For patients with such a condition, a conventional treatment is mandibular advancement by sagittal split ramus osteotomy (SSRO). This procedure has problems such as insufficient advancement, instability of jaw position, and postoperative relapse. Thus, in recent years, mandibular distraction osteogenesis has been used in some patients. Mandibular distraction has many advantages, but an ideal occlusion is difficult to achieve using this procedure. That is, 3-dimensional control cannot be attained using an internal device that is unidirectional. This report describes a case of severe mandibular micrognathia in a 14-year-old girl treated using backward distraction osteogenesis. This procedure was first reported by Ishii et al (Jpn J Jaw Deform 2004; 14:49) and involves a combination of SSRO and ramus distraction osteogenesis. In the present study, intermaxillary fixation in centric occlusion was performed after osteotomy, and proximal bone segments were distracted in a posterosuperior direction. This procedure is a superior surgical technique that avoids the drawbacks of SSRO and conventional mandibular distraction. However, it applies a large load to the temporomandibular joints and requires thorough management. Thus, careful evaluation needs to be made of the indication for backward distraction osteogenesis.

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).

Characterization of TiN coating layers using ultrasonic backward radiation.

PubMed

Song, Sung-Jin; Yang, Dong-Joo; Kim, Hak-Joon; Kwon, Sung D; Lee, Young-Ze; Kim, Ji-Yoon; Choi, Song-Chun

2006-12-22

Since ceramic layers coated on machinery components inevitably experience the changes in their properties it is necessary to evaluate the characteristics of ceramic coating layers nondestructively for the reliable use of coated components and the remaining life prediction. To address such a need, in the present study, the ultrasonic backward radiation technique is applied to examine the very thin TiN ceramic layers coated on AISI 1045 steel or austenitic 304 steel substrate. Specifically, the ultrasonic backward radiation profiles have been measured with variations in specimen preparation conditions such as coating layer thickness and sliding loading. In the experiments performed in the current study, the peak angle and the peak amplitude of ultrasonic backward radiation profile varied sensitively according to two specimen preparation conditions. In fact, this result demonstrates a high possibility of the ultrasonic backward radiation as an effective tool for the nondestructive characterization of the TiN ceramic coating layers even in such a thin regime.

Investigating backward scattered second harmonic generation from various mouse collagen tissues

NASA Astrophysics Data System (ADS)

Shen, Mengzhe; Tian, Yunxian; Chong, Shau Poh; Zhao, Jianhua; Zeng, Haishan; Tang, Shuo

2014-02-01

A confocal multiphoton microscopy system with various detection pinholes was used to differentiate backward scattered second harmonic generation (BS-SHG) from backward generated SHG (BG-SHG) based on the fact that BS-SHG is more scattered and therefore has a much bigger spot size than BG-SHG. BS-SHG is quantified from two types of mouse tissues, such as Achilles tendon, and skin, and at various focal depths. It is found that the BS-SHG contributes less to the total backward SHG for the skin than Achilles tendon with thicknesses of around three hundred micrometers. For tissue with larger F/B intensity ratio such as Achilles tendon, increasing the tissue thickness reduces it tremendously. However, for tissue with smaller F/B intensity ratio, tissue thickness increment does not alter it significantly. In addition, larger F/B intensity ratio might be related with a greater scattering coefficient from our Achilles tendon and skin comparison. When the focal point is moved deeper into tissue, the contribution of BS-SHG is found to decrease due to a reduced pass length of the forward propagated photons. On the contrary, when the tissue thickness increases, the contribution of the BS-SHG is increased. These observations for thicker skin tissues are related with our F/B intensity ratio measurement for thin mouse skin sample in terms of that the magnitude of backward generated SHG are dominant among the total backward SHG in mouse skin tissue. Considering the phase mismatching condition in the forward and backward directions, these results may indicate that quasi-phase matching originating from the regular structure of collagen could help with reducing the phase mismatch especially in the backward direction.

Compensatory balance reactions during forward and backward walking on a treadmill.

PubMed

Bolton, D A E; Misiaszek, J E

2012-04-01

Previous work suggests that balance perturbations to the body opposing the direction of progression during walking lead to larger amplitude corrective reactions than perturbations concurrent with walking direction. To test this hypothesis, subjects received forward and backward perturbations applied to the pelvis through a padded harness, while walking forwards or backwards on a treadmill. Contrary to our hypothesis, the greatest responses were associated with backward perturbations regardless of the direction of walking. Copyright © 2011 Elsevier B.V. All rights reserved.

The backward phase flow and FBI-transform-based Eulerian Gaussian beams for the Schrödinger equation

NASA Astrophysics Data System (ADS)

Leung, Shingyu; Qian, Jianliang

2010-11-01

We propose the backward phase flow method to implement the Fourier-Bros-Iagolnitzer (FBI)-transform-based Eulerian Gaussian beam method for solving the Schrödinger equation in the semi-classical regime. The idea of Eulerian Gaussian beams has been first proposed in [12]. In this paper we aim at two crucial computational issues of the Eulerian Gaussian beam method: how to carry out long-time beam propagation and how to compute beam ingredients rapidly in phase space. By virtue of the FBI transform, we address the first issue by introducing the reinitialization strategy into the Eulerian Gaussian beam framework. Essentially we reinitialize beam propagation by applying the FBI transform to wavefields at intermediate time steps when the beams become too wide. To address the second issue, inspired by the original phase flow method, we propose the backward phase flow method which allows us to compute beam ingredients rapidly. Numerical examples demonstrate the efficiency and accuracy of the proposed algorithms.

A two steps solution approach to solving large nonlinear models: application to a problem of conjunctive use.

PubMed

Vieira, J; Cunha, M C

2011-01-01

This article describes a solution method of solving large nonlinear problems in two steps. The two steps solution approach takes advantage of handling smaller and simpler models and having better starting points to improve solution efficiency. The set of nonlinear constraints (named as complicating constraints) which makes the solution of the model rather complex and time consuming is eliminated from step one. The complicating constraints are added only in the second step so that a solution of the complete model is then found. The solution method is applied to a large-scale problem of conjunctive use of surface water and groundwater resources. The results obtained are compared with solutions determined with the direct solve of the complete model in one single step. In all examples the two steps solution approach allowed a significant reduction of the computation time. This potential gain of efficiency of the two steps solution approach can be extremely important for work in progress and it can be particularly useful for cases where the computation time would be a critical factor for having an optimized solution in due time.

Functional morphology and hydrodynamics of backward swimming in bluegill sunfish, Lepomis macrochirus.

PubMed

Flammang, Brooke E; Lauder, George V

2016-10-01

Most teleost fishes, like the bluegill sunfish Lepomis macrochirus, have multiple flexible fins that are used as modifiable control surfaces. This helps to make fish highly maneuverable, permitting behaviors like reversing direction of motion and swimming backwards without having to rotate body position. To answer the question of how fish swim backwards we used high-speed videography and electromyography to determine the kinematics and muscle activity necessary to produce reverse-direction propulsion in four bluegill sunfish. We found that, in contrast to slow forward swimming, low-speed backward swimming is a multi-fin behavior, utilizing the pectoral, dorsal, anal, and caudal fins. The pectoral fins alternate beats, each fin broadly flaring on the outstroke and feathered on the instroke. The dorsal fin and dorsal portion of the caudal fin move out of phase as do the anal fin and ventral portion of the caudal fin. Electromyography of muscles in the pectoral, dorsal, anal, and caudal fins demonstrated bilateral activation when these fins changed direction, suggesting that fins are stiffened at this time. In addition to backward propulsion by the pectoral fins, particle image velocimetry revealed that the dorsal and anal fins are capable of producing reverse momentum jets to propel the fish backward. Because teleost fishes are statically unstable, locomotion at slow speeds requires precise fin control to adequately balance torques produced about the center of mass. Therefore, the kinematics of backward swimming may be the result of compensation for rolling, pitching, and yawning instability. We suggest that asymmetric pectoral fin activity with feathering during adduction balances rolling instability. The ventral to dorsal undulatory wave on the caudal fin controls pitch instability and yaw instability encountered from pectoral-driven backward locomotion. Thrust generation from the dorsal and anal fins decreases the destabilizing effect of the long moment arm of the

Early changes in Achilles tendon behaviour in vivo following downhill backwards walking.

PubMed

Joseph, C W; Bradshaw, E J; Furness, T P; Kemp, J; Clark, R A

2016-01-01

Downhill backwards walking causes repeated, cyclical loading of the muscle-tendon unit. The effect this type of repeated loading has on the mechanical behaviour of the Achilles tendon is presently unknown. This study aimed to investigate the biomechanical response of the Achilles tendon aponeurosis complex following a downhill backwards walking protocol. Twenty active males (age: 22.3 ± 3.0 years; mass: 74.7 ± 5.6 kg; height: 1.8 ± 0.7 m) performed 60 min of downhill (8.5°), backwards walking on a treadmill at -0.67 m · s(-1). Data were collected before, immediately post, and 24-, 48- and 168-h post-downhill backwards walking. Achilles tendon aponeurosis elongation, strain and stiffness were measured using ultrasonography. Muscle force decreased immediately post-downhill backward walking (P = 0.019). There were increases in Achilles tendon aponeurosis stiffness at 24-h post-downhill backward walking (307 ± 179.6 N · mm(-1), P = 0.004), and decreases in Achilles tendon aponeurosis strain during maximum voluntary contraction at 24 (3.8 ± 1.7%, P = 0.008) and 48 h (3.9 ± 1.8%, P = 0.002) post. Repeated cyclical loading of downhill backwards walking affects the behaviour of the muscle-tendon unit, most likely by altering muscle compliance, and these changes result in tendon stiffness increases.

Using a Backward Design Approach to Embed Assessment in Teaching

ERIC Educational Resources Information Center

Whitehouse, Mary

2014-01-01

Backward design provides a framework for curriculum planning that can be used at unit, course or school level. The approach places assessment at the heart of the planning process. In this article the ideas of backward design are outlined and their application to a current curriculum development project, York Science, is described.

Backward scattering effect of aligned carbon nanotube arrays

NASA Astrophysics Data System (ADS)

Wu, Pengfei; Ren, Zhifeng; Wang, Michael R.

2009-02-01

In terms of operational bandwidth and speed, photonic components are superior to electronic ones. However, it is difficult to control photons on nanoscale structures for data processing and interconnection. Nanophotonic device using surface plasmon (SP) offers an ideal solution to combine the superior technical advantages of both photonics and electronics on the same chip. The SP wavelength is much shorter than that of the exciting light, allowing the use of SP in various techniques that overcome diffraction limits. In this paper, we report an interesting plasmonic effect, enhanced backward scattering, by using a periodically-aligned carbon nanotube (CNT) array. The CNTs are grown on a transparent glass substrate with an average diameter of 50 nm and a length of about 1 μm. To enhance the conductivity, the CNTs are also coated with 10-nm Au layer by using E-beam CVD technique. By shining a laser beam to the CNT array, we found that the scattering intensity is maximally enhanced at the backward incident direction. The enhanced backward incident scattering is observed by using both periodic and nonperiodic CNT samples. The experimental results suggest that the backward scattering effect is due to the SP excitation and coupling. The proposed technique exploiting aligned carbon-nanotube arrays to manipulate surface plasmon will lead to useful optical features such as optical antennae effects, retro-reflection, switching, wavelength add/drop multiplexing, and may be particularly useful for optical sensing, smart target identification and optical wireless secure communication applications.

Electrophysiological Correlates of Subliminal Perception of Facial Expressions in Individuals with Autistic Traits: A Backward Masking Study

PubMed Central

Vukusic, Svjetlana; Ciorciari, Joseph; Crewther, David P.

2017-01-01

People with Autism spectrum disorder (ASD) show difficulty in social communication, especially in the rapid assessment of emotion in faces. This study examined the processing of emotional faces in typically developing adults with high and low levels of autistic traits (measured using the Autism Spectrum Quotient—AQ). Event-related potentials (ERPs) were recorded during viewing of backward-masked neutral, fearful and happy faces presented under two conditions: subliminal (16 ms, below the level of visual conscious awareness) and supraliminal (166 ms, above the time required for visual conscious awareness). Individuals with low and high AQ differed in the processing of subliminal faces, with the low AQ group showing an enhanced N2 amplitude for subliminal happy faces. Some group differences were found in the condition effects, with the Low AQ showing shorter frontal P3b and N4 latencies for subliminal vs. supraliminal condition. Although results did not show any group differences on the face-specific N170 component, there were shorter N170 latencies for supraliminal vs. subliminal conditions across groups. The results observed on the N2, showing group differences in subliminal emotion processing, suggest that decreased sensitivity to the reward value of social stimuli is a common feature both of people with ASD as well as people with high autistic traits from the normal population. PMID:28588465

Electrophysiological Correlates of Subliminal Perception of Facial Expressions in Individuals with Autistic Traits: A Backward Masking Study.

PubMed

Vukusic, Svjetlana; Ciorciari, Joseph; Crewther, David P

2017-01-01

People with Autism spectrum disorder (ASD) show difficulty in social communication, especially in the rapid assessment of emotion in faces. This study examined the processing of emotional faces in typically developing adults with high and low levels of autistic traits (measured using the Autism Spectrum Quotient-AQ). Event-related potentials (ERPs) were recorded during viewing of backward-masked neutral, fearful and happy faces presented under two conditions: subliminal (16 ms, below the level of visual conscious awareness) and supraliminal (166 ms, above the time required for visual conscious awareness). Individuals with low and high AQ differed in the processing of subliminal faces, with the low AQ group showing an enhanced N2 amplitude for subliminal happy faces. Some group differences were found in the condition effects, with the Low AQ showing shorter frontal P3b and N4 latencies for subliminal vs. supraliminal condition. Although results did not show any group differences on the face-specific N170 component, there were shorter N170 latencies for supraliminal vs. subliminal conditions across groups. The results observed on the N2, showing group differences in subliminal emotion processing, suggest that decreased sensitivity to the reward value of social stimuli is a common feature both of people with ASD as well as people with high autistic traits from the normal population.

Are forward and backward recall the same? A dual-task study of digit recall.

PubMed

St Clair-Thompson, Helen L; Allen, Richard J

2013-05-01

There is some debate surrounding the cognitive resources underlying backward digit recall. Some researchers consider it to differ from forward digit recall due to the involvement of executive control, while others suggest that backward recall involves visuospatial resources. Five experiments therefore investigated the role of executive-attentional and visuospatial resources in both forward and backward digit recall. In the first, participants completed visuospatial 0-back and 2-back tasks during the encoding of information to be remembered. The concurrent tasks did not differentially disrupt performance on backward digit recall, relative to forward digit recall. Experiment 2 shifted concurrent load to the recall phase instead and, in this case, revealed a larger effect of both tasks on backward recall, relative to forwards recall, suggesting that backward recall may draw on additional resources during the recall phase and that these resources are visuospatial in nature. Experiments 3 and 4 then further investigated the role of visual processes in forward and backward recall using dynamic visual noise (DVN). In Experiment 3, DVN was presented during encoding of information to be remembered and had no effect upon performance. However, in Experiment 4, it was presented during the recall phase, and the results provided evidence of a role for visual imagery in backward digit recall. These results were replicated in Experiment 5, in which the same list length was used for forward and backward recall tasks. The findings are discussed in terms of both theoretical and practical implications.

Science educators' perceptions of problems facing science education: A report of five surveys

NASA Astrophysics Data System (ADS)

Gallagher, James Joseph; Yager, Robert E.

Five groups of science educators representing faculty at graduate institutions, graduate students, teachers, supervisors, and leadership conferees were surveyed concerning their perceptions of current problems facing science education. A total of 144 participants provided an average of 4.7 responses. The responses were tabulated using an emergent set of categories that resulted in six major groupings, i.e. conceptual, organizational, teacher; related, student-related, university, and societal. The category with the most problems identified was in the area of conceptual problems. University related problems and organizational problems were the next two most frequently mentioned categories for problems. Specific problems in all categories most often cited include the following:1confusion and uncertainty in goals and objectives;2lack of vision and leadership in schools and universities;3absence of a theoretical base for science education;4poor quality teacher education programs;5inappropriate avenues for continuing education of teachers; limited dialogue between researchers and practitioners; declining enrollments; poor quality teaching and counseling; insufficient programs in science for the wide spectrum of students; and public and parental apathy towards science.

A Hybrid Backward-Forward Iterative Model for Improving Capacity Building of Earth Observations for Sustainable Societal Application

NASA Astrophysics Data System (ADS)

Hossain, F.; Iqbal, N.; Lee, H.; Muhammad, A.

2015-12-01

When it comes to building durable capacity for implementing state of the art technology and earth observation (EO) data for improved decision making, it has been long recognized that a unidirectional approach (from research to application) often does not work. Co-design of capacity building effort has recently been recommended as a better alternative. This approach is a two-way street where scientists and stakeholders engage intimately along the entire chain of actions from design of research experiments to packaging of decision making tools and each party provides an equal amount of input. Scientists execute research experiments based on boundary conditions and outputs that are defined as tangible by stakeholders for decision making. On the other hand, decision making tools are packaged by stakeholders with scientists ensuring the application-specific science is relevant. In this talk, we will overview one such iterative capacity building approach that we have implemented for gravimetry-based satellite (GRACE) EO data for improved groundwater management in Pakistan. We call our approach a hybrid approach where the initial step is a forward model involving a conventional short-term (3 day) capacity building workshop in the stakeholder environment addressing a very large audience. In this forward model, the net is cast wide to 'shortlist' a set of highly motivated stakeholder agency staffs who are then engaged more directly in 1-1 training. In the next step (the backward model), these short listed staffs are then brought back in the research environment of the scientists (supply) for 1-1 and long-term (6 months) intense brainstorming, training, and design of decision making tools. The advantage of this backward model is that it allows for a much better understanding for scientists of the ground conditions and hurdles of making a EO-based scientific innovation work for a specific decision making problem that is otherwise fundamentally impossible in conventional

The Screening Test for Emotional Problems-Parent Report (STEP-P): Studies of Reliability and Validity

ERIC Educational Resources Information Center

Erford, Bradley T.; Alsamadi, Silvana C.

2012-01-01

Score reliability and validity of parent responses concerning their 10- to 17-year-old students were analyzed using the Screening Test for Emotional Problems-Parent Report (STEP-P), which assesses a variety of emotional problems classified under the Individuals with Disabilities Education Improvement Act. Score reliability, convergent, and…

The Effect of Gender on the Construction of Backward Inferences

ERIC Educational Resources Information Center

Cakir, Ozler

2008-01-01

The main objective in the present study is to examine the effect of gender on primary school students' construction of elaborative backward inferences during text processing. A total of 333 children, aged 10-11 years (n = 158 girls and 175 boys) participated in the study. Each participant completed a backward inference test. The results indicate…

Potential interoperability problems facing multi-site radiation oncology centers in The Netherlands

NASA Astrophysics Data System (ADS)

Scheurleer, J.; Koken, Ph; Wessel, R.

2014-03-01

Aim: To identify potential interoperability problems facing multi-site Radiation Oncology (RO) departments in the Netherlands and solutions for unambiguous multi-system workflows. Specific challenges confronting the RO department of VUmc (RO-VUmc), which is soon to open a satellite department, were characterized. Methods: A nationwide questionnaire survey was conducted to identify possible interoperability problems and solutions. Further detailed information was obtained by in-depth interviews at 3 Dutch RO institutes that already operate in more than one site. Results: The survey had a 100% response rate (n=21). Altogether 95 interoperability problems were described. Most reported problems were on a strategic and semantic level. The majority were DICOM(-RT) and HL7 related (n=65), primarily between treatment planning and verification systems or between departmental and hospital systems. Seven were identified as being relevant for RO-VUmc. Departments have overcome interoperability problems with their own, or with tailor-made vendor solutions. There was little knowledge about or utilization of solutions developed by Integrating the Healthcare Enterprise Radiation Oncology (IHE-RO). Conclusions: Although interoperability problems are still common, solutions have been identified. Awareness of IHE-RO needs to be raised. No major new interoperability problems are predicted as RO-VUmc develops into a multi-site department.

The effect of repeated bouts of backward walking on physiologic efficiency.

PubMed

Childs, John D; Gantt, Christy; Higgins, Dan; Papazis, Janet A; Franklin, Ronald; Metzler, Terri; Underwood, Frank B

2002-08-01

Previous studies have demonstrated an increased energy expenditure with novel tasks. With practice, the energy cost decreases as the body more efficiently recruits motor units. This study examined whether one becomes more efficient after repeated bouts of backward walking. The subjects were 7 healthy subjects between the ages of 23 and 49 years. A backward walking speed was calculated to elicit a VO(2) equal to 60% of the VO(2)max. There were 18 training sessions at the prescribed walking speed 3 d x wk(-1) for 20 min x d(-1). The backward walking speed required to elicit a fixed VO(2) increased between weeks 4 and 6 of the training period. This finding suggests that backward walking is indeed a novel task and that motor learning occurs as a result of practice, leading to a more efficient recruitment of motor units.

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.

Using Computer Output as a Vehicle for Self-Directed Study of Financial Theory: The Art of Teaching Backwards

ERIC Educational Resources Information Center

Campbell, Robert D.

2017-01-01

This paper presents an example of an approach to teaching financial theory at the college and post-graduate levels that I call "teaching backwards". In the more traditional approach, instructors begin by explaining financial theory, then proceed to give examples of the way this theory can be applied to a business problem, structuring…

Anticipatory postural adjustments contribute to age-related changes in compensatory steps associated with unilateral perturbations.

PubMed

Hyodo, Masaki; Saito, Mayumi; Ushiba, Junichi; Tomita, Yutaka; Minami, Mihoko; Masakado, Yoshihisa

2012-07-01

Compensatory steps are essential for preventing falls following perturbations. This study aimed to explore age-related changes in compensatory steps to unilateral perturbations, specifically in terms of whether anticipatory postural adjustments (APAs) play a role in stabilizing lateral balance. Five young and five elderly male adults participated. The split-belt treadmill was used to provide bi- and unilateral perturbations, as forward or backward transitions, applied 10 times in random order. Backward steps evoked by unilateral forward perturbations were evaluated. We measured temporal characteristics, mediolateral (ML) center of mass (COM) motion, and ML step length of compensatory steps. Compensatory steps to unexpected perturbations showed delayed onset of foot-off (FO) and expanded lateral swing length in elderly compared to young subjects. Differences in COM motions and step width arose related to APAs. Elderly subjects showing APAs exhibited no significant differences in ML COM, ML COM velocity, or ML swing length compared to young subjects. However, elderly subjects without APAs showed significant changes toward instability in these parameters. The fact that APAs play a notable role, particularly in the elderly, in stability offers a new insight into preventing falls. However, APAs occurred in 29% of the steps of young and 35% of the steps of elderly subjects. If the occurrence of APAs in elderly people in response to compensatory steps was more frequent, fall risk would be reduced. Further studies, particularly into APA frequency, might contribute to improved intervention to prevent falls. Copyright © 2012 Elsevier B.V. All rights reserved.

Interlayer Crosstalk Reduction by Controlling Backward Reflectivity in Multilayer Optical Discs

NASA Astrophysics Data System (ADS)

Ushiyama, Junko; Miyauchi, Yasushi; Shintani, Toshimichi; Sugiyama, Toshinori; Miyamoto, Harukazu; Kurokawa, Takahiro

2008-05-01

A method is proposed to reduce interlayer crosstalk in multilayer optical discs by controlling backward reflectivity of information layers, which can lead to wider tolerances of disc fabrication accuracy. Reduction of the backward reflectivity reduces the signal from the ghost spot even if thicknesses of spacer layers are equal. Experimental results showed that the ratio of the signals obtained by the readout spot and the ghost spot is less by about one order for a disc with controlled backward reflectivity than for a conventional disc. A rough estimate of the crosstalk caused by the ghost spot agrees qualitatively with the experimental results.

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.

A causal relationship between face-patch activity and face-detection behavior.

PubMed

Sadagopan, Srivatsun; Zarco, Wilbert; Freiwald, Winrich A

2017-04-04

The primate brain contains distinct areas densely populated by face-selective neurons. One of these, face-patch ML, contains neurons selective for contrast relationships between face parts. Such contrast-relationships can serve as powerful heuristics for face detection. However, it is unknown whether neurons with such selectivity actually support face-detection behavior. Here, we devised a naturalistic face-detection task and combined it with fMRI-guided pharmacological inactivation of ML to test whether ML is of critical importance for real-world face detection. We found that inactivation of ML impairs face detection. The effect was anatomically specific, as inactivation of areas outside ML did not affect face detection, and it was categorically specific, as inactivation of ML impaired face detection while sparing body and object detection. These results establish that ML function is crucial for detection of faces in natural scenes, performing a critical first step on which other face processing operations can build.

The Effect of Syntactic Constraints on the Processing of Backwards Anaphora

ERIC Educational Resources Information Center

Kazanina, Nina; Lau, Ellen F.; Lieberman, Moti; Yoshida, Masaya; Phillips, Colin

2007-01-01

This article presents three studies that investigate when syntactic constraints become available during the processing of long-distance backwards pronominal dependencies ("backwards anaphora" or "cataphora"). Earlier work demonstrated that in such structures the parser initiates an active search for an antecedent for a pronoun, leading to gender…

The amygdala is involved in affective priming effect for fearful faces.

PubMed

Yang, J; Cao, Z; Xu, X; Chen, G

2012-10-01

The object of this study was to investigate whether the amygdala is involved in affective priming effect after stimuli are encoded unconsciously and consciously. During the encoding phase, each masked face (fearful or neutral) was presented to participants six times for 17ms each, using a backward masking paradigm. During the retrieval phase, participants made a fearful/neutral judgment for each face. Half of the faces had the same valence as that seen during encoding (congruent condition) and the other half did not (incongruent condition). Participants were divided into unaware and aware groups based on their subjective and objective awareness assessments. The fMRI results showed that during encoding, the amygdala elicited stronger activation for fearful faces than neutral faces but differed in the hemisphere according to the awareness level. During retrieval, the amygdala showed a significant repetition priming effect, with the congruent faces producing less activation than the incongruent faces, especially for fearful faces. These data suggest that the amygdala is important in unconscious retrieving of memories for emotional faces whether they are encoded consciously or unconsciously. Copyright © 2012 Elsevier Inc. All rights reserved.

Memory and time: Backward and forward telescoping in Alzheimer's disease.

PubMed

El Haj, Mohamad; Janssen, Steve M J; Antoine, Pascal

2017-10-01

Backward and forward telescoping are opposite timing biases. The former refers to misattributing events to earlier dates, whereas the latter refers to misattributing events to later dates. The present study investigated both biases in participants with Alzheimer's Disease (AD) and healthy older adults, matched on age, sex, and education level. Participants were asked to recall the years when five remote and five recent public events had occurred. They were also assessed with a cognitive and clinical battery that included a context memory task on which they had to associate letters and locations. Results showed backward telescoping for recent events and forward telescoping for remote events in AD participants and older adults. Furthermore, poorer context recall was observed in AD participants and older adults displaying backward telescoping than in those displaying forward telescoping. These findings suggest an association between the amount of contextual information recalled and the direction of the timing bias. Backward telescoping can be associated with deficiencies in retrieving context characteristics of events, which have been associated with retrograde amnesia and pathological changes to the hippocampus in AD. Copyright © 2017 Elsevier Inc. All rights reserved.

Current-induced modulation of backward spin-waves in metallic microstructures

NASA Astrophysics Data System (ADS)

Sato, Nana; Lee, Seo-Won; Lee, Kyung-Jin; Sekiguchi, Koji

2017-03-01

We performed a propagating spin-wave spectroscopy for backward spin-waves in ferromagnetic metallic microstructures in the presence of electric-current. Even with the smaller current injection of 5× {{10}10} A m-2 into ferromagnetic microwires, the backward spin-waves exhibit a gigantic 200 MHz frequency shift and a 15% amplitude change, showing 60 times larger modulation compared to previous reports. Systematic experiments by measuring dependences on a film thickness of mirowire, on the wave-vector of spin-wave, and on the magnitude of bias field, we revealed that for the backward spin-waves a distribution of internal magnetic field generated by electric-current efficiently modulates the frequency and amplitude of spin-waves. The gigantic frequency and amplitude changes were reproduced by a micromagnetics simulation, predicting that the current-injection of 5× {{10}11} A m-2 allows 3 GHz frequency shift. The effective coupling between electric-current and backward spin-waves has a potential to build up a logic control method which encodes signals into the phase and amplitude of spin-waves. The metallic magnonics cooperating with electronics could suggest highly integrated magnonic circuits both in Boolean and non-Boolean principles.

Moving backwards, moving forward: the experiences of older Filipino migrants adjusting to life in New Zealand.

PubMed

Montayre, Jed; Neville, Stephen; Holroyd, Eleanor

2017-12-01

To explore the experiences of older Filipino migrants adjusting to living permanently in New Zealand. The qualitative descriptive approach taken in this study involved 17 individual face-to-face interviews of older Filipino migrants in New Zealand. Three main themes emerged from the data. The first theme was "moving backwards and moving forward", which described how these older Filipino migrants adjusted to challenges they experienced with migration. The second theme was "engaging with health services" and presented challenges relating to the New Zealand healthcare system, including a lack of knowledge of the nature of health services, language barriers, and differences in cultural views. The third theme, "new-found home", highlighted establishing a Filipino identity in New Zealand and adjusting to the challenges of relocation. Adjustment to life in New Zealand for these older Filipino migrants meant starting over again by building new values through learning the basics and then moving forward from there.

Moving backwards, moving forward: the experiences of older Filipino migrants adjusting to life in New Zealand

PubMed Central

Montayre, Jed; Neville, Stephen; Holroyd, Eleanor

2017-01-01

ABSTRACT Purpose: To explore the experiences of older Filipino migrants adjusting to living permanently in New Zealand. Method: The qualitative descriptive approach taken in this study involved 17 individual face-to-face interviews of older Filipino migrants in New Zealand. Results: Three main themes emerged from the data. The first theme was “moving backwards and moving forward”, which described how these older Filipino migrants adjusted to challenges they experienced with migration. The second theme was “engaging with health services” and presented challenges relating to the New Zealand healthcare system, including a lack of knowledge of the nature of health services, language barriers, and differences in cultural views. The third theme, “new-found home”, highlighted establishing a Filipino identity in New Zealand and adjusting to the challenges of relocation. Conclusion: Adjustment to life in New Zealand for these older Filipino migrants meant starting over again by building new values through learning the basics and then moving forward from there. PMID:28705087

Development of face recognition: Dynamic causal modelling of MEG data.

PubMed

He, Wei; Johnson, Blake W

2018-04-01

Electrophysiological studies of adults indicate that brain activity is enhanced during viewing of repeated faces, at a latency of about 250 ms after the onset of the face (M250/N250). The present study aimed to determine if this effect was also present in preschool-aged children, whose brain activity was measured in a custom-sized pediatric MEG system. The results showed that, unlike adults, face repetition did not show any significant modulation of M250 amplitude in children; however children's M250 latencies were significantly faster for repeated than non-repeated faces. Dynamic causal modelling (DCM) of the M250 in both age groups tested the effects of face repetition within the core face network including the occipital face area (OFA), the fusiform face area (FFA), and the superior temporal sulcus (STS). DCM revealed that repetition of identical faces altered both forward and backward connections in children and adults; however the modulations involved inputs to both FFA and OFA in adults but only to OFA in children. These findings suggest that the amplitude-insensitivity of the immature M250 may be due to a weaker connection between the FFA and lower visual areas. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Excitatory motor neurons are local oscillators for backward locomotion

PubMed Central

Guan, Sihui Asuka; Fouad, Anthony D; Meng, Jun; Kawano, Taizo; Huang, Yung-Chi; Li, Yi; Alcaire, Salvador; Hung, Wesley; Lu, Yangning; Qi, Yingchuan Billy; Jin, Yishi; Alkema, Mark; Fang-Yen, Christopher

2018-01-01

Cell- or network-driven oscillators underlie motor rhythmicity. The identity of C. elegans oscillators remains unknown. Through cell ablation, electrophysiology, and calcium imaging, we show: (1) forward and backward locomotion is driven by different oscillators; (2) the cholinergic and excitatory A-class motor neurons exhibit intrinsic and oscillatory activity that is sufficient to drive backward locomotion in the absence of premotor interneurons; (3) the UNC-2 P/Q/N high-voltage-activated calcium current underlies A motor neuron’s oscillation; (4) descending premotor interneurons AVA, via an evolutionarily conserved, mixed gap junction and chemical synapse configuration, exert state-dependent inhibition and potentiation of A motor neuron’s intrinsic activity to regulate backward locomotion. Thus, motor neurons themselves derive rhythms, which are dually regulated by the descending interneurons to control the reversal motor state. These and previous findings exemplify compression: essential circuit properties are conserved but executed by fewer numbers and layers of neurons in a small locomotor network. PMID:29360035

Excitatory motor neurons are local oscillators for backward locomotion.

PubMed

Gao, Shangbang; Guan, Sihui Asuka; Fouad, Anthony D; Meng, Jun; Kawano, Taizo; Huang, Yung-Chi; Li, Yi; Alcaire, Salvador; Hung, Wesley; Lu, Yangning; Qi, Yingchuan Billy; Jin, Yishi; Alkema, Mark; Fang-Yen, Christopher; Zhen, Mei

2018-01-23

Cell- or network-driven oscillators underlie motor rhythmicity. The identity of C. elegans oscillators remains unknown. Through cell ablation, electrophysiology, and calcium imaging, we show: (1) forward and backward locomotion is driven by different oscillators; (2) the cholinergic and excitatory A-class motor neurons exhibit intrinsic and oscillatory activity that is sufficient to drive backward locomotion in the absence of premotor interneurons; (3) the UNC-2 P/Q/N high-voltage-activated calcium current underlies A motor neuron's oscillation; (4) descending premotor interneurons AVA, via an evolutionarily conserved, mixed gap junction and chemical synapse configuration, exert state-dependent inhibition and potentiation of A motor neuron's intrinsic activity to regulate backward locomotion. Thus, motor neurons themselves derive rhythms, which are dually regulated by the descending interneurons to control the reversal motor state. These and previous findings exemplify compression: essential circuit properties are conserved but executed by fewer numbers and layers of neurons in a small locomotor network. © 2017, Gao et al.

Static Longitudinal Stability of a Rocket Vehicle Having a Rear-Facing Step Ahead of the Stabilizing Fins

NASA Technical Reports Server (NTRS)

Keynton, Robert J.

1961-01-01

Tests were conducted at Mach numbers of 3.96 and 4.65 in the Langley Unitary Plan wind tunnel to determine the static longitudinal stability characteristics of a fin-stabilized rocket-vehicle configuration which had a rearward facing step located upstream of the fins. Two fin sizes and planforms, a delta and a clipped delta, were tested. The angle of attack was varied from 6 deg to -6 deg and the Reynolds number based on model 6 length was about 10 x 10. The configuration with the larger fins (clipped delta) had a center of pressure slightly rearward of and an initial normal-force-curve slope slightly higher than that of the configuration with the smaller fins (delta) as would be expected. Calculations of the stability parameters gave a slightly lower initial slope of the normal-force curve than measured data, probably because of boundary-layer separation ahead of the step. The calculated center of pressure agreed well with the measured data. Measured and calculated increments in the initial slope of the normal-force curve and in the center of pressure, due to changing fins, were in excellent agreement indicating that separated flow downstream of the step did not influence flow over the fins. This result was consistent with data from schlieren photographs.

Managing pets with behavior problems: realistic expectations.

PubMed

Horwitz, Debra F

2008-09-01

Management solutions offer a useful tool for owners faced with behavior issues in their pets. In some cases management will improve the behavior and allow control. In other situations it may be only the first step in treatment. By offering management solutions, veterinarians can help owners with problem pets and begin the road to recovery.

A JPEG backward-compatible HDR image compression

NASA Astrophysics Data System (ADS)

Korshunov, Pavel; Ebrahimi, Touradj

2012-10-01

High Dynamic Range (HDR) imaging is expected to become one of the technologies that could shape next generation of consumer digital photography. Manufacturers are rolling out cameras and displays capable of capturing and rendering HDR images. The popularity and full public adoption of HDR content is however hindered by the lack of standards in evaluation of quality, file formats, and compression, as well as large legacy base of Low Dynamic Range (LDR) displays that are unable to render HDR. To facilitate wide spread of HDR usage, the backward compatibility of HDR technology with commonly used legacy image storage, rendering, and compression is necessary. Although many tone-mapping algorithms were developed for generating viewable LDR images from HDR content, there is no consensus on which algorithm to use and under which conditions. This paper, via a series of subjective evaluations, demonstrates the dependency of perceived quality of the tone-mapped LDR images on environmental parameters and image content. Based on the results of subjective tests, it proposes to extend JPEG file format, as the most popular image format, in a backward compatible manner to also deal with HDR pictures. To this end, the paper provides an architecture to achieve such backward compatibility with JPEG and demonstrates efficiency of a simple implementation of this framework when compared to the state of the art HDR image compression.

Hidden asymmetry and forward-backward correlations

NASA Astrophysics Data System (ADS)

Bialas, A.; Zalewski, K.

2010-09-01

A model-independent method of studying the forward-backward correlations in symmetric high-energy processes is developed. The method allows a systematic study of the properties of various particle sources and allows one to uncover asymmetric structures hidden in symmetric hadron-hadron and nucleus-nucleus inelastic reactions.

Asymptotic (h tending to infinity) absolute stability for BDFs applied to stiff differential equations. [Backward Differentiation Formulas

NASA Technical Reports Server (NTRS)

Krogh, F. T.; Stewart, K.

1984-01-01

Methods based on backward differentiation formulas (BDFs) for solving stiff differential equations require iterating to approximate the solution of the corrector equation on each step. One hope for reducing the cost of this is to make do with iteration matrices that are known to have errors and to do no more iterations than are necessary to maintain the stability of the method. This paper, following work by Klopfenstein, examines the effect of errors in the iteration matrix on the stability of the method. Application of the results to an algorithm is discussed briefly.

[Backward flow signal in the left atrium studied by Doppler echocardiography. Differentiation from mitral regurgitation].

PubMed

Nagoshi, H; Miyairi, M; Asato, T; Naito, M; Honda, M

1983-03-01

A backward flow signal in the left atrium masquerading as mitral regurgitation was studied by a pulsed Doppler method. The subjects consisted of 20 normal volunteers, 12 cases with mitral valve prolapse syndrome, five cases with rheumatic mitral regurgitation, five cases with lone atrial fibrillation, four cases with asymmetric septal hypertrophy and three cases with the Björk-Shiley tilting disc valve in the mitral position. In two-dimensional echocardiography combined with pulsed Doppler method, a Doppler signal was recorded by locating a sample volume in the left atrium. In all of the cases with mitral valve prolapse syndrome and the cases with the prosthetic valve as well as in all of the normal subjects, the backward flow signal was observed in the left atrium. In three cases with mitral valve prolapse syndrome, it was differentiated from a transvalvular regurgitant flow signal. In all cases with rheumatic mitral regurgitation, the backward flow signal was masked by a turbulent flow signal representing regurgitation. In cases with mitral stenosis, the backward flow signal was scarcely recognized. The duration of the backward flow signal had no relationship with heart rate. The histogram of incidence on the scale of R-R interval revealed normal distribution with a mean value of 0.24 sec (+/- 0.09 sec). Therefore, in cases with tachycardia, the backward flow signal was seen throughout systole. The peak backward flow velocity of Doppler signals was correlated (r = 0.71, p less than 0.01) with the peak forward flow velocity in diastole. The faint backward flow signal seen in cases with mitral stenosis and post-extrasystolic potentiation of the backward flow signal were suggestive of the foregoing relationship. The mechanism producing the backward flow was postulated as a water hammer phenomenon caused by closure of the mitral valve.

High-speed video analysis of forward and backward spattered blood droplets.

PubMed

Comiskey, P M; Yarin, A L; Attinger, D

2017-07-01

High-speed videos of blood spatter due to a gunshot taken by the Ames Laboratory Midwest Forensics Resource Center (MFRC) [1] are analyzed. The videos used in this analysis were focused on a variety of targets hit by a bullet which caused either forward, backward, or both types of blood spatter. The analysis process utilized particle image velocimetry (PIV) and particle analysis software to measure drop velocities as well as the distributions of the number of droplets and their respective side view area. The results of this analysis revealed that the maximal velocity in the forward spatter can be about 47±5m/s and for the backward spatter - about 24±8m/s. Moreover, our measurements indicate that the number of droplets produced is larger in forward spatter than it is in backward spatter. In the forward and backward spatter the droplet area in the side-view images is approximately the same. The upper angles of the close-to-cone domain in which droplets are issued in forward and backward spatter are, 27±9° and 57±7°, respectively, whereas the lower angles of the close-to-cone domain are 28±12° and 30±18°, respectively. The inclination angle of the bullet as it penetrates the target is seen to play a large role in the directional preference of the spattered blood. Also, muzzle gases, bullet impact angle, as well as the aerodynamic wake of the bullet are seen to greatly influence the flight of the droplets. The intent of this investigation is to provide a quantitative basis for current and future research on bloodstain pattern analysis (BPA) of either forward or backward blood spatter due to a gunshot. Published by Elsevier B.V.

Backward spoof surface wave in plasmonic metamaterial of ultrathin metallic structure.

PubMed

Liu, Xiaoyong; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian

2016-02-04

Backward wave with anti-parallel phase and group velocities is one of the basic properties associated with negative refraction and sub-diffraction image that have attracted considerable interest in the context of photonic metamaterials. It has been predicted theoretically that some plasmonic structures can also support backward wave propagation of surface plasmon polaritons (SPPs), however direct experimental demonstration has not been reported, to the best of our knowledge. In this paper, a specially designed plasmonic metamaterial of corrugated metallic strip has been proposed that can support backward spoof SPP wave propagation. The dispersion analysis, the full electromagnetic field simulation and the transmission measurement of the plasmonic metamaterial waveguide have clearly validated the backward wave propagation with dispersion relation possessing negative slope and opposite directions of group and phase velocities. As a further verification and application, a contra-directional coupler is designed and tested that can route the microwave signal to opposite terminals at different operating frequencies, indicating new application opportunities of plasmonic metamaterial in integrated functional devices and circuits for microwave and terahertz radiation.

Unconstrained steps of myosin VI appear longest among known molecular motors.

PubMed

Ali, M Yusuf; Homma, Kazuaki; Iwane, Atsuko Hikikoshi; Adachi, Kengo; Itoh, Hiroyasu; Kinosita, Kazuhiko; Yanagida, Toshio; Ikebe, Mitsuo

2004-06-01

Myosin VI is a two-headed molecular motor that moves along an actin filament in the direction opposite to most other myosins. Previously, a single myosin VI molecule has been shown to proceed with steps that are large compared to its neck size: either it walks by somehow extending its neck or one head slides along actin for a long distance before the other head lands. To inquire into these and other possible mechanism of motility, we suspended an actin filament between two plastic beads, and let a single myosin VI molecule carrying a bead duplex move along the actin. This configuration, unlike previous studies, allows unconstrained rotation of myosin VI around the right-handed double helix of actin. Myosin VI moved almost straight or as a right-handed spiral with a pitch of several micrometers, indicating that the molecule walks with strides slightly longer than the actin helical repeat of 36 nm. The large steps without much rotation suggest kinesin-type walking with extended and flexible necks, but how to move forward with flexible necks, even under a backward load, is not clear. As an answer, we propose that a conformational change in the lifted head would facilitate landing on a forward, rather than backward, site. This mechanism may underlie stepping of all two-headed molecular motors including kinesin and myosin V.

Are the Editors faced with e-problems performing their duties and responsibilities satisfactorily?

PubMed

Ali Jawaid, Shaukat; Jawaid, Masood

2013-09-01

Astonishing revolution in information technology, developments in electronic publishing and availability of manuscript management software's has provided lot of facilities to authors, reviewers as well as editors but it has also given birth to lot of e-problems. This communication highlights some of these e-problems besides discussing the manuscript management system practiced by Pakistan Journal of Medical Sciences through modified Open Journal System. It also cautions the editors of small journals faced with financial and human resource constraints to keep themselves abreast of all these developments, go for automation in e publishing gradually as all the stake holders i.e. authors, reviewers and office management staff learns these and become used to it.

Survey of projected growth and problems facing air transportation, 1975 - 1985

NASA Technical Reports Server (NTRS)

Williams, L. J.; Wilson, A.

1975-01-01

Results are presented of a survey conducted to determine the current opinion of people working in air transportation demand forecasting on the future of air transportation over the next ten years. In particular, the survey included questions on future demand growth, load factor, fuel prices, introduction date for the next new aircraft, the priorities of problems facing air transportation, and the probability of a substantial change in air transportation regulation. The survey participants included: airlines, manufacturers, universities, government agencies, and other organizations (financial institutions, private research companies, etc.). The results are shown for the average responses within the organization represented as well as the overall averages.

The most common problem facing by the maintenance department: A case Study between Universiti Tun Hussein Onn Malaysia (UTHM) and Universiti Teknologi Malaysia (UTM)

NASA Astrophysics Data System (ADS)

Norazam Yasin, Mohd; Mohamad Zin, Rosli; Halid Abdullah, Abd; Shafiq Mahmad, Muhammad; Fikri Hasmori, Muhammad

2017-11-01

From time to time, the maintenance works become more challenging due to construction of new building and also aging of the existing buildings. University buildings without any exception require proper maintenance services to support their function requirements and this can be considered as major responsibilities to be fulfilled by the maintenance department in the universities. Maintenance department specifically will face various kinds of problems in their operation works and thus this might influence the maintenance work operations itself. This study purposely to identify the common problem facing by the maintenance department and also to examine the current status of the maintenance department. In addition, this study would also propose any suitable approach that could be implemented to overcome the problem facing by the maintenance department. To achieve the objectives of this study, a combination of deep literature study and carrying out a survey is necessary. Literature study aimed to obtain deeper information about this study, meanwhile a survey aimed at identifying the common problem facing by the maintenance department and also to provide the information of the maintenance department’s organization. Several methods will be used in analyzing the data obtained through the survey, including Microsoft Office Excel and also using mean index formula. This study has identified three categories of problem in the maintenance department, which are management problems, human resource problem, and technical problems. Following the findings, several solutions being proposed which can be implemented as the solution to the problem facing. These suggestions have the potential to improve the maintenance department work efficiency, thus could help to increase the department productivity.

Assessment of turbulent models for scramjet flowfields

NASA Technical Reports Server (NTRS)

Sindir, M. M.; Harsha, P. T.

1982-01-01

The behavior of several turbulence models applied to the prediction of scramjet combustor flows is described. These models include the basic two equation model, the multiple dissipation length scale variant of the two equation model, and the algebraic stress model (ASM). Predictions were made of planar backward facing step flows and axisymmetric sudden expansion flows using each of these approaches. The formulation of each of these models are discussed, and the application of the different approaches to supersonic flows is described. A modified version of the ASM is found to provide the best prediction of the planar backward facing step flow in the region near the recirculation zone, while the basic ASM provides the best results downstream of the recirculation. Aspects of the interaction of numerica modeling and turbulences modeling as they affect the assessment of turbulence models are discussed.

Single-layer HDR video coding with SDR backward compatibility

NASA Astrophysics Data System (ADS)

Lasserre, S.; François, E.; Le Léannec, F.; Touzé, D.

2016-09-01

The migration from High Definition (HD) TV to Ultra High Definition (UHD) is already underway. In addition to an increase of picture spatial resolution, UHD will bring more color and higher contrast by introducing Wide Color Gamut (WCG) and High Dynamic Range (HDR) video. As both Standard Dynamic Range (SDR) and HDR devices will coexist in the ecosystem, the transition from Standard Dynamic Range (SDR) to HDR will require distribution solutions supporting some level of backward compatibility. This paper presents a new HDR content distribution scheme, named SL-HDR1, using a single layer codec design and providing SDR compatibility. The solution is based on a pre-encoding HDR-to-SDR conversion, generating a backward compatible SDR video, with side dynamic metadata. The resulting SDR video is then compressed, distributed and decoded using standard-compliant decoders (e.g. HEVC Main 10 compliant). The decoded SDR video can be directly rendered on SDR displays without adaptation. Dynamic metadata of limited size are generated by the pre-processing and used to reconstruct the HDR signal from the decoded SDR video, using a post-processing that is the functional inverse of the pre-processing. Both HDR quality and artistic intent are preserved. Pre- and post-processing are applied independently per picture, do not involve any inter-pixel dependency, and are codec agnostic. Compression performance, and SDR quality are shown to be solidly improved compared to the non-backward and backward-compatible approaches, respectively using the Perceptual Quantization (PQ) and Hybrid Log Gamma (HLG) Opto-Electronic Transfer Functions (OETF).

Manual wheelchair propulsion by people with hemiplegia: within-participant comparisons of forward versus backward techniques.

PubMed

Charbonneau, Rebecca; Kirby, R Lee; Thompson, Kara

2013-09-01

To test the hypotheses that people with hemiplegia using arms and legs to propel their wheelchairs perform better backward than forward and prefer the backward direction. Within-participant cross-sectional design. Manual wheelchair users (N=18) with hemiplegia caused by stroke, a sample of convenience. Rehabilitation center. Participants each performed 9 skills from the Wheelchair Skills Test (WST 4.1)-4 low-rolling-resistance skills (rolls 10m, turns 90° while moving, rolls 2m across 5° side slope, descends 5cm level change) and 5 high-rolling-resistance skills (ascends 5° incline, rolls 2m on soft surface, gets over 15-cm pothole, gets over 2-cm threshold, ascends 5cm level change)-in both the forward and backward directions, in random order. Total percentage capacity scores from the modified WST 4.1, success rates for individual skills, and responses from an orally administered questionnaire regarding direction preferences. The mean ± SD total WST 4.1 capacity scores were 53%±26% in the forward direction and 76%±30% in the backward direction (P<.001). For the 4 low-rolling-resistance skills, there were no clinically significant differences (≥20%) between forward and backward success rates. For the 5 high-rolling-resistance skills, the success rates were 33% to 50% higher in the backward direction. Participants preferred the forward direction for low-rolling-resistance skills and the backward direction for high-rolling-resistance skills. Wheelchair skills that involve high rolling resistance are performed more successfully in the backward than the forward direction, and participants prefer the backward direction for such skills. These findings have implications for wheelchair selection and skills training. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

In search of evidence-based plastic surgery: the problems faced by the specialty.

PubMed

Offer, G J; Perks, A G

2000-07-01

Recently, there has been significant interest both from government and medical practitioners in the discipline of evidence-based medicine. In this article we discuss the problems faced by the plastic surgeon when trying to ensure that practice is evidence-based and highlight some of the reasons behind these difficulties. With the rapid growth of the Internet we also outline its use to access high quality information for the plastic surgeon. Copyright 2000 The British Association of Plastic Surgeons.

Repetitively Pulsed Backward-Wave Oscillator Investigations

DTIC Science & Technology

1994-03-31

Sinus-6 High Power BWO Experiments and Theory .................. 6 A . B W O physics .............................................................. 6...B. Experiments with high power output of BWO .............................. 8 Section III. Long Pulse Vacuum BWO Experiments...UNM) has completed its initial phase of research on repetitively pulsed high power backward-wave oscillators (BWOs). The aggressive program that we had

Collaborative Accounting Problem Solving via Group Support Systems in a Face-to-Face versus Distant Learning Environment.

ERIC Educational Resources Information Center

Burke, Jacqueline A.

2001-01-01

Accounting students (n=128) used either face-to-face or distant Group support systems to complete collaborative tasks. Participation and social presence perceptions were significantly higher face to face. Task difficulty did not affect participation in either environment. (Contains 54 references.) (JOW)

Source-receptor matrix calculation with a Lagrangian particle dispersion model in backward mode

NASA Astrophysics Data System (ADS)

Seibert, P.; Frank, A.

2004-01-01

The possibility to calculate linear-source receptor relationships for the transport of atmospheric trace substances with a Lagrangian particle dispersion model (LPDM) running in backward mode is shown and presented with many tests and examples. This mode requires only minor modifications of the forward LPDM. The derivation includes the action of sources and of any first-order processes (transformation with prescribed rates, dry and wet deposition, radioactive decay, etc.). The backward mode is computationally advantageous if the number of receptors is less than the number of sources considered. The combination of an LPDM with the backward (adjoint) methodology is especially attractive for the application to point measurements, which can be handled without artificial numerical diffusion. Practical hints are provided for source-receptor calculations with different settings, both in forward and backward mode. The equivalence of forward and backward calculations is shown in simple tests for release and sampling of particles, pure wet deposition, pure convective redistribution and realistic transport over a short distance. Furthermore, an application example explaining measurements of Cs-137 in Stockholm as transport from areas contaminated heavily in the Chernobyl disaster is included.

Backward assembly planning with DFA analysis

NASA Technical Reports Server (NTRS)

Lee, Sukhan (Inventor)

1995-01-01

An assembly planning system that operates based on a recursive decomposition of assembly into subassemblies, and analyzes assembly cost in terms of stability, directionality, and manipulability to guide the generation of preferred assembly plans is presented. The planning in this system incorporates the special processes, such as cleaning, testing, labeling, etc. that must occur during the assembly, and handles nonreversible as well as reversible assembly tasks through backward assembly planning. In order to increase the planning efficiency, the system avoids the analysis of decompositions that do not correspond to feasible assembly tasks. This is achieved by grouping and merging those parts that can not be decomposable at the current stage of backward assembly planning due to the requirement of special processes and the constraint of interconnection feasibility. The invention includes methods of evaluating assembly cost in terms of the number of fixtures (or holding devices) and reorientations required for assembly, through the analysis of stability, directionality, and manipulability. All these factors are used in defining cost and heuristic functions for an AO* search for an optimal plan.

Backward assembly planning with DFA analysis

NASA Technical Reports Server (NTRS)

Lee, Sukhan (Inventor)

1992-01-01

An assembly planning system that operates based on a recursive decomposition of assembly into subassemblies is presented. The planning system analyzes assembly cost in terms of stability, directionality, and manipulability to guide the generation of preferred assembly plans. The planning in this system incorporates the special processes, such as cleaning, testing, labeling, etc., that must occur during the assembly. Additionally, the planning handles nonreversible, as well as reversible, assembly tasks through backward assembly planning. In order to decrease the planning efficiency, the system avoids the analysis of decompositions that do not correspond to feasible assembly tasks. This is achieved by grouping and merging those parts that can not be decomposable at the current stage of backward assembly planning due to the requirement of special processes and the constraint of interconnection feasibility. The invention includes methods of evaluating assembly cost in terms of the number of fixtures (or holding devices) and reorientations required for assembly, through the analysis of stability, directionality, and manipulability. All these factors are used in defining cost and heuristic functions for an AO* search for an optimal plan.

Effects of progressive backward body weight suppoted treadmill training on gait ability in chronic stroke patients: A randomized controlled trial.

PubMed

Kim, Kyung Hun; Lee, Kyoung Bo; Bae, Young-Hyeon; Fong, Shirley S M; Lee, Suk Min

2017-10-23

A stroke patient with hemiplegic gait is generally described as being slow and asymmetric. Body weight-supported treadmill training and backward gait training are recent additions to therapeutic gait trainings that may help improve gait in stroke patient with hemiplegic gait. Therefore, we examined the effect of progressive backward body weight-supported treadmill training on gait in chronic stroke patients with hemiplegic gait. Thirty subjects were divided to the experimental and control groups. The experimental group consisted of 15 patients and underwent progressive backward body weight-supported treadmill training. The control group consisted of 15 patients and underwent general treadmill gait training five times per week, for a total of four weeks. The OptoGait was used to analyze gait kinematics, and the dynamic gait index (DGI) and results of the 6-minute walk test were used as the clinical evaluation indicators. A follow-up test was carried out four weeks later to examine persistence of exercise effects. The experimental group showed statistically significant results in all dependent variables week four compared to the control group. However, until the eighth week, only the dependent variables, of affected step length (ASL), stride length (SL), and DGI differed significantly between the two groups. This study verified that progressive bodyweight-supported treadmill training had a positive influence on the temporospatial characteristics of gait and clinical gait evaluation index in chronic stroke patients.

The Effects of a Secondary Task on Forward and Backward Walking in Parkinson Disease

PubMed Central

Hackney, Madeleine E.; Earhart, Gammon M.

2009-01-01

Background People with Parkinson disease (PD) often fall while multi-tasking or walking backward, unavoidable activities in daily living. Dual tasks involving cognitive demand during gait and unfamiliar motor skills like backward walking could identify those with fall risk, but dual tasking while walking backward has not been examined in those with PD, those who experience Freezing of Gait (FOG), or healthy older controls. Methods Seventy-eight people with PD (mean age = 65.1±9.5 years, Female: 28%) and 74 age- and sex-matched controls (mean age = 65.0±10.0 years, Female: 23%) participated. A computerized walkway measured gait velocity, stride length, swing and stance percent, cadence, heel to heel base of support, functional ambulation profile, and gait asymmetry during forward and backward walking with and without a secondary cognitive task. Results Direction and task effects on walking performance were similar between healthy controls and those with PD. However, those with PD were more affected than controls, and freezers were more affected than non-freezers, by backward walking and dual tasking. Walking backward seemed to impact gait more than dual tasking in those with PD, although the subset of freezers appeared particularly impacted by both challenges. Conclusion People with PD are impaired while performing complex motor and mental tasks simultaneously, which may put them at risk for falling. Those with FOG are more adversely affected by both motor and mental challenges than those without. Evaluation of backward walking while performing a secondary task might be an effective clinical tool to identify locomotor difficulties. PMID:19675121

Ocular forward light scattering and corneal backward light scattering in patients with dry eye.

PubMed

Koh, Shizuka; Maeda, Naoyuki; Ikeda, Chikako; Asonuma, Sanae; Mitamura, Hayato; Oie, Yoshinori; Soma, Takeshi; Tsujikawa, Motokazu; Kawasaki, Satoshi; Nishida, Kohji

2014-09-18

To evaluate ocular forward light scattering and corneal backward light scattering in patients with dry eye. Thirty-five eyes in 35 patients with dry eye and 20 eyes of 20 healthy control subjects were enrolled. The 35 dry eyes were classified into two groups according to whether superficial punctate keratopathy in the central 6-mm corneal zone (cSPK) was present or not. Ocular forward light scattering was quantified with a straylight meter. Corneal backward light scattering from the anterior, middle, and posterior corneal parts was assessed with a corneal densitometry program using the Scheimpflug imaging system. Both dry eye groups had significantly higher intraocular forward light scattering than the control group (both P<0.05). The dry eye group with cSPK had significantly higher values in anterior and total corneal backward light scattering than the other two groups. Moderate positive correlations were observed between the cSPK score and corneal backward light scattering from the anterior cornea (R=0.60, P<0.001) and corneal backward light scattering from the total cornea (R=0.54, P<0.001); however, no correlation was found between cSPK score and ocular forward light scattering (R=0.01, P=0.932). Ocular forward light scattering and corneal backward light scattering from the anterior cornea were greater in dry eyes than in normal eyes. Increased corneal backward light scattering in dry eye at least partially results from cSPK overlying the optical zone. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Backward-stochastic-differential-equation approach to modeling of gene expression

NASA Astrophysics Data System (ADS)

Shamarova, Evelina; Chertovskih, Roman; Ramos, Alexandre F.; Aguiar, Paulo

2017-03-01

In this article, we introduce a backward method to model stochastic gene expression and protein-level dynamics. The protein amount is regarded as a diffusion process and is described by a backward stochastic differential equation (BSDE). Unlike many other SDE techniques proposed in the literature, the BSDE method is backward in time; that is, instead of initial conditions it requires the specification of end-point ("final") conditions, in addition to the model parametrization. To validate our approach we employ Gillespie's stochastic simulation algorithm (SSA) to generate (forward) benchmark data, according to predefined gene network models. Numerical simulations show that the BSDE method is able to correctly infer the protein-level distributions that preceded a known final condition, obtained originally from the forward SSA. This makes the BSDE method a powerful systems biology tool for time-reversed simulations, allowing, for example, the assessment of the biological conditions (e.g., protein concentrations) that preceded an experimentally measured event of interest (e.g., mitosis, apoptosis, etc.).

Backward-stochastic-differential-equation approach to modeling of gene expression.

PubMed

Shamarova, Evelina; Chertovskih, Roman; Ramos, Alexandre F; Aguiar, Paulo

2017-03-01

In this article, we introduce a backward method to model stochastic gene expression and protein-level dynamics. The protein amount is regarded as a diffusion process and is described by a backward stochastic differential equation (BSDE). Unlike many other SDE techniques proposed in the literature, the BSDE method is backward in time; that is, instead of initial conditions it requires the specification of end-point ("final") conditions, in addition to the model parametrization. To validate our approach we employ Gillespie's stochastic simulation algorithm (SSA) to generate (forward) benchmark data, according to predefined gene network models. Numerical simulations show that the BSDE method is able to correctly infer the protein-level distributions that preceded a known final condition, obtained originally from the forward SSA. This makes the BSDE method a powerful systems biology tool for time-reversed simulations, allowing, for example, the assessment of the biological conditions (e.g., protein concentrations) that preceded an experimentally measured event of interest (e.g., mitosis, apoptosis, etc.).

A universal pathway for kinesin stepping.

PubMed

Clancy, Bason E; Behnke-Parks, William M; Andreasson, Johan O L; Rosenfeld, Steven S; Block, Steven M

2011-08-14

Kinesin-1 is an ATP-driven, processive motor that transports cargo along microtubules in a tightly regulated stepping cycle. Efficient gating mechanisms ensure that the sequence of kinetic events proceeds in the proper order, generating a large number of successive reaction cycles. To study gating, we created two mutant constructs with extended neck-linkers and measured their properties using single-molecule optical trapping and ensemble fluorescence techniques. Owing to a reduction in the inter-head tension, the constructs access an otherwise rarely populated conformational state in which both motor heads remain bound to the microtubule. ATP-dependent, processive backstepping and futile hydrolysis were observed under moderate hindering loads. On the basis of measurements, we formulated a comprehensive model for kinesin motion that incorporates reaction pathways for both forward and backward stepping. In addition to inter-head tension, we found that neck-linker orientation is also responsible for ensuring gating in kinesin.

Flow Induced Noise from Turbulent Flow over Steps and Gaps

DTIC Science & Technology

2010-05-04

Wall Jet Facility which is detailed in Figures 2.1 through 2.3. In this facility a Cincinnati Fan variable speed centrifugal fan with model number...the flow over the multiple backward steps considered in this study The following subsections will concentrate on the oil flow visualization performed ...NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Virginia Polytechnic Institute and State University

Future Critical Issues and Problems Facing Technology and Engineering Education in the Commonwealth of Virginia

ERIC Educational Resources Information Center

Katsioloudis, Petros; Moye, Johnny J.

2012-01-01

The purpose of this research was to determine the future critical issues and problems facing the K-12 technology and engineering education profession in the Commonwealth of Virginia. This study was based on the Wicklein nationwide studies (1993a, 2005). Even though this study did not exactly replicate the Wicklein studies--since it was limited to…

Interacting multiple model forward filtering and backward smoothing for maneuvering target tracking

NASA Astrophysics Data System (ADS)

Nandakumaran, N.; Sutharsan, S.; Tharmarasa, R.; Lang, Tom; McDonald, Mike; Kirubarajan, T.

2009-08-01

The Interacting Multiple Model (IMM) estimator has been proven to be effective in tracking agile targets. Smoothing or retrodiction, which uses measurements beyond the current estimation time, provides better estimates of target states. Various methods have been proposed for multiple model smoothing in the literature. In this paper, a new smoothing method, which involves forward filtering followed by backward smoothing while maintaining the fundamental spirit of the IMM, is proposed. The forward filtering is performed using the standard IMM recursion, while the backward smoothing is performed using a novel interacting smoothing recursion. This backward recursion mimics the IMM estimator in the backward direction, where each mode conditioned smoother uses standard Kalman smoothing recursion. Resulting algorithm provides improved but delayed estimates of target states. Simulation studies are performed to demonstrate the improved performance with a maneuvering target scenario. The comparison with existing methods confirms the improved smoothing accuracy. This improvement results from avoiding the augmented state vector used by other algorithms. In addition, the new technique to account for model switching in smoothing is a key in improving the performance.

Olfactory Interference during Inhibitory Backward Pairing in Honey Bees

PubMed Central

Dacher, Matthieu; Smith, Brian H.

2008-01-01

Background Restrained worker honey bees are a valuable model for studying the behavioral and neural bases of olfactory plasticity. The proboscis extension response (PER; the proboscis is the mouthpart of honey bees) is released in response to sucrose stimulation. If sucrose stimulation is preceded one or a few times by an odor (forward pairing), the bee will form a memory for this association, and subsequent presentations of the odor alone are sufficient to elicit the PER. However, backward pairing between the two stimuli (sucrose, then odor) has not been studied to any great extent in bees, although the vertebrate literature indicates that it elicits a form of inhibitory plasticity. Methodology/Principal Findings If hungry bees are fed with sucrose, they will release a long lasting PER; however, this PER can be interrupted if an odor is presented 15 seconds (but not 7 or 30 seconds) after the sucrose (backward pairing). We refer to this previously unreported process as olfactory interference. Bees receiving this 15 second backward pairing show reduced performance after a subsequent single forward pairing (excitatory conditioning) trial. Analysis of the results supported a relationship between olfactory interference and a form of backward pairing-induced inhibitory learning/memory. Injecting the drug cimetidine into the deutocerebrum impaired olfactory interference. Conclusions/Significance Olfactory interference depends on the associative link between odor and PER, rather than between odor and sucrose. Furthermore, pairing an odor with sucrose can lead either to association of this odor to PER or to the inhibition of PER by this odor. Olfactory interference may provide insight into processes that gate how excitatory and inhibitory memories for odor-PER associations are formed. PMID:18946512

Negative refraction and backward wave in pseudochiral mediums: illustrations of Gaussian beams.

PubMed

Chern, Ruey-Lin; Chang, Po-Han

2013-02-11

We investigate the phenomena of negative refraction and backward wave in pseudochiral mediums, with illustrations of Gaussian beams. Due to symmetry breaking intrinsic in pseudochiral mediums, there exist two elliptically polarized eigenwaves with different wave vectors. As the chirality parameter increases from zero, the two waves begin to split from each other. For a wave incident from vacuum onto a pseudochiral medium, negative refraction may occur for the right-handed wave, whereas backward wave may appear for the left-handed wave. These features are illustrated with Gaussian beams based on Fourier integral formulations for the incident, reflected, and transmitted waves. Negative refraction and backward wave are manifest, respectively, on the energy flow in space and wavefront movement in time.

Source-receptor matrix calculation with a Source-receptor matrix calculation with a backward mode

NASA Astrophysics Data System (ADS)

Seibert, P.; Frank, A.

2003-08-01

The possibility to calculate linear-source receptor relationships for the transport of atmospheric trace substances with a Lagrangian particle dispersion model (LPDM) running in backward mode is shown and presented with many tests and examples. The derivation includes the action of sources and of any first-order processes (transformation with prescribed rates, dry and wet deposition, radioactive decay, ...). The backward mode is computationally advantageous if the number of receptors is less than the number of sources considered. The combination of an LPDM with the backward (adjoint) methodology is especially attractive for the application to point measurements, which can be handled without artificial numerical diffusion. Practical hints are provided for source-receptor calculations with different settings, both in forward and backward mode. The equivalence of forward and backward calculations is shown in simple tests for release and sampling of particles, pure wet deposition, pure convective redistribution and realistic transport over a short distance. Furthermore, an application example explaining measurements of Cs-137 in Stockholm as transport from areas contaminated heavily in the Chernobyl disaster is included.

Face-to-face handoff: improving transfer to the pediatric intensive care unit after cardiac surgery.

PubMed

Vergales, Jeffrey; Addison, Nancy; Vendittelli, Analise; Nicholson, Evelyn; Carver, D Jeannean; Stemland, Christopher; Hoke, Tracey; Gangemi, James

2015-01-01

The goal was to develop and implement a comprehensive, primarily face-to-face handoff process that begins in the operating room and concludes at the bedside in the intensive care unit (ICU) for pediatric patients undergoing congenital heart surgery. Involving all stakeholders in the planning phase, the framework of the handoff system encompassed a combination of a formalized handoff tool, focused process steps that occurred prior to patient arrival in the ICU, and an emphasis on face-to-face communication at the conclusion of the handoff. The final process was evaluated by the use of observer checklists to examine quality metrics and timing for all patients admitted to the ICU following cardiac surgery. The process was found to improve how various providers view the efficiency of handoff, the ease of asking questions at each step, and the overall capability to improve patient care regardless of overall surgical complexity. © 2014 by the American College of Medical Quality.

The Effect of Micro-ramps on Supersonic Flow over a Forward-Facing Step

NASA Astrophysics Data System (ADS)

Zhang, Qing-Hu; Yi, Shi-He; Zhu, Yang-Zhu; Chen, Zhi; Wu, Yu

2013-04-01

The effect of micro-ramp control on fully developed turbulent flow over a forward-facing step (FFS) is investigated in a supersonic low-noise wind tunnel at Mach number 3 using nano-tracer planar laser scattering (NPLS) and supersonic particle image velocimetry (PIV) techniques. High spatiotemporal resolution images and the average velocity profiles of supersonic flow over the FFS with and without the control of the micro-ramps are captured. The fine structures of both cases, including the coherent structures of fully developed boundary layer and the large-scale hairpin-like vortices originated from the micro-ramps as well as the interaction of shock waves with the large-scale structures, are revealed and compared. Based on the time-correlation images, the temporal and spatial evolutionary characteristics of the coherent structures are investigated. It is beneficial to understand the dynamic mechanisms of the separated flow and the control mechanisms of the micro-ramps. The size of the separation region is determined by the NPLS and PIV. The results indicate that the control of the micro-ramps is capable of delaying the separation and diminishing the extent of recirculation zone.

Problems of older persons using a wheeled walker.

PubMed

Lindemann, Ulrich; Schwenk, Michael; Klenk, Jochen; Kessler, Max; Weyrich, Michael; Kurz, Franziska; Becker, Clemens

2016-04-01

Wheeled walkers (WWs) are used to improve mobility and for fall prevention in older persons, but not all users are satisfied with the usability of WWs. Intelligent WWs are being developed to improve the usability. The aim of this study was to support the development of intelligent WWs by investigating possible problems of using a WW. This study investigated 22 geriatric in-patients (median age 82 years) with and without their WW while opening a door against the direction of walking and passing through. Other possible problems when using WWs were identified by interview. Walking through the door was faster without than with using the WW (8.71 versus 12.86 s, p < 0.001), while interference between door and WW was documented in 41 of 44 (93 %) cases. Backward walking performance was better when using a WW with regard to gait speed, step width and walk ratio (all p < 0.002). Most referred problems when using a WW were walking downhill (83 %) and uphill (77 %) and obstacle crossing in general (77 %). Problems with opening a door against the direction of walking and the optimization of downhill and uphill walking as well as obstacle crossing should be regarded when developing an intelligent WW.

Forward-backward emission of target evaporated fragments in high energy nucleus-nucleus collisions

NASA Astrophysics Data System (ADS)

Zhang, Zhi; Ma, Tian-Li; Zhang, Dong-Hai

2015-10-01

The multiplicity distribution, multiplicity moment, scaled variance, entropy and reduced entropy of target evaporated fragments emitted in forward and backward hemispheres in 12 A GeV 4He, 3.7 A GeV 16O, 60 A GeV 16O, 1.7 A GeV 84Kr and 10.7 A GeV 197Au -induced emulsion heavy target (AgBr) interactions are investigated. It is found that the multiplicity distribution of target evaporated fragments emitted in both forward and backward hemispheres can be fitted by a Gaussian distribution. The multiplicity moments of target evaporated particles emitted in the forward and backward hemispheres increase with the order of the moment q, and the second-order multiplicity moment is energy independent over the entire energy range for all the interactions in the forward and backward hemisphere. The scaled variance, a direct measure of multiplicity fluctuations, is close to one for all the interactions, which indicate a correlation among the produced particles. The entropy of target evaporated fragments emitted in both forward and backward hemispheres are the same within experimental errors. Supported by National Science Foundation of China (11075100), Natural Science Foundation of Shanxi Province (2011011001-2) and the Shanxi Provincial Foundation for Returned Overseas Chinese Scholars, (2011-058)

Problems of Face Recognition in Patients with Behavioral Variant Frontotemporal Dementia.

PubMed

Chandra, Sadanandavalli Retnaswami; Patwardhan, Ketaki; Pai, Anupama Ramakanth

2017-01-01

Faces are very special as they are most essential for social cognition in humans. It is partly understood that face processing in its abstractness involves several extra striate areas. One of the most important causes for caregiver suffering in patients with anterior dementia is lack of empathy. This apart from being a behavioral disorder could be also due to failure to categorize the emotions of the people around them. Inlusion criteria: DSM IV for Bv FTD Tested for prosopagnosia - familiar faces, famous face, smiling face, crying face and reflected face using a simple picture card (figure 1). Advanced illness and mixed causes. 46 patients (15 females, 31 males) 24 had defective face recognition. (mean age 51.5),10/15 females (70%) and 14/31males(47. Familiar face recognition defect was found in 6/10 females and 6/14 males. Total- 40%(6/15) females and 19.35%(6/31)males with FTD had familiar face recognition. Famous Face: 9/10 females and 7/14 males. Total- 60% (9/15) females with FTD had famous face recognition defect as against 22.6%(7/31) males with FTD Smiling face defects in 8/10 female and no males. Total- 53.33% (8/15) females. Crying face recognition defect in 3/10 female and 2 /14 males. Total- 20%(3/15) females and 6.5%(2/31) males. Reflected face recognition defect in 4 females. Famous face recognition and positive emotion recognition defect in 80%, only 20% comprehend positive emotions, Face recognition defects are found in only 45% of males and more common in females. Face recognition is more affected in females with FTD There is differential involvement of different aspects of the face recognition could be one of the important factor underlying decline in the emotional and social behavior of these patients. Understanding these pathological processes will give more insight regarding patient behavior.

Hysteresis and Phase Transitions in a Lattice Regularization of an Ill-Posed Forward-Backward Diffusion Equation

NASA Astrophysics Data System (ADS)

Helmers, Michael; Herrmann, Michael

2018-03-01

We consider a lattice regularization for an ill-posed diffusion equation with a trilinear constitutive law and study the dynamics of phase interfaces in the parabolic scaling limit. Our main result guarantees for a certain class of single-interface initial data that the lattice solutions satisfy asymptotically a free boundary problem with a hysteretic Stefan condition. The key challenge in the proof is to control the microscopic fluctuations that are inevitably produced by the backward diffusion when a particle passes the spinodal region.

Exact solution for a two-phase Stefan problem with variable latent heat and a convective boundary condition at the fixed face

NASA Astrophysics Data System (ADS)

Bollati, Julieta; Tarzia, Domingo A.

2018-04-01

Recently, in Tarzia (Thermal Sci 21A:1-11, 2017) for the classical two-phase Lamé-Clapeyron-Stefan problem an equivalence between the temperature and convective boundary conditions at the fixed face under a certain restriction was obtained. Motivated by this article we study the two-phase Stefan problem for a semi-infinite material with a latent heat defined as a power function of the position and a convective boundary condition at the fixed face. An exact solution is constructed using Kummer functions in case that an inequality for the convective transfer coefficient is satisfied generalizing recent works for the corresponding one-phase free boundary problem. We also consider the limit to our problem when that coefficient goes to infinity obtaining a new free boundary problem, which has been recently studied in Zhou et al. (J Eng Math 2017. https://doi.org/10.1007/s10665-017-9921-y).

Advancing parabolic operators in thermodynamic MHD models: Explicit super time-stepping versus implicit schemes with Krylov solvers

NASA Astrophysics Data System (ADS)

Caplan, R. M.; Mikić, Z.; Linker, J. A.; Lionello, R.

2017-05-01

We explore the performance and advantages/disadvantages of using unconditionally stable explicit super time-stepping (STS) algorithms versus implicit schemes with Krylov solvers for integrating parabolic operators in thermodynamic MHD models of the solar corona. Specifically, we compare the second-order Runge-Kutta Legendre (RKL2) STS method with the implicit backward Euler scheme computed using the preconditioned conjugate gradient (PCG) solver with both a point-Jacobi and a non-overlapping domain decomposition ILU0 preconditioner. The algorithms are used to integrate anisotropic Spitzer thermal conduction and artificial kinematic viscosity at time-steps much larger than classic explicit stability criteria allow. A key component of the comparison is the use of an established MHD model (MAS) to compute a real-world simulation on a large HPC cluster. Special attention is placed on the parallel scaling of the algorithms. It is shown that, for a specific problem and model, the RKL2 method is comparable or surpasses the implicit method with PCG solvers in performance and scaling, but suffers from some accuracy limitations. These limitations, and the applicability of RKL methods are briefly discussed.

Backward Planning a Craniomaxillofacial Trauma Curriculum for the Surgical Workforce in Low-Resource Settings.

PubMed

Shaye, David A; Tollefson, Travis; Shah, Irfan; Krishnan, Gopal; Matic, Damir; Figari, Marcelo; Lim, Thiam Chye; Aniruth, Sunil; Schubert, Warren

2018-06-06

Trauma is a significant contributor to global disease, and low-income countries disproportionately shoulder this burden. Education and training are critical components in the effort to address the surgical workforce shortage. Educators can tailor training to a diverse background of health professionals in low-resource settings using competency-based curricula. We present a process for the development of a competency-based curriculum for low-resource settings in the context of craniomaxillofacial (CMF) trauma education. CMF trauma surgeons representing 7 low-, middle-, and high-income countries conducted a standardized educational curriculum development program. Patient problems related to facial injuries were identified and ranked from highest to lowest morbidity. Higher morbidity problems were categorized into 4 modules with agreed upon competencies. Methods of delivery (lectures, case discussions, and practical exercises) were selected to optimize learning of each competency. A facial injuries educational curriculum (1.5 days event) was tailored to health professionals with diverse training backgrounds who care for CMF trauma patients in low-resource settings. A backward planned, competency-based curriculum was organized into four modules titled: acute (emergent), eye (periorbital injuries and sight preserving measures), mouth (dental injuries and fracture care), and soft tissue injury treatments. Four courses have been completed with pre- and post-course assessments completed. Surgeons and educators from a diverse geographic background found the backward planning curriculum development method effective in creating a competency-based facial injuries (trauma) course for health professionals in low-resource settings, where contextual aspects of shortages of surgical capacity, equipment, and emergency transportation must be considered.

Face detection and eyeglasses detection for thermal face recognition

NASA Astrophysics Data System (ADS)

Zheng, Yufeng

2012-01-01

Thermal face recognition becomes an active research direction in human identification because it does not rely on illumination condition. Face detection and eyeglasses detection are necessary steps prior to face recognition using thermal images. Infrared light cannot go through glasses and thus glasses will appear as dark areas in a thermal image. One possible solution is to detect eyeglasses and to exclude the eyeglasses areas before face matching. In thermal face detection, a projection profile analysis algorithm is proposed, where region growing and morphology operations are used to segment the body of a subject; then the derivatives of two projections (horizontal and vertical) are calculated and analyzed to locate a minimal rectangle of containing the face area. Of course, the searching region of a pair of eyeglasses is within the detected face area. The eyeglasses detection algorithm should produce either a binary mask if eyeglasses present, or an empty set if no eyeglasses at all. In the proposed eyeglasses detection algorithm, block processing, region growing, and priori knowledge (i.e., low mean and variance within glasses areas, the shapes and locations of eyeglasses) are employed. The results of face detection and eyeglasses detection are quantitatively measured and analyzed using the manually defined ground truths (for both face and eyeglasses). Our experimental results shown that the proposed face detection and eyeglasses detection algorithms performed very well in contrast with the predefined ground truths.

Cerebral Asymmetries in Early Orthographic and Phonological Reading Processes: Evidence from Backward Masking

ERIC Educational Resources Information Center

Halderman, Laura K.; Chiarello, Christine

2005-01-01

A lateralized backward masking paradigm was used to examine hemisphere differences in orthographic and phonological processes at an early time course of word recognition. Targets (e.g., bowl) were presented and backward masked by either pseudohomophones of the target word (orthographically and phonologically similar, e.g., BOAL), orthographically…

Assessment of Corneal Backward Light Scattering in Diabetic Patients.

PubMed

Özyol, Pelin; Özyol, Erhan

2016-10-03

To analyze corneal backward light scattering differences in patients with type 2 diabetes mellitus. We enrolled 43 eyes from 43 diabetic patients and 40 eyes from 40 healthy controls. Corneal backward light scattering was evaluated using densitometry measurements from different corneal layers and zones obtained using Scheimpflug tomography (PentacamHR). When densitometry values were divided by depth, anterior layer of diabetic corneas displayed significantly higher corneal backward light scattering values than controls (32.05, 95% confidence intervals [CI], 31.02-33.08 vs. 29.18, 95% CI, 27.60-30.76, P=0.024). Corneal densitometry measurements were also significantly higher in diabetic eyes compared with control eyes, when considered by concentric zones of total cornea in the 0 to 2 mm (21.65, 95% CI, 20.28-23.01 vs. 18.87 95% CI, 18.49-19.25, P=0.020), and anterior layer in the 0 to 2 mm (27.3, 95% CI, 25.04-29.56 vs. 22.31, 95% CI, 20.57-24.05, P<0.001), 2 to 6 mm (26.2, 95% CI, 24.99-27.41 vs. 22.4, 95% CI, 20.18-24.62, P<0.001) and 6 to 10 mm (32.19, 95% CI, 29.98-34.40 vs. 27.2, 95% CI, 25.39-29.01, P=0.022). There was excellent positive correlation between anterior total corneal densitometry measurements and duration of diabetes (r=0.802, P<0.001), although no significant correlation was observed with anterior total corneal densitometry measurements and hemoglobin A1c levels (r=0.080, P=0.621) in diabetic eyes. Backward light scattering values from the anterior layer of the cornea is greater in diabetic eyes than in controls. Anterior total corneal densitometry measurements show positive correlation with the duration of diabetes.

Alternative face models for 3D face registration

NASA Astrophysics Data System (ADS)

Salah, Albert Ali; Alyüz, Neşe; Akarun, Lale

2007-01-01

3D has become an important modality for face biometrics. The accuracy of a 3D face recognition system depends on a correct registration that aligns the facial surfaces and makes a comparison possible. The best results obtained so far use a one-to-all registration approach, which means each new facial surface is registered to all faces in the gallery, at a great computational cost. We explore the approach of registering the new facial surface to an average face model (AFM), which automatically establishes correspondence to the pre-registered gallery faces. Going one step further, we propose that using a couple of well-selected AFMs can trade-off computation time with accuracy. Drawing on cognitive justifications, we propose to employ category-specific alternative average face models for registration, which is shown to increase the accuracy of the subsequent recognition. We inspect thin-plate spline (TPS) and iterative closest point (ICP) based registration schemes under realistic assumptions on manual or automatic landmark detection prior to registration. We evaluate several approaches for the coarse initialization of ICP. We propose a new algorithm for constructing an AFM, and show that it works better than a recent approach. Finally, we perform simulations with multiple AFMs that correspond to different clusters in the face shape space and compare these with gender and morphology based groupings. We report our results on the FRGC 3D face database.

Kruskal-Wallis-based computationally efficient feature selection for face recognition.

PubMed

Ali Khan, Sajid; Hussain, Ayyaz; Basit, Abdul; Akram, Sheeraz

2014-01-01

Face recognition in today's technological world, and face recognition applications attain much more importance. Most of the existing work used frontal face images to classify face image. However these techniques fail when applied on real world face images. The proposed technique effectively extracts the prominent facial features. Most of the features are redundant and do not contribute to representing face. In order to eliminate those redundant features, computationally efficient algorithm is used to select the more discriminative face features. Extracted features are then passed to classification step. In the classification step, different classifiers are ensemble to enhance the recognition accuracy rate as single classifier is unable to achieve the high accuracy. Experiments are performed on standard face database images and results are compared with existing techniques.

The Screening Tool of Feeding Problems Applied to Children (STEP-CHILD): Psychometric Characteristics and Associations with Child and Parent Variables

ERIC Educational Resources Information Center

Seiverling, Laura; Hendy, Helen M.; Williams, Keith

2011-01-01

The present study evaluated the 23-item Screening Tool for Feeding Problems (STEP; Matson & Kuhn, 2001) with a sample of children referred to a hospital-based feeding clinic to examine the scale's psychometric characteristics and then demonstrate how a children's revision of the STEP, the STEP-CHILD is associated with child and parent variables.…

Intentional Teaching, Intentional Scholarship: Applying Backward Design Principles in a Faculty Writing Group

ERIC Educational Resources Information Center

Linder, Kathryn E.; Cooper, Frank Rudy; McKenzie, Elizabeth M.; Raesch, Monika; Reeve, Patricia A.

2014-01-01

Backward design is a course creation method that encourages teachers to identify their goals for student understanding and measurable objectives for learning from the outset. In this article we explore the application of backward design to the production of scholarly articles. Specifically, we report on a writing group program that encourages…

Reversible Reasoning and the Working Backwards Problem Solving Strategy

ERIC Educational Resources Information Center

Ramful, Ajay

2015-01-01

Making sense of mathematical concepts and solving mathematical problems may demand different forms of reasoning. These could be either domain-based, such as algebraic, geometric or statistical reasoning, while others are more general such as inductive/deductive reasoning. This article aims at giving visibility to a particular form of reasoning…

Least-squares solution of incompressible Navier-Stokes equations with the p-version of finite elements

NASA Technical Reports Server (NTRS)

Jiang, Bo-Nan; Sonnad, Vijay

1991-01-01

A p-version of the least squares finite element method, based on the velocity-pressure-vorticity formulation, is developed for solving steady state incompressible viscous flow problems. The resulting system of symmetric and positive definite linear equations can be solved satisfactorily with the conjugate gradient method. In conjunction with the use of rapid operator application which avoids the formation of either element of global matrices, it is possible to achieve a highly compact and efficient solution scheme for the incompressible Navier-Stokes equations. Numerical results are presented for two-dimensional flow over a backward facing step. The effectiveness of simple outflow boundary conditions is also demonstrated.

Backward elastic light scattering of malaria infected red blood cells

NASA Astrophysics Data System (ADS)

Lee, Seungjun; Lu, Wei

2011-08-01

We investigated the backward light scattering pattern of healthy and malaria (Plasmodium falciparum) parasitized red blood cells. The spectrum could clearly distinguish between predominant ring stage infected blood cells and healthy blood cells. Further, we found that infected samples mixed with different stages of P. falciparum showed different signals, suggesting that even variance in parasite stages could also be detected by the spectrum. These results together with the backward scattering technique suggest the potential of non-invasive diagnosis of malaria through light scattering of blood cells near the surface of human body, such as using eyes or skin surface.

BACKWARD ESTIMATION OF STOCHASTIC PROCESSES WITH FAILURE EVENTS AS TIME ORIGINS1

PubMed Central

Gary Chan, Kwun Chuen; Wang, Mei-Cheng

2011-01-01

Stochastic processes often exhibit sudden systematic changes in pattern a short time before certain failure events. Examples include increase in medical costs before death and decrease in CD4 counts before AIDS diagnosis. To study such terminal behavior of stochastic processes, a natural and direct way is to align the processes using failure events as time origins. This paper studies backward stochastic processes counting time backward from failure events, and proposes one-sample nonparametric estimation of the mean of backward processes when follow-up is subject to left truncation and right censoring. We will discuss benefits of including prevalent cohort data to enlarge the identifiable region and large sample properties of the proposed estimator with related extensions. A SEER–Medicare linked data set is used to illustrate the proposed methodologies. PMID:21359167

Flight-measured base pressure coefficients for thick boundary-layer flow over an aft-facing step for Mach numbers from 0.4 to 2.5

NASA Technical Reports Server (NTRS)

Goecke, S. A.

1973-01-01

A 0.56-inch thick aft-facing step was located 52.1 feet from the leading edge of the left wing of an XB-70 airplane. A boundary-layer rake at a mirror location on the right wing was used to obtain local flow properties. Reynolds numbers were near 10 to the 8th power, resulting in a relatively thick boundary-layer. The momentum thickness ranged from slightly thinner to slightly thicker than the step height. Surface static pressures forward of the step were obtained for Mach numbers near 0.9, 1.5, 2.0, and 2.4. The data were compared with thin boundary-layer results from flight and wind-tunnel experiments and semiempirical relationships. Significant differences were found between the thick and the thin boundary-layer data.

Observations of cleavage steps, slip traces and dislocation hollow cores on cleaved ?100? faces of ?-arginine phosphate monohydrate single crystals by atomic force microscopy

NASA Astrophysics Data System (ADS)

Sangwal, K.; Torrent-Burgués, J.; Sanz, F.; Servat, J.

1997-03-01

The results of an atomic force microscopy study of the nature of cleavage steps, observation of slip traces and formation of hollow cores at the centres of dislocations on the {100} faces of L-arginine phosphate monohydrate (LAP) single crystals grown from aqueous solutions are described and discussed. It was observed that: (1) most of the cleavage steps and all the slip traces are of elementary height, a = 1.085 nm; (2) the origin of a cleavage step may or may not have a hollow core; and (3) close to its origin, the curvature of a cleavage step may be positive or negative or may change from positive to negative. The results suggest that slip traces observed on the cleaved surfaces of LAP are formed during the cleavage process while the rounding and the rearrangement of elementary cleavage steps take place immediately after the occurrence of cleavage. Analysis of the results also shows that the dislocations responsible for the origin of hollow cores always represent a stress field state corresponding to a trapped solution of different local interface supersaturations.

Backward-in-time methods to simulate large-scale transport and mixing in the ocean

NASA Astrophysics Data System (ADS)

Prants, S. V.

2015-06-01

In oceanography and meteorology, it is important to know not only where water or air masses are headed for, but also where they came from as well. For example, it is important to find unknown sources of oil spills in the ocean and of dangerous substance plumes in the atmosphere. It is impossible with the help of conventional ocean and atmospheric numerical circulation models to extrapolate backward from the observed plumes to find the source because those models cannot be reversed in time. We review here recently elaborated backward-in-time numerical methods to identify and study mesoscale eddies in the ocean and to compute where those waters came from to a given area. The area under study is populated with a large number of artificial tracers that are advected backward in time in a given velocity field that is supposed to be known analytically or numerically, or from satellite and radar measurements. After integrating advection equations, one gets positions of each tracer on a fixed day in the past and can identify from known destinations a particle positions at earlier times. The results provided show that the method is efficient, for example, in estimating probabilities to find increased concentrations of radionuclides and other pollutants in oceanic mesoscale eddies. The backward-in-time methods are illustrated in this paper with a few examples. Backward-in-time Lagrangian maps are applied to identify eddies in satellite-derived and numerically generated velocity fields and to document the pathways by which they exchange water with their surroundings. Backward-in-time trapping maps are used to identify mesoscale eddies in the altimetric velocity field with a risk to be contaminated by Fukushima-derived radionuclides. The results of simulations are compared with in situ mesurement of caesium concentration in sea water samples collected in a recent research vessel cruise in the area to the east of Japan. Backward-in-time latitudinal maps and the corresponding

Evaluation of energy expenditure in forward and backward movements performed by soccer referees

PubMed Central

Paes, M.R.; Fernandez, R.

2016-01-01

The aim of this study was to measure the energy expenditure for locomotor activities usually performed by soccer referees during a match (walking, jogging, and running) under laboratory conditions, and to compare forward with backward movements. The sample was composed by 10 male soccer referees, age 29±7.8 years, body mass 77.5±6.2 kg, stature 1.78±0.07 m and professional experience of 7.33±4.92 years. Referees were evaluated on two separate occasions. On the first day, maximal oxygen uptake (VO2max) was determined by a maximal treadmill test, and on the second day, the oxygen consumption was determined in different speeds of forward and backward movements. The mean VO2max was 41.20±3.60 mL·kg-1·min-1 and the mean heart rate achieved in the last stage of the test was 190.5±7.9 bpm. When results of forward and backward movements were compared at 1.62 m/s (walking speed), we found significant differences in VO2, in metabolic equivalents, and in kcal. However, the same parameters in forward and backward movements at jogging velocities (2.46 m/s) were not significantly different, showing that these motor activities have similar intensity. Backward movements at velocities equivalent to walking and jogging are moderate-intensity activities, with energy expenditure less than 9 kcal. Energy expenditure was overestimated by at least 35% when calculated by mathematical equations. In summary, we observed that backward movements are not high-intensity activities as has been commonly reported, and when calculated using equations available in the literature, energy expenditure was overestimated compared to the values obtained by indirect calorimetry. PMID:27074169

Using Problem-Solving Steps and Audience Roles To Increase Student Engagement in Elementary Civics Instruction.

ERIC Educational Resources Information Center

Beck, Terence A.

Leslie Herrenkohl's work in science (1998) has demonstrated that introducing "problem-solving steps" and "audience roles" to an elementary classroom can have a dramatic impact on rates of student engagement as measured through classroom talk. It is not known to what extent the success of the intervention was due to its…

Backward emitted high-energy neutrons in hard reactions of p and π+ on carbon

NASA Astrophysics Data System (ADS)

Malki, A.; Alster, J.; Asryan, G.; Averichev, Y.; Barton, D.; Baturin, V.; Bukhtoyarova, N.; Carroll, A.; Heppelmann, S.; Kawabata, T.; Leksanov, A.; Makdisi, Y.; Minina, E.; Navon, I.; Nicholson, H.; Ogawa, A.; Panebratsev, Yu.; Piasetzky, E.; Schetkovsky, A.; Shimanskiy, S.; Tang, A.; Watson, J. W.; Yoshida, H.; Zhalov, D.

2002-01-01

Beams of protons and pions of 5.9 GeV/c were incident on a C target. Neutrons emitted into the backward hemisphere, in the laboratory system, were detected in (triple) coincidence with two emerging particles of tranverse momenta pt>0.6 GeV/c. We determined that for (46.5+/-3.7)% of the proton-induced events and for (40.8+/-4.5)% of the pion-induced events with the two high-pt particles, there is also at least one backward emitted neutron with momentum greater than 0.32 GeV/c. This observation is in sharp contrast to a well- established universal pattern from a large variety of earlier inclusive measurements with hadrons, electrons, photons, neutrinos, and antineutrinos where the probability for backward nucleon emission was in the 5 to 10 % range. We present also a measurement of the momentum spectra for the backward going neutrons. The spectra have the same universal shape observed in the inclusive reactions. We speculate that the enhanced backward neutron emission in this semi-inclusive region could be an indication for a strong dependence of the cross section on the squared total center-of-mass energy (s) and for the importance of short-range nucleon-nucleon correlations.

Improved backward ray tracing with stochastic sampling

NASA Astrophysics Data System (ADS)

Ryu, Seung Taek; Yoon, Kyung-Hyun

1999-03-01

This paper presents a new technique that enhances the diffuse interreflection with the concepts of backward ray tracing. In this research, we have modeled the diffuse rays with the following conditions. First, as the reflection from the diffuse surfaces occurs in all directions, it is impossible to trace all of the reflected rays. We confined the diffuse rays by sampling the spherical angle out of the reflected rays around the normal vector. Second, the traveled distance of reflected energy from the diffuse surface differs according to the object's property, and has a comparatively short reflection distance. Considering the fact that the rays created on the diffuse surfaces affect relatively small area, it is very inefficient to trace all of the sampled diffused rays. Therefore, we set a fixed distance as the critical distance and all the rays beyond this distance are ignored. The result of this research is that as the improved backward ray tracing can model the illumination effects such as the color bleeding effects, we can replace the radiosity algorithm under the limited environment.

Testing Backwards Integration As A Method Of Age-Determination for KBO Families

NASA Astrophysics Data System (ADS)

Benfell, Nathan; Ragozzine, Darin

2017-10-01

The age of young asteroid collisional families is often determined by using backwards n-body integration of the solar system. This method is not used for discovering young asteroid families and is limited by the unpredictable influence of the Yarkovsky effect on individual specific asteroids over time. Since these limitations are not as important for objects in the Kuiper belt Marcus et al. 2011 suggested that backwards integration could be used to discover and characterize collisional families in the outer solar system. However, there are some minor effects that may be important to include in the integration to ensure a faithful reproduction of the actual solar system. We have created simulated families of Kuiper Belt objects through a forwards integration of various objects with identical starting locations and velocity distributions, based on the Haumea family. After carrying this integration forwards through ~4 Gyr, backwards integrations are used (1) to investigate which factors are of enough significance to require inclusion in the integration (e.g., terrestrial planets, KBO self-gravity, putative Planet 9, etc.), (2) to test orbital element clustering statistics and identify methods for assessing false alarm probabilities, and (3) to compare the age estimates with the known age of the simulated family to explore the viability of backwards integration for precise age estimates.

Shear zone formation within the billet and metal flow through the die orifice in unlubricated axisymmetric forward and backward extrusion

NASA Astrophysics Data System (ADS)

Valberg, Henry; Costa, Andrè L. M.

2017-10-01

Metal flow inside the billet is known to be completely different in forward (FWE) and backward (BWE) Al-extrusion. A practical implication of this is that contamination near to the surface of the extrusion billet, or on the peripheral surface skin, tends to flow out of the die more readily in BWE than in FWE. It is therefore common in BWE to use a scalping operation on the billet to remove eventual sub-surface contamination that may be present. This additional working operation may be required in order to avoid surface quality problems on BWE profiles. In spite of the importance of metal flow in metals extrusion, there are still lack of knowledge about the topic. With recent progress in FEM-analysis for modelling deformation processing, however, it is now possible to perform accurate studies on metal flow phenomena by simulation on the computer. In our study, we are using the 3D FEM-program DEFORM® to model axisymmetric FWE and BWE in case of non-lubricated extrusion through a flat-faced die. Our primary focus is to consider the difference in appearance of shear zones present inside the extrusion billet for the two processes, including metal flow in the die mouth.

Efficient Deterministic Finite Automata Minimization Based on Backward Depth Information.

PubMed

Liu, Desheng; Huang, Zhiping; Zhang, Yimeng; Guo, Xiaojun; Su, Shaojing

2016-01-01

Obtaining a minimal automaton is a fundamental issue in the theory and practical implementation of deterministic finite automatons (DFAs). A minimization algorithm is presented in this paper that consists of two main phases. In the first phase, the backward depth information is built, and the state set of the DFA is partitioned into many blocks. In the second phase, the state set is refined using a hash table. The minimization algorithm has a lower time complexity O(n) than a naive comparison of transitions O(n2). Few states need to be refined by the hash table, because most states have been partitioned by the backward depth information in the coarse partition. This method achieves greater generality than previous methods because building the backward depth information is independent of the topological complexity of the DFA. The proposed algorithm can be applied not only to the minimization of acyclic automata or simple cyclic automata, but also to automata with high topological complexity. Overall, the proposal has three advantages: lower time complexity, greater generality, and scalability. A comparison to Hopcroft's algorithm demonstrates experimentally that the algorithm runs faster than traditional algorithms.

Efficient Deterministic Finite Automata Minimization Based on Backward Depth Information

PubMed Central

Liu, Desheng; Huang, Zhiping; Zhang, Yimeng; Guo, Xiaojun; Su, Shaojing

2016-01-01

Obtaining a minimal automaton is a fundamental issue in the theory and practical implementation of deterministic finite automatons (DFAs). A minimization algorithm is presented in this paper that consists of two main phases. In the first phase, the backward depth information is built, and the state set of the DFA is partitioned into many blocks. In the second phase, the state set is refined using a hash table. The minimization algorithm has a lower time complexity O(n) than a naive comparison of transitions O(n2). Few states need to be refined by the hash table, because most states have been partitioned by the backward depth information in the coarse partition. This method achieves greater generality than previous methods because building the backward depth information is independent of the topological complexity of the DFA. The proposed algorithm can be applied not only to the minimization of acyclic automata or simple cyclic automata, but also to automata with high topological complexity. Overall, the proposal has three advantages: lower time complexity, greater generality, and scalability. A comparison to Hopcroft’s algorithm demonstrates experimentally that the algorithm runs faster than traditional algorithms. PMID:27806102

Early ERP Modulation for Task-Irrelevant Subliminal Faces

PubMed Central

Pegna, Alan J.; Darque, Alexandra; Berrut, Claire; Khateb, Asaid

2011-01-01

A number of investigations have reported that emotional faces can be processed subliminally, and that they give rise to specific patterns of brain activation in the absence of awareness. Recent event-related potential (ERP) studies have suggested that electrophysiological differences occur early in time (<200 ms) in response to backward-masked emotional faces. These findings have been taken as evidence of a rapid non-conscious pathway, which would allow threatening stimuli to be processed rapidly and subsequently allow appropriate avoidance action to be taken. However, for this to be the case, subliminal processing should arise even if the threatening stimulus is not attended. This point has in fact not yet been clearly established. In this ERP study, we investigated whether subliminal processing of fearful faces occurs outside the focus of attention. Fourteen healthy participants performed a line judgment task while fearful and non-fearful (happy or neutral) faces were presented both subliminally and supraliminally. ERPs were compared across the four experimental conditions (i.e., subliminal and supraliminal; fearful and non-fearful). The earliest differences between fearful and non-fearful faces appeared as an enhanced posterior negativity for the former at 170 ms (the N170 component) over right temporo-occipital electrodes. This difference was observed for both subliminal (p < 0.05) and supraliminal presentations (p < 0.01). Our results confirm that subliminal processing of fearful faces occurs early in the course of visual processing, and more importantly, that this arises even when the subject's attention is engaged in an incidental task. PMID:21687457

Early ERP Modulation for Task-Irrelevant Subliminal Faces.

PubMed

Pegna, Alan J; Darque, Alexandra; Berrut, Claire; Khateb, Asaid

2011-01-01

A number of investigations have reported that emotional faces can be processed subliminally, and that they give rise to specific patterns of brain activation in the absence of awareness. Recent event-related potential (ERP) studies have suggested that electrophysiological differences occur early in time (<200 ms) in response to backward-masked emotional faces. These findings have been taken as evidence of a rapid non-conscious pathway, which would allow threatening stimuli to be processed rapidly and subsequently allow appropriate avoidance action to be taken. However, for this to be the case, subliminal processing should arise even if the threatening stimulus is not attended. This point has in fact not yet been clearly established. In this ERP study, we investigated whether subliminal processing of fearful faces occurs outside the focus of attention. Fourteen healthy participants performed a line judgment task while fearful and non-fearful (happy or neutral) faces were presented both subliminally and supraliminally. ERPs were compared across the four experimental conditions (i.e., subliminal and supraliminal; fearful and non-fearful). The earliest differences between fearful and non-fearful faces appeared as an enhanced posterior negativity for the former at 170 ms (the N170 component) over right temporo-occipital electrodes. This difference was observed for both subliminal (p < 0.05) and supraliminal presentations (p < 0.01). Our results confirm that subliminal processing of fearful faces occurs early in the course of visual processing, and more importantly, that this arises even when the subject's attention is engaged in an incidental task.

Extending substructure based iterative solvers to multiple load and repeated analyses

NASA Technical Reports Server (NTRS)

Farhat, Charbel

1993-01-01

Direct solvers currently dominate commercial finite element structural software, but do not scale well in the fine granularity regime targeted by emerging parallel processors. Substructure based iterative solvers--often called also domain decomposition algorithms--lend themselves better to parallel processing, but must overcome several obstacles before earning their place in general purpose structural analysis programs. One such obstacle is the solution of systems with many or repeated right hand sides. Such systems arise, for example, in multiple load static analyses and in implicit linear dynamics computations. Direct solvers are well-suited for these problems because after the system matrix has been factored, the multiple or repeated solutions can be obtained through relatively inexpensive forward and backward substitutions. On the other hand, iterative solvers in general are ill-suited for these problems because they often must restart from scratch for every different right hand side. In this paper, we present a methodology for extending the range of applications of domain decomposition methods to problems with multiple or repeated right hand sides. Basically, we formulate the overall problem as a series of minimization problems over K-orthogonal and supplementary subspaces, and tailor the preconditioned conjugate gradient algorithm to solve them efficiently. The resulting solution method is scalable, whereas direct factorization schemes and forward and backward substitution algorithms are not. We illustrate the proposed methodology with the solution of static and dynamic structural problems, and highlight its potential to outperform forward and backward substitutions on parallel computers. As an example, we show that for a linear structural dynamics problem with 11640 degrees of freedom, every time-step beyond time-step 15 is solved in a single iteration and consumes 1.0 second on a 32 processor iPSC-860 system; for the same problem and the same parallel

Step by Step: Biology Undergraduates’ Problem-Solving Procedures during Multiple-Choice Assessment

PubMed Central

Prevost, Luanna B.; Lemons, Paula P.

2016-01-01

This study uses the theoretical framework of domain-specific problem solving to explore the procedures students use to solve multiple-choice problems about biology concepts. We designed several multiple-choice problems and administered them on four exams. We trained students to produce written descriptions of how they solved the problem, and this allowed us to systematically investigate their problem-solving procedures. We identified a range of procedures and organized them as domain general, domain specific, or hybrid. We also identified domain-general and domain-specific errors made by students during problem solving. We found that students use domain-general and hybrid procedures more frequently when solving lower-order problems than higher-order problems, while they use domain-specific procedures more frequently when solving higher-order problems. Additionally, the more domain-specific procedures students used, the higher the likelihood that they would answer the problem correctly, up to five procedures. However, if students used just one domain-general procedure, they were as likely to answer the problem correctly as if they had used two to five domain-general procedures. Our findings provide a categorization scheme and framework for additional research on biology problem solving and suggest several important implications for researchers and instructors. PMID:27909021

Effects of Progressive Body Weight Support Treadmill Forward and Backward Walking Training on Stroke Patients' Affected Side Lower Extremity's Walking Ability.

PubMed

Kim, Kyunghoon; Lee, Sukmin; Lee, Kyoungbo

2014-12-01

[Purpose] The purpose of the present study was to examine the effects of progressive body weight supported treadmill forward and backward walking training (PBWSTFBWT), progressive body weight supported treadmill forward walking training (PBWSTFWT), progressive body weight supported treadmill backward walking training (PBWSTBWT), on stroke patients' affected side lower extremity's walking ability. [Subjects and Methods] A total of 36 chronic stroke patients were divided into three groups with 12 subjects in each group. Each of the groups performed one of the progressive body weight supported treadmill training methods for 30 minute, six times per week for three weeks, and then received general physical therapy without any other intervention until the follow-up tests. For the assessment of the affected side lower extremity's walking ability, step length of the affected side, stance phase of the affected side, swing phase of the affected side, single support of the affected side, and step time of the affected side were measured using optogait and the symmetry index. [Results] In the within group comparisons, all the three groups showed significant differences between before and after the intervention and in the comparison of the three groups, the PBWSTFBWT group showed more significant differences in all of the assessed items than the other two groups. [Conclusion] In the present study progressive body weight supported treadmill training was performed in an environment in which the subjects were actually walked, and PBWSTFBWT was more effective at efficiently training stroke patients' affected side lower extremity's walking ability.

A survey of the dummy face and human face stimuli used in BCI paradigm.

PubMed

Chen, Long; Jin, Jing; Zhang, Yu; Wang, Xingyu; Cichocki, Andrzej

2015-01-15

It was proved that the human face stimulus were superior to the flash only stimulus in BCI system. However, human face stimulus may lead to copyright infringement problems and was hard to be edited according to the requirement of the BCI study. Recently, it was reported that facial expression changes could be done by changing a curve in a dummy face which could obtain good performance when it was applied to visual-based P300 BCI systems. In this paper, four different paradigms were presented, which were called dummy face pattern, human face pattern, inverted dummy face pattern and inverted human face pattern, to evaluate the performance of the dummy faces stimuli compared with the human faces stimuli. The key point that determined the value of dummy faces in BCI systems were whether dummy faces stimuli could obtain as good performance as human faces stimuli. Online and offline results of four different paradigms would have been obtained and comparatively analyzed. Online and offline results showed that there was no significant difference among dummy faces and human faces in ERPs, classification accuracy and information transfer rate when they were applied in BCI systems. Dummy faces stimuli could evoke large ERPs and obtain as high classification accuracy and information transfer rate as the human faces stimuli. Since dummy faces were easy to be edited and had no copyright infringement problems, it would be a good choice for optimizing the stimuli of BCI systems. Copyright © 2014 Elsevier B.V. All rights reserved.

Dissociative part-dependent biopsychosocial reactions to backward masked angry and neutral faces: An fMRI study of dissociative identity disorder.

PubMed

Schlumpf, Yolanda R; Nijenhuis, Ellert R S; Chalavi, Sima; Weder, Ekaterina V; Zimmermann, Eva; Luechinger, Roger; La Marca, Roberto; Reinders, A A T Simone; Jäncke, Lutz

2013-01-01

The Theory of Structural Dissociation of the Personality (TSDP) proposes that dissociative identity disorder (DID) patients are fixed in traumatic memories as "Emotional Parts" (EP), but mentally avoid these as "Apparently Normal Parts" of the personality (ANP). We tested the hypotheses that ANP and EP have different biopsychosocial reactions to subliminally presented angry and neutral faces, and that actors instructed and motivated to simulate ANP and EP react differently. Women with DID and matched healthy female actors (CON) were as ANP and EP (DIDanp, DIDep, CONanp, CONep) consecutively exposed to masked neutral and angry faces. Their brain activation was monitored using functional magnetic resonance imaging. The black-and-white dotted masks preceding and following the faces each had a centered colored dot, but in a different color. Participants were instructed to immediately press a button after a perceived color change. State anxiety was assessed after each run using the STAI-S. Final statistical analyses were conducted on 11 DID patients and 15 controls for differences in neural activity, and 13 DID patients and 15 controls for differences in behavior and psychometric measures. Differences between ANP and EP in DID patients and between DID and CON in the two dissociative parts of the personality were generally larger for neutral than for angry faces. The longest reaction times (RTs) existed for DIDep when exposed to neutral faces. Compared to DIDanp, DIDep was associated with more activation of the parahippocampal gyrus. Following neutral faces and compared to CONep, DIDep had more activation in the brainstem, face-sensitive regions, and motor-related areas. DIDanp showed a decreased activity all over the brain in the neutral and angry face condition. There were neither significant within differences nor significant between group differences in state anxiety. CON was not able to simulate genuine ANP and EP biopsychosocially. DID patients have dissociative

Dissociative part-dependent biopsychosocial reactions to backward masked angry and neutral faces: An fMRI study of dissociative identity disorder☆

PubMed Central

Schlumpf, Yolanda R.; Nijenhuis, Ellert R.S.; Chalavi, Sima; Weder, Ekaterina V.; Zimmermann, Eva; Luechinger, Roger; La Marca, Roberto; Reinders, A.A.T. Simone; Jäncke, Lutz

2013-01-01

Objective The Theory of Structural Dissociation of the Personality (TSDP) proposes that dissociative identity disorder (DID) patients are fixed in traumatic memories as “Emotional Parts” (EP), but mentally avoid these as “Apparently Normal Parts” of the personality (ANP). We tested the hypotheses that ANP and EP have different biopsychosocial reactions to subliminally presented angry and neutral faces, and that actors instructed and motivated to simulate ANP and EP react differently. Methods Women with DID and matched healthy female actors (CON) were as ANP and EP (DIDanp, DIDep, CONanp, CONep) consecutively exposed to masked neutral and angry faces. Their brain activation was monitored using functional magnetic resonance imaging. The black-and-white dotted masks preceding and following the faces each had a centered colored dot, but in a different color. Participants were instructed to immediately press a button after a perceived color change. State anxiety was assessed after each run using the STAI-S. Final statistical analyses were conducted on 11 DID patients and 15 controls for differences in neural activity, and 13 DID patients and 15 controls for differences in behavior and psychometric measures. Results Differences between ANP and EP in DID patients and between DID and CON in the two dissociative parts of the personality were generally larger for neutral than for angry faces. The longest reaction times (RTs) existed for DIDep when exposed to neutral faces. Compared to DIDanp, DIDep was associated with more activation of the parahippocampal gyrus. Following neutral faces and compared to CONep, DIDep had more activation in the brainstem, face-sensitive regions, and motor-related areas. DIDanp showed a decreased activity all over the brain in the neutral and angry face condition. There were neither significant within differences nor significant between group differences in state anxiety. CON was not able to simulate genuine ANP and EP biopsychosocially

Variations of cortisol, fatigue and sleep disturbances in sound engineers: effect of job task and fast backward-rotating shifts.

PubMed

Vangelova, Katia K

2008-01-01

The aim was to study the effect of job task and fast backward-rotating shifts on the time-of-day variations of cortisol, fatigue, and sleep disturbances in broadcasting sound engineers. The concentration of saliva cortisol and ratings of stress, sleepiness, and fatigue were followed at 3-hour intervals during the fast backward-rotating shifts in 26 sound engineers: 14 subjects from control rooms, aged 45.1 +/- 7.3 years, and 12 subjects working in direct transmissions, aged 51.7 +/- 6.0 years. Saliva cortisol was assessed using an radioimmunology kit. The participants reported for stress symptoms after the shifts and filled a sleep diary. The effects of job task, shift, and time-of-day were analyzed by tests of between-subjects effects (SPSS). Cortisol retained the typical diurnal pattern with a highly significant effect of the shift. The job task and the shift interacted significantly. Higher cortisol values during the morning and night shifts in engineers working in direct transmissions were found. Their stress ratings were also higher, as well as the ratings of sleepiness and fatigue. The quality of sleep was worse in engineers working in direct transmissions. In conclusion, our data indicate that stress and fast backward-rotating shifts in sound engineers working in direct transmissions affect physiological stress markers such as cortisol and increase sleepiness, fatigue, and sleep problems.

Backward transfer entropy: Informational measure for detecting hidden Markov models and its interpretations in thermodynamics, gambling and causality

PubMed Central

Ito, Sosuke

2016-01-01

The transfer entropy is a well-established measure of information flow, which quantifies directed influence between two stochastic time series and has been shown to be useful in a variety fields of science. Here we introduce the transfer entropy of the backward time series called the backward transfer entropy, and show that the backward transfer entropy quantifies how far it is from dynamics to a hidden Markov model. Furthermore, we discuss physical interpretations of the backward transfer entropy in completely different settings of thermodynamics for information processing and the gambling with side information. In both settings of thermodynamics and the gambling, the backward transfer entropy characterizes a possible loss of some benefit, where the conventional transfer entropy characterizes a possible benefit. Our result implies the deep connection between thermodynamics and the gambling in the presence of information flow, and that the backward transfer entropy would be useful as a novel measure of information flow in nonequilibrium thermodynamics, biochemical sciences, economics and statistics. PMID:27833120

Backward transfer entropy: Informational measure for detecting hidden Markov models and its interpretations in thermodynamics, gambling and causality

NASA Astrophysics Data System (ADS)

Ito, Sosuke

2016-11-01

The transfer entropy is a well-established measure of information flow, which quantifies directed influence between two stochastic time series and has been shown to be useful in a variety fields of science. Here we introduce the transfer entropy of the backward time series called the backward transfer entropy, and show that the backward transfer entropy quantifies how far it is from dynamics to a hidden Markov model. Furthermore, we discuss physical interpretations of the backward transfer entropy in completely different settings of thermodynamics for information processing and the gambling with side information. In both settings of thermodynamics and the gambling, the backward transfer entropy characterizes a possible loss of some benefit, where the conventional transfer entropy characterizes a possible benefit. Our result implies the deep connection between thermodynamics and the gambling in the presence of information flow, and that the backward transfer entropy would be useful as a novel measure of information flow in nonequilibrium thermodynamics, biochemical sciences, economics and statistics.

Problems facing promotion of astronomy in Arab countries

NASA Astrophysics Data System (ADS)

Osman, Anas M. I.

Promotion of astronomy in Arab countries is facing many scientific and technical problems. Teaching astronomy starts very late in schools, with very simple and limited courses. Many teachers lack a suitable astronomical background, which can lead to incorrect understanding by students of many astronomical ideas and phenomena. Teaching astronomy at higher levels is also very limited, for example: among the 16 universities in Egypt, astronomy is taught in only two faculties of science, just for two years. Graduate students find many difficulties in obtaining jobs related to astronomical activities and this is a serious limitation on the attraction of the study of astronomy. On the other hand, astronomical institutions are suffering from a serious lack of the new sophisticated equipment, while the budget allotted for maintenance is very small, and there is a serious shortage of technical staff. The training of astronomers and technicians is badly needed, since good research work depends on modern technological equipment and the complicated software used in controlling such equipment and in data analysis. Good libraries are needed for promotion of astronomy especially, the Internet facilities available for the staff is very limited. The effects of culture are very clear; many authorities in developing countries believe that astronomy is a luxury. Finally, most of astronomers are engaged with a lot of administration for all matters, so the free time left for science is very limited.

High accuracy step gauge interferometer

NASA Astrophysics Data System (ADS)

Byman, V.; Jaakkola, T.; Palosuo, I.; Lassila, A.

2018-05-01

Step gauges are convenient transfer standards for the calibration of coordinate measuring machines. A novel interferometer for step gauge calibrations implemented at VTT MIKES is described. The four-pass interferometer follows Abbe’s principle and measures the position of the inductive probe attached to a measuring head. The measuring head of the instrument is connected to a balanced boom above the carriage by a piezo translation stage. A key part of the measuring head is an invar structure on which the inductive probe and the corner cubes of the measuring arm of the interferometer are attached. The invar structure can be elevated so that the probe is raised without breaking the laser beam. During probing, the bending of the probe and the interferometer readings are recorded and the measurement face position is extrapolated to zero force. The measurement process is fully automated and the face positions of the steps can be measured up to a length of 2 m. Ambient conditions are measured continuously and the refractive index of air is compensated for. Before measurements the step gauge is aligned with an integrated 2D coordinate measuring system. The expanded uncertainty of step gauge calibration is U=\\sqrt{{{(64 nm)}2}+{{(88× {{10}-9}L)}2}} .

The focusing effect in backward Raman amplification in plasma

NASA Astrophysics Data System (ADS)

Li, Zhaoli; Peng, Hao; Zuo, Yanlei; Su, Jingxin; Yang, Suhui

2018-04-01

In this paper, the focusing effect on backward Raman amplification in plasma is investigated. A fluid model, used to simulate the backward Raman amplification and including the relativistic, ponderomotive, and thermal self-focusing and the mutual-focusing effect simultaneously, is proposed and investigated. The focusing effect is shown to severely distort the profile of the seed when the seed intensity was as high as 10 17 W/cm2. Reducing the plasma density can relax the focusing effect, but at the cost of decreasing the amplification efficiency. Changing the profile of the seed has a limited effect on mitigating the focusing effect. A Gaussian profile of the pump and a defocusing shape of the plasma density seem to be an effective way to mitigate the focusing effect without decreasing the amplification efficiency.

Instructional Design-Based Research on Problem Solving Strategies

ERIC Educational Resources Information Center

Emre-Akdogan, Elçin; Argün, Ziya

2016-01-01

The main goal of this study is to find out the effect of the instructional design method on the enhancement of problem solving abilities of students. Teaching sessions were applied to ten students who are in 11th grade, to teach them problem solving strategies which are working backwards, finding pattern, adopting a different point of view,…

Evaluation of a parallel implementation of the learning portion of the backward error propagation neural network: experiments in artifact identification.

PubMed Central

Sittig, D. F.; Orr, J. A.

1991-01-01

Various methods have been proposed in an attempt to solve problems in artifact and/or alarm identification including expert systems, statistical signal processing techniques, and artificial neural networks (ANN). ANNs consist of a large number of simple processing units connected by weighted links. To develop truly robust ANNs, investigators are required to train their networks on huge training data sets, requiring enormous computing power. We implemented a parallel version of the backward error propagation neural network training algorithm in the widely portable parallel programming language C-Linda. A maximum speedup of 4.06 was obtained with six processors. This speedup represents a reduction in total run-time from approximately 6.4 hours to 1.5 hours. We conclude that use of the master-worker model of parallel computation is an excellent method for obtaining speedups in the backward error propagation neural network training algorithm. PMID:1807607

An application of forward-backward difference approximation method on the optimal control problem in the transmission of tuberculosis model

NASA Astrophysics Data System (ADS)

Rahmah, Z.; Subartini, B.; Djauhari, E.; Anggriani, N.; Supriatna, A. K.

2017-03-01

Tuberculosis (TB) is a disease that is infected by the bacteria Mycobacterium tuberculosis. The World Health Organization (WHO) recommends to implement the Baccilus Calmete Guerin (BCG) vaccine in toddler aged two to three months to be protected from the infection. This research explores the numerical simulation of forward-backward difference approximation method on the model of TB transmission considering this vaccination program. The model considers five compartments of sub-populations, i.e. susceptible, vaccinated, exposed, infected, and recovered human sub-populations. We consider here the vaccination as a control variable. The results of the simulation showed that vaccination can indeed reduce the number of infected human population.

Enhancing multi-step quantum state tomography by PhaseLift

NASA Astrophysics Data System (ADS)

Lu, Yiping; Zhao, Qing

2017-09-01

Multi-photon system has been studied by many groups, however the biggest challenge faced is the number of copies of an unknown state are limited and far from detecting quantum entanglement. The difficulty to prepare copies of the state is even more serious for the quantum state tomography. One possible way to solve this problem is to use adaptive quantum state tomography, which means to get a preliminary density matrix in the first step and revise it in the second step. In order to improve the performance of adaptive quantum state tomography, we develop a new distribution scheme of samples and extend it to three steps, that is to correct it once again based on the density matrix obtained in the traditional adaptive quantum state tomography. Our numerical results show that the mean square error of the reconstructed density matrix by our new method is improved to the level from 10-4 to 10-9 for several tested states. In addition, PhaseLift is also applied to reduce the required storage space of measurement operator.

Forward-backward asymmetry in top quark-antiquark production

DOE PAGES

Abazov, Victor Mukhamedovich

2011-12-12

We present a measurement of forward-backward asymmetry in top quark-antiquark production in proton-antiproton collisions in the final state containing a lepton and at least four jets. Using a dataset corresponding to an integrated luminosity of 5.4 fb -1, collected by the D0 experiment at the Fermilab Tevatron Collider, we measure the t{bar t} forward-backward asymmetry to be (9.2 ± 3.7)% at the reconstruction level. When corrected for detector acceptance and resolution, the asymmetry is found to be (19.6 ± 6.5)%. We also measure a corrected asymmetry based on the lepton from a top quark decay, found to be (15.2 ±more » 4.0)%. The results are compared to predictions based on the next-to-leading-order QCD generator mc@nlo. The sensitivity of the measured and predicted asymmetries to the modeling of gluon radiation is discussed.« less

One-side forward-backward asymmetry at the LHC

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

Wang Youkai; Xiao Bo; Zhu Shouhua

2011-01-01

Forward-backward asymmetry A{sub FB} is an essential observable to study the nature of coupling in the standard model and physics beyond the standard model, as shown at LEP and Tevatron. As a proton-proton collider, the LHC does not have the preferred direction contrary to her counterparts, namely, LEP and Tevatron. Therefore, A{sub FB} is not applicable at the LHC. However, for the proton the momentum of the valence quark is usually larger than that of the sea quark. Utilizing this feature we have defined a so-called one-side forward-backward asymmetry A{sub OFB} for the top quark pair production at the LHCmore » in the previous work. In this paper we extend our studies to the charged leptons and bottom quarks as the final states. Our numerical results show that at the LHC A{sub OFB} can be utilized to study the nature of the couplings once enough events are collected.« less

Going Backward to Go Forward: The Critical Role of Regressive Movement in Cognitive Development

ERIC Educational Resources Information Center

Feldman, David Henry; Benjamin, Ann C.

2004-01-01

There is by this point no doubt that backward, regressive, negative or degenerative movements occur in cognitive development. The question is "why?" The challenges of the phenomenon have been and continue to be mainly two: identify the range and variety of systematic backward movements that appear in development; and, provide better and better…

Neighboring extremals of dynamic optimization problems with path equality constraints

NASA Technical Reports Server (NTRS)

Lee, A. Y.

1988-01-01

Neighboring extremals of dynamic optimization problems with path equality constraints and with an unknown parameter vector are considered in this paper. With some simplifications, the problem is reduced to solving a linear, time-varying two-point boundary-value problem with integral path equality constraints. A modified backward sweep method is used to solve this problem. Two example problems are solved to illustrate the validity and usefulness of the solution technique.

Counting-backward test for executive function in idiopathic normal pressure hydrocephalus.

PubMed

Kanno, S; Saito, M; Hayashi, A; Uchiyama, M; Hiraoka, K; Nishio, Y; Hisanaga, K; Mori, E

2012-10-01

The aim of this study was to develop and validate a bedside test for executive function in patients with idiopathic normal pressure hydrocephalus (INPH). Twenty consecutive patients with INPH and 20 patients with Alzheimer's disease (AD) were enrolled in this study. We developed the counting-backward test for evaluating executive function in patients with INPH. Two indices that are considered to be reflective of the attention deficits and response suppression underlying executive dysfunction in INPH were calculated: the first-error score and the reverse-effect index. Performance on both the counting-backward test and standard neuropsychological tests for executive function was assessed in INPH and AD patients. The first-error score, reverse-effect index and the scores from the standard neuropsychological tests for executive function were significantly lower for individuals in the INPH group than in the AD group. The two indices for the counting-backward test in the INPH group were strongly correlated with the total scores for Frontal Assessment Battery and Phonemic Verbal Fluency. The first-error score was also significantly correlated with the error rate of the Stroop colour-word test and the score of the go/no-go test. In addition, we found that the first-error score highly distinguished patients with INPH from those with AD using these tests. The counting-backward test is useful for evaluating executive dysfunction in INPH and for differentiating between INPH and AD patients. In particular, the first-error score may reflect deficits in the response suppression related to executive dysfunction in INPH. © 2012 John Wiley & Sons A/S.

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,…

Multi-Time Step Service Restoration for Advanced Distribution Systems and Microgrids

DOE PAGES

Chen, Bo; Chen, Chen; Wang, Jianhui; ...

2017-07-07

Modern power systems are facing increased risk of disasters that can cause extended outages. The presence of remote control switches (RCSs), distributed generators (DGs), and energy storage systems (ESS) provides both challenges and opportunities for developing post-fault service restoration methodologies. Inter-temporal constraints of DGs, ESS, and loads under cold load pickup (CLPU) conditions impose extra complexity on problem formulation and solution. In this paper, a multi-time step service restoration methodology is proposed to optimally generate a sequence of control actions for controllable switches, ESSs, and dispatchable DGs to assist the system operator with decision making. The restoration sequence is determinedmore » to minimize the unserved customers by energizing the system step by step without violating operational constraints at each time step. The proposed methodology is formulated as a mixed-integer linear programming (MILP) model and can adapt to various operation conditions. Furthermore, the proposed method is validated through several case studies that are performed on modified IEEE 13-node and IEEE 123-node test feeders.« less

Multi-Time Step Service Restoration for Advanced Distribution Systems and Microgrids

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

Chen, Bo; Chen, Chen; Wang, Jianhui

Modern power systems are facing increased risk of disasters that can cause extended outages. The presence of remote control switches (RCSs), distributed generators (DGs), and energy storage systems (ESS) provides both challenges and opportunities for developing post-fault service restoration methodologies. Inter-temporal constraints of DGs, ESS, and loads under cold load pickup (CLPU) conditions impose extra complexity on problem formulation and solution. In this paper, a multi-time step service restoration methodology is proposed to optimally generate a sequence of control actions for controllable switches, ESSs, and dispatchable DGs to assist the system operator with decision making. The restoration sequence is determinedmore » to minimize the unserved customers by energizing the system step by step without violating operational constraints at each time step. The proposed methodology is formulated as a mixed-integer linear programming (MILP) model and can adapt to various operation conditions. Furthermore, the proposed method is validated through several case studies that are performed on modified IEEE 13-node and IEEE 123-node test feeders.« less

Step by Step: Biology Undergraduates' Problem-Solving Procedures during Multiple-Choice Assessment.

PubMed

Prevost, Luanna B; Lemons, Paula P

2016-01-01

This study uses the theoretical framework of domain-specific problem solving to explore the procedures students use to solve multiple-choice problems about biology concepts. We designed several multiple-choice problems and administered them on four exams. We trained students to produce written descriptions of how they solved the problem, and this allowed us to systematically investigate their problem-solving procedures. We identified a range of procedures and organized them as domain general, domain specific, or hybrid. We also identified domain-general and domain-specific errors made by students during problem solving. We found that students use domain-general and hybrid procedures more frequently when solving lower-order problems than higher-order problems, while they use domain-specific procedures more frequently when solving higher-order problems. Additionally, the more domain-specific procedures students used, the higher the likelihood that they would answer the problem correctly, up to five procedures. However, if students used just one domain-general procedure, they were as likely to answer the problem correctly as if they had used two to five domain-general procedures. Our findings provide a categorization scheme and framework for additional research on biology problem solving and suggest several important implications for researchers and instructors. © 2016 L. B. Prevost and P. P. Lemons. CBE—Life Sciences Education © 2016 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Step by Step: Biology Undergraduates' Problem-Solving Procedures during Multiple-Choice Assessment

ERIC Educational Resources Information Center

Prevost, Luanna B.; Lemons, Paula P.

2016-01-01

This study uses the theoretical framework of domain-specific problem solving to explore the procedures students use to solve multiple-choice problems about biology concepts. We designed several multiple-choice problems and administered them on four exams. We trained students to produce written descriptions of how they solved the problem, and this…

Sequence-dependent base pair stepping dynamics in XPD helicase unwinding

PubMed Central

Qi, Zhi; Pugh, Robert A; Spies, Maria; Chemla, Yann R

2013-01-01

Helicases couple the chemical energy of ATP hydrolysis to directional translocation along nucleic acids and transient duplex separation. Understanding helicase mechanism requires that the basic physicochemical process of base pair separation be understood. This necessitates monitoring helicase activity directly, at high spatio-temporal resolution. Using optical tweezers with single base pair (bp) resolution, we analyzed DNA unwinding by XPD helicase, a Superfamily 2 (SF2) DNA helicase involved in DNA repair and transcription initiation. We show that monomeric XPD unwinds duplex DNA in 1-bp steps, yet exhibits frequent backsteps and undergoes conformational transitions manifested in 5-bp backward and forward steps. Quantifying the sequence dependence of XPD stepping dynamics with near base pair resolution, we provide the strongest and most direct evidence thus far that forward, single-base pair stepping of a helicase utilizes the spontaneous opening of the duplex. The proposed unwinding mechanism may be a universal feature of DNA helicases that move along DNA phosphodiester backbones. DOI: http://dx.doi.org/10.7554/eLife.00334.001 PMID:23741615

Assessing Backwards Integration as a Method of KBO Family Finding

NASA Astrophysics Data System (ADS)

Benfell, Nathan; Ragozzine, Darin

2018-04-01

The age of young asteroid collisional families can sometimes be determined by using backwards n-body integrations of the solar system. This method is not used for discovering young asteroid families and is limited by the unpredictable influence of the Yarkovsky effect on individual specific asteroids over time. Since these limitations are not as important for objects in the Kuiper belt, Marcus et al. 2011 suggested that backwards integration could be used to discover and characterize collisional families in the outer solar system. But various challenges present themselves when running precise and accurate 4+ Gyr integrations of Kuiper Belt objects. We have created simulated families of Kuiper Belt Objects with identical starting locations and velocity distributions, based on the Haumea Family. We then ran several long-term test integrations to observe the effect of various simulation parameters on integration results. These integrations were then used to investigate which parameters are of enough significance to require inclusion in the integration. Thereby we determined how to construct long-term integrations that both yield significant results and require manageable processing power. Additionally, we have tested the use of backwards integration as a method of discovery of potential young families in the Kuiper Belt.

Walk this way: approaching bodies can influence the processing of faces.

PubMed

Pilz, Karin S; Vuong, Quoc C; Bülthoff, Heinrich H; Thornton, Ian M

2011-01-01

A highly familiar type of movement occurs whenever a person walks towards you. In the present study, we investigated whether this type of motion has an effect on face processing. We took a range of different 3D head models and placed them on a single, identical 3D body model. The resulting figures were animated to approach the observer. In a first series of experiments, we used a sequential matching task to investigate how the motion of an approaching person affects immediate responses to faces. We compared observers' responses following approach sequences to their performance with figures walking backwards (receding motion) or remaining still. Observers were significantly faster in responding to a target face that followed an approach sequence, compared to both receding and static primes. In a second series of experiments, we investigated long-term effects of motion using a delayed visual search paradigm. After studying moving or static avatars, observers searched for target faces in static arrays of varying set sizes. Again, observers were faster at responding to faces that had been learned in the context of an approach sequence. Together these results suggest that the context of a moving body influences face processing, and support the hypothesis that our visual system has mechanisms that aid the encoding of behaviourally-relevant and familiar dynamic events. Copyright © 2010 Elsevier B.V. All rights reserved.

Backwards compatible high dynamic range video compression

NASA Astrophysics Data System (ADS)

Dolzhenko, Vladimir; Chesnokov, Vyacheslav; Edirisinghe, Eran A.

2014-02-01

This paper presents a two layer CODEC architecture for high dynamic range video compression. The base layer contains the tone mapped video stream encoded with 8 bits per component which can be decoded using conventional equipment. The base layer content is optimized for rendering on low dynamic range displays. The enhancement layer contains the image difference, in perceptually uniform color space, between the result of inverse tone mapped base layer content and the original video stream. Prediction of the high dynamic range content reduces the redundancy in the transmitted data while still preserves highlights and out-of-gamut colors. Perceptually uniform colorspace enables using standard ratedistortion optimization algorithms. We present techniques for efficient implementation and encoding of non-uniform tone mapping operators with low overhead in terms of bitstream size and number of operations. The transform representation is based on human vision system model and suitable for global and local tone mapping operators. The compression techniques include predicting the transform parameters from previously decoded frames and from already decoded data for current frame. Different video compression techniques are compared: backwards compatible and non-backwards compatible using AVC and HEVC codecs.

Investigation of enhanced forward and backward anti-stokes Raman signals in lithium niobate waveguides

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

Li, Da; Hong, Pengda; Ding, Yujie J., E-mail: yding300@gmail.com

2015-07-07

We have observed enhancements of the anti-Stokes Raman signals generated in lithium niobate waveguides in the forward and backward configurations by at least one order of magnitude under the pump power of the microwatt level. These output signals were measured using a single photon detector. The forward and backward propagating anti-Stokes signals exhibited different spectral features.

Fractional Steps methods for transient problems on commodity computer architectures

NASA Astrophysics Data System (ADS)

Krotkiewski, M.; Dabrowski, M.; Podladchikov, Y. Y.

2008-12-01

Fractional Steps methods are suitable for modeling transient processes that are central to many geological applications. Low memory requirements and modest computational complexity facilitates calculations on high-resolution three-dimensional models. An efficient implementation of Alternating Direction Implicit/Locally One-Dimensional schemes for an Opteron-based shared memory system is presented. The memory bandwidth usage, the main bottleneck on modern computer architectures, is specially addressed. High efficiency of above 2 GFlops per CPU is sustained for problems of 1 billion degrees of freedom. The optimized sequential implementation of all 1D sweeps is comparable in execution time to copying the used data in the memory. Scalability of the parallel implementation on up to 8 CPUs is close to perfect. Performing one timestep of the Locally One-Dimensional scheme on a system of 1000 3 unknowns on 8 CPUs takes only 11 s. We validate the LOD scheme using a computational model of an isolated inclusion subject to a constant far field flux. Next, we study numerically the evolution of a diffusion front and the effective thermal conductivity of composites consisting of multiple inclusions and compare the results with predictions based on the differential effective medium approach. Finally, application of the developed parabolic solver is suggested for a real-world problem of fluid transport and reactions inside a reservoir.

Air stepping in response to optic flows that move Toward and Away from the neonate.

PubMed

Barbu-Roth, Marianne; Anderson, David I; Desprès, Adeline; Streeter, Ryan J; Cabrol, Dominique; Trujillo, Michael; Campos, Joseph J; Provasi, Joëlle

2014-07-01

To shed further light on the perceptual regulation of newborn stepping, we compared neonatal air stepping in response to optic flows simulating forward or backward displacement with stepping forward on a surface. Twenty-two 3-day-olds performed four 60 s trials in which they stepped forward on a table (Tactile) or in the air in response to a pattern that moved toward (Toward) or away (Away) from them or was static (Static). Significantly more steps were taken in the Tactile and Toward conditions than the Static condition. The Away condition was intermediate to the other conditions. The knee joint activity across the entire trial was significantly greater in the Toward than the Away condition. Within-limb kinematics and between-limb coordination were very similar for steps taken in the air and on the table, particularly in the Toward and Tactile conditions. These findings highlight that visual and tactile stimulation can equally elicit neonatal stepping. © 2013 Wiley Periodicals, Inc.

Calibration of stereo rigs based on the backward projection process

NASA Astrophysics Data System (ADS)

Gu, Feifei; Zhao, Hong; Ma, Yueyang; Bu, Penghui; Zhao, Zixin

2016-08-01

High-accuracy 3D measurement based on binocular vision system is heavily dependent on the accurate calibration of two rigidly-fixed cameras. In most traditional calibration methods, stereo parameters are iteratively optimized through the forward imaging process (FIP). However, the results can only guarantee the minimal 2D pixel errors, but not the minimal 3D reconstruction errors. To address this problem, a simple method to calibrate a stereo rig based on the backward projection process (BPP) is proposed. The position of a spatial point can be determined separately from each camera by planar constraints provided by the planar pattern target. Then combined with pre-defined spatial points, intrinsic and extrinsic parameters of the stereo-rig can be optimized by minimizing the total 3D errors of both left and right cameras. An extensive performance study for the method in the presence of image noise and lens distortions is implemented. Experiments conducted on synthetic and real data demonstrate the accuracy and robustness of the proposed method.

Illumination normalization of face image based on illuminant direction estimation and improved Retinex.

PubMed

Yi, Jizheng; Mao, Xia; Chen, Lijiang; Xue, Yuli; Rovetta, Alberto; Caleanu, Catalin-Daniel

2015-01-01

Illumination normalization of face image for face recognition and facial expression recognition is one of the most frequent and difficult problems in image processing. In order to obtain a face image with normal illumination, our method firstly divides the input face image into sixteen local regions and calculates the edge level percentage in each of them. Secondly, three local regions, which meet the requirements of lower complexity and larger average gray value, are selected to calculate the final illuminant direction according to the error function between the measured intensity and the calculated intensity, and the constraint function for an infinite light source model. After knowing the final illuminant direction of the input face image, the Retinex algorithm is improved from two aspects: (1) we optimize the surround function; (2) we intercept the values in both ends of histogram of face image, determine the range of gray levels, and stretch the range of gray levels into the dynamic range of display device. Finally, we achieve illumination normalization and get the final face image. Unlike previous illumination normalization approaches, the method proposed in this paper does not require any training step or any knowledge of 3D face and reflective surface model. The experimental results using extended Yale face database B and CMU-PIE show that our method achieves better normalization effect comparing with the existing techniques.

Nanoscale dissolution and growth on anhydrite cleavage faces

NASA Astrophysics Data System (ADS)

Pina, Carlos M.

2009-12-01

In situ atomic force microscopy (AFM) was used to study the molecular-scale reactivity of anhydrite (1 0 0), (0 1 0), and (0 0 1) faces exposed to water and CaSO 4 aqueous solutions at room temperature. In pure water, dissolution occurs by step retreat and etch pit nucleation and growth. Both the kinetics of the step retreat and the shape of the etch pits are surface-specific and crystallographically controlled. In CaSO 4 aqueous solutions with concentrations ranging from 0.030 mol/l to 0.075 mol/l, the growth kinetics on anhydrite (1 0 0) and (0 1 0) faces was studied. Growth is also strongly controlled by crystallographic constraints and occurs exclusively from pre-existing step edges by highly anisotropic spreading of monolayers (˜3.5 Å in height). The AFM observations demonstrate that monolayer growth can occur on anhydrite (0 1 0) and (1 0 0) faces even from slightly supersaturated solutions. In addition, the comparison of the step kinetics on anhydrite faces shows that the mechanisms of step dissolution and growth are essentially the same, with the direction of migration of crystal building units being reversed at the anhydrite saturation point. Moreover, the analysis of both high resolution AFM images and lateral force microscopy (LFM) images confirms that the newly-formed monolayers are anhydrite growing in structural continuity with the original (1 0 0) and (0 1 0) surfaces. However, the formation of the first monolayers is metastable and two-dimensional nucleation and further multilayer growth of anhydrite are strongly inhibited even at high supersaturations.

Standoff Detection of Trace Molecules by Remote High Gain Backward Lasing in Air

DTIC Science & Technology

2016-09-17

vapor it is essential. Backward lasing from two simultaneously pumped, closely separated regions in the air provides a method for the reduction of pulse... inversion in an atomic species, leading to “cavityless” lasing. Lasing occurs from the population inversion that is created in the focal volume of...provide a reference that is capable of removing these pulse-to- pulse variations, a second, simultaneous backward lasing beam is generated using the same

The Screening Test for Emotional Problems--Teacher-Report Version (Step-T): Studies of Reliability and Validity

ERIC Educational Resources Information Center

Erford, Bradley T.; Butler, Caitlin; Peacock, Elizabeth

2015-01-01

The Screening Test for Emotional Problems-Teacher Version (STEP-T) was designed to identify students aged 7-17 years with wide-ranging emotional disturbances. Coefficients alpha and test-retest reliability were adequate for all subscales except Anxiety. The hypothesized five-factor model fit the data very well and external aspects of validity were…

Backward jump continuous-time random walk: An application to market trading

NASA Astrophysics Data System (ADS)

Gubiec, Tomasz; Kutner, Ryszard

2010-10-01

The backward jump modification of the continuous-time random walk model or the version of the model driven by the negative feedback was herein derived for spatiotemporal continuum in the context of a share price evolution on a stock exchange. In the frame of the model, we described stochastic evolution of a typical share price on a stock exchange with a moderate liquidity within a high-frequency time scale. The model was validated by satisfactory agreement of the theoretical velocity autocorrelation function with its empirical counterpart obtained for the continuous quotation. This agreement is mainly a result of a sharp backward correlation found and considered in this article. This correlation is a reminiscence of such a bid-ask bounce phenomenon where backward price jump has the same or almost the same length as preceding jump. We suggested that this correlation dominated the dynamics of the stock market with moderate liquidity. Although assumptions of the model were inspired by the market high-frequency empirical data, its potential applications extend beyond the financial market, for instance, to the field covered by the Le Chatelier-Braun principle of contrariness.

Backward jump continuous-time random walk: an application to market trading.

PubMed

Gubiec, Tomasz; Kutner, Ryszard

2010-10-01

The backward jump modification of the continuous-time random walk model or the version of the model driven by the negative feedback was herein derived for spatiotemporal continuum in the context of a share price evolution on a stock exchange. In the frame of the model, we described stochastic evolution of a typical share price on a stock exchange with a moderate liquidity within a high-frequency time scale. The model was validated by satisfactory agreement of the theoretical velocity autocorrelation function with its empirical counterpart obtained for the continuous quotation. This agreement is mainly a result of a sharp backward correlation found and considered in this article. This correlation is a reminiscence of such a bid-ask bounce phenomenon where backward price jump has the same or almost the same length as preceding jump. We suggested that this correlation dominated the dynamics of the stock market with moderate liquidity. Although assumptions of the model were inspired by the market high-frequency empirical data, its potential applications extend beyond the financial market, for instance, to the field covered by the Le Chatelier-Braun principle of contrariness.

Effects of computer-based graphic organizers to solve one-step word problems for middle school students with mild intellectual disability: A preliminary study.

PubMed

Sheriff, Kelli A; Boon, Richard T

2014-08-01

The purpose of this study was to examine the effects of computer-based graphic organizers, using Kidspiration 3© software, to solve one-step word problems. Participants included three students with mild intellectual disability enrolled in a functional academic skills curriculum in a self-contained classroom. A multiple probe single-subject research design (Horner & Baer, 1978) was used to evaluate the effectiveness of computer-based graphic organizers to solving mathematical one-step word problems. During the baseline phase, the students completed a teacher-generated worksheet that consisted of nine functional word problems in a traditional format using a pencil, paper, and a calculator. In the intervention and maintenance phases, the students were instructed to complete the word problems using a computer-based graphic organizer. Results indicated that all three of the students improved in their ability to solve the one-step word problems using computer-based graphic organizers compared to traditional instructional practices. Limitations of the study and recommendations for future research directions are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Alcohol Use and Problems in Mandated College Students: A Randomized Clinical Trial Using Stepped Care

PubMed Central

Borsari, Brian; Hustad, John T.P.; Mastroleo, Nadine R.; Tevyaw, Tracy O’Leary; Barnett, Nancy P.; Kahler, Christopher W.; Short, Erica Eaton; Monti, Peter M.

2012-01-01

Objective Over the past two decades, colleges and universities have seen a large increase in the number of students referred to the administration for alcohol policies violations. However, a substantial portion of mandated students may not require extensive treatment. Stepped care may maximize treatment efficiency and greatly reduce the demands on campus alcohol programs. Method Participants in the study (N = 598) were college students mandated to attend an alcohol program following a campus-based alcohol citation. All participants received Step 1: a 15-minute Brief Advice session that included the provision of a booklet containing advice to reduce drinking. Participants were assessed six weeks after receiving the Brief Advice, and those who continued to exhibit risky alcohol use (n = 405) were randomized to Step 2, a 60–90 minute brief motivational intervention (BMI) (n = 211) or an assessment-only control (n = 194). Follow-up assessments were conducted 3, 6, and 9 months after Step 2. Results Results indicated that the participants who received a BMI significantly reduced the number of alcohol-related problems compared to those who received assessment-only, despite no significant group differences in alcohol use. In addition, low risk drinkers (n = 102; who reported low alcohol use and related harms at 6-week follow-up and were not randomized to stepped care) showed a stable alcohol use pattern throughout the follow-up period, indicating they required no additional intervention. Conclusion Stepped care is an efficient and cost-effective method to reduce harms associated with alcohol use by mandated students. PMID:22924334

Persisting mental health problems among AIDS-orphaned children in South Africa.

PubMed

Cluver, Lucie D; Orkin, Mark; Gardner, Frances; Boyes, Mark E

2012-04-01

  By 2008, 12 million children in sub-Saharan Africa were orphaned by AIDS. Cross-sectional studies show psychological problems for AIDS-orphaned children, but until now no longitudinal study has explored enduring psychological effects of AIDS-orphanhood in the developing world.   A 4-year longitudinal follow-up of AIDS-orphaned children with control groups of other-orphans and non-orphans. 1021 children (M = 13.4 years, 50% female, 98% isiXhosa-speaking) were interviewed in 2005 and followed up in 2009 with 71% retention (49% female, M = 16.9 years), in poor urban South African settlements. Children were interviewed using sociodemographic questionnaires and well-validated standardised scales for assessing depression, anxiety, and post-traumatic stress. Data were analysed using mixed-design ANOVA and backward-stepping regression.   AIDS-orphaned children showed higher depression, anxiety, and post-traumatic stress disorder (PTSD) scores in both 2005 and 2009 when compared with other-orphans and non-orphans. Backward-stepping regression, controlling for baseline mental health, and sociodemographic cofactors such as age, gender, and type of bereavement, revealed that being AIDS-orphaned in 2005 was associated with depression, anxiety, and PTSD scores in 2009. This was not the case for other-orphaned or non-orphaned children. Age interacted with orphan status, such that there was a steep rise in psychological distress in the AIDS-orphaned group, but no rise with age amongst other-orphans and non-orphans.   Negative mental health outcomes amongst AIDS-orphaned children are maintained and worsen over a 4-year period. It is important that psychosocial support programmes are sustained, and focus on youth as well as young children. © 2011 The Authors. Journal of Child Psychology and Psychiatry © 2011 Association for Child and Adolescent Mental Health.

Forward-backward multiplicity correlations of target fragments in nucleus-emulsion collisions at a few hundred MeV/u

NASA Astrophysics Data System (ADS)

Zhang, Dong-Hai; Chen, Yan-Ling; Wang, Guo-Rong; Li, Wang-Dong; Wang, Qing; Yao, Ji-Jie; Zhou, Jian-Guo; Li, Rong; Li, Jun-Sheng; Li, Hui-Ling

2015-01-01

The forward-backward multiplicity and correlations of a target evaporated fragment (black track particle) and target recoiled proton (grey track particle) emitted from 150 A MeV 4He, 290 A MeV 12C, 400 A MeV 12C, 400 A MeV 20Ne and 500 A MeV 56Fe induced different types of nuclear emulsion target interactions are investigated. It is found that the forward and backward averaged multiplicity of a grey, black and heavily ionized track particle increases with the increase of the target size. The averaged multiplicity of a forward black track particle, backward black track particle, and backward grey track particle do not depend on the projectile size and energy, but the averaged multiplicity of a forward grey track particle increases with an increase of projectile size and energy. The backward grey track particle multiplicity distribution follows an exponential decay law and the decay constant decreases with an increase of target size. The backward-forward multiplicity correlations follow linear law which is independent of the projectile size and energy, and the saturation effect is observed in some heavy target data sets.

Analysis of temporal shear stress gradients during the onset phase of flow over a backward-facing step.

PubMed

Haidekker, M A; White, C R; Frangos, J A

2001-10-01

Endothelial cells in blood vessels are exposed to bloodflow and thus fluid shear stress. In arterial bifurcations and stenoses, disturbed flow causes zones of recirculation and stagnation, which are associated with both spatial and temporal gradients of shear stress. Such gradients have been linked to the generation of atherosclerotic plaques. For in-vitro studies of endothelial cell responses, the sudden-expansion flow chamber has been widely used and described. A two-dimensional numerical simulation of the onset phase of flow through the chamber was performed. The wall shear stress action on the bottom plate was computed as a function of time and distance from the sudden expansion. The results showed that depending on the time for the flow to be established, significant temporal gradients occurred close to the second stagnation point of flow. Slowly ramping the flow over 15 s instead of 200 ms reduces the temporal gradients by a factor of 300, while spatial gradients are reduced by 23 percent. Thus, the effects of spatial and temporal gradients can be observed separately. In experiments on endothelial cells, disturbed flow stimulated cell proliferation only when flow onset was sudden. The spatial patterns of proliferation rate match the exposure to temporal gradients. This study provides information on the dynamics of spatial and temporal gradients to which the cells are exposed in a sudden-expansion flow chamber and relates them to changes in the onset phase of flow.

Developing a New Quantitative Account of Backward Masking

ERIC Educational Resources Information Center

Francis, Gregory

2003-01-01

A new general explanation for u-shaped backward masking is analyzed and found to predict shifts in the interstimulus interval (ISI) that produces strongest masking. This predicted shift is then compared to six sets of masking data. The resulting comparisons force the general explanation to make certain assumptions to account for the data. In this…

Aerodynamic losses calculation of a turbine blade with film cooling with forward and backward injection by numerical method

NASA Astrophysics Data System (ADS)

Prajapati, Anil

Thermal efficiency and power output of gas turbines can be increased by increasing the turbine blade inlet temperature. However, the main problem is the durability of the turbine blade due to the thermal stress on it at high temperature. This has led to the development of film cooling technology, in which coolant is injected from a series of cooling holes made on the blade surface to form an insulating blanket over the blade surface. However, it has to pay the aerodynamic penalties due to the injection of coolant, which are not fully understood. Pressure loss coefficient is one of the easy and widely used parameters to determine the aerodynamic loss occurred on a turbine blade. The losses occurred on the turbine blade with forward injection and backward injection cooling are studied at a different blowing ratios by a numerical simulation, which shows that the loss is higher in the case of backward injection than in forward injection. Fan-shaped cooling holes are also considered to compare with the cylindrical holes. It is observed that the loss is increased due to the fan-shaped holes in the forward injection whereas there is not a substantial difference due to the fan-shaped holes in the backward injection. The aerodynamic loss due to the location of coolant injection is studied by using injection from the leading edge, pressure side, suction side and trailing edge respectively. The study is performed to determine the effect of incidence angles and coolant injection angles on the aerodynamic loss.

Effect of Face-to-face Education, Problem-based Learning, and Goldstein Systematic Training Model on Quality of Life and Fatigue among Caregivers of Patients with Diabetes.

PubMed

Masoudi, Reza; Soleimani, Mohammad Ali; Yaghoobzadeh, Ameneh; Baraz, Shahram; Hakim, Ashrafalsadat; Chan, Yiong H

2017-01-01

Education is a fundamental component for patients with diabetes to achieve good glycemic control. In addition, selecting the appropriate method of education is one of the most effective factors in the quality of life. The present study aimed to evaluate the effect of face-to-face education, problem-based learning, and Goldstein systematic training model on the quality of life (QOL) and fatigue among caregivers of patients with diabetes. This randomized clinical trial was conducted in Hajar Hospital (Shahrekord, Iran) in 2012. The study subjects consisted of 105 family caregivers of patients with diabetes. The participants were randomly assigned to three intervention groups (35 caregivers in each group). For each group, 5-h training sessions were held separately. QOL and fatigue were evaluated immediately before and after the intervention, and after 1, 2, 3, and 4 months of intervention. There was a significant increase in QOL for all the three groups. Both the problem-based learning and the Goldstein method showed desirable QOL improvement over time. The desired educational intervention for fatigue reduction during the 4-month post-intervention period was the Goldstein method. A significant reduction was observed in fatigue in all three groups after the intervention ( P < 0.001). The results of the present study illustrated that the problem-based learning and Goldstein systematic training model improve the QOL of caregivers of patients with diabetes. In addition, the Goldstein systematic training model had the greatest effect on the reduction of fatigue within 4 months of the intervention.

Learning Opportunities in Synchronous Computer-Mediated Communication and Face-to-Face Interaction

ERIC Educational Resources Information Center

Kim, Hye Yeong

2014-01-01

This study investigated how synchronous computer-mediated communication (SCMC) and face-to-face (F2F) oral interaction influence the way in which learners collaborate in language learning and how they solve their communicative problems. The findings suggest that output modality may affect how learners produce language, attend to linguistic forms,…

FaceIt: face recognition from static and live video for law enforcement

NASA Astrophysics Data System (ADS)

Atick, Joseph J.; Griffin, Paul M.; Redlich, A. N.

1997-01-01

Recent advances in image and pattern recognition technology- -especially face recognition--are leading to the development of a new generation of information systems of great value to the law enforcement community. With these systems it is now possible to pool and manage vast amounts of biometric intelligence such as face and finger print records and conduct computerized searches on them. We review one of the enabling technologies underlying these systems: the FaceIt face recognition engine; and discuss three applications that illustrate its benefits as a problem-solving technology and an efficient and cost effective investigative tool.

Investigating the role of backward walking therapy in alleviating plantar pressure of patients with diabetic peripheral neuropathy.

PubMed

Zhang, Xingguang; Zhang, Yanqi; Gao, Xiaoxiao; Wu, Jinxiao; Jiao, Xiumin; Zhao, Jing; Lv, Xiaofeng

2014-05-01

To investigate the effect of combination therapy of backward walking training and alpha-lipoic acid (ALA) treatment on the distribution of plantar pressure in patients with diabetic peripheral neuropathy (DPN). This study is a double-blinded, randomized controlled trial. The test group was treated with combination therapy of backward walking exercise and ALA (ALA for 2wk, backward walking exercise for 12wk), and the control group only received ALA treatment. Clinical and laboratory setting. Patients with DPN (N=60) were divided into the test group (n=30) or control group (n=30). Backward walking exercise with ALA treatment for the test group; lipoic acid treatment for the control group. Plantar pressure before and after treatment was tested and analyzed with the flatbed plantar pressure measurement system. After treatment, peak plantar pressure in the forefoot dropped for both the test and control groups; peak plantar pressure for the test group dropped significantly. Peak plantar pressure in the medial foot slightly increased for the test group, suggesting a more even distribution of plantar pressure in the test group after treatment. The combination therapy of ALA and backward walking proved to be more effective than ALA monotherapy. Backward walking also proved to have an ameliorating effect on balance ability and muscle strength of patients with DPN. Copyright © 2014 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

A Survey on Sentiment Classification in Face Recognition

NASA Astrophysics Data System (ADS)

Qian, Jingyu

2018-01-01

Face recognition has been an important topic for both industry and academia for a long time. K-means clustering, autoencoder, and convolutional neural network, each representing a design idea for face recognition method, are three popular algorithms to deal with face recognition problems. It is worthwhile to summarize and compare these three different algorithms. This paper will focus on one specific face recognition problem-sentiment classification from images. Three different algorithms for sentiment classification problems will be summarized, including k-means clustering, autoencoder, and convolutional neural network. An experiment with the application of these algorithms on a specific dataset of human faces will be conducted to illustrate how these algorithms are applied and their accuracy. Finally, the three algorithms are compared based on the accuracy result.

Face recognition from unconstrained three-dimensional face images using multitask sparse representation

NASA Astrophysics Data System (ADS)

Bentaieb, Samia; Ouamri, Abdelaziz; Nait-Ali, Amine; Keche, Mokhtar

2018-01-01

We propose and evaluate a three-dimensional (3D) face recognition approach that applies the speeded up robust feature (SURF) algorithm to the depth representation of shape index map, under real-world conditions, using only a single gallery sample for each subject. First, the 3D scans are preprocessed, then SURF is applied on the shape index map to find interest points and their descriptors. Each 3D face scan is represented by keypoints descriptors, and a large dictionary is built from all the gallery descriptors. At the recognition step, descriptors of a probe face scan are sparsely represented by the dictionary. A multitask sparse representation classification is used to determine the identity of each probe face. The feasibility of the approach that uses the SURF algorithm on the shape index map for face identification/authentication is checked through an experimental investigation conducted on Bosphorus, University of Milano Bicocca, and CASIA 3D datasets. It achieves an overall rank one recognition rate of 97.75%, 80.85%, and 95.12%, respectively, on these datasets.

Effects of temporal integration on the shape of visual backward masking functions.

PubMed

Francis, Gregory; Cho, Yang Seok

2008-10-01

Many studies of cognition and perception use a visual mask to explore the dynamics of information processing of a target. Especially important in these applications is the time between the target and mask stimuli. A plot of some measure of target visibility against stimulus onset asynchrony is called a masking function, which can sometimes be monotonic increasing but other times is U-shaped. Theories of backward masking have long hypothesized that temporal integration of the target and mask influences properties of masking but have not connected the influence of integration with the shape of the masking function. With two experiments that vary the spatial properties of the target and mask, the authors provide evidence that temporal integration of the stimuli plays a critical role in determining the shape of the masking function. The resulting data both challenge current theories of backward masking and indicate what changes to the theories are needed to account for the new data. The authors further discuss the implication of the findings for uses of backward masking to explore other aspects of cognition.

Forward and backward inference in spatial cognition.

PubMed

Penny, Will D; Zeidman, Peter; Burgess, Neil

2013-01-01

This paper shows that the various computations underlying spatial cognition can be implemented using statistical inference in a single probabilistic model. Inference is implemented using a common set of 'lower-level' computations involving forward and backward inference over time. For example, to estimate where you are in a known environment, forward inference is used to optimally combine location estimates from path integration with those from sensory input. To decide which way to turn to reach a goal, forward inference is used to compute the likelihood of reaching that goal under each option. To work out which environment you are in, forward inference is used to compute the likelihood of sensory observations under the different hypotheses. For reaching sensory goals that require a chaining together of decisions, forward inference can be used to compute a state trajectory that will lead to that goal, and backward inference to refine the route and estimate control signals that produce the required trajectory. We propose that these computations are reflected in recent findings of pattern replay in the mammalian brain. Specifically, that theta sequences reflect decision making, theta flickering reflects model selection, and remote replay reflects route and motor planning. We also propose a mapping of the above computational processes onto lateral and medial entorhinal cortex and hippocampus.

Labor supply functions of working male and female pharmacists: In search of the backward bend.

PubMed

Carvajal, Manuel J; Deziel, Lisa; Armayor, Graciela M

2012-01-01

Previous research has shown that U.S. pharmacists experience negative elasticities along a backward-bending labor supply function. The presence of a backward bend in the labor supply curve may cause a decrease in the amount of work at a time of labor shortage. Therefore, the determinants of pharmacists' labor supply functions should be explored to assess the impact of this backward bend. To determine whether female and male pharmacist work inputs are influenced by the same factors and estimate where the backward bend occurs, if at all, in their labor supply functions. Data were collected using a survey questionnaire mailed to registered pharmacists in South Florida. Labor supply functions were formulated and tested separately for 558 men and 498 women. The wage rate, other household income, human capital stock, job-related preferences, and opinion variables were hypothesized to explain labor supply differentials. Human capital stock variables included professional experience, holding a specialty board certification, and number of children; job-related preference variables included urban-rural location of work site and main role as a practitioner; and opinion variables included stress, autonomy, fairness in the workplace, flexibility, and job security. Men and women responded differently to identical stimuli, and their supply functions were influenced in different ways by the explanatory variables. Both genders exhibited positive labor supply elasticities greater than those reported in other studies. Both genders' backward bend in their labor supply functions occurred several standard deviations to the right of the mean. The backward bend in the labor supply functions of male and female pharmacists is not likely to affect in the near future the labor market's ability to regulate shortages of practitioners via increases in the wage rate. A more thorough understanding of pharmacists' labor supply functions must address gender issues and differences in response to

Rethinking the lecture: the application of problem based learning methods to atypical contexts.

PubMed

Rogal, Sonya M M; Snider, Paul D

2008-05-01

Problem based learning is a teaching and learning strategy that uses a problematic stimulus as a means of motivating and directing students to develop and acquire knowledge. Problem based learning is a strategy that is typically used with small groups attending a series of sessions. This article describes the principles of problem based learning and its application in atypical contexts; large groups attending discrete, stand-alone sessions. The principles of problem based learning are based on Socratic teaching, constructivism and group facilitation. To demonstrate the application of problem based learning in an atypical setting, this article focuses on the graduate nurse intake from a teaching hospital. The groups are relatively large and meet for single day sessions. The modified applications of problem based learning to meet the needs of atypical groups are described. This article contains a step by step guide of constructing a problem based learning package for large, single session groups. Nurse educators facing similar groups will find they can modify problem based learning to suit their teaching context.

The role of backward cell migration in two-hit mutants' production in the stem cell niche.

PubMed

Bollas, Audrey; Shahriyari, Leili

2017-01-01

It has been discovered that there are two stem cell groups in the intestinal crypts: central stem cells (CeSCs), which are at the very bottom of the crypt, and border stem cells (BSCs), which are located between CeSCs and transit amplifying cells (TAs). Moreover, backward cell migration from BSCs to CeSCs has been observed. Recently, a bi-compartmental stochastic model, which includes CeSCs and BSCs, has been developed to investigate the probability of two-hit mutant production in the stem cell niche. In this project, we improve this stochastic model by adding the probability of backward cell migration to the model. The model suggests that the probability of two-hit mutant production increases when the frequency of backward cell migration increases. Furthermore, a small non-zero probability of backward cell migration leads to the largest range of optimal values for the frequency of symmetric divisions and the portion of divisions at each stem cell compartment in terms of delaying 2-hit mutant production. Moreover, the probability of two-hit mutant production is more sensitive to the probability of symmetric divisions than to the rate of backward cell migrations. The highest probability of two-hit mutant production corresponds to the case when all stem cell's divisions are asymmetric.

The role of backward cell migration in two-hit mutants’ production in the stem cell niche

PubMed Central

Bollas, Audrey

2017-01-01

It has been discovered that there are two stem cell groups in the intestinal crypts: central stem cells (CeSCs), which are at the very bottom of the crypt, and border stem cells (BSCs), which are located between CeSCs and transit amplifying cells (TAs). Moreover, backward cell migration from BSCs to CeSCs has been observed. Recently, a bi-compartmental stochastic model, which includes CeSCs and BSCs, has been developed to investigate the probability of two-hit mutant production in the stem cell niche. In this project, we improve this stochastic model by adding the probability of backward cell migration to the model. The model suggests that the probability of two-hit mutant production increases when the frequency of backward cell migration increases. Furthermore, a small non-zero probability of backward cell migration leads to the largest range of optimal values for the frequency of symmetric divisions and the portion of divisions at each stem cell compartment in terms of delaying 2-hit mutant production. Moreover, the probability of two-hit mutant production is more sensitive to the probability of symmetric divisions than to the rate of backward cell migrations. The highest probability of two-hit mutant production corresponds to the case when all stem cell’s divisions are asymmetric. PMID:28931019

Joint torques and joint reaction forces during squatting with a forward or backward inclined Smith machine.

PubMed

Biscarini, Andrea; Botti, Fabio M; Pettorossi, Vito E

2013-02-01

We developed a biomechanical model to determine the joint torques and loadings during squatting with a backward/forward-inclined Smith machine. The Smith squat allows a large variety of body positioning (trunk tilt, foot placement, combinations of joint angles) and easy control of weight distribution between forefoot and heel. These distinctive aspects of the exercise can be managed concurrently with the equipment inclination selected to unload specific joint structures while activating specific muscle groups. A backward (forward) equipment inclination decreases (increases) knee torque, and compressive tibiofemoral and patellofemoral forces, while enhances (depresses) hip and lumbosacral torques. For small knee flexion angles, the strain-force on the posterior cruciate ligament increases (decreases) with a backward (forward) equipment inclination, whereas for large knee flexion angles, this behavior is reversed. In the 0 to 60 degree range of knee flexion angles, loads on both cruciate ligaments may be simultaneously suppressed by a 30 degree backward equipment inclination and selecting, for each value of the knee angle, specific pairs of ankle and hip angles. The anterior cruciate ligament is safely maintained unloaded by squatting with backward equipment inclination and uniform/forward foot weight distribution. The conditions for the development of anterior cruciate ligament strain forces are clearly explained.

What's in a mask? Information masking with forward and backward visual masks.

PubMed

Davis, Chris; Kim, Jeesun

2011-10-01

Three experiments tested how the physical format and information content of forward and backward masks affected the extent of visual pattern masking. This involved using different types of forward and backward masks with target discrimination measured by percentage correct in the first experiment (with a fixed target duration) and by an adaptive threshold procedure in the last two. The rationale behind the manipulation of the content of the masks stemmed from masking theories emphasizing attentional and/or conceptual factors rather than visual ones. Experiment 1 used word masks and showed that masking was reduced (a masking reduction effect) when the forward and backward masks were the same word (although in different case) compared to when the masks were different words. Experiment 2 tested the extent to which a reduction in masking might occur due to the physical similarity between the forward and backward masks by comparing the effect of the same content of the masks in the same versus different case. The result showed a significant reduction in masking for same content masks but no significant effect of case. The last experiment examined whether the reduction in masking effect would be observed with nonword masks--that is, having no high-level representation. No reduction in masking was found from same compared to different nonword masks (Experiment 3). These results support the view that the conscious perception of a rapidly displayed target stimulus is in part determined by high-level perceptual/cognitive factors concerned with masking stimulus grouping and attention.

Further insight into self-face recognition in schizophrenia patients: Why ambiguity matters.

PubMed

Bortolon, Catherine; Capdevielle, Delphine; Salesse, Robin N; Raffard, Stephane

2016-03-01

Although some studies reported specifically self-face processing deficits in patients with schizophrenia disorder (SZ), it remains unclear whether these deficits rather reflect a more global face processing deficit. Contradictory results are probably due to the different methodologies employed and the lack of control of other confounding factors. Moreover, no study has so far evaluated possible daily life self-face recognition difficulties in SZ. Therefore, our primary objective was to investigate self-face recognition in patients suffering from SZ compared to healthy controls (HC) using an "objective measure" (reaction time and accuracy) and a "subjective measure" (self-report of daily self-face recognition difficulties). Twenty-four patients with SZ and 23 HC performed a self-face recognition task and completed a questionnaire evaluating daily difficulties in self-face recognition. Recognition task material consisted in three different faces (the own, a famous and an unknown) being morphed in steps of 20%. Results showed that SZ were overall slower than HC regardless of the face identity, but less accurate only for the faces containing 60%-40% morphing. Moreover, SZ and HC reported a similar amount of daily problems with self/other face recognition. No significant correlations were found between objective and subjective measures (p > 0.05). The small sample size and relatively mild severity of psychopathology does not allow us to generalize our results. These results suggest that: (1) patients with SZ are as capable of recognizing their own face as HC, although they are susceptible to ambiguity; (2) there are far less self recognition deficits in schizophrenia patients than previously postulated. Copyright © 2015 Elsevier Ltd. All rights reserved.

Bottom-quark forward-backward asymmetry in the standard model and beyond.

PubMed

Grinstein, Benjamín; Murphy, Christopher W

2013-08-09

We computed the bottom-quark forward-backward asymmetry at the Tevatron in the standard model (SM) and for several new physics scenarios. Near the Z pole, the SM bottom asymmetry is dominated by tree level exchanges of electroweak gauge bosons. While above the Z pole, next-to-leading order QCD dominates the SM asymmetry as was the case with the top-quark forward-backward asymmetry. Light new physics, M(NP)≲150  GeV, can cause significant deviations from the SM prediction for the bottom asymmetry. The bottom asymmetry can be used to distinguish between competing new physics (NP) explanations of the top asymmetry based on how the NP interferes with s-channel gluon and Z exchange.

Flight-measured pressure characteristics of aft-facing steps in high Reynolds number flow at Mach numbers of 2.20, 2.50, and 2.80 and comparison with other data

NASA Technical Reports Server (NTRS)

Powers, S. G.

1978-01-01

The YF-12 airplane was studied to determine the pressure characteristics associated with an aft-facing step in high Reynolds number flow for nominal Mach numbers of 2.20, 2.50, and 2.80. Base pressure coefficients were obtained for three step heights. The surface static pressures ahead of and behind the step were measured for the no-step condition and for each of the step heights. A boundary layer rake was used to determine the local boundary layer conditions. The Reynolds number based on the length of flow ahead of the step was approximately 10 to the 8th power and the ratios of momentum thickness to step height ranged from 0.2 to 1.0. Base pressure coefficients were compared with other available data at similar Mach numbers and at ratios of momentum thickness to step height near 1.0. In addition, the data were compared with base pressure coefficients calculated by a semiempirical prediction method. The base pressure ratios are shown to be a function of Reynolds number based on momentum thickness. Profiles of the surface pressures ahead of and behind the step and the local boundary layer conditions are also presented.

Coaching Family Caregivers to Become Better Problem Solvers When Caring for Persons with Advanced Cancer.

PubMed

Dionne-Odom, J Nicholas; Lyons, Kathleen D; Akyar, Imatullah; Bakitas, Marie A

2016-01-01

Family caregivers of persons with advanced cancer often take on responsibilities that present daunting and complex problems. Serious problems that go unresolved may be burdensome and result in negative outcomes for caregivers' psychological and physical health and affect the quality of care delivered to the care recipients with cancer, especially at the end of life. Formal problem-solving training approaches have been developed over the past several decades to assist individuals with managing problems faced in daily life. Several of these problem-solving principles and techniques were incorporated into ENABLE (Educate, Nurture, Advise, Before Life End), an "early" palliative care telehealth intervention for individuals diagnosed with advanced cancer and their family caregivers. A hypothetical case resembling the situations of actual caregiver participants in ENABLE that exemplifies the complex problems that caregivers face is presented, followed by presentation of an overview of ENABLE's problem-solving key principles, techniques, and steps in problem-solving support. Though more research is needed to formally test the use of problem-solving support in social work practice, social workers can easily incorporate these techniques into everyday practice.

Hazardous Continuation Backward in Time in Nonlinear Parabolic Equations, and an Experiment in Deblurring Nonlinearly Blurred Imagery

PubMed Central

Carasso, Alfred S

2013-01-01

Identifying sources of ground water pollution, and deblurring nanoscale imagery as well as astronomical galaxy images, are two important applications involving numerical computation of parabolic equations backward in time. Surprisingly, very little is known about backward continuation in nonlinear parabolic equations. In this paper, an iterative procedure originating in spectroscopy in the 1930’s, is adapted into a useful tool for solving a wide class of 2D nonlinear backward parabolic equations. In addition, previously unsuspected difficulties are uncovered that may preclude useful backward continuation in parabolic equations deviating too strongly from the linear, autonomous, self adjoint, canonical model. This paper explores backward continuation in selected 2D nonlinear equations, by creating fictitious blurred images obtained by using several sharp images as initial data in these equations, and capturing the corresponding solutions at some positive time T. Successful backward continuation from t=T to t = 0, would recover the original sharp image. Visual recognition provides meaningful evaluation of the degree of success or failure in the reconstructed solutions. Instructive examples are developed, illustrating the unexpected influence of certain types of nonlinearities. Visually and statistically indistinguishable blurred images are presented, with vastly different deblurring results. These examples indicate that how an image is nonlinearly blurred is critical, in addition to the amount of blur. The equations studied represent nonlinear generalizations of Brownian motion, and the blurred images may be interpreted as visually expressing the results of novel stochastic processes. PMID:26401430

Hazardous Continuation Backward in Time in Nonlinear Parabolic Equations, and an Experiment in Deblurring Nonlinearly Blurred Imagery.

PubMed

Carasso, Alfred S

2013-01-01

Identifying sources of ground water pollution, and deblurring nanoscale imagery as well as astronomical galaxy images, are two important applications involving numerical computation of parabolic equations backward in time. Surprisingly, very little is known about backward continuation in nonlinear parabolic equations. In this paper, an iterative procedure originating in spectroscopy in the 1930's, is adapted into a useful tool for solving a wide class of 2D nonlinear backward parabolic equations. In addition, previously unsuspected difficulties are uncovered that may preclude useful backward continuation in parabolic equations deviating too strongly from the linear, autonomous, self adjoint, canonical model. This paper explores backward continuation in selected 2D nonlinear equations, by creating fictitious blurred images obtained by using several sharp images as initial data in these equations, and capturing the corresponding solutions at some positive time T. Successful backward continuation from t=T to t = 0, would recover the original sharp image. Visual recognition provides meaningful evaluation of the degree of success or failure in the reconstructed solutions. Instructive examples are developed, illustrating the unexpected influence of certain types of nonlinearities. Visually and statistically indistinguishable blurred images are presented, with vastly different deblurring results. These examples indicate that how an image is nonlinearly blurred is critical, in addition to the amount of blur. The equations studied represent nonlinear generalizations of Brownian motion, and the blurred images may be interpreted as visually expressing the results of novel stochastic processes.

Dynamic subfilter-scale stress model for large-eddy simulations

NASA Astrophysics Data System (ADS)

Rouhi, A.; Piomelli, U.; Geurts, B. J.

2016-08-01

We present a modification of the integral length-scale approximation (ILSA) model originally proposed by Piomelli et al. [Piomelli et al., J. Fluid Mech. 766, 499 (2015), 10.1017/jfm.2015.29] and apply it to plane channel flow and a backward-facing step. In the ILSA models the length scale is expressed in terms of the integral length scale of turbulence and is determined by the flow characteristics, decoupled from the simulation grid. In the original formulation the model coefficient was constant, determined by requiring a desired global contribution of the unresolved subfilter scales (SFSs) to the dissipation rate, known as SFS activity; its value was found by a set of coarse-grid calculations. Here we develop two modifications. We de-fine a measure of SFS activity (based on turbulent stresses), which adds to the robustness of the model, particularly at high Reynolds numbers, and removes the need for the prior coarse-grid calculations: The model coefficient can be computed dynamically and adapt to large-scale unsteadiness. Furthermore, the desired level of SFS activity is now enforced locally (and not integrated over the entire volume, as in the original model), providing better control over model activity and also improving the near-wall behavior of the model. Application of the local ILSA to channel flow and a backward-facing step and comparison with the original ILSA and with the dynamic model of Germano et al. [Germano et al., Phys. Fluids A 3, 1760 (1991), 10.1063/1.857955] show better control over the model contribution in the local ILSA, while the positive properties of the original formulation (including its higher accuracy compared to the dynamic model on coarse grids) are maintained. The backward-facing step also highlights the advantage of the decoupling of the model length scale from the mesh.

A Planning Tool for Incorporating Backward Design, Active Learning, and Authentic Assessment in the College Classroom

ERIC Educational Resources Information Center

Reynolds, Heather L.; Kearns, Katherine Dowell

2017-01-01

Backward course design is a compelling strategy for achieving results-based, student-centered learning. The backward course-design approach is first to identify student-learning outcomes, then the means of assessing the outcomes, and lastly the classroom activities that would support the learning outcomes. With demonstrated success at improving…

Rapid stepping test towards virtual visual objects: Feasibility and convergent validity in older adults.

PubMed

Hutzler, Yeshayahu; Korsensky, Olga; Laufer, Yocheved

2017-01-01

Rapid voluntary stepping has been recognized as an important measure of balance control. The purpose of this study was to assess the feasibility and convergent validity of a Rapid Stepping Test protocol utilizing a virtual reality SeeMeTM system (VR-RST) in elderly ambulatory and independent individuals living in a community residential home. Associations between step execution times determined by the system and the Activities-specific Balance Confidence (ABC) Questionnaire, and clinical measures of balance performance in the MiniBESTest and Timed Up and Go (TUG) test, were established in 60 participants (mean age 88.2 ± 5.0 years). All participants completed the study. The correlations of the ABC questionnaire and the clinical tests with VR-RST forward and backward stepping were moderate (ρ rage 0.42-0.52), and weak to moderate with sideward stepping (ρ rage 0.32-0.52). Moderate to strong correlations were found across stepping directions (ρ rage 0.45-0.87). Findings support the test's feasibility and validity and confirm the utility of the VR-RST as an assessment tool in an elderly population.

Redesigning an Introductory Language Curriculum: A Backward Design Approach

ERIC Educational Resources Information Center

Paesani, Kate

2017-01-01

In response to calls for curricular change in foreign language programs and institutional requirements to evaluate programmatic effectiveness, this article presents a backward design approach to the redesign of an introductory French curriculum grounded in the framing concept of cultural literacy. In addition, data from student evaluations,…

Modeling Spatial and Temporal Aspects of Visual Backward Masking

ERIC Educational Resources Information Center

Hermens, Frouke; Luksys, Gediminas; Gerstner, Wulfram; Herzog, Michael H.; Ernst, Udo

2008-01-01

Visual backward masking is a versatile tool for understanding principles and limitations of visual information processing in the human brain. However, the mechanisms underlying masking are still poorly understood. In the current contribution, the authors show that a structurally simple mathematical model can explain many spatial and temporal…

Context-dependent JPEG backward-compatible high-dynamic range image compression

NASA Astrophysics Data System (ADS)

Korshunov, Pavel; Ebrahimi, Touradj

2013-10-01

High-dynamic range (HDR) imaging is expected, together with ultrahigh definition and high-frame rate video, to become a technology that may change photo, TV, and film industries. Many cameras and displays capable of capturing and rendering both HDR images and video are already available in the market. The popularity and full-public adoption of HDR content is, however, hindered by the lack of standards in evaluation of quality, file formats, and compression, as well as large legacy base of low-dynamic range (LDR) displays that are unable to render HDR. To facilitate the wide spread of HDR usage, the backward compatibility of HDR with commonly used legacy technologies for storage, rendering, and compression of video and images are necessary. Although many tone-mapping algorithms are developed for generating viewable LDR content from HDR, there is no consensus of which algorithm to use and under which conditions. We, via a series of subjective evaluations, demonstrate the dependency of the perceptual quality of the tone-mapped LDR images on the context: environmental factors, display parameters, and image content itself. Based on the results of subjective tests, it proposes to extend JPEG file format, the most popular image format, in a backward compatible manner to deal with HDR images also. An architecture to achieve such backward compatibility with JPEG is proposed. A simple implementation of lossy compression demonstrates the efficiency of the proposed architecture compared with the state-of-the-art HDR image compression.

Steps in Solution Growth: Revised Gibbs-Thomson Law, Turbulence and Morphological Stability

NASA Technical Reports Server (NTRS)

Chernov, A. A.; Rashkovich, L. N.; Vekilov, P. G.

2004-01-01

Two groups of new phenomena revealed by AFM and high resolution optical interferometry on crystal faces growing from solutions will be discussed. 1. Spacing between strongly polygonized spiral steps with low less than 10(exp -2) kink density on lysozyme and K- biphtalate do not follow the Burton-cabrera-Frank theory. The critical length of the yet immobile first Short step segment adjacent to a pinning defect (dislocation, stacking fault) is many times longer than that following from the step free energy. The low-kink density steps are typical of many growth conditions and materials, including low temperature gas phase epitaxy and MBE. 2. The step bunching pattern on the approx. 1 cm long { 110) KDP face growing from the turbulent solution flow (Re (triple bonds) 10(exp 4), solution flow rate approx. 1 m/s) suggests that the step bunch height does not increase infinitely as the bunch path on the crystal face rises, as is usually observed on large KDP crystals. The mechanism controlling the maximal bunch width and height is based on the drag of the solution depleted by the step bunch down thc solution stream. It includes splitting, coagulation and interlacing of bunches

"Growing trees backwards": Description of a stand reconstruction model

Treesearch

Jonathan D. Bakker; Andrew J. Sanchez Meador; Peter Z. Fule; David W. Huffman; Margaret M. Moore

2008-01-01

We describe an individual-tree model that uses contemporary measurements to "grow trees backward" and reconstruct past tree diameters and stand structure in ponderosa pine dominated stands of the Southwest. Model inputs are contemporary structural measurements of all snags, logs, stumps, and living trees, and radial growth measurements, if available. Key...

The effect of cane use on the compensatory step following posterior perturbations.

PubMed

Hall, Courtney D; Jensen, Jody L

2004-08-01

The compensatory step is a critical component of the balance response and is impaired in older fallers. The purpose of this research was to examine whether utilization of a cane modified the compensatory step response following external posterior perturbations. Single subject withdrawal design was employed. Single subject statistical analysis--the standard deviation bandwidth-method--supplemented visual analysis of the data. Four older adults (range: 73-83 years) with balance impairment who habitually use a cane completed this study. Subjects received a series of sudden backward pulls that were large enough to elicit compensatory stepping. We examined the following variables both with and without cane use: timing of cane loading relative to step initiation and center of mass acceleration, stability margin, center of mass excursion and velocity, step length and width. No participant loaded the cane prior to initiation of the first compensatory step. There was no effect of cane use on the stability margin, nor was there an effect of cane use on center of mass excursion or velocity, or step length or width. These data suggest that cane use does not necessarily improve balance recovery following an external posterior perturbation when the individual is forced to rely on compensatory stepping. Instead these data suggest that the strongest factor in modifying step characteristics is experience with the perturbation.

Self-stigma and the intention to seek psychological help online compared to face-to-face.

PubMed

Wallin, Emma; Maathz, Pernilla; Parling, Thomas; Hursti, Timo

2018-07-01

The present study aims to investigate the impact of help-seeking self-stigma on the preference and intention to seek psychological treatment delivered online compared to face-to-face. This study uses survey data from two Swedish samples. Sample 1 consists of 267 students (78.7% women) with a mean age of 24.5 (SD = 6.1). Sample 2 consists of 195 primary care patients (56.9% women) with a mean age of 45.3 (SD = 17.7). The number of participants who preferred online treatment was higher if seeking psychological help for a perceived stigmatized problem compared to mental health problems in general. The odds ratios for choosing treatment online over face-to-face were 6.41, 95% CI [4.05, 10.14] in Sample 1 and 11.19, 95% CI [5.29, 23.67] in Sample 2. In addition, findings suggest that higher levels of help-seeking self-stigma predicted higher intention to seek treatment online compared to face-to-face. Our results suggest that online interventions may facilitate help-seeking among individuals deterred by stigma. © 2018 Wiley Periodicals, Inc.

Improving liver fibrosis diagnosis based on forward and backward second harmonic generation signals

NASA Astrophysics Data System (ADS)

Peng, Qiwen; Zhuo, Shuangmu; So, Peter T. C.; Yu, Hanry

2015-02-01

The correlation of forward second harmonic generation (SHG) signal and backward SHG signal in different liver fibrosis stages was investigated. We found that three features, including the collagen percentage for forward SHG, the collagen percentage for backward SHG, and the average intensity ratio of two kinds of SHG signals, can quantitatively stage liver fibrosis in thioacetamide-induced rat model. We demonstrated that the combination of all three features by using a support vector machine classification algorithm can provide a more accurate prediction than each feature alone in fibrosis diagnosis.

Cognitive disorganisation in schizotypy is associated with deterioration in visual backward masking.

PubMed

Cappe, Céline; Herzog, Michael H; Herzig, Daniela A; Brand, Andreas; Mohr, Christine

2012-12-30

To understand the causes of schizophrenia, a search for stable markers (endophenotypes) is ongoing. In previous years, we have shown that the shine-through visual backward masking paradigm meets the most important characteristics of an endophenotype. Here, we tested masking performance differences between healthy students with low and high schizotypy scores as determined by the self-report O-Life questionnaire assessing schizotypy along three dimensions, i.e. positive schizotypy (unusual experiences), cognitive disorganisation, and negative schizotypy (introvertive anhedonia). Forty participants performed the shine-through backward masking task and a classical cognitive test, the Wisconsin Card Sorting Task (WCST). We found that visual backward masking was impaired for students scoring high as compared to low on the cognitive disorganisation dimension, whereas the positive and negative schizotypy dimensions showed no link to masking performance. We also found group differences for students scoring high and low on the cognitive disorganisation factor for the WCST. These findings indicate that the shine-through paradigm is sensitive to differences in schizotypy which are closely linked with the pathological expression in schizophrenia. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

ECLIPS: An extended CLIPS for backward chaining and goal-directed reasoning

NASA Technical Reports Server (NTRS)

Homeier, Peter V.; Le, Thach C.

1991-01-01

Realistic production systems require an integrated combination of forward and backward reasoning to reflect appropriately the processes of natural human expert reasoning. A control mechanism that consists solely of forward reasoning is not an effective way to promptly focus the system's attention as calculation proceeds. Often, expert system programmers will attempt to compensate for this lack by using data to enforce the desired goal directed control structure. This approach is inherently flawed in that it is attempting to use data to fulfill the role of control. This paper will describe our implementation of backward chaining in C Language Integrated Production System (CLIPS), and show how this has shortened and simplified various CLIPS programs. This work was done at the Aerospace Corporation, and has general applicability.

Original and Mirror Face Images and Minimum Squared Error Classification for Visible Light Face Recognition.

PubMed

Wang, Rong

2015-01-01

In real-world applications, the image of faces varies with illumination, facial expression, and poses. It seems that more training samples are able to reveal possible images of the faces. Though minimum squared error classification (MSEC) is a widely used method, its applications on face recognition usually suffer from the problem of a limited number of training samples. In this paper, we improve MSEC by using the mirror faces as virtual training samples. We obtained the mirror faces generated from original training samples and put these two kinds of samples into a new set. The face recognition experiments show that our method does obtain high accuracy performance in classification.

Forward and Backward Inference in Spatial Cognition

PubMed Central

Penny, Will D.; Zeidman, Peter; Burgess, Neil

2013-01-01

This paper shows that the various computations underlying spatial cognition can be implemented using statistical inference in a single probabilistic model. Inference is implemented using a common set of ‘lower-level’ computations involving forward and backward inference over time. For example, to estimate where you are in a known environment, forward inference is used to optimally combine location estimates from path integration with those from sensory input. To decide which way to turn to reach a goal, forward inference is used to compute the likelihood of reaching that goal under each option. To work out which environment you are in, forward inference is used to compute the likelihood of sensory observations under the different hypotheses. For reaching sensory goals that require a chaining together of decisions, forward inference can be used to compute a state trajectory that will lead to that goal, and backward inference to refine the route and estimate control signals that produce the required trajectory. We propose that these computations are reflected in recent findings of pattern replay in the mammalian brain. Specifically, that theta sequences reflect decision making, theta flickering reflects model selection, and remote replay reflects route and motor planning. We also propose a mapping of the above computational processes onto lateral and medial entorhinal cortex and hippocampus. PMID:24348230

Student’s thinking process in solving word problems in geometry

NASA Astrophysics Data System (ADS)

Khasanah, V. N.; Usodo, B.; Subanti, S.

2018-05-01

This research aims to find out the thinking process of seventh grade of Junior High School in solve word problem solving of geometry. This research was descriptive qualitative research. The subject of the research was selected based on sex and differences in mathematical ability. Data collection was done based on student’s work test, interview, and observation. The result of the research showed that there was no difference of thinking process between male and female with high mathematical ability, and there were differences of thinking process between male and female with moderate and low mathematical ability. Also, it was found that male with moderate mathematical ability took a long time in the step of making problem solving plans. While female with moderate mathematical ability took a long time in the step of understanding the problems. The importance of knowing the thinking process of students in solving word problem solving were that the teacher knows the difficulties faced by students and to minimize the occurrence of the same error in problem solving. Teacher could prepare the right learning strategies which more appropriate with student’s thinking process.

Ultrafast forward and backward electron transfer dynamics of coumarin 337 in hydrogen-bonded anilines as studied with femtosecond UV-pump/IR-probe spectroscopy.

PubMed

Ghosh, Hirendra N; Verma, Sandeep; Nibbering, Erik T J

2011-02-10

Femtosecond infrared spectroscopy is used to study both forward and backward electron transfer (ET) dynamics between coumarin 337 (C337) and the aromatic amine solvents aniline (AN), N-methylaniline (MAN), and N,N-dimethylaniline (DMAN), where all the aniline solvents can donate an electron but only AN and MAN can form hydrogen bonds with C337. The formation of a hydrogen bond with AN and MAN is confirmed with steady state FT-IR spectroscopy, where the C═O stretching vibration is a direct marker mode for hydrogen bond formation. Transient IR absorption measurements in all solvents show an absorption band at 2166 cm(-1), which has been attributed to the C≡N stretching vibration of the C337 radical anion formed after ET. Forward electron transfer dynamics is found to be biexponential with time constants τ(ET)(1) = 500 fs, τ(ET)(2) = 7 ps in all solvents. Despite the presence of hydrogen bonds of C337 with the solvents AN and MAN, no effect has been found on the forward electron transfer step. Because of the absence of an H/D isotope effect on the forward electron transfer reaction of C337 in AN, hydrogen bonds are understood to play a minor role in mediating electron transfer. In contrast, direct π-orbital overlap between C337 and the aromatic amine solvents causes ultrafast forward electron transfer dynamics. Backward electron transfer dynamics, in contrast, is dependent on the solvent used. Standard Marcus theory explains the observed backward electron transfer rates.

A multi-view face recognition system based on cascade face detector and improved Dlib

NASA Astrophysics Data System (ADS)

Zhou, Hongjun; Chen, Pei; Shen, Wei

2018-03-01

In this research, we present a framework for multi-view face detect and recognition system based on cascade face detector and improved Dlib. This method is aimed to solve the problems of low efficiency and low accuracy in multi-view face recognition, to build a multi-view face recognition system, and to discover a suitable monitoring scheme. For face detection, the cascade face detector is used to extracted the Haar-like feature from the training samples, and Haar-like feature is used to train a cascade classifier by combining Adaboost algorithm. Next, for face recognition, we proposed an improved distance model based on Dlib to improve the accuracy of multiview face recognition. Furthermore, we applied this proposed method into recognizing face images taken from different viewing directions, including horizontal view, overlooks view, and looking-up view, and researched a suitable monitoring scheme. This method works well for multi-view face recognition, and it is also simulated and tested, showing satisfactory experimental results.

Back pain is associated with changes in loading pattern throughout forward and backward bending.

PubMed

Shum, Gary L K; Crosbie, Jack; Lee, Raymond Y W

2010-12-01

Experimental study to determine the kinetics of the lumbar spine (LS) and hips during forward and backward bending. To investigate the effects of back pain, with and without a positive straight leg raise (SLR) sign, on the loading patterns in the LS and hip during forward and backward bending. Forward and backward bending are important components of many functional activities and are part of routine clinical examination. However, there is a little information about the loading patterns during forward and backward bending in people with back pain with or without a positive SLR sign. Twenty asymptomatic participants, 20 back pain participants, and 20 participants with back pain and a positive SLR sign performed 3 continuous cycles of forward and backward bending. Electromagnetic sensors were attached to body segments to measure their kinematics while 2 nonconductive force plates gathered ground reaction force data. A biomechanical model was used to determine the loading pattern in LS and hips. Although the loading on the LS at the end of the range decreased significantly, the loading at the early and middle ranges of forward bending actually increased significantly in people with back pain, especially in those with positive SLR sign. This suggests that resistance to movement is significantly increased in people with back pain during this movement. This study suggested that it is not sufficient to study the spine at the end of range only, but a complete description of the loading patterns throughout the range is required. Although the maximum range of motion of the spine is reduced in people with back pain, there is a significant increase in the moment acting through the range, particularly in those with a positive SLR sign.

Semisupervised kernel marginal Fisher analysis for face recognition.

PubMed

Wang, Ziqiang; Sun, Xia; Sun, Lijun; Huang, Yuchun

2013-01-01

Dimensionality reduction is a key problem in face recognition due to the high-dimensionality of face image. To effectively cope with this problem, a novel dimensionality reduction algorithm called semisupervised kernel marginal Fisher analysis (SKMFA) for face recognition is proposed in this paper. SKMFA can make use of both labelled and unlabeled samples to learn the projection matrix for nonlinear dimensionality reduction. Meanwhile, it can successfully avoid the singularity problem by not calculating the matrix inverse. In addition, in order to make the nonlinear structure captured by the data-dependent kernel consistent with the intrinsic manifold structure, a manifold adaptive nonparameter kernel is incorporated into the learning process of SKMFA. Experimental results on three face image databases demonstrate the effectiveness of our proposed algorithm.

High-speed video analysis of forward and backward spattered blood droplets

NASA Astrophysics Data System (ADS)

Comiskey, Patrick; Yarin, Alexander; Attinger, Daniel

2017-11-01

High-speed videos of blood spatter due to a gunshot taken by the Ames Laboratory Midwest Forensics Resource Center are analyzed. The videos used in this analysis were focused on a variety of targets hit by a bullet which caused either forward, backward, or both types of blood spatter. The analysis process utilized particle image velocimetry and particle analysis software to measure drop velocities as well as the distributions of the number of droplets and their respective side view area. This analysis revealed that forward spatter results in drops travelling twice as fast compared to backward spatter, while both types of spatter contain drops of approximately the same size. Moreover, the close-to-cone domain in which drops are issued is larger in forward spatter than in the backward one. The inclination angle of the bullet as it penetrates the target is seen to play a significant role in the directional preference of the spattered blood. Also, the aerodynamic drop-drop interaction, muzzle gases, bullet impact angle, as well as the aerodynamic wake of the bullet are seen to greatly influence the flight of the drops. The aim of this study is to provide a quantitative basis for current and future research on bloodstain pattern analysis. This work was financially supported by the United States National Institute of Justice (award NIJ 2014-DN-BXK036).

Backward and forward Monte Carlo method for vector radiative transfer in a two-dimensional graded index medium

NASA Astrophysics Data System (ADS)

Qian, Lin-Feng; Shi, Guo-Dong; Huang, Yong; Xing, Yu-Ming

2017-10-01

In vector radiative transfer, backward ray tracing is seldom used. We present a backward and forward Monte Carlo method to simulate vector radiative transfer in a two-dimensional graded index medium, which is new and different from the conventional Monte Carlo method. The backward and forward Monte Carlo method involves dividing the ray tracing into two processes backward tracing and forward tracing. In multidimensional graded index media, the trajectory of a ray is usually a three-dimensional curve. During the transport of a polarization ellipse, the curved ray trajectory will induce geometrical effects and cause Stokes parameters to continuously change. The solution processes for a non-scattering medium and an anisotropic scattering medium are analysed. We also analyse some parameters that influence the Stokes vector in two-dimensional graded index media. The research shows that the Q component of the Stokes vector cannot be ignored. However, the U and V components of the Stokes vector are very small.

Memory Asymmetry of Forward and Backward Associations in Recognition Tasks

PubMed Central

Yang, Jiongjiong; Zhu, Zijian; Mecklinger, Axel; Fang, Zhiyong; Li, Han

2013-01-01

There is an intensive debate on whether memory for serial order is symmetric. The objective of this study was to explore whether associative asymmetry is modulated by memory task (recognition vs. cued recall). Participants were asked to memorize word triples (Experiment 1–2) or pairs (Experiment 3–6) during the study phase. They then recalled the word by a cue during a cued recall task (Experiment 1–4), and judged whether the presented two words were in the same or in a different order compared to the study phase during a recognition task (Experiment 1–6). To control for perceptual matching between the study and test phase, participants were presented with vertical test pairs when they made directional judgment in Experiment 5. In Experiment 6, participants also made associative recognition judgments for word pairs presented at the same or the reversed position. The results showed that forward associations were recalled at similar levels as backward associations, and that the correlations between forward and backward associations were high in the cued recall tasks. On the other hand, the direction of forward associations was recognized more accurately (and more quickly) than backward associations, and their correlations were comparable to the control condition in the recognition tasks. This forward advantage was also obtained for the associative recognition task. Diminishing positional information did not change the pattern of associative asymmetry. These results suggest that associative asymmetry is modulated by cued recall and recognition manipulations, and that direction as a constituent part of a memory trace can facilitate associative memory. PMID:22924326

Selected computations of transonic cavity flows

NASA Technical Reports Server (NTRS)

Atwood, Christopher A.

1993-01-01

An efficient diagonal scheme implemented in an overset mesh framework has permitted the analysis of geometrically complex cavity flows via the Reynolds averaged Navier-Stokes equations. Use of rapid hyperbolic and algebraic grid methods has allowed simple specification of critical turbulent regions with an algebraic turbulence model. Comparisons between numerical and experimental results are made in two dimensions for the following problems: a backward-facing step; a resonating cavity; and two quieted cavity configurations. In three-dimensions the flow about three early concepts of the stratospheric Observatory For Infrared Astronomy (SOFIA) are compared to wind-tunnel data. Shedding frequencies of resolved shear layer structures are compared against experiment for the quieted cavities. The results demonstrate the progress of computational assessment of configuration safety and performance.

Evidence of forward-backward multiplicity correlation at SPS energy

NASA Astrophysics Data System (ADS)

Bhoumik, Gopa; Bhattacharyya, Swarnapratim; Deb, Argha; Ghosh, Dipak

In this paper, a detailed study of two-particle rapidity correlation has been presented by measuring the dynamical fluctuation variable σc2 in forward and backward pseudo-rapidity window of shower particles produced in the relativistic heavy ion collision, 16O-AgBr interactions at 60AGeV and 32S-AgBr interactions at 200AGeV. Variations of σc2 with rapidity gap between forward and backward zones and with the width of each zone have been studied. For both cases, σc2 increase with increasing either width of the zone or gap between the zones. Our findings show the presence of strong long-range correlation. Comparison of experimental results with MC-RAND events confirms the present correlation to be dynamical in nature. We have also compared our results with FRITIOF and UrQMD events. Such events also show the presence of correlation, but found to fail to reproduce the experimental results both quantitatively and qualitatively. Strength of correlation is dependent on the centrality of collision for experimental events, it decreases with centrality.

Clustering Millions of Faces by Identity.

PubMed

Otto, Charles; Wang, Dayong; Jain, Anil K

2018-02-01

Given a large collection of unlabeled face images, we address the problem of clustering faces into an unknown number of identities. This problem is of interest in social media, law enforcement, and other applications, where the number of faces can be of the order of hundreds of million, while the number of identities (clusters) can range from a few thousand to millions. To address the challenges of run-time complexity and cluster quality, we present an approximate Rank-Order clustering algorithm that performs better than popular clustering algorithms (k-Means and Spectral). Our experiments include clustering up to 123 million face images into over 10 million clusters. Clustering results are analyzed in terms of external (known face labels) and internal (unknown face labels) quality measures, and run-time. Our algorithm achieves an F-measure of 0.87 on the LFW benchmark (13 K faces of 5,749 individuals), which drops to 0.27 on the largest dataset considered (13 K faces in LFW + 123M distractor images). Additionally, we show that frames in the YouTube benchmark can be clustered with an F-measure of 0.71. An internal per-cluster quality measure is developed to rank individual clusters for manual exploration of high quality clusters that are compact and isolated.

A computational investigation of feedforward and feedback processing in metacontrast backward masking

PubMed Central

Silverstein, David N.

2015-01-01

In human perception studies, visual backward masking has been used to understand the temporal dynamics of subliminal vs. conscious perception. When a brief target stimulus is followed by a masking stimulus after a short interval of <100 ms, performance on the target is impaired when the target and mask are in close spatial proximity. While the psychophysical properties of backward masking have been studied extensively, there is still debate on the underlying cortical dynamics. One prevailing theory suggests that the impairment of target performance due to the mask is the result of lateral inhibition between the target and mask in feedforward processing. Another prevailing theory suggests that this impairment is due to the interruption of feedback processing of the target by the mask. This computational study demonstrates that both aspects of these theories may be correct. Using a biophysical model of V1 and V2, visual processing was modeled as interacting neocortical attractors, which must propagate up the visual stream. If an activating target attractor in V1 is quiesced enough with lateral inhibition from a mask, or not reinforced by recurrent feedback, it is more likely to burn out before becoming fully active and progressing through V2 and beyond. Results are presented which simulate metacontrast backward masking with an increasing stimulus interval and with the presence and absence of feedback activity. This showed that recurrent feedback diminishes backward masking effects and can make conscious perception more likely. One model configuration presented a metacontrast noise mask in the same hypercolumns as the target, and produced type-A masking. A second model configuration presented a target line with two parallel adjacent masking lines, and produced type-B masking. Future work should examine how the model extends to more complex spatial mask configurations. PMID:25759672

Steps Toward Effective Production of Speech (STEPS): No. 4--General Information for Parents of a Deaf-Blind Child.

ERIC Educational Resources Information Center

Sheeley, Eugene C.; McQuiddy, Doris

The booklet, one of a series of guides developed by Project STEPS (Steps Toward Effective Production of Speech), presents information for parents and deaf-blind children. Total deafness and blindness and the problems of deafness and blindness are considered, as are the nature of deaf-blindness and its special problems (e.g., eating problems,…

Top quark forward-backward asymmetry and same-sign top quark pairs.

PubMed

Berger, Edmond L; Cao, Qing-Hong; Chen, Chuan-Ren; Li, Chong Sheng; Zhang, Hao

2011-05-20

The top quark forward-backward asymmetry measured at the Tevatron collider shows a large deviation from standard model expectations. Among possible interpretations, a nonuniversal Z' model is of particular interest as it naturally predicts a top quark in the forward region of large rapidity. To reproduce the size of the asymmetry, the couplings of the Z' to standard model quarks must be large, inevitably leading to copious production of same-sign top quark pairs at the energies of the Large Hadron Collider (LHC). We explore the discovery potential for tt and ttj production in early LHC experiments at 7-8 TeV and conclude that if no tt signal is observed with 1 fb⁻¹ of integrated luminosity, then a nonuniversal Z' alone cannot explain the Tevatron forward-backward asymmetry.

The efficiency of backward magnetic-pulse processing

NASA Astrophysics Data System (ADS)

Kudasov, Yu. B.; Maslov, D. A.; Surdin, O. M.

2017-01-01

The dependence of the efficiency of magnetic-pulse processing of materials on the pulsed magnetic-field shape has been studied. It is shown that, by using a pulse train instead of a single pulse in the fast-rising component of a magnetic field applied during the backward forming process, it is possible to increase the specific mechanical impulse transferred to a workpiece and, thus, improve the efficiency of processing. Possible applications of the proposed method to removing dents from car chassis and aircraft parts are considered

Forward-backward multiplicity correlations in sNN=200 GeV Au+Au collisions

NASA Astrophysics Data System (ADS)

Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Chai, Z.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Hauer, M.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Noucier, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Seals, H.; Sedykh, I.; Skulski, W.; Smith, C. E.; Stankiewicz, M. A.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tang, J.-L.; Tonjes, M. B.; Trzupek, A.; Vale, C.; Nieuwenhuizen, G. J. Van; Vaurynovich, S. S.; Verdier, R.; Veres, G. I.; Wenger, E.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

2006-07-01

Forward-backward correlations of charged-particle multiplicities in symmetric bins in pseudorapidity are studied to gain insight into the underlying correlation structure of particle production in Au+Au collisions. The PHOBOS detector is used to measure integrated multiplicities in bins centered at η, defined within |η|<3, and covering intervals Δη. The variance σC2 of a suitably defined forward-backward asymmetry variable C is calculated as a function of η,Δη, and centrality. It is found to be sensitive to short-range correlations, and the concept of “clustering” is used to interpret comparisons to phenomenological models.

A Journey Backwards: History through Style in Children's Fiction

ERIC Educational Resources Information Center

Ringrose, Christopher

2007-01-01

A & C Black's "Flashbacks" series invites its readers to "Read a "Flashback"..take a journey backwards in time". There are several ways in which children's fiction has encouraged its readers to engage with and care about history: through the presence of ghosts, through frame stories, time travel, or simply setting the narrative in the past.…

Visual cryptography for face privacy

NASA Astrophysics Data System (ADS)

Ross, Arun; Othman, Asem A.

2010-04-01

We discuss the problem of preserving the privacy of a digital face image stored in a central database. In the proposed scheme, a private face image is dithered into two host face images such that it can be revealed only when both host images are simultaneously available; at the same time, the individual host images do not reveal the identity of the original image. In order to accomplish this, we appeal to the field of Visual Cryptography. Experimental results confirm the following: (a) the possibility of hiding a private face image in two unrelated host face images; (b) the successful matching of face images that are reconstructed by superimposing the host images; and (c) the inability of the host images, known as sheets, to reveal the identity of the secret face image.

Neural mechanisms of single corrective steps evoked in the standing rabbit

PubMed Central

Hsu, L.-J.; Zelenin, P. V.; Lyalka, V. F.; Vemula, M. G.; Orlovsky, G. N.; Deliagina, T. G.

2017-01-01

Single steps in different directions are often used for postural corrections. However, our knowledge about the neural mechanisms underlying their generation is scarce. This study was aimed to characterize the corrective steps generated in response to disturbances of the basic body configuration caused by forward, backward or outward displacement of the hindlimb, as well as to reveal location in the CNS of the corrective step generating mechanisms. Video recording of the motor response to translation of the supporting surface under the hindlimb along with contact forces and activity of back and limb muscles was performed in freely standing intact and in fixed postmammillary rabbits. In intact rabbits, displacement of the hindlimb in any direction caused a lateral trunk movement towards the contralateral hindlimb, and then a corrective step in the direction opposite to the initial displacement. The time difference between onsets of these two events varied considerably. The EMG pattern in the supporting hindlimb was similar for all directions of corrective steps. It caused the increase in the limb stiffness. EMG pattern in the stepping limb differed in steps with different directions. In postmammillary rabbits the corrective stepping movements, as well as EMG patterns in both stepping and standing hindlimbs were similar to those observed in intact rabbits. This study demonstrates that the corrective trunk and limb movements are generated by separate mechanisms activated by sensory signals from the deviated limb. The neuronal networks generating postural corrective steps reside in the brainstem, cerebellum, and spinal cord. PMID:28215990

This Mechanistic Step Is ''Productive'': Organic Chemistry Students' Backward-Oriented Reasoning

ERIC Educational Resources Information Center

Caspari, I.; Weinrich, M. L.; Sevian, H.; Graulich, N.

2018-01-01

If an organic chemistry student explains that she represents a mechanistic step because ''it's a productive part of the mechanism,'' what meaning could the professor teaching the class attribute to this statement, what is actually communicated, and what does it mean for the student? The professor might think that the explanation is based on…

Pose-Invariant Face Recognition via RGB-D Images.

PubMed

Sang, Gaoli; Li, Jing; Zhao, Qijun

2016-01-01

Three-dimensional (3D) face models can intrinsically handle large pose face recognition problem. In this paper, we propose a novel pose-invariant face recognition method via RGB-D images. By employing depth, our method is able to handle self-occlusion and deformation, both of which are challenging problems in two-dimensional (2D) face recognition. Texture images in the gallery can be rendered to the same view as the probe via depth. Meanwhile, depth is also used for similarity measure via frontalization and symmetric filling. Finally, both texture and depth contribute to the final identity estimation. Experiments on Bosphorus, CurtinFaces, Eurecom, and Kiwi databases demonstrate that the additional depth information has improved the performance of face recognition with large pose variations and under even more challenging conditions.

Ethnicity identification from face images

NASA Astrophysics Data System (ADS)

Lu, Xiaoguang; Jain, Anil K.

2004-08-01

Human facial images provide the demographic information, such as ethnicity and gender. Conversely, ethnicity and gender also play an important role in face-related applications. Image-based ethnicity identification problem is addressed in a machine learning framework. The Linear Discriminant Analysis (LDA) based scheme is presented for the two-class (Asian vs. non-Asian) ethnicity classification task. Multiscale analysis is applied to the input facial images. An ensemble framework, which integrates the LDA analysis for the input face images at different scales, is proposed to further improve the classification performance. The product rule is used as the combination strategy in the ensemble. Experimental results based on a face database containing 263 subjects (2,630 face images, with equal balance between the two classes) are promising, indicating that LDA and the proposed ensemble framework have sufficient discriminative power for the ethnicity classification problem. The normalized ethnicity classification scores can be helpful in the facial identity recognition. Useful as a "soft" biometric, face matching scores can be updated based on the output of ethnicity classification module. In other words, ethnicity classifier does not have to be perfect to be useful in practice.

Frequency dependent steering with backward leaky waves via photonic crystal interface layer.

PubMed

Colak, Evrim; Caglayan, Humeyra; Cakmak, Atilla O; Villa, Alessandro D; Capolino, Filippo; Ozbay, Ekmel

2009-06-08

A Photonic Crystal (PC) with a surface defect layer (made of dimers) is studied in the microwave regime. The dispersion diagram is obtained with the Plane Wave Expansion Method. The dispersion diagram reveals that the dimer-layer supports a surface mode with negative slope. Two facts are noted: First, a guided (bounded) wave is present, propagating along the surface of the dimer-layer. Second, above the light line, the fast traveling mode couple to the propagating spectra and as a result a directive (narrow beam) radiation with backward characteristics is observed and measured. In this leaky mode regime, symmetrical radiation patterns with respect to the normal to the PC surface are attained. Beam steering is observed and measured in a 70 degrees angular range when frequency ranges in the 11.88-13.69 GHz interval. Thus, a PC based surface wave structure that acts as a frequency dependent leaky wave antenna is presented. Angular radiation pattern measurements are in agreement with those obtained via numerical simulations that employ the Finite Difference Time Domain Method (FDTD). Finally, the backward radiation characteristics that in turn suggest the existence of a backward leaky mode in the dimer-layer are experimentally verified using a halved dimer-layer structure.

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…

Preparation for Compensatory Forward Stepping in Parkinson’s Disease

PubMed Central

King, Laurie A.; St George, Rebecca J.; Carlson-Kuhta, Patricia; Nutt, John G.; Horak, Fay B.

2010-01-01

Objective To characterize preparation for compensatory stepping in people with Parkinson’s disease (PD) compared with healthy control subjects, and to determine whether levodopa medication improves preparation or the execution phases of the step. Design Observational study. Setting Outpatient neuroscience laboratory. Participants Nineteen participants with idiopathic PD tested both in the on and off levodopa states and 17 healthy subjects. Intervention Moveable platform with posterior translations of 24cm at 56cm/s. Main Outcome Measures Compensatory steps forward, in response to a backward surface translation (24cm amplitude at 56cm/s), were categorized according to the presence of an anticipatory postural adjustment (APA) before stepping: no APA, single APA, or multiple APAs. The following step parameters were calculated: step latency, step length, center of mass (CoM) average velocity, and CoM displacement at the step initiation. Results Lateral APAs were evident in 57% and 42% of trials for people with PD in the off and on medication states, respectively, compared with only 10% of trials for control subjects. Compared with subjects with PD who did not have APAs, those subjects with PD who did make an APA prior to stepping had significantly later (mean ± SEM, 356 ± 16ms vs 305 ± 8ms) and shorter (mean ± SEM, 251 ± 27mm vs 300 ± 16mm) steps, their CoM was significantly farther forward (185 ± 7mm vs 171 ± 5mm) at foot-off, and they took significantly more steps to regain equilibrium. Levodopa did not affect the preparation or execution phase of compensatory stepping. Poor axial scores and reports of freezing in the United Parkinson’s Disease Rating Scale were associated with use of 1 or more APAs before compensatory stepping. Conclusions Lateral postural preparation prior to compensatory stepping in subjects with PD was associated with inefficient balance recovery from external perturbations. PMID:20801249

Linear response theory and transient fluctuation relations for diffusion processes: a backward point of view

NASA Astrophysics Data System (ADS)

Liu, Fei; Tong, Huan; Ma, Rui; Ou-Yang, Zhong-can

2010-12-01

A formal apparatus is developed to unify derivations of the linear response theory and a variety of transient fluctuation relations for continuous diffusion processes from a backward point of view. The basis is a perturbed Kolmogorov backward equation and the path integral representation of its solution. We find that these exact transient relations could be interpreted as a consequence of a generalized Chapman-Kolmogorov equation, which intrinsically arises from the Markovian characteristic of diffusion processes.

Photocopy of print (original sepia print is backward and in ...

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

Photocopy of print (original sepia print is backward and in possession of MacDill Air Force Base, Civil Engineering, Tampa, Florida; 1953 architectural drawings by Horowick & Lee, Architects, Jacksonville, Florida) EXTERIOR ELEVATIONS - MacDill Air Force Base, Photography Laboratory, 2617 Florida Keys Avenue, Tampa, Hillsborough County, FL

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.

Coaching Family Caregivers to become Better Problem Solvers when Caring for Persons with Advanced Cancer

PubMed Central

Dionne-Odom, J. Nicholas; Lyons, Kathleen D.; Akyar, Imatullah; Bakitas, Marie

2016-01-01

Family caregivers of persons with advanced cancer often take on responsibilities that present daunting and complex problems. Serious problems that go unresolved may be burdensome and result in negative outcomes for caregivers’ psychological and physical health and affect the quality of care delivered to the care recipients with cancer, especially at the end of life. Formal problem-solving training approaches have been developed over the past several decades to assist individuals with managing problems faced in daily life. Several of these problem-solving principles and techniques were incorporated into ENABLE (Educate, Nurture, Advise, Before Life End), an ‘early’ palliative care telehealth intervention for individuals diagnosed with advanced cancer and their family caregivers. A hypothetical case resembling the situations of actual caregiver participants in ENABLE that exemplifies the complex problems that caregivers face is presented followed by presentation of an overview of ENABLE’s problem-solving key principles, techniques and steps in problem-solving support. Though more research is needed to formally test the use of problem-solving support in social work practice, social workers can easily incorporate these techniques into everyday practice. PMID:27143574

Single-molecule fluorescence reveals the unwinding stepping mechanism of replicative helicase.

PubMed

Syed, Salman; Pandey, Manjula; Patel, Smita S; Ha, Taekjip

2014-03-27

Bacteriophage T7 gp4 serves as a model protein for replicative helicases that couples deoxythymidine triphosphate (dTTP) hydrolysis to directional movement and DNA strand separation. We employed single-molecule fluorescence resonance energy transfer methods to resolve steps during DNA unwinding by T7 helicase. We confirm that the unwinding rate of T7 helicase decreases with increasing base pair stability. For duplexes containing >35% guanine-cytosine (GC) base pairs, we observed stochastic pauses every 2-3 bp during unwinding. The dwells on each pause were distributed nonexponentially, consistent with two or three rounds of dTTP hydrolysis before each unwinding step. Moreover, we observed backward movements of the enzyme on GC-rich DNAs at low dTTP concentrations. Our data suggest a coupling ratio of 1:1 between base pairs unwound and dTTP hydrolysis, and they further support the concept that nucleic acid motors can have a hierarchy of different-sized steps or can accumulate elastic energy before transitioning to a subsequent phase. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Backward- and forward-looking responsibility for obesity: policies from WHO, the EU and England.

PubMed

Vallgårda, Signild; Nielsen, Morten Ebbe Juul; Hartlev, Mette; Sandøe, Peter

2015-10-01

In assigning responsibility for obesity prevention a distinction may be drawn between who is responsible for the rise in obesity prevalence ('backward-looking responsibility'), and who is responsible for reducing it ('forward-looking responsibility'). We study how the two aspects of responsibility figure in the obesity policies of WHO (European Region), the EU and the Department of Health (England). Responsibility for the emergence and reduction of obesity is assigned to both individuals and other actors to different degrees in the policies, combining an individual and a systemic view. The policies assign backward-looking responsibility to individuals, the social environment, the authorities and businesses. When it comes to forward-looking responsibility, individuals are expected to play a central role in reducing and preventing obesity, but other actors are also urged to act. WHO assigns to individuals the lowest degree of backward- and forward-looking responsibility, and the Department of Health (England) assigns them the highest degree of responsibility. Differences in the assignment of backward- and above all forward-looking responsibility could be explained to some extent by the different roles of the three authorities making the plans. WHO is a UN agency with health as its goal, the EU is a liberal economic union with optimization of the internal European market as an important task, and England, as an independent sovereign country, has its own economic responsibilities. © The Author 2015. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

Incompressible Navier-Stokes Computations with Heat Transfer

NASA Technical Reports Server (NTRS)

Kiris, Cetin; Kwak, Dochan; Rogers, Stuart; Kutler, Paul (Technical Monitor)

1994-01-01

The existing pseudocompressibility method for the system of incompressible Navier-Stokes equations is extended to heat transfer problems by including the energy equation. The solution method is based on the pseudo compressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel line relaxation method. Current computations use one-equation Baldwin-Barth turbulence model which is derived from a simplified form of the standard k-epsilon model equations. Both forced and natural convection problems are examined. Numerical results from turbulent reattaching flow behind a backward-facing step will be compared against experimental measurements for the forced convection case. The validity of Boussinesq approximation to simplify the buoyancy force term will be investigated. The natural convective flow structure generated by heat transfer in a vertical rectangular cavity will be studied. The numerical results will be compared by experimental measurements by Morrison and Tran.

Beyond nonlinear saturation of backward Raman amplifiers

DOE PAGES

Barth, Ido; Toroker, Zeev; Balakin, Alexey A.; ...

2016-06-27

Backward Raman amplification is limited by relativistic nonlinear dephasing resulting in saturation of the leading spike of the amplified pulse. We employed pump detuning in order to mitigate the relativistic phase mismatch and to overcome the associated saturation. In an amplified pulse can then be reshaped into a monospike pulse with little precursory power ahead of it, with the maximum intensity increasing by a factor of two. Finally, this detuning can be employed advantageously both in regimes where the group velocity dispersion is unimportant and where the dispersion is important but small.

Beyond nonlinear saturation of backward Raman amplifiers

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

Barth, Ido; Toroker, Zeev; Balakin, Alexey A.

Backward Raman amplification is limited by relativistic nonlinear dephasing resulting in saturation of the leading spike of the amplified pulse. We employed pump detuning in order to mitigate the relativistic phase mismatch and to overcome the associated saturation. In an amplified pulse can then be reshaped into a monospike pulse with little precursory power ahead of it, with the maximum intensity increasing by a factor of two. Finally, this detuning can be employed advantageously both in regimes where the group velocity dispersion is unimportant and where the dispersion is important but small.

Photocopy of print (original sepia print is backward and in ...

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

Photocopy of print (original sepia print is backward and in possession of MacDill Air Force Base, Civil Engineering, Tampa, Florida; 1953 architectural drawings by Horowick & Lee, Architects, Jacksonville, Florida) FLOOR PLAN AND SCHEDULES - MacDill Air Force Base, Photography Laboratory, 2617 Florida Keys Avenue, Tampa, Hillsborough County, FL

The compression and expansion waves of the forward and backward flows: an in-vitro arterial model.

PubMed

Feng, J; Khir, A W

2008-05-01

Although the propagation of arterial waves of forward flows has been studied before, that of backward flows has not been thoroughly investigated. The aim of this research is to investigate the propagation of the compression and expansion waves of backward flows in terms of wave speed and dissipation, in flexible tubes. The aim is also to compare the propagation of these waves with those of forward flows. A piston pump generated a flow waveform in the shape of approximately half-sinusoid, in flexible tubes (12 mm and 16 mm diameter). The pump produced flow in either the forward or the backward direction by moving the piston forward, in a 'pushing action' or backward, in a 'pulling action', using a graphite brushes d.c. motor. Pressure and flow were measured at intervals of 5 cm along each tube and wave speed was determined using the PU-loop method. The simultaneous measurements of diameter were also taken at the same position of the pressure and flow in the 16 mm tube. Wave intensity analysis was used to determine the magnitude of the pressure and velocity waveforms and wave intensity in the forward and backward directions. Under the same initial experimental conditions, wave speed was higher during the pulling action (backward flow) than during the pushing action (forward flow). The amplitudes of pressure and velocity in the pulling action were significantly higher than those in the pushing action. The tube diameter was approximately 20 per cent smaller in the pulling action than in the pushing action in the 16 mm tube. The compression and expansion waves resulting from the pushing and pulling actions dissipated exponentially along the travelling distance, and their dissipation was greater in the smaller than in the larger tubes. Local wave speed in flexible tubes is flow direction- and wave nature-dependent and is greater with expansion than with compression waves. Wave dissipation has an inverse relationship with the vessel diameter, and dissipation of the

Preventing fall-related vertebral fractures: effect of floor stiffness on peak impact forces during backward falls.

PubMed

Sran, Meena M; Robinovitch, Stephen N

2008-08-01

In vivo biomechanical study of 11 male volunteers. To measure the peak forces applied to the buttocks in a backward fall from standing, and to determine whether this force is lowered by reductions in floor stiffness. Fall-related vertebral fractures are common and backward falls result in impact to the buttocks. Compliant flooring may reduce impact force and risk for vertebral fracture during a fall. However, we have little knowledge of the peak forces applied to the body during a backward fall, or how floor stiffness affects this force. Eleven males, mean age 25 +/- 5 (SD) years, were suddenly released from a backward lean of 15 degrees , falling backward onto the ground which was covered with 4.5, 7.5, or 10.5 cm of ethylene vinyl acetate foam rubber. We measured 3-dimensional impact forces applied to the buttocks at 960 Hz with a force plate. We used repeated measures analysis of variance and post hoc t tests to compare peak forces between conditions. We also modeled peak vertical force for falls onto a bare floor. RESULTS.: There was a significant difference in peak vertical force between falls onto the 10.5 cm foam condition compared with the 7.5 cm (P = 0.002) and 4.5 cm (P < 0.001) conditions. Peak vertical force (N) was (mean +/- SD) 5099 +/- 868, 4788 +/- 702, and 4544 +/- 672 for the 4.5, 7.5, and 10.5 cm foam conditions, respectively, and estimated at 6027 +/- 988 for the rigid (bare floor) condition. Compared with the bare floor, these foam floors provided, on average, 24, 20, and 15% force attenuation respectively. In a backward fall onto the buttocks, peak impact forces are 6.4 to 9.0 times body weight in a fall onto a bare floor. Reducing floor stiffness using even a thin (4.5 cm) layer of foam may provide 15% vertical force attenuation during a fall onto the buttocks.

Measurement and visualization of face-to-face interaction among community-dwelling older adults using wearable sensors.

PubMed

Masumoto, Kouhei; Yaguchi, Takaharu; Matsuda, Hiroshi; Tani, Hideaki; Tozuka, Keisuke; Kondo, Narihiko; Okada, Shuichi

2017-10-01

A number of interventions have been undertaken to develop and promote social networks among community-dwelling older adults. However, it has been difficult to examine the effects of these interventions, because of problems in assessing interactions. The present study was designed to quantitatively measure and visualize face-to-face interactions among elderly participants in an exercise program. We also examined relationships among interactional variables, personality and interest in community involvement, including interactions with the local community. Older adults living in the same community were recruited to participate in an exercise program that consisted of four sessions. We collected data on face-to-face interactions of the participants by using a wearable sensor technology device. Network analysis identified the communication networks of participants in the exercise program, as well as changes in these networks. Additionally, there were significant correlations between the number of people involved in face-to-face interactions and changes in both interest in community involvement and interactions with local community residents, as well as personality traits, including agreeableness. Social networks in the community are essential for solving problems caused by the aging society. We showed the possible applications of face-to-face interactional data for identifying core participants having many interactions, and isolated participants having only a few interactions within the community. Such data would be useful for carrying out efficient interventions for increasing participants' involvement with their community. Geriatr Gerontol Int 2017; 17: 1752-1758. © 2017 Japan Geriatrics Society.

Control Software for Piezo Stepping Actuators

NASA Technical Reports Server (NTRS)

Shields, Joel F.

2013-01-01

A control system has been developed for the Space Interferometer Mission (SIM) piezo stepping actuator. Piezo stepping actuators are novel because they offer extreme dynamic range (centimeter stroke with nanometer resolution) with power, thermal, mass, and volume advantages over existing motorized actuation technology. These advantages come with the added benefit of greatly reduced complexity in the support electronics. The piezo stepping actuator consists of three fully redundant sets of piezoelectric transducers (PZTs), two sets of brake PZTs, and one set of extension PZTs. These PZTs are used to grasp and move a runner attached to the optic to be moved. By proper cycling of the two brake and extension PZTs, both forward and backward moves of the runner can be achieved. Each brake can be configured for either a power-on or power-off state. For SIM, the brakes and gate of the mechanism are configured in such a manner that, at the end of the step, the actuator is in a parked or power-off state. The control software uses asynchronous sampling of an optical encoder to monitor the position of the runner. These samples are timed to coincide with the end of the previous move, which may consist of a variable number of steps. This sampling technique linearizes the device by avoiding input saturation of the actuator and makes latencies of the plant vanish. The software also estimates, in real time, the scale factor of the device and a disturbance caused by cycling of the brakes. These estimates are used to actively cancel the brake disturbance. The control system also includes feedback and feedforward elements that regulate the position of the runner to a given reference position. Convergence time for smalland medium-sized reference positions (less than 200 microns) to within 10 nanometers can be achieved in under 10 seconds. Convergence times for large moves (greater than 1 millimeter) are limited by the step rate.

Spatial-Sequential Working Memory in Younger and Older Adults: Age Predicts Backward Recall Performance within Both Age Groups

PubMed Central

Brown, Louise A.

2016-01-01

Working memory is vulnerable to age-related decline, but there is debate regarding the age-sensitivity of different forms of spatial-sequential working memory task, depending on their passive or active nature. The functional architecture of spatial working memory was therefore explored in younger (18–40 years) and older (64–85 years) adults, using passive and active recall tasks. Spatial working memory was assessed using a modified version of the Spatial Span subtest of the Wechsler Memory Scale – Third Edition (WMS-III; Wechsler, 1998). Across both age groups, the effects of interference (control, visual, or spatial), and recall type (forward and backward), were investigated. There was a clear effect of age group, with younger adults demonstrating a larger spatial working memory capacity than the older adults overall. There was also a specific effect of interference, with the spatial interference task (spatial tapping) reliably reducing performance relative to both the control and visual interference (dynamic visual noise) conditions in both age groups and both recall types. This suggests that younger and older adults have similar dependence upon active spatial rehearsal, and that both forward and backward recall require this processing capacity. Linear regression analyses were then carried out within each age group, to assess the predictors of performance in each recall format (forward and backward). Specifically the backward recall task was significantly predicted by age, within both the younger and older adult groups. This finding supports previous literature showing lifespan linear declines in spatial-sequential working memory, and in working memory tasks from other domains, but contrasts with previous evidence that backward spatial span is no more sensitive to aging than forward span. The study suggests that backward spatial span is indeed more processing-intensive than forward span, even when both tasks include a retention period, and that age predicts

Spatial-Sequential Working Memory in Younger and Older Adults: Age Predicts Backward Recall Performance within Both Age Groups.

PubMed

Brown, Louise A

2016-01-01

Working memory is vulnerable to age-related decline, but there is debate regarding the age-sensitivity of different forms of spatial-sequential working memory task, depending on their passive or active nature. The functional architecture of spatial working memory was therefore explored in younger (18-40 years) and older (64-85 years) adults, using passive and active recall tasks. Spatial working memory was assessed using a modified version of the Spatial Span subtest of the Wechsler Memory Scale - Third Edition (WMS-III; Wechsler, 1998). Across both age groups, the effects of interference (control, visual, or spatial), and recall type (forward and backward), were investigated. There was a clear effect of age group, with younger adults demonstrating a larger spatial working memory capacity than the older adults overall. There was also a specific effect of interference, with the spatial interference task (spatial tapping) reliably reducing performance relative to both the control and visual interference (dynamic visual noise) conditions in both age groups and both recall types. This suggests that younger and older adults have similar dependence upon active spatial rehearsal, and that both forward and backward recall require this processing capacity. Linear regression analyses were then carried out within each age group, to assess the predictors of performance in each recall format (forward and backward). Specifically the backward recall task was significantly predicted by age, within both the younger and older adult groups. This finding supports previous literature showing lifespan linear declines in spatial-sequential working memory, and in working memory tasks from other domains, but contrasts with previous evidence that backward spatial span is no more sensitive to aging than forward span. The study suggests that backward spatial span is indeed more processing-intensive than forward span, even when both tasks include a retention period, and that age predicts

Education Reform: A Step Forward or a Step Backward for Students with Learning Disabilities. Proceedings of a Symposium (Atlanta, Georgia, March 7-8, 1992).

ERIC Educational Resources Information Center

Learning Disabilities Association of America, Pittsburgh, PA.

This proceedings document includes 11 papers presented at a 1992 symposium on the impact of current educational reform initiatives on students with learning disabilities. Preceding the papers is a summary of the outcomes of the symposium, which are enumerated in terms of questions generated, commonalities, unresolved topics, and next steps. Papers…

A smart technique for attendance system to recognize faces through parallelism

NASA Astrophysics Data System (ADS)

Prabhavathi, B.; Tanuja, V.; Madhu Viswanatham, V.; Rajashekhara Babu, M.

2017-11-01

Major part of recognising a person is face with the help of image processing techniques we can exploit the physical features of a person. In the old approach method that is used in schools and colleges it is there that the professor calls the student name and then the attendance for the students marked. Here in paper want to deviate from the old approach and go with the new approach by using techniques that are there in image processing. In this paper we presenting spontaneous presence for students in classroom. At first classroom image has been in use and after that image is kept in data record. For the images that are stored in the database we apply system algorithm which includes steps such as, histogram classification, noise removal, face detection and face recognition methods. So by using these steps we detect the faces and then compare it with the database. The attendance gets marked automatically if the system recognizes the faces.

Gate-Tunable WSe2/SnSe2 Backward Diode with Ultrahigh-Reverse Rectification Ratio.

PubMed

Murali, Krishna; Dandu, Medha; Das, Sarthak; Majumdar, Kausik

2018-02-14

Backward diodes conduct more efficiently in the reverse bias than in the forward bias, providing superior high-frequency response, temperature stability, radiation hardness, and 1/f noise performance than a conventional diode conducting in the forward direction. Here, we demonstrate a van der Waals material-based backward diode by exploiting the giant staggered band offsets of WSe 2 /SnSe 2 vertical heterojunction. The diode exhibits an ultrahigh-reverse rectification ratio (R) of ∼2.1 × 10 4 , and the same is maintained up to an unusually large bias of 1.5 V-outperforming existing backward diode reports using conventional bulk semiconductors as well as one- and two-dimensional materials by more than an order of magnitude while maintaining an impressive curvature coefficient (γ) of ∼37 V -1 . The transport mechanism in the diode is shown to be efficiently tunable by external gate and drain bias, as well as by the thickness of the WSe 2 layer and the type of metal contacts used. These results pave the way for practical electronic circuit applications using two-dimensional materials and their heterojunctions.

New Developments of Computational Fluid Dynamics and Their Applications to Practical Engineering Problems

NASA Astrophysics Data System (ADS)

Chen, Hudong

2001-06-01

There have been considerable advances in Lattice Boltzmann (LB) based methods in the last decade. By now, the fundamental concept of using the approach as an alternative tool for computational fluid dynamics (CFD) has been substantially appreciated and validated in mainstream scientific research and in industrial engineering communities. Lattice Boltzmann based methods possess several major advantages: a) less numerical dissipation due to the linear Lagrange type advection operator in the Boltzmann equation; b) local dynamic interactions suitable for highly parallel processing; c) physical handling of boundary conditions for complicated geometries and accurate control of fluxes; d) microscopically consistent modeling of thermodynamics and of interface properties in complex multiphase flows. It provides a great opportunity to apply the method to practical engineering problems encountered in a wide range of industries from automotive, aerospace to chemical, biomedical, petroleum, nuclear, and others. One of the key challenges is to extend the applicability of this alternative approach to regimes of highly turbulent flows commonly encountered in practical engineering situations involving high Reynolds numbers. Over the past ten years, significant efforts have been made on this front at Exa Corporation in developing a lattice Boltzmann based commercial CFD software, PowerFLOW. It has become a useful computational tool for the simulation of turbulent aerodynamics in practical engineering problems involving extremely complex geometries and flow situations, such as in new automotive vehicle designs world wide. In this talk, we present an overall LB based algorithm concept along with certain key extensions in order to accurately handle turbulent flows involving extremely complex geometries. To demonstrate the accuracy of turbulent flow simulations, we provide a set of validation results for some well known academic benchmarks. These include straight channels, backward-facing

Powerlessness Reinterpreted: Reframing Step One.

ERIC Educational Resources Information Center

Young, Susan L.

The 12 steps of the well-known mutual help group, Alcoholics Anonymous (AA), begin with Step One, admitting powerlessness. Although Step One has helped many problem drinkers and other addicts, its spiritual concepts have been criticized. The possibility of reconceptualizing powerlessness as empowering, not only within AA and its offshoot programs,…

Deep learning and face recognition: the state of the art

NASA Astrophysics Data System (ADS)

Balaban, Stephen

2015-05-01

Deep Neural Networks (DNNs) have established themselves as a dominant technique in machine learning. DNNs have been top performers on a wide variety of tasks including image classification, speech recognition, and face recognition.1-3 Convolutional neural networks (CNNs) have been used in nearly all of the top performing methods on the Labeled Faces in the Wild (LFW) dataset.3-6 In this talk and accompanying paper, I attempt to provide a review and summary of the deep learning techniques used in the state-of-the-art. In addition, I highlight the need for both larger and more challenging public datasets to benchmark these systems. Despite the ability of DNNs and autoencoders to perform unsupervised feature learning, modern facial recognition pipelines still require domain specific engineering in the form of re-alignment. For example, in Facebook's recent DeepFace paper, a 3D "frontalization" step lies at the beginning of the pipeline. This step creates a 3D face model for the incoming image and then uses a series of affine transformations of the fiducial points to "frontalize" the image. This step enables the DeepFace system to use a neural network architecture with locally connected layers without weight sharing as opposed to standard convolutional layers.6 Deep learning techniques combined with large datasets have allowed research groups to surpass human level performance on the LFW dataset.3, 5 The high accuracy (99.63% for FaceNet at the time of publishing) and utilization of outside data (hundreds of millions of images in the case of Google's FaceNet) suggest that current face verification benchmarks such as LFW may not be challenging enough, nor provide enough data, for current techniques.3, 5 There exist a variety of organizations with mobile photo sharing applications that would be capable of releasing a very large scale and highly diverse dataset of facial images captured on mobile devices. Such an "ImageNet for Face Recognition" would likely receive a warm

Superior Recognition Performance for Happy Masked and Unmasked Faces in Both Younger and Older Adults

PubMed Central

Svärd, Joakim; Wiens, Stefan; Fischer, Håkan

2012-01-01

In the aging literature it has been shown that even though emotion recognition performance decreases with age, the decrease is less for happiness than other facial expressions. Studies in younger adults have also revealed that happy faces are more strongly attended to and better recognized than other emotional facial expressions. Thus, there might be a more age independent happy face advantage in facial expression recognition. By using a backward masking paradigm and varying stimulus onset asynchronies (17–267 ms) the temporal development of a happy face advantage, on a continuum from low to high levels of visibility, was examined in younger and older adults. Results showed that across age groups, recognition performance for happy faces was better than for neutral and fearful faces at durations longer than 50 ms. Importantly, the results showed a happy face advantage already during early processing of emotional faces in both younger and older adults. This advantage is discussed in terms of processing of salient perceptual features and elaborative processing of the happy face. We also investigate the combined effect of age and neuroticism on emotional face processing. The rationale was previous findings of age-related differences in physiological arousal to emotional pictures and a relation between arousal and neuroticism. Across all durations, there was an interaction between age and neuroticism, showing that being high in neuroticism might be disadvantageous for younger, but not older adults’ emotion recognition performance during arousal enhancing tasks. These results indicate that there is a relation between aging, neuroticism, and performance, potentially related to physiological arousal. PMID:23226135

Cognitive function and walking velocity in people with dementia; a comparison of backward and forward walking.

PubMed

Johansson, Hanna; Lundin-Olsson, Lillemor; Littbrand, Håkan; Gustafson, Yngve; Rosendahl, Erik; Toots, Annika

2017-10-01

How forward and backward walking, both central to everyday life, relate to cognition are relatively unexplored in people with dementia. This study aimed to investigate if forward and backward walking velocity respectively, associated with global cognition and executive function in people with dementia, and whether the association differed according to walking aid use or dementia type. Using a cross-sectional design, 161 participants (77% women), a mean Mini-Mental State Examination (MMSE) score of 15, and mean age of 85.5years and living in nursing homes were included. Self-paced forward walking (FW) and backward walking (BW) velocity over 2.4m was measured. Global cognitive outcome measurements included MMSE and Alzheimer Disease Assessment Scale - Cognitive subscale (ADAS-Cog). Executive function was measured using Verbal Fluency (VF). In comprehensively adjusted multivariate linear regression analyses, FW was independently associated with VF (p=0.001), but not MMSE (p=0.126) or ADAS-Cog (p=0.818). BW was independently associated with VF (p=0.043) and MMSE (p=0.022), but not ADAS-Cog (p=0.519). Interaction analyses showed that the association between BW velocity and executive function were stronger in participants who walked without a walking aid. No associations differed according to dementia type. In conclusion, executive function appears important to walking velocity, both forward and backward, in people with dementia with mild to moderately severe cognitive impairment. Global cognitive function was associated with backward walking only, perhaps due to it being more challenging. The association between BW velocity and executive function differed according to use of walking aids, which appeared to attenuate the association. Copyright © 2017 Elsevier B.V. All rights reserved.

Nine wave-length THz spectrum for identification using backward wave oscillator

NASA Astrophysics Data System (ADS)

Lv, Mo; Zhong, Hua; Ge, Xin-hao; He, Ting; Mu, Kaijun; Zhang, Cun-lin

2009-11-01

The sensing of the explosive is very important for homeland security and defense. We present a nine-wavelength continuous wave (CW) Terahertz (THz) spectroscopy for identification of explosive compounds (2,4-DNT, RDX and TNT) using three Backward Wave Oscillator (BWO) sources, which emit radiations from 0.2 THz to 0.38THz, 0.18THz to 0.26THz and 0.6THz to 0.7THz, respectively. To identify the target materials, only the transmitted THz power through the explosive pellets are measured at the nine discrete wavelengths. A hole, which is the same size as these pellets, is used as references to normalize the transmitted THz power. The measured discrete spectra was successfully identified and classified by using self-organizing map (SOM). These results prove that the backward wave oscillator is a convenient and powerful solution in future development of a standoff THz sensing and identification unit.

Testing a stepped care model for binge-eating disorder: a two-step randomized controlled trial.

PubMed

Tasca, Giorgio A; Koszycki, Diana; Brugnera, Agostino; Chyurlia, Livia; Hammond, Nicole; Francis, Kylie; Ritchie, Kerri; Ivanova, Iryna; Proulx, Genevieve; Wilson, Brian; Beaulac, Julie; Bissada, Hany; Beasley, Erin; Mcquaid, Nancy; Grenon, Renee; Fortin-Langelier, Benjamin; Compare, Angelo; Balfour, Louise

2018-05-24

A stepped care approach involves patients first receiving low-intensity treatment followed by higher intensity treatment. This two-step randomized controlled trial investigated the efficacy of a sequential stepped care approach for the psychological treatment of binge-eating disorder (BED). In the first step, all participants with BED (n = 135) received unguided self-help (USH) based on a cognitive-behavioral therapy model. In the second step, participants who remained in the trial were randomized either to 16 weeks of group psychodynamic-interpersonal psychotherapy (GPIP) (n = 39) or to a no-treatment control condition (n = 46). Outcomes were assessed for USH in step 1, and then for step 2 up to 6-months post-treatment using multilevel regression slope discontinuity models. In the first step, USH resulted in large and statistically significant reductions in the frequency of binge eating. Statistically significant moderate to large reductions in eating disorder cognitions were also noted. In the second step, there was no difference in change in frequency of binge eating between GPIP and the control condition. Compared with controls, GPIP resulted in significant and large improvement in attachment avoidance and interpersonal problems. The findings indicated that a second step of a stepped care approach did not significantly reduce binge-eating symptoms beyond the effects of USH alone. The study provided some evidence for the second step potentially to reduce factors known to maintain binge eating in the long run, such as attachment avoidance and interpersonal problems.

Discrimination of face gender and expression under dual-task conditions.

PubMed

García-Gutiérrez, Ana; Aguado, Luis; Romero-Ferreiro, Verónica; Pérez-Moreno, Elisa

2017-02-01

In order to test whether expression and gender can be attended to simultaneously without a cost in accuracy four experiments were carried out using a dual gender-expression task with male and female faces showing different emotional expressions that were backward masked by emotionally neutral faces. In the dual-facial condition the participants had to report both the gender and the expression of the targets. In two control conditions the participant reported either the gender or the expression of the face and indicated whether a surrounding frame was continuous or discontinuous. In Experiments 1-3, with angry and happy targets, asymmetric interference was observed. Gender discrimination, but no expression discrimination, was impaired in the dual-facial condition compared to the corresponding control. This effect was obtained with a between-subjects design in Experiment 1, with a within-subjects design in Experiment 2, and with androgynous face masks in Experiment 3. In Experiments 4a and 4b different target combinations were tested. No decrement of performance in the dual-facial task was observed for either gender or expression discrimination with fearful-disgusted (Experiment 4a) or fearful-happy faces (Experiment 4b). We conclude that the ability to attend simultaneously to gender and expression cues without a decrement in performance depends on the specific combination of expressions to be differentiated between. Happy and angry expressions are usually directed at the perceiver and command preferential attention. Under conditions of restricted viewing such as those of the present study, discrimination of these expressions is prioritized leading to impaired discrimination of other facial properties such as gender.

Spinal motor outputs during step-to-step transitions of diverse human gaits.

PubMed

La Scaleia, Valentina; Ivanenko, Yuri P; Zelik, Karl E; Lacquaniti, Francesco

2014-01-01

Aspects of human motor control can be inferred from the coordination of muscles during movement. For instance, by combining multimuscle electromyographic (EMG) recordings with human neuroanatomy, it is possible to estimate alpha-motoneuron (MN) pool activations along the spinal cord. It has previously been shown that the spinal motor output fluctuates with the body's center-of-mass motion, with bursts of activity around foot-strike and foot lift-off during walking. However, it is not known whether these MN bursts are generalizable to other ambulation tasks, nor is it clear if the spatial locus of the activity (along the rostrocaudal axis of the spinal cord) is fixed or variable. Here we sought to address these questions by investigating the spatiotemporal characteristics of the spinal motor output during various tasks: walking forward, backward, tiptoe and uphill. We reconstructed spinal maps from 26 leg muscle EMGs, including some intrinsic foot muscles. We discovered that the various walking tasks shared qualitative similarities in their temporal spinal activation profiles, exhibiting peaks around foot-strike and foot-lift. However, we also observed differences in the segmental level and intensity of spinal activations, particularly following foot-strike. For example, forward level-ground walking exhibited a mean motor output roughly 2 times lower than the other gaits. Finally, we found that the reconstruction of the spinal motor output from multimuscle EMG recordings was relatively insensitive to the subset of muscles analyzed. In summary, our results suggested temporal similarities, but spatial differences in the segmental spinal motor outputs during the step-to-step transitions of disparate walking behaviors.

Startle modulation and explicit valence evaluations dissociate during backward fear conditioning.

PubMed

Luck, Camilla C; Lipp, Ottmar V

2017-05-01

Blink startle magnitude is linearly modulated by affect such that, relative to neutral stimuli, startle magnitude is inhibited during pleasant stimuli and potentiated during unpleasant stimuli. Andreatta, Mühlberger, Yarali, Gerber, and Pauli (2010), however, report a dissociation between startle modulation and explicit valence evaluations during backward conditioning, a procedure in which the unconditional stimulus precedes the conditional stimulus (CS). Relative to controls, startles elicited during the CS were inhibited, suggesting that the CS had acquired positive valence, but participants still evaluated the CS as unpleasant after the experiment. In Experiment 1, we aimed to replicate this dissociation using a trial-by-trial measure of CS valence to measure startle modulation and CS valence simultaneously during forward and backward differential fear conditioning. In Experiment 2, we examined whether early and late portions of the CS could acquire differential valence by presenting startle probes at early and late probe positions during the CS. In both experiments, the dissociation between startle modulation and explicit valence evaluations in backward conditioning replicated, with CS+ evaluated as less pleasant than CS-, but startles elicited during CS+ inhibited relative to CS-. In Experiment 2, we provide preliminary evidence that this inhibition was present early, but not late, during the CS+. The results replicate the dissociation between implicit and explicit CS valence reported by Andreatta et al. (2010) using a trial-by-trial measure of valence. We also provide preliminary evidence that this dissociation may occur because the implicit and explicit measures are recorded at different times during the CS presentation. © 2017 Society for Psychophysiological Research.

Universities Face Wide-Ranging Changes

ERIC Educational Resources Information Center

Krieger, James H.

1976-01-01

Discusses problems facing the research university, including declining enrollments and funds, fewer opportunities for graduates, and the complexity of research problems. Recommends making more efficient use of resources, improving communications with the broader public, and reducing economic and social barriers to obtaining a higher education.…

Can we match ultraviolet face images against their visible counterparts?

NASA Astrophysics Data System (ADS)

Narang, Neeru; Bourlai, Thirimachos; Hornak, Lawrence A.

2015-05-01

In law enforcement and security applications, the acquisition of face images is critical in producing key trace evidence for the successful identification of potential threats. However, face recognition (FR) for face images captured using different camera sensors, and under variable illumination conditions, and expressions is very challenging. In this paper, we investigate the advantages and limitations of the heterogeneous problem of matching ultra violet (from 100 nm to 400 nm in wavelength) or UV, face images against their visible (VIS) counterparts, when all face images are captured under controlled conditions. The contributions of our work are three-fold; (i) We used a camera sensor designed with the capability to acquire UV images at short-ranges, and generated a dual-band (VIS and UV) database that is composed of multiple, full frontal, face images of 50 subjects. Two sessions were collected that span over the period of 2 months. (ii) For each dataset, we determined which set of face image pre-processing algorithms are more suitable for face matching, and, finally, (iii) we determined which FR algorithm better matches cross-band face images, resulting in high rank-1 identification rates. Experimental results show that our cross spectral matching (the heterogeneous problem, where gallery and probe sets consist of face images acquired in different spectral bands) algorithms achieve sufficient identification performance. However, we also conclude that the problem under study, is very challenging, and it requires further investigation to address real-world law enforcement or military applications. To the best of our knowledge, this is first time in the open literature the problem of cross-spectral matching of UV against VIS band face images is being investigated.

Sparse Regression as a Sparse Eigenvalue Problem

NASA Technical Reports Server (NTRS)

Moghaddam, Baback; Gruber, Amit; Weiss, Yair; Avidan, Shai

2008-01-01

We extend the l0-norm "subspectral" algorithms for sparse-LDA [5] and sparse-PCA [6] to general quadratic costs such as MSE in linear (kernel) regression. The resulting "Sparse Least Squares" (SLS) problem is also NP-hard, by way of its equivalence to a rank-1 sparse eigenvalue problem (e.g., binary sparse-LDA [7]). Specifically, for a general quadratic cost we use a highly-efficient technique for direct eigenvalue computation using partitioned matrix inverses which leads to dramatic x103 speed-ups over standard eigenvalue decomposition. This increased efficiency mitigates the O(n4) scaling behaviour that up to now has limited the previous algorithms' utility for high-dimensional learning problems. Moreover, the new computation prioritizes the role of the less-myopic backward elimination stage which becomes more efficient than forward selection. Similarly, branch-and-bound search for Exact Sparse Least Squares (ESLS) also benefits from partitioned matrix inverse techniques. Our Greedy Sparse Least Squares (GSLS) generalizes Natarajan's algorithm [9] also known as Order-Recursive Matching Pursuit (ORMP). Specifically, the forward half of GSLS is exactly equivalent to ORMP but more efficient. By including the backward pass, which only doubles the computation, we can achieve lower MSE than ORMP. Experimental comparisons to the state-of-the-art LARS algorithm [3] show forward-GSLS is faster, more accurate and more flexible in terms of choice of regularization

On the influence of airfoil deviations on the aerodynamic performance of wind turbine rotors

NASA Astrophysics Data System (ADS)

Winstroth, J.; Seume, J. R.

2016-09-01

The manufacture of large wind turbine rotor blades is a difficult task that still involves a certain degree of manual labor. Due to the complexity, airfoil deviations between the design airfoils and the manufactured blade are certain to arise. Presently, the understanding of the impact of manufacturing uncertainties on the aerodynamic performance is still incomplete. The present work analyzes the influence of a series of airfoil deviations likely to occur during manufacturing by means of Computational Fluid Dynamics and the aeroelastic code FAST. The average power production of the NREL 5MW wind turbine is used to evaluate the different airfoil deviations. Analyzed deviations include: Mold tilt towards the leading and trailing edge, thick bond lines, thick bond lines with cantilever correction, backward facing steps and airfoil waviness. The most severe influences are observed for mold tilt towards the leading and thick bond lines. By applying the cantilever correction, the influence of thick bond lines is almost compensated. Airfoil waviness is very dependent on amplitude height and the location along the surface of the airfoil. Increased influence is observed for backward facing steps, once they are high enough to trigger boundary layer transition close to the leading edge.

A Near-Wall Reynolds-Stress Closure without Wall Normals

NASA Technical Reports Server (NTRS)

Yuan, S. P.; So, R. M. C.

1997-01-01

With the aid of near-wall asymptotic analysis and results of direct numerical simulation, a new near-wall Reynolds stress model (NNWRS) is formulated based on the SSG high-Reynolds-stress model with wall-independent near-wall corrections. Only one damping function is used for flows with a wide range of Reynolds numbers to ensure that the near-wall modifications diminish away from the walls. The model is able to reproduce complicated flow phenomena induced by complex geometry, such as flow recirculation, reattachment and boundary-layer redevelopment in backward-facing step flow and secondary flow in three-dimensional square duct flow. In simple flows, including fully developed channel/pipe flow, Couette flow and boundary-layer flow, the wall effects are dominant, and the NNWRS model predicts less degree of turbulent anisotropy in the near-wall region compared with a wall-dependent near-wall Reynolds Stress model (NWRS) developed by So and colleagues. The comparison of the predictions given by the two models rectifies the misconception that the overshooting of skin friction coefficient in backward-facing step flow prevalent in those near-wall, models with wall normal is caused by he use of wall normal.

Backward Response-Level Crosstalk in the Psychological Refractory Period Paradigm

ERIC Educational Resources Information Center

Miller, Jeff; Alderton, Mark

2006-01-01

Bottleneck models of psychological refractory period (PRP) tasks suggest that a Task 1 response should be unaffected by the Task 2 response in the same trial, because selection of the former finishes before selection of the latter begins. Contrary to this conception, the authors found backward response-level crosstalk effects in which Task 2…

Calculating work in weakly driven quantum master equations: Backward and forward equations

NASA Astrophysics Data System (ADS)

Liu, Fei

2016-01-01

I present a technical report indicating that the two methods used for calculating characteristic functions for the work distribution in weakly driven quantum master equations are equivalent. One involves applying the notion of quantum jump trajectory [Phys. Rev. E 89, 042122 (2014), 10.1103/PhysRevE.89.042122], while the other is based on two energy measurements on the combined system and reservoir [Silaev et al., Phys. Rev. E 90, 022103 (2014), 10.1103/PhysRevE.90.022103]. These represent backward and forward methods, respectively, which adopt a very similar approach to that of the Kolmogorov backward and forward equations used in classical stochastic theory. The microscopic basis for the former method is also clarified. In addition, a previously unnoticed equality related to the heat is also revealed.

Forward-Backward Emission of Target Evaporated Fragments at High Energy Nucleus-Nucleus Collisions

NASA Astrophysics Data System (ADS)

Zhang, Zhi; Ma, Tian-Li; Zhang, Dong-Hai

The multiplicity distribution, multiplicity moments, scaled variance and entropy of target evaporated fragment emitted in forward and backward hemispheres in relativistic heavy ions induced emulsion heavy targets (AgBr) interactions are investigated. It is found that the multiplicity distribution can be fitted by the Gaussian distribution, and the fitting parameters are different between two hemispheres for all the interactions. The multiplicity moment increases with the order of the moment q, and second-order multiplicity moment is energy independent over the entire energy for all the interactions. The scaled variance is close to one for all the interactions. The entropy in forward hemisphere is greater than that in backward hemisphere for all the interactions.

Locating faces in color photographs using neural networks

NASA Astrophysics Data System (ADS)

Brown, Joe R.; Talley, Jim

1994-03-01

This paper summarizes a research effort in finding the locations and sizes of faces in color images (photographs, video stills, etc.) if, in fact, faces are presented. Scenarios for using such a system include serving as the means of localizing skin for automatic color balancing during photo processing or it could be used as a front-end in a customs port of energy context for a system which identified persona non grata given a database of known faces. The approach presented here is a hybrid system including: a neural pre-processor, some conventional image processing steps, and a neural classifier as the final face/non-face discriminator. Neither the training (containing 17,655 faces) nor the test (containing 1829 faces) imagery databases were constrained in their content or quality. The results for the pilot system are reported along with a discussion for improving the current system.

Application of the backward extrapolation method to pulsed neutron sources

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

Talamo, Alberto; Gohar, Yousry

We report particle detectors operated in pulse mode are subjected to the dead-time effect. When the average of the detector counts is constant over time, correcting for the dead-time effect is simple and can be accomplished by analytical formulas. However, when the average of the detector counts changes over time it is more difficult to take into account the dead-time effect. When a subcritical nuclear assembly is driven by a pulsed neutron source, simple analytical formulas cannot be applied to the measured detector counts to correct for the dead-time effect because of the sharp change of the detector counts overmore » time. This work addresses this issue by using the backward extrapolation method. The latter can be applied not only to a continuous (e.g. californium) external neutron source but also to a pulsed external neutron source (e.g. by a particle accelerator) driving a subcritical nuclear assembly. Finally, the backward extrapolation method allows to obtain from the measured detector counts both the dead-time value and the real detector counts.« less

Application of the backward extrapolation method to pulsed neutron sources

DOE PAGES

Talamo, Alberto; Gohar, Yousry

2017-09-23

We report particle detectors operated in pulse mode are subjected to the dead-time effect. When the average of the detector counts is constant over time, correcting for the dead-time effect is simple and can be accomplished by analytical formulas. However, when the average of the detector counts changes over time it is more difficult to take into account the dead-time effect. When a subcritical nuclear assembly is driven by a pulsed neutron source, simple analytical formulas cannot be applied to the measured detector counts to correct for the dead-time effect because of the sharp change of the detector counts overmore » time. This work addresses this issue by using the backward extrapolation method. The latter can be applied not only to a continuous (e.g. californium) external neutron source but also to a pulsed external neutron source (e.g. by a particle accelerator) driving a subcritical nuclear assembly. Finally, the backward extrapolation method allows to obtain from the measured detector counts both the dead-time value and the real detector counts.« less

Coupled forward-backward trajectory approach for nonequilibrium electron-ion dynamics

NASA Astrophysics Data System (ADS)

Sato, Shunsuke A.; Kelly, Aaron; Rubio, Angel

2018-04-01

We introduce a simple ansatz for the wave function of a many-body system based on coupled forward and backward propagating semiclassical trajectories. This method is primarily aimed at, but not limited to, treating nonequilibrium dynamics in electron-phonon systems. The time evolution of the system is obtained from the Euler-Lagrange variational principle, and we show that this ansatz yields Ehrenfest mean-field theory in the limit that the forward and backward trajectories are orthogonal, and in the limit that they coalesce. We investigate accuracy and performance of this method by simulating electronic relaxation in the spin-boson model and the Holstein model. Although this method involves only pairs of semiclassical trajectories, it shows a substantial improvement over mean-field theory, capturing quantum coherence of nuclear dynamics as well as electron-nuclear correlations. This improvement is particularly evident in nonadiabatic systems, where the accuracy of this coupled trajectory method extends well beyond the perturbative electron-phonon coupling regime. This approach thus provides an attractive route forward to the ab initio description of relaxation processes, such as thermalization, in condensed phase systems.

Memory for angry faces, impulsivity, and problematic behavior in adolescence.

PubMed

d'Acremont, Mathieu; Van der Linden, Martial

2007-04-01

Research has shown that cognitive processes like the attribution of hostile intention or angry emotion to others contribute to the development and maintenance of conduct problems. However, the role of memory has been understudied in comparison with attribution biases. The aim of this study was thus to test if a memory bias for angry faces was related to conduct problems in youth. Adolescents from a junior secondary school were presented with angry and happy faces and were later asked to recognize the same faces with a neutral expression. They also completed an impulsivity questionnaire. A teacher assessed their behavior. The results showed that a better recognition of angry faces than happy faces predicted conduct problems and hyperactivity/inattention as reported by the teacher. The memory bias effect was more pronounced for impulsive adolescents. It is suggested that a memory bias for angry faces favors disruptive behavior but that a good ability to control impulses may moderate the negative impact of this bias.

Assessing working memory in children with ADHD: Minor administration and scoring changes may improve digit span backward's construct validity.

PubMed

Wells, Erica L; Kofler, Michael J; Soto, Elia F; Schaefer, Hillary S; Sarver, Dustin E

2018-01-01

Pediatric ADHD is associated with impairments in working memory, but these deficits often go undetected when using clinic-based tests such as digit span backward. The current study pilot-tested minor administration/scoring modifications to improve digit span backward's construct and predictive validities in a well-characterized sample of children with ADHD. WISC-IV digit span was modified to administer all trials (i.e., ignore discontinue rule) and count digits rather than trials correct. Traditional and modified scores were compared to a battery of criterion working memory (construct validity) and academic achievement tests (predictive validity) for 34 children with ADHD ages 8-13 (M=10.41; 11 girls). Traditional digit span backward scores failed to predict working memory or KTEA-2 achievement (allns). Alternate administration/scoring of digit span backward significantly improved its associations with working memory reordering (r=.58), working memory dual-processing (r=.53), working memory updating (r=.28), and KTEA-2 achievement (r=.49). Consistent with prior work, these findings urge caution when interpreting digit span performance. Minor test modifications may address test validity concerns, and should be considered in future test revisions. Digit span backward becomes a valid measure of working memory at exactly the point that testing is traditionally discontinued. Copyright © 2017 Elsevier Ltd. All rights reserved.

Use of a cane for recovery from backward balance loss during treadmill walking.

PubMed

Hyodo, Masaki; Saito, Mayumi; Ushiba, Junichi; Tomita, Yutaka; Masakado, Yoshihisa

2013-06-01

To study whether a cane improved balance recovery after perturbation during walking. This study was a crossover comparison comparing the effect of walking with and without a cane for balance recovery after perturbation during treadmill walking. Five normal young volunteers participated. The velocity and acceleration of a marker sited on the seventh cerebral vertebra (C7) and vertical hand motion were measured by a motion analysis system. When using a cane, C7 backward velocity increased by approximately 15% (413 SD 95 mm/s with cane vs. 358 SD 88 mm/s without). In addition, C7 backward acceleration increased by approximately 23% (3.2 SD 0.7 m/s(2) with cane vs. 2.6 SD 0.8 m/s(2) without) and the vertical motion of the right hand decreased (187 SD 98 mm with cane vs. 372 SD 260 mm without). Additionally, no subject was able to use a cane to broaden their base of support. The ability to limit trunk extension is crucial for preventing falls. Therefore, using a cane jeopardizes recovery from backward balance loss. The results encourage further research on the risk of a cane on balance recovery for the elderly population and habitual cane users.

Isotropic Backward Waves Supported by a Spiral Array Metasurface.

PubMed

Tremain, Ben; Hooper, Ian R; Sambles, J Roy; Hibbins, Alastair P

2018-05-08

A planar metallic metasurface formed of spiral elements is shown to support an isotropic backward wave over a narrow band of microwave frequencies. The magnetic field of this left-handed mode is mapped experimentally using a near-field scanning technique, allowing the anti-parallel group and phase velocities to be directly visualised. The corresponding dispersion relation and isofrequency contours are obtained through Fourier transformation of the field images.

Kinematic and Kinetic Evaluation of High Speed Backward Running

DTIC Science & Technology

1999-06-30

Designed using Perform Pro , WHS/DIOR, Oct 94 KINEMATIC AND KINETIC EVALUATION OF HIGH SPEED BACKWARD RUNNING by ALAN WAYNE ARATA A DISSERTATION...Project Manager, Engineering Division, Kelly Air Force Base, Texas, 1983-86 AWARDS AND HONORS: All-American, 50yd Freestyle , 1979 Winner, Rocky...redirection #include <stdlib.h> // for exit #include <iomanip.h> // for set precision #include <string.h> // for string copy const int NUMPOINTS

Posture and movement characteristics of forward and backward walking in horses with shivering and acquired bilateral stringhalt.

PubMed

Draper, A C E; Trumble, T N; Firshman, A M; Baird, J D; Reed, S; Mayhew, I G; MacKay, R; Valberg, S J

2015-03-01

To investigate and further characterise posture and movement characteristics during forward and backward walking in horses with shivering and acquired, bilateral stringhalt. To characterise the movement of horses with shivering (also known as shivers) in comparison with control horses and horses with acquired bilateral stringhalt. Qualitative video analysis of gait in horses. Owners' and authors' videos of horses with shivering or stringhalt and control horses walking forwards and backwards and manually lifting their limbs were examined subjectively to characterise hyperflexion, hyperextension and postural abnormalities of the hindlimbs. The pattern and timing of vertical displacement of a hindlimb over one stride unit was evaluated among control, shivering and stringhalt cases. Gait patterns of shivering cases were characterised as follows: shivering-hyperextension (-HE, n = 13), in which horses subjectively showed hyperextension when backing and lifting the limb; shivering-hyperflexion (-HF, n = 27), in which horses showed hindlimb hyperflexion and abduction during backward walking; and shivering-forward hyperflexion (-FHF, n = 4), which resembled shivering-HF but included intermittent hyperflexion and abduction with forward walking. Horses with shivering-HF, shivering-FHF and stringhalt (n = 7) had a prolonged swing phase duration compared with control horses and horses with shivering-HE during backward walking. With the swing phase of forward walking, horses with stringhalt had a rapid ascent to adducted hyperflexion of the hindlimb, compared with a rapid descent of the hindlimb after abducted hyperflexion in horses with shivering-FHF. Shivering affects backward walking, with either HE or HF of hindlimbs, and can gradually progress to involve intermittent abducted hyperflexion during forward walking. Shivering-HF and shivering-FHF can look remarkably similar to acquired bilateral stringhalt during backward walking; however, stringhalt can be distinguished from

Detecting and Categorizing Fleeting Emotions in Faces

PubMed Central

Sweeny, Timothy D.; Suzuki, Satoru; Grabowecky, Marcia; Paller, Ken A.

2013-01-01

Expressions of emotion are often brief, providing only fleeting images from which to base important social judgments. We sought to characterize the sensitivity and mechanisms of emotion detection and expression categorization when exposure to faces is very brief, and to determine whether these processes dissociate. Observers viewed 2 backward-masked facial expressions in quick succession, 1 neutral and the other emotional (happy, fearful, or angry), in a 2-interval forced-choice task. On each trial, observers attempted to detect the emotional expression (emotion detection) and to classify the expression (expression categorization). Above-chance emotion detection was possible with extremely brief exposures of 10 ms and was most accurate for happy expressions. We compared categorization among expressions using a d′ analysis, and found that categorization was usually above chance for angry versus happy and fearful versus happy, but consistently poor for fearful versus angry expressions. Fearful versus angry categorization was poor even when only negative emotions (fearful, angry, or disgusted) were used, suggesting that this categorization is poor independent of decision context. Inverting faces impaired angry versus happy categorization, but not emotion detection, suggesting that information from facial features is used differently for emotion detection and expression categorizations. Emotion detection often occurred without expression categorization, and expression categorization sometimes occurred without emotion detection. These results are consistent with the notion that emotion detection and expression categorization involve separate mechanisms. PMID:22866885

Steps for arm and trunk actions of overhead forehand stroke used in badminton games across skill levels.

PubMed

Wang, Jianyu; Liu, Wenhao; Moffit, Jeffrey

2009-08-01

The purpose of this study was to examine arm and trunk actions in overhead forehand strokes used in badminton games across skill levels. The participants were 80 students (40 boys, 40 girls) who were randomly selected from video recordings of 300 students ages 16 to 19 years. The videotaped performances of overhead forehand strokes were coded based on three steps of arm action (elbow flexion, elbow and humeral flexion, and upward backswing) and three steps of trunk action (no trunk action, forward-backward movement, and trunk rotation). Students across the four skill levels exhibited different patterns of arm and trunk actions. Students at advanced levels used more mature arm and trunk actions.

Studying Turbulence Using Numerical Simulation Databases. Part 6; Proceedings of the 1996 Summer Program

NASA Technical Reports Server (NTRS)

1996-01-01

Topics considered include: New approach to turbulence modeling; Second moment closure analysis of the backstep flow database; Prediction of the backflow and recovery regions in the backward facing step at various Reynolds numbers; Turbulent flame propagation in partially premixed flames; Ensemble averaged dynamic modeling. Also included a study of the turbulence structures of wall-bounded shear flows; Simulation and modeling of the elliptic streamline flow.

Improvement of the Reynolds-stress model by a new pressure-strain correlation

NASA Technical Reports Server (NTRS)

Amano, Ryoichi S.; Chai, John C.

1988-01-01

A study is made to improve the predictions of Reynolds stresses in backward facing step flows, through modifications of the pressure-strain correlation. The mean-strain term of the pressure-strain correlation is formulated only in terms of nonisotropic turbulence in order to take the severe nonisotropic effect caused by a separating flow. This model is compared with other models and results are verified with experimental results.

Managing Problems Before Problems Manage You.

PubMed

Grigsby, Jim

2015-01-01

Every day we face problems, both personal and professional, and our initial reaction determines how well we solve those problems. Whether a problem is minor or major, short-term or lingering, there are techniques we can employ to help manage the problem and the problem-solving process. This article, based on my book Don't Tick Off The Gators! Managing Problems Before Problems Manage You, presents 12 different concepts for managing problems, not "cookie cutter" solutions, but different ideas that you can apply as they fit your circumstances.

Can use of walkers or canes impede lateral compensatory stepping movements?

PubMed

Bateni, Hamid; Heung, Evelyn; Zettel, John; McLlroy, William E; Maki, Brian E

2004-08-01

Although assistive devices, such as walkers and canes are often prescribed to aid in balance control, recent studies have suggested that such devices may actually increase risk of falling. In this study, we investigated one possible mechanism: the potential for walkers or canes to interfere with, or constrain, lateral movement of the feet and thereby impede execution of compensatory stepping reactions during lateral loss of balance. Lateral stepping reactions were evoked, in 10 healthy young adults (ages 22-27 years), by means of sudden unpredictable medio-lateral support surface translation. Subjects were tested while holding and loading a standard pickup walker or single-tip cane or while using no assistive device (hands free or holding an object). Results supported the hypothesis that using a walker or cane can interfere with compensatory stepping. Collisions between the swing-foot and mobility aid were remarkably frequent when using the walker (60% of stepping reactions) and also occurred in cane trials (11% of stepping reactions). Furthermore, such collisions were associated with a significant reduction (26-37%) in lateral step length. It appeared that subjects were sometimes able to avoid collision by increasing the forward or backward displacement of the swing-foot or by moving the cane; however, attempts to lift the walker out of the way occurred rarely and were usually impeded due to collision between the contralateral walker post and stance foot. The fact that compensatory stepping behavior was altered significantly in such a healthy cohort clearly demonstrates some of the safety limitations inherent to these assistive devices, as currently designed. Copyright 2003 Elsevier B.V.

Unusual energy properties of leaky backward Lamb waves in a submerged plate.

PubMed

Nedospasov, I A; Mozhaev, V G; Kuznetsova, I E

2017-05-01

It is found that leaky backward Lamb waves, i.e. waves with negative energy-flux velocity, propagating in a plate submerged in a liquid possess extraordinary energy properties distinguishing them from any other type of waves in isotropic media. Namely, the total time-averaged energy flux along the waveguide axis is equal to zero for these waves due to opposite directions of the longitudinal energy fluxes in the adjacent media. This property gives rise to the fundamental question of how to define and calculate correctly the energy velocity in such an unusual case. The procedure of calculation based on incomplete integration of the energy flux density over the plate thickness alone is applied. The derivative of the angular frequency with respect to the wave vector, usually referred to as the group velocity, happens to be close to the energy velocity defined by this mean in that part of the frequency range where the backward mode exists in the free plate. The existence region of the backward mode is formally increased for the submerged plate in comparison to the free plate as a result of the liquid-induced hybridization of propagating and nonpropagating (evanescent) Lamb modes. It is shown that the Rayleigh's principle (i.e. equipartition of total time-averaged kinetic and potential energies for time-harmonic acoustic fields) is violated due to the leakage of Lamb waves, in spite of considering nondissipative media. Copyright © 2017 Elsevier B.V. All rights reserved.

A problem-solving routine for improving hospital operations.

PubMed

Ghosh, Manimay; Sobek Ii, Durward K

2015-01-01

The purpose of this paper is to examine empirically why a systematic problem-solving routine can play an important role in the process improvement efforts of hospitals. Data on 18 process improvement cases were collected through semi-structured interviews, reports and other documents, and artifacts associated with the cases. The data were analyzed using a grounded theory approach. Adherence to all the steps of the problem-solving routine correlated to greater degrees of improvement across the sample. Analysis resulted in two models. The first partially explains why hospital workers tended to enact short-term solutions when faced with process-related problems; and tended not seek longer-term solutions that prevent problems from recurring. The second model highlights a set of self-reinforcing behaviors that are more likely to address problem recurrence and result in sustained process improvement. The study was conducted in one hospital setting. Hospital managers can improve patient care and increase operational efficiency by adopting and diffusing problem-solving routines that embody three key characteristics. This paper offers new insights on why caregivers adopt short-term approaches to problem solving. Three characteristics of an effective problem-solving routine in a healthcare setting are proposed.

Subject independent facial expression recognition with robust face detection using a convolutional neural network.

PubMed

Matsugu, Masakazu; Mori, Katsuhiko; Mitari, Yusuke; Kaneda, Yuji

2003-01-01

Reliable detection of ordinary facial expressions (e.g. smile) despite the variability among individuals as well as face appearance is an important step toward the realization of perceptual user interface with autonomous perception of persons. We describe a rule-based algorithm for robust facial expression recognition combined with robust face detection using a convolutional neural network. In this study, we address the problem of subject independence as well as translation, rotation, and scale invariance in the recognition of facial expression. The result shows reliable detection of smiles with recognition rate of 97.6% for 5600 still images of more than 10 subjects. The proposed algorithm demonstrated the ability to discriminate smiling from talking based on the saliency score obtained from voting visual cues. To the best of our knowledge, it is the first facial expression recognition model with the property of subject independence combined with robustness to variability in facial appearance.

The Academic, Administrative, Economic, Social, and Psychological Problems Faced by Students of Textile and Clothing Major at King Abdul-Aziz University

ERIC Educational Resources Information Center

Alsubyani, Noor Abdulhadi

2017-01-01

The purpose of this study is to investigate the academic, administrative, economic, social, and psychological problems faced by students of Textile and fabric major at King Abdul-Aziz University. To achieve this purpose, a questionnaire was designed and distributed to a sample of students in the Textile and fabric major, after the use of…

Facing the phase problem in Coherent Diffractive Imaging via Memetic Algorithms.

PubMed

Colombo, Alessandro; Galli, Davide Emilio; De Caro, Liberato; Scattarella, Francesco; Carlino, Elvio

2017-02-09

Coherent Diffractive Imaging is a lensless technique that allows imaging of matter at a spatial resolution not limited by lens aberrations. This technique exploits the measured diffraction pattern of a coherent beam scattered by periodic and non-periodic objects to retrieve spatial information. The diffracted intensity, for weak-scattering objects, is proportional to the modulus of the Fourier Transform of the object scattering function. Any phase information, needed to retrieve its scattering function, has to be retrieved by means of suitable algorithms. Here we present a new approach, based on a memetic algorithm, i.e. a hybrid genetic algorithm, to face the phase problem, which exploits the synergy of deterministic and stochastic optimization methods. The new approach has been tested on simulated data and applied to the phasing of transmission electron microscopy coherent electron diffraction data of a SrTiO 3 sample. We have been able to quantitatively retrieve the projected atomic potential, and also image the oxygen columns, which are not directly visible in the relevant high-resolution transmission electron microscopy images. Our approach proves to be a new powerful tool for the study of matter at atomic resolution and opens new perspectives in those applications in which effective phase retrieval is necessary.

Face liveness detection using shearlet-based feature descriptors

NASA Astrophysics Data System (ADS)

Feng, Litong; Po, Lai-Man; Li, Yuming; Yuan, Fang

2016-07-01

Face recognition is a widely used biometric technology due to its convenience but it is vulnerable to spoofing attacks made by nonreal faces such as photographs or videos of valid users. The antispoof problem must be well resolved before widely applying face recognition in our daily life. Face liveness detection is a core technology to make sure that the input face is a live person. However, this is still very challenging using conventional liveness detection approaches of texture analysis and motion detection. The aim of this paper is to propose a feature descriptor and an efficient framework that can be used to effectively deal with the face liveness detection problem. In this framework, new feature descriptors are defined using a multiscale directional transform (shearlet transform). Then, stacked autoencoders and a softmax classifier are concatenated to detect face liveness. We evaluated this approach using the CASIA Face antispoofing database and replay-attack database. The experimental results show that our approach performs better than the state-of-the-art techniques following the provided protocols of these databases, and it is possible to significantly enhance the security of the face recognition biometric system. In addition, the experimental results also demonstrate that this framework can be easily extended to classify different spoofing attacks.

[The application of operating room quality backward system in instrument place management].

PubMed

Du, Hui; He, Anjie; Zeng, Leilei

2010-09-01

Improvement of the surgery instrument's clean quality, the optimized preparation way, reasonable arrangement in groups, raising the working efficiency. We use the quality backward system into the instrument clean, the pack and the preparation way's question, carry on the analysis and the optimization, and appraise the effect after trying out 6 months. After finally the way optimized, instrument clean quality distinct enhancement; The flaws in the instrument clean, the pack way and the total operating time reduce; the contradictory between nurses and the cleans arising from the unclear connection reduces, the satisfaction degree of nurse and doctor to the instrument enhances. Using of operating room quality backward system in the management of the instrument clean, the pack and the preparation way optimized, may reduce flaws in the work and the waste of human resources, raise the working efficiency.

Screen Miniatures as Icons for Backward Navigation in Content-Based Software.

ERIC Educational Resources Information Center

Boling, Elizabeth; Ma, Guoping; Tao, Chia-Wen; Askun, Cengiz; Green, Tim; Frick, Theodore; Schaumburg, Heike

Users of content-based software programs, including hypertexts and instructional multimedia, rely on the navigation functions provided by the designers of those program. Typical navigation schemes use abstract symbols (arrows) to label basic navigational functions like moving forward or backward through screen displays. In a previous study, the…

Attitudes to face transplantation: results of a public engagement exercise at the Royal Society Summer Science Exhibition.

PubMed

Clarke, Alex; Simmons, Jon; White, Paul; Withey, Simon; Butler, Peter E M

2006-01-01

Hettiaratchy and Butler (Lancet 2002;360:5-6) framed face transplantation as the next logical step on the reconstructive ladder for severe facial injury, in particular, pan-facial burns. The procedure formed the basis for a Royal College of Surgeons of England working party report. Ethical, surgical, and psychological issues were identified as research priorities before face transplantation is attempted in the United Kingdom. Public engagement is a vital mechanism if people are to be informed about the risks and benefits of the technique and ultimately to be able to consent to either receiving or donating facial tissue. To sample public opinion about the procedure, 304 people attending the Royal Society Summer Science Exhibition were sampled by online questionnaire to determine their attitude toward face transplantation. Although people were more cautious about face transplantation when comparing this with solid-organ transplantation, most of the sample were in favor of the procedure, whether receiving a donor face or donating their own face after their death. Only 10% were against the idea in principle. Concerns about altered identity were not a barrier to face transplantation for 69% of the sample, with most people appropriately identifying the long-term problems of immunosuppression as the issue that most concerned them. There is a substantial population of people who, given the right circumstances, would contemplate face transplantation for themselves and would be willing to donate their own face for transplantation after their death.

Facing Life, English: 5113.30.

ERIC Educational Resources Information Center

Singleton, Clifford G.; Rice, M. Paul

The outline of a course in the investigation of literature (both fiction and nonfiction) which concerns youth facing and overcoming problems of life, with stress upon the novel and biography, is presented. The student is expected, through reading selected literary works, to (1) examine the problems confronted by youth, (2) examine youth's needs…

Tensor discriminant color space for face recognition.

PubMed